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Sample records for variable speed pumping

  1. Using Variable Speed Control on Pump Application

    Directory of Open Access Journals (Sweden)

    Dr.Sc. Aida Spahiu

    2012-06-01

    Full Text Available Pumps are one of the most common variable speed drive (VSD system applications and special interest has focused on improving their energy efficiency by using variable speed control instead of throttling or other less efficient flow control methods. Pumps are the single largest user of electricity in industry in the European Union, consuming 160 TWh per annum of electricity and accounting for 79 million tonnes of carbon dioxide (CO2 emissions [1]. Centrifugal pumps are the most likely pump style to provide a favorable return based on energy savings when applied with a variable speed drive. To help illustrate this, are conducted benchmark testing to document various head and flow scenarios and their corresponding effect on energy savings. Paper shows the relationship of static and friction head in the energy efficiency equation and the effect of motor, pump and VSD efficiencies. The received results are good reference points for engineers and managers of water sector in Albania to select the best prospects for maximizing efficiency and energy savings.

  2. Measure Guideline: Replacing Single-Speed Pool Pumps with Variable Speed Pumps for Energy Savings

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, A.; Easley, S.

    2012-05-01

    The report evaluates potential energy savings by replacing traditional single-speed pool pumps with variable speed pool pumps, and provide a basic cost comparison between continued uses of traditional pumps verses new pumps. A simple step-by-step process for inspecting the pool area and installing a new pool pump follows.

  3. Measure Guideline. Replacing Single-Speed Pool Pumps with Variable Speed Pumps for Energy Savings

    Energy Technology Data Exchange (ETDEWEB)

    Hunt, A. [Building Media and the Building America Retrofit Alliance (BARA), Wilmington, DE (United States); Easley, S. [Building Media and the Building America Retrofit Alliance (BARA), Wilmington, DE (United States)

    2012-05-01

    This measure guideline evaluates potential energy savings by replacing traditional single-speed pool pumps with variable speed pool pumps, and provides a basic cost comparison between continued uses of traditional pumps verses new pumps. A simple step-by-step process for inspecting the pool area and installing a new pool pump follows.

  4. Assessment of Japanese variable speed heat pump technology

    Energy Technology Data Exchange (ETDEWEB)

    Ushimaru, Kenji

    1988-01-01

    An analysis of critical component technologies and design methodologies for Japanese variable speed heat pumps are presented. The market for variable speed heat pumps in Japan is predominantly residential split-type, between the fractional to 2.5 ton capacity range. Approximately 1.1 million residential inverter-driven heat pumps were sold in 1987. Based on the market trends, component technology and several advanced features are described. Similarities and differences between Japanese and US system design methodologies are discussed. Finally, the outlook for future technology trends is briefly described. 8 refs., 6 figs., 1 tab.

  5. Modelling of Station of Pumping by Variable Speed

    Directory of Open Access Journals (Sweden)

    Benretem A.

    2016-05-01

    Full Text Available An increased energetic efficiency will make it possible to decrease the factory operating costs and hence to increase productivity. The centrifugal pumps are largely used because of their relatively simple operation and of their purchase price. One analyses thorough requirements imposed by the pumping plants is decisive. It is important to keep in mind the fact that the pumps consume approximately 20% of energy in the world. They constitute the possibility for the most significant efficiency improvement. They can reach their maximum effectiveness only with one pressure and a given flow. The approach suggested makes it possible to adapt with accuracy and effectiveness of system output of the industrial process requirements. The variable speed drive is one of best and effective techniques studied to reach this objective. The appearance of this technique comes only after the evolution obtained in the field of power electronics systems precisely static inverters as well as the efforts made by the researchers in the field of electric drive systems. This work suggested is the result of an in-depth study on the effectiveness of this new technique applied for the centrifugal pumps.

  6. Fixed-speed and Variable-speed Pumped Storage Dispatch Model in Power Systems with High Renewable Penetration

    Directory of Open Access Journals (Sweden)

    Yuan Bo

    2018-01-01

    Full Text Available According to different operating characteristics of pumped storage fixed speed unit and variable speed unit, a joint dispatching model of pumped storage unit and other types of units based on mixed integer linear optimization is constructed. The model takes into account the operating conditions, reservoir capacity, cycle type and other pumped storage unit constraints, but also consider the frequent start and stop and the stability of the operation of the unit caused by the loss. Using the Cplex solver to solve the model, the empirical example of the provincial power grid shows that the model can effectively arrange the pumping storage speed and the dispatching operation of the variable speed unit under the precondition of economic life of the unit, and give full play to the function of peak shaving and accommodating new energy. Because of its more flexible regulation characteristics of power generation and pumping conditions, the variable speed unit can better improve the operating conditions of other units in the system and promote the new energy dissipation.

  7. Fixed-speed and Variable-speed Pumped Storage Dispatch Model in Power Systems with High Renewable Penetration

    Science.gov (United States)

    Yuan, Bo; Zong, Jin; Xu, Zhicheng

    2018-06-01

    According to different operating characteristics of pumped storage fixed speed unit and variable speed unit, a joint dispatching model of pumped storage unit and other types of units based on mixed integer linear optimization is constructed. The model takes into account the operating conditions, reservoir capacity, cycle type and other pumped storage unit constraints, but also consider the frequent start and stop and the stability of the operation of the unit caused by the loss. Using the Cplex solver to solve the model, the empirical example of the provincial power grid shows that the model can effectively arrange the pumping storage speed and the dispatching operation of the variable speed unit under the precondition of economic life of the unit, and give full play to the function of peak shaving and accommodating new energy. Because of its more flexible regulation characteristics of power generation and pumping conditions, the variable speed unit can better improve the operating conditions of other units in the system and promote the new energy dissipation.

  8. A new hydraulic regulation method on district heating system with distributed variable-speed pumps

    International Nuclear Information System (INIS)

    Wang, Hai; Wang, Haiying; Zhu, Tong

    2017-01-01

    Highlights: • A hydraulic regulation method was presented for district heating with distributed variable speed pumps. • Information and automation technologies were utilized to support the proposed method. • A new hydraulic model was developed for distributed variable speed pumps. • A new optimization model was developed based on genetic algorithm. • Two scenarios of a multi-source looped system was illustrated to validate the method. - Abstract: Compared with the hydraulic configuration based on the conventional central circulating pump, a district heating system with distributed variable-speed-pumps configuration can often save 30–50% power consumption on circulating pumps with frequency inverters. However, the hydraulic regulations on distributed variable-speed-pumps configuration could be more complicated than ever while all distributed pumps need to be adjusted to their designated flow rates. Especially in a multi-source looped structure heating network where the distributed pumps have strongly coupled and severe non-linear hydraulic connections with each other, it would be rather difficult to maintain the hydraulic balance during the regulations. In this paper, with the help of the advanced automation and information technologies, a new hydraulic regulation method was proposed to achieve on-site hydraulic balance for the district heating systems with distributed variable-speed-pumps configuration. The proposed method was comprised of a new hydraulic model, which was developed to adapt the distributed variable-speed-pumps configuration, and a calibration model with genetic algorithm. By carrying out the proposed method step by step, the flow rates of all distributed pumps can be progressively adjusted to their designated values. A hypothetic district heating system with 2 heat sources and 10 substations was taken as a case study to illustrate the feasibility of the proposed method. Two scenarios were investigated respectively. In Scenario I, the

  9. On the Profitability of Variable Speed Pump-Storage-Power in Frequency Restoration Reserve

    Science.gov (United States)

    Filipe, Jorge; Bessa, Ricardo; Moreira, Carlos; Silva, Bernardo

    2017-04-01

    The increase penetration of renewable energy sources (RES) into the European power system has introduced a significant amount of variability and uncertainty in the generation profiles raising the needs for ancillary services as well as other tools like demand response, improved generation forecasting techniques and changes to the market design. While RES is able to replace energy produced by the traditional centralized generation, it cannot displace its capacity in terms of ancillary services provided. Therefore, centralized generation capacity must be retained to perform this function leading to over-capacity issues and underutilisation of the assets. Large-scale reversible hydro power plants represent the majority of the storage solution installed in the power system. This technology comes with high investments costs, hence the constant search for methods to increase and diversify the sources of revenue. Traditional fixed speed pump storage units typically operate in the day-ahead market to perform price arbitrage and, in some specific cases, provide downward replacement reserve (RR). Variable speed pump storage can not only participate in RR but also contribute to FRR, given their ability to control its operating point in pumping mode. This work does an extended analysis of a complete bidding strategy for Pumped Storage Power, enhancing the economic advantages of variable speed pump units in comparison with fixed ones.

  10. A novel technology for control of variable speed pumped storage power plant

    Institute of Scientific and Technical Information of China (English)

    Seyed Mohammad Hassan Hosseini; Mohammad Reza Semsar

    2016-01-01

    Variable speed pumped storage machines are used extensively in wind power plant and pumped storage power plant. This paper presents direct torque and flux control (DTFC) of a variable speed pumped storage power plant (VSPSP). By this method both torque and flux have been applied to control the VSPSP. The comparison between VSPSP’s control strategies is studied. At the first, a wind turbine with the capacity 2.2 kW and DTFC control strategies simulated then a 250 MW VSPSP is simulated with all of its parts (including electrical, mechanical, hydraulic and its control system) by MATLAB software. In all of simulations, both converters including two-level voltage source converter (2LVSC) and three-level voltage source converter (3LVSC) are applied. The results of applying 2LVSC and 3LVSC are the rapid dynamic responses with better efficiency, reducing the total harmonic distortion (THD) and ripple of rotor torque and flux.

  11. Variable speed drives for pumps used in intensive pond culture systems

    Science.gov (United States)

    Prior to about 2010, the only large pumps on most catfish farms were those associated with the water supply. Water from wells is usually pumped to the surface using single-speed, vertical, lineshaft turbine pumps powered by three phase, electric motors. Since 2010, several catfish farmers have bui...

  12. An Energy Efficient Hydraulic Winch Drive Concept Based on a Speed-variable Switched Differential Pump

    DEFF Research Database (Denmark)

    Schmidt, Lasse; Andersen, Torben O.; Pedersen, Henrik Clemmensen

    2017-01-01

    controls. Such solutions are typically constituted by many and rather expensive components, and are furthermore often suffering from low frequency dynamics. In this paper an alternative solution is proposed for winch drive operation, which is based on the so-called speed-variable switched differential pump......, originally designed for direct drive of hydraulic differential cylinders. This concept utilizes three pumps, driven by a single electric servo drive. The concept is redesigned for usage in winch drives, driven by flow symmetric hydraulic motors and single directional loads as commonly seen in e.g. active...... heave compensation applications. A general drive configuration approach is presented, along with a proper control strategy and design. The resulting concept is evaluated when applied for active heave compensation. Results demonstrate control performance on level with conventional valve solutions...

  13. Energy saving analyses on the reconstruction project in district heating system with distributed variable speed pumps

    International Nuclear Information System (INIS)

    Sheng, Xianjie; Lin, Duanmu

    2016-01-01

    Highlights: • The mathematical model of economic frictional factor based on DVFSP DHS is established. • Influence factors of economic frictional factor are analyzed. • Energy saving in a DVFSP district heating system is presented and analyzed. - Abstract: Optimization of the district heating (DH) piping network is of vital importance to the economics of the whole DH system. The application of distributed variable frequency speed pump (DVFSP) in the district heating network has been considered as a technology improvement that has a potential in saving energy compared to the conventional central circulating pump (CCCP) district heating system (DHS). Economic frictional factor is a common design parameter used in DH pipe network design. In this paper, the mathematical model of economic frictional factor based on DVFSP DHS is established, and influence factors are analyzed, providing a reference for engineering designs for the system. According to the analysis results, it is studied that the energy efficiency in the DH system with the DVFSP is compared with the one in the DH system with conventional central circulating pump (CCCP) using a case based on a district heating network in Dalian, China. The results of the study on the case show that the average electrical energy saved is 49.41% of the one saved by the DH system with conventional central circulating pump in the primary network.

  14. Residential Cold Climate Heat Pump (CCHP) w/Variable Speed Technology

    Energy Technology Data Exchange (ETDEWEB)

    Messmer, Craig S. [Unico, Inc., Arnold, MO (United States)

    2016-09-30

    This report summarizes the results of a three year program awarded to Unico, Inc. to commercialize a residential cold climate heat pump. Several designs were investigated. Compressors were selected using analysis from Oakridge National Laboratories followed by prototype construction and lab testing in a specially built environmental chamber capable of reaching -30°F. The initial design utilized two variable speed compressors in series with very good capacity results and acceptable efficiency at very cold temperatures. The design was then modified to reduce cost and complexity by redesigning the system using three dual-stage compressors: two in parallel followed by one in series. Extensive testing found significant challenge with oil management, reliability, weight and cost which prevented the system from being fully commercialized. Further analysis of other conceptual designs indicated that these challenges could be overcome in the future.

  15. Integration of Variable Speed Pumped Hydro Storage in Automatic Generation Control Systems

    Science.gov (United States)

    Fulgêncio, N.; Moreira, C.; Silva, B.

    2017-04-01

    Pumped storage power (PSP) plants are expected to be an important player in modern electrical power systems when dealing with increasing shares of new renewable energies (NRE) such as solar or wind power. The massive penetration of NRE and consequent replacement of conventional synchronous units will significantly affect the controllability of the system. In order to evaluate the capability of variable speed PSP plants participation in the frequency restoration reserve (FRR) provision, taking into account the expected performance in terms of improved ramp response capability, a comparison with conventional hydro units is presented. In order to address this issue, a three area test network was considered, as well as the corresponding automatic generation control (AGC) systems, being responsible for re-dispatching the generation units to re-establish power interchange between areas as well as the system nominal frequency. The main issue under analysis in this paper is related to the benefits of the fast response of variable speed PSP with respect to its capability of providing fast power balancing in a control area.

  16. Variable load failure mechanism for high-speed load sensing electro-hydrostatic actuator pump of aircraft

    Directory of Open Access Journals (Sweden)

    Cun SHI

    2018-05-01

    Full Text Available This paper presents a novel transient lubrication model for the analysis of the variable load failure mechanism of high-speed pump used in Load Sensing Electro-Hydrostatic Actuator (LS-EHA. Focusing on the slipper/swashplate pair partial abrasion, which is considered as the dominant failure mode in the high-speed condition, slipper dynamic models are established. A forth sliding motion of the slipper on the swashplate surface is presented under the fact that the slipper center of mass will rotate around the center of piston ball when the swashplate angle is dynamically adjusted. Besides, extra inertial tilting moments will be produced for the slipper based on the theorem on translation of force, which will increase rapidly when LS-EHA pump operates under high-speed condition. Then, a dynamic lubricating model coupling with fluid film thickness field, temperature field and pressure field is proposed. The deformation effects caused by thermal deflection and hydrostatic pressure are considered. A numerical simulation model is established to validate the effectiveness and accuracy of the proposed model. Finally, based on the load spectrum of aircraft flight profile, the variable load conditions and the oil film characteristics are analyzed, and series of variable load rules of oil film thickness with variable speed/variable pressure/variable displacement are concluded. Keywords: Coupling lubrication model, Electro-Hydrostatic Actuator (EHA, High-speed pump, Partial abrasion, Slipper pair, Variable load

  17. Power maximization of an asynchronous wind turbine with a variable speed feeding a centrifugal pump

    International Nuclear Information System (INIS)

    Ouchbel, T.; Zouggar, S.; Elhafyani, M.L.; Seddik, M.; Oukili, M.; Aziz, A.; Kadda, F.Z.

    2014-01-01

    Highlights: • The pumping system studied contain a WT, a SEIG, an IM and a CP. • The system must ensure the water pumping in optimum conditions despite the wind speed. • A steady state study and a practical testing are performed to resolve the control law. • A MPPT is proposed on the basis of static converter SVC. - Abstract: This article focuses on the study of a pumping system compound of a wind turbine, a self-excited induction generator (SEIG), an induction motor (IM), and a centrifugal pump (CP), which aims to ensure the water pumping in optimum conditions regardless the wind speed. As a first step, a study in the steady and dynamic state to determine the control law is examined. As a second step, and so as to achieve a maximum energy flow we have proposed a Maximum Power Point Tracking (MPPT) algorithm based on a static converter SVC. As a final step, experimental and simulation results are discussed to show the reliability of the system proposed

  18. Investigation into the Effects of the Variable Displacement Mechanism on Swash Plate Oscillation in High-Speed Piston Pumps

    Directory of Open Access Journals (Sweden)

    Xu Fang

    2018-04-01

    Full Text Available High-speed, pressure-compensated variable displacement piston pumps are widely used in aircraft hydraulic systems for their high power density. The swash plate is controlled by the pressure-compensated valve, which uses pressure feedback so that the instantaneous output flow of the pump is exactly enough to maintain a presetting pressure. The oscillation of the swash plate is one of the major excitation sources in the high-speed piston pump, which may cause lower efficiency, shorter service life, and even serious damage. This paper presents an improved model to investigate the influence of the variable displacement mechanism on the swash plate oscillation and introduces some feasible ways to reduce oscillation of the swash plate. Most of the variable structural parameters of the variable displacement mechanism are taken into consideration, and their influences on swash plate oscillation are discussed in detail. The influence of the load pipe on the oscillation of the swash plate is considered in the improved model. A test rig is built and similarities between the experiments and simulated results prove that the simulation model can effectively predict the variable displacement mechanism state. The simulation results show that increasing the volume of the outlet chamber, the spring stiffness of the control valve, the action area of the actuator piston, and offset distance of the actuator piston can significantly reduce the oscillation amplitude of the swash plate. Furthermore, reducing the diameter of the control valve spool and the dead volume of the actuator piston chamber can also have a positive effect on oscillation amplitude reduction.

  19. Using LDR as Sensing Element for an External Fuzzy Controller Applied in Photovoltaic Pumping Systems with Variable-Speed Drives.

    Science.gov (United States)

    Maranhão, Geraldo Neves De A; Brito, Alaan Ubaiara; Leal, Anderson Marques; Fonseca, Jéssica Kelly Silva; Macêdo, Wilson Negrão

    2015-09-22

    In the present paper, a fuzzy controller applied to a Variable-Speed Drive (VSD) for use in Photovoltaic Pumping Systems (PVPS) is proposed. The fuzzy logic system (FLS) used is embedded in a microcontroller and corresponds to a proportional-derivative controller. A Light-Dependent Resistor (LDR) is used to measure, approximately, the irradiance incident on the PV array. Experimental tests are executed using an Arduino board. The experimental results show that the fuzzy controller is capable of operating the system continuously throughout the day and controlling the direct current (DC) voltage level in the VSD with a good performance.

  20. Using LDR as Sensing Element for an External Fuzzy Controller Applied in Photovoltaic Pumping Systems with Variable-Speed Drives

    Directory of Open Access Journals (Sweden)

    Geraldo Neves De A. Maranhão

    2015-09-01

    Full Text Available In the present paper, a fuzzy controller applied to a Variable-Speed Drive (VSD for use in Photovoltaic Pumping Systems (PVPS is proposed. The fuzzy logic system (FLS used is embedded in a microcontroller and corresponds to a proportional-derivative controller. A Light-Dependent Resistor (LDR is used to measure, approximately, the irradiance incident on the PV array. Experimental tests are executed using an Arduino board. The experimental results show that the fuzzy controller is capable of operating the system continuously throughout the day and controlling the direct current (DC voltage level in the VSD with a good performance.

  1. Speed-variable Switched Differential Pump System for Direct Operation of Hydraulic Cylinders

    DEFF Research Database (Denmark)

    Schmidt, Lasse; Roemer, Daniel Beck; Pedersen, Henrik Clemmensen

    2015-01-01

    differential cylinders. The main idea was here to utilize an electric rotary drive, with the shaft interconnected to two antiparallel fixed displacement gear pumps, to actuate a differential cylinder. With the design carried out such that the area ratio of the cylinder matches the displacement ratio of the two...

  2. Advanced variable speed air source integrated heat pump (AS-IHP) development - CRADA final report

    Energy Technology Data Exchange (ETDEWEB)

    Baxter, Van D. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Rice, C. Keith [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Munk, Jeffrey D. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Ally, Moonis Raza [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Shen, Bo [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

    2015-09-30

    Between August 2011 and September 2015, Oak Ridge National Laboratory (ORNL) and Nordyne, LLC (now Nortek Global HVAC LLC, NGHVAC) engaged in a Cooperative Research and Development Agreement (CRADA) to develop an air-source integrated heat pump (AS-IHP) system for the US residential market. Two generations of laboratory prototype systems were designed, fabricated, and lab-tested during 2011-2013. Performance maps for the system were developed using the latest research version of the DOE/ORNL Heat Pump Design Model, or HPDM, (Rice 1991; Rice and Jackson 2005; Shen et al 2012) as calibrated against the lab test data. These maps were the input to the TRNSYS (SOLAR Energy Laboratory, et al, 2010) system to predict annual performance relative to a baseline suite of equipment meeting minimum efficiency standards in effect in 2006 (combination of 13 SEER air-source heat pump (ASHP) and resistance water heater with Energy Factor (EF) of 0.9). Predicted total annual energy savings, while providing space conditioning and water heating for a tight, well insulated 2600 ft2 (242 m2) house at 5 U.S. locations, ranged from 46 to 61%, averaging 52%, relative to the baseline system (lowest savings at the cold-climate Chicago location). Predicted energy use for water heating was reduced 62 to 76% relative to resistance WH. Based on these lab prototype test and analyses results a field test prototype was designed and fabricated by NGHVAC. The unit was installed in a 2400 ft2 (223 m2) research house in Knoxville, TN and field tested from May 2014 to April 2015. Based on the demonstrated field performance of the AS-IHP prototype and estimated performance of a baseline system operating under the same loads and weather conditions, it was estimated that the prototype would achieve ~40% energy savings relative to the minimum efficiency suite. The estimated WH savings were >60% and SC mode savings were >50%. But estimated SH savings were only about 20%. It is believed that had the test

  3. Rotor-dynamic design aspects for a variable frequency drive based high speed cryogenic centrifugal pump in fusion devices

    International Nuclear Information System (INIS)

    Das, Jotirmoy; Vaghela, Hitensinh; Bhattacharya, Ritendra; Patel, Pratik; Shukla, Vinit; Shah, Nitin; Sarkar, Biswanath

    2015-01-01

    Superconducting magnets of large size are inevitable for fusion devices due to high magnetic field requirements. Forced flow cooling of the superconducting magnets with high mass flowrate of the order ∼3 kg/s is required to keep superconducting magnets within its safe operational boundaries during various plasma scenarios. This important requirement can be efficiently fulfilled by employing high capacity and high efficiency cryogenic centrifugal pumps. The efficiency > 70% will ensure overall lower heat load to the cryoplant. Thermo-hydraulic design of cryogenic centrifugal pump revealed that to achieve the operational regime with high efficiency, the speed should be ∼ 10,000 revolutions per minute. In this regard, the rotor-dynamic design aspect is quite critical from the operational stability point of view. The rotor shaft design of the cryogenic pump is primarily an outcome of optimization between thermal heat-in leak at cryogenic temperature level from ambient, cryogenic fluid impedance and designed rotation speed of the impeller wheel. The paper describes the basic design related to critical speed of the rotor shaft, rotor whirl and system instability prediction to explore the ideal operational range of the pump from the system stability point of view. In the rotor-dynamic analysis, the paper also describes the Campbell plots to ensure that the pump is not disturbed by any of the critical speeds, especially while operating near the nominal and enhanced operating modes. (author)

  4. Pressure management of water distribution systems via the remote real-time control of variable speed pumps

    CSIR Research Space (South Africa)

    Page, Philip R

    2017-08-01

    Full Text Available describes controllers which set the pump speed α, a physical property of the pump. The “proportional control” method (denoted PC), in analogy to the method for PCVs [2, 3, 12, 13], adjusts αi+1 = αi − kpi (Hi −Hsp) (3) where kpi is a dimension-full parameter... constant) Kpi in Eq. 6. An analogous procedure was followed for a PCV [13]. The proposed controller is called the “parameter-dependent P-controller with known constant pump flow” (DCF). The LCF and DCF controllers require Q to be known, either through a...

  5. Utilization technique on variable speed device

    International Nuclear Information System (INIS)

    1989-12-01

    This reports of workshop on power technology describes using technique on variable speed device, which deals with alternating current situation and prospect of current variable speed device, technical trend and prospect of electronics, reduce expenses by variable speed device, control technique, measurement technology, high voltage variable speed device, recent trend of inverter technology, low voltage and high voltage variable speed device control device, operating variable speed device in cooling fan, FDF application and defect case of variable speed device, cooling pump application of water variable transformer, inverter application and energy effect of ventilation equipment, application of variable speed device and analysis of the result of operation and study for application of variable speed technology.

  6. High efficiency, variable geometry, centrifugal cryogenic pump

    International Nuclear Information System (INIS)

    Forsha, M.D.; Nichols, K.E.; Beale, C.A.

    1994-01-01

    A centrifugal cryogenic pump has been developed which has a basic design that is rugged and reliable with variable speed and variable geometry features that achieve high pump efficiency over a wide range of head-flow conditions. The pump uses a sealless design and rolling element bearings to achieve high reliability and the ruggedness to withstand liquid-vapor slugging. The pump can meet a wide range of variable head, off-design flow requirements and maintain design point efficiency by adjusting the pump speed. The pump also has features that allow the impeller and diffuser blade heights to be adjusted. The adjustable height blades were intended to enhance the pump efficiency when it is operating at constant head, off-design flow rates. For small pumps, the adjustable height blades are not recommended. For larger pumps, they could provide off-design efficiency improvements. This pump was developed for supercritical helium service, but the design is well suited to any cryogenic application where high efficiency is required over a wide range of head-flow conditions

  7. Variable speed generators

    CERN Document Server

    Boldea, Ion

    2005-01-01

    With the deregulation of electrical energy production and distribution, says Boldea (Polytechnical Institute, Timisoara, Romania) producers are looking for ways to tailor their electricity for different markets. Variable-speed electric generators are serving that purpose, up to the 400 megavolt ampere unit size, in Japan since 1996 and Germany sinc

  8. Indigenously developed large pumping speed cryoadsorption cryopump

    International Nuclear Information System (INIS)

    Gangradey, Ranjana; Mukherjee, Samiran Shanti; Agarwal, Jyoti

    2015-01-01

    Indigenous cryoadsorption cryopump with large pumping speeds for fusion reactor application has been developed at the Institute for Plasma Research (IPR). Towards its successful realization, technological bottlenecks were identified, studied and resolved. Hydroformed cryopanels were developed from concept leading to the design and product realization with successful technology transfer to the industry. This has led to the expertise for developing hydroformed panels for any desired shape, geometry and welding pattern. Activated sorbents were developed, characterized using an experimental set up which measures adsorption isotherms down to 4K for hydrogen and helium. Special techniques were evolved for coating sorbents on hydroformed cryopanels with suitable cryo-adhesives. Various arrangements of cryopanels at 4 K surrounded by 80 K shields and baffles (which are also hydroformed) were studied and optimized by transmission probability analysis using Monte Carlo techniques. CFD analysis was used to study the temperature distribution and flow analysis during the cryogen flow through the panels. Integration of the developed technologies to arrive at the final product was a challenging task and this was meticulously planned and executed. This resulted in a cryoadsorption cryopump offering pumping speeds as high as 50,000 to 70,000 1/s for helium and 1,50,000 1/s for hydrogen with a 3.2 m 2 of sorbent panel area. The first laboratory scale pump integrating the developed technologies was a Small Scale CryoPump (SSCP-01) with a pumping speed of 2,000 1/s for helium. Subsequently, Single Panel CryoPump (SPCP-01) with pumping speed 10,000 1/s for helium and a Multiple Panel CryoPump (MPCP-08) with a pumping speed of 70,000 1/s for helium and 1,50,000 1/s for hydrogen respectively were developed. This paper describes the efforts in realizing these products from laboratory to industrial scales. (author)

  9. Regulating vacuum pump speed with feedback control

    International Nuclear Information System (INIS)

    Ludington, D.C.; Aneshansley, D.J.; Pellerin, R.; Guo, F.

    1992-01-01

    Considerable energy is wasted by the vacuum pump/motor on dairy farms. The output capacity (m 3 /min or cfm) of the vacuum pump always exceeds the capacity needed to milk cows and wash pipelines. Vacuum pumps run at full speed and load regardless of actual need for air. Excess air is admitted through a controller. Energy can be saved from electrical demand reduced by regulating vacuum pump speed according to air based on air usage. An adjustable speed drive (ASD) on the motor and controlled based upon air usage, can reduce the energy used by the vacuum pump. However, the ASD unit tested could not maintain vacuum levels within generally accepted guidelines when air usage changed. Adding a high vacuum reserve and a dual vacuum controller between the vacuum pump and the milking pipeline brought vacuum stability within guidelines. The ASD/dual vacuum system can reduce energy consumption and demand by at least 50 percent during milking and provide better vacuum stability than conventional systems. Tests were not run during washing cycles. Using 1990 costs and only the energy saved during milking, the simple payback on investment in new equipment for a 5 hp motor, speed controller and vacuum regulator would be about 5 years

  10. Speed control variable rate irrigation

    Science.gov (United States)

    Speed control variable rate irrigation (VRI) is used to address within field variability by controlling a moving sprinkler’s travel speed to vary the application depth. Changes in speed are commonly practiced over areas that slope, pond or where soil texture is predominantly different. Dynamic presc...

  11. Speed control device for coolant recycling pump

    International Nuclear Information System (INIS)

    Kageyama, Takao.

    1992-01-01

    The present invention intends to increase a margin relative of the oscillations of neutron fluxes when the temperature of feedwater is lowered in a compulsory recycling type BWR reactor. That is, when the operation point represented by a reactor thermal power and a reactor core inlet flow rate is in a state approximate to an oscillation limit of the reactor power, the device of the present invention controls the recycling pump speed in the increasing direction depending on the lowering range of the feedwater temperature from a stationary state. With such a constitution, even if the reactor power is in the operation region near the oscillation limit in the BWR type reactor and a feedwater heating loss is caused, the speed of the coolant recycling pump is increased by 10% at the maximum depending on the extent of the reduction of the feedwater temperature, so that the oscillation of the reactor power can be prevented from lasting for a long period of time even if a reactivity external disturbance should occur in the reactor. (I.S.)

  12. LOFT pump speed controller stability and accuracy analysis

    International Nuclear Information System (INIS)

    Good, R.R.

    1978-01-01

    Two system modifications to the primary coolant pumps motor generators control systems have recently been completed. The range of pump speed operation has been extended and the scoop tube positioner motor replaced. This has necessitated a re-analysis of PSMG stability throughout its range of operation. System accuracy requirements of less than 4 Hz differential pump speed when operating at less than 35 Hz and 8.5 Hz differential pump speed when operating at greater than 35 Hz can be guaranteed by specifying the gain of the system. The installation of the new scoop tube positioner motor will increase the PSMG system's bandwidth and stability. Low speed pump trips should be carefully evaluated if the pump's operational range is to extend to 10 Hz

  13. Variable Speed Rotor System, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Variable speed rotors will give helicopters several advantages: higher top speed, greater fuel efficiency, momentary emergency over-power, resonance detuning...

  14. Efficiency improvement of variable speed electrical drives for HVAC applications

    Energy Technology Data Exchange (ETDEWEB)

    Abrahamsen, F.; Blaabjerg, F.; Pedersen, J.K. [Aalborg Univ., Inst. of Energy Technology, Aalborg East (Denmark)

    2000-07-01

    A large part of the produced electrical energy is consumed by ventilators, pumps and compressors, the so-called HVAC applications. A lot of this energy can be saved by speed control, but even with the large saving obtained alone by introduction of variable speed, it is still essential to optimise the control of the variable speed drive and to optimise the electrical machine with respect to efficiency. Experiments are made with energy optimal induction motor control on a 2.2 kW variable speed pump system. It is demonstrated that 10% of the consumed energy can typically be saved by energy optimal motor control compared with constant V/Hz control. In a comparison of induction motors and permanent magnet synchronous motors for a variable speed pump application it is shown that for 2.2 kW motors an investment in high-efficiency or PM motors are typically paid back within 2.5 years and 7 years respectively. For a 90 kW PM motor the pay-back time would be 24 years. It is today not profitable to use PM motors for variable speed HVAC applications above 2 kW rated motor power. A further study is required to determine this limit in power rating more precisely. (orig.)

  15. Variations in battery life of a heart-lung machine using different pump speeds, pressure loads, boot material, centrifugal pump head, multiple pump usage, and battery age.

    LENUS (Irish Health Repository)

    Marshall, Cornelius

    2012-02-03

    Electrical failure during cardiopulmonary bypass (CPB) has previously been reported to occur in 1 of every 1500 cases. Most heart-lung machine pump consoles are equipped with built-in battery back-up units. Battery run times of these devices are variable and have not been reported. Different conditions of use can extend battery life in the event of electrical failure. This study was designed to examine the run time of a fully charged battery under various conditions of pump speed, pressure loads, pump boot material, multiple pump usage, and battery life. Battery life using a centrifugal pump also was examined. The results of this study show that battery life is affected by pump speed, circuit pressure, boot stiffness, and the number of pumps in service. Centrifugal pumps also show a reduced drain on battery when compared with roller pumps. These elements affect the longevity and performance of the battery. This information could be of value to the individual during power failure as these are variables that can affect the battery life during such a challenging scenario.

  16. Evaluation of Ti-Zr-V (NEG) Thin Films for their pumping speed and pumping Capacity

    International Nuclear Information System (INIS)

    Bansod, Tripti; Sindal, B K; Kumar, K V A N P S; Shukla, S K

    2012-01-01

    Deposition of NEG thin films onto the interior walls of the vacuum chambers is an advanced technique to convert a vacuum chamber from a gas source to an effective pump. These films offer considerably large pumping speed for reactive gases like CO, H 2 etc. A UHV compatible pumping speed measurement system was developed in-house to measure the pumping speed of NEG coated chambers. To inject the fixed quantity of CO and H 2 gas in pumping speed measurement set-up a calibrated leak was also developed. Stainless steel chambers were sputter coated with thin film of Ti-Zr-V getter material using varied parameters for different compositions and thickness. Pumping capacity which is a function of sorbed gas quantities was also studied at various activation temperatures. In order to optimize the activation temperature for maximum pumping speed for CO and H 2 , pumping speeds were measured at room temperature after activation at different temperatures. The experimental system detail, pumping performance of the NEG film at various activation temperatures and RGA analysis are presented.

  17. Pumping speed of parallel-louvre-blind-type cryopumps

    International Nuclear Information System (INIS)

    Saho, Norihide; Ogata, Hisanao; Kunugi, Yosifumi; Uede, Taisei; Yamasita, Yasuo; Kawakami, Hiroyuki.

    1993-01-01

    As a new type of actual-sized cryopump with high pumping speed, a parallel-louvre-blind type cryopump of a rectangular cross section with opening distance B, width C and depth D, is proposed and is produced as a trial pump unit designed as actual size. The influence of pump depth size ratio R d (=D/B) and number of secondary cryopanels on the transmission probability P bc of the pump unit is calculated by Monte Carlo simulation, and the hydrogen pumping speed is measured by experiments. The following results are obtained. (1) The transmission probability of a cryopump designed with dimensional ratio of R d = 1.3 is calculated to be 0.66 at ratios of R c (=B/C) = 0.88, which means that hydrogen pumping speed of cryopumps of this size can attain 294 m 3 · s -1 /m 2 per opening area. (2) The real hydrogen pumping speed of the trial pump unit with 30 secondary cryopanels is measured as 295 m 3 · s -1 /m 2 . (author)

  18. Laser Velocimeter Measurements in the Pump of an Automotive Torque Converter Part II – Effect of Pump Speed and Oil Viscosity

    Directory of Open Access Journals (Sweden)

    Ronald D. Flack

    2000-01-01

    Full Text Available The velocity field inside a torque converter pump was studied for two separate effects: variable pump rotational speed and variable oil viscosity. Three-dimensional velocity measurements were taken using a laser velocimeter for both the pump mid- and exit planes. The effect ofvariable pump rotational speed was studied by running the pump at two different speeds and holding speed ratio (pump rotational speed]turbine rotational speed constant. Similarly, the effect of viscosity on the pump flow field was studied by varying the temperature and]or using two different viscosity oils as the working fluid in the pump. Threedimensional velocity vector plots, through-flow contour plots, and secondary flow profiles were obtained for both pump planes and all test conditions. Results showed that torque converter mass flows increased approximately linearly with increasing pump rotational speed (and fixed speed ratio but that the flow was not directly proportional to pump rotational speed. However, mass flows were seen to decrease as the oil viscosity was decreased with a resulting increased Reynolds number; for these conditions the high velocity regions were seen to decrease in size and low velocity regions were seen to increase in size. In the pump mid-plane strong counter-clockwise secondary flows and in the exit plane strong clockwise secondary flows were observed. The vorticities and slip factors were calculated from the experimental results and are presented. The torque core-to-shell and blade-to-blade torque distributions were calculated for both planes. Finally, the flow fields were seen to demonstrate similitude when Reynolds numbers were matched.

  19. Research on rotational speed to the influence of pump as turbine

    International Nuclear Information System (INIS)

    Yang, S S; Kong, F Y; Jiang, W M; Qu, X Y

    2012-01-01

    Due to the problem of lacking hydraulic control devices, pump as turbine (PAT) has the disadvantage of optimum operation only within a small range discharge where the net head utilization and operating efficiency are the highest. Variable speed operation offers a good solution to this problem. Pump manufactures normally do not provide performance curves of their pumps working as turbines, especially when working at variable speed condition. Therefore, establishing a correlation between PAT's performance curve and rotational speed is essential. In this paper, a method of predicting PAT's performance at different rotational speeds was first developed using theoretical analysis. In the second step, a single stage centrifugal pump operated as a turbine was tested at different rotational speeds. Typical performance curves of PAT operating at variable speed condition were acquired. Finally computational fluid dynamics (CFD) had been used in this research. The accuracy of CFD prediction was proved when compared with experimental data. The validity of presented method by theoretical analysis was validated using test and CFD results.

  20. Variable Speed Limit (VSL) - Best Management Practice

    Science.gov (United States)

    2012-07-01

    The Variable Speed Limit (VSL) system on the I-4 corridor in Orlando was implemented by Florida Department of Transportation in 2008, and since its deployment, it was revealed that the majority of traffic exceeds the speed limit by more mph when the ...

  1. Variable-speed, portable routing skate

    Science.gov (United States)

    Pesch, W. A.

    1967-01-01

    Lightweight, portable, variable-speed routing skate is used on heavy metal subassemblies which are impractical to move to a stationary machine. The assembly, consisting of the housing with rollers, router, and driving mechanism with transmission, weighs about forty pounds. Both speed and depth of cut are adjustable.

  2. Rural variable speed limits : phase II.

    Science.gov (United States)

    2012-05-01

    The Wyoming Department of Transportation (WYDOT) installed its first variable speed limit (VSL) corridor along : Interstate 80 in the Elk Mountain Corridor in the Spring of 2009 in an effort to improve safety and reduce road closures, : particularly ...

  3. Flow Rate In Microfluidic Pumps As A Function Of Tension and Pump Motor Head Speed

    Science.gov (United States)

    Irwin, Anthony; McBride, Krista

    2015-03-01

    As the use of microfluidic devices has become more common in recent years the need for standardization within the pump systems has grown. The pumps are ball bearing rotor microfluidic pumps and work off the idea of peristalsis. The rapid contraction and relaxation propagating down a tube or a microfluidic channel. The ball bearings compress the tube (occlusion) and move along part of the tube length forcing fluid to move inside of the tube in the same direction of the ball bearings. When the ball bearing rolls off the area occupied by the microfluidic channel, its walls and ceiling undergo restitution and a pocket of low pressure is briefly formed pulling more of the liquid into the pump system. Before looking to standardize the pump systems it must be known how the tension placed by the pumps bearing heads onto the PDMS inserts channels affect the pumps performance (mainly the flow rate produced). The relationship of the speed at which the bearings on the motor head spin and the flow rate must also be established. This research produced calibration curves for flow rate vs. tension and rpm. These calibration curves allow the devices to be set to optimal user settings by simply varying either the motor head tension or the motor head speed. I would like to acknowledge the help and support of Vanderbilt University SyBBURE program, Christina Marasco, Stacy Sherod, Franck Block and Krista McBride.

  4. Experiment of a centrifugal pump during changing speed operation

    International Nuclear Information System (INIS)

    Yuan, H J; Wu, Y L; Liu, S H; Shao, J

    2012-01-01

    In this paper, a method of changing rotational speed of impeller periodically as the pulsatile working condition is developed to realize pulse outputs both of flow discharge and of head for a centrifugal pump through experiment. The performance of the centrifugal pump under pulsatile working operation condition is measured which indicates this model pump could produce desired pulse flow under such condition. Flow patterns at four testing points under pulsatile conditions are obtained by means of the particle image velocimetry (PIV) technology both with laser induced fluorescence (LIF) particles and refractive index matched (RIM) fluid. Results of PIV measurement show the distributions of velocity, streamlines, and the principal Reynolds normal stress (PRNS). Under the design flow rate condition, the relative velocity in the blade channel distributes smoothly and decreases from inlet to exit. And at the impeller exit, the relative velocity is lower close to suction side than that near pressure side of blade in most of blade channels.

  5. Quantifying the energy impact of a variable flow pump in a ground-coupled heat pump system

    Energy Technology Data Exchange (ETDEWEB)

    Iolova, K.; Bernier, M.A. [Ecole Polytechnique, Montreal, PQ (Canada). Dept. de Genie Mecanique; Nichols, L. [Dessau-Soprin, Montreal, PQ (Canada)

    2006-07-01

    The thermal behaviour of an energy-efficient public high school building was modelled using the TRNSYS multi-zone building simulation program. The architectural elements such as windows, external and internal walls, roofs, and slabs were described in detail. The two-storey Ecole du Tournant high school near Montreal is the most efficient in Quebec and the second in Canada. It consumes 79.2 per cent less source energy than a typical high school built in accordance with the Model National Energy Code of Canada for Buildings. This presentation described the case study and quantified the energy impact of replacing a constant speed pump with a pump driven by a variable frequency drive in a ground-coupled heat pump (GCHP) system that was installed in the high school. Performance data collected from an on-site energy management system showed that the annual energy consumption of the heat pumps is 33 per cent (63700 kWh) of the total energy consumption of the school while the circulating pump consumes 7.1 per cent (13702 kWh). This performance data was used to validate the energy simulations which were performed using TRNSYS 15. Simulations with variable-flow pumping showed that pumping energy consumption was reduced by about 82 per cent while the total energy used by the circulating pump and heat pumps was reduced by 18.5 per cent. 11 refs., 2 tabs., 13 figs.

  6. Handbook of asynchronous machines with variable speed

    CERN Document Server

    Razik, Hubert

    2013-01-01

    This handbook deals with the asynchronous machine in its close environment. It was born from a reflection on this electromagnetic converter whose integration in industrial environments takes a wide part. Previously this type of motor operated at fixed speed, from now on it has been integrated more and more in processes at variable speed. For this reason it seemed useful, or necessary, to write a handbook on the various aspects from the motor in itself, via the control and while finishing by the diagnosis aspect. Indeed, an asynchronous motor is used nowadays in industry where variation speed a

  7. Measurement and evaluation of pumping speed and gas discharge characteristics of titanium getter pump by conductance modulation method

    International Nuclear Information System (INIS)

    Terada, Keiko; Okano, Tatsuo; Tsuji, Hiroshi.

    1989-01-01

    The conductance modulation method is designed to determine the pumping speed from a known conductance. With the method, the intrinsic pumping speed Sp and net pumping speed S * can be determined in a wide range up to near the ultimate pressure. In the present study, the pumping speed and gas discharge rate of a titanium getter pump at 77K are analyzed, and the results are compared with measurements made at room temperature. The pressure in a vacuum chamber depends on the gas load and the pumping speed. The pressure varies from P A to P B as the conductance of the orifice is changed from C A to C B . The ultimate pressure also changes from P AO to P BO . The intrinsic and net pumping speeds can be calculated from P A , P B , P AO and P BO . The major feature of the conductance modulation method is that the intrinsic and net pumping speeds can be determined from a change in the conductance without knowing the sensitivity of the vacuum meter or the flow rate of gas entering the chamber from outside. With this feature, the method is very effective for measuring the balance between the gas discharge and pumping speed near the ultimate pressure. (N.K.)

  8. Speed control at low wind speeds for a variable speed fixed pitch wind turbine

    Energy Technology Data Exchange (ETDEWEB)

    Rosmin, N.; Watson, S.J.; Tompson, M. [Loughborough Univ., Loughborough, Leicestershire (United Kingdom)

    2010-03-09

    The maximum power regulation below rated wind speed is regulated by changing the rotor/generator speed at large frequency range in a fixed pitch, variable speed, stall-regulated wind turbine. In order to capture the power at a maximum value the power coefficient is kept at maximum peak point by maintaining the tip speed ratio at its optimum value. The wind industry is moving from stall regulated fixed speed wind turbines to newer improved innovative versions with better reliability. While a stall regulated fixed pitch wind turbine is among the most cost-effective wind turbine on the market, its problems include noise, severe vibrations, high thrust loads and low power efficiency. Therefore, in order to improve such drawbacks, the rotation of the generator speed is made flexible where the rotation can be controlled in variable speed. This paper discussed the development of a simulation model which represented the behaviour of a stall regulated variable speed wind turbine at low wind speed control region by using the closed loop scalar control with adjustable speed drive. The paper provided a description of each sub-model in the wind turbine system and described the scalar control of the induction machine. It was concluded that by using a constant voltage/frequency ratio of the generator's stator side control, the generator speed could be regulated and the generator torque could be controlled to ensure the power coefficient could be maintained close to its maximum value. 38 refs., 1 tab., 10 figs.

  9. Variable speed drives boost air handler benefits

    Energy Technology Data Exchange (ETDEWEB)

    Twenty-four separate roof-top air handlers, controlled by variable speed ac motor drives, provide comfort and ventilation for employees at a 500,000 sq. ft. sportswear distribution center in southern Virginia. They were chosen over optional packaged HVAC units because of their flexibility, efficiency, and short payback advantages. The operation of the units is described.

  10. Cryopump measurements relating to safety, pumping speed, and radiation outgassing

    International Nuclear Information System (INIS)

    Graham, W.G.; Ruby, L.

    1978-09-01

    A test cryopump has been constructed to investigate operation in close proximity to a neutral beam, to determine static and dynamic pumping speeds, and to study outgassing such as might be produced by a pulse of nuclear radiation. No difficulty was encountered in operating the cryopump close to a deuterium neutral-beam source suitable for a fusion-reactor injector. Static and dynamic pumping-speed measurements agreed well, but were somewhat lower than expectations, probably due to the unusual method chosen to supply liquid helium. Safety tests showed that hydrogen could not be ignited at any subatmospheric pressure resulting from a leak-up-to-air accident. The possible hazard of liquid-oxygen condensation in such accidents was not explored. Tests made with pulses of neutrons and gamma rays produced by a TRIGA showed that the cryopump could be partially outgassed by radiation pulses of sufficient intensity. However, the effect is ascribed to the gamma-ray component of the TRIGA pulse which is about 10 3 times that expected from a fusion reactor such as TFTR

  11. A simulation-based analysis of variable flow pumping in ground source heat pump systems with different types of borehole heat exchangers: A case study

    International Nuclear Information System (INIS)

    Zarrella, Angelo; Emmi, Giuseppe; De Carli, Michele

    2017-01-01

    Highlights: • The work focuses on the variable flow in ground source heat pump systems. • The constant and variable speed circulation pumps in the ground loop are compared. • The constant temperature difference control across the heat pump is studied. • The variable flow affects the energy performance of the heat pump. • The constant temperature difference control offers an attractive energy saving. - Abstract: A simulation model of ground source heat pump systems has been used to investigate to what extent a variable flow of the heat-carrier fluid of the ground loop affects the energy efficiency of the entire system. The model contemporaneously considers the borehole heat exchangers, the heat pump, the building load, and the control strategies for the circulation pumps of the ground loop. A constant speed of the circulation pumps of the ground loop was compared with a variable flow controlled by means of a constant temperature difference across the heat pump on the ground side considering the load profile of an office building located in North Italy. The analysis was carried out for a single U-tube, double U-tube and coaxial pipe heat exchangers. The control strategies adopted to manage the flow rate of the heat-carrier fluid of the ground loop affect both the heat exchange rate of the borehole field and the heat pump’s long-term energy efficiency. The simulations show considerable differences in the system’s seasonal energy efficiency. The constant speed of the circulation pumps leads to the best results as far as the heat pump’s energy performance was concerned, but this advantage was lost because of the greater amount of electrical energy used by the circulation pumps; this, of course, affects the energy efficiency of the entire system. The optimal solution appears then to be a constant temperature difference in the heat-carrier fluid across the heat pump.

  12. Virtual Refrigerant Mass Flow and Power Sensors for Variable-Speed Compressors

    OpenAIRE

    Kim, Woohyun; Braun, James E.

    2012-01-01

    The use of variable-speed compressors in heat pumps and air conditioners has increased in recent years in order to improve comfort and energy efficiency. At the same time, there is a trend towards embedding more sensors in this type of equipment to facilitate real-time energy monitoring and diagnostics. Although compressor mass flow rate and power consumption are useful indices for performance monitoring and diagnostics, they are expensive to measure. The virtual variable-speed compressor sen...

  13. Flow in a Low Specific Speed Centrifugal Pump Using PIV

    Directory of Open Access Journals (Sweden)

    Cui Dai

    2013-01-01

    Full Text Available The interflow plays important roles in centrifugal pump design. In order to study the effect of rotation and z-axis on internal flow, two-dimensional particle image velocimetry (PIV measurements have been performed to measure the steady velocity field on three planes in all impeller passages of a low specific-speed centrifugal pump. The results show that the relative velocity flows in blade passages are obviously different in terms of the positions of the blade relative to the tongue. The interaction between the impeller and tongue changes the occurrence and development of low velocity region with time. From shroud to hub, the relative velocity gradually increases, and the minimum value moves toward the suction surface. On the midplane, the magnitude increases with increased flow rate from pressure surface to suction surface, while at the shroud and hub, the measured velocity first increases with decreased flow rate from the blade pressure surface to nearly ζ = 0.5 to 0.6.

  14. Small variable speed hermetic reciprocating compressors for domestic refrigerators

    DEFF Research Database (Denmark)

    Rasmussen, Bjarne D.

    1996-01-01

    This paper contains both a theoretical and experimental investigation of some of the fundamental characteristics of a smal variable speed hermetic reciprocating compressor intended for application in domestic refrigeration. The results of a previously published simulation model for variable speed...

  15. Investigations on the acoustic optimisation of a variable displacement pump using virtual prototyping

    Directory of Open Access Journals (Sweden)

    Thomas NIED-MENNINGER

    2009-01-01

    Full Text Available In modern vehicles the steering systems are still widely equipped with power-assisted steering pumps. In most cases vane pumps are used which limit the fluid volume flow in dependence of required pressure and running speed by a special design of the internal control valve. This control valve internally redirects the volume flow inside the pump leading still to unnecessary fluid circulation. Variable displacement pumps now offer an additional opportunity to eliminate the internal volume flow in dependence of the required load with reduced losses and hence increased efficiency. This is realized by a variable adjustment of the displacement cells, but simultaneously the variable force and load distributions inside the pump make the acoustic optimization even more difficult. In this paper the kinematics of the vane pump are modelled with a combined analytical and numerical approach. The data out of this model are used as input data for the hydraulic model of the variable displacement vane pump with a commercial tool. Both models are validated with data from test rig investigations. With this validated virtual prototype different design options are developed and finally successfully investigated on a test rig and in a passenger vehicle.

  16. Efficiency of a variable displacement open circuit floating cup pump

    NARCIS (Netherlands)

    Vael, G.E.M.; Achten, P.A.J.; Brink, van den T.L.

    2009-01-01

    The Floating Cup Displacement principle is a relatively new axial piston displacement principle for hydrostatic pumps, motors and transformers. Since its origin in 2001, it has been mainly applied in fixed displacement pump prototypes. At the SICFP’05, a design for a variable displacement open

  17. Using variable speed drives technology to reap rewards of efficient HVAC design

    International Nuclear Information System (INIS)

    Anon.

    1999-01-01

    Electric motors are continuously running at full speed with vanes and throttles used to modulate the output, in most HVAC applications. This results in an excessive wastage of electrical energy, and the solution is the variable speed drive, which can save vast amounts of energy in fans, pumps and compressors across the HVAC system. Users of traditional control methods will not benefit from the energy savings that are possible through variable speed drives because the motor speed remains the same, with the result that some, and in some cases most, of the energy drawn will be wasted. Variable speed drives are more efficient because they control output by regulating the motor speed, rather than run the motor at full speed and use restrictions to reduce the flow. Recently, small so-called micro-drives have been launched, cutting the cost for most variable speed operation. Variable speed motors can also introduce new features to the HVAC system. An example of how drives can save money and improve the indoor climate is cited for Heathrow airport. There, the gateroom was earlier controlled by modulating valves in both heater and cooler coils, with two fans that operated continuously at rated speed. This system was very inefficient because the occupancy of the gateroom varied between zero and maximum several times daily. A new system was installed using two AC drives, in which one drive controls the supply air fan and the other the return air fan. The energy savings amounted to 89% during two tests and 77% in a third. A pump installation in the district heating system of Strasbourg, Germany, showed the savings that are possible in pump applications

  18. Variable Displacement Control of the Concrete Pumping System Based on Dynamic Programming

    Directory of Open Access Journals (Sweden)

    Ye Min

    2017-01-01

    Full Text Available To solve the problems of cylinder piston striking cylinder and the hydraulic shocking of the main pump, and causing energy waste problem, the method of variable displacement control of piston stroke was proposed. In order to achieve effective control of the piston stroke, variable displacement control model was established under the physical constraint condition of non-collision between piston and cylinder. And the control process was realized by Dynamic Programming(DP, the simulation and test results show that piston of concrete pumping system don’t strike cylinder and reduce the hydraulic shock of the main pump outlet, meanwhile improve the response speed of the cylinder and achieve energy-saving purposes under varying loads. This control model built in the integration design space of structure variable and control variable is of guiding significance for solving open-loop system’s engineering problems.

  19. Retrofit of a liquid pipeline pump station at TRANSPETRO using VFD - Variable Frequency Drive

    Energy Technology Data Exchange (ETDEWEB)

    Santiago, Adilson [TRANSPETRO - PETROBRAS Transporte S.A., Rio de Janeiro, RJ (Brazil); Maddarena, Eduardo [Siemens Ltd., Rio de Janeiro, RJ (Brazil)

    2009-07-01

    This paper presents the main operational factors motivating the application of variable frequency drives (VFD) in oil pipeline operations and a real case under way at TRANSPETRO. A brief theoretical introduction on driving centrifugal pumps with variable speed is presented and the available VFD technologies are compared. A practical case using electronic VFD is described concerning a retrofit of a pipeline pump station in the REVAP Refinery in Sao Paulo State. The case encompasses the main aspects considered in the technical and financial feasibility analysis of the retrofit project and describes the operational modes that were changed. (author)

  20. FUZZY LOGIC BASED INTELLIGENT CONTROL OF A VARIABLE SPEED CAGE MACHINE WIND GENERATION SYSTEM

    Science.gov (United States)

    The paper describes a variable-speed wind generation system where fuzzy logic principles are used to optimize efficiency and enhance performance control. A squirrel cage induction generator feeds the power to a double-sided pulse width modulated converter system which either pump...

  1. Study on transient hydrodynamic performance and cavitation characteristic of high-speed mixed-flow pump

    International Nuclear Information System (INIS)

    Chen, T; Liu, Y L; Sun, Y B; Wang, L Q; Wu, D Z

    2013-01-01

    In order to analyse the hydrodynamic performance and cavitation characteristic of a high-speed mixed-flow pump during transient operations, experimental studies were carried out. The transient hydrodynamic performance and cavitation characteristics of the mixed-flow pump with guide vane during start-up operation processes were tested on the pump performance test-bed. Performance tests of the pump were carried out under various inlet pressures and speed-changing operations. The real-time instantaneous external characteristics such as rotational speed, hydraulic head, flow rate, suction pressure and discharge pressure of the pump were measured. Based on the experimental results, the effect of fluid acceleration on the hydrodynamic performances and cavitation characteristics of the mixed-flow pump were analysed and evaluated

  2. Variable speed electrical driving systems; Entrainements electriques a vitesse variable

    Energy Technology Data Exchange (ETDEWEB)

    Bonal, J. [ESE, Promethee, Groupe Schneider (France)

    1997-12-31

    This book is the first of a series of 3 volumes which synthesize the most recent knowledge on variable speed electrical driving systems. It is devoted to electronic and electromechanical engineers and technicians and to manufacturers of electrical equipments involving such systems. after a recall of basic electrotechnical and mechanical notions, this book focusses on the functionalities and criteria of definition of driving systems, and shows the interactions between the different parts of these equipments. It develops a methodological approach of the choice for the most suitable technology with respect to the application under consideration. Various industrial sectors are concerned and a particular attention is paid to the driving of receptive turbo-machineries which play a major role in the energy balance sheet of the industrial electrical power force. (J.S.) 28 refs.

  3. Fuzzy logic based variable speed wind generation system

    Energy Technology Data Exchange (ETDEWEB)

    Simoes, M.G. [Sao Paulo Univ., SP (Brazil). Escola Politecnica. PMC - Mecatronica; Bose, B.K. [Tennessee Univ., Knoxville, TN (United States). Dept. of Electrical Engineering; Spiegel, Ronal J. [Environmental Protection Agency, Research Triangle Park, NC (United States). Air and Energy Engineering Research Lab.

    1996-12-31

    This work demonstrates the successful application of fuzzy logic to enhance the performance and control of a variable speed wind generation system. A maximum power point tracker control is performed with three fuzzy controllers, without wind velocity measurement, and robust to wind vortex and turbine torque ripple. A squirrel cage induction generator feeds the power to a double-sided PWM converter system which pumps the power to a utility grid or supplies to an autonomous system. The fuzzy logic controller FLC-1 searches on-line the generator speed so that the aerodynamic efficiency of the wind turbine is optimized. A second fuzzy controller FLC-2 programs the machine flux by on-line search so as to optimize the machine-converter system wind vortex. Detailed analysis and simulation studies were performed for development of the control strategy and fuzzy algorithms, and a DSP TMS320C30 based hardware with C control software was built for the performance evaluation of a laboratory experimental set-up. The theoretical development was fully validated and the system is ready to be reproduced in a higher power installation. (author) 7 refs., 3 figs., 1 tab.

  4. Evaluation of variable advisory speed limits in work zones.

    Science.gov (United States)

    2013-08-01

    Variable advisory speed limit (VASL) systems could be effective at both urban and rural work zones, at both uncongested and congested sites. At uncongested urban work zones, the average speeds with VASL were lower than without VASL. But the standard ...

  5. Variable Speed Limit (VSL) - Best Management Practice [Summary

    Science.gov (United States)

    2012-01-01

    In variable speed limit (VSL) zones, the speed : limit changes in response to traffic congestion, : adverse weather, or road conditions. VSL zones are : often highly automated and have been employed : successfully in several U.S. and European : locat...

  6. Simulation Analysis and Experiment of Variable-Displacement Asymmetric Axial Piston Pump

    Directory of Open Access Journals (Sweden)

    Youshan Gao

    2017-03-01

    Full Text Available The variable displacement pump control system has greater energy-saving advantages and application prospects than the valve control system. However, the variable displacement pump control of differential cylinder is not concurrent with the existing technologies. The asymmetric pump-controlled cylinder is, therefore, used to balance the unequal volume flow through a single rod cylinder in closed-circuit system. This is considered to be an effective method. Nevertheless, the asymmetric axial piston pump (AAPP is a constant displacement pump. In this study, variable-displacement asymmetric axial piston pump (VAPP is investigated according to the same principle used in investigating AAPP. This study, therefore, aims at investigating the characteristics of VAPP. The variable-displacement output of VAPP is implemented by controlling the swash plate angle with angle feedback control circuit, which is composed of a servo proportional valve and an angular displacement sensor. The angular displacement sensor is connected to the swash plate. The simulation model of VAPP, which is set up through the ITI-SimulationX simulation platform, is used to predict VAPP’s characteristics. The purpose of implementing the experiment is to verify the theoretical results. Both the simulation and the experiment results demonstrated that the swash plate angle is controlled by a variable mechanism; when the swash plate angle increases, the flow of Port B and Port T increases while the response speed of Port B and Port T also accelerates. When the swash plate angle is constant, the flow of Port B and Port T increases along with the increase of pump speed, although the pressure-response speed of Port B is faster than that of Port T. Consequently, the flow pulsation of Port B and Port T tends to decrease gradually along with the increase of pump speed. When the pressure loaded on Port B equals to that of Port T, the flow ripple cycle of Port B is longer than that of Port T

  7. The optimization of low specific speed centrifugal pump based on incomplete sensitivities

    International Nuclear Information System (INIS)

    Zhang, R H; Zheng, K; Shi, F X; Yao, L H

    2012-01-01

    In this research, the optimization method for low specific speed centrifugal pump impeller based on incomplete sensitivities was proposed. The main feature of the algorithm is that it avoids solving the flow field repeatedly in one optimization cycle in finite difference method and it avoids solving the adjoint equation in adjoint method. The blade meridional plan is considered as constant, and the blade camber line was parameterize by Taylor function. The coefficients in the Taylor function were taken as the control variable. The moment acting on the blade was considered as the objective function. With the incomplete sensitivities we can get the gradient of the objective function with respect to the control variable easily, and the blade shape can be renewed according to the inverse direction of the gradient. We will find the optimum design when the objective function is minimized. The computational cost is greatly reduced. The calculation cases show that the proposed theory and method is rotational.

  8. Cavitation performance improvement of high specific speed mixed-flow pump

    International Nuclear Information System (INIS)

    Chen, T; Sun, Y B; Wu, D Z; Wang, L Q

    2012-01-01

    Cavitation performance improvement of large hydraulic machinery such as pump and turbine has been a hot topic for decades. During the design process of the pumps, in order to minimize size, weight and cost centrifugal and mixed-flow pump impellers are required to operate at the highest possible rotational speed. The rotational speed is limited by the phenomenon of cavitation. The hydraulic model of high-speed mixed-flow pump with large flow rate and high pumping head, which was designed based on the traditional method, always involves poor cavitation performance. In this paper, on the basis of the same hydraulic design parameters, two hydraulic models of high-speed mixed-flow pump were designed by using different methods, in order to investigate the cavitation and hydraulic performance of the two models, the method of computational fluid dynamics (CFD) was adopted for internal flow simulation of the high specific speed mixed-flow pump. Based on the results of numerical simulation, the influences of impeller parameters and three-dimensional configuration on pressure distribution of the blades' suction surfaces were analyzed. The numerical simulation results shows a better pressure distribution and lower pressure drop around the leading edge of the improved model. The research results could provide references to the design and optimization of the anti-cavitation blade.

  9. Study of the conditions affecting the critical speed of a rotating pump shaft

    International Nuclear Information System (INIS)

    Fardeau, P.; Huet, J.L.; Axisa, F.

    1983-01-01

    Knowing the parameters conditioning the critical speed of a pump shaft is important, both for safety and design purposes, since the shafts are often to operate beyond the first critical speed. These aims led CEA, associated with NOVATOME and FRAMATOME (with the cooperation of JEUMONT-SCHNEIDER) to carry out a test program on critical speeds of a full scale nuclear pump shaft. Fluid-structure interaction plays an important part in the setting of critical speed. Due to the coupling between the rotative fluid flow and the transverse vibrations of the shaft, inertial and stiffness forces are created, which are non conservative and proportional to the added mass of the fluid. The hydrostatic bearing effect and the influence of the water carried along by the pump wheel were also investigated, but proved unimportant in the case of the shaft studied. Experimental results are compared with calculations of critical speed. (orig.)

  10. Variable speed control for Vertical Axis Wind Turbine

    DEFF Research Database (Denmark)

    Galinos, Christos; Larsen, Torben J.

    A robust variable speed control for vertical axis wind turbine applications is implemented. It is a PI rotor speed controller based on an induction generator model operated at variable frequency. The generator dynamics are approximated by a first order differential equation with a prescribed slip....... In order to allow variability in the rotor speed an inverter is assumed which changes the nominal generator speed. Below rated power the optimum tip speed ratio is tracked, while above the power is constrained to rated. The wind speed which is needed in the control it is considered as a known signal...... the Inflow project. The investigation of the VAWT performance under different control parameters such as the PI gains has been performed by Christos Galinos. Deterministic and turbulent wind speed steps of 2 m/s from 6 m/s to 24 m/s and back to 12 m/s are applied. The controller gives smooth transient...

  11. Generating pulsatility by pump speed modulation with continuous-flow total artificial heart in awake calves.

    Science.gov (United States)

    Fukamachi, Kiyotaka; Karimov, Jamshid H; Sunagawa, Gengo; Horvath, David J; Byram, Nicole; Kuban, Barry D; Dessoffy, Raymond; Sale, Shiva; Golding, Leonard A R; Moazami, Nader

    2017-12-01

    The purpose of this study was to evaluate the effects of sinusoidal pump speed modulation of the Cleveland Clinic continuous-flow total artificial heart (CFTAH) on hemodynamics and pump flow in an awake chronic calf model. The sinusoidal pump speed modulations, performed on the day of elective sacrifice, were set at ±15 and ± 25% of mean pump speed at 80 bpm in four awake calves with a CFTAH. The systemic and pulmonary arterial pulse pressures increased to 12.0 and 12.3 mmHg (±15% modulation) and to 15.9 and 15.7 mmHg (±25% modulation), respectively. The pulsatility index and surplus hemodynamic energy significantly increased, respectively, to 1.05 and 1346 ergs/cm at ±15% speed modulation and to 1.51 and 3381 ergs/cm at ±25% speed modulation. This study showed that it is feasible to generate pressure pulsatility with pump speed modulation; the platform is suitable for evaluating the physiologic impact of pulsatility and allows determination of the best speed modulations in terms of magnitude, frequency, and profiles.

  12. The economics of a variable speed wind-diesel

    International Nuclear Information System (INIS)

    Moll, W.

    1992-01-01

    A remote community power supply system generating over 1,000 kWH/d will have at least one diesel generator running all the time. If one or more wind turbine generators are added to such a system, the diesel generator will produce less power when wind speeds are adequate, but its fuel efficiency will gradually decrease as load decreases. In the variable speed wind/diesel concept, the diesel rpm is reduced with decreasing load and a high fuel efficiency is maintained over virtually the full power range. The outputs of the diesel and wind turbine generators are fed into an inverter which synthesizes a desired voltage wave-shape with controlled magnitude and frequency. The variable speed wind/diesel concept may make vertical axis wind turbines suitable for remote community power supply because the inverter effectively isolates the power ripple of the wind turbine. A possible wind/diesel system configuration using the variable speed concept is illustrated. The economics of a 50-kW variable speed diesel and a 80-kW variable speed wind turbine generator was analyzed. Going from a constant speed diesel generator to a variable speed generator operating at 55% capacity factor, a 6% fuel saving was achieved. Adding one 80-kW wind turbine increased fuel savings to 32% at 5 m/s wind speed, but the unit energy cost rose 8.5%. At 7 m/s wind speed, fuel savings were 59% and energy savings were 7.8%. Economics are better for a peaking variable speed 50-kW wind/diesel system added to an existing diesel system to extend the installed capacity. At 7 m/s wind speed the fuel savings translate into ca $40,000 over 10 y and purchase of a $150,000 diesel generator is postponed. 7 figs., 1 tab

  13. Numerical Investigation on a Prototype Centrifugal Pump Subjected to Fluctuating Rotational Speed

    Directory of Open Access Journals (Sweden)

    Yu-Liang Zhang

    2014-01-01

    Full Text Available The rotational speed of pumps often encounters fluctuation in engineering for some reasons. In this paper, in order to study the transient response characteristic of a prototype centrifugal pump subjected to fluctuating rotational speed, a closed-loop pipe system including the pump is built to accomplish unsteady flow calculations in which the boundary conditions at the inlet and the outlet of the pump are not required to be set. The external performance results show that the head’s responsiveness to the fluctuating rotational speed is very good, while the flow rate’s responsiveness is slightly delayed. The variation tendencies of the static pressures at the inlet and the outlet of the pump are almost completely opposite, wherein the variation tendency of the static pressure at the outlet is identical with that of the rotational speed. The intensity of the turbulence energy in each impeller channel is relatively uniform in the transient flow calculations, while, in the quasi-steady flow calculation, it becomes weaker in a channel closed to the volute tongue. The nondimensional flow rate and head coefficients are dependent on the rotational speed, and their variation tendencies are opposite to that of the fluctuating rotational speed as a whole.

  14. Control and calculation of the titanium sublimation pumping speed and re-ionisation in the MAST neutral beam injectors

    International Nuclear Information System (INIS)

    McAdams, R.

    2015-01-01

    Highlights: • The titanium sublimation pumps for the MAST neutral beam injectors are described. • Evaporation regimes are established to give constant pumping speed for the titanium sublimation pumps. • The MCNP code is used to calculate the pumping speeds and gas profiles in the neutral beam injectors. • The gas profiles are then used to calculate the level of re-ionisation in the beamline. - Abstract: A high pumping speed is required in neutral beam injectors to minimise re-ionisation of the neutral beams. The neutral beam injectors on MAST use titanium sublimation pumps. These pumps do not have a constant pumping speed; their pumping speed depends on the gettering surface history and on both the integrated and applied gas load. In this paper we describe a method of maintaining a constant pumping speed, through different evaporation schemes, specifically suitable for operations of the MAST neutral beam injector beamlines for both short and relatively long beam pulses by measurement of the pressure in the beamline. In addition the MCNP code is then used to calculate the pumping speed and gas profile in the beamline by adjusting the input pumping speed to match the measured pressure. This allows the resulting gas profile to be used for calculation of the re-ionisation levels and an example is given

  15. Investigation of load reduction for a variable speed, variable pitch, and variable coning wind turbine

    Energy Technology Data Exchange (ETDEWEB)

    Pierce, K. [Univ. of Utah, Salt Lake City, UT (United States)

    1997-12-31

    A two bladed, variable speed and variable pitch wind turbine was modeled using ADAMS{reg_sign} to evaluate load reduction abilities of a variable coning configuration as compared to a teetered rotor, and also to evaluate control methods. The basic dynamic behavior of the variable coning turbine was investigated and compared to the teetered rotor under constant wind conditions as well as turbulent wind conditions. Results indicate the variable coning rotor has larger flap oscillation amplitudes and much lower root flap bending moments than the teetered rotor. Three methods of control were evaluated for turbulent wind simulations. These were a standard IPD control method, a generalized predictive control method, and a bias estimate control method. Each control method was evaluated for both the variable coning configuration and the teetered configuration. The ability of the different control methods to maintain the rotor speed near the desired set point is evaluated from the RMS error of rotor speed. The activity of the control system is evaluated from cycles per second of the blade pitch angle. All three of the methods were found to produce similar results for the variable coning rotor and the teetered rotor, as well as similar results to each other.

  16. Hydraulic performance of a low specific speed centrifugal pump with Spanwise-Slotted Blades

    International Nuclear Information System (INIS)

    Ye, D X; Li, H; Wang, Y

    2013-01-01

    The hydraulic efficiency of a low specific speed centrifugal pump is low because of the long and narrow meridian flow passage, and the severe disk friction. Spanwise slotted blade flow control technology has been applied to the low specific speed centrifugal pump. This paper concluded that spanwise slotted blades can improve the pump performance in both experiments and simulations. In order to study the influence to the impeller and volute by spanwise slotted blade, impeller efficiency and volute efficiency were defined. The minimum volute efficiency and the maximum pump efficiency appear at the same time in the design flow condition in the unsteady simulation. The mechanism of spanwise slotted blade flow control technology should be researched furthermore

  17. High-Speed Photo-Polarimetry of Magnetic Cataclysmic Variables

    Directory of Open Access Journals (Sweden)

    S. B. Potter

    2015-02-01

    Full Text Available I review recent highlights of the SAAO High-speed Photo-POlarimeter (HIPPO on the study of magnetic Cataclysmic Variables. Its high-speed capabilities are demonstrated with example observations made of the intermediate polar NY Lup and the polar IGRJ14536-5522.

  18. Critical Speed Control for a Fixed Blade Variable Speed Wind Turbine

    Directory of Open Access Journals (Sweden)

    Morgan Rossander

    2017-10-01

    Full Text Available A critical speed controller for avoiding a certain rotational speed is presented. The controller is useful for variable speed wind turbines with a natural frequency in the operating range. The controller has been simulated, implemented and tested on an open site 12 kW vertical axis wind turbine prototype. The controller is based on an adaptation of the optimum torque control. Two lookup tables and a simple state machine provide the control logic of the controller. The controller requires low computational resources, and no wind speed measurement is needed. The results suggest that the controller is a feasible method for critical speed control. The skipping behavior can be adjusted using only two parameters. While tested on a vertical axis wind turbine, it may be used on any variable speed turbine with the control of generator power.

  19. Pitch Angle Control for Variable Speed Wind Turbines

    DEFF Research Database (Denmark)

    Chen, Zhe; Zhang, Jianzhong; Cheng, M

    2008-01-01

    Pitch angle control is the most common means for adjusting the aerodynamic torque of the wind turbine when wind speed is above rated speed and various controlling variables may be chosen, such as wind speed, generator speed and generator power. As conventional pitch control usually use PI...... controller, the mathematical model of the system should be known well. A fuzzy logic pitch angle controller is developed in this paper, in which it does not need well known about the system and the mean wind speed is used to compensate the non-linear sensitivity. The fuzzy logic control strategy may have...... the potential when the system contains strong non-linearity, such as wind turbulence is strong, or the control objectives include fatigue loads. The design of the fuzzy logic controller and the comparisons with conversional pitch angle control strategies with various controlling variables are carried out...

  20. Development and numerical analysis of low specific speed mixed-flow pump

    International Nuclear Information System (INIS)

    Li, H F; Huo, Y W; Pan, Z B; Zhou, W C; He, M H

    2012-01-01

    With the development of the city, the market of the mixed flow pump with large flux and high head is prospect. The KSB Shanghai Pump Co., LTD decided to develop low speed specific speed mixed flow pump to meet the market requirements. Based on the centrifugal pump and axial flow pump model, aiming at the characteristics of large flux and high head, a new type of guide vane mixed flow pump was designed. The computational fluid dynamics method was adopted to analyze the internal flow of the new type model and predict its performances. The time-averaged Navier-Stokes equations were closed by SST k-ω turbulent model to adapt internal flow of guide vane with larger curvatures. The multi-reference frame(MRF) method was used to deal with the coupling of rotating impeller and static guide vane, and the SIMPLEC method was adopted to achieve the coupling solution of velocity and pressure. The computational results shows that there is great flow impact on the head of vanes at different working conditions, and there is great flow separation at the tailing of the guide vanes at different working conditions, and all will affect the performance of pump. Based on the computational results, optimizations were carried out to decrease the impact on the head of vanes and flow separation at the tailing of the guide vanes. The optimized model was simulated and its performance was predicted. The computational results show that the impact on the head of vanes and the separation at the tailing of the guide vanes disappeared. The high efficiency of the optimized pump is wide, and it fit the original design destination. The newly designed mixed flow pump is now in modeling and its experimental performance will be getting soon.

  1. Development and numerical analysis of low specific speed mixed-flow pump

    Science.gov (United States)

    Li, H. F.; Huo, Y. W.; Pan, Z. B.; Zhou, W. C.; He, M. H.

    2012-11-01

    With the development of the city, the market of the mixed flow pump with large flux and high head is prospect. The KSB Shanghai Pump Co., LTD decided to develop low speed specific speed mixed flow pump to meet the market requirements. Based on the centrifugal pump and axial flow pump model, aiming at the characteristics of large flux and high head, a new type of guide vane mixed flow pump was designed. The computational fluid dynamics method was adopted to analyze the internal flow of the new type model and predict its performances. The time-averaged Navier-Stokes equations were closed by SST k-ω turbulent model to adapt internal flow of guide vane with larger curvatures. The multi-reference frame(MRF) method was used to deal with the coupling of rotating impeller and static guide vane, and the SIMPLEC method was adopted to achieve the coupling solution of velocity and pressure. The computational results shows that there is great flow impact on the head of vanes at different working conditions, and there is great flow separation at the tailing of the guide vanes at different working conditions, and all will affect the performance of pump. Based on the computational results, optimizations were carried out to decrease the impact on the head of vanes and flow separation at the tailing of the guide vanes. The optimized model was simulated and its performance was predicted. The computational results show that the impact on the head of vanes and the separation at the tailing of the guide vanes disappeared. The high efficiency of the optimized pump is wide, and it fit the original design destination. The newly designed mixed flow pump is now in modeling and its experimental performance will be getting soon.

  2. Flicker Mitigation by Speed Control of Permanent Magnet Synchronous Generator Variable-Speed Wind Turbines

    DEFF Research Database (Denmark)

    Hu, Weihao; Zhang, Yunqian; Chen, Zhe

    2013-01-01

    operation. A new method of flicker mitigation by controlling the rotational speed is proposed. It smoothes the 3p active power oscillations from wind shear and tower shadow effects of the wind turbine by varying the rotational speed of the PMSG. Simulation results show that damping the 3p active power...... oscillation by using the flicker mitigation speed controller is an effective means for flicker mitigation of variable speed wind turbines with full-scale back-to-back power converters and PMSG during continuous operation.......Grid-connected wind turbines are fluctuating power sources that may produce flicker during continuous operation. This paper presents a simulation model of a MW-level variable speed wind turbine with a full-scale back-to-back power converter and permanent magnet synchronous generator (PMSG...

  3. Applicability of eddy viscosity turbulence models in low specific speed centrifugal pump

    International Nuclear Information System (INIS)

    Wang, Y; Wang, W J

    2012-01-01

    The accuracy of numerical simulation determines the performance prediction whether to be successful or not in the research of centrifugal pump. In order to study the applicability of different turbulence models in the low specific speed centrifugal pump, the object was based on XST45-200 stamping and welding centrifugal pump. Five different kinds of standards which are k-ε model, RNG k-ε model, Realizable k-ε model, Standard k-ω model and SST k-ω model are adopted in steady numerical simulations of the centrifugal pump flow fields. Then, inner and outside characteristics of the centrifugal pump were gotten .And it also provides the calculation of pressure distribution using different turbulence models in the five conditions. Lastly, the performance curves of head, power and efficiency are compared with the test. The results show a good agreement between five kinds of turbulence models and tests obtained in small flow and design condition. In large flow, the standard k-ε model is worse than the other four, which is larger than the tested head with a relative deviation of 47.9% and efficiency with 50%.The calculation accuracy which used RNG k-ε model is highest. SST k-ω model takes the second place. Standard k-ω model can be used for the numerical simulation in the low specific speed centrifugal pump.

  4. Survey of variable speed operation of wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, Ola; Hylander, J.; Thorborg, K. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Electric Power Engineering

    1996-12-01

    During the last five years the production and operation of variable-speed wind turbines have advanced from a few experimental machines to a serial production of at least 10 MW of installed capacity of variable speed machines per week. The rated power of serial wind turbines is today around 600 kW and for the prototypes up to 3000 kW. Variable speed operation of wind turbines can be obtained with several different types of electrical generating systems, such as synchronous generators with diode rectifiers and thyristor inverters or induction generators with IGBT-converters, for the wide speed range. For the narrow speed range the wound motor induction generator with a rotor cascade or a controlled rotor resistance is preferable. The development of permanent magnetic material and the reduction of costs of the power electronic components have opened a possibility of designing cost-effective wind turbines with a directly driven generator. Pitch control together with variable speed will make it possible to limit the power variation within a few percent, 2 to 5 %, of the rated power. 7 refs, 4 figs, 2 tabs

  5. Replumbing of the Biological Pump caused by Millennial Climate Variability

    Science.gov (United States)

    Galbraith, E.; Sarmiento, J.

    2008-12-01

    It has been hypothesized that millennial-timescale variability in the biological pump was a critical instigator of glacial-interglacial cycles. However, even in the absence of changes in ecosystem function (e.g. due to iron fertilization), determining the mechanisms by which physical climate variability alters the biological pump is not simple. Changes in upper ocean circulation and deep water formation have previously been shown to alter both the downward flux of organic matter and the mass of respired carbon in the ocean interior, often in non- intuitive ways. For example, a reduced upward flux of nutrients at the global scale will decrease the global rate of export production, but it could either increase or decrease the respired carbon content of the ocean interior, depending on where the reduced upward flux of nutrients occurs. Furthermore, viable candidates for physical climate forcing are numerous, including changes in the westerly winds, changes in the depth of the thermocline, and changes in the formation rate of North Atlantic Deep Water, among others. We use a simple, prognostic, light-and temperature-dependent model of biogeochemical cycling within a state-of-the- art global coupled ocean-atmosphere model to examine the response of the biological pump to changes in the coupled Earth system over multiple centuries. The biogeochemical model explicitly distinguishes respired carbon from preformed and saturation carbon, allowing the activity of the biological pump to be clearly quantified. Changes are forced in the model by altering the background climate state, and by manipulating the flux of freshwater to the North Atlantic region. We show how these changes in the physical state of the coupled ocean-atmosphere system impact the distribution and mass of respired carbon in the ocean interior, and the relationship these changes bear to global patterns of export production via the redistribution of nutrients.

  6. Variable current speed controller for eddy current motors

    Science.gov (United States)

    Gerth, H.L.; Bailey, J.M.; Casstevens, J.M.; Dixon, J.H.; Griffith, B.O.; Igou, R.E.

    1982-03-12

    A speed control system for eddy current motors is provided in which the current to the motor from a constant frequency power source is varied by comparing the actual motor speed signal with a setpoint speed signal to control the motor speed according to the selected setpoint speed. A three-phase variable voltage autotransformer is provided for controlling the voltage from a three-phase power supply. A corresponding plurality of current control resistors is provided in series with each phase of the autotransformer output connected to inputs of a three-phase motor. Each resistor is connected in parallel with a set of normally closed contacts of plurality of relays which are operated by control logic. A logic circuit compares the selected speed with the actual motor speed obtained from a digital tachometer monitoring the motor spindle speed and operated the relays to add or substract resistance equally in each phase of the motor input to vary the motor current to control the motor at the selected speed.

  7. Improving transition between power optimization and power limitation of variable speed/variable pitch wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, A D; Bindner, H [Risoe National Lab., Wind Energy and Atmospheric Physics Dept., Roskilde (Denmark); Rebsdorf, A [Vestas Wind Systems A/S, Lem (Denmark)

    1999-03-01

    The paper summarises and describes the main results of a recently performed study of improving the transition between power optimization and power limitation for variable speed/variable pitch wind turbines. The results show that the capability of varying the generator speed also can be exploited in the transition stage to improve the quality of the generated power. (au)

  8. Investigation of the Hydrodynamics of Sweep Blade in Hi-Speed Axial Fuel Pump Impeller

    Directory of Open Access Journals (Sweden)

    Ran Tao

    2013-01-01

    Full Text Available Fuel pump is a crucial component in aircraft engine ignition system. For the hi-speed axial fuel pumps, rotating stall triggers vortex and affects the operation stability and security. Sweep blade is widely used to solve the stability problems in aerodynamics field. Investigation on the hydrodynamics was conducted in this study. Based on the typical straight blade pump, positive and negative sweep blade pumps were modeled. With the large eddy simulation method, CFD simulations were conducted to calculate and analyze the flow characteristics in the pump models. To verify the simulation, experiments were also launched on the hydraulic test rig. Results show that the vortex occurs at the suction surface of blade and gathers near the blade tip region. Positive sweep blade is effective to reduce the hydraulic losses by driving the stalled fluid into the mid-part of blade. By applying the positive sweep blade on the axial fuel pump, the instability operating region will be diminished. Adopting sweep blade provides an effective means for stability and security of axial fuel pumps.

  9. Observer Backstepping Control for Variable Speed Wind Turbine

    DEFF Research Database (Denmark)

    Galeazzi, Roberto; Gryning, Mikkel Peter Sidoroff; Blanke, Mogens

    2013-01-01

    . The nonlinear controller aims at regulating the generator torque such that an optimal tip-speed ratio can be obtained. Simply relying on the measured rotor angular velocity the proposed observer backstepping controller guarantees global asymptotic tracking of the desired trajectory while maintaining a globally......This paper presents an observer backstepping controller as feasible solution to variable speed control of wind turbines to maximize wind power capture when operating between cut-in and rated wind speeds. The wind turbine is modeled as a two-mass drive-train system controlled by the generator torque...

  10. Overview of Variable-Speed Power-Turbine Research

    Science.gov (United States)

    Welch, Gerard E.

    2011-01-01

    The vertical take-off and landing (VTOL) and high-speed cruise capability of the NASA Large Civil Tilt-Rotor (LCTR) notional vehicle is envisaged to enable increased throughput in the national airspace. A key challenge of the LCTR is the requirement to vary the main rotor speeds from 100% at take-off to near 50% at cruise as required to minimize mission fuel burn. The variable-speed power-turbine (VSPT), driving a fixed gear-ratio transmission, provides one approach for effecting this wide speed variation. The key aerodynamic and rotordynamic challenges of the VSPT were described in the FAP Conference presentation. The challenges include maintaining high turbine efficiency at high work factor, wide (60 deg.) of incidence variation in all blade rows due to the speed variation, and operation at low Reynolds numbers (with transitional flow). The PT -shaft of the VSPT must be designed for safe operation in the wide speed range required, and therefore poses challenges associated with rotordynamics. The technical challenges drive research activities underway at NASA. An overview of the NASA SRW VSPT research activities was provided. These activities included conceptual and preliminary aero and mechanical (rotordynamics) design of the VSPT for the LCTR application, experimental and computational research supporting the development of incidence tolerant blading, and steps toward component-level testing of a variable-speed power-turbine of relevance to the LCTR application.

  11. SPEED COMPLIANCE IN FREEWAY VARIABLE SPEED LIMIT SYSTEM – CASE STUDY OF THE PRAGUE CITY RING

    Directory of Open Access Journals (Sweden)

    Michał MATOWICKI

    2016-03-01

    Full Text Available Many previous studies have confirmed the strong relationship between speed compliance and the frequency and severity of traffic accidents. Variable speed limit (VSL system as a measure to improve traffic safety enables the freeway system to change its posted speed limit based on various traffic and environmental conditions. Such system helps drivers to recognize the upcoming events, to adjust their driving style and in such way to address speed variation of the traffic flow. This is called speed harmonization. Although many studies researching the effect of VSL system on the traffic stream can be found, there are only few addressing its influence on the drivers behavior, particularly focusing on their tolerance limit and compliance, which has crucial meaning for future design of controlling algorithms. This study was prepared to inspect this grey area by studying the data from the VSL system at Prague city ring, describing the influence of the highway management system and its influence on drivers.

  12. Flicker Mitigation by Speed Control of Permanent Magnet Synchronous Generator Variable-Speed Wind Turbines

    Directory of Open Access Journals (Sweden)

    Yanting Hu

    2013-07-01

    Full Text Available Grid-connected wind turbines are fluctuating power sources that may produce flicker during continuous operation. This paper presents a simulation model of a MW-level variable speed wind turbine with a full-scale back-to-back power converter and permanent magnet synchronous generator (PMSG developed in the simulation tool of PSCAD/EMTDC. Flicker emission of this system is investigated. The 3p (three times per revolution power oscillation due to wind shear and tower shadow effects is the significant part in the flicker emission of variable speed wind turbines with PMSG during continuous operation. A new method of flicker mitigation by controlling the rotational speed is proposed. It smoothes the 3p active power oscillations from wind shear and tower shadow effects of the wind turbine by varying the rotational speed of the PMSG. Simulation results show that damping the 3p active power oscillation by using the flicker mitigation speed controller is an effective means for flicker mitigation of variable speed wind turbines with full-scale back-to-back power converters and PMSG during continuous operation.

  13. Exterior rotor permanent magnet generator in variable speed applications

    OpenAIRE

    Sattar, Rauf

    2016-01-01

    This thesis explores approaches for converting rotational mechanical power from diesel engines into electrical power of fixed frequency and voltage. Advances in high energy permanent magnets and power electronics are enabling technologies that provide opportunities for electrical machines with increased efficiency and compact size for variable speed power generation. The overall objective was to design a permanent magnet machine with concentrated winding that could be used in variable spe...

  14. Investigation on Flow-Induced Noise due to Backflow in Low Specific Speed Centrifugal Pumps

    Directory of Open Access Journals (Sweden)

    Qiaorui Si

    2013-01-01

    Full Text Available Flow-induced noise causes disturbances during the operation of centrifugal pumps and also affects their performance. The pumps often work at off-design conditions, mainly at part-load conditions, because of frequent changes in the pump device system. Consequently numerous unstable phenomena occur. In low specific speed centrifugal pumps the main disturbance is the inlet backflow, which is considered as one of the most important factors of flow-induced noise and vibration. In this study, a test rig of the flow-induced noise and vibration of the centrifugal pump was built to collect signals under various operating conditions. The three-dimensional unsteady flow of centrifugal pumps was calculated based on the Reynolds-averaged equations that resemble the shear stress transport (SST k-ω turbulence model. The results show that the blade passing frequency and shaft frequency are dominant in the spectrum of flow-induced noise, whereas the shaft component, amplitude value at shaft frequency, and peak frequencies around the shaft increase with decreasing flow. Through flow field analysis, the inlet backflow of the impeller occurs under 0.7 times the design flow. The pressure pulsation spectrum with backflow conditions validates the flow-induced noise findings. The velocity characteristics of the backflow zone at the inlet pipe were analyzed, and the dynamic characteristics of the backflow eddy during one impeller rotating period were simultaneously obtained by employing the backflow conditions. A flow visualization experiment was performed to confirm the numerical calculations.

  15. Active surge control for variable speed axial compressors.

    Science.gov (United States)

    Lin, Shu; Yang, Chunjie; Wu, Ping; Song, Zhihuan

    2014-09-01

    This paper discusses active surge control in variable speed axial compressors. A compression system equipped with a variable area throttle is investigated. Based on a given compressor model, a fuzzy logic controller is designed for surge control and a proportional speed controller is used for speed control. The fuzzy controller uses measurements of the change of pressure rise as well as the change of mass flow to determine the throttle opening. The presented approach does not require the knowledge of system equilibrium or the surge line. Numerical simulations show promising results. The proposed fuzzy logic controller performs better than a backstepping controller and is capable to suppress surge at different operating points. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

  16. Variable speed hermetic reciprocating compressors for domestic refrigerators

    DEFF Research Database (Denmark)

    Rasmussen, Bjarne D.

    1998-01-01

    This article describes the results of a both theoretical and experimental investigation of the performance of variable speed hermetic reciprocating compressors for domestic refrigerators. The investigation was performed as a part of a larger research project with the objective of reducing...

  17. LQG Controller Design for Pitch Regulated Variable Speed Wind Turbine

    DEFF Research Database (Denmark)

    Imran, Raja Muhammed; Hussain, Dil Muhammad Akbar; Chen, Zhe

    2014-01-01

    Variable speed wind turbine is a complex and nonlinear system, a sophisticated control is required to meet the challenges posed by these systems. This paper is presenting a pitch regulation strategy based on LQG (Linear Quadratic Gaussian) to regulate turbine at its rated power and to reject...

  18. An analytical investigation on the valve and centrifugal pump speed control with a constant differential pressure across the valve

    International Nuclear Information System (INIS)

    Jung, B. R.; Joo, K. I.; Lee, B. J.; Baek, S. J.; Noh, T. S.

    2003-01-01

    A valve opening and centrifugal pump speed control was investigated analytically in a simple pumping system where the differential pressure across the control valve is maintained constant over the required flow range. The valve control program was derived analytically only as a function of the required flow rate to maintain the constant differential pressure across the valve. The centrifugal pump speed control program was also derived analytically for the required flow rate for the constant differential pressure across the control valve. These derivations theoretically show that the independent control is possible between the valve and pump speed in a system with a constant valve pressure drop. In addition, it was shown that a linear pump speed control is impossible in maintaining the constant valve pressure drop

  19. Laser Velocimeter Measurements in the Pump of an Automotive Torque Converter Part I – Effect of Speed Ratio

    Directory of Open Access Journals (Sweden)

    Steven B. Ainley

    2000-01-01

    Full Text Available A torque converter was tested at four turbine/pump rotational speed ratios (0.200, 0.400, 0.600, and 0.800 all with a constant pump rotational speed in order to determine the effect of speed ratio on the torque converter pump flow field. Laser velocimetry was used to measure three components of velocity within the pump and a shaft encoder was employed to record the instantaneous pump angular position. Shaft encoder information was correlated with measured velocities to develop flow field blade-to-blade profiles and vector plots. Measurements were obtained in both the pump mid- and exit planes for all four speed ratios. Results showed large separation regions and jet/wake flows throughout the pump. The midplane flow was found to have strong counter-clockwise secondary components and the exit plane flow had strong clockwise secondary components. Mass flows were calculated from the velocity data and were found to decrease as the speed ratio was increased. Also, the vorticity and slip factors were calculated from the experimental data and are included. The mid-plane slip factors compare favorably to those for conventional centrifugal pumps but less slip was present in the exit plane than the mid-plane. Neither the slip factor nor the vorticity were seen to be strongly affected by the speed ratio. Finally, the torque core-to-shell and blade-to-blade torque distributions are presented for both planes.

  20. Walking speed-related changes in stride time variability: effects of decreased speed

    Directory of Open Access Journals (Sweden)

    Dubost Veronique

    2009-08-01

    Full Text Available Abstract Background Conflicting results have been reported regarding the relationship between stride time variability (STV and walking speed. While some studies failed to establish any relationship, others reported either a linear or a non-linear relationship. We therefore sought to determine the extent to which decrease in self-selected walking speed influenced STV among healthy young adults. Methods The mean value, the standard deviation and the coefficient of variation of stride time, as well as the mean value of stride velocity were recorded while steady-state walking using the GAITRite® system in 29 healthy young adults who walked consecutively at 88%, 79%, 71%, 64%, 58%, 53%, 46% and 39% of their preferred walking speed. Results The decrease in stride velocity increased significantly mean values, SD and CoV of stride time (p Conclusion The results support the assumption that gait variability increases while walking speed decreases and, thus, gait might be more unstable when healthy subjects walk slower compared with their preferred walking speed. Furthermore, these results highlight that a decrease in walking speed can be a potential confounder while evaluating STV.

  1. Impellers of low specific speed centrifugal pump based on the draughting technology

    International Nuclear Information System (INIS)

    Hongxun, C; Peiru, W; Weiwei, L; Wen, J

    2010-01-01

    The authors analyzed the reasons of low efficiency under different operation condition based on the performance test and CFD numerical simulation approach. And the analysis focuses on the relationship between pump efficiency and inner flow characteristics. In order to improve the internal flow and increase efficiency of the pump, some draughting methods of improving the internal flow structure have been proposed, and some new impellers were developed by these methods. The main geometric parameters of the impellers, such as diameter, width and installation of the size, were consistent with the original impeller. The experimental results show that the efficiency of new impellers was improved significantly. The authors' work has opened up a new direction for further improving the efficiency of the low specific speed centrifugal pump.

  2. Dynamic Modeling of Adjustable-Speed Pumped Storage Hydropower Plant: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, E.; Singh, M.; Gevorgian, V.; Mohanpurkar, M.; Havsapian, R.; Koritarov, V.

    2015-04-06

    Hydropower is the largest producer of renewable energy in the U.S. More than 60% of the total renewable generation comes from hydropower. There is also approximately 22 GW of pumped storage hydropower (PSH). Conventional PSH uses a synchronous generator, and thus the rotational speed is constant at synchronous speed. This work details a hydrodynamic model and generator/power converter dynamic model. The optimization of the hydrodynamic model is executed by the hydro-turbine controller, and the electrical output real/reactive power is controlled by the power converter. All essential controllers to perform grid-interface functions and provide ancillary services are included in the model.

  3. High-speed off-axis holographic cinematography with a copper-vapor-pumped dye laser.

    Science.gov (United States)

    Lauterborn, W; Judt, A; Schmitz, E

    1993-01-01

    A series of coherent light pulses is generated by pumping a dye laser with the pulsed output of a copper-vapor laser at rates of as much as 20 kHz. Holograms are recorded at this pulse rate on a rotating holographic plate. This technique of high-speed holographic cinematography is demonstrated by viewing the bubble filaments that appear in water under the action of a sound field of high intensity.

  4. Variable sound speed in interacting dark energy models

    Science.gov (United States)

    Linton, Mark S.; Pourtsidou, Alkistis; Crittenden, Robert; Maartens, Roy

    2018-04-01

    We consider a self-consistent and physical approach to interacting dark energy models described by a Lagrangian, and identify a new class of models with variable dark energy sound speed. We show that if the interaction between dark energy in the form of quintessence and cold dark matter is purely momentum exchange this generally leads to a dark energy sound speed that deviates from unity. Choosing a specific sub-case, we study its phenomenology by investigating the effects of the interaction on the cosmic microwave background and linear matter power spectrum. We also perform a global fitting of cosmological parameters using CMB data, and compare our findings to ΛCDM.

  5. Considering Variable Road Geometry in Adaptive Vehicle Speed Control

    Directory of Open Access Journals (Sweden)

    Xinping Yan

    2013-01-01

    Full Text Available Adaptive vehicle speed control is critical for developing Advanced Driver Assistance Systems (ADAS. Vehicle speed control considering variable road geometry has become a hotspot in ADAS research. In this paper, first, an exploration of intrinsic relationship between vehicle operation and road geometry is made. Secondly, a collaborative vehicle coupling model, a road geometry model, and an AVSC, which can respond to variable road geometry in advance, are developed. Then, based on H∞ control method and the minimum energy principle, a performance index is specified by a cost function for the proposed AVSC, which can explicitly consider variable road geometry in its optimization process. The proposed AVSC is designed by the Hamilton-Jacobi Inequality (HJI. Finally, simulations are carried out by combining the vehicle model with the road geometry model, in an aim of minimizing the performance index of the AVSC. Analyses of the simulation results indicate that the proposed AVSC can automatically and effectively regulate speed according to variable road geometry. It is believed that the proposed AVSC can be used to improve the economy, comfort, and safety effects of current ADAS.

  6. A conceptual framework for evaluating variable speed generator options for wind energy applications

    Science.gov (United States)

    Reddoch, T. W.; Lipo, T. A.; Hinrichsen, E. N.; Hudson, T. L.; Thomas, R. J.

    1995-01-01

    Interest in variable speed generating technology has accelerated as greater emphasis on overall efficiency and superior dynamic and control properties in wind-electric generating systems are sought. This paper reviews variable speed technology options providing advantages and disadvantages of each. Furthermore, the dynamic properties of variable speed systems are contrasted with synchronous operation. Finally, control properties of variable speed systems are examined.

  7. An Analysis of Variable-Speed Wind Turbine Power-Control Methods with Fluctuating Wind Speed

    Directory of Open Access Journals (Sweden)

    Seung-Il Moon

    2013-07-01

    Full Text Available Variable-speed wind turbines (VSWTs typically use a maximum power-point tracking (MPPT method to optimize wind-energy acquisition. MPPT can be implemented by regulating the rotor speed or by adjusting the active power. The former, termed speed-control mode (SCM, employs a speed controller to regulate the rotor, while the latter, termed power-control mode (PCM, uses an active power controller to optimize the power. They are fundamentally equivalent; however, since they use a different controller at the outer control loop of the machine-side converter (MSC controller, the time dependence of the control system differs depending on whether SCM or PCM is used. We have compared and analyzed the power quality and the power coefficient when these two different control modes were used in fluctuating wind speeds through computer simulations. The contrast between the two methods was larger when the wind-speed fluctuations were greater. Furthermore, we found that SCM was preferable to PCM in terms of the power coefficient, but PCM was superior in terms of power quality and system stability.

  8. Load flow analysis for variable speed offshore wind farms

    DEFF Research Database (Denmark)

    Chen, Zhe; Zhao, Menghua; Blaabjerg, Frede

    2009-01-01

    factors such as the different wind farm configurations, the control of wind turbines and the power losses of pulse width modulation converters are considered. The DC/DC converter model is proposed and integrated into load flow algorithm by modifying the Jacobian matrix. Two iterative methods are proposed...... and integrated into the load flow algorithm: one takes into account the control strategy of converters and the other considers the power losses of converters. In addition, different types of variable speed wind turbine systems with different control methods are investigated. Finally, the method is demonstrated......A serial AC-DC integrated load flow algorithm for variable speed offshore wind farms is proposed. It divides the electrical system of a wind farm into several local networks, and different load flow methods are used for these local networks sequentially. This method is fast, more accurate, and many...

  9. Adaptive Torque Control of Variable Speed Wind Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, K. E.

    2004-08-01

    The primary focus of this work is a new adaptive controller that is designed to resemble the standard non-adaptive controller used by the wind industry for variable speed wind turbines below rated power. This adaptive controller uses a simple, highly intuitive gain adaptation law designed to seek out the optimal gain for maximizing the turbine's energy capture. It is designed to work even in real, time-varying winds.

  10. Effects of impeller diameter and rotational speed on performance of pump running in turbine mode

    International Nuclear Information System (INIS)

    Jain, Sanjay V.; Swarnkar, Abhishek; Motwani, Karan H.; Patel, Rajesh N.

    2015-01-01

    Highlights: • Experiments done between 900 and 1500 rpm with original, 10% and 20% trimmed impellers. • The performance of PAT was found better in speed range of 1000–1200 rpm. • Blade rounding led to 3–4% rise in efficiency at rated speed with existing impeller. • Correlation developed has predicted η BEP within ±10% of experimental results. - Abstract: The major limitations of mini/micro hydropower schemes is the higher cost of small capacity hydro turbines. Also, it is very cumbersome, time consuming and expensive to develop the site specific turbines corresponding to local site conditions in mini/micro hydro range. In such plants, small centrifugal pumps can be used in turbine mode by running in the reverse direction. The efficiency of pump as turbines (PATs) is usually lower than the conventional hydro turbines; however, there may be substantial decrease in the capital cost of the plant. Hydropower plants usually runs at part load for several months in a year due to insufficient water availability for the power generation. The application range of PAT can be widened if its part load and/or maximum efficiency can be improved. In the present study, experimental investigations are carried out on centrifugal pump running in turbine mode to optimize its geometric and operational parameters e.g. impeller diameter and rotational speed. The experiments were performed in the wide range of rotational speeds varying from 900 to 1500 rpm with original (∅ 250 mm), 10% trimmed (∅ 225 mm) and 20% trimmed (∅ 200 mm) impellers. Impeller trimming led to improvement in efficiency at part load operating conditions. The performance of PAT was found better at the lower speeds than that at the rated speed. The effects of blade rounding were studied in all the cases and it led to 3–4% rise in efficiency at rated speed with the original impeller. The empirical correlation is also developed for prediction of efficiency in terms of impeller diameter and rotational

  11. Intelligent control for large-scale variable speed variable pitch wind turbines

    Institute of Scientific and Technical Information of China (English)

    Xinfang ZHANG; Daping XU; Yibing LIU

    2004-01-01

    Large-scale wind turbine generator systems have strong nonlinear multivariable characteristics with many uncertain factors and disturbances.Automatic control is crucial for the efficiency and reliability of wind turbines.On the basis of simplified and proper model of variable speed variable pitch wind turbines,the effective wind speed is estimated using extended Kalman filter.Intelligent control schemes proposed in the paper include two loops which operate in synchronism with each other.At below-rated wind speed,the inner loop adopts adaptive fuzzy control based on variable universe for generator torque regulation to realize maximum wind energy capture.At above-rated wind speed, a controller based on least square support vector machine is proposed to adjust pitch angle and keep rated output power.The simulation shows the effectiveness of the intelligent control.

  12. High-speed flow visualization in a pump-turbine under off-design operating conditions

    International Nuclear Information System (INIS)

    Hasmatuchi, V; Roth, S; Botero, F; Avellan, F; Farhat, M

    2010-01-01

    The flow hydrodynamics in a low specific speed radial pump-turbine reduced scale model is experimentally investigated under off-design operating conditions in generating mode. Wall pressure measurements, in the stator, synchronized with high-speed flow visualizations in the vaneless space between the impeller and the guide vanes using air bubbles injection are performed. When starting from the best efficiency point and increasing the runner speed, a significant increase of the pressure fluctuations is observed mainly in channels between wicket gates. The spectral analysis shows a rise of one stall cell, rotating with about 70% of the impeller frequency, at runaway, which further increases as the zero discharge condition is approached. Then a specific image processing technique is detailed and applied to create a synthetic instantaneous view of the flow pattern on the entire guide vanes circumference for an operating point in turbine-brake mode, where backflow and vortices accompany the stall passage.

  13. Numerical comparisons of the performance of a hydraulic coupling with different pump rotational speeds

    International Nuclear Information System (INIS)

    Luo, Y; Feng, L H; Liu, S H; Chen, T J; Fan, H G

    2013-01-01

    A hydraulic coupling is a hydrodynamic device for transmitting rotating mechanical power. It is widely used in the machinery industry because of its advantages of high energy transmission efficiency, shock absorption and good adaptability, etc. In this paper, SIMPLEC algorithm and SST k-ω turbulence model were employed to simulate the steady state flows at operating conditions of two different rotational speeds (3000r/min and 7500 r/min) of the pump of a specified hydraulic coupling model. The results indicate the existence of similarity in the distributions of the flow fields between the two speeds, but the efficiency at the optimum condition is larger with higher rotational speed. It is concluded that the similarity principle of the efficiency of the hydraulic couplings does not apply in this case due to the relatively high rotating speed and small geometric specifications. It is also shown that the radially stratified pressure distribution on the torus section becomes more obvious with larger speed ratios, since the centrifugal movement plays more dominant roles over the circulating movement in these situations. When the speed ratio is small, with the completion of the circulating flow, the pressure distribution presents in a more circular pattern around the neutral zone of the torus section

  14. Tip Speed Ratio Based Maximum Power Tracking Control of Variable Speed Wind Turbines; A Comprehensive Design

    Directory of Open Access Journals (Sweden)

    Murat Karabacak

    2017-08-01

    Full Text Available The most primitive control method of wind turbines used to generate electric energy from wind is the fixed speed control method. With this method, it is not possible that turbine input power is transferred to grid at maximum rate. For this reason, Maximum Power Tracking (MPT schemes are proposed. In order to implement MPT, the propeller has to rotate at a different speed for every different wind speed. This situation has led MPT based systems to be called Variable Speed Wind Turbine (VSWT systems. In VSWT systems, turbine input power can be transferred to grid at rates close to maximum power. When MPT based control of VSWT systems is the case, two important processes come into prominence. These are instantaneously determination and tracking of MPT point. In this study, using a Maximum Power Point Tracking (MPPT method based on tip speed ratio, power available in wind is transferred into grid over a back to back converter at maximum rate via a VSWT system with permanent magnet synchronous generator (PMSG. Besides a physical wind turbine simulator is modelled and simulated. Results show that a time varying MPPT point is tracked with a high performance.

  15. Transient analysis of a variable speed rotary compressor

    International Nuclear Information System (INIS)

    Park, Youn Cheol

    2010-01-01

    A transient simulation model of a rolling piston type rotary compressor is developed to predict the dynamic characteristics of a variable speed compressor. The model is based on the principles of conservation, real gas equations, kinematics of the crankshaft and roller, mass flow loss due to leakage, and heat transfer. For the computer simulation of the compressor, the experimental data were obtained from motor performance tests at various operating frequencies. Using the developed model, re-expansion loss, friction loss, mass flow loss and heat transfer loss is estimated as a function of the crankshaft speed in a variable speed compressor. In addition, the compressor efficiency and energy losses are predicted at various compressor-operating frequencies. Since the transient state of the compressor strongly depends on the system, the developed model is combined with a transient system simulation program to get transient variations of the compression process in the system. Motor efficiency, mechanical efficiency, motor torque and volumetric efficiency are calculated with respect to variation of the driving frequency in a rotary compressor.

  16. Pitch link loads reduction of variable speed rotors by variable tuning frequency fluidlastic isolators

    Directory of Open Access Journals (Sweden)

    Han Dong

    2015-10-01

    Full Text Available To reduce the pitch link loads of variable speed rotors, variable tuning frequency fluidlastic isolators are proposed. This isolator utilizes the variation of centrifugal force due to the change of rotor speed to change the tuning port area ratio, which can change the tuning frequency of the isolator. A rotor model including the model of fluidlastic isolator is coupled with a fuselage model to predict the steady responses of the rotor system in forward flight. The aeroelastic analyses indicate that distinct performance improvement in pitch link load control can be achieved by the utilization of variable frequency isolators compared with the constant tuning frequency isolators. The 4/rev (per revolution pitch link load is observed to be reduced by 87.6% compared with the increase of 56.3% by the constant frequency isolator, when the rotor speed is reduced by 16.7%. The isolation ability at different rotor speeds in different flight states is investigated. To achieve overall load reduction within the whole range of rotor speed, the strategy of the variation of tuning frequency is adjusted. The results indicate that the 4/rev pitch link load within the whole rotor speed range is decreased.

  17. Designing an Electro-Hydraulic Control Module for an Open-Circuit Variable Displacement Pump

    DEFF Research Database (Denmark)

    Pedersen, Henrik Clemmensen; Andersen, Torben Ole; Hansen, Michael Rygaard

    2005-01-01

    , in the form of an electric control signal, under varying working conditions, when having access to engine speed and actual pump pressure. The paper presents a model of both the pump and the control module, along with design considerations on which linear controllers are developed for a worst point......This paper deals with the problem of designing an electric control module for a Sauer-Danfoss Series 45 H-frame open circuit axial piston pump. The purpose of the electric control module is to replace the existing hydro-mechanical (LS) regulator, and enable the pump to follow a reference pressure...

  18. Pumping speed offered by activated carbon at liquid helium temperatures by sorbents adhered to indigenously developed hydroformed cryopanel

    International Nuclear Information System (INIS)

    Gangradey, Ranjana; Mukherjee, Samiran Shanti; Panchal, Paresh; Nayak, Pratik; Agarwal, Jyoti; Rana, Chirag; Kasthurirengan, S; Mishra, Jyoti Shankar; Patel, Haresh; Bairagi, Pawan; Lambade, Vrushabh; Sayani, Reena

    2015-01-01

    Towards the aim of developing a pump with large pumping speed of the order of 1 L/(s-cm 2 ) or above for gases like hydrogen and helium through physical adsorption, development of activated carbon based sorbents like granules, spheres, flocked fibres, knitted and non -knitted cloth was carried out. To investigate the pumping speed offered, a test facility SSCF (Small Scale Cryopump Facility) which can take samples of hydroformed cryopanel (a technology developed in India) of size ∼500 mm × 100 mm was set up as per international standards comprising a dome mounted with gauges, calibrated leak valve, gas analyser, sorbent adhered to cryopanel etc. The cryopanel was shielded by chevron baffles. Pumping speed measurements were carried out for gases like hydrogen, helium and argon at a constant panel temperature in the pressure range of 1×10 -7 to 1×10 -4 mbar, and pumping speed was found to be in the range of 2000 L/s for a pressure range 1×10 -6 to 1×10 -4 mbar, and 4000 L/s for pressure range 1×10 -7 mbar and below for a pumping surface area of ∼1000 cm 2 thus giving an average pumping speed of about 2 L/(s-cm 2 ). Using the Monte Carlo codes SSCF was modelled and simulation studies performed. Parameters like sticking coefficient, capture coefficients affecting the pumping speed were studied. This paper describes the experimental setup of SSCF, experimental results and its correlation with Monte-Carlo simulation. (paper)

  19. Grid impact of variable-speed wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, Aa [Chalmers Univ. of Technology, Dept. of Electric Power Engineering, Goeteborg (Sweden); Soerensen, P [Risoe National Lab., Roskilde (Denmark); Santjer, F [German Wind Energy Inst., DEWI, Wilhelmshaven (Germany)

    1999-03-01

    In this paper the power quality of variable-speed wind turbines equipped with forced-commutated inverters is investigated. Measurements have been taken on the same type of variable-speed wind turbines in Germany and Sweden. The measurements have been analysed according to existing IEC standards. Special attention has been paid to the aggregation of several wind turbines on flicker emission and harmonics. The aggregation has been compared with the summation laws used in the draft IEC 61400-21 `Power Quality Requirements for Grid Connected wind turbines`. The methods for calculating and summing flicker proposed by IEC Standards are reliable. Harmonics and inter-harmonics are treated in IEC 61000-4-7 and IEC 61000-3-6. The methods for summing harmonics and inter-harmonics in IEC 61000-3-6 are applicable to wind turbines. In order to obtain a correct magnitude of the frequency components, the use of a well-defined window width, according to IEC 61000-4-7 Amendment 1 is of a great importance. (au)

  20. Flicker Mitigation by Speed Control of Permanent Magnet Synchronous Generator Variable-Speed Wind Turbines

    OpenAIRE

    Weihao Hu; Yunqian Zhang; Zhe Chen; Yanting Hu

    2013-01-01

    Grid-connected wind turbines are fluctuating power sources that may produce flicker during continuous operation. This paper presents a simulation model of a MW-level variable speed wind turbine with a full-scale back-to-back power converter and permanent magnet synchronous generator (PMSG) developed in the simulation tool of PSCAD/EMTDC. Flicker emission of this system is investigated. The 3p (three times per revolution) power oscillation due to wind shear and tower shadow effects is the sign...

  1. Control of variable speed variable pitch wind turbine based on a disturbance observer

    Science.gov (United States)

    Ren, Haijun; Lei, Xin

    2017-11-01

    In this paper, a novel sliding mode controller based on disturbance observer (DOB) to optimize the efficiency of variable speed variable pitch (VSVP) wind turbine is developed and analyzed. Due to the highly nonlinearity of the VSVP system, the model is linearly processed to obtain the state space model of the system. Then, a conventional sliding mode controller is designed and a DOB is added to estimate wind speed. The proposed control strategy can successfully deal with the random nature of wind speed, the nonlinearity of VSVP system, the uncertainty of parameters and external disturbance. Via adding the observer to the sliding mode controller, it can greatly reduce the chattering produced by the sliding mode switching gain. The simulation results show that the proposed control system has the effectiveness and robustness.

  2. A study on the performance and internal flow characteristics of a very low specific speed centrifugal pump

    International Nuclear Information System (INIS)

    Choi, Young Do; Kurokawa, Junichi; Lee, Young Ho

    2005-01-01

    In the very low specific speed range (n s < 0.25, non-dimensional), the efficiency of centrifugal pump designed by a conventional method is very low in common. Therefore, positive-displacement pumps have long been used widely. Recently, since the centrifugal pumps are becoming higher in rotational speed and smaller in size, there experts to develop a new centrifugal pump with a high performance to replace the positive-displacement pumps. The purpose of this study is to investigate the internal flow characteristics of a very low specific speed centrifugal pump and to examine the effect of internal flow pattern on pump performance. The results show that the theoretical head definition of semi-open impeller should be revised by the consideration of high slip factor in the semi-open impeller, and the leakage flow through the tip clearance results in a large effect on the impeller internal flow. Strong reverse flow at the outlet of semi-open impeller reduces the absolute tangential velocity considerably, and the decreased absolute tangential velocity increases the slip factor with the reduction of theoretical head

  3. Comparison between OpenFOAM CFD & BEM theory for variable speedvariable pitch HAWT

    Directory of Open Access Journals (Sweden)

    ElQatary Islam

    2014-01-01

    Full Text Available OpenFoam is used to compare computational fluid dynamics (CFD with blade element momentum theory (BEM for a variable speed - variable pitch HAWT (Horizontal Axis Wind Turbine. The wind turbine is first designed using the BEM to determine the blade chord, twist and operating conditions. The wind turbine blade has an outer diameter of 14 m, uses a NACA 63–415 profile for the entire blade and root to tip twist distribution of 15deg (Figure 3. The RPM varies from 20–75 for freestream velocities varying between 3–10.5 m/s (variable speed and a constant RPM of 78.78 for velocities ranging between 11–25 m/s (variable pitch. OpenFOAM is used to investigate the wind turbine performance at several operating points including cut-in wind speed (3 m/s, rated wind speed (10.5 m/s and in the variable pitch zone. Simulation results show that in the variable-speed operating range, both CFD and BEM compare reasonably well. This agreement can be attributed to the fact that the complex three-dimensional flow around the turbine blades can be split into two radial segments. For radii less than the mid-span, the flow is three-dimensional, whereas for radii greater than the mid-span, the flow is approximately two-dimensional. Since the majority of the power is produced from sections beyond the mid-span, the agreement between CFD and BEM is reasonable. For the variable-pitch operating range the CFD results and BEM deviate considerably. In this case the majority of the power is produced from the inner sections in which the flow is three-dimensional and can no longer be predicted by the BEM. The results show that differences in pitch angles up to 10deg can result to regulate the power for high wind speeds in the variable-pitch operation zone.

  4. Maximizing Energy Capture of Fixed-Pitch Variable-Speed Wind Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Pierce, K.; Migliore, P.

    2000-08-01

    Field tests of a variable-speed, stall-regulated wind turbine were conducted at a US Department of Energy Laboratory. A variable-speed generating system, comprising a doubly-fed generator and series-resonant power converter, was installed on a 275-kW, downwind, two-blade wind turbine. Gearbox, generator, and converter efficiency were measured in the laboratory so that rotor aerodynamic efficiency could be determined from field measurement of generator power. The turbine was operated at several discrete rotational speeds to develop power curves for use in formulating variable-speed control strategies. Test results for fixed-speed and variable-speed operation are presented along with discussion and comparison of the variable-speed control methodologies. Where possible, comparisons between fixed-speed and variable-speed operation are shown.

  5. Variable flow controls of closed system pumps for energy savings in maritime power systems

    OpenAIRE

    Su, Chun-Lien; Liao, Chi-Hsiang; Chou, Tso-Chu; Chou, Ming-Hung; Guerrero, Josep M.

    2016-01-01

    Pumps are extensively used in maritime industries as marine vessels utilize a wide range of pumps and pumping techniques to transfer and distribute all types of air and fluids. The electrical energy consumed by the various motors accounts for about 70% of a vessel’s total power consumption, and this presents a problem in unique marine environments. Such situations are especially conducive to energy-saving strategies using variable frequency drives (VFDs) in centrifugal load service. This pape...

  6. Statistical analysis of nuclear power plant pump failure rate variability: some preliminary results

    International Nuclear Information System (INIS)

    Martz, H.F.; Whiteman, D.E.

    1984-02-01

    In-Plant Reliability Data System (IPRDS) pump failure data on over 60 selected pumps in four nuclear power plants are statistically analyzed using the Failure Rate Analysis Code (FRAC). A major purpose of the analysis is to determine which environmental, system, and operating factors adequately explain the variability in the failure data. Catastrophic, degraded, and incipient failure severity categories are considered for both demand-related and time-dependent failures. For catastrophic demand-related pump failures, the variability is explained by the following factors listed in their order of importance: system application, pump driver, operating mode, reactor type, pump type, and unidentified plant-specific influences. Quantitative failure rate adjustments are provided for the effects of these factors. In the case of catastrophic time-dependent pump failures, the failure rate variability is explained by three factors: reactor type, pump driver, and unidentified plant-specific influences. Finally, point and confidence interval failure rate estimates are provided for each selected pump by considering the influential factors. Both types of estimates represent an improvement over the estimates computed exclusively from the data on each pump

  7. A Step Towards Electric Propulsion Testing Standards: Pressure Measurements and Effective Pumping Speeds

    Science.gov (United States)

    Dankanich, John W.; Swiatek, Michael W.; Yim, John T.

    2012-01-01

    The electric propulsion community has been implored to establish and implement a set of universally applicable test standards during the research, development, and qualification of electric propulsion systems. Existing practices are fallible and result in testing variations which leads to suspicious results, large margins in application, or aversion to mission infusion. Performance measurements and life testing under appropriate conditions can be costly and lengthy. Measurement practices must be consistent, accurate, and repeatable. Additionally, the measurements must be universally transportable across facilities throughout the development, qualification, spacecraft integration and on-orbit performance. A preliminary step to progress towards universally applicable testing standards is outlined for facility pressure measurements and effective pumping speed calculations. The standard has been applied to multiple facilities at the NASA Glenn Research Center. Test results and analyses of universality of measurements are presented herein.

  8. Pump speed modulations and sub-maximal exercise tolerance in left ventricular assist device recipients

    DEFF Research Database (Denmark)

    Jung, Mette Holme; Houston, Brian; Russell, Stuart D

    2017-01-01

    of the 2 sub-maximal tests was determined by randomization. Both patient and physician were blinded to the sequence. Exercise duration, oxygen consumption (VO2) and rate of perceived exertion (RPE), using the Borg scale (score 6 to 20), were recorded. RESULTS: Nineteen patients (all with a HeartMate II...... ventricular assist device) completed 57 exercise tests. Baseline pump speed was 9,326 ± 378 rpm. At AT, workload was 63 ± 26 W (25 to 115 W) and VO2 was 79 ± 14% of maximum. Exercise duration improved by 106 ± 217 seconds (~13%) in Speedinc compared with Speedbase (837 ± 358 vs 942 ± 359 seconds; p = 0...

  9. Reconfigurable Charge Pump Circuit with Variable Pumping Frequency Scheme for Harvesting Solar Energy under Various Sunlight Intensities

    Directory of Open Access Journals (Sweden)

    Jeong Heon Kim

    2014-01-01

    Full Text Available We propose variable pumping frequency (VPF scheme which is merged with the previous reconfigurable charge pump (RCP circuit that can change its architecture according to a given sunlight condition. Here, merging the VPF scheme with the architecture reconfiguration can improve percentage output currents better by 21.4% and 22.4% than RCP circuit with the fixed pumping frequencies of 7 MHz and 15 MHz, respectively. Comparing the VPF scheme with real maximum power points (MPP, the VPF can deliver 91.9% of the maximum amount of output current to the load on average. In terms of the power and area overheads, the VPF scheme proposed in this paper consumes the power by 0.4% of the total power consumption and occupies the layout area by 1.61% of the total layout area.

  10. The Benefit of Variable-Speed Turbine Operation for Low Temperature Thermal Energy Power Recovery

    OpenAIRE

    Brasz, Joost J.

    2014-01-01

    This paper analyzes, given the large variation in turbine discharge pressure with changing ambient temperatures, whether variable-speed radial-inflow turbine operation has a similar benefit for Organic Rankine Cycle (ORC) power recovery systems as variable-speed centrifugal compression has for chiller applications. The benefit of variable-speed centrifugal compression over fixed-speed operation is a reduction in annual electricity consumption of almost 40 %. Air-conditioning systems are by ne...

  11. Power system integration and control of variable speed wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Eek, Jarle

    2009-12-15

    A wind power plant is a highly dynamic system that dependent on the type of technology requires a number of automatic control loops. This research deals with modelling, control and analysis related to power system integration of variable speed, pitch controlled wind turbines. All turbine components have been modelled and implemented in the power system simulation program SIMPOW, and a description of the modelling approach for each component is given. The level of model detail relates to the classical modelling of power system components for power system stability studies, where low frequency oscillations are of special importance. The wind turbine model includes a simplified representation of the developed rotor torque and the thrust force based on C{sub p-} and C{sub t} characteristic curves. The mechanical system model represents the fundamental torsional mode and the first mode of blades and tower movements. Two generator technologies have been investigated. The doubly fed induction generator (DFIG) and the stator converter interfaced permanent magnet synchronous generator (PMSG). A simplified model of a 2 level voltage source converter is used for both machine types. The generator converter controllers have been given special attention. All model components are linearized for the purpose of control system design and power system interaction related to small signal stability analysis. Different control strategies discussed in the literature have been investigated with regard to power system interaction aspects. All control parameters are identified using the internal model control approach. The analysis is focused on three main areas: 1. Identification of low damped oscillatory modes. This is carried out by the establishment and discussion of wind turbine modelling. 2. Interaction between control loops. A systematic approach is presented in order to analyse the influence of control loops used in variable speed wind turbines. 3.Impact on power system performance

  12. Variability of Wind Speeds and Power over Europe

    Science.gov (United States)

    Tambke, J.; von Bremen, L.; de Decker, J.; Schmidt, M.; Steinfeld, G.; Wolff, J.-O.

    2010-09-01

    of momentum through the air-sea interface is described by a common wave boundary layer with enhanced Charnock dynamics. 2.) Wind Field Variability Time series of wind speed and power from 400 potential offshore locations and 16,000 onshore sites in the 2020 and 2030 scenarios are part of the design basis of the EU-project www.OffshoreGrid.eu. This project investigates the grid integration of all planned offshore farms in Northern Europe and will serve as the basis for the "Blueprint for Offshore Grids" by the European Commission. The synchronous wind time series were calculated with the WRF-model. The simulation comprises four years and was validated with a number of wind measurements. We present detailed statistics of local, clustered and regional power production. The analysis quantifies spatial and temporal correlations, extreme events and ramps. Important results are the smoothing effects in a pan-European offshore grid. Key words: Offshore Wind Resource Assessment; Marine Meteorology; Wind Speed Profile; Marine Atmospheric Boundary Layer; Wind Variability, Spatio-temporal Correlation; Electricity Grid Integration

  13. Wind generator with electronic variable-speed drives

    Energy Technology Data Exchange (ETDEWEB)

    David, A.; Buchheit, N.; Jakobsen, H.

    1996-12-31

    Variable speed drives have been inserted between the network and the generator on certain recent wind power facilities. They have the following advantages: the drive allows the wind generator to operate at low speed with a significant reduction in acoustic noise, an important point if the facilities are sited near populated areas; the drive optimizes energy transfer, providing a gain of 4 to 10 %; the drive can possibly replace certain mechanical parts (the starting system and it in some cases, the reduction gear); the drive not only provides better transient management in relation to the network for less mechanical stress on the wind generator, it is also able to control reactive power. One commercial drive design sold by several manufacturers has already been installed on several wind generators with outputs of between 150 and 600 kw. In addition, such a solution is extremely well suited to mixed renewable energy systems. This design uses two inverse rectifier type converters and can therefore exchange energy in both directions. The equivalent drive with a single IGBT converter on the motor side and a diode converter on the network side is the solution most widely adopted throughout industry (with more than 50, 000 units installed in France per year). It still remains to be seen whether such a solution could be profitable in wind generator application (since the cost of the drive is quite high). This technical analysis is more destined for the converter-machine assembly specialists and is presented in this document, paying particular attention as it does to the modelling of the `wind energy - generator - drive - network` assembly, the associated drive command and control strategies and the simulations obtained during various transients. A 7.5 kW test bed has been installed in the Laboratoire d`Electronique de Puissance de Clamart, enabling tests to be carried out which emulate the operation of a wind generator.

  14. Three-Dimensional Numerical Analysis of an Operating Helical Rotor Pump at High Speeds and High Pressures including Cavitation

    Directory of Open Access Journals (Sweden)

    Zhou Yang

    2017-01-01

    Full Text Available High pressures, high speeds, low noise and miniaturization is the direction of development in hydraulic pump. According to the development trend, an operating helical rotor pump (HRP at high speeds and high pressures has been designed and produced, which rotational speed can reach 12000r/min and outlet pressure is as high as 25MPa. Three-dimensional simulation with and without cavitation inside the HRP is completed by the means of the computational fluid dynamics (CFD in this paper, which contributes to understand the complex fluid flow inside it. Moreover, the influences of the rotational speeds of the HRP with and without cavitation has been simulated at 25MPa.

  15. Method for optimising the energy of pumps

    NARCIS (Netherlands)

    Skovmose Kallesøe, Carsten; De Persis, Claudio

    2011-01-01

    The method involves determining whether pumps (pu1, pu5) are directly assigned to loads (v1, v3) as pilot pumps (pu2, pu3) and hydraulically connected upstream of the pilot pumps. The upstream pumps are controlled with variable speed for energy optimization. Energy optimization circuits are selected

  16. Self-Calibrating, Variable-Flow Pumping System

    Science.gov (United States)

    Walls, Joe T.

    1994-01-01

    Pumping system provides accurate, controlled flows of two chemical liquids mixed in spray head and react to form rigid or flexible polyurethane or polyisocyanurate foam. Compatible with currently used polyurethane-based coating materials and gas-bubble-forming agents (called "blowing agents" in industry) and expected to be compatible with materials that used in near future. Handles environmentally acceptable substitutes for chlorofluorocarbon foaming agents.

  17. Research on the speed of light transmission in a dual-frequency laser pumped single fiber with two directions

    Science.gov (United States)

    Qiu, Wei; Liu, Jianjun; Wang, Yuda; Yang, Yujing; Gao, Yuan; Lv, Pin; Jiang, Qiuli

    2018-01-01

    In this article a general theory of the coherent population oscillation effect in an erbium-doped fiber at room temperature is presented. We use dual pumping light waves with a simplified two-level system. Thus the time delay equations can be calculated from rate equations and the transmission equation. Using numerical simulation, in the case of dual-frequency pump light waves (1480 nm and 980 nm) with two directions, we analyze the influence of the pump power ratio on the group speed of light propagation. In addition, we compare slow light propagation with a single-pumping light and slow light propagation with a dual-pumping light at room temperature. The discussion shows that a larger time delay of slow light propagation can be obtained with a dual-frequency pumping laser. Compared to previous research methods, a dual-frequency laser pumped fiber with two directions is more controllable. Moreover, we conclude that the group velocity of light can be varied by changing the pump ratio.

  18. Numerical Simulation of 3D Solid-Liquid Turbulent Flow in a Low Specific Speed Centrifugal Pump: Flow Field Analysis

    Directory of Open Access Journals (Sweden)

    Baocheng Shi

    2014-06-01

    Full Text Available For numerically simulating 3D solid-liquid turbulent flow in low specific speed centrifugal pumps, the iteration convergence problem caused by complex internal structure and high rotational speed of pump is always a problem for numeral simulation researchers. To solve this problem, the combination of three measures of dynamic underrelaxation factor adjustment, step method, and rotational velocity control means according to residual curves trends of operating parameters was used to improve the numerical convergence. Numeral simulation of 3D turbulent flow in a low specific speed solid-liquid centrifugal pump was performed, and the results showed that the improved solution strategy is greatly helpful to the numerical convergence. Moreover, the 3D turbulent flow fields in pumps have been simulated for the bottom ash-particles with the volume fraction of 10%, 20%, and 30% at the same particle diameter of 0.1 mm. The two-phase calculation results are compared with those of single-phase clean water flow. The calculated results gave the main region of the abrasion of the impeller and volute casing and improve the hydraulic design of the impeller in order to decrease the abrasion and increase the service life of the pump.

  19. Experimental analysis of flow structure in contra-rotating axial flow pump designed with different rotational speed concept

    Science.gov (United States)

    Cao, Linlin; Watanabe, Satoshi; Imanishi, Toshiki; Yoshimura, Hiroaki; Furukawa, Akinori

    2013-08-01

    As a high specific speed pump, the contra-rotating axial flow pump distinguishes itself in a rear rotor rotating in the opposite direction of the front rotor, which remarkably contributes to the energy conversion, the reduction of the pump size, better hydraulic and cavitation performances. However, with two rotors rotating reversely, the significant interaction between blade rows was observed in our prototype contra-rotating rotors, which highly affected the pump performance compared with the conventional axial flow pumps. Consequently, a new type of rear rotor was designed by the rotational speed optimization methodology with some additional considerations, aiming at better cavitation performance, the reduction of blade rows interaction and the secondary flow suppression. The new rear rotor showed a satisfactory performance at the design flow rate but an unfavorable positive slope of the head — flow rate curve in the partial flow rate range less than 40% of the design flow rate, which should be avoided for the reliability of pump-pipe systems. In the present research, to understand the internal flow field of new rear rotor and its relation to the performances at the partial flow rates, the velocity distributions at the inlets and outlets of the rotors are firstly investigated. Then, the boundary layer flows on rotor surfaces, which clearly reflect the secondary flow inside the rotors, are analyzed through the limiting streamline observations using the multi-color oil-film method. Finally, the unsteady numerical simulations are carried out to understand the complicated internal flow structures in the rotors.

  20. Transient analysis of variable-speed wind turbines at wind speed disturbances and a pitch control malfunction

    International Nuclear Information System (INIS)

    Melicio, R.; Mendes, V.M.F.; Catalao, J.P.S.

    2011-01-01

    As wind power generation undergoes rapid growth, new technical challenges emerge: dynamic stability and power quality. The influence of wind speed disturbances and a pitch control malfunction on the quality of the energy injected into the electric grid is studied for variable-speed wind turbines with different power-electronic converter topologies. Additionally, a new control strategy is proposed for the variable-speed operation of wind turbines with permanent magnet synchronous generators. The performance of disturbance attenuation and system robustness is ascertained. Simulation results are presented and conclusions are duly drawn.

  1. Transient analysis of variable-speed wind turbines at wind speed disturbances and a pitch control malfunction

    Energy Technology Data Exchange (ETDEWEB)

    Melicio, R. [Department of Electromechanical Engineering, University of Beira Interior, R. Fonte do Lameiro, 6201-001 Covilha (Portugal); Mendes, V.M.F. [Department of Electrical Engineering and Automation, Instituto Superior de Engenharia de Lisboa, R. Conselheiro Emidio Navarro, 1950-062 Lisbon (Portugal); Catalao, J.P.S. [Department of Electromechanical Engineering, University of Beira Interior, R. Fonte do Lameiro, 6201-001 Covilha (Portugal); Center for Innovation in Electrical and Energy Engineering, Instituto Superior Tecnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon (Portugal)

    2011-04-15

    As wind power generation undergoes rapid growth, new technical challenges emerge: dynamic stability and power quality. The influence of wind speed disturbances and a pitch control malfunction on the quality of the energy injected into the electric grid is studied for variable-speed wind turbines with different power-electronic converter topologies. Additionally, a new control strategy is proposed for the variable-speed operation of wind turbines with permanent magnet synchronous generators. The performance of disturbance attenuation and system robustness is ascertained. Simulation results are presented and conclusions are duly drawn. (author)

  2. Active Power and Flux Control of a Self-Excited Induction Generator for a Variable-Speed Wind Turbine Generation

    Energy Technology Data Exchange (ETDEWEB)

    Na, Woonki; Muljadi, Eduard; Leighty, Bill; Kim, Jonghoon

    2017-05-11

    A Self-Excited Induction Generation (SEIG) for a variable speed wind turbine generation(VS-WG) is normally considered to be a good candidate for implementation in stand-alone applications such as battery charging, hydrogenation, water pumping, water purification, water desalination, and etc. In this study, we have examined a study on active power and flux control strategies for a SEIG for a variable speed wind turbine generation. The control analysis for the proposed system is carried out by using PSCAD software. In the process, we can optimize the control design of the system, thereby enhancing and expediting the control design procedure for this application. With this study, this control design for a SEIG for VS-WG can become the industry standard for analysis and development in terms of SEIG.

  3. Variable flow controls of closed system pumps for energy savings in maritime power systems

    DEFF Research Database (Denmark)

    Su, Chun-Lien; Liao, Chi-Hsiang; Chou, Tso-Chu

    2016-01-01

    and field tests of a practical auxiliary boiler feed water management system on a commercial vessel. It is proved that the proposed method can maintain constant water pressure for closed system pumps and provide an efficient way to measure energy savings and maintenance benefits. The results serve......Pumps are extensively used in maritime industries as marine vessels utilize a wide range of pumps and pumping techniques to transfer and distribute all types of air and fluids. The electrical energy consumed by the various motors accounts for about 70% of a vessel’s total power consumption......, and this presents a problem in unique marine environments. Such situations are especially conducive to energy-saving strategies using variable frequency drives (VFDs) in centrifugal load service. This paper presents the design and results of applying variable frequency constant pressure technology in closed system...

  4. AC-DC integrated load flow calculation for variable speed offshore wind farms

    DEFF Research Database (Denmark)

    Zhao, Menghua; Chen, Zhe; Blaabjerg, Frede

    2005-01-01

    This paper proposes a sequential AC-DC integrated load flow algorithm for variable speed offshore wind farms. In this algorithm, the variable frequency and the control strategy of variable speed wind turbine systems are considered. In addition, the losses of wind turbine systems and the losses...... of converters are also integrated into the load flow algorithm. As a general algorithm, it can be applied to different types of wind farm configurations, and the load flow is related to the wind speed....

  5. The Advanced Limiter Test-I (ALT-I) variable-geometry pump limiter module

    International Nuclear Information System (INIS)

    Pontau, A.E.; Malinowski, M.E.; Ver Berkmoes, A.A.; Guthrie, S.E.; Watson, R.D.; Goebel, D.M.; Campbell, G.A.

    1984-01-01

    The ALT-I variable geometry module has been designed to address many of the issues not previously settled by earlier experiments. The goal is to study the basic processes involved in pump limiter operation as well as demonstrate its utility and effect on the plasma. The flexibility and extensive instrumentation of ALT-I will offer a unique opportunity to parameterize operation and facilitate the engineering design of future pump limiters. (orig.)

  6. PV Array Driven Adjustable Speed Drive for a Lunar Base Heat Pump

    Science.gov (United States)

    Domijan, Alexander, Jr.; Buchh, Tariq Aslam

    1995-01-01

    A study of various aspects of Adjustable Speed Drives (ASD) is presented. A summary of the relative merits of different ASD systems presently in vogue is discussed. The advantages of using microcomputer based ASDs is now widely understood and accepted. Of the three most popular drive systems, namely the Induction Motor Drive, Switched Reluctance Motor Drive and Brushless DC Motor Drive, any one may be chosen. The choice would depend on the nature of the application and its requirements. The suitability of the above mentioned drive systems for a photovoltaic array driven ASD for an aerospace application are discussed. The discussion is based on the experience of the authors, various researchers and industry. In chapter 2 a PV array power supply scheme has been proposed, this scheme will have an enhanced reliability in addition to the other known advantages of the case where a stand alone PV array is feeding the heat pump. In chapter 3 the results of computer simulation of PV array driven induction motor drive system have been included. A discussion on these preliminary simulation results have also been included in this chapter. Chapter 4 includes a brief discussion on various control techniques for three phase induction motors. A discussion on different power devices and their various performance characteristics is given in Chapter 5.

  7. Variable speed limit system for Elk Mountain corridor.

    Science.gov (United States)

    2010-10-01

    Determining an appropriate speed for the current conditions can be difficult for the driver. Equally difficult is for law : enforcement agencies to enforce and cite someone going too fast for conditions. In many cases, drivers are cited for going : t...

  8. Variable speed limits system for Elk Mountain corridor.

    Science.gov (United States)

    2010-10-01

    "Determining an appropriate speed for the current conditions can be difficult for the driver. Equally difficult is for law : enforcement agencies to enforce and cite someone going too fast for conditions. In many cases, drivers are cited for going : ...

  9. Design and Construction of Variable Direct Current Speed Drive ...

    African Journals Online (AJOL)

    controlled rectifiers from the viewpoint of simplicity and cost effectiveness to act as power converter and controller. Design and construction of constituent circuits such as acceleration/deceleration, speed and current amplifier and the trigger ...

  10. The speed dependence of dry running screw type vacuum pumps; Die Drehzahlabhaengigkeit trockenlaufender Schraubenspindel-Vakuumpumpen

    Energy Technology Data Exchange (ETDEWEB)

    Kauder, K.; Rohe, A. [Univ. Dortmund (Germany). FG Fluidenergiemaschinen

    2003-07-01

    This contribution describes the development of a simple mathematical approach, which has the primary aim of describing the speed dependence of maximum vacuum of a screw type vacuum pump. Based on a simple positive displacement model assuming an isothermal process and with gas flow through an orifice used to depict the clearance mass flows, the vacuum achieved is calculated as function of rotor speed. Changes in the model's approaches, in particular the number of stages and the transition of viscose flow to molecular flow, enable us to depict the characteristic working behaviour of a screw type vacuum pump from the point of view of its maximum vacuum. An extension of this approach yields the characteristics of the delivery rate as a function of the suction pressure. If we replace the orifice flow with the transition flow it becomes possible to describe the characteristic maximum of suction speed at moderate inlet pressures, which can definitely be ascribed to increasing throttling during the transition of the viscose to the molecular flow type. Where there are larger discrepancies, continuous comparison of calculated with measured characteristics requires analyses of the sensitivity of this approach regarding the gap clearances, and a mathematical consideration of external leakages. Finally the effects of internal compression on working behaviour are calculated by using the algorithm. Even if the potential of this approach can not be completely realised due to unknown boundary condition in the examined machine, it nevertheless yields clear and explicable data about the influences of working and construction parameters on the working behaviour. (orig.) [German] Der vorgelegte Beitrag beschreibt einen einfachen mathematischen Ansatzes, der als primaeres Ziel verfolgt, die signifikante Drehzahlabhaengigkeit des Enddruckes von Schraubenspindel-Vakuumpumpen zu berechnen. Ausgehend vom einfachen Verdraengermaschinenmodell werden zunaechst mit Hilfe eines einstufigen

  11. PUMPS

    Science.gov (United States)

    Thornton, J.D.

    1959-03-24

    A pump is described for conveving liquids, particure it is not advisable he apparatus. The to be submerged in the liquid to be pumped, a conduit extending from the high-velocity nozzle of the injector,and means for applying a pulsating prcesure to the surface of the liquid in the conduit, whereby the surface oscillates between positions in the conduit. During the positive half- cycle of an applied pulse liquid is forced through the high velocity nozzle or jet of the injector and operates in the manner of the well known water injector and pumps liquid from the main intake to the outlet of the injector. During the negative half-cycle of the pulse liquid flows in reverse through the jet but no reverse pumping action takes place.

  12. Simulation Analysis of SPWM Variable Frequency Speed Based on Simulink

    Directory of Open Access Journals (Sweden)

    Min-Yan DI

    2014-01-01

    Full Text Available This article is studied on currently a very active field of researching sinusoidal pulse width modulation (SPWM frequency speed control system, and strengthen researched on the simulation model of speed control system with MATLAB / Simulink / Power System simulation tools, thus we can find the best way to simulation. We apply it to the actual conveyor belt, frequency conversion motor, when the obtained simulation results are compared with the measured data, we prove that the method is practical and effective. The results of our research have a guiding role for the future engineering and technical personnel in asynchronous motor SPWM VVVF CAD design.

  13. Analysis of Design Variables of Annular Linear Induction Electromagnetic Pump using an MHD Model

    Energy Technology Data Exchange (ETDEWEB)

    Kwak, Jae Sik; Kim, Hee Reyoung [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2015-05-15

    The generated force is affected by lots of factors including electrical input, hydrodynamic flow, geometrical shape, and so on. These factors, which are the design variables of an ALIP, should be suitably analyzed to optimally design an ALIP. Analysis on the developed pressure and efficiency of the ALIP according to the change of design variables is required for the ALIP satisfying requirements. In this study, the design variables of the ALIP are analyzed by using ideal MHD analysis model. Electromagnetic force and efficiency are derived by analyzing the main design variables such as pump core length, inner core diameter, flow gap and turns of coils. The developed pressure and efficiency of the ALIP were derived and analyzed on the change of the main variables such as pump core length, inner core diameter, flow gap, and turns of coils of the ALIP.

  14. Optimal multivariable control of a wind turbine with variable speed

    NARCIS (Netherlands)

    Steinbuch, M.

    1987-01-01

    The control system design for a 310 kW horizontal axis wind energy conversion system with a synchronous generator and DC link is investigated. Because the wind turbine system has multiple inputs (pitch angle, field vollage alld delay angle), and multiple outputs, (speed and power), and because the

  15. Variable speed control in wells turbine-based oscillating water column devices: optimum rotational speed

    Science.gov (United States)

    Lekube, J.; Garrido, A. J.; Garrido, I.

    2018-03-01

    The effects of climate change and global warming reveal the need to find alternative sources of clean energy. In this sense, wave energy power plants, and in particular Oscillating Water Column (OWC) devices, offer a huge potential of energy harnessing. Nevertheless, the conversion systems have not reached a commercially mature stage yet so as to compete with conventional power plants. At this point, the use of new control methods over the existing technology arises as a doable way to improve the efficiency of the system. Due to the non-uniform response that the turbine shows to the rotational speed variation, the speed control of the turbo-generator may offer a feasible solution for efficiency improvement during the energy conversion. In this context, a novel speed control approach for OWC systems is presented in this paper, demonstrating its goodness and affording promising results when particularized to the Mutriku’s wave power plant.

  16. Study of Stage-wise Pressure Pulsation in an Electric Submersible Pump under Variable Frequency Operation at Shut-off Condition

    Science.gov (United States)

    Dhanasekaran, A.; Kumaraswamy, S.

    2018-01-01

    Pressure pulsation causes vibration in the Electric Submersible Pump (ESP) and affects the life and performance of its system. ESP systems are installed at depths ranging from a few meters to several hundred meters. Unlike pumps used on the surface, once they are installed they become inaccessible for maintenance or for any kind of diagnostic measurement that might be taken directly on them. Therefore a detailed knowledge of mean and fluctuating pressures is required to achieve an optimal pressure distribution inside the ESP. This paper presents the results of an experimental investigation of the stage-wise pulsating pressure in ESP at shut-off condition at different speeds. Experiments were conducted on a pump having five stages. A variable frequency drive was used to operate the pump at five different speeds. Piezoresistive transducers were mounted at each stage of ESP to capture the unsteady pressure signals. Fast Fourier Transformation was carried out on the pressure signals to convert into frequency domain and the spectra of pressure pulsation signals were analyzed. The obtained results indicated the existence of fundamental frequency corresponding to the speed of rotation times the number of impeller blades and of the whole series of harmonics of higher frequencies.

  17. Pitch Angle Control for Variable Speed Wind Turbines

    Directory of Open Access Journals (Sweden)

    Mouna Ben Smida

    2015-08-01

    Full Text Available Abstract.Pitch control is a practical technique for power regulation above the rated wind speed it is considered as the most efficient and popular power control method. As conventional pitch control usually use PI controller, the mathematical model of the system should be known well.This paper deals with the operation and the control of the direct driven permanent magnet synchronous generator (PMSG.Different conventional strategies of pitch angle control are described and validated through simulation results under Matlab\\Simulink.

  18. Experimental Analysis of Variable Capacity Heat Pump Systems equipped with a liquid-cooled frequency inverter

    OpenAIRE

    Ebraheem, Thair

    2013-01-01

    Using an inverter-driven compressor in variable capacity heat pump systems has a main drawback, which is the extra loss in the inverter. The present experimental study aims to recover the inverter losses by using brine-cooled and water-cooled inverters, thereby improving the total efficiency of the heat pump system. In order to achieve this goal, a test rig with the air-cooled, water-cooled and brine-cooled inverters is designed and built, and a comparative analysis of the recovered heat, inv...

  19. Energy Implications of Retrofitting Retail Sector Rooftop Units with Stepped-Speed and Variable-Speed Functionality

    Energy Technology Data Exchange (ETDEWEB)

    Studer, D.; Romero, R.; Herrmann, L.; Benne, K.

    2012-04-01

    Commercial retailers understand that retrofitting constant-speed RTU fan motors with stepped- or variable-speed alternatives could save significant energy in most U.S. climate zones. However, they lack supporting data, both real-world and simulation based, on the cost effectiveness and climate zone-specific energy savings associated with this measure. Thus, building managers and engineers have been unable to present a compelling business case for fan motor upgrades to upper management. This study uses whole-building energy simulation to estimate the energy impact of this type of measure so retailers can determine its economic feasibility.

  20. High Speed Pump-Probe Apparatus for Observation of Transitional Effects in Ultrafast Laser Micromachining Processes

    Directory of Open Access Journals (Sweden)

    Ilya Alexeev

    2015-12-01

    Full Text Available A pump-probe experimental approach has been shown to be a very efficient tool for the observation and analysis of various laser matter interaction effects. In those setups, synchronized laser pulses are used to create an event (pump and to simultaneously observe it (probe. In general, the physical effects that can be investigated with such an apparatus are restricted by the temporal resolution of the probe pulse and the observation window. The latter can be greatly extended by adjusting the pump-probe time delay under the assumption that the interaction process remains fairly reproducible. Unfortunately, this assumption becomes invalid in the case of high-repetition-rate ultrafast laser material processing, where the irradiation history strongly affects the ongoing interaction process. In this contribution, the authors present an extension of the pump-probe setup that allows to investigate transitional and dynamic effects present during ultrafast laser machining performed at high pulse repetition frequencies.

  1. Operating problem of low specific speed pumps operating in closed hydraulic loop

    International Nuclear Information System (INIS)

    Rajput, A.K.

    1979-01-01

    Results of the studies of pressure pulsations caused by the centrifugal pump driving a typical sodium test loop are presented. The method of characteristics has been used for solving the equations of unsteady fluid flow in closed hydraulic loops with various boundary points, important of which are pump, control valve and heater tank (acting hydraulically as surge tank). Mathematical and computational models used for calculations are described. (M.G.B.)

  2. Flicker study on variable speed wind turbines with doubly fed induction generators

    DEFF Research Database (Denmark)

    Sun, Tao; Chen, Zhe; Blaabjerg, Frede

    2005-01-01

    to a conclusion that the factors mentioned above have different influences on flicker emission compared with that in the case of the fixed speed wind turbine. Flicker mitigation is realized by output reactive power control of the variable speed wind turbine with doubly fed induction generator. Simulation results...... show the wind turbine output reactive power control provides an effective means for flicker mitigation regardless of mean wind speed, turbulence intensity and short circuit capacity ratio.......Grid connected wind turbines may produce flicker during continuous operation. This paper presents a simulation model of a MW-level variable speed wind turbine with a doubly fed induction generator developed in the simulation tool of PSCAD/EMTDC. Flicker emission of variable speed wind turbines...

  3. Pump

    International Nuclear Information System (INIS)

    Mole, C.J.

    1983-01-01

    An electromagnetic pump for circulating liquid -metal coolant through a nuclear reactor wherein opposite walls of a pump duct serve as electrodes to transmit current radially through the liquid-metal in the ducts. A circumferential electric field is supplied to the liquid-metal by a toroidal electromagnet which has core sections interposed between the ducts. The windings of the electromagnet are composed of metal which is superconductive at low temperatures and the electromagnet is maintained at a temperature at which it is superconductive by liquid helium which is fed through the conductors which supply the excitation for the electromagnet. The walls of the ducts joining the electrodes include metal plates insulated from the electrodes backed up by insulators so that they are capable of withstanding the pressure of the liquid-metal. These composite wall structures may also be of thin metal strips of low electrical conductivity backed up by sturdy insulators. (author)

  4. Work zone variable speed limit systems: Effectiveness and system design issues.

    Science.gov (United States)

    2010-03-01

    Variable speed limit (VSL) systems have been used in a number of countries, particularly in Europe, as a method to improve flow and increase safety. VSLs use detectors to collect data on current traffic and/or weather conditions. Posted speed limits ...

  5. Applications of variable speed control for contending with recurrent highway congestion.

    Science.gov (United States)

    2014-07-01

    This research project developed vital operational guidelines for design of a variable speed limit (VSL) system and its integrated operations with ramp metering control in contending with recurrent highway congestion. The developed guidelines can serv...

  6. Overall control strategy of variable speed doubly-fed induction generator wind turbine

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Anca D.; Soerensen, Poul [Risoe National Laboratory, Roskilde (Denmark). Wind Energy Dept.; Iov, Florin; Blaabjerg, Frede [Aalborg Univ. (Denmark). Inst. of Energy Technology

    2004-07-01

    The variable speed doubly-fed induction generator wind turbine is today the most widely used concept. The paper presents an overall control system of the variable speed DFIG wind turbine, with focus on the control strategies and algorithms applied at each hierarchical control level of the wind turbine. The present control method is designed for normal continuous operations. The strongest feature of the implemented control method is that it allows the turbine to operate with the optimum power efficiency over a wider range of wind speeds. The variable speed/variable pitch wind turbine with doubly-fed induction generator is implemented in the dynamic power system simulation tool DIgSILENT. Simulation results are performed and analyzed in different normal operating conditions.

  7. Overall control strategy of variable speed doubly-fed induction generator wind turbine

    DEFF Research Database (Denmark)

    Hansen, A.D.; Iov, F.; Sørensen, Poul Ejnar

    2004-01-01

    The variable speed doubly-fed induction generator wind turbine is today the most widely used concept. The paper presents an overall control system of the variable speed DFIG wind turbine, with focus on the control strategies and algorithms applied at each hierarchical control level of the wind tu......-fed induction generator is implemented in the dynamic power system simulation tool DIgSILENT. Simulation results are performed and analyzed in different normal operating conditions....

  8. Modelling and control of variable speed wind turbines for power system studies

    DEFF Research Database (Denmark)

    Michalke, Gabriele; Hansen, Anca Daniela

    2010-01-01

    and implemented in the power system simulation tool DIgSILENT. Important issues like the fault ride-through and grid support capabilities of these wind turbine concepts are addressed. The paper reveals that advanced control of variable speed wind turbines can improve power system stability. Finally......, it will be shown in the paper that wind parks consisting of variable speed wind turbines can help nearby connected fixed speed wind turbines to ride-through grid faults. Copyright © 2009 John Wiley & Sons, Ltd.......Modern wind turbines are predominantly variable speed wind turbines with power electronic interface. Emphasis in this paper is therefore on the modelling and control issues of these wind turbine concepts and especially on their impact on the power system. The models and control are developed...

  9. Speed

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Speed. The rate of information transferred per second is the speed of the information. Measured in bits per second. Need for speed on the net: You-Tube phenomenon; IPTV; 3D Video telephony. Online gaming; HDTV.

  10. Wind Turbine Generator Modeling and Simulation Where Rotational Speed is the Controlled Variable

    DEFF Research Database (Denmark)

    Mihet-Popa, Lucian; Blaabjerg, Frede; Boldea, Ion

    2004-01-01

    the interaction between a wind turbine and the power system. The model is intended to simulate the behaviour of the wind turbine using induction generators both during normal operation. Sample simulation results for two induction generators (2/0.5 MW) validate the fundamental issues.......To optimise the power produced in a wind turbine, the speed of the turbine should vary with the wind speed. A simple control method is proposed that will allow an induction machine to run a turbine at its maximum power coefficient. Various types of power control strategies have been suggested...... for application in variable speed wind turbines. The usual strategy is to control the power or the torque acting on the wind turbine shafts. This paper presents an alternative control strategy, where the rotational speed is the controlled variable. The paper describes a model, which is being developed to simulate...

  11. Flicker Mitigation by Individual Pitch Control of Variable Speed Wind Turbines With DFIG

    DEFF Research Database (Denmark)

    Zhang, Yunqian; Chen, Zhe; Hu, Weihao

    2014-01-01

    generatorto investigate the flicker emission and mitigation issues. An individual pitch control (IPC) strategy is proposed to reduce the flicker emission at different wind speed conditions. The IPC scheme is proposed and the individual pitch controller is designed according to the generator active power...... and the azimuth angle of the wind turbine. The simulations are performed on the NREL (National Renewable Energy Laboratory) 1.5-MW upwind reference wind turbine model. Simulation results show that damping the generator active power by IPC is an effective means for flicker mitigation of variable speed wind......Due to the wind speed variation, wind shear and tower shadow effects, grid connected wind turbines are the sources of power fluctuations which may produce flicker during continuous operation. This paper presents a model of an MW-level variable-speed wind turbine with a doubly fed induction...

  12. Experimental study of R134a/R410A cascade cycle for variable refrigerant flow heat pump systems

    International Nuclear Information System (INIS)

    Kim, Jeong Hun; Lee, Jae Wan; Park, Warn Gyu; Choi, Hwan Jong; Lee, Sang Hun; Oh, Sai Kee

    2015-01-01

    Cascade cycle is widely applied to heat pumps operating at low ambient temperature to overcome problems such as low heating capacity and Coefficient of performance (COP) deterioration A number of researches have been conducted on cascade cycle heat pumps, but most of those studies were focused on system optimization to determine optimal intermediate temperature in air-to-water heat pumps. However, experimental optimization in regard to air and water heating simultaneously using a cascade cycle has been an understudied area. Therefore, we focused on experimental analysis for a cascade system with Variable refrigerant flow (VRF) heat pumps. Experiments were conducted under a variety of operating conditions, such as ambient and water inlet temperature. COP increased up to 16% when water inlet temperature decreased. COP of VRF heat pumps with cascade cycle is three-times higher compared with conventional boilers as well as 17% higher compared to single heat pumps

  13. Within-person variability in response speed as an indicator of cognitive impairment in older adults.

    Science.gov (United States)

    Strauss, Esther; Bielak, Allison A M; Bunce, David; Hunter, Michael A; Hultsch, David F

    2007-11-01

    Within-person variability may be an important indicator of central nervous system compromise. In this study, within-person variability in response speed was examined in community-dwelling older adults, ages 64-92 years, using a new framework that takes into account both the extent (single versus multiple domains affected) and nature (amnestic versus non-amnestic) of the cognitive impairment. Those with multiple domains of impairment were more variable than those who showed an isolated area of impairment, regardless of whether memory was one of the domains affected. Further, for those with difficulties in two or more non-memory domains, increased variability was most evident in more cognitively demanding situations, when individuals had to manipulate information held briefly in mind, switch cognitive set or inhibit an automatic response. Finally, group differentiation was better achieved when within-person variability as opposed to mean speed of performance was considered.

  14. Speed control of boiler feed water pump turbine based on gray correlation compensation

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Yun Long; Wang, Di; Zhou, Hai Chun [Northeast Dianli UniversityJilin (China)

    2017-01-15

    One of the most important controlled parameters of thermal power units is the boiler drum water level. Disturbances of feed water flow rate could cause instability of the drum water level. This study proposes the Gray correlation compensation (GCC) control technology for the Boiler feed water pump turbine (BFPT) to solve this problem. Simulation results indicate that the GCC controller outperforms the traditional proportional-integral-derivative controller when it encounters different disturbances. Furthermore, the GCC controller can rapidly switch to the high-pressure steam source to ensure that the drum water level is in the secure range during steam source switching of the BFPT.

  15. Variable speed wind turbine generator system with current controlled voltage source inverter

    International Nuclear Information System (INIS)

    Muyeen, S.M.; Al-Durra, Ahmed; Tamura, J.

    2011-01-01

    highlights: → Current controlled voltage source inverter scheme for wind power application. → Low voltage ride through of wind farm. → Variable speed wind turbine driven permanent magnet synchronous generator-operation and control. -- Abstract: The present popular trend of wind power generation is to use variable speed wind turbine (VSWT) driving a doubly fed induction generator (DFIG), wound field synchronous generator (WFSG) or permanent magnet synchronous generator (PMSG). Among them, stability analyses of DFIG type of VSWT have already been reported in many literatures. However, transient stability and low voltage ride through (LVRT) characteristics analyses for synchronous generator type of VSWT is not sufficient enough. This paper focuses on detailed LVRT characteristic analysis of variable speed wind turbine driving a PMSG (VSWT-PMSG) with current controlled voltage source inverter (CC-VSI). Modeling and suitable control strategies for overall system are developed to augment the low voltage ride through capability of variable speed wind generator, considering recent wind farm grid code. Both symmetrical and unsymmetrical faults are analyzed as network disturbances in this paper. The permanent fault due to unsuccessful reclosing of circuit breakers is taken into consideration, which is a salient feature of this study. Moreover, the dynamic characteristic is analyzed using real wind speed data measured in Hokkaido Island, Japan. The proposed control scheme is simulated by using the standard power system simulation package PSCAD/EMTDC and results are verified by comparing that of voltage controlled voltage source inverter scheme available in power system literature.

  16. Variable speed wind turbine generator system with current controlled voltage source inverter

    Energy Technology Data Exchange (ETDEWEB)

    Muyeen, S.M., E-mail: muyeen0809@yahoo.co [Dept. of Electrical Engineering, Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates); Al-Durra, Ahmed [Dept. of Electrical Engineering, The Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates); Tamura, J. [Dept. of EEE, Kitami Institute of Technology, 165 Koen-cho, Kitami 090-8507 (Japan)

    2011-07-15

    highlights: {yields} Current controlled voltage source inverter scheme for wind power application. {yields} Low voltage ride through of wind farm. {yields} Variable speed wind turbine driven permanent magnet synchronous generator-operation and control. -- Abstract: The present popular trend of wind power generation is to use variable speed wind turbine (VSWT) driving a doubly fed induction generator (DFIG), wound field synchronous generator (WFSG) or permanent magnet synchronous generator (PMSG). Among them, stability analyses of DFIG type of VSWT have already been reported in many literatures. However, transient stability and low voltage ride through (LVRT) characteristics analyses for synchronous generator type of VSWT is not sufficient enough. This paper focuses on detailed LVRT characteristic analysis of variable speed wind turbine driving a PMSG (VSWT-PMSG) with current controlled voltage source inverter (CC-VSI). Modeling and suitable control strategies for overall system are developed to augment the low voltage ride through capability of variable speed wind generator, considering recent wind farm grid code. Both symmetrical and unsymmetrical faults are analyzed as network disturbances in this paper. The permanent fault due to unsuccessful reclosing of circuit breakers is taken into consideration, which is a salient feature of this study. Moreover, the dynamic characteristic is analyzed using real wind speed data measured in Hokkaido Island, Japan. The proposed control scheme is simulated by using the standard power system simulation package PSCAD/EMTDC and results are verified by comparing that of voltage controlled voltage source inverter scheme available in power system literature.

  17. Automated Bearing Fault Diagnosis Using 2D Analysis of Vibration Acceleration Signals under Variable Speed Conditions

    Directory of Open Access Journals (Sweden)

    Sheraz Ali Khan

    2016-01-01

    Full Text Available Traditional fault diagnosis methods of bearings detect characteristic defect frequencies in the envelope power spectrum of the vibration signal. These defect frequencies depend upon the inherently nonstationary shaft speed. Time-frequency and subband signal analysis of vibration signals has been used to deal with random variations in speed, whereas design variations require retraining a new instance of the classifier for each operating speed. This paper presents an automated approach for fault diagnosis in bearings based upon the 2D analysis of vibration acceleration signals under variable speed conditions. Images created from the vibration signals exhibit unique textures for each fault, which show minimal variation with shaft speed. Microtexture analysis of these images is used to generate distinctive fault signatures for each fault type, which can be used to detect those faults at different speeds. A k-nearest neighbor classifier trained using fault signatures generated for one operating speed is used to detect faults at all the other operating speeds. The proposed approach is tested on the bearing fault dataset of Case Western Reserve University, and the results are compared with those of a spectrum imaging-based approach.

  18. Very-low-speed variable-structure control of sensorless induction machine drives without signal injection

    DEFF Research Database (Denmark)

    Lascu, Christian; Boldea, Ion; Blaabjerg, Frede

    2005-01-01

    A sensorless induction machine drive is presented, in which the principles of variable-structure control and direct torque control (DTC) are combined to ensure high-performance operation in the steady state and under transient conditions. The drive employs a new torque and flux controller......, the "linear and variable-structure control", which realizes accurate and robust control in a wide speed range. Conventional DTC transient merits are preserved, while the steady-state behavior is significantly improved. The full-order state observer is a sliding-mode one, which does not require the rotor speed...

  19. The experimental studies of operating modes of a diesel-generator set at variable speed

    Science.gov (United States)

    Obukhov, S. G.; Plotnikov, I. A.; Surkov, M. A.; Sumarokova, L. P.

    2017-02-01

    A diesel generator set working at variable speed to save fuel is studied. The results of experimental studies of the operating modes of an autonomous diesel generator set are presented. Areas for regulating operating modes are determined. It is demonstrated that the transfer of the diesel generator set to variable speed of the diesel engine makes it possible to improve the energy efficiency of the autonomous generator source, as well as the environmental and ergonomic performance of the equipment as compared with general industrial analogues.

  20. Centrifugal pumps

    CERN Document Server

    Anderson, HH

    1981-01-01

    Centrifugal Pumps describes the whole range of the centrifugal pump (mixed flow and axial flow pumps are dealt with more briefly), with emphasis on the development of the boiler feed pump. Organized into 46 chapters, this book discusses the general hydrodynamic principles, performance, dimensions, type number, flow, and efficiency of centrifugal pumps. This text also explains the pumps performance; entry conditions and cavitation; speed and dimensions for a given duty; and losses. Some chapters further describe centrifugal pump mechanical design, installation, monitoring, and maintenance. The

  1. Study on the VFD (Variable Frequency Drive) for RCP (Reactor Coolant Pump) Motors of APR1400

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jung Ha; Robert, M. Field; Kim, Tae Ryong [Department of NPP Engineering, KEPCO International Nuclear Graduate School, Ulsan (Korea, Republic of)

    2014-10-15

    Most industrial facilities are continually searching for ways to reduce energy costs while increasing or maintaining current production. In terms of electric motors, Variable Frequency Drive (VFD) units represent a critical opportunity for energy savings. Currently, VFDs are used on about ten (10) percent of industrial process motors, and this percentage is increasing every year. Properly applied VFDs have been documented to save as much as fifty percent of the energy consumed by certain industrial processes. Nuclear Power - Power plants in general and Nuclear Power Plants (NPPs) in particular are slow to adopt new technology. The nuclear power industry requires a nearly absolute demonstration through operating experience in other industries in which the new approach will result in a net improvement in plant reliability without any surprises. Only recently has the nuclear industry begun to adapt VFD units for large motors. Specifically, there are several examples in the Boiling Water Reactor (BWR) fleet of replacing Motor-Generator (M-G) sets with VFD units for Reactor Recirculation (RR) pump motor service. At one station, VFD units were introduced upstream of the Circulating Water (CWP) pump motors to address environmental issues. They units are taking advantage of VFD technology whose benefits include increased reliability, reduction in electrical house load, improved flow control, and reduced maintenance. RCP Application - In the case of new generation, it has been reported that the Westinghouse AP1000 will make use of VFD units for the Reactor Coolant Pump (RCP) motors.

  2. Using Random Forests to Select Optimal Input Variables for Short-Term Wind Speed Forecasting Models

    Directory of Open Access Journals (Sweden)

    Hui Wang

    2017-10-01

    Full Text Available Achieving relatively high-accuracy short-term wind speed forecasting estimates is a precondition for the construction and grid-connected operation of wind power forecasting systems for wind farms. Currently, most research is focused on the structure of forecasting models and does not consider the selection of input variables, which can have significant impacts on forecasting performance. This paper presents an input variable selection method for wind speed forecasting models. The candidate input variables for various leading periods are selected and random forests (RF is employed to evaluate the importance of all variable as features. The feature subset with the best evaluation performance is selected as the optimal feature set. Then, kernel-based extreme learning machine is constructed to evaluate the performance of input variables selection based on RF. The results of the case study show that by removing the uncorrelated and redundant features, RF effectively extracts the most strongly correlated set of features from the candidate input variables. By finding the optimal feature combination to represent the original information, RF simplifies the structure of the wind speed forecasting model, shortens the training time required, and substantially improves the model’s accuracy and generalization ability, demonstrating that the input variables selected by RF are effective.

  3. Assertion based verification methodology for HDL designs of primary sodium pump speed and eddy current flow measurement systems of PFBR

    International Nuclear Information System (INIS)

    Misra, M.K.; Menon, Saritha P.; Thirugnana Murthy, D.

    2013-01-01

    With the growing complexity and size of digital designs, functional verification has become a huge challenge. The validation and testing process accounts for a significant percentage of the overall development effort and cost for electronic systems. Many studies have shown that up to 70% of the design development time and resources are spent on functional verification. Functional errors manifest themselves very early in the design flow, and unless they are detected upfront, they can result in severe consequences - both financially and from a safety viewpoint. This paper covers the various types of verification methodologies and focuses on Assertion Based Verification Methodology for HDL designs, taking as case studies, the Primary Sodium Pump Speed and Eddy Current Flow Measurement Systems of PFBR. (author)

  4. Energy saving opportunity with variable speed drive in primary air-handling unit

    International Nuclear Information System (INIS)

    Li, J.S.M.

    2007-01-01

    Air conditioners used in the court buildings in Kowloon City, Hong Kong were retrofitted with variable speed drives in the primary air handling unit (PAU) in an effort to reduce energy consumption. The initial effect of this retrofit was investigated along with the feasibility of using a carbon dioxide (CO 2 ) based demand control ventilation to reduce energy consumption while optimizing indoor air quality. The air flow in most air conditioning fans is either constant or controlled by motorized inlet guide vanes. Although this controls the flow and may reduce the load on the fan, this constriction adds an energy loss, resulting in inefficient operation. Variable speed drives should be used on the PAU in order to maintain system efficiency. As the speed of the fans are reduced, the flow will decrease proportionally, while the power required by the fan will reduce the cube of the speed. Therefore, if the fresh air supply can be controlled by reducing the speed of the fan motor, then flow control would be more efficient. The energy saving associated with variable fresh air supply flow rate was evaluated along with the cost to building owners. This paper presented the results of the potential energy and cost savings associated with this retrofit, and included implementation cost and pay back period. It was estimated that about 20 per cent of power consumption and electricity costs can be saved per year, with a simple payback period of 2 years. 7 refs., 3 tabs., 3 figs

  5. Match-to-match variability in high-speed running activity in a professional soccer team.

    Science.gov (United States)

    Carling, Christopher; Bradley, Paul; McCall, Alan; Dupont, Gregory

    2016-12-01

    This study investigated variability in competitive high-speed running performance in an elite soccer team. A semi-automated tracking system quantified running performance in 12 players over a season (median 17 matches per player, 207 observations). Variability [coefficient of variation (CV)] was compared for total sprint distance (TSD, >25.2 km/h), high-speed running (HSR, 19.8-25.2 km/h), total high-speed running (THSR, ≥19.8 km/h); THSR when the team was in and out of ball possession, in individual ball possession, in the peak 5 min activity period; and distance run according to individual maximal aerobic speed (MAS). Variability for % declines in THSR and distance covered at ≥80% MAS across halves, at the end of play (final 15 min vs. mean for all 15 min periods) and transiently (5 min period following peak 5 min activity period), was analysed. Collectively, variability was higher for TSD versus HSR and THSR and lowest for distance run at ≥80% MAS (CVs: 37.1%, 18.1%, 19.8% and 11.8%). THSR CVs when the team was in/out of ball possession, in individual ball possession and during the peak 5 min period were 31.5%, 26.1%, 60.1% and 23.9%. Variability in THSR declines across halves, at the end of play and transiently, ranged from 37.1% to 142.6%, while lower CVs were observed in these metrics for running at ≥80% MAS (20.9-53.3%).These results cast doubt on the appropriateness of general measures of high-speed activity for determining variability in an elite soccer team, although individualisation of HSR thresholds according to fitness characteristics might provide more stable indicators of running performance and fatigue occurrence.

  6. Control of variable speed wind turbine with doubly-fed induction generator

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, A.D.; Soerensen, P. [Risoe National Lab., Wind Energy Dept., Roskilde (Denmark); Iov, F.; Blaabjerg, F. [Aalborg Univ., Inst. of Energy Technology, Aalborg (Denmark)

    2004-07-01

    draIn this paper, a Control method suitable for a variable speed grid connected pitch-controlled wind turbine with doubly-fed induction generator (DFIG) is developed. The targets of the Control system are: 1) to Control the power drawn from the wind turbine in order to track the wind turbine optimum operation point 2) to limit the power in case of high wind speeds and 3) to Control the reactive power interchanged between the wind turbine generator and the grid. The considered configuration of DFIG is an induction generator with a wound rotor connected to the grid through a back-to-back power converter and a stator directly connected to the grid. The paper presents the overall Control system of the variable speed DFIG wind turbine, with focus on the Control strategies and algorithms applied at each hierarchical Control level of the wind turbine. There are two Control levels: a DFIG Control level and wind turbine Control level. The DFIG Control level contains a fast Control of the power converter and of the doubly-fed induction generator and it has as goal to Control the active and reactive power of the wind turbine independently. The wind turbine Control level supervises with Control signals both the DFIG Control level and the hydraulic pitch Control system of the wind turbine. The present Control method is designed for normal continuous operations. The variable speed/variable pitch wind turbine with doubly-fed induction generator is implemented in the dynamic power system simulation tool DIgSILENT, which makes possible to investigate the dynamic performance of gid-connected wind turbines as a part of realistic electrical grid models. Several significant simulation results are performed With the overall Control-implemented algorithm applied on a variable speed, variable pitch wind turbine model. (au)

  7. Spatial and temporal variability of mean daily wind speeds in the Czech Republic, 1961-2015

    Czech Academy of Sciences Publication Activity Database

    Brázdil, Rudolf; Zahradníček, Pavel; Řezníčková, Ladislava; Tolasz, R.; Štěpánek, Petr; Dobrovolný, Petr

    2017-01-01

    Roč. 72, č. 3 (2017), s. 197-216 ISSN 0936-577X R&D Projects: GA MŠk(CZ) LO1415; GA ČR(CZ) GA15-11805S Institutional support: RVO:67179843 Keywords : mean daily wind speed * spatial variability * temporal variability * wind stilling * Czech Republic Subject RIV: DG - Athmosphere Sciences, Meteorology OBOR OECD: Meteorology and atmospheric sciences Impact factor: 1.578, year: 2016

  8. Mixed convection heat transfer simulation in a rectangular channel with a variable speed rotational cylinder

    Science.gov (United States)

    Khan, Md Imran; Billah, Md. Mamun; Rahman, Mohammed Mizanur; Hasan, Mohammad Nasim

    2017-12-01

    Numerical simulation of steady two-dimensional heat transfer in a rectangular channel with a centered variable speed cylinder has been performed in this paper. In this setup, an isoflux heater is placed at the bottom wall of the channel while the upper wall is kept isothermal with a low temperature. The cylinder's peripheral speed to maximum inlet fluid velocity ratio (ξ) is varied from 0.5 to 1.5 for both clockwise and anticlockwise rotational cases. Air has been considered as working fluid while other system parameters such as Grashof and Reynolds numbers are varied. The effects of rotational speed, Grashof and Reynolds numbers on the streamline pattern, isothermal lines, local and average Nusselt number are analyzed and presented. It is observed the cylinder's rotational direction and speed has a significant effect on the flow pattern, temperature distribution as well as heat transfer characteristics.

  9. Potential electricity savings by variable speed control of compressor for air conditioning systems

    Energy Technology Data Exchange (ETDEWEB)

    Nasution, Henry [Bung Hatta University, Department of Mechanical Engineering, Faculty of Industrial Engineering, Padang, West Sumatera (Indonesia); Wan Hassan, Mat Nawi [Universiti Teknologi Malaysia, Faculty of Mechanical Engineering, Skudai, Johor Bahru-Darul Ta' zim (Malaysia)

    2006-05-15

    The potential of a variable-speed compressor running on a controller to provide enhanced load-matching capability, energy saving and thermal comfort for application in air-conditioning system is demonstrated. An air-conditioning system, originally operated on a constant speed mode, is retrofitted with an inverter and a PID controller. The system was installed to a thermal environmental room together with a data acquisition system to monitor energy consumption and temperature of the room. Measurements were taken 2 h daily at a time interval of 5 min for an on/off and an inverter variable-speed conditions. The results indicate that thermal comfort of the room together with energy saving can be obtained through a proper selection of K for the controller. At a temperature setting of 22 C, the energy saving for the system is estimated to reach 25.3% for PID controllers. (orig.)

  10. Flicker Study on Variable Speed Wind Turbines with Permanent Magnet Synchronous Generator

    DEFF Research Database (Denmark)

    Hu, Weihao; Chen, Zhe; Wang, Yue

    2008-01-01

    capacity, grid impedance angle) are analyzed. Flicker mitigation is realized by output reactive power control of the variable speed wind turbines with PMSG. Simulation results show the output reactive power control is an effective measure to mitigate the flicker during continuous operation of grid......Grid connected wind turbines are fluctuating power sources that may produce flicker during continuous operation. This paper presents a simulation model of a MW-level variable speed wind turbines with a permanent magnet synchronous generator (PMSG) and a full-scale converter developed...... in the simulation tool of PSCAD/EMTDC. Flicker emission of this system is investigated during continuous operation. The dependence of flicker emission on wind characteristics (mean speed, turbulence intensity), 3p torque oscillations due to wind shear and tower shadow effects and grid conditions (short circuit...

  11. A New Turbo-shaft Engine Control Law during Variable Rotor Speed Transient Process

    Science.gov (United States)

    Hua, Wei; Miao, Lizhen; Zhang, Haibo; Huang, Jinquan

    2015-12-01

    A closed-loop control law employing compressor guided vanes is firstly investigated to solve unacceptable fuel flow dynamic change in single fuel control for turbo-shaft engine here, especially for rotorcraft in variable rotor speed process. Based on an Augmented Linear Quadratic Regulator (ALQR) algorithm, a dual-input, single-output robust control scheme is proposed for a turbo-shaft engine, involving not only the closed loop adjustment of fuel flow but also that of compressor guided vanes. Furthermore, compared to single fuel control, some digital simulation cases using this new scheme about variable rotor speed have been implemented on the basis of an integrated system of helicopter and engine model. The results depict that the command tracking performance to the free turbine rotor speed can be asymptotically realized. Moreover, the fuel flow transient process has been significantly improved, and the fuel consumption has been dramatically cut down by more than 2% while keeping the helicopter level fight unchanged.

  12. Differential effects of absent visual feedback control on gait variability during different locomotion speeds.

    Science.gov (United States)

    Wuehr, M; Schniepp, R; Pradhan, C; Ilmberger, J; Strupp, M; Brandt, T; Jahn, K

    2013-01-01

    Healthy persons exhibit relatively small temporal and spatial gait variability when walking unimpeded. In contrast, patients with a sensory deficit (e.g., polyneuropathy) show an increased gait variability that depends on speed and is associated with an increased fall risk. The purpose of this study was to investigate the role of vision in gait stabilization by determining the effects of withdrawing visual information (eyes closed) on gait variability at different locomotion speeds. Ten healthy subjects (32.2 ± 7.9 years, 5 women) walked on a treadmill for 5-min periods at their preferred walking speed and at 20, 40, 70, and 80 % of maximal walking speed during the conditions of walking with eyes open (EO) and with eyes closed (EC). The coefficient of variation (CV) and fractal dimension (α) of the fluctuations in stride time, stride length, and base width were computed and analyzed. Withdrawing visual information increased the base width CV for all walking velocities (p < 0.001). The effects of absent visual information on CV and α of stride time and stride length were most pronounced during slow locomotion (p < 0.001) and declined during fast walking speeds. The results indicate that visual feedback control is used to stabilize the medio-lateral (i.e., base width) gait parameters at all speed sections. In contrast, sensory feedback control in the fore-aft direction (i.e., stride time and stride length) depends on speed. Sensory feedback contributes most to fore-aft gait stabilization during slow locomotion, whereas passive biomechanical mechanisms and an automated central pattern generation appear to control fast locomotion.

  13. Models for Numerical Evaluation of Variable Speed Different Wind Generator Systems

    DEFF Research Database (Denmark)

    Li, Hui; Chen, Zhe; Polinder, H.

    2007-01-01

    of different wind generator systems, the other presents the optimization results and evaluation of variable speed wind generator systems. In this report, firstly, it gives an overview of various wind generator topologies, including their advantages and disadvantages, market status and developing trends. Next...

  14. Analysis of the short-term overproduction capability of variable speed wind turbines

    DEFF Research Database (Denmark)

    Hansen, Anca Daniela; Altin, Müfit; Margaris, Ioannis D.

    2014-01-01

    Emphasis in this article is on variable speed wind turbines (VSWTs) capability to provide short-term overproduction and better understanding of VSWTs’ mechanical and electrical limits to deliver such support. VSWTs’ short-term overproduction capability is of primary concern for the transmission...

  15. Dynamic modelling and analysis of a wind turbine with variable speed

    NARCIS (Netherlands)

    Steinbuch, M.

    1986-01-01

    On behalf of the operation of the Dutch National Wind Farm, which is under construction now, a study is being performed on the control system design of variable speed wind turbines. To realize this a non-linear dynamic model of a wind turbine with synchronous generator and AC/ DC/AC conversion has

  16. Wind tunnel experiments to prove a hydraulic passive torque control concept for variable speed wind turbines

    NARCIS (Netherlands)

    Diepeveen, N.F.B.; Jarquin-Laguna, A.

    2014-01-01

    In this paper the results are presented of experiments to prove an innovative concept for passive torque control of variable speed wind turbines using fluid power technology. It is demonstrated that by correctly configuring the hydraulic drive train, the wind turbine rotor operates at or near

  17. Dynamic Analysis of Fluid Power Drive-trains for Variable Speed Wind Turbines : A Parameter Study

    NARCIS (Netherlands)

    Jarquin Laguna, A.; Diepeveen, N.F.B.

    2013-01-01

    In the pursuit of making wind energy technology more economically attractive, the application of fluid power technology for the transmission of wind energy is being developed by several parties all over the world. This paper presents a dynamic model of a fluid power transmission for variable speed

  18. Evaluation of variable speed limits on I-270/I-255 in St. Louis.

    Science.gov (United States)

    2010-10-01

    In May of 2008, MoDOT installed a Variable Speed Limit (VSL) system along the I270/I255 corridor in St. Louis. This project evaluated the VSL system and its potential impacts and benefits to the transportation users. The technical system ...

  19. Appendices : evaluation of variable speed limits on I-270/I-255 in St. Louis.

    Science.gov (United States)

    2010-10-01

    In May of 2008, MoDOT installed a Variable Speed Limit (VSL) system along the I-270/I-255 corridor in : St. Louis. This project evaluated the VSL system and its potential impacts and benefits to the : transportation users. The technical system ...

  20. Control Method for Variable Speed Wind Turbines to Support Temporary Primary Frequency Control

    DEFF Research Database (Denmark)

    Wang, Haijiao; Chen, Zhe; Jiang, Quanyuan

    2014-01-01

    This paper develops a control method for variable speed wind turbines (VSWTs) to support temporary primary frequency control of power system. The control method contains two parts: (1) up-regulate support control when a frequency drop event occurs; (2) down-regulate support control when a frequen...

  1. A disturbance decoupling nonlinear control law for variable speed wind turbines

    DEFF Research Database (Denmark)

    Thomsen, Sven Creutz; Poulsen, Niels Kjølstad

    2007-01-01

    This paper describes a nonlinear control law for controlling variable speed wind turbines using feedback linearization. The novel aspect of the control law is its ability to decouple the effect of wind fluctuations. Furthermore, the transformation to feedback linearizable coordinates is chosen...

  2. Variability in the Speed of the Brewer-Dobson Circulation as Observed by Aura/MLS

    Science.gov (United States)

    Flury, Thomas; Wu, Dong L.; Read, W. G.

    2013-01-01

    We use Aura/MLS stratospheric water vapour (H2O) measurements as tracer for dynamics and infer interannual variations in the speed of the Brewer-Dobson circulation (BDC) from 2004 to 2011. We correlate one-year time series of H2O in the lower stratosphere at two subsequent pressure levels (68 hPa, approx.18.8 km and 56 hPa, approx 19.9 km at the Equator) and determine the time lag for best correlation. The same calculation is made on the horizontal on the 100 hPa (approx 16.6 km) level by correlating the H2O time series at the Equator with the ones at 40 N and 40 S. From these lag coefficients we derive the vertical and horizontal speeds of the BDC in the tropics and extra-tropics, respectively. We observe a clear interannual variability of the vertical and horizontal branch. The variability reflects signatures of the Quasi Biennial Oscillation (QBO). Our measurements confirm the QBO meridional circulation anomalies and show that the speed variations in the two branches of the BDC are out of phase and fairly well anti-correlated. Maximum ascent rates are found during the QBO easterly phase. We also find that transport of H2O towards the Northern Hemisphere (NH) is on the average two times faster than to the Southern Hemisphere (SH) with a mean speed of 1.15m/s at 100 hPa. Furthermore, the speed towards the NH shows much more interannual variability with an amplitude of about 21% whilst the speed towards the SH varies by only 10 %. An amplitude of 21% is also observed in the variability of the ascent rate at the Equator which is on the average 0.2mm/s.

  3. Wind tunnel experiments to prove a hydraulic passive rotor speed control concept for variable speed wind turbines (poster)

    NARCIS (Netherlands)

    Diepeveen, N.F.B.; Jarquin Laguna, A.

    2012-01-01

    As alternative to geared and direct drive solutions, fluid power drive trains are being developed by several institutions around the world. The common configuration is where the wind turbine rotor is coupled to a hydraulic pump. The pump is connected through a high pressure line to a hydraulic motor

  4. Energy and economic analysis of an ICE-based variable speed-operated micro-cogenerator

    Energy Technology Data Exchange (ETDEWEB)

    Caresana, Flavio; Bartolini, Carlo Maria [Universita Politecnica delle Marche, Dipartimento di Energetica, Via Brecce Bianche, Ancona (AN) 60100 (Italy); Brandoni, Caterina [Universita Telematica e-Campus, Ingegneria Energetica, Via Isimbardi 10, Novedrate (CO) 22060 (Italy); Feliciotti, Petro [Universita Politecnica delle Marche, Dipartimento di Ingegneria Informatica, Gestionale e dell' Automazione, Via Brecce Bianche, Ancona (AN) 60100 (Italy)

    2011-03-15

    Micro-combined heat and power (CHP) systems are a key resource to meet the EUCO{sub 2} reduction agreed in the Kyoto Protocol. In the near future they are likely to spread significantly through applications in the residential and service sectors, since they can provide considerably higher primary energy efficiencies than plants generating electricity and heat separately. A 28 kW{sub e} natural gas, automotive-derived internal combustion engine CHP system was modeled with a view to comparing constant and variable speed operation modes. Besides their energy performances, the paper addresses the major factors involved in their economic evaluation and describes a method to assess their economic feasibility. Typical residential and service sector applications were chosen as test cases and the results discussed in terms of energy performances and of profitability. They showed that interesting savings can be obtained with respect to separate generation, and that they are higher for the household application in variable speed operating conditions. In fact the plant's energy performance is greatly enhanced by the possibility, for any given power, to regulate the engine's rotational speed. From the economic viewpoint, despite the higher initial cost of the variable speed concept, the system involves a shorter pay-back period and ensures greater profit. (author)

  5. Energy and economic analysis of an ICE-based variable speed-operated micro-cogenerator

    International Nuclear Information System (INIS)

    Caresana, Flavio; Brandoni, Caterina; Feliciotti, Petro; Bartolini, Carlo Maria

    2011-01-01

    Micro-combined heat and power (CHP) systems are a key resource to meet the EUCO 2 reduction agreed in the Kyoto Protocol. In the near future they are likely to spread significantly through applications in the residential and service sectors, since they can provide considerably higher primary energy efficiencies than plants generating electricity and heat separately. A 28 kW e natural gas, automotive-derived internal combustion engine CHP system was modeled with a view to comparing constant and variable speed operation modes. Besides their energy performances, the paper addresses the major factors involved in their economic evaluation and describes a method to assess their economic feasibility. Typical residential and service sector applications were chosen as test cases and the results discussed in terms of energy performances and of profitability. They showed that interesting savings can be obtained with respect to separate generation, and that they are higher for the household application in variable speed operating conditions. In fact the plant's energy performance is greatly enhanced by the possibility, for any given power, to regulate the engine's rotational speed. From the economic viewpoint, despite the higher initial cost of the variable speed concept, the system involves a shorter pay-back period and ensures greater profit.

  6. Control of variable speed wind turbines with doubly-fed induction generators

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, A.D.; Soerensen, P.; Iov, F.; Blaabjerg, F.

    2005-07-01

    The paper presents an overall control method for variable speed pitch controlled wind turbines with doubly-fed induction generators (DFIG). Emphasis is on control strategies and algorithms applied at each hierarchical control level of the wind turbine. The objectives of the control system are: 1) to control the power drawn from the wind turbine in order to track the wind turbine maximum power operation point, 2) to limit the power in case of large wind speeds, and 3) to control the reactive power interchanged between the wind turbine generator and the grid. The present control method is designed for normal continuous operations. The strongest feature of the implemented control method is that it allows the turbine to operate with the optimum power efficiency over a wide range of wind speeds. The model of the variable speed, variable pitch wind turbine with doubly-fed induction generator is implemented in the dynamic power system simulation tool DlgSILENT PowerFactory which allows investigation of the dynamic performance of grid-connected wind turbines within realistic electrical grid models. Simulation results are presented and analysed in different normal operating conditions. (author)

  7. Variable-Speed Power-Turbine Research at Glenn Research Center

    Science.gov (United States)

    Welch, Gerard E.; McVetta, Ashlie B.; Stevens, Mark A.; Howard, Samuel A.; Giel, Paul W.; Ameri, Ali, A.; To, Waiming; Skoch, Gary J.; Thurman, Douglas R.

    2012-01-01

    The main rotors of the NASA Large Civil Tilt-Rotor (LCTR) notional vehicle operate over a wide speed-range, from 100 percent at takeoff to 54 percent at cruise. The variable-speed power turbine (VSPT) offers one approach by which to effect this speed variation. VSPT aerodynamics challenges include high work factors at cruise, wide (40 to 60 ) incidence-angle variations in blade and vane rows over the speed range, and operation at low Reynolds numbers. Rotordynamics challenges include potential responsiveness to shaft modes within the 50 percent VSPT speed-range. A research effort underway at NASA Glenn Research Center, intended to address these key aerodynamic and rotordynamic challenges, is described. Conceptual design and 3-D multistage RANS and URANS analyses, conducted internally and under contract, provide expected VSPT sizing, stage-count, performance and operability information, and maps for system studies. Initial steps toward experimental testing of incidence-tolerant blading in a transonic linear cascade are described, and progress toward development/improvement of a simulation capability for multistage turbines with low Reynolds number transitional flow is summarized. Preliminary rotordynamics analyses indicate that viable concept engines with 50 percent VSPT shaft-speed range. Assessments of potential paths toward VSPT component-level testing are summarized.

  8. Modeling and control of a variable-speed wind turbine equipped with permanent magnet synchronous generator

    Energy Technology Data Exchange (ETDEWEB)

    Aliprantis, D.C.; Papathanassiou, S.A.; Papadopoulos, M.P.; Kladas, A.G. [Purdue University, Electrical and Computer Engineering, West Lafayette, IN (United States)

    2000-08-01

    In this paper the operation of a variable-speed, stall regulated wind turbine equipped with a permanent magnet synchronous generator (PMSG) is examined. The emphasis is placed on the analysis of the electric part of the system, i.e. the electrical generator, the power electronics converters and the control. The operational characteristics of the machine are investigated through a series of computer simulations and the speed control system is designed to maximize the power output and achieve a smooth torque and power profile. (orig.)

  9. Silicon photonic transceiver circuit for high-speed polarization-based discrete variable quantum key distribution.

    Science.gov (United States)

    Cai, Hong; Long, Christopher M; DeRose, Christopher T; Boynton, Nicholas; Urayama, Junji; Camacho, Ryan; Pomerene, Andrew; Starbuck, Andrew L; Trotter, Douglas C; Davids, Paul S; Lentine, Anthony L

    2017-05-29

    We demonstrate a silicon photonic transceiver circuit for high-speed discrete variable quantum key distribution that employs a common structure for transmit and receive functions. The device is intended for use in polarization-based quantum cryptographic protocols, such as BB84. Our characterization indicates that the circuit can generate the four BB84 states (TE/TM/45°/135° linear polarizations) with >30 dB polarization extinction ratios and gigabit per second modulation speed, and is capable of decoding any polarization bases differing by 90° with high extinction ratios.

  10. Experimental research of variable rotation speed ICE-based electric power station

    Directory of Open Access Journals (Sweden)

    Dar’enkov Andrey

    2017-01-01

    Full Text Available Developing variable rotation speed ICE-based stand-alone electric power stations which can supply distant regions and autonomous objects with electricity are of scientific interest due to the insufficient study. The relevance of developing such electric power stations is determined by their usage is to provide a significant fuel saving as well as increase ICE motor service life. The article describes the electric station of autonomous objects with improved fuel economy. The article describes multivariate characteristic. Multivariate characteristic shows the optimal frequency of rotation of the internal combustion engine. At this rotational speed there is the greatest fuel economy.

  11. Power Control of Permanent Magnet Generator Based Variable Speed Wind Turbines

    DEFF Research Database (Denmark)

    Deng, Fujin; Chen, Zhe

    2009-01-01

    When the wind power accounts for a large portion of the grid, it will be required to regulate the active power and reactive power. This paper investigates a MWlevel variable speed wind turbine with a permanent magnet synchronous generator (PMSG). The power control capabilities of two kinds...... of control schemes conducted respectively on this wind turbine under two conditions, including rapid wind speed change and grids faults, are compared. The simulation study of the wind turbine system is conducted using PSCAD/EMTDC, and the results show the different power control capabilities of the two...

  12. Frequency support capability of variable speed wind turbine based on electromagnetic coupler

    DEFF Research Database (Denmark)

    You, Rui; Barahona Garzón, Braulio; Chai, Jianyun

    2015-01-01

    In the variable speed wind turbine based on electromagnetic coupler (WT-EMC), a synchronous generator is directly coupled with grid. So like conventional power plants WT-EMC is able to support grid frequency inherently. But due to the reduced inertia of synchronous generator, its frequency support...... capability has to be enhanced. In this paper, the frequency support capability of WT-EMC is studied at three typical wind conditions and with two control strategies-droop control and inertial control to enhance its frequency support capability. The synchronous generator speed, more stable than the grid...

  13. Analysis of the cylinder block tilting inertia moment and its effect on the performance of high-speed electro-hydrostatic actuator pumps of aircraft

    Directory of Open Access Journals (Sweden)

    Junhui ZHANG

    2018-01-01

    Full Text Available Electro-hydrostatic actuator (EHA pumps are usually characterized as high speed and small displacement. The tilting inertia moment on the cylinder block produced by the inertia forces of piston/slipper assemblies cannot be ignored when analyzing the cylinder block balance. A large tilting inertia moment will make the cylinder block tilt away from the valve plate, resulting in severe wear and significantly increased leakage. This paper presents an analytical expression for the tilting inertia moment on the cylinder block by means of vector analysis. In addition, a high-speed test rig was built up, and experiments on an EHA pump prototype were carried out at high speeds of up to 10,000 r/min. The predicted nature of the cylinder block tilt at high speeds corresponds closely to the witness marks on the dismantled EHA pump prototype. It is suggested that more attention should be given to the tilting inertia moment acting on the cylinder block of an EHA pump since both wear and leakage flow between the cylinder block and the valve plate are very much dependent on this tilting moment.

  14. Design study and performance analysis of a high-speed multistage variable-geometry fan for a variable cycle engine

    Science.gov (United States)

    Sullivan, T. J.; Parker, D. E.

    1979-01-01

    A design technology study was performed to identify a high speed, multistage, variable geometry fan configuration capable of achieving wide flow modulation with near optimum efficiency at the important operating condition. A parametric screening study of the front and rear block fans was conducted in which the influence of major fan design features on weight and efficiency was determined. Key design parameters were varied systematically to determine the fan configuration most suited for a double bypass, variable cycle engine. Two and three stage fans were considered for the front block. A single stage, core driven fan was studied for the rear block. Variable geometry concepts were evaluated to provide near optimum off design performance. A detailed aerodynamic design and a preliminary mechanical design were carried out for the selected fan configuration. Performance predictions were made for the front and rear block fans.

  15. Integrated Variable Speed Limits Control and Ramp Metering for Bottleneck Regions on Freeway

    Directory of Open Access Journals (Sweden)

    Ming-hui Ma

    2015-01-01

    Full Text Available To enhance the efficiency of the existing freeway system and therefore to mitigate traffic congestion and related problems on the freeway mainline lane-drop bottleneck region, the advanced strategy for bottleneck control is essential. This paper proposes a method that integrates variable speed limits and ramp metering for freeway bottleneck region control to relieve the chaos in bottleneck region. To this end, based on the analyses of spatial-temporal patterns of traffic flow, a macroscopic traffic flow model is extended to describe the traffic flow operating characteristic by considering the impacts of variable speed limits in mainstream bottleneck region. In addition, to achieve the goal of balancing the priority of the vehicles on mainline and on-ramp, increasing capacity, and reducing travel delay on bottleneck region, an improved control model, as well as an advanced control strategy that integrates variable speed limits and ramp metering, is developed. The proposed method is tested in simulation for a real freeway infrastructure feed and calibrates real traffic variables. The results demonstrate that the proposed method can substantially improve the traffic flow efficiency of mainline and on-ramp and enhance the quality of traffic flow at the investigated freeway mainline bottleneck.

  16. A Neural Network Controller for Variable-Speed Variable-Pitch Wind Energy Conversion Systems Using Generalized Minimum Entropy Criterion

    Directory of Open Access Journals (Sweden)

    Mifeng Ren

    2014-01-01

    Full Text Available This paper considers the neural network controller design problem for variable pitch wind energy conversion systems (WECS with non-Gaussian wind speed disturbances in the stochastic distribution control framework. The approach here is used to directly model the unknown control law based on a fixed neural network (the number of layers and nodes in a neural network is fixed without the need to construct a separate model for the WECS. In order to characterize the randomness of the WECS, a generalized minimum entropy criterion is established to train connection weights of the neural network. For the train purpose, both kernel density estimation method and sliding window technique are adopted to estimate the PDF of tracking error and entropies. Due to the unknown process dynamics, the gradient of the objective function in a gradient-descent-type algorithm is estimated using an incremental perturbation method. The proposed approach is illustrated on a simulated WECS with non-Gaussian wind speed.

  17. Stability Augmentation of Wind Farm using Variable Speed Permanent Magnet Synchronous Generator

    Science.gov (United States)

    Rosyadi, Marwan; Muyeen, S. M.; Takahashi, Rion; Tamura, Junji

    This paper presents a new control strategy of variable speed permanent magnet wind generator for stability augmentation of wind farm including fixed speed wind turbine with Induction Generator (IG). A new control scheme is developed for two levels back-to-back converters of Permanent Magnet Synchronous Generator (PMSG), by which both active and reactive powers delivered to the grid can be controlled easily. To avoid the converter damage, the DC link protection controller is also proposed in order to protect the dc link circuit during fault condition. To evaluate the control capability of the proposed controllers, simulations are performed on two model systems composed of wind farms connected to an infinite bus. From transient and steady state analyses by using PSCAD/EMTDC, it is concluded that the proposed control scheme is very effective to improve the stability of wind farm for severe network disturbance and randomly fluctuating wind speed.

  18. Power Maximization Control of Variable Speed Wind Generation System Using Permanent Magnet Synchronous Generator

    Science.gov (United States)

    Morimoto, Shigeo; Nakamura, Tomohiko; Takeda, Yoji

    This paper proposes the sensorless output power maximization control of the wind generation system. A permanent magnet synchronous generator (PMSG) is used as a variable speed generator in the proposed system. The generator torque is suitably controlled according to the generator speed and thus the power from a wind turbine settles down on the maximum power point by the proposed MPPT control method, where the information of wind velocity is not required. Moreover, the maximum available generated power is obtained by the optimum current vector control. The current vector of PMSG is optimally controlled according to the generator speed and the required torque in order to minimize the losses of PMSG considering the voltage and current constraints. The proposed wind power generation system can be achieved without mechanical sensors such as a wind velocity detector and a position sensor. Several experimental results show the effectiveness of the proposed control method.

  19. DAC with LQR Control Design for Pitch Regulated Variable Speed Wind Turbine

    DEFF Research Database (Denmark)

    Imran, Raja Muhammad; Hussain, Dil Muhammad Akbar; Soltani, Mohsen

    2014-01-01

    Disturbance Accommodation Control (DAC) is used to model and simulate a system with known disturbance waveform. This paper presents a control scheme to mitigate the effect of disturbances by using collective pitch control for the aboverated wind speed (Region III) for a variable speed wind turbine....... We have used Linear Quadratic Regulator (LQR) to obtain full state feedback gain, disturbance feedback gain is calculated independently and then estimator gain is achieved by poleplacement technique in the DAC augmented plant model. The reduced order model (two-mass model) of wind turbine is used...... and 5MW National Renewable Energy Laboratory (NREL) wind turbine is used in this research. We have shown comparison of results relating to pitch angle, drive train torsion and generator speed obtained by a PID controller and DAC. Simulations are performed in MATLAB/Simulink. The results are compared...

  20. Modeling and Design Optimization of Variable-Speed Wind Turbine Systems

    Directory of Open Access Journals (Sweden)

    Ulas Eminoglu

    2014-01-01

    Full Text Available As a result of the increase in energy demand and government subsidies, the usage of wind turbine system (WTS has increased dramatically. Due to the higher energy production of a variable-speed WTS as compared to a fixed-speed WTS, the demand for this type of WTS has increased. In this study, a new method for the calculation of the power output of variable-speed WTSs is proposed. The proposed model is developed from the S-type curve used for population growth, and is only a function of the rated power and rated (nominal wind speed. It has the advantage of enabling the user to calculate power output without using the rotor power coefficient. Additionally, by using the developed model, a mathematical method to calculate the value of rated wind speed in terms of turbine capacity factor and the scale parameter of the Weibull distribution for a given wind site is also proposed. Design optimization studies are performed by using the particle swarm optimization (PSO and artificial bee colony (ABC algorithms, which are applied into this type of problem for the first time. Different sites such as Northern and Mediterranean sites of Europe have been studied. Analyses for various parameters are also presented in order to evaluate the effect of rated wind speed on the design parameters and produced energy cost. Results show that proposed models are reliable and very useful for modeling and optimization of WTSs design by taking into account the wind potential of the region. Results also show that the PSO algorithm has better performance than the ABC algorithm for this type of problem.

  1. Intra-individual variability in information processing speed reflects white matter microstructure in multiple sclerosis.

    Science.gov (United States)

    Mazerolle, Erin L; Wojtowicz, Magdalena A; Omisade, Antonina; Fisk, John D

    2013-01-01

    Slowed information processing speed is commonly reported in persons with multiple sclerosis (MS), and is typically investigated using clinical neuropsychological tests, which provide sensitive indices of mean-level information processing speed. However, recent studies have demonstrated that within-person variability or intra-individual variability (IIV) in information processing speed may be a more sensitive indicator of neurologic status than mean-level performance on clinical tests. We evaluated the neural basis of increased IIV in mildly affected relapsing-remitting MS patients by characterizing the relation between IIV (controlling for mean-level performance) and white matter integrity using diffusion tensor imaging (DTI). Twenty women with relapsing-remitting MS and 20 matched control participants completed the Computerized Test of Information Processing (CTIP), from which both mean response time and IIV were calculated. Other clinical measures of information processing speed were also collected. Relations between IIV on the CTIP and DTI metrics of white matter microstructure were evaluated using tract-based spatial statistics. We observed slower and more variable responses on the CTIP in MS patients relative to controls. Significant relations between white matter microstructure and IIV were observed for MS patients. Increased IIV was associated with reduced integrity in more white matter tracts than was slowed information processing speed as measured by either mean CTIP response time or other neuropsychological test scores. Thus, despite the common use of mean-level performance as an index of cognitive dysfunction in MS, IIV may be more sensitive to the overall burden of white matter disease at the microstructural level. Furthermore, our study highlights the potential value of considering within-person fluctuations, in addition to mean-level performance, for uncovering brain-behavior relationships in neurologic disorders with widespread white matter pathology.

  2. Modeling, Simulation and Control of Matrix Convert for Variable Speed Wind Turbine System

    Directory of Open Access Journals (Sweden)

    M. Alizadeh Moghadam

    2015-09-01

    Full Text Available This paper presents modeling, simulation and control of matrix converter (MC for variable speed wind turbine (VSWT system including permanent magnet synchronous generator (PMSG. At a given wind velocity, the power available from a wind turbine is a function of its shaft speed. In order to track maximum power, the MC adjusts the PMSG shaft speed.The proposed control system allowing independent control maximum power point tracking (MPPT of generator side and regulate reactive power of grid side for the operation of the VSWT system. The MPPT is implemented by a new control system. This control system is based on control of zero d-axis current (ZDC. The ZDC control can be realized by transfer the three-phase stator current in the stationary reference frame into d-and q-axis components in the synchronous reference frame. Also this paper is presented, a novel control strategy to regulate the reactive power supplied by a variable speed wind energy conversion system. This control strategy is based on voltage oriented control (VOC. The simulation results based on Simulink/Matlab software show that the controllers can extract maximum power and regulate reactive power under varying wind velocities.

  3. A New Fault Diagnosis Algorithm for PMSG Wind Turbine Power Converters under Variable Wind Speed Conditions

    Directory of Open Access Journals (Sweden)

    Yingning Qiu

    2016-07-01

    Full Text Available Although Permanent Magnet Synchronous Generator (PMSG wind turbines (WTs mitigate gearbox impacts, they requires high reliability of generators and converters. Statistical analysis shows that the failure rate of direct-drive PMSG wind turbines’ generators and inverters are high. Intelligent fault diagnosis algorithms to detect inverters faults is a premise for the condition monitoring system aimed at improving wind turbines’ reliability and availability. The influences of random wind speed and diversified control strategies lead to challenges for developing intelligent fault diagnosis algorithms for converters. This paper studies open-circuit fault features of wind turbine converters in variable wind speed situations through systematic simulation and experiment. A new fault diagnosis algorithm named Wind Speed Based Normalized Current Trajectory is proposed and used to accurately detect and locate faulted IGBT in the circuit arms. It is compared to direct current monitoring and current vector trajectory pattern approaches. The results show that the proposed method has advantages in the accuracy of fault diagnosis and has superior anti-noise capability in variable wind speed situations. The impact of the control strategy is also identified. Experimental results demonstrate its applicability on practical WT condition monitoring system which is used to improve wind turbine reliability and reduce their maintenance cost.

  4. Feasibility of a Simple Small Wind Turbine with Variable-Speed Regulation Made of Commercial Components

    Directory of Open Access Journals (Sweden)

    Jesús Peláez Vara

    2013-07-01

    Full Text Available The aim of this study was to propose and evaluate a very small wind turbine (VSWT that competes with commercial grid-connected VSWTs in terms of simplicity, robustness and price. Its main components are a squirrel-cage induction generator (SCIG driven by a frequency converter. The system has a direct-drive shaft, and may be constructed with commercial equipment. Simulation of the wind turbine effect is done with a motor. A control program regulates the variable-speed of rotation through three operational modes: (i to drive the turbine to its optimum operation point; (ii to limit its maximum rotational speed; and (iii to limit the maximum power it generates. Two tests were performed, in order to evaluate the dynamic response of this system under variable wind speeds. The tests demonstrate that the system operates at the optimum operational point of the turbine, and within the set limits of maximum rotational speed and maximum generated power. The drop in performance in relation to its nominal value is about 75%, when operating at 50% of the nominal power. In summary, this VSWT with its proposed control program is feasible and reliable for operating direct-shaft grid-connected VSWTs.

  5. A New Structure Based on Cascaded Multilevel Converter for Variable Speed Wind Turbine

    DEFF Research Database (Denmark)

    Deng, Fujin; Chen, Zhe

    2010-01-01

    An alternative structure for variable speed wind turbine, using multiple permanent magnet synchronous generators (PMSGs) drive-train configuration and cascaded multilevel converter is proposed in this paper. This study presents a power electronic solution for the wind turbine. A transformer......-less cascaded multilevel converter interface based on PMSGs is developed to synthesize a desired high ac sinusoidal output voltage. The benefits of high power and high ac voltage make this structure possible to be applied in the wind power generation. In addition, the bulky transformer could be omitted....... A simulation model of 10 MW variable speed wind turbine based on PMSGs developed in PSCAD/EMTDC is presented. The dynamic performance of grid-connected wind turbine is analyzed. Simulation results shows that the proposed structure may be attractive in wind power generation....

  6. Modelling and control algorithms of the cross conveyors line with multiengine variable speed drives

    Science.gov (United States)

    Cheremushkina, M. S.; Baburin, S. V.

    2017-02-01

    The paper deals with the actual problem of developing the control algorithm that meets the technical requirements of the mine belt conveyors, and enables energy and resource savings taking into account a random sort of traffic. The most effective method of solution of these tasks is the construction of control systems with the use of variable speed drives for asynchronous motors. The authors designed the mathematical model of the system ‘variable speed multiengine drive - conveyor - control system of conveyors’ that takes into account the dynamic processes occurring in the elements of the transport system, provides an assessment of the energy efficiency of application the developed algorithms, which allows one to reduce the dynamic overload in the belt to 15-20%.

  7. Variable Speed Wind Turbine Based on Multiple Generators Drive-Train Configuration

    DEFF Research Database (Denmark)

    Deng, Fujin; Chen, Zhe

    2010-01-01

    A variable speed wind turbine is presented in this paper, where multiple permanent magnet synchronous generators (MPMSGs) drive-train configuration is employed in the wind turbine. A cascaded multilevel converter interface based on the MPMSGs is developed to synthesize a desired high ac sinusoidal...... output voltage, which could be directly connected to the grids. What is more, such arrangement has been made so that the output ac voltage having a selected phase angle difference among the stator windings of multiple generators. A phase angle shift strategy is proposed in this paper, which effectively...... reduce the fluctuation of the electromagnetic torque sum and results in a good performance for the MPMSGs structure. The simulation study is conducted using PSCAD/EMTDC, and the results verify the feasibility of this variable speed wind turbine based on multiple generators drive-train configuration....

  8. Perfection of badminton players’ speed-power fitness with the help of training means’ variable modules

    Directory of Open Access Journals (Sweden)

    I.V. Karatnyk

    2016-06-01

    Full Text Available Purpose: to determine effectiveness of badminton players’ speed power fitness program’s perfection at stage of specialized basic training with different variants of training means modules’ combination. Material: in experiment badminton players of 15-17 years’ age (from 1st sports grade to master of sports participated. The sportsmen were divided into three experimental groups (10 persons in each. The trainings were being conducted during 24 weeks by different variants of program. Results: we created different complexes of exercises, combined in three modules (every of each lasted eight week micro-cycles. Every module has more expressed meaningful parts (1 – speed, 2 – power, 3 – jumping. All modules were combined in program of badminton players’ speed power fitness perfection. For every experimental group we worked out distinguishing variant of modules’ combination in program (first variant – 1-2-3 modules; second – 2-3-1; third – 3-1-2. General duration of program was 24 week micro-cycles. Conclusions: we recommended some variants of variable modules’ combination for badminton players’ speed-power fitness perfection. With it, we can regard total influence on the following: speed-power endurance, work with support on own body, quick movements of different body links.

  9. Variable-speed wind power system with improved energy capture via multilevel conversion

    Science.gov (United States)

    Erickson, Robert W.; Al-Naseem, Osama A.; Fingersh, Lee Jay

    2005-05-31

    A system and method for efficiently capturing electrical energy from a variable-speed generator are disclosed. The system includes a matrix converter using full-bridge, multilevel switch cells, in which semiconductor devices are clamped to a known constant DC voltage of a capacitor. The multilevel matrix converter is capable of generating multilevel voltage wave waveform of arbitrary magnitude and frequencies. The matrix converter can be controlled by using space vector modulation.

  10. Level of recall, retrieval speed, and variability on the Cued-Recall Retrieval Speed Task (CRRST) in individuals with amnestic mild cognitive impairment.

    Science.gov (United States)

    Ramratan, Wendy S; Rabin, Laura A; Wang, Cuiling; Zimmerman, Molly E; Katz, Mindy J; Lipton, Richard B; Buschke, Herman

    2012-03-01

    Individuals with amnestic mild cognitive impairment (aMCI) show deficits on traditional episodic memory tasks and reductions in speed of performance on reaction time tasks. We present results on a novel task, the Cued-Recall Retrieval Speed Task (CRRST), designed to simultaneously measure level and speed of retrieval. A total of 390 older adults (mean age, 80.2 years), learned 16 words based on corresponding categorical cues. In the retrieval phase, we measured accuracy (% correct) and retrieval speed/reaction time (RT; time from cue presentation to voice onset of a correct response) across 6 trials. Compared to healthy elderly adults (HEA, n = 303), those with aMCI (n = 87) exhibited poorer performance in retrieval speed (difference = -0.13; p cued-learning and processing speed variability may facilitate early detection of dementia in at-risk older adults.

  11. 75 FR 2159 - In the Matter of Certain Variable Speed Wind Turbines and Components Thereof; Termination of...

    Science.gov (United States)

    2010-01-14

    ... INTERNATIONAL TRADE COMMISSION [Investigation No. 337-TA-641] In the Matter of Certain Variable Speed Wind Turbines and Components Thereof; Termination of Investigation With Final Determination of No..., and the sale within the United States after importation of certain variable speed wind turbines and...

  12. Development of The Structural and Functional Design of the Laboratory Bench for Experimental Research Diesel Generator Sets on Variable Speed

    Directory of Open Access Journals (Sweden)

    Obuhov Sergei

    2017-01-01

    Full Text Available A diesel generator set working at variable speed to save fuel is studied. A description is provided of a laboratory bench for conducting experimental studies of a variable speed diesel generator set. Its component parts are described, and its technical characteristics are given.

  13. Hydraulic development of high specific-speed pump-turbines by means of an inverse design method, numerical flow-simulation (CFD) and model testing

    International Nuclear Information System (INIS)

    Kerschberger, P; Gehrer, A

    2010-01-01

    In recent years an increased interest in pump-turbines has been recognized in the market. The rapid availability of pumped storage schemes and the benefits to the power system by peak lopping, providing reserve and rapid response for frequency control are becoming of growing advantage. In that context it is requested to develop pump-turbines that reliably stand dynamic operation modes, fast changes of the discharge rate by adjusting the variable diffuser vanes as well as fast changes from pump to turbine operation. Within the present study various flow patterns linked to the operation of a pump-turbine system are discussed. In that context pump and turbine mode are presented separately and different load cases at both operation modes are shown. In order to achieve modern, competitive pump-turbine designs it is further explained which design challenges should be considered during the geometry definition of a pump-turbine impeller. Within the present study a runner-blade profile for a low head pump-turbine has been developed. For the initial hydraulic runner-blade design, an inverse design method has been applied. Within this design procedure, a first blade geometry is generated by imposing the pressure loading-distribution and by means of an inverse 3D potential-flow-solution. The hydraulic behavior of both, pump-mode and turbine-mode is then evaluated by solving the full 3D Navier-Stokes equations in combination with a robust turbulence model. Based on this initial design the blade profile has been further optimized and redesigned considering various hydraulic pump-turbine requirements. Finally, the progress in hydraulic design is demonstrated by model test results which show a significant improvement in hydraulic performance compared to an existing reference design.

  14. Hydraulic development of high specific-speed pump-turbines by means of an inverse design method, numerical flow-simulation (CFD) and model testing

    Science.gov (United States)

    Kerschberger, P.; Gehrer, A.

    2010-08-01

    In recent years an increased interest in pump-turbines has been recognized in the market. The rapid availability of pumped storage schemes and the benefits to the power system by peak lopping, providing reserve and rapid response for frequency control are becoming of growing advantage. In that context it is requested to develop pump-turbines that reliably stand dynamic operation modes, fast changes of the discharge rate by adjusting the variable diffuser vanes as well as fast changes from pump to turbine operation. Within the present study various flow patterns linked to the operation of a pump-turbine system are discussed. In that context pump and turbine mode are presented separately and different load cases at both operation modes are shown. In order to achieve modern, competitive pump-turbine designs it is further explained which design challenges should be considered during the geometry definition of a pump-turbine impeller. Within the present study a runner-blade profile for a low head pump-turbine has been developed. For the initial hydraulic runner-blade design, an inverse design method has been applied. Within this design procedure, a first blade geometry is generated by imposing the pressure loading-distribution and by means of an inverse 3D potential-flow-solution. The hydraulic behavior of both, pump-mode and turbine-mode is then evaluated by solving the full 3D Navier-Stokes equations in combination with a robust turbulence model. Based on this initial design the blade profile has been further optimized and redesigned considering various hydraulic pump-turbine requirements. Finally, the progress in hydraulic design is demonstrated by model test results which show a significant improvement in hydraulic performance compared to an existing reference design.

  15. Low-Voltage Ride-Through of Variable Speed Wind Turbines with Permanent Magnet Synchronous Generator

    DEFF Research Database (Denmark)

    Deng, Fujin; Chen, Zhe

    2009-01-01

    This paper presents a simulation model of a MW-level variable speed wind turbine with a permanent magnet synchronous generator (PMSG) and a full-scale converter developed in the simulation tool of PSCAD/EMTDC. The low voltage ride-through (LVRT) capability of the wind turbine is investigated. A new...... control scheme for the wind turbine that keeps it connected to the grid during grid faults is designed and simulated. Its design has special focus on the regulation of the DC-link voltage. Simulation results show the proposed control scheme is an effective measure to improve LVRT capability of variable...

  16. Technical Subtopic 2.1: Modeling Variable Refrigerant Flow Heat Pump and Heat Recovery Equipment in EnergyPlus

    Energy Technology Data Exchange (ETDEWEB)

    Raustad, Richard; Nigusse, Bereket; Domitrovic, Ron

    2013-09-30

    enthalpy method where relevant air-side parameters were controlled while collecting output performance data at discreet points of steady-state operation. The primary metrics include system power consumption and zonal heating and cooling capacity. Using this test method, the measured total cooling capacity was somewhat lower than reported by the manufacturer. The measured power was found to be equal to or greater than the manufacturers indicated power. Heating capacity measurements produced similar results. The air-side performance metric was total cooling and heating energy since the computer model uses those same metrics as input to the model. Although the sensible and latent components of total cooling were measured, they are not described in this report. The test methodology set the thermostat set point temperature very low for cooling and very high for heating to measure full-load performance and was originally thought to provide the maximum available capacity. Manufacturers stated that this test method would not accurately measure performance of VRF systems which is now believed to be a true statement. Near the end of the project, an alternate test method was developed to better represent VRF system performance as if field installed. This method of test is preliminarily called the Load Based Method of Test where the load is fixed and the indoor conditions and unit operation are allowed to fluctuate. This test method was only briefly attempted in a laboratory setting but does show promise for future lab testing. Since variable-speed air-conditioners and heat pumps include an on-board control algorithm to modulate capacity, these systems are difficult to test. Manufacturers do have the ability to override internal components to accommodate certification procedures, however, it is unknown if the resulting operation is replicated in the field, or if so, how often. Other studies have shown that variable-speed air-conditioners and heat pumps do out perform their single-speed

  17. High-speed limnology: using advanced sensors to investigate spatial variability in biogeochemistry and hydrology.

    Science.gov (United States)

    Crawford, John T; Loken, Luke C; Casson, Nora J; Smith, Colin; Stone, Amanda G; Winslow, Luke A

    2015-01-06

    Advanced sensor technology is widely used in aquatic monitoring and research. Most applications focus on temporal variability, whereas spatial variability has been challenging to document. We assess the capability of water chemistry sensors embedded in a high-speed water intake system to document spatial variability. This new sensor platform continuously samples surface water at a range of speeds (0 to >45 km h(-1)) resulting in high-density, mesoscale spatial data. These novel observations reveal previously unknown variability in physical, chemical, and biological factors in streams, rivers, and lakes. By combining multiple sensors into one platform, we were able to detect terrestrial-aquatic hydrologic connections in a small dystrophic lake, to infer the role of main-channel vs backwater nutrient processing in a large river and to detect sharp chemical changes across aquatic ecosystem boundaries in a stream/lake complex. Spatial sensor data were verified in our examples by comparing with standard lab-based measurements of selected variables. Spatial fDOM data showed strong correlation with wet chemistry measurements of DOC, and optical NO3 concentrations were highly correlated with lab-based measurements. High-frequency spatial data similar to our examples could be used to further understand aquatic biogeochemical fluxes, ecological patterns, and ecosystem processes, and will both inform and benefit from fixed-site data.

  18. Clinical Impact of Speed Variability to Identify Ultramarathon Runners at Risk for Acute Kidney Injury.

    Directory of Open Access Journals (Sweden)

    Sen-Kuang Hou

    Full Text Available Ultramarathon is a high endurance exercise associated with a wide range of exercise-related problems, such as acute kidney injury (AKI. Early recognition of individuals at risk of AKI during ultramarathon event is critical for implementing preventative strategies.To investigate the impact of speed variability to identify the exercise-related acute kidney injury anticipatively in ultramarathon event.This is a prospective, observational study using data from a 100 km ultramarathon in Taipei, Taiwan. The distance of entire ultramarathon race was divided into 10 splits. The mean and variability of speed, which was determined by the coefficient of variation (CV in each 10 km-split (25 laps of 400 m oval track were calculated for enrolled runners. Baseline characteristics and biochemical data were collected completely 1 week before, immediately post-race, and one day after race. The main outcome was the development of AKI, defined as Stage II or III according to the Acute Kidney Injury Network (AKIN criteria. Multivariate analysis was performed to determine the independent association between variables and AKI development.26 ultramarathon runners were analyzed in the study. The overall incidence of AKI (in all Stages was 84.6% (22 in 26 runners. Among these 22 runners, 18 runners were determined as Stage I, 4 runners (15.4% were determined as Stage II, and none was in Stage III. The covariates of BMI (25.22 ± 2.02 vs. 22.55 ± 1.96, p = 0.02, uric acid (6.88 ± 1.47 vs. 5.62 ± 0.86, p = 0.024, and CV of speed in specific 10-km splits (from secondary 10 km-split (10th - 20th km-split to 60th - 70th km-split were significantly different between runners with or without AKI (Stage II in univariate analysis and showed discrimination ability in ROC curve. In the following multivariate analysis, only CV of speed in 40th - 50th km-split continued to show a significant association to the development of AKI (Stage II (p = 0.032.The development of exercise

  19. Power maximization of variable-speed variable-pitch wind turbines using passive adaptive neural fault tolerant control

    Science.gov (United States)

    Habibi, Hamed; Rahimi Nohooji, Hamed; Howard, Ian

    2017-09-01

    Power maximization has always been a practical consideration in wind turbines. The question of how to address optimal power capture, especially when the system dynamics are nonlinear and the actuators are subject to unknown faults, is significant. This paper studies the control methodology for variable-speed variable-pitch wind turbines including the effects of uncertain nonlinear dynamics, system fault uncertainties, and unknown external disturbances. The nonlinear model of the wind turbine is presented, and the problem of maximizing extracted energy is formulated by designing the optimal desired states. With the known system, a model-based nonlinear controller is designed; then, to handle uncertainties, the unknown nonlinearities of the wind turbine are estimated by utilizing radial basis function neural networks. The adaptive neural fault tolerant control is designed passively to be robust on model uncertainties, disturbances including wind speed and model noises, and completely unknown actuator faults including generator torque and pitch actuator torque. The Lyapunov direct method is employed to prove that the closed-loop system is uniformly bounded. Simulation studies are performed to verify the effectiveness of the proposed method.

  20. In situ measurements of krypton in xenon gas with a quadrupole mass spectrometer following a cold-trap at a temporarily reduced pumping speed

    International Nuclear Information System (INIS)

    Brown, E; Rosendahl, S; Huhmann, C; Weinheimer, C; Kettling, H

    2013-01-01

    A new method for measuring trace amounts of krypton in xenon using a cold trap with a residual gas analyzer has been developed, which achieves an increased sensitivity by temporarily reducing the pumping speed while expending a minimal amount of xenon. By partially closing a custom built butterfly valve between the measurement chamber and the turbomolecular pump, a sensitivity of 40 ppt has been reached. This method has been tested on an ultra-pure gas sample from Air Liquide with an unknown intrinsic krypton concentration, yielding a krypton concentration of 330±200 ppt.

  1. Intraindividual variability in executive functions but not speed of processing or conflict resolution predicts performance differences in gait speed in older adults.

    Science.gov (United States)

    Holtzer, Roee; Mahoney, Jeannette; Verghese, Joe

    2014-08-01

    The relationship between executive functions (EF) and gait speed is well established. However, with the exception of dual tasking, the key components of EF that predict differences in gait performance have not been determined. Therefore, the current study was designed to determine whether processing speed, conflict resolution, and intraindividual variability in EF predicted variance in gait performance in single- and dual-task conditions. Participants were 234 nondemented older adults (mean age 76.48 years; 55% women) enrolled in a community-based cohort study. Gait speed was assessed using an instrumented walkway during single- and dual-task conditions. The flanker task was used to assess EF. Results from the linear mixed effects model showed that (a) dual-task interference caused a significant dual-task cost in gait speed (estimate = 35.99; 95% CI = 33.19-38.80) and (b) of the cognitive predictors, only intraindividual variability was associated with gait speed (estimate = -.606; 95% CI = -1.11 to -.10). In unadjusted analyses, the three EF measures were related to gait speed in single- and dual-task conditions. However, in fully adjusted linear regression analysis, only intraindividual variability predicted performance differences in gait speed during dual tasking (B = -.901; 95% CI = -1.557 to -.245). Among the three EF measures assessed, intraindividual variability but not speed of processing or conflict resolution predicted performance differences in gait speed. © The Author 2013. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  2. Variable population exposure and distributed travel speeds in least-cost tsunami evacuation modelling

    Science.gov (United States)

    Fraser, Stuart A.; Wood, Nathan J.; Johnston, David A.; Leonard, Graham S.; Greening, Paul D.; Rossetto, Tiziana

    2014-01-01

    Evacuation of the population from a tsunami hazard zone is vital to reduce life-loss due to inundation. Geospatial least-cost distance modelling provides one approach to assessing tsunami evacuation potential. Previous models have generally used two static exposure scenarios and fixed travel speeds to represent population movement. Some analyses have assumed immediate departure or a common evacuation departure time for all exposed population. Here, a method is proposed to incorporate time-variable exposure, distributed travel speeds, and uncertain evacuation departure time into an existing anisotropic least-cost path distance framework. The method is demonstrated for hypothetical local-source tsunami evacuation in Napier City, Hawke's Bay, New Zealand. There is significant diurnal variation in pedestrian evacuation potential at the suburb level, although the total number of people unable to evacuate is stable across all scenarios. Whilst some fixed travel speeds approximate a distributed speed approach, others may overestimate evacuation potential. The impact of evacuation departure time is a significant contributor to total evacuation time. This method improves least-cost modelling of evacuation dynamics for evacuation planning, casualty modelling, and development of emergency response training scenarios. However, it requires detailed exposure data, which may preclude its use in many situations.

  3. Variable Speed Limits: Strategies to Improve Safety and Traffic Parameters for a Bottleneck

    Directory of Open Access Journals (Sweden)

    M. Z. Hasanpour

    2017-04-01

    Full Text Available The primary purpose of the speed limit system is to enforce reasonable and safe speed. To reduce secondary problems such as accidents and queuing, Variable Speed Limits (VSL has been suggested. In this paper VSL is used to better safety and traffic parameters. Traffic parameters including speed, queue length and stopping time have been pondering. For VLS, an optimization decision tree algorithm with the function of microscopic simulation was used. The results in case of sub saturated, saturated and supersaturated at a bottleneck are examined and compared with the Allaby logic tree. The results show that the proposed decision tree shows an improved performance in terms of safety and comfort along the highway. The VSL pilot project is part of the Road Safety Improvement Program included in Iran’s road safety action plan that is in the research process in the BHRC Research Institute, Road and Housing & Urban Development Research that is planned for next 10-year Transportation safety view Plan.

  4. Modeling the Power Variability of Core Speed Scaling on Homogeneous Multicore Systems

    Directory of Open Access Journals (Sweden)

    Zhihui Du

    2017-01-01

    Full Text Available We describe a family of power models that can capture the nonuniform power effects of speed scaling among homogeneous cores on multicore processors. These models depart from traditional ones, which assume that individual cores contribute to power consumption as independent entities. In our approach, we remove this independence assumption and employ statistical variables of core speed (average speed and the dispersion of the core speeds to capture the comprehensive heterogeneous impact of subtle interactions among the underlying hardware. We systematically explore the model family, deriving basic and refined models that give progressively better fits, and analyze them in detail. The proposed methodology provides an easy way to build power models to reflect the realistic workings of current multicore processors more accurately. Moreover, unlike the existing lower-level power models that require knowledge of microarchitectural details of the CPU cores and the last level cache to capture core interdependency, ours are easier to use and scalable to emerging and future multicore architectures with more cores. These attributes make the models particularly useful to system users or algorithm designers who need a quick way to estimate power consumption. We evaluate the family of models on contemporary x86 multicore processors using the SPEC2006 benchmarks. Our best model yields an average predicted error as low as 5%.

  5. A hybrid approach to fault diagnosis of roller bearings under variable speed conditions

    Science.gov (United States)

    Wang, Yanxue; Yang, Lin; Xiang, Jiawei; Yang, Jianwei; He, Shuilong

    2017-12-01

    Rolling element bearings are one of the main elements in rotating machines, whose failure may lead to a fatal breakdown and significant economic losses. Conventional vibration-based diagnostic methods are based on the stationary assumption, thus they are not applicable to the diagnosis of bearings working under varying speeds. This constraint limits the bearing diagnosis to the industrial application significantly. A hybrid approach to fault diagnosis of roller bearings under variable speed conditions is proposed in this work, based on computed order tracking (COT) and variational mode decomposition (VMD)-based time frequency representation (VTFR). COT is utilized to resample the non-stationary vibration signal in the angular domain, while VMD is used to decompose the resampled signal into a number of band-limited intrinsic mode functions (BLIMFs). A VTFR is then constructed based on the estimated instantaneous frequency and instantaneous amplitude of each BLIMF. Moreover, the Gini index and time-frequency kurtosis are both proposed to quantitatively measure the sparsity and concentration measurement of time-frequency representation, respectively. The effectiveness of the VTFR for extracting nonlinear components has been verified by a bat signal. Results of this numerical simulation also show the sparsity and concentration of the VTFR are better than those of short-time Fourier transform, continuous wavelet transform, Hilbert-Huang transform and Wigner-Ville distribution techniques. Several experimental results have further demonstrated that the proposed method can well detect bearing faults under variable speed conditions.

  6. Variable Delay Element For Jitter Control In High Speed Data Links

    Science.gov (United States)

    Livolsi, Robert R.

    2002-06-11

    A circuit and method for decreasing the amount of jitter present at the receiver input of high speed data links which uses a driver circuit for input from a high speed data link which comprises a logic circuit having a first section (1) which provides data latches, a second section (2) which provides a circuit generates a pre-destorted output and for compensating for level dependent jitter having an OR function element and a NOR function element each of which is coupled to two inputs and to a variable delay element as an input which provides a bi-modal delay for pulse width pre-distortion, a third section (3) which provides a muxing circuit, and a forth section (4) for clock distribution in the driver circuit. A fifth section is used for logic testing the driver circuit.

  7. Variable-Speed Power-Turbine for the Large Civil Tilt Rotor

    Science.gov (United States)

    Suchezky, Mark; Cruzen, G. Scott

    2012-01-01

    Turbine design concepts were studied for application to a large civil tiltrotor transport aircraft. The concepts addressed the need for high turbine efficiency across the broad 2:1 turbine operating speed range representative of the notional mission for the aircraft. The study focused on tailoring basic turbine aerodynamic design design parameters to avoid the need for complex, heavy, and expensive variable geometry features. The results of the study showed that good turbine performance can be achieved across the design speed range if the design focuses on tailoring the aerodynamics for good tolerance to large swings in incidence, as opposed to optimizing for best performance at the long range cruise design point. A rig design configuration and program plan are suggested for a dedicated experiment to validate the proposed approach.

  8. Dual stator winding variable speed asynchronous generator: optimal design and experiments

    International Nuclear Information System (INIS)

    Tutelea, L N; Deaconu, S I; Popa, G N

    2015-01-01

    In the present paper is carried out a theoretical and experimental study of dual stator winding squirrel cage asynchronous generator (DSWA) behavior in the presence of saturation regime (non-sinusoidal) due to the variable speed operation. The main aims are the determination of the relations of calculating the equivalent parameters of the machine windings to optimal design using a Matlab code. Issue is limited to three phase range of double stator winding cage-induction generator of small sized powers, the most currently used in the small adjustable speed wind or hydro power plants. The tests were carried out using three-phase asynchronous generator having rated power of 6 [kVA]. (paper)

  9. Variable speed wind turbine control by discrete-time sliding mode approach.

    Science.gov (United States)

    Torchani, Borhen; Sellami, Anis; Garcia, Germain

    2016-05-01

    The aim of this paper is to propose a new design variable speed wind turbine control by discrete-time sliding mode approach. This methodology is designed for linear saturated system. The saturation constraint is reported on inputs vector. To this end, the back stepping design procedure is followed to construct a suitable sliding manifold that guarantees the attainment of a stabilization control objective. It is well known that the mechanisms are investigated in term of the most proposed assumptions to deal with the damping, shaft stiffness and inertia effect of the gear. The objectives are to synthesize robust controllers that maximize the energy extracted from wind, while reducing mechanical loads and rotor speed tracking combined with an electromagnetic torque. Simulation results of the proposed scheme are presented. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

  10. Step-by-step variability of swing phase trajectory area during steady state walking at a range of speeds

    Science.gov (United States)

    Hurt, Christopher P.; Brown, David A.

    2018-01-01

    Background Step kinematic variability has been characterized during gait using spatial and temporal kinematic characteristics. However, people can adopt different trajectory paths both between individuals and even within individuals at different speeds. Single point measures such as minimum toe clearance (MTC) and step length (SL) do not necessarily account for the multiple paths that the foot may take during the swing phase to reach the same foot fall endpoint. The purpose of this study was to test a step-by-step foot trajectory area (SBS-FTA) variability measure that is able to characterize sagittal plane foot trajectories of varying areas, and compare this measure against MTC and SL variability at different speeds. We hypothesize that the SBS-FTA variability would demonstrate increased variability with speed. Second, we hypothesize that SBS-FTA would have a stronger curvilinear fit compared with the CV and SD of SL and MTC. Third, we hypothesize SBS-FTA would be more responsive to change in the foot trajectory at a given speed compared to SL and MTC. Fourth, SBS-FTA variability would not strongly co-vary with SL and MTC variability measures since it represents a different construct related to foot trajectory area variability. Methods We studied 15 nonimpaired individuals during walking at progressively faster speeds. We calculated SL, MTC, and SBS-FTA area. Results SBS-FTA variability increased with speed, had a stronger curvilinear fit compared with the CV and SD of SL and MTC, was more responsive at a given speed, and did not strongly co-vary with SL and MTC variability measures. Conclusion SBS foot trajectory area variability was sensitive to change with faster speeds, captured a relationship that the majority of the other measures did not demonstrate, and did not co-vary strongly with other measures that are also components of the trajectory. PMID:29370202

  11. Hydraulic performance numerical simulation of high specific speed mixed-flow pump based on quasi three-dimensional hydraulic design method

    International Nuclear Information System (INIS)

    Zhang, Y X; Su, M; Hou, H C; Song, P F

    2013-01-01

    This research adopts the quasi three-dimensional hydraulic design method for the impeller of high specific speed mixed-flow pump to achieve the purpose of verifying the hydraulic design method and improving hydraulic performance. Based on the two families of stream surface theory, the direct problem is completed when the meridional flow field of impeller is obtained by employing iterative calculation to settle the continuity and momentum equation of fluid. The inverse problem is completed by using the meridional flow field calculated in the direct problem. After several iterations of the direct and inverse problem, the shape of impeller and flow field information can be obtained finally when the result of iteration satisfies the convergent criteria. Subsequently the internal flow field of the designed pump are simulated by using RANS equations with RNG k-ε two-equation turbulence model. The static pressure and streamline distributions at the symmetrical cross-section, the vector velocity distribution around blades and the reflux phenomenon are analyzed. The numerical results show that the quasi three-dimensional hydraulic design method for high specific speed mixed-flow pump improves the hydraulic performance and reveal main characteristics of the internal flow of mixed-flow pump as well as provide basis for judging the rationality of the hydraulic design, improvement and optimization of hydraulic model

  12. Strategy for the Operation of Cooling Towers with variable Speed Fans

    CERN Document Server

    Iñigo-Golfín, J

    2001-01-01

    Within the SPS Cooling Water Project at CERN aimed at the reduction of water consumption, this primary open cooling loop will be closed and all the primary cooling circuit components will be upgraded to the new required duty and brought to the necessary safety and operability standards. In particular the tower fans will be fitted with variable frequency drives to replace the existing two speed motors. This paper presents a study to optimize the operation of SPS cooling towers taking into account outdoor conditions (wet and dry bulb temperatures) and the entirety of the primary circuit in which they will operate.

  13. Modular Multilevel Converters Based Variable Speed Wind Turbines for Grid Faults

    DEFF Research Database (Denmark)

    Deng, Fujin; Liu, Dong; Wang, Yanbo

    2016-01-01

    in the dc-link of the power converter to improve system performance, but also ensure the grid-side current balancing to increase the generated power of the wind turbine under the unbalanced grid fault, in comparison with the conventional VSWT based on BTB three-level NPC converters. The simulation studies......The modular multilevel converter (MMC) becomes attractive in the medium- and high-power application with high modularity. In this paper, the MMC is proposed to be applied in the variable speed wind turbine (VSWT) based on the full-scale back-to-back (BTB) power converter, where the generator...

  14. Performance comparison of control schemes for variable-speed wind turbines

    Science.gov (United States)

    Bottasso, C. L.; Croce, A.; Savini, B.

    2007-07-01

    We analyze the performance of different control schemes when applied to the regulation problem of a variable-speed representative wind turbine. In particular, we formulate and compare a wind-scheduled PID, a LQR controller and a novel adaptive non-linear model predictive controller, equipped with observers of the tower states and wind. The simulations include gusts and turbulent winds of varying intensity in nominal as well as off-design operating conditions. The experiments highlight the possible advantages of model-based non-linear control strategies.

  15. Performance comparison of control schemes for variable-speed wind turbines

    International Nuclear Information System (INIS)

    Bottasso, C L; Croce, A; Savini, B

    2007-01-01

    We analyze the performance of different control schemes when applied to the regulation problem of a variable-speed representative wind turbine. In particular, we formulate and compare a wind-scheduled PID, a LQR controller and a novel adaptive non-linear model predictive controller, equipped with observers of the tower states and wind. The simulations include gusts and turbulent winds of varying intensity in nominal as well as off-design operating conditions. The experiments highlight the possible advantages of model-based non-linear control strategies

  16. Improving Fault Ride-Through Capability of Variable Speed Wind Turbines in Distribution Networks

    DEFF Research Database (Denmark)

    Mokryani, Geev; Siano, P.; Piccolo, Antonio

    2013-01-01

    In this paper, a fuzzy controller for improving the fault ride-through (FRT) capability of variable speed wind turbines (WTs) equipped with a doubly fed induction generator (DFIG) is presented. DFIGs can be used as reactive power sources to control the voltage at the point of common coupling (PCC......). The controller is designed to compensate for the voltage at the PCC by simultaneously regulating the reactive and active power generated by WTs. The performance of the controller is evaluated in different case studies considering a different number of wind farms in different locations. Simulations carried out...

  17. Technical specifications of variable speed motors for negative pressure control in hot cell area

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seon Duk; Bang, H. S.; Cho, W. K

    2002-01-01

    Hot cells are the facilities for handling the high radioactive materials and various R and D activities are performed using hot cells. Therefore the control of air flow in hot cell area is very important technology and it is started with the variable speed motor(VSM) controlling the air handling system in that area. This report describes various technical aspects of VS motors and will be useful for understanding the practical technologies of VS motors and also for optimization of the negative pressure controls in hot cell area.

  18. A Comparison Study between Two MPPT Control Methods for a Large Variable-Speed Wind Turbine under Different Wind Speed Characteristics

    Directory of Open Access Journals (Sweden)

    Dongran Song

    2017-05-01

    Full Text Available Variable speed wind turbines (VSWTs usually adopt a maximum power point tracking (MPPT method to optimize energy capture performance. Nevertheless, obtained performance offered by different MPPT methods may be affected by the impact of wind turbine (WT’s inertia and wind speed characteristics and it needs to be clarified. In this paper, the tip speed ratio (TSR and optimal torque (OT methods are investigated in terms of their performance under different wind speed characteristics on a 1.5 MW wind turbine model. To this end, the TSR control method based on an effective wind speed estimator and the OT control method are firstly presented. Then, their performance is investigated and compared through simulation test results under different wind speeds using Bladed software. Comparison results show that the TSR control method can capture slightly more wind energy at the cost of high component loads than the other one under all wind conditions. Furthermore, it is found that both control methods present similar trends of power reduction that is relevant to mean wind speed and turbulence intensity. From the obtained results, we demonstrate that, to further improve MPPT capability of large VSWTs, other advanced control methods using wind speed prediction information need to be addressed.

  19. Improvement of the low-speed friction characteristics of a hydraulic piston pump by PVD-coating of TiN

    International Nuclear Information System (INIS)

    Hong, Yeh Sun; Lee, Sang Yul; Kim, Sung Hun; Lim, Hyun Sik

    2006-01-01

    The hydraulic pump of an Electro-hydrostatic Actuator should be able to quickly feed large volume of oil into hydraulic cylinder in order to reduce the response time. On the other hand, it should be also able to precisely dispense small amount of oil through low-speed operation so that the steady state position control error of the actuator can be accurately compensated. Within the scope of axial piston type hydraulic pumps, this paper is focused on the investigation how the surface treatment of their cylinder barrel with TiN plasma coating can contribute to the reduction of the friction and wear rate of valve plate in the low-speed range with mixed lubrication. The results showed that the friction torque of the valve plate mated with a TiN-coated cylinder barrel could be reduced to 22% of that with an uncoated original one when load pressure was 300 bar and rotational speed 100 rpm. It means that the torque efficiency of the test pump was expected to increase more than 1.3% under the same working condition. At the same time, the wear rate of the valve plate could be reduced to 40∼50%

  20. The Performance Test for Reactor Coolant Pump (RCP) adopting Variable Restriction Orifice Type Control Valve

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S.; Bae, B. U.; Cho, Y. J. and others

    2014-05-15

    The design values of the RCPTF are 17.2 MPa, 343 .deg. C, 11.7 m{sup 3}/s, and 13 MW in the maximum pressure, temperature, flow rate, and electrical power, respectively. In the RCPTF, various types of tests can be performed including a hydraulic performance test to acquire a H-Q curve as well seal transient tests, thrust bearing transient test, cost down test, NPSHR verification test, and so on. After a commissioning startup test was successfully perfomed, mechanical structures are improved including a flow stabilizer and variable restriction orifice. Two- branch pipe (Y-branch) was installed to regulate the flow rate in the range of performance tests. In the main pipe, a flow restrictor (RO: Restriction Orifice) for limiting the maximum flow rate was installed. In the branch pipe line, a globe valve and a butterfly valves for regulating the flow rate was located on the each branch line. When the pressure loss of the valve side is smaller than that of the RO side, the flow rate of valve side was increasing and the flow disturbance was occurred in the lower pipe line. Due to flow disturbnace, it is to cause an error when measuring RCP head and flow measurement of the venturi flow meter installed in the lower main pipe line, and thus leading to a decrease in measurement accuracy as a result. To increase the efficiency of the flow control availability of the test facility, the variable restriction orifice (VRO) type flow control valve was designed and manufactured. In the RCPTF in KAERI, the performance tests and various kinds of transient tests of the RCP were successfully performed. In this study, H-Q curve of the pump using the VRO revealed a similar trend to the result from two ROs. The VRO was confirmed to effectively cover the full test range of the flow rate.

  1. UDE-based control of variable-speed wind turbine systems

    Science.gov (United States)

    Ren, Beibei; Wang, Yeqin; Zhong, Qing-Chang

    2017-01-01

    In this paper, the control of a PMSG (permanent magnet synchronous generator)-based variable-speed wind turbine system with a back-to-back converter is considered. The uncertainty and disturbance estimator (UDE)-based control approach is applied to the regulation of the DC-link voltage and the control of the RSC (rotor-side converter) and the GSC (grid-side converter). For the rotor-side controller, the UDE-based vector control is developed for the RSC with PMSG control to facilitate the application of the MPPT (maximum power point tracking) algorithm for the maximum wind energy capture. For the grid-side controller, the UDE-based vector control is developed to control the GSC with the power reference generated by a UDE-based DC-link voltage controller. Compared with the conventional vector control, the UDE-based vector control can achieve reliable current decoupling control with fast response. Moreover, the UDE-based DC-link voltage regulation can achieve stable DC-link voltage under model uncertainties and external disturbances, e.g. wind speed variations. The effectiveness of the proposed UDE-based control approach is demonstrated through extensive simulation studies in the presence of coupled dynamics, model uncertainties and external disturbances under varying wind speeds. The UDE-based control is able to generate more energy, e.g. by 5% for the wind profile tested.

  2. Impact of the vibrations on the environment caused by passages of trains at variable speed

    Directory of Open Access Journals (Sweden)

    Kożuch Barbara

    2016-01-01

    Full Text Available The paper deals with negative environmental impact caused by the passages of different kinds of trains at variable speed. The study is based on the measurement results which took place in Poland in 2013 on the railway line no. 4. The effect of the traction unit – Pendolino (EMU 250 on the vibration climate was analysed. The impact of passages of new trains was compared to currently operated rolling stock. The speed of trains was varying between 40 and 250 km/h. Vibration measurements were conducted by stuff of an accredited Laboratory of Structural Mechanics at Cracow University of Technology (Accreditation No. AB 826. The influence of the indicated vibrations due to passages of the trains on the building in the neighbourhood of the line was investigated. The vibration assessment was done for horizontal components of vibrations according to Polish standard code. Assessment of environmental impact was presented by indicator of perceptibility of vibration through construction (WODB, which refers to the Scales of Dynamic Influences (SDI scales. The limits specified by standards in any of the passages have not been exceeded. The change of speed or rolling stock resulted in a change in the characteristic of the vibration spectrum.

  3. Study and experimental verification of control tuning strategies in a variable speed wind energy conversion system

    Energy Technology Data Exchange (ETDEWEB)

    Zaragoza, Jordi; Pou, Josep; Arias, Antoni [Electronic Engineering Dept., Technical University of Catalonia, Campus Terrassa, C. Colom 1, 08222 Terrassa (Spain); Spiteri, Cyril [Department of Industrial Electrical Power Conversion, University of Malta, Faculty of Engineering, Msida (Malta); Robles, Eider; Ceballos, Salvador [Energy Unit, Robotiker-Tecnalia Technology Corporation, Zamudio, Basque Country (Spain)

    2011-05-15

    This paper analyzes and compares different control tuning strategies for a variable speed wind energy conversion system (WECS) based on a permanent-magnet synchronous generator (PMSG). The aerodynamics of the wind turbine (WT) and a PMSG have been modeled. The control strategy used in this research is composed of three regulators, which may be based on either linear or nonlinear controllers. In this analysis, proportional-integral (PI) linear controllers have been used. Two different tuning strategies are analyzed and compared. The main goal is to enhance the overall performance by achieving a low sensitivity to disturbances and minimal overshoot under variable operating conditions. Finally, the results have been verified by an experimental WECS laboratory prototype. (author)

  4. Objectifying Tactics: Athlete and Race Variability in Elite Short-Track Speed Skating.

    Science.gov (United States)

    Konings, Marco J; Hettinga, Florentina J

    2018-02-01

    To objectively capture and understand tactical considerations in a race, the authors explored whether race-to-race variation of an athlete and the variation of competitors within a race could provide insight into how and when athletes modify their pacing decisions in response to other competitors. Lap times of elite 500-, 1000-, and 1500-m short-track speed-skating competitions from 2011 to 2016 (N = 6965 races) were collected. Log-transformed lap and finishing times were analyzed with mixed linear models. To determine within-athlete race-to-race variability, athlete identity (between-athletes differences) and the residual (within-athlete race-to-race variation) were added as random effects. To determine race variability, race identity (between-races differences) and the residual (within-race variation) were added as random effects. Separate analyses were performed for each event. Within-athlete race-to-race variability of the finishing times increased with prolonged distance of the event (500-m, CV = 1.6%; 1000-m, CV = 2.8%; 1500-m, CV = 4.1%), mainly due to higher within-athlete race-to-race variability in the initial phase of 1000-m (3.3-6.9%) and 1500-m competitions (8.7-12.2%). During these early stages, within-race variability is relatively low in 1000-m (1.1-1.4%) and 1500-m (1.3-2.8%) competitions. The present study demonstrated how analyses of athlete and race variability could provide insight into tactical pacing decisions in sports where finishing position is emphasized over finishing time. The high variability of short-track skaters is a result of the decision to alter initial pacing behavior based on the behavior of other competitors in their race, emphasizing the importance of athlete-environment interactions in the context of pacing.

  5. Control of a Stand-Alone Variable Speed Wind Energy Supply System †

    Directory of Open Access Journals (Sweden)

    Mohamed M. Hamada

    2013-04-01

    Full Text Available This paper presents a simple control strategy for the operation of a variable speed stand-alone wind turbine with a permanent magnet synchronous generator (PMSG. The PMSG is connected to a three phase resistive load through a switch mode rectifier and a voltage source inverter. Control of the generator side converter is used to achieve maximum power extraction from the available wind power. Control of the DC-DC bidirectional buck-boost converter, which is connected between batteries bank and DC-link voltage, is used to maintain the DC-link voltage at a constant value. It is also used to make the batteries bank stores the surplus of wind energy and supplies this energy to the load during a wind power shortage. The load side voltage source inverter uses a relatively complex vector control scheme to control the output load voltage in terms of amplitude and frequency. The control strategy works under wind speed variation as well as with variable load. Extensive simulation results have been performed using MATLAB/SIMULINK.

  6. Assessing intraindividual variability in sustained attention: reliability, relation to speed and accuracy, and practice effects

    Directory of Open Access Journals (Sweden)

    HAGEN C. FLEHMIG

    2007-06-01

    Full Text Available We investigated the psychometric properties of competing measures of sustained attention. 179 subjects were assessed twice within seven day's time with a test designed to measure sustained attention, or concentration, respectively. In addition to traditional performance indices [i.e., speed (MRT and accuracy (E%], we evaluated two intraindividual response time (RT variability measures: standard deviation (SDRT and coefficient of variation (CVRT. For the overall test, both indices were reliable. SDRT showed good to acceptable retest reliability for all subtests. For CVRT, retest reliability coefficients ranged from very good to not satisfactory. While the reversed-word recognition test proved highly reliable, the mental calculation test and the arrows test were not sufficiently reliable. CVRT was only slightly correlated but SDRT was highly correlated with MRT. In contrast to substantial practice gains for MRT, SDRT and E%, only CVRT proved to be stable. In conclusion, CVRT appears to be a potential index for assessing performance variability: it is reliable for the overall test, only moderately correlated with speed, and virtually not affected by practice. However, before applying CVRT in practical assessment settings, additional research is required to elucidate the impact of task-specific factors on the reliability of this performance measure.

  7. Control and Health Monitoring of Variable Speed Wind Power Generation Systems; Period of Performance: 10 July 1997 - 10 July 2000

    Energy Technology Data Exchange (ETDEWEB)

    Song, Y. D.; Bikdash, M.; Schulz, M. J.

    2001-09-01

    This document reports accomplishments on variable speed control, furling analysis, and health monitoring of wind turbines. There are three parts, prepared by Song, Bikdash, and Schulz, respectively. The first part discusses variable-speed control of wind turbines, exploring a memory-based method for wind speed prediction and wind turbine control. The second part addresses the yaw dynamics of wind turbines, including modeling, analysis, and control. The third part of the report discusses new analytical techniques that were developed and tested to detect initial damage to prevent failures of wind turbine rotor blades.

  8. Pumping behavior of sputter ion pumps

    International Nuclear Information System (INIS)

    Chou, T.S.; McCafferty, D.

    The ultrahigh vacuum requirements of ISABELLE is obtained by distributed pumping stations. Each pumping station consists of 1000 l/s titanium sublimation pump for active gases (N 2 , H 2 , O 2 , CO, etc.), and a 20 l/s sputter ion pump for inert gases (methane, noble gases like He, etc.). The combination of the alarming production rate of methane from titanium sublimation pumps (TSP) and the decreasing pumping speed of sputter ion pumps (SIP) in the ultrahigh vacuum region (UHV) leads us to investigate this problem. In this paper, we first describe the essential physics and chemistry of the SIP in a very clean condition, followed by a discussion of our measuring techniques. Finally measured methane, argon and helium pumping speeds are presented for three different ion pumps in the range of 10 -6 to 10 -11 Torr. The virtues of the best pump are also discussed

  9. Comprehensive Modeling and Analysis of Rotorcraft Variable Speed Propulsion System With Coupled Engine/Transmission/Rotor Dynamics

    Science.gov (United States)

    DeSmidt, Hans A.; Smith, Edward C.; Bill, Robert C.; Wang, Kon-Well

    2013-01-01

    This project develops comprehensive modeling and simulation tools for analysis of variable rotor speed helicopter propulsion system dynamics. The Comprehensive Variable-Speed Rotorcraft Propulsion Modeling (CVSRPM) tool developed in this research is used to investigate coupled rotor/engine/fuel control/gearbox/shaft/clutch/flight control system dynamic interactions for several variable rotor speed mission scenarios. In this investigation, a prototypical two-speed Dual-Clutch Transmission (DCT) is proposed and designed to achieve 50 percent rotor speed variation. The comprehensive modeling tool developed in this study is utilized to analyze the two-speed shift response of both a conventional single rotor helicopter and a tiltrotor drive system. In the tiltrotor system, both a Parallel Shift Control (PSC) strategy and a Sequential Shift Control (SSC) strategy for constant and variable forward speed mission profiles are analyzed. Under the PSC strategy, selecting clutch shift-rate results in a design tradeoff between transient engine surge margins and clutch frictional power dissipation. In the case of SSC, clutch power dissipation is drastically reduced in exchange for the necessity to disengage one engine at a time which requires a multi-DCT drive system topology. In addition to comprehensive simulations, several sections are dedicated to detailed analysis of driveline subsystem components under variable speed operation. In particular an aeroelastic simulation of a stiff in-plane rotor using nonlinear quasi-steady blade element theory was conducted to investigate variable speed rotor dynamics. It was found that 2/rev and 4/rev flap and lag vibrations were significant during resonance crossings with 4/rev lagwise loads being directly transferred into drive-system torque disturbances. To capture the clutch engagement dynamics, a nonlinear stick-slip clutch torque model is developed. Also, a transient gas-turbine engine model based on first principles mean

  10. Torque control of synchronous and induction generators for variable speed operation of wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, Ola; Ulen, E. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Electric Power Engineering

    1996-12-01

    The aim of this paper is to investigate variable speed electrical systems. Synchronous generators with diode rectifiers and line-commutated thyristor converters are compared with induction generators with force commutated transistor converters and scalar control. The system characteristics are examined regarding possible speed of response (bandwidth) of the torque control, including the sensitivity to disturbances for the drive train and also the possibility to get damping of the drive train resonance. Analyses, simulations and laboratory tests with a 40 kW machine set-up have been performed. The investigation shows that the system with synchronous generator is well suited for wind power applications. A rapid standard DC-current regulator is included in the torque control and can be used for damping of the resonance. The torque control has a bandwidth up to about 3 Hz and the DC-voltage controller up to about 1 Hz. The system with induction generator with scalar control (no transformations) is more difficult to control. A linear approach is only possible up to about 1.5 Hz. In this region it turns out that the behaviour can be visualized as an added inertia on the generator side that can be rather big. 4 refs, 9 figs

  11. Transient and dynamic control of a variable speed wind turbine with synchronous generator

    Energy Technology Data Exchange (ETDEWEB)

    Jauch, Clemens [Riso National Laboratory, Wind Energy Department, PO Box 49, DK 4000 Roskilde, (Denmark)

    2007-02-14

    In this article, a controller for dynamic and transient control of a variable speed wind turbine with a full-scale converter-connected high-speed synchronous generator is presented. First, the phenomenon of drive train oscillations in wind turbines with full-scale converter-connected generators is discussed. Based on this discussion, a controller is presented that dampens these oscillations without impacting on the power that the wind turbine injects into the grid. Since wind turbines are increasingly demanded to take over power system stabilizing and control tasks, the presented wind turbine design is further enhanced to support the grid in transient grid events. A controller is designed that allows the wind turbine to ride through transient grid faults. Since such faults often cause power system oscillations, another controller is added that enables the turbine to participate in the damping of such oscillations. It is concluded that the controllers presented keep the wind turbine stable under any operating conditions, and that they are capable of adding substantial damping to the power system. (Author).

  12. Variable speed limit strategies analysis with link transmission model on urban expressway

    Science.gov (United States)

    Li, Shubin; Cao, Danni

    2018-02-01

    The variable speed limit (VSL) is a kind of active traffic management method. Most of the strategies are used in the expressway traffic flow control in order to ensure traffic safety. However, the urban expressway system is the main artery, carrying most traffic pressure. It has similar traffic characteristics with the expressways between cities. In this paper, the improved link transmission model (LTM) combined with VSL strategies is proposed, based on the urban expressway network. The model can simulate the movement of the vehicles and the shock wave, and well balance the relationship between the amount of calculation and accuracy. Furthermore, the optimal VSL strategy can be proposed based on the simulation method. It can provide management strategies for managers. Finally, a simple example is given to illustrate the model and method. The selected indexes are the average density, the average speed and the average flow on the traffic network in the simulation. The simulation results show that the proposed model and method are feasible. The VSL strategy can effectively alleviate traffic congestion in some cases, and greatly promote the efficiency of the transportation system.

  13. Modeling and control of PMSG-based variable-speed wind turbine

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hong-Woo; Ko, Hee-Sang [Wind Energy Research Center, Korea Institute of Energy Research, Yuseong-gu Jang-Dong 71-2,305-343 Daejeon (Korea); Kim, Sung-Soo [Chungbuk National University (Korea)

    2010-01-15

    This paper presents a control scheme of a variable-speed wind turbine with a permanent-magnetic synchronous generator (PMSG) and full-scale back-to-back voltage source converter. A comprehensive dynamical model of the PMSG wind turbine and its control scheme is presented. The control scheme comprises both the wind-turbine control itself and the power-converter control. In addition, since the PMSG wind turbine is able to support actively the grid due to its capability to control independently active and reactive power production to the imposed set-values with taking into account its operating state and limits, this paper presents the supervisory reactive power control scheme in order to regulate/contribute the voltage at a remote location. The ability of the control scheme is assessed and discussed by means of simulations, based on a candidate site of the offshore wind farm in Jeju, Korea. (author)

  14. Modeling and Operational Testing of an Isolated Variable Speed PMSG Wind Turbine with Battery Energy Storage

    Directory of Open Access Journals (Sweden)

    BAROTE, L.

    2012-05-01

    Full Text Available This paper presents the modeling and operational testing of an isolated permanent magnet synchronous generator (PMSG, driven by a small wind turbine with a battery energy storage system during wind speed and load variations. The whole system is initially modeled, including the PMSG, the boost converter and the storage system. The required power for the connected loads can be effectively delivered and supplied by the proposed wind turbine and energy storage systems, subject to an appropriate control method. Energy storage devices are required for power balance and power quality in stand alone wind energy systems. The main purpose is to supply 230 V / 50 Hz domestic appliances through a single-phase inverter. The experimental waveforms, compared to the simulation results, show a good prediction of the electrical variable parameters. Furthermore, it can be seen that the results validate the stability of the supply.

  15. Principles of a simulation model for a variable-speed pitch-regulated wind turbine

    Energy Technology Data Exchange (ETDEWEB)

    Camblong, H.; Vidal, M.R.; Puiggali, J.R.

    2004-07-01

    This paper considers the basic principles for establishing a simulation- model of a variable speed, pitch regulated, wind turbine. This model is used to test various control algorithms designed with the aim of maximising energetic yield and robustness and minimising flicker emission and dynamic drive train loads. One of the most complex elements of such a system is the interaction between wind and turbine. First, a detailed and didactic analysis of this interaction is given. This is used to understand some complicated phenomena, and to help design a simpler and more efficient (in terms of processing time) mathematical model. Additional submodels are given for the mechanical coupling, the pitch system and the electrical power system, before the entire model is validated by comparison with filed measurements on a 180 kW turbine. The complete simulation model is flexible, efficient and allows easy evaluation of different control algorithms. (author)

  16. Variable speed limit strategies analysis with mesoscopic traffic flow model based on complex networks

    Science.gov (United States)

    Li, Shu-Bin; Cao, Dan-Ni; Dang, Wen-Xiu; Zhang, Lin

    As a new cross-discipline, the complexity science has penetrated into every field of economy and society. With the arrival of big data, the research of the complexity science has reached its summit again. In recent years, it offers a new perspective for traffic control by using complex networks theory. The interaction course of various kinds of information in traffic system forms a huge complex system. A new mesoscopic traffic flow model is improved with variable speed limit (VSL), and the simulation process is designed, which is based on the complex networks theory combined with the proposed model. This paper studies effect of VSL on the dynamic traffic flow, and then analyzes the optimal control strategy of VSL in different network topologies. The conclusion of this research is meaningful to put forward some reasonable transportation plan and develop effective traffic management and control measures to help the department of traffic management.

  17. Variable speed DFIG wind energy system for power generation and harmonic current mitigation

    Energy Technology Data Exchange (ETDEWEB)

    Gaillard, A.; Saadate, S. [Groupe de Recherche en Electrotechnique et Electronique de Nancy, Nancy Universite - Universite Henri Poincare Nancy 1, BP239, 54506 Vandoeuvre les Nancy Cedex (France); Poure, P. [Laboratoire d' Instrumentation Electronique de Nancy, Nancy Universite - Universite Henri Poincare Nancy 1, BP239, 54506 Vandoeuvre les Nancy Cedex (France); Machmoum, M. [IREENA, 37 Boulevard de l' Universite, BP 406, 44602 Saint-Nazaire Cedex (France)

    2009-06-15

    This paper presents a novel approach for simultaneous power generation and harmonic current mitigation using variable speed WECS with DFIG. A new control strategy is proposed to upgrade the DFIG control to achieve simultaneously a green active and reactive power source with active filtering capability. To ensure high filtering performance, we studied an improved harmonic isolator in the time-domain, based on a new high selectivity filter developed in our laboratory. We examined two solutions for harmonic current mitigation: first, by compensating the whole harmonic component of the grid currents or second, by selective isolation of the predominant harmonic currents to ensure active filtering of the 5th and 7th harmonics. Simulation results for a 3 MW WECS with DFIG confirm the effectiveness and the performance of the two proposed approaches. (author)

  18. An empirical model for independent control of variable speed refrigeration system

    International Nuclear Information System (INIS)

    Li Hua; Jeong, Seok-Kwon; Yoon, Jung-In; You, Sam-Sang

    2008-01-01

    This paper deals with an empirical dynamic model for decoupling control of the variable speed refrigeration system (VSRS). To cope with inherent complexity and nonlinearity in system dynamics, the model parameters are first obtained based on experimental data. In the study, the dynamic characteristics of indoor temperature and superheat are assumed to be first-order model with time delay. While the compressor frequency and opening angle of electronic expansion valve are varying, the indoor temperature and the superheat exhibit interfering characteristics each other in the VSRS. Thus, each decoupling model has been proposed to eliminate such interference. Finally, the experiment and simulation results indicate that the proposed model offers more tractable means for describing the actual VSRS comparing to other models currently available

  19. Examining Impulse-Variability Theory and the Speed-Accuracy Trade-Off in Children's Overarm Throwing Performance.

    Science.gov (United States)

    Molina, Sergio L; Stodden, David F

    2018-04-01

    This study examined variability in throwing speed and spatial error to test the prediction of an inverted-U function (i.e., impulse-variability [IV] theory) and the speed-accuracy trade-off. Forty-five 9- to 11-year-old children were instructed to throw at a specified percentage of maximum speed (45%, 65%, 85%, and 100%) and hit the wall target. Results indicated no statistically significant differences in variable error across the target conditions (p = .72), failing to support the inverted-U hypothesis. Spatial accuracy results indicated no statistically significant differences with mean radial error (p = .18), centroid radial error (p = .13), and bivariate variable error (p = .08) also failing to support the speed-accuracy trade-off in overarm throwing. As neither throwing performance variability nor accuracy changed across percentages of maximum speed in this sample of children as well as in a previous adult sample, current policy and practices of practitioners may need to be reevaluated.

  20. Second-order Sliding Mode Control of DFIG Based Variable Speed Wind Turbine for Maximum Power Point Tracking

    Institute of Scientific and Technical Information of China (English)

    Xiangjie Liu; Chengcheng Wang; Yaozhen Han

    2017-01-01

    This paper proposes a super-twisting second order sliding mode control scheme to maximize the wind energy capture of a doubly fed induction generator based variable speed wind turbine (VSWT) system, and minimize the reactive power simultaneously. Two second order sliding mode controllers are designed to achieve the control objectives, reduce mechanical stress and improve control accuracy. By regulating the generator rotor voltage, one controller makes the wind turbine rotor speed track the optimal speed, which can maximize power generation. The other maintains the rotor current at rated value to minimize the reactive power. A quadratic form Lyapunov function is adopted to determine the range of controller parameters and guarantee the finite time stability. Simulation results on a 1.5 MW doubly fed induction generator (DFIG)-based variable speed wind turbine demonstrate the validity of the proposed control strategy.

  1. Power Consumption Optimization for Multiple Parallel Centrifugal Pumps

    DEFF Research Database (Denmark)

    Jepsen, Kasper Lund; Hansen, Leif; Mai, Christian

    2017-01-01

    Large amounts of energy is being used in a wide range of applications to transport liquid. This paper proposes a generic solution for minimizing power consumption of a generic pumping station equipped with identical variable speed pumps. The proposed solution consists of two sequential steps; fir...

  2. Bearing Fault Diagnosis under Variable Speed Using Convolutional Neural Networks and the Stochastic Diagonal Levenberg-Marquardt Algorithm

    Directory of Open Access Journals (Sweden)

    Viet Tra

    2017-12-01

    Full Text Available This paper presents a novel method for diagnosing incipient bearing defects under variable operating speeds using convolutional neural networks (CNNs trained via the stochastic diagonal Levenberg-Marquardt (S-DLM algorithm. The CNNs utilize the spectral energy maps (SEMs of the acoustic emission (AE signals as inputs and automatically learn the optimal features, which yield the best discriminative models for diagnosing incipient bearing defects under variable operating speeds. The SEMs are two-dimensional maps that show the distribution of energy across different bands of the AE spectrum. It is hypothesized that the variation of a bearing’s speed would not alter the overall shape of the AE spectrum rather, it may only scale and translate it. Thus, at different speeds, the same defect would yield SEMs that are scaled and shifted versions of each other. This hypothesis is confirmed by the experimental results, where CNNs trained using the S-DLM algorithm yield significantly better diagnostic performance under variable operating speeds compared to existing methods. In this work, the performance of different training algorithms is also evaluated to select the best training algorithm for the CNNs. The proposed method is used to diagnose both single and compound defects at six different operating speeds.

  3. Exploiting maximum energy from variable speed wind power generation systems by using an adaptive Takagi-Sugeno-Kang fuzzy model

    International Nuclear Information System (INIS)

    Galdi, V.; Piccolo, A.; Siano, P.

    2009-01-01

    Nowadays, incentives and financing options for developing renewable energy facilities and the new development in variable speed wind technology make wind energy a competitive source if compared with conventional generation ones. In order to improve the effectiveness of variable speed wind systems, adaptive control systems able to cope with time variances of the system under control are necessary. On these basis, a data driven designing methodology for TSK fuzzy models design is presented in this paper. The methodology, on the basis of given input-output numerical data, generates the 'best' TSK fuzzy model able to estimate with high accuracy the maximum extractable power from a variable speed wind turbine. The design methodology is based on fuzzy clustering methods for partitioning the input-output space combined with genetic algorithms (GA), and recursive least-squares (LS) optimization methods for model parameter adaptation

  4. Monitoring for shaft cracks on reactor recirculation pumps

    International Nuclear Information System (INIS)

    Kowal, M.G.; O'Brien, J.T. Jr.

    1989-01-01

    The article discusses the vibration characteristics associated with a boiling water reactor (BWR) recirculation pump. It also describes the application of diagnostic techniques and shaft crack theory to an on-line diagnostic monitoring system for reactor recirculation pumps employed at Philadelphia Electric Company's Peach Bottom Atomic Power Station. Specific emphasis is placed on the unique monitoring techniques associated with these variable speed vertical pumps

  5. Smoothing Control of Wind Farm Output by Using Kinetic Energy of Variable Speed Wind Power Generators

    Science.gov (United States)

    Sato, Daiki; Saitoh, Hiroumi

    This paper proposes a new control method for reducing fluctuation of power system frequency through smoothing active power output of wind farm. The proposal is based on the modulation of rotaional kinetic energy of variable speed wind power generators through power converters between permanent magnet synchronous generators (PMSG) and transmission lines. In this paper, the proposed control is called Fluctuation Absorption by Flywheel Characteristics control (FAFC). The FAFC can be easily implemented by adding wind farm output signal to Maximum Power Point Tracking control signal through a feedback control loop. In order to verify the effectiveness of the FAFC control, a simulation study was carried out. In the study, it was assumed that the wind farm consisting of PMSG type wind power generator and induction machine type wind power generaotors is connected with a power sysem. The results of the study show that the FAFC control is a useful method for reducing the impacts of wind farm output fluctuation on system frequency without additional devices such as secondary battery.

  6. Sliding mode direct power control of RSC for DFIGs driven by variable speed wind turbines

    Directory of Open Access Journals (Sweden)

    E.G. Shehata

    2015-12-01

    Full Text Available In spite of its several advantages, a classic direct power control (DPC of doubly fed induction generators (DFIGs driven by variable speed wind turbines has some drawbacks. In this paper, a simple and robust total sliding mode controller (TSMC is designed to improve the classical DPC performance without complicating the overall scheme. The TSMC is designed to regulate the DFIG stator active and reactive powers. Two integral switching functions are selected for describing the switching surfaces of the active and reactive powers. Reaching phase stability problem of the classical sliding mode controller is avoided in the proposed TSMC. Neither current control loops nor accurate values of machine parameters are required in the proposed scheme. In addition, axes transformation of the stator voltage and current are eliminated. The grid side converter is controlled based on DPC principle to regulate both DC-link voltage and total reactive power. The feasibility of the proposed DPC scheme is validated through simulation studies on a 1.5 MW wind power generation system. The performance of the proposed and conventional DPC schemes is compared under different operating conditions.

  7. Voltage control of a variable speed wind turbine connected to an isolated load: Experimental study

    International Nuclear Information System (INIS)

    Masmoudi, Abdelkarim; Krichen, Lotfi; Ouali, Abderrazak

    2012-01-01

    Highlights: ► We develop an experimental test bench of a wind energy conversion system. ► A DC motor is emulating a variable speed wind turbine using a DS1104 card. ► The production unit is supplying a three-phase load. ► A voltage control is established in order to regulate the DC bus voltage and the line-to-line voltages. - Abstract: This study is interested in the development of an experimental test bench of an autonomous wind energy conversion system (WECS) based on a permanent magnet synchronous generator (PMSG). After the description of the test bench, the elements constituting the WECS are presented. Then, a real time model implemented under a digital signal processor (DSP) system is established. The first objective of this work is to validate the functionality of the test bench leading to experiment some principles developed in theory. The second objective is to control the load connection voltages and the DC bus voltage. For the first control, two resonant controllers are used and for the second one, a dump load, connected to the DC bus, offers the possibility to maintain a balance between production and consumption in spite of wind fluctuations and load variations. The experimental results show the effectiveness of the test bench trying out in real time the behavior of a WECS supplying an isolated load.

  8. Perceived Cost and Intrinsic Motor Variability Modulate the Speed-Accuracy Trade-Off.

    Directory of Open Access Journals (Sweden)

    Matteo Bertucco

    Full Text Available Fitts' Law describes the speed-accuracy trade-off of human movements, and it is an elegant strategy that compensates for random and uncontrollable noise in the motor system. The control strategy during targeted movements may also take into account the rewards or costs of any outcomes that may occur. The aim of this study was to test the hypothesis that movement time in Fitts' Law emerges not only from the accuracy constraints of the task, but also depends on the perceived cost of error for missing the targets. Subjects were asked to touch targets on an iPad® screen with different costs for missed targets. We manipulated the probability of error by comparing children with dystonia (who are characterized by increased intrinsic motor variability to typically developing children. The results show a strong effect of the cost of error on the Fitts' Law relationship characterized by an increase in movement time as cost increased. In addition, we observed a greater sensitivity to increased cost for children with dystonia, and this behavior appears to minimize the average cost. The findings support a proposed mathematical model that explains how movement time in a Fitts-like task is related to perceived risk.

  9. GeneratorSE: A Sizing Tool for Variable-Speed Wind Turbine Generators

    Energy Technology Data Exchange (ETDEWEB)

    Sethuraman, Latha [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Dykes, Katherine L [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-09-22

    This report documents a set of analytical models employed by the optimization algorithms within the GeneratorSE framework. The initial values and boundary conditions employed for the generation of the various designs and initial estimates for basic design dimensions, masses, and efficiency for the four different models of generators are presented and compared with empirical data collected from previous studies and some existing commercial turbines. These models include designs applicable for variable-speed, high-torque application featuring direct-drive synchronous generators and low-torque application featuring induction generators. In all of the four models presented, the main focus of optimization is electromagnetic design with the exception of permanent-magnet and wire-wound synchronous generators, wherein the structural design is also optimized. Thermal design is accommodated in GeneratorSE as a secondary attribute by limiting the winding current densities to acceptable limits. A preliminary validation of electromagnetic design was carried out by comparing the optimized magnetic loading against those predicted by numerical simulation in FEMM4.2, a finite-element software for analyzing electromagnetic and thermal physics problems for electrical machines. For direct-drive synchronous generators, the analytical models for the structural design are validated by static structural analysis in ANSYS.

  10. On the modelling and partial-load control of variable-speed wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Novak, P [Chalmers Univ. of Technology, Goeteborg (Sweden). School of Electrical and Computer Engineering

    1996-12-31

    The focus of this thesis is on modelling and variable-speed control of wind turbines. A physical model structure including the fundamental drive-train mode is derived and validated by system-identification experiments on a full-scale wind turbine. The resulting, parametrized model has been used as a basis for an evaluation of controllers for partial-load operation, validated by non-linear simulations. This evaluation, including several controller concepts, verifies that a sophisticated controller becomes necessary, when stretching the limits in power-loss minimization. This control strategy also demands the sampling frequency to be pushed to a high level. As a consequence, the angular-position measurements become time correlated and, in the limit, periodic. It is shown in the thesis how the resulting, operating-point-dependent effects on the measurement errors influence the estimation quality, using a stationary Kalman filter as an example. A gain-scheduling estimation approach is shown to improve the performance. 39 refs, 63 figs, 2 tabs

  11. Comparative studies on control systems for a two-blade variable-speed wind turbine with a speed exclusion zone

    International Nuclear Information System (INIS)

    Yang, Jian; Song, Dongran; Dong, Mi; Chen, Sifan; Zou, Libing; Guerrero, Josep M.

    2016-01-01

    To avoid the coincidence between the tower nature frequency and rotational excitation frequency, a SEZ (speed exclusion zone) must be built for a two-blade wind turbine with a full rated converter. According to the literature, two methods of SEZ-crossing could be adopted. However, none of them have been studied in industrial applications, and their performance remains unclear. Moreover, strategies on power regulation operation are not covered. To fully investigate them, this paper develops two control systems for a two-blade WT (wind turbines) with a SEZ. Because control systems play vital roles in determining the performance of the WT, this paper focuses on comparative studies on their operation strategies and performance. In these strategies, optimal designs are introduced to improve existing SEZ algorithms. Moreover, to perform power regulation outside the SEZ, two operation modes are divided in the proposed down power regulation solutions. The developed control systems’ performance is confirmed by simulations and field tests. Two control systems present similar capabilities of power production and SEZ-bridging. Nevertheless, at the cost of significantly increased tower loads, one captures 1% more energy than the other. Overall consideration must be made for the control system selection for a WT with a SEZ. - Highlights: • Two control systems are developed for a two-blade WT with a SEZ. • Three strategies, that is, power optimization, power limitation and power regulation, are discussed. • Optimal designs are adopted to enhance the WT's SEZ-bridging capability. • Simple but effective power regulation solutions are presented. • Simulation and field test results show that Control System 2 produces 1% more energy at the cost of increased tower loads.

  12. Numerical Investigation of Pressure Fluctuation Characteristics in a Centrifugal Pump with Variable Axial Clearance

    Directory of Open Access Journals (Sweden)

    Lei Cao

    2016-01-01

    Full Text Available Clearance flows in the sidewall gaps of centrifugal pumps are unsteady as well as main flows in the volute casing and impeller, which may cause vibration and noise, and the corresponding pressure fluctuations are related to the axial clearance size. In this paper, unsteady numerical simulations were conducted to predict the unsteady flows within the entire flow passage of a centrifugal pump operating in the design condition. Pressure fluctuation characteristics in the volute casing, impeller, and sidewall gaps were investigated with three axial clearance sizes. Results show that an axial clearance variation affects the pressure fluctuation characteristics in each flow domain by different degree. The greatest pressure fluctuation occurs at the blade pressure surface and is almost not influenced by the axial clearance variation which has a certainly effect on the pressure fluctuation characteristics around the tongue. The maximum pressure fluctuation amplitude in the sidewall gaps is larger than that in the volute casing, and different spectrum characteristics show up in the three models due to the interaction between the clearance flow and the main flow as well as the rotor-stator interaction. Therefore, clearance flow should be taken into consideration in the hydraulic design of centrifugal pumps.

  13. State-Space Modeling and Performance Analysis of Variable-Speed Wind Turbine Based on a Model Predictive Control Approach

    Directory of Open Access Journals (Sweden)

    H. Bassi

    2017-04-01

    Full Text Available Advancements in wind energy technologies have led wind turbines from fixed speed to variable speed operation. This paper introduces an innovative version of a variable-speed wind turbine based on a model predictive control (MPC approach. The proposed approach provides maximum power point tracking (MPPT, whose main objective is to capture the maximum wind energy in spite of the variable nature of the wind’s speed. The proposed MPC approach also reduces the constraints of the two main functional parts of the wind turbine: the full load and partial load segments. The pitch angle for full load and the rotating force for the partial load have been fixed concurrently in order to balance power generation as well as to reduce the operations of the pitch angle. A mathematical analysis of the proposed system using state-space approach is introduced. The simulation results using MATLAB/SIMULINK show that the performance of the wind turbine with the MPC approach is improved compared to the traditional PID controller in both low and high wind speeds.

  14. Correlation between sea surface temperature and wind speed in Greenland Sea and their relationships with NAO variability

    Directory of Open Access Journals (Sweden)

    Bo Qu

    2012-09-01

    Full Text Available The North Atlantic Oscillation (NAO is one of the major causes of many recent changes in the Arctic Ocean. Generally, it is related to wind speed, sea surface temperature (SST, and sea ice cover. In this study, we analyzed the distributions of and correlations between SST, wind speed, NAO, and sea ice cover from 2003 to 2009 in the Greenland Sea at 10°W to 10°E, 65°N to 80°N. SST reached its peak in July, while wind speed reached its minimum in July. Seasonal variability of SST and wind speed was different for different regions. SST and wind speed mainly had negative correlations. Detailed correlation research was focused on the 75°N to 80°N band. Regression analysis shows that in this band, the variation of SST lagged three months behind that of wind speed. Ice cover and NAO had a positive correlation, and the correlation coefficient between ice cover and NAO in the year 2007 was 0.61. SST and NAO also had a positive correlation, and SST influenced NAO one month in advance. The correlation coefficients between SST and NAO reached 0.944 for the year 2005, 0.7 for the year 2008, and 0.74 for the year 2009 after shifting SST one month later. NAO also had a positive correlation with wind speed, and it also influenced wind speed one month in advance. The correlation coefficients between NAO and wind speed reached 0.783, 0.813, and 0.818 for the years 2004, 2005, and 2008, respectively, after shifting wind speed one month earlier.

  15. Control design for a pitch-regulated, variable speed wind turbine

    DEFF Research Database (Denmark)

    Hansen, M.H.; Hansen, Anca Daniela; Larsen, Torben J.

    2005-01-01

    The three different controller designs presented herein are similar and all based on PI-regulation of rotor speed and power through the collective blade pitch angle and generator moment. The aeroelastic and electrical modelling used for the time-domainanalysis of these controllers are however...... different, which makes a directly quantitative comparison difficult. But there are some observations of similar behaviours should be mentioned: • Very similar step responses in rotor speed, pitch angle, and powerare seen for simulations with steps in wind speed. • All controllers show a peak in power...... for wind speed step-up over rated wind speed, which can be almost removed by changing the parameters of the frequency converter. • Responses of rotor speed, pitchangle, and power for different simulations with turbulent inflow are similar for all three controllers. Again, there seems to be an advantage...

  16. Resonant Vibrations Resulting from the Re-Engineering of a Constant-Speed 2-Bladed Turbine to a Variable-Speed 3-Bladed Turbine

    Energy Technology Data Exchange (ETDEWEB)

    Fleming, P.; Wright, A. D.; Finersh, L. J.

    2010-12-01

    The CART3 (Controls Advanced Research Turbine, 3-bladed) at the National Wind Technology Center has recently been converted from a 2-bladed constant speed machine to a 3-bladed variable speed machine designed specically for controls research. The purpose of this conversion was to develop an advanced controls field-testing platform which has the more typical 3-bladed configuration. A result of this conversion was the emergence of several resonant vibrations, some of which initially prevented operation of the turbine until they could be explained and resolved. In this paper, the investigations into these vibrations are presented as 'lessons-learned'. Additionally, a frequency-domain technique called waterfall plotting is discussed and its usefulness in this research is illustrated.

  17. Constant versus variable response signal delays in speed accuracy trade-offs : Effects of advance preparation for processing time

    OpenAIRE

    Miller, Jeff; Sproesser, Gudrun; Ulrich, Rolf

    2008-01-01

    In two experiments, we used response signals (RSs) to control processing time and trace out speed accuracy trade-off (SAT) functions in a difficult perceptual discrimination task. Each experiment compared performance in blocks of trials with constant and, hence, temporally predictable RS lags against performance in blocks with variable, unpredictable RS lags. In both experiments, essentially equivalent SAT functions were observed with constant and variable RS lags. We conclude that there is l...

  18. Intelligent approach to maximum power point tracking control strategy for variable-speed wind turbine generation system

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Whei-Min; Hong, Chih-Ming [Department of Electrical Engineering, National Sun Yat-Sen University, Kaohsiung 80424 (China)

    2010-06-15

    To achieve maximum power point tracking (MPPT) for wind power generation systems, the rotational speed of wind turbines should be adjusted in real time according to wind speed. In this paper, a Wilcoxon radial basis function network (WRBFN) with hill-climb searching (HCS) MPPT strategy is proposed for a permanent magnet synchronous generator (PMSG) with a variable-speed wind turbine. A high-performance online training WRBFN using a back-propagation learning algorithm with modified particle swarm optimization (MPSO) regulating controller is designed for a PMSG. The MPSO is adopted in this study to adapt to the learning rates in the back-propagation process of the WRBFN to improve the learning capability. The MPPT strategy locates the system operation points along the maximum power curves based on the dc-link voltage of the inverter, thus avoiding the generator speed detection. (author)

  19. [Hypothesis on the equilibrium point and variability of amplitude, speed and time of single-joint movement].

    Science.gov (United States)

    Latash, M; Gottleib, G

    1990-01-01

    Problems of single-joint movement variability are analysed in the framework of the equilibrium-point hypothesis (the lambda-model). Control of the movements is described with three parameters related to movement amplitude speed, and time. Three strategies emerge from this description. Only one of them is likely to lead to a Fitts' type speed-accuracy trade-off. Experiments were performed to test one of the predictions of the model. Subjects performed identical sets of single-joint fast movements with open or closed eyes and some-what different instructions. Movements performed with closed eyes were characterized with higher peak speeds and unchanged variability in seeming violation of the Fitt's law and in a good correspondence to the model.

  20. Variability Extraction and Synthesis via Multi-Resolution Analysis using Distribution Transformer High-Speed Power Data

    Energy Technology Data Exchange (ETDEWEB)

    Chamana, Manohar [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Mather, Barry A [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-10-19

    A library of load variability classes is created to produce scalable synthetic data sets using historical high-speed raw data. These data are collected from distribution monitoring units connected at the secondary side of a distribution transformer. Because of the irregular patterns and large volume of historical high-speed data sets, the utilization of current load characterization and modeling techniques are challenging. Multi-resolution analysis techniques are applied to extract the necessary components and eliminate the unnecessary components from the historical high-speed raw data to create the library of classes, which are then utilized to create new synthetic load data sets. A validation is performed to ensure that the synthesized data sets contain the same variability characteristics as the training data sets. The synthesized data sets are intended to be utilized in quasi-static time-series studies for distribution system planning studies on a granular scale, such as detailed PV interconnection studies.

  1. Influence of travel speed on spray deposition uniformity from an air-assisted variable-rate sprayer

    Science.gov (United States)

    A newly developed LiDAR-guided air-assisted variable-rate sprayer for nursery and orchard applications was tested at various travel speeds to compare its spray deposition and coverage uniformity with constant-rate applications. Spray samplers, including nylon screens and water-sensitive papers (WSP)...

  2. An improved synchronous reference frame phase-locked loop for stand-alone variable speed constant frequency power generation systems

    DEFF Research Database (Denmark)

    Liu, Yi; Xu, Wei; Ke, Longzhang

    2017-01-01

    The phase-locked loop (PLL) based on conventional synchronous reference frame, i.e. dqPLL, is usually employed in grid-connected variable speed constant frequency (VSCF) power generation systems (PGSs). However, the voltage amplitude drop of stand-alone PGSs is often greater than that of the grid...

  3. Pump characteristics and applications

    CERN Document Server

    Volk, Michael

    2013-01-01

    Providing a wealth of information on pumps and pump systems, Pump Characteristics and Applications, Third Edition details how pump equipment is selected, sized, operated, maintained, and repaired. The book identifies the key components of pumps and pump accessories, introduces the basics of pump and system hydraulics as well as more advanced hydraulic topics, and details various pump types, as well as special materials on seals, motors, variable frequency drives, and other pump-related subjects. It uses example problems throughout the text, reinforcing the practical application of the formulae

  4. High speed capillary zone electrophoresis-mass spectrometry via an electrokinetically pumped sheath flow interface for rapid analysis of amino acids and a protein digest.

    Science.gov (United States)

    Schiavone, Nicole M; Sarver, Scott A; Sun, Liangliang; Wojcik, Roza; Dovichi, Norman J

    2015-06-01

    While capillary zone electrophoresis (CZE) has been used to produce very rapid and efficient separations, coupling these high-speed separations with mass spectrometry (MS) has been challenging. Now, with much faster and sensitive mass spectrometers, it is possible to take full advantage of the CZE speed and reconstruct the fast migrating peaks. Here are three high-speed CZE-MS analyses via an electrokinetically pumped sheath-flow interface. The first separation demonstrates CZE-ESI-MS of an amino acid mixture with a 2-min separation, >50,000 theoretical plates, low micromolar concentration detection limits, and subfemtomole mass detection limits (LTQ XL mass spectrometer). The second separation with our recently improved third-generation CE-MS interface illustrates a 20 amino acid separation in ∼7min with an average over 200,000 plate counts, and results in almost-baseline resolution of structural isomers, leucine and isoleucine. The third separation is of a BSA digest with a reproducible CZE separation and mass spectrometry detection in 2min. CZE-MS/MS analysis of the BSA digest identified 31 peptides, produced 52% sequence coverage, and generated a peak capacity of ∼40 across the 1-min separation window (Q-Exactive mass spectrometer). Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Variable Pitch Approach for Performance Improving of Straight-Bladed VAWT at Rated Tip Speed Ratio

    Directory of Open Access Journals (Sweden)

    Zhenzhou Zhao

    2018-06-01

    Full Text Available This paper presents a new variable pitch (VP approach to increase the peak power coefficient of the straight-bladed vertical-axis wind turbine (VAWT, by widening the azimuthal angle band of the blade with the highest aerodynamic torque, instead of increasing the highest torque. The new VP-approach provides a curve of pitch angle designed for the blade operating at the rated tip speed ratio (TSR corresponding to the peak power coefficient of the fixed pitch (FP-VAWT. The effects of the new approach are exploited by using the double multiple stream tubes (DMST model and Prandtl’s mathematics to evaluate the blade tip loss. The research describes the effects from six aspects, including the lift, drag, angle of attack (AoA, resultant velocity, torque, and power output, through a comparison between VP-VAWTs and FP-VAWTs working at four TSRs: 4, 4.5, 5, and 5.5. Compared with the FP-blade, the VP-blade has a wider azimuthal zone with the maximum AoA, lift, drag, and torque in the upwind half-cycle, and yields the two new larger maximum values in the downwind half-cycle. The power distribution in the swept area of the turbine changes from an arched shape of the FP-VAWT into the rectangular shape of the VP-VAWT. The new VP-approach markedly widens the highest-performance zone of the blade in a revolution, and ultimately achieves an 18.9% growth of the peak power coefficient of the VAWT at the optimum TSR. Besides achieving this growth, the new pitching method will enhance the performance at TSRs that are higher than current optimal values, and an increase of torque is also generated.

  6. Scalable Active Optical Access Network Using Variable High-Speed PLZT Optical Switch/Splitter

    Science.gov (United States)

    Ashizawa, Kunitaka; Sato, Takehiro; Tokuhashi, Kazumasa; Ishii, Daisuke; Okamoto, Satoru; Yamanaka, Naoaki; Oki, Eiji

    This paper proposes a scalable active optical access network using high-speed Plumbum Lanthanum Zirconate Titanate (PLZT) optical switch/splitter. The Active Optical Network, called ActiON, using PLZT switching technology has been presented to increase the number of subscribers and the maximum transmission distance, compared to the Passive Optical Network (PON). ActiON supports the multicast slot allocation realized by running the PLZT switch elements in the splitter mode, which forces the switch to behave as an optical splitter. However, the previous ActiON creates a tradeoff between the network scalability and the power loss experienced by the optical signal to each user. It does not use the optical power efficiently because the optical power is simply divided into 0.5 to 0.5 without considering transmission distance from OLT to each ONU. The proposed network adopts PLZT switch elements in the variable splitter mode, which controls the split ratio of the optical power considering the transmission distance from OLT to each ONU, in addition to PLZT switch elements in existing two modes, the switching mode and the splitter mode. The proposed network introduces the flexible multicast slot allocation according to the transmission distance from OLT to each user and the number of required users using three modes, while keeping the advantages of ActiON, which are to support scalable and secure access services. Numerical results show that the proposed network dramatically reduces the required number of slots and supports high bandwidth efficiency services and extends the coverage of access network, compared to the previous ActiON, and the required computation time for selecting multicast users is less than 30msec, which is acceptable for on-demand broadcast services.

  7. LMFBR with booster pump in pumping loop

    International Nuclear Information System (INIS)

    Rubinstein, H.J.

    1975-01-01

    A loop coolant circulation system is described for a liquid metal fast breeder reactor (LMFBR) utilizing a low head, high specific speed booster pump in the hot leg of the coolant loop with the main pump located in the cold leg of the loop, thereby providing the advantages of operating the main pump in the hot leg with the reliability of cold leg pump operation

  8. Effect of formulation- and administration-related variables on deposition pattern of nasal spray pumps evaluated using a nasal cast.

    Science.gov (United States)

    Kundoor, Vipra; Dalby, Richard N

    2011-08-01

    To systematically evaluate the effect of formulation- and administration-related variables on nasal spray deposition using a nasal cast. Deposition pattern was assessed by uniformly coating a transparent nose model with Sar-Gel®, which changes from white to purple on contact with water. Sprays were subsequently discharged into the cast, which was then digitally photographed. Images were quantified using Adobe® Photoshop. The effects of formulation viscosity (which influences droplet size), simulated administration techniques (head orientation, spray administration angle, spray nozzle insertion depth), spray pump design and metering volume on nasal deposition pattern were investigated. There was a significant decrease in the deposition area associated with sprays of increasing viscosity. This appeared to be mediated by an increase in droplet size and a narrowing of the spray plume. Administration techniques and nasal spray pump design also had a significant effect on the deposition pattern. This simple color-based method provides quantitative estimates of the effects that different formulation and administration variables may have on the nasal deposition area, and provides a rational basis on which manufacturers of nasal sprays can base their patient instructions or post approval changes when it is impractical to optimize these using a clinical study.

  9. Full-shipload tramp ship routing and scheduling with variable speeds

    DEFF Research Database (Denmark)

    Wen, M.; Røpke, Stefan; Petersen, Hanne Løhmann

    2016-01-01

    This paper investigates the simultaneous optimization problem of routing and sailing speed in the context of full-shipload tramp shipping. In this problem, a set of cargoes can be transported from their load to discharge ports by a fleet of heterogeneous ships of different speed ranges and load......-dependent fuel consumption. The objective is to determine which orders to serve and to find the optimal route for each ship and the optimal sailing speed on each leg of the route so that the total profit is maximized. The problem originated from a real-life challenge faced by a Danish tramp shipping company....... It is shown that speed optimization can improve the total profit by 16% on average and the fuel price has a significant effect on the average sailing speed and total profit....

  10. Modeling and Performance Improvement of the Constant Power Regulator Systems in Variable Displacement Axial Piston Pump

    Science.gov (United States)

    Park, Sung Hwan; Lee, Ji Min; Kim, Jong Shik

    2013-01-01

    An irregular performance of a mechanical-type constant power regulator is considered. In order to find the cause of an irregular discharge flow at the cut-off pressure area, modeling and numerical simulations are performed to observe dynamic behavior of internal parts of the constant power regulator system for a swashplate-type axial piston pump. The commercial numerical simulation software AMESim is applied to model the mechanical-type regulator with hydraulic pump and simulate the performance of it. The validity of the simulation model of the constant power regulator system is verified by comparing simulation results with experiments. In order to find the cause of the irregular performance of the mechanical-type constant power regulator system, the behavior of main components such as the spool, sleeve, and counterbalance piston is investigated using computer simulation. The shape modification of the counterbalance piston is proposed to improve the undesirable performance of the mechanical-type constant power regulator. The performance improvement is verified by computer simulation using AMESim software. PMID:24282389

  11. Modeling and Performance Improvement of the Constant Power Regulator Systems in Variable Displacement Axial Piston Pump

    Directory of Open Access Journals (Sweden)

    Sung Hwan Park

    2013-01-01

    Full Text Available An irregular performance of a mechanical-type constant power regulator is considered. In order to find the cause of an irregular discharge flow at the cut-off pressure area, modeling and numerical simulations are performed to observe dynamic behavior of internal parts of the constant power regulator system for a swashplate-type axial piston pump. The commercial numerical simulation software AMESim is applied to model the mechanical-type regulator with hydraulic pump and simulate the performance of it. The validity of the simulation model of the constant power regulator system is verified by comparing simulation results with experiments. In order to find the cause of the irregular performance of the mechanical-type constant power regulator system, the behavior of main components such as the spool, sleeve, and counterbalance piston is investigated using computer simulation. The shape modification of the counterbalance piston is proposed to improve the undesirable performance of the mechanical-type constant power regulator. The performance improvement is verified by computer simulation using AMESim software.

  12. Modeling and performance improvement of the constant power regulator systems in variable displacement axial piston pump.

    Science.gov (United States)

    Park, Sung Hwan; Lee, Ji Min; Kim, Jong Shik

    2013-01-01

    An irregular performance of a mechanical-type constant power regulator is considered. In order to find the cause of an irregular discharge flow at the cut-off pressure area, modeling and numerical simulations are performed to observe dynamic behavior of internal parts of the constant power regulator system for a swashplate-type axial piston pump. The commercial numerical simulation software AMESim is applied to model the mechanical-type regulator with hydraulic pump and simulate the performance of it. The validity of the simulation model of the constant power regulator system is verified by comparing simulation results with experiments. In order to find the cause of the irregular performance of the mechanical-type constant power regulator system, the behavior of main components such as the spool, sleeve, and counterbalance piston is investigated using computer simulation. The shape modification of the counterbalance piston is proposed to improve the undesirable performance of the mechanical-type constant power regulator. The performance improvement is verified by computer simulation using AMESim software.

  13. On higher ground: how well can dynamic body acceleration determine speed in variable terrain?

    Directory of Open Access Journals (Sweden)

    Owen R Bidder

    Full Text Available INTRODUCTION: Animal travel speed is an ecologically significant parameter, with implications for the study of energetics and animal behaviour. It is also necessary for the calculation of animal paths by dead-reckoning. Dead-reckoning uses heading and speed to calculate an animal's path through its environment on a fine scale. It is often used in aquatic environments, where transmission telemetry is difficult. However, its adoption for tracking terrestrial animals is limited by our ability to measure speed accurately on a fine scale. Recently, tri-axial accelerometers have shown promise for estimating speed, but their accuracy appears affected by changes in substrate and surface gradients. The purpose of the present study was to evaluate four metrics of acceleration; Overall dynamic body acceleration (ODBA, vectorial dynamic body acceleration (VDBA, acceleration peak frequency and acceleration peak amplitude, as proxies for speed over hard, soft and inclined surfaces, using humans as a model species. RESULTS: A general linear model (GLM showed a significant difference in the relationships between the metrics and speed depending on substrate or surface gradient. When the data from all surface types were considered together, VeDBA had the highest coefficient of determination. CONCLUSIONS: All of the metrics showed some variation in their relationship with speed according to the surface type. This indicates that changes in the substrate or surface gradient during locomotion by animals would produce errors in speed estimates, and also in dead-reckoned tracks if they were calculated from speeds based entirely on a priori calibrations. However, we describe a method by which the relationship between acceleration metrics and speed can be corrected ad hoc, until tracks accord with periodic ground truthed positions, obtained via a secondary means (e.g. VHF or GPS telemetry. In this way, dead-reckoning provides a means to obtain fine scale movement data

  14. A pilot clinical trial on a Variable Automated Speed and Sensing Treadmill (VASST) for hemiparetic gait rehabilitation in stroke patients.

    Science.gov (United States)

    Chua, Karen S G; Chee, Johnny; Wong, Chin J; Lim, Pang H; Lim, Wei S; Hoo, Chuan M; Ong, Wai S; Shen, Mira L; Yu, Wei S

    2015-01-01

    Impairments in walking speed and capacity are common problems after stroke which may benefit from treadmill training. However, standard treadmills, are unable to adapt to the slower walking speeds of stroke survivors and are unable to automate training progression. This study tests a Variable Automated Speed and Sensing Treadmill (VASST) using a standard clinical protocol. VASST is a semi-automated treadmill with multiple sensors and micro controllers, including wireless control to reposition a fall-prevention harness, variable pre-programmed exercise parameters and laser beam foot sensors positioned on the belt to detect subject's foot positions. An open-label study with assessor blinding was conducted in 10 community-dwelling chronic hemiplegic patients who could ambulate at least 0.1 m/s. Interventions included physiotherapist-supervised training on VASST for 60 min three times per week for 4 weeks (total 12 h). Outcome measures of gait speed, quantity, balance, and adverse events were assessed at baseline, 2, 4, and 8 weeks. Ten subjects (8 males, mean age 55.5 years, 2.1 years post stroke) completed VASST training. Mean 10-m walk test speed was 0.69 m/s (SD = 0.29) and mean 6-min walk test distance was 178.3 m (84.0). After 4 weeks of training, 70% had significant positive gains in gait speed (0.06 m/s, SD = 0.08 m/s, P = 0.037); and 90% improved in walking distance. (54.3 m, SD = 30.9 m, P = 0.005). There were no adverse events. This preliminary study demonstrates the initial feasibility and short-term efficacy of VASST for walking speed and distance for people with chronic post-stroke hemiplegia.

  15. Sodium pumping: pump problems

    International Nuclear Information System (INIS)

    Guer, M.; Guiton, P.

    Information on sodium pumps for LMFBR type reactors is presented concerning ring pump design, pool reactor pump design, secondary pumps, sodium bearings, swivel joints of the oscillating annulus, and thermal shock loads

  16. Oil supply on demand: Oil pumps in serial application; Bedarfsgerechte Oelversorgung: Regeloelpumpen im Serieneinsatz

    Energy Technology Data Exchange (ETDEWEB)

    Lamparski, C. [S H W Automotive GmbH und Co. KG, Bad Schussenried (Germany)

    2007-07-01

    Usually, constant displacement oil pumps are used for the oil supply of combustion engines. Gerotor, helical or spur gear pumps or vane pumps are the most common solutions. The disadvantage of the mentioned design is the oil delivery as function of pump speed, independent from the engine needs. Variability of oil delivery for reduction of hydraulic losses is the logical consequence. The first variable displacement oil pump which has fulfilled this requirement is the Internal Regulated Oil Pump (IRP). The mass production of this oil pump started in 2002. The solution for outer gear pumps and vane cells followed shortly. The following contribution gives a summary of different technical concepts for adjusting of oil delivery, beginning with pump pressure as a leading value till map regulation and its transformation in mass production products. (orig.)

  17. Adaptive sliding mode back-stepping pitch angle control of a variable-displacement pump controlled pitch system for wind turbines.

    Science.gov (United States)

    Yin, Xiu-xing; Lin, Yong-gang; Li, Wei; Liu, Hong-wei; Gu, Ya-jing

    2015-09-01

    A variable-displacement pump controlled pitch system is proposed to mitigate generator power and flap-wise load fluctuations for wind turbines. The pitch system mainly consists of a variable-displacement hydraulic pump, a fixed-displacement hydraulic motor and a gear set. The hydraulic motor can be accurately regulated by controlling the pump displacement and fluid flows to change the pitch angle through the gear set. The detailed mathematical representation and dynamic characteristics of the proposed pitch system are thoroughly analyzed. An adaptive sliding mode pump displacement controller and a back-stepping stroke piston controller are designed for the proposed pitch system such that the resulting pitch angle tracks its desired value regardless of external disturbances and uncertainties. The effectiveness and control efficiency of the proposed pitch system and controllers have been verified by using realistic dataset of a 750 kW research wind turbine. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

  18. In situ measurements of krypton in xenon gas with a quadrupole mass spectrometer following a cold-trap at a temporarily reduced pumping speed

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Ethan; Rosendahl, Stephan; Huhmann, Christian; Kettling, Hans; Schlak, Martin; Weinheimer, Christian [Muenster Univ. (Germany). Inst. fuer Kernphysik

    2013-07-01

    Liquid xenon detectors have risen to be extremely competitive for dark matter and neutrinoless double-beta decay searches. In order to achieve the required sensitivity, backgrounds must be reduced substantially. One important background is the beta-decay of {sup 85}Kr, which constitutes a uniform internal background in liquid xenon detectors. Cryogenic distillation can be used to reduce the krypton concentration to acceptable levels, but gas diagnostics become incredibly difficult at these ultra-pure levels. A new method for measuring the concentration of krypton in xenon has been developed, expanding on the existing technique of a cold trap and a Residual Gas Analyzer (RGA). By using a liquid nitrogen cold trap, one can take advantage of the difference in vapor pressures of krypton in xenon to freeze most of the xenon gas while allowing the krypton to pass to the measurement chamber. Here, only a few milliliters of xenon is expended in the measurement, while achieving a sensitivity of sub ppb (parts per billion). The key change is the use of a butterfly valve to partially close the opening in front of the turbomolecular pump, thereby reducing the effective pumping speed and enhancing the RGA signal.

  19. Mode Transition Variable Geometry for High Speed Inlets for Hypersonic Aircraft, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Hypersonic propulsion research has been a focus of the NASA aeronautics program for years. Previous high-speed cruise and space access programs have examined the...

  20. Use of an expert system for the choice of variable speed drives; Application des techniques d`intelligence artificielle pour le choix des systemes d`entrainement a vitesse variable

    Energy Technology Data Exchange (ETDEWEB)

    Chetate, B.; Khaldi, T.; Boudjennah, B.; Kara, C. [Institut National des Hydrocarbures et de la Chimie de Boumerdes (Algeria). Laboratoire des Economies d`Energie Electrique

    1998-06-01

    The electrical motors variable speed is a factor of energy saving. The interest of variable speed is justified by the fact that the investment is quickly redeemable. In this study, the authors present an expert system for the rational choice of variable speed drives (IES/VSD). This system allows to take into account the varieties of electrical motors, electronics converters and complex control systems. (authors) 12 refs.

  1. An Adaptive Frequency Strategy for Variable Speed Wind Turbines: Application to High Wind Integration Into Power Systems

    Directory of Open Access Journals (Sweden)

    Ana Fernández-Guillamón

    2018-06-01

    Full Text Available This paper presents a new frequency controller for variable speed wind turbines connected to the grid under power imbalance conditions. It is based on the fast power reserve emulation technique, having two different operation modes: overproduction and recovery mode. In the first mode, the active power provided by wind turbines is set over the mechanical power, reducing their rotational speed. This overproduction power is estimated according to the frequency excursion. In the second mode, the active power is established under the mechanical power to recover the initial rotational speed through a smooth trajectory. The power system considered for simulation purposes includes thermal, hydro-power and wind-power plants. The controller proposed has been evaluated under different mix-generation scenarios implemented in Matlab/Simulink. Extensive results and comparison to previous proposals are also included in the paper.

  2. Control model design to limit DC-link voltage during grid fault in a dfig variable speed wind turbine

    Science.gov (United States)

    Nwosu, Cajethan M.; Ogbuka, Cosmas U.; Oti, Stephen E.

    2017-08-01

    This paper presents a control model design capable of inhibiting the phenomenal rise in the DC-link voltage during grid- fault condition in a variable speed wind turbine. Against the use of power circuit protection strategies with inherent limitations in fault ride-through capability, a control circuit algorithm capable of limiting the DC-link voltage rise which in turn bears dynamics that has direct influence on the characteristics of the rotor voltage especially during grid faults is here proposed. The model results so obtained compare favorably with the simulation results as obtained in a MATLAB/SIMULINK environment. The generated model may therefore be used to predict near accurately the nature of DC-link voltage variations during fault given some factors which include speed and speed mode of operation, the value of damping resistor relative to half the product of inner loop current control bandwidth and the filter inductance.

  3. Peristaltic pumps for waste disposal

    International Nuclear Information System (INIS)

    Griffith, G.W.

    1992-09-01

    Laboratory robots are capable of generating large volumes of hazardous liquid wastes when they are used to perform chemical analyses of metal finishing solutions. A robot at Allied-Signal Inc., Kansas City Division, generates 30 gallons of acid waste each month. This waste contains mineral acids, heavy metals, metal fluorides, and other materials. The waste must be contained in special drums that are closed to the atmosphere. The initial disposal method was to have the robot pour the waste into a collecting funnel, which contained a liquid-sensing valve to admit the waste into the drum. Spills were inevitable, splashing occurred, and the special valve often didn't work well. The device also occupied a large amount of premium bench space. Peristaltic pumps are made to handle hazardous liquids quickly and efficiently. A variable-speed pump, equipped with a quick-loading pump head, was mounted below the robot bench near the waste barrel. The pump inlet tube was mounted above the bench within easy reach of the robot, while the outlet tube was connected directly to the barrel. During operation, the robot brings the waste liquid up to the pump inlet tube and activates the pump. When the waste has been removed, the pump stops. The procedure is quick, simple, inexpensive, safe, and reliable

  4. Variable-Speed Generation Subsystem Using the Doubly-Fed Generator; Period of Performance February 9, 1994 - April 30, 1999

    Energy Technology Data Exchange (ETDEWEB)

    Weigand, C.H.; Lauw, H.K.; Marckx, D.A. (Electronic Power Conditioning Incorporated)

    2000-12-18

    Over the past decade, fixed-speed, utility-scale wind turbines have technically advanced to a point where they can economically complete against nuclear and fossil-fuel-based power plants in geographical areas with a sufficient wind resource. The objective of this subcontract was to compare various electrical topologies allowing variable-speed turbine operation, identify the most suitable for a 275-kW (or larger) utility-scale wind turbine, and then design, build, lab test, and field test this variable-speed generation subsystem based on the previously identified optimum approach. Preliminary tests of the controls for a doubly fed variable-speed generation system rated at 750 kW were performed on a wind turbine. A 275-kW VSGS was thoroughly tested in the laboratory and on a wind turbine. Using field-oriented control, excellent dynamic behavior of the drive train was demonstrated, acoustic tests revealed an 11 dB reduction in turbine noise in low-wind, low-RPM operation compared to fixed-speed operation. The overall efficiency of the electrical system suffered from inadequate efficiency of the power converter at low power. Consequently, a different converter topology has been proposed that will satisfy both efficiency and power quality requirements for future use. This report provides information on all aspects of the project, including events that were unanticipated at the outset. A great deal of information is available in the references, comprised of NREL reports, journal articles, and conference papers on specific project results.

  5. Numerical Simulation of Tubular Pumping Systems with Different Regulation Methods

    Science.gov (United States)

    Zhu, Honggeng; Zhang, Rentian; Deng, Dongsheng; Feng, Xusong; Yao, Linbi

    2010-06-01

    Since the flow in tubular pumping systems is basically along axial direction and passes symmetrically through the impeller, most satisfying the basic hypotheses in the design of impeller and having higher pumping system efficiency in comparison with vertical pumping system, they are being widely applied to low-head pumping engineering. In a pumping station, the fluctuation of water levels in the sump and discharge pool is most common and at most time the pumping system runs under off-design conditions. Hence, the operation of pump has to be flexibly regulated to meet the needs of flow rates, and the selection of regulation method is as important as that of pump to reduce operation cost and achieve economic operation. In this paper, the three dimensional time-averaged Navier-Stokes equations are closed by RNG κ-ɛ turbulent model, and two tubular pumping systems with different regulation methods, equipped with the same pump model but with different designed system structures, are numerically simulated respectively to predict the pumping system performances and analyze the influence of regulation device and help designers make final decision in the selection of design schemes. The computed results indicate that the pumping system with blade-adjusting device needs longer suction box, and the increased hydraulic loss will lower the pumping system efficiency in the order of 1.5%. The pumping system with permanent magnet motor, by means of variable speed regulation, obtains higher system efficiency partly for shorter suction box and partly for different structure design. Nowadays, the varied speed regulation is realized by varied frequency device, the energy consumption of which is about 3˜4% of output power of the motor. Hence, when the efficiency of variable frequency device is considered, the total pumping system efficiency will probably be lower.

  6. Exploring the stochastic and deterministic aspects of cyclic emission variability on a high speed spark-ignition engine

    International Nuclear Information System (INIS)

    Karvountzis-Kontakiotis, A.; Dimaratos, A.; Ntziachristos, L.; Samaras, Z.

    2017-01-01

    This study contributes to the understanding of cycle-to-cycle emissions variability (CEV) in premixed spark-ignition combustion engines. A number of experimental investigations of cycle-to-cycle combustion variability (CCV) exist in published literature; however only a handful of studies deal with CEV. This study experimentally investigates the impact of CCV on CEV of NO and CO, utilizing experimental results from a high-speed spark-ignition engine. Both CEV and CCV are shown to comprise a deterministic and a stochastic component. Results show that at maximum break torque (MBT) operation, the indicated mean effective pressure (IMEP) maximizes and its coefficient of variation (COV_I_M_E_P) minimizes, leading to minimum variation of NO. NO variability and hence mean NO levels can be reduced by more than 50% and 30%, respectively, at advanced ignition timing, by controlling the deterministic CCV using cycle resolved combustion control. The deterministic component of CEV increases at lean combustion (lambda = 1.12) and this overall increases NO variability. CEV was also found to decrease with engine load. At steady speed, increasing throttle position from 20% to 80%, decreased COV_I_M_E_P, COV_N_O and COV_C_O by 59%, 46%, and 6% respectively. Highly resolved engine control, by means of cycle-to-cycle combustion control, appears as key to limit the deterministic feature of cyclic variability and by that to overall reduce emission levels. - Highlights: • Engine emissions variability comprise both stochastic and deterministic components. • Lean and diluted combustion conditions increase emissions variability. • Advanced ignition timing enhances the deterministic component of variability. • Load increase decreases the deterministic component of variability. • The deterministic component can be reduced by highly resolved combustion control.

  7. Pumping station design for a pumped-storage wind-hydro power plant

    International Nuclear Information System (INIS)

    Anagnostopoulos, John S.; Papantonis, Dimitris E.

    2007-01-01

    This work presents a numerical study of the optimum sizing and design of a pumping station unit in a hybrid wind-hydro plant. The standard design that consists of a number of identical pumps operating in parallel is examined in comparison with two other configurations, using one variable-speed pump or an additional set of smaller jockey pumps. The aim is to reduce the amount of the wind generated energy that cannot be transformed to hydraulic energy due to power operation limits of the pumps and the resulting step-wise operation of the pumping station. The plant operation for a period of one year is simulated by a comprehensive evaluation algorithm, which also performs a detailed economic analysis of the plant using dynamic evaluation methods. A preliminary study of the entire plant sizing is carried out at first using an optimization tool based on evolutionary algorithms. The performance of the three examined pumping station units is then computed and analyzed in a comparative study. The results reveal that the use of a variable-speed pump constitutes the most effective and profitable solution, and its superiority is more pronounced for less dispersed wind power potential

  8. Analysis for SEER of variable speed room air conditioner in China. Paper no. IGEC-1-104

    International Nuclear Information System (INIS)

    Yitai, M.; Shengchun, L.; Lirong, M.

    2005-01-01

    In this paper, the calculation method for seasonal energy efficiency ratio (SEER) given in Standard JRA4046-1999 is analyzed and further modified. Based on temperature zone map of U.S., Japan and China and detailed weather data of eight Chinese cities in last 30 years, regional seasonal energy efficiency ratio (RSEER) and energy saving percentage of variable speed room air conditioner are analyzed and compared with various geographical regions in China. It is concluded that RSEER presents the associated effect of season, climate and geography, and therefore should be taken as an evaluation standard for room air conditioner, especially variable speed room air conditioner. Experimental measurements are conducted in the analysis to investigate the effect of energy efficiency ratio (EER) on the improvement of energy saving percentage and SEER. (author)

  9. Intelligent Multiobjective Slip and Speed Ratio Control of a Novel Dual-Belt Continuously Variable Transmission for Automobiles

    Directory of Open Access Journals (Sweden)

    Zhengchao Xie

    2014-01-01

    Full Text Available Van Doorne’s continuously variable transmission (CVT is the most popular CVT design for automotive transmission, but it is only applicable to low-power passenger cars because of its low torque capacity. To overcome this limitation of traditional single-belt CVT, a novel dual-belt Van Doorne’s CVT (DBVCVT system, which is applicable to heavy-duty vehicles, has been previously proposed by the authors. This paper, based on the published analytical model and test rig of DBVCVT, further proposes an intelligent multiobjective fuzzy controller for slip and speed ratio control of DBVCVT. The controller aims to safely control the clamping forces of both the primary and the secondary pulleys in order to improve the transmission efficiency, achieve the accurate speed ratio, and avoid the belt slip under different engine loads and vehicle speeds. The slip, speed ratio, and transmission efficiency dynamics of DBVCVT are firstly analyzed and modeled in this paper. With the aid of a flexible objective function, the analytical model, and fuzzy logic, a Pareto rule base for fuzzy controller is developed for multiobjective DBVCVT control. Experimental results show that the proposed controller for slip and speed ratio regulation of DBVCVT is effective and performs well under different user-defined weights.

  10. A comparison of the hourly output between the Ambu® Smart-Infuser™ Pain Pump and the On-Q Pump® with Select-A-Flow™ Variable Rate Controller with standard and overfill volumes.

    Science.gov (United States)

    Iliev, Peter; Bhalla, Tarun; Tobias, Joseph D

    2016-04-01

    The Ambu Smart-Infuser Pain Pump and the On-Q Pump with Select-a-Flow Variable Rate Controller are elastomeric devices with a flow regulator that controls the rate of infusion of a local anesthetic agent through a peripheral catheter. As a safety evaluation, we evaluated the infusion characteristics of these two devices when filled with manufacturer recommended standard volumes and when overfilled with a volume 50% in excess of that which is recommended. Nineteen disposable devices from the two manufacturers were used in this study. Nine were filled with 0.9% normal saline according to the respective manufacturers' recommendations (four Ambu pumps were filled with 650 ml and five On-Q pumps were filled with 550 ml) and 10 devices were 150% overfilled (five Ambu pumps were filled with 975 ml and five On-Q pumps were filled with 825 ml). All of the devices were set to infuse at 10 ml · h(-1) at room temperature (21°C) for 12 h. The fluid delivered during each 2-h period was measured using a graduated column. The On-Q pump (in the settings of normal fill and 150% overfill) delivered a significantly higher output per hour than the set rate during the first 8 h, while the Ambu pump delivered a value close to the set rate of 10 ml · h(-1). No significant difference in the hourly delivered output was noted for either device when comparing the normal fill to the 150% overfill groups. This investigation demonstrates that no change in the hourly output occurs with overfilling of these home infusion devices. However, as noted previously, the hourly output from the On-Q device is significantly higher than the set rate during the initial 8 h of infusion which could have potential clinical implications. © 2016 John Wiley & Sons Ltd.

  11. Modeling and Control of a DC-grid Hybrid Power System with Battery and Variable Speed Diesel Generators

    OpenAIRE

    Syverud, Tron Hansen

    2016-01-01

    Hybrid electric power systems (HPS) have successfully been integrated in the road-traffic industry due to enhanced efficiency and environmental benefits. Recently this concept has been implemented in the marine sector. In this master thesis, the construction of a DC hybrid power system for a marine vessel is outlined in detail. The HPS is developed in Matlbat/Simulink and comprises two set of diesel generators with variable speed, six-pulse diode bridges, a battery bank, bidire...

  12. Realization of PLC to the Variable Frequency Speed Regulation System of Mine Local Ventilator based on RS-485 Communication

    Science.gov (United States)

    Ma, Kai; Li, Jian; Yun, Yichong

    2018-03-01

    The article first introduces the merits of serial communication in the PLC to the variable frequency speed regulation system of mine local ventilator, and then sets up a hardware application development platform of PLC and inverter based on RS-485 communication technology, next presents communication initialization of the PLC and Inverter. Finally according to the control requirements, PLC send run operation & monitoring instruction to Inverter, realizes the serial communication control between the PLC and Inverter.

  13. Constant versus variable response signal delays in speed--accuracy trade-offs: effects of advance preparation for processing time.

    Science.gov (United States)

    Miller, Jeff; Sproesser, Gudrun; Ulrich, Rolf

    2008-07-01

    In two experiments, we used response signals (RSs) to control processing time and trace out speed--accuracy trade-off(SAT) functions in a difficult perceptual discrimination task. Each experiment compared performance in blocks of trials with constant and, hence, temporally predictable RS lags against performance in blocks with variable, unpredictable RS lags. In both experiments, essentially equivalent SAT functions were observed with constant and variable RS lags. We conclude that there is little effect of advance preparation for a given processing time, suggesting that the discrimination mechanisms underlying SAT functions are driven solely by bottom-up information processing in perceptual discrimination tasks.

  14. Design of Stirrer Impeller with Variable Operational Speed for a Food Waste Homogenizer

    Directory of Open Access Journals (Sweden)

    Idris A. Kayode

    2016-05-01

    Full Text Available A conceptualized impeller called KIA is designed for impact agitation of food waste in a homogenizer. A comparative analysis of the performance of KIA is made with three conventional impeller types, Rushton, Anchor, and Pitched Blade. Solid–liquid mixing of a moisture-rich food waste is simulated under various operational speeds, in order to compare the dispersions and thermal distributions at homogenous slurry conditions. Using SolidWorks, the design of the impellers employs an Application Programming Interface (API which acts as the canvas for creating a graphical user interface (GUI for automation of its assembly. A parametric analysis of the homogenizer, at varying operational speeds, enables the estimation of the critical speed of the mixing shaft diameter and the deflection under numerous mixing conditions and impeller configurations. The numerical simulation of the moisture-rich food waste (approximated as a Newtonian carrot–orange soup is performed with ANSYS CFX v.15.0. The velocity and temperature field distribution of the homogenizer for various impeller rotational speeds are analyzed. It is anticipated that the developed model will help in the selection of a suitable impeller for efficient mixing of food waste in the homogenizer.

  15. Typing Speed as a Confounding Variable and the Measurement of Quality in Divergent Thinking

    Science.gov (United States)

    Forthmann, Boris; Holling, Heinz; Çelik, Pinar; Storme, Martin; Lubart, Todd

    2017-01-01

    The need to control for writing or typing speed when assessing divergent-thinking performance has been recognized since the early '90s. An even longer tradition in divergent-thinking research has the issue of scoring the responses for quality. This research addressed both issues within structural equation modeling. Three dimensions of…

  16. Variable-speed-of-light cosmology and second law of thermodynamics

    International Nuclear Information System (INIS)

    Youm, Donam

    2002-01-01

    We examine whether cosmologies with a varying speed of light (VSL) are compatible with the second law of thermodynamics. We find that the VSL cosmology with a varying fundamental constant is severely constrained by the second law of thermodynamics, whereas the bimetric cosmological models are less constrained

  17. Variable-speed-of-light cosmology and second law of thermodynamics

    International Nuclear Information System (INIS)

    Youm, Donam

    2002-03-01

    We examine whether the cosmologies with varying speed of light (VSL) are compatible with the second law of thermodynamics. We find that the VSL cosmology with varying fundamental constant is severely constrained by the second law of thermodynamics, whereas the bimetric cosmological models are less constrained. (author)

  18. Control design for a pitch-regulated, variable speed wind turbine

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, M.H.; Hansen, A.; Larsen, T.J.; Oeye, S.; Soerensen, P.; Fuglsang, P.

    2005-01-01

    The three different controller designs presented herein are similar and all based on PI-regulation of rotor speed and power through the collective blade pitch angle and generator moment. The aeroelastic and electrical modelling used for the time-domain analysis of these controllers are however different, which makes a directly quantitative comparison difficult. But there are some observations of similar behaviours should be mentioned: 1) Very similar step responses in rotor speed, pitch angle, and power are seen for simulations with steps in wind speed. 2) All controllers show a peak in power for wind speed step-up over rated wind speed, which can be almost removed by changing the parameters of the frequency converter. 3) Responses of rotor speed, pitch angle, and power for different simulations with turbulent inflow are similar for all three controllers. Again, there seems to be an advantage of tuning the parameters of the frequency converter to obtain a more constant power output. The dynamic modelling of the power controller is an important result for the inclusion of generator dynamics in the aeroelastic modelling of wind turbines. A reduced dynamic model of the relation between generator torque and generator speed variations is presented; where the integral term of the inner PI-regulator of rotor current is removed be-cause the time constant is very small compared to the important aeroelastic frequencies. It is shown how the parameters of the transfer function for the remaining control system with the outer PI-regulator of power can be derived from the generator data sheet. The main results of the numerical optimisation of the control parameters in the pitch PI-regulator performed in Chapter 6 are the following: 1) Numerical optimization can be used to tune controller parameters, especially when the optimization is used as refinement of a qualified initial guess. 2) The design model used to calculate the initial value parameters, as described in Chapter 3

  19. Role of pump hydro in electric power systems

    Science.gov (United States)

    Bessa, R.; Moreira, C.; Silva, B.; Filipe, J.; Fulgêncio, N.

    2017-04-01

    This paper provides an overview of the expected role that variable speed hydro power plants can have in future electric power systems characterized by a massive integration of highly variable sources. Therefore, it is discussed the development of a methodology for optimising the operation of hydropower plants under increasing contribution from new renewable energy sources, addressing the participation of a hydropower plant with variable speed pumping in reserve markets. Complementarily, it is also discussed the active role variable speed generators can have in the provision of advanced frequency regulation services.

  20. Learning multiple variable-speed sequences in striatum via cortical tutoring.

    Science.gov (United States)

    Murray, James M; Escola, G Sean

    2017-05-08

    Sparse, sequential patterns of neural activity have been observed in numerous brain areas during timekeeping and motor sequence tasks. Inspired by such observations, we construct a model of the striatum, an all-inhibitory circuit where sequential activity patterns are prominent, addressing the following key challenges: (i) obtaining control over temporal rescaling of the sequence speed, with the ability to generalize to new speeds; (ii) facilitating flexible expression of distinct sequences via selective activation, concatenation, and recycling of specific subsequences; and (iii) enabling the biologically plausible learning of sequences, consistent with the decoupling of learning and execution suggested by lesion studies showing that cortical circuits are necessary for learning, but that subcortical circuits are sufficient to drive learned behaviors. The same mechanisms that we describe can also be applied to circuits with both excitatory and inhibitory populations, and hence may underlie general features of sequential neural activity pattern generation in the brain.

  1. Design of Stirrer Impeller with Variable Operational Speed for a Food Waste Homogenizer

    OpenAIRE

    Idris A. Kayode; Emmanuel O. B. Ogedengbe; Marc A. Rosen

    2016-01-01

    A conceptualized impeller called KIA is designed for impact agitation of food waste in a homogenizer. A comparative analysis of the performance of KIA is made with three conventional impeller types, Rushton, Anchor, and Pitched Blade. Solid–liquid mixing of a moisture-rich food waste is simulated under various operational speeds, in order to compare the dispersions and thermal distributions at homogenous slurry conditions. Using SolidWorks, the design of the impellers employs an Application P...

  2. Implementation of MRAC controller of a DFIG based variable speed grid connected wind turbine

    International Nuclear Information System (INIS)

    Abdeddaim, Sabrina; Betka, Achour; Drid, Said; Becherif, Mohamed

    2014-01-01

    Highlights: • Set-up of an experimental test emulating a wind turbine, driving a grid-connected conventional DFIG. • An optimal operation below rated speed is achieved by means of an appropriate maximum power-point tracking algorithm. • Design and implementation of an adaptive model reference controller (MRAC) of the active and reactive power regulation. - Abstract: This paper presents the design and the implementation of a model reference adaptive control of the active and reactive power regulation of a grid connected wind turbine based on a doubly fed induction generator. This regulation is achieved below the synchronous speed, by means of a maximum power-point tracking algorithm. The experiment was conducted on a 1 kW didactic wound rotor induction machine in association with a wind turbine emulator. This implementation is realized using a dSPACE 1104 single-board control and acquisition interface. The obtained results show a permanent track of the available maximum wind power, under a chosen wind speed profile. Furthermore the proposed controller exhibits a smooth regulation of the stator active and reactive power amounts exchanged between the machine and the grid

  3. Advantages of variable-speed operation of hydraulic turbo-engines; Vorteile durch den drehzahlvariablen Betrieb von hydraulischen Stroemungsmaschinen

    Energy Technology Data Exchange (ETDEWEB)

    Harbort, T. [Stuttgart Univ. (Germany). Inst. fuer Stroemungsmechanik und Hydraulische Stroemungsmaschinen

    1997-12-31

    The performance of current hydraulic turbo-engines in the variable speed sector is monitored and judged. The study covers radial and axial engines as well as Pelton turbines. Variable-speed operation of hydraulic turbo-engines can be realized by means of different combinations of electrical rotating machines and frequency converters. The operating range of the frequency converter plays an important role in the optimization of performance and is taken into account. The smoothness of run of reaction turbines and their cavitation performance can be enhanced by speed regulation. But above all, efficiency is more or less substantially enhanced during partial load or in the case of greatly varying heights of drop. The latter holds true also of Pelton turbines. (orig.) [Deutsch] Das Betriebsverhalten der gaengigen hydraulischen Stroemungsmaschinen wird in Hinblick auf den drehzahlvariablen Betrieb erfasst und beurteilt. Die Untersuchung erfolgt fuer Radialmaschinen, Axialmaschinen und Peltonturbinen. Der drehzahlvariable Betrieb hydraulischer Stroemungsmaschinen kann mit verschiedenen Kombinationen von elektrischen Maschinen und Frequenzumrichtern realisiert werden. Der Arbeitsbereich des Frequenzumrichters spielt eine wichtige Rolle fuer die Optimierung des Betriebsverhaltens und wird beruecksichtigt. Bei Ueberdruckturbinen kann man durch Drehzahlregelung eine groessere Laufruhe sowie ein guenstigeres Kavitationsverhalten erreichen. Vor allem aber sind im Teillastbereich oder bei stark schwankenden Fallhoehen mehr oder weniger grosse Wirkungsgradgewinne erzielbar. Das letztere gilt auch fuer Peltonturbinen. (orig.)

  4. Vertical dynamics of a single-span beam subjected to moving mass-suspended payload system with variable speeds

    Science.gov (United States)

    He, Wei

    2018-03-01

    This paper presents the vertical dynamics of a simply supported Euler-Bernoulli beam subjected to a moving mass-suspended payload system of variable velocities. A planar theoretical model of the moving mass-suspended payload system of variable speeds is developed based on several assumptions: the rope is massless and rigid, and its length keeps constant; the stiffness of the gantry beam is much greater than the supporting beam, and the gantry beam can be treated as a mass particle traveling along the supporting beam; the supporting beam is assumed as a simply supported Bernoulli-Euler beam. The model can be degenerated to consider two classical cases-the moving mass case and the moving payload case. The proposed model is verified using both numerical and experimental methods. To further investigate the effect of possible influential factors, numerical examples are conducted covering a range of parameters, such as variable speeds (acceleration or deceleration), mass ratios of the payload to the total moving load, and the pendulum lengths. The effect of beam flexibility on swing response of the payload is also investigated. It is shown that the effect of a variable speed is significant for the deflections of the beam. The accelerating movement tends to induce larger beam deflections, while the decelerating movement smaller ones. For accelerating or decelerating movements, the moving mass model may underestimate the deflections of the beam compared with the presented model; while for uniform motion, both the moving mass model and the moving mass-payload model lead to same beam responses. Furthermore, it is observed that the swing response of the payload is not sensitive to the stiffness of the beam for operational cases of a moving crane, thus a simple moving payload model can be employed in the swing control of the payload.

  5. Results of Investigations of Failures of Geothermal Direct Use Well Pumps

    Energy Technology Data Exchange (ETDEWEB)

    Culver, G.

    1994-12-01

    Failures of 13 geothermal direct-use well pumps were investigated and information obtained about an additional 5 pumps that have been in service up to 23 years, but have not failed. Pumps with extra long lateral and variable-speed drives had the highest correlation with reduced time in service. There appears to be at least circumstantial evidence that recirculation may be a cause of reduced pump life. If recirculation is a cause of pump failures, pump specifiers will need to be more aware of minimum flow conditions as well as maximum flow conditions when specifying pumps. Over-sizing pumps and the tendency to specify pumps with high flow and low Net Positive Suction Head (NPSH) could lead to increased problems with recirculation.

  6. Sliding Mode Control of a Variable- Speed Wind Energy Conversion System Using a Squirrel Cage Induction Generator

    Directory of Open Access Journals (Sweden)

    Mohamed Zribi

    2017-05-01

    Full Text Available This paper deals with the control of a variable-speed wind energy conversion (WEC system using a squirrel cage induction generator (SCIG connected to the grid through a back-to-back three phase (AC-DC-AC power converter. The sliding mode control technique is used to control the WEC system. The objective of the controllers is to force the states of the system to track their desired states. One controller is used to regulate the generator speed and the flux so that maximum power is extracted from the wind. Another controller is used to control the grid side converter, which controls the DC bus voltage and the active and reactive powers injected into the grid. The performance of the controlled wind energy conversion system is verified through MATLAB simulations, which show that the controlled system performs well.

  7. Effect of trotting speed on kinematic variables measured by use of extremity-mounted inertial measurement units in nonlame horses performing controlled treadmill exercise.

    Science.gov (United States)

    Cruz, Antonio M; Vidondo, Beatriz; Ramseyer, Alessandra A; Maninchedda, Ugo E

    2018-02-01

    OBJECTIVE To assess effects of speed on kinematic variables measured by use of extremity-mounted inertial measurement units (IMUs) in nonlame horses performing controlled exercise on a treadmill. ANIMALS 10 nonlame horses. PROCEDURES 6 IMUs were attached at predetermined locations on 10 nonlame Franches Montagnes horses. Data were collected in triplicate during trotting at 3.33 and 3.88 m/s on a high-speed treadmill. Thirty-three selected kinematic variables were analyzed. Repeated-measures ANOVA was used to assess the effect of speed. RESULTS Significant differences between the 2 speeds were detected for most temporal (11/14) and spatial (12/19) variables. The observed spatial and temporal changes would translate into a gait for the higher speed characterized by increased stride length, protraction and retraction, flexion and extension, mediolateral movement of the tibia, and symmetry, but with similar temporal variables and a reduction in stride duration. However, even though the tibia coronal range of motion was significantly different between speeds, the high degree of variability raised concerns about whether these changes were clinically relevant. For some variables, the lower trotting speed apparently was associated with more variability than was the higher trotting speed. CONCLUSIONS AND CLINICAL RELEVANCE At a higher trotting speed, horses moved in the same manner (eg, the temporal events investigated occurred at the same relative time within the stride). However, from a spatial perspective, horses moved with greater action of the segments evaluated. The detected changes in kinematic variables indicated that trotting speed should be controlled or kept constant during gait evaluation.

  8. Estimation of the high-spatial-resolution variability in extreme wind speeds for forestry applications

    Directory of Open Access Journals (Sweden)

    A. Venäläinen

    2017-07-01

    Full Text Available The bioeconomy has an increasing role to play in climate change mitigation and the sustainable development of national economies. In Finland, a forested country, over 50 % of the current bioeconomy relies on the sustainable management and utilization of forest resources. Wind storms are a major risk that forests are exposed to and high-spatial-resolution analysis of the most vulnerable locations can produce risk assessment of forest management planning. In this paper, we examine the feasibility of the wind multiplier approach for downscaling of maximum wind speed, using 20 m spatial resolution CORINE land-use dataset and high-resolution digital elevation data. A coarse spatial resolution estimate of the 10-year return level of maximum wind speed was obtained from the ERA-Interim reanalyzed data. Using a geospatial re-mapping technique the data were downscaled to 26 meteorological station locations to represent very diverse environments. Applying a comparison, we find that the downscaled 10-year return levels represent 66 % of the observed variation among the stations examined. In addition, the spatial variation in wind-multiplier-downscaled 10-year return level wind was compared with the WAsP model-simulated wind. The heterogeneous test area was situated in northern Finland, and it was found that the major features of the spatial variation were similar, but in some locations, there were relatively large differences. The results indicate that the wind multiplier method offers a pragmatic and computationally feasible tool for identifying at a high spatial resolution those locations with the highest forest wind damage risks. It can also be used to provide the necessary wind climate information for wind damage risk model calculations, thus making it possible to estimate the probability of predicted threshold wind speeds for wind damage and consequently the probability (and amount of wind damage for certain forest stand configurations.

  9. Polar representation of centrifugal pump homologous curves

    International Nuclear Information System (INIS)

    Veloso, Marcelo Antonio; Mattos, Joao Roberto Loureiro de

    2008-01-01

    Essential for any mathematical model designed to simulate flow transient events caused by pump operations is the pump performance data. The performance of a centrifugal pump is characterized by four basic parameters: the rotational speed, the volumetric flow rate, the dynamic head, and the hydraulic torque. Any one of these quantities can be expressed as a function of any two others. The curves showing the relationships between these four variables are called the pump characteristic curves, also referred to as four-quadrant curves. The characteristic curves are empirically developed by the pump manufacturer and uniquely describe head and torque as functions of volumetric flow rate and rotation speed. Because of comprising a large amount of points, the four-quadrant configuration is not suitable for computational purposes. However, it can be converted to a simpler form by the development of the homologous curves, in which dynamic head and hydraulic torque ratios are expressed as functions of volumetric flow and rotation speed ratios. The numerical use of the complete set of homologous curves requires specification of sixteen partial curves, being eight for the dynamic head and eight for the hydraulic torque. As a consequence, the handling of homologous curves is still somewhat complicated. In solving flow transient problems that require the pump characteristic data for all the operation zones, the polar form appears as the simplest way to represent the homologous curves. In the polar method, the complete characteristics of a pump can be described by only two closed curves, one for the dynamic head and other for the hydraulic torque, both in function of a single angular coordinate defined adequately in terms of the quotient between volumetric flow ratio and rotation speed ratio. The usefulness and advantages of this alternative method are demonstrated through a practical example in which the homologous curves for a pump of the type used in the main coolant loops of a

  10. Parametric representation of centrifugal pump homologous curves

    International Nuclear Information System (INIS)

    Veloso, Marcelo A.; Mattos, Joao R.L. de

    2015-01-01

    Essential for any mathematical model designed to simulate flow transient events caused by pump operations is the pump performance data. The performance of a centrifugal pump is characterized by four basic quantities: the rotational speed, the volumetric flow rate, the dynamic head, and the hydraulic torque. The curves showing the relationships between these four variables are called the pump characteristic curves. The characteristic curves are empirically developed by the pump manufacturer and uniquely describe head and torque as functions of volumetric flow rate and rotation speed. Because of comprising a large amount of points, this configuration is not suitable for computational purposes. However, it can be converted to a simpler form by the development of the homologous curves, in which dynamic head and hydraulic torque ratios are expressed as functions of volumetric flow and rotation speed ratios. The numerical use of the complete set of homologous curves requires specification of sixteen partial curves, being eight for the dynamic head and eight for the hydraulic torque. As a consequence, the handling of homologous curves is still somewhat complicated. In solving flow transient problems that require the pump characteristic data for all the operation zones, the parametric form appears as the simplest way to deal with the homologous curves. In this approach, the complete characteristics of a pump can be described by only two closed curves, one for the dynamic head and other for the hydraulic torque, both in function of a single angular coordinate defined adequately in terms of the quotient between volumetric flow ratio and rotation speed ratio. The usefulness and advantages of this alternative method are demonstrated through a practical example in which the homologous curves for a pump of the type used in the main coolant loops of a pressurized water reactor (PWR) are transformed to the parametric form. (author)

  11. Grid Compatibility of Variable Speed Wind Turbines with Directly Coupled Synchronous Generator and Hydro-Dynamically Controlled Gearbox

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, H.; Poeller, M. [DIgSILENT GmbH, 72810 Gomaringen (Germany); Basteck, A.; Tilscher, M.; Pfister, J. [Voith Turbo GmbH and Co. KG, 74564 Crailsheim (Germany)

    2006-07-01

    This paper analyzes grid integration aspects of a new type of variable-speed wind turbine, the directly coupled synchronous generator with hydro-dynamically controlled gearbox. In contrast to existing wind generators using synchronous generators, the generator of this concept is directly connected to the AC grid, without the application of any power electronics converter. Variable speed operation of the turbine is mechanically achieved by a gear box with continuously controllable variable gear box ratio. For this purpose, a detailed dynamic model of a 2 MW wind turbine with a Voith WinDrive has been implemented using the modelling environment of the simulation software DIgSILENT PowerFactory. For investigating grid compatibility aspects of this new wind generator concept, a model of a 50 MW wind farm, with typical layout, based on 25 wind turbines of the 2 MW-class has been analyzed. This paper focuses on the compatibility of the new concept with existing connection standards, such as the E.ON grid code. Of special interest are typical stability phenomena of synchronous generators, such as transient and oscillatory stability as well as power quality issues like voltage flicker. The results of stability studies are presented and possible advantages of the new concept with special focus on offshore applications are discussed.

  12. Part load performance of air-cooled centrifugal chillers with variable speed condenser fan control

    Energy Technology Data Exchange (ETDEWEB)

    Yu, F.W.; Chan, K.T. [Department of Building Services Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China)

    2007-11-15

    Air-cooled centrifugal chillers are commonly used in commercial buildings but their performance analysis is lacking. This paper investigates the part load performance of the chillers via a thermodynamic model. The model was validated using a wide range of operating data from an existing chiller with specific settings of outdoor temperature and condensing pressure in controlling the condensing temperature. The validated model was developed specifically to ascertain the maximum coefficient of performance of chiller (COP) together with the strategy for optimizing the condensing temperature under various operating conditions. It is found that the highest COP occurs at a part load ratio (PLR) of 0.71-0.84, depending on the outdoor temperature and the control of condensing temperature, rather than at full load. Yet the chillers operating at such part load conditions will cause extra energy used for the early staging of chilled water pumps. To minimize the overall chiller plant energy consumption, it is still preferable to implement chiller sequencing based on the full load condition than on the aforementioned PLRs. The results of this paper present criteria for implementing low-energy strategies for operating air-cooled chillers satisfying a given building cooling load profile. (author)

  13. 变速变桨风力机组控制策略研究%Research on the Control Strategy for Variable Speed and Variable Pitch Wind Turbine

    Institute of Scientific and Technical Information of China (English)

    陈铁军; 汪兆财

    2012-01-01

    In order to increase the utilization efficiency of wind energy of wind turbine power generation system, and improve the quality of output electric energy, with the chaotic system theory as the core, the control structure of chaotic automation used for variable speed and variable pitch wind turbine is established. In addition, combining with fuzzy control theory, the algorithm of controller is given. The simulation of the control structure and control algorithm shows that comparing with conventional control method, the variable speed and variable pitch wind turbine with chaotic automation control structure and under control algorithm reaches predicted target, the practical control effect is excellent.%为提高风力机发电系统的风能利用效率、改善输出电能质量,针对变速变桨风力发电机组的控制问题,以混杂系统理论为核心,建立了应用于变速变桨风力机组的混杂自动机控制结构.同时,结合模糊控制理论,给出控制器的算法.通过对该控制结构和控制算法的仿真表明,与常规的控制方法相比,采用混杂自动机控制结构和控制算法控制变速变桨风力机组,既提高了风能的利用效率,又很好地改善了风力机输出电能质量,实际控制效果良好.

  14. Modelling and Design of a 3 kW Permanent Magnet Synchronous Generator suitable for Variable Speed Small Wind Turbines

    Directory of Open Access Journals (Sweden)

    Acharya Parash

    2016-01-01

    Full Text Available This paper presents the modeling and design of a 3 kW Permanent Magnet Synchronous Generator (PMSG used for a variable speed wind turbine. Initially, the PMSG is modeled in the d-q reference frame. Different optimized parameters of the generator are extracted from the design and used in simulation of the PMSG. The generator output power is matched with the power of the turbine such that the generator is not either over-sized or under-sized.

  15. A study of flux control for high-efficiency speed control of variable flux permanent magnet motor

    Directory of Open Access Journals (Sweden)

    Young Hyun Kim

    2018-05-01

    Full Text Available In this study, we evaluate the performance of permanent magnets (PMs. The efficiency of attraction in the high speed region was studied using the variable flux memory motor (VFMM. It is presented in order to analyze the magnetic characteristics of PMs, using the second quadrant plan data with re- and de-magnetization. In addition, this study focuses on the evaluation of operational characteristics relative to the magnetizing directions according to the d-axis currents, by using one of the finite element solutions. The feasibility of application for the VFMM has been experimentally demonstrated.

  16. A study of flux control for high-efficiency speed control of variable flux permanent magnet motor

    Science.gov (United States)

    Kim, Young Hyun; Lee, Seong Soo; Lee, Jung Ho

    2018-05-01

    In this study, we evaluate the performance of permanent magnets (PMs). The efficiency of attraction in the high speed region was studied using the variable flux memory motor (VFMM). It is presented in order to analyze the magnetic characteristics of PMs, using the second quadrant plan data with re- and de-magnetization. In addition, this study focuses on the evaluation of operational characteristics relative to the magnetizing directions according to the d-axis currents, by using one of the finite element solutions. The feasibility of application for the VFMM has been experimentally demonstrated.

  17. Investigation of the spatial variability and possible origins of wind-induced air pressure fluctuations responsible for pressure pumping

    Science.gov (United States)

    Mohr, Manuel; Laemmel, Thomas; Maier, Martin; Zeeman, Matthias; Longdoz, Bernard; Schindler, Dirk

    2017-04-01

    The exchange of greenhouse gases between the soil and the atmosphere is highly relevant for the climate of the Earth. Recent research suggests that wind-induced air pressure fluctuations can alter the soil gas transport and therefore soil gas efflux significantly. Using a newly developed method, we measured soil gas transport in situ in a well aerated forest soil. Results from these measurements showed that the commonly used soil gas diffusion coefficient is enhanced up to 30% during periods of strong wind-induced air pressure fluctuations. The air pressure fluctuations above the forest floor are only induced at high above-canopy wind speeds (> 5 m s-1) and lie in the frequency range 0.01-0.1 Hz. Moreover, the amplitudes of air pressure fluctuations in this frequency range show a clear quadratic dependence on mean above-canopy wind speed. However, the origin of these wind-induced pressure fluctuations is still unclear. Airflow measurements and high-precision air pressure measurements were conducted at three different vegetation-covered sites (conifer forest, deciduous forest, grassland) to investigate the spatial variability of dominant air pressure fluctuations, their origin and vegetation-dependent characteristics. At the conifer forest site, a vertical profile of air pressure fluctuations was measured and an array consisting of five pressure sensors were installed at the forest floor. At the grassland site, the air pressure measurements were compared with wind observations made by ground-based LIDAR and spatial temperature observations from a fibre-optic sensing network (ScaleX Campaign 2016). Preliminary results show that at all sites the amplitudes of relevant air pressure fluctuations increase with increasing wind speed. Data from the array measurements reveal that there are no time lags between the air pressure signals of different heights, but a time lag existed between the air pressure signals of the sensors distributed laterally on the forest floor

  18. Performance analysis of variable speed multiphase induction motor with pole phase modulation

    Directory of Open Access Journals (Sweden)

    Liu Huijuan

    2016-09-01

    Full Text Available The pole phase modulation (PPM technique is an effective method to extend speed range and torque capabilities for an integrated starter and hybrid electric vehicles applications. In this paper, the five pole-phase combination types of a multiphase induction motor (IM with 36 stator slots and 36 stator conductors are presented and compared quantitatively by using the time-stepping finite element method (TS-FEM. The 36 stator conductors of the proposed multiphase IM are fed by a 36 leg inverter and the current phase angle and amplitude of each stator conductor can be controlled independently. This paper focuses on the winding connection, the PPM technique and the performance comparative analysis of each pole-phase combination types of the proposed multiphase IM. The flux distribution, air-gap flux density, output torque, core losses and efficiency of five pole-phase combination types have been investigated.

  19. Adaptive Voltage Control Strategy for Variable-Speed Wind Turbine Connected to a Weak Network

    DEFF Research Database (Denmark)

    Abulanwar, Elsayed; Hu, Weihao; Chen, Zhe

    2016-01-01

    and smoothness at the point of connection (POC) in order to maximise the wind power penetration into such networks. Intensive simulation case studies under different network topology and wind speed ranges reveal the effectiveness of the AVC scheme to effectively suppress the POC voltage variations particularly......Significant voltage fluctuations and power quality issues pose considerable constraints on the efficient integration of remotely located wind turbines into weak networks. Besides, 3p oscillations arising from the wind shear and tower shadow effects induce further voltage perturbations during...... continuous operation. This study investigates and analyses the repercussions raised by integrating a doubly-fed induction generator wind turbine into an ac network of different parameters and very weak conditions. An adaptive voltage control (AVC) strategy is proposed to retain voltage constancy...

  20. Analysis of Disturbance Source Inducing by The Variable Speed Wind Turbine System Forced Power Oscillations

    DEFF Research Database (Denmark)

    Tan, Jin; Hu, Weihao; Wang, Xiaoru

    2015-01-01

    The main focus of forced low frequency oscillations is to analyze the disturbance source and the origin of forced oscillations. In this paper, the origin of low-frequency periodical oscillations induced by wind turbines’ mechanical power is investigated and the mechanism is studied of fluctuating...... power transfer through permanent magnet generator wind turbine system. Considering the tower shadow and the wind shear effect, the mechanical and generator coupling model is developed by PSCAD. Simulation is done to analyze the impacts on output power of operation points and mechanical fluctuation...... components. It is shown that when the oscillation frequency of tower shadow coincides with the system natural frequency, it may cause forced oscillations, whereas, the wind shear and natural wind speed fluctuation are not likely to induce forced oscillations....

  1. Experimental Study of a Novel Direct-Expansion Variable Frequency Finned Solar/Air-Assisted Heat Pump Water Heater

    Directory of Open Access Journals (Sweden)

    Jing Qin

    2018-01-01

    Full Text Available A novel direct expansion variable frequency finned solar/air-assisted heat pump water heater was fabricated and tested in the enthalpy difference lab with a solar simulator. A solar/air source evaporator-collector with an automatic lifting glass cover plate was installed on the system. The system could be operated in three modes, namely, air, solar, and dual modes. The effects of the ambient temperature, solar irradiation, compressor frequency, and operating mode on the performance of this system were studied in this paper. The experimental results show that the ambient temperature, solar irradiation, and operating mode almost have no effect on the energy consumption of the compressor. When the ambient temperature and the solar irradiation were increased, the COP was found to increase with decreasing heating time. Also, when the compressor frequency was increased, an increase in the energy consumption of the compressor and the heat gain of the evaporator were noted with a decrease in the heating time.

  2. Evaluation of different inertial control methods for variable-speed wind turbines simulated by fatigue, aerodynamic, structures and turbulence (FAST)

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiao; Gao, Wenzhong; Scholbrock, Andrew; Muljadi, Eduard; Gevorgian, Vahan; Wang, Jianhui; Yan, Weihang; Zhang, Huaguang

    2017-10-18

    To mitigate the degraded power system inertia and undesirable primary frequency response caused by large-scale wind power integration, the frequency support capabilities of variable-speed wind turbines is studied in this work. This is made possible by controlled inertial response, which is demonstrated on a research turbine - controls advanced research turbine, 3-bladed (CART3). Two distinct inertial control (IC) methods are analysed in terms of their impacts on the grids and the response of the turbine itself. The released kinetic energy in the IC methods are determined by the frequency measurement or shaped active power reference in the turbine speed-power plane. The wind turbine model is based on the high-fidelity turbine simulator fatigue, aerodynamic, structures and turbulence, which constitutes the aggregated wind power plant model with the simplified power converter model. The IC methods are implemented over the baseline CART3 controller, evaluated in the modified 9-bus and 14-bus testing power grids considering different wind speeds and different wind power penetration levels. The simulation results provide various insights on designing such kinds of ICs. The authors calculate the short-term dynamic equivalent loads and give a discussion about the turbine structural loadings related to the inertial response.

  3. Mechanical fault diagnostics for induction motor with variable speed drives using Adaptive Neuro-fuzzy Inference System

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Z. [Department of Electrical & amp; Computer Engineering, Queen' s University, Kingston, Ont. (Canada K7L 3N6); Sadeghian, A. [Department of Computer Science, Ryerson University, Toronto, Ont. (Canada M5B 2K3); Wu, B. [Department of Electrical & amp; Computer Engineering, Ryerson University, Toronto, Ont. (Canada M5B 2K3)

    2006-06-15

    A novel online diagnostic algorithm for mechanical faults of electrical machines with variable speed drive systems is presented in this paper. Using Wavelet Packet Decomposition (WPD), a set of feature coefficients, represented with different frequency resolutions, related to the mechanical faults is extracted from the stator current of the induction motors operating over a wide range of speeds. A new integrated diagnostic system for electrical machine mechanical faults is then proposed using multiple Adaptive Neuro-fuzzy Inference Systems (ANFIS). This paper shows that using multiple ANFIS units significantly reduces the scale and complexity of the system and speeds up the training of the network. The diagnostic algorithm is validated on a three-phase induction motor drive system, and it is proven to be capable of detecting rotor bar breakage and air gap eccentricity faults with high accuracy. The algorithm is applicable to a variety of industrial applications where either continuous on-line monitoring or off-line fault diagnostics is required. (author)

  4. The ORNL Modulating Heat Pump Design Tool User's Guide

    Energy Technology Data Exchange (ETDEWEB)

    Rice, C.K.

    2001-06-01

    The ORNL Modulating Heat Pump Design Tool consists of a Modulating HPDM (Heat Pump Design Model) and a parametric-analysis (contour-data generating) front-end. Collectively the program is also referred to as MODCON which is in reference to the modulating and the contour data generating capabilities. The program was developed by Oak Ridge National Laboratory for the Department of Energy to provide a publicly-available system design tool for variable- and single-speed heat pumps.

  5. The ORNL Modulating Heat Pump Design Tool -- Mark IV User's Guide

    Energy Technology Data Exchange (ETDEWEB)

    Rice, C.K.

    2001-09-27

    The ORNL Modulating Heat Pump Design Tool consists of a Modulating HPDM (Heat Pump Design Model) and a parametric-analysis (contour-data generating) front-end. Collectively the program is also referred to as MODCON which is in reference to the modulating and the contour data generating capabilities. The program was developed by Oak Ridge National Laboratory for the Department of Energy to provide a publicly-available system design tool for variable- and single-speed heat pumps.

  6. Fuzzy multivariable control of domestic heat pumps

    International Nuclear Information System (INIS)

    Underwood, C.P.

    2015-01-01

    Poor control has been identified as one of the reasons why recent field trials of domestic heat pumps in the UK have produced disappointing results. Most of the technology in use today uses a thermostatically-controlled fixed speed compressor with a mechanical expansion device. This article investigates improved control of these heat pumps through the design and evaluation of a new multivariable fuzzy logic control system utilising a variable speed compressor drive with capacity control linked through to evaporator superheat control. A new dynamic thermal model of a domestic heat pump validated using experimental data forms the basis of the work. The proposed control system is evaluated using median and extreme daily heating demand profiles for a typical UK house compared with a basic thermostatically-controlled alternative. Results show good tracking of the heating temperature and superheat control variables, reduced cycling and an improvement in performance averaging 20%. - Highlights: • A new dynamic model of a domestic heat pump is developed and validated. • A new multivariable fuzzy logic heat pump control system is developed/reported. • The fuzzy controller regulates both plant capacity and evaporator superheat degree. • Thermal buffer storage is also considered as well as compressor cycling. • The new controller shows good variable tracking and a reduction in energy of 20%.

  7. Variable-speed belt conveyor systems improve economy in operation; Drehzahlgeregelte Bandanlagen verbessern die betriebswirtschaftlichen Kennzahlen

    Energy Technology Data Exchange (ETDEWEB)

    Keller, C.; Neuffer, I.; Weber, D. [Siemens AG, Erlangen (Germany). Bereich Anlagenbau und Technische Dienstleistungen (ATD)

    1999-03-01

    Previous large conveyor system solutions were a compromise between mechanical design and electrical drive technology, usually based on slipring motors for cost reasons. Today`s power electronics systems now make it possible to use medium-voltage frequency converters in large conveyor systems. This new technology opens up design solutions with torque control that yield distinctly better behaviour under load fluctuation conditions, thereby reducing wear and tear. Experience gained from completed projects has shown that a higher-level load-dependent conveyor speed control can achieve energy savings of up to 20%, since material flows tend to be stochastic rather than constant. Maximum speed is required for short periods only and can therefore be obtained by means of field weakening, a higher gear ratio and short-time overshooting of the rated motor current. This permits the use of motors with smaller frame sizes. Furthermore, in view of the controlled torque and shorter belt runs, it is conceivable that built-in safety margins could be reduced. The solution presented here shows how a distinct improvement in cost efficiency can be attained. (orig.) [Deutsch] Bisherige Loesungen fuer grosse Bandanlagen sind ein Kompromiss zwischen mechanischer Konstruktion und elektrischer Antriebstechnik, bei der aus Kostengruenden meist Schleifringlaeufermotoren eingesetzt werden. Aufgrund der Moeglichkeiten, die die Leistungselektronik heute bietet, ist ein Einsatz von Mittelspannungsumrichtern auch auf diesem Gebiet realisierbar. Damit sind Loesungen moeglich, die besonders durch ein gefuehrtes Moment ein deutlich verbessertes Verhalten bei Momenten- oder Lastaenderungen herbeifuehren und damit eine materialschonende Betriebsweise ermoeglichen. Ausserdem hat sich bei ausgefuehrten Anlagen gezeigt, dass sich durch eine uebergeordnete foerderleistungsabhaengige Bandgeschwindigkeitsregelung auch Energie bis zu 20% einsparen laesst, da der Materialfluss nicht stetig, sondern eher

  8. Investigations dealing with variable-speed drives of belt conveyor systems; Untersuchungen an drehzahlstellbaren Antrieben von Gurtbandfoerderanlagen

    Energy Technology Data Exchange (ETDEWEB)

    Heuvel, B. van den [RWE Power AG, Technikzentrum Tagebaue/Hauptwerkstatt, Versuchsabteilung, Frechen (Germany)

    2006-04-15

    Safe and faultless operation of belt conveyor systems is a crucial factor in maintaining the availability of interlinked conveying systems employed in mining operations; the use of components with a high efficiency or low energy consumption and energy-conserving plant operation modes allow economic efficiency to be enhanced. With the power increase of single drives to 2500 kW the static design is gaining significance and - with the introduction of variable-speed conveyor drives - particular importance is also to be attached to the proper dynamic design and adjustment of the drive units. Comprehensive measurement and computational studies made of different conveyor drive units in the 900 to 2500 kW power range revealed that excitations of torsional natural frequencies caused by the drives' tooth contact frequencies were the reason for the damage that had occurred; remedial measures were developed the efficacy of which was demonstrated in practice. Moreover, investigations aimed at precautionary damage prevention are described which were performed with newly designed gears prior to the conversion of proven conveyor drives to variable-speed drive units. When designing new gears in the future, we recommend to also investigate them with regard to their dynamic behaviour in the drive train during the design phase by performing appropriate torsional vibration analyses. (orig.)

  9. able utilizando redes neuronales artificiales; UTILIZATION OF ARTIFICIAL NEURAL NETWORK IN THE SIMULATION AND CONTROL OF WIND TURBINE GENERATORS WITH VARIABLE SPEED AND VARIABLE PITCH.

    Directory of Open Access Journals (Sweden)

    Osley López González

    2011-02-01

    , considered as a whole, must be able of respond with anadequate precision and speed in response to the randomness and variability of the wind.The relationship between the wind speed, the blade pitch and the generator speed in order to produce themaximum power and also be able to limit the output power for large wind speeds is a very complicated oneand it is very difficult to find its mathematical function.In this paper, the authors, utilizing the MATLABSIMULINK toolboxes, propose representing this functional relation by means of an Artificial Neural Network(ANN. The parameters and characteristics of an existing wind turbine generator are utilized and it isdemonstrated that it is possible to use an ANN in the simulation and control of a variable speed, variablepitch wind turbine that capture the maximum power from the wind.

  10. Evaluation of the Inertial Response of Variable-Speed Wind Turbines Using Advanced Simulation: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Scholbrock, Andrew K [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Muljadi, Eduard [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Gevorgian, Vahan [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Scholbrock, Andrew K [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Wang, Xiao [Northeastern University; Gao, Wenzhong [University of Denver; Yan, Weihang [University of Denver; Wang, Jianhui [Northeastern University

    2017-08-09

    In this paper, we focus on the temporary frequency support effect provided by wind turbine generators (WTGs) through the inertial response. With the implemented inertial control methods, the WTG is capable of increasing its active power output by releasing parts of the stored kinetic energy when the frequency excursion occurs. The active power can be boosted temporarily above the maximum power points, but the rotor speed deceleration follows and an active power output deficiency occurs during the restoration of rotor kinetic energy. In this paper, we evaluate and compare the inertial response induced by two distinct inertial control methods using advanced simulation. In the first stage, the proposed inertial control methods are analyzed in offline simulation. Using an advanced wind turbine simulation program, FAST with TurbSim, the response of the researched wind turbine is comprehensively evaluated under turbulent wind conditions, and the impact on the turbine mechanical components are assessed. In the second stage, the inertial control is deployed on a real 600-kW wind turbine, the three-bladed Controls Advanced Research Turbine, which further verifies the inertial control through a hardware-in-the-loop simulation. Various inertial control methods can be effectively evaluated based on the proposed two-stage simulation platform, which combines the offline simulation and real-time hardware-in-the-loop simulation. The simulation results also provide insights in designing inertial control for WTGs.

  11. Optimal number of circulating water pumps in a nuclear power plant

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Lin [College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, Jiangsu (China); Liu, Deyou, E-mail: liudyhhuc@163.com [College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, Jiangsu (China); Zhou, Ling, E-mail: zlhhu@163.com [College of Water Conservancy and Hydropower Engineering, Hohai University, Nanjing 210098, Jiangsu (China); Wang, Feng [School of Hydraulic, Energy and Power Engineering, Yangzhou University, Yangzhou 225009, Jiangsu (China); Wang, Pei [College of Energy and Electrical Engineering, Hohai University, Nanjing 210098, Jiangsu (China)

    2015-07-15

    Highlights: • We present a novel method to optimize the number of variable speed pumps. • The economic effect of variable speed pumps number optimization is presented. • We present a novel method to optimize the number of constant speed pumps. • The proposed pumps number optimization method is more accurate than the widely used method. - Abstract: A circulating cooling system that uses variable speed pumps (VSPs) or constant-speed pumps (CSPs) as circulating water pumps (CWPs) is optimized to improve the cycle efficiency of nuclear power plants. This study focused on the optimal number of VSPs and CSPs. A novel method is proposed to optimize the number of VSPs with varying dry-bulb temperature and relative humidity, which could help decrease operation costs by $243,310 per year. This method is also used to optimize the number of CSPs and is compared with another widely used method that optimizes the number of CSPs according to the varying condenser inlet water temperature. A comparison shows that the proposed method is more accurate than the widely used method.

  12. Optimal number of circulating water pumps in a nuclear power plant

    International Nuclear Information System (INIS)

    Xia, Lin; Liu, Deyou; Zhou, Ling; Wang, Feng; Wang, Pei

    2015-01-01

    Highlights: • We present a novel method to optimize the number of variable speed pumps. • The economic effect of variable speed pumps number optimization is presented. • We present a novel method to optimize the number of constant speed pumps. • The proposed pumps number optimization method is more accurate than the widely used method. - Abstract: A circulating cooling system that uses variable speed pumps (VSPs) or constant-speed pumps (CSPs) as circulating water pumps (CWPs) is optimized to improve the cycle efficiency of nuclear power plants. This study focused on the optimal number of VSPs and CSPs. A novel method is proposed to optimize the number of VSPs with varying dry-bulb temperature and relative humidity, which could help decrease operation costs by $243,310 per year. This method is also used to optimize the number of CSPs and is compared with another widely used method that optimizes the number of CSPs according to the varying condenser inlet water temperature. A comparison shows that the proposed method is more accurate than the widely used method

  13. PLC-Based Pressure Control in Multi-Pump Applications

    Directory of Open Access Journals (Sweden)

    Vodovozov Valery

    2015-12-01

    Full Text Available The paper is devoted to the centrifugal pumps represented the most popular type of pumping equipment used in different areas. The pressure control approach for variable speed driven (VSD parallel connected centrifugal pumps is reported. The goal of the study is optimization of some quality indices, such as efficiency, consumed power, productivity, energy carrier temperature, heat irradiation, etc. One of them – efficiency – has been studied in the paper more carefully. The mathematical model of pumping process is discussed and a vector-matrix description of the multi-pump application is given. The program-based pressure control system is developed which productivity is changed by regulating the number of working pumps. The paper introduces new pressure control algorithms based on the working point estimation intended for programmable logical controllers (PLC. Experiments prove correctness of the offered methodology.

  14. Pumping characteristics of roots blower pumps for light element gases

    International Nuclear Information System (INIS)

    Hiroki, Seiji; Abe, Tetsuya; Tanzawa, Sadamitsu; Nakamura, Jun-ichi; Ohbayashi, Tetsuro

    2002-07-01

    The pumping speed and compression ratio of the two-stage roots blower pumping system were measured for light element gases (H 2 , D 2 and He) and for N 2 , in order to assess validity of the ITER torus roughing system as an ITER R and D task (T234). The pumping system of an Edwards EH1200 (nominal pumping speed of 1200 m 3 /s), two EH250s (ibid. 250 m 3 /s) and a backing pump (ibid. 100 m 3 /s) in series connection was tested under PNEUROP standards. The maximum pumping speeds of the two-stage system for D 2 and N 2 were 1200 and 1300 m 3 /h, respectively at 60 Hz, which satisfied the nominal pumping speed. These experimental data support the design validity of the ITER torus roughing system. (author)

  15. Optimal control of a variable spin speed CMG system for space vehicles. [Control Moment Gyros

    Science.gov (United States)

    Liu, T. C.; Chubb, W. B.; Seltzer, S. M.; Thompson, Z.

    1973-01-01

    Many future NASA programs require very high accurate pointing stability. These pointing requirements are well beyond anything attempted to date. This paper suggests a control system which has the capability of meeting these requirements. An optimal control law for the suggested system is specified. However, since no direct method of solution is known for this complicated system, a computation technique using successive approximations is used to develop the required solution. The method of calculus of variations is applied for estimating the changes of index of performance as well as those constraints of inequality of state variables and terminal conditions. Thus, an algorithm is obtained by the steepest descent method and/or conjugate gradient method. Numerical examples are given to show the optimal controls.

  16. Chapter 18: Variable Frequency Drive Evaluation Protocol. The Uniform Methods Project: Methods for Determining Energy Efficiency Savings for Specific Measures

    Energy Technology Data Exchange (ETDEWEB)

    Romberger, Jeff [SBW Consulting, Inc., Bellevue, WA (United States)

    2017-06-21

    An adjustable-speed drive (ASD) includes all devices that vary the speed of a rotating load, including those that vary the motor speed and linkage devices that allow constant motor speed while varying the load speed. The Variable Frequency Drive Evaluation Protocol presented here addresses evaluation issues for variable-frequency drives (VFDs) installed on commercial and industrial motor-driven centrifugal fans and pumps for which torque varies with speed. Constant torque load applications, such as those for positive displacement pumps, are not covered by this protocol.

  17. Analysis of a variable speed air conditioner considering the R-290/POE ISO 22 mixture effect

    International Nuclear Information System (INIS)

    Ribeiro, Guilherme B.; Barbosa, Jader R.

    2016-01-01

    Highlights: • A numerical model that considers the oil-refrigerant mixture effect is proposed. • In order to compare the model, an air conditioner calorimeter was constructed. • The system was evaluated under oil circulation ratios between 1 and 7%. • The presence of oil resulted in a significant SEER deterioration (around 69%). - Abstract: Air-conditioning applications using propane (R-290) have several environmental and thermodynamic advantages over more commonly used refrigerants, such as R-410A and R-22. This paper presents the development of a mathematical model for variable capacity air conditioning systems that use R-290/POE ISO 22 as refrigerant/lubricant. The thermodynamic performance of the refrigeration system is evaluated in terms of the SEER (Seasonal Energy Efficiency Ratio). The thermodynamic properties of the refrigerant/lubricant mixture were obtained from a departure-function approach using the Peng-Robinson equation of state. The effect of the oil on the condenser and evaporator heat transfer coefficients and pressure drops was also taken into account. Sub-models were developed for each component of the air conditioning system, including the connecting lines and the scroll compressor. Furthermore, an air conditioner experimental calorimeter was constructed and tested in order to validate the proposed model.

  18. Experimental enhancement of fuzzy fractional order PI+I controller of grid connected variable speed wind energy conversion system

    International Nuclear Information System (INIS)

    Beddar, Antar; Bouzekri, Hacene; Babes, Badreddine; Afghoul, Hamza

    2016-01-01

    Highlights: • Fuzzy fractional order PI+I for wind energy conversion system is developed. • Investigation of the control methods performances under wind and load variations. • PSO algorithm with frequency method are used for parameters tuning. • Experimental results are presented. - Abstract: In this paper, fuzzy fractional order PI+I (FFOPI+I) controller for grid connected Variable Speed Wind Energy Conversion System (VS-WECS) is proposed. The FFOPI+I controller is applied to control a Permanent Magnet Synchronous Generator (PMSG) connected to the grid and nonlinear load through a back-to-back AC-DC-AC PWM converter. The control strategy of the Machine Side Converter (MSC) aims, at first, to extract a maximum power under fluctuating wind speed. Then, the Grid Side Converter (GSC) is controlled to improve the power quality and ensure sinusoidal current in the grid side. The FFOPI+I controller implements a Fuzzy Logic Controller (FLC) in parallel with Fractional Order PI (FOPI) and conventional PI controllers by having a commune proportional gain. The FLC changes the integral gains at runtime. The initial parameters of the FFOPI+I controller were calculated using a frequency method to create a search space then the PSO algorithm is used to select the optimal parameters. To evaluate the performance of the proposed controller in steady and transient states, an experimental test bench has been built in laboratory using dSPACE1104 card. The experimental results demonstrate the effectiveness and feasibility of the FFOPI+I over FOPI and conventional PI controllers by realizing maximum power extraction and improving the grid-side power factor for a wide range of wind speed.

  19. Complementary Aerodynamic Performance Datasets for Variable Speed Power Turbine Blade Section from Two Independent Transonic Turbine Cascades

    Science.gov (United States)

    Flegel, Ashlie B.; Welch, Gerard E.; Giel, Paul W.; Ames, Forrest E.; Long, Jonathon A.

    2015-01-01

    Two independent experimental studies were conducted in linear cascades on a scaled, two-dimensional mid-span section of a representative Variable Speed Power Turbine (VSPT) blade. The purpose of these studies was to assess the aerodynamic performance of the VSPT blade over large Reynolds number and incidence angle ranges. The influence of inlet turbulence intensity was also investigated. The tests were carried out in the NASA Glenn Research Center Transonic Turbine Blade Cascade Facility and at the University of North Dakota (UND) High Speed Compressible Flow Wind Tunnel Facility. A large database was developed by acquiring total pressure and exit angle surveys and blade loading data for ten incidence angles ranging from +15.8deg to -51.0deg. Data were acquired over six flow conditions with exit isentropic Reynolds number ranging from 0.05×106 to 2.12×106 and at exit Mach numbers of 0.72 (design) and 0.35. Flow conditions were examined within the respective facility constraints. The survey data were integrated to determine average exit total-pressure and flow angle. UND also acquired blade surface heat transfer data at two flow conditions across the entire incidence angle range aimed at quantifying transitional flow behavior on the blade. Comparisons of the aerodynamic datasets were made for three "match point" conditions. The blade loading data at the match point conditions show good agreement between the facilities. This report shows comparisons of other data and highlights the unique contributions of the two facilities. The datasets are being used to advance understanding of the aerodynamic challenges associated with maintaining efficient power turbine operation over a wide shaft-speed range.

  20. An alternative arrangement of metered dosing fluid using centrifugal pump

    Science.gov (United States)

    Islam, Md. Arafat; Ehsan, Md.

    2017-06-01

    Positive displacement dosing pumps are extensively used in various types of process industries. They are widely used for metering small flow rates of a dosing fluid into a main flow. High head and low controllable flow rates make these pumps suitable for industrial flow metering applications. However their pulsating flow is not very suitable for proper mixing of fluids and they are relatively more expensive to buy and maintain. Considering such problems, alternative techniques to control the fluid flow from a low cost centrifugal pump is practiced. These include - throttling, variable speed drive, impeller geometry control and bypass control. Variable speed drive and impeller geometry control are comparatively costly and the flow control by throttling is not an energy efficient process. In this study an arrangement of metered dosing flow was developed using a typical low cost centrifugal pump using bypass flow technique. Using bypass flow control technique a wide range of metered dosing flows under a range of heads were attained using fixed pump geometry and drive speed. The bulk flow returning from the system into the main tank ensures better mixing which may eliminate the need of separate agitators. Comparative performance study was made between the bypass flow control arrangement of centrifugal pump and a diaphragm type dosing pump. Similar heads and flow rates were attainable using the bypass control system compared to the diaphragm dosing pump, but using relatively more energy. Geometrical optimization of the centrifugal pump impeller was further carried out to make the bypass flow arrangement more energy efficient. Although both the systems run at low overall efficiencies but the capital cost could be reduced by about 87% compared to the dosing pump. The savings in capital investment and lower maintenance cost very significantly exceeds the relatively higher energy cost of the bypass system. This technique can be used as a cost effective solution for

  1. Cutting-in control of the variable speed constant frequency wind power generator based on internal model controller

    Energy Technology Data Exchange (ETDEWEB)

    Guo Jindong; Xu Honghua; Zhao Dongli [Inst. of Electrical Engineering, CAS, BJ (China)

    2008-07-01

    The no-impact-current cutting-in-network control is the key of variable speed constant frequency (VSCF) wind power control system. Based on the stator flux linkage oriented control theory of doubly fed induction generator (DFIG), the field-oriented vector control technique and the internal model controller (IMC) are transplanted into the voltage control of DFIG and a novel cutting-in control strategy is obtained. The strategy does not need the exact inductor generator model, and has perfect performance without overshoot. The structure of the controller is simple, and the only parameter to be adjusted is directly related to system performance, so the strategy is easy to realize. Finally the strategy is studied by simulation using Matlab, the results of the simulation show that the control strategy can effectively control the stator voltage. (orig.)

  2. Cooling and Heating Season Impacts of Right-Sizing of Fixed- and Variable-Capacity Heat Pumps With Attic and Indoor Ductwork

    Energy Technology Data Exchange (ETDEWEB)

    Cummings, James [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States); Withers, Charles [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States); Kono, Jamie [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States)

    2015-06-01

    A new generation of central, ducted variable-capacity heat pump systems has come on the market, promising very high cooling and heating efficiency. They are controlled differently than standard fixed-capacity systems. Instead of cycling on at full capacity and then cycling off when the thermostat is satisfied, they vary their cooling and heating output over a wide range (approximately 40% - 118% of nominal full capacity), thus staying 'on' for 60% - 100% more hours per day compared to fixed -capacity systems. Experiments in this research examined the performance of 2-ton and 3-ton fixed- and variable-capacity systems and the impacts of system oversizing.

  3. 30 min of treadmill walking at self-selected speed does not increase gait variability in independent elderly.

    Science.gov (United States)

    Da Rocha, Emmanuel S; Kunzler, Marcos R; Bobbert, Maarten F; Duysens, Jacques; Carpes, Felipe P

    2018-06-01

    Walking is one of the preferred exercises among elderly, but could a prolonged walking increase gait variability, a risk factor for a fall in the elderly? Here we determine whether 30 min of treadmill walking increases coefficient of variation of gait in elderly. Because gait responses to exercise depend on fitness level, we included 15 sedentary and 15 active elderly. Sedentary participants preferred a lower gait speed and made smaller steps than the actives. Step length coefficient of variation decreased ~16.9% by the end of the exercise in both the groups. Stride length coefficient of variation decreased ~9% after 10 minutes of walking, and sedentary elderly showed a slightly larger step width coefficient of variation (~2%) at 10 min than active elderly. Active elderly showed higher walk ratio (step length/cadence) than sedentary in all times of walking, but the times did not differ in both the groups. In conclusion, treadmill gait kinematics differ between sedentary and active elderly, but changes over time are similar in sedentary and active elderly. As a practical implication, 30 min of walking might be a good strategy of exercise for elderly, independently of the fitness level, because it did not increase variability in step and stride kinematics, which is considered a risk of fall in this population.

  4. New and future heat pump technologies

    Science.gov (United States)

    Creswick, F. A.

    It is not possible to say for sure what future heat pumps will look like, but there are some interesting possibilities. In the next five years, we are likely to see US heat pumps with two kinds of innovations: capacity modulation and charge control. Capacity modulation will be accomplished by variable-speed compressor motors. The objective of charge control is to keep the refrigerant charge in the system where it belongs for best performance; there are probably many ways to accomplish this. Charge control will improve efficiency and durability; capacity modulation will further improve efficiency and comfort. The Stirling cycle heat pump has several interesting advantages, but it is farther out in time. At present, we don't know how to make it as efficient as the conventional vapor-compression heat pump. Electric utility people should be aware that major advances are being made in gas-fired heat pumps which could provide strong competition in the future. However, even a gas-fired heat pump has a substantial auxiliary electric power requirement. The resources needed to develop advanced heat pumps are substantial and foreign competition will be intense. It will be important for utilities, manufacturers, and the federal government to work in close cooperation.

  5. Too much or too little step width variability is associated with a fall history in older persons who walk at or near normal gait speed

    Directory of Open Access Journals (Sweden)

    Newman Anne B

    2005-07-01

    Full Text Available Abstract Background Decreased gait speed and increased stride time, stride length, double support time, and stance time variability have consistently been associated with falling whereas step width variability has not been strongly related to falls. The purpose was to examine the linear and nonlinear associations between gait variability and fall history in older persons and to examine the influence of gait speed. Methods Gait characteristics and fall history were obtained in 503 older adults (mean age = 79; 61% female participating in the Cardiovascular Health Study who could ambulate independently. Gait characteristics were recorded from two trials on a 4 meter computerized walkway at the subject's self-selected walking speed. Gait variability was calculated as the coefficient of variation. The presence of a fall in the past 12 months was determined by interview. The nonlinear association between gait variability and fall history was examined using a simple three level classification derived from the distribution of the data and from literature based cut-points. Multivariate logistic regression was used to examine the association between step width variability (extreme or moderate and fall history stratifying by gait speed (1.0 m/s and controlling for age and gender. Results Step length, stance time, and step time variability did not differ with respect to fall history (p > .33. Individuals with extreme step width variability (either low or high step width variability were more likely to report a fall in the past year than individuals with moderate step width variability. In individuals who walked ≥ 1.0 m/s (n = 281, after controlling for age, gender, and gait speed, compared to individuals with moderate step width variability individuals with either low or high step width variability were more likely to have fallen in the past year (OR and 95% CI 4.38 [1.79–10.72]. The association between step width variability and fall history was not

  6. Low Wind Speed Turbine Project Phase II: The Application of Medium-Voltage Electrical Apparatus to the Class of Variable Speed Multi-Megawatt Low Wind Speed Turbines; 15 June 2004--30 April 2005

    Energy Technology Data Exchange (ETDEWEB)

    Erdman, W.; Behnke, M.

    2005-11-01

    Kilowatt ratings of modern wind turbines have progressed rapidly from 50 kW to 1,800 kW over the past 25 years, with 3.0- to 7.5-MW turbines expected in the next 5 years. The premise of this study is simple: The rapid growth of wind turbine power ratings and the corresponding growth in turbine electrical generation systems and associated controls are quickly making low-voltage (LV) electrical design approaches cost-ineffective. This report provides design detail and compares the cost of energy (COE) between commercial LV-class wind power machines and emerging medium-voltage (MV)-class multi-megawatt wind technology. The key finding is that a 2.5% reduction in the COE can be achieved by moving from LV to MV systems. This is a conservative estimate, with a 3% to 3.5% reduction believed to be attainable once purchase orders to support a 250-turbine/year production level are placed. This evaluation considers capital costs as well as installation, maintenance, and training requirements for wind turbine maintenance personnel. Subsystems investigated include the generator, pendant cables, variable-speed converter, and padmount transformer with switchgear. Both current-source and voltage-source converter/inverter MV topologies are compared against their low-voltage, voltage-source counterparts at the 3.0-, 5.0-, and 7.5-MW levels.

  7. The Contribution of Compressional Magnetic Pumping to the Energization of the Earth's Outer Electron Radiation Belt During High-Speed Stream-Driven Storms

    Science.gov (United States)

    Borovsky, Joseph E.; Horne, Richard B.; Meredith, Nigel P.

    2017-12-01

    Compressional magnetic pumping is an interaction between cyclic magnetic compressions and pitch angle scattering with the scattering acting as a catalyst to allow the cyclic compressions to energize particles. Compressional magnetic pumping of the outer electron radiation belt at geosynchronous orbit in the dayside magnetosphere is analyzed by means of computer simulations, wherein solar wind compressions of the dayside magnetosphere energize electrons with electron pitch angle scattering by chorus waves and by electromagnetic ion cyclotron (EMIC) waves. The magnetic pumping is found to produce a weak bulk heating of the electron radiation belt, and it also produces an energetic tail on the electron energy distribution. The amount of energization depends on the robustness of the solar wind compressions and on the amplitude of the chorus and/or EMIC waves. Chorus-catalyzed pumping is better at energizing medium-energy (50-200 keV) electrons than it is at energizing higher-energy electrons; at high energies (500 keV-2 MeV) EMIC-catalyzed pumping is a stronger energizer. The magnetic pumping simulation results are compared with energy diffusion calculations for chorus waves in the dayside magnetosphere; in general, compressional magnetic pumping is found to be weaker at accelerating electrons than is chorus-driven energy diffusion. In circumstances when solar wind compressions are robust and when EMIC waves are present in the dayside magnetosphere without the presence of chorus, EMIC-catalyzed magnetic pumping could be the dominant energization mechanism in the dayside magnetosphere, but at such times loss cone losses will be strong.

  8. Global design of a reversible air/water heat pump with variable power for the residential sector; Conception globale d'une pompe a chaleur air/eau inversable a puissance variable pour le secteur residentiel

    Energy Technology Data Exchange (ETDEWEB)

    Flach-Malaspina, N.

    2004-10-15

    Variable power is one of the means to improve the seasonal energy efficiency of heat pump space heating systems. The dual compressors technology is energetically efficient and is available in Europe. The main results of this work are: 1 - the identification of the origin of cycling losses in heating and cooling mode of existing mono-compressor air/water systems. The standby consumption of the heat pump is the only element which can efficiently contribute to reduce the energy losses at partial load. 2 - The quantification of the energy gains by adapting the dual compressors technology to a prototype of reference heat pump. 3 - A dynamic model of calculation of the seasonal coefficient of performance has been developed. 4 - The optimization of compressors operation and of the unfreezing system has permitted to increase the seasonal coefficient of performance from 14.7% to 18.6% with respect to the outdoor temperature. To carry out this study, design, experimental and modeling works have been done. The design of a heat pump fitted with two compressors has required the development of a new partial load testing bench. The several experimental and standardized tests have permitted to characterize an existing heat pump and a dual compressor heat pump whatever the operation mode and the outdoor climate. The dynamical model obtained has permitted to optimize the energy efficiency of the system thanks to a better management of the unfreezing system and to a proper regulation of the compressors. Some ways of improvement concern the dimensioning of compressors and the management of exchangers flow rates for an additional improvement of seasonal coefficients of performance. (J.S.)

  9. Induction Motors Most Efficient Operation Points in Pumped Storage Systems

    DEFF Research Database (Denmark)

    Busca-Forcos, Andreea; Marinescu, Corneliu; Busca, Cristian

    2015-01-01

    A clear focus is nowadays on developing and improving the energy storage technologies. Pumped storage is a well-established one, and is capable of enhancing the integration of renewable energy sources. Pumped storage has an efficiency between 70-80%, and each of its elements affects it. Increased...... efficiency is desired especially when operating with renewable energy systems, which present low energy conversion factor (up to 50% - performance coefficient for wind turbines, and efficiency up to 40% for photovoltaic systems). In this paper the most efficient operation points of the induction motors...... in pumped storage systems are established. The variable speed operation of the pumped storage systems and motor loading conditions for pump applications have been the key factors for achieving the purpose of the paper....

  10. Effects of central nervous system drugs on driving: speed variability versus standard deviation of lateral position as outcome measure of the on-the-road driving test.

    Science.gov (United States)

    Verster, Joris C; Roth, Thomas

    2014-01-01

    The on-the-road driving test in normal traffic is used to examine the impact of drugs on driving performance. This paper compares the sensitivity of standard deviation of lateral position (SDLP) and SD speed in detecting driving impairment. A literature search was conducted to identify studies applying the on-the-road driving test, examining the effects of anxiolytics, antidepressants, antihistamines, and hypnotics. The proportion of comparisons (treatment versus placebo) where a significant impairment was detected with SDLP and SD speed was compared. About 40% of 53 relevant papers did not report data on SD speed and/or SDLP. After placebo administration, the correlation between SDLP and SD speed was significant but did not explain much variance (r = 0.253, p = 0.0001). A significant correlation was found between ΔSDLP and ΔSD speed (treatment-placebo), explaining 48% of variance. When using SDLP as outcome measure, 67 significant treatment-placebo comparisons were found. Only 17 (25.4%) were significant when SD speed was used as outcome measure. Alternatively, for five treatment-placebo comparisons, a significant difference was found for SD speed but not for SDLP. Standard deviation of lateral position is a more sensitive outcome measure to detect driving impairment than speed variability.

  11. Cryosorption vacuum pumping under fusion reactor conditions

    International Nuclear Information System (INIS)

    Watson, J.S.; Fisher, P.W.

    1977-01-01

    Experiments are in progress on cryosorption pumping using a double-chevron pump with a molecular sieve pumping surface. Studies have been made with hydrogen, deuterium, helium, and deuterium-helium at 10 -7 to 3 x 10 -3 torr. Steady pumping speeds were observed for deuterium; above 10 -4 torr the speed increased with pressure until runaway occurred. At less than 10 -6 torr and low panel loading, hydrogen pumping speeds resemble those for deuterium. At higher pressures, the pump can function by condensation or sorption, and unsteady speeds are observed. Helium pumping is always by sorption, but regions of instability have been observed and defined. Deuterium-helium pumping tests showed that deuterium condensation on the panels prevents cryosorption of helium; however, compound pumps with separate panels for helium and hydrogen will be satisfactory

  12. Utility-scale variable-speed wind turbines using a doubly-fed generator with a soft-switching power converter

    Energy Technology Data Exchange (ETDEWEB)

    Weigand, C.H.; Lauw, H.K.; Marckx, D.A. [Electronic Power Conditioning, Inc., Corvallis, OR (United States)

    1996-12-31

    Utility-scale wind turbines operating at variable RPM have been studied for a considerable period of time. Whereas the increase in energy output originally has been considered the principal benefit of variable-speed operation, the ability to tightly control the drive-train torque by electronic means is becoming another very important cost factor, especially for turbine ratings above 500 kilowatts. This cost benefit becomes even more significant as optimum turbine ratings today are approaching (and surpassing) 1 Megawatt. Having identified the benefits for the turbine, the designer is confronted with the task of finding the most cost-effective variable-speed generation system which allows him to make use of the benefits, yet does not introduce well-known electrical problems associated with state-of-the-art variable-speed generator controls, such as drastically reduced generator winding life, excessive harmonics on the utility, and poor utility power factor. This paper will indicate that for high-power (> 500 kW), utility-scale wind turbines a doubly-fed generator system in connection with a soft-switching resonant power converter is the least-cost variable-speed generation system offering all of the desired benefits, yet avoids the introduction of the potential electrical problems stated above. 3 refs., 3 figs., 1 tab.

  13. Validation of Generic Models for Variable Speed Operation Wind Turbines Following the Recent Guidelines Issued by IEC 61400-27

    Directory of Open Access Journals (Sweden)

    Andrés Honrubia-Escribano

    2016-12-01

    Full Text Available Considerable efforts are currently being made by several international working groups focused on the development of generic, also known as simplified or standard, wind turbine models for power system stability studies. In this sense, the first edition of International Electrotechnical Commission (IEC 61400-27-1, which defines generic dynamic simulation models for wind turbines, was published in February 2015. Nevertheless, the correlations of the IEC generic models with respect to specific wind turbine manufacturer models are required by the wind power industry to validate the accuracy and corresponding usability of these standard models. The present work conducts the validation of the two topologies of variable speed wind turbines that present not only the largest market share, but also the most technological advances. Specifically, the doubly-fed induction machine and the full-scale converter (FSC topology are modeled based on the IEC 61400-27-1 guidelines. The models are simulated for a wide range of voltage dips with different characteristics and wind turbine operating conditions. The simulated response of the IEC generic model is compared to the corresponding simplified model of a wind turbine manufacturer, showing a good correlation in most cases. Validation error sources are analyzed in detail, as well. In addition, this paper reviews in detail the previous work done in this field. Results suggest that wind turbine manufacturers are able to adjust the IEC generic models to represent the behavior of their specific wind turbines for power system stability analysis.

  14. Fault-Ride through Strategy for Permanent-Magnet Synchronous Generators in Variable-Speed Wind Turbines

    Directory of Open Access Journals (Sweden)

    Mohamed Abdelrahem

    2016-12-01

    Full Text Available Currently, the electric power production by wind energy conversion systems (WECSs has increased significantly. Consequently, wind turbine (WT generators are requested to fulfill the grid code (GC requirements stated by network operators. In case of grid faults/voltage dips, a mismatch between the generated active power from the wind generator and the active power delivered to the grid is produced. The conventional approach is using a braking chopper (BC in the DC-link to dissipate this active power. This paper proposes a fault-ride through (FRT strategy for variable-speed WECSs based on permanent magnet synchronous generators (PMSGs. The proposed strategy exploits the rotor inertia of the WECS (inertia of the WT and PMSG to store the surplus active power during the grid faults/voltage dips. Thus, no additional hardware components are requested. Furthermore, a direct model predictive control (DMPC scheme for the PMSG is proposed in order to enhance the dynamic behavior of the WECS. The behavior of the proposed FRT strategy is verified and compared with the conventional BC approach for all the operation conditions by simulation results. Finally, the simulation results confirm the feasibility of the proposed FRT strategy.

  15. Application of a compressible flow solver and barotropic cavitation model for the evaluation of the suction head in a low specific speed centrifugal pump impeller channel

    International Nuclear Information System (INIS)

    Limbach, P; Müller, T; Skoda, R

    2015-01-01

    Commonly, for the simulation of cavitation in centrifugal pumps incompressible flow solvers with VOF kind cavitation models are applied. Since the source/sink terms of the void fraction transport equation are based on simplified bubble dynamics, empirical parameters may need to be adjusted to the particular pump operating point. In the present study a barotropic cavitation model, which is based solely on thermodynamic fluid properties and does not include any empirical parameters, is applied on a single flow channel of a pump impeller in combination with a time-explicit viscous compressible flow solver. The suction head curves (head drop) are compared to the results of an incompressible implicit standard industrial CFD tool and are predicted qualitatively correct by the barotropic model. (paper)

  16. The New S-RAM Air Variable Compressor/Expander for Heat Pump and Waste Heat to Power Application

    Energy Technology Data Exchange (ETDEWEB)

    Dehoff, Ryan R [ORNL; Jestings, Lee [S-RAM Dynamics; Conde, Ricardo [S-RAM Dynamics

    2016-05-23

    S-RAM Dynamics (S-RAM) has designed an innovative heat pump system targeted for commercial and industrial applications. This new heat pump system is more efficient than anything currently on the market and utilizes air as the refrigerant instead of hydrofluorocarbon (HFC) refrigerants, leading to lower operating costs, minimal environmental costs or concerns, and lower maintenance costs. The heat pumps will be manufactured in the United States. This project was aimed at determining the feasibility of utilizing additive manufacturing to make the heat exchanger device for the new heat pump system. ORNL and S-RAM Dynamics collaborated on determining the prototype performance and subsequently printing of the prototype using additive manufacturing. Complex heat exchanger designs were fabricated using the Arcam electron beam melting (EBM) powder bed technology using Ti-6Al-4V material. An ultrasonic welding system was utilized in order to remove the powder from the small openings of the heat exchanger. The majority of powder in the small chambers was removed, however, the amount of powder remaining in the heat exchanger was a function of geometry. Therefore, only certain geometries of heat exchangers could be fabricated. SRAM Dynamics evaluated a preliminary heat exchanger design. Although the results of the additive manufacturing of the heat exchanger were not optimum, a less complex geometry was demonstrated. A sleeve valve was used as a demonstration piece, as engine designs from S-RAM Dynamics require the engine to have a very high density. Preliminary designs of this geometry were successfully fabricated using the EBM technology.

  17. Transient Simulation Study of Slip-Frequency Vector Control for Variable Speed Doubly-Fed Brushless Motor with Magnetic Barrier Rotor

    Directory of Open Access Journals (Sweden)

    Jingxiong ZHANG

    2014-01-01

    Full Text Available In this paper, a transient simulation model of a variable speed doubly fed brushless motor (DFBM using back-to-back converter is described. Based on analysis of rotor flux oriented vector control theory of doubly fed induction motor, the control of the currents in DFBM that produce the magnetic flux and the torque is achieved by a digital controller, the speed is regulated by a PI controller which is tuned by a genetic algorithm. According to the state equation of DFBM and the control schemes, the system simulation module is established in MATLAB/ SIMULINK. An extensive simulation study is performed to examine the control characteristics of the machine-side converter under different operation conditions in variable-speed DFBM driver system.

  18. METHOD FOR OPTIMIZING THE ENERGY OF PUMPS

    NARCIS (Netherlands)

    Skovmose Kallesøe, Carsten; De Persis, Claudio

    2013-01-01

    The device for energy-optimization on operation of several centrifugal pumps controlled in rotational speed, in a hydraulic installation, begins firstly with determining which pumps as pilot pumps are assigned directly to a consumer and which pumps are hydraulically connected in series upstream of

  19. Test of a cryogenic helium pump

    International Nuclear Information System (INIS)

    Lue, J.W.; Miller, J.R.; Walstrom, P.L.; Herz, W.

    1981-01-01

    The design of a cryogenic helium pump for circulating liquid helium in a magnet and the design of a test loop for measuring the pump performance in terms of mass flow vs pump head at various pump speeds are described. A commercial cryogenic helium pump was tested successfully. Despite flaws in the demountable connections, the piston pump itself has performed satisfactorily. A helium pump of this type is suitable for the use of flowing supercritical helium through Internally Cooled Superconductor (ICS) magnets. It has pumped supercritical helium up to 7.5 atm with a pump head up to 2.8 atm. The maximum mass flow rate obtained was about 16 g/s. Performance of the pump was degraded at lower pumping speeds

  20. LMR [liquid metal reactor] centrifugal pump coastdowns

    International Nuclear Information System (INIS)

    Dunn, F.E.; Malloy, D.J.

    1987-01-01

    A centrifugal pump model which describes the interrelationships of the pump discharge flowrate, pump speed, shaft torque and dynamic head has been implemented based upon existing models. Specifically, the pump model is based upon the dimensionless-homologous pump theory of Wylie and Streeter. Given data from a representative pump, homologous theory allows one to predict the transient characteristics of similarly sized pumps. This homologous pump model has been implemented into both the one-dimensional SASSYS-1 systems analysis code and the three-dimensional COMMIX-1A code. Comparisons have been made both against other pump models (CRBR) and actual pump coastdown data (EBR-II and FFTF). Agreement with this homologous pump model has been excellent. Additionally, these comparisons indicate the validity of applying the medium size pump data of Wylie and Streeter to a range of typical LMR centrifugal pumps

  1. Making effective use of rod pumping systems in coalbed methane applications

    Energy Technology Data Exchange (ETDEWEB)

    Crivello, A. [eProduction Solutions Inc., Kingwood, TX (United States)

    2003-07-01

    The advantages of optimizing coalbed methane (CBM) operations are increased production, reduced expenses, improved efficiency, and better inventory. The author discussed the CBM production cycle and the possible artificial lift options, including electric submersible pump (ESP), plunger lift, primary coolant pump (PCP), and reciprocating rod lift. The presentation focused on the rod lift, as it represents a low to moderate capital expenditure, has good system efficiency, an excellent fluid volume range, an excellent salvage value, excellent familiarity with equipment, and has readily available parts and service. The major disadvantage of the rod lift is that the fixed operating range does not adapt to changing reservoir characteristics. A comparison between the rod pump controller and the variable speed drive was presented. The well can be operated at or near the pumped off condition with variable speed drives with rod pumping intelligence. The author provided a closer examination of the variable frequency drive and the vector flux drive. The presentation also included a discussion of prime movers, drive and inclinometer, gearbox loading, rod load limiter, and dynamometer cards. Three case studies were presented: CSW1, CSW2, and CSW3. It was concluded that wells must be kept pumping, and that a Flux Vector Drive should be used along with an NEMA B motor and properly sized pumping unit and pump. tabs., figs.

  2. Building America Case Study: Impact of Improved Duct Insulation on Fixed-Capacity (SEER 13) and Variable-Capacity (SEER 22) Heat Pumps, Cocoa, Florida

    Energy Technology Data Exchange (ETDEWEB)

    2017-04-01

    A new generation of central, ducted variable-capacity heat pump systems has come on the market, promising very high cooling and heating efficiency. Instead of cycling on at full capacity and then cycling off when the thermostat is satisfied, they vary their cooling and heating output over a wide range (approximately 40 to 118% of nominal full capacity); thus, staying 'on' for 60% to 100% more hours per day compared to fixed-capacity systems. Current Phase 4 experiments in an instrumented lab home with simulated occupancy evaluate the impact of duct R-value enhancement on the overall operating efficiency of the variable-capacity system compared to the fixed-capacity system.

  3. Maximum Power Point Tracking in Variable Speed Wind Turbine Based on Permanent Magnet Synchronous Generator Using Maximum Torque Sliding Mode Control Strategy

    Institute of Scientific and Technical Information of China (English)

    Esmaeil Ghaderi; Hossein Tohidi; Behnam Khosrozadeh

    2017-01-01

    The present study was carried out in order to track the maximum power point in a variable speed turbine by minimizing electromechanical torque changes using a sliding mode control strategy.In this strategy,fhst,the rotor speed is set at an optimal point for different wind speeds.As a result of which,the tip speed ratio reaches an optimal point,mechanical power coefficient is maximized,and wind turbine produces its maximum power and mechanical torque.Then,the maximum mechanical torque is tracked using electromechanical torque.In this technique,tracking error integral of maximum mechanical torque,the error,and the derivative of error are used as state variables.During changes in wind speed,sliding mode control is designed to absorb the maximum energy from the wind and minimize the response time of maximum power point tracking (MPPT).In this method,the actual control input signal is formed from a second order integral operation of the original sliding mode control input signal.The result of the second order integral in this model includes control signal integrity,full chattering attenuation,and prevention from large fluctuations in the power generator output.The simulation results,calculated by using MATLAB/m-file software,have shown the effectiveness of the proposed control strategy for wind energy systems based on the permanent magnet synchronous generator (PMSG).

  4. Pumping behavior of sputtering ion pump

    Energy Technology Data Exchange (ETDEWEB)

    Chou, T.S.; Bittner, J.; Schuchman, J.

    1991-12-31

    To optimize the design of a distributed ion pump (DIP) for the Superconducting X-Ray Lithography Source (SXLS) the stability of the rotating electron cloud at very high magnetic field beyond transition, must be re-examined. In this work the pumping speed and frequency spectrum of a DIP at various voltages (1 to 10 KV) and various magnetic fields (0.1 to 4 Tesla) are measured. Three cell diameters 10 mm, 5 mm and 2.5 mm, each 8 mm long, and with 3 or 4 mm gaps between anode and cathode are investigated. In this study both the titanium cathodes and the stainless steel anode plates are perforated with holes comparable in size to the anode cell diameters. Only the partially saturated pumping behavior is under investigation. The ultimate pressure and conditioning of the pump will be investigated at a later date when the stability criterion for the electron cloud is better understood.

  5. Pumping behavior of sputtering ion pump

    Energy Technology Data Exchange (ETDEWEB)

    Chou, T.S.; Bittner, J.; Schuchman, J.

    1991-01-01

    To optimize the design of a distributed ion pump (DIP) for the Superconducting X-Ray Lithography Source (SXLS) the stability of the rotating electron cloud at very high magnetic field beyond transition, must be re-examined. In this work the pumping speed and frequency spectrum of a DIP at various voltages (1 to 10 KV) and various magnetic fields (0.1 to 4 Tesla) are measured. Three cell diameters 10 mm, 5 mm and 2.5 mm, each 8 mm long, and with 3 or 4 mm gaps between anode and cathode are investigated. In this study both the titanium cathodes and the stainless steel anode plates are perforated with holes comparable in size to the anode cell diameters. Only the partially saturated pumping behavior is under investigation. The ultimate pressure and conditioning of the pump will be investigated at a later date when the stability criterion for the electron cloud is better understood.

  6. Development of sensor-less control strategies for grid connected PMSG based variable speed wind energy conversion system with improved power quality features

    Energy Technology Data Exchange (ETDEWEB)

    Chandra, A. [Quebec Univ., Montreal, PQ (Canada). Dept. of Electrical Engineering

    2010-07-01

    Interest in renewable energy sources has grown in recent years in response to concerns of increasing pollution levels and depleting fossil fuels. Among renewable energy sources, wind energy generation is the fastest growing technology and one of the most cost-effective and environmental friendly means to generate electricity from renewable sources. Modern wind turbines are ready to be deployed in large scale as a result of recent developments in wind power technology. Variable speed permanent magnet synchronous generators (PMSG) based wind energy conversion systems (WECS) are becoming more popular. The use of a permanent magnet reduces size, cost and weight of overall WECS. In addition, the absence of field winding and its excitation system avoids heat dissipation in the rotor winding, thereby improving overall efficiency of the WECS. This type of configuration is more appropriate for remote locations, particularly for off-shore wind application, where the geared doubly fed induction generator usually requires regular maintenance due to tearing-wearing in brushes, windings and gear box. This presentation discussed the development of sensor-less control strategies for grid connected PMSG based variable speed wind energy conversion system with improved power quality features. A novel adaptive network-based fuzzy inference system was used to estimate the speed and position of variable speed PMSG under fluctuating wind conditions. A novel control strategy was developed for the grid interfacing inverter incorporating power quality improvement features at point of common coupling.

  7. Perbandingan Passive LC Filter Dan Passve Single Tuned Filter Untuk Mereduksi Harmonisa Variable Speed Drive Dengan Beban Motor Induksi Tiga Fasa

    OpenAIRE

    Mustamam

    2016-01-01

    Most of the tools that used as speed control of three phase induction motors rotation is 1 phase Variable Speed Drive (VSD), where VSD is a harmonic generator. Therefore the harmonics that arise in the VSD can be reduced by using passive LC filters fasif namely passive single tuned filter that meet the standards IEC61000-3-2 Class A.The results obtained through passive LC filter could reduce the total distortion of harmonic current (THDi) from 102.9% to 23.78% while passive sin...

  8. Penis Pump

    Science.gov (United States)

    ... your appointment might be less involved. Choosing a penis pump Some penis pumps are available without a ... it doesn't get caught in the ring. Penis pumps for penis enlargement Many advertisements in magazines ...

  9. Pumping behavior of ion pump elements at high and misaligned magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Hseuh, H. C.; Jiang, W. S.; Mapes, M.

    1994-11-01

    The pumping speeds of several diode type ion pump elements with cell radii of 5 mm, 5.5 mm, 6 mm, 9 mm and 12 mm were measured while being subjected to a magnetic field B, ranging from 500 Gauss up to 15 KG, and misalignment angles (angles between the direction of B and the anode axis) from 0 to 13 degrees. The pumping speeds of elements with the 9 mm and 12 mm cells peaked around 1--2 KG, then dropped off rapidly with an increasing magnetic field. The pumping speeds of the smaller cell elements remained constant with an increasing magnetic field. The pumping speeds of all the elements decreased with increasing misalignment. The measured pumping speeds from this study are 3--4 times lower than the calculated pumping, speeds using previously reported empirical formulae.

  10. Pumping behavior of ion pump elements at high and misaligned magnetic fields

    International Nuclear Information System (INIS)

    Hseuh, H.C.; Jiang, W.S.; Mapes, M.

    1994-01-01

    The pumping speeds of several diode type ion pump elements with cell radii of 5 mm, 5.5 mm, 6 mm, 9 mm and 12 mm were measured while being subjected to a magnetic field B, ranging from 500 Gauss up to 15 KG, and misalignment angles (angles between the direction of B and the anode axis) from 0 to 13 degrees. The pumping speeds of elements with the 9 mm and 12 mm cells peaked around 1--2 KG, then dropped off rapidly with an increasing magnetic field. The pumping speeds of the smaller cell elements remained constant with an increasing magnetic field. The pumping speeds of all the elements decreased with increasing misalignment. The measured pumping speeds from this study are 3--4 times lower than the calculated pumping, speeds using previously reported empirical formulae

  11. Variability of Basal Rate Profiles in Insulin Pump Therapy and Association with Complications in Type 1 Diabetes Mellitus.

    Science.gov (United States)

    Laimer, Markus; Melmer, Andreas; Mader, Julia K; Schütz-Fuhrmann, Ingrid; Engels, Heide-Rose; Götz, Gabriele; Pfeifer, Martin; Hermann, Julia M; Stettler, Christoph; Holl, Reinhard W

    2016-01-01

    Traditionally, basal rate profiles in continuous subcutaneous insulin infusion therapy are individually adapted to cover expected insulin requirements. However, whether this approach is indeed superior to a more constant BR profile has not been assessed so far. This study analysed the associations between variability of BR profiles and acute and chronic complications in adult type 1 diabetes mellitus. BR profiles of 3118 female and 2427 male patients from the "Diabetes-Patienten-Verlaufsdokumentation" registry from Germany and Austria were analysed. Acute and chronic complications were recorded 6 months prior and after the most recently documented basal rate. The "variability index" was calculated as variation of basal rate intervals in percent and describes the excursions of the basal rate intervals from the median basal rate. The variability Index correlated positively with severe hypoglycemia (r = .06; p1), hypoglycemic coma (r = .05; p = 0.002), and microalbuminuria (r = 0.05; p = 0.006). In addition, a higher variability index was associated with higher frequency of diabetic ketoacidosis (r = .04; p = 0.029) in male adult patients. Logistic regression analysis adjusted for age, gender, duration of disease and total basal insulin confirmed significant correlations of the variability index with severe hypoglycemia (β = 0.013; p1) and diabetic ketoacidosis (β = 0.012; p = 0.017). Basal rate profiles with higher variability are associated with an increased frequency of acute complications in adults with type 1 diabetes.

  12. Experimental results of wind powered pumping plant with electrical transmission

    International Nuclear Information System (INIS)

    Falchetta, M.; Prischich, D.; Benedetti, A.; Cara, G.

    1992-01-01

    A demonstrative application of deep well pumping system employing a wind powered pumping plant with an electric transmission was set-up and tested for two years at the test field of the Casaccia center of ENEA (Italian Agency for Energy, New Technologies and the Environment), near Rome. The tests permitted the evaluation of the practical performance, advantages and drawbacks of a wind pumping plant of this type, in order to permit a design optimization and a proper choice of components and of control strategies for future commercial applications. The main point of investigation was the evaluation of the effectiveness of a control scheme based on a 'permanent link' between electric generator and electric motor, avoiding any electronics and switching components, and leading to a very robust and reliable means of transferring energy to the pump at variable speed, and at low cost

  13. Final Report: Cooling Seasonal Energy and Peak Demand Impacts of Improved Duct Insulation on Fixed-Capacity (SEER 13) and Variable-Capacity (SEER 22) Heat Pumps

    Energy Technology Data Exchange (ETDEWEB)

    Withers, C. [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States); Florida Solar Energy Center (FSEC), Cocoa, FL (United States); Cummings, J. [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States); Florida Solar Energy Center (FSEC), Cocoa, FL (United States); Nigusse, B. [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States); Florida Solar Energy Center (FSEC), Cocoa, FL (United States)

    2016-09-01

    A new generation of full variable-capacity, central, ducted air-conditioning (AC) and heat pump units has come on the market, and they promise to deliver increased cooling (and heating) efficiency. They are controlled differently than standard single-capacity (fixed-capacity) systems. Instead of cycling on at full capacity and then cycling off when the thermostat is satisfied, they can vary their capacity over a wide range (approximately 40% to 118% of nominal full capacity), thus staying “on” for up to twice as many hours per day compared to fixed-capacity systems of the same nominal capacity. The heating and cooling capacity is varied by adjusting the indoor fan air flow rate, compressor, and refrigerant flow rate as well as the outdoor unit fan air flow rate. Note that two-stage AC or heat pump systems were not evaluated in this research effort. The term dwell is used to refer to the amount of time distributed air spends inside ductwork during space-conditioning cycles. Longer run times mean greater dwell time and therefore greater exposure to conductive gains and losses.

  14. Final Report: Cooling Seasonal Energy and Peak Demand Impacts of Improved Duct Insulation on Fixed-Capacity (SEER 13) and Variable-Capacity (SEER 22) Heat Pumps

    Energy Technology Data Exchange (ETDEWEB)

    Withers, C. [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States); Florida Solar Energy Center, Cocoa, FL (United States); Cummings, J. [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States); Florida Solar Energy Center, Cocoa, FL (United States); Nigusse, B. [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States); Florida Solar Energy Center, Cocoa, FL (United States)

    2016-09-08

    A new generation of full variable-capacity, central, ducted air-conditioning (AC) and heat pump units has come on the market, and they promise to deliver increased cooling (and heating) efficiency. They are controlled differently than standard single-capacity (fixed-capacity) systems. Instead of cycling on at full capacity and then cycling off when the thermostat is satisfied, they can vary their capacity over a wide range (approximately 40% to 118% of nominal full capacity), thus staying “on” for up to twice as many hours per day compared to fixed-capacity systems of the same nominal capacity. The heating and cooling capacity is varied by adjusting the indoor fan air flow rate, compressor, and refrigerant flow rate as well as the outdoor unit fan air flow rate. Note that two-stage AC or heat pump systems were not evaluated in this research effort. The term dwell is used to refer to the amount of time distributed air spends inside ductwork during space-conditioning cycles. Longer run times mean greater dwell time and therefore greater exposure to conductive gains and losses.

  15. Cooling and Heating Season Impacts of Right-Sizing of Fixed- and Variable-Capacity Heat Pumps With Attic and Indoor Ductwork

    Energy Technology Data Exchange (ETDEWEB)

    Cummings, James [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States); Withers, Charles [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States); Kono, Jamie [Building America Partnership for Improved Residential Construction, Cocoa, FL (United States)

    2015-06-24

    A new generation of full variable-capacity air-conditioning (A/C) and heat pump units has come on the market that promises to deliver very high cooling and heating efficiency. The units are controlled differently than standard single-capacity (fixed-capacity) systems. Instead of cycling on at full capacity and cycling off when the thermostat is satisfied, the new units can vary their capacity over a wide range (approximately 40%–118% of nominal full capacity) and stay on for 60%–100% more hours per day than the fixed-capacity systems depending on load-to-capacity ratios. Two-stage systems were not evaluated in this research effort.

  16. Pump cavitation and inducer design

    International Nuclear Information System (INIS)

    Heslenfeld, M.W.; Hes, M. de

    2002-01-01

    Details of past work on sodium pump development and cavitation studies executed mainly for SNR 300 were reported earlier. Among the requirements for large sodium pumps are long life (200000 hours up to 300000 hours) and small size of impeller and pump, fully meeting the process and design criteria. These criteria are the required 'Q, H, r characteristics' in combination with a low NPSH value and the avoidance of cavitation damage to the pump. The pump designer has to develop a sound hydraulic combination consisting of suction arrangement, impeller design and diffuser. On the other hand the designer is free to choose an optimal pump speed. The pump speed in its turn influences the rotor dynamic pump design and the pump drive. The introduction of the inducer as an integral part of the pump design is based on following advantages: no tip cavitation; (possible) cavitation bubbles move to the open centre due to centrifugal forces on the fluid; the head of the inducer improves the inlet conditions of the impeller. The aim of an inducer is the increase in the suction specific speed (SA value) of a pump whereby the inducer functions as a pressure source improving the impeller inlet conditions. With inducer-impeller combinations values up to SA=15000 are realistic. With the use of an inducer the overall pump sizes can be reduced with Ca. 30%. Pumps commonly available have SA values up to a maximum of ca. 10000. A development programme was executed for SNR 300 in order to reach an increase of the suction specific speed of the impeller from SA 8200 to SA 11000. Further studies to optimize pumps design for the follow up line introduced the 'inducer acting as a pre-impeller' development. This programme was executed in the period 1979-1981. At the FDO premises a scale 1 2.8 inducer impeller combination with a suction specific speed SA=15000 was developed, constructed and tested at the water test rig. This water test rig is equipped with a perspex pipe allowing also visualisation

  17. Fractional order nonlinear variable speed and current regulation of a permanent magnet synchronous generator wind turbine system

    Directory of Open Access Journals (Sweden)

    Anitha Karthikeyan

    2018-03-01

    Full Text Available In this paper we derived the fractional order model of the Permanent Magnet Synchronous Generator (PMSG from its integer model. The PMSG was employing a shaft sensor for the speed sensing and control. But this sensor would increase the hardware complexity as well as the cost of the system. Hence we have developed a Fractional order Nonlinear adaptive control method for speed and current tracking of the PMSG. The objective of an adaptive controller is to first define a virtual control state and force it to become a stabilizing function in accordance with a corresponding error dynamics. In order to study the Lyapunov exponents of the fractional order controller, we proposed a new method which would remove the complexity of finding the sign of the Lyapunov first derivative. The Fractional order control scheme is implemented in LabVIEW for simulation results. The simulation results indicated that the estimated rotor position and speed correspond to their actual values well. Keywords: Chaos suppression, Fractional order systems, Permanent magnet synchronous generator, Speed and current control, Lyapunov stability

  18. A Latent Variable Analysis of Working Memory Capacity, Short-Term Memory Capacity, Processing Speed, and General Fluid Intelligence.

    Science.gov (United States)

    Conway, Andrew R. A.; Cowan, Nelsin; Bunting, Michael F.; Therriault, David J.; Minkoff, Scott R. B.

    2002-01-01

    Studied the interrelationships among general fluid intelligence, short-term memory capacity, working memory capacity, and processing speed in 120 young adults and used structural equation modeling to determine the best predictor of general fluid intelligence. Results suggest that working memory capacity, but not short-term memory capacity or…

  19. Joint Calibration of Submarine Groundwater Discharge (SGD) with Tidal Pumping: Modeling Variable-density Groundwater Flow in Unconfined Coastal Aquifer of Apalachee Bay, Gulf of Mexico

    Science.gov (United States)

    Li, X.; Hu, B.; Burnett, W.; Santos, I.

    2008-05-01

    Submarine Groundwater Discharge (SGD) as an unseen phenomenon is now recognized as an important pathway between land and sea. These discharges typically display significant spatial and temporal variability making quantification difficult. Groundwater seepage is patchy, diffuse, and temporally variable, and thus makes the estimation of its magnitude and components is a challenging enterprise. A two-dimensional hydrogeological model is developed to the near-shore environment of an unconfined aquifer at a Florida coastal area in the northeastern Gulf of Mexico. Intense geological survey and slug tests are set to investigate the heterogeneity of this layered aquifer. By applying SEAWAT2000, considering the uncertainties caused by changes of boundary conditions, a series of variable-density-flow models incorporates the tidal-influenced seawater recirculation and the freshwater-saltwater mixing zone under the dynamics of tidal pattern, tidal amplitude and variation of water table. These are thought as the contributing factors of tidal pumping and hydraulic gradient which are the driven forces of SGD. A tidal-influenced mixing zone in the near-shore aquifer shows the importance of tidal mechanism to flow and salt transport in the process of submarine pore water exchange. Freshwater ratio in SGD is also analyzed through the comparison of Submarine Groundwater Recharge and freshwater inflow. The joint calibration with other methods (natural tracer model and seepage meter) is also discussed.

  20. Energy cost of walking: solving the paradox of steady state in the presence of variable walking speed.

    Science.gov (United States)

    Plasschaert, Frank; Jones, Kim; Forward, Malcolm

    2009-02-01

    Measurement of the energy cost of walking in children with cerebral palsy is used for baseline and outcome assessment. However, such testing relies on the establishment of steady state that is deemed present when oxygen consumption is stable. This is often assumed when walking speed is constant but in practice, speed can and does vary naturally. Whilst constant speed is achievable on a treadmill, this is often impractical clinically, thus rendering an energy cost test to an element of subjectivity. This paper attempts to address this issue by presenting a new method for calculating energy cost of walking that automatically applies a mathematically defined threshold for steady state within a (non-treadmill) walking trial and then strips out all of the non-steady state events within that trial. The method is compared with a generic approach that does not remove non-steady state data but rather uses an average value over a complete walking trial as is often used in the clinical environment. Both methods were applied to the calculation of several energy cost of walking parameters of self-selected walking speed in a cohort of unimpaired subjects and children with cerebral palsy. The results revealed that both methods were strongly correlated for each parameter but showed systematic significant differences. It is suggested that these differences are introduced by the rejection of non-steady state data that would otherwise have incorrectly been incorporated into the calculation of the energy cost of walking indices during self-selected walking with its inherent speed variation.

  1. Measures for speed management.

    NARCIS (Netherlands)

    2009-01-01

    Measures for speed management are essential for limiting the negative effects of driving too fast and at inappropriate speeds. To begin with, safe and credible speed limits need to be determined. Dynamic and variable speed limits that take into account the current circumstances, such as weather

  2. Development and evaluation of cryosorption pump and cryotrapping pump for CTR applications

    International Nuclear Information System (INIS)

    Kuribayashi, S.; Ota, H.; Sato, H.

    1986-01-01

    In order to obtain the engineering data to design compound cryopump for CTR, the authors tested the cryosorption pump and cryotrapping pump. The cryosorption panel was consisted of coconut charcoal metallically bonded to 4.2K cryopanel by brazing. The initial pumping speed of helium of cryosorption pump was found to be ≅2.2 iota/scm/sup 2/. The speed dropped off with loading (about 8 Torr iota/cm/sup 2/) to 1.5 iota/scm/sup 2/. The initial helium pumping speed of the 4.2K cryotrapping pump by argon spray was found to be ≅6 iota/scm/sup 2/. The speed, however, dropped off with loading (≅0.3 Torr iota/cm/sup 2/) to less than 5%. These results indicate that the cryosorption pump by coconut charcoal is superior to the cryotrapping pump, because the capacity of the former is larger than the latter

  3. The pumping of hydrogen and helium by sputter-ion pumps

    International Nuclear Information System (INIS)

    Welch, K.M.; Pate, D.J.; Todd, R.J.

    1992-01-01

    The pumping of hydrogen in diode and triode sputter-ion pumps is discussed. The type of cathode material used in these pumps is shown to have a significant impact on the effectiveness with which hydrogen is pumped. Examples of this include data for pumps with aluminum and titanium-alloy cathodes. Diode pumps with aluminum cathodes are shown to be no more effective in the pumping of hydrogen than in the pumping of helium. The use of titanium or titanium alloy anodes is also shown to measurably impact on the speed of these pumps at.very low pressures. This stems from the fact that hydrogen is x10 6 more soluble in titanium than in stainless steel. Hydrogen becomes resident in the anodes because of fast neutral burial. Lastly, quantitative data are given for the He speeds and capacities of both noble and conventional diode and triode pumps. The effectiveness of various pump regeneration procedures, subsequent to the pumping of He, is reported.These included bakeout and N 2 glow discharge cleaning. The comparative desorption of He with the subsequent pumping of N 2 is reported on. The N 2 speed of these pumps was used as the benchmark for defining the size of the pumps vs. their respective He speeds

  4. Latest trends in variable speed drive systems. ; Application to elevators. Kahensoku drive system no saishin doko. ; Elevator eno oyo

    Energy Technology Data Exchange (ETDEWEB)

    Inaba, H. (Hitachi, Ltd., Tokyo (Japan))

    1992-07-12

    The history of the elevator development may be summarized as a challenge to heights of buildings, pursuit of energy saving, and realizing comfort. Transfer of its drive system to the inverter drive system has been nearly completed keeping the pace with advance of electronic technologies. This paper describes control systems of elevators, effects of introducing inverters, and future trends. The inverter system used widely now for standard elevators with a speed lower than 105 m/min consists of a converter to rectify the utility power, a regenerative power consuming circuit to suppress overvoltage in the DC stage, and an inverter to supply power to induction motors. Those elevators exceeding a 120 m/min speed use power regenerating inverter system, with its converter controlled using micro computers according to loads and speeds of motors. The inverter system is particularly marked for having realized energy saving, lower power consumption, lower environmental pollution (from harmonics), comfort and maintainability at high levels. 13 refs., 9 figs.

  5. Design optimization under uncertainty and speed variability for a piezoelectric energy harvester powering a tire pressure monitoring sensor

    Science.gov (United States)

    Toghi Eshghi, Amin; Lee, Soobum; Kazem Sadoughi, Mohammad; Hu, Chao; Kim, Young-Cheol; Seo, Jong-Ho

    2017-10-01

    Energy harvesting (EH) technologies to power small sized electronic devices are attracting great attention. Wasted energy in a vehicle’s rotating tire has a great potential to enable self-powered tire pressure monitoring sensors (TPMS). Piezoelectric type energy harvesters can be used to collect vibrational energy and power such systems. Due to the presence of harsh acceleration in a rotating tire, a design tradeoff needs to be studied to prolong the harvester’s fatigue life as well as to ensure sufficient power generation. However, the design by traditional deterministic design optimization (DDO) does not show reliable performance due to the lack of consideration of various uncertainty factors (e.g., manufacturing tolerances, material properties, and loading conditions). In this study, we address a new EH design formulation that considers the uncertainty in car speed, dimensional tolerances and material properties, and solve this design problem using reliability-based design optimization (RBDO). The RBDO problem is formulated to maximize compactness and minimize weight of a TPMS harvester while satisfying power and durability requirements. A transient analysis has been done to measure the time varying response of EH such as power generation, dynamic strain, and stress. A conservative design formulation is proposed to consider the expected power from varied speed and stress at higher speed. When compared to the DDO, the RBDO results show that the reliability of EH is increased significantly by scarifying the objective function. Finally, experimental test has been conducted to demonstrate the merits of RBDO design over DDO.

  6. A Multi-Point Method Considering the Maximum Power Point Tracking Dynamic Process for Aerodynamic Optimization of Variable-Speed Wind Turbine Blades

    Directory of Open Access Journals (Sweden)

    Zhiqiang Yang

    2016-05-01

    Full Text Available Due to the dynamic process of maximum power point tracking (MPPT caused by turbulence and large rotor inertia, variable-speed wind turbines (VSWTs cannot maintain the optimal tip speed ratio (TSR from cut-in wind speed up to the rated speed. Therefore, in order to increase the total captured wind energy, the existing aerodynamic design for VSWT blades, which only focuses on performance improvement at a single TSR, needs to be improved to a multi-point design. In this paper, based on a closed-loop system of VSWTs, including turbulent wind, rotor, drive train and MPPT controller, the distribution of operational TSR and its description based on inflow wind energy are investigated. Moreover, a multi-point method considering the MPPT dynamic process for the aerodynamic optimization of VSWT blades is proposed. In the proposed method, the distribution of operational TSR is obtained through a dynamic simulation of the closed-loop system under a specific turbulent wind, and accordingly the multiple design TSRs and the corresponding weighting coefficients in the objective function are determined. Finally, using the blade of a National Renewable Energy Laboratory (NREL 1.5 MW wind turbine as the baseline, the proposed method is compared with the conventional single-point optimization method using the commercial software Bladed. Simulation results verify the effectiveness of the proposed method.

  7. Slip flow coefficient analysis in water hydraulics gear pump for environmental friendly application

    International Nuclear Information System (INIS)

    Yusof, A A; Wasbari, F; Zakaria, M S; Ibrahim, M Q

    2013-01-01

    Water hydraulics is the sustainable option in developing fluid power systems with environmental friendly approach. Therefore, an investigation on water-based external gear pump application is being conducted, as a low cost solution in the shifting effort of using water, instead of traditional oil hydraulics in fluid power application. As the gear pump is affected by fluid viscosity, an evaluation has been conducted on the slip flow coefficient, in order to understand to what extent the spur gear pump can be used with water-based hydraulic fluid. In this paper, the results of a simulated study of variable-speed fixed displacement gear pump are presented. The slip flow coefficient varies from rotational speed of 250 RPM to 3500 RPM, and provides volumetric efficiency ranges from 9 % to 97% accordingly

  8. On control strategies for power optimization and regulation of variable speed wind turbines; Sur les strategies de commande pour l'optimisation et la regulation de puissance des eoliennes a vitesse variable

    Energy Technology Data Exchange (ETDEWEB)

    Boukhezzar, B

    2006-02-15

    The research work is dealing with variable speed wind turbines modelling and control design, in order to achieve the objectives of maximizing the extracted energy from the wind, below the rated power area in the one hand and in the other hand regulating the electric power production, above the rated power area, while reducing mechanical transient loads. For this purpose, we have studied various control strategies from linear to nonlinear based. some of the controllers that we have developed, herein appear for the first time in the relevant domain, the remaining others are an adaptation of well know controllers to the adopted wind turbine models. as matter of fact, we have derived two wind turbine models as well as a wind speed estimator. Indeed, the estimator allows obtaining the effective wind speed which cannot be measured, since the wind profile around the rotor is variable in time and space. As results, it has been shown that single input control by means of pitch angle or generator control cannot succeed to simultaneously drive the electric power output regulation and the rotor speed reference tracking. So then, our idea is to combine nonlinear dynamic state feedback torque control and pitch linear based control which turns out to be the best strategy. In addition, the validation of the controllers performance, using a high turbulence wind speed profile, has been performed through wind turbine simulators provided by nrel (national renewable energy laboratory, golden, co), has confirmed the theoretical results and has led to quite satisfactory conclusions in terms of energy capture optimization, power regulation and disturbances strong rejection as well. (author)

  9. Pump Application as Hydraulic Turbine – Pump as Turbine (PaT)

    OpenAIRE

    Rusovs, D

    2009-01-01

    The paper considers pump operation as hydraulic turbine with purpose to produce mechanical power from liquid flow. The Francis hydraulic turbine was selected for comparison with centrifugal pump in reverse operation. Turbine and centrifugal pump velocity triangles were considered with purpose to evaluate PaT efficiency. Shape of impeller blades for turbine and pumps was analysed. Specific speed calculation is carried out with purpose to obtain similarity in pump and turbine description. For ...

  10. Power Quality Control and Design of Power Converter for Variable-Speed Wind Energy Conversion System with Permanent-Magnet Synchronous Generator

    Directory of Open Access Journals (Sweden)

    Yüksel Oğuz

    2013-01-01

    Full Text Available The control strategy and design of an AC/DC/AC IGBT-PMW power converter for PMSG-based variable-speed wind energy conversion systems (VSWECS operation in grid/load-connected mode are presented. VSWECS consists of a PMSG connected to a AC-DC IGBT-based PWM rectifier and a DC/AC IGBT-based PWM inverter with LCL filter. In VSWECS, AC/DC/AC power converter is employed to convert the variable frequency variable speed generator output to the fixed frequency fixed voltage grid. The DC/AC power conversion has been managed out using adaptive neurofuzzy controlled inverter located at the output of controlled AC/DC IGBT-based PWM rectifier. In this study, the dynamic performance and power quality of the proposed power converter connected to the grid/load by output LCL filter is focused on. Dynamic modeling and control of the VSWECS with the proposed power converter is performed by using MATLAB/Simulink. Simulation results show that the output voltage, power, and frequency of VSWECS reach to desirable operation values in a very short time. In addition, when PMSG based VSWECS works continuously with the 4.5 kHz switching frequency, the THD rate of voltage in the load terminal is 0.00672%.

  11. Power quality control and design of power converter for variable-speed wind energy conversion system with permanent-magnet synchronous generator.

    Science.gov (United States)

    Oğuz, Yüksel; Güney, İrfan; Çalık, Hüseyin

    2013-01-01

    The control strategy and design of an AC/DC/AC IGBT-PMW power converter for PMSG-based variable-speed wind energy conversion systems (VSWECS) operation in grid/load-connected mode are presented. VSWECS consists of a PMSG connected to a AC-DC IGBT-based PWM rectifier and a DC/AC IGBT-based PWM inverter with LCL filter. In VSWECS, AC/DC/AC power converter is employed to convert the variable frequency variable speed generator output to the fixed frequency fixed voltage grid. The DC/AC power conversion has been managed out using adaptive neurofuzzy controlled inverter located at the output of controlled AC/DC IGBT-based PWM rectifier. In this study, the dynamic performance and power quality of the proposed power converter connected to the grid/load by output LCL filter is focused on. Dynamic modeling and control of the VSWECS with the proposed power converter is performed by using MATLAB/Simulink. Simulation results show that the output voltage, power, and frequency of VSWECS reach to desirable operation values in a very short time. In addition, when PMSG based VSWECS works continuously with the 4.5 kHz switching frequency, the THD rate of voltage in the load terminal is 0.00672%.

  12. Wear behaviors of pure aluminum and extruded aluminum alloy (AA2024-T4) under variable vertical loads and linear speeds

    Science.gov (United States)

    Jung, Jeki; Oak, Jeong-Jung; Kim, Yong-Hwan; Cho, Yi Je; Park, Yong Ho

    2017-11-01

    The aim of this study was to investigate the transition of wear behavior for pure aluminum and extruded aluminum alloy 2024-T4 (AA2024-T4). The wear test was carried using a ball-on-disc wear testing machine at various vertical loads and linear speeds. The transition of wear behaviors was analyzed based on the microstructure, wear tracks, wear cross-section, and wear debris. The critical wear rates for each material are occurred at lower linear speed for each vertical load. The transition of wear behavior was observed in which abrasion wears with the generation of an oxide layer, fracture of oxide layer, adhesion wear, severe adhesion wear, and the generation of seizure occurred in sequence. In case of the pure aluminum, the change of wear debris occurred in the order of blocky, flake, and needle-like debris. Cutting chip, flake-like, and coarse flake-like debris was occurred in sequence for the extruded AA2024-T4. The transition in the wear behavior of extruded AA2024-T4 occurred slower than in pure aluminum.

  13. Vacuum pumping for controlled thermonuclear reactors

    International Nuclear Information System (INIS)

    Watson, J.S.; Fisher, P.W.

    1976-01-01

    Thermonuclear reactors impose unique vacuum pumping problems involving very high pumping speeds, handling of hazardous materials (tritium), extreme cleanliness requirements, and quantitative recovery of pumped materials. Two principal pumping systems are required for a fusion reactor, a main vacuum system for evacuating the torus and a vacuum system for removing unaccelerated deuterium from neutral beam injectors. The first system must pump hydrogen isotopes and helium while the neutral beam system can operate by pumping only hydrogen isotopes (perhaps only deuterium). The most promising pumping techniques for both systems appear to be cryopumps, but different cryopumping techniques can be considered for each system. The main vacuum system will have to include cryosorption pumps cooled to 4.2 0 K to pump helium, but the unburned deuterium-tritium and other impurities could be pumped with cryocondensation panels (4.2 0 K) or cryosorption panels at higher temperatures. Since pumping speeds will be limited by conductance through the ducts and thermal shields, the pumping performance for both systems will be similar, and other factors such as refrigeration costs are likely to determine the choice. The vacuum pumping system for neutral beam injectors probably will not need to pump helium, and either condensation or higher temperature sorption pumps can be used

  14. Reducing 4DCBCT imaging time and dose: the first implementation of variable gantry speed 4DCBCT on a linear accelerator.

    Science.gov (United States)

    O'Brien, Ricky T; Stankovic, Uros; Sonke, Jan-Jakob; Keall, Paul J

    2017-06-07

    Four dimensional cone beam computed tomography (4DCBCT) uses a constant gantry speed and imaging frequency that are independent of the patient's breathing rate. Using a technique called respiratory motion guided 4DCBCT (RMG-4DCBCT), we have previously demonstrated that by varying the gantry speed and imaging frequency, in response to changes in the patient's real-time respiratory signal, the imaging dose can be reduced by 50-70%. RMG-4DCBCT optimally computes a patient specific gantry trajectory to eliminate streaking artefacts and projection clustering that is inherent in 4DCBCT imaging. The gantry trajectory is continuously updated as projection data is acquired and the patient's breathing changes. The aim of this study was to realise RMG-4DCBCT for the first time on a linear accelerator. To change the gantry speed in real-time a potentiometer under microcontroller control was used to adjust the current supplied to an Elekta Synergy's gantry motor. A real-time feedback loop was developed on the microcontroller to modulate the gantry speed and projection acquisition in response to the real-time respiratory signal so that either 40, RMG-4DCBCT 40 , or 60, RMG-4DCBCT 60 , uniformly spaced projections were acquired in 10 phase bins. Images of the CIRS dynamic Thorax phantom were acquired with sinusoidal breathing periods ranging from 2 s to 8 s together with two breathing traces from lung cancer patients. Image quality was assessed using the contrast to noise ratio (CNR) and edge response width (ERW). For the average patient, with a 3.8 s breathing period, the imaging time and image dose were reduced by 37% and 70% respectively. Across all respiratory rates, RMG-4DCBCT 40 had a CNR in the range of 6.5 to 7.5, and RMG-4DCBCT 60 had a CNR between 8.7 and 9.7, indicating that RMG-4DCBCT allows consistent and controllable CNR. In comparison, the CNR for conventional 4DCBCT drops from 20.4 to 6.2 as the breathing rate increases from 2 s to 8 s. With RMG-4DCBCT

  15. James A. FitzPatrick Nuclear Power Plant recirculation pumps vibration system installation and performance since July 7, 1990

    International Nuclear Information System (INIS)

    Lefter, J.

    1992-01-01

    James A. FitzPatrick recirculation pumps are vertical units consisting of General Electric 5,300 hp variable speed motors driving Byron Jackson Pumps. Speed range is from 400 rpm at 20% reactor power to 1,480 rpm at 100% power. Full speed pump output is 42,500 gpm at 530 ft. head. This paper describes the vibration monitoring system. The design of this vibration monitoring system took about five months and was installed during plant refueling outage between February and May 1990. The objectives of this project were as follows: (1) document and assess the mechanical condition of each RRP during plant startup normal operation and shutdown; (2) identify any areas of operation that might be harmful to the unit; (3) perform impact testing of the proximity probe brackets to determine if any bracket resonances existed in the 0 to 20 times operating speed region (0 to 20X); (4) define and recommend Acceptance Regions in the TDM system

  16. Optimal sizing of small wind/battery systems considering the DC bus voltage stability effect on energy capture, wind speed variability, and load uncertainty

    International Nuclear Information System (INIS)

    Lujano-Rojas, Juan M.; Dufo-López, Rodolfo; Bernal-Agustín, José L.

    2012-01-01

    Highlights: ► We propose a mathematical model for optimal sizing of small wind energy systems. ► No other previous work has considered all the aspects included in this paper. ► The model considers several parameters about batteries. ► Wind speed variability is considered by means of ARMA model. ► The results show how to minimize the expected energy that is not supplied. - Abstract: In this paper, a mathematical model for stochastic simulation and optimization of small wind energy systems is presented. This model is able to consider the operation of the charge controller, the coulombic efficiency during charge and discharge processes, the influence of temperature on the battery bank capacity, the wind speed variability, and load uncertainty. The joint effect of charge controller operation, ambient temperature, and coulombic efficiency is analyzed in a system installed in Zaragoza (Spain), concluding that if the analysis without considering these factors is carried out, the reliability level of the physical system could be lower than expected, and an increment of 25% in the battery bank capacity would be required to reach a reliability level of 90% in the analyzed case. Also, the effect of the wind speed variability and load uncertainty in the system reliability is analyzed. Finally, the uncertainty in the battery bank lifetime and its effect on the net present cost are discussed. The results showed that, considering uncertainty of 17.5% in the battery bank lifetime calculated using the Ah throughput model, about 12% of uncertainty in the net present cost is expected. The model presented in this research could be a useful stochastic simulation and optimization tool that allows the consideration of important uncertainty factors in techno-economic analysis.

  17. The Effects of Heart Rate Versus Speed-Based High-Intensity Interval Training on Heart Rate Variability in Young Females

    Directory of Open Access Journals (Sweden)

    Maryam Rabbani

    2017-06-01

    Full Text Available Introduction: The aim of this study was to compare the effects of high-intensity interval training (HIT prescription by heart rate (HR-based and running speed (speed-based methods on natural logarithm of the square root of the mean of the sum of the squares of differences between adjacent normal R-R intervals (Ln rMSSD as a measure of heart rate variability (HRV in young female student athletes. Methods: Seventeen female student athletes participated in this study and were divided into HR-based (n=9, age: 16.7 years and speed-based (n=8, age: 16.9 years HIT groups. 30-15 Intermittent Fitness Test was used for the speed-based group to detect the reference maximum speed (VIFT for prescribing the HIT intensity accordingly. Age predicted maximal HR was used for the HR-based group as the reference value. All subjects performed similar training protocol for 5 weeks, except the method of individualizing HIT sessions (2 weekly sessions of HIT=3 sets of 3 minutes work interspersed with 3 minutes passive recovery with the 15-15 seconds format during each working set; either according to 90%-95% of maximal HR or VIFT. Results: HR- and speed-based HIT groups showed the most likely large improvements in Ln rMSSD of +7.9%, 90% confidence limits [CL] (5.9; 10.0; standardized change: +1.75 (1.32; 2.19 and +5.5%, (2.8; 8.3; +1.41 (0.72; 2.09, respectively. In between group analyses, HR-based HIT produced likely a small greater improvement in Ln rMSSD than speed-based HIT (+1.9%, [-5.0; 4.4]; +0.50 [-0.14; 1.14], chances for greater/similar/lower values of 79/17/4. Conclusion: It is concluded that both HIT prescription strategies were effective in Ln rMSSD elevation, but using maximal HR as a reference may elicit higher parasympathetic dominance with small effect in young female student athletes.

  18. Automated surveillance of reactor coolant pump performance

    International Nuclear Information System (INIS)

    Gross, K.C.; Singer, R.M.; Humenik, K.E.

    1992-01-01

    An artificial intelligence based expert system has been developed for continuous surveillance and diagnosis of centrifugal-type reactor coolant pump (RCP) performance and operability. The expert system continuously monitors digitized signals from a variety of physical variables (speed, vibration level, motor power, discharge pressure) associated with RCP performance for annunciation of the incipience or onset of off-normal operation. The system employs an extremely sensitive pattern-recognition technique, the sequential probability ratio test (SPRT) for rapid identification of pump operability degradation. The sequential statistical analysis of the signal noise has been shown to provide the theoretically shortest sampling time to detect disturbances and thus has the potential of providing incipient fault detection information to operators sufficiently early to avoid forced plant shutdowns. The sensitivity and response time of the expert system are analyzed in this paper using monte carlo simulation techniques

  19. A reduced switch count UPF power conditioner for grid connected variable speed wind energy conversion system employing PM generators: a simulation study

    Energy Technology Data Exchange (ETDEWEB)

    Raju, A.B.; Fernandes, B.G.; Chatterjee, K. [Indian Institute of Technology, Mumbai (India). Dept. of Electrical Engineering

    2004-07-01

    In this paper, modelling and simulation of a grid connected variable speed wind energy conversion system (VSWECS) with reduced switch count power converter is presented. The system consists of a permanent magnet synchronous generator (PMSG), two-pulse width modulated B-4 power converters and a maximum power point tracker (MPPT). Mathematical models of each element of the system are developed separately and are then integrated to simulate the whole system for various wind velocities. The complete system is simulated using MATLAB/SIMULINK and simulation results are presented. (author)

  20. Heat pumps

    CERN Document Server

    Macmichael, DBA

    1988-01-01

    A fully revised and extended account of the design, manufacture and use of heat pumps in both industrial and domestic applications. Topics covered include a detailed description of the various heat pump cycles, the components of a heat pump system - drive, compressor, heat exchangers etc., and the more practical considerations to be taken into account in their selection.

  1. Study and performances analysis of fuel cell assisted vector control variable speed drive system used for electric vehicles

    Science.gov (United States)

    Pachauri, Rupendra Kumar; Chauhan, Yogesh K.

    2017-02-01

    This paper is a novel attempt to combine two important aspects of fuel cell (FC). First, it presents investigations on FC technology and its applications. A description of FC operating principles is followed by the comparative analysis of the present FC technologies together with the issues concerning various fuels. Second, this paper also proposes a model for the simulation and performances evaluation of a proton exchange membrane fuel cell (PEMFC) generation system. Furthermore, a MATLAB/Simulink-based dynamic model of PEMFC is developed and parameters of FC are so adjusted to emulate a commercially available PEMFC. The system results are obtained for the PEMFC-driven adjusted speed induction motor drive (ASIMD) system, normally used in electric vehicles and analysis is carried out for different operating conditions of FC and ASIMD system. The obtained results prove the validation of system concept and modelling.

  2. Comparison of Sliding Mode Control and Fuzzy Logic control applied to Variable Speed Wind Energy Conversion Systems

    Directory of Open Access Journals (Sweden)

    Souhila Rached Zine

    2015-08-01

    Full Text Available wind energy features prominently as a supplementary energy booster. It does not pollute and is inexhaustible. However, its high cost is a major constraint, especially on the less windy sites. The purpose of wind energy systems is to maximize energy efficiency, and extract maximum power from the wind speed. In This case, the MPPT control becomes important. To realize this control, strategy conventional Proportional and Integral (PI controller is usually used. However, this strategy cannot achieve better performance. This paper proposes other control methods of a turbine which optimizes its production such as fuzzy logic, sliding mode control. These methods improve the quality and energy efficiency. The proposed Sliding Mode Control (SMC strategy and the fuzzy controllers have presented attractive features such as robustness to parametric uncertainties of the turbine, simplicity of its design and good performances. The simulation result under Matlab\\Simulink has validated the performance of the proposed MPPT strategies.

  3. DAC to Mitigate the Effect of Periodic Disturbances on Drive Train using Collective Pitch for Variable Speed Wind Turbine

    DEFF Research Database (Denmark)

    Imran, Raja Muhammad; Hussain, Dil Muhammad Akbar; Soltani, Mohsen

    2015-01-01

    scheme to mitigate the effect of 3p flicker on drive train. 5MW wind turbine of the National Renewable Laboratories (NREL) is used as research object and results are simulated in MATLAB/Simulink. We designed the controller based on linearized model of the wind turbine generated for above rated wind speed...... and then tested its performance on the nonlinear model of wind turbine. We have shown a comparison of the results for proportional-integral(PI) and proposed DAC controller tested on nonlinear model of wind turbine. Result shows that our proposed controller shows better mitigation of flicker generated due to 3p......DAC is a linear control technique used to mitigate the effect of disturbance on the plant. It is a superposition of full state feedback and disturbance feedback. This paper presents a control technique based on Disturbance Accommodation Control (DAC) to reduce fatigue on drive train generated...

  4. Modeling and control of a Continuously Variable Transmission in a constant speed power take-off application

    NARCIS (Netherlands)

    Aladagli, Irmak; Hofman, Theo; Steinbuch, Maarten; Vroemen, Bas

    2012-01-01

    Traditional control design techniques like manual tuning are widely employed within the Continuously Variable Transmission (CVT) industry. However, manual tuning comprises of trial and error and is therefore time consuming. Moreover, the results are likely far from optimal in the sense of some

  5. In-process tool rotational speed variation with constant heat input in friction stir welding of AZ31 sheets with variable thickness

    Science.gov (United States)

    Buffa, Gianluca; Campanella, Davide; Forcellese, Archimede; Fratini, Livan; Simoncini, Michela

    2017-10-01

    In the present work, friction stir welding experiments on AZ31 magnesium alloy sheets, characterized by a variable thickness along the welding line, were carried out. The approach adapted during welding consisted in maintaining constant the heat input to the joint. To this purpose, the rotational speed of the pin tool was increased with decreasing thickness and decreased with increasing thickness in order to obtain the same temperatures during welding. The amount by which the rotational speed was changed as a function of the sheet thickness was defined on the basis of the results given by FEM simulations of the FSW process. Finally, the effect of the in-process variation of the tool rotational speed on the mechanical and microstructural properties of FSWed joints was analysed by comparing both the nominal stress vs. nominal strain curves and microstructure of FSWed joints obtained in different process conditions. It was observed that FSW performed by keeping constant the heat input to the joint leads to almost coincident results both in terms of the curve shape, ultimate tensile strength and ultimate elongation values, and microstructure.

  6. LOX/LH2 vane pump for auxiliary propulsion systems

    Science.gov (United States)

    Hemminger, J. A.; Ulbricht, T. E.

    1985-01-01

    Positive displacement pumps offer potential efficiency advantages over centrifugal pumps for future low thrust space missions. Low flow rate applications, such as space station auxiliary propulsion or dedicated low thrust orbiter transfer vehicles, are typical of missions where low flow and high head rise challenge centrifugal pumps. The positive displacement vane pump for pumping of LOX and LH2 is investigated. This effort has included: (1) a testing program in which pump performance was investigated for differing pump clearances and for differing pump materials while pumping LN2, LOX, and LH2; and (2) an analysis effort, in which a comprehensive pump performance analysis computer code was developed and exercised. An overview of the theoretical framework of the performance analysis computer code is presented, along with a summary of analysis results. Experimental results are presented for pump operating in liquid nitrogen. Included are data on the effects on pump performance of pump clearance, speed, and pressure rise. Pump suction performance is also presented.

  7. Heat pumps

    CERN Document Server

    Brodowicz, Kazimierz; Wyszynski, M L; Wyszynski

    2013-01-01

    Heat pumps and related technology are in widespread use in industrial processes and installations. This book presents a unified, comprehensive and systematic treatment of the design and operation of both compression and sorption heat pumps. Heat pump thermodynamics, the choice of working fluid and the characteristics of low temperature heat sources and their application to heat pumps are covered in detail.Economic aspects are discussed and the extensive use of the exergy concept in evaluating performance of heat pumps is a unique feature of the book. The thermodynamic and chemical properties o

  8. A Heuristic T-S Fuzzy Model for the Pumped-Storage Generator-Motor Using Variable-Length Tree-Seed Algorithm-Based Competitive Agglomeration

    Directory of Open Access Journals (Sweden)

    Jianzhong Zhou

    2018-04-01

    Full Text Available With the fast development of artificial intelligence techniques, data-driven modeling approaches are becoming hotspots in both academic research and engineering practice. This paper proposes a novel data-driven T-S fuzzy model to precisely describe the complicated dynamic behaviors of pumped storage generator motor (PSGM. In premise fuzzy partition of the proposed T-S fuzzy model, a novel variable-length tree-seed algorithm based competitive agglomeration (VTSA-CA algorithm is presented to determine the optimal number of clusters automatically and improve the fuzzy clustering performances. Besides, in order to promote modeling accuracy of PSGM, the input and output formats in the T-S fuzzy model are selected by an economical parameter controlled auto-regressive (CAR model derived from a high-order transfer function of PSGM considering the distributed components in the water diversion system of the power plant. The effectiveness and superiority of the T-S fuzzy model for PSGM under different working conditions are validated by performing comparative studies with both practical data and the conventional mechanistic model.

  9. Centrifugal pumps: fundamentals and classification

    International Nuclear Information System (INIS)

    Solar Manuel, A. M.

    2009-01-01

    Centrifugal pumps are usually employed to impulse water to elevate it, dose it or give it pressure or speed. They can be used with clean water or loaded with high solid concentration and don't work properly with air or another gas flow. There are another less used pumps, coming from volumetric or ram pumps to magnetic ones for specific uses. Centrifugal ones are rotokinetic pumps, like peripherical or lateral channel pumps. They work in a different way that non rotational kinetic ones and static ones. The work approaches their pre definition, selection, installation, operation and maintenance. It also review their morphology, hidromechanic principles and the basic elements pumps are made of. (Author)

  10. Power Extraction Control of Variable Speed Wind Turbine Systems Based on Direct Drive Synchronous Generator in All Operating Regimes

    Directory of Open Access Journals (Sweden)

    Youssef Errami

    2018-01-01

    Full Text Available Due to the increased penetration of wind energy into the electrical power systems in recent years, the turbine controls are actively occupied in the research. This paper presents a nonlinear backstepping strategy to control the generators and the grid sides of a Wind Farm System (WFS based Direct Drive Synchronous Generator (DDSG. The control objectives such as Tracking the Maximum Power (TMP from the WFS, pitch control, regulation of dc-link voltage, and reactive and active power generation at varying wind velocity are included. To validate the proposed control strategy, simulation results for 6-MW-DDSG based Wind Farm System are carried out by MATLAB-Simulink. Performance comparison and evaluation with Vector Oriented Control (VOC are provided under a wide range of functioning conditions, three-phase voltage dips, and the probable occurrence of uncertainties. The proposed control strategy offers remarkable characteristics such as excellent dynamic and steady state performance under varying wind speed and robustness to parametric variations in the WFS and under severe faults of grid voltage.

  11. Work plan for vibration cable re-route and water flush system modifications for 107-AN mixer pump

    International Nuclear Information System (INIS)

    Leshikar, G.A.

    1995-01-01

    A mixer pump (75 horsepower Hazleton submersible) is to be installed in the central pump pit of Double-Shell Tank 241-AN-107 for the Caustic Addition Project. The mixer pump will be used as a platform to inject, mix, and entrain caustic with the waste, in order to bring the waste hydroxyl ion concentration into compliance with Tank Farm operating specifications. Testing of the mixer pump and caustic addition system revealed that the mixer pump's vibration cable picks up electromagnetic interference from the motor power cable during variable speed operation of the pump. Also, it was noted that the mixer pump's water flush system may not be as effective as desired. Ergo this work plan for improving the operation of these mixer pump subsystems. A new vibration cable shall be routed entirely outside the mixer pump support column pipe, up thru a new penetration in the pump mounting flange. The existing penetration in the side of the pipe is to be plugged. Increasing the distance between power and instrument cables may reduce or eliminate electromagnetic interference to the vibration monitor. The mixer pump water flush system shall be modified to allow pressure isolation of individual branches. A header is to be installed on the middle section of the support column. Each branch (there are three) shall contain a solenoid valve (normally open) to control flow into the branch. The solenoid cables shall be routed up thru three new penetrations in the pump mounting flange to a new electrical box mounted on the flange. The existing flush piping to the inlet screen will remain but the continuation of the flush piping to the pump discharge nozzles is to be removed and the tee plugged. New stainless steel tubing is to be run down to the pump discharge nozzles. Pressure isolation of individual branches will maximize the flush system's effectiveness at blasting potential sediment clogs out of the pump discharge nozzles

  12. Pump audit identifies the energy consumers; Pump Audit identifiziert gezielt die Energieverschwender

    Energy Technology Data Exchange (ETDEWEB)

    Siekemann, Ralf [Grundfos GmbH, Erkrath (Germany)

    2011-03-14

    Engineering and services, which enhance and secure the energy efficiency of pump systems, are demanded. Speed-regulated pumps, included high efficient motors and a service philosophy, be designed on value conservation and cost control, are as well as professional ''pump-audits''. (orig./GL)

  13. The role of capacitance in a wind-electric water pumping system

    Energy Technology Data Exchange (ETDEWEB)

    Ling, Shitao [West Texas A& M Univ., Canyon, TX (United States); Clark, R.N. [Conservation and Production Research Lab., Bushland, TX (United States)

    1997-12-31

    The development of controllers for wind-electric water pumping systems to enable the use of variable voltage, variable frequency electricity to operate standard AC submersible pump motors has provided a more efficient and flexible water pumping system to replace mechanical windmills. A fixed capacitance added in parallel with the induction motor improves the power factor and starting ability of the pump motor at the lower cut-in frequency. The wind-electric water pumping system developed by USDA-Agricultural Research Service, Bushland, TX, operated well at moderate wind speeds (5-12 m/s), but tended to lose synchronization in winds above 12 m/s, especially if they were gusty. Furling generally did not occur until synchronization had been lost and the winds had to subside before synchronization could be reestablished. The frequency needed to reestablish synchronization was much lower (60-65 Hz) than the frequency where synchronization was lost (70-80 Hz). As a result, the load (motor and pump) stayed off an excessive amount of time thus causing less water to be pumped and producing a low system efficiency. The controller described in this paper dynamically connects additional capacitance of the proper amount at the appropriate time to keep the system synchronized (running at 55 to 60 Hz) and pumping water even when the wind speed exceeds 15 m/s. The system efficiency was improved by reducing the system off-line time and an additional benefit was reducing the noise caused by the high speed blade rotation when the load was off line in high winds.

  14. Centrifugal pumps

    CERN Document Server

    Gülich, Johann Friedrich

    2014-01-01

    This book gives an unparalleled, up-to-date, in-depth treatment of all kinds of flow phenomena encountered in centrifugal pumps including the complex interactions of fluid flow with vibrations and wear of materials. The scope includes all aspects of hydraulic design, 3D-flow phenomena and partload operation, cavitation, numerical flow calculations, hydraulic forces, pressure pulsations, noise, pump vibrations (notably bearing housing vibration diagnostics and remedies), pipe vibrations, pump characteristics and pump operation, design of intake structures, the effects of highly viscous flows, pumping of gas-liquid mixtures, hydraulic transport of solids, fatigue damage to impellers or diffusers, material selection under the aspects of fatigue, corrosion, erosion-corrosion or hydro-abrasive wear, pump selection, and hydraulic quality criteria. As a novelty, the 3rd ed. brings a fully analytical design method for radial impellers, which eliminates the arbitrary choices inherent to former design procedures. The d...

  15. Power converter with maximum power point tracking MPPT for small wind-electric pumping systems

    International Nuclear Information System (INIS)

    Lara, David; Merino, Gabriel; Salazar, Lautaro

    2015-01-01

    Highlights: • We implement a wind electric pumping system of small power. • The power converter allowed to change the operating point of the electro pump. • Two control techniques were implemented in the power converter. • The control V/f variable allowed to increase the power generated by the permanent magnet generator. - Abstract: In this work, an AC–DC–AC direct-drive power converter was implemented for a wind electric pumping system consisting of a permanent magnet generator (PMG) of 1.3 kW and a peripheral single phase pump of 0.74 kW. In addition, the inverter linear V/f control scheme and the maximum power point tracking (MPPT) algorithm with variable V/f were developed. MPPT algorithm seeks to extract water in a wide range of power input using the maximum amount of wind power available. Experimental trials at different pump pressures were conducted. With a MPPT tracking system with variable V/f, a power value of 1.3 kW was obtained at a speed of 350 rpm and a maximum operating hydraulic head of 50 m. At lower operating heads pressures (between 10 and 40 m), variable V/f control increases the power generated by the PMG compared to the linear V/f control. This increase ranged between 4% and 23% depending on the operating pressure, with an average of 13%, getting close to the maximum electrical power curve of the PMG. The pump was driven at variable frequency reaching a minimum speed of 0.5 times the rated speed. Efficiency of the power converter ranges between 70% and 95% with a power factor between 0.4 and 0.85, depending on the operating pressure

  16. Pumping life

    DEFF Research Database (Denmark)

    Sitsel, Oleg; Dach, Ingrid; Hoffmann, Robert Daniel

    2012-01-01

    The name PUMPKIN may suggest a research centre focused on American Halloween traditions or the investigation of the growth of vegetables – however this would be misleading. Researchers at PUMPKIN, short for Centre for Membrane Pumps in Cells and Disease, are in fact interested in a large family o......’. Here we illustrate that the pumping of ions means nothing less than the pumping of life....

  17. Rapid Speed Modulation of a Rotary Total Artificial Heart Impeller.

    Science.gov (United States)

    Kleinheyer, Matthias; Timms, Daniel L; Tansley, Geoffrey D; Nestler, Frank; Greatrex, Nicholas A; Frazier, O Howard; Cohn, William E

    2016-09-01

    Unlike the earlier reciprocating volume displacement-type pumps, rotary blood pumps (RBPs) typically operate at a constant rotational speed and produce continuous outflow. When RBP technology is used in constructing a total artificial heart (TAH), the pressure waveform that the TAH produces is flat, without the rise and fall associated with a normal arterial pulse. Several studies have suggested that pulseless circulation may impair microcirculatory perfusion and the autoregulatory response and may contribute to adverse events such as gastrointestinal bleeding, arteriovenous malformations, and pump thrombosis. It may therefore be beneficial to attempt to reproduce pulsatile output, similar to that generated by the native heart, by rapidly modulating the speed of an RBP impeller. The choice of an appropriate speed profile and control strategy to generate physiologic waveforms while minimizing power consumption and blood trauma becomes a challenge. In this study, pump operation modes with six different speed profiles using the BiVACOR TAH were evaluated in vitro. These modes were compared with respect to: hemodynamic pulsatility, which was quantified as surplus hemodynamic energy (SHE); maximum rate of change of pressure (dP/dt); pulse power index; and motor power consumption as a function of pulse pressure. The results showed that the evaluated variables underwent different trends in response to changes in the speed profile shape. The findings indicated a possible trade-off between SHE levels and flow rate pulsatility related to the relative systolic duration in the speed profile. Furthermore, none of the evaluated measures was sufficient to fully characterize hemodynamic pulsatility. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  18. The Impacts of Wind Speed Trends and 30-Year Variability in Relation to Hydroelectric Reservoir Inflows on Wind Power in the Pacific Northwest.

    Science.gov (United States)

    Cross, Benjamin D; Kohfeld, Karen E; Bailey, Joseph; Cooper, Andrew B

    2015-01-01

    In hydroelectric dominated systems, the value and benefits of energy are higher during extended dry periods and lower during extended or extreme wet periods. By accounting for regional and temporal differences in the relationship between wind speed and reservoir inflow behavior during wind farm site selection, the benefits of energy diversification can be maximized. The goal of this work was to help maximize the value of wind power by quantifying the long-term (30-year) relationships between wind speed and streamflow behavior, using British Columbia (BC) and the Pacific Northwest (PNW) as a case study. Clean energy and self-sufficiency policies in British BC make the benefits of increased generation during low streamflow periods particularly large. Wind density (WD) estimates from a height of 10m (North American Regional Reanalysis, NARR) were correlated with cumulative usable inflows (CUI) for BC (collected from BC Hydro) for 1979-2010. The strongest WD-CUI correlations were found along the US coast (r ~0.55), whereas generally weaker correlations were found in northern regions, with negative correlations (r ~ -0.25) along BC's North Coast. Furthermore, during the lowest inflow years, WD anomalies increased by up to 40% above average values for the North Coast. Seasonally, high flows during the spring freshet were coincident with widespread negative WD anomalies, with a similar but opposite pattern for low inflow winter months. These poorly or negatively correlated sites could have a moderating influence on climate related variability in provincial electricity supply, by producing greater than average generation in low inflow years and reduced generation in wet years. Wind speed and WD trends were also analyzed for all NARR grid locations, which showed statistically significant positive trends for most of the PNW and the largest increases along the Pacific Coast.

  19. A PLL-based resampling technique for vibration analysis in variable-speed wind turbines with PMSG: A bearing fault case

    Science.gov (United States)

    Pezzani, Carlos M.; Bossio, José M.; Castellino, Ariel M.; Bossio, Guillermo R.; De Angelo, Cristian H.

    2017-02-01

    Condition monitoring in permanent magnet synchronous machines has gained interest due to the increasing use in applications such as electric traction and power generation. Particularly in wind power generation, non-invasive condition monitoring techniques are of great importance. Usually, in such applications the access to the generator is complex and costly, while unexpected breakdowns results in high repair costs. This paper presents a technique which allows using vibration analysis for bearing fault detection in permanent magnet synchronous generators used in wind turbines. Given that in wind power applications the generator rotational speed may vary during normal operation, it is necessary to use special sampling techniques to apply spectral analysis of mechanical vibrations. In this work, a resampling technique based on order tracking without measuring the rotor position is proposed. To synchronize sampling with rotor position, an estimation of the rotor position obtained from the angle of the voltage vector is proposed. This angle is obtained from a phase-locked loop synchronized with the generator voltages. The proposed strategy is validated by laboratory experimental results obtained from a permanent magnet synchronous generator. Results with single point defects in the outer race of a bearing under variable speed and load conditions are presented.

  20. Integrated Power and Attitude Control Design of Satellites Based on a Fuzzy Adaptive Disturbance Observer Using Variable-Speed Control Moment Gyros

    Directory of Open Access Journals (Sweden)

    Zhongyi Chu

    2016-01-01

    Full Text Available To satisfy the requirements for small satellites that seek agile slewing with peak power, this paper investigates integrated power and attitude control using variable-speed control moment gyros (VSCMGs that consider the mass and inertia of gimbals and wheels. The paper also details the process for developing the controller by considering various environments in which the controller may be implemented. A fuzzy adaptive disturbance observer (FADO is proposed to estimate and compensate for the effects of equivalent disturbances. The algorithms can simultaneously track attitude and power. The simulation results illustrate the effectiveness of the control approach, which exhibits an improvement of 80 percent compared with alternate approaches that do not employ a FADO.

  1. Flicker Mitigation by Active Power Control of Variable-Speed Wind Turbines With Full-Scale Back-to-Back Power Converters

    DEFF Research Database (Denmark)

    Hu, Weihao; Chen, Zhe; Wang, Zhaoan

    2009-01-01

    /EMTDC. Flicker emission of this system is investigated. Reactive power compensation is mostly adopted for flicker mitigation. However, the flicker mitigation technique shows its limits, when the grid impedance angle is low in some distribution networks. A new method of flicker mitigation by controlling active...... power is proposed. It smoothes the 3p active power oscillations from wind shear and tower shadow effects of the wind turbine by varying the dc-link voltage of the full-scale converter. Simulation results show that damping the 3p active power oscillation by using the flicker mitigation controller...... is an effective means for flicker mitigation of variable-speed wind turbines with full-scale back-to-back power converters during continuous operation....

  2. Baxter elastomeric pumps: Feasibility of weight estimates.

    Science.gov (United States)

    Chambers, Carole R; Pabia, Mica; Sawyer, Michael; Tang, Patricia A

    2017-09-01

    Purpose Elastomeric pumps are used to infuse a 46-h fluorouracil protocol and patients are asked to visually inspect the pump daily. The pump has a variability of ±10% and there are additional patient variables that can increase this. The feasibility of weighing the pump rather than a visual inspection along with the secondary objective to confirm the pump's variability in real world conditions was undertaken. Methods Empty pumps were weighed using both pharmacy and kitchen scales. Pumps upon completion of the 46-h infusion were also weighed using both pharmacy and kitchen scales. Results The kitchen scale was as accurate as the pharmacy grade scale. Disconnected pumps showed the expected variability from using these infusor pumps along with a few showing greater variability likely due to patient variables. Conclusion Weighing pumps appears to be feasible both at the pharmacy and home level. Next steps would be to weigh pumps during the infusion to validate an alternate method to simple visual inspection for patients to confirm proper infusing of the pump at their home.

  3. Rotary Speed Sensor for Antilocking Brakes

    Science.gov (United States)

    Berdahl, C. M.

    1986-01-01

    Sensor based on fluidic principles produces negative pressure approximately proportional to rotational speed. Sensor developed as part of antilocking brake system for motorcycles. Uses inlet pressure rather than outlet pressure as braking-control signal, eliminating pressure pulsations caused by pump vanes and ensuring low-noise signal. Sensor is centrifugal air pump turned by one of motorcycle wheels. Air enters pump through orifice plates, and suction taken off through port in pump inlet plenum.

  4. Advanced performance of small diaphragm vacuum pumps through the use of mechatronics

    Science.gov (United States)

    Lachenmann, R.; Dirscherl, J.

    Oil-free diaphragm vacuum pumps have proven to be the best way in vacuum generation for the chemical laboratory and they also find increasing use as backing pumps for modern wide-range turbo molecular pumps. The majority of vacuum pumps in practical use pump only a rather small percentage of their lifetime at full gas load. A pump backing a turbo molecular pump does not have to pump a significant gas load when the high-vacuum pump is running at ultimate vacuum pressure. Also, for a vacuum distillation the vacuum pump has to operate at full speed only at the beginning to lower the pressure inside the system to a vacuum level where evaporation starts. In a rather leak-tight system the distillation process continues by evaporating from the hot liquid and condensing at the cold condenser without the need of a mechanical vacuum pump. Rotational speed controlled diaphragm pumps are now available through progress in mechatronics and offer high pumping speed capability for fast pump-down cycles and precise pressure control for distillations. At low gas load the rotational speed can be reduced, improving maintenance intervals, power consumption, noise, vibration and - surprisingly - also ultimate pressure. The different behaviour in pumping speed and ultimate pressure of rotational speed controlled diaphragm pumps in comparison to constant-speed pumps is related to the mechanical properties of the valves and gas dynamics .

  5. Lunar Base Heat Pump

    Science.gov (United States)

    Walker, D.; Fischbach, D.; Tetreault, R.

    1996-01-01

    The objective of this project was to investigate the feasibility of constructing a heat pump suitable for use as a heat rejection device in applications such as a lunar base. In this situation, direct heat rejection through the use of radiators is not possible at a temperature suitable for lde support systems. Initial analysis of a heat pump of this type called for a temperature lift of approximately 378 deg. K, which is considerably higher than is commonly called for in HVAC and refrigeration applications where heat pumps are most often employed. Also because of the variation of the rejection temperature (from 100 to 381 deg. K), extreme flexibility in the configuration and operation of the heat pump is required. A three-stage compression cycle using a refrigerant such as CFC-11 or HCFC-123 was formulated with operation possible with one, two or three stages of compression. Also, to meet the redundancy requirements, compression was divided up over multiple compressors in each stage. A control scheme was devised that allowed these multiple compressors to be operated as required so that the heat pump could perform with variable heat loads and rejection conditions. A prototype heat pump was designed and constructed to investigate the key elements of the high-lift heat pump concept. Control software was written and implemented in the prototype to allow fully automatic operation. The heat pump was capable of operation over a wide range of rejection temperatures and cooling loads, while maintaining cooling water temperature well within the required specification of 40 deg. C +/- 1.7 deg. C. This performance was verified through testing.

  6. Reactor coolant pumps for nuclear reactors

    International Nuclear Information System (INIS)

    Harand, E.; Richter, G.; Tschoepel, G.

    1975-01-01

    A brake for the pump rotor of a main coolant pump or a shutoff member on the pump are provided in order to prevent excess speeds of the pump rotor. Such excess speeds may occur in PWR type reactors with water at a pressure below, e.g., 150 bars if there is leakage from a coolant line associated with the main coolant pump. As a brake, a centrifugal brake depending upon the pump speed or a brake ring arranged on the pump housing and acting on the pump rotor, which ring would be activated by pressure differentials in the pump, may be used. If the pressure differences between suction and pressure sockets are very small, a controlled hydraulic increase of the pressure force on the brake may also be provided. Furthermore, a turbine brake may be provided. A slide which is automatically movable in closing position along the pump rotor axis is used as a shutoff element. It is of cylindrical configuration and is arranged concentrically with the rotor axis. (DG) [de

  7. Liquid metals pumping

    International Nuclear Information System (INIS)

    Le Frere, J.P.

    1984-01-01

    Pumps used to pump liquid metals depend on the liquid metal and on the type of application concerned. One deals more particularly with electromagnetic pumps, the main pumps used with mechanical pumps. To pump sodium in the nuclear field, these two types of pumps are used; the pumps of different circuits of Super Phenix are presented and described [fr

  8. Motor Integrated Variable Speed Drives

    DEFF Research Database (Denmark)

    Singh, Yash Veer

    rectifier at the front end is presented in this thesis and requirements of a buffer stage in the form of ESI is explained in detail. An equivalent circuit and linear model are developed to give the transfer function and control of the ESI based three-phase rectifier. In this thesis a power converter...... with ESI is designed and tested with standard induction motor to verify functionality of a working drive. One modified version of the ESI based converter has also been looked into to reduce losses of converter, but because of difficulties in reducing the bus-bar inductance in that design, further...

  9. Electromagnetic pump

    International Nuclear Information System (INIS)

    Ito, Koji; Suetake, Norio; Aizawa, Toshie; Nakasaki, Masayoshi

    1998-01-01

    The present invention provides an electromagnetic pump suitable to a recycling pump for liquid sodium as coolants of an FBR type reactor. Namely, a stator module of the electromagnetic pump of the present invention comprises a plurality of outer laminate iron core units and outer stator modules stacked alternately in the axial direction. With such a constitution, even a long electromagnetic pump having a large number of outer stator coils can be manufactured without damaging electric insulation of the outer stator coils. In addition, the inner circumferential surface of the outer laminate iron cores is urged and brought into contact with the outer circumferential surface of the outer duct by an elastic material. With such a constitution, Joule loss heat generated in the outer stator coils and internal heat generated in the outer laminate iron cores can be released to an electroconductive fluid flowing the inner circumference of the outer duct by way of the outer duct. (I.S.)

  10. Electrokinetic pump

    Science.gov (United States)

    Patel, Kamlesh D.

    2007-11-20

    A method for altering the surface properties of a particle bed. In application, the method pertains particularly to an electrokinetic pump configuration where nanoparticles are bonded to the surface of the stationary phase to alter the surface properties of the stationary phase including the surface area and/or the zeta potential and thus improve the efficiency and operating range of these pumps. By functionalizing the nanoparticles to change the zeta potential the electrokinetic pump is rendered capable of operating with working fluids having pH values that can range from 2-10 generally and acidic working fluids in particular. For applications in which the pump is intended to handle highly acidic solutions latex nanoparticles that are quaternary amine functionalized can be used.

  11. Implementation of multiple measures to improve reactor recirculation pump sealing performance in nuclear boiling water reactor service

    Energy Technology Data Exchange (ETDEWEB)

    Loenhout, Gerard van [Flowserve B.V., Etten-Leur (Netherlands). Nuclear Services and Solutions Engineering; Hurni, Juerg

    2015-05-15

    A modern reactor recirculation pump circulates a large volume of high temperature, very pure water from the reactor pressure vessel back to the core by feeding into multiple stationary jet pumps inside the vessel. Together with the jet pumps, they allow station operators to vary coolant flow and variable pump speed provides the best and most stable reactor power control. A crucial technical problem with a recirculation pump, such as a mechanical seal indicating loss of sealing pressure, may result in a power station having to shut down for repair. This article describes the sudden increase in stray current phenomenon leading to rapid and severe deterioration of the mechanical end face shaft seal in a reactor recirculation pump. This occurred after the installation of a variable frequency converter replacing the original motor-generator set. This article will also discuss the 2,500 hour laboratory test results conducted under reactor recirculation pump sealing conditions using a newly developed seal face technology recently implemented to overcome challenges when sealing neutral, ultra-pure water. In addition, the article will describe the elaborate shaft grounding arrangement and the preliminary measurement results achieved in order to eliminate potential damages to both pump and mechanical seal.

  12. Liquid sodium pumps

    International Nuclear Information System (INIS)

    Allen, H.G.

    1985-01-01

    The pump for use in a nuclear reactor cooling system comprises a booster stage impeller for drawing the liquid through the inlet. A diffuser is affixedly disposed within the pump housing to convert the kinetic pressure imparted to the liquid into increased static pressure. A main stage impeller is rotatively driven by a pump motor at a relatively high speed to impart a relatively high static pressure to the liquid and for discharging the liquid at a relatively high static pressure. A hydraulic coupling is disposed remotely from the liquid path for hydraulically coupling the main stage impeller and the booster stage impeller to rotate the booster stage impeller at a relatively low speed to maintain the low net positive suction pressure applied to the liquid at the inlet greater than the vapor pressure of the liquid and to ensure that the low net positive suction heat, as established by the main stage impeller exceeds the vapor pressure. The coupling comprises a grooved drum which rotates between inner and outer drag coupling members. In a modification the coupling comprises a torque converter. (author)

  13. Pumps and pump facilities. 2. ed.

    International Nuclear Information System (INIS)

    Bohl, W.; Bauerfeind, H.; Gutmann, G.; Leuschner, G.; Matthias, H.B.; Mengele, R.; Neumaier, R.; Vetter, G.; Wagner, W.

    1981-01-01

    This book deals with the common fundamental aspects of liquid pumps and gives an exemplary choice of the most important kinds of pumps. The scientific matter is dealt with by means of practical mathematical examples among other ways of presenting the matter. Survey of contents: Division on main operational data of pumps - pipe characteristics - pump characteristics - suction behaviour of the pumps - projecting and operation of rotary pumps - boiler feed pumps - reactor feed pumps - oscillating positive-displacement pumps - eccentric spiral pumps. (orig./GL) [de

  14. A generic pump/compressor design for circulation of cryogenic fluids

    International Nuclear Information System (INIS)

    Jasinski, T.; Honkonen, S.C.; Sixsmith, H.; Stacy, W.D.

    1986-01-01

    This paper describes the development of a second-generation centrifugal circulator for cryogenic fluids. The circulator is designed to operate over a wide range of flow rate and pressure rise and can be used for the pumping of liquid and compression of vapor at temperatures down to liquid helium (4 K). The machine incorporates self-acting gas journal bearings, a permanent magnet axial thrust bearing, and a variable speed induction motor drive to provide for reliable, maintenance-free operation. The paper provides design details of the pump. Calculated performance characteristics are also presented along with a general discussion regarding limitations of the present system

  15. High-efficiency design optimization of a centrifugal pump

    Energy Technology Data Exchange (ETDEWEB)

    Heo, Man Woong; Ma, Sang Bum; Shim, Hyeon Seok; Kim, Kwang Yong [Dept. of Mechanical Engineering, Inha University, Incheon (Korea, Republic of)

    2016-09-15

    Design optimization of a backward-curved blades centrifugal pump with specific speed of 150 has been performed to improve hydraulic performance of the pump using surrogate modeling and three-dimensional steady Reynolds-averaged Navier-Stokes analysis. The shear stress transport model was used for the analysis of turbulence. Four geometric variables defining the blade hub inlet angle, hub contours, blade outlet angle, and blade angle profile of impeller were selected as design variables, and total efficiency of the pump at design flow rate was set as the objective function for the optimization. Thirty-six design points were chosen using the Latin hypercube sampling, and three different surrogate models were constructed using the objective function values calculated at these design points. The optimal point was searched from the constructed surrogate model by using sequential quadratic programming. The optimum designs of the centrifugal pump predicted by the surrogate models show considerable increases in efficiency compared to a reference design. Performance of the best optimum design was validated compared to experimental data for total efficiency and head.

  16. Cryogenic vacuum pumping at the LBL 88-inch cyclotron

    International Nuclear Information System (INIS)

    Elo, D.; Morris, D.; Clark, D.J.; Gough, R.A.

    1978-09-01

    A cryogenic vacuum pumping panel has been in operation at the 88-inch cyclotron since 1974. The nude pumping panel is located in the acceleration chamber. The pumping surface consists of tubing cooled to 20 0 K by a closed loop helium refrigeration system. The pumping surfaces are shielded from radiation heat loads and water vapors by liquid nitrogen cooled baffles. The panel was designed for an average pumping speed of 14,000 liters/sec. for air. This approximately tripled the total effective pumping on the acceleration chamber from the existing diffusion pumped system, significantly reducing charge exchange losses of heavy ions during acceleration. Design, installation and performance characteristics are described

  17. Development of ceramic vacuum pumps for fusion reactors

    International Nuclear Information System (INIS)

    Anon.

    1990-01-01

    To achieve the magnetic field resistance and tritium resistance which are required for vacuum pumps for fusion reactors, a vacuum pump consisting of middle-ceramic turbo molecular pump (TMP), using ceramic rotor and ceramic turbo roughing pump was developed. In colaboration with the Japan Atomic Energy Research Institute, performance tests on pumping speed, compression ratio of middle-ceramic TMP and both of pumping characteristics were carried out. Sufficient performances were obtained. It was showed that middle-ceramic TMP had pumping speed of more than 500 l/s, and could achieve the pressure below 4 x 10 -7 Pa. Ceramic turbo roughing pump could vacuum from atmospheric pressure. It is concluded that complete oil-free ceramic vacuum pump can be put into practical use (K.S.)

  18. Power supplyer for reactor coolant recycling pump

    International Nuclear Information System (INIS)

    Nara, Hiroshi; Okinaka, Yo.

    1991-01-01

    The present invention concerns a variable voltage/variable frequency static power source (static power source) used as a power source for a coolants recycling pump motor of a nuclear power plant. That is, during lower power operation such as start up or shutdown in which stoppage of the power source gives less effect to a reactor core, power is supplied from a power system, a main power generator connected thereto or a high voltage bus in the plant or a common high voltage bus to the static power source. However, during rated power operation, power is supplied from the output of an axially power generator connected with a main power generator having an extremely great inertia moment to the static power device. With such a constitution, the static power device is not stopped by the lowering of the voltage due to a thunderbolt falling accident or the like to a power-distribution line suddenly occurred in the power system. Accordingly, reactor core flowrate is free from rapid decrease caused by the reduction of rotation speed of the recycling pump. Accordingly, disadvantgages upon operation control in the reactor core is not caused. (I.S.)

  19. Fluidic pumps

    International Nuclear Information System (INIS)

    Priestman, G.H.

    1990-01-01

    A fluidic pump has primary and secondary vessels connected by a pipe, a displacement vessel having liquid to be delivered through a pipe via a rectifier provided with a feed tank. A drive unit delivers pressure fluid to a line to raise liquid and compress trapped gas or liquid in the space, including the pipe between the liquids in the two vessels and thus drive liquid out of the displacement vessel. The driving gas is therefore separated by the barrier liquid and the trapped gas or liquid from the liquid to be pumped which liquid could be e.g. radioactive. (author)

  20. Pumped storage

    International Nuclear Information System (INIS)

    Strauss, P.L.

    1991-01-01

    The privately financed 1,000 MW Rocky Point Pumped Storage Project located in central Colorado, USA, will be one of the world's highest head, 2,350 feet reversible pump/turbine projects. The project will offer an economical supply of peaking power and spinning reserve power to Colorado and other southwestern states. This paper describes how the project will be made compatible with the environmental conditions in the project area and the type of terrestrial mitigation measures that are being proposed for those situations where the project impacts the environment, either temporarily or permanently

  1. Performance analysis of air source heat pump system for office building

    Energy Technology Data Exchange (ETDEWEB)

    Han, Dong Won; KIm, Yong Chan [Korea University, Seoul (Korea, Republic of); Chang, Young Soo [School of Mechanical System Engineering, Kookmin University, Seoul (Korea, Republic of)

    2016-11-15

    In this study, the performance of an air source heat pump system installed in a commercial building is analyzed using the developed heat pump performance model and building load simulation data of several regions in Korea. The performance test of an air source heat pump system with a variable speed compressor is tested to develop model that considers changes in the performance characteristics of the heat pump system under various operating conditions. The heat pump system is installed in an environmental chamber, and the experimental equipment is set up according to the manufacturer' specifications as well as the AHRI 1230 test specifications. The performance test conditions of the heat pump system are selected using a central composite design method, in which 29 points for each cooling and heating mode are selected. The developed performance model based on experimental data predicts experimental values with an error of ±5 %. Building cooling and heating loads in three regions in Korea are analyzed using TRNSYS software, which includes standard building and weather data from Seoul, Daejeon and Busan in Korea. The effects of outdoor air temperature and part load ratio on the performance and regional monthly average power consumption of the heat pump system are analyzed.

  2. Efficiency assessment of a wind pumping system

    International Nuclear Information System (INIS)

    Lara, David D.; Merino, Gabriel G.; Pavez, Boris J.; Tapia, Juan A.

    2011-01-01

    The combined efficiency of the components determines overall system performance in electric wind pumping systems. We evaluated a system composed of a 3 kW wind generator feeding a battery bank of 48 V/880 Ah by means of a non-controlled 6-pulse rectifier. Connected to this battery bank was a 1.5 kW inverter that generated 220 V at 50 Hz, which powers a 1.1 kW single-phase electric pump. At the University of Concepcion, Chile, energy losses in each electrical component was determined using a data collection system configured to measure electrical variables in real time. The electrical power generated by the wind generator for different wind speeds averaged 38% lower than the power curve provided by the manufacturer. Electromechanical tests performed in a lab showed the operation efficiency of the electric generator of the wind turbine averaged 80%. This information, along with the electrical power output, and the wind velocity measured during field operation allowed us to determine the rotor's power coefficient C p , which had a maximum value of 35%. For the stored energy components measured data indicated that the rectifier, the battery bank, and the inverter operated with average efficiencies of 95%, 78% and 86% respectively. The combined component efficiencies showed a maximum of 17% of the wind energy would be available for water pumping. Since a large amount of wind energy was dissipated during the energy conversion process, new configurations should be analyzed that could avoid such losses in wind pumping systems.

  3. Efficiency assessment of a wind pumping system

    Energy Technology Data Exchange (ETDEWEB)

    Lara, David D.; Merino, Gabriel G. [Department of Mechanization and Energy, University of Concepcion, Avenida Vicente Mendez 595, Chillan (Chile); Pavez, Boris J. [Department of Electrical Engineering, University of La Frontera, Casilla 54-D, Temuco (Chile); Tapia, Juan A. [Department of Electrical Engineering, University of Concepcion, Casilla 160-C, Concepcion (Chile)

    2011-02-15

    The combined efficiency of the components determines overall system performance in electric wind pumping systems. We evaluated a system composed of a 3 kW wind generator feeding a battery bank of 48 V/880 Ah by means of a non-controlled 6-pulse rectifier. Connected to this battery bank was a 1.5 kW inverter that generated 220 V at 50 Hz, which powers a 1.1 kW single-phase electric pump. At the University of Concepcion, Chile, energy losses in each electrical component was determined using a data collection system configured to measure electrical variables in real time. The electrical power generated by the wind generator for different wind speeds averaged 38% lower than the power curve provided by the manufacturer. Electromechanical tests performed in a lab showed the operation efficiency of the electric generator of the wind turbine averaged 80%. This information, along with the electrical power output, and the wind velocity measured during field operation allowed us to determine the rotor's power coefficient C{sub p}, which had a maximum value of 35%. For the stored energy components measured data indicated that the rectifier, the battery bank, and the inverter operated with average efficiencies of 95%, 78% and 86% respectively. The combined component efficiencies showed a maximum of 17% of the wind energy would be available for water pumping. Since a large amount of wind energy was dissipated during the energy conversion process, new configurations should be analyzed that could avoid such losses in wind pumping systems. (author)

  4. Test report for the run-in acceptance testing of the hydrogen mitigation retrieval Pump-3

    International Nuclear Information System (INIS)

    Berglin, B.G.; Nash, Ch.R.

    1997-01-01

    This report will provide the findings of the demonstration test conducted on the Double-Shell Tank (DST) 241-SY-101 HMR Pump-3 in accordance with WHC-SDWM-TP-434 ''Test plan for run-in acceptance testing of hydrogen mitigation/retrieval pump-3'' at the 400 Area Maintenance and Storage Facility (MASF) building from 7 June 1996 through 30 July 1996 per work package 4A-96-92/W. The DST 241-SY-101 hydrogen mitigation retrieval Pump-3 is a 200-HP submersible electric driven pump that has been modified for use in the DST 241-SY-101 containing mixed waste located in the 200W area. The pump has a motor driven rotation mechanism that allows the pump column to rotate through 355 degree. Prior to operation, pre-operational checks were performed which included loop calibration grooming and alignment of instruments, learning how plumb HMR-3 assembly hung in a vertical position and bump test of the motor to determine rotation direction. The pump was tested in the MASF Large Diameter Cleaning Vessel (LDCV) with process water at controlled temperatures and levels. In addition, the water temperature of the cooling water to the motor oil heat exchanger was recorded during testing. A 480-volt source powered a Variable Frequency Drive (VFD). The VFD powered the pump at various frequencies and voltages to control speed and power output of the pump. A second VFD powered the oil cooling pump. A third VFD was not available to operate the rotational drive motor during the 72 hour test, so it was demonstrated as operational before and after the test. A Mini Acquisition and Control System (Mini-DACS) controls pump functions and monitoring of the pump parameters. The Mini-DACS consists of three computers, software and some Programmable Logic Controllers (PLC). Startup and shutdown of either the pump motor or the oil cooling pump can be accomplished by the Mini-DACS. When the pump was in operation, the Mini-DACS monitors automatically collects data electronically. However, some required data

  5. Turbomolecular pump vacuum system for the Princeton Large Torus

    International Nuclear Information System (INIS)

    Dylla, H.F.

    1977-10-01

    A turbomolecular pump vacuum system has been designed and installed on the Princeton Large Torus (PLT). Four vertical shaft, oil-bearing, 1500 l/s turbomolecular pumps have been interfaced to the 6400 liter PLT Vacuum vessel to provide a net pumping speed of 3000 l/s for H 2 . The particular requirements and problems of tokamak vacuum systems are enumerated. A vacuum control system is described which protects the vacuum vessel from contamination, and protects the turbomolecular pumps from damage under a variety of possible failure modes. The performance of the vacuum system is presented in terms of pumping speed measurements and residual gas behavior

  6. Fuel savings with conventional hot water space heating systems by incorporating a natural gas powered heat pump. Preliminary project: Development of heat pump technology

    Science.gov (United States)

    Vanheyden, L.; Evertz, E.

    1980-12-01

    Compression type air/water heat pumps were developed for domestic heating systems rated at 20 to 150 kW. The heat pump is driven either by a reciprocating piston or rotary piston engine modified to operate on natural gas. Particular features of natural gas engines as prime movers, such as waste heat recovery and variable speed, are stressed. Two systems suitable for heat pump operation were selected from among five different mass produced car engines and were modified to incorporate reciprocating piston compressor pairs. The refrigerants used are R 12 and R 22. Test rig data transferred to field conditions show that the fuel consumption of conventional boilers can be reduced by 50% and more by the installation of engine driven heat pumps. Pilot heat pumps based on a 1,600 cc reciprocating piston engine were built for heating four two-family houses. Pilot pump operation confirms test rig findings. The service life of rotary piston and reciprocating piston engines was investigated. The tests reveal characteristic curves for reciprocating piston engines and include exhaust composition measurements.

  7. Development of model pump for establishing hydraulic design of primary sodium pumps in PFBR

    International Nuclear Information System (INIS)

    Chougule, R.J.; Sahasrabudhe, H.G.; Rao, A.S.L.K.; Balchander, K.; Kale, R.D.

    1994-01-01

    Indira Gandhi Centre for Atomic Research, Kalpakkam indicated requirement of indigenous development of primary sodium pump, handling liquid sodium as coolant in Fast Breeder Reactor. The primary sodium pump concept selected in its preliminary design is a vertical, single stage, with single suction impeller, suction facing downwards. The pump is having diffuser, discharge casing and discharge collector. The 1/3 rd size model pump is developed to establish the hydraulic performance of the prototype primary sodium pump. The main objectives were to verify the hydraulic design to operate on low net positive suction head available (NPSHA), no evidence of visible cavitation at available NPSHA, the pump should be designed with a diffuser etc. The model pump PSP 250/40 was designed and successfully developed by Research and Development Division of M/s Kirloskar Brothers Ltd., Kirloskarvadi. The performance testing using model pump was successfully carried out on a closed circuit test rig. The performance of a model pump at three different speeds 1900 rpm, 1456 rpm and 975 rpm was established. The values of hydraulic axial thrust with and without balancing holes on impeller at 1900 rpm was measured. Visual cavitation study at 1900 rpm was carried out to establish the NPSH at bubble free operation of the pump. The tested performance of the model pump is converted to the full scale prototype pump. The predicted performance of prototype pump at 700 rpm was found to be meeting fully with the expected duties. (author). 6 figs., 3 tabs

  8. Application of the DTC control in the photovoltaic pumping system

    International Nuclear Information System (INIS)

    Moulay-Idriss, Chergui; Mohamed, Bourahla

    2013-01-01

    Highlights: ► To improve the efficiency of PV systems, under different temperature and irradiance conditions. ► The MPPT and different control method for the induction motor were applied. ► The DTC in PV pumping system introduced and performance studied. ► The introductions of DTC in PV systems are very promising. ► Optimizing the water pumping system speed response characteristic by DTC. - Abstract: We aim to find a better control and optimization among the different functions of a solar pumping system. The photovoltaic panel can provide a maximum power only for defined output voltage and current. In addition, the operation to get the maximum power depends on the terminals of load, mostly a non-linear load like induction motor. In this work, we propose an intelligent control method for the maximum power point tracking of a photovoltaic system under variable temperature and irradiance conditions. The system was tested without maximum power point tracking, with the use of Scalar-Based control motor, but we cannot maintain the speed optimal. Next, we developed several methods for the control. Finally, we have chosen the Direct Torque Control.

  9. Inducer pumps for liquid metal reactor plants

    International Nuclear Information System (INIS)

    Jackson, E.D.

    2002-01-01

    Pumps proposed for liquid metal reactor plants typically use centrifugal impellers as the rotating element and are required to maintain a relatively low speed to keep the suction specific speed low enough to operate at the available net positive suction head (HPSH) and to avoid cavitation damage. These low speeds of operation require that the pump diameter increase and/or multiple stages be used to achieve the design head. This frequently results in a large, heavy, complex pump design. In addition, the low speed results in a larger drive motor size so that the resultant penalty to the plant designer is multiplied. The heavier pump can also result in further complications as, e.g., the difficulty in maintaining the first critical speed sufficiently above the pump operating range to provide margin for rotor dynamic stability. To overcome some of these disadvantages, it was proposed the use of inducer pumps for Liquid Metal Fast Breeder Reactor (LMFBR) plants. This paper discusses some of the advantages of the inducer pump and the development history of designing and testing these pumps both in water and sodium. The inducer pump is seen to be a sound concept with a strong technology base derived from the aerospace and ship propulsion industries. The superior suction performance capability of the inducer offers significant system design advantages, primarily a smaller, lighter weight, less complex pump design with resulting saving in cost. Extensive testing of these pumps has been conducted in both sodium and water to demonstrate the long-life capability with no cavitation damage occurring in those designs based on Rockwell's current design criteria. These tests have utilized multiple inspection and measurement approaches to accurately assess and identify any potential for cavitation damage, and these approaches have all concluded that no damage is occurring. Therefore, it is concluded that inducer pumps can be safely designed for long life operation in sodium with

  10. Investigation the Effects of Operation Methods on Energy Consumption in Agricultural Water Pumping Stations

    Directory of Open Access Journals (Sweden)

    M. DelfanAzari

    2017-01-01

    Full Text Available Introduction: The energy crisis has led the world toward the reduction of energy consumption. More than 70 percent of the energy in agriculture sector is used by pumps. In our country, there is no clear standard and guideline and also no adequate supervision for the design, selection, installation and operation of pumping systems appropriate to the circumstances and needs. Consequently, these systems operate with low efficiency and high losses of energy. While more than 20 percent of the world's electricity is consumed by pumps, average pumping efficiency is less than 40%. So evaluation of pumping stations and providing some solutions to increase efficiency and pumping system’s life time and to reduce energy consumption can be an effective in optimization of energy consumption in the country. The main reasons for the low efficiency of pumping systems comparing to potential efficiency are using unsuitable techniques for flow control, hydraulic and physical changes of pumping system during the time, using pumps or motors with low efficiency and poor maintenance. Normally the amount of flow is not constant over the time in a pumping system and needed flow rate is changed at different times. Designing of pumping system should be responsible for peak requirements as well as it must suggest the suitable flow control method to achieve least energy losses for minimum flow requirements. Also one of the main capabilities to reduce energy consumption in pumping stations is improving the flow control method. Using the flow control valves and bypass line with high energy losses is very common. While the use of variable speed pumps (VSPs that supply water requirement with sufficient pressure and minimum amount of energy, is limited due to lack of awareness of designers and (or high initial costs. Materials and Methods: In this study, the operation of the pumping stations under four scenarios (for discharge control in a drip irrigation system was analyzed

  11. Modeling the effects of the variability of temperature-related dynamic viscosity on the thermal-affected zone of groundwater heat-pump systems

    Science.gov (United States)

    Lo Russo, Stefano; Taddia, Glenda; Cerino Abdin, Elena

    2018-01-01

    Thermal perturbation in the subsurface produced in an open-loop groundwater heat pump (GWHP) plant is a complex transport phenomenon affected by several factors, including the exploited aquifer's hydrogeological and thermal characteristics, well construction features, and the temporal dynamics of the plant's groundwater abstraction and reinjection system. Hydraulic conductivity has a major influence on heat transport because plume propagation, which occurs primarily through advection, tends to degrade following conductive heat transport and convection within moving water. Hydraulic conductivity is, in turn, influenced by water reinjection because the dynamic viscosity of groundwater varies with temperature. This paper reports on a computational analysis conducted using FEFLOW software to quantify how the thermal-affected zone (TAZ) is influenced by the variation in dynamic viscosity due to reinjected groundwater in a well-doublet scheme. The modeling results demonstrate non-negligible groundwater dynamic-viscosity variation that affects thermal plume propagation in the aquifer. This influence on TAZ calculation was enhanced for aquifers with high intrinsic permeability and/or substantial temperature differences between abstracted and post-heat-pump-reinjected groundwater.

  12. Test bench for operational investigation of photovoltaic pumping systems; Bancada de ensaio para averiguacao operacional de sistemas fotovoltaicos de bombeamento

    Energy Technology Data Exchange (ETDEWEB)

    Brito, Alaan Ubaiara; Fedrizzi, Maria Cristina; Zilles, Roberto [Universidade de Sao Paulo (IEE/USP), SP (Brazil). Inst. de Eletrotecnica e Energia], Emails: alaan@iee.usp.br, fedrizzi@iee.usp.br, zilles@iee.usp.br

    2006-07-01

    From the daily water demand, total head and the daily average irradiation, is possible to determine the size of the PV generator for pumping systems. However, once the equipment is acquired some tests are recommended, specially to verify its performance. One of the most relevant parameters to qualify a pumping system is the daily water delivered (m{sup 3}/day) as a function of daily solar irradiation (Wh/m{sup 2}). Facilities that fit different boundaries conditions, as for example constant total head (m) are not easily available, and just few laboratories have this capability. In this way a simple instrumentation with the capability to determine the daily performance of PV pumping systems is presented. The proposed test tools use a hydraulic circuit with two pumps, one connected to the PV system and the other to the electric grid. The total head is maintained constant by the variable speed drive connected to the grid. (author)

  13. A solar assisted heat-pump dryer and water heater

    International Nuclear Information System (INIS)

    Hawlader, M.N.A.; Chou, S.K.; Jahangeer, K.A.; Rahman, S.M.A.

    2006-01-01

    Growing concern about the depletion of conventional energy resources has provided impetus for considerable research and development in the area of alternative energy sources. A solar assisted heat pump dryer and water heater found to be one of the solutions while exploring for alternative energy sources. The heat pump system is used for drying and water heating applications with the major share of the energy derived from the sun and the ambient. The solar assisted heat pump dryer and water heater has been designed, fabricated and tested. The performance of the system has been investigated under the meteorological conditions of Singapore. The system consists of a variable speed reciprocating compressor, evaporator-collector, storage tank, air cooled condenser, auxiliary heater, blower, dryer, dehumidifier, and air collector. The drying medium used is air and the drying chamber is configured to carry out batch drying of good grains. A water tank connected in series with the air cooled condenser delivers hot water for domestic applications. The water tank also ensures complete condensation of the refrigerant vapour. A simulation program is developed using Fortran language to evaluate the performance of the system and the influence of different variables. The performance indices considered to evaluate the performance of the system are: Solar Fraction (SF), Coefficient of Performance (COP) and Specific Moisture Extraction Rate (SMER). A COP value of 7.5 for a compressor speed of 1800 rpm was observed. Maximum collector efficiencies of 0.86 and 0.81 have been found for evaporator-collector and air collector, respectively. A value of the SMER of 0.79 has been obtained for a load of 20 kg and a compressor speed of 1200 rpm

  14. Solar Pump

    Science.gov (United States)

    Pique, Charles

    1987-01-01

    Proposed pump moves liquid by action of bubbles formed by heat of sun. Tube of liquid having boiling point of 100 to 200 degrees F placed at focal axis of cylindrical reflector. Concentrated sunlight boils liquid at focus, and bubbles of vapor rise in tube, carrying liquid along with them. Pressure difference in hot tube sufficient to produce flow in large loop. Used with conventional flat solar heating panel in completely solar-powered heat-storage system.

  15. PUMP: analog-hybrid reactor coolant hydraulic transient model

    International Nuclear Information System (INIS)

    Grandia, M.R.

    1976-03-01

    The PUMP hybrid computer code simulates flow and pressure distribution; it is used to determine real time response to starting and tripping all combinations of PWR reactor coolant pumps in a closed, pressurized, four-pump, two-loop primary system. The simulation includes the description of flow, pressure, speed, and torque relationships derived through pump affinity laws and from vendor-supplied pump zone maps to describe pump dynamic characteristics. The program affords great flexibility in the type of transients that can be simulated

  16. Neutral pumping rates for a next step tokamak ignition device

    International Nuclear Information System (INIS)

    Galambos, J.D.; Peng, Y.K.M.; Heifetz, D.

    1985-01-01

    Neutral pumping rates are calculated for pump-limiter and divertor options of a next step tokamak ignition device using a method that accounts for the coupled effects of neutral transport and plasma transport. For both pump limiters and divertors the plasma flow into the channel surrounding the neutralizer plate is greatly reduced by the neutral recycling. The fraction of this flow that is pumped can be large (>50%) but in general is dependent on the particular geometry and plasma conditions. It is estimated that pumping speeds greater than or approximately 10 5 L/s are adequate for the exhaust requirements in the pump-limiter and the divertor cases

  17. Reducing the risk of rear-end collisions with infrastructure-to-vehicle (I2V) integration of variable speed limit control and adaptive cruise control system.

    Science.gov (United States)

    Li, Ye; Wang, Hao; Wang, Wei; Liu, Shanwen; Xiang, Yun

    2016-08-17

    Adaptive cruise control (ACC) has been investigated recently to explore ways to increase traffic capacity, stabilize traffic flow, and improve traffic safety. However, researchers seldom have studied the integration of ACC and roadside control methods such as the variable speed limit (VSL) to improve safety. The primary objective of this study was to develop an infrastructure-to-vehicle (I2V) integrated system that incorporated both ACC and VSL to reduce rear-end collision risks on freeways. The intelligent driver model was firstly modified to simulate ACC behavior and then the VSL strategy used in this article was introduced. Next, the I2V system was proposed to integrate the 2 advanced techniques, ACC and VSL. Four scenarios of no control, VSL only, ACC only, and the I2V system were tested in simulation experiments. Time exposed time to collision (TET) and time integrated time to collision (TIT), 2 surrogate safety measures derived from time to collision (TTC), were used to evaluate safety issues associated with rear-end collisions. The total travel times of each scenario were also compared. The simulation results indicated that both the VSL-only and ACC-only methods had a positive impact on reducing the TET and TIT values (reduced by 53.0 and 58.6% and 59.0 and 65.3%, respectively). The I2V system combined the advantages of both ACC and VSL to achieve the most safety benefits (reduced by 71.5 and 77.3%, respectively). Sensitivity analysis of the TTC threshold also showed that the I2V system obtained the largest safety benefits with all of the TTC threshold values. The impact of different market penetration rates of ACC vehicles in I2V system indicated that safety benefits increase with an increase in ACC proportions. Compared to VSL-only and ACC-only scenarios, this integrated I2V system is more effective in reducing rear-end collision risks. The findings of this study provide useful information for traffic agencies to implement novel techniques to improve

  18. Aerodynamic Effects of Turbulence Intensity on a Variable-Speed Power-Turbine Blade with Large Incidence and Reynolds Number Variations

    Science.gov (United States)

    Flegel, Ashlie Brynn; Giel, Paul W.; Welch, Gerard E.

    2014-01-01

    The effects of inlet turbulence intensity on the aerodynamic performance of a variable speed power turbine blade are examined over large incidence and Reynolds number ranges. Both high and low turbulence studies were conducted in the NASA Glenn Research Center Transonic Turbine Blade Cascade Facility. The purpose of the low inlet turbulence study was to examine the transitional flow effects that are anticipated at cruise Reynolds numbers. The high turbulence study extends this to LPT-relevant turbulence levels while perhaps sacrificing transitional flow effects. Downstream total pressure and exit angle data were acquired for ten incidence angles ranging from +15.8 to 51.0. For each incidence angle, data were obtained at five flow conditions with the exit Reynolds number ranging from 2.12105 to 2.12106 and at a design exit Mach number of 0.72. In order to achieve the lowest Reynolds number, the exit Mach number was reduced to 0.35 due to facility constraints. The inlet turbulence intensity, Tu, was measured using a single-wire hotwire located 0.415 axial-chord upstream of the blade row. The inlet turbulence levels ranged from 0.25 - 0.4 for the low Tu tests and 8- 15 for the high Tu study. Tu measurements were also made farther upstream so that turbulence decay rates could be calculated as needed for computational inlet boundary conditions. Downstream flow field measurements were obtained using a pneumatic five-hole pitchyaw probe located in a survey plane 7 axial chord aft of the blade trailing edge and covering three blade passages. Blade and endwall static pressures were acquired for each flow condition as well. The blade loading data show that the suction surface separation that was evident at many of the low Tu conditions has been eliminated. At the extreme positive and negative incidence angles, the data show substantial differences in the exit flow field. These differences are attributable to both the higher inlet Tu directly and to the thinner inlet endwall

  19. Aerodynamic Effects of High Turbulence Intensity on a Variable-Speed Power-Turbine Blade With Large Incidence and Reynolds Number Variations

    Science.gov (United States)

    Flegel, Ashlie B.; Giel, Paul W.; Welch, Gerard E.

    2014-01-01

    The effects of high inlet turbulence intensity on the aerodynamic performance of a variable speed power turbine blade are examined over large incidence and Reynolds number ranges. These results are compared to previous measurements made in a low turbulence environment. Both high and low turbulence studies were conducted in the NASA Glenn Research Center Transonic Turbine Blade Cascade Facility. The purpose of the low inlet turbulence study was to examine the transitional flow effects that are anticipated at cruise Reynolds numbers. The current study extends this to LPT-relevant turbulence levels while perhaps sacrificing transitional flow effects. Assessing the effects of turbulence at these large incidence and Reynolds number variations complements the existing database. Downstream total pressure and exit angle data were acquired for 10 incidence angles ranging from +15.8deg to -51.0deg. For each incidence angle, data were obtained at five flow conditions with the exit Reynolds number ranging from 2.12×10(exp 5) to 2.12×10(exp 6) and at a design exit Mach number of 0.72. In order to achieve the lowest Reynolds number, the exit Mach number was reduced to 0.35 due to facility constraints. The inlet turbulence intensity, Tu, was measured using a single-wire hotwire located 0.415 axial-chord upstream of the blade row. The inlet turbulence levels ranged from 8 to 15 percent for the current study. Tu measurements were also made farther upstream so that turbulence decay rates could be calculated as needed for computational inlet boundary conditions. Downstream flow field measurements were obtained using a pneumatic five-hole pitch/yaw probe located in a survey plane 7 percent axial chord aft of the blade trailing edge and covering three blade passages. Blade and endwall static pressures were acquired for each flow condition as well. The blade loading data show that the suction surface separation that was evident at many of the low Tu conditions has been eliminated. At

  20. Evaluating Moisture Control of Variable-Capacity Heat Pumps in Mechanically Ventilated, Low-Load Homes in Climate Zone 2A

    Energy Technology Data Exchange (ETDEWEB)

    Eric Martin, Chuck Withers, Janet McIlvaine, Dave Chasar, and David Beal

    2018-03-29

    Low-load homes can present a challenge when selecting appropriate space-conditioning equipment. Conventional, fixed-capacity heating and cooling equipment is often oversized for small homes, causing increased first costs and operating costs. This report evaluates the performance of variable-capacity comfort systems, with a focus on inverter-driven, variable-capacity systems, as well as proposed system enhancements.