WorldWideScience

Sample records for high speed turbine

  1. Some design aspects of high-speed vertical-axis wind turbines

    National Research Council Canada - National Science Library

    Templin, R. J; South, P

    1977-01-01

    ... (rotor height to diameter ratio, solidity, number of blades, etc.) for high-speed vertical-axis wind turbines from kilowatt to megawatt sizes and shows that very large turbines are theoretically feasible...

  2. An air bearing system for small high speed gas turbines

    Science.gov (United States)

    Turner, A. B.; Davies, S. J.; Nimir, Y. L.

    1994-03-01

    This paper describes the second phase of an experimental program concerning the application of air bearings to small turbomachinery test rigs and small gas turbines. The first phase examined externally pressurized (EP) journal bearings, with a novel EP thrust bearing, for application to 'warm air' test rigs, and was entirely successful at rotational speeds in excess of 100,000 rpm. This second phase examined several designs of tilting pad-spiring journal bearings, one with a novel form of externally pressurized pad, but all using the original EP thrust bearing. The designs tested are described, including some oscillogram traces, for tests up to a maximum of 70,000 rpm; the most successful using a carbon pad-titanium beam spring arrangement. The thrust bearing which gave trouble-free operation throughout, is also described. The results of an original experiment to measure the 'runway speed' of a radial inflow turbine are also presented, which show that overspeeds of 58 percent above the design speed can result from free-power turbine coupling failure.

  3. The effect of tip speed ratio on a vertical axis wind turbine at high Reynolds numbers

    Science.gov (United States)

    Parker, Colin M.; Leftwich, Megan C.

    2016-05-01

    This work visualizes the flow surrounding a scaled model vertical axis wind turbine at realistic operating conditions. The model closely matches geometric and dynamic properties—tip speed ratio and Reynolds number—of a full-size turbine. The flow is visualized using particle imaging velocimetry (PIV) in the midplane upstream, around, and after (up to 4 turbine diameters downstream) the turbine, as well as a vertical plane behind the turbine. Time-averaged results show an asymmetric wake behind the turbine, regardless of tip speed ratio, with a larger velocity deficit for a higher tip speed ratio. For the higher tip speed ratio, an area of averaged flow reversal is present with a maximum reverse flow of -0.04U_∞. Phase-averaged vorticity fields—achieved by syncing the PIV system with the rotation of the turbine—show distinct structures form from each turbine blade. There were distinct differences in results by tip speed ratios of 0.9, 1.3, and 2.2 of when in the cycle structures are shed into the wake—switching from two pairs to a single pair of vortices being shed—and how they convect into the wake—the middle tip speed ratio vortices convect downstream inside the wake, while the high tip speed ratio pair is shed into the shear layer of the wake. Finally, results show that the wake structure is much more sensitive to changes in tip speed ratio than to changes in Reynolds number.

  4. Vibration characteristics of dental high-speed turbines and speed-increasing handpieces.

    Science.gov (United States)

    Poole, Ruth L; Lea, Simon C; Dyson, John E; Shortall, Adrian C C; Walmsley, A Damien

    2008-07-01

    Vibrations of dental handpieces may contribute to symptoms of hand-arm vibration syndrome in dental personnel and iatrogenic enamel cracking in teeth. However, methods for measuring dental handpiece vibrations have previously been limited and information about vibration characteristics is sparse. This preliminary study aimed to use a novel approach to assess the vibrations of unloaded high-speed handpieces in vitro. Maximum vibration displacement amplitudes of five air turbines and two speed-increasing handpieces were recorded whilst they were operated with and without a rotary cutting instrument (RCI) using a scanning laser vibrometer (SLV). RCI rotation speeds, calculated from frequency peaks, were consistent with expected values. ANOVA statistical analysis indicated significant differences in vibrations between handpiece models (p0.11). Operating handpieces with a RCI resulted in greater vibrations than with no RCI (pmeasurement exceeded 4 microm for the handpieces in the current test setup (implying that these vibrations may be unlikely to cause adverse effects), this study has formed the basis for future work which will include handpiece vibration measurements whilst cutting under clinically representative loads.

  5. Small Horizontal Axis Wind Turbine under High Speed Operation: Study of Power Evaluation

    Science.gov (United States)

    Moh. M. Saad, Magedi; Mohd, Sofian Bin; Zulkafli, Mohd Fadhli Bin; Abdullah, Aslam Bin; Rahim, Mohammad Zulafif Bin; Subari, Zulkhairi Bin; Rosly, Nurhayati Binti

    2017-10-01

    Mechanical energy is produced through the rotation of wind turbine blades by air that convert the mechanical energy into electrical energy. Wind turbines are usually designed to be use for particular applications and design characteristics may vary depending on the area of use. The variety of applications is reflected on the size of turbines and their infrastructures, however, performance enhancement of wind turbine may start by analyzing the small horizontal axis wind turbine (SHAWT) under high wind speed operation. This paper analyzes the implementations of SHAWT turbines and investigates their performance in both simulation and real life. Depending on the real structure of the rotor geometry and aerodynamic test, the power performance of the SHAWT was simulated using ANSYS-FLUENT software at different wind speed up to 33.33 m/s (120km/h) in order to numerically investigate the actual turbine operation. Dynamic mesh and user define function (UDF) was used for revolving the rotor turbine via wind. Simulation results were further validated by experimental data and hence good matching was yielded. And for reducing the energy producing cost, car alternator was formed to be used as a small horizontal wind turbine. As a result, alternator-based turbine system was found to be a low-cost solution for exploitation of wind energy.

  6. A reference Pelton turbine - High speed visualization in the rotating frame

    Science.gov (United States)

    Solemslie, Bjørn W.; Dahlhaug, Ole G.

    2016-11-01

    To enable a detailed study the flow mechanisms effecting the flow within the reference Pelton runner designed at the Waterpower Laboratory (NTNLT) a flow visualization system has been developed. The system enables high speed filming of the hydraulic surface of a single bucket in the rotating frame of reference. It is built with an angular borescopes adapter entering the turbine along the rotational axis and a borescope embedded within a bucket. A stationary high speed camera located outside the turbine housing has been connected to the optical arrangement by a non-contact coupling. The view point of the system includes the whole hydraulic surface of one half of a bucket. The system has been designed to minimize the amount of vibrations and to ensure that the vibrations felt by the borescope are the same as those affecting the camera. The preliminary results captured with the system are promising and enable a detailed study of the flow within the turbine.

  7. Experiences with the hydraulic design of the high specific speed Francis turbine

    International Nuclear Information System (INIS)

    Obrovsky, J; Zouhar, J

    2014-01-01

    The high specific speed Francis turbine is still suitable alternative for refurbishment of older hydro power plants with lower heads and worse cavitation conditions. In the paper the design process of such kind of turbine together with the results comparison of homological model tests performed in hydraulic laboratory of ČKD Blansko Engineering is introduced. The turbine runner was designed using the optimization algorithm and considering the high specific speed hydraulic profile. It means that hydraulic profiles of the spiral case, the distributor and the draft tube were used from a Kaplan turbine. The optimization was done as the automatic cycle and was based on a simplex optimization method as well as on a genetic algorithm. The number of blades is shown as the parameter which changes the resulting specific speed of the turbine between n s =425 to 455 together with the cavitation characteristics. Minimizing of cavitation on the blade surface as well as on the inlet edge of the runner blade was taken into account during the design process. The results of CFD analyses as well as the model tests are mentioned in the paper

  8. Experiences with the hydraulic design of the high specific speed Francis turbine

    Science.gov (United States)

    Obrovsky, J.; Zouhar, J.

    2014-03-01

    The high specific speed Francis turbine is still suitable alternative for refurbishment of older hydro power plants with lower heads and worse cavitation conditions. In the paper the design process of such kind of turbine together with the results comparison of homological model tests performed in hydraulic laboratory of ČKD Blansko Engineering is introduced. The turbine runner was designed using the optimization algorithm and considering the high specific speed hydraulic profile. It means that hydraulic profiles of the spiral case, the distributor and the draft tube were used from a Kaplan turbine. The optimization was done as the automatic cycle and was based on a simplex optimization method as well as on a genetic algorithm. The number of blades is shown as the parameter which changes the resulting specific speed of the turbine between ns=425 to 455 together with the cavitation characteristics. Minimizing of cavitation on the blade surface as well as on the inlet edge of the runner blade was taken into account during the design process. The results of CFD analyses as well as the model tests are mentioned in the paper.

  9. 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.

  10. High speed, self-acting shaft seal. [for use in turbine engines

    Science.gov (United States)

    Ludwig, L. P.; Hady, W. F. (Inventor)

    1975-01-01

    A high-speed, self-acting circumferential type shaft seal for use in turbine engines is disclosed. One or more conventional circumferential ring seals having a central aperture are mounted in a housing. In three of the four embodiments of the invention, a helical groove and one or more dam seals are cut in the inner cylindrical surface of the one or more ring seals. In a fourth embodiment, two or more lift pads are disposed in surface contact with the inner cylindrical surface of the seal rings. To the outside of the lift pads, two dam seals are cut in the inner cylindrical surface of two of the ring seals. In each of the embodiments, a net outward radial force was produced during rotation of the turbine causing the ring seals to lift out of contact with the turbine shaft to minimize wear of the ring seals.

  11. A study on high speed coupling design for wind turbine using a finite element analysis

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyoung Woo; Kang, Jong Hun [Dept. of Mechatronics Engineering, Jungwon University, Geosan (Korea, Republic of); Han, Jeong Young [Pusan Educational Center for Computer Aided Machine Design, Pusan University, Busan (Korea, Republic of)

    2016-08-15

    The purpose of this study is to design a high speed coupling for 3 MW wind turbines and evaluate its structural stability. A basic analysis was performed to assess the structural stability of two materials, SPS6 steel plate and a composite material (Glass7628, Glass/Epoxy), in relation to misalignment in the axial and radial directions. The entire model was analyzed for a high speed coupling based on the SPS6 steel plate, which was found to have higher stability among the two materials, and safety factors were estimated for various levels of power delivery. To test the proposed high speed coupling design, a performance test was carried out to verify the stability of the final product.

  12. A study on high speed coupling design for wind turbine using a finite element analysis

    International Nuclear Information System (INIS)

    Lee, Hyoung Woo; Kang, Jong Hun; Han, Jeong Young

    2016-01-01

    The purpose of this study is to design a high speed coupling for 3 MW wind turbines and evaluate its structural stability. A basic analysis was performed to assess the structural stability of two materials, SPS6 steel plate and a composite material (Glass7628, Glass/Epoxy), in relation to misalignment in the axial and radial directions. The entire model was analyzed for a high speed coupling based on the SPS6 steel plate, which was found to have higher stability among the two materials, and safety factors were estimated for various levels of power delivery. To test the proposed high speed coupling design, a performance test was carried out to verify the stability of the final product

  13. Comparison of performances of full-speed turbine and half-speed turbine for nuclear power plants

    International Nuclear Information System (INIS)

    Wang Hu; Zhang Weihong; Zhang Qiang; Li Shaohua

    2010-01-01

    The steam turbines of nuclear power plants can be divided into the full-speed turbine and half-speed turbine. Different speed leads to differences in many aspects. Therefore, the rational speed is the key point in the selection of steam turbines. This paper contrasts the economy between the half-speed turbine and full-speed turbine, by calculating the relative internal efficiency of half-speed and full-speed steam turbines with the typical level of 1000 megawatt. At the same time, this paper also calculate the relative speed of high speed water drops in the last stage blade of half-speed turbine and full-speed turbine, to contrast the water erosion between the half-speed turbine and full-speed turbine. The results show that the relative internal efficiency of half-speed turbine is higher than that of the full-speed turbine, and that the security especially the ability of preventing water erosion of half-speed turbine is better than that of the full-speed turbine. (authors)

  14. Global Sensitivity Analysis of High Speed Shaft Subsystem of a Wind Turbine Drive Train

    Directory of Open Access Journals (Sweden)

    Saeed Asadi

    2018-01-01

    Full Text Available The wind turbine dynamics are complex and critical area of study for the wind industry. Quantification of the effective factors to wind turbine performance is valuable for making improvements to both power performance and turbine health. In this paper, the global sensitivity analysis of validated mathematical model for high speed shaft drive train test rig has been developed in order to evaluate the contribution of systems input parameters to the specified objective functions. The drive train in this study consists of a 3-phase induction motor, flexible shafts, shafts’ coupling, bearing housing, and disk with an eccentric mass. The governing equations were derived by using the Lagrangian formalism and were solved numerically by Newmark method. The variance based global sensitivity indices are introduced to evaluate the contribution of input structural parameters correlated to the objective functions. The conclusion from the current research provides informative beneficial data in terms of design and optimization of a drive train setup and also can provide better understanding of wind turbine drive train system dynamics with respect to different structural parameters, ultimately designing more efficient drive trains. Finally, the proposed global sensitivity analysis (GSA methodology demonstrates the detectability of faults in different components.

  15. Fault Tolerant and Optimal Control of Wind Turbines with Distributed High-Speed Generators

    Directory of Open Access Journals (Sweden)

    Urs Giger

    2017-01-01

    Full Text Available In this paper, the control scheme of a distributed high-speed generator system with a total amount of 12 generators and nominal generator speed of 7000 min − 1 is studied. Specifically, a fault tolerant control (FTC scheme is proposed to keep the turbine in operation in the presence of up to four simultaneous generator faults. The proposed controller structure consists of two layers: The upper layer is the baseline controller, which is separated into a partial load region with the generator torque as an actuating signal and the full-load operation region with the collective pitch angle as the other actuating signal. In addition, the lower layer is responsible for the fault diagnosis and FTC characteristics of the distributed generator drive train. The fault reconstruction and fault tolerant control strategy are tested in simulations with several actuator faults of different types.

  16. Gain-scheduled Linear Quadratic Control of Wind Turbines Operating at High Wind Speed

    DEFF Research Database (Denmark)

    Østergaard, Kasper Zinck; Stoustrup, Jakob; Brath, Per

    2007-01-01

    This paper addresses state estimation and linear quadratic (LQ) control of variable speed variable pitch wind turbines. On the basis of a nonlinear model of a wind turbine, a set of operating conditions is identified and a LQ controller is designed for each operating point. The controller gains...... are then interpolated linearly to get a control law for the entire operating envelope. A nonlinear state estimator is designed as a combination of two unscented Kalman filters and a linear disturbance estimator. The gain-scheduling variable (wind speed) is then calculated from the output of these state estimators...

  17. 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.

  18. Torque- and Speed Control of a Pitch Regulated Wind Turbine

    Energy Technology Data Exchange (ETDEWEB)

    Rasila, Mika

    2003-07-01

    Variable speed operated wind turbines has the potential to reduce fatigue loads, compared to fixed speed wind turbines. With pitch controllable rotor blades limitation of the power at high wind speeds is obtained. The thesis describes different controlling aspects concerning wind turbines and how these together can be used to optimize the system's performance. Torque control is used in order to achieve reduction on the mechanical loads on the drive-train for low wind speeds and limitation of power output for high wind speeds. In the high wind speed interval torque control is effective in order to limit the output power if a sufficiently fast pitch actuator is used. In the middle wind speed interval filter utilization can be used to give a reference signal to the controller in order to reduce speed and torque variations.

  19. An Airbreathing Launch Vehicle Design with Turbine-Based Low-Speed Propulsion and Dual Mode Scramjet High-Speed Propulsion

    Science.gov (United States)

    Moses, P. L.; Bouchard, K. A.; Vause, R. F.; Pinckney, S. Z.; Ferlemann, S. M.; Leonard, C. P.; Taylor, L. W., III; Robinson, J. S.; Martin, J. G.; Petley, D. H.

    1999-01-01

    Airbreathing launch vehicles continue to be a subject of great interest in the space access community. In particular, horizontal takeoff and horizontal landing vehicles are attractive with their airplane-like benefits and flexibility for future space launch requirements. The most promising of these concepts involve airframe integrated propulsion systems, in which the external undersurface of the vehicle forms part of the propulsion flowpath. Combining of airframe and engine functions in this manner involves all of the design disciplines interacting at once. Design and optimization of these configurations is a most difficult activity, requiring a multi-discipline process to analytically resolve the numerous interactions among the design variables. This paper describes the design and optimization of one configuration in this vehicle class, a lifting body with turbine-based low-speed propulsion. The integration of propulsion and airframe, both from an aero-propulsive and mechanical perspective are addressed. This paper primarily focuses on the design details of the preferred configuration and the analyses performed to assess its performance. The integration of both low-speed and high-speed propulsion is covered. Structural and mechanical designs are described along with materials and technologies used. Propellant and systems packaging are shown and the mission-sized vehicle weights are disclosed.

  20. Defining the Field of Existence of Shrouded Blades in High-Speed Gas Turbines

    Science.gov (United States)

    Belousov, Anatoliy I.; Nazdrachev, Sergeiy V.

    2018-01-01

    This work provides a method for determining the region of existence of banded blades of gas turbines for aircraft engines based on the analytical evaluation of tensile stresses in specific characteristic sections of the blade. This region is determined by the set of values of the parameter, which forms the law of distribution of the cross-sectional area of the cross-sections along the height of the airfoil. When seven independent parameters (gas-dynamic, structural and strength) are changed, the choice of the best option is proposed at the early design stage. As an example, the influence of the dimension of a turbine on the domain of the existence of banded blades is shown.

  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. HIGH EFFICIENCY TURBINE

    OpenAIRE

    VARMA, VIJAYA KRUSHNA

    2012-01-01

    Varma designed ultra modern and high efficiency turbines which can use gas, steam or fuels as feed to produce electricity or mechanical work for wide range of usages and applications in industries or at work sites. Varma turbine engines can be used in all types of vehicles. These turbines can also be used in aircraft, ships, battle tanks, dredgers, mining equipment, earth moving machines etc, Salient features of Varma Turbines. 1. Varma turbines are simple in design, easy to manufac...

  3. Low speed turbines for nuclear power plants

    International Nuclear Information System (INIS)

    Ugol'nikov, V.V.; Kosyak, Yu.F.; Virchenko, M.A.

    1975-01-01

    Work of the Kharkov turbine plant on planning and manufacture for nuclear power plants of low-speed (1500 rpm) turbines with a power of 500-1000 MW is described. The selection of a construction diagram for the turbine assembly, determined basically by the presence or absence of parts of average pressure, is considered. Special construction features of the condenser and turbine are described. Turbine K-500, with a rate of 1500 rpm, was calculated for operation in a two-loop nuclear power plant with saturated steam with intermediate separation and two-stage steam regeneration. On the base of this turbine, three models of 1000-MW turbines were developed. The first model has a cylinder of average pressure (TsSD) and a lateral condenser. The second has no TsSD but a low location of the condensers. The third has no TsSD and the condensers are located laterally. Calculations of the heat efficiency of the three types of turbines showed that several advantages are offered by the model with a TsSD. Better aerodynamic properties of the exhaust nozzles and condensers with lateral location allows decreasing the specific heat consumption to 0.5-1% or, at the same power, a 10-20% decrease in cooling water consumption

  4. Pressure measurements and high speed visualizations of the cavitation phenomena at deep part load condition in a Francis turbine

    International Nuclear Information System (INIS)

    Yamamoto, K; Müller, A; Favrel, A; Landry, C; Avellan, F

    2014-01-01

    In a hydraulic power plant, it is essential to provide a reliable, sustainable and flexible energy supply. In recent years, in order to cover the variations of the renewable electricity production, hydraulic power plants are demanded to operate with more extended operating range. Under these off-design conditions, a hydraulic turbine is subject to cavitating swirl flow at the runner outlet. It is well-known that the helically/symmetrically shaped cavitation develops at the runner outlet in part load/full load condition, and it gives severe damage to the hydraulic systems under certain conditions. Although there have been many studies about partial and full load conditions, contributions reporting the deep part load condition are limited, and the cavitation behaviour at this condition is not yet understood. This study aims to unveil the cavitation phenomena at deep part load condition by high speed visualizations focusing on the draft tube cone as well as the runner blade channel, and pressure fluctuations associated with the phenomena were also investigated

  5. Cavitation on a scaled-down model of a Francis turbine guide vane: high-speed imaging and PIV measurements

    Science.gov (United States)

    Pervunin, K. S.; Timoshevskiy, M. V.; Churkin, S. A.; Kravtsova, A. Yu; Markovich, D. M.; Hanjalić, K.

    2015-12-01

    Cavitation on two symmetric foils, a NACA0015 hydrofoil and a scaled-down model of a Francis turbine guide vane (GV), was investigated by high-speed visualization and PIV. At small attack angles the differences between the profiles of the mean and fluctuating velocities for both hydrofoils were shown to be insignificant. However, at the higher angle of incidence, flow separation from the GV surface was discovered for quasi-steady regimes including cavitation-free and cavitation inception cases. The flow separation leads to the appearance of a second maximum in velocity fluctuations distributions downstream far from the GV surface. When the transition to unsteady regimes occurred, the velocity distributions became quite similar for both foils. Additionally, for the GV an unsteady regime characterized by asymmetric spanwise variations of the sheet cavity length along with alternating periodic detachments of clouds between the sidewalls of the test channel was for the first time visualized. This asymmetric behaviour is very likely to be governed by the cross instability that was recently described by Decaix and Goncalvès [8]. Moreover, it was concluded that the existence of the cross instability is independent on the test body shape and its aspect ratio.

  6. 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.

  7. 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.

  8. 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.

  9. Numerical Study on the Effect of Swept Blade on the Aerodynamic Performance of Wind Turbine at High Tip Speed Ratio

    International Nuclear Information System (INIS)

    Zuo, H M; Liu, C; Yang, H; Wang, F

    2016-01-01

    The current situation is that the development of high speed wind energy saturates gradually, therefore, it is highly necessary to develop low speed wind energy. This paper, based on a specific straight blade and by using Isight, a kind of multidiscipline optimization software, which integrates ICEM (Integrated Computer Engineering and Manufacturing) and CFD (Computational Fluid Dynamics) software, optimizes the blade stacking line (the centers of airfoil from blade root to tip) and acquires the optimization swept blade shape. It is found that power coefficient C p of swept blade is 3.2% higher than that of straight blade at the tip speed ratio of 9.82, that the thrust of swept blade receives is obviously less than that of straight blade. Inflow angle of attack and steam line on the suction of the swept and straight blade are also made a comparison. (paper)

  10. Heat transfer measurements on an incidence-tolerant low pressure turbine blade in a high speed linear cascade at low to moderate Reynolds numbers

    Science.gov (United States)

    Moualeu, Leolein Patrick Gouemeni

    Runway-independent aircraft are expected to be the future for short-haul flights by improving air transportation and reducing area congestion encountered in airports. The Vehicle Systems Program of NASA identified a Large Civil Tilt-Rotor, equipped with variable-speed power-turbine engines, as the best concept. At cruise altitude, the engine rotor-speed will be reduced by as much as the 50% of take-off speed. The large incidence variation in the low pressure turbine associated with the change in speed can be detrimental to the engine performance. Low pressure turbine blades in cruise altitude are more predisposed to develop regions of boundary layer separation. Typical phenomenon such as impinging wakes on downstream blades and mainstream turbulences enhance the complexity of the flow in low pressure turbines. It is therefore important to be able to understand the flow behavior to accurately predict the losses. Research facilities are seldom able to experimentally reproduce low Reynolds numbers at relevant engine Mach number. Having large incidence swing as an additional parameter in the investigation of the boundary layer development, on a low pressure turbine blade, makes this topic unique and as a consequence requires a unique facility to conduct the experimental research. The compressible flow wind tunnel facility at the University of North Dakota had been updated to perform steady state experiments on a modular-cascade, designed to replicate a large variation of the incidence angles. The high speed and low Reynolds number facility maintained a sealed and closed loop configuration for each incidence angle. The updated facility is capable to produce experimental Reynolds numbers as low as 45,000 and as high as 570,000 at an exit Mach number of 0.72. Pressure and surface temperature measurements were performed at these low pressure turbine conditions. The present thesis investigates the boundary layer development on the surface of an Incidence-tolerant blade. The

  11. [Comparative study of complications among routine method,high speed turbine handpiece and piezosurgery device after extraction of impacted wisdom teeth].

    Science.gov (United States)

    Guo, Zhao-zhong; Zhang, Heng; Li, Yan; Li, Xin; Liu, Yin; Wang, Yang; Yuan, Chun-xia; Liu, Xue

    2012-04-01

    To investigate complications in extraction of complicated impacted wisdom teeth whose root apex near to the inferior alveolar nerve(IAN) by using routine method(chisels),high speed turbine handpiece and piezosurgery device respectively. Three hundred qualified patients with impacted wisdom teeth were divided into three groups randomly,one hundred patients in group A were extracted by routine method, one hundred patients in group B were extracted by high speed turbine handpiece, and one hundred patients in group C were extracted by piezosurgery device. The operation time, postoperative pain duration,dry socket and IAN injury were compared between each two groups. All statistical analysis was performed using SPSS 13.0 software package. Differences between groups were compared using a paired t test (quantitative data) or Chi-square test (qualitative data). The operation time in group A was(14.12±0.12)min, (7.22±0.15)min in group B, (25.23±0.32)min in group C; Significant difference was found between group A and group B(Ppiezosurgery device is more effective in reducing postoperative complications.

  12. 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)

  13. 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...

  14. On the Response of a Micro Wind Turbine to Wind-Speed Change

    OpenAIRE

    烏谷, 隆; 渡辺, 公彦; 大屋, 裕二

    2004-01-01

    To improve the efficiency of a wind turbine, it is more effective to use high-speed wind. A method collecting wind to get high-speed wind was experimentally studied. It was found that the brimmed diffuser was a good device to get high-speed wind. The brimmed diffuser accelerated approaching wind, and wind speed near its inlet became about 1.7 times. Using this brimmed diffuser, we have made a new micro wind turbine and been carrying out field experiment. In order realize the properties of the...

  15. 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.

  16. High-speed laser diagnostics for the study of flame dynamics in a lean premixed gas turbine model combustor

    Science.gov (United States)

    Boxx, Isaac; Arndt, Christoph M.; Carter, Campbell D.; Meier, Wolfgang

    2012-03-01

    A series of measurements was taken on two technically premixed, swirl-stabilized methane-air flames (at overall equivalence ratios of ϕ = 0.73 and 0.83) in an optically accessible gas turbine model combustor. The primary diagnostics used were combined planar laser-induced fluorescence of the OH radical and stereoscopic particle image velocimetry (PIV) with simultaneous repetition rates of 10 kHz and a measurement duration of 0.8 s. Also measured were acoustic pulsations and OH chemiluminescence. Analysis revealed strong local periodicity in the thermoacoustically self-excited (or ` noisy') flame (ϕ = 0.73) in the regions of the flow corresponding to the inner shear layer and the jet-inflow. This periodicity appears to be the result of a helical precessing vortex core (PVC) present in that region of the combustor. The PVC has a precession frequency double (at 570 Hz) that of the thermo-acoustic pulsation (at 288 Hz). A comparison of the various data sets and analysis techniques applied to each flame suggests a strong coupling between the PVC and the thermo-acoustic pulsation in the noisy flame. Measurements of the stable (` quiet') flame (ϕ = 0.83) revealed a global fluctuation in both velocity and heat-release around 364 Hz, but no clear evidence of a PVC.

  17. 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...

  18. 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...

  19. 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

  20. Design of large permanent magnetized synchronous electric machines: Low speed, high torque machines - generator for direct driven wind turbine - motor for rim driven thruster

    Energy Technology Data Exchange (ETDEWEB)

    Kroevel, Oeystein

    2011-02-15

    This work presents the design of two prototype permanent magnetized electric machines for two different applications where large permanent magnet machines might be used. Existing technology have been used as the fundament for new design and adapted to new applications, contributing, hopefully, to the development of better and more environmental friendly energy conversion. The first application presented is represented with a prototype made in cooperation with the industry in which a PM-motor is integrated into a propeller unit. Both because of the industrial connection, and the integration between the PM-motor and the propeller, the choices made for the PM-motor are conservative trying to reduce the risk. The direct rim driven thruster prototype includes a surface mounted radial flux permanent magnet machine (SM RFPM) with fractional slot winding with a q around 1. Other engineering features were introduced to make the integration of propeller and motor feasible, but without the PM-machine the thruster would not have reached the performance demand. An important part of the project was to show that the SM RFPM enables this solution, providing high performance with a large air gap. The prototype has been tested in sea, under harsh conditions, and even though the magnets have been exposed directly to sea water and been visible corroded, the electric motor still performs well within the specifications. The second application is represented with a prototype PM-generator for wind turbines. This is an example of a new, very low speed high torque machine. The generator is built to test phenomena regarding concentrated coils, and as opposed to the first application, being a pure academic university project, its success is not connected to its performance, but with the prototype's ability to expose the phenomena in question. The prototype, or laboratory model, of the generator for direct driven wind turbines features SM RFPM with concentrated coils (CC). An opportunity

  1. 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.

  2. Robust Control Analysis of Hydraulic Turbine Speed

    Science.gov (United States)

    Jekan, P.; Subramani, C.

    2018-04-01

    An effective control strategy for the hydro-turbine governor in time scenario is adjective for this paper. Considering the complex dynamic characteristic and the uncertainty of the hydro-turbine governor model and taking the static and dynamic performance of the governing system as the ultimate goal, the designed logic combined the classical PID control theory with artificial intelligence used to obtain the desired output. The used controller will be a variable control techniques, therefore, its parameters can be adaptively adjusted according to the information about the control error signal.

  3. 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

  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. A miniaturized piezoelectric turbine with self-regulation for increased air speed range

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Hailing, E-mail: h.fu14@imperial.ac.uk; Yeatman, Eric M. [Department of Electrical and Electronic Engineering, Imperial College London, London SW7 2AZ (United Kingdom)

    2015-12-14

    This paper presents the design and demonstration of a piezoelectric turbine with self-regulation for increased air speed range. The turbine's transduction is achieved by magnetic “plucking” of a piezoelectric beam by the passing rotor. The increased speed range is achieved by the self-regulating mechanism which can dynamically adjust the magnetic coupling between the magnets on the turbine rotor and the piezoelectric beam using a micro-spring. The spring is controlled passively by the centrifugal force of the magnet on the rotor. This mechanism automatically changes the relative position of the magnets at different rotational speeds, making the coupling weak at low airflow speeds and strong at high speeds. Hence, the device can start up with a low airflow speed, and the output power can be ensured when the airflow speed is high. A theoretical model was established to analyse the turbine's performance, advantages, and to optimize its design parameters. A prototype was fabricated and tested in a wind tunnel. The start-up airflow speed was 2.34 m/s, showing a 30% improvement against a harvester without the mechanism.

  6. A miniaturized piezoelectric turbine with self-regulation for increased air speed range

    International Nuclear Information System (INIS)

    Fu, Hailing; Yeatman, Eric M.

    2015-01-01

    This paper presents the design and demonstration of a piezoelectric turbine with self-regulation for increased air speed range. The turbine's transduction is achieved by magnetic “plucking” of a piezoelectric beam by the passing rotor. The increased speed range is achieved by the self-regulating mechanism which can dynamically adjust the magnetic coupling between the magnets on the turbine rotor and the piezoelectric beam using a micro-spring. The spring is controlled passively by the centrifugal force of the magnet on the rotor. This mechanism automatically changes the relative position of the magnets at different rotational speeds, making the coupling weak at low airflow speeds and strong at high speeds. Hence, the device can start up with a low airflow speed, and the output power can be ensured when the airflow speed is high. A theoretical model was established to analyse the turbine's performance, advantages, and to optimize its design parameters. A prototype was fabricated and tested in a wind tunnel. The start-up airflow speed was 2.34 m/s, showing a 30% improvement against a harvester without the mechanism

  7. High speed atom source

    International Nuclear Information System (INIS)

    Hoshino, Hitoshi.

    1990-01-01

    In a high speed atom source, since the speed is not identical between ions and electrons, no sufficient neutralizing effect for ionic rays due to the mixing of the ionic rays and the electron rays can be obtained failing to obtain high speed atomic rays at high density. In view of the above, a speed control means is disposed for equalizing the speed of ions forming ionic rays and the speed of electrons forming electron rays. Further, incident angle of the electron rays and/or ionic rays to a magnet or an electrode is made variable. As a result, the relative speed between the ions and the electrons to the processing direction is reduced to zero, in which the probability of association between the ions and the electrons due to the coulomb force is increased to improve the neutralizing efficiency to easily obtain fine and high density high speed electron rays. Further, by varying the incident angle, a track capable of obtaining an ideal mixing depending on the energy of the neutralized ionic rays is formed. Since the high speed electron rays has such high density, they can be irradiated easily to the minute region of the specimen. (N.H.)

  8. 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....

  9. Voltage sag influence on fatigue life of the drivetrain of fixed speed wind turbines

    DEFF Research Database (Denmark)

    Veluri, Badrinath; Santos-Martin, David; Jensen, Henrik Myhre

    2011-01-01

    Occurrence of voltage sags due to electrical grid faults and other network disturbances generate transients of the generator electromagnetic torque which result in significant high stresses and noticeable vibrations for the wind turbine mechanical system and may also have a detrimental effect...... on the fatigue life of important drivetrain components. The high penetration of wind energy in the electrical grids demands new requirements for the operation of wind energy conversion systems. Although fixed speed wind turbine technology is nowadays replaced by variable speed wind turbines. In some countries...... by the stator flux oscillations which cause high transients of the generator electromagnetic torque. This paper focuses in estimating the resulting significant stresses transients due to the electromagnetic torque transients, which transmits to the wind turbine mechanical system that may have a detrimental...

  10. 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).

  11. 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...

  12. Unsteady flow simulations of Pelton turbine at different rotational speeds

    Directory of Open Access Journals (Sweden)

    Minsuk Choi

    2015-11-01

    Full Text Available This article presents numerical simulations of a small Pelton turbine suitable for desalination system. A commercial flow solver was adopted to resolve difficulties in the numerical simulation for Pelton turbine such as the relative motion of the turbine runner to the injector and two-phase flow of water and air. To decrease the numerical diffusion of the water jet, a new topology with only hexagonal mesh was suggested for the computational mesh around the complex geometry of a bucket. The predicted flow coefficient, net head coefficient, and overall efficiency showed a good agreement with the experimental data. Based on the validation of the numerical results, the pattern of wet area on the bucket inner surface has been analyzed at different rotational speeds, and an attempt to find the connection between rotational speeds, torque, and efficiency has been made.

  13. High speed data acquisition

    International Nuclear Information System (INIS)

    Cooper, P.S.

    1997-07-01

    A general introduction to high speed data acquisition system techniques in modern particle physics experiments is given. Examples are drawn from the SELEX(E78 1) high statistics charmed baryon production and decay experiment now taking data at Fermilab

  14. 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.

  15. Methods for calculating the speed-up characteristics of steam-water turbines

    International Nuclear Information System (INIS)

    Golovach, E.A.

    1981-01-01

    The methods of approximate and specified calculations of speed- up characteristics of steam-water turbines are considered. The specified non-linear method takes into account change of thermal efficiency, heat drop and losses in the turbine as well as vacuum break-up the condenser. Speed-up characteristics of the K-1000-60-1500 turbine are presented. The calculational results obtained by the non-linear method are compared with the calculations conducted by the approximate linearized method. Differences in the frequency speed up of the turbine rotor rotation calculated by the two methods constitute only 0.5-2.0%. That is why it is necessary to take into account in the specified calculations first of all the most important factors following the rotor speed- up in the following consequence: valve shift of the high pressure cylinder (HPC); steam volume in front of the HPC; shift of the valves behind the separator-steam superheater (SSS); steam volumes and moisture boiling in the SSS; steam consumption for regenerating heating of feed water, steam volumes at the intermediate elements of the turbine, losses in the turbine, heat drop and thermal efficiency [ru

  16. 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

  17. Master equation and runaway speed of the Francis turbine

    Science.gov (United States)

    Zhang, Zh.

    2018-04-01

    The master equation of the Francis turbine is derived based on the combination of the angular momentum (Euler) and the energy laws. It relates the geometrical design of the impeller and the regulation settings (guide vane angle and rotational speed) to the discharge and the power output. The master equation, thus, enables the complete characteristics of a given Francis turbine to be easily computed. While applying the energy law, both the shock loss at the impeller inlet and the swirling loss at the impeller exit are taken into account. These are main losses which occur at both the partial load and the overloads and, thus, dominantly influence the characteristics of the Francis turbine. They also totally govern the discharge of the water through the impeller when the impeller is found in the standstill. The computations have been performed for the discharge, the hydraulic torque and the hydraulic efficiency. They were also compared with the available measurements on a model turbine. Excellent agreement has been achieved. The computations also enable the runaway speed of the Francis turbine and the related discharge to be determined as a function of the setting angle of the guide vanes.

  18. 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)

  19. High-Speed Photography

    International Nuclear Information System (INIS)

    Paisley, D.L.; Schelev, M.Y.

    1998-01-01

    The applications of high-speed photography to a diverse set of subjects including inertial confinement fusion, laser surgical procedures, communications, automotive airbags, lightning etc. are briefly discussed. (AIP) copyright 1998 Society of Photo-Optical Instrumentation Engineers

  20. High speed heterostructure devices

    CERN Document Server

    Beer, Albert C; Willardson, R K; Kiehl, Richard A; Sollner, T C L Gerhard

    1994-01-01

    Volume 41 includes an in-depth review of the most important, high-speed switches made with heterojunction technology. This volume is aimed at the graduate student or working researcher who needs a broad overview andan introduction to current literature. Key Features * The first complete review of InP-based HFETs and complementary HFETs, which promise very low power and high speed * Offers a complete, three-chapter review of resonant tunneling * Provides an emphasis on circuits as well as devices.

  1. Influence of speed and frequency towards the automotive turbocharger turbine performance under pulsating flow conditions

    International Nuclear Information System (INIS)

    Padzillah, M.H.; Rajoo, S.; Martinez-Botas, R.F.

    2014-01-01

    Highlights: • 3D CFD modeling of a turbocharger turbine with pulsating flow. • Characterization based on turbine speed and frequency. • Speed has higher influence on turbine performance compared to frequency. • Detailed localized flow behavior are shown for better understanding. - Abstract: The ever-increasing demand for low carbon applications in automotive industry has intensified the development of highly efficient engines and energy recovery devices. Even though there are significant developments in the alternative powertrains such as full electric, their full deployment is hindered by high costing and unattractive life-cycle energy and emission balance. Thus powertrain based on highly efficient internal combustion engines are still considered to be the mainstream for years to come. Traditionally, turbocharger has been an essential tool to boost the engine power, however in recent years it is seen as an enabling technology for engine downsizing. It is a well-known fact that a turbocharger turbine in an internal combustion engine operates in a highly pulsating exhaust flow. There are numerous studies looking into the complex interaction of the pulsating exhaust gas within the turbocharger turbine, however the phenomena is still not fully integrated into the design stage. Industry practice is still to design and match the turbine to an engine based on steady performance maps. The current work is undertaken with the mind to move one step closer towards fully integrating the pulsating flow performance into the turbocharger turbine design. This paper presents the development efforts and results from a full 3-D CFD model of a turbocharger turbine stage. The simulations were conducted at 30,000 rpm and 48,000 rpm (50% and 80% design speed respectively) for both 20 Hz and 80 Hz pulsating flow inlet conditions. Complete validation procedure using cold-flow experimental data is also described. The temporal and spatial resolutions of the incidence angle at the

  2. 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...

  3. Generalised pole-placement control of steam turbine speed

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-del-Busto, R. [ITESM, Cuernavaca (Mexico). Div. de Ingenieria y Ciencias; Munoz, J. [ITESM, Xochimilco (Mexico). Div. de Ingenieria y Ciencias

    1996-12-31

    An application of a pole-placement self-tuning predictive control algorithm is developed to regulate speed of a power plant steam turbine model. Two types of system representation (CARMA and CARIMA) are used to test the control algorithm. Simulation results show that when using a CARMA model better results are produced. Two further comparisons are made when using a PI controller and a generalised predictive controller. (author)

  4. High speed drying of saturated steam

    International Nuclear Information System (INIS)

    Marty, C.; Peyrelongue, J.P.

    1993-01-01

    This paper describes the development of the drying process for the saturated steam used in the PWR nuclear plant turbines in order to prevent negative effects of water on turbine efficiency, maintenance costs and equipment lifetime. The high speed drying concept is based on rotating the incoming saturated steam in order to separate water which is more denser than the steam; the water film is then extracted through an annular slot. A multicellular modular equipment has been tested. Applications on high and low pressure extraction of various PWR plants are described (Bugey, Loviisa)

  5. WIND TURBINE OPERATION PARAMETER CHARACTERISTICS AT A GIVEN WIND SPEED

    Directory of Open Access Journals (Sweden)

    Zdzisław Kamiński

    2014-06-01

    Full Text Available This paper discusses the results of the CFD simulation of the flow around Vertical Axis Wind Turbine rotor. The examined rotor was designed following patent application no. 402214. The turbine operation is characterised by parameters, such as opening angle of blades, power, torque, rotational velocity at a given wind velocity. Those parameters have an impact on the performance of entire assembly. The distribution of forces acting on the working surfaces in the turbine can change, depending on the angle of rotor rotation. Moreover, the resultant force derived from the force acting on the oncoming and leaving blades should be as high as possible. Accordingly, those parameters were individually simulated over time for each blade in three complete rotations. The attempts to improve the performance of the entire system resulted in a new research trend to improve the performance of working turbine rotor blades.

  6. 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....

  7. 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...

  8. 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...

  9. Effectiveness of Changing Wind Turbine Cut-in Speed to Reduce Bat Fatalities at Wind Facilities

    Energy Technology Data Exchange (ETDEWEB)

    Huso, Manuela M. P. [Oregon State Univ., Corvallis, OR (United States); Hayes, John P. [Univ. of Florida, Gainesville, FL (United States)

    2009-04-01

    This report details an experiment on the effectiveness of changing wind turbine cut-in speed on reducing bat fatality from wind turbines at the Casselman Wind Project in Somerset County, Pennsylvania.

  10. Neuron-Adaptive PID Based Speed Control of SCSG Wind Turbine System

    Directory of Open Access Journals (Sweden)

    Shan Zuo

    2014-01-01

    Full Text Available In searching for methods to increase the power capacity of wind power generation system, superconducting synchronous generator (SCSG has appeared to be an attractive candidate to develop large-scale wind turbine due to its high energy density and unprecedented advantages in weight and size. In this paper, a high-temperature superconducting technology based large-scale wind turbine is considered and its physical structure and characteristics are analyzed. A simple yet effective single neuron-adaptive PID control scheme with Delta learning mechanism is proposed for the speed control of SCSG based wind power system, in which the RBF neural network (NN is employed to estimate the uncertain but continuous functions. Compared with the conventional PID control method, the simulation results of the proposed approach show a better performance in tracking the wind speed and maintaining a stable tip-speed ratio, therefore, achieving the maximum wind energy utilization.

  11. High speed network sampling

    OpenAIRE

    Rindalsholt, Ole Arild

    2005-01-01

    Master i nettverks- og systemadministrasjon Classical Sampling methods play an important role in the current practice of Internet measurement. With today’s high speed networks, routers cannot manage to generate complete Netflow data for every packet. They have to perform restricted sampling. This thesis summarizes some of the most important sampling schemes and their applications before diving into an analysis on the effect of sampling Netflow records.

  12. High temperature turbine engine structure

    Energy Technology Data Exchange (ETDEWEB)

    Carruthers, W.D.; Boyd, G.L.

    1993-07-20

    A hybrid ceramic/metallic gas turbine is described comprising; a housing defining an inlet, an outlet, and a flow path communicating the inlet with the outlet for conveying a flow of fluid through the housing, a rotor member journaled by the housing in the flow path, the rotor member including a compressor rotor portion rotatively inducting ambient air via the inlet and delivering this air pressurized to the flow path downstream of the compressor rotor, a combustor disposed in the flow path downstream of the compressor receiving the pressurized air along with a supply of fuel to maintain combustion providing a flow of high temperature pressurized combustion products in the flow path downstream thereof, the rotor member including a turbine rotor portion disposed in the flow path downstream of the combustor and rotatively expanding the combustion products toward ambient for flow from the turbine engine via the outlet, the turbine rotor portion providing shaft power driving the compressor rotor portion and an output shaft portion of the rotor member, a disk-like metallic housing portion journaling the rotor member to define a rotational axis therefore, and a disk-like annular ceramic turbine shroud member bounding the flow path downstream of the combustor and circumscribing the turbine rotor portion to define a running clearance therewith, the disk-like ceramic turbine shroud member having a reference axis coaxial with the rotational axis and being spaced axially from the metallic housing portion in mutually parallel concentric relation therewith and a plurality of spacers disposed between ceramic disk-like shroud member and the metallic disk-like housing portion and circumferentially spaced apart, each of the spacers having a first and second end portion having an end surface adjacent the shroud member and the housing portion respectively, the end surfaces having a cylindrical curvature extending transversely relative to the shroud member and the housing portion.

  13. High speed rotary drum

    Energy Technology Data Exchange (ETDEWEB)

    Sagara, H

    1970-03-25

    A high speed rotary drum is disclosed in which the rotor vessel is a double-wall structure comprising an inner wave-shaped pipe inserted coaxially within an outer straight pipe, the object being to provide a strengthened composite light-weight structure. Since force induced axial deformation of the straight pipe and radial deformation of the corrugated pipe are small, the composite effectively resists external forces and, if the waves of the inner pipe are given a sufficient amplitude, the thickness of both pipes may be reduced to lower the overall weight. Thus high angular velocities can be obtained to separate U/sup 235/ from gaseous UF/sub 6/.

  14. 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.

  15. 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.

  16. 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...

  17. 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...

  18. High Speed Photomicrography

    Science.gov (United States)

    Hyzer, William G.

    1983-03-01

    One of the most challenging areas in applying high-speed photography and videography in the plant and laboratory is in the recording of rapid events at macro and microscopic scales. Depth of field, exposure efficiency, working distance, and required exposure time are all reduced as optical magnification is increased, which severely taxes the skill and ingenuity of workers interested in recording any fast moving phenomena through the microscope or with magnifying lenses. This paper defines the problems inherent in photographing within macro and microscopic ranges and offers a systematic approach to optimizing the selection of equipment and choice of applicable techniques.

  19. 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.

  20. 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...

  1. 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.

  2. Development of high temperature turbine

    Energy Technology Data Exchange (ETDEWEB)

    Takahara, Kitao; Nouse, Hiroyuki; Yoshida, Toyoaki; Minoda, Mitsuhiro; Matsusue, Katsutoshi; Yanagi, Ryoji

    1988-07-01

    For the contribution to the development of FJR710, high by-pass ratio turbofan engine, with the study for many years of the development of high efficiency turbine for the jet engine, the first technical prize from the Energy Resource Research Committee was awarded in April, 1988. This report introduced its technical contents. In order to improve the thermal efficiency and enlarge the output, it is very effective to raise the gas temperature at the inlet of gas turbine. For its purpose, by cooling the nozzle and moving blades and having those blades operate at lower temperature than that of the working limitation, they realized, for the first time in Japan, the technique of cooling turbine to heighten the operational gas temperature. By that technique, it was enabled to raise the gas temperature at the inlet of turbine, to 1,350/sup 0/C from 850/sup 0/C. This report explain many important points of study covering the basic test, visualizing flow experiment, material discussion and structural design in the process of development. (9 figs)

  3. Measuring the Dynamic Characteristics of a Low Specific Speed Pump—Turbine Model

    Directory of Open Access Journals (Sweden)

    Eve Cathrin Walseth

    2016-03-01

    Full Text Available This paper presents results from an experiment performed to obtain the dynamic characteristics of a reversible pump-turbine model. The characteristics were measured in an open loop system where the turbine initially was run on low rotational speed before the generator was disconnected allowing the turbine to go towards runaway. The measurements show that the turbine experience damped oscillations in pressure, speed and flow rate around runaway corresponding with presented stability criterion in published literature. Results from the experiment is reproduced by means of transient simulations. A one dimensional analytical turbine model for representation of the pump-turbine is used in the calculations. The simulations show that it is possible to reproduce the physics in the measurement by using a simple analytical model for the pump-turbine as long as the inertia of the water masses in the turbine are modeled correctly.

  4. Using wind speed from a blade-mounted flow sensor for power and load assessment on modern wind turbines

    DEFF Research Database (Denmark)

    Pedersen, Mads M.; Larsen, Torben J.; Madsen, Helge Aa

    2017-01-01

    In this paper an alternative method to evaluate power performance and loads on wind turbines using a blade-mounted flow sensor is investigated. The hypothesis is that the wind speed measured at the blades has a high correlation with the power and loads such that a power or load assessment can...... be performed from a few hours or days of measurements. In the present study a blade-mounted five-hole pitot tube is used as the flow sensor as an alternative to the conventional approach, where the reference wind speed is either measured at a nearby met mast or on the nacelle using lidar technology or cup...... anemometers. From the flow sensor measurements, an accurate estimate of the wind speed at the rotor plane can be obtained. This wind speed is disturbed by the presence of the wind turbine, and it is therefore different from the free-flow wind speed. However, the recorded wind speed has a high correlation...

  5. 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...

  6. 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.

  7. 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.

  8. Simulation model of an active-stall fixed-speed wind turbine controller

    Energy Technology Data Exchange (ETDEWEB)

    Jauch, C.; Hansen, A.D.; Sorensen, P.; Blaabjerg, F.

    2004-07-01

    This paper describes an active-stall wind turbine controller. The objective is to develop a general model of an active stall controller in order to simulate the operation of grid connected active stall wind turbines. The active stall turbine concept and its control strategies are presented and evaluated by simulations. The presented controller is described for continuous operation under all wind speeds from start-up wind speed to shut down wind speed. Due to its parametric implementation it is general i. e. it can represent different active stall wind turbine controllers and can be implemented in different simulation tools. (author)

  9. Multi-objective PID Optimization for Speed Control of an Isolated Steam Turbine using Gentic Algorithm

    OpenAIRE

    Sanjay Kr. Singh; D. Boolchandani; S.G. Modani; Nitish Katal

    2014-01-01

    This study focuses on multi-objective optimization of the PID controllers for optimal speed control for an isolated steam turbine. In complex operations, optimal tuning plays an imperative role in maintaining the product quality and process safety. This study focuses on the comparison of the optimal PID tuning using Multi-objective Genetic Algorithm (NSGA-II) against normal genetic algorithm and Ziegler Nichols methods for the speed control of an isolated steam turbine. Isolated steam turbine...

  10. 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.

  11. Prediction models for wind speed at turbine locations in a wind farm

    DEFF Research Database (Denmark)

    Knudsen, Torben; Bak, Thomas; Soltani, Mohsen

    2011-01-01

    In wind farms, individual turbines disturb the wind field by generating wakes that influence other turbines in the farm. From a control point of view, there is an interest in dynamic optimization of the balance between fatigue and production, and an understanding of the relationship between turbines...... on standard turbine measurements such as rotor speed and power produced, an effective wind speed, which represents the wind field averaged over the rotor disc, is derived. The effective wind speed estimator is based on a continuous–discrete extended Kalman filter that takes advantage of nonlinear time varying...... on the result related to effective wind speed, it is possible to predict wind speeds at neighboring turbines, with a separation of over 700 m, up to 1 min ahead reducing the error by 30% compared with a persistence method. The methodological results are demonstrated on data from an off-shore wind farm...

  12. Accounting for the speed shear in wind turbine power performance measurement

    DEFF Research Database (Denmark)

    Wagner, Rozenn; Courtney, Michael; Gottschall, Julia

    2011-01-01

    The current IEC standard for wind turbine power performance measurement only requires measurement of the wind speed at hub height assuming this wind speed to be representative for the whole rotor swept area. However, the power output of a wind turbine depends on the kinetic energy flux, which...... itself depends on the wind speed profile, especially for large turbines. Therefore, it is important to characterize the wind profile in front of the turbine, and this should be preferably achieved by measuring the wind speed over the vertical range between lower and higher rotor tips. In this paper, we...... describe an experiment in which wind speed profiles were measured in front of a multimegawatt turbine using a ground–based pulsed lidar. Ignoring the vertical shear was shown to overestimate the kinetic energy flux of these profiles, in particular for those deviating significantly from a power law profile...

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. High speed metal removal

    Science.gov (United States)

    Pugh, R. F.; Pohl, R. F.

    1982-10-01

    Four types of steel (AISI 1340, 4140, 4340, and HF-1) which are commonly used in large caliber projectile manufacture were machined at different hardness ranges representing the as-forged and the heat treated condition with various ceramic tools using ceramic coated tungsten carbide as a reference. Results show that machining speeds can be increased significantly using present available tooling.

  18. Assessment of C-Type Darrieus Wind Turbine Under Low Wind Speed Condition

    Science.gov (United States)

    Misaran, M. S.; Rahman, Md. M.; Muzammil, W. K.; Ismail, M. A.

    2017-07-01

    Harvesting wind energy in in a low wind speed region is deem un-economical if not daunting task. Study shows that a minimum cut in speed of 3.5 m/s is required to extract a meaningful wind energy for electricity while a mean speed of 6 m/s is preferred. However, in Malaysia the mean speed is at 2 m/s with certain potential areas having 3 m/s mean speed. Thus, this work aims to develop a wind turbine that able to operate at lower cut-in speed and produce meaningful power for electricity generation. A C-type Darrieus blade is selected as it shows good potential to operate in arbitrary wind speed condition. The wind turbine is designed and fabricated in UMS labs while the performance of the wind turbine is evaluated in a simulated wind condition. Test result shows that the wind turbine started to rotate at 1 m/s compared to a NACA 0012 Darrieus turbine that started to rotate at 3 m/s. The performance of the turbine shows that it have good potential to be used in an intermittent arbitrary wind speed condition as well as low mean wind speed condition.

  19. 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.

  20. 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)

  1. Time Series Model of Wind Speed for Multi Wind Turbines based on Mixed Copula

    Directory of Open Access Journals (Sweden)

    Nie Dan

    2016-01-01

    Full Text Available Because wind power is intermittent, random and so on, large scale grid will directly affect the safe and stable operation of power grid. In order to make a quantitative study on the characteristics of the wind speed of wind turbine, the wind speed time series model of the multi wind turbine generator is constructed by using the mixed Copula-ARMA function in this paper, and a numerical example is also given. The research results show that the model can effectively predict the wind speed, ensure the efficient operation of the wind turbine, and provide theoretical basis for the stability of wind power grid connected operation.

  2. 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.

  3. Effect of Tip-Speed Constraints on the Optimized Design of a Wind Turbine

    Energy Technology Data Exchange (ETDEWEB)

    Dykes, K.; Resor, B.; Platt, A.; Guo, Y.; Ning, A.; King, R.; Parsons, T.; Petch, D.; Veers, P.

    2014-10-01

    This study investigates the effect of tip-velocity constraints on system levelized cost of energy (LCOE). The results indicate that a change in maximum tip speed from 80 to 100~m/s could produce a 32% decrease in gearbox weight (a 33% reduction in cost) which would result in an overall reduction of 1%-9% in system LCOE depending on the design approach. Three 100~m/s design cases were considered including a low tip-speed ratio/high-solidity rotor design, a high tip-speed ratio/ low-solidity rotor design, and finally a flexible blade design in which a high tip-speed ratio was used along with removing the tip deflection constraint on the rotor design. In all three cases, the significant reduction in gearbox weight caused by the higher tip-speed and lower overall gear ratio was counterbalanced by increased weights for the rotor and/or other drivetrain components and the tower. As a result, the increased costs of either the rotor or drivetrain components offset the overall reduction in turbine costs from down-sizing the gearbox. Other system costs were not significantly affected, whereas energy production was slightly reduced in the 100~m/s case low tip-speed ratio case and increased in the high tip-speed ratio case. This resulted in system cost of energy reductions moving from the 80~m/s design to the 100~m/s designs of 1.2% for the low tip-speed ratio, 4.6% for the high tip-speed ratio, and 9.5% for the final flexible case (the latter result is optimistic because the impact of deflection of the flexible blade on power production was not modeled). Overall, the results demonstrate that there is a trade-off in system design between the maximum tip velocity and the overall wind plant cost of energy, and there are many trade-offs within the overall system in designing a turbine for a high maximum tip velocity.

  4. High-speed AC motors

    Energy Technology Data Exchange (ETDEWEB)

    Jokinen, T.; Arkkio, A. [Helsinki University of Technology Laboratory of Electromechanics, Otaniemi (Finland)

    1997-12-31

    The paper deals with various types of highspeed electric motors, and their limiting powers. Standard machines with laminated rotors can be utilised if the speed is moderate. The solid rotor construction makes it possible to reach higher power and speed levels than those of laminated rotors. The development work on high-speed motors done at Helsinki University of Technology is presented, too. (orig.) 12 refs.

  5. 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

  6. 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

  7. 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)

  8. The choice of design speed for PWR turbines for 50 Hz generating systems

    International Nuclear Information System (INIS)

    Harris, F.R.; Kalderon, D.

    1983-01-01

    Turbines for use with water-cooled reactors, by virtue of their large output, coupled to their larger steam flow per unit output than for fossil-fuelled units, require large total blade exhaust areas; this has led to the adoption of 1800 rpm as the design speed where generation is at 60 Hz, but for generation at 50 Hz both 1500 rpm and 3000 rpm turbines can be deployed over a wide range of outputs. The paper points out why half-speed units, universal for generation at 60 Hz, are often uneconomic for 50 Hz generation. Full-speed and half-speed machines are compared in size, weight, constructional features, reliability, and efficiency. Taking into account economic practice in selection of condenser pressures, the available cooling water temperatures, and also the current and foreseeable turbine blade annulus areas, combinations of outputs and cooling water temperatures where each type of turbine is likely to be economically preferable are identified. (author)

  9. 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...

  10. 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.

  11. High efficiency turbine blade coatings

    Energy Technology Data Exchange (ETDEWEB)

    Youchison, Dennis L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gallis, Michail A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-06-01

    The development of advanced thermal barrier coatings (TBCs) of yttria stabilized zirconia (YSZ) that exhibit lower thermal conductivity through better control of electron beam - physical vapor deposition (EB-PVD) processing is of prime interest to both the aerospace and power industries. This report summarizes the work performed under a two-year Lab-Directed Research and Development (LDRD) project (38664) to produce lower thermal conductivity, graded-layer thermal barrier coatings for turbine blades in an effort to increase the efficiency of high temperature gas turbines. This project was sponsored by the Nuclear Fuel Cycle Investment Area. Therefore, particular importance was given to the processing of the large blades required for industrial gas turbines proposed for use in the Brayton cycle of nuclear plants powered by high temperature gas-cooled reactors (HTGRs). During this modest (~1 full-time equivalent (FTE)) project, the processing technology was developed to create graded TBCs by coupling ion beam-assisted deposition (IBAD) with substrate pivoting in the alumina-YSZ system. The Electron Beam - 1200 kW (EB-1200) PVD system was used to deposit a variety of TBC coatings with micron layered microstructures and reduced thermal conductivity below 1.5 W/m.K. The use of IBAD produced fully stoichiometric coatings at a reduced substrate temperature of 600°C and a reduced oxygen background pressure of 0.1 Pa. IBAD was also used to successfully demonstrate the transitioning of amorphous PVD-deposited alumina to the -phase alumina required as an oxygen diffusion barrier and for good adhesion to the substrate Ni2Al3 bondcoat. This process replaces the time consuming thermally grown oxide formation required before the YSZ deposition. In addition to the process technology, Direct Simulation Monte Carlo plume modeling and spectroscopic characterization of the PVD plumes were performed. The project consisted of five tasks. These included the

  12. 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....

  13. 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)

  14. Direct Torque Control of a Small Wind Turbine with a Sliding-Mode Speed Controller

    Science.gov (United States)

    Sri Lal Senanayaka, Jagath; Karimi, Hamid Reza; Robbersmyr, Kjell G.

    2016-09-01

    In this paper. the method of direct torque control in the presence of a sliding-mode speed controller is proposed for a small wind turbine being used in water heating applications. This concept and control system design can be expanded to grid connected or off-grid applications. Direct torque control of electrical machines has shown several advantages including very fast dynamics torque control over field-oriented control. Moreover. the torque and flux controllers in the direct torque control algorithms are based on hvsteretic controllers which are nonlinear. In the presence of a sliding-mode speed control. a nonlinear control system can be constructed which is matched for AC/DC conversion of the converter that gives fast responses with low overshoots. The main control objectives of the proposed small wind turbine can be maximum power point tracking and soft-stall power control. This small wind turbine consists of permanent magnet synchronous generator and external wind speed. and rotor speed measurements are not required for the system. However. a sensor is needed to detect the rated wind speed overpass events to activate proper speed references for the wind turbine. Based on the low-cost design requirement of small wind turbines. an available wind speed sensor can be modified. or a new sensor can be designed to get the required measurement. The simulation results will be provided to illustrate the excellent performance of the closed-loop control system in entire wind speed range (4-25 m/s).

  15. Multiroller traction drive speed reducer: Evaluation for automotive gas turbine engine

    Science.gov (United States)

    Rohn, D. A.; Anderson, N. E.; Loewenthal, S. H.

    1982-01-01

    Tests were conducted on a nominal 14:1 fixed-ratio Nasvytis multiroller traction drive retrofitted as the speed reducer in an automotive gas turbine engine. Power turbine speeds of 45,000 rpm and a drive output power of 102 kW (137 hp) were reached. The drive operated under both variable roller loading (proportional to torque) and fixed roller loading (automatic loading mechanism locked). The drive operated smoothly and efficiently as the engine speed reducer. Engine specific fuel consumption with the traction speed reducer was comparable to that with the original helical gearset.

  16. A Simple and Effective Approach for the Prediction of Turbine Power Production From Wind Speed Forecast

    Directory of Open Access Journals (Sweden)

    Marino Marrocu

    2017-11-01

    Full Text Available An accurate forecast of the power generated by a wind turbine is of paramount importance for its optimal exploitation. Several forecasting methods have been proposed either based on a physical modeling or using a statistical approach. All of them rely on the availability of high quality measures of local wind speed, corresponding generated power and on numerical weather forecasts. In this paper, a simple and effective wind power forecast technique, based on the probability distribution mapping of wind speed forecast and observed power data, is presented and it is applied to two turbines located on the island of Borkum (Germany in the North Sea. The wind speed forecast of the ECMWF model at 100 m from the ground is used as the prognostic meteorological parameter. Training procedures are based entirely on relatively short time series of power measurements. Results show that our approach has skills that are similar or better than those obtained using more standard methods when measured with mean absolute error.

  17. 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...

  18. SEAL FOR HIGH SPEED CENTRIFUGE

    Science.gov (United States)

    Skarstrom, C.W.

    1957-12-17

    A seal is described for a high speed centrifuge wherein the centrifugal force of rotation acts on the gasket to form a tight seal. The cylindrical rotating bowl of the centrifuge contains a closure member resting on a shoulder in the bowl wall having a lower surface containing bands of gasket material, parallel and adjacent to the cylinder wall. As the centrifuge speed increases, centrifugal force acts on the bands of gasket material forcing them in to a sealing contact against the cylinder wall. This arrangememt forms a simple and effective seal for high speed centrifuges, replacing more costly methods such as welding a closure in place.

  19. Wind Speed Preview Measurement and Estimation for Feedforward Control of Wind Turbines

    Science.gov (United States)

    Simley, Eric J.

    Wind turbines typically rely on feedback controllers to maximize power capture in below-rated conditions and regulate rotor speed during above-rated operation. However, measurements of the approaching wind provided by Light Detection and Ranging (lidar) can be used as part of a preview-based, or feedforward, control system in order to improve rotor speed regulation and reduce structural loads. But the effectiveness of preview-based control depends on how accurately lidar can measure the wind that will interact with the turbine. In this thesis, lidar measurement error is determined using a statistical frequency-domain wind field model including wind evolution, or the change in turbulent wind speeds between the time they are measured and when they reach the turbine. Parameters of the National Renewable Energy Laboratory (NREL) 5-MW reference turbine model are used to determine measurement error for a hub-mounted circularly-scanning lidar scenario, based on commercially-available technology, designed to estimate rotor effective uniform and shear wind speed components. By combining the wind field model, lidar model, and turbine parameters, the optimal lidar scan radius and preview distance that yield the minimum mean square measurement error, as well as the resulting minimum achievable error, are found for a variety of wind conditions. With optimized scan scenarios, it is found that relatively low measurement error can be achieved, but the attainable measurement error largely depends on the wind conditions. In addition, the impact of the induction zone, the region upstream of the turbine where the approaching wind speeds are reduced, as well as turbine yaw error on measurement quality is analyzed. In order to minimize the mean square measurement error, an optimal measurement prefilter is employed, which depends on statistics of the correlation between the preview measurements and the wind that interacts with the turbine. However, because the wind speeds encountered by

  20. High-efficiency wind turbine

    Science.gov (United States)

    Hein, L. A.; Myers, W. N.

    1980-01-01

    Vertical axis wind turbine incorporates several unique features to extract more energy from wind increasing efficiency 20% over conventional propeller driven units. System also features devices that utilize solar energy or chimney effluents during periods of no wind.

  1. Design and cold-air test of single-stage uncooled turbine with high work output

    Science.gov (United States)

    Moffitt, T. P.; Szanca, E. M.; Whitney, W. J.; Behning, F. P.

    1980-01-01

    A solid version of a 50.8 cm single stage core turbine designed for high temperature was tested in cold air over a range of speed and pressure ratio. Design equivalent specific work was 76.84 J/g at an engine turbine tip speed of 579.1 m/sec. At design speed and pressure ratio, the total efficiency of the turbine was 88.6 percent, which is 0.6 point lower than the design value of 89.2 percent. The corresponding mass flow was 4.0 percent greater than design.

  2. 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)

  3. Performance Investigation of A Mix Wind Turbine Using A Clutch Mechanism At Low Wind Speed Condition

    Science.gov (United States)

    Jamanun, M. J.; Misaran, M. S.; Rahman, M.; Muzammil, W. K.

    2017-07-01

    Wind energy is one of the methods that generates energy from sustainable resources. This technology has gained prominence in this era because it produces no harmful product to the society. There is two fundamental type of wind turbine are generally used this day which is Horizontal axis wind turbine (HAWT) and Vertical axis wind turbine (VAWT). The VAWT technology is more preferable compare to HAWT because it gives better efficiency and cost effectiveness as a whole. However, VAWT is known to have distinct disadvantage compared to HAWT; self-start ability and efficiency at low wind speed condition. Different solution has been proposed to solve these issues which includes custom design blades, variable angle of attack mechanism and mix wind turbine. A new type of clutch device was successfully developed in UMS to be used in a mix Savonius-Darrieus wind turbine configuration. The clutch system which barely audible when in operation compared to a ratchet clutch system interconnects the Savonius and Darrieus rotor; allowing the turbine to self-start at low wind speed condition as opposed to a standalone Darrieus turbine. The Savonius height were varied at three different size in order to understand the effect of the Savonius rotor to the mix wind turbine performance. The experimental result shows that the fabricated Savonius rotor show that the height of the Savonius rotor affecting the RPM for the turbine. The swept area (SA), aspect ratio (AR) and tip speed ratio (TSR) also calculated in this paper. The highest RPM recorded in this study is 90 RPM for Savonius rotor 0.22-meter height at 2.75 m/s. The Savonius rotor 0.22-meter also give the highest TSR for each range of speed from 0.75 m/s, 1.75 m/s and 2.75 m/s where it gives 1.03 TSR, 0.76 TSR, and 0.55 TSR.

  4. 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.

  5. Impact of Shaft Stiffness on Inertial Response of Fixed Speed Wind Turbines

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Future power' system faces several challenges, one of them is the high penetration level of intermittent wind power generation, providing small or even no inertial response and being not contributing to the frequency stability. The effect of shaft stiffness on inertial response of fixed speed wind turbines is presented. Four different drive-train models based on the multi-body system are developed. The small-signal analysis demonstrates no significant differences between models in terms of electro-mechanical eigen-values for increasing shaft stiffness. The natural resonance frequency of drive-train torsion modes shows slightly different values between damped and undamped models, but no significant differences are found in the number-mass models. Time-domain simulations show the changes in the active power contribution of a wind farm based on a fixed speed wind turbine during the system frequency disturbance. The changes in the kinetic energy during the dynamic process are calculated and their contribution to the inertia constant is small and effective. The largest contribution of the kinetic energy is provided at the beginning of the system frequency disturbance to reduce the rate of the frequency change, it is positive for the frequency stability.

  6. Adaptive pitch control for variable speed wind turbines

    Science.gov (United States)

    Johnson, Kathryn E [Boulder, CO; Fingersh, Lee Jay [Westminster, CO

    2012-05-08

    An adaptive method for adjusting blade pitch angle, and controllers implementing such a method, for achieving higher power coefficients. Average power coefficients are determined for first and second periods of operation for the wind turbine. When the average power coefficient for the second time period is larger than for the first, a pitch increment, which may be generated based on the power coefficients, is added (or the sign is retained) to the nominal pitch angle value for the wind turbine. When the average power coefficient for the second time period is less than for the first, the pitch increment is subtracted (or the sign is changed). A control signal is generated based on the adapted pitch angle value and sent to blade pitch actuators that act to change the pitch angle of the wind turbine to the new or modified pitch angle setting, and this process is iteratively performed.

  7. Effects of Yaw Error on Wind Turbine Running Characteristics Based on the Equivalent Wind Speed Model

    Directory of Open Access Journals (Sweden)

    Shuting Wan

    2015-06-01

    Full Text Available Natural wind is stochastic, being characterized by its speed and direction which change randomly and frequently. Because of the certain lag in control systems and the yaw body itself, wind turbines cannot be accurately aligned toward the wind direction when the wind speed and wind direction change frequently. Thus, wind turbines often suffer from a series of engineering issues during operation, including frequent yaw, vibration overruns and downtime. This paper aims to study the effects of yaw error on wind turbine running characteristics at different wind speeds and control stages by establishing a wind turbine model, yaw error model and the equivalent wind speed model that includes the wind shear and tower shadow effects. Formulas for the relevant effect coefficients Tc, Sc and Pc were derived. The simulation results indicate that the effects of the aerodynamic torque, rotor speed and power output due to yaw error at different running stages are different and that the effect rules for each coefficient are not identical when the yaw error varies. These results may provide theoretical support for optimizing the yaw control strategies for each stage to increase the running stability of wind turbines and the utilization rate of wind energy.

  8. Applying micro scales of horizontal axis wind turbines for operation in low wind speed regions

    International Nuclear Information System (INIS)

    Pourrajabian, Abolfazl; Ebrahimi, Reza; Mirzaei, Masoud

    2014-01-01

    Highlights: • Three micro-turbines with output power less than 1 kW were designed for operation in low wind speed regions. • In addition to the output power, starting time was considered as a key parameter during the design. • The effects of generator resistive torque and number of blades on the performance of the turbines were investigated. - Abstract: Utilizing the micro scales of wind turbines could noticeably supply the demand for the electricity in low wind speed regions. Aerodynamic design and optimization of the blade, as a main part of a wind turbine, were addressed in the study. Three micro scales of horizontal axis wind turbines with output power of 0.5, 0.75 and 1 kW were considered and the geometric optimization of the blades in terms of the two involved parameters, chord and twist, was undertaken. In order to improve the performance of the turbines at low wind speeds, starting time was included in an objective function in addition to the output power – the main and desirable goal of the wind turbine blade design. A purpose-built genetic algorithm was employed to maximize both the output power and the starting performance which were calculated by the blade-element momentum theory. The results emphasize that the larger values of the chord and twist at the root part of the blades are indispensable for the better performance when the wind speed is low. However, the noticeable value of the generator resistive torque could largely delay the starting of the micro-turbines especially for the considered smaller size, 0.5 kW, where the starting aerodynamic torque could not overcome the generator resistive torque. For that size, an increase in the number of blades improved both the starting performance and also output power

  9. Dynamic behavior of parked wind turbine at extreme wind speed

    DEFF Research Database (Denmark)

    Totsuka, Yoshitaka; Imamura, Hiroshi; Yde, Anders

    2016-01-01

    of standstill and idling is analyzed by time domain simulations using two different coupled aero-hydro-servo-elastic codes. Trend in modern wind turbines is development of bigger, lighter and more flexible rotors where vibration issues may cause aero-elastic instabilities which have a serious impact...

  10. 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...

  11. Wind speed reductions by large-scale wind turbine deployments lower turbine efficiencies and set low wind power potentials

    Science.gov (United States)

    Miller, Lee; Kleidon, Axel

    2017-04-01

    Wind turbines generate electricity by removing kinetic energy from the atmosphere. Large numbers of wind turbines are likely to reduce wind speeds, which lowers estimates of electricity generation from what would be presumed from unaffected conditions. Here, we test how well wind power potentials that account for this effect can be estimated without explicitly simulating atmospheric dynamics. We first use simulations with an atmospheric general circulation model (GCM) that explicitly simulates the effects of wind turbines to derive wind power limits (GCM estimate), and compare them to a simple approach derived from the climatological conditions without turbines [vertical kinetic energy (VKE) estimate]. On land, we find strong agreement between the VKE and GCM estimates with respect to electricity generation rates (0.32 and 0.37 We m-2) and wind speed reductions by 42 and 44%. Over ocean, the GCM estimate is about twice the VKE estimate (0.59 and 0.29 We m-2) and yet with comparable wind speed reductions (50 and 42%). We then show that this bias can be corrected by modifying the downward momentum flux to the surface. Thus, large-scale limits to wind power can be derived from climatological conditions without explicitly simulating atmospheric dynamics. Consistent with the GCM simulations, the approach estimates that only comparatively few land areas are suitable to generate more than 1 We m-2 of electricity and that larger deployment scales are likely to reduce the expected electricity generation rate of each turbine. We conclude that these atmospheric effects are relevant for planning the future expansion of wind power.

  12. High-speed holographic camera

    International Nuclear Information System (INIS)

    Novaro, Marc

    The high-speed holographic camera is a disgnostic instrument using holography as an information storing support. It allows us to take 10 holograms, of an object, with exposures times of 1,5ns, separated in time by 1 or 2ns. In order to get these results easily, no mobile part is used in the set-up [fr

  13. Low Wind Speed Turbine Developments in Convoloid Gearing: Final Technical Report, June 2005 - October 2008

    Energy Technology Data Exchange (ETDEWEB)

    Genesis Partners LP

    2010-08-01

    This report presents the results of a study conducted by Genesis Partners LP as part of the United States Department of Energy Wind Energy Research Program to develop wind technology that will enable wind systems to compete in regions having low wind speeds. The purpose of the program is to reduce the cost of electricity from large wind systems in areas having Class 4 winds to 3 cents per kWh for onshore systems or 5 cents per kWh for offshore systems. This work builds upon previous activities under the WindPACT project, the Next Generation Turbine project, and Phase I of the Low Wind Speed Turbine (LWST) project. This project is concerned with the development of more cost-effective gearing for speed increasers for wind turbines.

  14. 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...

  15. 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...

  16. High speed laser tomography system

    Science.gov (United States)

    Samsonov, D.; Elsaesser, A.; Edwards, A.; Thomas, H. M.; Morfill, G. E.

    2008-03-01

    A high speed laser tomography system was developed capable of acquiring three-dimensional (3D) images of optically thin clouds of moving micron-sized particles. It operates by parallel-shifting an illuminating laser sheet with a pair of galvanometer-driven mirrors and synchronously recording two-dimensional (2D) images of thin slices of the imaged volume. The maximum scanning speed achieved was 120000slices/s, sequences of 24 volume scans (up to 256 slices each) have been obtained. The 2D slices were stacked to form 3D images of the volume, then the positions of the particles were identified and followed in the consecutive scans. The system was used to image a complex plasma with particles moving at speeds up to cm/s.

  17. 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.

  18. Flow and free running speed characterization of dental air turbine handpieces.

    Science.gov (United States)

    Dyson, J E; Darvell, B W

    1999-09-01

    Dental air turbine handpieces have been widely used in clinical dentistry for over 30 years, yet little work has been reported on their performance. A few studies have been concerned with measurement of speed (i.e. rotation rate), torque and power performance of these devices, but neither investigations of functional relationships between controlling variables nor theory dealing specifically with this class of turbine have been reported. This has hindered the development of satisfactory methods of handpiece specification and of testing dental rotary cutting tools. It was the intention of the present work to remedy that deficiency. Measurements of pressure, temperature, gas flow rate and rotation rate were made with improved accuracy and precision for 14 ball bearing turbine handpieces on several gases. Functional relationships between gas properties, supply pressure, flow rate, turbine design factors and free running speed were identified and equations describing these aspects of behaviour of this class of turbine developed. The rotor radius, through peripheral Mach number, was found to be a major determinant of speed performance. In addition, gas flow was found to be an important limiting factor through the effect of choke. Each dental handpiece can be treated as a simple orifice of a characteristic cross-sectional area. Free running speed can be explained in terms of gas properties and pressure, with allowance for a design-specific performance coefficient.

  19. Speed and Torque Control Strategies for Loss Reduction of Vertical Axis Wind Turbines

    Science.gov (United States)

    Argent, Michael; McDonald, Alasdair; Leithead, Bill; Giles, Alexander

    2016-09-01

    This paper builds on the work into modelling the generator losses for Vertical Axis Wind Turbines from their intrinsic torque cycling to investigate the effects of aerodynamic inefficiencies caused by the varying rotational speed resulting from different torque control strategies to the cyclic torque. This is achieved by modelling the wake that builds up from the rotation of the VAWT rotor to investigate how the wake responds to a changing rotor speed and how this in turn affects the torque produced by the blades as well as the corresponding change in generator losses and any changes to the energy extracted by the wind turbine rotor.

  20. Model and simulation of the hydraulic turbine speed regulator of the Atucha I nuclear power plant

    International Nuclear Information System (INIS)

    Copparoni, G.; Etchepareborda, A.; Urrutia, G.

    1992-01-01

    The hydraulics turbines of Atucha I Nuclear Power Plant takes advantage of condenser cooling water level difference between the plant and the river to recover about 2,5 MW e. It also supplies emergency power until diesel generators start up. Speed regulation is needed due to the transients that during this process occur. The purpose is to minimize the diesels start up time, and to avoid overshoots on the internal grid frequency. The hydraulic turbine, its speed regulator and the electric system associated with this transient have been modeled. The models and some simulation results are presented in this work. (author)

  1. Modeling of the dynamics of wind to power conversion including high wind speed behavior

    DEFF Research Database (Denmark)

    Litong-Palima, Marisciel; Bjerge, Martin Huus; Cutululis, Nicolaos Antonio

    2016-01-01

    This paper proposes and validates an efficient, generic and computationally simple dynamic model for the conversion of the wind speed at hub height into the electrical power by a wind turbine. This proposed wind turbine model was developed as a first step to simulate wind power time series...... for power system studies. This paper focuses on describing and validating the single wind turbine model, and is therefore neither describing wind speed modeling nor aggregation of contributions from a whole wind farm or a power system area. The state-of-the-art is to use static power curves for the purpose...... of power system studies, but the idea of the proposed wind turbine model is to include the main dynamic effects in order to have a better representation of the fluctuations in the output power and of the fast power ramping especially because of high wind speed shutdowns of the wind turbine. The high wind...

  2. CFD analysis for H-rotor Darrieus turbine as a low speed wind energy converter

    Directory of Open Access Journals (Sweden)

    M.H. Mohamed

    2015-03-01

    Full Text Available Vertical axis wind turbines like the Darrieus turbine appear to be promising for the conditions of low wind speed, but suffer from a low efficiency compared to horizontal axis turbines. A fully detailed numerical analysis is introduced in this work to improve the global performance of this wind turbine. A comparison between ANSYS Workbench and Gambit meshing tools for the numerical modeling is performed to summarize a final numerical sequence for the Darrieus rotor performance. Then, this model sequence is applied for different blade airfoils to obtain the best performance. Unsteady simulations performed for different speed ratios and based on URANS turbulent calculations using sliding mesh approach. Results show that the accuracy of ANSYS Workbench meshing is improved by using SST K-omega model but it is not recommended for other turbulence models. Moreover, this CFD procedure is used in this paper to assess the turbine performance with different airfoil shapes (25 airfoils. The results introduced new shapes for this turbine with higher efficiency than the regular airfoils by 10%. In addition, blade pitch angle has been studied and the results indicated that the zero pitch angle gives best performance.

  3. High-speed parallel counter

    International Nuclear Information System (INIS)

    Gus'kov, B.N.; Kalinnikov, V.A.; Krastev, V.R.; Maksimov, A.N.; Nikityuk, N.M.

    1985-01-01

    This paper describes a high-speed parallel counter that contains 31 inputs and 15 outputs and is implemented by integrated circuits of series 500. The counter is designed for fast sampling of events according to the number of particles that pass simultaneously through the hodoscopic plane of the detector. The minimum delay of the output signals relative to the input is 43 nsec. The duration of the output signals can be varied from 75 to 120 nsec

  4. 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...

  5. 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

  6. 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)

  7. Performance analysis of wind turbines at low tip-speed ratio using the Betz-Goldstein model

    International Nuclear Information System (INIS)

    Vaz, Jerson R.P.; Wood, David H.

    2016-01-01

    Highlights: • General formulations for power and thrust at any tip-speed ratio are developed. • The Joukowsky model for the blades is modified with specific vortex distributions. • Betz-Goldstein model is shown to be the most consistent at low tip-speed ratio. • The effects of finite blade number are assessed using tip loss factors. • Tip loss for finite blade number may complicate the vortex breakdown. - Abstract: Analyzing wind turbine performance at low tip-speed ratio is challenging due to the relatively high level of swirl in the wake. This work presents a new approach to wind turbine analysis including swirl for any tip-speed ratio. The methodology uses the induced velocity field from vortex theory in the general momentum theory, in the form of the turbine thrust and torque equations. Using the constant bound circulation model of Joukowsky, the swirl velocity becomes infinite on the wake centreline even at high tip-speed ratio. Rankine, Vatistas and Delery vortices were used to regularize the Joukowsky model near the centreline. The new formulation prevents the power coefficient from exceeding the Betz-Joukowsky limit. An alternative calculation, based on the varying circulation for Betz-Goldstein optimized rotors is shown to have the best general behavior. Prandtl’s approximation for the tip loss and a recent alternative were employed to account for the effects of a finite number of blades. The Betz-Goldstein model appears to be the only one resistant to vortex breakdown immediately behind the rotor for an infinite number of blades. Furthermore, the dependence of the induced velocity on radius in the Betz-Goldstein model allows the power coefficient to remain below Betz-Joukowsky limit which does not occur for the Joukowsky model at low tip-speed ratio.

  8. Low Speed Technology for Small Turbine Development Reaction Injection Molded 7.5 Meter Wind Turbine Blade

    Energy Technology Data Exchange (ETDEWEB)

    David M. Wright; DOE Project Officer - Keith Bennett

    2007-07-31

    An optimized small turbine blade (7.5m radius) was designed and a partial section molded with the RIM (reaction-injection molded polymer) process for mass production. The intended market is for generic three-bladed wind turbines, 100 kilowatts or less, for grid-assist end users with rural and semi-rural sites, such as the farm/ranch market, having low to moderate IEC Class 3-4 wind regimes. This blade will have substantial performance improvements over, and be cheaper than, present-day 7.5m blades. This is made possible by the injection-molding process, which yields high repeatability, accurate geometry and weights, and low cost in production quantities. No wind turbine blade in the 7.5m or greater size has used this process. The blade design chosen uses a RIM skin bonded to a braided infused carbon fiber/epoxy spar. This approach is attractive to present users of wind turbine blades in the 5-10m sizes. These include rebladeing California wind farms, refurbishing used turbines for the Midwest farm market, and other manufacturers introducing new turbines in this size range.

  9. Robust control of speed and temperature in a power plant gas turbine.

    Science.gov (United States)

    Najimi, Ebrahim; Ramezani, Mohammad Hossein

    2012-03-01

    In this paper, an H(∞) robust controller has been designed for an identified model of MONTAZER GHAEM power plant gas turbine (GE9001E). In design phase, a linear model (ARX model) which is obtained using real data has been applied. Since the turbine has been used in a combined cycle power plant, its speed and also the exhaust gas temperature should be adjusted simultaneously by controlling fuel signals and compressor inlet guide vane (IGV) position. Considering the limitations on the system inputs, the aim of the control is to maintain the turbine speed and the exhaust gas temperature within desired interval under uncertainties and load demand disturbances. Simulation results of applying the proposed robust controller on the nonlinear model of the system (NARX model), fairly fulfilled the predefined aims. Simulations also show the improvement in the performance compared to MPC and PID controllers for the same conditions. Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.

  10. Analysis of the Flicker Level Produced by a Fixed-Speed Wind Turbine

    Science.gov (United States)

    Suppioni, Vinicius; P. Grilo, Ahda

    2013-10-01

    In this article, the analysis of the flicker emission during continuous operation of a mid-scale fixed-speed wind turbine connected to a distribution system is presented. Flicker emission is investigated based on simulation results, and the dependence of flicker emission on short-circuit capacity, grid impedance angle, mean wind speed, and wind turbulence is analyzed. The simulations were conducted in different programs in order to provide a more realistic wind emulation and detailed model of mechanical and electrical components of the wind turbine. Such aim is accomplished by using FAST (Fatigue, Aerodynamics, Structures, and Turbulence) to simulate the mechanical parts of the wind turbine, Simulink/MatLab to simulate the electrical system, and TurbSim to obtain the wind model. The results show that, even for a small wind generator, the flicker level can limit the wind power capacity installed in a distribution system.

  11. 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.

  12. 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...

  13. On the wind speed reduction in the center of large clusters of wind turbines

    DEFF Research Database (Denmark)

    Frandsen, Sten Tronæs

    1992-01-01

    of the wind speed assuming the wind turbines effectively act as roughness elements. The model makes use of similarities to so-called canopy flows, where the surface drag and the drag on individual obstacles are added to form the total drag. Results are compared with existing models for reduction of efficiency...

  14. Fixed-speed active-stall wind turbines in offshore applications

    DEFF Research Database (Denmark)

    Akhmatov, Vladislav; Nielsen, Arne Hejde

    2005-01-01

    A large offshore wind farm in the East Danish power system was commissioned in 2003 at Rodsand. The power capacity of the wind farm is 165 MW divided between 72 wind turbines. For this large offshore application, robust and well-known wind technology has been chosen in the form of fixed-speed, ac...

  15. 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.

  16. 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...

  17. 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...

  18. Compressor and Turbine Multidisciplinary Design for Highly Efficient Micro-gas Turbine

    Science.gov (United States)

    Barsi, Dario; Perrone, Andrea; Qu, Yonglei; Ratto, Luca; Ricci, Gianluca; Sergeev, Vitaliy; Zunino, Pietro

    2018-06-01

    Multidisciplinary design optimization (MDO) is widely employed to enhance turbomachinery components efficiency. The aim of this work is to describe a complete tool for the aero-mechanical design of a radial inflow turbine and a centrifugal compressor. The high rotational speed of such machines and the high exhaust gas temperature (only for the turbine) expose blades to really high stresses and therefore the aerodynamics design has to be coupled with the mechanical one through an integrated procedure. The described approach employs a fully 3D Reynolds Averaged Navier-Stokes (RANS) solver for the aerodynamics and an open source Finite Element Analysis (FEA) solver for the mechanical integrity assessment. Due to the high computational cost of both these two solvers, a meta model, such as an artificial neural network (ANN), is used to speed up the optimization design process. The interaction between two codes, the mesh generation and the post processing of the results are achieved via in-house developed scripting modules. The obtained results are widely presented and discussed.

  19. 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

  20. High speed computer assisted tomography

    International Nuclear Information System (INIS)

    Maydan, D.; Shepp, L.A.

    1980-01-01

    X-ray generation and detection apparatus for use in a computer assisted tomography system which permits relatively high speed scanning. A large x-ray tube having a circular anode (3) surrounds the patient area. A movable electron gun (8) orbits adjacent to the anode. The anode directs into the patient area xrays which are delimited into a fan beam by a pair of collimating rings (21). After passing through the patient, x-rays are detected by an array (22) of movable detectors. Detector subarrays (23) are synchronously movable out of the x-ray plane to permit the passage of the fan beam

  1. 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.

  2. 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.

  3. Stability analysis for a delay differential equations model of a hydraulic turbine speed governor

    Science.gov (United States)

    Halanay, Andrei; Safta, Carmen A.; Dragoi, Constantin; Piraianu, Vlad F.

    2017-01-01

    The paper aims to study the dynamic behavior of a speed governor for a hydraulic turbine using a mathematical model. The nonlinear mathematical model proposed consists in a system of delay differential equations (DDE) to be compared with already established mathematical models of ordinary differential equations (ODE). A new kind of nonlinearity is introduced as a time delay. The delays can characterize different running conditions of the speed governor. For example, it is considered that spool displacement of hydraulic amplifier might be blocked due to oil impurities in the oil supply system and so the hydraulic amplifier has a time delay in comparison to the time control. Numerical simulations are presented in a comparative manner. A stability analysis of the hydraulic control system is performed, too. Conclusions of the dynamic behavior using the DDE model of a hydraulic turbine speed governor are useful in modeling and controlling hydropower plants.

  4. Multiroller Traction Drive Speed Reducer. Evaluation for Automotive Gas Turbine Engine

    Science.gov (United States)

    1982-06-01

    Speed is deLermined by a magnetic pickup on a toothed wheel . Gas turbine engine instrumunelLtiouu i -designed 1f0r measurement of specific fuel...buffer seal and the fluid--film bearing measured a maximum total runout of 0.038 mm (0.0015 in.) at low speed. At higher speeds, above 8000 rpm, the...maximum was 0.025 mm (0.001 in.) except near 10 000 rpm, where the oscilloscope indicated an excursion of 0.045 mm (0.0018 in.). This runout was within

  5. 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.

  6. On Using Wind Speed Preview to Reduce Wind Turbine Tower Oscillations

    DEFF Research Database (Denmark)

    Kristalny, Maxim; Madjidian, Daria; Knudsen, Torben

    2013-01-01

    We investigate the potential of using previewed wind speed measurements for damping wind turbine fore-aft tower oscillations. Using recent results on continuous-time H 2 preview control, we develop a numerically efficient framework for the feedforward controller synthesis. One of the major benefits...... characteristics on the achievable performance and on the required length of preview. We demonstrate the importance of accounting for the distortion in the controller synthesis and quantify the potential benefits of using previewed information by means of simulations based on real-world turbine data....

  7. Accounting for the speed shear in wind turbine power performance measurement

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, R.

    2010-04-15

    The power curve of a wind turbine is the primary characteristic of the machine as it is the basis of the warranty for it power production. The current IEC standard for power performance measurement only requires the measurement of the wind speed at hub height and the air density to characterise the wind field in front of the turbine. However, with the growing size of the turbine rotors during the last years, the effect of the variations of the wind speed within the swept rotor area, and therefore of the power output, cannot be ignored any longer. Primary effects on the power performance are from the vertical wind shear and the turbulence intensity. The work presented in this thesis consists of the description and the investigation of a simple method to account for the wind speed shear in the power performance measurement. Ignoring this effect was shown to result in a power curve dependant on the shear condition, therefore on the season and the site. It was then proposed to use an equivalent wind speed accounting for the whole speed profile in front of the turbine. The method was first tested with aerodynamic simulations of a multi-megawatt wind turbine which demonstrated the decrease of the scatter in the power curve. A power curve defined in terms of this equivalent wind speed would be less dependant on the shear than the standard power curve. The equivalent wind speed method was then experimentally validated with lidar measurements. Two equivalent wind speed definitions were considered both resulting in the reduction of the scatter in the power curve. As a lidar wind profiler can measure the wind speed at several heights within the rotor span, the wind speed profile is described with more accuracy than with the power law model. The equivalent wind speed derived from measurements, including at least one measurement above hub height, resulted in a smaller scatter in the power curve than the equivalent wind speed derived from profiles extrapolated from measurements

  8. 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.

  9. 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)

  10. High-speed data search

    Science.gov (United States)

    Driscoll, James N.

    1994-01-01

    The high-speed data search system developed for KSC incorporates existing and emerging information retrieval technology to help a user intelligently and rapidly locate information found in large textual databases. This technology includes: natural language input; statistical ranking of retrieved information; an artificial intelligence concept called semantics, where 'surface level' knowledge found in text is used to improve the ranking of retrieved information; and relevance feedback, where user judgements about viewed information are used to automatically modify the search for further information. Semantics and relevance feedback are features of the system which are not available commercially. The system further demonstrates focus on paragraphs of information to decide relevance; and it can be used (without modification) to intelligently search all kinds of document collections, such as collections of legal documents medical documents, news stories, patents, and so forth. The purpose of this paper is to demonstrate the usefulness of statistical ranking, our semantic improvement, and relevance feedback.

  11. Online monitoring of dynamic tip clearance of turbine blades in high temperature environments

    Science.gov (United States)

    Han, Yu; Zhong, Chong; Zhu, Xiaoliang; Zhe, Jiang

    2018-04-01

    Minimized tip clearance reduces the gas leakage over turbine blade tips and improves the thrust and efficiency of turbomachinery. An accurate tip clearance sensor, measuring the dynamic clearances between blade tips and the turbine case, is a critical component for tip clearance control. This paper presents a robust inductive tip clearance sensor capable of monitoring dynamic tip clearances of turbine machines in high-temperature environments and at high rotational speeds. The sensor can also self-sense the temperature at a blade tip in situ such that temperature effect on tip clearance measurement can be estimated and compensated. To evaluate the sensor’s performance, the sensor was tested for measuring the tip clearances of turbine blades under various working temperatures ranging from 700 K to 1300 K and at turbine rotational speeds ranging from 3000 to 10 000 rpm. The blade tip clearance was varied from 50 to 2000 µm. The experiment results proved that the sensor can accurately measure the blade tip clearances with a temporal resolution of 10 µm. The capability of accurately measuring the tip clearances at high temperatures (~1300 K) and high turbine rotation speeds (~30 000 rpm), along with its compact size, makes it promising for online monitoring and active control of blade tip clearances of high-temperature turbomachinery.

  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. 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.

  14. Wind turbine blades for harnessing energy from Malaysian low speed wind - manufacturing technique

    International Nuclear Information System (INIS)

    Abas Abd Wahab; Azmin Shakrine

    2000-01-01

    Blades for wind turbine to harness energy in the Malaysia low speed winds have been designed. During wind tunnel testing, wind turbine model using this type of blades has cut in speed of 1.5 m/s and turned at 450 rpm at 4 m/s wind. The blades, due to their critical dimensions of 1.2 m length, 5 cm thickness, tapered and 15 degree twist, were difficult to produce especially in large number. Several production methods have been studied but for economical mass production, fibreglass blades using CNC cutting mould were chosen. The blade and mould designs and the manufacturing processes are briefly outlined in this paper. (Author)

  15. 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

  16. Dynamic Protective Control Strategy for Distributed Generation System with Fixed-speed Wind Turbines

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    The characteristics of induction generator based fixed-speed wind turbines (FSWT) are investigated. The impacts of different execution time in protective operations are studied under different fauit duration and various wind velocity situations, e.g. , FSWT stabilities of load shedding in distribution systems. Based on this research, a dynamic protective control strategy for a distributed generation system (DGS) with FSWT is proposed. Finally, simulation results demonstrate the effectiveness of the strategy.

  17. Empirical investigation on using wind speed volatility to estimate the operation probability and power output of wind turbines

    International Nuclear Information System (INIS)

    Liu, Heping; Shi, Jing; Qu, Xiuli

    2013-01-01

    Highlights: ► Ten-minute wind speed and power generation data of an offshore wind turbine are used. ► An ARMA–GARCH-M model is built to simultaneously forecast wind speed mean and volatility. ► The operation probability and expected power output of the wind turbine are predicted. ► The integrated approach produces more accurate wind power forecasting than other conventional methods. - Abstract: In this paper, we introduce a quantitative methodology that performs the interval estimation of wind speed, calculates the operation probability of wind turbine, and forecasts the wind power output. The technological advantage of this methodology stems from the empowered capability of mean and volatility forecasting of wind speed. Based on the real wind speed and corresponding wind power output data from an offshore wind turbine, this methodology is applied to build an ARMA–GARCH-M model for wind speed forecasting, and then to compute the operation probability and the expected power output of the wind turbine. The results show that the developed methodology is effective, the obtained interval estimation of wind speed is reliable, and the forecasted operation probability and expected wind power output of the wind turbine are accurate

  18. 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.)

  19. 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...

  20. An innovative medium speed wind turbine rotor blade design for low wind regime (electrical power generation)

    International Nuclear Information System (INIS)

    Abas Abd Wahab; Chong Wen Tong

    2001-01-01

    This paper describes the preliminary study of a small-scale wind turbine rotor blade (a low wind speed region turbine). A new wind turbine rotor blade (AE2 blade) for stand alone system has been conceptualized, designed, constructed and tested. The system is a reduced size prototype (half-scaled) to develop an efficient (adapted to Malaysian wind conditions)and cost effective wind energy conversion system (WECS) with local design and production technique. The blades were constructed from aluminium sheet with metal blending technique. The layout and design of rotor blade, its innovative features and test results are presented. Results from indoor test showed that the advantages of AE2 blade in low speed, with the potential of further improvements. The best rotor efficiency, C P attained with simple AE2 blades rotor (number of blade = 3) was 37.3% (Betz efficiency = 63%) at tip speed ratio (TSR) = 3.6. From the fabrication works and indoor testing, the AE2 blade rotor has demonstrated its structural integrity (ease of assembly and transportation), simplicity, acceptable performance and low noise level. (Author)

  1. 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

  2. Wake flow characteristics at high wind speed

    DEFF Research Database (Denmark)

    Aagaard Madsen, Helge; Larsen, Torben J.; Larsen, Gunner Chr.

    2016-01-01

    Wake flow characteristic at high wind speeds is the main subject of this paper. Although the wake losses decrease at high wind speeds it has been found in a recent study that for multiple wake inflow the increase in loading due to wake effects are substantial even at wind speeds well above rated ...

  3. Experimental high-speed network

    Science.gov (United States)

    McNeill, Kevin M.; Klein, William P.; Vercillo, Richard; Alsafadi, Yasser H.; Parra, Miguel V.; Dallas, William J.

    1993-09-01

    Many existing local area networking protocols currently applied in medical imaging were originally designed for relatively low-speed, low-volume networking. These protocols utilize small packet sizes appropriate for text based communication. Local area networks of this type typically provide raw bandwidth under 125 MHz. These older network technologies are not optimized for the low delay, high data traffic environment of a totally digital radiology department. Some current implementations use point-to-point links when greater bandwidth is required. However, the use of point-to-point communications for a total digital radiology department network presents many disadvantages. This paper describes work on an experimental multi-access local area network called XFT. The work includes the protocol specification, and the design and implementation of network interface hardware and software. The protocol specifies the Physical and Data Link layers (OSI layers 1 & 2) for a fiber-optic based token ring providing a raw bandwidth of 500 MHz. The protocol design and implementation of the XFT interface hardware includes many features to optimize image transfer and provide flexibility for additional future enhancements which include: a modular hardware design supporting easy portability to a variety of host system buses, a versatile message buffer design providing 16 MB of memory, and the capability to extend the raw bandwidth of the network to 3.0 GHz.

  4. High speed all optical networks

    Science.gov (United States)

    Chlamtac, Imrich; Ganz, Aura

    1990-01-01

    An inherent problem of conventional point-to-point wide area network (WAN) architectures is that they cannot translate optical transmission bandwidth into comparable user available throughput due to the limiting electronic processing speed of the switching nodes. The first solution to wavelength division multiplexing (WDM) based WAN networks that overcomes this limitation is presented. The proposed Lightnet architecture takes into account the idiosyncrasies of WDM switching/transmission leading to an efficient and pragmatic solution. The Lightnet architecture trades the ample WDM bandwidth for a reduction in the number of processing stages and a simplification of each switching stage, leading to drastically increased effective network throughputs. The principle of the Lightnet architecture is the construction and use of virtual topology networks, embedded in the original network in the wavelength domain. For this construction Lightnets utilize the new concept of lightpaths which constitute the links of the virtual topology. Lightpaths are all-optical, multihop, paths in the network that allow data to be switched through intermediate nodes using high throughput passive optical switches. The use of the virtual topologies and the associated switching design introduce a number of new ideas, which are discussed in detail.

  5. 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.

  6. Using wind speed from a blade-mounted flow sensor for power and load assessment on modern wind turbines

    Directory of Open Access Journals (Sweden)

    M. M. Pedersen

    2017-11-01

    Full Text Available In this paper an alternative method to evaluate power performance and loads on wind turbines using a blade-mounted flow sensor is investigated. The hypothesis is that the wind speed measured at the blades has a high correlation with the power and loads such that a power or load assessment can be performed from a few hours or days of measurements.In the present study a blade-mounted five-hole pitot tube is used as the flow sensor as an alternative to the conventional approach, where the reference wind speed is either measured at a nearby met mast or on the nacelle using lidar technology or cup anemometers. From the flow sensor measurements, an accurate estimate of the wind speed at the rotor plane can be obtained. This wind speed is disturbed by the presence of the wind turbine, and it is therefore different from the free-flow wind speed. However, the recorded wind speed has a high correlation with the actual power production as well as the flap-wise loads as it is measured close to the blade where the aerodynamic forces are acting.Conventional power curves are based on at least 180 h of 10 min mean values, but using the blade-mounted flow sensor both the observation average time and the overall assessment time can potentially be shortened. The basis for this hypothesis is that the sensor is able to provide more observations with higher accuracy, as the sensor follows the rotation of the rotor and because of the high correlation between the flow at the blades and the power production. This is the research question addressed in this paper.The method is first tested using aeroelastic simulations where the dependence of the radial position and effect of multiple blade-mounted flow sensors are also investigated. Next the method is evaluated on the basis of full-scale measurements on a pitch-regulated, variable-speed 3.6 MW wind turbine.It is concluded that the wind speed derived from the blade-mounted flow sensor is highly correlated with the

  7. 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.

  8. High speed infrared radiation thermometer, system, and method

    Science.gov (United States)

    Markham, James R.

    2002-01-01

    The high-speed radiation thermometer has an infrared measurement wavelength band that is matched to the infrared wavelength band of near-blackbody emittance of ceramic components and ceramic thermal barrier coatings used in turbine engines. It is comprised of a long wavelength infrared detector, a signal amplifier, an analog-to-digital converter, an optical system to collect radiation from the target, an optical filter, and an integral reference signal to maintain a calibrated response. A megahertz range electronic data acquisition system is connected to the radiation detector to operate on raw data obtained. Because the thermometer operates optimally at 8 to 12 .mu.m, where emittance is near-blackbody for ceramics, interferences to measurements performed in turbine engines are minimized. The method and apparatus are optimized to enable mapping of surface temperatures on fast moving ceramic elements, and the thermometer can provide microsecond response, with inherent self-diagnostic and calibration-correction features.

  9. Accounting for the speed shear in wind turbine power performance measurement

    DEFF Research Database (Denmark)

    Wagner, Rozenn

    the vertical wind shear and the turbulence intensity. The work presented in this thesis consists of the description and the investigation of a simple method to account for the wind speed shear in the power performance measurement. Ignoring this effect was shown to result in a power curve dependant on the shear...... for turbulence intensity suggested by Albers. The second method was found to be more suitable for normalising the power curve for the turbulence intensity. Using the equivalent wind speed accounting for the wind shear in the power performance measurement was shown to result in a more repeatable power curve than......The power curve of a wind turbine is the primary characteristic of the machine as it is the basis of the warranty for it power production. The current IEC standard for power performance measurement only requires the measurement of the wind speed at hub height and the air density to characterise...

  10. Evaluation of a new device for sterilizing dental high-speed handpieces

    DEFF Research Database (Denmark)

    Larsen, T; Andersen, H K; Fiehn, N E

    1997-01-01

    Dental high-speed turbines and handpieces can take up and expel microorganisms during operation and thus need regular sterilization. This study established a method for validating devices used to sterilize high-speed turbines and handpieces. The air and water channels and turbine chambers were...... contaminated with suspensions of Streptococcus salivarius or endospores of Bacillus stearothermophilus. The effect of flushing and/or autoclaving performed by a new device combining both procedures was evaluated by counting the number of viable bacteria recovered from these devices. Further, the effect...... on clinically used handpieces was evaluated. In an initial experiment, the device partially reduced S. salivarius, and the endospores survived. In a second experiment, a 5 to 6 log reduction of S. salivarius in air and water channels was obtained. No growth was observed in clinically used high-speed handpieces...

  11. 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.

  12. 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.

  13. 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...

  14. High Speed On-Wafer Characterization Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — At the High Speed On-Wafer Characterization Laboratory, researchers characterize and model devices operating at terahertz (THz) and millimeter-wave frequencies. The...

  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. Understanding the Benefits and Limitations of Increasing Maximum Rotor Tip Speed for Utility-Scale Wind Turbines

    International Nuclear Information System (INIS)

    Ning, A; Dykes, K

    2014-01-01

    For utility-scale wind turbines, the maximum rotor rotation speed is generally constrained by noise considerations. Innovations in acoustics and/or siting in remote locations may enable future wind turbine designs to operate with higher tip speeds. Wind turbines designed to take advantage of higher tip speeds are expected to be able to capture more energy and utilize lighter drivetrains because of their decreased maximum torque loads. However, the magnitude of the potential cost savings is unclear, and the potential trade-offs with rotor and tower sizing are not well understood. A multidisciplinary, system-level framework was developed to facilitate wind turbine and wind plant analysis and optimization. The rotors, nacelles, and towers of wind turbines are optimized for minimum cost of energy subject to a large number of structural, manufacturing, and transportation constraints. These optimization studies suggest that allowing for higher maximum tip speeds could result in a decrease in the cost of energy of up to 5% for land-based sites and 2% for offshore sites when using current technology. Almost all of the cost savings are attributed to the decrease in gearbox mass as a consequence of the reduced maximum rotor torque. Although there is some increased energy capture, it is very minimal (less than 0.5%). Extreme increases in tip speed are unnecessary; benefits for maximum tip speeds greater than 100-110 m/s are small to nonexistent

  17. Understanding the Benefits and Limitations of Increasing Maximum Rotor Tip Speed for Utility-Scale Wind Turbines

    Science.gov (United States)

    Ning, A.; Dykes, K.

    2014-06-01

    For utility-scale wind turbines, the maximum rotor rotation speed is generally constrained by noise considerations. Innovations in acoustics and/or siting in remote locations may enable future wind turbine designs to operate with higher tip speeds. Wind turbines designed to take advantage of higher tip speeds are expected to be able to capture more energy and utilize lighter drivetrains because of their decreased maximum torque loads. However, the magnitude of the potential cost savings is unclear, and the potential trade-offs with rotor and tower sizing are not well understood. A multidisciplinary, system-level framework was developed to facilitate wind turbine and wind plant analysis and optimization. The rotors, nacelles, and towers of wind turbines are optimized for minimum cost of energy subject to a large number of structural, manufacturing, and transportation constraints. These optimization studies suggest that allowing for higher maximum tip speeds could result in a decrease in the cost of energy of up to 5% for land-based sites and 2% for offshore sites when using current technology. Almost all of the cost savings are attributed to the decrease in gearbox mass as a consequence of the reduced maximum rotor torque. Although there is some increased energy capture, it is very minimal (less than 0.5%). Extreme increases in tip speed are unnecessary; benefits for maximum tip speeds greater than 100-110 m/s are small to nonexistent.

  18. Accurate calibration of steam turbine speed control system and its influence on primary regulation at electric grid

    Energy Technology Data Exchange (ETDEWEB)

    Irrazabal Bohorquez, Washington Orlando; Barbosa, Joao Roberto [Technological Institute of Aeronautics (ITA/CTA), Sao Jose dos Campos, SP (Brazil). Center for Reference on Gas Turbine and Energy], E-mail: barbosa@ita.br

    2010-07-01

    In an interconnected electric system there are two very important parameters: the field voltage and the frequency system. The frequency system is very important for the primary regulation of the electric grid. Each turbomachine actuating as generator interconnected to the grid has an automatic speed regulator to keep the rotational speed and mechanical power of the prime machine operating at the set conditions and stable frequency. The electric grid is a dynamical system and in every moment the power units are exposed to several types of disturbances, which cause unbalance of the mechanical power developed by prime machine and the consumed electric power at the grid. The steam turbine speed control system controls the turbine speed to support the electric grid primary frequency at the same time it controls the frequency of the prime machine. Using a mathematical model for the speed control system, the transfer functions were calculated, as well as the proportionality constants of each element of the steam turbine automatic speed regulator. Among other parameters, the droop characteristic of steam turbine and the dynamic characteristics of the automatic speed regulator elements were calculated. Another important result was the determination of the behavior of the speed control when disturbances occur with the improvement of the calibration precision of the control system. (author)

  19. 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.

  20. 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.

  1. 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

  2. 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...

  3. High speed, High resolution terahertz spectrometers

    International Nuclear Information System (INIS)

    Kim, Youngchan; Yee, Dae Su; Yi, Miwoo; Ahn, Jaewook

    2008-01-01

    A variety of sources and methods have been developed for terahertz spectroscopy during almost two decades. Terahertz time domain spectroscopy (THz TDS)has attracted particular attention as a basic measurement method in the fields of THz science and technology. Recently, asynchronous optical sampling (AOS)THz TDS has been demonstrated, featuring rapid data acquisition and a high spectral resolution. Also, terahertz frequency comb spectroscopy (TFCS)possesses attractive features for high precision terahertz spectroscopy. In this presentation, we report on these two types of terahertz spectrometer. Our high speed, high resolution terahertz spectrometer is demonstrated using two mode locked femtosecond lasers with slightly different repetition frequencies without a mechanical delay stage. The repetition frequencies of the two femtosecond lasers are stabilized by use of two phase locked loops sharing the same reference oscillator. The time resolution of our terahertz spectrometer is measured using the cross correlation method to be 270 fs. AOS THz TDS is presented in Fig. 1, which shows a time domain waveform rapidly acquired on a 10ns time window. The inset shows a zoom into the signal with 100ps time window. The spectrum obtained by the fast Fourier Transformation (FFT)of the time domain waveform has a frequency resolution of 100MHz. The dependence of the signal to noise ratio (SNR)on the measurement time is also investigated

  4. Adaptive Backstepping Control Based on Floating Offshore High Temperature Superconductor Generator for Wind Turbines

    Directory of Open Access Journals (Sweden)

    Feng Yang

    2014-01-01

    Full Text Available With the rapid development of offshore wind power, the doubly fed induction generator and permanent magnet synchronous generator cannot meet the increasing request of power capacity. Therefore, superconducting generator should be used instead of the traditional motor, which can improve generator efficiency, reduce the weight of wind turbines, and increase system reliability. This paper mainly focuses on nonlinear control in the offshore wind power system which is consisted of a wind turbine and a high temperature superconductor generator. The proposed control approach is based on the adaptive backstepping method. Its main purpose is to regulate the rotor speed and generator voltage, therefore, achieving the maximum power point tracking (MPPT, improving the efficiency of a wind turbine, and then enhancing the system’s stability and robustness under large disturbances. The control approach can ensure high precision of generator speed tracking, which is confirmed in both the theoretical analysis and numerical simulation.

  5. Reducing Heating In High-Speed Cinematography

    Science.gov (United States)

    Slater, Howard A.

    1989-01-01

    Infrared-absorbing and infrared-reflecting glass filters simple and effective means for reducing rise in temperature during high-speed motion-picture photography. "Hot-mirror" and "cold-mirror" configurations, employed in projection of images, helps prevent excessive heating of scenes by powerful lamps used in high-speed photography.

  6. Design of low noise airfoil with high aerodynamic performance for use on small wind turbines

    Institute of Scientific and Technical Information of China (English)

    Taehyung; KIM; Seungmin; LEE; Hogeon; KIM; Soogab; LEE

    2010-01-01

    Wind power is one of the most reliable renewable energy sources and internationally installed capacity is increasing radically every year.Although wind power has been favored by the public in general,the problem with the impact of wind turbine noise on people living in the vicinity of the turbines has been increased.Low noise wind turbine design is becoming more and more important as noise is spreading more adverse effect of wind turbine to public.This paper demonstrates the design of 10 kW class wind turbines,each of three blades,a rotor diameter 6.4 m,a rated rotating speed 200 r/min and a rated wind speed 10 m/s.The optimized airfoil is dedicated for the 75% spanwise position because the dominant source of a wind turbine blade is trailing edge noise from the outer 25% of the blade.Numerical computations are performed for incompressible flow and for Mach number at 0.145 and for Reynolds numbers at 1.02×106 with a lift performance,which is resistant to surface contamination and turbulence intensity.The objectives in the design process are to reduce noise emission,while sustaining high aerodynamic efficiency.Dominant broadband noise sources are predicted by semi-empirical formulas composed of the groundwork by Brooks et al.and Lowson associated with typical wind turbine operation conditions.During the airfoil redesign process,the aerodynamic performance is analyzed to reduce the wind turbine power loss.The results obtained from the design process show that the design method is capable of designing airfoils with reduced noise using a commercial 10 kW class wind turbine blade airfoil as a basis.Therefore,the new optimized airfoil showing 2.9 dB reductions of total sound pressure level(SPL) and higher aerodynamic performance are achieved.

  7. High Power Density Power Electronic Converters for Large Wind Turbines

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk

    . For these VSCs, high power density is required due to limited turbine nacelle space. Also, high reliability is required since maintenance cost of these remotely located wind turbines is quite high and these turbines operate under harsh operating conditions. In order to select a high power density and reliability......In large wind turbines (in MW and multi-MW ranges), which are extensively utilized in wind power plants, full-scale medium voltage (MV) multi-level (ML) voltage source converters (VSCs) are being more preferably employed nowadays for interfacing these wind turbines with electricity grids...... VSC solution for wind turbines, first, the VSC topology and the switch technology to be employed should be specified such that the highest possible power density and reliability are to be attained. Then, this qualitative approach should be complemented with the power density and reliability...

  8. Remaining life assessment of a high pressure turbine rotor

    International Nuclear Information System (INIS)

    Nguyen, Ninh; Little, Alfie

    2012-01-01

    This paper describes finite element and fracture mechanics based modelling work that provides a useful tool for evaluation of the remaining life of a high pressure (HP) steam turbine rotor that had experienced thermal fatigue cracking. An axis-symmetrical model of a HP rotor was constructed. Steam temperature, pressure and rotor speed data from start ups and shut downs were used for the thermal and stress analysis. Operating history and inspection records were used to benchmark the damage experienced by the rotor. Fracture mechanics crack growth analysis was carried out to evaluate the remaining life of the rotor under themal cyclic loading conditions. The work confirmed that the fracture mechanics approach in conjunction with finite element modelling provides a useful tool for assessing the remaining life of high temperature components in power plants.

  9. Investigation of a High Head Francis Turbine at Runaway Operating Conditions

    Directory of Open Access Journals (Sweden)

    Chirag Trivedi

    2016-03-01

    Full Text Available Hydraulic turbines exhibit total load rejection during operation because of high fluctuations in the grid parameters. The generator reaches no-load instantly. Consequently, the turbine runner accelerates to high speed, runaway speed, in seconds. Under common conditions, stable runaway is only reached if after a load rejection, the control and protection mechanisms both fail and the guide vanes cannot be closed. The runner life is affected by the high amplitude pressure loading at the runaway speed. A model Francis turbine was used to investigate the consequences at the runaway condition. Measurements and simulations were performed at three operating points. The numerical simulations were performed using standard k-ε, k-ω shear stress transport (SST and scale-adaptive simulation (SAS models. A total of 12.8 million hexahedral mesh elements were created in the complete turbine, from the spiral casing inlet to the draft tube outlet. The experimental and numerical analysis showed that the runner was subjected to an unsteady pressure loading up to three-times the pressure loading observed at the best efficiency point. Investigates of unsteady pressure pulsations at the vaneless space, runner and draft tube are discussed in the paper. Further, unsteady swirling flow in the blade passages was observed that was rotating at a frequency of 4.8-times the runaway runner angular speed. Apart from the unsteady pressure loading, the development pattern of the swirling flow in the runner is discussed in the paper.

  10. High - speed steel for precise cased tools

    International Nuclear Information System (INIS)

    Karwiarz, J.; Mazur, A.

    2001-01-01

    The test results of high-vanadium high - speed steel (SWV9) for precise casted tools are presented. The face -milling cutters of NFCa80A type have been tested in industrial operating conditions. An average life - time of SWV9 steel tools was 3-10 times longer compare to the conventional high - speed milling cutters. Metallography of SWB9 precise casted steel revealed beneficial for tool properties distribution of primary vanadium carbides in the steel matrix. Presented results should be a good argument for wide application of high - vanadium high - speed steel for precise casted tools. (author)

  11. Velocity and pressure measurements in guide vane clearance gap of a low specific speed Francis turbine

    Science.gov (United States)

    Thapa, B. S.; Dahlhaug, O. G.; Thapa, B.

    2016-11-01

    In Francis turbine, a small clearance gap between the guide vanes and the cover plates is usually required to pivot guide vanes as a part of governing system. Deflection of cover plates and erosion of mating surfaces causes this gap to increase from its design value. The clearance gap induces the secondary flow in the distributor system. This effects the main flow at the runner inlet, which causes losses in efficiency and instability. A guide vane cascade of a low specific speed Francis turbine has been developed for experimental investigations. The test setup is able to produce similar velocity distributions at the runner inlet as that of a reference prototype turbine. The setup is designed for particle image velocimetry (PIV) measurements from the position of stay vane outlet to the position of runner inlet. In this study, velocity and pressure measurements are conducted with 2 mm clearance gap on one side of guide vane. Leakage flow is observed and measured together with pressure measurements. It is concluded that the leakage flow behaves as a jet and mixes with the main flow in cross-wise direction and forms a vortex filament. This causes non-uniform inlet flow conditions at runner blades.

  12. 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.

  13. 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.

  14. High-Speed Videography Instrumentation And Procedures

    Science.gov (United States)

    Miller, C. E.

    1982-02-01

    High-speed videography has been an electronic analog of low-speed film cameras, but having the advantages of instant-replay and simplicity of operation. Recent advances have pushed frame-rates into the realm of the rotating prism camera. Some characteristics of videography systems are discussed in conjunction with applications in sports analysis, and with sports equipment testing.

  15. High speed rails. Fatigue behaviour

    International Nuclear Information System (INIS)

    Duart, J. M.; Pero-Sanz, J. A.; Verdeja, J. I.

    2005-01-01

    In recent years, passenger train speed and freight train load have increased to enhance efficiency of rail road transportation. These trends have increased the severity of rail service conditions, calling for rails with greater wear resistance, strength and fatigue behaviour. In the United Stated and Europe, track site weld rails are made entirely by aluminothermic process. This work describes the results of experimental study conducted on bending fatigue strength of plain rails and aluminothermic welded rails with preheating procedures (oxipropane and air-induced propane) approved by railways authorities. Compliance with the required fatigue strength shall be ascertained by 4 point pulsating bending test in accordance with European standards by aluminothermic welding in rails. The locati method, based in the empirical Miner's law about the cumulative damage on a fatigue tested material, allows, once known the Wohler curve of the welding process in use to settle the fatigue tensile limit at 50% with only one test. The values obtained at 2.10''6 cycles for plain rails (S f =353 MPa), oxipropane preheated aluminothermic weld rails (S f =225 MPa), and propane-air induced aluminothermic weld rails (S f =210 MPa) are very similar to those resulting from test method stated in the European Standard. From our point of view and due to its ease, speediness and savings, this is the most suitable test to check the quality and compare the aluminothermic processes in use. (Author) 15 refs

  16. High resolution, high speed ultrahigh vacuum microscopy

    International Nuclear Information System (INIS)

    Poppa, Helmut

    2004-01-01

    The history and future of transmission electron microscopy (TEM) is discussed as it refers to the eventual development of instruments and techniques applicable to the real time in situ investigation of surface processes with high resolution. To reach this objective, it was necessary to transform conventional high resolution instruments so that an ultrahigh vacuum (UHV) environment at the sample site was created, that access to the sample by various in situ sample modification procedures was provided, and that in situ sample exchanges with other integrated surface analytical systems became possible. Furthermore, high resolution image acquisition systems had to be developed to take advantage of the high speed imaging capabilities of projection imaging microscopes. These changes to conventional electron microscopy and its uses were slowly realized in a few international laboratories over a period of almost 40 years by a relatively small number of researchers crucially interested in advancing the state of the art of electron microscopy and its applications to diverse areas of interest; often concentrating on the nucleation, growth, and properties of thin films on well defined material surfaces. A part of this review is dedicated to the recognition of the major contributions to surface and thin film science by these pioneers. Finally, some of the important current developments in aberration corrected electron optics and eventual adaptations to in situ UHV microscopy are discussed. As a result of all the path breaking developments that have led to today's highly sophisticated UHV-TEM systems, integrated fundamental studies are now possible that combine many traditional surface science approaches. Combined investigations to date have involved in situ and ex situ surface microscopies such as scanning tunneling microscopy/atomic force microscopy, scanning Auger microscopy, and photoemission electron microscopy, and area-integrating techniques such as x-ray photoelectron

  17. A condenser for very high power steam turbines

    International Nuclear Information System (INIS)

    Gardey, Robert.

    1973-01-01

    The invention relates to a condenser for very high power steam turbines under the masonry-block supporting the low-pressure stages of the turbine, that condenser comprises two horizontal aligned water-tube bundles passing through the steam-exhaust sleeves of the low-pressure stages, on both sides of a common inlet water box. The invention can be applied in particular to the 1000-2000 MW turbines of light water nuclear power stations [fr

  18. Lubrication and cooling for high speed gears

    Science.gov (United States)

    Townsend, D. P.

    1985-01-01

    The problems and failures occurring with the operation of high speed gears are discussed. The gearing losses associated with high speed gearing such as tooth mesh friction, bearing friction, churning, and windage are discussed with various ways shown to help reduce these losses and thereby improve efficiency. Several different methods of oil jet lubrication for high speed gearing are given such as into mesh, out of mesh, and radial jet lubrication. The experiments and analytical results for the various methods of oil jet lubrication are shown with the strengths and weaknesses of each method discussed. The analytical and experimental results of gear lubrication and cooling at various test conditions are presented. These results show the very definite need of improved methods of gear cooling at high speed and high load conditions.

  19. Polymer Surface Textured with Nanowire Bundles to Repel High-Speed Water Drops.

    Science.gov (United States)

    Li, Y P; Li, X Y; Zhu, X P; Lei, M K; Lakhtakia, A

    2018-05-11

    Water drops impacting windshields of high-speed trains and aircraft as well as blades in steam turbine power generators obliquely and at high speeds are difficult to repel. Impacting drops penetrate the void regions of nanotextured and microtextured superhydrophobic coatings, with this pinning resulting in the loss of drop mobility. In order to repel high-speed water drops, we nanotextured polymer surfaces with nanowire bundles separated from their neighbors by microscale void regions, with the nanowires in a bundle separated from their neighbors by nanoscale void regions. Water drops with speeds below a critical speed rebound completely. Water drops with speeds exceeding a critical speed rebound partially, but residual droplets that begin to be pinned undergo a spontaneous dewetting process and slide off. The natural oscillations of residual droplets drive this dewetting process in the interbundle void regions, resulting in a transition from the sticky Wenzel state to the slippery Cassie state without external stimuli.

  20. 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.

  1. Operation Design of Wind Turbines in Strong Wind Conditions

    DEFF Research Database (Denmark)

    Shen, Wen Zhong; Montes, Melissa Barroso; Odgaard, Peter Fogh

    2012-01-01

    and variable speed pitch regulated wind turbines. The variable speed design is more suitable for wind turbines to run at very high wind speeds which can help the turbine braking system to stop the turbine at the new "cut-out" wind speed. Reference power, rotational speed and pitch angle have been designed...... optimally. In order to reduce the possible increased loading, fatigue due to the wind gusts, control strategies have been considered for both constant sped and variable speed pitch regulated wind turbines. The control study shows that the designed controllers can reduce the standard deviations efficiently......In order to reduce the impact on the electrical grid from the shutdown of MW wind turbines at wind speeds higher than the cut-out wind speed of 25 m/s, we propose in this paper to run the turbines at high wind speeds up to 40 m/s. Two different operation designs are made for both constant speed...

  2. High-Speed Sealift Technology Development Plan

    National Research Council Canada - National Science Library

    2002-01-01

    .... The purpose of the project was to define the technology investments required to enable development of the high-speed commercial and military ships needed to provide realistic future mission capabilities...

  3. Balancing High-Speed Rotors at Low Speed

    Science.gov (United States)

    Giordano, J.; Zorzi, E.

    1986-01-01

    Flexible balancing reduces vibrations at operating speeds. Highspeed rotors in turbomachines dynamically balanced at fraction of operating rotor speed. New method takes into account rotor flexible rather than rigid.

  4. Mitigating the negative impacts of tall wind turbines on bats: Vertical activity profiles and relationships to wind speed.

    Science.gov (United States)

    Wellig, Sascha D; Nusslé, Sébastien; Miltner, Daniela; Kohle, Oliver; Glaizot, Olivier; Braunisch, Veronika; Obrist, Martin K; Arlettaz, Raphaël

    2018-01-01

    Wind turbines represent a source of hazard for bats, especially through collision with rotor blades. With increasing technical development, tall turbines (rotor-swept zone 50-150 m above ground level) are becoming widespread, yet we lack quantitative information about species active at these heights, which impedes proposing targeted mitigation recommendations for bat-friendly turbine operation. We investigated vertical activity profiles of a bat assemblage, and their relationships to wind speed, within a major valley of the European Alps where tall wind turbines are being deployed. To monitor bat activity we installed automatic recorders at sequentially increasing heights from ground level up to 65 m, with the goal to determine species-specific vertical activity profiles and to link them to wind speed. Bat call sequences were analysed with an automatic algorithm, paying particular attention to mouse-eared bats (Myotis myotis and Myotis blythii) and the European free-tailed bat (Tadarida teniotis), three locally rare species. The most often recorded bats were the Common pipistrelle (Pipistrellus pipistrellus) and Savi's pipistrelle (Hypsugo savii). Mouse-eared bats were rarely recorded, and mostly just above ground, appearing out of risk of collision. T. teniotis had a more evenly distributed vertical activity profile, often being active at rotor level, but its activity at that height ceased above 5 ms-1 wind speed. Overall bat activity in the rotor-swept zone declined with increasing wind speed, dropping below 5% above 5.4 ms-1. Collision risk could be drastically reduced if nocturnal operation of tall wind turbines would be restricted to wind speeds above 5 ms-1. Such measure should be implemented year-round because T. teniotis remains active in winter. This operational restriction is likely to cause only small energy production losses at these tall wind turbines, although further analyses are needed to assess these losses precisely.

  5. 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.

  6. High-speed photography. Technique and evolution

    International Nuclear Information System (INIS)

    Sanchez-Tembleque, R.

    1981-01-01

    It is intended to present some general considerations about ''Higg-speed photography'' as a tool of work common in mos research laboratories in the world. ''High-speed photography'' relies on the principles of photography of actions, that change rapidly with the time. The evolution of this technique goes along with the discovering of new phenomena in wich higher speeds are involved. At present is normal to deal with changing rates involving picoseconds times (10 -12 s) and new developments on the field of femtosecond (10 -15 s) theoretically are contemplated. (author)

  7. Rotation speed measurement for turbine governor: torsion filtering by using Kalman filter

    International Nuclear Information System (INIS)

    Houry, M.P.; Bourles, H.

    1996-01-01

    The rotation speed of a turbogenerator is disturbed by its shaft torsion. Obtaining a filtered measure of this speed is a problem of a great practical importance for turbine governor. A good filtering of this speed must meet two requirements: it must cut frequencies of the shaft torsion oscillation and it must not reduce or delay the signal in the pass-band, i.e. at lower frequencies. At Electricite de France, the speed measure is used to set in motion the fast valving system as quickly as possible, after a short circuit close to the unit or rather an islanding. It is difficult to satisfy these two requirements by using conventional filtering methods. The standard solution consists in a first order filter: at Electricite de France, its time constant is equal to 80 ms. We have decided to improve this filtering by designing a new filter which cuts the frequencies of the shaft torsion oscillation without reducing the bandwidth to the speed measure. If one uses conventional methods to obtain a band stop filter, it is easy to obtain the desired magnitude but not a phase near zero in the whole pass-band. Therefore, we have chosen to design the filter by using Kalman'a theory. The measurement noise is modeled as a colored one, generated by a very lightly damped system driven by a while noise. The resulting Kalman filter is an effective band stop filter, whose phase nicely remains near zero in the whole pass-band. The digital simulations we made and the tests we carried out with the Electricite de France Micro Network laboratory show the advantages of the rotation speed filter we designed using Kalman's theory. With the proposed filter, the speed measure filtering is better in terms of reduction and phase shift. the result is that there are less untimely solicitations of the fast valving system. Consequently, this device improves the power systems stability by minimizing the risks of deep perturbations due to a temporary lack of generation and the risks of under-speed loss

  8. Partial analysis of wind power limit for large disturbance using fixed speed wind turbine

    International Nuclear Information System (INIS)

    Santos Fuentefria, Ariel; Cairo Rodriguez, Daniel; Boza Valerino, Juan Gualberto

    2014-01-01

    The amount of wind power that allow an electric network without losing his stability as known as wind power limit. The wind power limit fundamentally depends on the wind turbine technology and the weakness level of the system. To know the system behaviors in dynamic performance having into account the worst disturbance is a very important matter, a short circuit in one of the most power transference line or the loss of a large generation unit was a large disturbance that can affect system stability. The wind power limit may change with the nature of the disturbance. To know the wind power limit considering this conditions allow use the wind at maximum level. In the present paper the behavior of fixed speed wind turbine for different fault types is analyzed, at those conditions, the wind power is increasing until the system become voltage unstable. For the analysis the IEEE 14 Bus Test Case is used. The Power System Analysis Toolbox (PSAT) package is used for the simulation. (author)

  9. Assessing noise from wind farm developments in Ireland: A consideration of critical wind speeds and turbine choice

    International Nuclear Information System (INIS)

    King, E.A.; Pilla, F.; Mahon, J.

    2012-01-01

    Wind farms are becoming increasingly popular in Ireland in an effort to increase the production of green energy within the state. As with any infrastructural development, wind farms must consider potential environmental impacts prior to construction. One particular issue that must be examined is the emission of noise from the development. In Ireland wind farm developments must adhere to planning conditions that usually outline permissible noise levels for both the construction and operational phases of the development. The critical wind speed is often cited as the wind speed at which these limits apply. This paper examines how the critical wind speed is determined and investigates its relationship with background noise levels and turbine choice. The study consisted of ten one-week monitoring periods during which meteorological conditions and background noise levels were simultaneously recorded. It was found that the critical wind speed is non-transferable, i.e. it depends on both the turbine choice and background noise environment and is specific to that particular turbine/site combination. Furthermore the critical wind speed during the night-time is often different to the overall critical wind speed suggesting that future noise studies should consider a range of critical wind speeds, particularly for night-time noise assessments. - Highlights: ► This paper considers the use of the critical wind speed when assessing noise impacts from wind farms. ► It was found that the critical wind speed could vary depending on the time of the day. ► The critical wind speed was found to be a non-transferable value. ► Noise assessments for wind farms should be developed over a range of critical wind speeds.

  10. 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....

  11. On the reversed Brayton cycle with high speed machinery

    Energy Technology Data Exchange (ETDEWEB)

    Backman, J.

    1996-12-31

    This work was carried out in the laboratory of Fluid Dynamics, at Lappeenranta University of Technology during the years 1991-1996. The research was a part of larger high speed technology development research. First, there was the idea of making high speed machinery applications with the Brayton cycle. There was a clear need to deepen the knowledge of the cycle itself and to make a new approach in the field of the research. Also, the removal of water from the humid air seemed very interesting. The goal of this work was to study methods of designing high speed machinery for the reversed Brayton cycle, from theoretical principles to practical applications. The reversed Brayton cycle can be employed as an air dryer, a heat pump or a refrigerating machine. In this research the use of humid air as a working fluid has an environmental advantage, as well. A new calculation method for the Brayton cycle is developed. In this method especially the expansion process in the turbine is important because of the condensation of the water vapour in the humid air. This physical phenomena can have significant effects on the level of performance of the application. Also, the influence of calculating the process with actual, achievable process equipment efficiencies is essential for the development of future machinery. The above theoretical calculations are confirmed with two different laboratory prototypes. (53 refs.)

  12. On the reversed Brayton cycle with high speed machinery

    Energy Technology Data Exchange (ETDEWEB)

    Backman, J

    1997-12-31

    This work was carried out in the laboratory of Fluid Dynamics, at Lappeenranta University of Technology during the years 1991-1996. The research was a part of larger high speed technology development research. First, there was the idea of making high speed machinery applications with the Brayton cycle. There was a clear need to deepen the knowledge of the cycle itself and to make a new approach in the field of the research. Also, the removal of water from the humid air seemed very interesting. The goal of this work was to study methods of designing high speed machinery for the reversed Brayton cycle, from theoretical principles to practical applications. The reversed Brayton cycle can be employed as an air dryer, a heat pump or a refrigerating machine. In this research the use of humid air as a working fluid has an environmental advantage, as well. A new calculation method for the Brayton cycle is developed. In this method especially the expansion process in the turbine is important because of the condensation of the water vapour in the humid air. This physical phenomena can have significant effects on the level of performance of the application. Also, the influence of calculating the process with actual, achievable process equipment efficiencies is essential for the development of future machinery. The above theoretical calculations are confirmed with two different laboratory prototypes. (53 refs.)

  13. 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...

  14. Tuning of the PI Controller Parameters of a PMSG Wind Turbine to Improve Control Performance under Various Wind Speeds

    OpenAIRE

    Yun-Su Kim; Il-Yop Chung; Seung-Il Moon

    2015-01-01

    This paper presents a method to seek the PI controller parameters of a PMSG wind turbine to improve control performance. Since operating conditions vary with the wind speed, therefore the PI controller parameters should be determined as a function of the wind speed. Small-signal modeling of a PMSG WT is implemented to analyze the stability under various operating conditions and with eigenvalues obtained from the small-signal model of the PMSG WT, which are coordinated by adjusting the PI con...

  15. Fast control strategy for stabilising fixed-speed induction-generator-based wind turbines in an islanded distributed system

    DEFF Research Database (Denmark)

    Wei, Mu; Chen, Zhe

    2013-01-01

    Distributed generation systems (DGS) with fixed-speed induction-generator-based wind turbines (FSWT) are sensitive and vulnerable to voltage disturbances and reactive power deficiency. Consequently, the control and protection strategies for such a DGS should be prompt and precise to avoid undesired...

  16. 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

  17. Rotation speed measurement for turbine governor: torsion filtering by using Kalman filter

    International Nuclear Information System (INIS)

    Houry, M.P.; Bourles, H.

    1995-11-01

    The rotation speed of a turbogenerator is disturbed by its shaft torsion. Obtaining a filtered measure of this sped a problem of a great practical importance for turbine governor. A good filtering of this speed must meet two requirements: it must cut frequencies of the shaft torsion oscillation and it must not reduce or delay the signal in the pass-band. i.e. at lower frequencies. At Electricite de France, the speed measure is used to set in motion the fast valving system as quickly as possible, after a short circuit close to the unit (to contribute to the stability) or after an islanding (to quickly reach a balance with the house load). It is difficult to satisfy these two requirements by using conventional filtering methods. The standard solution consists in a first order filter: at Electricite de France, its time constant is equal to 80 ms; We have decided to improve this filtering by designing a new filter which cuts the frequencies of the shaft torsion oscillation without reducing the bandwidth of the speed measure. If one uses conventional methods to obtain a band-stop filter (for instance a Butterworth, a Chebyshev or an elliptic band-stop filter),it is easy to obtain the desired magnitude but not a phase near zero in the whole pass-band. Therefore, we have chosen to design the filter by using Kalman's theory. The measurement noise is modeled as a colored one, generated by a very lightly damped system driven by a white noise. The resulting Kalman filter is an effective band-stop filter, whose phase nicely remains near zero in the whole pass-band. (authors). 13 refs., 12 figs

  18. Aerodynamic design on high-speed trains

    Science.gov (United States)

    Ding, San-San; Li, Qiang; Tian, Ai-Qin; Du, Jian; Liu, Jia-Li

    2016-04-01

    Compared with the traditional train, the operational speed of the high-speed train has largely improved, and the dynamic environment of the train has changed from one of mechanical domination to one of aerodynamic domination. The aerodynamic problem has become the key technological challenge of high-speed trains and significantly affects the economy, environment, safety, and comfort. In this paper, the relationships among the aerodynamic design principle, aerodynamic performance indexes, and design variables are first studied, and the research methods of train aerodynamics are proposed, including numerical simulation, a reduced-scale test, and a full-scale test. Technological schemes of train aerodynamics involve the optimization design of the streamlined head and the smooth design of the body surface. Optimization design of the streamlined head includes conception design, project design, numerical simulation, and a reduced-scale test. Smooth design of the body surface is mainly used for the key parts, such as electric-current collecting system, wheel truck compartment, and windshield. The aerodynamic design method established in this paper has been successfully applied to various high-speed trains (CRH380A, CRH380AM, CRH6, CRH2G, and the Standard electric multiple unit (EMU)) that have met expected design objectives. The research results can provide an effective guideline for the aerodynamic design of high-speed trains.

  19. Design Concepts for Low Aspect Ratio High Pressure Turbines for High Bypass Ratio Turbofans, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The performance gains and weight reductions from using Ceramic Matrix Composite(CMC) turbine blades in both the High Pressure Turbine(HPT) and Low Pressure...

  20. The development of control systems for high power steam turbines

    International Nuclear Information System (INIS)

    Mathey, M.

    1983-01-01

    The functional and technological aspects of developments in the field of control systems for steam turbines over the last twenty years are analyzed. These developments have now culminated in very sophisticated systems which closely link electronics to high pressure hydraulic technology. A detailed description of these systeme high-lighting the high technical level of the control methods and the flexibility and reliability in service of turbines controlled in this way is given [fr

  1. Aerodynamics of Wind Turbines

    DEFF Research Database (Denmark)

    Hansen, Martin Otto Laver

    Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its second edition, it has been entirely updated and substantially extended to reflect advances in technology, research into rotor aerodynamics and the structural...... response of the wind turbine structure. Topics covered include increasing mass flow through the turbine, performance at low and high wind speeds, assessment of the extreme conditions under which the turbine will perform and the theory for calculating the lifetime of the turbine. The classical Blade Element...... Momentum method is also covered, as are eigenmodes and the dynamic behavior of a turbine. The new material includes a description of the effects of the dynamics and how this can be modeled in an aeroelastic code, which is widely used in the design and verification of modern wind turbines. Further...

  2. Aerodynamics of wind turbines

    DEFF Research Database (Denmark)

    Hansen, Martin Otto Laver

    Aerodynamics of Wind Turbines is the established essential text for the fundamental solutions to efficient wind turbine design. Now in its third edition, it has been substantially updated with respect to structural dynamics and control. The new control chapter now includes details on how to design...... Turbines (VAWT). Topics covered include increasing mass flow through the turbine, performance at low and high wind speeds, assessment of the extreme conditions under which the turbine will perform and the theory for calculating the lifetime of the turbine. The classical Blade Element Momentum method...... is also covered, as are eigenmodes and the dynamic behaviour of a turbine. The book describes the effects of the dynamics and how this can be modelled in an aeroelastic code, which is widely used in the design and verification of modern wind turbines. Furthermore, it examines how to calculate...

  3. Simplified equations for the rotational speed response to inflow velocity variation in fixed-pitch small wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, H; Hasegawa, Y, E-mail: hsuzuki@nitech.ac.jp [Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555 (Japan)

    2015-02-01

    We propose simplified equations for the rotational speed response to inflow velocity variation in fixed-pitch small wind turbines. The present formulation is derived by introducing a series expansion for the torque coefficient at the constant tip-speed ratio. By focusing on the first- and second-order differential coefficients of the torque coefficient, we simplify the original differential equation. The governing equation based only on the first-order differential coefficient is found to be linear, whereas the second-order differential coefficient introduces nonlinearity. We compare the numerical solutions of the three governing equations for rotational speed in response to sinusoidal and normal-random variations of inflow velocity. The linear equation gives accurate solutions of amplitude and phase lag. Nonlinearity occurs in the mean value of rotational speed variation. We also simulate the rotational speed in response to a step input of inflow velocity using the conditions of two previous studies, and note that the form of this rotational speed response is a system of first-order time lag. We formulate the gain and time constant for this rotational speed response. The magnitude of the gain is approximately three when the wind turbine is operated at optimal tip-speed ratio. We discuss the physical meaning of the derived time constant. (paper)

  4. 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

  5. A high speed digital noise generator

    Science.gov (United States)

    Obrien, J.; Gaffney, B.; Liu, B.

    In testing of digital signal processing hardware, a high speed pseudo-random noise generator is often required to simulate an input noise source to the hardware. This allows the hardware to be exercised in a manner analogous to actual operating conditions. In certain radar and communication environments, a noise generator operating at speeds in excess of 60 MHz may be required. In this paper, a method of generating high speed pseudo-random numbers from an arbitrarily specified distribution (Gaussian, Log-Normal, etc.) using a transformation from a uniform noise source is described. A noise generator operating at 80 MHz has been constructed. Different distributions can be readily obtained by simply changing the ROM set. The hardware and test results will be described. Using this approach, the generation of pseudo-random sequences with arbitrary distributions at word rates in excess of 200 MHz can be readily achieved.

  6. Compressibility, turbulence and high speed flow

    CERN Document Server

    Gatski, Thomas B

    2013-01-01

    Compressibility, Turbulence and High Speed Flow introduces the reader to the field of compressible turbulence and compressible turbulent flows across a broad speed range, through a unique complimentary treatment of both the theoretical foundations and the measurement and analysis tools currently used. The book provides the reader with the necessary background and current trends in the theoretical and experimental aspects of compressible turbulent flows and compressible turbulence. Detailed derivations of the pertinent equations describing the motion of such turbulent flows is provided and an extensive discussion of the various approaches used in predicting both free shear and wall bounded flows is presented. Experimental measurement techniques common to the compressible flow regime are introduced with particular emphasis on the unique challenges presented by high speed flows. Both experimental and numerical simulation work is supplied throughout to provide the reader with an overall perspective of current tre...

  7. Improvement of automatic control systems of high-power turbines of PAO tubroatom for nuclear power plants

    Science.gov (United States)

    Shvetsov, V. L.; Babaev, I. N.

    2017-09-01

    The main technical solutions applied by PAO Turboatom used as the compensatory measures at the increase of the period of nonstop operation of nuclear power plants' (NPP) turbines with VVER-1000 type reactors up to 18 months are (1) replacing the standard hydraulic speed controller with an electronic one, (2) introduction of overclocking protection, (3) modernization of units of stop-control valves of high pressures, (4) installation of locking dampers on the receiver tubes of turbines of the first and second modification, and (5) improving the quality of repairs by reviewing the requirements for their implementation. The introduction of complex diagnostics of a control system on the basis of automatic treatment of results of registration of working parameters of the turbine is allocated as a separate prospective direction. Using an electronic controller of speed makes it possible to simplify the procedure of its inclusion in work at the failure of an electro-hydraulic system of control and vice versa. The regimes of maintaining the turbine rotor speed, steam pressure on the outlet of turbine, and the positions of main servomotors were introduced into the functions of the electronic controller. An electronic controller of speed includes its own electro-hydraulic transducer, turbine rotor speed sensor, and sensors of the position of main servomotors. Into the functions of electro- hydraulic control system and electronic speed controller, the function of overclocking protection, which determines the formation of commands for stopping the turbine at the exceeding of both the defined level of rotation speed and the defined combination of achieved rotation speed and angular acceleration of rotor, was introduced. To simplify the correction of forces acting on the control valve cups, the design of the cups was changed, and it has the profiled inserts. The solutions proposed were implemented on K-1100-60/1500-2M turbines of Rostov NPP. From the composition of control system

  8. Test Program for High Efficiency Gas Turbine Exhaust Diffuser

    Energy Technology Data Exchange (ETDEWEB)

    Norris, Thomas R.

    2009-12-31

    This research relates to improving the efficiency of flow in a turbine exhaust, and thus, that of the turbine and power plant. The Phase I SBIR project demonstrated the technical viability of “strutlets” to control stalls on a model diffuser strut. Strutlets are a novel flow-improving vane concept intended to improve the efficiency of flow in turbine exhausts. Strutlets can help reduce turbine back pressure, and incrementally improve turbine efficiency, increase power, and reduce greenhouse gas emmission. The long-term goal is a 0.5 percent improvement of each item, averaged over the US gas turbine fleet. The strutlets were tested in a physical scale model of a gas turbine exhaust diffuser. The test flow passage is a straight, annular diffuser with three sets of struts. At the end of Phase 1, the ability of strutlets to keep flow attached to struts was demonstrated, but the strutlet drag was too high for a net efficiency advantage. An independently sponsored followup project did develop a highly-modified low-drag strutlet. In combination with other flow improving vanes, complicance to the stated goals was demonstrated for for simple cycle power plants, and to most of the goals for combined cycle power plants using this particular exhaust geometry. Importantly, low frequency diffuser noise was reduced by 5 dB or more, compared to the baseline. Appolicability to other diffuser geometries is yet to be demonstrated.

  9. 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.

  10. High-speed cryptography and cryptanalysis

    NARCIS (Netherlands)

    Schwabe, P.

    2011-01-01

    Modern digital communication relies heavily on cryptographic protection to ensure data integrity and privacy. In order to deploy state-of-the art cryptographic primitives and protocols in real-world scenarios, one needs to highly optimize software for both speed and security. This requires careful

  11. High-speed elevators controlled by inverters

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, Yoshio; Takahashi, Hideaki; Nakamura, Kiyoshi; Kinoshita, Hiroshi

    1988-10-25

    The super-high-speed elevator with superiority to 300m/min of speed, requires both the large capacity power and wide range speed controls. Therefore, in order to materialize the smooth and quiet operation characteristics, by applying the inverter control, the low torque ripple control in the low frequency range and high frequency large capacity inverting for lowering the motor in noise are necessary with their being assured of reliability. To satisfy the above necessary items, together with the development of a sine wave pulse width and frequency modulation (PWM/PFM) control system, to more precisely enable the sine wave electric current control, and 3kHz switching power converter, using a 800A power transistor module, a supervoltage control circuit under the extraordinary condition was designed. As a result of commercializing a 360m/min super-high speed inverter elevator, the power source unit, due to the effect of high power factor, could be reduced by 30% in capacity and also the higher harmonic wave including ratio could be considerably lowered to the inferiority to 5%. 2 references, 7 figures, 1 table.

  12. High Speed Wireless Signal Generation and Demodulation

    DEFF Research Database (Denmark)

    Caballero Jambrina, Antonio; Sambaraju, Rakesh; Zibar, Darko

    We present the experimental demonstration of high speed wireless generation, up to 40 Gb/s, in the 75-110 GHz wireless band. All-optical OFDM and photonic up-conversion are used for generation and single side-band modulation with digital coherent detection for demodulation....

  13. High speed CAMAC differential branch highway driver

    International Nuclear Information System (INIS)

    McMillan, D.E.; Nelson, R.O.; Poore, R.V.; Sunier, J.W.; Ross, J.J.

    1979-01-01

    A new CAMAC branch driver is described that incorporates several unusual features which combine to give reliable, high-speed performance. These include balanced line driver/receivers, stored CAMAC command lists, 8 DMA channels, pseudo LAMS, hardware priority encoding of LAMS, and hardware-implemented Q-controlled block transfers. 3 figures

  14. High Speed SPM of Functional Materials

    Energy Technology Data Exchange (ETDEWEB)

    Huey, Bryan D. [Univ. of Connecticut, Storrs, CT (United States)

    2015-08-14

    The development and optimization of applications comprising functional materials necessitates a thorough understanding of their static and dynamic properties and performance at the nanoscale. Leveraging High Speed SPM and concepts enabled by it, efficient measurements and maps with nanoscale and nanosecond temporal resolution are uniquely feasible. This includes recent enhancements for topographic, conductivity, ferroelectric, and piezoelectric properties as originally proposed, as well as newly developed methods or improvements to AFM-based mechanical, friction, thermal, and photoconductivity measurements. The results of this work reveal fundamental mechanisms of operation, and suggest new approaches for improving the ultimate speed and/or efficiency, of data storage systems, magnetic-electric sensors, and solar cells.

  15. Pulsed laser triggered high speed microfluidic switch

    Science.gov (United States)

    Wu, Ting-Hsiang; Gao, Lanyu; Chen, Yue; Wei, Kenneth; Chiou, Pei-Yu

    2008-10-01

    We report a high-speed microfluidic switch capable of achieving a switching time of 10 μs. The switching mechanism is realized by exciting dynamic vapor bubbles with focused laser pulses in a microfluidic polydimethylsiloxane (PDMS) channel. The bubble expansion deforms the elastic PDMS channel wall and squeezes the adjacent sample channel to control its fluid and particle flows as captured by the time-resolved imaging system. A switching of polystyrene microspheres in a Y-shaped channel has also been demonstrated. This ultrafast laser triggered switching mechanism has the potential to advance the sorting speed of state-of-the-art microscale fluorescence activated cell sorting devices.

  16. Architecture Of High Speed Image Processing System

    Science.gov (United States)

    Konishi, Toshio; Hayashi, Hiroshi; Ohki, Tohru

    1988-01-01

    One of architectures for a high speed image processing system which corresponds to a new algorithm for a shape understanding is proposed. And the hardware system which is based on the archtecture was developed. Consideration points of the architecture are mainly that using processors should match with the processing sequence of the target image and that the developed system should be used practically in an industry. As the result, it was possible to perform each processing at a speed of 80 nano-seconds a pixel.

  17. Analysis of Mechanical Stresses Due to Voltage Dips in Fixed-Speed Wind Turbines

    DEFF Research Database (Denmark)

    Veluri, Badrinath; Santos-Martin, David; Jensen, Henrik Myhre

    2011-01-01

    stresses transients that may have a detrimental effect on the fatigue life of drivetrain system due to voltage dips. A rainflow cycle counting method for the stress history during the voltage dip event, analyses mean and amplitudes of the counted cycles, their occurrence moment and time of duration.......Voltage dips due to electrical grid faults generate transients of the generator electromagnetic torque which result in significant high stresses and noticeable vibrations for the wind turbine mechanical system. These events may also have a detrimental effect on the fatigue life of important...

  18. 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.

  19. High-speed Maglev studies in Canada

    International Nuclear Information System (INIS)

    Atherton, D.L.; Eastham, A.R.

    1974-01-01

    This paper reports on Canadian studies of superconducting magnetic levitation and variable-speed linear synchronous motor propulsion for high-speed inter-city guided ground transport. Levitation is obtained by the interaction of vehicle-mounted superconducting magnets and the eddy currents induced in aluminium strip conductors on the guideway. Non-contact propulsion by linear synchronous motor (LSM) is obtained by using vehicle-borne superconducting magnets and powered guideway coils. A suggested guidance scheme uses a flat guideway with 'null-flux' loops overlying the LSM windings. The propulsion magnets interact with the loops and the edges of the levitation strips to provide lateral stabilization. The test facility is a 7.6m wheel, rotating with a peripheral speed of 33m/s. (author)

  20. High speed printing with polygon scan heads

    Science.gov (United States)

    Stutz, Glenn

    2016-03-01

    To reduce and in many cases eliminate the costs associated with high volume printing of consumer and industrial products, this paper investigates and validates the use of the new generation of high speed pulse on demand (POD) lasers in concert with high speed (HS) polygon scan heads (PSH). Associated costs include consumables such as printing ink and nozzles, provisioning labor, maintenance and repair expense as well as reduction of printing lines due to high through put. Targets that are applicable and investigated include direct printing on plastics, printing on paper/cardboard as well as printing on labels. Market segments would include consumer products (CPG), medical and pharmaceutical products, universal ID (UID), and industrial products. In regards to the POD lasers employed, the wavelengths include UV(355nm), Green (532nm) and IR (1064nm) operating within the repetition range of 180 to 250 KHz.

  1. Potential scenarios of concern for high speed rail operations

    Science.gov (United States)

    2011-03-16

    Currently, multiple operating authorities are proposing the : introduction of high-speed rail service in the United States. : While high-speed rail service shares a number of basic : principles with conventional-speed rail service, the operational : ...

  2. Controls of Hydraulic Wind Turbine

    Directory of Open Access Journals (Sweden)

    Zhang Yin

    2016-01-01

    Full Text Available In this paper a hydraulic wind turbine generator system was proposed based on analysis the current wind turbines technologies. The construction and principles were introduced. The mathematical model was verified using MATLAB and AMsim. A displacement closed loop of swash plate of motor and a speed closed loop of generator were setup, a PID control is introduced to maintain a constant speed and fixed frequency at wind turbine generator. Simulation and experiment demonstrated that the system can connect grid to generate electric and enhance reliability. The control system demonstrates a high performance speed regulation and effectiveness. The results are great significant to design a new type hydraulic wind turbine system.

  3. Data Capture Technique for High Speed Signaling

    Science.gov (United States)

    Barrett, Wayne Melvin; Chen, Dong; Coteus, Paul William; Gara, Alan Gene; Jackson, Rory; Kopcsay, Gerard Vincent; Nathanson, Ben Jesse; Vranas, Paylos Michael; Takken, Todd E.

    2008-08-26

    A data capture technique for high speed signaling to allow for optimal sampling of an asynchronous data stream. This technique allows for extremely high data rates and does not require that a clock be sent with the data as is done in source synchronous systems. The present invention also provides a hardware mechanism for automatically adjusting transmission delays for optimal two-bit simultaneous bi-directional (SiBiDi) signaling.

  4. Flow in Pelton turbines

    OpenAIRE

    Furnes, Kjartan

    2013-01-01

    The flow in Pelton turbines is subsonic, turbulent, multiphase (water, air, and water vapor from cavitation), has high speeds, sharp gradients, free surface and dynamic boundary conditions. A static grid is unsuitable for modeling this mainly due to the turbine wheel and the liquid having a non-stationary relative motion.In recent times, significant progress in CFD simulation has been made, which also is relevant for Pelton turbines.Nevertheless, it is still common to perform costly model tes...

  5. Copper infiltrated high speed steels based composites

    International Nuclear Information System (INIS)

    Madej, M.; Lezanski, J.

    2003-01-01

    High hardness, mechanical strength, heat resistance and wear resistance of M3/2 high speed steel (HSS) make it an attractive material. Since technological and economical considerations are equally important, infiltration of high-speed steel skeleton with liquid cooper has proved to be a suitable technique whereby fully dense material is produced at low cost. Attempts have been made to describe the influence of the production process parameters and alloying additives, such as tungsten carbide on the microstructure and mechanical properties of copper infiltrated HSS based composites. The compositions of powder mixtures are 100% M3/2, M3/2+10% Wc, M3/2=30% WC. The powders were uniaxially cold compacted in a cylindrical die at 800 MPa. The green compacts were sintered in vacuum at 1150 o C for 60 minutes. Thereby obtained porous skeletons were subsequently infiltrated with cooper, by gravity method, in vacuum furnace at 1150 o C for 15 minutes. (author)

  6. Fuel Flexible Combustion Systems for High-Efficiency Utilization of Opportunity Fuels in Gas Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Venkatesan, Krishna

    2011-11-30

    The purpose of this program was to develop low-emissions, efficient fuel-flexible combustion technology which enables operation of a given gas turbine on a wider range of opportunity fuels that lie outside of current natural gas-centered fuel specifications. The program encompasses a selection of important, representative fuels of opportunity for gas turbines with widely varying fundamental properties of combustion. The research program covers conceptual and detailed combustor design, fabrication, and testing of retrofitable and/or novel fuel-flexible gas turbine combustor hardware, specifically advanced fuel nozzle technology, at full-scale gas turbine combustor conditions. This project was performed over the period of October 2008 through September 2011 under Cooperative Agreement DE-FC26-08NT05868 for the U.S. Department of Energy/National Energy Technology Laboratory (USDOE/NETL) entitled "Fuel Flexible Combustion Systems for High-Efficiency Utilization of Opportunity Fuels in Gas Turbines". The overall objective of this program was met with great success. GE was able to successfully demonstrate the operability of two fuel-flexible combustion nozzles over a wide range of opportunity fuels at heavy-duty gas turbine conditions while meeting emissions goals. The GE MS6000B ("6B") gas turbine engine was chosen as the target platform for new fuel-flexible premixer development. Comprehensive conceptual design and analysis of new fuel-flexible premixing nozzles were undertaken. Gas turbine cycle models and detailed flow network models of the combustor provide the premixer conditions (temperature, pressure, pressure drops, velocities, and air flow splits) and illustrate the impact of widely varying fuel flow rates on the combustor. Detailed chemical kinetic mechanisms were employed to compare some fundamental combustion characteristics of the target fuels, including flame speeds and lean blow-out behavior. Perfectly premixed combustion experiments were conducted to

  7. Speed regulation of water turbines by status feedback; Drehzahlregelung von Wasserturbinen mit Zustandsreglern

    Energy Technology Data Exchange (ETDEWEB)

    Maurer, W.

    1990-12-31

    The development of a speed controller by state freedback for water turbines will be presented. The possible improvement of the dynamic behaviour of the whole hydro power plant will be shown. The interaction of automatic control with the system and the influence of real working conditions will be described in detail. The procedure of controller design and the development of the description of the system in state equations will be explained. In addition to this the development of a digital program for the nonlinear simulation of hydro power plants will be presented. (orig.) [Deutsch] Die Entwicklung eines Zustandsreglers fuer die Drehzahlregelung von Wasserturbinen wird vorgestellt. Anhand nichtlinerer Simulationen wird die damit erzielbare Verbesserung des dynamischen Verhaltens der gesamten Wasserkraftanlage dokumentiert, sowie das Zusammenwirken mit regelungsnahen Steuerungen und der Einfluss praktischer Randbedingungen detailliert untersucht. Die Vorgehensweise beim Reglerentwurf und bei der Erstellung der dazu notwendigen linearen Beschreibung des dynamischen Verhaltens wird erlaeutert. Darueber hinaus wird die Entwicklung eines Programmsystems zur nichtlinearen Simulation von Wasserkraftanlagen beschrieben. (orig.)

  8. 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.

  9. 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.

  10. Speed regulation of water turbines by status feedback; Drehzahlregelung von Wasserturbinen mit Zustandsreglern

    Energy Technology Data Exchange (ETDEWEB)

    Maurer, W

    1991-12-31

    The development of a speed controller by state freedback for water turbines will be presented. The possible improvement of the dynamic behaviour of the whole hydro power plant will be shown. The interaction of automatic control with the system and the influence of real working conditions will be described in detail. The procedure of controller design and the development of the description of the system in state equations will be explained. In addition to this the development of a digital program for the nonlinear simulation of hydro power plants will be presented. (orig.) [Deutsch] Die Entwicklung eines Zustandsreglers fuer die Drehzahlregelung von Wasserturbinen wird vorgestellt. Anhand nichtlinerer Simulationen wird die damit erzielbare Verbesserung des dynamischen Verhaltens der gesamten Wasserkraftanlage dokumentiert, sowie das Zusammenwirken mit regelungsnahen Steuerungen und der Einfluss praktischer Randbedingungen detailliert untersucht. Die Vorgehensweise beim Reglerentwurf und bei der Erstellung der dazu notwendigen linearen Beschreibung des dynamischen Verhaltens wird erlaeutert. Darueber hinaus wird die Entwicklung eines Programmsystems zur nichtlinearen Simulation von Wasserkraftanlagen beschrieben. (orig.)

  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. 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.

  13. A New Apparatus for Measuring the Temperature at Machine Parts Rotating at High Speeds

    Science.gov (United States)

    Gnam, E.

    1945-01-01

    After a brief survey of the available methods for measuring the temperatures of machine parts at high speed, in particular turbine blades and rotors, an apparatus is described which is constructed on the principle of induction. Transmission of the measuring current by sliding contacts therefore is avoided. Up-to-date experiments show that it is possible to give the apparatus a high degree of sensitivity and accuracy. In comparison with sliding contact types, the present apparatus shows the important advantage that it operates for any length of time without wear, and that the contact difficulties, particularly occurring at high sliding speeds,are avoided.

  14. High speed imaging system for nuclear diagnostics

    International Nuclear Information System (INIS)

    Eyer, H.H.

    1976-01-01

    A high speed imaging system based on state-of-the-art photosensor arrays has been designed for use in nuclear diagnostics. The system is comprised of a front-end rapid-scan solid-state camera, a high speed digitizer, and a PCM line driver in a downhole package and a memory buffer system in a uphole trailer. The downhole camera takes a ''snapshot'' of a nuclear device created flux stream, digitizes the image and transmits it to the uphole memory system before being destroyed. The memory system performs two functions: it retains the data for local display and processing by a microprocessor, and it buffers the data for retransmission at slower rates to the LLL computational facility (NADS). The impetus for such a system as well as its operation are discussed. Also discussed are new systems under development which incorporate higher data rates and more resolution

  15. High speed imaging system for nuclear diagnostics

    International Nuclear Information System (INIS)

    Eyer, H.H.

    1976-01-01

    A high speed imaging system based on state-of-the-art photosensor arrays has been designed for use in nuclear diagnostics. The system is comprised of a front-end rapid-scan solid-state camera, a high speed digitizer, and a PCM line driver in a downhole package and a memory buffer system in an uphole trailer. The downhole camera takes a ''snapshot'' of a nuclear device created flux stream, digitizes the image and transmits it to the uphole memory system before being destroyed. The memory system performs two functions: it retains the data for local display and processing by a microprocessor, and it buffers the data for retransmission at slower rates to the LLL computational facility (NADS). The impetus for such a system as well as its operation is discussed. Also discussed are new systems under development which incorporate higher data rates and more resolution

  16. Design and Pitch Angle Optimisation of Horizontal Axis Hydrokinetic Turbine with Constant Tip Speed Ratio

    Directory of Open Access Journals (Sweden)

    Nigam Suyash

    2017-01-01

    Full Text Available Booming population and associated energy demands, looming threat of exhaustion of conventional sources of energy and the severe environmental repercussions of the same call for alternate sources of clean energy. Hydrokinetic turbine is one such developing technology which harnesses zero-head free flow of water and affects hydrological ecology minimally. This paper discusses the optimisation of Horizontal Axis Hydrokinetic Turbine (HAHkT blade chord length and twist angle using blade element momentum (BEM theory to achieve a constant optimal angle of attack (AoA, thus maximising the power output. To achieve this while maintaining robustness at the hub end and eliminate cavitation, two different hydrofoils (S832 and E817 are selected. S832 is simulated using ANSYS 14.0 at low (00 and high (150 angles of attack and compared against more widely used NACA 4412 to study flow separation characteristics. This is followed by calculating angles of relative flow, ratios of chord length and subsequently twist angles for each blade element using MATLAB simulations. A blade model is thus developed for visualisation using computer aided designing after obtaining optimal chord lengths and pitch angles.

  17. 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.

  18. High speed VLSI neural network for high energy physics

    NARCIS (Netherlands)

    Masa, P.; Masa, P.; Hoen, K.; Hoen, Klaas; Wallinga, Hans

    1994-01-01

    A CMOS neural network IC is discussed which was designed for very high speed applications. The parallel architecture, analog computing and digital weight storage provides unprecedented computing speed combined with ease of use. The circuit classifies up to 70 dimensional vectors within 20

  19. Development of high-speed video cameras

    Science.gov (United States)

    Etoh, Takeharu G.; Takehara, Kohsei; Okinaka, Tomoo; Takano, Yasuhide; Ruckelshausen, Arno; Poggemann, Dirk

    2001-04-01

    Presented in this paper is an outline of the R and D activities on high-speed video cameras, which have been done in Kinki University since more than ten years ago, and are currently proceeded as an international cooperative project with University of Applied Sciences Osnabruck and other organizations. Extensive marketing researches have been done, (1) on user's requirements on high-speed multi-framing and video cameras by questionnaires and hearings, and (2) on current availability of the cameras of this sort by search of journals and websites. Both of them support necessity of development of a high-speed video camera of more than 1 million fps. A video camera of 4,500 fps with parallel readout was developed in 1991. A video camera with triple sensors was developed in 1996. The sensor is the same one as developed for the previous camera. The frame rate is 50 million fps for triple-framing and 4,500 fps for triple-light-wave framing, including color image capturing. Idea on a video camera of 1 million fps with an ISIS, In-situ Storage Image Sensor, was proposed in 1993 at first, and has been continuously improved. A test sensor was developed in early 2000, and successfully captured images at 62,500 fps. Currently, design of a prototype ISIS is going on, and, hopefully, will be fabricated in near future. Epoch-making cameras in history of development of high-speed video cameras by other persons are also briefly reviewed.

  20. High speed PVD thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Beele, W. [Sulzer Metco Coatings BV (Netherlands); Eschendorff, G. [Sulzer Metco Coatings BV (Netherlands); Eldim BV (Netherlands)

    2006-07-15

    The high speed PVD process (HS-PVD) combines gas phase coating synthesis with high deposition rates. The process has been demonstrated for high purity YSZ deposited as a chemically bonded top thermal barrier with columnar structure of EB-PVD features. The process can manufacture EB-PVD like coatings that match in regards to their TGO-formation and columnar structure. Coatings with a columnar structure formed by individual columns of 1/4 of the diameter of a classical EB-PVD type TBC have been deposited. These coatings have the potential to prove a significant reduction in thermal conductivity and in erosion performance. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  1. High speed PVD thermal barrier coatings

    International Nuclear Information System (INIS)

    Beele, W.; Eschendorff, G.

    2006-01-01

    The high speed PVD process (HS-PVD) combines gas phase coating synthesis with high deposition rates. The process has been demonstrated for high purity YSZ deposited as a chemically bonded top thermal barrier with columnar structure of EB-PVD features. The process can manufacture EB-PVD like coatings that match in regards to their TGO-formation and columnar structure. Coatings with a columnar structure formed by individual columns of 1/4 of the diameter of a classical EB-PVD type TBC have been deposited. These coatings have the potential to prove a significant reduction in thermal conductivity and in erosion performance. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  2. Low Wind Speed Turbine Project Conceptual Design Study: Advanced Independent Pitch Control; July 30, 2002--July 31, 2004 (Revised)

    Energy Technology Data Exchange (ETDEWEB)

    Olsen, T.; Lang, E.; Hansen, A.C.; Cheney, M. C.; Quandt, G.; VandenBosche, J.; Meyer, T.

    2004-12-01

    AES conducted a conceptual study of independent pitch control using inflow angle sensors. The control strategy combined input from turbine states (rotor speed, rotor azimuth, each blade pitch) with inflow angle measurements (each blade angle of attack at station 11 of 15) to derive blade pitch demand signals. The controller reduced loads sufficiently to allow a 10% rotor extension and reduce COE by 6.3%.

  3. Speed Estimation in Geared Wind Turbines Using the Maximum Correlation Coefficient

    DEFF Research Database (Denmark)

    Skrimpas, Georgios Alexandros; Marhadi, Kun S.; Jensen, Bogi Bech

    2015-01-01

    to overcome the above mentioned issues. The high speed stage shaft angular velocity is calculated based on the maximum correlation coefficient between the 1 st gear mesh frequency of the last gearbox stage and a pure sinus tone of known frequency and phase. The proposed algorithm utilizes vibration signals...

  4. Design and development of gas turbine high temperature reactor 300

    International Nuclear Information System (INIS)

    Kunitomi, Kazuhiko; Katanishi, Shoji; Takada, Shoji; Yan, Xing; Takizuka, Takakazu

    2003-01-01

    JAERI (Japan Atomic Energy Research Institute) has been designing a Japan's original gas turbine high temperature reactor, GTHTR300 (Gas Turbine High Temperature Reactor 300). The greatly simplified design based on salient features of the HTGR (High Temperature Gas-cooled reactor) with a closed helium gas turbine enables the GTHTR300 a high efficient and economically competitive reactor to be deployed in early 2010s. Also, the GTHTR300 fully taking advantage of various experiences accumulated in design, construction and operation of the HTTR (High Temperature Engineering Test Reactor) and fossil gas turbine systems reduces technological development concerning a reactor system and electric generation system. Original features of this system are core design with two-year refueling interval, conventional steel material usage for a reactor pressure vessel, innovative plant flow scheme and horizontally installed gas turbine unit. Due to these salient features, the capital cost of the GTHTR300 is less than a target cost of 200 thousands Yen/kWe, and the electric generation cost is close to a target cost of 4 Yen/kWh. This paper describes the original design features focusing on reactor core design, fuel design, in-core structure design and reactor pressure vessel design except PCU design. Also, R and D for developing the power conversion unit is briefly described. The present study is entrusted from the Ministry of Education, Culture, Sports, Science and Technology of Japan. (author)

  5. Network Based High Speed Product Innovation

    DEFF Research Database (Denmark)

    Lindgren, Peter

    In the first decade of the 21st century, New Product Development has undergone major changes in the way NPD is managed and organised. This is due to changes in technology, market demands, and in the competencies of companies. As a result NPD organised in different forms of networks is predicted...... to be of ever-increasing importance to many different kinds of companies. This happens at the same times as the share of new products of total turnover and earnings is increasing at unprecedented speed in many firms and industries. The latter results in the need for very fast innovation and product development...... - a need that can almost only be resolved by organising NPD in some form of network configuration. The work of Peter Lindgren is on several aspects of network based high speed product innovation and contributes to a descriptive understanding of this phenomenon as well as with normative theory on how NPD...

  6. BLOSTREAM: A HIGH SPEED STREAM CIPHER

    Directory of Open Access Journals (Sweden)

    ALI H. KASHMAR

    2017-04-01

    Full Text Available Although stream ciphers are widely utilized to encrypt sensitive data at fast speeds, security concerns have led to a shift from stream to block ciphers, judging that the current technology in stream cipher is inferior to the technology of block ciphers. This paper presents the design of an improved efficient and secure stream cipher called Blostream, which is more secure than conventional stream ciphers that use XOR for mixing. The proposed cipher comprises two major components: the Pseudo Random Number Generator (PRNG using the Rabbit algorithm and a nonlinear invertible round function (combiner for encryption and decryption. We evaluate its performance in terms of implementation and security, presenting advantages and disadvantages, comparison of the proposed cipher with similar systems and a statistical test for randomness. The analysis shows that the proposed cipher is more efficient, high speed, and secure than current conventional stream ciphers.

  7. High-speed reconstruction of compressed images

    Science.gov (United States)

    Cox, Jerome R., Jr.; Moore, Stephen M.

    1990-07-01

    A compression scheme is described that allows high-definition radiological images with greater than 8-bit intensity resolution to be represented by 8-bit pixels. Reconstruction of the images with their original intensity resolution can be carried out by means of a pipeline architecture suitable for compact, high-speed implementation. A reconstruction system is described that can be fabricated according to this approach and placed between an 8-bit display buffer and the display's video system thereby allowing contrast control of images at video rates. Results for 50 CR chest images are described showing that error-free reconstruction of the original 10-bit CR images can be achieved.

  8. 脉冲 Er:YAG 激光与常规涡轮高速车针治疗楔状缺损的效果比较%The Effect Comparasion between the Pulse Er:YAG Laser and the Conventional Turbine High-speed Dental Bur to the Remedy of Teeth Wedge-shaped Defect

    Institute of Scientific and Technical Information of China (English)

    范伟; 贺慧霞

    2015-01-01

    目的:比较Er:YAG激光与常规涡轮机高速车针治疗楔状缺损的效果。方法收集我院口腔科就诊的、双侧多个同名牙楔状缺损患者85例382颗牙,随机分为激光组和涡轮机组各191牙,其中每位患者每侧至少2颗牙采用激光表面预备,对侧高速涡轮机预备,脉冲照射采用激光剂量为300 mJ,20 Hz间歇操作。涡轮机组采用高速车针制备固位型,自体对照,两组均预备后光固化树脂黏充填。比较两组治疗后1周、1个月、6个月、12个月术后充填物保存率、边缘着色、继发龋等指标,评价其临床治疗效果。结果两组术中疼痛牙齿发生率激光组(16.7%)显著少于涡轮机组(74.8%),差异有统计学意义(P<0.05);术后1周、1个月激光组分别有35牙和12牙出现冷热刺激痛,而涡轮机组发生刺激痛分别为83牙和44牙,两者差异有统计学意义( P<0.05);术后6个月和12个月修复体保存率激光组显著高于涡轮机组,差异有统计学意义( P<0.05);但边缘适合性、边缘着色和继发龋发生率两组差异无统计学意义。结论激光组较涡轮机组在楔状缺损治疗中疼痛发生率低、治疗后疼痛反应轻;修复体保存率高。300 mJ,20 Hz的Er:YAG激光治疗楔状缺损具有无痛、安全、高效的优点。%Objective To compare the effects of Er: YAG laser and conventional high-speed burr in treatment of wedge-shaped tooth defects and to evaluate its applicability and reliability .Methods 382 bilateral multiple teeth with wedge-shaped defects in 85 patients were randomly divided into two groups with 191 teeth in each:laser group and the turbine burr group .At least two teeth of one side in all patients were irradiated by pulsed Er:YAG laser with doses of 300 mj, 20 Hz.Meanwhile, the caries cavities on the contralateral were prepared by high-speed burr .Then the prepared caries defects in both

  9. Brittle Materials Design, High Temperature Gas Turbine

    Science.gov (United States)

    1977-08-01

    Radiation Pyrometer Mounting in the Hot Spin Rig 47 Showing Tempeiature Measurement Locations on a Test Rotor Figure 3.23 Stainless Steel Insulator...analysis in hot pressed Si3N4 (3,4,6). • Acoustic emission was applied for the detection of crack propagation and the onset of catastrophic failure in...scanning with acoustic emission (4). • X-ray radiography was applied for the detection of internal defects in turbine ceramic components (2,3.4,5)1

  10. Cavitation induced by high speed impact of a solid surface on a liquid jet

    Science.gov (United States)

    Farhat, Mohamed; Tinguely, Marc; Rouvinez, Mathieu

    2009-11-01

    A solid surface may suffer from severe erosion if it impacts a liquid jet at high speed. The physics behind the erosion process remains unclear. In the present study, we have investigated the impact of a gun bullet on a laminar water jet with the help of a high speed camera. The bullet has a flat front and 11 mm diameter, which is half of jet diameter. The impact speed was varied between 200 and 500 ms-1. Immediately after the impact, a systematic shock wave and high speed jetting were observed. As the compression waves reflect on the jet boundary, a spectacular number of vapour cavities are generated within the jet. Depending on the bullet velocity, these cavities may grow and collapse violently on the bullet surface with a risk of cavitation erosion. We strongly believe that this transient cavitation is the main cause of erosion observed in many industrial applications such as Pelton turbines.

  11. Design of very high speed electric generators

    International Nuclear Information System (INIS)

    Labollita, Santiago

    2008-01-01

    This work approaches the design process of an electric generator suitable for running efficiently at high speed, driven by a turbo shaft.The axial flux concept was used.For the mechanical design of the prototype, cooling capacity and mounting method were considered, looking for simplicity of the parts evolved. Neodymium-iron-boron permanent magnets were used as magnetic source.For the electrical design, a calculation tool was developed in order to predict the prototype electrical parameters and optimize its geometry.The goal was to obtain 1 kW of electric power at a speed of 100,000 rpm.The efficiency and electrical behaviour of the prototype were characterized at speeds between 2,000 rpm and 30,000 rpm and then the behaviour at the design condition was predicted by obtaining an equivalent electric circuit.The estimated load voltage was 237 V as well as an electrical efficiency of 95%.Eddy current effects were not recognized. Increase of the internal resistance and decree of inductance were observed while raising the electric frequency.Finally, an electronic system was developed in order to use the prototype as a c.c. motor. Global performance was measured according to different supply characteristic. An optimum supply voltage was found.A maximum efficiency of 63% was reached. [es

  12. High-pressure turbine deposition in land-based gas turbines from various synfuels

    Energy Technology Data Exchange (ETDEWEB)

    Bons, J.P.; Crosby, J.; Wammack, J.E.; Bentley, B.I.; Fletcher, T.H. [Brigham Young University, Provo, UT (United States). Dept. of Mechanical Engineering

    2007-01-15

    Ash deposits from four candidate power turbine synfuels were studied in an accelerated deposition test facility. The facility matches the gas temperature and velocity of modern first-stage high-pressure turbine vanes. A natural gas combustor was seeded with finely ground fuel ash particulate from four different fuels: straw, sawdust, coal, and petroleum coke. The entrained ash particles were accelerated to a combustor exit flow Mach number of 0.31 before impinging on a thermal barrier coating (TBC) target coupon at 1150{sup o}C. Postexposure analyses included surface topography, scanning electron microscopy and x-ray spectroscopy. Due to significant differences in the chemical composition of the various fuel ash samples, deposit thickness and structure vary considerably for fuel. Biomass products (e.g., sawdust and straw) are significantly less prone to deposition than coal and petcoke for the same particle loading conditions. In a test simulating one turbine operating year at a moderate particulate loading of 0.02 parts per million by weight, deposit thickness from coal and petcoke ash exceeded 1 and 2 mm, respectively. These large deposits from coal and petcoke were found to detach readily from the turbine material with thermal cycling and handling. The smaller biomass deposit samples showed greater tenacity, in adhering to the TBC surface. In all cases, corrosive elements (e.g., Na, K, V, Cl, S) were found to penetrate the TBC layer during the accelerated deposition test. Implications for the power generation goal of fuel flexibility are discussed.

  13. 14 CFR 23.253 - High speed characteristics.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false High speed characteristics. 23.253 Section... Requirements § 23.253 High speed characteristics. If a maximum operating speed VMO/MMO is established under § 23.1505(c), the following speed increase and recovery characteristics must be met: (a) Operating...

  14. Development history of the gas turbine modular high temperature reactor

    International Nuclear Information System (INIS)

    Brey, H.L.

    2001-01-01

    The development of the high temperature gas cooled reactor (HTGR) as an environmentally agreeable and efficient power source to support the generation of electricity and achieve a broad range of high temperature industrial applications has been an evolutionary process spanning over four decades. This process has included ongoing major development in both the HTGR as a nuclear energy source and associated power conversion systems from the steam cycle to the gas turbine. This paper follows the development process progressively through individual plant designs from early research of the 1950s to the present focus on the gas turbine modular HTGR. (author)

  15. Continuous QKD and high speed data encryption

    Science.gov (United States)

    Zbinden, Hugo; Walenta, Nino; Guinnard, Olivier; Houlmann, Raphael; Wen, Charles Lim Ci; Korzh, Boris; Lunghi, Tommaso; Gisin, Nicolas; Burg, Andreas; Constantin, Jeremy; Legré, Matthieu; Trinkler, Patrick; Caselunghe, Dario; Kulesza, Natalia; Trolliet, Gregory; Vannel, Fabien; Junod, Pascal; Auberson, Olivier; Graf, Yoan; Curchod, Gilles; Habegger, Gilles; Messerli, Etienne; Portmann, Christopher; Henzen, Luca; Keller, Christoph; Pendl, Christian; Mühlberghuber, Michael; Roth, Christoph; Felber, Norbert; Gürkaynak, Frank; Schöni, Daniel; Muheim, Beat

    2013-10-01

    We present the results of a Swiss project dedicated to the development of high speed quantum key distribution and data encryption. The QKD engine features fully automated key exchange, hardware key distillation based on finite key security analysis, efficient authentication and wavelength division multiplexing of the quantum and the classical channel and one-time pas encryption. The encryption device allows authenticated symmetric key encryption (e.g AES) at rates of up to 100 Gb/s. A new quantum key can uploaded up to 1000 times second from the QKD engine.

  16. High speed UNIBUS-VME interface

    International Nuclear Information System (INIS)

    Olmos, P.

    1987-01-01

    An interface between VME an the UNIBUS of PDP or VAX computer is presented. The system supports high speed parallel communication (up to 1MB/S) and is composed of two modules. One of these is a commercial DR11M board which performs DMA transfers between UNIBUS and the external word. The other is a VME module specifically developed for this application. The interface has been tested under VMS operating system in VAX and VALET-PLUS system for the VME Bus. We describe in detail the VME module and its connection with the DR11M. Software, both in WMS and VALET, is also described. (Author) 7 refs

  17. Aerodynamic and Performance Behavior of a Three-Stage High Efficiency Turbine at Design and Off-Design Operating Points

    Directory of Open Access Journals (Sweden)

    M. T. Schobeiri

    2004-01-01

    Full Text Available This article deals with the aerodynamic and performance behavior of a three-stage high pressure research turbine with 3-D curved blades at its design and off-design operating points. The research turbine configuration incorporates six rows beginning with a stator row. Interstage aerodynamic measurements were performed at three stations, namely downstream of the first rotor row, the second stator row, and the second rotor row. Interstage radial and circumferential traversing presented a detailed flow picture of the middle stage. Performance measurements were carried out within a rotational speed range of 75% to 116% of the design speed. The experimental investigations have been carried out on the recently established multi-stage turbine research facility at the Turbomachinery Performance and Flow Research Laboratory, TPFL, of Texas A&M University.

  18. A Low Speed BIST Framework for High Speed Circuit Testing

    NARCIS (Netherlands)

    Speek, H.; Kerkhoff, Hans G.; Shashaani, M.; Sachdev, M.

    2000-01-01

    Testing of high performance integrated circuits is becoming increasingly a challenging task owing to high clock frequencies. Often testers are not able to test such devices due to their limited high frequency capabilities. In this article we outline a design-for-test methodology such that high

  19. Influence of wind farm capacity, turbine size and wind speed on production cost: analysis of the actual market trend

    International Nuclear Information System (INIS)

    Laali, A.-R.; Meyer, J.-L.

    1996-01-01

    Several studies are undertaken in R and D Division of EDF in collaboration with ERASME association in order to have a good knowledge of the wind energy production costs. These studies are performed in the framework of a wind energy monitoring project and concern the influence of a few parameters like wind farm capacity, turbine size and wind speed on production costs, through an analysis of the actual market trend. Some 50 manufacturers and 140 different kind of wind turbines are considered for this study. The minimum production cost is situated at 800/900 kW wind turbine rated power. This point will probably move to more important powers in the future. This study is valid only for average conditions and some special parameters like particular climate conditions or lack of infrastructure for a special site that could modify the results shown on the curves. The variety of wind turbines (rated power as a function of rotor diameter, height and specific rated power) in the actual market is analysed. A brief analysis of the market trend is also performed. (author)

  20. Hydraulic turbines and auxiliary equipment

    Energy Technology Data Exchange (ETDEWEB)

    Luo Gaorong [Organization of the United Nations, Beijing (China). International Centre of Small Hydroelectric Power Plants

    1995-07-01

    This document presents a general overview on hydraulic turbines and auxiliary equipment, emphasizing the turbine classification, in accordance with the different types of turbines, standard turbine series in China, turbine selection based on the basic data required for the preliminary design, general hill model curves, chart of turbine series and the arrangement of application for hydraulic turbines, hydraulic turbine testing, and speed regulating device.

  1. 风机转动速度调节的PID优化算法研究%Research on PID Optimization Algorithm for Rotating Speed Regulation of Wind Turbine

    Institute of Scientific and Technical Information of China (English)

    李家伟

    2015-01-01

    With control optimizing of the rotational speed of the wind turbine, improve the output power and the power trans-mission efficiency of the wind turbine, the interference of magnetic loss coupling by the wind turbine rotor blade in the con-trol, it is difficult to achieve effective speed regulation, The algorithm has the defects of nonlinear distortion. A wind turbine of PID based on optimal control of rotating speed adjustment optimization, analysis of rotating speed adjusting parameter model of wind turbine, the wind turbine rotor blade speed adjustment control optimization objective function, the design of three layers PID neural network, the PID variable structure control, wind turbine speed shaft connected with the rotor axis the gear box, the aerodynamic excitation brake operation, speed regulation, effectively restrain the interference of wind tur-bine rotor blade control strong coupling magnetic loss, improve the speed of rotation to adjust the output control perfor-mance of wind turbine. The simulation results show that, the method can effectively realize the wind turbine speed control, it can improve the wind turbine efficiency and output gain.%通过对风机转动速度的优化控制调节,提高风机的输出功率和电能传输效率,风机转子叶片控制中受到强耦合的磁损耗的干扰,难以实现有效的转速调节,提出一种基于PID优化控制的风机转动速度调节优化算法,分析风机转动速度调节控制参数模型,构建风机转子叶片速度调节的优化控制目标函数,设计三层前向PID神经网络,通过PID变结构控制,风机的低速轴将转子轴心与齿轮箱连接,激发空气动力闸的运行,进行转速调节,有效地抑制了风机转子叶片控制中强耦合磁损耗的干扰,提高了风机转动速度调节输出控制性能.仿真结果表明,采用该方法能有效实现风机转速调节控制,提高风机运行效率和输出增益.

  2. Investigations on high speed MHD liquid flow

    International Nuclear Information System (INIS)

    Yamasaki, Takasuke; Kamiyama, Shin-ichi.

    1982-01-01

    Lately, the pressure drop problem of MHD two-phase flow in a duct has been investigated theoretically and experimentally in conjunction with the problems of liquid metal MHD two-phase flow power-generating cycle or of liquid metal boiling two-phase flow in the blanket of a nuclear fusion reactor. Though many research results have been reported so far for MHD single-phase flow, the hydrodynamic studies on high speed two-phase flow are reported only rarely, specifically the study dealing with the generation of cavitation is not found. In the present investigation, the basic equation was derived, analyzing the high speed MHD liquid flow in a diverging duct as the one-dimensional flow of homogeneous two-phase fluid of small void ratio. Furthermore, the theoretical solution for the effect of magnetic field on cavitation-generating conditions was tried. The pressure distribution in MHD flow in a duct largely varies with load factor, and even if the void ratio is small, the pressure distribution in two-phase flow is considerably different from that in single-phase flow. Even if the MHD two-phase flow in a duct is subsonic flow at the throat, the critical conditions may be achieved sometimes in a diverging duct. It was shown that cavitation is more likely to occur as magnetic field becomes more intense if it is generated downstream of the throat. This explains the experimental results qualitatively. (Wakatsuki, Y.)

  3. High-speed motion neutron radiography

    International Nuclear Information System (INIS)

    Bossi, R.H.; Barton, J.P.; Robinson, A.H.

    1982-01-01

    A system has been developed to perform neutron radiographic analysis of dynamic events having a duration of several milliseconds. The system has been operated in the range of 2000 to 10,000 frames. Synchronization has provided high-speed motion neutron radiographs for evaluation of the firing cycles of 7.62-mm munition rounds within a thick steel rifle barrel. The system has also been used to demonstrate its ability to produce neutron radiographic movies of two-phase flow. The equipment includes a TRIGA reactor capable of pulsing to a peak power of 3000 MW, a neutron beam collimator, a scintillator neutron conversion screen coupled to an image intensifier, and a 16-mm high-speed movie camera. The peak neutron flux incident at the object position is about 4 X 10 11 n/cm 2 X s with a pulse, full-width at half-maximum, of 9 ms. Modulation transfer function techniques have been used to assist optimization of the system performance. Special studies have been performed on the scintillator conversion screens and on the effects of statistical limitations on information availability

  4. 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.

  5. The design of wind turbine for electrical power generation in Malaysian wind characteristics

    International Nuclear Information System (INIS)

    Abas Ab Wahab; Chong Wen Thong

    2000-01-01

    The paper describes the study of a wind turbine for electrical power generation in Malaysia wind characteristics. In this research, the wind turbine is designs based on the local wind characteristics and tries to avoid the problems faced in the past (turbine design, access, manpower and technical). The new wind turbine rotor design for a medium speed wind speed turbine utilises the concept of open-close type of horizontal axis (up-wind) wind turbine is intended to widen the optimum performance range for electrical generation in Malaysia wind characteristics. The wind turbine has been designed to cut-in at a lower speed, and to provide the rotation speed that high enough to run a generator. The analysis and design of new low speed wind turbine blades and open-close turbine rotor and prediction of turbine performance are being detailed in this paper. (Author)

  6. High-fidelity Modeling of Local Effects of Damage for Derated Offshore Wind Turbines

    International Nuclear Information System (INIS)

    Richards, Phillip W; Griffith, D Todd; Hodges, Dewey H

    2014-01-01

    Offshore wind power production is an attractive clean energy option, but the difficulty of access can lead to expensive and rare opportunities for maintenance. As part of the Structural Health and Prognostics Management (SHPM) project at Sandia National Laboratories, smart loads management (controls) are investigated for their potential to increase the fatigue life of offshore wind turbine rotor blades. Derating refers to altering the rotor angular speed and blade pitch to limit power production and loads on the rotor blades. High- fidelity analysis techniques like 3D finite element modeling (FEM) should be used alongside beam models of wind turbine blades to characterize these control strategies in terms of their effect to mitigate fatigue damage and extend life of turbine blades. This study will consider a commonly encountered damage type for wind turbine blades, the trailing edge disbond, and show how FEM can be used to quantify the effect of operations and control strategies designed to extend the fatigue life of damaged blades. The Virtual Crack Closure Technique (VCCT) will be used to post-process the displacement and stress results to provide estimates of damage severity/criticality and provide a means to estimate the fatigue life under a given operations and control strategy

  7. High-fidelity Modeling of Local Effects of Damage for Derated Offshore Wind Turbines

    Science.gov (United States)

    Richards, Phillip W.; Griffith, D. Todd; Hodges, Dewey H.

    2014-06-01

    Offshore wind power production is an attractive clean energy option, but the difficulty of access can lead to expensive and rare opportunities for maintenance. As part of the Structural Health and Prognostics Management (SHPM) project at Sandia National Laboratories, smart loads management (controls) are investigated for their potential to increase the fatigue life of offshore wind turbine rotor blades. Derating refers to altering the rotor angular speed and blade pitch to limit power production and loads on the rotor blades. High- fidelity analysis techniques like 3D finite element modeling (FEM) should be used alongside beam models of wind turbine blades to characterize these control strategies in terms of their effect to mitigate fatigue damage and extend life of turbine blades. This study will consider a commonly encountered damage type for wind turbine blades, the trailing edge disbond, and show how FEM can be used to quantify the effect of operations and control strategies designed to extend the fatigue life of damaged blades. The Virtual Crack Closure Technique (VCCT) will be used to post-process the displacement and stress results to provide estimates of damage severity/criticality and provide a means to estimate the fatigue life under a given operations and control strategy.

  8. 14 CFR 25.253 - High-speed characteristics.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false High-speed characteristics. 25.253 Section...-speed characteristics. (a) Speed increase and recovery characteristics. The following speed increase and recovery characteristics must be met: (1) Operating conditions and characteristics likely to cause...

  9. Florida intercity high speed rail passenger service

    Energy Technology Data Exchange (ETDEWEB)

    Najafi, F.T.; Watford, S.; Moore, G.; Des, A. [Florida Univ., Gainesville, FL (United States). Dept. of Civil Engineering

    1997-10-01

    Plans for a new high-speed rail (HSR) transportation system in Florida were reviewed. HSR is believed to be the least expensive, most energy-efficient and least environmentally harmful alternative to air and highway travel. The system in Florida will be used as a case study to determine its overall impact on the environment, people and economy. The 300-plus mile system will move travelers at speeds of over 200 mph between Miami, Orlando, and Tampa. The study will identify the impacts of a HSR system on existing transportation networks, environment, energy, growth and growth distribution, safety, economy, travel time, and tourism. Transportation problems and the innovative mechanisms needed to realize the joint public and private venture approach to planning, locating, permitting, managing, financing, constructing and maintaining an inter-regional HSR line for the state were studied. The all-electric train would greatly help the environment in two ways: (1) zero emissions from the train itself, and (2) the reduction of trips by automobile and aircraft would reduce the amount of fuel and energy being used. 4 refs., 1 fig.

  10. High-Speed RaPToRS

    Science.gov (United States)

    Henchen, Robert; Esham, Benjamin; Becker, William; Pogozelski, Edward; Padalino, Stephen; Sangster, Thomas; Glebov, Vladimir

    2008-11-01

    The High-Speed Rapid Pneumatic Transport of Radioactive Samples (HS-RaPToRS) system, designed to quickly and safely move radioactive materials, was assembled and tested at the Mercury facility of the Naval Research Laboratory (NRL) in Washington D.C. A sample, which is placed inside a four-inch-diameter carrier, is activated before being transported through a PVC tube via airflow. The carrier travels from the reaction chamber to the end station where it pneumatically brakes prior to the gate. A magnetic latch releases the gate when the carrier arrives and comes to rest. The airflow, optical carrier-monitoring devices, and end gate are controlled manually or automatically with LabView software. The installation and testing of the RaPToRS system at NRL was successfully completed with transport times of less than 3 seconds. The speed of the carrier averaged 16 m/s. Prospective facilities for similar systems include the Laboratory for Laser Energetics and the National Ignition Facility.

  11. Overview and Design of self-acting pitch control mechanism for vertical axis wind turbine using multi body simulation approach

    DEFF Research Database (Denmark)

    Chougule, Prasad; Nielsen, Søren R.K.

    2014-01-01

    Awareness about wind energy is constantly growing in the world. Especially a demand for small scale wind turbine is increasing and various products are available in market. There are mainly two types of wind turbines, horizontal axis wind turbine and vertical axis wind turbines. Horizontal axis...... wind turbines are suitable for high wind speed whereas vertical axis wind turbines operate relatively low wind speed area. Vertical axis wind turbines are cost effective and simple in construction as compared to the horizontal axis wind turbine. However, vertical axis wind turbines have inherent...

  12. Impact of fault ride-through requirements on fixed-speed wind turbine structural loads

    DEFF Research Database (Denmark)

    Hansen, Anca Daniela; Cutululis, Nicolaos Antonio; Markou, Helen

    2011-01-01

    by performing a rainflow and a statistical analysis for fatigue and ultimate structural loads, respectively. Two cases are compared i.e. one where the turbine is immediately disconnected from the grid when a grid fault occurs and one where the turbine is equipped with a fault ride-through controller...... and therefore it is able to remain connected to the grid during the grid fault. Copyright © 2010 John Wiley & Sons, Ltd....

  13. A highly efficient Francis turbine designed for energy recovery in cooling towers

    Directory of Open Access Journals (Sweden)

    Daqing Zhou

    2015-03-01

    Full Text Available In China, cooling water entering cooling towers still retains surplus pressure between 39,240 and 147,150 Pa. In order to utilize this wasted energy, it is suggested that the surplus water energy can be harnessed to drive a type of hydroturbine installed in the inner platform of cooling tower and make the fan rotate via its coupled shafts. However, conventional hydroturbines are not suited for this job because of their low efficiency or unmatched rotating speed with that of the fan under the operating conditions of cooling towers. In this article, according to the requirements of turbine work environment in cooling towers, a new type of hydroturbine, Francis turbine with ultra-low specific speed (ns  = 50 m.kW, was designed to replace the fan motor in a cooling tower. Primarily, the shape, position, and number of runner blades were designed and optimized through theoretical analyses and computational fluid dynamics simulations. Additionally, metal elliptical volute and single-row ring guide vanes were applied to scale down the structural dimensions. Finally, the optimal scheme of the new Francis turbine was proven to have a high efficiency of 88% and good operation stability through testing of a physical model and can achieve the goal of harvesting renewable energy in the cooling tower.

  14. Optimization of advenced liquid natural gas-fuelled combined cycle machinery systems for a high-speed ferry

    DEFF Research Database (Denmark)

    Tveitaskog, Kari Anne; Haglind, Fredrik

    2012-01-01

    . Furthermore, practical and operational aspects of using these three machinery systems for a high-speed ferry are discussed. Two scenarios are evaluated. The first scenario evaluates the combined cycles with a given power requirement, optimizing the combined cycle while operating the gas turbine at part load...

  15. Using a High-Speed Camera to Measure the Speed of Sound

    Science.gov (United States)

    Hack, William Nathan; Baird, William H.

    2012-01-01

    The speed of sound is a physical property that can be measured easily in the lab. However, finding an inexpensive and intuitive way for students to determine this speed has been more involved. The introduction of affordable consumer-grade high-speed cameras (such as the Exilim EX-FC100) makes conceptually simple experiments feasible. Since the…

  16. High speed operation of permanent magnet machines

    Science.gov (United States)

    El-Refaie, Ayman M.

    This work proposes methods to extend the high-speed operating capabilities of both the interior PM (IPM) and surface PM (SPM) machines. For interior PM machines, this research has developed and presented the first thorough analysis of how a new bi-state magnetic material can be usefully applied to the design of IPM machines. Key elements of this contribution include identifying how the unique properties of the bi-state magnetic material can be applied most effectively in the rotor design of an IPM machine by "unmagnetizing" the magnet cavity center posts rather than the outer bridges. The importance of elevated rotor speed in making the best use of the bi-state magnetic material while recognizing its limitations has been identified. For surface PM machines, this research has provided, for the first time, a clear explanation of how fractional-slot concentrated windings can be applied to SPM machines in order to achieve the necessary conditions for optimal flux weakening. A closed-form analytical procedure for analyzing SPM machines designed with concentrated windings has been developed. Guidelines for designing SPM machines using concentrated windings in order to achieve optimum flux weakening are provided. Analytical and numerical finite element analysis (FEA) results have provided promising evidence of the scalability of the concentrated winding technique with respect to the number of poles, machine aspect ratio, and output power rating. Useful comparisons between the predicted performance characteristics of SPM machines equipped with concentrated windings and both SPM and IPM machines designed with distributed windings are included. Analytical techniques have been used to evaluate the impact of the high pole number on various converter performance metrics. Both analytical techniques and FEA have been used for evaluating the eddy-current losses in the surface magnets due to the stator winding subharmonics. Techniques for reducing these losses have been

  17. High Speed Magnetostrictive MEMS Actuated Mirror Deflectors, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The main goal of this proposal is to develop high speed magnetostrictive and MEMS actuators for rapidly deflecting or deforming mirrors. High speed, light-weight,...

  18. High-speed and intercity passenger rail testing strategy.

    Science.gov (United States)

    2013-05-01

    This high-speed and intercity passenger rail (HSIPR) testing strategy addresses the requirements for testing of high-speed train sets and technology before introduction to the North American railroad system. The report documents the results of a surv...

  19. A high current, high speed pulser using avalanche transistors

    International Nuclear Information System (INIS)

    Hosono, Yoneichi; Hasegawa, Ken-ichi

    1985-01-01

    A high current, high speed pulser for the beam pulsing of a linear accelerator is described. It uses seven avalanche transistors in cascade. Design of a trigger circuit to obtain fast rise time is discussed. The characteristics of the pulser are : (a) Rise time = 0.9 ns (FWHM) and (d) Life time asymptotically equals 2000 -- 3000 hr (at 50 Hz). (author)

  20. THE CHARACTERISTICS OF THE OPERATING PARAMETERS OF THE VERTICAL AXIS WIND TURBINE FOR THE SELECTED WIND SPEED

    Directory of Open Access Journals (Sweden)

    Zbigniew Czyż

    2017-03-01

    Full Text Available The article presents the results of examining a wind turbine on the vertical axis of rotation. The study was conducted in an open circuit wind tunnel Gunt HM 170 in the laboratory of the Department of Thermodynamics, Fluid Mechanics and Aviation Propulsion Systems in Lublin University of Technology. The subject of research was a rotor based on the patent PL 219985. The research object in the form of rotor consists of blades capable of altering the surface of the active area (receiving kinetic energy of the wind. The study was performed on appropriately scaled and geometrically similar models with maintaining, relevant to the type of research, the criterion numbers. Research objects in the form of rotors with different angles of divergence of blades were made using a 3D powder printer ZPrinter® 450. The results of the research conducted were carried out at the selected flow velocity of 6.5 m/s for three angles of divergence, ie. 30°, 60°, and 90° at variable rotational speed. The applied research station allows braking of the turbine to the required speed, recording velocity and torque, which allows to obtain characteristics of torque and power as a function of rotor speed.

  1. High-speed cineradiographies acquisition and processing

    International Nuclear Information System (INIS)

    Kahn, E.; Nourrissat, Yves; Viguier, Philippe

    A high-speed cineradiography installation provides dimensional informations recorded either on a film, or on a magnetic tape. In the event of the film, the imperfection of our visual sense leads us to look for a method of measurement which allows us to extract the information from a noisy image; the association of an optical flying spot scanner with a computer is adapted to this use and allows us, for instance, to determine the inside and outside diameters of a sphere during its implosion. On the other hand, the radiographic recording on magnetic tape is processed, after numerisation by the computer, in the same way as the numeric tape generated after the optical scanner. We compare the results achieved by the two recording methods [fr

  2. Inlet design for high-speed propfans

    Science.gov (United States)

    Little, B. H., Jr.; Hinson, B. L.

    1982-01-01

    A two-part study was performed to design inlets for high-speed propfan installation. The first part was a parametric study to select promising inlet concepts. A wide range of inlet geometries was examined and evaluated - primarily on the basis of cruise thrust and fuel burn performance. Two inlet concepts were than chosen for more detailed design studies - one apropriate to offset engine/gearbox arrangements and the other to in-line arrangements. In the second part of this study, inlet design points were chosen to optimize the net installed thrust, and detailed design of the two inlet configurations was performed. An analytical methodology was developed to account for propfan slipstream effects, transonic flow efects, and three-dimensional geometry effects. Using this methodology, low drag cowls were designed for the two inlets.

  3. High Speed/ Low Effluent Process for Ethanol

    Energy Technology Data Exchange (ETDEWEB)

    M. Clark Dale

    2006-10-30

    n this project, BPI demonstrated a new ethanol fermentation technology, termed the High Speed/ Low Effluent (HS/LE) process on both lab and large pilot scale as it would apply to wet mill and/or dry mill corn ethanol production. The HS/LE process allows very rapid fermentations, with 18 to 22% sugar syrups converted to 9 to 11% ethanol ‘beers’ in 6 to 12 hours using either a ‘consecutive batch’ or ‘continuous cascade’ implementation. This represents a 5 to 8X increase in fermentation speeds over conventional 72 hour batch fermentations which are the norm in the fuel ethanol industry today. The ‘consecutive batch’ technology was demonstrated on a large pilot scale (4,800 L) in a dry mill corn ethanol plant near Cedar Rapids, IA (Xethanol Biofuels). The pilot demonstrated that 12 hour fermentations can be accomplished on an industrial scale in a non-sterile industrial environment. Other objectives met in this project included development of a Low Energy (LE) Distillation process which reduces the energy requirements for distillation from about 14,000 BTU/gal steam ($0.126/gal with natural gas @ $9.00 MCF) to as low as 0.40 KW/gal electrical requirements ($0.022/gal with electricity @ $0.055/KWH). BPI also worked on the development of processes that would allow application of the HS/LE fermentation process to dry mill ethanol plants. A High-Value Corn ethanol plant concept was developed to produce 1) corn germ/oil, 2) corn bran, 3) ethanol, 4) zein protein, and 5) nutritional protein, giving multiple higher value products from the incoming corn stream.

  4. Parametric study of laminated composite material shaft of high speed rotor-bearing system

    Science.gov (United States)

    Gonsalves, Thimothy Harold; Kumar, G. C. Mohan; Ramesh, M. R.

    2018-04-01

    In this paper some of the important parameters that influence the effectiveness of composite material shaft of high speed rotor-bearing system on rotor dynamics are analyzed. The type of composite material composition, the number of layers along with their stacking sequences are evaluated as they play an important role in deciding the best configuration suitable for the high-speed application. In this work the lateral modal frequencies for five types of composite materials shaft of a high-speed power turbine rotor-bearing system and stresses due to operating torque are evaluated. The results are useful for the selection of right combination of material, number of layers and their stacking sequences. The numerical analysis is carried out using the ANSYS Rotor dynamic analysis features.

  5. High-speed railways in Japan

    International Nuclear Information System (INIS)

    Kyotani, Y.

    1974-01-01

    This paper reviews the development of conventional railways in Japan, leading up to the Shinkansen line, which at present runs at speeds up to 210km/h, and will in the future be speeded up to 260km/h. It then goes on to review the development of a superconductive, magnetically levitated train, which will constitute the next generation of railways, running at speeds of up to 500km/h. (author)

  6. High-speed Stochastic Fatigue Testing

    DEFF Research Database (Denmark)

    Brincker, Rune; Sørensen, John Dalsgaard

    1990-01-01

    Good stochastic fatigue tests are difficult to perform. One of the major reasons is that ordinary servohydraulic loading systems realize the prescribed load history accurately at very low testing speeds only. If the speeds used for constant amplitude testing are applied to stochastic fatigue...

  7. Modelling and Analysis of Variable Speed Wind Turbines with Induction Generator during Grid Fault

    DEFF Research Database (Denmark)

    Bolik, Sigrid Mechthild

    During recent years wind turbine technology has undergone rapid developments. Growth in size and the optimization of wind turbines has enabled wind energy to become increasingly competitive with conventional energy sources. As a result today's wind turbines participate actively in the power...... by any single modelling software program. In addition a huge range of in-house programs from different companies exist, the most widely known software for current research on the power grid are PSS/E, EMTDC/PSCAD and DigSilent. In general research and especially for control developments the software...... of the model. Investigations in optimisation of the implemented models are advised. Otherwise the presented models can be seen as basis for further modelling investigations. The developed models are open for further extension for different purpose, e.g. research of the harmonics. The introduced saturation...

  8. Application of high speed photography for high current vacuum arcs

    NARCIS (Netherlands)

    Damstra, G.C.; Merck, W.F.H.; Vossen, J.W.G.L.; Janssen, M.F.P.; Bouwmeester, C.E.

    1998-01-01

    A high speed image detection system for 106 frames per second or 107 streaks per second has been developed for the testing of vacuum circuit breakers, using 10×16 optical fibres for light transfer to 160 fast photo diodes. The output of these diodes is multiplexed, AD converted in a 4 bit

  9. Canadian high speed magnetically levitated vehicle system

    Energy Technology Data Exchange (ETDEWEB)

    Atherton, D L [Queen' s Univ., Kingston, Ont.; Belanger, P R; Burke, P E; Dawson, G E; Eastham, A R; Hayes, W F; Ooi, B T; Silvester, P; Slemon, G R

    1978-04-01

    A technically feasible high speed (400 to 480 km/h) guided ground transportation system, based on the use of the vehicle-borne superconducting magnets for electrodynamic suspension and guidance and for linear synchronous motor propulsion was defined as a future modal option for Canadian application. Analysis and design proposals were validated by large-scale tests on a rotating wheel facility and by modelling system components and their interactions. Thirty ton vehicles carrying 100 passengers operate over a flat-topped elevated guideway, which minimizes system down-time due to ice and snow accumulation and facilitates the design of turn-outs. A clearance of up to 15 cm is produced by the electrodynamic interaction between the vehicle-borne superconducting magnets and aluminum guideway strips. Propulsion and automatic system control is provided by the superconducting linear synchronous motor which operates at good efficiency (0.74) and high power factor (0.95). The vehicle is guided primarily by the interaction between the LSM field magnet array and flat null-flux loops overlying the stator windings in the guideway. The linear synchronous motor, electrodynamic suspension as well as levitation strip joints, parasitic LSM winding losses and limitations to the use of ferromagnetic guideway reinforcement were investigated experimentally on the test wheel facility. The use of a secondary suspension assures adequate dynamic stability, and good ride quality is achieved by optimized passive components with respect to lateral modes and by an actively controlled secondary suspension with respect to vertical motion.

  10. Material constraints on high-speed design

    Science.gov (United States)

    Bucur, Diana; Militaru, Nicolae

    2015-02-01

    Current high-speed circuit designs with signal rates up to 100Gbps and above are implying constraints for dielectric and conductive materials and their dependence of frequency, for component elements and for production processes. The purpose of this paper is to highlight through various simulation results the frequency dependence of specific parameters like insertion and return loss, eye diagrams, group delay that are part of signal integrity analyses type. In low-power environment designs become more complex as the operation frequency increases. The need for new materials with spatial uniformity for dielectric constant is a need for higher data rates circuits. The fiber weave effect (FWE) will be analyzed through the eye diagram results for various dielectric materials in a differential signaling scheme given the fact that the FWE is a phenomenon that affects randomly the performance of the circuit on balanced/differential transmission lines which are typically characterized through the above mentioned approaches. Crosstalk between traces is also of concern due to propagated signals that have tight rise and fall times or due to high density of the boards. Criteria should be considered to achieve maximum performance of the designed system requiring critical electronic properties.

  11. Simulations of High Speed Fragment Trajectories

    Science.gov (United States)

    Yeh, Peter; Attaway, Stephen; Arunajatesan, Srinivasan; Fisher, Travis

    2017-11-01

    Flying shrapnel from an explosion are capable of traveling at supersonic speeds and distances much farther than expected due to aerodynamic interactions. Predicting the trajectories and stable tumbling modes of arbitrary shaped fragments is a fundamental problem applicable to range safety calculations, damage assessment, and military technology. Traditional approaches rely on characterizing fragment flight using a single drag coefficient, which may be inaccurate for fragments with large aspect ratios. In our work we develop a procedure to simulate trajectories of arbitrary shaped fragments with higher fidelity using high performance computing. We employ a two-step approach in which the force and moment coefficients are first computed as a function of orientation using compressible computational fluid dynamics. The force and moment data are then input into a six-degree-of-freedom rigid body dynamics solver to integrate trajectories in time. Results of these high fidelity simulations allow us to further understand the flight dynamics and tumbling modes of a single fragment. Furthermore, we use these results to determine the validity and uncertainty of inexpensive methods such as the single drag coefficient model.

  12. High speed all-silicon optical modulator

    International Nuclear Information System (INIS)

    Marris-Morini, Delphine; Le Roux, Xavier; Pascal, Daniel; Vivien, Laurent; Cassan, Eric; Fedeli, Jean Marc; Damlencourt, Jean Francois; Bouville, David; Palomo, Jose; Laval, Suzanne

    2006-01-01

    Electrorefractive effect is experimentally demonstrated in an all-silicon optical structure. A highly doped Si P + layer is embedded in the intrinsic region of a PIN diode integrated in a SOI waveguide. Holes are confined at equilibrium around the P + layer. By applying a reverse bias to the diode, electrical field sweeps the carriers out of the active region. Free carrier concentration variations are responsible for local refractive index variations leading to an effective index variation of the waveguide optical mode and to an optical absorption variation. As a figure of merit, the product V π L π , determined from the measured effective index variation, is equal to 3.1 V cm. Furthermore, the device performances have theoretically been investigated. Estimations show that V π L π as small as 1 V cm are feasible using optimized structures. Response times lower than 2 ps are predicted, which gives the possibility to achieve very high-speed modulation. Furthermore, a temperature increases from 300 to 400 K does not change the index variation amplitude, and despite the carrier mobility reduction, response times are still lower than 2 ps

  13. Full Dynamic Ball Bearing Model with Elastic Outer Ring for High Speed Applications

    Directory of Open Access Journals (Sweden)

    Christian Wagner

    2017-06-01

    Full Text Available Ball bearings are commonly used in high speed turbomachinery and have a critical influence on the rotordynamic behavior. Therefore, a simulation model of the bearing to predict the dynamic influence is essential. The presented model is a further step to develop an accurate and efficient characterization of the ball bearing’s rotor dynamic parameters such as stiffness and deflections as well as vibrational excitations induced by the discrete rolling elements. To make it applicable to high speed turbomachinery, the model considers centrifugal forces, gyroscopic effects and ball spinning. The consideration of an elastic outer ring makes the bearing model suitable for integrated lightweight bearing constructions used in modern aircraft turbines. In order to include transient rotordynamic behavior, the model is built as a full dynamic multibody simulation with time integration. To investigate the influence of the elasticity of the outer ring, a comparison with a rigid formulation for several rotational speeds and loads is presented.

  14. Turbulence influence on optimum tip speed ratio for a 200 kW vertical axis wind turbine

    Science.gov (United States)

    Möllerström, E.; Eriksson, S.; Goude, A.; Ottermo, F.; Hylander, J.

    2016-09-01

    The influence of turbulence intensity (TI) on the tip speed ratio for maximum power coefficient, here called λCp_max, is studied for a 200 kW VAWT H-rotor using logged data from a 14 month period with the H-rotor operating in wind speeds up to 9 m/s. The TI - λCp_max relation is examined by dividing 10 min mean values in different turbulence intensity ranges and producing multiple CP(λ) curves. A clear positive relation between TI and λCp_max is shown and is further strengthened as possible secondary effects are examined and deemed non-essential. The established relation makes it possible to tune the control strategy to enhance the total efficiency of the turbine.

  15. Francis-99: Transient CFD simulation of load changes and turbine shutdown in a model sized high-head Francis turbine

    International Nuclear Information System (INIS)

    Mössinger, Peter; Jester-Zürker, Roland; Jung, Alexander

    2017-01-01

    With increasing requirements for hydropower plant operation due to intermittent renewable energy sources like wind and solar, numerical simulations of transient operations in hydraulic turbo machines become more important. As a continuation of the work performed for the first workshop which covered three steady operating conditions, in the present paper load changes and a shutdown procedure are investigated. The findings of previous studies are used to create a 360° model and compare measurements with simulation results for the operating points part load, high load and best efficiency. A mesh motion procedure is introduced, allowing to represent moving guide vanes for load changes from best efficiency to part load and high load. Additionally an automated re-mesh procedure is added for turbine shutdown to ensure reliable mesh quality during guide vane closing. All three transient operations are compared to PIV velocity measurements in the draft tube and pressure signals in the vaneless space. Simulation results of axial velocity distributions for all three steady operation points, during both load changes and for the shutdown correlated well with the measurement. An offset at vaneless space pressure is found to be a result of guide vane corrections for the simulation to ensure similar velocity fields. Short-time Fourier transformation indicating increasing amplitudes and frequencies at speed-no load conditions. Further studies will discuss the already measured start-up procedure and investigate the necessity to consider the hydraulic system dynamics upstream of the turbine by means of a 1D3D coupling between the 3D flow field and a 1D system model. (paper)

  16. Francis-99: Transient CFD simulation of load changes and turbine shutdown in a model sized high-head Francis turbine

    Science.gov (United States)

    Mössinger, Peter; Jester-Zürker, Roland; Jung, Alexander

    2017-01-01

    With increasing requirements for hydropower plant operation due to intermittent renewable energy sources like wind and solar, numerical simulations of transient operations in hydraulic turbo machines become more important. As a continuation of the work performed for the first workshop which covered three steady operating conditions, in the present paper load changes and a shutdown procedure are investigated. The findings of previous studies are used to create a 360° model and compare measurements with simulation results for the operating points part load, high load and best efficiency. A mesh motion procedure is introduced, allowing to represent moving guide vanes for load changes from best efficiency to part load and high load. Additionally an automated re-mesh procedure is added for turbine shutdown to ensure reliable mesh quality during guide vane closing. All three transient operations are compared to PIV velocity measurements in the draft tube and pressure signals in the vaneless space. Simulation results of axial velocity distributions for all three steady operation points, during both load changes and for the shutdown correlated well with the measurement. An offset at vaneless space pressure is found to be a result of guide vane corrections for the simulation to ensure similar velocity fields. Short-time Fourier transformation indicating increasing amplitudes and frequencies at speed-no load conditions. Further studies will discuss the already measured start-up procedure and investigate the necessity to consider the hydraulic system dynamics upstream of the turbine by means of a 1D3D coupling between the 3D flow field and a 1D system model.

  17. A compact, high efficiency contra-rotating generator suitable for wind turbines in the urban environment

    Energy Technology Data Exchange (ETDEWEB)

    Booker, J.D. [Department of Mechanical Engineering, University of Bristol, University Walk, Bristol BS8 1TR (United Kingdom); Mellor, P.H.; Wrobel, R.; Drury, D. [Department of Electrical and Electronic Engineering, University of Bristol, Bristol (United Kingdom)

    2010-09-15

    This paper is concerned with the design, development and performance testing of a permanent magnet (PM) generator for wind turbine applications in urban areas. The radially interacting armature windings and magnet array are carried on direct drive, contra-rotating rotors, resulting in a high torque density and efficiency. This topology also provides improved physical and mechanical characteristics such as compactness, low starting torque, elimination of gearboxes, low maintenance, low noise and vibration, and the potential for modular construction. The design brief required a 50 kW continuous rated prototype generator, with a relative speed at the air-gap of 500 rpm. A test rig has been instrumented to give measurements of the mechanical input (torque and speed) and electrical output (voltage, current and power) of the generator, as well as temperature readings from inside the generator using a wireless telemetry device. Peak power output was found to be 48 kW at a contra-rotating speed of 500 rpm, close to the design target, with an efficiency of 94%. It is anticipated that the generator will find application in a wide range of wind turbine designs suited to the urban environment, e.g. types sited on the top of buildings, as there is growing interest in providing quiet, low cost, clean electricity at point of use. (author)

  18. High-Speed Data Recorder for Space, Geodesy, and Other High-Speed Recording Applications

    Science.gov (United States)

    Taveniku, Mikael

    2013-01-01

    A high-speed data recorder and replay equipment has been developed for reliable high-data-rate recording to disk media. It solves problems with slow or faulty disks, multiple disk insertions, high-altitude operation, reliable performance using COTS hardware, and long-term maintenance and upgrade path challenges. The current generation data recor - ders used within the VLBI community are aging, special-purpose machines that are both slow (do not meet today's requirements) and are very expensive to maintain and operate. Furthermore, they are not easily upgraded to take advantage of commercial technology development, and are not scalable to multiple 10s of Gbit/s data rates required by new applications. The innovation provides a softwaredefined, high-speed data recorder that is scalable with technology advances in the commercial space. It maximally utilizes current technologies without being locked to a particular hardware platform. The innovation also provides a cost-effective way of streaming large amounts of data from sensors to disk, enabling many applications to store raw sensor data and perform post and signal processing offline. This recording system will be applicable to many applications needing realworld, high-speed data collection, including electronic warfare, softwaredefined radar, signal history storage of multispectral sensors, development of autonomous vehicles, and more.

  19. Towards accurate performance prediction of a vertical axis wind turbine operating at different tip speed ratios

    NARCIS (Netherlands)

    Rezaeiha, A.; Kalkman, I.; Blocken, B.J.E.

    2017-01-01

    Accurate prediction of the performance of a vertical-axis wind turbine (VAWT) using CFD simulation requires the employment of a sufficiently fine azimuthal increment (dθ) combined with a mesh size at which essential flow characteristics can be accurately resolved. Furthermore, the domain size needs

  20. Fault Diagnosis and Fault Tolerant Control with Application on a Wind Turbine Low Speed Shaft Encoder

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Sardi, Hector Eloy Sanchez; Escobet, Teressa

    2015-01-01

    tolerant control of wind turbines using a benchmark model. In this paper, the fault diagnosis scheme is improved and integrated with a fault accommodation scheme which enables and disables the individual pitch algorithm based on the fault detection. In this way, the blade and tower loads are not increased...

  1. High-Speed Interferometry Under Impacting Drops

    KAUST Repository

    Langley, Kenneth R.; Li, Erqiang; Thoroddsen, Sigurdur T

    2017-01-01

    Over the last decade the rapid advances in high-speed video technology, have opened up to study many multi-phase fluid phenomena, which tend to occur most rapidly on the smallest length-scales. One of these is the entrapment of a small bubble under a drop impacting onto a solid surface. Here we have gone from simply observing the presence of the bubble to detailed imaging of the formation of a lubricating air-disc under the drop center and its subsequent contraction into the bubble. Imaging the full shape-evolution of the air-disc has required μm and sub-μs space and time resolutions. Time-resolved 200 ns interferometry with monochromatic light, has allowed us to follow individual fringes to obtain absolute air-layer thicknesses, based on the eventual contact with the solid. We can follow the evolution of the dimple shape as well as the compression of the gas. The improved imaging has also revealed new levels of detail, like the nature of the first contact which produces a ring of micro-bubbles, highlighting the influence of nanometric surface roughness. Finally, for impacts of ultra-viscous drops we see gliding on ~100 nm thick rarified gas layers, followed by extreme wetting at numerous random spots.

  2. High-Speed Interferometry Under Impacting Drops

    KAUST Repository

    Langley, Kenneth R.

    2017-08-31

    Over the last decade the rapid advances in high-speed video technology, have opened up to study many multi-phase fluid phenomena, which tend to occur most rapidly on the smallest length-scales. One of these is the entrapment of a small bubble under a drop impacting onto a solid surface. Here we have gone from simply observing the presence of the bubble to detailed imaging of the formation of a lubricating air-disc under the drop center and its subsequent contraction into the bubble. Imaging the full shape-evolution of the air-disc has required μm and sub-μs space and time resolutions. Time-resolved 200 ns interferometry with monochromatic light, has allowed us to follow individual fringes to obtain absolute air-layer thicknesses, based on the eventual contact with the solid. We can follow the evolution of the dimple shape as well as the compression of the gas. The improved imaging has also revealed new levels of detail, like the nature of the first contact which produces a ring of micro-bubbles, highlighting the influence of nanometric surface roughness. Finally, for impacts of ultra-viscous drops we see gliding on ~100 nm thick rarified gas layers, followed by extreme wetting at numerous random spots.

  3. The high speed civil transport and NASA's High Speed Research (HSR) program

    Science.gov (United States)

    Shaw, Robert J.

    1994-01-01

    Ongoing studies being conducted not only in this country but in Europe and Asia suggest that a second generation supersonic transport, or High-Speed Civil Transport (HSCT), could become an important part of the 21st century international air transportation system. However, major environmental compatibility and economic viability issues must be resolved if the HSCT is to become a reality. This talk will overview the NASA High-Speed Research (HSR) program which is aimed at providing the U.S. industry with a technology base to allow them to consider launching an HSCT program early in the next century. The talk will also discuss some of the comparable activities going on within Europe and Japan.

  4. High Specific Stiffness Shafts and Advanced Bearing Coatings for Gas Turbine Engines Final Report CRADA No. TC-1089-95

    Energy Technology Data Exchange (ETDEWEB)

    Barbee, Troy [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chin, Herbert [United Technologies Corporation, East Hartford, CT (United States)

    2017-11-09

    At the time of the CRADA, the largest in-service gas-turbine aircraft engines strove for increased thrust and power density to meet the requirements for take-off thrust, given the increase in take-off gross weight (TOGW) associated with longer range transport requirements. The trend in modem turbo shaft engines was toward turbine shafts with higher and higher length-to-diameter ratios, which reduced the shaft critical speed. Using co nventional shaft materials, this lead to shafts that needed to operate near or above sensitive shaft bending critical speeds, therefore requiring multiple bearings and/ or multiple squeeze-film dampers to control the dynamic response. Using new materials and d esign concepts this project demonstrated the use of new shaft materials which could provide increased shaft speed range above existing maximum engine speeds without encountering a critic al speed event and high vector deflections. This increased main shaft speed also resulted in decreased bearing life associated with lower heat dissipation and higher centrifugal forces. Thus, a limited effort was devoted to feasibility of higher performance bearing coatings to mitigate the speed effects.

  5. Wind Turbine Diagnosis under Variable Speed Conditions Using a Single Sensor Based on the Synchrosqueezing Transform Method.

    Science.gov (United States)

    Guo, Yanjie; Chen, Xuefeng; Wang, Shibin; Sun, Ruobin; Zhao, Zhibin

    2017-05-18

    The gearbox is one of the key components in wind turbines. Gearbox fault signals are usually nonstationary and highly contaminated with noise. The presence of amplitude-modulated and frequency-modulated (AM-FM) characteristics compound the difficulty of precise fault diagnosis of wind turbines, therefore, it is crucial to develop an effective fault diagnosis method for such equipment. This paper presents an improved diagnosis method for wind turbines via the combination of synchrosqueezing transform and local mean decomposition. Compared to the conventional time-frequency analysis techniques, the improved method which is performed in non-real-time can effectively reduce the noise pollution of the signals and preserve the signal characteristics, and hence is suitable for the analysis of nonstationary signals with high noise. This method is further validated by simulated signals and practical vibration data measured from a 1.5 MW wind turbine. The results confirm that the proposed method can simultaneously control the noise and increase the accuracy of time-frequency representation.

  6. High Speed Dynamics in Brittle Materials

    Science.gov (United States)

    Hiermaier, Stefan

    2015-06-01

    Brittle Materials under High Speed and Shock loading provide a continuous challenge in experimental physics, analysis and numerical modelling, and consequently for engineering design. The dependence of damage and fracture processes on material-inherent length and time scales, the influence of defects, rate-dependent material properties and inertia effects on different scales make their understanding a true multi-scale problem. In addition, it is not uncommon that materials show a transition from ductile to brittle behavior when the loading rate is increased. A particular case is spallation, a brittle tensile failure induced by the interaction of stress waves leading to a sudden change from compressive to tensile loading states that can be invoked in various materials. This contribution highlights typical phenomena occurring when brittle materials are exposed to high loading rates in applications such as blast and impact on protective structures, or meteorite impact on geological materials. A short review on experimental methods that are used for dynamic characterization of brittle materials will be given. A close interaction of experimental analysis and numerical simulation has turned out to be very helpful in analyzing experimental results. For this purpose, adequate numerical methods are required. Cohesive zone models are one possible method for the analysis of brittle failure as long as some degree of tension is present. Their recent successful application for meso-mechanical simulations of concrete in Hopkinson-type spallation tests provides new insight into the dynamic failure process. Failure under compressive loading is a particular challenge for numerical simulations as it involves crushing of material which in turn influences stress states in other parts of a structure. On a continuum scale, it can be modeled using more or less complex plasticity models combined with failure surfaces, as will be demonstrated for ceramics. Models which take microstructural

  7. 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...

  8. Reliability Estimation with Uncertainties Consideration for High Power IGBTs in 2.3 MW Wind Turbine Converter System

    DEFF Research Database (Denmark)

    Kostandyan, Erik; Ma, Ke

    2012-01-01

    This paper investigates the lifetime of high power IGBTs (insulated gate bipolar transistors) used in large wind turbine applications. Since the IGBTs are critical components in a wind turbine power converter, it is of great importance to assess their reliability in the design phase of the turbine....... Minimum, maximum and average junction temperatures profiles for the grid side IGBTs are estimated at each wind speed input values. The selected failure mechanism is the crack propagation in solder joint under the silicon die. Based on junction temperature profiles and physics of failure model......, the probabilistic and determinist damage models are presented with estimated fatigue lives. Reliably levels were assessed by means of First Order Reliability Method taking into account uncertainties....

  9. Study on gas turbines. Leading role of high efficiency power generation; Gas turbine kenkyu. Kokoritsu hatsuden no shuyaku wo nerau

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-01-31

    This review summarizes research works of Central Research Institute of Electric Power Industry on gas turbines playing a leading role of high efficiency power generation. This article describes historical changes of gas turbine technology, changes and current status from the viewpoint of electric power industry, and development trend in various makers. Increase in the flow-in gas temperature, low NOx combustion technology, use of various fuels, and durability evaluation and improvement technology for high temperature parts are described as technological problems and development trends. The increase in temperature is indispensable for the improvement of efficiency. Materials having heat resistance, anticorrosion and strength are required. Accordingly, Ni-based single crystal super alloy has been developed. Developments of ceramic gas turbine and catalytic combustor are also described. The coal gasification combined power generation is expected as a new power generation technology having availability of various coals, high efficiency, and excellent environmental protection. Development of 1500 {degree}C class combustor for turbines has been promoted. Evaluation and improvement of durability of high temperature parts are also described. For the new utilization technology of gas turbines, repowering and compressed air storage gas turbine power generation technology are introduced. 92 figs., 14 tabs.

  10. High Speed impedance tomography for cardiac imaging

    International Nuclear Information System (INIS)

    Tehrani, J.N.; Jin, C.; Schaik, Andre

    2010-01-01

    Full text: Electrical Impedance Tomography (EIT) calculates the internal conductivity distribution within a body using electrical contact measurements. Previous investigation has shown that optimizing electrode placement can give better information about the stroke volume and better separation between the ventricles and atria than with the electrodes attached in the transverse plane. In our investigation we are developing fast three dimensional imaging of the heart (two planes of 16 electrodes) including internal electrodes in esophagus. The reconstruction speed in EIT is one of the main limitations for real time imaging when using a detailed three dimensional finite element mesh. For that reason we investigated new iterative algorithms for solving large scale LJ regularization. In this research we compare these algorithms on noise reliability and speed for 2D cardiac models. The four methods were as follows: (I) an interior point method for solving Ll-regularized least squares problems (Ll-LS); (2) total variation using a Lagrangian multiplier (TV AL3); (3) a two step iterative shrinkage/thresholding method (TWIST) for solving the Lo-regularized least squares problem; (4) The Least Absolute Shrinkage and Selection Operator (LASSO). In our investigation, using 1600 elements, we found all four algorithms provided an improvement over the best conventional EIT reconstruction method, Total Variation, in three important areas: robustness to noise, increased computational speed of at least 40 x and a visually apparent improvement in spatial resolution. Out of the four algorithms we found TWIST was the fastest with at least a 1 00 x speed increase. (author)

  11. Concept for high speed computer printer

    Science.gov (United States)

    Stephens, J. W.

    1970-01-01

    Printer uses Kerr cell as light shutter for controlling the print on photosensitive paper. Applied to output data transfer, the information transfer rate of graphic computer printers could be increased to speeds approaching the data transfer rate of computer central processors /5000 to 10,000 lines per minute/.

  12. 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)

  13. Chicago-St. Louis high speed rail plan

    International Nuclear Information System (INIS)

    Stead, M.E.

    1994-01-01

    The Illinois Department of Transportation (IDOT), in cooperation with Amtrak, undertook the Chicago-St. Louis High Speed Rail Financial and Implementation Plan study in order to develop a realistic and achievable blueprint for implementation of high speed rail in the Chicago-St. Louis corridor. This report presents a summary of the Price Waterhouse Project Team's analysis and the Financial and Implementation Plan for implementing high speed rail service in the Chicago-St. Louis corridor

  14. 33 CFR 84.24 - High-speed craft.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false High-speed craft. 84.24 Section... RULES ANNEX I: POSITIONING AND TECHNICAL DETAILS OF LIGHTS AND SHAPES § 84.24 High-speed craft. (a) The masthead light of high-speed craft with a length to breadth ratio of less than 3.0 may be placed at a...

  15. A Historical Review of High Speed Metal Forming

    OpenAIRE

    Zittel, G.

    2010-01-01

    This paper will present a Historical Review of High Speed Metal Forming beginning with the first thought of forming metal by using an electromagnetic impulse to today, whereby High Speed Metal Forming is an accepted production process. Although this paper will briefly cover the basic physics of the process, it will not dwell on it. It will rather show how the industrial acceptance of High Speed Metal Forming is tightly connected to the knowledge acquired from many applications studies. These ...

  16. Chicago-St. Louis high speed rail plan

    Energy Technology Data Exchange (ETDEWEB)

    Stead, M.E.

    1994-12-31

    The Illinois Department of Transportation (IDOT), in cooperation with Amtrak, undertook the Chicago-St. Louis High Speed Rail Financial and Implementation Plan study in order to develop a realistic and achievable blueprint for implementation of high speed rail in the Chicago-St. Louis corridor. This report presents a summary of the Price Waterhouse Project Team`s analysis and the Financial and Implementation Plan for implementing high speed rail service in the Chicago-St. Louis corridor.

  17. A High Efficiency PSOFC/ATS-Gas Turbine Power System

    Energy Technology Data Exchange (ETDEWEB)

    W.L. Lundberg; G.A. Israelson; M.D. Moeckel; S.E. Veyo; R.A. Holmes; P.R. Zafred; J.E. King; R.E. Kothmann

    2001-02-01

    A study is described in which the conceptual design of a hybrid power system integrating a pressurized Siemens Westinghouse solid oxide fuel cell generator and the Mercury{trademark} 50 gas turbine was developed. The Mercury{trademark} 50 was designed by Solar Turbines as part of the US. Department of Energy Advanced Turbine Systems program. The focus of the study was to develop the hybrid power system concept that principally would exhibit an attractively-low cost of electricity (COE). The inherently-high efficiency of the hybrid cycle contributes directly to achieving this objective, and by employing the efficient, power-intensive Mercury{trademark} 50, with its relatively-low installed cost, the higher-cost SOFC generator can be optimally sized such that the minimum-COE objective is achieved. The system cycle is described, major system components are specified, the system installed cost and COE are estimated, and the physical arrangement of the major system components is discussed. Estimates of system power output, efficiency, and emissions at the system design point are also presented. In addition, two bottoming cycle options are described, and estimates of their effects on overall-system performance, cost, and COE are provided.

  18. 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.

  19. High-Speed Shaft Bearing Loads Testing and Modeling in the NREL Gearbox Reliability Collaborative: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    McNiff, B.; Guo, Y.; Keller, J.; Sethuraman, L.

    2014-12-01

    Bearing failures in the high speed output stage of the gearbox are plaguing the wind turbine industry. Accordingly, the National Renewable Energy Laboratory (NREL) Gearbox Reliability Collaborative (GRC) has performed an experimental and theoretical investigation of loads within these bearings. The purpose of this paper is to describe the instrumentation, calibrations, data post-processing and initial results from this testing and modeling effort. Measured HSS torque, bending, and bearing loads are related to model predictions. Of additional interest is examining if the shaft measurements can be simply related to bearing load measurements, eliminating the need for invasive modifications of the bearing races for such instrumentation.

  20. Optimization of advanced liquid natural gas-fuelled machineries for a high-speed ferry

    DEFF Research Database (Denmark)

    Tveitaskog, Kari Anne; Haglind, Fredrik

    -based optimization routine are used. The top cycle is modeled as the aero-derivative gas turbine LM2500, while the following five options for bottoming cycles are modeled: ∙ Single pressure steam cycle ∙ Dual-pressure steam cycle ∙ ORC using Toluene as the working fluid with an intermediate oil loop ∙ ABC with inter......This report is aimed at designing and optimizing combined cycles in order to define the most suitable machinery system for the future high-speed Incat ferry operated by Mols-Linien. For this purpose, an in-house numerical simulation tool called DNA (Dynamic Network Analysis) and a genetic algorithm...

  1. Time optimal paths for high speed maneuvering

    Energy Technology Data Exchange (ETDEWEB)

    Reister, D.B.; Lenhart, S.M.

    1993-01-01

    Recent theoretical results have completely solved the problem of determining the minimum length path for a vehicle with a minimum turning radius moving from an initial configuration to a final configuration. Time optimal paths for a constant speed vehicle are a subset of the minimum length paths. This paper uses the Pontryagin maximum principle to find time optimal paths for a constant speed vehicle. The time optimal paths consist of sequences of axes of circles and straight lines. The maximum principle introduces concepts (dual variables, bang-bang solutions, singular solutions, and transversality conditions) that provide important insight into the nature of the time optimal paths. We explore the properties of the optimal paths and present some experimental results for a mobile robot following an optimal path.

  2. Application of polarization in high speed, high contrast inspection

    Science.gov (United States)

    Novak, Matthew J.

    2017-08-01

    Industrial optical inspection often requires high speed and high throughput of materials. Engineers use a variety of techniques to handle these inspection needs. Some examples include line scan cameras, high speed multi-spectral and laser-based systems. High-volume manufacturing presents different challenges for inspection engineers. For example, manufacturers produce some components in quantities of millions per month, per week or even per day. Quality control of so many parts requires creativity to achieve the measurement needs. At times, traditional vision systems lack the contrast to provide the data required. In this paper, we show how dynamic polarization imaging captures high contrast images. These images are useful for engineers to perform inspection tasks in some cases where optical contrast is low. We will cover basic theory of polarization. We show how to exploit polarization as a contrast enhancement technique. We also show results of modeling for a polarization inspection application. Specifically, we explore polarization techniques for inspection of adhesives on glass.

  3. Variable Speed (DFIG) Wind Turbines: Rapid Frequency Response to Power System Disturbances

    DEFF Research Database (Denmark)

    Chandrashekhara, Divya K; Hansen, Anca Daniela; Sørensen, Poul Ejnar

    2009-01-01

    This paper examines the effect of integrating large number of wind turbines particularly the double fed induction generator (DFIG) on the virtual inertia of the Danish power system network. The virtual inertia refers to the kinetic energy stored in the rotating masses which can be released...... initially to counter act the frequency change during a power system disturbance. Simulation studies have been carried out on a generic reduced model of a transmission power grid of the Danish TSO Energinet.dk to assess the impact of loss of generation on system frequency. Further, simulation study has been...

  4. Fault ride-through enhancement of fixed speed wind turbine using bridge-type fault current limiter

    Directory of Open Access Journals (Sweden)

    Mostafa I. Marei

    2016-05-01

    Full Text Available The interaction between wind energy turbines and the grid results in two main problems, increasing the short-circuit level and reducing the Fault Ride-Through (FRT capability during faults. The objective of this paper is to solve these problems, for fixed speed Wind Energy Systems (WECS, utilizing the bridge-type Fault Current Limiter (FCL with a discharging resistor. A simple cascaded control system is proposed for the FCL to regulate the terminal voltage of the generator and limit the current. The system is simulated on PSCAD/EMTDC software to evaluate the dynamic performance of the proposed WECS compensated by FCL. The simulation results show the potentials of the FCL as a simple and effective method for solving grid interconnection problems of WECS.

  5. Application of high-speed photography to hydrodynamic instability research

    International Nuclear Information System (INIS)

    Chang Lihua; Li Zuoyou; Xiao Zhengfei; Zou Liyong; Liu Jinhong; Xiong Xueshi

    2012-01-01

    High-speed photography is used to study the Rayleigh-Taylor instability of air-water interface driven by high- pressure exploding gas. Clear images illustrating the instability are obtained, along with the air bubble peak speed and turbulent mixing speed. The RM (Richtmyer-Meshkov) instability of air/SF 6 interface driven by shock wave is also researched by using high-speed Schlieren technique on the horizontal shock tube and primary experimental results are obtained, which show the change of the turbulent mixing region clearly. (authors)

  6. High-speed ground transportation development outside United States

    Energy Technology Data Exchange (ETDEWEB)

    Eastham, T.R. [Queen`s Univ., Kingston, Ontario (United Kingdom)

    1995-09-01

    This paper surveys the state of high-speed (in excess of 200 km/h) ground-transportation developments outside the United States. Both high-speed rail and Maglev systems are covered. Many vehicle systems capable of providing intercity service in the speed range 200--500 km/h are or will soon be available. The current state of various technologies, their implementation, and the near-term plans of countries that are most active in high-speed ground transportation development are reported.

  7. Induced Unbalance as a Method for Improving the Dynamic Stability of High-Speed Turbochargers

    KAUST Repository

    Gordon Kirk, R.; Alsaeed, Ali A.

    2011-01-01

    The high-speed diesel engine turbocharger is known to have subsynchronous vibrations for a wide speed range. The bearing fluid-film instability is the main source of the vibration. The nonlinear forces inside the bearings are causing the rotor to whirl in a limit cycle. This study presents a new method for improving the dynamic stability by inducing the turbocharger rotor unbalance in order to suppress the subsynchronous vibration. The finite-element model of the turbocharger with floating-ring bearings is numerically solved for the nonlinear time-transient response. Both compressor and turbine added unbalance are induced and the dynamic stability is computed. The turbocharger model with linearized floating-ring bearings is also solved for eigenvalues to predict the modes of instability. The linear analysis demonstrates that the forward whirling mode of the floating-ring at the compressor end also becomes unstable at the higher turbocharger speeds, in addition to the unstable forward conical and cylindrical modes. The numerical predictions are also compared to the former experimental results of a similar turbocharger. The results of the study show that the subsynchronous frequency amplitude of the dominant first mode is reduced when inducing either the compressor or the turbine unbalance at a certain level. © 2011 R. Gordon Kirk and Ali A. Alsaeed.

  8. 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.

  9. Electrical insulation characteristics of liquid helium under high speed rotating field

    International Nuclear Information System (INIS)

    Ishii, I.; Fuchino, S.; Okano, M.; Tamada, N.

    1996-01-01

    Electrical breakdown behavior of liquid helium was investigated under high speed rotating field. In the development of superconducting turbine generator it is essential to get the knowledge of electrical insulation characteristics of liquid helium under high speed rotating field. When the current of the field magnet of a superconducting generator is changed, changing magnetic field generates heat in the conductor and it causes bubbles in the liquid helium around the conductor. The behavior of the bubbles is affected largely by the buoyancy which is generated by the centrifugal force. Electrical breakdown behavior of the liquid helium is strongly dependent on the gas bubbles in the liquid. Electrical breakdown voltage between electrodes was measured in a rotating cryostat with and without heater input for bubble formation. Decrease of the breakdown voltage by the heater power was smaller in the rotating field than that in the non rotating field

  10. Reliability of Wind Speed Data from Satellite Altimeter to Support Wind Turbine Energy

    Science.gov (United States)

    Uti, M. N.; Din, A. H. M.; Omar, A. H.

    2017-10-01

    Satellite altimeter has proven itself to be one of the important tool to provide good quality information in oceanographic study. Nowadays, most countries in the world have begun in implementation the wind energy as one of their renewable energy for electric power generation. Many wind speed studies conducted in Malaysia using conventional method and scientific technique such as anemometer and volunteer observing ships (VOS) in order to obtain the wind speed data to support the development of renewable energy. However, there are some limitations regarding to this conventional method such as less coverage for both spatial and temporal and less continuity in data sharing by VOS members. Thus, the aim of this research is to determine the reliability of wind speed data by using multi-mission satellite altimeter to support wind energy potential in Malaysia seas. Therefore, the wind speed data are derived from nine types of satellite altimeter starting from year 1993 until 2016. Then, to validate the reliability of wind speed data from satellite altimeter, a comparison of wind speed data form ground-truth buoy that located at Sabah and Sarawak is conducted. The validation is carried out in terms of the correlation, the root mean square error (RMSE) calculation and satellite track analysis. As a result, both techniques showing a good correlation with value positive 0.7976 and 0.6148 for point located at Sabah and Sarawak Sea, respectively. It can be concluded that a step towards the reliability of wind speed data by using multi-mission satellite altimeter can be achieved to support renewable energy.

  11. High capacity, high speed histogramming data acquisition memory

    International Nuclear Information System (INIS)

    Epstein, A.; Boulin, C.

    1996-01-01

    A double width CAMAC DRAM store module was developed for use as a histogramming memory in fast time-resolved synchrotron radiation applications to molecular biology. High speed direct memory modify (3 MHz) is accomplished by using a discrete DRAM controller and fast page mode access. The module can be configured using standard SIMMs to sizes of up to 64M-words. The word width is 16 bit and the module can handle overflows by storing the overflow addresses in a dedicated FIFO. Simultaneous front panel DMM/DMI access and CAMAC readout of the overflow addresses is supported

  12. High speed all-optical networks

    Science.gov (United States)

    Chlamtac, Imrich

    1993-01-01

    An inherent problem of conventional point-to-point WAN architectures is that they cannot translate optical transmission bandwidth into comparable user available throughput due to the limiting electronic processing speed of the switching nodes. This report presents the first solution to WDM based WAN networks that overcomes this limitation. The proposed Lightnet architecture takes into account the idiosyncrasies of WDM switching/transmission leading to an efficient and pragmatic solution. The Lightnet architecture trades the ample WDM bandwidth for a reduction in the number of processing stages and a simplification of each switching stage, leading to drastically increased effective network throughputs.

  13. A high-speed interface for multi-channel analyzer

    International Nuclear Information System (INIS)

    Shen Ji; Zheng Zhong; Qiao Chong; Chen Ziyu; Ye Yunxiu; Ye Zhenyu

    2003-01-01

    This paper presents a high-speed computer interface for multi-channel analyzer based on DMA technique. Its essential principle and operating procedure are introduced. By the detecting of γ spectrum of 137 Cs with the interface, it's proved that the interface can meet the requirements of high-speed data acquisition

  14. Advancing high-speed rail policy in the United States.

    Science.gov (United States)

    2012-06-01

    This report builds on a review of international experience with high-speed rail projects to develop recommendations for a High-speed rail policy framework for the United States. The international review looked at the experience of Korea, Taiwan, Chin...

  15. 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.

  16. High-power condensation turbine application to district heating

    International Nuclear Information System (INIS)

    Virchenko, M.A.; Arkad'ev, B.A.; Ioffe, V.Yu.

    1982-01-01

    In general outline the role of condensation turbines in NPP district heating is considered. The expediency of expansion of central heating loading of turbines of operating as well as newly designed condensation power plants on the basis of the WWER-1000-type reactors is shown. The principle heat flowsheet of the 1000 MW power turbine is given. An advantage in using turbines with uncontrolled steam bleeding is pointed out [ru

  17. Niobium-Matrix-Composite High-Temperature Turbine Blades

    Science.gov (United States)

    Kaplan, Richard B.; Tuffias, Robert H.; La Ferla, Raffaele; Heng, Sangvavann; Harding, John T.

    1995-01-01

    High-temperture composite-material turbine blades comprising mainly niobium matrices reinforced with refractory-material fibers being developed. Of refractory fibrous materials investigated, FP-AL(2)0(3), tungsten, and polymer-based SiC fibers most promising. Blade of this type hollow and formed in nearly net shape by wrapping mesh of reinforcing refractory fibers around molybdenum mandrel, then using thermal-gradient chemical-vapor infiltration (CVI) to fill interstices with niobium. CVI process controllable and repeatable, and kinetics of both deposition and infiltration well understood.

  18. High speed micromachining with high power UV laser

    Science.gov (United States)

    Patel, Rajesh S.; Bovatsek, James M.

    2013-03-01

    Increasing demand for creating fine features with high accuracy in manufacturing of electronic mobile devices has fueled growth for lasers in manufacturing. High power, high repetition rate ultraviolet (UV) lasers provide an opportunity to implement a cost effective high quality, high throughput micromachining process in a 24/7 manufacturing environment. The energy available per pulse and the pulse repetition frequency (PRF) of diode pumped solid state (DPSS) nanosecond UV lasers have increased steadily over the years. Efficient use of the available energy from a laser is important to generate accurate fine features at a high speed with high quality. To achieve maximum material removal and minimal thermal damage for any laser micromachining application, use of the optimal process parameters including energy density or fluence (J/cm2), pulse width, and repetition rate is important. In this study we present a new high power, high PRF QuasarR 355-40 laser from Spectra-Physics with TimeShiftTM technology for unique software adjustable pulse width, pulse splitting, and pulse shaping capabilities. The benefits of these features for micromachining include improved throughput and quality. Specific example and results of silicon scribing are described to demonstrate the processing benefits of the Quasar's available power, PRF, and TimeShift technology.

  19. Effect of welding current and speed on occurrence of humping bead in high-speed GMAW

    Institute of Scientific and Technical Information of China (English)

    Chen Ji; Wu Chuansong

    2009-01-01

    The developed mathematical model of humping formation mechanism in high-speed gas metal arc welding (GMAW) is used to analyze the effects of welding current and welding speed on the occurrence of humping bead. It considers both the momentum and heat content of backward flowing molten jet inside weld pool. Three-dimensional geometry of weld pool, the spacing between two adjacent humps and hump height along humping weld bead are calculated under different levels of welding current and welding speed. It shows that wire feeding rate, power intensity and the moment of backward flowing molten jet are the major factors on humping bead formation.

  20. Compressibility, turbulence and high speed flow

    CERN Document Server

    Gatski, Thomas B

    2009-01-01

    This book introduces the reader to the field of compressible turbulence and compressible turbulent flows across a broad speed range through a unique complimentary treatment of both the theoretical foundations and the measurement and analysis tools currently used. For the computation of turbulent compressible flows, current methods of averaging and filtering are presented so that the reader is exposed to a consistent development of applicable equation sets for both the mean or resolved fields as well as the transport equations for the turbulent stress field. For the measurement of turbulent compressible flows, current techniques ranging from hot-wire anemometry to PIV are evaluated and limitations assessed. Characterizing dynamic features of free shear flows, including jets, mixing layers and wakes, and wall-bounded flows, including shock-turbulence and shock boundary-layer interactions, obtained from computations, experiments and simulations are discussed. Key features: * Describes prediction methodologies in...

  1. 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

  2. Thermomechanical simulations and experimental validation for high speed incremental forming

    Science.gov (United States)

    Ambrogio, Giuseppina; Gagliardi, Francesco; Filice, Luigino; Romero, Natalia

    2016-10-01

    Incremental sheet forming (ISF) consists in deforming only a small region of the workspace through a punch driven by a NC machine. The drawback of this process is its slowness. In this study, a high speed variant has been investigated from both numerical and experimental points of view. The aim has been the design of a FEM model able to perform the material behavior during the high speed process by defining a thermomechanical model. An experimental campaign has been performed by a CNC lathe with high speed to test process feasibility. The first results have shown how the material presents the same performance than in conventional speed ISF and, in some cases, better material behavior due to the temperature increment. An accurate numerical simulation has been performed to investigate the material behavior during the high speed process confirming substantially experimental evidence.

  3. Tuning of the PI Controller Parameters of a PMSG Wind Turbine to Improve Control Performance under Various Wind Speeds

    Directory of Open Access Journals (Sweden)

    Yun-Su Kim

    2015-02-01

    Full Text Available This paper presents a method to seek the PI controller parameters of a PMSG wind turbine to improve control performance. Since operating conditions vary with the wind speed, therefore the PI controller parameters should be determined as a function of the wind speed. Small-signal modeling of a PMSG WT is implemented to analyze the stability under various operating conditions and with eigenvalues obtained from the small-signal model of the PMSG WT, which are coordinated by adjusting the PI controller parameters. The parameters to be tuned are chosen by investigating participation factors of state variables, which simplifies the problem by reducing the number of parameters to be tuned. The process of adjusting these PI controller parameters is carried out using particle swarm optimization (PSO. To characterize the improvements in the control method due to the PSO method of tuning the PI controller parameters, the PMSG WT is modeled using the MATLAB/SimPowerSystems libraries with the obtained PI controller parameters.

  4. The use of high-speed imaging in education

    Science.gov (United States)

    Kleine, H.; McNamara, G.; Rayner, J.

    2017-02-01

    Recent improvements in camera technology and the associated improved access to high-speed camera equipment have made it possible to use high-speed imaging not only in a research environment but also specifically for educational purposes. This includes high-speed sequences that are created both with and for a target audience of students in high schools and universities. The primary goal is to engage students in scientific exploration by providing them with a tool that allows them to see and measure otherwise inaccessible phenomena. High-speed imaging has the potential to stimulate students' curiosity as the results are often surprising or may contradict initial assumptions. "Live" demonstrations in class or student- run experiments are highly suitable to have a profound influence on student learning. Another aspect is the production of high-speed images for demonstration purposes. While some of the approaches known from the application of high speed imaging in a research environment can simply be transferred, additional techniques must often be developed to make the results more easily accessible for the targeted audience. This paper describes a range of student-centered activities that can be undertaken which demonstrate how student engagement and learning can be enhanced through the use of high speed imaging using readily available technologies.

  5. Novel high speed fiber-optic pressure sensor systems.

    Science.gov (United States)

    2014-03-01

    The goal of this project is to develop a complete test of this technology for high-speed, high-accuracy applications, specifically cost-effective data acquisition techniques and practical mounting methods tailored for the subject environment. The sec...

  6. Modern trends in designing high-speed trains

    Directory of Open Access Journals (Sweden)

    Golubović Snežana D.

    2015-01-01

    Full Text Available Increased advantages of railway transportation systems over other types of transportation systems in the past sixty years have been a result of an intensive development of the new generations of high-speed trains. Not only do these types of trains comply with the need for increased speed of transportation and make the duration of the journey shorter, but they also meet the demands for increased reliability, safety and direct application of energy efficiency to the transportation system itself. Along with increased train speed, the motion resistance is increased as well, whereby at speeds over 200 km/h the proportion of air resistance becomes the most dominant member. One of the most efficient measures for reducing air resistance, as well as other negative consequences of high-speed motion, is the development of the aerodynamic shape of the train. This paper presents some construction solutions that affect the aerodynamic properties of high-speed trains, first and foremost, the nose shape, as well as the similarities and differences of individual subsystems necessary for the functioning of modern high-speed rail systems. We analysed two approaches to solving the problem of the aerodynamic shape of the train and the appropriate infrastructure using the examples of Japan and France. Two models of high-speed trains, Shinkansen (Japan and TGV, i.e. AGV (France, have been discussed.

  7. High-speed solar wind flow parameters at 1 AU

    International Nuclear Information System (INIS)

    Feldman, W.C.; Asbridge, J.R.; Bame, S.J.; Gosling, J.T.

    1976-01-01

    To develop a set of constraints for theories of solar wind high-speed streams, a detailed study was made of the fastest streams observed at 1 AU during the time period spanning March 1971 through July 1974. Streams were accepted for study only if (1) the maximum speed exceeded 650 km s -1 ; (2) effects of stream-stream dynamical interaction on the flow parameters could be safely separated from the intrinsic characteristics of the high-speed regions; (3) the full width at half maximum (FWHM) of the stream when mapped back to 20 solar radii by using a constant speed approximation was greater than 45degree in Carrington longitude; and (4) there were no obvious solar-activity-induced contaminating effects. Nineteen streams during this time interval satisfied these criteria. Average parameters at 1 AU for those portions of these streams above V=650 km s -1 are given.Not only is it not presently known why electrons are significantly cooler than the protons within high-speed regions, but also observed particle fluxes and convected energy fluxes for speed greater than 650 km s -1 are substantially larger than those values predicted by any of the existing theories of solar wind high-speed streams. More work is therefore needed in refining present solar wind models to see whether suitable modifications and/or combinations of existing theories based on reasonable coronal conditions can accommodate the above high-speed flow parameters

  8. Characterizing speed-independence of high-level designs

    DEFF Research Database (Denmark)

    Kishinevsky, Michael; Staunstrup, Jørgen

    1994-01-01

    This paper characterizes the speed-independence of high-level designs. The characterization is a condition on the design description ensuring that the behavior of the design is independent of the speeds of its components. The behavior of a circuit is modeled as a transition system, that allows data...... types, and internal as well as external non-determinism. This makes it possible to verify the speed-independence of a design without providing an explicit realization of the environment. The verification can be done mechanically. A number of experimental designs have been verified including a speed-independent...

  9. Research on Aerodynamic Noise Reduction for High-Speed Trains

    OpenAIRE

    Zhang, Yadong; Zhang, Jiye; Li, Tian; Zhang, Liang; Zhang, Weihua

    2016-01-01

    A broadband noise source model based on Lighthill’s acoustic theory was used to perform numerical simulations of the aerodynamic noise sources for a high-speed train. The near-field unsteady flow around a high-speed train was analysed based on a delayed detached-eddy simulation (DDES) using the finite volume method with high-order difference schemes. The far-field aerodynamic noise from a high-speed train was predicted using a computational fluid dynamics (CFD)/Ffowcs Williams-Hawkings (FW-H)...

  10. Review of High-Speed Fiber Optic Grating Sensors Systems

    Energy Technology Data Exchange (ETDEWEB)

    Udd, E; Benterou, J; May, C; Mihailov, S J; Lu, P

    2010-03-24

    Fiber grating sensors can be used to support a wide variety of high speed measurement applications. This includes measurements of vibrations on bridges, traffic monitoring on freeways, ultrasonic detection to support non-destructive tests on metal plates and providing details of detonation events. This paper provides a brief overview of some of the techniques that have been used to support high speed measurements using fiber grating sensors over frequency ranges from 10s of kHz, to MHZ and finally toward frequencies approaching the GHz regime. Very early in the development of fiber grating sensor systems it was realized that a high speed fiber grating sensor system could be realized by placing an optical filter that might be a fiber grating in front of a detector so that spectral changes in the reflection from a fiber grating were amplitude modulated. In principal the only limitation on this type of system involved the speed of the output detector which with the development of high speed communication links moved from the regime of 10s of MHz toward 10s of GHz. The earliest deployed systems involved civil structures including measurements of the strain fields on composite utility poles and missile bodies during break tests, bridges and freeways. This was followed by a series of developments that included high speed fiber grating sensors to support nondestructive testing via ultrasonic wave detection, high speed machining and monitoring ship hulls. Each of these applications involved monitoring mechanical motion of structures and thus interest was in speeds up to a few 10s of MHz. Most recently there has been interest in using fiber grating to monitor the very high speed events such as detonations and this has led to utilization of fiber gratings that are consumed during an event that may require detection speeds of hundreds of MHz and in the future multiple GHz.

  11. Active Boundary Layer Control on a Highly Loaded Turbine Exit Case Profile

    Directory of Open Access Journals (Sweden)

    Julia Kurz

    2018-03-01

    Full Text Available A highly loaded turbine exit guide vane with active boundary layer control was investigated experimentally in the High Speed Cascade Wind Tunnel at the University of the German Federal Armed Forces, Munich. The experiments include profile Mach number distributions, wake traverse measurements as well as boundary layer investigations with a flattened Pitot probe. Active boundary layer control by fluidic oscillators was applied to achieve improved performance in the low Reynolds number regime. Low solidity, which can be applied to reduce the number of blades, increases the risk of flow separation resulting in increased total pressure losses. Active boundary layer control is supposed to overcome these negative effects. The experiments show that active boundary layer control by fluidic oscillators is an appropriate way to suppress massive open separation bubbles in the low Reynolds number regime.

  12. High-speed LWR transients simulation for optimizing emergency response

    International Nuclear Information System (INIS)

    Wulff, W.; Cheng, H.S.; Lekach, S.V.; Mallen, A.N.; Stritar, A.

    1984-01-01

    The purpose of computer-assisted emergency response in nuclear power plants, and the requirements for achieving such a response, are presented. An important requirement is the attainment of realistic high-speed plant simulations at the reactor site. Currently pursued development programs for plant simulations are reviewed. Five modeling principles are established and a criterion is presented for selecting numerical procedures and efficient computer hardware to achieve high-speed simulations. A newly developed technology for high-speed power plant simulation is described and results are presented. It is shown that simulation speeds ten times greater than real-time process-speeds are possible, and that plant instrumentation can be made part of the computational loop in a small, on-site minicomputer. Additional technical issues are presented which must still be resolved before the newly developed technology can be implemented in a nuclear power plant

  13. Prediction and analysis of infra and low-frequency noise of upwind horizontal axis wind turbine using statistical wind speed model

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Gwang-Se; Cheong, Cheolung, E-mail: ccheong@pusan.ac.kr [School of Mechanical Engineering, Pusan National University, Busan, 609-745, Rep. of Korea (Korea, Republic of)

    2014-12-15

    Despite increasing concern about low-frequency noise of modern large horizontal-axis wind turbines (HAWTs), few studies have focused on its origin or its prediction methods. In this paper, infra- and low-frequency (the ILF) wind turbine noise are closely examined and an efficient method is developed for its prediction. Although most previous studies have assumed that the ILF noise consists primarily of blade passing frequency (BPF) noise components, these tonal noise components are seldom identified in the measured noise spectrum, except for the case of downwind wind turbines. In reality, since modern HAWTs are very large, during rotation, a single blade of the turbine experiences inflow with variation in wind speed in time as well as in space, breaking periodic perturbations of the BPF. Consequently, this transforms acoustic contributions at the BPF harmonics into broadband noise components. In this study, the ILF noise of wind turbines is predicted by combining Lowson’s acoustic analogy with the stochastic wind model, which is employed to reproduce realistic wind speed conditions. In order to predict the effects of these wind conditions on pressure variation on the blade surface, unsteadiness in the incident wind speed is incorporated into the XFOIL code by varying incident flow velocities on each blade section, which depend on the azimuthal locations of the rotating blade. The calculated surface pressure distribution is subsequently used to predict acoustic pressure at an observing location by using Lowson’s analogy. These predictions are compared with measured data, which ensures that the present method can reproduce the broadband characteristics of the measured low-frequency noise spectrum. Further investigations are carried out to characterize the IFL noise in terms of pressure loading on blade surface, narrow-band noise spectrum and noise maps around the turbine.

  14. Prediction and analysis of infra and low-frequency noise of upwind horizontal axis wind turbine using statistical wind speed model

    Directory of Open Access Journals (Sweden)

    Gwang-Se Lee

    2014-12-01

    Full Text Available Despite increasing concern about low-frequency noise of modern large horizontal-axis wind turbines (HAWTs, few studies have focused on its origin or its prediction methods. In this paper, infra- and low-frequency (the ILF wind turbine noise are closely examined and an efficient method is developed for its prediction. Although most previous studies have assumed that the ILF noise consists primarily of blade passing frequency (BPF noise components, these tonal noise components are seldom identified in the measured noise spectrum, except for the case of downwind wind turbines. In reality, since modern HAWTs are very large, during rotation, a single blade of the turbine experiences inflow with variation in wind speed in time as well as in space, breaking periodic perturbations of the BPF. Consequently, this transforms acoustic contributions at the BPF harmonics into broadband noise components. In this study, the ILF noise of wind turbines is predicted by combining Lowson’s acoustic analogy with the stochastic wind model, which is employed to reproduce realistic wind speed conditions. In order to predict the effects of these wind conditions on pressure variation on the blade surface, unsteadiness in the incident wind speed is incorporated into the XFOIL code by varying incident flow velocities on each blade section, which depend on the azimuthal locations of the rotating blade. The calculated surface pressure distribution is subsequently used to predict acoustic pressure at an observing location by using Lowson’s analogy. These predictions are compared with measured data, which ensures that the present method can reproduce the broadband characteristics of the measured low-frequency noise spectrum. Further investigations are carried out to characterize the IFL noise in terms of pressure loading on blade surface, narrow-band noise spectrum and noise maps around the turbine.

  15. Incorporating YBCO Coated Conductors in High-speed Superconducting Generators

    Science.gov (United States)

    2008-07-01

    4.0 kW/lb (8.82 kW/kg). The machine configuration chosen by GE for design was a homopolar inductor alternator (HIA) which locates the...extremely severe ac loss environment. Even if this is ultimately impossible for high speed generators, it may not preclude lower speed motors and

  16. Surface grinding characteristics of ferrous metals under high-speed and speed-stroke grinding conditions

    International Nuclear Information System (INIS)

    Ghani, A.K.; Choudhury, I.A.; Ahim, M.B.

    1999-01-01

    Some ferrous metals have been ground under different conditions with high-speed and speed-stroke in surface grinding operation. The paper describes experimental investigation of grinding forces in grinding some ferrous metals with the application of cutting fluids. Grinding tests have been carried out on mild steel, assab steel and stainless steel with different combinations of down feed and cross feed. The wheel speed was 27 m/sec while the table speed was maintained at the maximum possible 25 m/min. The grindability has been evaluated by measuring the grinding forces, grinding ratio, and surface finish. Grinding forces have been plotted against down feed of the grinding wheel and cross feed of the table. It has been observed that the radial and tangential grinding forces in stainless steel were higher than those in assab steel and mild steel

  17. 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.

  18. Trend on High-speed Power Line Communication Technology

    Science.gov (United States)

    Ogawa, Osamu

    High-speed power line communication (PLC) is useful technology to easily build the communication networks, because construction of new infrastructure is not necessary. In Europe and America, PLC has been used for broadband networks since the beginning of 21th century. In Japan, high-speed PLC was deregulated only indoor usage in 2006. Afterward it has been widely used for home area network, LAN in hotels and school buildings and so on. And recently, PLC is greatly concerned as communication technology for smart grid network. In this paper, the author surveys the high-speed PLC technology and its current status.

  19. High-speed AFM of human chromosomes in liquid

    Energy Technology Data Exchange (ETDEWEB)

    Picco, L M; Dunton, P G; Ulcinas, A; Engledew, D J; Miles, M J [H H Wills Physics Laboratory and IRC in Nanotechnology, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Hoshi, O; Ushiki, T [Division of Microscopic Anatomy and Bio-Imaging, Department of Cellular Function, Niigata University Graduate School of Medical and Dental Sciences, Asahimachi-Dori 1, Niigata, 951-8150 (Japan)], E-mail: m.j.miles@bristol.ac.uk

    2008-09-24

    Further developments of the previously reported high-speed contact-mode AFM are described. The technique is applied to the imaging of human chromosomes at video rate both in air and in water. These are the largest structures to have been imaged with high-speed AFM and the first imaging in liquid to be reported. A possible mechanism that allows such high-speed contact-mode imaging without significant damage to the sample is discussed in the context of the velocity dependence of the measured lateral force on the AFM tip.

  20. Rat muscle blood flows during high-speed locomotion

    International Nuclear Information System (INIS)

    Armstrong, R.B.; Laughlin, M.H.

    1985-01-01

    We previously studied blood flow distribution within and among rat muscles as a function of speed from walking (15 m/min) through galloping (75 m/min) on a motor-driven treadmill. The results showed that muscle blood flows continued to increase as a function of speed through 75 m/min. The purpose of the present study was to have rats run up to maximal treadmill speeds to determine if blood flows in the muscles reach a plateau as a function of running speed over the animals normal range of locomotory speeds. Muscle blood flows were measured with radiolabeled microspheres at 1 min of running at 75, 90, and 105 m/min in male Sprague-Dawley rats. The data indicate that even at these relatively high treadmill speeds there was still no clear evidence of a plateau in blood flow in most of the hindlimb muscles. Flows in most muscles continued to increase as a function of speed. These observed patterns of blood flow vs. running speed may have resulted from the rigorous selection of rats that were capable of performing the high-intensity exercise and thus only be representative of a highly specific population of animals. On the other hand, the data could be interpreted to indicate that the cardiovascular potential during exercise is considerably higher in laboratory rats than has normally been assumed and that inadequate blood flow delivery to the muscles does not serve as a major limitation to their locomotory performance

  1. FPGA Flash Memory High Speed Data Acquisition

    Science.gov (United States)

    Gonzalez, April

    2013-01-01

    The purpose of this research is to design and implement a VHDL ONFI Controller module for a Modular Instrumentation System. The goal of the Modular Instrumentation System will be to have a low power device that will store data and send the data at a low speed to a processor. The benefit of such a system will give an advantage over other purchased binary IP due to the capability of allowing NASA to re-use and modify the memory controller module. To accomplish the performance criteria of a low power system, an in house auxiliary board (Flash/ADC board), FPGA development kit, debug board, and modular instrumentation board will be jointly used for the data acquisition. The Flash/ADC board contains four, 1 MSPS, input channel signals and an Open NAND Flash memory module with an analog to digital converter. The ADC, data bits, and control line signals from the board are sent to an Microsemi/Actel FPGA development kit for VHDL programming of the flash memory WRITE, READ, READ STATUS, ERASE, and RESET operation waveforms using Libero software. The debug board will be used for verification of the analog input signal and be able to communicate via serial interface with the module instrumentation. The scope of the new controller module was to find and develop an ONFI controller with the debug board layout designed and completed for manufacture. Successful flash memory operation waveform test routines were completed, simulated, and tested to work on the FPGA board. Through connection of the Flash/ADC board with the FPGA, it was found that the device specifications were not being meet with Vdd reaching half of its voltage. Further testing showed that it was the manufactured Flash/ADC board that contained a misalignment with the ONFI memory module traces. The errors proved to be too great to fix in the time limit set for the project.

  2. Hydraulic turbines

    International Nuclear Information System (INIS)

    Meluk O, G.

    1998-01-01

    The hydraulic turbines are defined according to the specific speed, in impulse turbines and in reaction turbines. Currently, the Pelton turbines (of impulse) and the Francis and Kaplan turbines (of reaction), they are the most important machines in the hydroelectric generation. The hydraulic turbines are capable of generating in short times, large powers, from its loads zero until the total load and reject the load instantly without producing damages in the operation. When the hydraulic resources are important, the hydraulic turbines are converted in the axle of the electric system. Its combination with thermoelectric generation systems, it allow the continuing supply of the variations in demand of energy system. The available hydraulic resource in Colombia is of 93085 MW, of which solely 9% is exploited, become 79% of all the electrical country generation, 21% remaining is provided by means of the thermoelectric generation

  3. General momentum theory for wind turbines at low tip speed ratios

    DEFF Research Database (Denmark)

    Sørensen, Jens Nørkær; van Kuik, Gijs A. M.

    2011-01-01

    General momentum theory is used to study the behaviour of the ‘classical’ free vortex wake model of Joukowsky. This model has recently attained considerable attention as it shows the possibility of achieving a power performance that greatly exceeds the Lanchester‐Betz limit for rotors running...... at low tip speed ratios. This behaviour is confirmed even when including the effect of a centre vortex, allowing azimuthal velocities and the associated radial pressure gradient to be taken into account in the axial momentum balance without any simplifying assumptions. It is shown that the most likely...

  4. Turbine component casting core with high resolution region

    Science.gov (United States)

    Kamel, Ahmed; Merrill, Gary B.

    2014-08-26

    A hollow turbine engine component with complex internal features can include a first region and a second, high resolution region. The first region can be defined by a first ceramic core piece formed by any conventional process, such as by injection molding or transfer molding. The second region can be defined by a second ceramic core piece formed separately by a method effective to produce high resolution features, such as tomo lithographic molding. The first core piece and the second core piece can be joined by interlocking engagement that once subjected to an intermediate thermal heat treatment process thermally deform to form a three dimensional interlocking joint between the first and second core pieces by allowing thermal creep to irreversibly interlock the first and second core pieces together such that the joint becomes physically locked together providing joint stability through thermal processing.

  5. Safety philosophy of gas turbine high temperature reactor (GTHTR300)

    International Nuclear Information System (INIS)

    Shoji Katanishi; Kazuhiko Kunitomi; Shusaku Shiozawa

    2002-01-01

    Japan Atomic Energy Research Institute (JAERI) has undertaken the study of an original design concept of gas turbine high temperature reactor, the GTHTR300. The general concept of this study is development of a greatly simplified design that leads to substantially reduced technical and cost requirements. Newly proposed design features enable the GTHTR300 to be an efficient and economically competitive reactor in 2010's. Also, the GTHTR300 fully takes advantage of its inherent safety characteristics. The safety philosophy of the GTHTR300 is developed based on the HTTR (High Temperature Engineering Test Reactor) of JAERI which is the first HTGR in Japan. Major features of the newly proposed safety philosophy for the GTHTR300 are described in this article. (authors)

  6. High Speed Frame Synchronization and Viterbi Decoding

    DEFF Research Database (Denmark)

    Paaske, Erik; Justesen, Jørn; Larsen, Knud J.

    1996-01-01

    The purpose of Phase 1 of the study is to describe the system structure and algorithms in sufficient detail to allow drawing the high level architecture of units containing frame synchronization and Viterbi decoding. The systems we consider are high data rate space communication systems. Also...... components. Node synchronization performed within a Viterbi decoder is discussed, and algorithms for frame synchronization are described and analyzed. We present a list of system configurations that we find potentially useful. Further, the high level architecture of units that contain frame synchronization...... and various other functions needed in a complete system is presented. Two such units are described, one for placement before the Viterbi decoder and another for placement after the decoder. The high level architectures of three possible implementations of Viterbi decoders are described: The first...

  7. 一种风电机组在低风速区间的功率控制方法%A power control method of wind turbines in low wind speed area

    Institute of Scientific and Technical Information of China (English)

    张安安; 郭红鼎; 于兵; 李楠; 李超

    2015-01-01

    由于在低风速区间风速变化较快、风能密度较低,因此对风电机组的功率转换效率造成了较大影响。针对风电机组在低风速区域的运行特点,从功率控制角度出发,以提高风电机组功率输出效率为目的,采用最大功率点跟踪控制策略(MPPT)实现对风能最大限度的捕获,提出了大范围快速对焦最优转速的控制策略。与传统爬山法相比,该方法具有寻优速度快、精确度高、简单易行的优点。在Power Simulation(PSIM)环境中仿真分析,研究结果表明:该控制策略对提高机组稳定性和功率转换效率具有一定的价值。%Wind velocity alters rapidly and the density of wind energy is lower in low wind speed area, which greatly affect power conversion efficiency of wind turbines. Aimed at enhancing wind turbines efficiency of power output, MPPT is adopted to capture maximum wind power from the perspective of power control according to operating peculiarity of wind turbine in low wind speed area. On the basis, a control strategy of fast focusing optimal rotating speed in wide range is simple, highly accurate and quicker to achieve optimal solution compared with conventional climbing method. Simulation in Power Simulation (PSIM) shows that this control strategy has a certain value for improving wind turbine stability and power conversion efficiency.

  8. 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

  9. High-speed rail turnout literature review : final report.

    Science.gov (United States)

    2016-08-01

    High-speed rail (HSR) turnout design criteria generally address unbalanced lateral acceleration or cant deficiency (CD), cant deficiency change rate (CDCR), and entry and exit jerk. Various countries have adopted different design values for their HSR...

  10. Multicast Performance Analysis for High-Speed Torus Networks

    National Research Council Canada - National Science Library

    Oral, S; George, A

    2002-01-01

    ... for unicast-based and path-based multicast communication on high-speed torus networks. Software-based multicast performance results of selected algorithms on a 16-node Scalable Coherent Interface (SCI) torus are given...

  11. High speed railway track dynamics models, algorithms and applications

    CERN Document Server

    Lei, Xiaoyan

    2017-01-01

    This book systematically summarizes the latest research findings on high-speed railway track dynamics, made by the author and his research team over the past decade. It explores cutting-edge issues concerning the basic theory of high-speed railways, covering the dynamic theories, models, algorithms and engineering applications of the high-speed train and track coupling system. Presenting original concepts, systematic theories and advanced algorithms, the book places great emphasis on the precision and completeness of its content. The chapters are interrelated yet largely self-contained, allowing readers to either read through the book as a whole or focus on specific topics. It also combines theories with practice to effectively introduce readers to the latest research findings and developments in high-speed railway track dynamics. It offers a valuable resource for researchers, postgraduates and engineers in the fields of civil engineering, transportation, highway & railway engineering.

  12. Progress in the development of niobium alloyed high speed steel

    International Nuclear Information System (INIS)

    Guimaraes, J.R.C.

    1987-01-01

    The development of economy-grades of niobium alloyed high speed steel is described. Both the metallurgical concepts behind the steel design and the results of performance tests are presented. (Author) [pt

  13. High-Speed Thermal Characterization of Cryogenic Flows, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Luna proposes to continue development on a high-speed fiber optic sensor and readout system for cryogenic temperature measurements in liquid oxygen (LOX) and liquid...

  14. Noise from wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Fegeant, Olivier [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Building Sciences

    2002-02-01

    A rapid growth of installed wind power capacity is expected in the next few years. However, the siting of wind turbines on a large scale raises concerns about their environmental impact, notably with respect to noise. To this end, variable speed wind turbines offer a promising solution for applications in densely populated areas like the European countries, as this design would enable an efficient utilisation of the masking effect due to ambient noise. In rural and recreational areas where wind turbines are sited, the ambient noise originates from the action of wind on the vegetation and about the listener's ear (pseudo-noise). It shows a wind speed dependence similar to that of the noise from a variable speed wind turbine and can therefore mask the latter for a wide range of conditions. However, a problem inherent to the design of these machines is their proclivity to pure tone generation, because of the enhanced difficulty of avoiding structural resonances in the mechanical parts. Pure tones are deemed highly annoying and are severely regulated by most noise policies. In relation to this problem, the vibration transmission of structure-borne sound to the tower of the turbine is investigated, in particular when the tower is stiffened at its upper end. Furthermore, since noise annoyance due to wind turbine is mostly a masking issue, the wind-related sources of ambient noise are studied and their masking potentials assessed. With this aim, prediction models for wind-induced vegetation noise and pseudo-noise have been developed. Finally, closely related to the effect of masking, is the difficulty, regularly encountered by local authorities and wind farm developers, to measure noise immission from wind turbines. A new measurement technique has thus been developed in the course of this work. Through improving the signal-to-noise ratio between wind turbine noise and ambient noise, the new technique yields more accurate measurement results.

  15. Orthogonal Bases used for Feed Forward Control of Wind Turbines

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Stoustrup, Jakob

    2011-01-01

    In optimizing wind turbines it can be of a large help to use information of wind speeds at upwind turbine for the control of downwind turbines, it is, however, problematic to use these measurements directly since they are highly influenced by turbulence behind the wind turbine rotor plane. In this....... In this paper an orthogonal basis is use to extract the general trends in the wind signal, which are forward to the down wind turbines. This concept controller is designed and simulated on a generic 4.8 MW wind turbine model, which shows the potential of this proposed scheme....

  16. High Speed Frame Synchronization and Viterbi Decoding

    DEFF Research Database (Denmark)

    Paaske, Erik; Justesen, Jørn; Larsen, Knud J.

    1998-01-01

    The study has been divided into two phases. The purpose of Phase 1 of the study was to describe the system structure and algorithms in sufficient detail to allow drawing the high level architecture of units containing frame synchronization and Viterbi decoding. After selection of which specific...... potentially useful.Algorithms for frame synchronization are described and analyzed. Further, the high level architecture of units that contain frame synchronization and various other functions needed in a complete system is presented. Two such units are described, one for placement before the Viterbi decoder...... towards a realization in an FPGA.Node synchronization performed within a Viterbi decoder is discussed, and the high level architectures of three possible implementations of Viterbi decoders are described: The first implementation uses a number of commercially available decoders while the the two others...

  17. High Speed Rail (HSR) in the United States

    Science.gov (United States)

    2009-12-08

    announced that it will expand the capacity on its aging high speed line between Tokyo and Osaka, the most heavily traveled intercity rail segment in the...United States, in most of these countries intercity rail travel (including both conventional and high speed rail) represents less than 10% of all...that is sometimes mentioned by its advocates. Intercity passenger rail transport is relatively safe, at least compared with highway travel . And HSR in

  18. Application of Beyond Bound Decoding for High Speed Optical Communications

    DEFF Research Database (Denmark)

    Li, Bomin; Larsen, Knud J.; Vegas Olmos, Juan José

    2013-01-01

    This paper studies the application of beyond bound decoding method for high speed optical communications. This hard-decision decoding method outperforms traditional minimum distance decoding method, with a total net coding gain of 10.36 dB.......This paper studies the application of beyond bound decoding method for high speed optical communications. This hard-decision decoding method outperforms traditional minimum distance decoding method, with a total net coding gain of 10.36 dB....

  19. Nanocrystalline Ni-Co Alloy Synthesis by High Speed Electrodeposition

    OpenAIRE

    Idris, Jamaliah; Christian, Chukwuekezie; Gaius, Eyu

    2013-01-01

    Electrodeposition of nanocrystals is economically and technologically viable production path for the synthesis of pure metals and alloys both in coatings and bulk form. The study presents nanocrystalline Ni-Co alloy synthesis by high speed electrodeposition. Nanocrystalline Ni-Co alloys coatings were prepared by direct current (DC) and deposited directly on steel and aluminum substrates without any pretreatment, using high speed electrodeposition method. The influence of the electrolysis par...

  20. Development of a super high speed railway and ML 100

    Energy Technology Data Exchange (ETDEWEB)

    Usami, Y

    1973-07-01

    A history of the development progress is given, followed by a discussion of the propulsion system for a super high speed railway-structure. Induction linear motors and synchronous linear motors are discussed in some detail. The maintenance system is then described (basic test apparatus-rotary type superconductive magnetic force maintenance system, etc.). Experiments using a linear running superconductive magnetic test car are discussed. Developments of super high speed railways in America, France, England, West Germany, etc. are described.

  1. Double Tunneling Injection Quantum Dot Lasers for High Speed Operation

    Science.gov (United States)

    2017-10-23

    Double Tunneling-Injection Quantum Dot Lasers for High -Speed Operation The views, opinions and/or findings contained in this report are those of...SECURITY CLASSIFICATION OF: 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 13. SUPPLEMENTARY NOTES 12. DISTRIBUTION AVAILIBILITY STATEMENT 6...State University Title: Double Tunneling-Injection Quantum Dot Lasers for High -Speed Operation Report Term: 0-Other Email: asryan@vt.edu Distribution

  2. High-speed optical signal processing using time lenses

    DEFF Research Database (Denmark)

    Galili, Michael; Hu, Hao; Guan, Pengyu

    2015-01-01

    This paper will discuss time lenses and their broad range of applications. A number of recent demonstrations of complex high-speed optical signal processing using time lenses will be outlined with focus on the operating principle.......This paper will discuss time lenses and their broad range of applications. A number of recent demonstrations of complex high-speed optical signal processing using time lenses will be outlined with focus on the operating principle....

  3. Integrated computer network high-speed parallel interface

    International Nuclear Information System (INIS)

    Frank, R.B.

    1979-03-01

    As the number and variety of computers within Los Alamos Scientific Laboratory's Central Computer Facility grows, the need for a standard, high-speed intercomputer interface has become more apparent. This report details the development of a High-Speed Parallel Interface from conceptual through implementation stages to meet current and future needs for large-scle network computing within the Integrated Computer Network. 4 figures

  4. High speed data transmission at the Superconducting Super Collider

    International Nuclear Information System (INIS)

    Leskovar, B.

    1990-04-01

    High speed data transmission using fiber optics in the data acquisition system of the Superconducting Super Collider has been investigated. Emphasis is placed on the high speed data transmission system overview, the local data network and on subassemblies, such as optical transmitters and receivers. Also, the performance of candidate subassemblies having a low power dissipation for the data acquisition system is discussed. 14 refs., 5 figs

  5. California statewide model for high-speed rail

    OpenAIRE

    Outwater, Maren; Tierney, Kevin; Bradley, Mark; Sall, Elizabeth; Kuppam, Arun; Modugala, Vamsee

    2010-01-01

    The California High Speed Rail Authority (CHSRA) and the Metropolitan Transportation Commission (MTC) have developed a new statewide model to support evaluation of high-speed rail alternatives in the State of California. This statewide model will also support future planning activities of the California Department of Transportation (Caltrans). The approach to this statewide model explicitly recognizes the unique characteristics of intraregional travel demand and interregional travel demand. A...

  6. Minimum Plate Thickness in High-Speed Craft

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup; Zhang, Shengming

    1998-01-01

    The minimum plate thickness requirements specified by the classification societies for high-speed craft are supposed to ensure adequate resistance to impact loads such as collision with floating objects and objects falling on the deck. The paper presents analytical methods of describing such impact...... phenomena and proposes performance requirements instead of thickness requirements for hull panels in high-speed craft made of different building materials....

  7. High-speed precision motion control

    CERN Document Server

    Yamaguchi, Takashi; Pang, Chee Khiang

    2011-01-01

    Written for researchers and postgraduate students in Control Engineering, as well as professionals in the Hard Disk Drive industry, this book discusses high-precision and fast servo controls in Hard Disk Drives (HDDs). The editors present a number of control algorithms that enable fast seeking and high precision positioning, and propose problems from commercial products, making the book valuable to researchers in HDDs. Each chapter is self contained, and progresses from concept to technique, present application examples that can be used within automotive, aerospace, aeronautical, and manufactu

  8. Innovation in Vertical Axis Hydrokinetic Turbine – Straight Blade Cascaded (VAHT-SBC) design and testing for low current speed power generation

    Science.gov (United States)

    Hantoro, R.; Utama, I. K. A. P.; Arief, I. S.; Ismail, A.; Manggala, S. W.

    2018-05-01

    This study examines an innovative turbine with the addition of the number and arrangement of straight blade cascaded (SBC). SBC is a combination of passive variable-pitch and fixed pitch of each turbine arm. This study was conducted in an open channel flow that has a current velocity (V-m/s) of 1.1, 1.2, and 1.3. RPM and torque ware measured for coefficient of performance (Cp) and tip speed ratio (TSR) calculation. Without changing the turbine dimension, the employment of cascaded blade (three blades in each arm) contributes to improve energy extraction significantly. A significant increase in Cp value is seen when 9 blades (3 cascaded blades per arm) are used with a Cp 0.42 value at TSR 2.19. This value has reached 93% of the maximum theoritical Cp value.

  9. A high-speed analog neural processor

    NARCIS (Netherlands)

    Masa, P.; Masa, Peter; Hoen, Klaas; Hoen, Klaas; Wallinga, Hans

    1994-01-01

    Targeted at high-energy physics research applications, our special-purpose analog neural processor can classify up to 70 dimensional vectors within 50 nanoseconds. The decision-making process of the implemented feedforward neural network enables this type of computation to tolerate weight

  10. High-speed X-ray topography

    International Nuclear Information System (INIS)

    Eckers, W.; Oppolzer, H.

    1977-01-01

    The investigation of lattice defects in semiconductor crystals by conventional X-ray diffraction topography is very time-consuming. Exposure times can be reduced by using high-intensity X-rays and X-ray image intensifiers. The described system comprises a high-power rotating-anode X-ray tube, a remote-controlled X-ray topography camera, and a television system operating with an X-ray sensing VIDICON. System performance is demonstrated with reference to exploratory examples. The exposure time for photographic plates is reduced to 1/20 and for the X-ray TV system (resolution of the order of 30 μm) to 1/100 relative to that required when using a conventional topography system. (orig.) [de

  11. High-speed quantum networking by ship

    Science.gov (United States)

    Devitt, Simon J.; Greentree, Andrew D.; Stephens, Ashley M.; van Meter, Rodney

    2016-11-01

    Networked entanglement is an essential component for a plethora of quantum computation and communication protocols. Direct transmission of quantum signals over long distances is prevented by fibre attenuation and the no-cloning theorem, motivating the development of quantum repeaters, designed to purify entanglement, extending its range. Quantum repeaters have been demonstrated over short distances, but error-corrected, global repeater networks with high bandwidth require new technology. Here we show that error corrected quantum memories installed in cargo containers and carried by ship can provide a exible connection between local networks, enabling low-latency, high-fidelity quantum communication across global distances at higher bandwidths than previously proposed. With demonstrations of technology with sufficient fidelity to enable topological error-correction, implementation of the quantum memories is within reach, and bandwidth increases with improvements in fabrication. Our approach to quantum networking avoids technological restrictions of repeater deployment, providing an alternate path to a worldwide Quantum Internet.

  12. High speed gated x-ray imagers

    International Nuclear Information System (INIS)

    Kilkenny, J.D.; Bell, P.; Hanks, R.; Power, G.; Turner, R.E.; Wiedwald, J.

    1988-01-01

    Single and multi-frame gated x-ray images with time-resolution as fast as 150 psec are described. These systems are based on the gating of microchannel plates in a stripline configuration. The gating voltage comes from the avalanche breakdown of reverse biased p-n junction producing high power voltage pulses as short as 70 psec. Results from single and four frame x-ray cameras used on Nova are described. 8 refs., 9 figs

  13. Sensitivity of Turbine-Height Wind Speeds to Parameters in Planetary Boundary-Layer and Surface-Layer Schemes in the Weather Research and Forecasting Model

    Science.gov (United States)

    Yang, Ben; Qian, Yun; Berg, Larry K.; Ma, Po-Lun; Wharton, Sonia; Bulaevskaya, Vera; Yan, Huiping; Hou, Zhangshuan; Shaw, William J.

    2017-01-01

    We evaluate the sensitivity of simulated turbine-height wind speeds to 26 parameters within the Mellor-Yamada-Nakanishi-Niino (MYNN) planetary boundary-layer scheme and MM5 surface-layer scheme of the Weather Research and Forecasting model over an area of complex terrain. An efficient sampling algorithm and generalized linear model are used to explore the multiple-dimensional parameter space and quantify the parametric sensitivity of simulated turbine-height wind speeds. The results indicate that most of the variability in the ensemble simulations is due to parameters related to the dissipation of turbulent kinetic energy (TKE), Prandtl number, turbulent length scales, surface roughness, and the von Kármán constant. The parameter associated with the TKE dissipation rate is found to be most important, and a larger dissipation rate produces larger hub-height wind speeds. A larger Prandtl number results in smaller nighttime wind speeds. Increasing surface roughness reduces the frequencies of both extremely weak and strong airflows, implying a reduction in the variability of wind speed. All of the above parameters significantly affect the vertical profiles of wind speed and the magnitude of wind shear. The relative contributions of individual parameters are found to be dependent on both the terrain slope and atmospheric stability.

  14. Research on the tool holder mode in high speed machining

    Science.gov (United States)

    Zhenyu, Zhao; Yongquan, Zhou; Houming, Zhou; Xiaomei, Xu; Haibin, Xiao

    2018-03-01

    High speed machining technology can improve the processing efficiency and precision, but also reduce the processing cost. Therefore, the technology is widely regarded in the industry. With the extensive application of high-speed machining technology, high-speed tool system has higher and higher requirements on the tool chuck. At present, in high speed precision machining, several new kinds of clip heads are as long as there are heat shrinkage tool-holder, high-precision spring chuck, hydraulic tool-holder, and the three-rib deformation chuck. Among them, the heat shrinkage tool-holder has the advantages of high precision, high clamping force, high bending rigidity and dynamic balance, etc., which are widely used. Therefore, it is of great significance to research the new requirements of the machining tool system. In order to adapt to the requirement of high speed machining precision machining technology, this paper expounds the common tool holder technology of high precision machining, and proposes how to select correctly tool clamping system in practice. The characteristics and existing problems are analyzed in the tool clamping system.

  15. High-speed and high-ratio referential genome compression.

    Science.gov (United States)

    Liu, Yuansheng; Peng, Hui; Wong, Limsoon; Li, Jinyan

    2017-11-01

    The rapidly increasing number of genomes generated by high-throughput sequencing platforms and assembly algorithms is accompanied by problems in data storage, compression and communication. Traditional compression algorithms are unable to meet the demand of high compression ratio due to the intrinsic challenging features of DNA sequences such as small alphabet size, frequent repeats and palindromes. Reference-based lossless compression, by which only the differences between two similar genomes are stored, is a promising approach with high compression ratio. We present a high-performance referential genome compression algorithm named HiRGC. It is based on a 2-bit encoding scheme and an advanced greedy-matching search on a hash table. We compare the performance of HiRGC with four state-of-the-art compression methods on a benchmark dataset of eight human genomes. HiRGC takes compress about 21 gigabytes of each set of the seven target genomes into 96-260 megabytes, achieving compression ratios of 217 to 82 times. This performance is at least 1.9 times better than the best competing algorithm on its best case. Our compression speed is also at least 2.9 times faster. HiRGC is stable and robust to deal with different reference genomes. In contrast, the competing methods' performance varies widely on different reference genomes. More experiments on 100 human genomes from the 1000 Genome Project and on genomes of several other species again demonstrate that HiRGC's performance is consistently excellent. The C ++ and Java source codes of our algorithm are freely available for academic and non-commercial use. They can be downloaded from https://github.com/yuansliu/HiRGC. jinyan.li@uts.edu.au. Supplementary data are available at Bioinformatics online. © The Author (2017). Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com

  16. 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.

  17. 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.

  18. Application of stochastic methods for wind speed forecasting and wind turbines design at the area of Thessaly, Greece

    Science.gov (United States)

    Dimitriadis, Panayiotis; Lazaros, Lappas; Daskalou, Olympia; Filippidou, Ariadni; Giannakou, Marianna; Gkova, Eleni; Ioannidis, Romanos; Polydera, Angeliki; Polymerou, Eleni; Psarrou, Eleftheria; Vyrini, Alexandra; Papalexiou, Simon; Koutsoyiannis, Demetris

    2015-04-01

    Several methods exist for estimating the statistical properties of wind speed, most of them being deterministic or probabilistic, disregarding though its long-term behaviour. Here, we focus on the stochastic nature of wind. After analyzing several historical timeseries at the area of interest (AoI) in Thessaly (Greece), we show that a Hurst-Kolmogorov (HK) behaviour is apparent. Thus, disregarding the latter could lead to unrealistic predictions and wind load situations, causing some impact on the energy production and management. Moreover, we construct a stochastic model capable of preserving the HK behaviour and we produce synthetic timeseries using a Monte-Carlo approach to estimate the future wind loads in the AoI. Finally, we identify the appropriate types of wind turbines for the AoI (based on the IEC 61400 standards) and propose several industrial solutions. Acknowledgement: This research is conducted within the frame of the undergraduate course "Stochastic Methods in Water Resources" of the National Technical University of Athens (NTUA). The School of Civil Engineering of NTUA provided moral support for the participation of the students in the Assembly.

  19. Sphinx, the high speed flash radiography

    International Nuclear Information System (INIS)

    Anon.

    1997-01-01

    Sphinx (Nanosecond Pulse X-Photon Source) is the most compact (0.1 m 3 ) existing system which can generates short pulses (10 to 30 nanoseconds) of 5 to 180 keV X-photon radiation with a repeating cadence of 100 pulses per second and doses which can reach 2 mR at 1 m. This system was developed by the Research Group on Energetics of Ionized Media (GREMI) from the CNRS (French National Center for Scientific Research) and the University of Orleans (France). Sphinx is the smallest device from a series of compact X-ray sources ranging from 5 to 400 keV. These devices can have several possible applications such as the study of ultra-fast phenomena, the high cadence flash radiography in medicine, biology, materials studies, pre-ionizing of gas lasers, self-excitation and photo-ionization of atoms, molecules or aggregates. (J.S.)

  20. Control structures for high speed processors

    Science.gov (United States)

    Maki, G. K.; Mankin, R.; Owsley, P. A.; Kim, G. M.

    1982-01-01

    A special processor was designed to function as a Reed Solomon decoder with throughput data rate in the Mhz range. This data rate is significantly greater than is possible with conventional digital architectures. To achieve this rate, the processor design includes sequential, pipelined, distributed, and parallel processing. The processor was designed using a high level language register transfer language. The RTL can be used to describe how the different processes are implemented by the hardware. One problem of special interest was the development of dependent processes which are analogous to software subroutines. For greater flexibility, the RTL control structure was implemented in ROM. The special purpose hardware required approximately 1000 SSI and MSI components. The data rate throughput is 2.5 megabits/second. This data rate is achieved through the use of pipelined and distributed processing. This data rate can be compared with 800 kilobits/second in a recently proposed very large scale integration design of a Reed Solomon encoder.

  1. Hybrid high solar share gas turbine systems with innovative gas turbine cycles

    OpenAIRE

    Puppe, Michael; Giuliano, Stefano; Buck, Reiner; Krüger, Michael; Lammel, Oliver; Boje, Sven; Saidi, Karim; Gampe, Uwe; Felsmann, Christian; Freimark, Manfred; Langnickel, Ulrich

    2015-01-01

    In this paper results from an ongoing research project (HYGATE) are presented, which is performed to reduce the levelized cost of electricity (LCOE) and to increase the CO2 reduction potential of the solar-hybrid gas turbine plant concept (SHGT). Key improvements are the integration of thermal energy storage and the reduction of the operating temperature of the gas turbine to 950°C. As a result the solar receiver can provide the necessary temperature for solar-only operation of the plant at d...

  2. High Power Electronics - Key Technology for Wind Turbines

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Ma, Ke

    2014-01-01

    reliability challenges for the future wind turbines are explained. It is concluded that the wind turbine behavior/performance can be significantly improved by introducing power electronics, and there will be higher requirements for the power electronics performances in wind power application....

  3. ALICE HLT high speed tracking on GPU

    CERN Document Server

    Gorbunov, Sergey; Aamodt, Kenneth; Alt, Torsten; Appelshauser, Harald; Arend, Andreas; Bach, Matthias; Becker, Bruce; Bottger, Stefan; Breitner, Timo; Busching, Henner; Chattopadhyay, Sukalyan; Cleymans, Jean; Cicalo, Corrado; Das, Indranil; Djuvsland, Oystein; Engel, Heiko; Erdal, Hege Austrheim; Fearick, Roger; Haaland, Oystein Senneset; Hille, Per Thomas; Kalcher, Sebastian; Kanaki, Kalliopi; Kebschull, Udo Wolfgang; Kisel, Ivan; Kretz, Matthias; Lara, Camillo; Lindal, Sven; Lindenstruth, Volker; Masoodi, Arshad Ahmad; Ovrebekk, Gaute; Panse, Ralf; Peschek, Jorg; Ploskon, Mateusz; Pocheptsov, Timur; Ram, Dinesh; Rascanu, Theodor; Richter, Matthias; Rohrich, Dieter; Ronchetti, Federico; Skaali, Bernhard; Smorholm, Olav; Stokkevag, Camilla; Steinbeck, Timm Morten; Szostak, Artur; Thader, Jochen; Tveter, Trine; Ullaland, Kjetil; Vilakazi, Zeblon; Weis, Robert; Yin, Zhong-Bao; Zelnicek, Pierre

    2011-01-01

    The on-line event reconstruction in ALICE is performed by the High Level Trigger, which should process up to 2000 events per second in proton-proton collisions and up to 300 central events per second in heavy-ion collisions, corresponding to an inp ut data stream of 30 GB/s. In order to fulfill the time requirements, a fast on-line tracker has been developed. The algorithm combines a Cellular Automaton method being used for a fast pattern recognition and the Kalman Filter method for fitting of found trajectories and for the final track selection. The tracker was adapted to run on Graphics Processing Units (GPU) using the NVIDIA Compute Unified Device Architecture (CUDA) framework. The implementation of the algorithm had to be adjusted at many points to allow for an efficient usage of the graphics cards. In particular, achieving a good overall workload for many processor cores, efficient transfer to and from the GPU, as well as optimized utilization of the different memories the GPU offers turned out to be cri...

  4. High speed motion-picture photography. Instrumentation and application

    International Nuclear Information System (INIS)

    Bertin-Maghit, G.; Delli, C.; Falgayrettes, M.

    1981-01-01

    Filming technology at 5,000 frames/second is presented in this paper for the determination of the volume and the expension speed of a gas bubble in water. The high speed 16 mm movie camera, fitted with ultra-wide angle lenses, is placed in front of a side light facing the bubble. Ten 60 ms fast flashes, released in succession, illuminate the bubble [fr

  5. High Speed Trimaran (HST) Seatrain Experiments, Model 5714

    Science.gov (United States)

    2013-12-01

    wave absorbing beach at the other. The carriage has electro-hydraulic drive and a regenerative braking system with a maximum carriage speed of 20...Carderock Division To: Commander, Naval Sea Systems Command (PMS3 85) Subj FORWARDING OF REPORT Encl: (1) NSWCCD-80-TR-2013/015, "High Speed Trimaran...and verify the system processes and capability. Your comments will be reviewed and are appreciated. JUDE F. BROWN By direction Copy to: NAVSEA

  6. The sound of high winds. The effect of atmospheric stability on wind turbine sound and microphone noise

    International Nuclear Information System (INIS)

    Van den Berg, G.P.

    2006-01-01

    In this thesis issues are raised concerning wind turbine noise and its relationship to altitude dependent wind velocity. The following issues are investigated: what is the influence of atmospheric stability on the speed and sound power of a wind turbine?; what is the influence of atmospheric stability on the character of wind turbine sound?; how widespread is the impact of atmospheric stability on wind turbine performance: is it relevant for new wind turbine projects; how can noise prediction take this stability into account?; what can be done to deal with the resultant higher impact of wind turbine sound? Apart from these directly wind turbine related issues, a final aim was to address a measurement problem: how does wind on a microphone affect the measurement of the ambient sound level?

  7. Turbine stage model

    International Nuclear Information System (INIS)

    Kazantsev, A.A.

    2009-01-01

    A model of turbine stage for calculations of NPP turbine department dynamics in real time was developed. The simulation results were compared with manufacturer calculations for NPP low-speed and fast turbines. The comparison results have shown that the model is valid for real time simulation of all modes of turbines operation. The model allows calculating turbine stage parameters with 1% accuracy. It was shown that the developed turbine stage model meets the accuracy requirements if the data of turbine blades setting angles for all turbine stages are available [ru

  8. Recent progress on high-speed optical transmission

    Directory of Open Access Journals (Sweden)

    Jianjun Yu

    2016-05-01

    Full Text Available The recently reported high spectral efficiency (SE and high-baud-rate signal transmission are all based on digital coherent optical communications and digital signal processing (DSP. DSP simplifies the reception of advanced modulation formats and also enables the major electrical and optical impairments to be processed and compensated in the digital domain, at the transmitter or receiver side. In this paper, we summarize the research progress on high-speed signal generation and detection and also show the progress on DSP for high-speed signal detection. We also report the latest progress on multi-core and multi-mode multiplexing.

  9. Short Circuits of a 10 MW High Temperature Superconducting Wind Turbine Generator

    NARCIS (Netherlands)

    Song, X.; Polinder, H.; Liu, D.; Mijatovic, Nenad; Holbøll, Joachim; Jensen, Bogi Bech

    Direct drive high temperature superconducting (HTS) wind turbine generators have been proposed to tackle challenges for ever increasing wind turbine ratings. Due to smaller reactances in HTS generators, higher fault currents and larger transient torques could occur if sudden short circuits happen at

  10. FY 2000 report on the results of the leading R and D on MGC ultra high efficiency turbine system technology; 2000 nendo MGC chokokoritsu turbine system gijutsu sendo kenkyu kaihatsu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-03-01

    The R and D were conducted with the aim of using melt-growth composite materials (MGC) as structural members of the gas turbine system for power generation, etc., and the results of the FY 2000 results were summed up. As to the heightening of performance of MGC materials, improvement in high temperature strength, fracture toughness and thermal shock resistance was obtained by making the material structure minute by increasing the mold descending speed in ternary system MGC materials. Concerning the enlarging technology, trially manufactured were a large sample of 53mm diameter and a thin plate of 40mm width x 80mm height x 6mm thickness. In the study of evaluation of mechanical/physical characteristics of MGC materials, the following were indicated: AYZ ternary system MGC materials were twice higher in bending strength than Al{sub 2}O{sub 3}/YAG binary system, and were equal in creep characteristics at 1,700 degrees C to Al{sub 2}O{sub 3}/YAG. The applicability to turbine stationary blade was shown. In the system study, by applying MGC materials to gas turbine stationary blade, small- and medium-size gas turbine cycles were set up which have plant gross thermal efficiency of 38% at turbine inlet temperature of 1,700 degrees C. (NEDO)

  11. An ultra-high speed whole slide image viewing system.

    Science.gov (United States)

    Yagi, Yukako; Yoshioka, Shigeatsu; Kyusojin, Hiroshi; Onozato, Maristela; Mizutani, Yoichi; Osato, Kiyoshi; Yada, Hiroaki; Mark, Eugene J; Frosch, Matthew P; Louis, David N

    2012-01-01

    One of the goals for a Whole Slide Imaging (WSI) system is implementation in the clinical practice of pathology. One of the unresolved problems in accomplishing this goal is the speed of the entire process, i.e., from viewing the slides through making the final diagnosis. Most users are not satisfied with the correct viewing speeds of available systems. We have evaluated a new WSI viewing station and tool that focuses on speed. A prototype WSI viewer based on PlayStation®3 with wireless controllers was evaluated at the Department of Pathology at MGH for the following reasons: 1. For the simulation of signing-out cases; 2. Enabling discussion at a consensus conference; and 3. Use at slide seminars during a Continuing Medical Education course. Pathologists were being able to use the system comfortably after 0-15 min training. There were no complaints regarding speed. Most pathologists were satisfied with the functionality, usability and speed of the system. The most difficult situation was simulating diagnostic sign-out. The preliminary results of adapting the Sony PlayStation®3 (PS3®) as an ultra-high speed WSI viewing system were promising. The achieved speed is consistent with what would be needed to use WSI in daily practice.

  12. Nickel/Diamond Composite Coating Prepared by High Speed Electrodeposition

    Directory of Open Access Journals (Sweden)

    ZHANG Yan

    2016-10-01

    Full Text Available Nickel/diamond composite coatings were prepared on the basis of a new high speed electroplating bath. The influence of additives, plating parameters and diamond concentration on internal stress was investigated in order to find the solution to decrease the stress introduced by high current density; the micro morphology of the coatings were observed by SEM. The bath and depositing parameters were optimized that thick nickel/diamond composite coatings with low internal stress can be high speed electroplated with a high cathode current density of 30A/dm2. The results show that when plated with bath composition and parameters as follows: sodium dodecyl sulfate 0.5g/L, ammonium acetate 3g/L, sodium citrate 1.5g/L, diamond particles 30g/L; pH value 3-4, temperature 50℃, the composite coatings prepared in high speed have the lowest internal stress.

  13. Material requirements for the High Speed Civil Transport

    Science.gov (United States)

    Stephens, Joseph R.; Hecht, Ralph J.; Johnson, Andrew M.

    1993-01-01

    Under NASA-sponsored High Speed Research (HSR) programs, the materials and processing requirements have been identified for overcoming the environmental and economic barriers of the next generation High Speed Civil Transport (HSCT) propulsion system. The long (2 to 5 hours) supersonic cruise portion of the HSCT cycle will place additional durability requirements on all hot section engine components. Low emissions combustor designs will require high temperature ceramic matrix composite liners to meet an emission goal of less than 5g NO(x) per Kg fuel burned. Large axisymmetric and two-dimensional exhaust nozzle designs are now under development to meet or exceed FAR 36 Stage III noise requirements, and will require lightweight, high temperature metallic, intermetallic, and ceramic matrix composites to reduce nozzle weight and meet structural and acoustic component performance goals. This paper describes and discusses the turbomachinery, combustor, and exhaust nozzle requirements of the High Speed Civil Transport propulsion system.

  14. Observation of high-resolution wind fields and offshore wind turbine wakes using TerraSAR-X imagery

    Science.gov (United States)

    Gies, Tobias; Jacobsen, Sven; Lehner, Susanne; Pleskachevsky, Andrey

    2014-05-01

    1. Introduction Numerous large-scale offshore wind farms have been built in European waters and play an important role in providing renewable energy. Therefore, knowledge of behavior of wakes, induced by large wind turbines and their impact on wind power output is important. The spatial variation of offshore wind turbine wake is very complex, depending on wind speed, wind direction, ambient atmospheric turbulence and atmospheric stability. In this study we demonstrate the application of X-band TerraSAR-X (TS-X) data with high spatial resolution for studies on wind turbine wakes in the near and far field of the offshore wind farm Alpha Ventus, located in the North Sea. Two cases which different weather conditions and different wake pattern as observed in the TS-X image are presented. 2. Methods The space-borne synthetic aperture radar (SAR) is a unique sensor that provides two-dimensional information on the ocean surface. Due to their high resolution, daylight and weather independency and global coverage, SARs are particularly suitable for many ocean and coastal applications. SAR images reveal wind variations on small scales and thus represent a valuable means in detailed wind-field analysis. The general principle of imaging turbine wakes is that the reduced wind speed downstream of offshore wind farms modulates the sea surface roughness, which in turn changes the Normalized Radar Cross Section (NRCS, denoted by σ0) in the SAR image and makes the wake visible. In this study we present two cases at the offshore wind farm Alpha Ventus to investigate turbine-induced wakes and the retrieved sea surface wind field. Using the wind streaks, visible in the TS-X image and the shadow behind the offshore wind farm, induced by turbine wake, the sea surface wind direction is derived and subsequently the sea surface wind speed is calculated using the latest generation of wind field algorithm XMOD2. 3. Case study alpha ventus Alpha Ventus is located approximately 45 km from the

  15. Assessment of rural soundscapes with high-speed train noise.

    Science.gov (United States)

    Lee, Pyoung Jik; Hong, Joo Young; Jeon, Jin Yong

    2014-06-01

    In the present study, rural soundscapes with high-speed train noise were assessed through laboratory experiments. A total of ten sites with varying landscape metrics were chosen for audio-visual recording. The acoustical characteristics of the high-speed train noise were analyzed using various noise level indices. Landscape metrics such as the percentage of natural features (NF) and Shannon's diversity index (SHDI) were adopted to evaluate the landscape features of the ten sites. Laboratory experiments were then performed with 20 well-trained listeners to investigate the perception of high-speed train noise in rural areas. The experiments consisted of three parts: 1) visual-only condition, 2) audio-only condition, and 3) combined audio-visual condition. The results showed that subjects' preference for visual images was significantly related to NF, the number of land types, and the A-weighted equivalent sound pressure level (LAeq). In addition, the visual images significantly influenced the noise annoyance, and LAeq and NF were the dominant factors affecting the annoyance from high-speed train noise in the combined audio-visual condition. In addition, Zwicker's loudness (N) was highly correlated with the annoyance from high-speed train noise in both the audio-only and audio-visual conditions. © 2013.

  16. Investigation into the effects of operating conditions and design parameters on the creep life of high pressure turbine blades in a stationary gas turbine engine

    OpenAIRE

    Eshati, Samir; Abu, Abdullahi; Laskaridis, Panagiotis; Haslam, Anthony

    2011-01-01

    A physics–based model is used to investigate the relationship between operating conditions and design parameters on the creep life of a stationary gas turbine high pressure turbine (HPT) blade. A performance model is used to size the blade and to determine its stresses. The effects of radial temperature distortion, turbine inlet temperature, ambient temperature and compressor degradation on creep life are then examined. The results show variations in creep life and failure locat...

  17. HDR 192Ir source speed measurements using a high speed video camera

    International Nuclear Information System (INIS)

    Fonseca, Gabriel P.; Viana, Rodrigo S. S.; Yoriyaz, Hélio; Podesta, Mark; Rubo, Rodrigo A.; Sales, Camila P. de; Reniers, Brigitte; Verhaegen, Frank

    2015-01-01

    Purpose: The dose delivered with a HDR 192 Ir afterloader can be separated into a dwell component, and a transit component resulting from the source movement. The transit component is directly dependent on the source speed profile and it is the goal of this study to measure accurate source speed profiles. Methods: A high speed video camera was used to record the movement of a 192 Ir source (Nucletron, an Elekta company, Stockholm, Sweden) for interdwell distances of 0.25–5 cm with dwell times of 0.1, 1, and 2 s. Transit dose distributions were calculated using a Monte Carlo code simulating the source movement. Results: The source stops at each dwell position oscillating around the desired position for a duration up to (0.026 ± 0.005) s. The source speed profile shows variations between 0 and 81 cm/s with average speed of ∼33 cm/s for most of the interdwell distances. The source stops for up to (0.005 ± 0.001) s at nonprogrammed positions in between two programmed dwell positions. The dwell time correction applied by the manufacturer compensates the transit dose between the dwell positions leading to a maximum overdose of 41 mGy for the considered cases and assuming an air-kerma strength of 48 000 U. The transit dose component is not uniformly distributed leading to over and underdoses, which is within 1.4% for commonly prescribed doses (3–10 Gy). Conclusions: The source maintains its speed even for the short interdwell distances. Dose variations due to the transit dose component are much lower than the prescribed treatment doses for brachytherapy, although transit dose component should be evaluated individually for clinical cases

  18. 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).

  19. The Design of High Efficiency Crossflow Hydro Turbines: A Review and Extension

    Directory of Open Access Journals (Sweden)

    Ram Adhikari

    2018-01-01

    Full Text Available Efficiency is a critical consideration in the design of hydro turbines. The crossflow turbine is the cheapest and easiest hydro turbine to manufacture and so is commonly used in remote power systems for developing countries. A longstanding problem for practical crossflow turbines is their lower maximum efficiency compared to their more advanced counterparts, such as Pelton and Francis turbines. This paper reviews the experimental and computational studies relevant to the design of high efficiency crossflow turbines. We concentrate on the studies that have contributed to designs with efficiencies in the range of 88–90%. Many recent studies have been conducted on turbines of low maximum efficiency, which we believe is due to misunderstanding of design principles for achieving high efficiencies. We synthesize the key results of experimental and computational fluid dynamics studies to highlight the key fundamental design principles for achieving efficiencies of about 90%, as well as future research and development areas to further improve the maximum efficiency. The main finding of this review is that the total conversion of head into kinetic energy in the nozzle and the matching of nozzle and runner designs are the two main design requirements for the design of high efficiency turbines.

  20. Design of high-speed ECT and ERT system

    International Nuclear Information System (INIS)

    Wang Baoliang; Huang Zhiyao; Li Haiqing

    2009-01-01

    Process tomography technique provides a novel method to investigate the multi-phase flow distribution inside pipe or vessel. Electrical resistance tomography (ERT) and electrical capacitance tomography (ECT) are extensively studied in recent years. As the capacitance to voltage and resistance to voltage converters run faster, the speeds of other circuits in the system, such as MCU, A/D, D/A etc, have become the bottlenecks of improving the speed. This paper describes a new dual-modal, ECT and ERT, data acquisition system. The system is controlled by a digital signal processor. Both the ERT and the ECT systems use one platform to simplify the system design and maintenance. The system can work at high speed which is only limited by the capacitance to voltage converter or resistance to voltage converter. Primary test results show the speed of the new system is 1400 frames/second for 16-electrode ERT and 2200 frames/second for 12-electrode ECT.

  1. Energetic optimization of regenerative braking for high speed railway systems

    International Nuclear Information System (INIS)

    Frilli, Amedeo; Meli, Enrico; Nocciolini, Daniele; Pugi, Luca; Rindi, Andrea

    2016-01-01

    Highlights: • A model of longitudinal dynamics of the High-speed train ETR1000 is presented. • The model includes on board traction and braking subsystems. • Interactions between overhead line and power line are modelled. • The model is validated on real experimental data. • An energy storage strategy for a high-speed line is proposed. - Abstract: The current development trend in the railway field has led to an ever increasing interest for the energetic optimization of railway systems (especially considering the braking phases), with a strong attention to the mutual interactions between the loads represented by railway vehicles and the electrical infrastructure, including all the sub-systems related to distribution and smart energy management such as energy storage systems. In this research work, the authors developed an innovative coupled modelling approach suitable for the analysis of the energetic optimization of railway systems and based on the use of the new object oriented language Matlab-Simscape™, which presents several advantages with respect to conventional modelling tools. The proposed model has been validated considering an Italian Direct Current High-speed line and the High-speed train ETR 1000. Furthermore, the model has been used to perform an efficiency analysis, considering the use of energy storage devices. The results obtained with the developed model show that the use of energy recovery systems in high-speed railway can provide great opportunities of energy savings.

  2. High-speed railway signal trackside equipment patrol inspection system

    Science.gov (United States)

    Wu, Nan

    2018-03-01

    High-speed railway signal trackside equipment patrol inspection system comprehensively applies TDI (time delay integration), high-speed and highly responsive CMOS architecture, low illumination photosensitive technique, image data compression technique, machine vision technique and so on, installed on high-speed railway inspection train, and achieves the collection, management and analysis of the images of signal trackside equipment appearance while the train is running. The system will automatically filter out the signal trackside equipment images from a large number of the background image, and identify of the equipment changes by comparing the original image data. Combining with ledger data and train location information, the system accurately locate the trackside equipment, conscientiously guiding maintenance.

  3. Single-Photon Tracking for High-Speed Vision

    Directory of Open Access Journals (Sweden)

    Istvan Gyongy

    2018-01-01

    Full Text Available Quanta Imager Sensors provide photon detections at high frame rates, with negligible read-out noise, making them ideal for high-speed optical tracking. At the basic level of bit-planes or binary maps of photon detections, objects may present limited detail. However, through motion estimation and spatial reassignment of photon detections, the objects can be reconstructed with minimal motion artefacts. We here present the first demonstration of high-speed two-dimensional (2D tracking and reconstruction of rigid, planar objects with a Quanta Image Sensor, including a demonstration of depth-resolved tracking.

  4. Preliminary tests of a high speed vertical axis windmill model

    Energy Technology Data Exchange (ETDEWEB)

    South, P; Rangi, R S

    1971-01-01

    This report discusses a fixed-pitch vertical axis windmill that combines the inherent simplicity of this type of machine with a high aerodynamic efficiency and a high relative velocity. A three-bladed rotor was selected as the basic design, having constant chord symmetric airfoil blades configured in a catenary curve such that the rotor diameter is equal to the rotor height. In wind tunnel tests using a 30 inch scale model, it was found that once this rotor was given a very low rotational speed, it picked up speed and ran at a rotor tip velocity/wind speed ratio greater than 1. The number of blades was varied in the testing. A maximum power coefficient of 0.67 was achieved at 17 ft/s wind speed at a tip speed/wind speed ratio of 7.25 for a 2-bladed rotor. Increasing the number of blades above 3 did not result in higher power. The rotor could operate in gusts which double the mean wind velocity. Examination of Reynolds number effects, and taking into account the scale of the model, it was concluded that a full-scale windmill could run at lower velocity ratios than those predicted by the model tests, and that it could self-start under no-load conditions if the cut-in rpm are at least half the rpm for maximum power at the prevailing wind speed. Preliminary estimates show that a 15 ft diameter windmill of this design, designed to operate with a safety factor of 2.5 up to a maximum wind speed of 60 ft/s, would weigh ca 150 lb and could be marketed for ca $60.00, excluding the driven unit, if sufficient quantities were produced to make tooling costs negligible. Similarly, a 30 ft windmill would weigh ca 1000 lb and cost ca $400.00. 2 refs., 6 figs.

  5. High temperature gas-cooled reactor: gas turbine application study

    International Nuclear Information System (INIS)

    1980-12-01

    The high-temperature capability of the High-Temperature Gas-Cooled Reactor (HTGR) is a distinguishing characteristic which has long been recognized as significant both within the US and within foreign nuclear energy programs. This high-temperature capability of the HTGR concept leads to increased efficiency in conventional applications and, in addition, makes possible a number of unique applications in both electrical generation and industrial process heat. In particular, coupling the HTGR nuclear heat source to the Brayton (gas turbine) Cycle offers significant potential benefits to operating utilities. This HTGR-GT Application Study documents the effort to evaluate the appropriateness of the HTGR-GT as an HTGR Lead Project. The scope of this effort included evaluation of the HTGR-GT technology, evaluation of potential HTGR-GT markets, assessment of the economics of commercial HTGR-GT plants, and evaluation of the program and expenditures necessary to establish HTGR-GT technology through the completion of the Lead Project

  6. High temperature gas-cooled reactor: gas turbine application study

    Energy Technology Data Exchange (ETDEWEB)

    1980-12-01

    The high-temperature capability of the High-Temperature Gas-Cooled Reactor (HTGR) is a distinguishing characteristic which has long been recognized as significant both within the US and within foreign nuclear energy programs. This high-temperature capability of the HTGR concept leads to increased efficiency in conventional applications and, in addition, makes possible a number of unique applications in both electrical generation and industrial process heat. In particular, coupling the HTGR nuclear heat source to the Brayton (gas turbine) Cycle offers significant potential benefits to operating utilities. This HTGR-GT Application Study documents the effort to evaluate the appropriateness of the HTGR-GT as an HTGR Lead Project. The scope of this effort included evaluation of the HTGR-GT technology, evaluation of potential HTGR-GT markets, assessment of the economics of commercial HTGR-GT plants, and evaluation of the program and expenditures necessary to establish HTGR-GT technology through the completion of the Lead Project.

  7. An evaluation on the antimicrobical properties of two disinfectants on dental high-speed instruments

    Directory of Open Access Journals (Sweden)

    Nejatidanesh F

    2003-08-01

    Full Text Available Statement of Problem: Rotary dental instruments (i-e. iow speed and high speed handpieces, due to"ninfection spread high potentiality, should be sterilized between dental visits for each patient. When a high"nspeed rotary instrument pauses at a high velocity, contaminated fluids like blood and saliva will be"nsucked into its tubes."nPurpose: The aim of this study was to compare the bactericidal effects ofDeconex 53 plus solution and"nthe solarsept spray on dental high- speed instruments."nMaterials and Methods: In this experimental study, one hundred and twenty (120 dental high- speed"nturbines, sterilized by autoclave, were divided into 6 groups. The turbines were contaminated with"nbacterial suspension. Streptococcus mutans, Staphilococcus aureus and Neisseria SP were the first"nmicrobial groups. Pseudomonas aruginosa was the second microbial group and Bacillus subtilis spore"nwas the third microbial group. After 5 minutes, three contaminated groups were placed in Deconex53"nplus 2% solution for 15 minutes. Three other groups after contamination were sprayed with Deconex"nsoiar sept spray for 2 minutes. Then the samples were placed in TSB culture and after 24 hours"nincubation at 37°, the samples were transmitted on blood agar solid culture for bacterial viability"nobservation. The results were observed after 24 hours incubation. Proportional test with normal"ndistribution was used for data analysis."nResults: The Deconex 53 plus had 85% disinfectant activity on the first microbial group, 10% on the"nsecond microbial group and 100% on the third microbial group. Also the solarsept spray had 30%"ndisinfectant activity on the first microbial group and 15% on the third micribial group . The solarsept"nspray had no bactericidal effect on turbines contaminated by the second microbial group. The results"nproved that the disinfectant effects of Deconex 53 plus solution for 15 minutes were significantly better"nthan the solarsept spray for 10 minutes

  8. Analysis of Unsteady Tip and Endwall Heat Transfer in a Highly Loaded Transonic Turbine Stage

    Science.gov (United States)

    Shyam, Vikram; Ameri, Ali; Chen, Jen-Ping

    2010-01-01

    In a previous study, vane-rotor shock interactions and heat transfer on the rotor blade of a highly loaded transonic turbine stage were simulated. The geometry consists of a high pressure turbine vane and downstream rotor blade. This study focuses on the physics of flow and heat transfer in the rotor tip, casing and hub regions. The simulation was performed using the Unsteady Reynolds-Averaged Navier-Stokes (URANS) code MSU-TURBO. A low Reynolds number k-epsilon model was utilized to model turbulence. The rotor blade in question has a tip gap height of 2.1 percent of the blade height. The Reynolds number of the flow is approximately 3x10(exp 6) per meter. Unsteadiness was observed at the tip surface that results in intermittent "hot spots". It is demonstrated that unsteadiness in the tip gap is governed by inviscid effects due to high speed flow and is not strongly dependent on pressure ratio across the tip gap contrary to published observations that have primarily dealt with subsonic tip flows. The high relative Mach numbers in the tip gap lead to a choking of the leakage flow that translates to a relative attenuation of losses at higher loading. The efficacy of new tip geometry is discussed to minimize heat flux at the tip while maintaining choked conditions. In addition, an explanation is provided that shows the mechanism behind the rise in stagnation temperature on the casing to values above the absolute total temperature at the inlet. It is concluded that even in steady mode, work transfer to the near tip fluid occurs due to relative shearing by the casing. This is believed to be the first such explanation of the work transfer phenomenon in the open literature. The difference in pattern between steady and time-averaged heat flux at the hub is also explained.

  9. Noise in the passenger cars of high-speed trains.

    Science.gov (United States)

    Hong, Joo Young; Cha, Yongwon; Jeon, Jin Yong

    2015-12-01

    The aim of this study is to investigate the effects of both room acoustic conditions and spectral characteristics of noises on acoustic discomfort in a high-speed train's passenger car. Measurement of interior noises in a high-speed train was performed when the train was operating at speeds of 100 km/h and 300 km/h. Acoustic discomfort caused by interior noises was evaluated by paired comparison methods based on the variation of reverberation time (RT) in a passenger car and the spectral differences in interior noises. The effect of RT on acoustic discomfort was not significant, whereas acoustic discomfort significantly varied depending on spectral differences in noise. Acoustic discomfort increased with increment of the sound pressure level (SPL) ratio at high frequencies, and variation in high-frequency noise components were described using sharpness. Just noticeable differences of SPL with low- and high-frequency components were determined to be 3.7 and 2.9 dB, respectively. This indicates that subjects were more sensitive to differences in SPLs at the high-frequency range than differences at the low-frequency range. These results support that, for interior noises, reduction in SPLs at high frequencies would significantly contribute to improved acoustic quality in passenger cars of high-speed trains.

  10. Adaptations to speed endurance training in highly trained soccer players

    DEFF Research Database (Denmark)

    Nyberg, Michael Permin; Fiorenza, Matteo; Lund, Anders

    2016-01-01

    PURPOSE: The present study examined whether a period of additional speed endurance training would improve intense intermittent exercise performance in highly trained soccer players during the season and whether the training changed aerobic metabolism and the level of oxidative enzymes in type I...... and II muscle fibers. METHODS: During the last nine weeks of the season, thirteen semi-professional soccer players performed additional speed endurance training sessions consisting of 2-3 sets of 8 - 10 repetitions of 30 m sprints with 10 s of passive recovery (SET). Before and after SET, subjects...... in type I and II fibers did not change. CONCLUSION: In highly trained soccer players, additional speed endurance training is associated with an improved ability to perform repeated high-intensity work. To what extent the training-induced changes in V˙O2 kinetics and mechanical efficiency in type I fibers...

  11. Novel high efficient speed sensorless controller for maximum power extraction from wind energy conversion systems

    International Nuclear Information System (INIS)

    Fathabadi, Hassan

    2016-01-01

    Highlights: • Novel sensorless MPPT technique without drawbacks of other sensor/sensorless methods. • Tracking the actual MPP of WECSs, no tracking the MPP of their wind turbines. • Actually extracting the highest output power from WECSs. • Novel MPPT technique having the MPPT efficiency more than 98.5% for WECSs. • Novel MPPT technique having short convergence time for WECSs. - Abstract: In this study, a novel high accurate sensorless maximum power point tracking (MPPT) method is proposed. The technique tracks the actual maximum power point of a wind energy conversion system (WECS) at which maximum output power is extracted from the system, not the maximum power point of its wind turbine at which maximum mechanical power is obtained from the turbine, so it actually extracts the highest output power from the system. The technique only uses input voltage and current of the converter used in the system, and neither needs any speed sensors (anemometer and tachometer) nor has the drawbacks of other sensor/sensorless based MPPT methods. The technique has been implemented as a MPPT controller by constructing a WECS. Theoretical results, the technique performance, and its advantages are validated by presenting real experimental results. The real static-dynamic response of the MPPT controller is experimentally obtained that verifies the proposed MPPT technique high accurately extracts the highest instant power from wind energy conversion systems with the MPPT efficiency of more than 98.5% and a short convergence time that is only 25 s for the constructed system having a total inertia and friction coefficient of 3.93 kg m 2 and 0.014 N m s, respectively.

  12. Stability control for high speed tracked unmanned vehicles

    Science.gov (United States)

    Pape, Olivier; Morillon, Joel G.; Houbloup, Philippe; Leveque, Stephane; Fialaire, Cecile; Gauthier, Thierry; Ropars, Patrice

    2005-05-01

    The French Military Robotic Study Program (introduced in Aerosense 2003), sponsored by the French Defense Procurement Agency and managed by Thales as the prime contractor, focuses on about 15 robotic themes which can provide an immediate "operational add-on value". The paper details the "automatic speed adjustment" behavior (named SYR4), developed by Giat Industries Company, which main goal is to secure the teleoperated mobility of high speed tracked vehicles on rough grounds; more precisely, the validated low level behavior continuously adjusts the vehicle speed taking into account the teleperator wish AND the maximum speed that the vehicle can manage safely according to the commanded radius of curvature. The algorithm is based on a realistic physical model of the ground-tracks relation, taking into account many vehicle and ground parameters (such as ground adherence and dynamic specificities of tracked vehicles). It also deals with the teleoperator-machine interface, providing a balanced strategy between both extreme behaviors: a) maximum speed reduction before initiating the commanded curve; b) executing the minimum possible radius without decreasing the commanded speed. The paper presents the results got from the military acceptance tests performed on tracked SYRANO vehicle (French Operational Demonstrator).

  13. Comprehensive surface treatment of high-speed steel tool

    Science.gov (United States)

    Fedorov, Sergey V.; Aleshin, Sergey V.; Swe, Min Htet; Abdirova, Raushan D.; Kapitanov, Alexey V.; Egorov, Sergey B.

    2018-03-01

    One of the promising directions of hardening of high-speed steel tool is the creation on their surface of the layered structures with the gradient of physic-chemical properties between the wear-resistant coatings to the base material. Among the methods of such surface modification, a special process takes place based on the use of pulsed high-intensity charged particle beams. The high speed of heating and cooling allows structural-phase transformations in the surface layer, which cannot be realized in a stationary mode. The treatment was conducted in a RITM-SP unit, which constitutes a combination of a source of low-energy high-current electron beams "RITM" and two magnetron spraying systems on a single vacuum chamber. The unit enables deposition of films on the surface of the desired product and subsequent liquid-phase mixing of materials of the film and the substrate by an intense pulse electron beam. The article discusses features of the structure of the subsurface layer of high-speed steel M2, modified by surface alloying of a low-energy high-current electron beam, and its effect on the wear resistance of the tool when dry cutting hard to machine Nickel alloy. A significant decrease of intensity of wear of high-speed steel with combined treatment happens due to the displacement of the zone of wear and decrease the radius of rounding of the cutting edge because of changes in conditions of interaction with the material being treated.

  14. High-speed measurement of firearm primer blast waves

    OpenAIRE

    Courtney, Michael; Daviscourt, Joshua; Eng, Jonathan; Courtney, Amy

    2012-01-01

    This article describes a method and results for direct high-speed measurements of firearm primer blast waves employing a high-speed pressure transducer located at the muzzle to record the blast pressure wave produced by primer ignition. Key findings are: 1) Most of the lead styphnate based primer models tested show 5.2-11.3% standard deviation in the magnitudes of their peak pressure. 2) In contrast, lead-free diazodinitrophenol (DDNP) based primers had standard deviations of the peak blast p...

  15. High-speed centrifugation induces aggregation of extracellular vesicles.

    Science.gov (United States)

    Linares, Romain; Tan, Sisareuth; Gounou, Céline; Arraud, Nicolas; Brisson, Alain R

    2015-01-01

    Plasma and other body fluids contain cell-derived extracellular vesicles (EVs), which participate in physiopathological processes and have potential biomedical applications. In order to isolate, concentrate and purify EVs, high-speed centrifugation is often used. We show here, using electron microscopy, receptor-specific gold labelling and flow cytometry, that high-speed centrifugation induces the formation of EV aggregates composed of a mixture of EVs of various phenotypes and morphologies. The presence of aggregates made of EVs of different phenotypes may lead to erroneous interpretation concerning the existence of EVs harbouring surface antigens from different cell origins.

  16. High-speed photodetectors in optical communication system

    Science.gov (United States)

    Zhao, Zeping; Liu, Jianguo; Liu, Yu; Zhu, Ninghua

    2017-12-01

    This paper presents a review and discussion for high-speed photodetectors and their applications on optical communications and microwave photonics. A detailed and comprehensive demonstration of high-speed photodetectors from development history, research hotspots to packaging technologies is provided to the best of our knowledge. A few typical applications based on photodetectors are also illustrated, such as free-space optical communications, radio over fiber and millimeter terahertz signal generation systems. Project supported by the Preeminence Youth Fund of China (No. 61625504).

  17. High-speed centrifugation induces aggregation of extracellular vesicles

    Directory of Open Access Journals (Sweden)

    Romain Linares

    2015-12-01

    Full Text Available Plasma and other body fluids contain cell-derived extracellular vesicles (EVs, which participate in physiopathological processes and have potential biomedical applications. In order to isolate, concentrate and purify EVs, high-speed centrifugation is often used. We show here, using electron microscopy, receptor-specific gold labelling and flow cytometry, that high-speed centrifugation induces the formation of EV aggregates composed of a mixture of EVs of various phenotypes and morphologies. The presence of aggregates made of EVs of different phenotypes may lead to erroneous interpretation concerning the existence of EVs harbouring surface antigens from different cell origins.

  18. Plasma-Assisted Chemistry in High-Speed Flow

    International Nuclear Information System (INIS)

    Leonov, Sergey B.; Yarantsev, Dmitry A.; Napartovich, Anatoly P.; Kochetov, Igor V.

    2007-01-01

    Fundamental problems related to the high-speed combustion are analyzed. The result of plasma-chemical modeling is presented as a motivation of experimental activity. Numerical simulations of the effect of uniform non-equilibrium discharge on the premixed hydrogen and ethylene-air mixture in supersonic flow demonstrate an advantage of such a technique over a heating. Experimental results on multi-electrode non-uniform discharge maintenance behind wallstep and in cavity of supersonic flow are presented. The model test on hydrogen and ethylene ignition is demonstrated at direct fuel injection to low-temperature high-speed airflow

  19. Miniature high speed compressor having embedded permanent magnet motor

    Science.gov (United States)

    Zhou, Lei (Inventor); Zheng, Liping (Inventor); Chow, Louis (Inventor); Kapat, Jayanta S. (Inventor); Wu, Thomas X. (Inventor); Kota, Krishna M. (Inventor); Li, Xiaoyi (Inventor); Acharya, Dipjyoti (Inventor)

    2011-01-01

    A high speed centrifugal compressor for compressing fluids includes a permanent magnet synchronous motor (PMSM) having a hollow shaft, the being supported on its ends by ball bearing supports. A permanent magnet core is embedded inside the shaft. A stator with a winding is located radially outward of the shaft. The PMSM includes a rotor including at least one impeller secured to the shaft or integrated with the shaft as a single piece. The rotor is a high rigidity rotor providing a bending mode speed of at least 100,000 RPM which advantageously permits implementation of relatively low-cost ball bearing supports.

  20. Magneto-optical system for high speed real time imaging

    Science.gov (United States)

    Baziljevich, M.; Barness, D.; Sinvani, M.; Perel, E.; Shaulov, A.; Yeshurun, Y.

    2012-08-01

    A new magneto-optical system has been developed to expand the range of high speed real time magneto-optical imaging. A special source for the external magnetic field has also been designed, using a pump solenoid to rapidly excite the field coil. Together with careful modifications of the cryostat, to reduce eddy currents, ramping rates reaching 3000 T/s have been achieved. Using a powerful laser as the light source, a custom designed optical assembly, and a high speed digital camera, real time imaging rates up to 30 000 frames per seconds have been demonstrated.

  1. High speed motion neutron radiography of dynamic events

    International Nuclear Information System (INIS)

    Robinson, A.H.; Barton, J.P.

    1983-01-01

    The development of a technique that permits neutron radiographic analysis of dynamic processes over a period lasting from one to ten milliseconds is described. The key to the technique is the use of a neutron pulse broad enough to span the duration of a brief event and intense enough to allow recording of the results on a high-speed movie film at frame rates of 10,000 frames/sec. Some typical application results in ballistic studies and two-phase flow are shown and discussed. The use of scintillator screens in the high-speed motion neutron radiography system is summarized and the statistical limitations of the technique are discussed

  2. 基于直流调速和实时组态的风力机模拟器设计%Design of Wind Turbine Simulator Based on DC Speed Control System and Real-Time Configuration Software

    Institute of Scientific and Technical Information of China (English)

    张计科; 王生铁; 刘广忱

    2013-01-01

    In order to meet the requirements of research on small-scale wind power generation system and improve reliability and development efficiency of software and hardware, the wind turbine simulator based on DC speed control system and real-time configuration environment was designed and implemented according to principle of standardized hardware and configurable software,and experiments were also done in this paper. Experimental results show that the wind turbine simulator not only can simulate accurately static output characteristics of a wind turbine and have good dynamic response so' as to behave almost the same as an actual wind turbine, but also can be configured and run to simulate off-line and run in realtime in MATLAB/Simulink environment,and has the merits of convenient model and parameters adjustment of wind turbine and wind speed as well as high software development efficiency. The wind turbine simulator presented in this paper has significant value for investigation on small wind power generation in a laboratory.%从研究小型风力发电系统需求出发,为了提高软硬件开发效率及可靠性,本着硬件标准化和软件组态化的原则,设计并实现了基于直流调速系统和实时组态环境的小型风力机模拟器,并进行了实验验证.实验结果表明,该风力机模拟器不但可以较为精准地模拟风力机的静态输出特性,动态响应好,达到不依赖于自然风资源而具有实际风力机特性的模拟效果,而且可以使离线仿真和在线运行统一在MATLAB/Simulink平台下组态和运行,风力机和风速模型及参数调整方便、软件开发效率高,对于实验室研究小型风力发电具有重要价值.

  3. In place chemical cleaning of Will County Unit 4 high pressure turbine for efficiency recovery

    International Nuclear Information System (INIS)

    Cloffi, S.J.

    1989-01-01

    Due to the proliferation of nuclear units and the economic penalties associated with nuclear unit's following load, the fossil industry has had to switch gears in their mode of operation. A fossil unit must be able to cycle on and off if it is to remain useful to system power supply. Furthermore, a fossil unit is indispensable if it can go to a low load at night and ramp up during the day to meet load demand. Despite the cautions, warnings, and lack of information from turbine and boiler manufactures, Will County Unit 4 achieved such minimum load operation in November 1987. Within the year, Unit 4 experienced numerous cycle chemistry upsets and a steady decline in turbine capability. In depth turbine testing coupled with the chemistry characteristics reveal the cause to be copper deposits on the second and third stages of the high pressure turbine. This paper details the investigation, remedial action, and possible solutions to this turbine capability problem

  4. Feature Tracking for High Speed AFM Imaging of Biopolymers.

    Science.gov (United States)

    Hartman, Brett; Andersson, Sean B

    2018-03-31

    The scanning speed of atomic force microscopes continues to advance with some current commercial microscopes achieving on the order of one frame per second and at least one reaching 10 frames per second. Despite the success of these instruments, even higher frame rates are needed with scan ranges larger than are currently achievable. Moreover, there is a significant installed base of slower instruments that would benefit from algorithmic approaches to increasing their frame rate without requiring significant hardware modifications. In this paper, we present an experimental demonstration of high speed scanning on an existing, non-high speed instrument, through the use of a feedback-based, feature-tracking algorithm that reduces imaging time by focusing on features of interest to reduce the total imaging area. Experiments on both circular and square gratings, as well as silicon steps and DNA strands show a reduction in imaging time by a factor of 3-12 over raster scanning, depending on the parameters chosen.

  5. Design, Fabrication, and Performance Test of a 100-W Helical-Blade Vertical-Axis Wind Turbine at Low Tip-Speed Ratio

    Directory of Open Access Journals (Sweden)

    Dowon Han

    2018-06-01

    Full Text Available A 100-W helical-blade vertical-axis wind turbine was designed, manufactured, and tested in a wind tunnel. A relatively low tip-speed ratio of 1.1 was targeted for usage in an urban environment at a rated wind speed of 9 m/s and a rotational speed of 170 rpm. The basic dimensions were determined through a momentum-based design method according to the IEC 61400-2 protocol. The power output was estimated by a mathematical model that takes into account the aerodynamic performance of the NACA0018 blade shape. The lift and drag of the blade with respect to the angle of attack during rotation were calculated using 2D computational fluid dynamics (CFD simulation to take into account stall region. The average power output calculated by the model was 108.34 W, which satisfies the target output of 100 W. The manufactured wind turbine was tested in a large closed-circuit wind tunnel, and the power outputs were measured for given wind speeds. At the design condition, the measured power output was 114.7 W, which is 5.9% higher than that of the mathematical model. This result validates the proposed design method and power estimation by the mathematical model.

  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. Development of High-Powered Steam Turbines by OAO NPO Central Research and Design Institute for Boilers and Turbines

    Science.gov (United States)

    Mikhailov, V. E.; Khomenok, L. A.; Kovalev, I. A.

    2018-01-01

    The article provides an overview of the developments by OAO NPO TsKTI aimed at improvement of components and assemblies of new-generation turbine plants for ultra-supercritical steam parameters to be installed at the power-generating facilities in service. The list of the assemblies under development includes cylinder shells, the cylinder's flow paths and rotors, seals, bearings, and rotor cooling systems. The authors consider variants of the shafting-cylinder configurations for which advanced high-pressure and intermediate-pressure cylinders with reactive blading and low-pressure cylinders of conventional design and with counter-current steam flows are proposed and high-pressure rotors, which can increase the economic efficiency and reduce the overall turbine plant dimensions. Materials intended for the equipment components that operate at high temperatures and a steam cooling technique that allows the use of cheaper steel grades owing to the reduction in the metal's working temperature are proposed. A new promising material for the bearing surfaces is described that enables the operation at higher unit pressures. The material was tested on a full-scale test bench at OAO NPO TsKTI and a turbine in operation. Ways of controlling the erosion of the blades in the moisture-steam turbine compartments by the steam heating of the hollow guide blades are considered. To ensure the dynamic stability of the shafting, shroud and diaphragm seals that prevent the development of the destabilizing circulatory forces of the steam flow were devised and trialed. Advanced instrumentation and software are proposed to monitor the condition of the blading and thermal stresses under transient conditions, to diagnose the vibration processes, and to archive the obtained data. Attention is paid to the normalization of the electromagnetic state of the plant in order to prevent the electrolytic erosion of the plant components. The instrumentation intended for monitoring the relevant electric

  8. Optimization of hydraulic turbine diffuser

    Directory of Open Access Journals (Sweden)

    Moravec Prokop

    2016-01-01

    Full Text Available Hydraulic turbine diffuser recovers pressure energy from residual kinetic energy on turbine runner outlet. Efficiency of this process is especially important for high specific speed turbines, where almost 50% of available head is utilized within diffuser. Magnitude of the coefficient of pressure recovery can be significantly influenced by designing its proper shape. Present paper focuses on mathematical shape optimization method coupled with CFD. First method is based on direct search Nelder-Mead algorithm, while the second method employs adjoint solver and morphing. Results obtained with both methods are discussed and their advantages/disadvantages summarized.

  9. A High-Speed Design of Montgomery Multiplier

    Science.gov (United States)

    Fan, Yibo; Ikenaga, Takeshi; Goto, Satoshi

    With the increase of key length used in public cryptographic algorithms such as RSA and ECC, the speed of Montgomery multiplication becomes a bottleneck. This paper proposes a high speed design of Montgomery multiplier. Firstly, a modified scalable high-radix Montgomery algorithm is proposed to reduce critical path. Secondly, a high-radix clock-saving dataflow is proposed to support high-radix operation and one clock cycle delay in dataflow. Finally, a hardware-reused architecture is proposed to reduce the hardware cost and a parallel radix-16 design of data path is proposed to accelerate the speed. By using HHNEC 0.25μm standard cell library, the implementation results show that the total cost of Montgomery multiplier is 130 KGates, the clock frequency is 180MHz and the throughput of 1024-bit RSA encryption is 352kbps. This design is suitable to be used in high speed RSA or ECC encryption/decryption. As a scalable design, it supports any key-length encryption/decryption up to the size of on-chip memory.

  10. Turbine airfoil cooling system with cooling systems using high and low pressure cooling fluids

    Science.gov (United States)

    Marsh, Jan H.; Messmann, Stephen John; Scribner, Carmen Andrew

    2017-10-25

    A turbine airfoil cooling system including a low pressure cooling system and a high pressure cooling system for a turbine airfoil of a gas turbine engine is disclosed. In at least one embodiment, the low pressure cooling system may be an ambient air cooling system, and the high pressure cooling system may be a compressor bleed air cooling system. In at least one embodiment, the compressor bleed air cooling system in communication with a high pressure subsystem that may be a snubber cooling system positioned within a snubber. A delivery system including a movable air supply tube may be used to separate the low and high pressure cooling subsystems. The delivery system may enable high pressure cooling air to be passed to the snubber cooling system separate from low pressure cooling fluid supplied by the low pressure cooling system to other portions of the turbine airfoil cooling system.

  11. High-speed imaging of explosive eruptions: applications and perspectives

    Science.gov (United States)

    Taddeucci, Jacopo; Scarlato, Piergiorgio; Gaudin, Damien; Capponi, Antonio; Alatorre-Ibarguengoitia, Miguel-Angel; Moroni, Monica

    2013-04-01

    Explosive eruptions, being by definition highly dynamic over short time scales, necessarily call for observational systems capable of relatively high sampling rates. "Traditional" tools, like as seismic and acoustic networks, have recently been joined by Doppler radar and electric sensors. Recent developments in high-speed camera systems now allow direct visual information of eruptions to be obtained with a spatial and temporal resolution suitable for the analysis of several key eruption processes. Here we summarize the methods employed to gather and process high-speed videos of explosive eruptions, and provide an overview of the several applications of these new type of data in understanding different aspects of explosive volcanism. Our most recent set up for high-speed imaging of explosive eruptions (FAMoUS - FAst, MUltiparametric Set-up,) includes: 1) a monochrome high speed camera, capable of 500 frames per second (fps) at high-definition (1280x1024 pixel) resolution and up to 200000 fps at reduced resolution; 2) a thermal camera capable of 50-200 fps at 480-120x640 pixel resolution; and 3) two acoustic to infrasonic sensors. All instruments are time-synchronized via a data logging system, a hand- or software-operated trigger, and via GPS, allowing signals from other instruments or networks to be directly recorded by the same logging unit or to be readily synchronized for comparison. FAMoUS weights less than 20 kg, easily fits into four, hand-luggage-sized backpacks, and can be deployed in less than 20' (and removed in less than 2', if needed). So far, explosive eruptions have been recorded in high-speed at several active volcanoes, including Fuego and Santiaguito (Guatemala), Stromboli (Italy), Yasur (Vanuatu), and Eyjafiallajokull (Iceland). Image processing and analysis from these eruptions helped illuminate several eruptive processes, including: 1) Pyroclasts ejection. High-speed videos reveal multiple, discrete ejection pulses within a single Strombolian

  12. 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

  13. Design of a 4 1/2 stage turbine with a stage loading factor of 4.66 and high specific work output

    Science.gov (United States)

    Webster, P. F.

    1976-01-01

    The aerodynamic design of a highly loaded multistage fan drive turbine is discussed. Turbine flowpath and airfoil sections are presented along with respective pressure and velocity distributions. Vibrational modes are identified in the expected turbine operating range.

  14. Assessment of Gearbox Operational Loads and Reliability under High Mean Wind Speeds

    DEFF Research Database (Denmark)

    Dabrowski, Dariusz; Natarajan, Anand

    2015-01-01

    wind turbine that operates in storm conditions with mean wind speeds less than 30 m/s is presented. In the study, normal shut-downs of a wind turbine in storm conditions were investigated. The analysis were conducted for two storm control strategies and different wind conditions from an extreme...... operating gust, normal turbulence model and extreme turbulence model. In the paper, loads in the planetary gear are quantified as well as the torsional moments in the main shaft. On the basis of simulation results the annual probability of failure of the gearbox in a wind turbine with soft storm controller...... is calculated, and compared with the one had the gearbox working in a wind turbine operating with hard storm controller. In the study, it was found that normal shut-downs do not have a significant influence on the ultimate loads in the gearbox, since they are related mostly to the gusts occurring during...

  15. Structural Reliability Aspects in Design of Wind Turbines

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard

    2007-01-01

    Reliability assessment, optimal design and optimal operation and maintenance of wind turbines are an area of significant interest for the fast growing wind turbine industry for sustainable production of energy. Offshore wind turbines in wind farms give special problems due to wake effects inside...... the farm. Reliability analysis and optimization of wind turbines require that the special conditions for wind turbine operation are taken into account. Control of the blades implies load reductions for large wind speeds and parking for high wind speeds. In this paper basic structural failure modes for wind...... turbines are described. Further, aspects are presented related to reliability-based optimization of wind turbines, assessment of optimal reliability level and operation and maintenance....

  16. High-speed photography application to pulsed hot plasma investigation

    International Nuclear Information System (INIS)

    Borov'etskij, M.; Koz'yarkevich, V.; Skrzhechanovskij, V.; Socha, R.

    1986-01-01

    Plasma focus is investigated using an electron-optical chamber for high-speed photography (KSK-1). Experimental devices for studying dynamics and structure of a plasma layer in the chosen interval, recording plasma spectra with time resolution as well as for studying the dynamics and structure of a plasma layer by Schlieren- and shadow methods are briefly described. Experimental results are presented

  17. Modelling Of Residual Stresses Induced By High Speed Milling Process

    International Nuclear Information System (INIS)

    Desmaison, Olivier; Mocellin, Katia; Jardin, Nicolas

    2011-01-01

    Maintenance processes used in heavy industries often include high speed milling operations. The reliability of the post-process material state has to be studied. Numerical simulation appears to be a very interesting way to supply an efficient residual stresses (RS) distribution prediction.Because the adiabatic shear band and the serrated chip shaping are features of the austenitic stainless steel high speed machining, a 2D high speed orthogonal cutting model is briefly presented. This finite element model, developed on Forge registered software, is based on data taken from Outeiro and al.'s paper [1]. A new behaviour law fully coupling Johnson-Cook's constitutive law and Latham and Cockcroft's damage model is detailed in this paper. It ensures results that fit those found in literature.Then, the numerical tools used on the 2D model are integrated to a 3D high speed milling model. Residual stresses distribution is analysed, on the surface and into the depth of the material. Various revolutions and passes of the two teeth hemispheric mill on the workpiece are simulated. Thus the sensitivity of the residual stresses generation to the cutting conditions can be discussed. In order to validate the 3D model, a comparison of the cutting forces measured by EDF R and D to those given by numerical simulations is achieved.

  18. Intel Legend and CERN would build up high speed Internet

    CERN Multimedia

    2002-01-01

    Intel, Legend and China Education and Research Network jointly announced on the 25th of April that they will be cooperating with each other to build up the new generation high speed internet, over the next three years (1/2 page).

  19. Visualization of Projectile Flying at High Speed in Dusty Atmosphere

    Science.gov (United States)

    Masaki, Chihiro; Watanabe, Yasumasa; Suzuki, Kojiro

    2017-10-01

    Considering a spacecraft that encounters particle-laden environment, such as dust particles flying up over the regolith by the jet of the landing thruster, high-speed flight of a projectile in such environment was experimentally simulated by using the ballistic range. At high-speed collision of particles on the projectile surface, they may be reflected with cracking into smaller pieces. On the other hand, the projectile surface will be damaged by the collision. To obtain the fundamental characteristics of such complicated phenomena, a projectile was launched at the velocity up to 400 m/s and the collective behaviour of particles around projectile was observed by the high-speed camera. To eliminate the effect of the gas-particle interaction and to focus on only the effect of the interaction between the particles and the projectile's surface, the test chamber pressure was evacuated down to 30 Pa. The particles about 400μm diameter were scattered and formed a sheet of particles in the test chamber by using two-dimensional funnel with a narrow slit. The projectile was launched into the particle sheet in the tangential direction, and the high-speed camera captured both projectile and particle motions. From the movie, the interaction between the projectile and particle sheet was clarified.

  20. Soliton-based ultra-high speed optical communications

    Indian Academy of Sciences (India)

    All these facts are the outcome of research on optical solitons in fibers in spite of the fact that the commonly used RZ format is not always called a soliton format. The overview presented here attempts to incorporate the role of soliton-based communications research in present day ultra-high speed communications.