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Sample records for providing reactive power

  1. A Tariff for Reactive Power

    Energy Technology Data Exchange (ETDEWEB)

    Kueck, John D [ORNL; Kirby, Brendan J [ORNL; Li, Fangxing [ORNL; Tufon, Christopher [Pacific Gas and Electric Company; Isemonger, Alan [California Independent System Operator

    2008-07-01

    Two kinds of power are required to operate an electric power system: real power, measured in watts, and reactive power, measured in volt-amperes reactive or VARs. Reactive power supply is one of a class of power system reliability services collectively known as ancillary services, and is essential for the reliable operation of the bulk power system. Reactive power flows when current leads or lags behind voltage. Typically, the current in a distribution system lags behind voltage because of inductive loads such as motors. Reactive power flow wastes energy and capacity and causes voltage droop. To correct lagging power flow, leading reactive power (current leading voltage) is supplied to bring the current into phase with voltage. When the current is in phase with voltage, there is a reduction in system losses, an increase in system capacity, and a rise in voltage. Reactive power can be supplied from either static or dynamic VAR sources. Static sources are typically transmission and distribution equipment, such as capacitors at substations, and their cost has historically been included in the revenue requirement of the transmission operator (TO), and recovered through cost-of-service rates. By contrast, dynamic sources are typically generators capable of producing variable levels of reactive power by automatically controlling the generator to regulate voltage. Transmission system devices such as synchronous condensers can also provide dynamic reactive power. A class of solid state devices (called flexible AC transmission system devices or FACTs) can provide dynamic reactive power. One specific device has the unfortunate name of static VAR compensator (SVC), where 'static' refers to the solid state nature of the device (it does not include rotating equipment) and not to the production of static reactive power. Dynamic sources at the distribution level, while more costly would be very useful in helping to regulate local voltage. Local voltage regulation would

  2. REACTIVE POWER COMPENSATOR WITH SMOOTH CONTROL

    Directory of Open Access Journals (Sweden)

    V. V. Burlaka

    2014-12-01

    Full Text Available Reactive power compensation devices are widely used: thyristor-control reactors (TCR and thyristor-switched capacitors (TSC. The TCR disadvantages are discussed. The TSC disadvantages are: influence of higher harmonics on nonsinusoidal voltage power system, the inability to ensure the smooth regulation. The proposed reactive power compensator consists of series with active filter and capacitors with step switch. Reactive power compensator’s control system is proposed. Hysteretic control of the inverter with current feedback is applied. DC-voltage regulator provides balance of active power. The control system allows overcompensation or undercompensation of reactive power modes. Reactive power distribution regulator performs the redistribution of power between switching capacitors and active filter. Minimization condition of this regulator is active filter’s power. Adjustment properties of reactive power compensator are analyzed. The choice of relations between the capacitors TSC steps to minimize the installed capacity of the active filter and the number of stages in TSC is considered. The approach that makes possible to «isolate» capacitors from harmonic currents and provide smooth control of reactive power is proposed

  3. Water reactive hydrogen fuel cell power system

    Science.gov (United States)

    Wallace, Andrew P; Melack, John M; Lefenfeld, Michael

    2014-11-25

    A water reactive hydrogen fueled power system includes devices and methods to combine reactant fuel materials and aqueous solutions to generate hydrogen. The generated hydrogen is converted in a fuel cell to provide electricity. The water reactive hydrogen fueled power system includes a fuel cell, a water feed tray, and a fuel cartridge to generate power for portable power electronics. The removable fuel cartridge is encompassed by the water feed tray and fuel cell. The water feed tray is refillable with water by a user. The water is then transferred from the water feed tray into the fuel cartridge to generate hydrogen for the fuel cell which then produces power for the user.

  4. Water reactive hydrogen fuel cell power system

    Science.gov (United States)

    Wallace, Andrew P; Melack, John M; Lefenfeld, Michael

    2014-01-21

    A water reactive hydrogen fueled power system includes devices and methods to combine reactant fuel materials and aqueous solutions to generate hydrogen. The generated hydrogen is converted in a fuel cell to provide electricity. The water reactive hydrogen fueled power system includes a fuel cell, a water feed tray, and a fuel cartridge to generate power for portable power electronics. The removable fuel cartridge is encompassed by the water feed tray and fuel cell. The water feed tray is refillable with water by a user. The water is then transferred from the water feed tray into a fuel cartridge to generate hydrogen for the fuel cell which then produces power for the user.

  5. Adaptive Compensation of Reactive Power With Shunt Active Power Filters

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Asiminoaei, Lucian; Hansen, Steffan

    2008-01-01

    This paper describes an adaptive method for compensating the reactive power with an active power filter (APF), which is initially rated for mitigation of only the harmonic currents given by a nonlinear industrial load. It is proven that, if the harmonic currents do not load the APF at the rated...... power, the available power can be used to provide a part of the required reactive power. Different indicators for designing such application are given, and it is proven that the proposed adaptive algorithm represents an added value to the APF. The algorithm is practically validated on a laboratory setup...... with a 7-kVA APF....

  6. Reactive power compensation a practical guide

    CERN Document Server

    Hofmann, Wolfgang; Just, Wolfgang

    2012-01-01

    The comprehensive resource on reactive power compensation, presenting the design, application and operation of reactive power equipment and installations The area of reactive power compensation is gaining increasing importance worldwide. If suitably designed, it is capable of improving voltage quality significantly, meaning that losses in equipment and power systems are reduced, the permissible loading of equipment can be increased, and the over-all stability of system operation improved. Ultimately, energy use and CO2 emisson are reduced. This unique guide discusses the

  7. Reactive power cost determination and allocation using generalized tracing methods

    Energy Technology Data Exchange (ETDEWEB)

    Kazemi, A.; Bashiri, S. [Iran Univ. of Science and Technology, Tehran (Iran, Islamic Republic of)

    2005-07-01

    A generalized tracing method was proposed for the allocation of standard 30 bus power system reactive power costs. Reactive power costs were divided into 2 parts: direct costs and opportunity costs. Generator opportunity costs were calculated using power flow calculations when no voltage limitation was applied to system buses. The cost of transformers with tap changers and the generating cost of reactive power via capacitor banks with switching facilities were considered. The cost of capacitor banks was calculated using the costs of generating reactive power through the capacitor bank, along with installation costs and consumption rates. The transmission line was classified based on the direction of reactive power flow. Generator domain was described as the set of buses which received generating power from the generators. Load domain was described as the set of buses in which power consumed by the load provided a path for power flow. A reactive power tracing algorithm was implemented on a 30 bus power system. The algorithm was able to determine the contribution of generators and loads and the contribution of each load on reactive power losses. Generator contributions were determined for each bus. The cost of reactive power was allocated by determined source and load contributions in each domain. It was concluded that the proposed method can be used to accurately allocate generation and transmission costs. 8 refs., 6 tabs., 5 figs.

  8. Reactive power management in electric power systems - A case ...

    African Journals Online (AJOL)

    The reactive power consumption by industrial plants and generation patterns in the Ethiopian Electric Light and Power Authority's (EELPA) system is critically evaluated. The flaws in the incentive mechanism for reactive power compensation are identified and recommendations made. Further, the voltage profile at the ...

  9. On Variable Reverse Power Flow-Part I: Active-Reactive Optimal Power Flow with Reactive Power of Wind Stations

    Directory of Open Access Journals (Sweden)

    Aouss Gabash

    2016-02-01

    Full Text Available It has recently been shown that using battery storage systems (BSSs to provide reactive power provision in a medium-voltage (MV active distribution network (ADN with embedded wind stations (WSs can lead to a huge amount of reverse power to an upstream transmission network (TN. However, unity power factors (PFs of WSs were assumed in those studies to analyze the potential of BSSs. Therefore, in this paper (Part-I, we aim to further explore the pure reactive power potential of WSs (i.e., without BSSs by investigating the issue of variable reverse power flow under different limits on PFs in an electricity market model. The main contributions of this work are summarized as follows: (1 Introducing the reactive power capability of WSs in the optimization model of the active-reactive optimal power flow (A-R-OPF and highlighting the benefits/impacts under different limits on PFs. (2 Investigating the impacts of different agreements for variable reverse power flow on the operation of an ADN under different demand scenarios. (3 Derivation of the function of reactive energy losses in the grid with an equivalent-π circuit and comparing its value with active energy losses. (4 Balancing the energy curtailment of wind generation, active-reactive energy losses in the grid and active-reactive energy import-export by a meter-based method. In Part-II, the potential of the developed model is studied through analyzing an electricity market model and a 41-bus network with different locations of WSs.

  10. Reactive Power Management in Electric Power Systems

    African Journals Online (AJOL)

    The quality of electric power at a supply point can be quantified in terms of how stab)e are the voltage and frequency and how close is the power factor to unity. The continuity of supply and in three-phase systems the degree to which the phase currents and voltages are balanced constitute additional quality parameters.

  11. APPLICATION OF MODIFIED POWER FLOW TRACING METHOD FOR REACTIVE POWER PRICING IN PRACTICAL UTILITY SYSTEM

    Directory of Open Access Journals (Sweden)

    M. SUSITHRA

    2017-01-01

    Full Text Available Competitive trend towards restructuring and unbundling of transmission services has resulted in the need to discover the impact of a particular generator to load. This paper initially presents the analysis of three different reactive power valuation methods namely, Modified Ybus , Virtual flow approach and modified power flow tracing to compute the reactive power output from a particular generator to particular load. Among these methods, the modified power flow electricity tracing method is identified as the best method to trace the reactive power contribution from various reactive power sources to loads, transmission line, etc. Also this proposed method breakdown the total reactive power loss in a transmission line into components to be allocated to individual loads. Secondly, based on this Method a novel allocation method for reactive power service for practical system is proposed. Hence, this method can be useful in providing additional insight into power system operation and can be used to modify existing tariffs of charging for reactive power transmission loss and reactive power transmission services. Simulation and comparison results are shown by taking WSCC 9 and IEEE 30 bus system as test system.

  12. Reactive power management of power networks with wind generation

    CERN Document Server

    Amaris, Hortensia; Ortega, Carlos Alvarez

    2012-01-01

    As the energy sector shifts and changes to focus on renewable technologies, the optimization of wind power becomes a key practical issue. Reactive Power Management of Power Networks with Wind Generation brings into focus the development and application of advanced optimization techniques to the study, characterization, and assessment of voltage stability in power systems. Recent advances on reactive power management are reviewed with particular emphasis on the analysis and control of wind energy conversion systems and FACTS devices. Following an introduction, distinct chapters cover the 5 key

  13. Power coefficient of reactivity in CANDU 6 Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Park, J. H. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Adams, R.; Boyle, S.; Connolly, A.; Kastanya, D.; Khaial, A.; Lau, V. [CANDU Energy Inc., Mississauga (Canada)

    2012-03-15

    The Power Coefficient of Reactivity (PCR) measures the change in reactor core reactivity per unit change in reactor power and is an integral quantity which captures the contributions of the fuel temperature, coolant void and coolant temperature reactivity feedbacks. All nuclear reactor designs provide a balance between the inherent nuclear characteristics and the engineered reactivity control features, to ensure that changes in reactivity in all operating conditions are maintained within a safe range. The CANDU reactor design takes advantage of the inherent nuclear characteristics of small reactivity coefficient, minimal excess reactivity and very long prompt neutron lifetime to mitigate the magnitude of the demand on the engineered systems for controlling reactivity. In particular, CANDU reactors have always taken advantage of the small value of the PCR associated with its design characteristics, such that the overall design of the reactor does not depend on the sign of the PCR. This is a contrast to other reactor design concepts which are dependent on a PCR which is both large and negative in the design of their engineered systems for controlling reactivity. It will be demonstrated that during a Loss of Regulation Control (LORC) event, the impact of having a positive power coefficient, or of hypothesizing a PCR larger than that estimated for CANDU, has no significant impact on the reactor safety. Since the CANDU 6 PCR is small, its role in the operation or safety of the reactor is not significant.

  14. Joint excitation and reactive power control in thermal power plant

    Directory of Open Access Journals (Sweden)

    Dragosavac Jasna

    2013-01-01

    Full Text Available The coordinated voltage and reactive power controller, designed for the thermal power plant, is presented in the paper. A brief explanation of the need for such device is given and justification for commissioning of such equipment is outlined. After short description of the theoretical background of the proposed control design, the achieved features of the commissioned equipment are fully given. Achieved performances are illustrated by recorded reactive power and bus voltage responses after commissioning of the described equipment into the largest thermal power plant in Serbia. As it can be seen in presented records, all design targets are met.

  15. Static reactive power compensators for high-voltage power systems. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1981-04-01

    A study conducted to summarize the role of static reactive power compensators for high voltage power system applications is described. This information should be useful to the utility system planning engineer in applying static var systems (SVS) to high voltage as (HVAC) systems. The static var system is defined as a form of reactive power compensator. The general need for reactive power compensation in HVAC systems is discussed, and the static var system is compared to other devices utilized to provide reactive power compensation. Examples are presented of applying SVS for specific functions, such as the prevention of voltage collapse. The operating principles of commercially available SVS's are discussed in detail. The perormance and active power loss characteristics of SVS types are compared.

  16. Multiagent voltage and reactive power control system

    Directory of Open Access Journals (Sweden)

    I. Arkhipov

    2014-12-01

    Full Text Available This paper is devoted to the research of multiagent voltage and reactive power control system development. The prototype of the system has been developed by R&D Center at FGC UES (Russia. The control system architecture is based on the innovative multiagent system theory application that leads to the achievement of several significant advantages (in comparison to traditional control systems implementation such as control system efficiency enhancement, control system survivability and cyber security.

  17. Optimal Reactive Power Dispatch Considering FACTS Devices

    Directory of Open Access Journals (Sweden)

    Ismail MAROUANI

    2011-06-01

    Full Text Available Because their capability to change the network parameters with a rapid response and enhanced flexibility, flexible AC transmission system (FACTS devices have taken more attention in power systems operations as improvement of voltage profile and minimizing system losses. In this way, this paper presents a multi-objective evolutionary algorithm (MOEA to solve optimal reactive power dispatch (ORPD problem with FACTS devices. This nonlinear multi-objective problem (MOP consists to minimize simultaneously real power loss in transmission lines and voltage deviation at load buses, by tuning parameters and searching the location of FACTS devices. The constraints of this MOP are divided to equality constraints represented by load flow equations and inequality constraints such as, generation reactive power sources and security limits at load buses. Two types of FACTS devices, static synchronous series compensator (SSSC and unified power flow controller (UPFC are considered. A comparative study regarding the effects of an SSSC and an UPFC on voltage deviation and total transmission real losses is carried out. The design problem is tested on a 6-bus system.

  18. Adaptive Reactive Power Control of PV Power Plants for Improved Power Transfer Capability under Ultra-Weak Grid Conditions

    DEFF Research Database (Denmark)

    Yang, Dongsheng; Wang, Xiongfei; Liu, Fangcheng

    2018-01-01

    the ultra-weak grid is significantly improved with the low PF operation. An adaptive reactive power droop control is next proposed to effectively distribute the reactive power demands to the individual inverters, and meanwhile maximize the power transfer capacity of the PV power plant. Simulation results......This paper analyzes the power transfer limitation of the PV power plant under the ultra-weak grid condition, i.e., when the Short-Circuit Ratio (SCR) is close to 1. It explicitly identifies that a minimum SCR of 2 is required for the PV power plant to deliver the rated active power when operating...... of a 200 MW PV power plant demonstrate that the proposed method can ensure the rated power transfer of PV power plant with the SCR of 1.25, provided that the PV inverters are operated with the minimal PF=0.9....

  19. Coordinated reactive power control to meet Quebec's interconnection requirements for wind power plants

    Energy Technology Data Exchange (ETDEWEB)

    El Itani, Samer; Dernbach, Matthias [REpower Systems SE (Germany). Applied Project Engineering; Williams, Stephen E.; Bishop, Martin T. [S and C Electric Company (United States). Power Quality Products Div.

    2012-07-01

    The 2 MW-class, DFIG-type wind turbine generator of REpower Systems constitutes a major portion of the wind power installations in Quebec. In collaboration with S and C Electric, a reactive power compensation and control strategy was developed to satisfy the interconnection requirements addressing reactive power and voltage control This paper demonstrates the proposed solution, which consists of local voltage control at the wind turbines, wind turbine reactive power coordination through the REpower Power Management Unit, substation based inverters, and the S and C DSTATCOM master plant-level control at the point of connection. Through time-domain simulations, the potential dynamic performance of the wind power plant is demonstrated under normal and faulted grid conditions, considering all system elements. The results show that the response of the wind plant to system voltage variations is fast, robust, and optimized with respect to the utilization of reactive power resources. The automatic voltage regulation system is capable of maintaining the voltage at the point of connection during normal operating conditions. Under fault conditions, extra reactive current is transiently released to the grid, thus providing indispensable support to the system voltage. (orig.)

  20. Guidelines for Distribution System Operators on Reactive Power Provision by Electric Vehicles in Low Voltage Grids

    DEFF Research Database (Denmark)

    Zecchino, Antonio; Marinelli, Mattia; Træholt, Chresten

    2017-01-01

    The increasing success of electric vehicles is bringing new technical challenges to power system operators. This work intends to provide guidelines for distribution system operators in terms of reactive power requirements when evaluating and authorizing electric vehicles supply equipment with fast...... the amount of reactive power that an individual electric vehicle is expected to provide when connected to a low voltage feeder, in order to benefit of the desired voltage rise effect in comparison to the case of unitary power factor....

  1. Secure provision of reactive power ancillary services in competitive electricity markets

    Science.gov (United States)

    El-Samahy, Ismael

    The research work presented in this thesis discusses various complex issues associated with reactive power management and pricing in the context of new operating paradigms in deregulated power systems, proposing appropriate policy solutions. An integrated two-level framework for reactive power management is set forth, which is both suitable for a competitive market and ensures a secure and reliable operation of the associated power system. The framework is generic in nature and can be adopted for any electricity market structure. The proposed hierarchical reactive power market structure comprises two stages: procurement of reactive power resources on a seasonal basis, and real-time reactive power dispatch. The main objective of the proposed framework is to provide appropriate reactive power support from service providers at least cost, while ensuring a secure operation of the power system. The proposed procurement procedure is based on a two-step optimization model. First, the marginal benefits of reactive power supply from each provider, with respect to system security, are obtained by solving a loadability-maximization problem subject to transmission security constraints imposed by voltage and thermal limits. Second, the selected set of generators is determined by solving an optimal power flow (OPF)-based auction. This auction maximizes a societal advantage function comprising generators' offers and their corresponding marginal benefits with respect to system security, and considering all transmission system constraints. The proposed procedure yields the selected set of generators and zonal price components, which would form the basis for seasonal contracts between the system operator and the selected reactive power service providers. The main objective of the proposed reactive power dispatch model is to minimize the total payment burden on the Independent System Operator (ISO), which is associated with reactive power dispatch. The real power generation is

  2. REACTIVE POWER DEVICES IN SYSTEMS OF ELECTRIC TRACTION

    Directory of Open Access Journals (Sweden)

    M. O. Kostin

    2010-04-01

    Full Text Available A comparative characteristic of different concepts and expressions for determination of reactive power in the circuits with non-sinusoidal electric values has been given. For the first Ukrainian electric locomotives of DE1 type with the system of DC electric traction, the values of reactive power after Budeany, Fryze, and also the differential, integral and generalized reactive powers have been determined. Some measures on reducing its consumption by the DC electric rolling stock have been suggested.

  3. Advanced Reactive Power Reserve Management Scheme to Enhance LVRT Capability

    Directory of Open Access Journals (Sweden)

    Hwanik Lee

    2017-10-01

    Full Text Available Abstract: To increase the utilization of wind power in the power system, grid integration standards have been proposed for the stable integration of large-scale wind power plants. In particular, fault-ride-through capability, especially Low-Voltage-Ride-Through (LVRT, has been emphasized, as it is related to tripping in wind farms. Therefore, this paper proposes the Wind power plant applicable-Effective Reactive power Reserve (Wa-ERPR, which combines both wind power plants and conventional generators at the Point of Interconnection (POI. The reactive power capability of the doubly-fed induction generator wind farm was considered to compute the total Wa-ERPR at the POI with reactive power capability of existing generators. By using the Wa-ERPR management algorithm, in case of a violation of the LVRT standards, the amount of reactive power compensation is computed using the Wa-ERPR management scheme. The proposed scheme calculates the Wa-ERPR and computes the required reactive power, reflecting the change of the system topology pre- and post-contingency, to satisfy the LVRT criterion when LVRT regulation is not satisfied at the POI. The static synchronous compensator (STATCOM with the capacity corresponding to calculated amount of reactive power through the Wa-ERPR management scheme is applied to the POI. Therefore, it is confirmed that the wind power plant satisfies the LVRT criteria by securing the appropriate reactive power at the POI, by applying of the proposed algorithm.

  4. 77 FR 24949 - Reactive Power Resources; Supplemental Notice Requesting Comments

    Science.gov (United States)

    2012-04-26

    ... requirements more broadly than to individual wind generators during the interconnection study process. At the... ] reactive power resources, including synchronous and asynchronous generation resources, transmission...

  5. Autonomous Active and Reactive Power Distribution Strategy in Islanded Microgrids

    DEFF Research Database (Denmark)

    Wu, Dan; Tang, Fen; Guerrero, Josep M.

    2014-01-01

    This paper proposes an autonomous active and reactive power distribution strategy that can be applied directly on current control mode (CCM) inverters, being compatible as well with conventional droop-controlled voltage control mode (VCM) converters. In a microgrid, since renewable energy sources...... (RES) units regulate different active power, the proposed reactive power distribution is adaptively controlled according to the active power distribution among energy storage systems (ESS) and RES units. The virtual impedance is implemented in order to improve the reactive power sharing...... in a distributed way. Real-time hardware-in-the-loop results are presented to verify the proposed control strategy....

  6. An Enhanced Islanding Microgrid Reactive Power, Imbalance Power, and Harmonic Power Sharing Scheme

    DEFF Research Database (Denmark)

    He, Jinwei; Lin, Yun Wei; Blaabjerg, Frede

    2015-01-01

    To address inaccurate power sharing problems in autonomous islanding microgrids, an enhanced droop control method through online virtual impedance adjustment is proposed. First, a term associated with DG reactive power, imbalance power, or harmonic power is added to the conventional real power......-frequency droop control. The transient real power variations caused by this term are captured to realize DG series virtual impedance tuning. With the regulation of DG virtual impedance at fundamental positive sequence, fundamental negative sequence, and harmonic frequencies, an accurate power sharing can...... unit local controllers. The feasibility of the proposed method is verified by simulated and experimental results from a low-power three-phase microgrid prototype....

  7. Assessment of the Economic Potential of Microgrids for Reactive Power Supply

    Energy Technology Data Exchange (ETDEWEB)

    Appen, Jan von; Marnay, Chris; Stadler, Michael; Momber, Ilan; Klapp, David; Scheven, Alexander von

    2011-05-01

    As power generation from variable distributed energy resources (DER) grows, energy flows in the network are changing, increasing the requirements for ancillary services, including voltage support. With the appropriate power converter, DER can provide ancillary services such as frequency control and voltage support. This paper outlines the economic potential of DERs coordinated in a microgrid to provide reactive power and voltage support at its point of common coupling. The DER Customer Adoption Model assesses the costs of providing reactive power, given local utility rules. Depending on the installed DER, the cost minimizing solution for supplying reactive power locally is chosen. Costs include the variable cost of the additional losses and the investment cost of appropriately over-sizing converters or purchasing capacitors. A case study of a large health care building in San Francisco is used to evaluate different revenue possibilities of creating an incentive for microgrids to provide reactive power.

  8. Reactive Power Capability of the Wind Turbine with Doubly Fed Induction Generator

    DEFF Research Database (Denmark)

    Tian, Jie; Su, Chi; Chen, Zhe

    2013-01-01

    of reactive power compensation, depending on the wind speed and the active power control strategy. This paper analyzes the reactive power capability of Doubly Fed Induction Generator (DFIG) based wind turbine, considering the rated stator current limit, the rated rotor current limit, the rated rotor voltage...... and reactive power compensation at the point of common coupling (PCC). Besides the shunt flexible alternating current transmission system (FACTS) devices such as the static var compensator (SVC) and the static synchronous compensator (STATCOM), the wind turbine itself can also provide a certain amount...... limit, and the reactive power capability of the grid side convertor (GSC). The boundaries of reactive power capability of DFIG based wind turbine are derived. The result was obtained using the software MATLAB....

  9. An accurate autonomous islanding microgrid reactive power, imbalance power and harmonic power sharing scheme

    DEFF Research Database (Denmark)

    He, Jinwei; Li, Yun Wei; Blaabjerg, Frede

    2013-01-01

    To address inaccurate power sharing problems in autonomous islanding microgrids, an enhanced droop control method through adaptive virtual impedance adjustment is proposed. First, a term associated with DG reactive power, imbalance power or harmonic power is added to the conventional real power......-frequency droop control. The transient real power variations caused by this additional term are captured to realize DG series virtual impedance tuning. With the regulation of DG virtual impedance at fundamental positive sequence, fundamental negative sequence, and harmonic frequencies, an accurate power sharing...

  10. Reactive power control with CHP plants - A demonstration

    DEFF Research Database (Denmark)

    Nyeng, Preben; Østergaard, Jacob; Andersen, Claus A.

    2010-01-01

    power rating of 7.3 MW on two synchronous generators. A closed-loop control is implemented, that remote controls the CHP plant to achieve a certain reactive power flow in a near-by substation. The solution communicates with the grid operator’s existing SCADA system to obtain measurements from......In this project the potential for ancillary services provision by distributed energy resources is investigated. Specifically, the provision of reactive power control by combined heat and power plants is examined, and the application of the new standard for DER communication systems, IEC 61850...... lines to underground cables has changed the reactive power balance, and third, the TSO has introduced restrictions in the allowed exchange of reactive power between the transmission system and distribution grids (known as the Mvar-arrangement). The demonstration includes a CHP plant with an electric...

  11. Coordinated reactive power management in power networks with wind turbines and FACTS devices

    Energy Technology Data Exchange (ETDEWEB)

    Amaris, Hortensia, E-mail: hamaris@ing.uc3m.e [University Carlos III of Madrid, Electrical Engineering Department, 28911 Leganes, Madrid (Spain); Alonso, Monica, E-mail: moalonso@ing.uc3m.e [University Carlos III of Madrid, Electrical Engineering Department, 28911 Leganes, Madrid (Spain)

    2011-07-15

    Highlights: {yields} Coordinated reactive power management among variable speed wind farms and static var compensator to improve the voltage stability in the network. {yields} Optimization formulation including the reactive power capability from double-fed induction generators (from the induction machine and the grid side converter). {yields} Application of genetic algorithm in power networks with wind farms. -- Abstract: Reactive power management is a critical issue when dealing with the planning and operation of power networks with high wind energy penetration. This paper is intended to introduce a coordinated Reactive Power Planning strategy among Doubly-Fed Induction Generator (DFIG) variable speed wind turbines and Flexible AC Transmission Systems (FACTS) devices. According to this strategy, the reactive power capability from DFIG wind turbines is obtained and the limitations on deliverable power are deduced for each operation point. Furthermore, instead of using the reactive power limit as it is traditionally done, the reactive power injection from Static Var Compensator (SVC) is related to the existing physical limits of the control variables. The optimization strategy is based on genetic algorithms and includes directly in its formulation both the reactive power capability from wind turbines and the reactive power injection from SVC units. An existing 140-bus power system is used to validate the performance and effectiveness of the proposed method.

  12. EVALUATING DEGREE OF ACTIVE POWER LOSSES REDUCTION IN THE ELECTRIC POWER LINES WITH REACTIVE POWER COMPENSATION

    Directory of Open Access Journals (Sweden)

    V. N. Radkevich

    2016-01-01

    Full Text Available The paper considers evaluation procedure for the degree of active power losses reduction in the power transmission lines under 1 kV and 6–10 kV of the systems of electric power supply of industrial enterprises with compensating installations mounted at the side of the customer. The capacitor installations conform to the applied voltage level and factor in dielectric losses in the capacitors. The voltage at the compensating device terminal changes from 0.95 to 1.05 of the capacitors nominal voltage. The study did not account for reactive power losses in the line, nor did it for its charge capacity, conditioned by relative shortness of the cable lines generally operating in the mains of industrial enterprises. For this reason, the quantities of reactive power being consumed and generated by the transmission line are negligible and do not significantly affect the reactive power flux. The researchers obtain functional relations that allow estimating the degree of power loss reduction in the transmission line factoring in its explicit initial data. They perform mathematical analysis of the obtained functional relations and study the function by means of derivatives. The function extremum points are found as well as the intervals of its increment and decrement. A graphical research of the obtained functional relation is performed. It is ascertained that reduction of the active power losses is contingent on the line and the capacitor-installation engineering factors, the electrical energy consumer reactive load value as well as the voltage applied to the capacitor installation. The functional relations presented in the article can be employed in scoping calculation necessary for decision making on the reactive power compensation in systems of the industrial facilities electric power supply. Their account will allow a more accurate estimate of technical and economic effect of the capacitor bank installation in the electrical mains under 1 kV and 6

  13. Thermal Behavior Optimization in Multi-MW Wind Power Converter by Reactive Power Circulation

    DEFF Research Database (Denmark)

    Zhou, Dao; Blaabjerg, Frede; Lau, Mogens

    2014-01-01

    for the conditions of constant wind speed and during wind gust. It is concluded that the thermal performance will be improved by injecting proper reactive power circulation within the wind turbine system, thereby being able to reduce the thermal cycling and enhance the reliability of the power converter.......The influence of actively controlled reactive power on the thermal behavior of multi-MW wind power converter with a Doubly-Fed Induction Generator (DFIG) is investigated. First, the allowable range of internal reactive power circulation is mapped depending on the DC-link voltage as well...... as the induction generator and power device capacity. Then, the effects of reactive power circulation on current characteristic and thermal distribution of the two-level back-to-back power converter are analyzed and compared. Finally, the thermal-oriented reactive power control method is introduced to the system...

  14. Reactive power influence on the thermal cycling of multi-MW wind power inverter

    DEFF Research Database (Denmark)

    Ma, Ke; Liserre, Marco; Blaabjerg, Frede

    2013-01-01

    In this paper the reactive power influence on the thermal cycling of power devices in grid-connected inverter for 10 MW wind turbines is investigated. Restrained by the grid codes, the allowable reactive power ranges in relation to amplitude and phase angle of the load current for a single...... converter system are first presented at different wind speeds. Furthermore, the interaction between paralleled converter systems in a wind park is also considered and analyzed. By controlling the reactive power circulated among paralleled converters, a new concept is then proposed to stabilize the thermal...... fluctuation of the power devices during wind gusts. It is concluded that the reactive power may change the thermal distribution of power devices. By properly controlling the reactive power, it is possible to achieve a more stable junction temperature in the power devices during the fluctuation of wind speed...

  15. Reactive power influence on the thermal cycling of multi-MW wind power inverter

    DEFF Research Database (Denmark)

    Ma, Ke; Liserre, Marco; Blaabjerg, Frede

    2012-01-01

    In this paper the reactive power influence on the thermal cycling of power devices in grid-connected inverter for 10 MW wind turbines is investigated. Restrained by the grid codes, the allowable reactive power ranges in relation to amplitude and phase angle of the load current for a single...... converter system are first presented at different wind speeds. Furthermore, the interaction between paralleled converter systems in a wind park is also considered and analyzed. By controlling the reactive power circulated among paralleled converters, a new concept is then proposed to stabilize the thermal...... fluctuation of the power devices during wind gusts. It is concluded that the reactive power may change the thermal distribution of power devices. By properly controlling the reactive power, it is possible to achieve a more stable junction temperature in the power devices during the fluctuation of wind speed...

  16. Coordination of baseload power plant group control with static reactive power compensator control

    Directory of Open Access Journals (Sweden)

    Zbigniew Szczerba

    2012-06-01

    Full Text Available Reactive power sources in power system nodes: generators and static reactive power compensators, are controlled by control systems. Generators – by generator node group controllers, compensators – by voltage controllers. The paper presents issues of these control systems’ coordination and proposals for its implementation.

  17. Reactive Power Injection Strategies for Single-Phase Photovoltaic Systems Considering Grid Requirements

    DEFF Research Database (Denmark)

    Yang, Yongheng; Wang, Huai; Blaabjerg, Frede

    2014-01-01

    like what the conventional power plants do today in the grid regulation participation. Requirements of ancillary services like Low-Voltage Ride-Through (LVRT) associated with reactive current injection and voltage support through reactive power control, have been in effectiveness in some countries, e.......g. Germany and Italy. Those advanced features can be provided by next generation PV systems, and will be enhanced in the future to ensure an even efficient and reliable utilization of PV systems. In light of this, Reactive Power Injection (RPI) strategies for single-phase PV systems are explored...

  18. Reactive Power Injection Strategies for Single-Phase Photovoltaic Systems Considering Grid Requirements

    DEFF Research Database (Denmark)

    Yang, Yongheng; Wang, Huai; Blaabjerg, Frede

    2014-01-01

    like what the conventional power plants do today in the grid regulation participation. Requirements of ancillary services like Low-Voltage Ride-Through (LVRT) associated with reactive current injection and voltage support through reactive power control, have been in effectiveness in some countries....... Those advanced features can be provided by next-generation PV systems, and will be enhanced in the future to ensure an even efficient and reliable utilization of PV systems. In the light of this, Reactive Power Injection (RPI) strategies for single-phase PV systems are explored in this paper. The RPI...

  19. A DFIG Islanding Detection Scheme Based on Reactive Power Infusion

    Science.gov (United States)

    Wang, M.; Liu, C.; He, G. Q.; Li, G. H.; Feng, K. H.; Sun, W. W.

    2017-07-01

    A lot of research has been done on photovoltaic (the “PV”) power system islanding detection in recent years. As a comparison, much less attention has been paid to islanding in wind turbines. Meanwhile, wind turbines can work in islanding conditions for quite a long period, which can be harmful to equipments and cause safety hazards. This paper presents and examines a double fed introduction generation (the “DFIG”) islanding detection scheme based on feedback of reactive power and frequency and uses a trigger signal of reactive power infusion which can be obtained by dividing the voltage total harmonic distortion (the "THD") by the voltage THD of last cycle to avoid the deterioration of power quality. This DFIG islanding detection scheme uses feedback of reactive power current loop to amplify the frequency differences in islanding and normal conditions. Simulation results show that the DFIG islanding detection scheme is effective.

  20. Optimized Reactive Power Flow of DFIG Power Converters for Better Reliability Performance Considering Grid Codes

    DEFF Research Database (Denmark)

    Zhou, Dao; Blaabjerg, Frede; Lau, Mogens

    2015-01-01

    and the current loading. Then an optimized reactive power flow is proposed in the case an over-excited reactive power support is applied with the joint compensation from both the rotor-side converter and the grid-side converter. Finally, some experimental validations are performed at a down-scale DFIG prototype......If there is no reactive power exchange between the Doubly-Fed Induction Generator (DFIG) and the grid, the various characteristics of the power converters in the DFIG wind turbine system cause the lifetime expectancy of the rotor-side converter significantly less than the grid-side converter....... In order to fulfill the modern grid codes, over-excited reactive power injection will further reduce the lifetime of the rotor-side converter. In this paper, the additional stress of the power semiconductor due to the reactive power injection is firstly evaluated in terms of modulation index...

  1. Guidelines for Distribution System Operators on Reactive Power Provision by Electric Vehicles in Low Voltage Grids

    DEFF Research Database (Denmark)

    Zecchino, Antonio; Marinelli, Mattia; Træholt, Chresten

    2017-01-01

    The increasing success of electric vehicles is bringing new technical challenges to power system operators. This work intends to provide guidelines for distribution system operators in terms of reactive power requirements when evaluating and authorizing electric vehicles supply equipment with fast...... the amount of reactive power that an individual electric vehicle is expected to provide when connected to a low voltage feeder, in order to benefit of the desired voltage rise effect in comparison to the case of unitary power factor....... charging capability in existing low voltage distribution feeders. The aim is to prevent the voltage to exceed the permitted values when charging at high power, by exploiting the effect of the reactive power. The proposed guidelines for distribution system operators are reported in a matrix, which indicates...

  2. Reactive power control with CHP plants - A demonstration

    DEFF Research Database (Denmark)

    Nyeng, Preben; Østergaard, Jacob; Andersen, Claus A.

    2010-01-01

    -7- 420, is investigated as a means to improve the control possibilities. To gain first-hand experience on the topic, a demonstration case has been designed and implemented in the project. The demonstration case is based on the issue of reactive power balancing in distribution grids, an issue...... that is attracting increasing attention from the distribution grid operators due to three main reasons, that all call for flexible reactive power control resources: First, the presence of DER, like wind turbines and CHP plants, makes the conditions less predictable, second, the intensive transform from overhead......In this project the potential for ancillary services provision by distributed energy resources is investigated. Specifically, the provision of reactive power control by combined heat and power plants is examined, and the application of the new standard for DER communication systems, IEC 61850...

  3. Ant colony search algorithm for optimal reactive power optimization

    Directory of Open Access Journals (Sweden)

    Lenin K.

    2006-01-01

    Full Text Available The paper presents an (ACSA Ant colony search Algorithm for Optimal Reactive Power Optimization and voltage control of power systems. ACSA is a new co-operative agents’ approach, which is inspired by the observation of the behavior of real ant colonies on the topic of ant trial formation and foraging methods. Hence, in the ACSA a set of co-operative agents called "Ants" co-operates to find good solution for Reactive Power Optimization problem. The ACSA is applied for optimal reactive power optimization is evaluated on standard IEEE, 30, 57, 191 (practical test bus system. The proposed approach is tested and compared to genetic algorithm (GA, Adaptive Genetic Algorithm (AGA.

  4. Thermal behavior optimization in multi-MW wind power converter by reactive power circulation

    DEFF Research Database (Denmark)

    Zhou, Dao; Blaabjerg, Frede; Lau, Mogens

    2013-01-01

    In the paper, an actively controlled reactive power influence to the thermal behavior of multi-MW wind power converter with Doubly-Fed Induction Generator (DFIG) is investigated. The allowable range of internal reactive power circulation is firstly mapped depending on the DC-link voltage as well ...... in the conditions of constant wind speed and during wind gust. It is concluded that the thermal performance will be improved by injecting proper reactive power circulation in the wind turbine system and thereby be able to reduce the thermal cycling and enhance the reliability.......In the paper, an actively controlled reactive power influence to the thermal behavior of multi-MW wind power converter with Doubly-Fed Induction Generator (DFIG) is investigated. The allowable range of internal reactive power circulation is firstly mapped depending on the DC-link voltage as well...... as the induction generator and power device capacity. Then the effects of reactive power circulation towards current characteristic and thermal distribution of the two-level back-to-back power converter is analyzed and compared. Finally the thermal-oriented reactive power is introduced to the system...

  5. Dynamic Reactive Power Control in Offshore HVDC Connected Wind Power Plants

    DEFF Research Database (Denmark)

    Sakamuri, Jayachandra N.; Cutululis, Nicolaos Antonio; Rather, Zakir Hussain

    2016-01-01

    This paper presents a coordinated reactive power control for a HVDC connected cluster of offshore wind power plants (WPPs). The reactive power reference for the WPP cluster is estimated by an optimization algorithm aiming at minimum active power losses in the offshore AC Grid. For each optimal......, such as wind turbine (WT) terminal, collector cable, and export cable, on the dynamic voltage profile of the offshore grid is investigated. Furthermore, the dynamic reactive power contribution from WTs from different WPPs of the cluster for such faults has also been studied....

  6. Reactive Power Pricing Model Considering the Randomness of Wind Power Output

    Science.gov (United States)

    Dai, Zhong; Wu, Zhou

    2018-01-01

    With the increase of wind power capacity integrated into grid, the influence of the randomness of wind power output on the reactive power distribution of grid is gradually highlighted. Meanwhile, the power market reform puts forward higher requirements for reasonable pricing of reactive power service. Based on it, the article combined the optimal power flow model considering wind power randomness with integrated cost allocation method to price reactive power. Meanwhile, considering the advantages and disadvantages of the present cost allocation method and marginal cost pricing, an integrated cost allocation method based on optimal power flow tracing is proposed. The model realized the optimal power flow distribution of reactive power with the minimal integrated cost and wind power integration, under the premise of guaranteeing the balance of reactive power pricing. Finally, through the analysis of multi-scenario calculation examples and the stochastic simulation of wind power outputs, the article compared the results of the model pricing and the marginal cost pricing, which proved that the model is accurate and effective.

  7. Dynamic Reactive Power Compensation of Large Scale Wind Integrated Power System

    DEFF Research Database (Denmark)

    Rather, Zakir Hussain; Chen, Zhe; Thøgersen, Paul

    2015-01-01

    wind turbines especially wind farms with additional grid support functionalities like dynamic support (e,g dynamic reactive power support etc.) and ii) refurbishment of existing conventional central power plants to synchronous condensers could be one of the efficient, reliable and cost effective option......Due to progressive displacement of conventional power plants by wind turbines, dynamic security of large scale wind integrated power systems gets significantly compromised. In this paper we first highlight the importance of dynamic reactive power support/voltage security in large scale wind...... integrated power systems with least presence of conventional power plants. Then we propose a mixed integer dynamic optimization based method for optimal dynamic reactive power allocation in large scale wind integrated power systems. One of the important aspects of the proposed methodology is that unlike...

  8. Reactive power optimization strategy considering analytical impedance ratio

    Science.gov (United States)

    Wu, Zhongchao; Shen, Weibing; Liu, Jinming; Guo, Maoran; Zhang, Shoulin; Xu, Keqiang; Wang, Wanjun; Sui, Jinlong

    2017-05-01

    In this paper, considering the traditional reactive power optimization cannot realize the continuous voltage adjustment and voltage stability, a dynamic reactive power optimization strategy is proposed in order to achieve both the minimization of network loss and high voltage stability with wind power. Due to the fact that wind power generation is fluctuant and uncertain, electrical equipments such as transformers and shunt capacitors may be operated frequently in order to achieve minimization of network loss, which affect the lives of these devices. In order to solve this problem, this paper introduces the derivation process of analytical impedance ratio based on Thevenin equivalent. Thus, the multiple objective function is proposed to minimize the network loss and analytical impedance ratio. Finally, taking the improved IEEE 33-bus distribution system as example, the result shows that the movement of voltage control equipment has been reduced and network loss increment is controlled at the same time, which proves the applicable value of this strategy.

  9. Voltage Stability Impact of Grid-Tied Photovoltaic Systems Utilizing Dynamic Reactive Power Control

    Science.gov (United States)

    Omole, Adedamola

    Photovoltaic (PV) DGs can be optimized to provide reactive power support to the grid, although this feature is currently rarely utilized as most DG systems are designed to operate with unity power factor and supply real power only to the grid. In this work, the voltage stability of a power system embedded with PV DG is examined in the context of the high reactive power requirement after a voltage sag or fault. A real-time dynamic multi-function power controller that enables renewable source PV DGs to provide the reactive power support necessary to maintain the voltage stability of the microgrid, and consequently, the wider power system is proposed. The loadability limit necessary to maintain the voltage stability of an interconnected microgrid is determined by using bifurcation analysis to test for the singularity of the network Jacobian and load differential equations with and without the contribution of the DG. The maximum and minimum real and reactive power support permissible from the DG is obtained from the loadability limit and used as the limiting factors in controlling the real and reactive power contribution from the PV source. The designed controller regulates the voltage output based on instantaneous power theory at the point-of-common coupling (PCC) while the reactive power supply is controlled by means of the power factor and reactive current droop method. The control method is implemented in a modified IEEE 13-bus test feeder system using PSCADRTM power system analysis software and is applied to the model of a Tampa ElectricRTM PV installation at Lowry Park Zoo in Tampa, FL. This dissertation accomplishes the systematic analysis of the voltage impact of a PV DG-embedded power distribution system. The method employed in this work bases the contribution of the PV resource on the voltage stability margins of the microgrid rather than the commonly used loss-of-load probability (LOLP) and effective load-carrying capability (ELCC) measures. The results of

  10. Reactive Power and Voltage Control of Offshore Wind Farms

    OpenAIRE

    Jerkø, Anders

    2014-01-01

    There are several challenges related to reactive power and voltage control of HVAC transmission from offshore wind farms to the main grid, which need to be addressed when designing wind farms. One challenge is the variation of wind speeds and thereby also power production, which can make it difficult to operate the system within the grid code requirements. This Master s thesis focuses on finding beneficial operating strategies to solve these challenges. Various locations of a static var compe...

  11. Local Dynamic Reactive Power for Correction of System Voltage Problems

    Energy Technology Data Exchange (ETDEWEB)

    Kueck, John D [ORNL; Rizy, D Tom [ORNL; Li, Fangxing [ORNL; Xu, Yan [ORNL; Li, Huijuan [University of Tennessee, Knoxville (UTK); Adhikari, Sarina [ORNL; Irminger, Philip [ORNL

    2008-12-01

    Distribution systems are experiencing outages due to a phenomenon known as local voltage collapse. Local voltage collapse is occurring in part because modern air conditioner compressor motors are much more susceptible to stalling during a voltage dip than older motors. These motors can stall in less than 3 cycles (.05s) when a fault, such as on the sub-transmission system, causes voltage to sag to 70 to 60%. The reasons for this susceptibility are discussed in the report. During the local voltage collapse, voltages are depressed for a period of perhaps one or two minutes. There is a concern that these local events are interacting together over larger areas and may present a challenge to system reliability. An effective method of preventing local voltage collapse is the use of voltage regulation from Distributed Energy Resources (DER) that can supply or absorb reactive power. DER, when properly controlled, can provide a rapid correction to voltage dips and prevent motor stall. This report discusses the phenomenon and causes of local voltage collapse as well as the control methodology we have developed to counter voltage sag. The problem is growing because of the use of low inertia, high efficiency air conditioner (A/C) compressor motors and because the use of electric A/C is growing in use and becoming a larger percentage of system load. A method for local dynamic voltage regulation is discussed which uses reactive power injection or absorption from local DER. This method is independent, rapid, and will not interfere with conventional utility system voltage control. The results of simulations of this method are provided. The method has also been tested at the ORNL s Distributed Energy Communications and Control (DECC) Laboratory using our research inverter and synchronous condenser. These systems at the DECC Lab are interconnected to an actual distribution system, the ORNL distribution system, which is fed from TVA s 161kV sub-transmission backbone. The test results

  12. Loss Minimizing Operation of Doubly Fed Induction Generator Based Wind Generation Systems Considering Reactive Power Provision

    DEFF Research Database (Denmark)

    Baohua, Zhang; Hu, Weihao; Chen, Zhe

    2014-01-01

    The paper deals with control techniques for minimizing the operating loss of doubly fed induction generator based wind generation systems when providing reactive power. The proposed method achieves its goal through controlling the rotor side q-axis current in the synchronous reference frame....... The formula for the control reference is explicitly deduced in this paper considering the losses of the generator, the power electronic devices and the filter. Three control strategies are compared with the proposed method under different wind speeds and different reactive power references. The simulation...

  13. Reactive power control methods for improved reliability of wind power inverters under wind speed variations

    DEFF Research Database (Denmark)

    Ma, Ke; Liserre, Marco; Blaabjerg, Frede

    2012-01-01

    method to relieve the thermal cycling of power switching devices under severe wind speed variations, by circulating reactive power among the parallel power converters in a WTS or among the WTS's in a wind park. The amount of reactive power is adjusted to limit the junction temperature fluctuation......The thermal cycling of power switching devices may lead to failures that compromise the reliability of power converters. Wind Turbine Systems (WTS) are especially subject to severe thermal cycling which may be caused by the wind speed variations or power grid faults. This paper proposes a control...... temperature fluctuation in the most stressed devices of 3L-NPC wind power inverter under severe wind speed variations can be significantly stabilized, and the reliability of the power converter can thereby be improved while the increased stress of the other devices in the same power converter...

  14. 77 FR 21555 - Reactive Power Resources; Supplemental Notice of Technical Conference

    Science.gov (United States)

    2012-04-10

    ... reactive power requirements more broadly than to individual wind generators during the interconnection... power requirements more broadly than to individual wind generators during the interconnection study... different types of reactive power resources, including synchronous and asynchronous generation resources...

  15. Interior Point Method Evaluation for Reactive Power Flow Optimization in the Power System

    Directory of Open Access Journals (Sweden)

    Zbigniew Lubośny

    2013-03-01

    Full Text Available The paper verifies the performance of an interior point method in reactive power flow optimization in the power system. The study was conducted on a 28 node CIGRE system, using the interior point method optimization procedures implemented in Power Factory software.

  16. Voltage Control in Distribution Systems Considered Reactive Power Output Sharing

    Science.gov (United States)

    Oshiro, Masato; Senjyu, Tomonobu; Yona, Atsushi; Urasaki, Naomitsu; Funabashi, Toshihisa

    In recent years, distributed generation (DG) and renewable energy source (RES) are attracting special attention to distribution systems. Renewable energy such as photovoltaic (PV) system and wind turbine generator are used as a source of clean energy. However, the large amount of distributed generation causes voltage deviation beyond a statutory range in distribution systems. This paper proposes a methodology for voltage control by using inverters interfaced with DG and tap changing transformers. In the proposed method a one-day schedule of voltage references for the control devices are determined by an optimization technique based on predicted values of load demand and PV power generation. Furthermore, decided reactive power output according to the locally measurable voltage based on droop characteristic. Slope and base value on droop characteristic are selected by fuzzy control. The proposed method accomplishes improvement against voltage distribution considered the reactive power output sharing and reduction of distribution loss. The effectiveness of the proposed method is verified by using MATLAB®.

  17. On the Sequential Control of ITER Poloidal Field Converters for Reactive Power Reduction

    Science.gov (United States)

    Yuan, Hongwen; Fu, Peng; Gao, Ge; Huang, Liansheng; Song, Zhiquan; He, Shiying; Wu, Yanan; Dong, Lin; Wang, Min; Fang, Tongzhen

    2014-12-01

    Sequential control applied to the International Thermonuclear Experimental Reactor (ITER) poloidal field converter system for the purpose of reactive power reduction is the subject of this investigation. Due to the inherent characteristics of thyristor-based phase-controlled converter, the poloidal field converter system consumes a huge amount of reactive power from the grid, which subsequently results in a voltage drop at the 66 kV busbar if no measure is taken. The installation of a static var compensator rated for 750 MVar at the 66 kV busbar is an essential way to compensate reactive power to the grid, which is the most effective measure to solve the problem. However, sequential control of the multi-series converters provides an additional method to improve the natural power factor and thus alleviate the pressure of reactive power demand of the converter system without any additional cost. In the present paper, by comparing with the symmetrical control technique, the advantage of sequential control in reactive power consumption is highlighted. Simulation results based on SIMULINK are found in agreement with the theoretical analysis.

  18. PROVIDING QUALITY OF ELECTRIC POWER IN ELECTRIC POWER SYSTEM IN PARALLEL OPERATION WITH WIND TURBINE

    Directory of Open Access Journals (Sweden)

    Yu. A. Rolik

    2016-01-01

    Full Text Available The problem of providing electric power quality in the electric power systems (EPS that are equipped with sufficiently long air or cable transmission lines is under consideration. This problem proved to be of particular relevance to the EPS in which a source of electrical energy is the generator of wind turbines since the wind itself is an instable primary energy source. Determination of the degree of automation of voltage regulation in the EPS is reduced to the choice of methods and means of regulation of power quality parameters. The concept of a voltage loss and the causes of the latter are explained by the simplest power system that is presented by a single-line diagram. It is suggested to regulate voltage by means of changing parameters of the network with the use of the method of reducing loss of line voltage by reducing its reactance. The latter is achieved by longitudinal capacitive compensation of the inductive reactance of the line. The effect is illustrated by vector diagrams of currents and voltages in the equivalent circuits of transmission lines with and without the use of longitudinal capacitive compensation. The analysis of adduced formulas demonstrated that the use of this method of regulation is useful only in the systems of power supply with a relatively low power factor (cosφ < 0.7 to 0.9. This power factor is typical for the situation of inclusion the wind turbine with asynchronous generator in the network since the speed of wind is instable. The voltage regulation fulfilled with the aid of the proposed method will make it possible to provide the required quality of the consumers’ busbars voltage in this situation. In is turn, it will make possible to create the necessary conditions for the economical transmission of electric power with the lowest outlay of reactive power and the lowest outlay of active power losses.

  19. Optimum Arrangement of Reactive Power Sources While Using Genetic Algori

    Directory of Open Access Journals (Sweden)

    A. M. Gashimov

    2010-01-01

    Full Text Available Reduction of total losses in distribution electricity supply network is considered as an important measure which serves for improvement of efficiency of electric power supply systems. This objective can be achieved by optimum distribution of reactive power sources in proper places of distribution electricity supply network. The proposed methodology is based on application of a genetic algorithm. Total expenses for installation of capacitor banks, their operation and also expenses related to electric power losses are considered as an efficiency function which is used for determination of places with optimum values of capacitor bank power. The methodology is the most efficient for selection of optimum places in the network where it is necessary to install capacitor banks with due account of their power control depending on a switched-on load value in the units.

  20. THE IMPACT OF POWER COEFFICIENT OF REACTIVITY ON CANDU 6 REACTORS

    Directory of Open Access Journals (Sweden)

    D. KASTANYA

    2013-10-01

    Full Text Available The combined effects of reactivity coefficients, along with other core nuclear characteristics, determine reactor core behavior in normal operation and accident conditions. The Power Coefficient of Reactivity (PCR is an aggregate indicator representing the change in reactor core reactivity per unit change in reactor power. It is an integral quantity which captures the contributions of the fuel temperature, coolant void, and coolant temperature reactivity feedbacks. All nuclear reactor designs provide a balance between their inherent nuclear characteristics and the engineered reactivity control features, to ensure that changes in reactivity under all operating conditions are maintained within a safe range. The CANDU® reactor design takes advantage of its inherent nuclear characteristics, namely a small magnitude of reactivity coefficients, minimal excess reactivity, and very long prompt neutron lifetime, to mitigate the demand on the engineered systems for controlling reactivity and responding to accidents. In particular, CANDU reactors have always taken advantage of the small value of the PCR associated with their design characteristics, such that the overall design and safety characteristics of the reactor are not sensitive to the value of the PCR. For other reactor design concepts a PCR which is both large and negative is an important aspect in the design of their engineered systems for controlling reactivity. It will be demonstrated that during Loss of Regulation Control (LORC and Large Break Loss of Coolant Accident (LBLOCA events, the impact of variations in power coefficient, including a hypothesized larger than estimated PCR, has no safety-significance for CANDU reactor design. Since the CANDU 6 PCR is small, variations in the range of values for PCR on the performance or safety of the reactor are not significant.

  1. The Impact of Power Coefficient of Reactivity on CANDU 6 Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Kastanya, D.; Boyle, S.; Hopwood, J. [Candu Energy Inc., Mississauga (Canada); Park, Joo Hwan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    The combined effects of reactivity coefficients, along with other core nuclear characteristics, determine reactor core behavior in normal operation and accident conditions. The Power Coefficient of Reactivity (PCR) is an aggregate indicator representing the change in reactor core reactivity per unit change in reactor power. It is an integral quantity which captures the contributions of the fuel temperature, coolant void, and coolant temperature reactivity feedbacks. All nuclear reactor designs provide a balance between their inherent nuclear characteristics and the engineered reactivity control features, to ensure that changes in reactivity under all operating conditions are maintained within a safe range. The CANDU reactor design takes advantage of its inherent nuclear characteristics, namely a small magnitude of reactivity coefficients, minimal excess reactivity, and very long prompt neutron lifetime, to mitigate the demand on the engineered systems for controlling reactivity and responding to accidents. In particular, CANDU reactors have always taken advantage of the small value of the PCR associated with their design characteristics, such that the overall design and safety characteristics of the reactor are not sensitive to the value of the PCR. For other reactor design concepts a PCR which is both large and negative is an important aspect in the design of their engineered systems for controlling reactivity. It will be demonstrated that during Loss of Regulation Control (LORC) and Large Break Loss of Coolant Accident (LBLOCA) events, the impact of variations in power coefficient, including a hypothesized larger than estimated PCR, has no safety-significance for CANDU reactor design. Since the CANDU 6 PCR is small, variations in the range of values for PCR on the performance or safety of the reactor are not significant.

  2. Sliding mode active and reactive power decoupled control for Distributed Power Flow Controllers

    OpenAIRE

    Martins, I m; Silva, F. A.; Pinto, S. F.; Martins, I. E.

    2014-01-01

    Unified Power Flow Controllers (UPFC) are one of the most useful Flexible AC Transmission Systems (FACTS). They can be used for power flow control in AC transmission grids, allowing simultaneous control of the bus voltage and line active and reactive power. However, due to high costs and reliability concerns, UPFCs have experimented limited use in such applications. Recently, the concepts of Distributed FACTS (DFACTS) and Distributed Power Flow Controller (DPFC) have been introduced as a low ...

  3. Wolf Search Algorithm for Solving Optimal Reactive Power Dispatch Problem

    Directory of Open Access Journals (Sweden)

    Kanagasabai Lenin

    2015-03-01

    Full Text Available This paper presents a new bio-inspired heuristic optimization algorithm called the Wolf Search Algorithm (WSA for solving the multi-objective reactive power dispatch problem. Wolf Search algorithm is a new bio – inspired heuristic algorithm which based on wolf preying behaviour. The way wolves search for food and survive by avoiding their enemies has been imitated to formulate the algorithm for solving the reactive power dispatches. And the speciality  of wolf is  possessing  both individual local searching ability and autonomous flocking movement and this special property has been utilized to formulate the search algorithm .The proposed (WSA algorithm has been tested on standard IEEE 30 bus test system and simulation results shows clearly about the good performance of the proposed algorithm .

  4. Study on Optimization Strategy for Voltage and Reactive Power Control of Wind Farm

    Science.gov (United States)

    Lu, Q.; Shi, L.; Chen, N.

    A method for calculating reactive power limit of wind farm comprised of doubly-fed induction generators (DFIG) is proposed. The reactive power limit of wind farm is the sum of reactive power limit of DFIGs which is calculated by the method considering static stability margin. Based on this, reactive power control of wind farm is discussed and proposed. The proposed reactive power control is divided into different control modes according to power factor of high voltage side in wind farm substation and voltage of low voltage side in point of interconnection(POI). In different control modes, different control objects are applied on reactive power regulation. After reactive power regulation is finished, some reactive power of wind farm should be released. At last, numerical test system is established, the result shows that the proposed method is effective to support voltage of POI

  5. Reactive Power Optimization with SVC & TCSC using Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Biplab Bhattacharyya

    2014-01-01

    Full Text Available In this paper Genetic Algorithm (GA is used as an evolutionary tecthniques for the optimal placement of flexible AC transmission systems (FACTS devices in an interconnected power system. Here two types of FACTS devices has been discussed nemely, Thyristor Controlled Series Capacitor (TCSC and Static Var Compensator (SVC for the economic operation and to reduce the transmission loss. Reactively loading of the system is taken from base to 200% of base loading and the system performance is observed without and with FACTS devices. Optimal placement of FACTS devices in the system is determined by calculating active and reactive power flow in lines. FACTS devices along with reactive generation of generators and transformer tap setting are used for the power transfer capacity using GA. The proposed approach is applied on IEEE 14 and IEEE 30-bus test systems. Finally the effectiveness of the proposed GA based method of placement of FACTS devices is established by comparing the results with another standard method of optimization like Particle Swarm Optimization (PSO technique.

  6. Reactive power interconnection requirements for PV and wind plants : recommendations to NERC.

    Energy Technology Data Exchange (ETDEWEB)

    McDowell, Jason (General Electric, Schenectady, NY); Walling, Reigh (General Electric, Schenectady, NY); Peter, William (SunPower, Richmond, CA); Von Engeln, Edi (NV Energy, Reno, NV); Seymour, Eric (AEI, Fort Collins, CO); Nelson, Robert (Siemens Wind Turbines, Orlando, FL); Casey, Leo (Satcon, Boston, MA); Ellis, Abraham; Barker, Chris. (SunPower, Richmond, CA)

    2012-02-01

    Voltage on the North American bulk system is normally regulated by synchronous generators, which typically are provided with voltage schedules by transmission system operators. In the past, variable generation plants were considered very small relative to conventional generating units, and were characteristically either induction generator (wind) or line-commutated inverters (photovoltaic) that have no inherent voltage regulation capability. However, the growing level of penetration of non-traditional renewable generation - especially wind and solar - has led to the need for renewable generation to contribute more significantly to power system voltage control and reactive power capacity. Modern wind-turbine generators, and increasingly PV inverters as well, have considerable dynamic reactive power capability, which can be further enhanced with other reactive support equipment at the plant level to meet interconnection requirements. This report contains a set of recommendations to the North-America Electricity Reliability Corporation (NERC) as part of Task 1-3 (interconnection requirements) of the Integration of Variable Generation Task Force (IVGTF) work plan. The report discusses reactive capability of different generator technologies, reviews existing reactive power standards, and provides specific recommendations to improve existing interconnection standards.

  7. A Hierarchical Modeling for Reactive Power Optimization With Joint Transmission and Distribution Networks by Curve Fitting

    DEFF Research Database (Denmark)

    Ding, Tao; Li, Cheng; Huang, Can

    2017-01-01

    function of the slave model for the master model, which reflects the impacts of each slave model. Second, the transmission and distribution networks are decoupled at feeder buses, and all the distribution networks are coordinated by the master reactive power optimization model to achieve the global......In order to solve the reactive power optimization with joint transmission and distribution networks, a hierarchical modeling method is proposed in this paper. It allows the reactive power optimization of transmission and distribution networks to be performed separately, leading to a master......–slave structure and improves traditional centralized modeling methods by alleviating the big data problem in a control center. Specifically, the transmission-distribution-network coordination issue of the hierarchical modeling method is investigated. First, a curve-fitting approach is developed to provide a cost...

  8. Distributed Optimal Control of Reactive Power and Voltage in Islanded Microgrids

    DEFF Research Database (Denmark)

    Wang, Yanbo; Wang, Xiongfei; Chen, Zhe

    2017-01-01

    This paper presents a distributed optimal control strategy for islanded microgrids, which allows to perform reactive power sharing and voltage regulation without using communication system. To perform the twofold objectives, a small signal model is first developed to reconstruct the system input...... performance of the optimal controller is analyzed, from which the guideline for choosing controller parameters is formulated. The results obtained from sensitivity analysis, simulations and experiments show that the proposed approach provides the expected reliability and flexibility for optimizing......-output relationship, which is evaluated through sensitivity analysis. A state estimator is then constructed to observe reactive power distribution and system voltages by local measurement. An optimal regulator is developed to perform both reactive power sharing and system voltage restoration. And the dynamic...

  9. Distributed Optimal Control of Reactive Power and Voltage in Islanded Microgrids

    DEFF Research Database (Denmark)

    Wang, Yanbo; Wang, Xiongfei; Chen, Zhe

    2016-01-01

    The paper proposes a distributed optimal control strategy for islanded microgrids, which allows to perform reactive power sharing and voltage regulation without communication system. To realize the twofold objective, an improved small signal model is developed first to reconstruct the system input...... power sharing and system voltage restoration. And the dynamic performance of the optimal controller is analyzed, from which the guideline for choosing controller parameters is formulated. The results obtained from sensitivity analysis, simulations and experiments show that the proposed approach provides......-output relationship, where the relationship is evaluated with sensitivity analysis. A state estimator is then constructed based on the new input-output relationship in order to observe reactive power distribution and system voltages by local measurement. An optimal regulator is developed to perform both reactive...

  10. A Hybrid Optimization Method for Reactive Power and Voltage Control Considering Power Loss Minimization

    DEFF Research Database (Denmark)

    Liu, Chengxi; Qin, Nan; Bak, Claus Leth

    2015-01-01

    This paper proposes a hybrid optimization method to optimally control the voltage and reactive power with minimum power loss in transmission grid. This approach is used for the Danish automatic voltage control (AVC) system which is typically a non-linear non-convex problem mixed with both...

  11. Static reactive power compensation for the pulse power supply plant of the CERN booster

    CERN Document Server

    Jahn, K; Schluter, W

    1975-01-01

    If pulse power supplies with high-capacity static converters are connected directly to an 18 kV network without any special compensation measures being adopted, certain problems must be overcome. The article describes a new reactive-power compensation system in detail, a number of oscillograms being used to illustrate the results obtained. The system is also suitable for use in metallurgical plants and rolling mills where there are large fluctuations in the reactive power, and in steelworks for working in parallel with electric arc furnaces. (2 refs).

  12. IDLING AND NATURAL POWER TRANSFER LOSS SAVING BY MEANS OF SHUNT REACTORS AND REACTIVE POWER SOURCES

    Directory of Open Access Journals (Sweden)

    Patsiuk V.I

    2009-04-01

    Full Text Available The closed formulas for definition of the steady–state values of voltages, currents, active and reactive power in a line with the distributed and lumped constants are shown. The influence of the shunt reactors and reactive power sources in the form of capacitor banks on losses of idling with various wave lengths is investigated. For the half-wave transmissions line the optimal parameters (which allow increasing of the output during the natural-power transfer of the shunt reactors were obtained.

  13. The Assessment of Working Conditions of Traction Substation for Power and Reactive Energy

    Directory of Open Access Journals (Sweden)

    Zbigniew Lukasik

    2008-01-01

    Full Text Available In this paper, problems concerning the management of reactive power of DC traction substation have been discussed. The structure of traction system and its main elements has been sketched. Reactive power issue with respect to rectifier sets has been presented. The case of generating reactive power of capacitive character in the traction supplying systemand taken precautions has been also described.

  14. A Preliminary Analysis of the Economics of Using Distributed Energy as a Source of Reactive Power Supply

    Energy Technology Data Exchange (ETDEWEB)

    Li, Fangxing [ORNL; Kueck, John D [ORNL; Rizy, D Tom [ORNL; King, Thomas F [ORNL

    2006-04-01

    A major blackout affecting 50 million people in the Northeast United States, where insufficient reactive power supply was an issue, and an increased number of filings made to the Federal Energy Regulatory Commission by generators for reactive power has led to a closer look at reactive power supply and compensation. The Northeastern Massachusetts region is one such area where there is an insufficiency in reactive power compensation. Distributed energy due to its close proximity to loads seems to be a viable option for solving any present or future reactive power shortage problems. Industry experts believe that supplying reactive power from synchronized distributed energy sources can be 2 to 3 times more effective than providing reactive support in bulk from longer distances at the transmission or generation level. Several technology options are available to supply reactive power from distributed energy sources such as small generators, synchronous condensers, fuel cells or microturbines. In addition, simple payback analysis indicates that investments in DG to provide reactive power can be recouped in less than 5 years when capacity payments for providing reactive power are larger than $5,000/kVAR and the DG capital and installation costs are lower than $30/kVAR. However, the current institutional arrangements for reactive power compensation present a significant barrier to wider adoption of distributed energy as a source of reactive power. Furthermore, there is a significant difference between how generators and transmission owners/providers are compensated for reactive power supplied. The situation for distributed energy sources is even more difficult, as there are no arrangements to compensate independent DE owners interested in supplying reactive power to the grid other than those for very large IPPs. There are comparable functionality barriers as well, as these smaller devices do not have the control and communications requirements necessary for automatic

  15. Compensation of Reactive Power from Wind Turbines with Power Electronics Equipment

    DEFF Research Database (Denmark)

    Pedersen, Jørgen Kaas

    1996-01-01

    that the supply line must deliver the reactive current with ensuing losses, the strong variation also will cause varying inductive voltage losses in the supply with flicker as a consequence. With power electronic equipment it is possible to produce the reactive power on location and reduce the losses and voltage....... Commissioning of the compensator is planned to January 1997. The compensator is a result of an EU-project with participation of SIEMENS (D), who is constructing the compensator, ELSAM (DK), SH (DK), UMIST (UK) and DTU (DK)....

  16. Probabilistic Approach to Optimizing Active and Reactive Power Flow in Wind Farms Considering Wake Effects

    Directory of Open Access Journals (Sweden)

    Yong-Cheol Kang

    2013-10-01

    Full Text Available This paper presents a novel probabilistic optimization algorithm for simultaneous active and reactive power dispatch in power systems with significant wind power integration. Two types of load and wind-speed uncertainties have been assumed that follow normal and Weibull distributions, respectively. A PV bus model for wind turbines and the wake effect for correlated wind speed are used to achieve accurate AC power flow analysis. The power dispatch algorithm for a wind-power integrated system is modeled as a probabilistic optimal power flow (P-OPF problem, which is operated through fixed power factor control to supply reactive power. The proposed P-OPF framework also considers emission information, which clearly reflects the impact of the energy source on the environment. The P-OPF was tested on a modified IEEE 118-bus system with two wind farms. The results show that the proposed technique provides better system operation performance evaluation, which is helpful in making decisions about power system optimal dispatch under conditions of uncertainty.

  17. Basic study on dynamic reactive-power control method with PV output prediction for solar inverter

    Directory of Open Access Journals (Sweden)

    Ryunosuke Miyoshi

    2016-01-01

    Full Text Available To effectively utilize a photovoltaic (PV system, reactive-power control methods for solar inverters have been considered. Among the various methods, the constant-voltage control outputs less reactive power compared with the other methods. We have developed a constant-voltage control to reduce the reactive-power output. However, the developed constant-voltage control still outputs unnecessary reactive power because the control parameter is constant in every waveform of the PV output. To reduce the reactive-power output, we propose a dynamic reactive-power control method with a PV output prediction. In the proposed method, the control parameter is varied according to the properties of the predicted PV waveform. In this study, we performed numerical simulations using a distribution system model, and we confirmed that the proposed method reduces the reactive-power output within the voltage constraint.

  18. Secondary Control for Reactive Power Sharing in Droop-Controlled Islanded MicroGrids

    DEFF Research Database (Denmark)

    Micallef, A.; Apap, M.; Spiteri-Staines, C.

    2012-01-01

    , droop control has real and reactive power sharing limitations when there are mismatches between the microsources. This paper analyses the effect due to mismatches in the power line impedances connecting the source inverters to the microgrid. From the simulations results obtained, it was shown...... that the reactive power demand is unequally shared between the microsource inverters when there are mismatches between the power line impedances. To achieve equal reactive power sharing between the inverters, an external loop requiring low bandwidth communications was implemented in a central controller. Simulation...... results are presented showing the feasibility of the proposed solution in achieving reactive power sharing between the inverters connected to the microgrid....

  19. Tutorial: Reactive high power impulse magnetron sputtering (R-HiPIMS)

    Science.gov (United States)

    Anders, André

    2017-05-01

    High Power Impulse Magnetron Sputtering (HiPIMS) is a coating technology that combines magnetron sputtering with pulsed power concepts. By applying power in pulses of high amplitude and a relatively low duty cycle, large fractions of sputtered atoms and near-target gases are ionized. In contrast to conventional magnetron sputtering, HiPIMS is characterized by self-sputtering or repeated gas recycling for high and low sputter yield materials, respectively, and both for most intermediate materials. The dense plasma in front of the target has the dual function of sustaining the discharge and providing plasma-assistance to film growth, affecting the microstructure of growing films. Many technologically interesting thin films are compound films, which are composed of one or more metals and a reactive gas, most often oxygen or nitrogen. When reactive gas is added, non-trivial consequences arise for the system because the target may become "poisoned," i.e., a compound layer forms on the target surface affecting the sputtering yield and the yield of secondary electron emission and thereby all other parameters. It is emphasized that the target state depends not only on the reactive gas' partial pressure (balanced via gas flow and pumping) but also on the ion flux to the target, which can be controlled by pulse parameters. This is a critical technological opportunity for reactive HiPIMS (R-HiPIMS). The scope of this tutorial is focused on plasma processes and mechanisms of operation and only briefly touches upon film properties. It introduces R-HiPIMS in a systematic, step-by-step approach by covering sputtering, magnetron sputtering, reactive magnetron sputtering, pulsed reactive magnetron sputtering, HiPIMS, and finally R-HiPIMS. The tutorial is concluded by considering variations of R-HiPIMS known as modulated pulsed power magnetron sputtering and deep-oscillation magnetron sputtering and combinations of R-HiPIMS with superimposed dc magnetron sputtering.

  20. Electrical engineering unit for the reactive power control of the load bus at the voltage instability

    Science.gov (United States)

    Kotenev, A. V.; Kotenev, V. I.; Kochetkov, V. V.; Elkin, D. A.

    2018-01-01

    For the purpose of reactive power control error reduction and decrease of the voltage sags in the electric power system caused by the asynchronous motors started the mathematical model of the load bus was developed. The model was built up of the sub-models of the following elements: a transformer, a transmission line, a synchronous and an asynchronous loads and a capacitor bank load, and represents the automatic reactive power control system taking into account electromagnetic processes of the asynchronous motors started and reactive power changing of the electric power system elements caused by the voltage fluctuation. The active power/time and reactive power/time characteristics based on the recommended procedure of the equivalent electric circuit parameters calculation were obtained. The derived automatic reactive power control system was shown to eliminate the voltage sags in the electric power system caused by the asynchronous motors started.

  1. A Reactive Power Dispatch Strategy with Loss Minimization for a DFIG Based Wind Farm

    DEFF Research Database (Denmark)

    Zhang, Baohua; Hou, Peng; Hu, Weihao

    2016-01-01

    An optimal reactive power dispatch strategy is proposed to minimize the total electrical losses of a Wind Farm (WF), including not only losses in the transmission cables and Wind Turbine (WT) transformers, but also losses inside wind energy generation systems. The reactive power dispatch inside...... reactive power limits. A WF is carefully designed and used for case studies. Wake effect is considered when calculating the active power at each WT. The total losses of the WF are calculated by implementing the proposed strategy at different wind speeds and reactive power references. The simulation results...

  2. Microgrid Reactive and Harmonic Power Sharing Using Enhanced Virtual Impedance

    DEFF Research Database (Denmark)

    He, Jinwei; Wei Li, Yun; Guerrero, Josep M.

    2013-01-01

    only a line current feed-forward term is added to the DG voltage reference, the proposed virtual impedances at fundamental and harmonic frequencies are realized using DG line current and point of common coupling (PCC) voltage feed-forward terms, respectively. With this modification, the mismatched DG......To address the load sharing problem in islanding microgrids, this paper proposes an improved approach which regulates the distributed generation (DG) unit interfacing virtual impedance at fundamental and selected harmonic frequencies. In contrast to the conventional virtual impedance control where...... feeder impedances can be properly compensated, resulting in accurate reactive and harmonic power sharing at the same time. In addition, this paper shows that the microgrid PCC harmonic voltages can be mitigated by reducing the magnitude of DG unit equivalent harmonic impedance. Finally, an improved...

  3. Robust Adaptive Reactive Power Control for Doubly Fed Induction Generator

    Directory of Open Access Journals (Sweden)

    Huabin Wen

    2014-01-01

    Full Text Available The problem of reactive power control for mains-side inverter (MSI in doubly fed induction generator (DFIG is studied in this paper. To accommodate the modelling nonlinearities and inherent uncertainties, a novel robust adaptive control algorithm for MSI is proposed by utilizing Lyapunov theory that ensures asymptotic stability of the system under unpredictable external disturbances and significant parametric uncertainties. The distinguishing benefit of the aforementioned scheme consists in its capabilities to maintain satisfactory performance under varying operation conditions without the need for manually redesigning or reprogramming the control gains in contrast to the commonly used PI/PID control. Simulations are also built to confirm the correctness and benefits of the control scheme.

  4. THE IMPACT OF POWER COEFFICIENT OF REACTIVITY ON CANDU 6 REACTORS

    OpenAIRE

    D. KASTANYA; S. BOYLE; Hopwood, J; Park, Joo Hwan

    2013-01-01

    The combined effects of reactivity coefficients, along with other core nuclear characteristics, determine reactor core behavior in normal operation and accident conditions. The Power Coefficient of Reactivity (PCR) is an aggregate indicator representing the change in reactor core reactivity per unit change in reactor power. It is an integral quantity which captures the contributions of the fuel temperature, coolant void, and coolant temperature reactivity feedbacks. All nuclear reactor design...

  5. Impact of Reactive Power Injection Outside Feed-In Hours on the Reliability of Photovoltaic Inverters

    DEFF Research Database (Denmark)

    Anurag, Anup; Yang, Yongheng; Blaabjerg, Frede

    2015-01-01

    -in operation, especially at night. This serves as a motivation for utilizing the PV inverters at night for reactive power compensation. Thus, a detailed analysis on the impact of reactive power injection by PV inverters outside feed-in operation on the thermal performance and also the reliability is performed...... in this paper. A thermal analysis based on the mission profile (i.e. solar irradiance and ambient temperature) has been incorporated, so as to determine the additional temperature rise in the components (IGBTs and diodes) outside feed-in operation for different values of reactive power injection. Consequently...... for different values of reactive power injection an assessment of the economic impacts is made. This analysis can be useful in choosing between conventional reactive power devices or PV inverters for injecting reactive power to the grid....

  6. Progressive Particle Swarm Optimization Algorithm for Solving Reactive Power Problem

    Directory of Open Access Journals (Sweden)

    Kanagasabai Lenin

    2015-11-01

    Full Text Available In this paper a Progressive particle swarm optimization algorithm (PPS is used to solve optimal reactive power problem. A Particle Swarm Optimization algorithm maintains a swarm of particles, where each particle has position vector and velocity vector which represents the potential solutions of the particles. These vectors are modernized from the information of global best (Gbest and personal best (Pbest of the swarm. All particles move in the search space to obtain optimal solution. In this paper a new concept is introduced of calculating the velocity of the particles with the help of Euclidian Distance conception. This new-fangled perception helps in finding whether the particle is closer to Pbest or Gbest and updates the velocity equation consequently. By this we plan to perk up the performance in terms of the optimal solution within a rational number of generations. The projected PPS has been tested on standard IEEE 30 bus test system and simulation results show clearly the better performance of the proposed algorithm in reducing the real power loss with control variables are within the limits.

  7. A New DC Power Flow Model for Q Flow Analysis for use in Reactive Power Market

    Directory of Open Access Journals (Sweden)

    K. Sarmila Har Beagam

    2017-04-01

    Full Text Available DC Power Flow method is widely used for active power flow analysis in deregulated power system. DC Power Flow model is a constant matrix, non-iterative model which is built into DC Optimal Power Flow model for market clearing and settlement of real power market. As of now, there are few papers available in DC Power Flow model for reactive power flow analysis .Hence, this paper introduces a pure Q market and proposes a new DC Q flow model (DCQF which can be built into a DC Optimal Q flow model for market clearing and settlement of pure Q market. In addition to the DCQF method, to obtain accurate result satisfying a specified mismatch tolerance, an Iterative QF method is also proposed whose results match exactly with the solution obtained using FDPF method. The DCQF method and Iterative QF method are tested on Ward and Hale 6-Bus System, IEEE-30 Bus System and Indian Utility 119-Bus System. The bus voltage magnitude computed using the proposed DCQF method is compared with the accurate solution obtained using Iterative QF method (proposed/Fast Decoupled Power Flow method for a mismatch tolerance of 0.1 MVAr. The maximum error value obtained is acceptable even for security analysis. The proposed DCQF and Iterative QF method are faster when compared to FDPF method.

  8. Voltage and reactive power control in WPPs. Solutions adopted and lessons learned from three international experiences

    Energy Technology Data Exchange (ETDEWEB)

    Quinonez-Varela, G.; Lorenzo-Sotelo, P.; Alonso-Sadaba, O.; Arlaban-Gabeiras, M.T.; Solano-Lopez, L.; Giraut-Ruso, E.; Chocarro-Aguirrebengoa, I.; Duddy, P.; Ruiz-Guillen, J.; Rebollo-Rico, I. [Acciona Energia, S.A., Sarriguren (Spain)

    2010-07-01

    Voltage and reactive power control is a requirement imposed on wind power plants by numerous System Operators around the world in recent years. Nowadays, more stringent demands are being enforced to allow a larger and safer grid integration of wind generation. The Grid Codes defining these requirements differ from each other depending on the country, characteristics of the grid and other site specific conditions. This paper presents three relevant examples of Acciona's experience in adopting solutions to meet the latest voltage and reactive control requirements in Canada, Australia and Spain, each case based on different wind turbine technology namely Full Converter, DFIG and Squirrel Cage respectively. A thorough discussion of the solutions is provided including a description of the control algorithms and results from field tests performed to demonstrate compliance. (orig.)

  9. Reactive Power Support of Electrical Vehicle Charging Station Upgraded with Flywheel Energy Storage System

    DEFF Research Database (Denmark)

    SUN, BO; Dragicevic, Tomislav; Savaghebi, Mehdi

    2015-01-01

    Electrical vehicles (EVs) are presenting increasingly potential to replace the conventional fossil fuel based vehicles due to environmental friendly characteristic. Accordingly, Charging Stations (CS), as an intermediate between grid and large numbers of EVs, are supposed to have more critical...... influence on future smart transportation network. This paper explores an off-board charging station upgraded with flywheel energy storage system that could provide a reactive power support to the grid utility. A supervisory control scheme based on distributed bus signaling is proposed to coordinate...... the operation of each component in the system. As a result, the charging station could supply the reactive power support to the utility grid without compromising the charging algorithm and preserve the battery’s lifetime. Finally, the real-time simulation results based on dSPACE1006 verifies the proposed...

  10. FUZZY LOGIC CONTROLLER BASED ACTIVE POWER LINE CONDITIONERS FOR COMPENSATING REACTIVE POWER AND HARMONICS

    Directory of Open Access Journals (Sweden)

    Karuppanan.P

    2010-07-01

    Full Text Available This article explores a novel fuzzy logic controller (FLC based threephase shunt active power line conditioners (APLC for power quality improvements due to the non-linear loads. The fuzzy logic controller is Mamdani-type and linguistic description, so it does not necessitate a mathematical model of the system. The FLC controller is capable of controlling harmonic current and dc-side capacitor voltage of the inverter to improve the performance of the active power filter. Hysteresis current controller (HCC is used to generate the switching signals from the comparison of reference current and actual current for driving the current controlled voltage source inverter (VSI. Extensive simulation executed and tested under different non-linear load conditions. The simulation results reveal that the APLC with fuzzy logic controller is a perfect candidate for current harmonics and reactive power compensation.

  11. Containment and Consensus-Based Distributed Coordination Control to Achieve Bounded Voltage and Precise Reactive Power Sharing in Islanded AC Microgrids

    DEFF Research Database (Denmark)

    Han, Renke; Meng, Lexuan; Ferrari-Trecate, Giancarlo

    2017-01-01

    This paper presents a novel distributed approach to achieve both bounded voltage and accurate reactive power sharing regulation in AC microgrid. The coupling/trade-off effects between bus voltages and reactive power sharing regulation are first analyzed in detail to provide a guideline for coordi...

  12. Genetic Algorithms for Optimal Reactive Power Compensation of a Power System with Wind Generators based on Artificial Neural Networks

    Directory of Open Access Journals (Sweden)

    L. Krichen

    2007-03-01

    Full Text Available In this paper, we develop a method to maintain an acceptable voltages profile and minimization of active losses of a power system including wind generators in real time. These tasks are ensured by acting on capacitor and inductance benches implemented in the consuming nodes. To solve this problem, we minimize an objective function associated to active losses under constraints imposed on the voltages and the reactive productions of the various benches. The minimization procedure was realised by the use of genetic algorithms (GA. The major disadvantage of this technique is that it requires a significant computing time thus not making it possible to deal with the problem in real time. After a training phase, a neural model has the capacity to provide a good estimation of the voltages, the reactive productions and the losses for forecast curves of the load and the wind speed, in real time.

  13. Active and reactive power control of a current-source PWM-rectifier using space vectors

    Energy Technology Data Exchange (ETDEWEB)

    Salo, M.; Tuusa, H. [Tampere University of Technology (Finland). Department of Electrical Engineering, Power Electronics

    1997-12-31

    In this paper the current-source PWM-rectifier with active and reactive power control is presented. The control system is realized using space vector methods. Also, compensation of the reactive power drawn by the line filter is discussed. Some simulation results are shown. (orig.) 8 refs.

  14. New hybrid active power filter for harmonic current suppression and reactive power compensation

    Science.gov (United States)

    Biricik, Samet; Cemal Ozerdem, Ozgur; Redif, Soydan; Sezai Dincer, Mustafa

    2016-08-01

    In the case of undistorted and balanced grid voltages, low ratio shunt active power filters (APFs) can give unity power factors and achieve current harmonic cancellation. However, this is not possible when source voltages are distorted and unbalanced. In this study, the cost-effective hybrid active power filter (HAPF) topology for satisfying the requirements of harmonic current suppression and non-active power compensation for industry is presented. An effective strategy is developed to observe the effect of the placement of power capacitors and LC filters with the shunt APF. A new method for alleviating the negative effects of a nonideal grid voltage is proposed that uses a self-tuning filter algorithm with instantaneous reactive power theory. The real-time control of the studied system was achieved with a field-programmable gate array (FPGA) architecture, which was developed using the OPAL-RT system. The performance result of the proposed HAPF system is tested and presented under nonideal supply voltage conditions.

  15. Reactive Power Strategy of Cascaded Delta-connected STATCOM Under Asymmetrical Voltage Conditions

    DEFF Research Database (Denmark)

    He, Zhixing; Ma, Fujun; Xu, Qianming

    2017-01-01

    Cascaded static synchronous compensator (STATCOM) is an effective solution for reactive power support in mid-dle/high voltage conditions, and it has been widely employed to control reactive power in photovoltaic (PV) plants, wind farms, and industrial occasions. In this paper, reactive power...... control strategy of cascaded delta-connected STATCOM under asym-metrical voltage conditions is investigated. A new phase current reference calculation method is proposed to support reactive power continually under abnormal voltage conditions considering cluster voltage balancing control and phase current...... of the phase current references. Furthermore, the reactive power support capability of cascaded STATCOM under asymmetrical voltage conditions is explored and compared by combining the proposed references calculation method with the three generalized current references calculation strategies. Finally...

  16. Real-Time Reactive Power Distribution in Microgrids by Dynamic Programing

    DEFF Research Database (Denmark)

    Levron, Yoash; Beck, Yuval; Katzir, Liran

    2017-01-01

    as radial ones. The optimization problem is formulated with the cluster reactive powers as free variables, and the solution space is spanned by the cluster reactive power outputs. The optimal solution is then constructed by efficiently scanning the entire solution space, by scanning every possible......In this paper a new real-time optimization method for reactive power distribution in microgrids is proposed. The method enables location of a globally optimal distribution of reactive power under normal operating conditions. The method exploits the typical compact structure of microgrids to obtain...... combination of reactive powers, by means of dynamic programming. Since every single step involves a one-dimensional problem, the complexity of the solution is only linear with the number of clusters, and as a result, a globally optimal solution may be obtained in real time. The paper includes the results...

  17. Proactive and Reactive Transmission Power Control for Energy-Efficient On-Body Communications

    Science.gov (United States)

    Vallejo, Mónica; Recas, Joaquín.; Ayala, José L.

    2015-01-01

    In wireless body sensor network (WBSNs), the human body has an important effect on the performance of the communication due to the temporal variations caused and the attenuation and fluctuation of the path loss. This fact suggests that the transmission power must adapt to the current state of the link in a way that it ensures a balance between energy consumption and packet loss. In this paper, we validate our two transmission power level policies (reactive and predictive approaches) using the Castalia simulator. The integration of our experimental measurements in the simulator allows us to easily evaluate complex scenarios, avoiding the difficulties associated with a practical realization. Our results show that both schemes perform satisfactorily, providing overall energy savings of 24% and 22% for a case of study, as compared to the maximum transmission power mode. PMID:25769049

  18. Reactive Power Dispatch Method in Wind Farms to Improve the Lifetime of Power Converter Considering Wake Effect

    DEFF Research Database (Denmark)

    Tian, Jie; Zhou, Dao; Su, Chi

    2017-01-01

    In Wind Farms (WF), the most popular and commonly implemented active power control method is the Maximum Power Point Tracking (MPPT). Due to the wake effect, the upstream Wind Turbine (WT) in WFs has more active power generation than the downstream WT at the wind directions and wind speeds...... DFIG WTs. It can be concluded that, compared with the traditional reactive power dispatch method, the proposed method can increase the lifetime of the upstream WT’s power converter....

  19. An Optimal Reactive Power Control Strategy for a DFIG-Based Wind Farm to Damp the Sub-Synchronous Oscillation of a Power System

    Directory of Open Access Journals (Sweden)

    Bin Zhao

    2014-05-01

    Full Text Available This study presents the auxiliary damping control with the reactive power loop on the rotor-side converter of doubly-fed induction generator (DFIG-based wind farms to depress the sub-synchronous resonance oscillations in nearby turbogenerators. These generators are connected to a series capacitive compensation transmission system. First, the damping effect of the reactive power control of the DFIG-based wind farms was theoretically analyzed, and a transfer function between turbogenerator speed and the output reactive power of the wind farms was introduced to derive the analytical expression of the damping coefficient. The phase range to obtain positive damping was determined. Second, the PID phase compensation parameters of the auxiliary damping controller were optimized by a genetic algorithm to obtain the optimum damping in the entire subsynchronous frequency band. Finally, the validity and effectiveness of the proposed auxiliary damping control were demonstrated on a modified version of the IEEE first benchmark model by time domain simulation analysis with the use of DigSILENT/PowerFactory. Theoretical analysis and simulation results show that this derived damping factor expression and the condition of the positive damping can effectively analyze their impact on the system sub-synchronous oscillations, the proposed wind farms reactive power additional damping control strategy can provide the optimal damping effect over the whole sub-synchronous frequency band, and the control effect is better than the active power additional damping control strategy based on the power system stabilizator.

  20. Comprehensive Reactive Power Support of DFIG Adapted to Different Depth of Voltage Sags

    Directory of Open Access Journals (Sweden)

    Yangwu Shen

    2017-06-01

    Full Text Available The low voltage ride-through (LVRT capability of the doubly-fed induction generator (DFIG significantly impacts upon the integration of wind power into the power grid. This paper develops a novel comprehensive control strategy to enhance the LVRT and reactive power support capacities of the DFIG by installing the energy storage system (ESS. The ESS is connected to the DC-link capacitor of the DFIG and used to regulate the DC-link voltage during normal or fault operations. The unbalanced power between the captured wind power and the power injected to the grid during the transient process is absorbed or compensated by the ESS. The rotor-side converter (RSC is used to control the maximum power production and the grid-side converter (GSC is used to control the reactive power before participating in the voltage support. When the supply voltage continues to drop, the rotor speed is increased by controlling the RSC to realize the LVRT capability and help the GSC further enhance the reactive power support capability. The capacity of the GSC is dedicated to injecting the reactive power to the grid. An auxiliary transient pitch angle controller is proposed to protect the generator’s over speed. Both RSC and GSC act as reactive power sources to further enhance the voltage support capability with serious voltage sags. Simulations based on a single-machine infinite-bus power system verify the effectiveness of the developed comprehensive control strategy.

  1. An Efficient Reactive Power Control Method for Power Network Systems with Solar Photovoltaic Generators Using Sparse Optimization

    Directory of Open Access Journals (Sweden)

    Yu Li

    2017-05-01

    Full Text Available With the incremental introduction of solar photovoltaic (PV generators into existing power systems, and their fast-growing share in the gross electricity generation, system voltage stability has become a critical issue. One of the major concerns is voltage fluctuation, due to large and random penetration of solar PV generators. To suppress severe system voltage deviation, reactive power control of the photovoltaic system inverter has been widely proposed in recent works; however, excessive use of reactive power control would increase both initial and operating costs. In this paper, a method for efficient allocation and control of reactive power injection using the sparse optimization technique is proposed. Based on a constrained linearized model describing the influence of reactive power injection on voltage magnitude change, the objective of this study is formulated as an optimization problem, which aims to find the best reactive power injection that minimizes the whole system voltage variation. Two types of formulations are compared: the first one is the conventional least-square optimization, while the second one is adopted from a sparse optimization technique, called the constrained least absolute shrinkage and selection operator (LASSO method. The constrained LASSO method adds ℓ 1 -norm penalty to the total reactive power injection, which contributes to the suppression of the number of control nodes with non-zero reactive power injection. The authors analyzed the effectiveness of the constrained LASSO method using the IEEE 39-bus and 57-bus power network as benchmark examples, under various PV power generation and allocation patterns. The simulation results show that the constrained LASSO method automatically selects the minimum number of inverters required for voltage regulation at the current operating point.

  2. Application of a fast and elitist multi-objective genetic algorithm to Reactive Power Dispatch

    Directory of Open Access Journals (Sweden)

    Subramanian Ramesh

    2009-01-01

    Full Text Available This paper presents an Elitist Non-Dominated Sorting Genetic Algorithm version II (NSGA-II, for solving the Reactive Power Dispatch (RPD problem. The optimal RPD problem is a nonlinear constrained multi-objective optimization problem where the real power loss and the bus voltage deviations are to be minimized. Since the problem is treated as a true multi-objective optimization problem, different trade-off solutions are provided. The decision maker has an option to choose a solution among the different trade-off solutions provided in the pareto-optimal front. The standard IEEE 30-bus test system is used and the results show the effectiveness of NSGA-II and confirm its potential to solve the multi-objective RPD problem. The results obtained by NSGA-II are compared and validated with conventional weighted sum method using Real-coded Genetic Algorithm (RGA and NSGA.

  3. Optimization of a Virtual Power Plant to Provide Frequency Support.

    Energy Technology Data Exchange (ETDEWEB)

    Neely, Jason C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Johnson, Jay [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gonzalez, Sigifredo [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lave, Matthew Samuel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Delhotal, Jarod James [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-12-01

    Increasing the penetration of distributed renewable sources, including photovoltaic (PV) sources, poses technical challenges for grid management. The grid has been optimized over decades to rely upon large centralized power plants with well-established feedback controls, but now non-dispatchable, renewable sources are displacing these controllable generators. This one-year study was funded by the Department of Energy (DOE) SunShot program and is intended to better utilize those variable resources by providing electric utilities with the tools to implement frequency regulation and primary frequency reserves using aggregated renewable resources, known as a virtual power plant. The goal is to eventually enable the integration of 100s of Gigawatts into US power systems.

  4. Impact on Generator Reactive Power Limits on a Static Voltage Stability

    Directory of Open Access Journals (Sweden)

    TOVAR-GONZALEZ, E. A.

    2011-11-01

    Full Text Available Voltage stability margin in a power system is closely related with the availability of reactive power in the system. Therefore, adequate modeling of the reactive power sources becomes an important issue in this type of studies. The Minimum Singular Value of the load flow Jacobian matrix has been commonly used as a static voltage stability index. In this paper, such index is used to assess the influence on the static voltage stability limit of modeling the generators reactive power limits by its capability curve. Simulation results on a test system indicate that modeling the reactive power limits of the generating units by the simplified Qmin/Qmax approach, commonly used by most of the load flow programs, yields optimistic values for this voltage stability index.

  5. Multi-objective Reactive Power Optimization Based on Improved Particle Swarm Algorithm

    Science.gov (United States)

    Cui, Xue; Gao, Jian; Feng, Yunbin; Zou, Chenlu; Liu, Huanlei

    2018-01-01

    In this paper, an optimization model with the minimum active power loss and minimum voltage deviation of node and maximum static voltage stability margin as the optimization objective is proposed for the reactive power optimization problems. By defining the index value of reactive power compensation, the optimal reactive power compensation node was selected. The particle swarm optimization algorithm was improved, and the selection pool of global optimal and the global optimal of probability (p-gbest) were introduced. A set of Pareto optimal solution sets is obtained by this algorithm. And by calculating the fuzzy membership value of the pareto optimal solution sets, individuals with the smallest fuzzy membership value were selected as the final optimization results. The above improved algorithm is used to optimize the reactive power of IEEE14 standard node system. Through the comparison and analysis of the results, it has been proven that the optimization effect of this algorithm was very good.

  6. Multiagent-Based Reactive Power Sharing and Control Model for Islanded Microgrids

    DEFF Research Database (Denmark)

    Chen, Feixiong; Chen, Minyou; Li, Qiang

    2016-01-01

    In islanded microgrids (MGs), the reactive power cannot be shared proportionally among distributed generators (DGs) with conventional droop control, due to the mismatch in feeder impedances. For the purpose of proportional reactive power sharing, a multiagent system (MAS) based distributed control...... of the control model, in which the uncertainty of intermittent DGs, variations in load demands, as well as impacts of time delays are considered. The simulation results demonstrate the eectiveness of the control model in proportional reactive power sharing, and the plug and play capability of the control model...

  7. Distributed Reactive Power Control based Conservation Voltage Reduction in Active Distribution Systems

    Directory of Open Access Journals (Sweden)

    EMIROGLU, S.

    2017-11-01

    Full Text Available This paper proposes a distributed reactive power control based approach to deploy Volt/VAr optimization (VVO / Conservation Voltage Reduction (CVR algorithm in a distribution network with distributed generations (DG units and distribution static synchronous compensators (D-STATCOM. A three-phase VVO/CVR problem is formulated and the reactive power references of D-STATCOMs and DGs are determined in a distributed way by decomposing the VVO/CVR problem into voltage and reactive power control. The main purpose is to determine the coordination between voltage regulator (VR and reactive power sources (Capacitors, D-STATCOMs and DGs based on VVO/CVR. The study shows that the reactive power injection capability of DG units may play an important role in VVO/CVR. In addition, it is shown that the coordination of VR and reactive power sources does not only save more energy and power but also reduces the power losses. Moreover, the proposed VVO/CVR algorithm reduces the computational burden and finds fast solutions. To illustrate the effectiveness of the proposed method, the VVO/CVR is performed on the IEEE 13-node test system feeder considering unbalanced loading and line configurations. The tests are performed taking the practical voltage-dependent load modeling and different customer types into consideration to improve accuracy.

  8. A Comparison between Voltage and Reactive Power Feedback Schemes of DFIGs for Inter-Area Oscillation Damping Control

    Directory of Open Access Journals (Sweden)

    Kai Liao

    2017-08-01

    Full Text Available Reactive power modulation of wind power plants is an effective way to damp inter-area oscillation in wind power penetrated power systems. For doubly fed induction generator (DFIG based wind farms, there are two different ways to achieve reactive power modulation: one is via reactive power feedback control, and the other method is via voltage feedback control. While both of the control schemes are feasible, their effectiveness may differ, and there has not been a systematic comparison between them. This paper investigates the differences between these two feedback schemes for inter-area oscillation damping control. The principles of utilizing DFIG for damping control is introduced at first. Then, analytical techniques including the frequency domain analysis, μ -analysis and time domain analysis are used to systematically study the performance of the two control schemes against inter-area oscillation. The robustness of the control schemes with respect to the variety of system operation points is also studied. The results from this paper can provide an insight into the understatement of DFIG reactive modulation against oscillation and guidance for controller design.

  9. Consensus-based Distributed Control for Accurate Reactive, Harmonic and Imbalance Power Sharing in Microgrids

    DEFF Research Database (Denmark)

    Zhou, Jianguo; Kim, Sunghyok; Zhang, Huaguang

    2017-01-01

    This paper investigates the issue of accurate reactive, harmonic and imbalance power sharing in a microgrid. Harmonic and imbalance droop controllers are developed to proportionally share the harmonic power and the imbalance power among distributed generation (DG) units and improve the voltage qu...

  10. Improvement of the dynamic response of the ITER Reactive Power Compensation system

    Energy Technology Data Exchange (ETDEWEB)

    Finotti, Claudio, E-mail: claudio.finotti@igi.cnr.it [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova (Italy); Gaio, Elena [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), Corso Stati Uniti 4, 35127 Padova (Italy); Song, Inho; Tao, Jun; Benfatto, Ivone [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France)

    2015-10-15

    Highlights: • The slow response reasons of the classic ITER Reactive Power Compensation (RPC) control are explained. • The dynamic behaviors of the ac/dc converter and of the RPC are characterized. • New control concept to speed up the RPC response is developed. • Good performance of the new RPC control is verified even during fast transient conditions. - Abstract: The ITER ac/dc conversion system can absorb a total active and reactive power up to 500 MW and 950 Mvar, respectively. The Reactive Power Compensation (RPC) system is rated for a nominal power of 750 Mvar necessary to comply with the allowable reactive power limit value from the grid of 200 Mvar. This system is currently under construction and is based on Static Var Compensation technology with Thyristor Controlled Reactor (TCR) and Tuned Filters. The RPC has to minimize the demand of reactive power from the grid; its control is based on a feed-forward method, where the corrective input is the measurement of the reactive power consumption of the ac/dc converters, derived from the 50 Hz component of the Fast Fourier Transform (FFT) of the three-phase voltages and currents. The delay introduced by the FFT calculation and the slow response of the TCR could make the response speed of the RPC not sufficient to face fast variations of the reactive power demand and therefore in this paper a new controller of the RPC able to overcome this shortcoming is proposed and evaluated. It is based on the calculation of the predicted consumption of the reactive power by using the voltage reference signals coming from the Plasma Control System and the measurements of the dc current of the ac/dc converters and of the 66 kV busbar voltage, and on the speed up of the RPC control by introducing a lead–lag transfer function.

  11. Local Reactive Power Control Methods for Overvoltage Prevention of Distributed Solar Inverters in Low-Voltage Grids

    DEFF Research Database (Denmark)

    Demirok, Erhan; Gonzalez, Pablo Casado; Frederiksen, Kenn H. B.

    2011-01-01

    voltage (LV) grids by means of solar inverters with reactive power control capability. This paper underlines weak points of standard reactive power strategies which are already imposed by certain grid codes, and then, the study introduces a new reactive power control method that is based on sensi...

  12. Biodiesel by catalytic reactive distillation powered by metal oxides

    NARCIS (Netherlands)

    Kiss, A.A.; Dimian, A.C.; Rothenberg, G.

    2008-01-01

    The properties and use of biodiesel as a renewable fuel as well as the problems associated with its current production processes are outlined. A novel sustainable esterification process based on catalytic reactive distillation is proposed. The pros and cons of manufacturing biodiesel via fatty acid

  13. Optimal System for the Compensation of the Reactive Power with Synchronous Motors

    Directory of Open Access Journals (Sweden)

    Iuliu Petrica

    2010-10-01

    Full Text Available In the activity of some factories that use synchronous motors it’s nec-essary to chose and maintain the most rational value of the reactive power provided by the synchronous motors. In the context of the reduction of the energy consumption and knowing that the power of the synchronous motors is relatively great in the air compressor stations, the approach of the optimal regime of functioning of the synchronous motors, concerning the energy consumption, is necessary. Considering the synchronous motors together with the other consumers fed from the same bars and the feeder cable a functional utility, in the paper as optimising is presented the working regime that assures, on the defined above assembly, the minimal losses of energy.

  14. Review of reactive power dispatch strategies for loss minimization in a DFIG-based wind farm

    DEFF Research Database (Denmark)

    Zhang, Baohua; Hu, Weihao; Hou, Peng

    2017-01-01

    power control strategies are investigated. All of the combined strategies are formulated based on the comprehensive loss models of WFs, including the loss models of DFIGs, converters, filters, transformers, and cables of the collection system. Optimization problems are solved by a Modified Particle...... Swarm Optimization (MPSO) algorithm. The effectiveness of these strategies is evaluated by simulations on a carefully designed WF under a series of cases with different wind speeds and reactive power requirements of the WF. The wind speed at each WT inside the WF is calculated using the Jensen wake......This paper reviews and compares the performance of reactive power dispatch strategies for the loss minimization of Doubly Fed Induction Generator (DFIG)-based Wind Farms (WFs). Twelve possible combinations of three WF level reactive power dispatch strategies and fourWind Turbine (WT) level reactive...

  15. MILP Approach for Bilevel Transmission and Reactive Power Planning Considering Wind Curtailment

    DEFF Research Database (Denmark)

    Ugranli, Faruk; Karatepe, Engin; Nielsen, Arne Hejde

    2017-01-01

    In this study, two important planning problems in power systems that are transmission expansion and reactive power are formulated as a mixed-integer linear programming taking into account the bilevel structure due to the consideration of market clearing under several load-wind scenarios. The obje......In this study, two important planning problems in power systems that are transmission expansion and reactive power are formulated as a mixed-integer linear programming taking into account the bilevel structure due to the consideration of market clearing under several load-wind scenarios...... system planners will be able to find economical investment plans by considering the balance between wind power curtailment and the installation of transmission lines and reactive power sources....

  16. Reactive power balance in a distribution network with wind farms and CHPS

    DEFF Research Database (Denmark)

    Lund, Torsten; Nielsen, John Eli; Hylle, Per

    2007-01-01

    In Denmark, a large part of the electricity is generated by wind turbines and combined heat and power plants. Most of them are connected to the distribution systems. In periods with high wind speeds, large flows of reactive power have been observed between the 150kV and the 60 kV systems. The tra......In Denmark, a large part of the electricity is generated by wind turbines and combined heat and power plants. Most of them are connected to the distribution systems. In periods with high wind speeds, large flows of reactive power have been observed between the 150kV and the 60 kV systems....... The transfer of reactive power reduces the capacity of the lines, causes thermal losses and can in some cases reduce the voltage stability margin of the system. To identify the origin of the problem, an actual distribution system with a high penetration of wind power and distributed generation has been...

  17. ACCOUNTING OF REACTIVE POWER COMPENSATION LEVEL AT PAYMENT CALCULATION OF TECHNOLOGICAL CONSUMPTION (LOSSES OF ELECTRIC POWER FOR ITS TRANSMISSION IN POWER NETWORK

    Directory of Open Access Journals (Sweden)

    E. P. Zabello

    2005-01-01

    Full Text Available The method is proposed to make a correction in payment for consumption of reactive energy and power which is attributed to deviation of actual activation energy losses for reactive power compensation from their standard value. It is recommended to calculate standard loss values for every voltage level and actual loss values are to be determined with the help of application of remote electronic accounting means in the current mode of power consumption.

  18. Reactive Power Dispatch for Loss Minimization of a Doubly Fed Induction Generator Based Wind Farm

    DEFF Research Database (Denmark)

    Zhang, Baohua; Hu, Weihao; Hou, Peng

    2014-01-01

    This paper proposes an optimal reactive power dispatching strategy in order to minimize the total losses in a DFIG based wind farm, including the copper loss of the generators, the losses of converters, filters, transformers and the losses of cables. The reactive power constraints, bus voltage...... constraints as well as other operational constraints are considered in the optimization problem. The proposed strategy is compared with proportional dispatching method. Simulation results validate the effectiveness of the proposed strategy....

  19. An islanding microgrid reactive power sharing scheme enhanced by programmed virtual impedances

    DEFF Research Database (Denmark)

    He, Jinwei; Li, Yun Wei; Guerrero, Josep M.

    2012-01-01

    This paper proposes an improved power control approach to address the load sharing problems in islanded microgrids. The proposed method first estimates distributed generation (DG) unit feeder impedances through measuring low order point of common coupling (PCC) harmonic voltages and DG unit line...... harmonic currents. With the knowledge of feeder impedances, reactive power sharing performance can be enhanced by the regulation of DG unit output virtual impedance. The proposed method realizes accurate real and reactive power sharing in proportion to DG unit rated power. Simulated and experimental...

  20. Towards a Reactive Power Oscillation Damping Controller for Wind Power Plant Based on Full Converter Wind Turbines

    DEFF Research Database (Denmark)

    Knüppel, Thyge; Kumar, Sathess; Thuring, Patrik

    2012-01-01

    In this paper a power oscillation damping controller (POD) based on modulation of reactive power (Q POD) is analyzed where the modular and distributed characteristics of the wind power plant (WPP) are considered. For a Q POD it is essential that the phase of the modulated output is tightly...... controlled to achieve a positive damping contribution. It is investigated how a park level voltage, reactive power, and power factor control at different grid strengths interact with the Q POD in terms of a resulting phase shift. A WPP is modular and distributed and a WPP Q POD necessitate that each WT...... contributes to a collective response. This ability is shown with a 150 wind turbine (WT) WPP with all WTs represented, and it is demonstrated that the WPP contributes to the inter-area damping. The work is based on a nonlinear, dynamic model of the 3.6 MW Siemens Wind Power WT....

  1. Reactive Power Compensation Using an Energy Management System

    Science.gov (United States)

    2014-09-01

    of light loading [6] is also demonstrated. Other works include an analysis of the effects on microgrid power quality given different H- bridge...inverter loading schemes [7] and using the EMS to manage peak power demand on a microgrid in order to improve energy efficiency and reduce energy costs [8

  2. A New Approach to Optimal Allocation of Reactive Power Ancillary Service in Distribution Systems in the Presence of Distributed Energy Resources

    Directory of Open Access Journals (Sweden)

    Abouzar Samimi

    2015-11-01

    Full Text Available One of the most important Distribution System Operators (DSO schemes addresses the Volt/Var control (VVC problem. Developing a cost-based reactive power dispatch model for distribution systems, in which the reactive powers are appropriately priced, can motivate Distributed Energy Resources (DERs to participate actively in VVC. In this paper, new reactive power cost models for DERs, including synchronous machine-based DGs and wind turbines (WTs, are formulated based on their capability curves. To address VVC in the context of competitive electricity markets in distribution systems, first, in a day-ahead active power market, the initial active power dispatch of generation units is estimated considering environmental and economic aspects. Based on the results of the initial active power dispatch, the proposed VVC model is executed to optimally allocate reactive power support among all providers. Another novelty of this paper lies in the pricing scheme that rewards transformers and capacitors for tap and step changing, respectively, while incorporating the reactive power dispatch model. A Benders decomposition algorithm is employed as a solution method to solve the proposed reactive power dispatch, which is a mixed integer non-linear programming (MINLP problem. Finally, a typical 22-bus distribution network is used to verify the efficiency of the proposed method.

  3. Insurer Market Power Lowers Prices In Numerous Concentrated Provider Markets.

    Science.gov (United States)

    Scheffler, Richard M; Arnold, Daniel R

    2017-09-01

    Using prices of hospital admissions and visits to five types of physicians, we analyzed how provider and insurer market concentration-as measured by the Herfindahl-Hirschman Index (HHI)-interact and are correlated with prices. We found evidence that in the range of the Department of Justice's and Federal Trade Commission's definition of a moderately concentrated market (HHI of 1,500-2,500), insurers have the bargaining power to reduce provider prices in highly concentrated provider markets. In particular, hospital admission prices were 5 percent lower and cardiologist, radiologist, and hematologist/oncologist visit prices were 4 percent, 7 percent, and 19 percent lower, respectively, in markets with high provider concentration and insurer HHI above 2,000, compared to such markets with insurer HHI below 2,000. We did not find evidence that high insurer concentration reduced visit prices for primary care physicians or orthopedists, however. The policy dilemma that arises from our findings is that there are no insurer market mechanisms that will pass a portion of these price reductions on to consumers in the form of lower premiums. Large purchasers of health insurance such as state and federal governments, as well as the use of regulatory approaches, could provide a solution. Project HOPE—The People-to-People Health Foundation, Inc.

  4. 77 FR 11109 - Reactive Power Resources; Notice of Technical Conference

    Science.gov (United States)

    2012-02-24

    ... interconnecting asynchronous generators and raises questions concerning the need and efficacy of continuing the... requirements more broadly than to individual wind generators during the interconnection study process.\\2\\ \\1... power resources, including synchronous and asynchronous generation resources, transmission resources and...

  5. Single-Phase Boost Inverter-Based Electric Vehicle Charger With Integrated Vehicle to Grid Reactive Power Compensation

    DEFF Research Database (Denmark)

    Wickramasinghe Abeywardana, Damith Buddika; Acuna, Pablo; Hredzak, Branislav

    2018-01-01

    Vehicle to grid (V2G) reactive power compensation using electric vehicle (EV) onboard chargers helps to ensure grid power quality by achieving unity power factor operation. However, the use of EVs for V2G reactive power compensation increases the second-order harmonic ripple current component...

  6. Reactive power compensation. System service - line quality. 2. ed.; Blindleistungskompensation. Systemdienstleistung - Netzqualitaet

    Energy Technology Data Exchange (ETDEWEB)

    Grosse-Gehling, Martin; Just, Wolfgang; Reese, Juergen; Schlabbach, Juergen

    2013-11-01

    Reactive power compensation is playing an increasingly important role as the need for an efficient use of operating equipment and power grids continues to grow. This book presents the fundamentals of reactive power compensation in low and medium voltage grids, offering a wealth of application and calculation examples that will further the reader's understanding of the following topics: 1. design, dimensioning and operation of capacitors and capacitor installations; 2. long-term stability and ageing of capacitor installations; 3. use of passive and active filters; 4. improvement of voltage quality by means of filters and capacitor installations; 5. provision of reactive power compensation by means of power electronics; 6. costs and economic efficiency of reactive power compensation and filter equipment; 7. considerations from the viewpoint of the power supply industry; price regulations; 8. information requirements concerning PCB-containing capacitors; 9. climate protection and energy efficiency through reactive power compensation; 10. technical connection requirements and guidelines; 11. special technical issues concerning the use of reactive power compensation installations. [German] Die Blindleistungskompensation gewinnt angesichts der Notwendigkeit zur erhoehten Ausnutzung der Betriebsmittel und Netze zunehmend an Bedeutung. In diesem Buch werden die Grundlagen der Blindleistungskompensation in Nieder- und Mittelspannungsnetzen beschrieben und folgende Themen anhand zahlreicher Anwendungs- und Berechnungsbeispiele vertieft: 1. Aufbau, Auslegung und Betrieb von Kondensatoren und Kondensatoranlagen, 2. Langzeitstabilitaet und Alterung von Kondensatoranlagen, 3. Einsatz passiver und aktiver Filter, 4. Verbesserung der Spannungsqualitaet durch Filter und Kondensatoranlagen, 5. Blindleistungsbereitstellung mit Leistungselektronik, 6. Kosten und Wirtschaftlichkeit von Kompensations- und Filteranlagen, 7. Elektrizitaetswirtschaftliche Betrachtungen

  7. The effect of reactive emotions expressed in response to another's anger on inferences of social power.

    Science.gov (United States)

    Hareli, Shlomo; David, Shlomo

    2017-06-01

    Social perception of emotions is influenced by the context in which it occurs. One such context is a social interaction involving an exchange of emotions. The way parties to the interaction are perceived is shaped by the combination of emotions exchanged. This idea was examined by assessing the extent to which expressions of anger toward a target-which, in isolation, are perceived as signals of high social power-are influenced by the target's emotional reaction to it (i.e., reactive emotions). Three studies show that the angry person was perceived as having a higher level of social power when this anger was responded by fear or sadness than when it was responded by neutrality or anger. Study 1 indicated that reactive emotions have a stronger effect on perceived social power when emotions were incongruent with gender stereotypes. Study 2 indicated that these effects are a result of these emotions serving as reactive emotions rather than a benchmark against which the angry person's power is assessed. Study 3 showed that reactive emotions affect perceived social power by serving as signals of the level to which the high social power suggested by the first person's expression is confirmed by its target. Comparing effects of reactive emotions to anger with reactive emotions to sadness, showed that perceived social power of the expresser is determined by the nature of the expression, with some adjustment caused by the reactive emotions. This underscores the importance of social interaction as a context for the social perception of emotions. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  8. Reactive power compensation considering high harmonics generation from internal and external nonlinear load

    Science.gov (United States)

    Skamyin, A. N.; Belsky, A. A.

    2017-10-01

    The paper deals with reactive power compensation by means of condenser batteries with harmonic distortions in voltage and current, resulting from internal and external nonlinear load regarding the connection point shared by consumers. The paper presents the dependencies of the capacitor’s overloading factor from the required reactive power for compensating. These relations can help to determine in which capacity area of the capacitor banks its operation is ensured without overload. The paper also presents algorithm for selecting parameters of condenser batteries which leads to minimization of the capacitors overload and maximization of the network power factor.

  9. Brayton Power Conversion Unit Tested: Provides a Path to Future High-Power Electric Propulsion Missions

    Science.gov (United States)

    Mason, Lee S.

    2003-01-01

    Closed-Brayton-cycle conversion technology has been identified as an excellent candidate for nuclear electric propulsion (NEP) power conversion systems. Advantages include high efficiency, long life, and high power density for power levels from about 10 kWe to 1 MWe, and beyond. An additional benefit for Brayton is the potential for the alternator to deliver very high voltage as required by the electric thrusters, minimizing the mass and power losses associated with the power management and distribution (PMAD). To accelerate Brayton technology development for NEP, the NASA Glenn Research Center is developing a low-power NEP power systems testbed that utilizes an existing 2- kWe Brayton power conversion unit (PCU) from previous solar dynamic technology efforts. The PCU includes a turboalternator, a recuperator, and a gas cooler connected by gas ducts. The rotating assembly is supported by gas foil bearings and consists of a turbine, a compressor, a thrust rotor, and an alternator on a single shaft. The alternator produces alternating-current power that is rectified to 120-V direct-current power by the PMAD unit. The NEP power systems testbed will be utilized to conduct future investigations of operational control methods, high-voltage PMAD, electric thruster interactions, and advanced heat rejection techniques. The PCU was tested in Glenn s Vacuum Facility 6. The Brayton PCU was modified from its original solar dynamic configuration by the removal of the heat receiver and retrofitting of the electrical resistance gas heater to simulate the thermal input of a steady-state nuclear source. Then, the Brayton PCU was installed in the 3-m test port of Vacuum Facility 6, as shown. A series of tests were performed between June and August of 2002 that resulted in a total PCU operational time of about 24 hr. An initial test sequence on June 17 determined that the reconfigured unit was fully operational. Ensuing tests provided the operational data needed to characterize PCU

  10. A NEW RELAY DESIGN FOR REACTIVE POWER COMPENSATION AND ECONOMICAL COMPARISION WITH CLASSICAL RELAY

    Directory of Open Access Journals (Sweden)

    Mustafa ŞEKKELİ

    2007-02-01

    Full Text Available In most cases, reactive power compensation is otomatically achieved with reactive power control relay by switching on and off, stationary shunt capasitors to the electrical network. İn this study , a new relay has been designed and developed. İn this method, capasitors which is switched on and of are optimally choosen. İn classical relay , only one capasitor can be added or extructed to the network. But,in designing new relay, 1,2 or 3 capasitor banks which are nearest value for desired inductive reactive power can be optimally choosen. As a result , switching number of capacitor and contactor is reduced minimum value and line is loaded less inductive current , it means that less active power losses. New designed relay has been compared with classical one economically . This relay has been manufactured and approved experimantally.

  11. Improving voltage stability by utilizing reactive power injection capability of variable speed wind turbines

    Energy Technology Data Exchange (ETDEWEB)

    Ullah, N.R.; Thiringer, T. [Chalmer Univ. of Technology, Goteborg (Sweden). Dept. of Energy and Environment

    2008-07-01

    The effect of wind power generation on voltage stability was investigated by studying various reactive power control algorithms in combination with different wind power systems. The impact of reactive power injection by the systems on steady-state power transfer limits was analyzed. Critical load and wind generation situations were also determined. A power system model based on the Swedish transmission system was used. The wind farm installation was connected to ta 400 kV transmission grid. Four different wind turbine systems were considered: (1) traditional fixed speed; (2) variable speed wind turbine producing active power at unity power factor; (3) a variable speed turbine with a full power grid side converter; and (4) a wind turbine system with a large grid side converter. Simulations were conducted to consider the tap changing action of the transformer for all 4 types of wind turbine. Results of the study showed that use of the reactive power injection capability of wind turbine systems can increase the grid voltage stability limit. The wind farm also assisted in delaying voltage collapse events and prevented the transformer's tap from operating. It was concluded that the use of grid side converters substantially improved maximum deliverable loads. 14 refs., 2 tabs., 15 figs.

  12. Decentralized production: the reactive power problem; Producao descentralizada: o problema da potencia reactiva

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Rui M.G.; Paiva, J.P. Sucena [Universidade Tecnica de Lisboa (Portugal). Inst. Superior Tecnico. E-mail: rcastro@hertz.ist.utl.pt

    1999-07-01

    In accordance with the present regulation, the independent producer of electric power from renewable energy sources, connected to the public network, must supply reactive power equivalent to 40% of the active power produced (at the peak and full consumption). In order to study the consequences of this technical regulation, a high voltage network with contribution from mini hydropower production was analyzed. Initially, a network was studied in its reference configuration and afterwards, in the exploration mode, where the power plants proceed to a local compensation of the power factor. From the obtained results, the main conclusion is that the regulation under discussion is not technically supported, since that a a correct voltage profile is not maintained at the plant influence zone. On the other hand, considering that the reactive power is value with local influence, some benefit for the public network can not be assured.

  13. Power system services provided by inverter connected distributed energy resources

    DEFF Research Database (Denmark)

    For the last few years there has been a significant increase of DER units in Denmark, of those units more and more are connected to the power system using inverters. These inverter connected units have the potential to support the electrical power system with various power system services. One...

  14. Active and reactive power neurocontroller for grid-connected photovoltaic generation system

    Directory of Open Access Journals (Sweden)

    I. Abadlia

    2016-03-01

    Full Text Available Many researchers have contributed to the development of a firm foundation for analysis and design of control applications in grid-connected renewable energy sources. This paper presents an intelligent control algorithm fond on artificial neural networks for active and reactive power controller in grid-connected photovoltaic generation system. The system is devices into two parts in which each part contains an inverter with control algorithm. A DC/DC converter in output voltage established by control magnitude besides maximum power point tracker algorithm always finds optimal power of the PV array in use. A DC/AC hysteresis inverter designed can synchronize a sinusoidal current output with the grid voltage and accurate an independent active and reactive power control. Simulation results confirm the validation of the purpose. Neurocontroller based active and reactive power presents an efficiency control that guarantees good response to the steps changing in active and reactive power with an acceptable current/voltage synchronism. In this paper the power circuit and the control system of the presented grid-connected photovoltaic generation system is simulated and tested by MatLab/Simulink.

  15. Reactive power control and optimisation of hybrid off shore tidal turbine with system uncertainties

    Directory of Open Access Journals (Sweden)

    Asit Mohanty

    2016-12-01

    Full Text Available This paper projects an isolated hybrid model of Offshore wind-diesel-tidal turbine and discusses the stability and reactive power management issue of the whole system. The hybrid system often loses its stability as it becomes prone to uncertain load and input parameters and therefore the necessity of Reactive power management becomes necessary. The overall stability of the hybrid offshore wind-diesel-tidal turbine is made possible by the management of reactive power in the hybrid system through the application of FACTS devices. And therefore the dynamic hybrid model of the DFIG and DDPMSG based offshore wind-diesel-tidal turbine is analysed for stability with different input parameters like wind and tidal energies. For detailed modelling and simulation, a small signal model of the whole hybrid system is designed and reactive power management of the system is achieved by the incorporation of a STATCOM controller. For improvement of stability and reactive power compensation of the hybrid system, GA and PSO optimised STATCOM controller is used.

  16. Compatibility of Space Nuclear Power Plant Materials in an Inert He/Xe Working Gas Containing Reactive Impurities

    Energy Technology Data Exchange (ETDEWEB)

    MM Hall

    2006-01-31

    A major materials selection and qualification issue identified in the Space Materials Plan is the potential for creating materials compatibility problems by combining dissimilar reactor core, Brayton Unit and other power conversion plant materials in a recirculating, inert He/Xe gas loop containing reactive impurity gases. Reported here are results of equilibrium thermochemical analyses that address the compatibility of space nuclear power plant (SNPP) materials in high temperature impure He gas environments. These studies provide early information regarding the constraints that exist for SNPP materials selection and provide guidance for establishing test objectives and environments for SNPP materials qualification testing.

  17. Transient Control of Synchronous Machine Active and Reactive Power in Micro-grid Power Systems

    Science.gov (United States)

    Weber, Luke G.

    There are two main topics associated with this dissertation. The first is to investigate phase-to-neutral fault current magnitude occurring in generators with multiple zero-sequence current sources. The second is to design, model, and tune a linear control system for operating a micro-grid in the event of a separation from the electric power system. In the former case, detailed generator, AC8B excitation system, and four-wire electric power system models are constructed. Where available, manufacturers data is used to validate the generator and exciter models. A gain-delay with frequency droop control is used to model an internal combustion engine and governor. The four wire system is connected through a transformer impedance to an infinite bus. Phase-to-neutral faults are imposed on the system, and fault magnitudes analyzed against three-phase faults to gauge their severity. In the latter case, a balanced three-phase system is assumed. The model structure from the former case - but using data for a different generator - is incorporated with a model for an energy storage device and a net load model to form a micro-grid. The primary control model for the energy storage device has a high level of detail, as does the energy storage device plant model in describing the LC filter and transformer. A gain-delay battery and inverter model is used at the front end. The net load model is intended to be the difference between renewable energy sources and load within a micro-grid system that has separated from the grid. Given the variability of both renewable generation and load, frequency and voltage stability are not guaranteed. This work is an attempt to model components of a proposed micro-grid system at the University of Wisconsin Milwaukee, and design, model, and tune a linear control system for operation in the event of a separation from the electric power system. The control module is responsible for management of frequency and active power, and voltage and reactive

  18. Genetic algorithms for optimal reactive power compensation planning on the national grid system

    Science.gov (United States)

    Pilgrim, J. D.

    This work investigates the use of Genetic Algorithms (GAs) for optimal Reactive power Compensation Planning (RCP) of practical power systems. In particular, RCP of the transmission system of England and Wales as owned and operated by National Grid is considered. The GA is used to simultaneously solve both the siting problem---optimisation of the installation of new devices---and the operational problem---optimisation of preventive transformer taps and the controller characteristics of dynamic compensation devices. A computer package called Genetic Compensation Placement (GCP) has been developed which uses an Integer coded GA (IGA) to solve the RCP problem. The RCP problem is implemented as a multi-objective optimisation: in the interests of security, the number of system and operational constraint violations and the deviation of the busbar voltages from the ideal are all minimised for the base (intact) case and the contingent cases. In the interests of cost reduction, the reactive power cost is minimised for the base case. The reactive power cost encompasses the costs incurred from the installation of reactive power sources and the utilisation of new and existing dynamic reactive power compensation devices. GCP is compared to SCORPION (a planning program currently being used by National Grid) which uses a combination of linear programming and heuristic back-tracking. Results are presented for a practical test system developed with the cooperation of National Grid, and it is found that GCP produces solutions that are cheaper than solutions found by SCORPION and perform extremely well: an improvement in voltage profiles, a decrease in complex power mismatches, and a reduction in MVolt Amps-reactive (VAr) utilisation were observed.

  19. An Enhanced Quantum-Behaved Particle Swarm Algorithm for Reactive Power Optimization considering Distributed Generation Penetration

    Directory of Open Access Journals (Sweden)

    Runhai Jiao

    2015-01-01

    Full Text Available This paper puts forward a novel particle swarm optimization algorithm with quantum behavior (QPSO to solve reactive power optimization in power system with distributed generation. Moreover, differential evolution (DE operators are applied to enhance the algorithm (DQPSO. This paper focuses on the minimization of active power loss, respectively, and uses QPSO and DQPSO to determine terminal voltage of generators, and ratio of transformers, switching group number of capacitors to achieve optimal reactive power flow. The proposed algorithms are validated through three IEEE standard examples. Comparing the results obtained from QPSO and DQPSO with those obtained from PSO, we find that our algorithms are more likely to get the global optimal solution and have a better convergence. What is more, DQPSO is better than QPSO. Furthermore, with the integration of distributed generation, active power loss has decreased significantly. Specifically, PV distributed generations can suppress voltage fluctuation better than PQ distributed generations.

  20. Voltage Control of Distribution Grids with Multi-Microgrids Using Reactive Power Management

    Directory of Open Access Journals (Sweden)

    WLODARCZYK, P.

    2015-02-01

    Full Text Available Low-voltage Microgrids can be valuable sources of ancillary services for the Distribution System Operators (DSOs. The aim of this paper was to study if and how multi-microgrids can contribute to Voltage Control (VC in medium-voltage distribution grids by means of reactive power generation and/or absorption. The hierarchical control strategy was proposed with the main focus on the tertiary control which was defined as optimal power flow problem. The interior-point algorithm was applied to optimise experimental benchmark grid with the presence of Distributed Energy Resources (DERs. Moreover, two primary objectives were formulated: active power losses and amount of reactive power used to reach the voltage profile. As a result the active power losses were minimised to the high extent achieving the savings around 22% during entire day.

  1. Optimal Coordinated EV Charging with Reactive Power Support in Constrained Distribution Grids

    Energy Technology Data Exchange (ETDEWEB)

    Paudyal, Sumit; Ceylan, Oğuzhan; Bhattarai, Bishnu P.; Myers, Kurt S.

    2017-07-01

    Electric vehicle (EV) charging/discharging can take place in any P-Q quadrants, which means EVs could support reactive power to the grid while charging the battery. In controlled charging schemes, distribution system operator (DSO) coordinates with the charging of EV fleets to ensure grid’s operating constraints are not violated. In fact, this refers to DSO setting upper bounds on power limits for EV charging. In this work, we demonstrate that if EVs inject reactive power into the grid while charging, DSO could issue higher upper bounds on the active power limits for the EVs for the same set of grid constraints. We demonstrate the concept in an 33-node test feeder with 1,500 EVs. Case studies show that in constrained distribution grids in coordinated charging, average costs of EV charging could be reduced if the charging takes place in the fourth P-Q quadrant compared to charging with unity power factor.

  2. Optimal Control of Wind Farms for Coordinated TSO-DSO Reactive Power Management

    Directory of Open Access Journals (Sweden)

    David Sebastian Stock

    2018-01-01

    Full Text Available The growing importance of renewable generation connected to distribution grids requires an increased coordination between transmission system operators (TSOs and distribution system operators (DSOs for reactive power management. This work proposes a practical and effective interaction method based on sequential optimizations to evaluate the reactive flexibility potential of distribution networks and to dispatch them along with traditional synchronous generators, keeping to a minimum the information exchange. A modular optimal power flow (OPF tool featuring multi-objective optimization is developed for this purpose. The proposed method is evaluated for a model of a real German 110 kV grid with 1.6 GW of installed wind power capacity and a reduced order model of the surrounding transmission system. Simulations show the benefit of involving wind farms in reactive power support reducing losses both at distribution and transmission level. Different types of setpoints are investigated, showing the feasibility for the DSO to fulfill also individual voltage and reactive power targets over multiple connection points. Finally, some suggestions are presented to achieve a fair coordination, combining both TSO and DSO requirements.

  3. FUZZY ALGORITHM TO CONTROL REACTIVE POWER FLOW IN ELECTRIC NETWORK WITH NONLINEAR LOADS

    Directory of Open Access Journals (Sweden)

    H. B. Guliyev

    2016-01-01

    Full Text Available One of the important problems of efficient function of electric networks containing load nodes of nonlinear character of power consumption is reactive power compensation and maintaining voltage quality in a grid. The commonly used methods for compensation of harmonic currents by filtering devices make it possible to solve the problem in a narrow band of variation of current of a nonlinear load. In the reality stochastic character of power consumption of nonlinear load reveals itself in appropriate changes in harmonic components of voltage and their share in total load current. This could considerably change the magnitude and direction of reactive power flow in a grid and impair the existing processes of reactive power control. The scheme and the algorithm of control of capacitor banks in networks with non-linear load that are based on the use of fuzzy logic software are presented in the article. The results of model experiments analysis of the modes of the harmonic of the power flows on behalf of the 14-nodal scheme recommended by IEEE as well as the schemes of a real grid with powerful traction substation are presented. The mentioned results demonstrate that when harmonic components of voltages exceed normative magnitudes, the use of the proposed algorithm eliminates additional loading on the capacitor banks with higher harmonic currents whereas the control procedure acquires quality, the number of commutations is being reduced, the capacitor battery functions longer and the probability of its malfunction decreases.

  4. REACTIVE POWER COMPENSATION OF THE TRACTION NETWORK OF THE ELECTRIFIED RAILWAY TRANSPORTATION

    Directory of Open Access Journals (Sweden)

    Berzan V.P.

    2010-08-01

    Full Text Available The method of the parametrical analysis of reactive power compensation of traction network depending on load-ing position on stage between two traction substations is offered. Problem solutions are received in an explicit form at a unilateral and bilateral supplying of complex loading by traction network. The parametrical analysis of active loading influence on characteristics of the compensating devices mounted on low voltage bars of traction substations depending on a site of this loading between power supplies and the loading is made. It is shown, that depending on point of joining of active loading to network and its values the compensating device generally should generate both inductive, and capacitive reactive power for maintenance of power factor value of traction network .

  5. Settlement of reactive power compensation in the light of white certificates

    Directory of Open Access Journals (Sweden)

    Zajkowski Konrad

    2017-01-01

    The detailed method and an estimation method proposed for the determination of savings on active energy as a result of the reactive power compensation carried out possess some errors and inconvenience. The detailed method requires knowledge of the network topology and a determination of reactive power Q at each point of the network. The estimation method of analysis is easy in execution, especially if the consumer of energy is the main or the most significant purchaser of electricity in the network. Unfortunately, this latter method can be used only for activities that do not require high computational accuracy. The results obtained by this method are approximate values that can be used for the calculation of economic indicators. The estimation method is suitable for determining the number of white certificates when a power audit concerns a recipient of electricity, the structure of which is a large number of divisions scattered at many different locations in the power system.

  6. Consensus-based Distributed Control for Accurate Reactive, Harmonic and Imbalance Power Sharing in Microgrids

    DEFF Research Database (Denmark)

    Zhou, Jianguo; Kim, Sunghyok; Zhang, Huaguang

    2017-01-01

    quality at the point of common coupling (PCC). Further, a distributed consensus protocol is developed to adaptively regulate the virtual impedance at fundamental frequency and selected harmonic frequencies. Additionally, a dynamic consensus based method is adopted to restore the voltage to their average......This paper investigates the issue of accurate reactive, harmonic and imbalance power sharing in a microgrid. Harmonic and imbalance droop controllers are developed to proportionally share the harmonic power and the imbalance power among distributed generation (DG) units and improve the voltage...... voltage. With the proposed methods, the microgrid system reliability and flexibility can be enhanced and the knowledge of the line impedance is not required. And the reactive, harmonic and imbalance power can be proportionally shared among the DG units. Moreover, the quality of the voltage at PCC can...

  7. Opposition-Based Improved PSO for Optimal Reactive Power Dispatch and Voltage Control

    Directory of Open Access Journals (Sweden)

    Shengrang Cao

    2015-01-01

    Full Text Available An opposition-based improved particle swarm optimization algorithm (OIPSO is presented for solving multiobjective reactive power optimization problem. OIPSO uses the opposition learning to improve search efficiency, adopts inertia weight factors to balance global and local exploration, and takes crossover and mutation and neighborhood model strategy to enhance population diversity. Then, a new multiobjective model is built, which includes system network loss, voltage dissatisfaction, and switching operation. Based on the market cost prices, objective functions are converted to least-cost model. In modeling process, switching operation cost is described according to the life cycle cost of transformer, and voltage dissatisfaction penalty is developed considering different voltage quality requirements of customers. The experiment is done on the new mathematical model. Through the simulation of IEEE 30-, 118-bus power systems, the results prove that OIPSO is more efficient to solve reactive power optimization problems and the model is more accurate to reflect the real power system operation.

  8. Dynamic power management for reactive stream processing on the SCC tiled architecture

    National Research Council Canada - National Science Library

    Karavadara, Nilesh; Zolda, Michael; Nga Nguyen, Vu Thien; Knoop, Jens; Kirner, Raimund

    2016-01-01

    .... Many modern processors support some form of DVFS.In this article, we focus on the development of an execution framework that provides lightweight DVFS support for reactive stream processing systems (RSPS...

  9. Reactive Power Control for Improving Wind Turbine System Behavior Under Grid Faults

    DEFF Research Database (Denmark)

    Rodriguez, P.; Timbus, A.; Teodorescu, Remus

    2009-01-01

    This letter aims to present a generalized vector-based formulation for calculating the grid-side current reference to control reactive power delivered to the grid. Strategies for current reference generation were implemented on the abc stationary reference frame, and their effectivenesswas demons...

  10. Reactive Power Sharing and Voltage Harmonic Distortion Compensation of Droop Controlled Single Phase Islanded Microgrids

    DEFF Research Database (Denmark)

    Micallef, Alexander; Apap, Maurice; Spiteri-Staines, Cyril

    2014-01-01

    and reduction of the voltage harmonic distortion at the point of common coupling (PCC). Experimental results were then presented to show the suitability of the proposed algorithms in achieving reactive power sharing and in improving the voltage harmonic distortion at the PCC....

  11. Settlement of reactive power compensation in the light of white certificates

    Science.gov (United States)

    Zajkowski, Konrad

    2017-10-01

    The article discusses the problem of the determination of savings on active energy as a result of a reactive power compensation. Statutory guidance on the required energy audit to obtain white certificates in the European Union was followed. The analysis was made on the basis of the Polish Law. The paper presents a detailed analytical method and an estimation method taking into account the impact on the line, the transformer and the generator. According to the relevant guidelines in the European Union, the reduction of CO2 emissions by calculating the saving of active power should be determined. The detailed method and an estimation method proposed for the determination of savings on active energy as a result of the reactive power compensation carried out possess some errors and inconvenience. The detailed method requires knowledge of the network topology and a determination of reactive power Q at each point of the network. The estimation method of analysis is easy in execution, especially if the consumer of energy is the main or the most significant purchaser of electricity in the network. Unfortunately, this latter method can be used only for activities that do not require high computational accuracy. The results obtained by this method are approximate values that can be used for the calculation of economic indicators. The estimation method is suitable for determining the number of white certificates when a power audit concerns a recipient of electricity, the structure of which is a large number of divisions scattered at many different locations in the power system.

  12. Optimal reactive power planning for distribution systems considering intermittent wind power using Markov model and genetic algorithm

    Science.gov (United States)

    Li, Cheng

    Wind farms, photovoltaic arrays, fuel cells, and micro-turbines are all considered to be Distributed Generation (DG). DG is defined as the generation of power which is dispersed throughout a utility's service territory and either connected to the utility's distribution system or isolated in a small grid. This thesis addresses modeling and economic issues pertaining to the optimal reactive power planning for distribution system with wind power generation (WPG) units. Wind farms are inclined to cause reverse power flows and voltage variations due to the random-like outputs of wind turbines. To deal with this kind of problem caused by wide spread usage of wind power generation, this thesis investigates voltage and reactive power controls in such a distribution system. Consequently static capacitors (SC) and transformer taps are introduced into the system and treated as controllers. For the purpose of getting optimum voltage and realizing reactive power control, the research proposes a proper coordination among the controllers like on-load tap changer (OLTC), feeder-switched capacitors. What's more, in order to simulate its uncertainty, the wind power generation is modeled by the Markov model. In that way, calculating the probabilities for all the scenarios is possible. Some outputs with consecutive and discrete values have been used for transition between successive time states and within state wind speeds. The thesis will describe the method to generate the wind speed time series from the transition probability matrix. After that, utilizing genetic algorithm, the optimal locations of SCs, the sizes of SCs and transformer taps are determined so as to minimize the cost or minimize the power loss, and more importantly improve voltage profiles. The applicability of the proposed method is verified through simulation on a 9-bus system and a 30-bus system respectively. At last, the simulation results indicate that as long as the available capacitors are able to sufficiently

  13. Reduced Cost of Reactive Power in Doubly Fed Induction Generator Wind Turbine System With Optimized Grid Filter

    DEFF Research Database (Denmark)

    Zhou, Dao; Blaabjerg, Frede; Franke, Toke

    2015-01-01

    The modern grid requirement has caused that the wind power system behaves more like conventional rotating generators, and it is able to support certain amount of the reactive power. For a typical doubly fed induction generator (DFIG) wind turbine system, the reactive power can be supported either...... for the generator and the wind power converter in terms of the reactive power done by the rotor-side converter or the grid-side converter with various grid filters. Afterward, the annual energy loss is also estimated based on yearly wind profile. Finally, experimental results of the loss distribution are performed...... with the optimized filter and thereby more energy production for the wind turbine....

  14. Combined Active and Reactive Power Control of Wind Farms based on Model Predictive Control

    DEFF Research Database (Denmark)

    Zhao, Haoran; Wu, Qiuwei; Wang, Jianhui

    2017-01-01

    the sensitivity coefficients to improve the computation efficiency and overcome the convergence problem. Two control modes are designed for both normal and emergency conditions. A wind farm with 20 wind turbines was used to verify the proposed combined control scheme.......This paper proposes a combined wind farm controller based on Model Predictive Control (MPC). Compared with the conventional decoupled active and reactive power control, the proposed control scheme considers the significant impact of active power on voltage variations due to the low X=R ratio...... of wind farm collector systems. The voltage control is improved. Besides, by coordination of active and reactive power, the Var capacity is optimized to prevent potential failures due to Var shortage, especially when the wind farm operates close to its full load. An analytical method is used to calculate...

  15. Reactive power generation in high speed induction machines by continuously occurring space-transients

    Science.gov (United States)

    Laithwaite, E. R.; Kuznetsov, S. B.

    1980-09-01

    A new technique of continuously generating reactive power from the stator of a brushless induction machine is conceived and tested on a 10-kw linear machine and on 35 and 150 rotary cage motors. An auxiliary magnetic wave traveling at rotor speed is artificially created by the space-transient attributable to the asymmetrical stator winding. At least two distinct windings of different pole-pitch must be incorporated. This rotor wave drifts in and out of phase repeatedly with the stator MMF wave proper and the resulting modulation of the airgap flux is used to generate reactive VA apart from that required for magnetization or leakage flux. The VAR generation effect increases with machine size, and leading power factor operation of the entire machine is viable for large industrial motors and power system induction generators.

  16. An Enhanced Instantaneous Circulating Current Control for Reactive power and Harmonic Load Sharing in Islanded Microgrids

    DEFF Research Database (Denmark)

    Lorzadeh, Iman; Askarian Abyaneh, Hossein; Savaghebi, Mehdi

    2017-01-01

    To address inaccurate load demand sharing problems among parallel inverter-interfaced voltage-controlled distributed generation (DG) units in islanded microgrids with different DG power ratings and mismatched feeder impedances, an enhanced voltage control scheme based on actively compensation...... branches, the reactive power and harmonic currents can be independently shared without having remarkable effects on the amplitude and quality of the DGs voltage, even if nonlinear (harmonic) loads are directly connected at the output terminal of units. In addition, the accurate load sharing can also...... of circulating voltage drops is proposed in this paper. Using proposed strategy, reactive power and harmonic currents sharing are shared accurately and proportionally without knowledge of feeder impedances. As the proposed local controller consists of two well-separated fundamental and harmonic voltage control...

  17. Optimal Day-Ahead Scheduling of a Smart Distribution Grid Considering Reactive Power Capability of Distributed Generation

    Directory of Open Access Journals (Sweden)

    Rongxiang Yuan

    2016-04-01

    Full Text Available In the traditional paradigm, large power plants provide active and reactive power required for the transmission system and the distribution network purchases grid power from it. However, with more and more distributed energy resources (DERs connected at distribution levels, it is necessary to schedule DERs to meet their demand and participate in the electricity markets at the distribution level in the near future. This paper proposes a comprehensive operational scheduling model to be used in the distribution management system (DMS. The model aims to determine optimal decisions on active elements of the network, distributed generations (DGs, and responsive loads (RLs, seeking to minimize the day-ahead composite economic cost of the distribution network. For more detailed simulation, the composite cost includes the aspects of the operation cost, emission cost, and transmission loss cost of the network. Additionally, the DMS effectively utilizes the reactive power support capabilities of wind and solar power integrated in the distribution, which is usually neglected in previous works. The optimization procedure is formulated as a nonlinear combinatorial problem and solved with a modified differential evolution algorithm. A modified 33-bus distribution network is employed to validate the satisfactory performance of the proposed methodology.

  18. New Approach to Optimize the Apfs Placement Based on Instantaneous Reactive Power Theory by Genetic Algorithm

    Science.gov (United States)

    Hashemi-Dezaki, Hamed; Mohammadalizadeh-Shabestary, Masoud; Askarian-Abyaneh, Hossein; Rezaei-Jegarluei, Mohammad

    2014-01-01

    In electrical distribution systems, a great amount of power are wasting across the lines, also nowadays power factors, voltage profiles and total harmonic distortions (THDs) of most loads are not as would be desired. So these important parameters of a system play highly important role in wasting money and energy, and besides both consumers and sources are suffering from a high rate of distortions and even instabilities. Active power filters (APFs) are innovative ideas for solving of this adversity which have recently used instantaneous reactive power theory. In this paper, a novel method is proposed to optimize the allocation of APFs. The introduced method is based on the instantaneous reactive power theory in vectorial representation. By use of this representation, it is possible to asses different compensation strategies. Also, APFs proper placement in the system plays a crucial role in either reducing the losses costs and power quality improvement. To optimize the APFs placement, a new objective function has been defined on the basis of five terms: total losses, power factor, voltage profile, THD and cost. Genetic algorithm has been used to solve the optimization problem. The results of applying this method to a distribution network illustrate the method advantages.

  19. Reliability Analysis of Single-Phase PV Inverters with Reactive Power Injection at Night Considering Mission Profiles

    DEFF Research Database (Denmark)

    Anurag, Anup; Yang, Yongheng; Blaabjerg, Frede

    2015-01-01

    , especially at night when there is no solar irradiance. This serves as a motivation for utilizing the PV inverters at night for reactive power compensation. Thus, an analysis on the impact of reactive power injection by PV inverters outside feed-in operation on the thermal performance and the reliability has...... loading, considering the operation outside active feed-in hours. An analytical lifetime model is then employed for lifetime quantization based on the Palgrem Miner rule. Thereafter, considering the lifetime reduction of the PV inverter under different mission profiles with reactive power injection...... at night, the impact of PV sites on the economic value of the inverter is assessed. This analysis can be useful in choosing between conventional reactive power compensation devices or PV inverters for injecting reactive power to the grid....

  20. Reduced Cost of Reactive Power in Doubly Fed Induction Generator Wind Turbine System with Optimized Grid Filter

    DEFF Research Database (Denmark)

    Zhou, Dao; Blaabjerg, Frede; Franke, Toke

    2014-01-01

    the rotor-side converter or the grid-side converter. This paper firstly compares the current ripples and supportive reactive power ranges between the conventional L and optimized LCL filter, if the reactive power is injected from the grid-side converter. Then, the loss distribution is evaluated both...... for the generator and the wind power converter in terms of the reactive power done by the rotor-side converter or the grid-side converter with various grid filters. Afterwards, the annual energy loss is also estimated based on yearly wind profile. Finally, experimental results of the loss distribution are performed...

  1. An Improved Droop Control Strategy for Reactive Power Sharing in Islanded Microgrid

    DEFF Research Database (Denmark)

    Han, Hua; Liu, Yao; Sun, Yao

    2015-01-01

    For microgrid in islanded operation, due to the effects of mismatched line impedance, the reactive power could not be shared accurately with the conventional droop method. To improve the reactive power sharing accuracy, this paper proposes an improved droop control method. The proposed method...... mainly includes two important operations: error reduction operation and voltage recovery operation. The sharing accuracy is improved by the sharing error reduction operation, which is activated by the low-bandwidth synchronization signals. However, the error reduction operation will result in a decrease...... in output voltage amplitude. Therefore, the voltage recovery operation is proposed to compensate the decrease. The needed communication in this method is very simple, and the plug-and-play is reserved. Simulations and experimental results show that the improved droop controller can share load active...

  2. An Optimized Reactive Power Control of Distributed Solar Inverters in Low Voltage Networks

    DEFF Research Database (Denmark)

    Demirok, Erhan; Sera, Dezso; Teodorescu, Remus

    2011-01-01

    This study examines the reactive power ancillary services of solar inverters which are connected to low voltage (LV) distribution networks by giving attention to the grid voltage support service and grid losses. Two typical reference LV distribution network models as suburban and farm...... are introduced from the literature in order to evaluate contribution of two static droop strategies cosφ(P) and Q(U) on the grid voltage. Photovoltaic (PV) hosting capacities of the suburban and farm networks are estimated and the most predominant limitations of connecting more solar inverters are emphasized...... for each network type. Regarding the overloading of MV/LV distribution transformers, overloading of lines and the grid overvoltage limitations, new local grid voltage support methods (cosφ(P,U) and Q(U,P)) are also proposed. Resulting maximum allowable penetration levels with different reactive power...

  3. Measurement based analysis of active and reactive power losses in a distribution network with wind farms and CHPs

    DEFF Research Database (Denmark)

    Lund, Torsten

    2007-01-01

    The paper presents an investigation of the active and reactive power losses in a distribution network with wind turbines and combined heat and power plants. The investigation is based on 15 min average power measurements and load flow calculations in the power system simulation tool Power......Factory®. Based on the measurements and simulations, a regressive model for calculation and allocation of active and reactive power losses has been derived. The influence of the covariance between load and production on the system losses is investigated separately....

  4. Evaluation of reactive power support interactions among PV systems using sensitivity analysis

    Energy Technology Data Exchange (ETDEWEB)

    Samadi, Afshin; Eriksson, Robert; Soeder, Lennart [KTH Royal Institute of Technology, Stockholm (Sweden). Dept. of Electric Power Systems

    2012-07-01

    Growing trends in generating power from distributed PhotoVoltaic (PV) systems has accommodated more and more PV systems within load pockets in distribution grid. This high penetration has brought about new challenges such as voltage profile violation, reverse load flow and etc. A few remedies have been imposed by grid codes such as reactive power contribution of PV systems and active power curtailment. This study applies two analytical methods from control science to find the possibility of controllability among the PV systems in a distribution grid for voltage profile control at specific set-points through reactive poser regulation and active power curtailment. For this purpose, the voltage sensitivity matrix is used as the steady-state gain of the multi-variable system. The first method is Relative Gain Array (RGA), in which RGA of the voltage sensitivity matrix is utilized as a quantitative measure to address controllability and the level of voltage control interaction among PV systems. The second method is Condition Number (CN), in which Singular Value Decomposition (SVD) of the voltage sensitivity matrix is used as a mathematical measure to indicate the voltage control directionality among PV systems. Two radial test distribution grids with different feeder R/X ratio, overhead line and underground cable, which consist of five PV systems, are used to calculate load flow and, in turn, voltage sensitivity matrix. The results demonstrate that decentralized voltage control to specific set-points is basically impossible in the both system. It is also shown that voltage control directionality of the both systems is increased by reactive power regulation compared to active power curtailing. (orig.)

  5. Principles for construction the compensators of reactive power with voltage stabilization for transformer substations

    Science.gov (United States)

    Vlasayevsky, Stanislav; Klimash, Stepan; Klimash, Vladimir

    2017-10-01

    Based on the booster transformer and the transistor converter with a DC link, a system is proposed for fast and accurate unloading the electric network from reactive power with simultaneous stabilization of voltage among consumers. The system contains a discrete stage of reactive power compensation and adjustable part. The adjustable part includes series and parallel reactive power compensators. The series compensator consists of a booster transformer, a voltage inverter and is designed to be switched on to the high voltage of the transformer substations. The parallel compensator consists of a rectifier with an input choke and is connected to the low voltage of the substation. The rectifier and inverter are connected by a DC link with an LC filter. The rectifier regulates the output voltage and the phase of the sinusoidal input current. The inverter regulates the magnitude and phase of the voltage on the control winding of the booster transformer. The rectifier and inverter control systems are synchronized with the network and with pulse width modulation.

  6. Atmosphere Clouds Model Algorithm for Solving Optimal Reactive Power Dispatch Problem

    Directory of Open Access Journals (Sweden)

    Lenin Kanagasabai

    2014-04-01

    Full Text Available In this paper, a new method, called Atmosphere Clouds Model (ACM algorithm, used for solving optimal reactive power dispatch problem. ACM stochastic optimization algorithm stimulated from the behavior of cloud in the natural earth. ACM replicate the generation behavior, shift behavior and extend behavior of cloud. The projected (ACM algorithm has been tested on standard IEEE 30 bus test system and simulation results shows clearly about the superior performance of the proposed algorithm in plummeting the real power loss. Normal 0 false false false EN-IN X-NONE X-NONE

  7. Measured effects of wind turbine reactive power control on an isolated utility

    Energy Technology Data Exchange (ETDEWEB)

    Smith, R.F.; Shaltens, R.K.; Wilreker, V.F.

    1984-06-01

    One phase of an overall effort in evaluating performance of a 150 kW MOD-OA wind turbine connected to the Block Island Power Company (BIPCO) system consisted in analyzing three methods of excitation (reactive power) control. These are identified as: 1) constant var (reactive), 2) constant voltage, and 3) constant power factor (PF) control. The power system environment in which the wind turbine generator (WTG) exists ultimately determines which method of control is the most suitable. In the case of the BIPCO installation, the major emphasis was to insure sufficient WTG electrical torque during wind gusts in low power output periods. Subsequent use of constant PF control demonstrated an adequacy of performance equivalent to that of constant var control while constant voltage control indicated a diminished capacity to maintain synchronism with the utility, when compared to constant var or PF control. A mathematical model which incorporates the detailed excitation system transfer functions is used to compare the results indicated by the measurements produced during a three-month data acquisition effort.

  8. TLBO based Voltage Stable Environment Friendly Economic Dispatch Considering Real and Reactive Power Constraints

    Science.gov (United States)

    Verma, H. K.; Mafidar, P.

    2013-09-01

    In view of growing concern towards environment, power system engineers are forced to generate quality green energy. Hence the economic dispatch (ED) aims at the power generation to meet the load demand at minimum fuel cost with environmental and voltage constraints along with essential constraints on real and reactive power. The emission control which reduces the negative impact on environment is achieved by including the additional constraints in ED problem. Presently, the power system mostly operates near its stability limits, therefore with increased demand the system faces voltage problem. The bus voltages are brought within limit in the present work by placement of static var compensator (SVC) at weak bus which is identified from bus participation factor. The optimal size of SVC is determined by univariate search method. This paper presents the use of Teaching Learning based Optimization (TLBO) algorithm for voltage stable environment friendly ED problem with real and reactive power constraints. The computational effectiveness of TLBO is established through test results over particle swarm optimization (PSO) and Big Bang-Big Crunch (BB-BC) algorithms for the ED problem.

  9. Distributed Operation of Interlinked AC Microgrids with Dynamic Active and Reactive Power Tuning

    DEFF Research Database (Denmark)

    Nutkani, Inam Ullah; Loh, Poh Chiang; Blaabjerg, Frede

    2013-01-01

    Microgrids are small grids formed by clustering modern generating sources, storage systems, and loads together. Being independent, the formed microgrids can, in principle, operate at their own preferred voltages and frequencies. Tying them to the mains grid or another microgrid would therefore...... require some interlinking power converters, whose control should preferably be autonomous without depending on fast communication links. Contributing to this theme of research, a distributed power management scheme has been proposed in this paper for interlinking two or more independent microgrids...... operating at different voltages and frequencies. The proposed scheme allows sources in the microgrids to concentrate more on active power harnessing, while the interlinking converters focus more on meeting the load reactive demand. If necessary, backup active power from an underloaded microgrid can also...

  10. Transaction of long-term power purchasing contract by independent power providers in wholesale and retail competitive system

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung Hoon [Korea Energy Economics Institute, Euiwang (Korea)

    1998-12-01

    In general, the restructuring starts with separation and division of power sector from the existing monopolist as the cases of Thailand and Malaysia. When the power provider is separated and divided, it becomes an independent power provider. The existing regional electricity provider carries out the supplying function to end-users buying electricity from several separated and divided providers. Therefore, the existing regional electricity providers give up the power generation business but become a demand monopolist in wholesale market. The competition system capable of applying during the separation period is the Generation Pool. With the Generation Pool, it is able to promote competition of power generation sector effectively and there is no need to have an extra step such as long-term power purchasing contract. In fact, Latin America and Chile have been managed the power market for more than 10 years with the competition system by the Generation Pool. 9 refs.

  11. Method and apparatus to provide power conversion with high power factor

    Science.gov (United States)

    Perreault, David J.; Lim, Seungbum; Otten, David M.

    2017-05-23

    A power converter circuit rectifies a line voltage and applies the rectified voltage to a stack of capacitors. Voltages on the capacitors are coupled to a plurality of regulating converters to be converted to regulated output signals. The regulated output signals are combined and converted to a desired DC output voltage of the power converter. Input currents of the regulating converters are modulated in a manner that enhances the power factor of the power converter.

  12. Efficient and Reliable Reactive Power Supply and Consumption --Insights from an Integrated Program of Engineering and EconomicResearch

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Robert J.; Mount, Timothy D.; Schuler, Richard; Schulze,William; Zimmerman, Ray; Alvarado, Fernando; Lesieutre, Bernard C.; Overholt, Philip N.; Eto, Joseph H.

    2008-01-01

    In 2005, the Federal Energy Regulatory Commission (FERC) began discussing regulatory policy for reactive-power procurement and pricing in competitive electricity markets. This paper summarizes findings from a unique, interdisciplinary program of public-interest research that lays a formal foundation for evaluating aspects of FERC staff recommendations and offers early insights that should be useful in guiding policy implementation, specifically by: (1) clarifying the consumers and economic characteristics of reactive power as a basis for creating incentives to appropriately price it, (2) defining specific challenges in creating a competitive market for reactive power as well as new tools needed to help ensure such a market functions efficiently, and (3) demonstrating the importance of accounting for the physical characteristics of the transmission network in planning for reactive power and avoiding the exercise of market power by suppliers.

  13. Coordination of voltage and reactive power control in the extra high voltage substations based on the example of solutions applied in the national power system

    Directory of Open Access Journals (Sweden)

    Dariusz Kołodziej

    2012-06-01

    Full Text Available This paper presents examples of coordination between automatic voltage and reactive power control systems (ARST covering adjacent and strongly related extra high voltage substations. Included are conclusions resulting from the use of these solutions. The Institute of Power Engineering, Gdańsk Division has developed and deployed ARST systems in the national power system for a dozen or so years.

  14. Recursive Pyramid Algorithm-Based Discrete Wavelet Transform for Reactive Power Measurement in Smart Meters

    Directory of Open Access Journals (Sweden)

    Mahin K. Atiq

    2013-09-01

    Full Text Available Measurement of the active, reactive, and apparent power is one of the most fundamental tasks of smart meters in energy systems. Recently, a number of studies have employed the discrete wavelet transform (DWT for power measurement in smart meters. The most common way to implement DWT is the pyramid algorithm; however, this is not feasible for practical DWT computation because it requires either a log N cascaded filter or O (N word size memory storage for an input signal of the N-point. Both solutions are too expensive for practical applications of smart meters. It is proposed that the recursive pyramid algorithm is more suitable for smart meter implementation because it requires only word size storage of L × Log (N-L, where L is the length of filter. We also investigated the effect of varying different system parameters, such as the sampling rate, dc offset, phase offset, linearity error in current and voltage sensors, analog to digital converter resolution, and number of harmonics in a non-sinusoidal system, on the reactive energy measurement using DWT. The error analysis is depicted in the form of the absolute difference between the measured and the true value of the reactive energy.

  15. Systems and methods for providing power to a load based upon a control strategy

    Energy Technology Data Exchange (ETDEWEB)

    Perisic, Milun; Lawrence, Christopher P; Ransom, Ray M; Kajouke, Lateef A

    2014-11-04

    Systems and methods are provided for an electrical system. The electrical system, for example, includes a first load, an interface configured to receive a voltage from a voltage source, and a controller configured to receive the voltage through the interface and to provide a voltage and current to the first load. The controller may be further configured to, receive information on a second load electrically connected to the voltage source, determine an amount of reactive current to return to the voltage source such that a current drawn by the electrical system and the second load from the voltage source is substantially real, and provide the determined reactive current to the voltage source.

  16. Simplified reactive power management strategy for complex power grids under stochastic operation and incomplete information

    DEFF Research Database (Denmark)

    Vlachogiannis, Ioannis (John)

    2009-01-01

    In the current released energy market, the large-scale complex transmission networks and the distribution ones with dispersed energy sources and "intelligent" components operate under uncertainties, stochastic and prior incomplete information. A safe and reliable operation of such complex power g...... consider more stochastic aspects such as variable grid's topology. Results of the proposed strategy obtained on the networks of IEEE 30-bus and IEEE 118-bus systems demonstrate the effectiveness of the proposed strategy....

  17. A new approach for three-phase loads compensation based on the instantaneous reactive power theory

    Energy Technology Data Exchange (ETDEWEB)

    Salmeron, Patricio; Herrera, Reyes S.; Vazquez, Jesus R. [Electrical Engineering Department of the University of Huelva (Spain)

    2008-04-15

    The original instantaneous reactive power theory or p-q theory has been systematically used in the control of active power filters (APFs). When the APF is connected in parallel to a non-linear and unbalanced load, the p-q theory application has allowed a compensation strategy named constant power to be obtained. This means that, after the APF connection, the instantaneous power supplied by the source is constant and it has the same value as the average power consumed by the load. Nevertheless, the use of other compensation strategies is possible: unity power factor or sinusoidal and balanced supply currents, among others. This paper shows that any compensation strategy may be developed into the p-q theory frame. Besides, the paper presents a p-q theory reformulation without using mapping matrices, which makes easier the obtention of the compensation currents. Finally, an exhaustive analysis of practical cases has been carried out at simulation and experimental level through a laboratory prototype which has allowed the proposed approach to be verified. (author)

  18. Photovoltaic Hosting Capacity of Feeders with Reactive Power Control and Tap Changers

    Energy Technology Data Exchange (ETDEWEB)

    Ceylan, Oğuzhan; Paudyal, Sumit; Bhattarai, Bishnu P.; Myers, Kurt S.

    2017-06-01

    This paper proposes an algorithm to determine photovoltaic (PV) hosting capacity of power distribution networks as a function of number of PV injection nodes, reactive power support from the PVs, and the sub-station load tap changers (LTCs). In the proposed method, several minute by minute simulations are run based on randomly chosen PV injection nodes, daily PV output profiles, and daily load profiles from a pool of high-resolution realistic data set. The simulation setup is built using OpenDSS and MATLAB. The performance of the proposed method is investigated in the IEEE 123-node distribution feeder for multiple scenarios. The case studies are performed particularly for one, two, five and ten PV injection nodes, and looking at the maximum voltage deviations. Case studies show that the PV hosting capacity of the 123-node feeder greatly differs with the number of PV injection nodes. We have also observed that the PV hosting capacity increases with reactive power support and higher tap position of sub-station LTC.

  19. Voltage stability in low voltage microgrids in aspects of active and reactive power demand

    Directory of Open Access Journals (Sweden)

    Parol Mirosław

    2016-03-01

    Full Text Available Low voltage microgrids are autonomous subsystems, in which generation, storage and power and electrical energy consumption appear. In the paper the main attention has been paid to the voltage stability issue in low voltage microgrid for different variants of its operation. In the introduction a notion of microgrid has been presented, and also the issue of influence of active and reactive power balance on node voltage level has been described. Then description of voltage stability issue has been presented. The conditions of voltage stability and indicators used to determine voltage stability margin in the microgrid have been described. Description of the low voltage test microgrid, as well as research methodology along with definition of considered variants of its operation have been presented further. The results of exemplary calculations carried out for the daily changes in node load of the active and reactive power, i.e. the voltage and the voltage stability margin indexes in nodes have been presented. Furthermore, the changes of voltage stability margin indexes depending on the variant of the microgrid operation have been presented. Summary and formulation of conclusions related to the issue of voltage stability in microgrids have been included at the end of the paper.

  20. Study on offshore wind farm integration mode and reactive power compensation

    Energy Technology Data Exchange (ETDEWEB)

    Bian, Xiaoyan; Hong, Lijun; Fu, Yang [Shanghai Univ. of Electrical Power (China). Power and Automation Engineering Dept.

    2013-07-01

    Two typical offshore wind farm grid-connected modes are introduced and dynamic characteristics under their modes are compared from the simulation by PSS/E. The result shows that offshore wind farm with VSC-HVDC has better dynamic characteristics on fault isolation, reactive power compensation, and fault ride through ability. In addition, STATCOM has been applied to the offshore wind farm, the simulation results indicates that it can improve the bus voltage stability in fault and maintain the voltage level under a small perturbation.

  1. A Comprehensive LVRT Control Strategy for DFIG Wind Turbines With Enhanced Reactive Power Support

    DEFF Research Database (Denmark)

    Xie, Dongliang; Xu, Zhao; Yang, Lihui

    2013-01-01

    The paper presents a new control strategy to enhance the ability of reactive power support of a doubly fed induction generator (DFIG) based wind turbine during serious voltage dips. The proposed strategy is an advanced low voltage ride through (LVRT) control scheme, with which a part...... of the captured wind energy during grid faults is stored temporarily in the rotor's inertia energy and the remaining energy is available to the grid while the DC-link voltage and rotor current are kept below the dangerous levels. After grid fault clearance, the control strategy ensures smooth release of the rotor...

  2. Active and reactive power support of MV distribution systems using battery energy storage

    DEFF Research Database (Denmark)

    Wang, Jiawei; Hashemi Toghroljerdi, Seyedmostafa; You, Shi

    2017-01-01

    Adoption of Battery Energy Storage Systems (BESSs) for provision of grid services is increasing. This paper investigates the applications of BESS for the grid upgrade deferral and voltage support of Medium Voltage (MV) distribution systems. A BESS is modelled in Matlab/Simulink to perform peak load...... shaving and voltage support service from the perspective of Distribution System Operators (DSOs). An active power support algorithm is implemented and the effects of various load profiles as well as different Photovoltaic (PV) penetration scenarios on the operation of BESS and the optimal BESS converter...... size for peak load shaving are investigated. The BESS annual lifetime degradation is also estimated using a rainflow counting algorithm. A reactive power support algorithm embedded with Q-U droop control is proposed in order to reduce the voltage drop in a part of 10 kV distribution network of Nordhavn...

  3. Effects of Radial Reflector Composition on Core Reactivity and Peak Power

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sang Yoon; Lee, Kyung Hoon; Song, Jae Seung

    2007-10-15

    The effects of radial SA-240 alloy shroud on core reactivity and peak power are evaluated. The existence of radial SA-240 alloy shroud makes reflector water volume decrease, so the thermal absorption cross section of radial reflector is lower than without SA-240 alloy shroud case. Finally, the cycle length is increased from 788 EFPD to 845 EFPD and the peak power is decreased from 1.66 to 1.49. In the case of without SA-240 alloy shroud, a new core loading pattern search has been performed. For the guarantee of the same equivalent cycle length of with SA-240 alloy shroud case, the enrichment of U-235 should be increased from 4.22 w/o to 4.68 w/o. The nuclear key safety parameters of new core loading pattern have been calculated and recorded for the future.

  4. Solar pv fed stand-alone excitation system of a synchronous machine for reactive power generation

    Science.gov (United States)

    Sudhakar, N.; Jain, Siddhartha; Jyotheeswara Reddy, K.

    2017-11-01

    This paper presents a model of a stand-alone solar energy conversion system based on synchronous machine working as a synchronous condenser in overexcited state. The proposed model consists of a Synchronous Condenser, a DC/DC boost converter whose output is fed to the field of the SC. The boost converter is supplied by the modelled solar panel and a day time variable irradiance is fed to the panel during the simulation time. The model also has one alternate source of rechargeable batteries for the time when irradiance falls below a threshold value. Also the excess power produced when there is ample irradiance is divided in two parts and one is fed to the boost converter while other is utilized to recharge the batteries. A simulation is done in MATLAB-SIMULINK and the obtained results show the utility of such modelling for supplying reactive power is feasible.

  5. Reactive Power Management in Islanded Microgrid – Proportional Power Sharing in Hierarchical Droop Control

    DEFF Research Database (Denmark)

    Milczarek, Adam; Malinowski, Mariusz; Guerrero, Josep M.

    2015-01-01

    A microgrid (MG) is a local energy system consisting a number of energy sources (e.g. wind turbine or solar panels among others), energy storage units and loads that operate connected to the main electrical grid or autonomously. MGs provide flexibility, reduce the main electricity grid dependence...

  6. 18 CFR 2.22 - Pricing policy for transmission services provided under the Federal Power Act.

    Science.gov (United States)

    2010-04-01

    ... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Pricing policy for... INTERPRETATIONS Statements of General Policy and Interpretations Under the Federal Power Act § 2.22 Pricing policy... Policy Statement on its pricing policy for transmission services provided under the Federal Power Act...

  7. Reactive Power Management in Islanded Microgrid – Proportional Power Sharing in Hierarchical Droop Control

    OpenAIRE

    Milczarek, Adam; Malinowski, Mariusz; Guerrero, Josep M.

    2015-01-01

    A microgrid (MG) is a local energy system consisting a number of energy sources (e.g. wind turbine or solar panels among others), energy storage units and loads that operate connected to the main electrical grid or autonomously. MGs provide flexibility, reduce the main electricity grid dependence and contribute to change the large centralized production paradigm to local and distributed generation. However, such energy systems require complex management, advanced control and optimization. Mor...

  8. Lanthanide ions (III) as sensitizers of melatonin oxidation in reaction mixtures providing reactive species of oxygen and nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Kaczmarek, Małgorzata, E-mail: mkaczmar@amu.edu.pl

    2015-06-15

    Chemiluminescence (CL) of the reactive systems providing strong oxidants (reactive species of oxygen and nitrogen) containing lanthanide ions (III) and melatonin, was studied. Kinetic curves of emission decay and spectral distributions of chemiluminescence were obtained. Analysis of differences in the intensity of chemiluminescence and CL spectra proved that excitation of Tb(III) and Dy(III) ions takes place with the energy transfer from the products of melatonin oxidation: N{sup 1}-acetyl-N{sup 2}-formyl-5-methoxykynuramine (AFMK) and N{sup 1}-acetyl-5-methoxykynuramine (AMK) to the lanthanide ions. In the system Fe(II)/Fe(III)–H{sub 2}O{sub 2}–Mel–Tb(III) a linear correlation was established between the integrated CL intensity and melatonin concent. - Highlights: • Chemiluminescence (CL) of melatonin (Mel) oxidation by reactive species of oxygen and nitrogen. • Tb(III) and Dy(III) ions as sensitizers of a melatonin oxidation process. • New CL method for determination of melatonin in pharmaceutical preparations based on CL of Fe(II)/Fe(III)–H{sub 2}O{sub 2}–Mel–Tb(III) system.

  9. Reduction of DC-link Capacitor in Case of Cascade Multilevel Converters by means of Reactive Power Control

    DEFF Research Database (Denmark)

    Gohil, Ghanshyamsinh Vijaysinh; Wang, Huai; Liserre, Marco

    2014-01-01

    A method to selectively control the amount of dc link voltage ripple by processing desired reactive power by a DC/DC converter in isolated AC/DC or AC/DC/AC system is proposed. The concept can reduce the dc link capacitors used for balancing the input and output power and thereby limiting the vol...

  10. Mix of power system flexibility means providing 50 % wind power penetration in the Danish power system in 2030

    DEFF Research Database (Denmark)

    Nørgård, Per; Lund, Henrik; Mathiesen, Brian Vad

    2008-01-01

    Time series simulations of an example of a realistic modified energy system in Denmark 2030, assuming no internal power transmission bottlenecks, indicates that it is both technical possible and economic feasible to maintain the energy balance on hourly basis, even with a wind power penetration...

  11. Impact of wind power plant reactive current injection during asymmetrical grid faults

    DEFF Research Database (Denmark)

    Göksu, Ömer; Teodorescu, Remus; Bak, Claus Leth

    2013-01-01

    ) are requested to stay connected and inject positive-sequence reactive current in order to boost positive-sequence grid voltage during short-circuit grid faults, irrespective of the fault type; symmetrical or asymmetrical. However, as shown in this study, when WPPs inject pure positive-sequence reactive current...... in case of asymmetrical faults, as a conventional method (CM) in accordance with the grid code requirement, positive-sequence grid voltage is boosted, but also higher negative sequence voltage in the grid and higher overvoltages at the non-faulty phases occur. In this study, an alternative injection...... method, where WTs are injecting both positive and negative sequence currents during asymmetrical faults, providing improved grid support, is given and compared with the CM. In addition, effect of coupling between positive, negative and zero sequences when WPPs are injecting currents during asymmetrical...

  12. High efficiency H6 single-phase transformerless grid-tied PV inverter with proposed modulation for reactive power generation

    Science.gov (United States)

    Almasoudi, Fahad M.; Alatawi, Khaled S.; Matin, Mohammad

    2017-08-01

    Implementation of transformerless inverters in PV grid-tied system offer great benefits such as high efficiency, light weight, low cost, etc. Most of the proposed transformerless inverters in literature are verified for only real power application. Currently, international standards such as VDE-AR-N 4105 has demanded that PV grid-tied inverters should have the ability of controlling a specific amount of reactive power. Generation of reactive power cannot be accomplished in single phase transformerless inverter topologies because the existing modulation techniques are not adopted for a freewheeling path in the negative power region. This paper enhances a previous high efficiency proposed H6 trnasformerless inverter with SiC MOSFETs and demonstrates new operating modes for the generation of reactive power. A proposed pulse width modulation (PWM) technique is applied to achieve bidirectional current flow through freewheeling state. A comparison of the proposed H6 transformerless inverter using SiC MOSFETs and Si MOSFTEs is presented in terms of power losses and efficiency. The results show that reactive power control is attained without adding any additional active devices or modification to the inverter structure. Also, the proposed modulation maintains a constant common mode voltage (CM) during every operating mode and has low leakage current. The performance of the proposed system verifies its effectiveness in the next generation PV system.

  13. A Fast Reactive Power Optimization in Distribution Network Based on Large Random Matrix Theory and Data Analysis

    Directory of Open Access Journals (Sweden)

    Wanxing Sheng

    2016-05-01

    Full Text Available In this paper, a reactive power optimization method based on historical data is investigated to solve the dynamic reactive power optimization problem in distribution network. In order to reflect the variation of loads, network loads are represented in a form of random matrix. Load similarity (LS is defined to measure the degree of similarity between the loads in different days and the calculation method of the load similarity of load random matrix (LRM is presented. By calculating the load similarity between the forecasting random matrix and the random matrix of historical load, the historical reactive power optimization dispatching scheme that most matches the forecasting load can be found for reactive power control usage. The differences of daily load curves between working days and weekends in different seasons are considered in the proposed method. The proposed method is tested on a standard 14 nodes distribution network with three different types of load. The computational result demonstrates that the proposed method for reactive power optimization is fast, feasible and effective in distribution network.

  14. Thermal Performance and Reliability Analysis of Single-Phase PV Inverters with Reactive Power Injection Outside Feed-In Operating Hours

    DEFF Research Database (Denmark)

    Anurag, Anup; Yang, Yongheng; Blaabjerg, Frede

    2015-01-01

    there is no solar irradiance. However, reactive power injection causes additional power losses in the switching components leading to a temperature rise in the devices. Thus, this paper analyses the impact of reactive power injection by PV inverters outside feed-in operation on the thermal performance...... used. The damage produced on the transistors has been quantified using Palmgren Miner rule. A reliability analysis has been carried out on a PV inverter with and without the injection of reactive power into the utility grid at nights. Economic impacts of injecting reactive power from PV inverters...... outside feed-in operating hours have been analyzed thereafter. This analysis can be helpful to make a better choice while choosing between conventional reactive power devices or PV inverters for injecting reactive power to the grid....

  15. Reactive power despatch optimization using genetic algorithms; Otimizacao do despacho de reativos utilizando algoritmos geneticos

    Energy Technology Data Exchange (ETDEWEB)

    Dornellas, Carlos R.R.; Falcao, Djalma M.; Bomfim, Antonio L.B. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia

    1996-12-31

    This work presents an optimization method of the reactive power dispatch based on Genetic Algorithms (GAs). Suggested by John Holland in 1975. GAs are search algorithms that imitate the natural evolution of the species, combining the concepts of selective adaptation and survival of the fittest. GAs are robust, flexible, simple and particularly useful in the solution of the problems in which other optimization techniques may fail. GAs have great probability to determine the global optimum solution and they do not depend on information about linearity and convexity, however, they usually require a computational time greater than the conventional methods. The proposed method was applied to the IEEE 14 bus system and the results are presented and discussed. (author) 12 refs., 5 figs., 5 tabs.

  16. An optimal reactive power control strategy for a DFIG-based wind farm to damp the sub-synchronous oscillation of a power system

    DEFF Research Database (Denmark)

    Zhao, Bin; Li, Hui; Wang, Mingyu

    2014-01-01

    This study presents the auxiliary damping control with the reactive power loop on the rotor-side converter of doubly-fed induction generator (DFIG)-based wind farms to depress the sub-synchronous resonance oscillations in nearby turbogenerators. These generators are connected to a series capacitive...... compensation transmission system. First, the damping effect of the reactive power control of the DFIG-based wind farms was theoretically analyzed, and a transfer function between turbogenerator speed and the output reactive power of the wind farms was introduced to derive the analytical expression...... of the damping coefficient. The phase range to obtain positive damping was determined. Second, the PID phase compensation parameters of the auxiliary damping controller were optimized by a genetic algorithm to obtain the optimum damping in the entire subsynchronous frequency band. Finally, the validity...

  17. Reactive Power based Model Reference Neural Learning Adaptive System for Speed Estimation in Sensor-less Induction Motor Drives

    Directory of Open Access Journals (Sweden)

    K Sedhuraman

    2012-12-01

    Full Text Available In this paper, a novel reactive power based model reference neural learning adaptive system (RP-MRNLAS is proposed. The model reference adaptive system (MRAS based speed estimation is one of the most popular methods used for sensor-less controlled induction motor drives. In conventional MRAS, the error adaptation is done using a Proportional-integral-(PI. The non-linear mapping capability of a neural network (NN and the powerful learning algorithms have increased the applications of NN in power electronics and drives. Thus, a neural learning algorithm is used for the adaptation mechanism in MRAS and is often referred to as a model reference neural learning adaptive system (MRNLAS. In MRNLAS, the error between the reference and neural learning adaptive models is back propagated to adjust the weights of the neural network for rotor speed estimation. The two different methods of MRNLAS are flux based (RF-MRNLAS and reactive power based (RP-MRNLAS. The reactive power- based methods are simple and free from integral equations as compared to flux based methods. The advantage of the reactive power based method and the NN learning algorithms are exploited in this work to yield a RPMRNLAS. The performance of the proposed RP-MRNLAS is analyzed extensively. The proposed RP-MRNLAS is compared in terms of accuracy and integrator drift problems with popular rotor flux-based MRNLAS for the same system and validated through Matlab/Simulink. The superiority of the RP- MRNLAS technique is demonstrated

  18. Comprehensive Cost Minimization in Distribution Networks Using Segmented-time Feeder Reconfiguration and Reactive Power Control of Distributed Generators

    DEFF Research Database (Denmark)

    Chen, Shuheng; Hu, Weihao; Chen, Zhe

    2016-01-01

    In this paper, an efficient methodology is proposed to deal with segmented-time reconfiguration problem of distribution networks coupled with segmented-time reactive power control of distributed generators. The target is to find the optimal dispatching schedule of all controllable switches...... and distributed generators’ reactive powers in order to minimize comprehensive cost. Corresponding constraints, including voltage profile, maximum allowable daily switching operation numbers (MADSON), reactive power limits, and so on, are considered. The strategy of grouping branches is used to simplify...... (FAHPSO) is implemented in VC++ 6.0 program language. A modified version of the typical 70-node distribution network and several real distribution networks are used to test the performance of the proposed method. Numerical results show that the proposed methodology is an efficient method for comprehensive...

  19. Dropped out or pushed out? Insurance market exit and provider market power in Medicare Advantage.

    Science.gov (United States)

    Pelech, Daria

    2017-01-01

    This paper explores how provider and insurer market power affect which markets an insurer chooses to operate in. A 2011 policy change required that certain private insurance plans in Medicare form provider networks de novo; in response, insurers cancelled two-thirds of the affected plans. Using detailed data on pre-policy provider and insurer market structure, I compare markets where insurers built networks to those they exited. Overall, insurers in the most concentrated hospital and physician markets were 9 and 13 percentage points more likely to exit, respectively, than those in the least concentrated markets. Conversely, insurers with more market power were less likely to exit than those with less, and an insurer's market power had the largest effect on exit in concentrated hospital markets. These findings suggest that concentrated provider markets contribute to insurer exit and that insurers with less market power have more difficulty surviving in concentrated provider markets. Published by Elsevier B.V.

  20. Systems and methods for providing power to a load based upon a control strategy

    Energy Technology Data Exchange (ETDEWEB)

    Perisic, Milun; Kajouke, Lateef A; Ransom, Ray M

    2013-12-24

    Systems and methods are provided for an electrical system. The electrical system includes a load, an interface configured to receive a voltage from a voltage source, and a controller configured to receive the voltage from the voltage source through the interface and to provide a voltage and current to the load. Wherein, when the controller is in a constant voltage mode, the controller provides a constant voltage to the load, when the controller is in a constant current mode, the controller provides a constant current to the load, and when the controller is in a constant power mode, the controller provides a constant power to the load.

  1. Customized power quality service provided by converter interfaced microgrids — Voltage harmonics as a study case

    DEFF Research Database (Denmark)

    Meng, Lexuan; Chaudhary, Sanjay K.; Guerrero, Josep M.

    2017-01-01

    Customers may have different power quality requirements, thus, the economic operational strategy can try to provide them with distinctive quality levels as customized service. An optimization based method is proposed in this paper to realize this functionality, offering the possibility...

  2. Application of Hybrid MOPSO Algorithm to Optimal Reactive Power Dispatch Problem Considering Voltage Stability

    Directory of Open Access Journals (Sweden)

    Yujiao Zeng

    2014-01-01

    Full Text Available This study presents a novel hybrid multiobjective particle swarm optimization (HMOPSO algorithm to solve the optimal reactive power dispatch (ORPD problem. This problem is formulated as a challenging nonlinear constrained multiobjective optimization problem considering three objectives, that is, power losses minimization, voltage profile improvement, and voltage stability enhancement simultaneously. In order to attain better convergence and diversity, this work presents the use of combing the classical MOPSO with Gaussian probability distribution, chaotic sequences, dynamic crowding distance, and self-adaptive mutation operator. Moreover, multiple effective strategies, such as mixed-variable handling approach, constraint handling technique, and stopping criteria, are employed. The effectiveness of the proposed algorithm for solving the ORPD problem is validated on the standard IEEE 30-bus and IEEE 118-bus systems under nominal and contingency states. The obtained results are compared with classical MOPSO, nondominated sorting genetic algorithm (NSGA-II, multiobjective evolutionary algorithm based on decomposition (MOEA/D, and other methods recently reported in the literature from the point of view of Pareto fronts, extreme, solutions and multiobjective performance metrics. The numerical results demonstrate the superiority of the proposed HMOPSO in solving the ORPD problem while strictly satisfying all the constraints.

  3. Real And Reactive Power Saving In Three Phase Induction Machine Using Star-Delta Switching Schemes

    Directory of Open Access Journals (Sweden)

    Ramesh Daravath

    2015-08-01

    Full Text Available Induction machines are the most commonly used industrial drives for variety of applications. It has been estimated that induction motors consumes approximately 50 of all the electric energy generated. Further in the area of renewable energy sources such as wind or bio-mass energy induction machines have been found suitable for functioning as generators. In this context it may be mentioned that a star-delta switching is common for the starting of three-phase induction motor. Now it is proposed to use this star-delta switching for energy conservation of induction machines i.e. at times of reduced loads the machine switched back to star connection. Using a three-phase 400 V 50 Hz 4-pole induction machine it has been demonstrated that the star-delta switching of stator winding of three-phase induction machine motor generator operations reconnected in star at suitable reduced loads with a switching arrangement can result in improved efficiency and power factor as compared to a fixed delta or star connection. The predetermined values along with the experimental results have also been presented in this report. A simulation program has been developed for the predetermination of performance of the three-phase induction machine using exact equivalent circuit. A case study on a 250 kW 400 V 4-pole three-phase induction machine operated with different load cycles reveals the significant real and reactive power savings that could be obtained in the present proposal.

  4. Demand response strategy management with active and reactive power incentive in the smart grid: a two-level optimization approach

    Directory of Open Access Journals (Sweden)

    Ryuto Shigenobu

    2017-05-01

    Full Text Available High penetration of distributed generators (DGs using renewable energy sources (RESs is raising some important issues in the operation of modern po­wer system. The output power of RESs fluctuates very steeply, and that include uncertainty with weather conditions. This situation causes voltage deviation and reverse power flow. Several methods have been proposed for solving these problems. Fundamentally, these methods involve reactive power control for voltage deviation and/or the installation of large battery energy storage system (BESS at the interconnection point for reverse power flow. In order to reduce the installation cost of static var compensator (SVC, Distribution Company (DisCo gives reactive power incentive to the cooperating customers. On the other hand, photovoltaic (PV generator, energy storage and electric vehicle (EV are introduced in customer side with the aim of achieving zero net energy homes (ZEHs. This paper proposes not only reactive power control but also active power flow control using house BESS and EV. Moreover, incentive method is proposed to promote participation of customers in the control operation. Demand response (DR system is verified with several DR menu. To create profit for both side of DisCo and customer, two level optimization approach is executed in this research. Mathematical modeling of price elasticity and detailed simulations are executed by case study. The effectiveness of the proposed incentive menu is demonstrated by using heuristic optimization method.

  5. Optimal reactive power and voltage control in distribution networks with distributed generators by fuzzy adaptive hybrid particle swarm optimisation method

    DEFF Research Database (Denmark)

    Chen, Shuheng; Hu, Weihao; Su, Chi

    2015-01-01

    A new and efficient methodology for optimal reactive power and voltage control of distribution networks with distributed generators based on fuzzy adaptive hybrid PSO (FAHPSO) is proposed. The objective is to minimize comprehensive cost, consisting of power loss and operation cost of transformers...... that the proposed method can search a more promising control schedule of all transformers, all capacitors and all distributed generators with less time consumption, compared with other listed artificial intelligent methods....

  6. K 4R - Knowledge to the Power of RESTful, Resourceful and Reactive Rules

    Science.gov (United States)

    Amador, Ricardo

    The Web of today clearly answers questions of the form "What is the representation of ...?". The Semantic Web (SW) of tomorrow aims at answering questions of the form "What is the meaning of ...?". It is our stance that in order to realize the full potential of the original concept proposed by Tim Berners-Lee et al. (in Scientific American, May 2001), the SW must also answer, in a meaningful way, questions of a dynamic and active nature, like "What to do if ...?" or "What to do when ...?". Moreover, SW questions of the form "What to do ...?" must be expressed and answered in a declarative, compositional and language agnostic way. It is our (hypo)thesis that formally established concepts, viz. the Web's REST architectural style, declarative SW representation of resources based on Description Logics (e.g., OWL-DL), and Reactive Rules (e.g., "on Event if Condition do Action" -ECA- rules), provide the proper theoretical foundations to achieve this goal. This paper describes our current research proposal, K 4R (pronounced, with an Italian flavor, "Che fare?"), towards achieving a declarative model for expressing (re)active behavior in and for the SW.

  7. Optimization Based Shunt APF Controller to Mitigate Reactive Power, Burden of Neutral Conductor, Current Harmonics and Improve cosɸ

    Directory of Open Access Journals (Sweden)

    P. Anjana

    2017-03-01

    Full Text Available This paper presents a Modified Gravitational Search Algorithm (MGSA to improve the performance of PI controller in varying load condition. The proposed approach is capable of mitigating reactive power, neutral current, source current THD and significant improvement in power factor nearly unity (0.997. The DC link voltage across the capacitor is controlled by PI controller which is deciding the performance of shunt APF. Hence, the robust optimization technique based integral time square error (ITSE with consideration of weight factor (α & β, maximum overshoot ((|(∆_Ve ̅〖(n〗_max | and setling time t_s-t_0, is providing the optimum solution of Kp & Ki. The robustness of proposed objective function and algorithm compared with GSA based three other error criterion techniques. The efficiency of the proposed controller has been tested over nonlinear and unbalance loading condition. The performance of ITSE based MGSA-PI controller is batter then other three error criterion techniques. The values of THD are below the mark of 5% specified in IEEE-519 standard.

  8. Coupling/Tradeoff Analysis and Novel Containment Control for Reactive Power, Output Voltage in Islanded Micro-Grid

    DEFF Research Database (Denmark)

    Han, Renke; Meng, Lexuan; Guerrero, Josep M.

    2016-01-01

    Based on the hierarchical control structure in islanded Micro-Grid (MG) systems, the coupling/tradeoff effects in different control levels are analyzed in details. In the primary level, analyses of the coupling effects among droop control gains, line impedance differences, output reactive power a...

  9. Containment and Consensus-based Distributed Coordination Control for Voltage Bound and Reactive Power Sharing in AC Microgrid

    DEFF Research Database (Denmark)

    Han, Renke; Meng, Lexuan; Ferrari-Trecate, Giancarlo

    2017-01-01

    This paper offers a highly flexible and reliable control strategy to achieve voltage bounded regulation and accurate reactive power sharing coordinately in AC Micro-Grids. A containment and consensus-based distributed coordination controller is proposed, by which each output voltage magnitude can...

  10. Investigation of the behavior of a three phase grid-connected photovoltaic system to control active and reactive power

    Energy Technology Data Exchange (ETDEWEB)

    Tsengenes, Georgios; Adamidis, Georgios [Department of Electrical Engineering and Computer Engineering, Democritus University of Thrace, University Campus Kimmeria, 67100 Xanthi (Greece)

    2011-01-15

    In this paper, a photovoltaic (PV) system, with maximum power point tracking (MPPT), connected to a three phase grid is presented. The connection of photovoltaic system on the grid takes place in one stage using voltage source inverter (VSI). For a better utilization of the photovoltaic system, the control strategy applied is based on p-q theory. According to this strategy during sunlight the system sends active power to the grid and at the same time compensates the reactive power of the load. In case there is no sunlight (during the night for instance), the inverter only compensates the reactive power of the load. In this paper the use of p-q theory to supply the grid with active power and compensate the reactive power of the load is investigated. The advantage of this control strategy is that the photovoltaic system is operated the whole day. Furthermore, the p-q theory uses simple algebraic calculations without demanding the use of PLL to synchronize the inverter with the grid. (author)

  11. Using hydropower to complement wind energy: a hybrid system to provide firm power

    Energy Technology Data Exchange (ETDEWEB)

    Jaramillo, O.A.; Borja, M.A.; Huacuz, J.M. [Instituto de Investigaciones Electricas, Morelos (Mexico). Energias No Convencionales

    2004-09-01

    This paper presents a theoretical study of how wind power can be complemented by hydropower. A conceptual framework is provided for a hybrid power station that produces constant power output without the intermittent fluctuations inherent when using wind power. Two hypothetical facilities are considered as case studies. One of them is a hydropower plant located on the ''Presidente Benito Juarez'' dam in Jalapa del Marques, Oaxaca, Mexico. The other hypothetical facility is a wind farm located near ''La Venta's', an area in Juchitan, Oaxaca, Mexico. The wind-hydro-power system is a combined wind and hydro power plant in a region that is rich in both resources. The model shows that the hybrid plant could provide close to 20 MW of firm power to the electrical distribution system. On a techno-economic basis, we obtain the levelized production cost of the hybrid system. Taking into account two different discount rates of 7% and 10%, figures for levelized production cost are developed. (author)

  12. Lightweight Innovative Solar Array (LISA): Providing Higher Power to Small Spacecraft

    Science.gov (United States)

    Johnson, Les; Carr, John; Fabisinski, Leo; Russell,Tiffany; Smith, Leigh

    2015-01-01

    Affordable and convenient access to electrical power is essential for all spacecraft and is a critical design driver for the next generation of smallsats, including cubesats, which are currently extremely power limited. The Lightweight Innovative Solar Array (LISA), a concept designed, prototyped, and tested at the NASA Marshall Space Flight Center (MSFC) in Huntsville, Alabama provides an affordable, lightweight, scalable, and easily manufactured approach for power generation in space. This flexible technology has many wide-ranging applications from serving small satellites to providing abundant power to large spacecraft in GEO and beyond. By using very thin, ultra-flexible solar arrays adhered to an inflatable structure, a large area (and thus large amount of power) can be folded and packaged into a relatively small volume. The LISA array comprises a launch-stowed, orbit-deployed structure on which lightweight photovoltaic devices and, potentially, transceiver elements are embedded. The system will provide a 2.5 to 5 fold increase in specific power generation (Watts/kilogram) coupled with a >2x enhancement of stowed volume (Watts/cubic-meter) and a decrease in cost (dollars/Watt) when compared to state-of-the-art solar arrays.

  13. Using genetic algorithm and TOPSIS technique for multiobjective reactive power compensation

    Energy Technology Data Exchange (ETDEWEB)

    Azzam, M. [Department of Electrical Engineering, Faculty of Engineering, Mina University, Mina (Egypt); Mousa, A.A. [Department of Basic Engineering Sciences, Faculty of Engineering, Menoufia University, Shebin El-Kom (Egypt)

    2010-06-15

    A new approach to solve the multiobjective reactive power compensation (RPC) problem is presented. It is based on the combination of genetic algorithm (GA) and the {epsilon}-dominance concept. The algorithm maintains a finite-sized archive of nondominated solutions (Pareto solution) which gets iteratively updated in the presence of new solutions based on the concept of {epsilon}-dominance. The use of {epsilon}-dominance makes the algorithms practical by allowing a decision maker (DM) able to control the resolution of the Pareto set approximation according to his needs. The proposed approach is suitable to RPC problem where the objective functions may be ill-defined and having nonconvex Pareto-optimal front. It gives a reasonable freedom in choosing compensation devices from the available commercial devices. It may save computing time in cases of small archive. Moreover to help the DM to extract the best compromise solution from a finite set of alternatives a TOPSIS (Technique for Order Performance by Similarity to Ideal Solution) method is adopted. It is based upon simultaneous minimization of distance from an ideal point (IP) and maximization of distance from a nadir point (NP). The proposed approach is carried out on the standard IEEE 30-bus 6-generator test system. The results demonstrate the capabilities of the proposed approach to generate true and well-distributed Pareto-optimal nondominated solutions of the multiobjective RPC problem in one single run. (author)

  14. Single-point reactive power control method on voltage rise mitigation in residential networks with high PV penetration

    DEFF Research Database (Denmark)

    Hasheminamin, Maryam; Agelidis, Vassilios; Ahmadi, Abdollah

    2018-01-01

    Voltage rise (VR) due to reverse power flow is an important obstacle for high integration of Photovoltaic (PV) into residential networks. This paper introduces and elaborates a novel methodology of an index-based single-point-reactive power-control (SPRPC) methodology to mitigate voltage rise by ...... system with high r/x ratio. Efficacy, effectiveness and cost study of SPRPC is compared to droop control to evaluate its advantages....... by absorbing adequate reactive power from one selected point. The proposed index utilizes short circuit analysis to select the best point to apply this Volt/Var control method. SPRPC is supported technically and financially by distribution network operator that makes it cost effective, simple and efficient...

  15. Multi-Objective Advanced Inverter Controls to Dispatch the Real and Reactive Power of Many Distributed PV Systems.

    Energy Technology Data Exchange (ETDEWEB)

    Reno, Matthew J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lave, Matthew Samuel [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Broderick, Robert Joseph [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Seuss, John [Georgia Inst. of Technology, Atlanta, GA (United States); Grijalva, Santiago [Georgia Inst. of Technology, Atlanta, GA (United States)

    2016-01-01

    The research presented in this report compares several real - time control strategies for the power output of a large number of PV distributed throughout a large distribution feeder circuit. Both real and reactive power controls are considered with the goal of minimizing network over - voltage violations caused by large amounts of PV generation. Several control strategies are considered under various assumptions regarding the existence and latency of a communication network. The control parameters are adjusted to maximize the effectiveness of each control. The controls are then compared based on their ability to achieve multiple objectiv es. These objectives include minimizing the total number of voltage violations , minimizing the total amount of PV energy curtailed or reactive power generated, and maximizing the fairness of any control action among all PV systems . The controls are simulat ed on the OpenDSS platform using time series load and spatially - distributed irradiance data.

  16. Low Complexity Distributed SDP Approach for General OPF Problems with Reactive Power Cost

    OpenAIRE

    Chang, Chin-Yao; Zhang, Wei

    2016-01-01

    Optimal power flow (OPF) problem is a class of large-scale and non-convex optimization problem. Various algorithms are proposed to solve the challenging OPF problem. Recent studies show that semidefinite programming (SDP) can either provide an exact or near global optima for many existing OPF problems. However, SDP-based approaches usually have the complexity growing exponentially with respect to the network size, which may not be suitable for large-scale OPF problem. In this paper, we rewrit...

  17. Second-Life Batteries on a Gas Turbine Power Plant to Provide Area Regulation Services

    Directory of Open Access Journals (Sweden)

    Lluc Canals Casals

    2017-03-01

    Full Text Available Batteries are used in the electricity grid to provide ancillary services. Area regulation seems to provide substantial revenues and profit, but Li-ion batteries are still too expensive to enter widely into this market. On the other hand, electric vehicle (EV batteries are considered inappropriate for traction purposes when they reach a state of health (SoH of 80%. The reuse of these batteries offers affordable batteries for second-life stationary applications. This study analyzes two possible scenarios where batteries may give power and energy support to a gas turbine cogeneration power plant, and how long these batteries may last under different loads.

  18. Lightweight Inflatable Solar Array: Providing a Flexible, Efficient Solution to Space Power Systems for Small Spacecraft

    Science.gov (United States)

    Johnson, Len; Fabisinski, Leo; Cunningham, Karen; Justice, Stefanie

    2014-01-01

    Affordable and convenient access to electrical power is critical to consumers, spacecraft, military and other applications alike. In the aerospace industry, an increased emphasis on small satellite flights and a move toward CubeSat and NanoSat technologies, the need for systems that could package into a small stowage volume while still being able to power robust space missions has become more critical. As a result, the Marshall Space Flight Center's Advanced Concepts Office identified a need for more efficient, affordable, and smaller space power systems to trade in performing design and feasibility studies. The Lightweight Inflatable Solar Array (LISA), a concept designed, prototyped, and tested at the NASA Marshall Space Flight Center (MSFC) in Huntsville, Alabama provides an affordable, lightweight, scalable, and easily manufactured approach for power generation in space or on Earth. This flexible technology has many wide-ranging applications from serving small satellites to soldiers in the field. By using very thin, ultraflexible solar arrays adhered to an inflatable structure, a large area (and thus large amount of power) can be folded and packaged into a relatively small volume (shown in artist rendering in Figure 1 below). The proposed presentation will provide an overview of the progress to date on the LISA project as well as a look at its potential, with continued development, to revolutionize small spacecraft and portable terrestrial power systems.

  19. [Effects of Reactive Jump Training in Handball Players Regarding Jump Height and Power Development in the Triceps Surae Muscle].

    Science.gov (United States)

    Rensing, N; Westermann, A; Möller, D; von Piekartz, H

    2015-12-01

    Studies have shown changes in the technical and physical demands in modern handball. The game has increased considerably in speed, power and dynamics. Jump training has, therefore, become ever more important in the training of the athletes. These developments contribute to the fact that handball is now one of the most injury-prone types of sport, with the lower extremities being most frequently affected. Reactive jump training is not only used in training by now, but also increasingly in injury prevention. The aim of this study was to investigate the effectiveness of reactive jump training with handball players. 21 regional league handball players were randomly divided into an intervention group (n = 12) and a control group (n = 9). The intervention group completed a six-week reactive jump training programme while the control group went through a non-specific training programme. Jump height (squat and counter movement jump), isokinetic and isometric maximum power as well as muscle activity served as measuring parameters. A comparison of the intervention and control groups revealed that the reactive jump training led to significant improvements in jump height. The isometric and isokinetic maximum power measurements and the electromyographic activities of the triceps surae muscle demonstrated an improvement in the values within the intervention group. However, this improvement was not significant compared with the control group. Likewise both jumps correlated with the muscle activity of the soleus muscle as shown by electromyography. A moderate correlation was noticed between the isokinetic maximum power measurement and the electromyographic activity of the soleus and gastrocnemius medialis muscles. Furthermore, the correlations of the isometric and isokinetic maximum power meas-urements resulted in a strong correlation coefficient. This study revealed a significant increase in jump height after reactive jump training. There was no significant difference in

  20. High fluence low-power laser irradiation induces mitochondrial permeability transition mediated by reactive oxygen species.

    Science.gov (United States)

    Wu, Shengnan; Xing, Da; Gao, Xuejuan; Chen, Wei R

    2009-03-01

    High fluence low-power laser irradiation (HF-LPLI) can induce cell apoptosis via the mitochondria/caspase-3 pathway. Here, we further investigated the mechanism involved in the apoptotic process in human lung adenocarcinoma cells (ASTC-a-1) at a laser irradiation fluence of 120 J/cm(2) (633 nm). Cytochrome c release was ascribed to mitochondrial permeability transition (MPT) because the release was prevented by cyclosporine (CsA), a specific inhibitor of MPT. Furthermore, mitochondrial permeability for calcein (approximately 620 Da) was another evidence for the MPT induction under HF-LPLI treatment. A high-level intracellular reactive oxygen species (ROS) generation was observed after irradiation. The photodynamically produced ROS caused onset of MPT, as the ROS scavenger docosahexaenoic acid (DHA) prevented the MPT. However, CsA failed to prevented cell death induced by HF-LPLI, indicating the existence of other signaling pathways. Following laser irradiation, Bax activation occurred after mitochondrial depolarization and cytochrome c release, indicating Bax activation was a downstream event. In the presence of CsA, Bax was still activated at the end-stage of apoptotic process caused by HF-LPLI, suggesting that Bax was involved in an alternative-signaling pathway, which was independent of MPT. Under HF-LPLI treatment, cell viabilities due to pre-treatment with DHA, CsA, or Bax small interfering RNA (siRNA) demonstrated that the MPT signaling pathway was dominant, while Bax signaling pathway was secondary, and more importantly ROS mediated both pathways. Taken together, these results showed that HF-LPLI induced cell apoptosis via the CsA-sensitive MPT, which was ROS-dependent. Furthermore, there existed a secondary signaling pathway through Bax activation. The observed link between MPT and triggering ROS could be a fundamental phenomenon in HF-LPLI-induced cell apoptosis.

  1. Power Analysis for Genetic Association Test (PAGEANT) provides insights to challenges for rare variant association studies.

    Science.gov (United States)

    Derkach, Andriy; Zhang, Haoyu; Chatterjee, Nilanjan

    2017-11-28

    Genome-wide association studies are now shifting focus from analysis of common to rare variants. As power for association testing for individual rare variants may often be low, various aggregate level association tests have been proposed to detect genetic loci. Typically, power calculations for such tests require specification of large number of parameters, including effect sizes and allele frequencies of individual variants, making them difficult to use in practice. We propose to approximate power to varying degree of accuracy using a smaller number of key parameters, including the total genetic variance explained by multiple variants within a locus. We perform extensive simulation studies to assess the accuracy of the proposed approximations in realistic settings. Using these simplified power calculations, we develop an analytic framework to obtain bounds on genetic architecture of an underlying trait given results from a genome-wide association studies with rare variants. Finally, we provide insights into the required quality of annotation/functional information for identification of likely causal variants to make meaningful improvement in power. A shiny application that allows a variety of Power Analysis of GEnetic AssociatioN Tests (PAGEANT), in R is made publicly available at https://andrewhaoyu.shinyapps.io/PAGEANT/. nilanjan@jhu.edu. Supplementary data are available at Bioinformatics online.

  2. Reactive power static sources in the diagnosis of insulation condition of the induction motor and the power supply cable in terms of local compensation

    Directory of Open Access Journals (Sweden)

    Валерій Єгорович Кривоносов

    2017-06-01

    Full Text Available Reactive power compensation is particularly relevant for the industrial companies, major power consumers of which are asynchronous motors (АM. The most effective reactive power compensation is at placing the capacitor bank (CB directly at the points of AM connection. The capacity of the CB and the method of controlling the power factor depend on the AM loading conditions. Under operating conditions ensuring AM reliable start-up after a technological pause is an important task. Reliable motor start-up is possible when the insulation resistance of the stator windings is equal to or above 0.5 megohms. The discharge of the capacitor bank at the moment of the AM disconnection from the network, makes it possible to use the power stored in the CB to diagnose insulation condition and suitability of the AM to a safe start. The speed of the CB discharge is the criterion showing that the AM winding insulation resistance is of critical value. The capacitors discharge simulation made it possible to develop a method to protect the AM and the power cable as well as to formulate an algorithm to identify one-, two-, three- and interphase short circuit when operating, and at the time of the AM disconnection from the network and to define the critical value of the insulation resistance according to the capacitor discharge speed

  3. Characterization of combined power plasma jet using AC high voltage and nanosecond pulse for reactive species composition control

    Science.gov (United States)

    Takashima, Keisuke; Konishi, Hideaki; Kato, Toshiaki; Kaneko, Toshiro

    2014-10-01

    In the application studies for both bio-medical and agricultural applications, the roles of the reactive oxide and/or nitride species generated in the plasma has been reported as a key to control the effects and ill-effects on the living organism. The correlation between total OH radical exposure from an air atmospheric pressure plasma jet and the sterilization threshold on Botrytis cinerea is presented. With the increase of the OH radical exposure to the Botrytis cinerea, the probability of sterilization is increased. In this study, to resolve the roles of reactive species including OH radicals, a combined power plasma jet using nanosecond pulses and low-frequency sinusoidal AC high voltage (a few kHz) is studied for controlling the composition of the reactive species. The nanosecond pulses are superimposed on the AC voltage which is in synchronization with the AC phase. The undergoing work to characterize the combined power discharge with electric charge and voltage cycle on the plasma jet will also be presented to discuss the discharge characteristics to control the composition of the reactive species.

  4. An Integral Model to Provide Reactive and Proactive Services in an Academic CSIRT Based on Business Intelligence

    Directory of Open Access Journals (Sweden)

    Walter Fuertes

    2017-11-01

    Full Text Available Cyber-attacks have increased in severity and complexity. That requires, that the CERT/CSIRT research and develops new security tools. Therefore, our study focuses on the design of an integral model based on Business Intelligence (BI, which provides reactive and proactive services in a CSIRT, in order to alert and reduce any suspicious or malicious activity on information systems and data networks. To achieve this purpose, a solution has been assembled, that generates information stores, being compiled from a continuous network transmission of several internal and external sources of an organization. However, it contemplates a data warehouse, which is focused like a correlator of logs, being formed by the information of feeds with diverse formats. Furthermore, it analyzed attack detection and port scanning, obtained from sensors such as Snort and Passive Vulnerability Scanner, which are stored in a database, where the logs have been generated by the systems. With such inputs, we designed and implemented BI systems using the phases of the Ralph Kimball methodology, ETL and OLAP processes. In addition, a software application has been implemented using the SCRUM methodology, which allowed to link the obtained logs to the BI system for visualization in dynamic dashboards, with the purpose of generating early alerts and constructing complex queries using the user interface through objects structures. The results demonstrate, that this solution has generated early warnings based on the level of criticality and level of sensitivity of malware and vulnerabilities as well as monitoring efficiency, increasing the level of security of member institutions.

  5. Autonomous Control of Current and Voltage Controlled DG Interface Inverters for Reactive Power Sharing and Harmonics Compensation in Islanded Microgrids

    DEFF Research Database (Denmark)

    Mousazadeh, Seyyed Yousef; Jalilain, Alireza; Savaghebi, Mehdi

    2018-01-01

    by using capacitive virtual impedance which can fully compensate the effect of output inductance of the LCL filters. Furthermore, an adaptive virtual admittance regulated based on remaining capacity of the CCM units is implemented for the CCM units. For reactive power sharing, modified droop and reverse...... droop control methods are used for VCM and CCM units, respectively. The related droop coefficients are set by taking the limited capacity of the inverters and the distorted power into account. An experimental prototype is developed to evaluate the effectiveness of the proposed control scheme...

  6. Sliding mode controller for four leg shunt active power filter to eliminating zero sequence current, compensating harmonics and reactive power with fixed switching frequency

    Directory of Open Access Journals (Sweden)

    Chebabhi Ali

    2015-01-01

    Full Text Available In this paper, the four leg inverter controlled by the three dimensional space vector modulation (3D SVM is used as the shunt active power filter (SAPF for compensating the three phase four wire electrical network, by using the four leg inverter with 3D SVM advantages to eliminated zero sequence current, fixed switching frequency of inverter switches, and reduced switching losses. This four leg inverter is employed as shunt active power filter to minimizing harmonic currents, reducing magnitude of neutral wire current, eliminating zero sequence current caused by nonlinear single phase loads and compensating reactive power, and a nonlinear sliding mode control technique (SMC is proposed for harmonic currents and DC bus voltage control to improve the performances of the three phase four wire four leg shunt active power filter based on Synchronous Reference Frame (SRF theory in the dq0 axes, and to decoupling the four leg SAPF mathematical model.

  7. Application of Multi-Objective Evolutionary Algorithm for Optimal Reactive Power Dispatch with Flexible AC Transmission System Devices

    Directory of Open Access Journals (Sweden)

    Abdarrazak OUALI

    2011-12-01

    Full Text Available Because their capability to change the network parameters with a rapid response and enhanced flexibility, flexible AC transmission system (FACTS devices have taken more attention in power systems operations as improvement of voltage profile and minimizing system losses. In this way, this paper presents a multi-objective evolutionary algorithm (MOEA to solve optimal reactive power dispatch (ORPD problem with FACTS devices. This nonlinear multi-objective problem (MOP consists to minimize simultaneously real power loss in transmission lines and voltage deviation at load buses, by tuning parameters and searching the location of FACTS devices. The constraints of this MOP are divided to equality constraints represented by load flow equations and inequality constraints such as, generation reactive power sources and security limits at load buses. Two types of FACTS devices, static synchronous series compensator (SSSC and unified power flow controller (UPFC are considered. A comparative study regarding the effects of an SSSC and an UPFC on voltage deviation and total transmission real losses is carried out. The design problem is tested on a 6-bus system.

  8. Active and reactive power control of the doubly fed induction generator based on wind energy conversion system

    Directory of Open Access Journals (Sweden)

    Ghulam Sarwar Kaloi

    2016-11-01

    Full Text Available This paper presents a dynamic modeling and control of doubly fed induction-generator (DFIG based on the wind turbine systems. Active and reactive power control of the DFIG are based on the feedback technique by using the suitable voltage vectors on the rotor side. The rotor flux has no impact on the changes of the stator active and reactive power. The proposed controller is based on the feedback technique in order to reduce the oscillation of the generator. The control approach is estimated through the simulation result of the feedback controller assembled with DFIG wind turbines. It is applied by the feedback control based techniques in order to control the power flowing of DFIG and the power grid. Hence, an improved feedback control technique is adopted to get a better power flow transfer and to improve the dynamic system and transient stability. In stable condition, the improved performance of the controller, the proposed method is verified for the effectiveness of the control method is done in stable conditions.

  9. Analysis of static safety of power systems: a study about contingencies selection criteria in the reactive subproblem; Analise de seguranca estatica de sistemas de potencia: um estudo sobre criterios de selecao de contingencias no subproblema reativo

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Jose Vicente Canto dos

    1993-12-01

    The main objective of static safety's analysis in power systems is the determination of the level of gravity of the different contingencies that can occur in a system. Habitually, static safety's analysis is divided in two parts: selection and analysis of contingencies. In this work, they are studied several criteria of selection of applicable contingencies to the sub-problem reactive and are introduced comparisons among results provided by different criteria. They are also studied several forms of evaluation of the impact caused by contingencies on the power systems reactive profile.

  10. Using reactive transport codes to provide mechanistic biogeochemistry representations in global land surface models: CLM-PFLOTRAN 1.0

    Science.gov (United States)

    Tang, G.; Yuan, F.; Bisht, G.; Hammond, G. E.; Lichtner, P. C.; Kumar, J.; Mills, R. T.; Xu, X.; Andre, B.; Hoffman, F. M.; Painter, S. L.; Thornton, P. E.

    2015-12-01

    We explore coupling to a configurable subsurface reactive transport code as a flexible and extensible approach to biogeochemistry in land surface models; our goal is to facilitate testing of alternative models and incorporation of new understanding. A reaction network with the CLM-CN decomposition, nitrification, denitrification, and plant uptake is used as an example. We implement the reactions in the open-source PFLOTRAN code, coupled with the Community Land Model (CLM), and test at Arctic, temperate, and tropical sites. To make the reaction network designed for use in explicit time stepping in CLM compatible with the implicit time stepping used in PFLOTRAN, the Monod substrate rate-limiting function with a residual concentration is used to represent the limitation of nitrogen availability on plant uptake and immobilization. To achieve accurate, efficient, and robust numerical solutions, care needs to be taken to use scaling, clipping, or log transformation to avoid negative concentrations during the Newton iterations. With a tight relative update tolerance to avoid false convergence, an accurate solution can be achieved with about 50 % more computing time than CLM in point mode site simulations using either the scaling or clipping methods. The log transformation method takes 60-100 % more computing time than CLM. The computing time increases slightly for clipping and scaling; it increases substantially for log transformation for half saturation decrease from 10-3 to 10-9 mol m-3, which normally results in decreasing nitrogen concentrations. The frequent occurrence of very low concentrations (e.g. below nanomolar) can increase the computing time for clipping or scaling by about 20 %; computing time can be doubled for log transformation. Caution needs to be taken in choosing the appropriate scaling factor because a small value caused by a negative update to a small concentration may diminish the update and result in false convergence even with very tight relative

  11. A novel hybrid Particle Swarm Optimizer with multi verse optimizer for global numerical optimization and Optimal Reactive Power Dispatch problem

    Directory of Open Access Journals (Sweden)

    Pradeep Jangir

    2017-04-01

    Full Text Available Recent trend of research is to hybridize two and more algorithms to obtain superior solution in the field of optimization problems. In this context, a new technique hybrid Particle Swarm Optimization (PSO-Multi verse Optimizer (MVO is exercised on some unconstraint benchmark test functions and the most common problem of the modern power system named Optimal Reactive Power Dispatch (ORPD is optimized using the novel hybrid meta-heuristic optimization algorithm Particle Swarm Optimization-Multi Verse Optimizer (HPSO-MVO method. Hybrid PSO-MVO is combination of PSO used for exploitation phase and MVO for exploration phase in uncertain environment. Position and Speed of particle is modernised according to location of universes in each iteration. The hybrid PSO-MVO method has a fast convergence rate due to use of roulette wheel selection method. For the ORPD solution, standard IEEE-30 bus test system is used. The hybrid PSO-MVO method is implemented to solve the proposed problem. The problems considered in the ORPD are fuel cost reduction, Voltage profile improvement, Voltage stability enhancement, Active power loss minimization and Reactive power loss minimization. The results obtained with hybrid PSO-MVO method is compared with other techniques such as Particle Swarm Optimization (PSO and Multi Verse Optimizer (MVO. Analysis of competitive results obtained from HPSO-MVO validates its effectiveness compare to standard PSO and MVO algorithm.

  12. Detailed neutronic study of the power evolution for the European Sodium Fast Reactor during a positive insertion of reactivity

    Energy Technology Data Exchange (ETDEWEB)

    Facchini, A.; Giusti, V.; Ciolini, R. [Department of Civil and Industrial Engineering (DICI), University of Pisa, Largo Lucio Lazzarino 2, I-56126 Pisa (Italy); Tuček, K.; Thomas, D. [Joint Research Centre, Institute for Energy and Transport (JRC - IET), European Commission, P.O. Box 2, NL-1755 ZG Petten (Netherlands); D' Agata, E., E-mail: elio.dagata@ec.europa.eu [Joint Research Centre, Institute for Energy and Transport (JRC - IET), European Commission, P.O. Box 2, NL-1755 ZG Petten (Netherlands)

    2017-03-15

    Highlights: • This paper studies the effect of an unexpected runway of a control rod in the ESFR. • The power peaked fuel pin within the core was identified. • The increase of the fission power density of the fuel pin has been evaluated. • Radial/axial fission power density of the power peaked fuel pin has been evaluated. - Abstract: The new reactor concepts proposed in the Generation IV International Forum require the development and validation of new components and new materials. Inside the Collaborative Project on the European Sodium Fast Reactor, several accidental scenario have been studied. Nevertheless, none of them coped with mechanical safety assessment of the fuel cladding under accidental conditions. Among the accidental conditions considered, there is the unprotected transient of overpower (UTOP), due to the insertion, at the end of the first fuel cycle, of a positive reactivity into the reactor core as a consequence of the unexpected runaway of one control rod. The goal of the study was the search for a detailed distribution of the fission power, in the radial and axial directions, within the power peaked fuel pin under the above accidental conditions. Results show that after the control rod ejection an increase from 658 W/cm{sup 3} to 894 W/cm{sup 3}, i.e. of some 36%, is expected for the power peaked fuel pin. This information will represent the base to investigate, in a future work, the fuel cladding safety margin.

  13. Systems of mechanized and reactive droplets powered by multi-responsive surfactants

    Science.gov (United States)

    Yang, Zhijie; Wei, Jingjing; Sobolev, Yaroslav I.; Grzybowski, Bartosz A.

    2018-01-01

    Although ‘active’ surfactants, which are responsive to individual external stimuli such as temperature, electric or magnetic fields, light, redox processes or chemical agents, are well known, it would be interesting to combine several of these properties within one surfactant species. Such multi-responsive surfactants could provide ways of manipulating individual droplets and possibly assembling them into larger systems of dynamic reactors. Here we describe surfactants based on functionalized nanoparticle dimers that combine all of these and several other characteristics. These surfactants and therefore the droplets that they cover are simultaneously addressable by magnetic, optical and electric fields. As a result, the surfactant-covered droplets can be assembled into various hierarchical structures, including dynamic ones, in which light powers the rapid rotation of the droplets. Such rotating droplets can transfer mechanical torques to their non-nearest neighbours, thus acting like systems of mechanical gears. Furthermore, droplets of different types can be merged by applying electric fields and, owing to interfacial jamming, can form complex, non-spherical, ‘patchy’ structures with different surface regions covered with different surfactants. In systems of droplets that carry different chemicals, combinations of multiple stimuli can be used to control the orientations of the droplets, inter-droplet transport, mixing of contents and, ultimately, sequences of chemical reactions. Overall, the multi-responsive active surfactants that we describe provide an unprecedented level of flexibility with which liquid droplets can be manipulated, assembled and reacted.

  14. The comparative effectiveness of serving peak loads in the variants of providing nuclear power plants with a base load

    Science.gov (United States)

    Batenin, V. M.; Aminov, R. Z.; Shkret, A. F.; Garievskii, M. V.

    2012-07-01

    The present paper reports the results of an investigation into the effectiveness of serving peak loads in the variants of providing nuclear power plants with a base load through unloading condensing power plants, combined heat and power (CHP) plants, combined-cycle thermal power plants during night-time off-peak hours, the use of the off-peak electric power for power and heat supply, and water electrolysis with the use of hydrogen and oxygen for production of the peak electric power, as compared with the variant of the development of pumped storage hydropower plants.

  15. Exploring the Feasibility of Providing Electrical Power to Remote Bases Via Space-Based Solar Power Satellites

    Science.gov (United States)

    2013-06-01

    attributes vary by design alternative, to include transmitter size, rectenna size, power transmitted, mass of components, and number of launches...system attributes vary by design alternative, to include transmitter size, rectenna size, power transmitted, mass of components, and number of launches...32 e. Ground Power Receiver ( Rectenna

  16. Financial assistance for investments in wind power in Germany. Business incentives provided by the Deutsche Ausgleichsbank

    Energy Technology Data Exchange (ETDEWEB)

    Koch, M. [Deutsche Ausgleichsbank, Bonn (Germany)

    1995-12-31

    Within a generous financial framework investments in wind energy power have rapidly increased in Germany since the late 1980`s. In addition to direct subsidies or incentive stipulated by statutory provisions the DtA has encouraged investments in wind energy projects by loans at preferential interest rates with tremendous success and it will continue to do so. At present especially new ways of supporting environmental investments are being seek which have a cross-border environmental impact. The goal is to provide financial assistance both to domestic and foreign companies willing to invest in transboundary projects which may be located in East European Countries

  17. Dynamic power flow controllers

    Science.gov (United States)

    Divan, Deepakraj M.; Prasai, Anish

    2017-03-07

    Dynamic power flow controllers are provided. A dynamic power flow controller may comprise a transformer and a power converter. The power converter is subject to low voltage stresses and not floated at line voltage. In addition, the power converter is rated at a fraction of the total power controlled. A dynamic power flow controller controls both the real and the reactive power flow between two AC sources having the same frequency. A dynamic power flow controller inserts a voltage with controllable magnitude and phase between two AC sources; thereby effecting control of active and reactive power flows between two AC sources.

  18. Improved power-law estimates from multiple samples provided by millennium climate simulations

    Science.gov (United States)

    Henriksson, S. V.; Räisänen, P.; Silen, J.; Järvinen, H.; Laaksonen, A.

    2015-02-01

    Using the long annual mean temperature time series provided by millennium Earth System Model simulations and a method of discrete Fourier transform with varying starting point and length of time window together with averaging, we get good fits to power laws between two characteristic oscillatory timescales of the model climate: multidecadal (50-80 years) and El Nino (3-6 years) timescales. For global mean temperature, we fit β ˜ 0.35 in a relation S( f) ˜ f - β in a simulation without external climate forcing and β over 0.7 in a simulation with external forcing included. The power law is found both with and without external forcing despite the forcings, e.g. the volcanic forcing, not showing similar behaviour, indicating a nonlinear temperature response to time-varying forcing. We also fit a power law with β ˜ 8 to the narrow frequency range between El Nino frequencies (up to 1/(3.2 years)) and the Nyquist frequency (1/(2 years)). Also, monthly mean temperature time series are considered and a decent power-law fit for frequencies above 1/year is obtained. Regional variability in best-fit β is explored, and the impact of choosing the frequency range on the result is illustrated. When all resolved frequencies are used, land areas seem to have lower βs than ocean areas on average, but when fits are restricted to frequencies below 1/(6 years), this difference disappears, while regional differences still remain. Results compare well with measurements both for global mean temperature and for the central England temperature record.

  19. An Aircraft Electric Power Testbed for Validating Automatically Synthesized Reactive Control Protocols

    Science.gov (United States)

    2013-01-01

    we describe our recently developed simulation models and a hardware testbed for validating reactive controllers synthesized using TuLiP [1], a...temporal logic planning toolbox, in order to investigate the validity of the assumptions made in controller synthesis. TuLiP is a collection of Python... TuLiP can be used to synthesize logic so that the satisfaction of certain safety requirements is guaranteed. The synthesized logic enables the contac

  20. Supervisory Control for Real Time Reactive Power Flow Optimization in Islanded Microgrids

    DEFF Research Database (Denmark)

    Milczarek, Adam; Vasquez, Juan Carlos; Malinowski, Mariusz

    2013-01-01

    -line measurements. Similarly to any process system, MG hierarchical control is divided into three levels. However, an additional control algorithm is required to manage power transmission between sources and loads, maximizing efficiency and minimizing transmission losses. This real-time optimization problem...... is addressed to locally readjust converters operation to attain global efficiency. An algorithm is presented by formulating and solving the power sharing optimization problem in a two-level approach. The objective function is the sum of the apparent power transferred, whose minimization reduces total power...... losses and energy costs. The performance of the approach proposed is validated on a simulated case study. Different scenarios are tested and the performance of the algorithm is compared and discussed. The power losses reduction obtained with the proposed approach are compared with those obtained...

  1. “Simulation of Active and Reactive Power Control of DFIG”

    OpenAIRE

    Nidhish G Mishra; A. A. Shaikh,

    2016-01-01

    The penetration of wind energy generation units into existing electrical power system network is In creasing rapidly during recent years. The number of Doubly-Fed Induction Generator (DFIG) has grown over the last few years in several countries as a result of the tremendous increase in wind power generation. They use electronic converters in order to operate at different speeds. This converter system decouples the electrical and mechanical behavior of the generator from the grid v...

  2. Preliminary study on the reactivation of the WERAP small hydro power station in Bubikon; Vorstudie Kleinwasserkraftwerk WERAP Immobilien AG, Bubikon ZH. Revitalisierung des 100-jaehrigen Kraftwerkes

    Energy Technology Data Exchange (ETDEWEB)

    Bretscher, A.; Gutzwiller, S.

    2003-07-01

    This study on the revitalisation of a small hydro power station belonging to old spinning mill in Bubikon, Switzerland, proposes ideas for the reactivation of an old hydropower installation that once helped power a spinning mill. Details are given on the history of the mill and the hydrological conditions to be expected at the site. Three variants are proposed for the refurbishment, including the revision of the power station's existing 44 kW Francis turbine dating from 1908, the addition of further, similar Francis turbine or its replacement with a new 61 kW Francis turbine. The costs and amortisation of the refurbishment variants are examined, the revenues that can be expected from its operation and other financial factors are discussed. Further, environmental and legal aspects of the project are examined and suggestions are made for the next steps to be taken towards the realisation of this small hydropower plant. An annex provides photographs of the location and the power station's equipment.

  3. Low Power Testing—What Can Commercial Design-for-Test Tools Provide?

    OpenAIRE

    Xijiang Lin

    2011-01-01

    Minimizing power consumption during functional operation and during manufacturing tests has become one of the dominant requirements for the semiconductor designs in the past decade. From commercial design-for-test (DFT) tools’ point of view, this paper describes how DFT tools can help to achieve comprehensive testing of low power designs and reduce test power consumption during test application.

  4. Power Relations and Health Care Communication in Older Adulthood: Educating Recipients and Providers.

    Science.gov (United States)

    Eliassen, A Henry

    2016-12-01

    Unequal power relations lie just below the surface in much of today's discourse on health care communication with older adults. Focusing on pathologies or deficits tends to reinforce stereotypes of frailty and dependency, thus framing elders as a vulnerable group requiring special assistance. Implicit stereotyping frequently colors interactions of health care personnel with older clients and their families-interactions likely to affect elders' perceptions and health outcomes. Health care providers need to be attuned to the vast and growing diversity in today's older population, wherein many older adults are exemplars of what it takes to marshal resources and cope with multifaceted challenges. Thus, elders have the potential to teach medical personnel through narratives of resilience as well as tribulation. This potential can be fully realized, however, only in contexts where communication patterns characterized by paternalism, consumerism, and collaboration are mutually recognized and selectively challenged or implemented. Promising interventions to facilitate health care communication in older adulthood might well be directed toward (a) educating both recipients and providers to become more mindful of cues that evoke stereotypical thinking, (b) promoting an institutional culture that normalizes situationally appropriate assertive responses to stereotyping, and (c) formally ratifying older adults' life experience in the training of health care personnel. © The Author 2015. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  5. Intraspinal Sensory Neurons Provide Powerful Inhibition to Motor Circuits Ensuring Postural Control during Locomotion.

    Science.gov (United States)

    Hubbard, Jeffrey Michael; Böhm, Urs Lucas; Prendergast, Andrew; Tseng, Po-En Brian; Newman, Morgan; Stokes, Caleb; Wyart, Claire

    2016-11-07

    In the vertebrate spinal cord, cerebrospinal fluid-contacting neurons (CSF-cNs) are GABAergic neurons whose functions are only beginning to unfold. Recent evidence indicates that CSF-cNs detect local spinal bending and relay this mechanosensory feedback information to motor circuits, yet many CSF-cN targets remain unknown. Using optogenetics, patterned illumination, and in vivo electrophysiology, we show here that CSF-cNs provide somatic inhibition to fast motor neurons and excitatory sensory interneurons involved in the escape circuit. Ventral CSF-cNs respond to longitudinal spinal contractions and induce large inhibitory postsynaptic currents (IPSCs) sufficient to silence spiking of their targets. Upon repetitive stimulation, these IPSCs promptly depress, enabling the mechanosensory response to the first bend to be the most effective. When CSF-cNs are silenced, postural control is compromised, resulting in rollovers during escapes. Altogether, our data demonstrate how GABAergic sensory neurons provide powerful inhibitory feedback to the escape circuit to maintain balance during active locomotion. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Stability of nonlinear load electric arc furnaces in the presence of reactive power sources

    Directory of Open Access Journals (Sweden)

    Pegah Sagha

    2014-04-01

    Full Text Available This paper first discusses about Electric arc.the model used in this paper is a dynamic model shown with a differential equation. Then, this model is placed with power system model which is considered as a thevenin equivalent model,and whole dynamical system is derived. With linearization around the work places, Jacobian Matrix of the system was extracted and the stability of equilibrium points specificed. Infollow, restricted equation to the central manifold for system intended is achieved and using that, possible events in the system the critical values of the bifurcation parameter is investigated. At the end, the analytical result is compared with the simulation results obtained with the help of Auto software. Finally, we will conclude that, using one type of the analytical method, one split of power system is characterized, but with using Auto software, all bifurcation are identified in the power system.

  7. Raman Spectroscopy Provides a Powerful Diagnostic Tool for Accurate Determination of Albumin Glycation

    Science.gov (United States)

    Dingari, Narahara Chari; Horowitz, Gary L.; Kang, Jeon Woong; Dasari, Ramachandra R.; Barman, Ishan

    2012-01-01

    We present the first demonstration of glycated albumin detection and quantification using Raman spectroscopy without the addition of reagents. Glycated albumin is an important marker for monitoring the long-term glycemic history of diabetics, especially as its concentrations, in contrast to glycated hemoglobin levels, are unaffected by changes in erythrocyte life times. Clinically, glycated albumin concentrations show a strong correlation with the development of serious diabetes complications including nephropathy and retinopathy. In this article, we propose and evaluate the efficacy of Raman spectroscopy for determination of this important analyte. By utilizing the pre-concentration obtained through drop-coating deposition, we show that glycation of albumin leads to subtle, but consistent, changes in vibrational features, which with the help of multivariate classification techniques can be used to discriminate glycated albumin from the unglycated variant with 100% accuracy. Moreover, we demonstrate that the calibration model developed on the glycated albumin spectral dataset shows high predictive power, even at substantially lower concentrations than those typically encountered in clinical practice. In fact, the limit of detection for glycated albumin measurements is calculated to be approximately four times lower than its minimum physiological concentration. Importantly, in relation to the existing detection methods for glycated albumin, the proposed method is also completely reagent-free, requires barely any sample preparation and has the potential for simultaneous determination of glycated hemoglobin levels as well. Given these key advantages, we believe that the proposed approach can provide a uniquely powerful tool for quantification of glycation status of proteins in biopharmaceutical development as well as for glycemic marker determination in routine clinical diagnostics in the future. PMID:22393405

  8. Reactive Power Compensation of a 24 MW Wind Farm using a 12-Pulse Voltage Source Converter

    DEFF Research Database (Denmark)

    Pedersen, Knud Ole Helgesen; Pedersen, Jørgen Kaas

    1998-01-01

    Integration of large wind farms in distribution and transmission systems may have severe influence on the power quality at the connection point and may also influence the voltage controlling capability of the electrical system. The purpose of the described project has been to develop and investig......Integration of large wind farms in distribution and transmission systems may have severe influence on the power quality at the connection point and may also influence the voltage controlling capability of the electrical system. The purpose of the described project has been to develop...... and investigate the use of a STATCOM by modelling and field testing an 8 MVar unit in a 24 MW wind farm....

  9. DC microgrids with energy storage systems and demand response for providing support to frequency regulation of electrical power systems

    DEFF Research Database (Denmark)

    Basic, Hrvoje; Dragicevic, Tomislav; Pandzic, Hrvoje

    2017-01-01

    Frequency regulation of electric power systems efficiency depends on response time and on power reserves for frequency regulation. As integration of non-dispatchable renewable generation in the power system results with increased need for power reserves from fast responding power units, the idea...... of using aggregated DC microgrids in frequency regulation is presented. Model proposed in this work is based on using battery energy storage, combined with demand response for achieving efficient usage of battery energy storage. It is shown that large number of DC microgrids can provide sufficient....

  10. Calculation methods of reactivity using derivatives of nuclear power and Filter fir; Metodos para o calculo da reatividade usando derivadas da potencia nuclear e o filtro FIR

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, Daniel Suescun

    2007-07-01

    This work presents two new methods for the solution of the inverse point kinetics equation. The first method is based on the integration by parts of the integral of the inverse point kinetics equation, which results in a power series in terms of the nuclear power in time dependence. Applying some conditions to the nuclear power, the reactivity is represented as first and second derivatives of this nuclear power. This new calculation method for reactivity has special characteristics, amongst which the possibility of using different sampling periods, and the possibility of restarting the calculation, after its interruption associated it with a possible equipment malfunction, allowing the calculation of reactivity in a non-continuous way. Apart from this reactivity can be obtained with or without dependency on the nuclear power memory. The second method is based on the Laplace transform of the point kinetics equations, resulting in an expression equivalent to the inverse kinetics equation as a function of the power history. The reactivity can be written in terms of the summation of convolution with response to impulse, characteristic of a linear system. For its digital form the Z-transform is used, which is the discrete version of the Laplace transform. In this method it can be pointed out that the linear part is equivalent to a filter named Finite Impulse Response (Fir). The Fir filter will always be, stable and non-varying in time, and, apart from this, it can be implemented in the non-recursive way. This type of implementation does not require feedback, allowing the calculation of reactivity in a continuous way. The proposed methods were validated using signals with random noise and showing the relationship between the reactivity difference and the degree of the random noise. (author)

  11. Reactive power and voltage control based on general quantum genetic algorithms

    DEFF Research Database (Denmark)

    Vlachogiannis, Ioannis (John); Østergaard, Jacob

    2009-01-01

    This paper presents an improved evolutionary algorithm based on quantum computing for optima l steady-state performance of power systems. However, the proposed general quantum genetic algorithm (GQ-GA) can be applied in various combinatorial optimization problems. In this study the GQ-GA determin...

  12. Integration of Renewable Energy for the Harmonic Current and Reactive Power Compensation

    DEFF Research Database (Denmark)

    Pouresmaeil, Edris; Shaker, Hamid Reza; Mehrasa, Majid

    2015-01-01

    This paper deals with a control technique for multilevel converter topologies base on Direct Lyapunov Control Method (DLCM) for integration of Renewable Energy Resources (RER) into the power grid. The compensation of variations in reference current components is considered properly in this control...

  13. Relationship between anaerobic parameters provided from MAOD and critical power model in specific table tennis test.

    Science.gov (United States)

    Zagatto, A M; Gobatto, C A

    2012-08-01

    The aim of this study was to verify the validity of the curvature constant parameter (W'), calculated from 2-parameter mathematical equations of critical power model, in estimating the anaerobic capacity and anaerobic work capacity from a table tennis-specific test. Specifically, we aimed to i) compare constants estimated from three critical intensity models in a table tennis-specific test (Cf); ii) correlate each estimated W' with the maximal accumulated oxygen deficit (MAOD); iii) correlate each W' with the total amount of anaerobic work (W ANAER) performed in each exercise bout performed during the Cf test. Nine national-standard male table tennis players participated in the study. MAOD was 63.0(10.8) mL · kg - 1 and W' values were 32.8(6.6) balls for the linear-frequency model, 38.3(6.9) balls for linear-total balls model, 48.7(8.9) balls for Nonlinear-2 parameter model. Estimated W' from the Nonlinear 2-parameter model was significantly different from W' from the other 2 models (P0.13). Thus, W' estimated from the 2-parameter mathematical equations did not correlate with MAOD or W ANAER in table tennis-specific tests, indicating that W' may not provide a strong and valid estimation of anaerobic capacity and anaerobic capacity work. © Georg Thieme Verlag KG Stuttgart · New York.

  14. Measuring modules for the research of compensators of reactive power with voltage stabilization in MATLAB

    Science.gov (United States)

    Vlasayevsky, Stanislav; Klimash, Stepan; Klimash, Vladimir

    2017-10-01

    A set of mathematical modules was developed for evaluation the energy performance in the research of electrical systems and complexes in the MatLab. In the electrotechnical library SimPowerSystems of the MatLab software, there are no measuring modules of energy coefficients characterizing the quality of electricity and the energy efficiency of electrical apparatus. Modules are designed to calculate energy coefficients characterizing the quality of electricity (current distortion and voltage distortion) and energy efficiency indicators (power factor and efficiency) are presented. There are described the methods and principles of building the modules. The detailed schemes of modules built on the elements of the Simulink Library are presented, in this connection, these modules are compatible with mathematical models of electrical systems and complexes in the MatLab. Also there are presented the results of the testing of the developed modules and the results of their verification on the schemes that have analytical expressions of energy indicators.

  15. Multiobjective optimization of the reactive power compensation in electric distribution systems

    Directory of Open Access Journals (Sweden)

    Manoel Socorro Santos-Azevedo

    2014-01-01

    Full Text Available Se han empleado diferentes métodos de optimización para la sele cción y localización de bancos de capacitores en circuitos de distribución. Sin embargo, hay que considerar la distorsión pro ducida por los armónicos de las cargas no-lineales y la posible aparición de resonancias entre los elementos inductivos del sistema y los bancos de capacitores existentes. Por otra parte, no se ha int egrado en una sola metodología la utilización de bancos de capacitores y de f iltros pasivos de harmónicos para compensar la potencia reactiv a en sistemas de distribución contaminados por armónicos. El present e trabajo se propone como objetivo desarrollar dicha metodologí a. El programa desarrollado se basa en el algoritmo de optimización m ultiobjetivo NSGA-II que se prueba con éxito en varios ejemplos prácticos.

  16. A Study on Real-Time Pricing Method of Reactive Power in Voltage Profile Control Method of Future Distribution Network

    Science.gov (United States)

    Koide, Akira; Tsuji, Takao; Oyama, Tsutomu; Hashiguchi, Takuhei; Goda, Tadahiro; Shinji, Takao; Tsujita, Shinsuke

    It is of prime importance to solve the voltage maintenance problem caused by the introduction of a large number of distributed generators. The authors have proposed “voltage profile control method” using reactive power control of distributed generators and developed new systems which can give economical incentives to DG owners who cooperate the voltage profile management in the previous works. However, it is difficult to apply the proposed economical systems to real-time operation because they are based on the optimization technology and the specific amount of incentive is informed after the control action has finished. Therefore, in this paper, we develop a new method that can determine the amount of incentives in real-time and encourage the costumers to cooperate voltage profile control method. The proposed method is tested in one feeder distribution network and its effectiveness is shown.

  17. Integration of heterogeneous industrial consumers to provide regulating power to the smart grid

    DEFF Research Database (Denmark)

    Rahnama, Samira; Stoustrup, Jakob; Rasmussen, Henrik

    2013-01-01

    In this paper, we propose a framework to utilize the flexibility of consumers in the future smart grid with a high share of fluctuating power. Focus is on industrial cases, where a total power consumption of a few number of consumers are large enough in order to bid in the market. Heterogeneous c...

  18. Reactive power predispatch in the economical dispatch of multimodal hydroelectric systems; Predespacho de potencia reactiva en el despacho economico de sistemas hidrotermicos multinodales

    Energy Technology Data Exchange (ETDEWEB)

    Dona, Victor M.; Hoese, Alejandro; Vargas, Alberto [Universidad Nacional de San Juan (Argentina). Instituto de Energia Electrica]. E-mail: vdona@iee.unsj.edu.ar

    2001-07-01

    The reactive power dispatch in generators and compensation equipment is necessary to the effects of maintaining an appropriate voltage level in the entire electric system. The lack of an appropriate dispatch programming for reactive power, can implies in a forced and not programmed operation of generator units. This contemplates in an unfavorable way in the operation costs when an entire optimization period is analyzed. This paper presents an associated predispatch proposal of generator units to the voltage-reactive power control needs, which is accomplished within the economical dispatch calculation during the operation programming process of an electric system. Finally, it is shown the main methodological aspects and results related to a real network.

  19. Forty candles for the Rance River TPP tides provide renewable and sustainable power generation

    Energy Technology Data Exchange (ETDEWEB)

    Charlier, Roger H. [Free University of Brussels (V.U.B.), Brussels (Belgium)

    2007-12-15

    Prices of oil and other fossil fuels have proven a powerful incentive for the alternative energy hunters. The alternatives include the various forms of ocean energy that, often considered uneconomical for electricity generation, have become attractive and competitive. Many sites throughout the world have been considered, at one time or another, suitable for implantation of a tidal power station, but very few have witnessed implementation of often ambitious plans. The Rance River tidal power plant, near St Malo in Brittany (France) is an exception. It is celebrating in 2006, 40 years of durable, loyal and productive service. (author)

  20. DC microgrids providing frequency regulation in electrical power system - imperfect communication issues

    DEFF Research Database (Denmark)

    Bašić, Hrvoje; Dragicevic, Tomislav; Pandžić, Hrvoje

    2017-01-01

    This paper presents a model of multiple DC microgrids with battery energy storage systems and demand response capability, taking part in primary frequency regulation of electrical power system. Although DC microgrids can contribute to stability and efficiency of frequency regulation, these complex...... systems may cause serious stability issues due to the imperfect communication. This work presents possible scenarios of unstable primary frequency regulation in a simplified model of electrical power system with DC microgrids, which are controlled through communication network....

  1. Dynamic compensation of real and reactive power in wind farms using STATCOM

    Directory of Open Access Journals (Sweden)

    Shahzad Ahsan

    2016-09-01

    Full Text Available The dynamic stability of Squirrel Cage Induction Generators (SCIG based wind turbines may be improved by Static Synchronous Compensator (STATCOM. At the time of starting of wind farm and during short circuit fault the voltage of bus connecting the wind farm reduces drastically (Chen, 2005. A controller for the STATCOM has been developed with its capability to coordinate between the positive and the negative sequences of the grid voltage. This paper investigates effects of Squirrel Cage Induction Generator (SCIG in combination with a Static Synchronous Compensator (STATCOM under normal and during fault condition (Inwai et al., 2005. The results show that the STATCOM can regulate the fast changing voltage at the point of common coupling between the wind farm and the grid in normal and during fault condition. Also it can supply the active power during the short circuit fault condition.

  2. Assessment of transient stability of cable based transmission grids with reactive power compensation

    DEFF Research Database (Denmark)

    Foo, Yii; Dall, Laurids; Silva, Filipe Miguel Faria da

    2017-01-01

    through a series of sensitivity analysis with respect to the cables compensation degree. A separate case of disconnecting the SRs of the faulted line is also carried out. The tendencies are initially observed and explained for smaller systems, Single-Machine Infinite Bus (SMIB) and 9-bus system...... by switching out the corresponding SRs of the faulted line when the line is taken out of service. Over-compensation without SR switching, also leads to a positive effect on the transient stability. However, over-compensation improves the excitation condition of the SGs at the expense of voltage stability......Underground transmission cables are gaining popularity due to its applications near cities and aesthetic purpose. For example in Denmark, the transmission power grid is changing significantly as many conventional overhead lines (OHL) are replaced by cables and more is expected over the coming years...

  3. Reactive power prices at competitive electric markets through methodology based on marginal costs; Precios de potencia reactiva en mercados electricos competitivos a traves de metodologia basada en costos marginales

    Energy Technology Data Exchange (ETDEWEB)

    Dona, Victor M.; Paredes, Andres [Universidad Nacional de San Juan (Argentina). Instituto de Energia Electrica]. E-mail: vdona@iee.unsj.edu.ar

    2001-07-01

    This paper presents the development and application of a methodology based on the marginal cost theory of reactive and active power, and also on optimization techniques. The methodology allows to find economic signals of active and reactive power at nodal level, and allows the defining of rewarding criteria of the reactive power transportation detecting responsibilities among the transporters and distributors in the generation-consuming of reactive power. The paper also shows main methodological design and the results of the application interconnection argentin system.

  4. Voltage sensitivity based reactive power control on VSC-HVDC in a wind farm connected hybrid multi-infeed HVDC system

    DEFF Research Database (Denmark)

    Liu, Yan; Chen, Zhe

    2013-01-01

    With increasing application of both Line Commutated Converter based High Voltage Direct Current (LCC-HVDC) systems and Voltage Source Converter based HVDC (VSC-HVDC) links, a new type of system structure named Hybrid Multi-Infeed HVDC (HMIDC) system is formed in the modern power systems. This paper...... presents the operation and control method of the wind farm connected HMIDC system. The wind power fluctuation takes large influence to the system voltages. In order to reduce the voltage fluctuation of LCC-HVDC infeed bus caused by the wind power variation, a voltage sensitivity-based reactive power...

  5. Providing Contexts for Understanding Musical Narratives of Power in the Classroom: Music, Politics, and Power in Grenada, West Indies

    Science.gov (United States)

    Sirek, Danielle

    2016-01-01

    The role of music in Grenada, West Indies has traditionally been to pass on knowledges, values, and ideals; and to provide a means of connecting to one another through expressing commonality of experience, ancestry, and nationhood. This paper explores how Eric Matthew Gairy, during his era of political leadership in Grenada (1951-1979), exploited…

  6. Providing Efficient Network Access to Green Power Generators : A Long-term Property Rights Perspective

    NARCIS (Netherlands)

    Petropoulos, G.; Willems, Bert

    2017-01-01

    Coordinating the timing of new production facilities is one of the challenges of liberalized power sectors. It is complicated by the presence of transmission bottlenecks, oligopolistic competition and the unknown prospects of low-carbon technologies. We build a model encompassing a late and early

  7. Ensured power supply and environmental protection as elements of a provident social policy

    Science.gov (United States)

    Hartkopf, G.

    1980-09-01

    The conflict situation between the industry and environmental protection, which has developed in post-war Germany is examined in the light of the current governmental approach to the power supply problem. Means of resolving the principal problem areas are discussed.

  8. Containment and Consensus-based Distributed Coordination Control to Achieve Bounded Voltage and Precise Reactive Power Sharing in Islanded AC Microgrids

    DEFF Research Database (Denmark)

    Han, Renke; Meng, Lexuan; Ferrari-Trecate, Giancarlo

    2017-01-01

    for coordinated control design. Furthermore, a containment and consensus-based distributed coordination controller is proposed, by which the bus voltage magnitudes can be bounded within a reasonable range, instead of only controlling average voltage value. Further, the accurate reactive power sharing between...

  9. Provide for the Common Defence: Rebalancing Constitutional War Powers in the 21st Century

    Science.gov (United States)

    2015-04-13

    2 Congressional Protection of Legislative War Powers Senate opposition to the Treaty of Versailles , and the corresponding League of Nations, at...thirds of the Senate would be required to conclude peace treaties . The arrangement placed a legislative control on potentially unethical executives...executive interpretation of a standing treaty by George Washington gave rise to another debate between Hamilton and Madison. The Treaty of Alliance and

  10. Allocation of reactive power support, active loss balancing and demand interruption ancillary services in MicroGrids

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Mario Helder [Departamento de Engenharia Electrotecnica, Instituto Politecnico de Tomar, Quinta do Contador, Estrada da Serra, 2300 Tomar (Portugal); Saraiva, Joao Tome [INESC Porto and Faculdade de Engenharia da Universidade do Porto, Campus da FEUP, Rua Dr. Roberto Frias, 4200 - 465 Porto (Portugal)

    2010-10-15

    MicroGrids represent a new paradigm for the operation of distribution systems and there are several advantages as well as challenges regarding their development. One of the advantages is related with the participation of MicroGrid agents in electricity markets and in the provision of ancillary services. This paper describes two optimization models to allocate three ancillary services among MicroGrid agents - reactive power/voltage control, active loss balancing and demand interruption. These models assume that MicroGrid agents participate in the day-ahead market sending their bids to the MicroGrid Central Controller, MGCC, that acts as an interface with the Market Operator. Once the Market Operator returns the economic dispatch of the MicroGrid agents, the MGCC checks its technical feasibility (namely voltage magnitude and branch flow limits) and activates an adjustment market to change the initial schedule and to allocate these three ancillary services. One of the models has crisp nature considering that voltage and branch flow limits are rigid while the second one admits that voltage and branch flow limits are modeled in a soft way using Fuzzy Set concepts. Finally, the paper illustrates the application of these models with a Case Study using a 55 node MV/LV network. (author)

  11. Experiences in simulating and testing coordinated voltage control provided by multiple wind power plants

    Energy Technology Data Exchange (ETDEWEB)

    Arlaban, T.; Alonso, O.; Ortiz, D. [Acciona Windpower S.A. (Spain); Peiro, J.; Rivas, R. [Red Electrica de Espana SAU (Spain); Quinonez-Varela, G.; Lorenzo, P. [Acciona Energia S.A. (Spain)

    2011-07-01

    This document presents some field tests performed in a transmission system node in order to check the adequacy of voltage control performance by multiple wind power plants, with an overall capacity of 395 MW. It briefly explains the Spanish TSO motivation towards new voltage control requirements and the necessity of performing such tests in order to set the most convenient voltage control parameters and to verify the stable operation. It presents how different the voltage control capability between modern wind turbines (DFIG) and older ones (SCIG) specifically retrofitted for voltage control is. (orig.)

  12. Reactive Power Control of Single-Stage Three-Phase Photovoltaic System during Grid Faults Using Recurrent Fuzzy Cerebellar Model Articulation Neural Network

    Directory of Open Access Journals (Sweden)

    Faa-Jeng Lin

    2014-01-01

    Full Text Available This study presents a new active and reactive power control scheme for a single-stage three-phase grid-connected photovoltaic (PV system during grid faults. The presented PV system utilizes a single-stage three-phase current-controlled voltage-source inverter to achieve the maximum power point tracking (MPPT control of the PV panel with the function of low voltage ride through (LVRT. Moreover, a formula based on positive sequence voltage for evaluating the percentage of voltage sag is derived to determine the ratio of the injected reactive current to satisfy the LVRT regulations. To reduce the risk of overcurrent during LVRT operation, a current limit is predefined for the injection of reactive current. Furthermore, the control of active and reactive power is designed using a two-dimensional recurrent fuzzy cerebellar model articulation neural network (2D-RFCMANN. In addition, the online learning laws of 2D-RFCMANN are derived according to gradient descent method with varied learning-rate coefficients for network parameters to assure the convergence of the tracking error. Finally, some experimental tests are realized to validate the effectiveness of the proposed control scheme.

  13. The Impact of Providing Web-Based PowerPoint Slides as Study Guides in Undergraduate Business Classes

    Science.gov (United States)

    Frank, Jonathan; Shaw, Lewis; Wilson, Elizabeth

    2009-01-01

    This study examines undergraduate business students' use of PowerPoint slides provided as a supplement to class attendance, textbook reading, and other traditional course resources. We survey students in 4 diverse (accounting, marketing, management, and information systems) lower-level undergraduate courses in which the instructor provided…

  14. 76 FR 45248 - PJM Interconnection, L.L.C., PJM Power Providers Group v. PJM Interconnection, L.L.C...

    Science.gov (United States)

    2011-07-28

    ... Energy Regulatory Commission PJM Interconnection, L.L.C., PJM Power Providers Group v. PJM Interconnection, L.L.C.; Supplemental Notice of Staff Technical Conference On June 13, 2011, the Commission issued... Resources Services, Inc., Maryland Public Service Commission, Monitoring Analytics, L.L.C., National Rural...

  15. INFORMATIVE ADVERTISING: A MARKET INFORMATION PROVIDER OR A SEED OF MARKET POWER?

    Directory of Open Access Journals (Sweden)

    Anzhelika G. GERASYMENKO

    2012-07-01

    Full Text Available This paper investigates the role of informative advertising in creation and augment of market power as well as the ability of an advertiser to maximize the value of its economic rent. Informative advertising is considered to be a merit good unlike a persuasive one that is mostly associated with a bad. But analysis of the advertisement breakdown in Ukraine shows that the share of price advertisements, which are the most beneficial for the public, is negligible today. Further still those advertisements are mostly situated in the sectors, where price competition is the least strong. Another kind of informative advertising – differentiating advertising – turns from an instrument of informing consumers into the vehicle of manipulation of consumer choice. Using the blind tests the author has compared the quality and the prices of the range of advertised goods and has found out a low level of correlation between the variables. That means that informative advertising serves a function of informing consumers inefficiently. At the same time phantom differentiation and misleading advertising proliferation as well as informative advertising concentration on experience and credible goods instead search ones testify to effective serving a function of maximizing advertiser welfare.

  16. Candesartan and amlodipine combination therapy provides powerful vascular protection in stroke-prone spontaneously hypertensive rats.

    Science.gov (United States)

    Takai, Shinji; Jin, Denan; Shimosato, Takashi; Sakonjo, Hiroshi; Miyazaki, Mizuo

    2011-02-01

    The vascular protective effects of placebo, candesartan (1 mg kg(-1) per day) monotherapy, candesartan (1 mg kg(-1) per day) and amlodipine (1 mg kg(-1) per day) combination therapy, and candesartan (1 mg kg(-1) per day) and hydrochlorothiazide (HCTZ) (10 mg kg(-1) per day) combination therapy for 2 weeks were compared in stroke-prone, spontaneously hypertensive rats. Candesartan monotherapy significantly reduced blood pressure, and both combination therapies were equally and significantly lower than the monotherapy. Acetylcholine-induced vascular relaxation was significantly stronger in all therapeutic groups than in the placebo-treated group. Furthermore, the relaxation was significantly stronger in the candesartan plus amlodipine-treated group than in the candesartan-treated group; however, there was no significant difference between the candesartan- and candesartan plus HCTZ-treated groups. Vascular gene expressions of the NADPH oxidase subunits p22(phox), gp91(phox), NOX1 and NOX4 were significantly attenuated in all therapeutic groups compared with the placebo-treated group, and there were no significant differences among those groups. However, a significant augmentation of vascular superoxide dismutase activity was observed in the candesartan plus amlodipine-treated group, but not in other groups. Malondialdehyde levels in the vascular tissues were significantly attenuated in all therapeutic groups. Compared with the candesartan-treated group, significant attenuation was observed in the candesartan plus amlodipine-treated group, but not in the candesartan plus HCTZ-treated group. Immunohistological analysis showed that areas positive for 4-hydroxy-2-nonenal were significantly reduced in all therapeutic groups, but this reduction was significantly greater for the candesartan plus amlodipine-treated group than for the candesartan-treated group. Thus, candesartan and amlodipine combination therapy could have a powerful protective effect in vascular tissues via

  17. Process- and optoelectronic-control of NiOx thin films deposited by reactive high power impulse magnetron sputtering

    Science.gov (United States)

    Keraudy, Julien; Delfour-Peyrethon, Brice; Ferrec, Axel; Garcia Molleja, Javier; Richard-Plouet, Mireille; Payen, Christophe; Hamon, Jonathan; Corraze, Benoît; Goullet, Antoine; Jouan, Pierre-Yves

    2017-05-01

    In this contribution, based on the analyses of the discharge behavior as well as final properties of the deposited Ni-O films during reactive high power impulse magnetron sputtering discharge, we have demonstrated that monitoring the oxygen flow rate leads to 4 different regimes of discharge. Tuning the oxygen partial pressure allows deposition of a large range of chemical compositions from pure nickel to nickel-deficient NiOx (x > 1) in the poisoned mode. Investigation of the plasma dynamics by time-resolved optical emission spectroscopy suggests that the discharge behavior in the poisoned mode principally comes from the higher contribution of both oxygen and argon ions in the total ionic current, leading to a change in the ion induced secondary electron emission coefficient. Additionally, material characterizations have revealed that optoelectronic properties of NiOx films can be easily tuned by adjusting the O/Ni ratio, which is influenced by the change of the oxygen flow rate. Stoichiometric NiO films (O/Ni ratio ˜ 1) are transparent in the visible range with a transmittance ˜80% and insulating as expected with an electrical resistivity ˜106 Ω cm. On the other hand, increasing the O/Ni > 1 leads to the deposition of more conductive coating (ρ ˜ 10 Ω cm) films with a lower transmittance ˜ 50%. These optoelectronic evolutions are accompanied by a band-gap narrowing 3.65 to 3.37 eV originating from the introduction of acceptor states between the Fermi level and the valence band maximum. In addition, our analysis has demonstrated that nickel vacancies are homogeneously distributed over the film thickness, explaining the p-type of the films.

  18. A New Reactive-Power Sharing Scheme for Two Inverter-Based Distributed Generations with Unequal Line Impedances in Islanded Microgrids

    Directory of Open Access Journals (Sweden)

    Jae-Hyuk Kim

    2017-11-01

    Full Text Available This paper proposes a new reactive-power sharing scheme to reduce the circulating current when two inverter-based distributed generations (DGs operate in parallel through unequal line impedances in an islanded microgrid. If the terminal voltages of the two DGs are not equal due to the unequal line impedances, a circulating current due to reactive-power unbalance occurs, which increases system loss. The proposed droop control compensates the terminal voltage difference to reduce the circulating current by considering a feed-forward path of the line voltage drop. The feasibility of the proposed droop control was first verified through computer simulations, and then experiments with a hardware set-up in the lab. The experimental results were compared with the simulation results to confirm the feasibility of the proposed droop control.

  19. Percutaneous Biopsy and Radiofrequency Ablation of Osteoid Osteoma with Excess Reactive New Bone Formation and Cortical Thickening Using a Battery-Powered Drill for Access: A Technical Note

    Energy Technology Data Exchange (ETDEWEB)

    Filippiadis, D., E-mail: dfilippiadis@yahoo.gr; Gkizas, C., E-mail: chgkizas@gmail.com; Kostantos, C., E-mail: drkarpen@yahoo.gr; Mazioti, A., E-mail: argyromazioti@yahoo.gr; Reppas, L., E-mail: l.reppas@yahoo.com; Brountzos, E., E-mail: ebrountz@med.uoa.gr; Kelekis, N., E-mail: kelnik@med.uoa.gr; Kelekis, A., E-mail: akelekis@med.uoa.gr [University General Hospital “ATTIKON”, 2nd Radiology Department (Greece)

    2016-10-15

    PurposeTo report our experience with the use of a battery-powered drill in biopsy and radiofrequency ablation of osteoid osteoma with excess reactive new bone formation. The battery-powered drill enables obtaining the sample while drilling.Materials and MethodsDuring the last 18 months, 14 patients suffering from painful osteoid osteoma with excess reactive new bone formation underwent CT-guided biopsy and radiofrequency ablation. In order to assess and sample the nidus of the osteoid osteoma, a battery-powered drill was used. Biopsy was performed in all cases. Then, coaxially, a radiofrequency electrode was inserted and ablation was performed with osteoid osteoma protocol. Procedure time (i.e., drilling including local anesthesia), amount of scans, technical and clinical success, and the results of biopsy are reported.ResultsAccess to the nidus through the excess reactive new bone formation was feasible in all cases. Median procedure time was 50.5 min. Histologic verification of osteoid osteoma was performed in all cases. Radiofrequency electrode was coaxially inserted within the nidus and ablation was successfully performed in all lesions. Median amount CT scans, performed to control correct positioning of the drill and precise electrode placement within the nidus was 11. There were no complications or material failure reported in our study.ConclusionsThe use of battery-powered drill facilitates access to the osteoid osteoma nidus in cases where excess reactive new bone formation is present. Biopsy needle can be used for channel creation during the access offering at the same time the possibility to extract bone samples.

  20. MODEL REQUEST FOR PROPOSALS TO PROVIDE ENERGY AND OTHER ATTRIBUTES FROM AN OFFSHORE WIND POWER PROJECT

    Energy Technology Data Exchange (ETDEWEB)

    Jeremy Firestone; Dawn Kurtz Crompton

    2011-10-22

    This document provides a model RFP for new generation. The 'base' RFP is for a single-source offshore wind RFP. Required modifications are noted should a state or utility seek multi-source bids (e.g., all renewables or all sources). The model is premised on proposals meeting threshold requirements (e.g., a MW range of generating capacity and a range in terms of years), RFP issuer preferences (e.g., likelihood of commercial operation by a date certain, price certainty, and reduction in congestion), and evaluation criteria, along with a series of plans (e.g., site, environmental effects, construction, community outreach, interconnection, etc.). The Model RFP places the most weight on project risk (45%), followed by project economics (35%), and environmental and social considerations (20%). However, if a multi-source RFP is put forward, the sponsor would need to either add per-MWh technology-specific, life-cycle climate (CO2), environmental and health impact costs to bid prices under the 'Project Economics' category or it should increase the weight given to the 'Environmental and Social Considerations' category.

  1. Parametric identification of an asynchronous machine by the reactive power method; Identificacao parametrica de uma maquina assincrona pelo metodo da potencia reativa

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Alexandre Alves Sampaio e

    1996-07-01

    The obtention of the electrical and mechanical parameters of a squirrel-cage induction motor is investigated. Two methods of identification are studied: the reactive power method, used to determine the electrical parameters and an acceleration method on a startup test used to to find the mechanical ones. The method of reactive power is developed by analysing the machine steady state operation. In this analysis, a relationship between the electrical parameters and the reactive power is obtained. A minimization algorithm is used to determine the parameters based on this relationship. The acceleration method uses an acquisition of the transient variables, which is used in a recursive least square method furnishing the mechanical parameters. Both of methods are implemented on a special hardware and software system, consisting of sensors and A/D boards that make a digital acquisition of voltage, current and speed values. The validation procedures for the method and parameters are based on comparing between the real and simulated evaluation of the dynamical behavior of the motor in a startup test. The skin-effect influence over some of the motor parameters was also discussed. (author)

  2. Reactive Power Control of Single-Stage Three-Phase Photovoltaic System during Grid Faults Using Recurrent Fuzzy Cerebellar Model Articulation Neural Network

    OpenAIRE

    Faa-Jeng Lin; Kuang-Chin Lu; Hsuan-Yu Lee

    2014-01-01

    This study presents a new active and reactive power control scheme for a single-stage three-phase grid-connected photovoltaic (PV) system during grid faults. The presented PV system utilizes a single-stage three-phase current-controlled voltage-source inverter to achieve the maximum power point tracking (MPPT) control of the PV panel with the function of low voltage ride through (LVRT). Moreover, a formula based on positive sequence voltage for evaluating the percentage of voltage sag is deri...

  3. Powerful reactive sorption of silver(I) and mercury(II) onto poly(o-phenylenediamine) microparticles.

    Science.gov (United States)

    Li, Xin-Gui; Ma, Xiao-Li; Sun, Jin; Huang, Mei-Rong

    2009-02-03

    The strong adsorbability of Ag(I) and Hg(II) ions onto fine poly(o-phenylenediamine) (PoPD) microparticles synthesized through a chemically oxidative polymerization of o-phenylenediamine was systematically examined and PoPD/Ag nanocomposites were facilely prepared through the reactive sorption method. The effect of the (NH4)2S2O8 oxidant/o-phenylenediamine monomer ratio on the polymerization yield, macromolecular structure, conductivity, and insolubility of the PoPD microparticles was studied. The Ag(I) adsorbability of the microparticles was significantly optimized by varying the oxidant/monomer ratio, doping state, Ag(I) concentration, sorption time, and solution pH. The Ag(I) adsorbance steadily increases with changing oxidant/monomer molar ratio from 3/1 to 1/1, reaching up to the highest Ag(I) adsorbance of 533 mg.g(-1) at the oxidant/monomer ratio of 1/1. The sorption process fits the pseudosecond-order kinetics. The sorption is rapid because both the adsorbance and adsorptivity within 30 min reach up to 76% of the final values. The initial sorption rate of silver ions obtained from the pseudosecond-order equation is 12.9 mg.g(-1).min(-1). The highest adsorptivity of silver ions is up to 99.1%. The optimal solution pH for Ag(I) sorption is around 5.0. The sorption mechanism may include the chelation and redox reaction between Ag(I) ions and amine/imine groups on the PoPD chains. Similarly, the microparticles also have powerful Hg(II) adsorbability with 96.7% adsorptivity at an initial Hg(II) concentration of 4 mM. Competitive sorption between Ag(I) and Hg(II) in their mixture solution onto the microparticles was studied, exhibiting a preferential sorption toward Ag(I). The microparticles as a cost-effective sorbent demonstrate a promising application in the removal and even recovery of heavy-metal ions from wastewater. The PoPD/Ag nanocomposites possess (1) high Ag content of 34.8 wt %, (2) small diameter of Ag nanoparticles of around 10-20 nm, (3) narrow

  4. Calculation and comparison of xenon and samarium reactivities of the HEU, LEU core in the low power research reactor.

    Science.gov (United States)

    Dawahra, S; Khattab, K; Saba, G

    2015-07-01

    Comparative studies for the conversion of the fuel from HEU to LEU in the Miniature Neutron Source Reactor (MNSR) have been performed using the MCNP4C and GETERA codes. The precise calculations of (135)Xe and (149)Sm concentrations and reactivities were carried out and compared during the MNSR operation time and after shutdown for the existing HEU fuel (UAl4-Al, 90% enriched) and the potential LEU fuels (U3Si2-Al, U3Si-Al, U9Mo-Al, 19.75% enriched and UO2, 12.6% enriched) in this paper using the MCNP4C and GETERA codes. It was found that the (135)Xe and (149)Sm reactivities did not reach their equilibrium reactivities during the daily operating time of the reactor. The (149)Sm reactivities could be neglected compared to (135)Xe reactivities during the reactor operating time and after shutdown. The calculations for the UAl4-Al produced the highest (135)Xe reactivity in all the studied fuel group during the reactor operation (0.39 mk) and after the reactor shutdown (0.735 mk), It followed by U3Si-Al (0.34 mk, 0.653 mk), U3Si2-Al (0.33 mk, 0.634 mk), U9Mo-Al (0.3 mk, 0.568 mk) and UO2 (0.24 mk, 0.448 mk) fuels, respectively. Finally, the results showed that the UO2 was the best candidate for fuel conversion to LEU in the MNSR since it gave the lowest (135)Xe reactivity during the reactor operation and after shutdown. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Novel Control Strategy for Multiple Run-of-the-River Hydro Power Plants to Provide Grid Ancillary Services

    Energy Technology Data Exchange (ETDEWEB)

    Mohanpurkar, Manish; Luo, Yusheng; Hovsapian, Rob; Muljadi, Eduard; Gevorgian, Vahan; Koritarov, Vladimir

    2017-05-01

    Electricity generated by Hydropower Plants (HPPs) contributes a considerable portion of bulk electricity generation and delivers it with a low carbon footprint. In fact, HPP electricity generation provides the largest share from renewable energy resources, which includes solar and wind energy. The increasing penetration of wind and solar penetration leads to a lowered inertia in the grid and hence poses stability challenges. In recent years, breakthrough in energy storage technologies have demonstrated the economic and technical feasibility of extensive deployments in power grids. Multiple ROR HPPs if integrated with scalable, multi time-step energy storage so that the total output can be controlled. Although, the size of a single energy storage is far smaller than that of a typical reservoir, cohesively managing multiple sets of energy storage distributed in different locations is proposed. The ratings of storages and multiple ROR HPPs approximately equals the rating of a large, conventional HPP. The challenges associated with the system architecture and operation are described. Energy storage technologies such as supercapacitors, flywheels, batteries etc. can function as a dispatchable synthetic reservoir with a scalable size of energy storage will be integrated. Supercapacitors, flywheels, and battery are chosen to provide fast, medium, and slow responses to support grid requirements. Various dynamic and transient power grid conditions are simulated and performances of integrated ROR HPPs with energy storage is provided. The end goal of this research is to investigate the inertial equivalence of a large, conventional HPP with a unique set of multiple ROR HPPs and optimally rated energy storage systems.

  6. Cost on Reliability and Production Loss for Power Converters in the Doubly Fed Induction Generator to Support Modern Grid Codes

    DEFF Research Database (Denmark)

    Zhou, Dao; Blaabjerg, Frede; Lau, Mogens

    2016-01-01

    As wind farms are normally located in remote areas, many grid codes have been issued especially related to the reactive power support. Although the Doubly-Fed Induction Generator (DFIG) based power converter is able to control the active power and reactive power independently, the effects...... of providing reactive power on the lifetime of the power converter and the cost-of-energy of the whole system are seldom evaluated, even though it is an important topic. In this paper, the loss models of the DFIG system are established at various conditions of the reactive power injection. If the mission...... profile is taken into account, the lifespan of the power semiconductors as well as the cost of the reactive power can be calculated. It is concluded that an over-excited reactive power injection significantly reduces the power converter lifetime, only 1/4 of the case that there is no reactive power...

  7. Compensación de potencia reactiva mediante bancos asimétricos de capacitores; Reactive Power Compensation by Unbalanced Capacitor Banks

    Directory of Open Access Journals (Sweden)

    Ignacio Pérez Abril

    2011-02-01

    Full Text Available A pesar de que los sistemas de distribución primaria y secundaria son desbalanceados por naturaleza, lacompensación de potencia reactiva en estos sistemas, se realiza comúnmente mediante bancos decondensadores trifásicos balanceados. En este trabajo se presenta la formulación general para el problemade compensación de potencia reactiva en sistemas desbalanceados mediante bancos de condensadoresdesbalanceados. Se presentan cuatro ejemplos de compensación en el secundario de bancos desbalanceadosde transformadores monofásicos. Todos los ejemplos muestran que la compensación por bancosdesbalanceados de capacitores incrementa los beneficios con respecto al uso de bancos balanceados  In spite of the fact that primary and secondary distribution systems are unbalanced by nature, thereactive power compensation on these systems is commonly developed by the use of balanced capacitorbanks. In this paper, the general formulation for the reactive power compensation problem onunbalanced systems with unbalanced capacitor banks is developed. Four examples of reactive powercompensation on the secondary of unbalanced three-phase transformers banks are presented. All theexamples show that the compensation by unbalanced capacitor banks increases the active power lossessaving as well as reduce the transformer’s load and contributes to balance the line currents when the loadis unbalanced.

  8. Active and Reactive Power Control Strategy for Grid-Connected Six-Phase Generator by Using Multi-Modular Matrix Converters

    Directory of Open Access Journals (Sweden)

    David Caballero

    2016-12-01

    Full Text Available This paper proposes an active and reactive power control strategy based on predictive control approaches applied to gridconnected renewable energy systems. To accomplish this a multi-modular matrix converter topologies are used in combination with a simple but efficient grid synchronization strategy. The theoretical performance analysis is performed considering a six-phase wind energy generator system interconnected with the grid. Results based on a MATLAB/Simulink simulation environment are discussed and the most relevant characteristics of the proposed control technique are highlighted considering the total harmonic distortion and the mean squared error as a parameters of performance.

  9. GENERAL QUESTIONS AS TO PROVIDING ELECTROMAGNETIC COMPATIBILITY OF POWER CABLE LINES, THEIR AMPERAGE CAPACITY AND TYPES OF SHIELD CONSTRUCTION

    Directory of Open Access Journals (Sweden)

    I.A. Kostiukov

    2013-09-01

    Full Text Available Works studying ways of reducing magnetic fields of cross-linked polyethylene power cable lines are reviewed. Different aspects of single-phase power cable shield construction influence on thermal conditions of a three-phase power cable line are analyzed. Questions concerning electromagnetic compatibility of power cables are considered.

  10. 77 FR 24941 - Vantage Wind Energy LLC; Order Accepting Updated Market Power Analysis and Providing Direction on...

    Science.gov (United States)

    2012-04-26

    ... Energy Regulatory Commission Vantage Wind Energy LLC; Order Accepting Updated Market Power Analysis and... vertical market power.\\10\\ As discussed ] below, we find that Vantage Wind satisfies the Commission's... its power to its power purchasers. Vantage Wind further states that none of Polsky Energy, Invenergy...

  11. An Active Power Filter Based on a Three-Level Inverter and 3D-SVPWM for Selective Harmonic and Reactive Compensation

    Directory of Open Access Journals (Sweden)

    José Luis Monroy-Morales

    2017-03-01

    Full Text Available Active Power Filters (APFs have been used for reducing waveform distortion and improving power quality. However, this function can be improved by means of a selective harmonic compensation. Since an APF has rating restrictions, it is convenient to have the option of selecting an individual or a set of particular harmonics in order to compensate and apply the total APF capabilities to eliminate these harmonics, in particular those with a greater impact on the Total Harmonic Distortion (THD. This paper presents the development of a new APF prototype based on a three-phase three-level Neutral Point Clamped (NPC inverter with selective harmonic compensation capabilities and reactive power compensation. The selective harmonic compensation approach uses several Synchronous Rotating Frames (SRF, to detect and control individual or a set of harmonics using d and q variables. The APF includes a Three-Dimensional Space Vector Modulator (3D-SVPWM in order to generate the compensation currents. Because of its multilevel topology, the proposed active power filter can be used in diverse power quality applications at sub-transmission and distribution voltage levels. Simulation and experimental results are shown to validate the proposed solution and assess the prototype performance in different scenarios.

  12. Power

    OpenAIRE

    Bowles, Samuel; Gintis, Herbert

    2007-01-01

    We consider the exercise of power in competitive markets for goods, labour and credit. We offer a definition of power and show that if contracts are incomplete it may be exercised either in Pareto-improving ways or to the disadvantage of those without power. Contrasting conceptions of power including bargaining power, market power, and consumer sovereignty are considered. Because the exercise of power may alter prices and other aspects of exchanges, abstracting from power may miss essential a...

  13. Recovery Act: Demonstration of a SOFC Generator Fueled by Propane to Provide Electrical Power to Real World Applications

    Energy Technology Data Exchange (ETDEWEB)

    Bessette, Norman [Acumentrics Corporation, Westwood, MA (United States)

    2016-08-01

    The objective of this project provided with funds through the American Recovery and Reinvestment Act of 2009 (ARRA) was to demonstrate a Solid Oxide Fuel Cell (SOFC) generator capable of operation on propane fuel to improve efficiency and reduce emissions over commercially available portable generators. The key objectives can be summarized as: Development of two portable electrical generators in the 1-3kW range utilizing Solid Oxide Fuel Cells and propane fuel; The development and demonstration of a proof-of-concept electro-mechanical propane fuel interface that provides a user friendly capability for managing propane fuel; The deployment and use of the fuel cell portable generators to power media production equipment over the course of several months at multiple NASCAR automobile racing events; The deployment and use of the fuel cell portable generators at scheduled events by first responders (police, fire) of the City of Folsom California; and Capturing data with regard to the systems’ ability to meet Department of Energy (DOE) Technical Targets and evaluating the ease of use and potential barriers to further adoption of the systems.

  14. Fourier power, subjective distance and object categories all provide plausible models of BOLD responses in scene-selective visual areas

    Directory of Open Access Journals (Sweden)

    Mark Daniel Lescroart

    2015-11-01

    Full Text Available Perception of natural visual scenes activates several functional areas in the human brain, including the Parahippocampal Place Area (PPA, Retrosplenial Complex (RSC, and the Occipital Place Area (OPA. It is currently unclear what specific scene-related features are represented in these areas. Previous studies have suggested that PPA, RSC, and/or OPA might represent at least three qualitatively different classes of features: (1 2D features related to Fourier power; (2 3D spatial features such as the distance to objects in a scene; or (3 abstract features such as the categories of objects in a scene. To determine which of these hypotheses best describes the visual representation in scene-selective areas, we applied voxel-wise modeling (VM to BOLD fMRI responses elicited by a set of 1,386 images of natural scenes. VM provides an efficient method for testing competing hypotheses by comparing predictions of brain activity based on encoding models that instantiate each hypothesis. Here we evaluated three different encoding models that instantiate each of the three hypotheses listed above. We used linear regression to fit each encoding model to the fMRI data recorded from each voxel, and we evaluated each fit model by estimating the amount of variance it predicted in a withheld portion of the data set. We found that voxel-wise models based on Fourier power or the subjective distance to objects in each scene predicted much of the variance predicted by a model based on object categories. Furthermore, the response variance explained by these three models is largely shared, and the individual models explain little unique variance in responses. Based on an evaluation of previous studies and the data we present here, we conclude that there is currently no good basis to favor any one of the three alternative hypotheses about visual representation in scene-selective areas. We offer suggestions for further studies that may help resolve this issue.

  15. Fourier power, subjective distance, and object categories all provide plausible models of BOLD responses in scene-selective visual areas

    Science.gov (United States)

    Lescroart, Mark D.; Stansbury, Dustin E.; Gallant, Jack L.

    2015-01-01

    Perception of natural visual scenes activates several functional areas in the human brain, including the Parahippocampal Place Area (PPA), Retrosplenial Complex (RSC), and the Occipital Place Area (OPA). It is currently unclear what specific scene-related features are represented in these areas. Previous studies have suggested that PPA, RSC, and/or OPA might represent at least three qualitatively different classes of features: (1) 2D features related to Fourier power; (2) 3D spatial features such as the distance to objects in a scene; or (3) abstract features such as the categories of objects in a scene. To determine which of these hypotheses best describes the visual representation in scene-selective areas, we applied voxel-wise modeling (VM) to BOLD fMRI responses elicited by a set of 1386 images of natural scenes. VM provides an efficient method for testing competing hypotheses by comparing predictions of brain activity based on encoding models that instantiate each hypothesis. Here we evaluated three different encoding models that instantiate each of the three hypotheses listed above. We used linear regression to fit each encoding model to the fMRI data recorded from each voxel, and we evaluated each fit model by estimating the amount of variance it predicted in a withheld portion of the data set. We found that voxel-wise models based on Fourier power or the subjective distance to objects in each scene predicted much of the variance predicted by a model based on object categories. Furthermore, the response variance explained by these three models is largely shared, and the individual models explain little unique variance in responses. Based on an evaluation of previous studies and the data we present here, we conclude that there is currently no good basis to favor any one of the three alternative hypotheses about visual representation in scene-selective areas. We offer suggestions for further studies that may help resolve this issue. PMID:26594164

  16. Analysis of the reactive power consumption and the harmonics in the network by the non-linear electrical loads

    Energy Technology Data Exchange (ETDEWEB)

    Cogo, Joao Roberto [Escola Federal de Engenharia de Itajuba, MG (Brazil)

    1994-12-31

    The non linear electrical loads can give rise to a number of disturbances in electrical power networks. Among them, the high consumption of relative power is to be noted and so is the several harmonic components which may be injected in the industry system and very often in the utility system. So, by using appropriate technical considerations, as well as measurements in typical special electrical loads, such negative effects are analyzed and ways of minimizing them are suggested. (author) 3 refs., 11 figs., 6 tabs.

  17. Reactive power compensation capability of a STATCOM based on two types of Modular Multilevel Cascade Converters for offshore wind application

    DEFF Research Database (Denmark)

    Tanaka, Takaaki; Wang, Huai; Ma, Ke

    2017-01-01

    Static Synchronous Compensators (STATCOMs) have been applied for offshore wind power plants to satisfy the grid codes under both normal operation and grid fault conditions. This paper investigates the performances of two types of Modular Multilevel Cascade Converters (MMCC) for STATCOM applicatio...

  18. Preliminary analysis of Block Island Power Company's use of clean distributed resources to provide power to its customers

    Energy Technology Data Exchange (ETDEWEB)

    Hoff, T.E.

    2000-01-25

    This report is an analysis of the potential for Block Island Power Company (BIPCO) to use renewable energy and clean distributed resources to supply power to its customers. The preliminary conclusion of this work is that a system composed of clean distributed resources has the potential to be a technically and economically feasible alternative for BIPCO.

  19. Non-Model-Based Control of a Wheeled Vehicle Pulling Two Trailers to Provide Early Powered Mobility and Driving Experiences.

    Science.gov (United States)

    Sanders Td Vr, David A

    2018-01-01

    Non-model-based control of a wheeled vehicle pulling two trailers is proposed. It is a fun train for disabled children consisting of a locomotive and two carriages. The fun train has afforded opportunities for both disabled and able bodied young people to share an activity and has provided early driving experiences for disabled children; it has introduced them to assistive and powered mobility. The train is a nonlinear system and subject to nonholonomic kinematic constraints, so that position and state depend on the path taken to get there. The train is described, and then, a robust control algorithm using proportional-derivative filtered errors is proposed to control the locomotive. The controller was not dependent on an accurate model of the train, because the mass of the vehicle and two carriages changed depending on the number, size, and shape of children and wheelchair seats on the train. The controller was robust and stable in uncertainty. Results are presented to show the effectiveness of the approach, and the suggested control algorithm is shown to be acceptable without knowing the exact plant dynamics.

  20. Dynamics of processes during the deposition of ZrO2 films by controlled reactive high-power impulse magnetron sputtering: A modelling study

    Science.gov (United States)

    Kozák, Tomáš; Vlček, Jaroslav

    2017-07-01

    A time-dependent parametric model was applied to controlled reactive high-power impulse magnetron sputtering (HiPIMS) depositions of stoichiometric ZrO2 films, carried out in our laboratories, (i) to clarify the complicated dynamics of the processes on the target and substrate surfaces during voltage pulses, and (ii) to corroborate the importance of the O2 inlet configuration (position and direction) which strongly affects the O2 dissociation in the discharge and the chemisorption flux of oxygen atoms and molecules onto the substrate. The repetition frequency was 500 Hz at the deposition-averaged target power densities of 25 Wcm-2, being close to a target power density applicable in industrial HiPIMS systems, and 50 Wcm-2 with a pulse-averaged target power density up to 2 kWcm-2. The pulse duration was 50 μs. For the experimental conditions with the to-substrate O2 inlets, the deposition-averaged target power density of 50 Wcm-2, and the oxygen partial pressure of 0.05 Pa (being close to the mean value during controlled depositions), our model predicts a low compound fraction, changing between 8% and 12%, in the target surface layer at an almost constant high compound fraction, changing between 92% and 93%, in the substrate surface layer during the pulse period (2000 μs). The calculated deposition rate of 89 nm/min for these films is in good agreement with the measured value of 80 nm/min achieved for optically transparent stoichiometric ZrO2 films prepared under these conditions.

  1. Final Report Providing the Design for Low-Cost Wireless Current Transducer and Electric Power Sensor Prototype

    Energy Technology Data Exchange (ETDEWEB)

    Kintner-Meyer, Michael CW; Burghard, Brion J.; Reid, Larry D.

    2005-01-31

    This report describes the design and development of a wireless current transducer and electric power sensor prototype. The report includes annotated schematics of the power sensor circuitry and the printed circuit board. The application program used to illustrate the functionality of the wireless sensors is described in this document as well.

  2. Functionalization of reactive polymer multilayers with RGD and an anti-fouling motif: RGD density provides control over human corneal epithelial cell-substrate interactions

    Science.gov (United States)

    Tocce, Elizabeth J.; Broderick, Adam H.; Murphy, Kaitlin C.; Liliensiek, Sara J.; Murphy, Christopher J.; Lynn, David M.; Nealey, Paul F.

    2011-01-01

    Our study demonstrates that substrates fabricated using a ‘reactive’ layer-by-layer approach promote well-defined cell-substrate interactions of human corneal epithelial cells. Specifically, crosslinked and amine-reactive polymer multilayers were produced by alternating ‘reactive’ deposition of an azlactone-functionalized polymer [poly(2-vinyl-4,4-dimethylazlactone)] and a primary amine-containing polymer [branched poly(ethylene imine)]. Advantages of our system include a 5 to 30-fold decrease in deposition time compared to traditional polyelectrolyte films and direct modification of the films with peptides. Our films react with mixtures of an adhesion-promoting peptide containing Arg-Gly-Asp (RGD) and the small molecule d-glucamine, a chemical motif which is non-fouling. Resulting surfaces prevent protein adsorption and promote cell attachment through specific peptide interactions. The specificity of cell attachment via immobilized RGD sequences was verified using both a scrambled RDG peptide control as well as soluble-RGD competitive assays. Films were functionalized with monotonically increasing surface densities of RGD which resulted in both increased cell attachment and the promotion of a tri-phasic proliferative response of a human corneal epithelial cell line (hTCEpi). The ability to treat PEI/PVDMA films with peptides for controlled cell-substrate interactions enables the use of these films in a wide range of biological applications. PMID:21972074

  3. Study on Reactive Automatic Compensation System Design

    Science.gov (United States)

    Zhe, Sun; Qingyang, Liang; Peiqing, Luo; Chenfei, Zhang

    At present, low-voltage side of transformer is public in urban distribution network, as inductive load of household appliances is increasing, the power factor decreased, this lead to a large loss of public transformer low voltage side, the supply voltage indicators can not meet user's requirements. Therefore, the design of reactive power compensation system has become another popular research. This paper introduces the principle of reactive power compensation, analyzes key technologies of reactive power compensation, design an overall program of reactive power automatic compensation system to conquer various deficiencies of reactive power automatic compensation equipment.

  4. Extensively re-organized systemic lymph nodes provide a feasible environment for self-reactivity in lupus-prone NZB × NZW F1 mice.

    Science.gov (United States)

    Kurosawa, Yoichi; Ozawa, Madoka; Kanda, Yasuhiro; Takeuchi, Arata; Kawamura, Toshihiko; Narita, Ichiei; Katakai, Tomoya

    2017-12-31

    Lymphadenopathy is a frequently observed symptom in systemic lupus erythematosus, although the immunological role of lymph nodes (LNs) in systemic autoimmunity remains largely unknown. Here, we performed comprehensive and systematic analyses of LNs in lupus-prone NZB × NZW F1 (BWF1) mice, demonstrating extensive tissue re-organization of the systemic LNs with follicular expansion, hyper germinal center (GC) formation, atrophy of the paracortical T-cell area and expansion of the medulla in aged BWF1 mice bearing glomerulonephritis. The proportion of B cells was significantly increased in these reactive LNs but not in the spleen, and lymphocyte subsets involved in antibody production, i.e. GC B cells, follicular helper T cells and plasma cells, were elevated. Draining LNs of the affected organs, such as the renal and cervical nodes, showed enhanced tissue re-organization and accumulation of effector lymphocytes, suggesting the presence of a positive feedback loop of regional responses. LN cells isolated from disease-bearing animals produced anti-DNA antibody, indicating activation of autoreactive lymphocytes in situ. The substantial development of disease and LN alterations in mice that received a splenectomy at a young age points to the importance of other secondary lymphoid organs, most likely LNs, for the progression of autoimmune responses independent of the spleen. Taken together, our findings highlight the value of taking LN alterations and activities into consideration for understanding the pathogenesis of systemic autoimmunity. © The Japanese Society for Immunology. 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  5. Timing of the compensation of winter respiratory carbon losses provides explanatory power for net ecosystem productivity of forests

    DEFF Research Database (Denmark)

    Haeni, M.; Zweifel, R.; Eugster, W.

    2017-01-01

    , and Australia, using different NEPc integration methods. We found cDOY to be a particularly powerful predictor for NEPc of temperate evergreen needle-leaf forests (R2 = 0.58) and deciduous broadleaf forests (R2 = 0.68). In general, the latest cDOY correlated with the lowest NEPc. The explanatory power of c......Accurate predictions of net ecosystem productivity (NEPc) of forest ecosystems are essential for climate change decisions and requirements in the context of national forest growth and greenhouse gas inventories. However, drivers and underlying mechanisms determining NEPc (e.g. climate, nutrients......) are not entirely understood yet, particularly when considering the influence of past periods. Here we explored the explanatory power of the compensation day (cDOY) —defined as the day of year when winter net carbon losses are compensated by spring assimilation— for NEPc in 26 forests in Europe, North America...

  6. Operating characteristics of a single-stage Stirling cryocooler capable of providing 700 W cooling power at 77 K

    Science.gov (United States)

    Xu, Ya; Sun, Daming; Qiao, Xin; Yu, Yan S. W.; Zhang, Ning; Zhang, Jie; Cai, Yachao

    2017-04-01

    High cooling capacity Stirling cryocooler generally has hundreds to thousands watts of cooling power at liquid nitrogen temperature. It is promising in boil-off gas (BOG) recondensation and high temperature superconducting (HTS) applications. A high cooling capacity Stirling cryocooler driven by a crank-rod mechanism was developed and studied systematically. The pressure and frequency characteristics of the cryocooler, the heat rejection from the ambient heat exchanger, and the cooling performance are studied under different charging pressure. Energy conversion and distribution in the cryocooler are analyzed theoretically. With an electric input power of 10.9 kW and a rotating speed of 1450 r/min of the motor, a cooling power of 700 W at 77 K and a relative Carnot efficiency of 18.2% of the cryocooler have been achieved in the present study, and the corresponding pressure ratio in the compression space reaches 2.46.

  7. Analytical Assessment of Voltage Support via Reactive Power from new Electric Vehicles Supply Equipment in Radial Distribution Grids with Voltage-Dependent Loads

    DEFF Research Database (Denmark)

    Zecchino, Antonio; Marinelli, Mattia

    2018-01-01

    Grid operators have to cope with secure electric vehicles integration in the power system, which may lead to violations of the allowed voltage band. This work intends to provide an analytical assessment and guidelines for distribution system operators when evaluating new electric vehicle supply...

  8. Fuel reactivity and release of pollutants and alkali vapours in pressurized combustion for combined cycle power generation

    Energy Technology Data Exchange (ETDEWEB)

    Aho, M.; Haemaelaeinen, J.; Paakkinen, K.; Rantanen, J. [VTT Energy, Jyvaeskylae (Finland); Hernberg, R.; Haeyrinen, V.; Joutsenoja, T. [Tampere Univ. of Technology (Finland). Lab. of Plasma Technology

    1996-12-01

    This project forms a part of the overall Pressurized Power Coal Combustion Project Area (PPFC) which aims at an assessment of the viability and technical merits of pressurized pulverized coal combustion, in an atmosphere of recycled flue gas and oxygen in a coordinated and harmonized programme. The objective of the research at Technical Research Centre of Finland (VTT) and Tampere University of Technology (TUT) is aimed at determining the consequences of solid fuel burning in a mixture of oxygen and recycled flue gases. Combustion conditions of a pressurized entrained flow of pulverized coal and char particles in PEFR are determined with high precision. The effects of experimental parameters on the formation of nitrogen oxides (N{sub 2}O, NO and NO{sub 2}) and gaseous alkali compounds (indicated as NaX(g) and KX(g)) are studied. An effective on-line analysis method for vaporised Na and K compounds was developed. The dependency between particle temperatures and the vaporisation of Na and K was measured with three coals. The results show that alkali removal before gas turbines is always necessary with these coals if combusted in combined cycles. Pressure decreases the formation of NO and has usually no clear effect on the formation of N{sub 2}O. The order of NO/N{sub 2}O ratios correspond to fuel-O/fuel-N ratios. Increase of PO{sub 2} (oxygen concentration) of combustion gas increases the formation of NO{sub 2}. Remarkable concentrations of NO{sub 2} were often measured at high PO{sub 2} at 800-850 deg C. Therefore, NO{sub 2} should be measured from pressurized fluidized bed reactors. Some trends of the formation of NO{sub 2} with coal differ clearly from those with its parent char: N{sub 2}O formation is not strongly temperature dependent with char, and the concentrations of N{sub 2}O formed from char are much lower than those of coal. PO{sub 2} does not effect on the formation of NO from char in the studied range

  9. Use of blade pitch control to provide power train damping for the Mod-2, 2.5-mW wind turbine

    Science.gov (United States)

    Blissell, W. A., Jr.

    1995-01-01

    The Control System for the Mod-2 wind turbine system is required to provide not only for startup, RPM regulation, maximizing or regulating power, and stopping the rotor, but also for load limiting, especially in the power train. Early operations with above-rated winds revealed an instability which was caused primarily by coupling between the quill shaft and the rotor air loads. This instability caused the first of several major Mod-2 Control System changes which are reviewed in the paper.

  10. Power

    DEFF Research Database (Denmark)

    Elmholdt, Claus Westergård; Fogsgaard, Morten

    2016-01-01

    In this chapter, we will explore the dynamics of power in processes of creativity, and show its paradoxical nature as both a bridge and a barrier to creativity in organisations. Recent social psychological experimental research (Slighte, de Dreu & Nijstad, 2011) on the relation between power...... and creativity suggests that when managers give people the opportunity to gain power and explicate that there is reason to be more creative, people will show a boost in creative behaviour. Moreover, this process works best in unstable power hierarchies, which implies that power is treated as a negotiable...... and floating source for empowering people in the organisation. We will explore and discuss here the potentials, challenges and pitfalls of power in relation to creativity in the life of organisations today. The aim is to demonstrate that power struggles may be utilised as constructive sources of creativity...

  11. Reactive Systems

    DEFF Research Database (Denmark)

    Aceto, Luca; Ingolfsdottir, Anna; Larsen, Kim Guldstrand

    A reactive system comprises networks of computing components, achieving their goals through interaction among themselves and their environment. Thus even relatively small systems may exhibit unexpectedly complex behaviours. As moreover reactive systems are often used in safety critical systems, t...

  12. Reactive capability limits of wind farms

    Energy Technology Data Exchange (ETDEWEB)

    Villacorta, A.R. [European Univ., Madrid (Spain). Dept. of Electrical and Electronic Engineering; Gomez, S.A.; Rodriguez Amenedo, J.L. [Carlos III Univ., Madrid (Spain). Dept. of Electrical Engineering

    2005-07-01

    Wind Energy Conversion Systems (WECS) technology can be classified into two main types: fixed speed and variable speed. Fixed speed WECS use an induction generator connected directly to the grid while variable speed WECS use a power converter to connect the generator to the grid. Fixed speed WECS require shunt capacitors for reactive power compensation, while variable speed WECS have reactive power capability. Under the Spanish grid code, wind farms have to operate in a range of power factor values. This paper determines the reactive power capability of wind farms equipped with both fixed and variable speed WECS. The reactive power capability can be represented as a reactive capability curve. In this paper, the reactive capability curve is used to calculate the additional reactive power compensation needed to meet the requirements of the Spanish grid code. (Author)

  13. PROGRAM TECHNICAL SYSTEM OF PROVIDING OF SECURITY OF THE INFORMATIVE RESOURCES FOR ON THE CIRCLES OF ELECTRIC POWER SUPPLY

    Directory of Open Access Journals (Sweden)

    V.M. Bakiko

    2010-08-01

    Full Text Available The model of anti-interference protective filter with due account taken of stray parameters of elements is developed. The algorithm of functioning of anti-interference protective filter with integrated system management, which forms the new class of intellectual devices of security of informative resources on the circles of power supply, is offered. The analysis of possibilities of dynamic magnetic biasing of direct current of pericardium of throttle with the use of latitudinal impulsive modulation is experimentally conducted. The efficiency of hardware-software complex of security of informative resources is explored.

  14. Compensación de potencia reactiva en sistemas desbalanceados utilizando algoritmos genéticos Reactive power compensation in unbalanced systems using genetic algorithms

    Directory of Open Access Journals (Sweden)

    Davel Borges Vasconcellos

    2012-12-01

    Full Text Available La eficiencia energética de un sistema eléctrico depende en gran medida del factor de potencia con que opera y de una eficaz compensación de potencia reactiva si esta es necesaria. Una de las vías más utilizadas para efectuar la compensación del reactivo es el empleo de bancos de capacitores. La óptima aplicación de estos presupone tres aspectos: la selección de la capacidad más adecuada de los bancos, el tipo de compensador a utilizar, fijo o variable, así como la ubicación en el sistema de suministro eléctrico. En determinadas publicaciones, estos aspectos se tratan de forma independiente. Sin embargo, desde el punto de vista técnico ellos están mutuamente vinculados y todos poseen una implicación económica, lo que obliga a la necesidad de considerarlos en conjunto para un problema de optimización dado. Existen referencias de otros trabajos que desarrollan métodos que consideran estos aspectos de manera conjunta, pero presentan limitantes para ser aplicados en los sistemas de suministro eléctrico del sector terciario y donde predominan condiciones de desbalance. En este trabajo se presenta un método con el empleo de los algoritmos genéticos que posibilita una formulación más exacta del problema arrojando soluciones de mayor calidad. El programa desarrollado se soporta sobre software MATLAB, versión 7.8 (R2009a, utilizando las estructuras de programación de Genetic Algorithm and Direct Search Toolbox. La efectividad de su aplicación se muestra en casos de estudio correspondientes a sistemas de suministro eléctrico de dos hoteles pertenecientes al sector terciario en la provincia de Camagüey, Cuba.The energy efficiency of an electric system depends in great extent of the reactive power compensation that is carried out. One of the ways most used for reactive is power of capacitor banks. A good selection of these, presupposes three aspects: the selection of the banks capacity, the compensator type to be used and the

  15. Power

    OpenAIRE

    Hafford-Letchfield, Trish

    2015-01-01

    This chapter looks at the concept of power in social work by focusing on what this means as a ‘professional’ and theorizes competing discourses of empowerment in social work and its key concepts, drawing in particular on the explanatory powers of critical theorist Michel Foucault (1991). The chapter problematizes the concept of power by explicitly drawing on both users’ and carers’ accounts from the literature to demonstrate different external and internal influences on the root causes of dis...

  16. RelA-Mediated BECN1 Expression Is Required for Reactive Oxygen Species-Induced Autophagy in Oral Cancer Cells Exposed to Low-Power Laser Irradiation.

    Directory of Open Access Journals (Sweden)

    Chih-Wen Shu

    Full Text Available Low-power laser irradiation (LPLI is a non-invasive and safe method for cancer treatment that alters a variety of physiological processes in the cells. Autophagy can play either a cytoprotective role or a detrimental role in cancer cells exposed to stress. The detailed mechanisms of autophagy and its role on cytotoxicity in oral cancer cells exposed to LPLI remain unclear. In this study, we showed that LPLI at 810 nm with energy density 60 J/cm2 increased the number of microtubule associated protein 1 light chain 3 (MAP1LC3 puncta and increased autophagic flux in oral cancer cells. Moreover, reactive oxygen species (ROS production was induced, which increased RelA transcriptional activity and beclin 1 (BECN1 expression in oral cancer cells irradiated with LPLI. Furthermore, ROS scavenger or knockdown of RelA diminished LPLI-induced BECN1 expression and MAP1LC3-II conversion. In addition, pharmacological and genetic ablation of autophagy significantly enhanced the effects of LPLI-induced apoptosis in oral cancer cells. These results suggest that autophagy may be a resistant mechanism for LPLI-induced apoptosis in oral cancer cells.

  17. Effect of multiple slip on a chemically reactive MHD non-Newtonian nanofluid power law fluid flow over a stretching sheet with microorganism

    Science.gov (United States)

    Basir, Mohammad Faisal Mohd; Ismail, Fazreen Amira; Amirsom, Nur Ardiana; Latiff, Nur Amalina Abdul; Ismail, Ahmad Izani Md.

    2017-04-01

    The effect of multiple slip on a chemically reactive magnetohydrodynamic (MHD) non-Newtonian power law fluid flow over a stretching sheet with microorganism was numerically investigated. The governing partial differential equations were transformed into nonlinear ordinary differential equations using the similarity transformations developed by Lie group analysis. The reduced governing nonlinear ordinary differential equations were then numerically solved using the Runge-Kutta-Fehlberg fourth-fifth order method. Good agreement was found between the present numerical solutions with the existing published results to support the validity and the accuracy of the numerical computations. The influences of the velocity, thermal, mass and microorganism slips, the magnetic field parameter and the chemical reaction parameter on the dimensionless velocity, temperature, nanoparticle volume fraction, microorganism concentration, the distribution of the density of motile microorganisms have been illustrated graphically. The effects of the governing parameters on the physical quantities, namely, the local heat transfer rate, the local mass transfer rate and the local microorganism transfer rate were analyzed and discussed.

  18. Sodium Nitrate Induces Reactive Oxygen Species That Lower the Antioxidant Power, Damage the Membrane, and Alter Pathways of Glucose Metabolism in Human Erythrocytes.

    Science.gov (United States)

    Ansari, Fariheen Aisha; Mahmood, Riaz

    2015-12-09

    Nitrate salts are widely used as food additives and nitrogenous fertilizers and are present as contaminants in drinking water supplies. The effect of different concentrations (1-15 mM) of sodium nitrate (NaNO3) on human erythrocytes was studied under in vitro conditions. Treatment of erythrocytes with NaNO3 resulted in increases in methemoglobin levels, lipid peroxidation, and protein oxidation and a decrease in glutathione content. There were changes in the activities of all major antioxidant defense enzymes, and the pathways of glucose metabolism were also affected. Increased generation of reactive oxygen species (ROS) took place while the antioxidant power was impaired. The osmotic fragility of cells was increased, and membrane-bound enzymes were greatly inhibited. All changes were statistically significant at a probability level of P < 0.05 at all concentrations of NaNO3 except the lowest (1 mM). Thus, NaNO3 generates ROS that cause significant damage to human erythrocytes and interfere in normal cellular pathways.

  19. Reactivity Network: Secondary Sources for Inorganic Reactivity Information.

    Science.gov (United States)

    Mellon, E. K.

    1989-01-01

    Provides an eclectic annotated bibliography of secondary sources for inorganic reactivity information of interest to reactivity network review authors and to anyone seeking information about simple inorganic reactions in order to develop experiments and demonstrations. Gives 119 sources. (MVL)

  20. Timing of the compensation of winter respiratory carbon losses provides explanatory power for net ecosystem productivity of forests

    DEFF Research Database (Denmark)

    Haeni, M.; Zweifel, R.; Eugster, W.

    2017-01-01

    Accurate predictions of net ecosystem productivity (NEPc) of forest ecosystems are essential for climate change decisions and requirements in the context of national forest growth and greenhouse gas inventories. However, drivers and underlying mechanisms determining NEPc (e.g. climate, nutrients......DOY depended on the integration method for NEPc, forest type, and whether the site had a distinct winter net respiratory carbon loss or not. The integration methods starting in autumn led to better predictions of NEPc from cDOY then the classical calendar method starting at January 1. Limited explanatory power...... of cDOY for NEPc was found for warmer sites with no distinct winter respiratory loss period. Our findings highlight the importance of the influence of winter processes and the delayed responses of previous seasons’ climatic conditions on current year's NEPc. Such carry-over effects may contain...

  1. Modelación de los efectos de la compensación de potencia reactiva en sistemas de suministro eléctrico Modelation of effects on reactive power compensation in secondary power systems

    Directory of Open Access Journals (Sweden)

    Davel Borges Vasconcellos

    2012-08-01

    Full Text Available Se presentan los inconvenientes de la potencia reactiva y a partir de allí se realiza la modelación matemática de los efectos económicos de ésta, aplicable a sistemas de suministro eléctrico. Los efectos tomados en cuenta son: los costos de inversión de los bancos de capacitores, los gastos de amortización de los bancos, los gastos de pérdidas de energía activa de los bancos, los beneficios por la mejora del factor de potencia, incluida la reducción de pérdidas de energía activa en el sistema, así como los beneficios por la liberación de la capacidad de carga, para el caso de empresas donde este aspecto pueda representar un atractivo económico. Para el análisis de los estados de carga antes y después de la compensación se utilizan algoritmos de flujos de potencia trifásicos, con el empleo de modelos de gráficos de carga ajustados, como aspecto novedoso. Estos efectos, de acuerdo con el sistema de tarifas eléctricas de Cuba, son integrados en una función de análisis económico, en este caso el Valor Actual Neto (VAN, la cual sirve de base para el planteamiento del problema de optimización, que puede derivar en la correcta selección de los dispositivos compensadores.The inconveniences of the reactive power are presented and from this are carried out the mathematical models of its economic effects applicable to secondary power systems. The effects taken into account are: the costs of the capacitors banks, the expenses of paying-off to the banks, the expenses of power losses to the banks, the benefits for the improvement of the power factor, included the reduction of power loss in the system, as well as the benefits for the liberation of the load capacity, to the case of companies where the latest aspect can represent an economic attractiveness. For the analysis after and before compensation, are consider load flow algorithm witch load model adjust. According to electrical tariff structures in Cuba, these effects are

  2. Reactive Power Management in Electric Power Systems

    African Journals Online (AJOL)

    current in energy conversion, and, as a result, the excess current represents a waste to the consumer as ... BRIEF REVIEW OF BASIC RELATIONS a) Voltage Drop and Losses. For a simplified analysis, the ... 1be solution of the transmission line wave equation is. V(x) = V, cos/J(a-x) + jZJ,sin/J(a-x) with a= the length and Z0 ...

  3. A heuristic model for planning problem solution of reactive in electric power systems; Um modelo heuristico para solucao do problema de planejamento de reativos em sistemas de energia eletrica

    Energy Technology Data Exchange (ETDEWEB)

    Mantovani, Jose Roberto Sanches

    1995-02-01

    This work introduces a model to solve the planning problem of reactive in electric power systems. The proposed method uses mixed integer linear programming and is solved using implicit enumeration (binary search). The special heuristics to reduce candidates' initial set and to obtain discreet solutions are adopted. They were going accomplished two algorithm implementations, one sequential and other parallel. The implementation parallel uses an asynchronous programming model and is adjusted for distributed memory computer. Defined a bars candidates set for the new reactive sources allocation, the developed program supplies the location and the reactive sources magnitude that must be allocated in the system, considering safety and operation restrictions. The implementation parallel performance is evaluated for three real systems of 309, 725 and 810 bars. The results for the test systems IEEE30 and IEEE118, and the three real systems used in the implementation parallel evaluation are also presented.

  4. Compositionally modulated multilayer diamond-like carbon coatings with AlTiSi multi-doping by reactive high power impulse magnetron sputtering

    Science.gov (United States)

    Dai, Wei; Gao, Xiang; Liu, Jingmao; Kwon, Se-Hun; Wang, Qimin

    2017-12-01

    Diamond-like carbon (DLC) coatings with AlTiSi multi-doping were prepared by a reactive high power impulse magnetron sputtering with using a gas mixture of Ar and C2H2 as precursor. The composition, microstructure, compressive stress, and mechanical property of the as-deposited DLC coatings were studied systemically by using SEM, XPS, TEM, Raman spectrum, stress-tester, and nanoindentation as a function of the Ar fraction. The results show that the doping concentrations of the Al, Ti and Si atoms increased as the Ar fraction increased. The doped Ti and Si preferred to bond with C while the doped Al mainly existed in oxidation state without bonding with C. As the doping concentrations increased, TiC carbide nanocrystals were formed in the DLC matrix. The microstructure of coatings changed from an amorphous feature dominant AlTiSi-DLC to a carbide nanocomposite AlTiSi-DLC with TiC nanoparticles embedding. In addition, the coatings exhibited the compositionally modulated multilayer consisting of alternate Al-rich layer and Al-poor layer due to the rotation of the substrate holder and the diffusion behavior of the doped Al which tended to separate from C and diffuse towards the DLC matrix surface owing to its weak interactions with C. The periodic Al-rich layer can effectively release the compressive stress of the coatings. On the other hand, the hard TiC nanoparticles were conducive to the hardness of the coatings. Consequently, the DLC coatings with relatively low residual stress and high hardness could be acquired successfully through AlTiSi multi-doping. It is believed that the AlCrSi multi-doping may be a good way for improving the comprehensive properties of the DLC coatings. In addition, we believe that the DLC coatings with Al-rich multilayered structure have a high oxidation resistance, which allows the DLC coatings application in high temperature environment.

  5. Novel Control Strategy for Multiple Run-of-the-River Hydro Power Plants to Provide Grid Ancillary Services

    Energy Technology Data Exchange (ETDEWEB)

    Mohanpurkar, Manish; Luo, Yusheng; Hovsapian, Rob; Muljadi, Eduard; Gevorgian, Vahan; Koritarov, Vladimir

    2017-07-12

    Hydropower plant (HPP) generation comprises a considerable portion of bulk electricity generation and is delivered with a low-carbon footprint. In fact, HPP electricity generation provides the largest share from renewable energy resources, which include wind and solar. Increasing penetration levels of wind and solar lead to a lower inertia on the electric grid, which poses stability challenges. In recent years, breakthroughs in energy storage technologies have demonstrated the economic and technical feasibility of extensive deployments of renewable energy resources on electric grids. If integrated with scalable, multi-time-step energy storage so that the total output can be controlled, multiple run-of-the-river (ROR) HPPs can be deployed. Although the size of a single energy storage system is much smaller than that of a typical reservoir, the ratings of storages and multiple ROR HPPs approximately equal the rating of a large, conventional HPP. This paper proposes cohesively managing multiple sets of energy storage systems distributed in different locations. This paper also describes the challenges associated with ROR HPP system architecture and operation.

  6. [Reactive arthritis].

    Science.gov (United States)

    Gerloni, V; Fantini, F

    1990-01-01

    The term reactive arthritis was introduced to describe an acute non-purulent arthritis complicating an infection elsewhere in the body. Reactive arthritis can also be classified into HLA-B27 associated and non-associated forms. Rheumatic fever is an example of the HLA-B27 non-associated forms with genetic factors other than HLA-B27 involved. HLA-B27 associated reactive arthritis includes enteric, urogenic and idiopathic arthritides. The bacteria known to trigger post-enteritic reactive arthritis are: Yersinia, Salmonella, Shigella, Campylobacter, Clostridium difficile and Brucella; those known to trigger post-urethritic reactive arthritis are Chlamydia trachomatis and Ureaplasma urealyticum, but often the germ remains unidentified. Mechanisms through which susceptibility to reactive arthritis is linked to HLA-B27 antigen are still incompletely understood, but a clue could be cross-reactivity between B27 and a surface antigen of pathogenic germs. The clinical profile of the disease is characterized by an asymmetrical oligoarthritis with involvement particularly of the peripheral joints of the lower limbs. The arthritis generally recovers without sequelae within a few weeks or months. Accompanying features can be the involvement of enthesis and tendon sheets in form of a talalgia or dactylitis. In some cases the arthritis can relapse and chronicize. In some cases, in addition, involvement of the axial skeleton can occur (spondylitis and/or sacroiliitis). Another feature of the disease is the frequent association with typical extra-articular manifestations such as uveitis and muco-cutaneous lesions.

  7. VAr reserve concept applied to a wind power plant

    DEFF Research Database (Denmark)

    Martinez, Jorge; Kjær, Philip C.; Rodriguez, Pedro

    2011-01-01

    Larger percentages of wind power penetration translate into more demanding requirements from the grid codes; for example voltage support at the point of connection has been introduced recently by several grid codes from around the world, making it important to analyze this control when applied...... to wind power plants. This paper proposes two different VAr reserve control strategies for a wind power plant. The amount of dynamic VAr available most of the operation time, makes the wind power plant (WPP) a good candidate to include a VAr reserve management system. Two different ways of implementing...... a VAr management system are proposed and analyzed. Such a reactive power reserve may be provided by the wind power plant since the amount of reactive power installed for most active power working points exceeds the demand required by the grid operator. Basically, this overrated reactive power capacity...

  8. Reactive Systems

    DEFF Research Database (Denmark)

    Aceto, Luca; Ingolfsdottir, Anna; Larsen, Kim Guldstrand

    A reactive system comprises networks of computing components, achieving their goals through interaction among themselves and their environment. Thus even relatively small systems may exhibit unexpectedly complex behaviours. As moreover reactive systems are often used in safety critical systems......, the need for mathematically based formal methodology is increasingly important. There are many books that look at particular methodologies for such systems. This book offers a more balanced introduction for graduate students and describes the various approaches, their strengths and weaknesses, and when...

  9. Reactive Systems

    DEFF Research Database (Denmark)

    Aceto, Luca; Ingolfsdottir, Anna; Larsen, Kim Guldstrand

    A reactive system comprises networks of computing components, achieving their goals through interaction among themselves and their environment. Thus even relatively small systems may exhibit unexpectedly complex behaviours. As moreover reactive systems are often used in safety critical systems, t...... into account. The book has arisen from various courses taught in Denmark and Iceland and is designed to give students a broad introduction to the area, with exercises throughout....

  10. Power quality issues current harmonics

    CERN Document Server

    Mikkili, Suresh

    2015-01-01

    Power Quality Issues: Current Harmonics provides solutions for the mitigation of power quality problems related to harmonics. Focusing on active power filters (APFs) due to their excellent harmonic and reactive power compensation in two-wire (single phase), three-wire (three-phase without neutral), and four-wire (three-phase with neutral) AC power networks with nonlinear loads, the text:Introduces the APF technology, describing various APF configurations and offering guidelines for the selection of APFs for specific application considerationsCompares shunt active filter (SHAF) control strategi

  11. Radial distribution of power starting from the reactivity using nodal schemes of second and third order; Distribucion radial de potencia a partir de la reactividad usando esquemas nodales de segundo y tercer orden

    Energy Technology Data Exchange (ETDEWEB)

    Delfin L, A.; Alonso V, G. [ININ, Km. 36.5 Carretera Mexico-Toluca, 52045 Ocoyocac, Estado de Mexico (Mexico); Valle G, E. del [IPN-ESFM, 07738 Mexico D.F. (Mexico)]. e-mail: adl@nuclear.inin.mx

    2003-07-01

    In this work two nodal schemes of finite element are presented, one of second and the other of third order of accurate that allow to determine the radial distribution of power starting from the corresponding reactivities.The schemes here developed were obtained taking as starting point the equation developed by Driscoll et al, the one which is based on the diffusion approach of 1-1/2 energy groups. This equation relates the power fraction of an assemble with their reactivity and with the power fractions and reactivities of the assemblies that its surround it. Driscoll and collaborators they solve in form approximate such equation supposing that the reactivity of each assemble it is but a lineal function of the burnt one of the fuel. The spatial approach carries out it with the classic technique of finite differences centered in mesh. Nevertheless that the algebraic system to which its arrive it can be solved without more considerations introduce some additional suppositions and adjustment parameters that it allows them to predict results comparable to those contributed by three dimensions analysis and this way to reduce the one obtained error when its compare their results with those of a production code like CASMO. Also in the two schemes that here are presented the same approaches of Driscoll were used being obtained errors of the one 10% and of 5% for the second schemes and third order respectively for a test case that it was built starting from data of the Cycle 1 of the Unit 1 of the Laguna Verde Nucleo electric plant. These errors its were obtained when comparing with a computer program based on the matrix response method. It is sought to have this way a quick and efficient tool for the multicycle analysis in the fuel management. However, this model presents problems in the appropriate prediction of the average burnt of the nucleus and of the burnt one by lot. (Author)

  12. Pragmatic power

    CERN Document Server

    Eccles, William

    2008-01-01

    Pragmatic Power is focused on just three aspects of the AC electrical power system that supplies and moves the vast majority of electrical energy nearly everywhere in the world: three-phase power systems, transformers, and induction motors. The reader needs to have had an introduction to electrical circuits and AC power, although the text begins with a review of the basics of AC power. Balanced three-phase systems are studied by developing their single-phase equivalents. The study includes a look at how the cost of ""power"" is affected by reactive power and power factor. Transformers are cons

  13. PHYSICAL MEANING OF THE «REACTIVE POWER» CONCEPT APPLIED TO THREE-PHASE ENERGY SUPPLY SYSTEMS WITH NON-LINEAR LOAD

    Directory of Open Access Journals (Sweden)

    G.G. Zhemerov

    2015-12-01

    Full Text Available Purpose. The contradictions in the use of the term «reactive power» require justification by clarifying its physical meaning. The aim of the paper is to reveal the physical meaning of the term «reactive power» applied to three-phase three-wire and four-wire energy supply systems. Methodology. We have applied the modern theory of instantaneous active and reactive power, the graphical filling complex branched energy supply system of simplified design scheme, the theory of electrical circuits, computer Matlab-simulation. Results. We have provided answers to six basic questions that reveal the physical meaning and definition of the concept of «reactive power». We have justified the assumptions suggesting a universal calculation formula to determine the relative total power loss in the three-phase energy supply system as the sum of four components caused by: a minimal losses, reactive power, active power pulsations and instantaneous current flow in the neutral wire. Originality. We have developed the definition that reveals the physical meaning of the term «reactive power» for three-phase energy supply systems corresponding to modern theories of instantaneous active and reactive power. Practical value. We have proposed energy efficiency method ideas of energy supply systems with non-linear load based on the additional components of the power losses calculation. The further development of the method will allow to amend the design, selection and operation of the power active filters practices.

  14. The influence of the reactive energy in the electric power sector planning and the need of consolidation of the hourly period for evaluation of the power factor of the loads; A influencia da energia eletrica reativa no planejamento do setor eletrico e a necessidade de consolidacao do periodo horario para avaliacao do fator de potencia das cargas

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Moacyr Trindade de Oliveira

    1993-07-01

    Among expectations of optimization of electric power systems and the national electric rating laws, there is the important factors of consumption and transmission of reactive energy which concerns the objectives of electric sector. Related to it, the DNAEE, ELETROBRAS and the concessionaires have been developing studies in order to optimize the electric system performance, and consequently the investments of concessionaires and consumers, reducing costs imposed to society due to the form of consumption and/or compensation of reactive loads. This work shows the evolution and consolidation of tariff studies and electric performance of the system, indicating the ways which attend the expectations os all segments of the society through a small adaptation of present regulations an rules related to reactive energy, making possible the system growing in supply by the minimum cost. The main objective of this work is to reinforce the real necessity of to remain intact all the new regulation of power factor, that has been consolidated by the DNAEE's document number 085/92 and your revaluation document number 613/93, including the interval of hourly integration for reactive energy at the determinate date and show the damages for the society caused by the postponement of this condition, that has been considerate in the document number 613/93, from April 1994 until April 1996, however keeping in 1994 the introduction of the new power factor reference of 0.92. (author)

  15. Power imbalance and consumerism in the doctor-patient relationship: health care providers' experiences of patient encounters in a rural district in India.

    Science.gov (United States)

    Fochsen, Grethe; Deshpande, Kirti; Thorson, Anna

    2006-11-01

    The aim of this study is to explore health care providers' experiences and perceptions of their encounters with male and female patients in a rural district in India with special reference to tuberculosis (TB) care. The authors conducted semistructured interviews with 22 health care providers, 17 men and 5 women, from the public and private health care sectors. Findings reveal that doctors adopted an authoritarian as well as a consumerist approach in the medical encounter, indicating that power imbalances in the doctor-patient relationship are negotiable and subject to change. Gender was identified as an influencing factor of the doctor's dominance. A patient-centered approach, acknowledging patients' own experiences and shared decision making, is called for and should be included in TB control activities. This seems to be especially important for female patients, whose voices were not heard in the medical encounter.

  16. Reactive arthritis.

    Science.gov (United States)

    Keat, A

    1999-01-01

    Reactive arthritis is one of the spondyloarthropathy family of clinical syndromes. The clinical features are those shared by other members of the spondyloarthritis family, though it is distinguished by a clear relationship with a precipitating infection. Susceptibility to reactive arthritis is closely linked with the class 1 HLA allele B27; it is likely that all sub-types pre-dispose to this condition. The link between HLA B27 and infection is mirrored by the development of arthritis in HLA B27-transgenic rats. In this model, arthritis does not develop in animals maintained in a germ-free environment. Infections of the gastrointestinal, genitourinary and respiratory tract appear to provoke reactive arthritis and a wide range of pathogens has now been implicated. Although mechanistic parallels may exist, reactive arthritis is distinguished from Lyme disease, rheumatic fever and Whipple's disease by virtue of the distinct clinical features and the link with HLA B27. As in these conditions both antigens and DNA of several micro-organisms have been detected in joint material from patients with reactive arthritis. The role of such disseminated microbial elements in the provocation or maintenance of arthritis remains unclear. HLA B27-restricted T-cell responses to microbial antigens have been demonstrated and these may be important in disease pathogenesis. The importance of dissemination of bacteria from sites of mucosal infection and their deposition in joints has yet to be fully understood. The role of antibiotic therapy in the treatment of reactive arthritis is being explored; in some circumstances, both the anti-inflammatory and anti-microbial effects of certain antibiotics appear to be valuable. The term reactive arthritis should be seen as a transitory one, reflecting a concept which may itself be on the verge of replacement, as our understanding of the condition develops. Nevertheless it appropriately describes arthritis that is associated with demonstrable

  17. The physics of power systems operation

    Science.gov (United States)

    Ohler, C.

    2015-08-01

    The article explains the operation of power systems from the point of view of physics. Physicists imagine things, rather than in terms of impedances and circuits, in terms of fields and energy conversions. The account is concrete and simple. The use of alternating current entails the issue of reactive power. Reactive power consists of energy that oscillates between electrical and magnetic fields, it flows on top of the active power which carries the useful energy. The control of active and reactive power is essential for the power system's reliable operation. The frequency of a power system is the same everywhere. The stability of the frequency indicates that generation and demand of active power are equal, a decline in frequency indicates a lack of generation relative to the demand. Adapting the electrical power injected into the system is the way of frequency control. Because of the parasitic inductances and capacitances of overhead lines, cables, and transformers, the voltage at different locations of the power system depends on the load. The voltage is regulated by the combined action of generator excitation, transformer tap changers and series compensation in order to provide consumers with a stable voltage supply. The integration of solar cells and wind turbines into the power system poses some challenges. But the power system is able to accommodate large amounts of fluctuating renewable power generation if the right complementary measures are taken.

  18. The physics of power systems operation

    Directory of Open Access Journals (Sweden)

    Ohler C.

    2015-01-01

    Full Text Available The article explains the operation of power systems from the point of view of physics. Physicists imagine things, rather than in terms of impedances and circuits, in terms of fields and energy conversions. The account is concrete and simple. The use of alternating current entails the issue of reactive power. Reactive power consists of energy that oscillates between electrical and magnetic fields, it flows on top of the active power which carries the useful energy. The control of active and reactive power is essential for the power system’s reliable operation. The frequency of a power system is the same everywhere. The stability of the frequency indicates that generation and demand of active power are equal, a decline in frequency indicates a lack of generation relative to the demand. Adapting the electrical power injected into the system is the way of frequency control. Because of the parasitic inductances and capacitances of overhead lines, cables, and transformers, the voltage at different locations of the power system depends on the load. The voltage is regulated by the combined action of generator excitation, transformer tap changers and series compensation in order to provide consumers with a stable voltage supply. The integration of solar cells and wind turbines into the power system poses some challenges. But the power system is able to accommodate large amounts of fluctuating renewable power generation if the right complementary measures are taken.

  19. Ultra Efficient CHHP Using a High Temperature Fuel Cell to Provide On-Site Process Reducing Gas, Clean Power, and Heat

    Energy Technology Data Exchange (ETDEWEB)

    Jahnke, Fred C. [Fuelcell Energy, Inc., Danbury, CT (United States)

    2015-06-30

    FuelCell Energy and ACuPowder investigated and demonstrated the use of waste anode exhaust gas from a high temperature fuel cell for replacing the reducing gas in a metal processing furnace. Currently companies purchase high pressure or liquefied gases for the reducing gas which requires substantial energy in production, compression/liquefaction, and transportation, all of which is eliminated by on-site use of anode exhaust gas as reducing gas. We performed research on the impact of the gas composition on product quality and then demonstrated at FuelCell Energy’s manufacturing facility in Torrington, Connecticut. This demonstration project continues to operate even though the research program is completed as it provides substantial benefits to the manufacturing facility by supplying power, heat, and hydrogen.

  20. Recipients of electric-powered indoor/outdoor wheelchairs provided by a national health service: a cross-sectional study.

    Science.gov (United States)

    Frank, Andrew O; De Souza, Lorraine H

    2013-12-01

    To describe the characteristics across all ages of powered wheelchair users and the assistive technology prescribed by a regional specialist wheelchair service. Cross-sectional study. Regional wheelchair service. Electric-powered indoor/outdoor wheelchair (EPIOC) users (N=544) with 262 boys and men (mean age ± SD, 41.7±20.7y; range, 8-82y) and 282 girls and women (mean age ± SD, 47.2±19.7y; range, 7-92y). Not applicable. Demographic, clinical/diagnostic details of EPIOC recipients, including pain, (kypho)scoliosis, and ventilators. Technical features, including specialized (adaptive) seating, tilt in space, and modified control systems. Factors were related to age groups: 1 (0-15y), 2 (16-24y), 3 (25-54y), 4 (55-74y), and 5 (≥75y). Neurologic/neuromuscular conditions predominated (81%) with cerebral palsy (18.9%) and multiple sclerosis (16.4%). Conditions presenting at birth or during childhood constituted 39%. Of the participants, 99 had problematic pain, 83 had (kypho)scoliosis, and 11 used ventilators. Specialized (adaptive) seating was provided to 169 users (31%); most had cerebral palsy or muscular dystrophy. Tilt in space was used by 258 (53%) participants. Younger people were more likely to receive tilt in space than older ones. Only 92 had specialized (adaptive) seating and tilt in space (mean age ± SD, 29±17.8y; range, 8-72y). Of the participants, 52 used modified control systems. The diversity of EPIOC users across age and diagnostic groups is shown. Their complex interrelations with these technical features of EPIOC prescriptions are explored. Younger users were more complex because of age-related changes. This study provides outcomes of the EPIOC prescription for this heterogeneous group of very severely disabled people. Copyright © 2013 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  1. Reactive Systems

    DEFF Research Database (Denmark)

    Aceto, Luca; Ingolfsdottir, Anna; Larsen, Kim Guldstrand

    A reactive system comprises networks of computing components, achieving their goals through interaction among themselves and their environment. Thus even relatively small systems may exhibit unexpectedly complex behaviours. As moreover reactive systems are often used in safety critical systems, t...... into account. The book has arisen from various courses taught in Denmark and Iceland and is designed to give students a broad introduction to the area, with exercises throughout......., the need for mathematically based formal methodology is increasingly important. There are many books that look at particular methodologies for such systems. This book offers a more balanced introduction for graduate students and describes the various approaches, their strengths and weaknesses, and when...... they are best used. Milner's CCS and its operational semantics are introduced, together with the notions of behavioural equivalences based on bisimulation techniques and with recursive extensions of Hennessy-Milner logic. In the second part of the book, the presented theories are extended to take timing issues...

  2. Fuel Temperature Coefficient of Reactivity

    Energy Technology Data Exchange (ETDEWEB)

    Loewe, W.E.

    2001-07-31

    A method for measuring the fuel temperature coefficient of reactivity in a heterogeneous nuclear reactor is presented. The method, which is used during normal operation, requires that calibrated control rods be oscillated in a special way at a high reactor power level. The value of the fuel temperature coefficient of reactivity is found from the measured flux responses to these oscillations. Application of the method in a Savannah River reactor charged with natural uranium is discussed.

  3. Estimating systemic fibrosis by combining galectin-3 and ST2 provides powerful risk stratification value for patients after acute decompensated heart failure.

    Science.gov (United States)

    Wang, Chao-Hung; Yang, Ning-I; Liu, Min-Hui; Hsu, Kuang-Hung; Kuo, Li-Tang

    2016-01-01

    Two fibrosis biomarkers, galectin-3 (Gal-3) and suppression of tumorigenicity 2 (ST2), provide prognostic value additive to natriuretic peptides and traditional risk factors in patients with heart failure (HF). However, it is to be investigated whether their combined measurement before discharge provides incremental risk stratification for patients after acute HF. A total of 344 patients with acute HF were analyzed with Gal-3, and ST2 measured. Patients were prospectively followed for 3.7 ± 1.3 years for deaths, and composite events (death/HF-related re-hospitalizations). The levels of Gal-3 and ST2 were only slightly related (r = 0.20, p risk factors. According to the cutoff at median values, patients were separated into four subgroups based on high and low Gal-3 (HG and LG, respectively) and ST2 levels (HS and LS, respectively). Kaplan-Meier survival curves showed that HGHS powerfully identified patients at risk of mortality (Log rank = 21.27, p risk stratification value.

  4. An Active Power Filter Based on a Three-Level Inverter and 3D-SVPWM for Selective Harmonic and Reactive Compensation

    OpenAIRE

    José Luis Monroy-Morales; David Campos-Gaona; Máximo Hernández-Ángeles; Rafael Peña-Alzola; José Leonardo Guardado-Zavala

    2017-01-01

    Active Power Filters (APFs) have been used for reducing waveform distortion and improving power quality. However, this function can be improved by means of a selective harmonic compensation. Since an APF has rating restrictions, it is convenient to have the option of selecting an individual or a set of particular harmonics in order to compensate and apply the total APF capabilities to eliminate these harmonics, in particular those with a greater impact on the Total Harmonic Distortion (THD). ...

  5. Influence of the electrical power applied to the target on the optical and structural properties of ZrON films produced via RF magnetron sputtering in a reactive atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Pinzón, M.J. [Grupo de Ciencia de Materiales y Superficies, Departamento de Física, Universidad Nacional de Colombia, AA 14490 Bogotá (Colombia); Alfonso, J.E., E-mail: jealfonsoo@unal.edu.co [Grupo de Ciencia de Materiales y Superficies, Departamento de Física, Universidad Nacional de Colombia, AA 14490 Bogotá (Colombia); Olaya, J.J. [Grupo de Ciencia de Materiales y Superficies, Departamento de Física, Universidad Nacional de Colombia, AA 14490 Bogotá (Colombia); Cubillos, G.I.; Romero, E. [Grupo de Materiales y Procesos Químicos, Universidad Nacional de Colombia, AA 14490 Bogotá (Colombia)

    2014-12-01

    The influence of the variation of electrical power applied to the target on the morphology and optical properties of zirconium oxynitride - zirconium oxide (ZrON) films deposited via RF magnetron sputtering on common glass substrates in a reactive atmosphere of N{sub 2}/O{sub 2}, with a flow ratio ΦN{sub 2}/ΦO{sub 2} of 1.25 was investigated. The crystallographic structure of the films was established through X-ray diffraction (XRD), the morphology was evaluated through scanning electron microscopy (SEM) and atomic force microscopy (AFM), and the optical behavior was evaluated through transmittance measurements. The XRD analysis showed that the films grew with mixed crystalline structures: monoclinic (ZrO{sub 2}) and body-centered cubic (Zr{sub 2}ON{sub 2}). SEM analysis showed that the films grew with a homogeneous morphology, and AFM results established that as the electrical power applied to the target increased, there were changes in the grain size and the roughness of the films. The thickness, refractive index, and absorption coefficient of the films were calculated using the values of the transmittance through the Swanepoel method. Additionally, the energy band gap was determined via analysis of the free interference region. - Highlights: • We growth zirconium oxynitride films by RF magnetron sputtering in reactive atmosphere. • We determine the influence of the electrical power applied at the target in optical and structural properties. • We determine the crystallite size, grain size and roughness of the zirconium oxynitride films. • We determine the optical parameters such refractive index of the zirconium oxynitride films through Swanepoel method. • We calculated the absorption coefficient and optical band gap of the zirconium oxynitride films.

  6. Combined magnetic resonance and diffusion tensor imaging analyses provide a powerful tool for in vivo assessment of deformation along human muscle fibers.

    Science.gov (United States)

    Pamuk, Uluç; Karakuzu, Agah; Ozturk, Cengizhan; Acar, Burak; Yucesoy, Can A

    2016-10-01

    Muscle fiber direction strain provides invaluable information for characterizing muscle function. However, methods to study this for human muscles in vivo are lacking. Using magnetic resonance (MR) imaging based deformation analyses and diffusion tensor (DT) imaging based tractography combined, we aimed to assess muscle fiber direction local tissue deformations within the human medial gastrocnemius (GM) muscle. Healthy female subjects (n=5, age=27±1 years) were positioned prone within the MR scanner in a relaxed state with the ankle angle fixed at 90°. The knee was brought to flexion (140.8±3.0°) (undeformed state). Sets of 3D high resolution MR, and DT images were acquired. This protocol was repeated at extended knee joint position (177.0±1.0°) (deformed state). Tractography and Demons nonrigid registration algorithm was utilized to calculate local deformations along muscle fascicles. Undeformed state images were also transformed by a synthetic rigid body motion to calculate strain errors. Mean strain errors were significantly smaller then mean fiber direction strains (lengthening: 0.2±0.1% vs. 8.7±8.5%; shortening: 3.3±0.9% vs. 7.5±4.6%). Shortening and lengthening (up to 23.3% and 116.7%, respectively) occurs simultaneously along individual fascicles despite imposed GM lengthening. Along-fiber shear strains confirm the presence of much shearing between fascicles. Mean fiber direction strains of different tracts also show non-uniform distribution. Inhomogeneity of fiber strain indicates epimuscular myofascial force transmission. We conclude that MR and DT imaging analyses combined provide a powerful tool for quantifying deformation along human muscle fibers in vivo. This can help substantially achieving a better understanding of normal and pathological muscle function and mechanisms of treatment techniques. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Comparison Study of Power System Small Signal Stability Improvement Using SSSC and STATCOM

    DEFF Research Database (Denmark)

    Hu, Weihao; Su, Chi; Fang, Jiakun

    2013-01-01

    A static synchronous series compensator (SSSC) has the ability to emulate a reactance in series with the connected transmission line. A static synchronous compensator (STATCOM) is able to provide the reactive power to an electricity network. When fed with some supplementary signals from...... the connected power system, both SSSC and STATCOM are able to participate in the power system inter-area oscillation damping by changing the compensated reactance or the provided reactive power. This paper analyses the influence of SSSC and STATCOM on power system small signal stability. The damping controller...

  8. 1:1 FASTA update: Using the power of E-values in FASTA to detect potential allergen cross-reactivity

    Directory of Open Access Journals (Sweden)

    Ping Song

    2015-01-01

    Full Text Available In the context of regulatory assessment of transgenic proteins for potential allergenicity, a previous investigation demonstrated that a 1:1 FASTA comparison using an E-value of 1.0E-09 as a criterion is superior to the conventional FASTA search (using the whole sequence as a query for >35% identity over 80 amino acids, but with improved specificity. A further study, using groups of known cross-reactive peanut allergens, indicates the sensitivity of this approach is superior to the conventional FASTA search and equivalent to 80-mer sliding window FASTA search recommended by WHO/FAO. Specifically, the 1:1 FASTA approach eliminated the technical issues resulting from lack of identification of short query sequences with high identity to known allergens, or high identity over short amino acid stretches, and different E-value settings when searching for >35% identity over 80aa. Based on the performance of this simple application of existing bioinformatics tools, and its ease of implementation and interpretation in the context of a regulatory assessment, we advocate that adoption of this 1:1 FASTA approach as a supplement to the FAO/WHO/ CODEX criterion (>35% identity over 80aa formulated 13 years ago. Adoption of this approach eliminates many biologically irrelevant homology hits generated by the FAO/WHO/CODEX criterion and improves the safety assessment of GM crops.

  9. Instantaneous power theory and applications to power conditioning

    CERN Document Server

    Akagi, Hirofumi; Aredes, Mauricio

    2017-01-01

    This new edition, written by a team of experts in the field, is fully updated with information on the latest electric power technology. The instantaneous power theory, or “the p-q theory,” makes clear the physical meaning of what instantaneous real and imaginary power is in a three-phase circuit. Moreover, it provides insight into how energy flows from a source to a load, or circulates between phases, in a three-phase circuit. This theory can be used in the design and understanding of FACTS (Flexible AC Transmission System) compensators. The book introduces many concepts in the field of active filtering that are unique to this edition. It provides a study tool for final year undergraduate students, graduate students and engineers dealing ith harmonic pollution problems, reactive power compensation or power quality in general.

  10. Experiment and CFD Analysis of Reactive Muffler

    OpenAIRE

    Yunshi Yao; Shaodong Wei; Jinpeng Zhao; Shibin Chen; Zhongxu Feng; Jinxi Yue

    2013-01-01

    A conventional muffler used in vibratory rollers is usually designed based on experience and its performance could be enhanced in a large degree through structure optimization. In order to evaluate performance of reactive muffler and its effect on power loss of engine, flow field of muffler was discussed by CFD comparing with experimental test and the structure of reactive muffler was optimized. Based on results of simulation and optimization, the reactive muffler used in vibratory rollers wi...

  11. Electric Substations, Electric substation locations provided to us from Kansas City Power and Light and City of Gardner only at this time. AIMS is working on getting other providers in area. Data is limited to CUE (Collaborative Utility Exchange) Participants and subcontracto, Published in 2004, Johnson County Government.

    Data.gov (United States)

    NSGIC Local Govt | GIS Inventory — Electric Substations dataset current as of 2004. Electric substation locations provided to us from Kansas City Power and Light and City of Gardner only at this time....

  12. Transmission Lines or Poles, Electric, Electric transmission lines locations provided to us from Kansas City Power and Light and City of Gardner only at this time. AIMS is working on getting other providers in area. Data is limited to CUE (Collaborative Utility Exchange) Participants and subc, Published in 2004, Johnson County Government.

    Data.gov (United States)

    NSGIC Local Govt | GIS Inventory — Transmission Lines or Poles, Electric dataset current as of 2004. Electric transmission lines locations provided to us from Kansas City Power and Light and City of...

  13. Spring 5 & reactive streams

    CERN Document Server

    CERN. Geneva; Clozel, Brian

    2017-01-01

    Spring is a framework widely used by the world-wide Java community, and it is also extensively used at CERN. The accelerator control system is constituted of 10 million lines of Java code, spread across more than 1000 projects (jars) developed by 160 software engineers. Around half of this (all server-side Java code) is based on the Spring framework. Warning: the speakers will assume that people attending the seminar are familiar with Java and Spring’s basic concepts. Spring 5.0 and Spring Boot 2.0 updates (45 min) This talk will cover the big ticket items in the 5.0 release of Spring (including Kotlin support, @Nullable and JDK9) and provide an update on Spring Boot 2.0, which is scheduled for the end of the year. Reactive Spring (1h) Spring Framework 5.0 has been released - and it now supports reactive applications in the Spring ecosystem. During this presentation, we'll talk about the reactive foundations of Spring Framework with the Reactor project and the reactive streams specification. We'll al...

  14. Obtaining additional energy savings from the Filumex project by means of the reactive power compensation; Obtencion de ahorros adicionales del proyecto Filumex mediante la compensacion de la potencia reactiva

    Energy Technology Data Exchange (ETDEWEB)

    Cervantes Jaramillo, Enrique L.; Loredo Gutierrez, Miguel Angel; Hernandez Hernandez, Eduardo [Comision Federal de Electricidad, Mexico, D. F. (Mexico)

    1996-12-31

    This paper presents the proposal for establishing in a parallel way to Flamex project, the compensation in the intermediate tension network for the increment in reactive power supplied to the domestic user. This is due to the following three phenomena that occur in replacing incandescent light bulbs with fluorescent lamps: a) A fluorescent lamp has a power factor of 0.9; consequently it requires the supply of a reactive power of about 50% of its capacity. b) In replacing an incandescent light bulb for a fluorescent lamp, approximately 80% of its capacity is not supplied, this leads to the disappearance of a good deal of the user`s purely resistive load, that will cause that its natural power factor is decreased from 0.91 to 0.86 lagging. c) In decreasing the annual maximum demand in the distribution circuit in a greater proportion than the decrease of the annual consumption, their load factors and the annual losses will be increased and therefore the share of its annual energy losses will be increased in about 18.9%. The above, gives rise to the fact that the compensation of reactive power by means of the installation of capacitor banks in the main leads of the distribution circuit, turns out to be a highly appealing technical-economical solution, with a Benefit/Cost rate of 4, a return time of the investment of 2 years and a net benefit of $4.78/user (Pesos). [Espanol] Se presenta la propuesta para establecer en una forma paralela al proyecto FILUMEX, la compensacion en la red de media tension del incremento de la potencia reactiva suministrada al usuario domestico. Este es debido a los siguientes tres fenomenos que ocurren al sustituir los focos incandescentes por lamparas fluorescentes: a) Una lampara fluorescente tiene un factor de potencia de 0.9, por lo que requiere el suministro de una potencia reactiva de aproximadamente el 50% de su capacidad. b) Al sustituirse un foco incandescente por una lampara fluorescente, se deja de suministrar aproximadamente el 80

  15. Network models provide insights into how oriens–lacunosum-moleculare and bistratified cell interactions influence the power of local hippocampal CA1 theta oscillations

    Directory of Open Access Journals (Sweden)

    Katie A Ferguson

    2015-08-01

    Full Text Available Hippocampal theta is a 4-12 Hz rhythm associated with episodic memory, and although it has been studied extensively, the cellular mechanisms underlying its generation are unclear. The complex interactions between different interneuron types, such as those between oriens--lacunosum-moleculare (OLM interneurons and bistratified cells (BiCs, make their contribution to network rhythms difficult to determine experimentally. We created network models that are tied to experimental work at both cellular and network levels to explore how these interneuron interactions affect the power of local oscillations. Our cellular models were constrained with properties from patch clamp recordings in the CA1 region of an intact hippocampus preparation in vitro. Our network models are composed of three different types of interneurons: parvalbumin-positive (PV+ basket and axo-axonic cells (BC/AACs, PV+ BiCs, and somatostatin-positive OLM cells. Also included is a spatially extended pyramidal cell model to allow for a simplified local field potential representation, as well as experimentally-constrained, theta frequency synaptic inputs to the interneurons. The network size, connectivity, and synaptic properties were constrained with experimental data. To determine how the interactions between OLM cells and BiCs could affect local theta power, we explored a number of OLM-BiC connections and connection strengths.We found that our models operate in regimes in which OLM cells minimally or strongly affected the power of network theta oscillations due to balances that, respectively, allow compensatory effects or not. Inactivation of OLM cells could result in no change or even an increase in theta power. We predict that the dis-inhibitory effect of OLM cells to BiCs to pyramidal cell interactions plays a critical role in the power of network theta oscillations. Our network models reveal a dynamic interplay between different classes of interneurons in influencing local theta

  16. Supercapacitor to Provide Ancillary Services: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, Eduard [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Gevorgian, Vahan [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Luo, Yusheng [Idaho National Laboratory; Mohanpurkar, M. [Idaho National Laboratory; Hovsapian, R. [Idaho National Laboratory; Koritarov, V. [Argonne National Laboratory

    2017-10-09

    Supercapacitor technology has reached a level of maturity as a viable energy storage option available to support a modern electric power system grid; however, its application is still limited because of its energy capacity and the cost of the commercial product. In this paper, we demonstrate transient models of supercapacitor energy storage plants operating in coordination with run-of-the-river (ROR), doubly-fed induction generator hydropower plants (HPP) using a system control concept and architecture developed. A detailed transient model of a supercapacitor energy storage device is coupled with the grid via a three-phase inverter/rectifier and bidirectional DC-DC converter. In addition, we use a version of a 14-bus IEEE test case that includes the models of the supercapacitor energy storage device, ROR HPPs, and synchronous condensers that use the rotating synchronous generators of retired coal-powered plants. The purpose of the synchronous condensers is to enhance the system stability by providing voltage and reactive power control, provide power system oscillations damping, and maintain system inertia at secure levels. The control layer provides coordinated, decentralized operation of distributed ROR HPPs and energy storage as aggregate support to power system operations.

  17. Method for generating a highly reactive plasma for exhaust gas aftertreatment and enhanced catalyst reactivity

    Science.gov (United States)

    Whealton, John H.; Hanson, Gregory R.; Storey, John M.; Raridon, Richard J.; Armfield, Jeffrey S.; Bigelow, Timothy S.; Graves, Ronald L.

    2002-01-01

    A method for non-thermal plasma aftertreatment of exhaust gases the method comprising the steps of providing short risetime, high frequency, high power bursts of low-duty factor microwaves sufficient to generate a plasma discharge and passing a gas to be treated through the discharge so as to cause dissociative reduction of the exhaust gases and enhanced catalyst reactivity through application of the pulsed microwave fields directly to the catalyst material sufficient to cause a polarizability catastrophe and enhanced heating of the metal crystallite particles of the catalyst, and in the presence or absence of the plasma. The invention also includes a reactor for aftertreatment of exhaust gases.

  18. Power Sharing Control between Load-Side Inverters in DC Microgrid for Super High Quality Electric Power Distribution System

    Science.gov (United States)

    Kakigano, Hiroaki; Nada, Kaho; Miura, Yushi; Ise, Toshifumi; Uchida, Ryohei

    DC microgrid is a novel power system using dc distribution in order to provide a super high quality electric power. The dc distribution system is suitable for dc output type distributed generations such as photovoltaic and fuel cells, and energy storages such as batteries and electric double layer capacitors. Power is distributed through dc distribution line and converted to required ac or dc voltage by converters placed near loads. Load-side single phase inverters are connected through transformers in order to share active and reactive power. In this paper, a power sharing control scheme was proposed, and the power sharing characteristics were demonstrated by experimental results.

  19. Unique insights into the nanoworld. A unique highest-power microscope provides access to the world of atoms; Einzigartige Einblicke in die Nanowelt

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2012-07-01

    With the best electron microscopes of our time in the Ernst Ruska center (ER-C) researchers can map the arrangement of atoms in a material and study very detailedly. This is for the progress in material science and nanotechnology deciding, then the interplay of the atoms determines the properties of materials and components. The ER-C, which is operated commonly by the Juelich Research Center and by the RWTH Aachen, has now supplemented its device park by an Europe-widely unique highest-power microscope: PICO corrects beside the spherical aberration yet a further lens error - the chromatic aberration - and reaches so a record resolution of 50 billionth millimeters.

  20. Coordination of International Standards with Implementation of the IECRE Conformity Assessment System to Provide Multiple Certification Offerings for PV Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, George; Haring, Adrian; Spooner, Ted; Ball, Greg; Kurtz, Sarah; Heinze, Matthias; Yamamichi, Masaaki; Eguchi, Yoshihito; Ramu, Govind

    2016-11-21

    To help address the industry's needs for assuring the value and reducing the risk of investments in PV power plants; the International Electrotechnical Commission (IEC) has established a new conformity assessment system for renewable energy (IECRE). There are presently important efforts underway to define the requirements for various types of PV system certificates, and publication of the international standards upon which these certifications will be based. This paper presents a detailed analysis of the interrelationship of these activities and the timing for initiation of IECRE PV system certifications.

  1. Application of the optimum reactive power dispatch to the cost establishment for the support voltage in a power electrical system for generalized dispatch; Aplicacion del despacho optimo de potencia reactiva al establecimiento del costo por el soporte de voltaje en un sistema electrico de potencia con despacho centralizado

    Energy Technology Data Exchange (ETDEWEB)

    Barragan Gomez, Sergio Baruch

    2004-05-15

    The changes in the structures of the electric systems of vertical schemes to horizontal schemes have caused systems to be formed by four segments: generation, transmission, distribution and commercialization. Under this scheme the system operator is the one in charge of guaranteeing an economic and secure administration-operation. One of the main tasks of this organization together with the transmission net is achieving the movement of power from the generation centers until the consumption points, however in order to make this activity possible, a group of auxiliary service is needed. In a horizontal scheme, the voltage support of the generators is considered as an auxiliary service, which is necessary for the operation of the system. Although compensation of reactive power should be achieved in a local way through shunt compensation, static compensators, synchronous condensers and transformers with under load tap changer, because transmitting reactive power flow from generators causes an increment in the transmission system losses, however although the main function of the synchronous generators is the production of active power, in an implicit way these generate reactive power under certain operation conditions. Therefore the need of determining a cost for the voltage support of the generators exists, since this action is considered as an auxiliary service and it is rewarded in an independent way. In this work, the gradient method is used to solve the reactive power dispatch and determine the cost for voltage support of each participant generator in the system. The reactive power dispatch is subject to equality restrictions that represent the balance equations of active and reactive power of each node and to inequality restrictions that correspond to limits in the voltage profiles of all the system nodes. The equality restrictions are considered with the Lagrange multipliers method and the inequality restrictions with quadratic penalty functions. The total cost

  2. Solvent reactivation of adhesives in textile conservation: survey and comparison with heat reactivation

    Directory of Open Access Journals (Sweden)

    Célia Medina

    2006-01-01

    Full Text Available Current practice of solvent reactivation of adhesives in textile conservation was assessed using two methodologies: an international survey of conservators, and practical tests that provided a comparative study between two different reactivation techniques, heat and solvents. Despite some recent technical developments in the application of solvent reactivation for the treatment of textiles, the survey pointed out that conservators are using solvent reactivation techniques less often than more familiar and longer established heat reactivation techniques. The comparative study proved that the two adhesive reactivating techniques (solvents or heat produce very different results in practice. Moreover, different solvent reactivation techniques (applied via brush or in vapour form and different solvents used to reactivate the adhesive also produce diverse results. Some of the possible variables to consider when selecting reactivation techniques for adhesives are highlighted.

  3. Dysregulated negative emotional reactivity as a predictor of chronic peer victimization in childhood.

    Science.gov (United States)

    Rosen, Paul J; Milich, Richard; Harris, Monica J

    2012-01-01

    This study examined the relations of dysregulated negative emotional reactivity, emotional distress, and chronic peer victimization in childhood. A model was proposed whereby dysregulated reactivity was directly and indirectly related to concurrent peer victimization through victimization-related emotional distress. The model further proposed that dysregulated reactivity directly incrementally predicted longitudinal peer victimization above and beyond the effect of concurrent victimization. Two hundred thirteen 9- to 13-year-old children and their parents completed measures of dysregulated reactivity and victimization experiences at baseline and 6-month follow-up. Children also related narratives of personal victimization experiences at baseline that were coded to assess victimization-related emotional distress. Model testing strongly supported the direct association of dysregulated reactivity with concurrent victimization and incremental predictive effects of dysregulated reactivity on peer victimization over time. Model testing also provided support for an indirect effect of dysregulated reactivity on concurrent peer victimization through victimization-related emotional distress. This study demonstrated the powerful role that dysregulated negative emotional reactivity plays in the development of chronic peer victimization over time. © 2012 Wiley Periodicals, Inc.

  4. Reactivity analysis for numerical solution of the point kinetic equation for subcritical; Analise da reatividade para solucao numerica da equacao da cinetica pontual para sistemas subcriticos

    Energy Technology Data Exchange (ETDEWEB)

    Henrice Junior, Edson; Goncalves, Alessandro da Cruz, E-mail: ejunior@nuclear.ufrj.br, E-mail: alessandro@nuclear.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Energia Nuclear; Palma, Daniel Artur Pinheiro, E-mail: dapalma@cnen.gov.br [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil); Mesquita, Amir Zacarias, E-mail: amir@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2015-07-01

    This paper provides a comparison between the reactivity calculated by the approximation based on the multiplication factor (K{sub eff}) and a new approach for the reactivity calculation to be used in the kinetics point equation for subcritical systems. To obtain the necessary kinetic parameters as well and the reference Power value calculation and validation, a subcritical system was simulated with the Monte Carlo code Serpent. This study is important for determining nuclear Power in such systems. The results shown consistent values with the validation method and new in-depth studies to calculate the reactivity should be performed to such systems, making the issue a very current theme. (author)

  5. Carbon as Investment Risk—The Influence of Fossil Fuel Divestment on Decision Making at Germany’s Main Power Providers

    Directory of Open Access Journals (Sweden)

    Dagmar Kiyar

    2015-09-01

    Full Text Available German electricity giants have recently taken high-level decisions to remove selected fossil fuel operations from their company portfolio. This new corporate strategy could be seen as a direct response to the growing global influence of the fossil fuel divestment campaign. In this paper we ask whether the divestment movement currently exerts significant influence on decision-making at the top four German energy giants—E.On, RWE, Vattenfall and EnBW. We find that this is not yet the case. After describing the trajectory of the global fossil fuel divestment campaign, we outline four alternative influences on corporate strategy that, currently, are having a greater impact than the divestment movement on Germany’s power sector. In time, however, clear political decisions and strong civil support may increase the significance of climate change concerns in the strategic management of the German electricity giants.

  6. Análisis de la compensación de potencia reactiva en sistemas contaminados con armónicos; Analysis of the Reactive Power Compensation in Contaminated Systems with Harmonics

    Directory of Open Access Journals (Sweden)

    Secundino Marrero Ramírez

    2011-02-01

    Full Text Available En este artículo se presentan los resultados obtenidos en la evaluación de una red industrial con presenciade contaminación armónica, donde las cargas no lineales corresponden fundamentalmente a rectificadoresy variadores de velocidad. Se establecieron los armónicos típicos generados por estas cargas y ellopermitió determinar los niveles de distorsión armónica de tensión y corriente para analizar su influencia enla selección del banco de condensadores durante la compensación de la potencia reactiva atendiendo alcomportamiento del sistema ante diferentes estados de carga.  The article is given the evaluation obtained of an industrial network with the presence of harmoniccontamination, where the non lineal loads correspond fundamentally to rectifiers and variators of speed.Where the typical harmonic generated by these loads settled down and it allowed it to determine the levelsof harmonic distortion of tension and current to analyze their influence in the selection of the bank ofcondensers during the compensation of the power it reactivates assisting to the behavior of the systembefore different load states.

  7. Plasma characterization in reactive sputtering processes of Ti in Ar/O2 mixtures operated in metal, transition and poisoned modes: a comparison between direct current and high-power impulse magnetron discharges

    Science.gov (United States)

    Haase, Fabian; Kersten, Holger; Lundin, Daniel

    2017-10-01

    Two reactive sputtering techniques have been studied: direct current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HiPIMS), operated in various Ar/O2 gas mixtures using a Ti target. The processes were characterized during different modes of operation including pure argon, metallic, transition and compound mode. Energy flux data as well as data on electron density and temperature were combined to obtain knowledge about the trends and changes in the investigated internal process plasma properties for the different modes investigated. Although there is a large reduction of the mass deposition rate (a factor 10 in DCMS and a factor 14 in HiPIMS), when transiting from the metal to compound mode, we detect no significant decrease of the total energy flux in DCMS and only a minor decrease in HiPIMS ( <20%). Such a result is surprising considering that the neutral flux contribution to the total energy flux is known to be significant. Instead, we find that the reduction of the neutral component is compensated by an increase in the electron and ion flux components, which is experimentally detected as an increase of the effective electron temperature and a slightly increasing (DCMS) or essentially constant (HiPIMS) electron density with increasing oxygen flow rate.

  8. The impact of fuel temperature reactivity coefficient on loss of reactivity control accident

    Energy Technology Data Exchange (ETDEWEB)

    Park, J. H.; Ryu, E. H.; Song, Y. M.; Jung, J. Y. [KAERI, Daejeon (Korea, Republic of)

    2012-10-15

    Nuclear reactors experience small power fluctuations or anticipated operational transients during even normal power operation. During normal operation, the reactivity is mainly controlled by liquid zone controllers, adjuster rods, mechanical control absorbers, and moderator poison. Even when the reactor power is increased abruptly and largely from an accident and when reactor control systems cannot be actuated quickly due to a fast transient, the reactor should be controlled and stabilized by its inherent safety parameter, such as a negative PCR (Power Coefficient of Reactivity) feedback. A PWR (Pressurized Water Reactor), it is well designed for the reactor to have a negative PCR so that the reactor can be safely shut down or stabilized whenever an abrupt reactivity insertion into the reactor core occurs or the reactor power is abruptly increased. However, it is known that a CANDU reactor has a small amount of PCR, as either negative or positive, because of the different design basis and safety concepts from a PWR. CNSC's regulatory and safety regime has stated that; The PCR of CANDU reactors does not pose a significant risk. Consistent with Canadian nuclear safety requirements, nuclear power plants must have an appropriate combination of inherent and engineered safety features incorporated into the design of the reactor safety and control systems. A reactor design that has a PCR is quite acceptable provided that the reactor is stable against power fluctuations, and that the probability and consequences of any potential accidents that would be aggravated by a positive reactivity feedback are maintained within CNSCprescribed limits. Recently, it was issued licensing the refurbished Wolsong unit 1 in Korea to be operated continuously after its design lifetime in which the calculated PCR was shown to have a small positive value by applying the recent physics code systems, which are composed of WIMS IST, DRAGON IST, and RFSP IST. These code systems were

  9. Medicare Provider Data - Hospice Providers

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Hospice Utilization and Payment Public Use File provides information on services provided to Medicare beneficiaries by hospice providers. The Hospice PUF...

  10. A Multi-Functional Power Electronic Converter in Distributed Generation Power Systems

    DEFF Research Database (Denmark)

    Chen, Zhe; Blaabjerg, Frede; Pedersen, John Kim

    2005-01-01

    This paper presents a power electronic converter which is used as an interface for a distributed generation unit/energy storage device, and also functioned as an active power compensator in a hybrid compensation system. The operation and control of the converter have been described. An example...... and passive filters connected to each distorting load or distributed generation (DG) unit. The passive filters are distributely located to remove major harmonics and provide reactive power compensation. The active power electronic filter corrects the system unbalance, removes the remaining harmonic components......, and damps the possible harmonic resonance. Simulation results demonstrate that the converter system can transfer the real power by following a desired reference power for a variable speed wind power conversion system to effectively extract the renewable energy and also enhance the power quality...

  11. CONTROL SYSTEM FOR MULTILEVEL INVERTOR OF SOLAR POWER STATION

    Directory of Open Access Journals (Sweden)

    S.M. Levitskiy

    2015-11-01

    Full Text Available Purpose. The development of control law for network multilevel invertor of solar power station and design device for control law realization. Methodology. At synthesis of control law theory of automatic control, power network engineering and circuit technique are considered. The control law for distributive control over the direct-axis and quadrature-axis currents of invertor after abc-dq transform of three phase current’s momentary value is used. Results. The improved model of regulator of direct-axis invertor’s current is developed and provides the voltage optimization of invertor’s operating both from solar module and from network by means of calculation the reactive power consumption from network, voltage on network and voltage on solar module. The improved model of regulator of quadrature-axis invertor’s current is developed and provides the power and frequency optimization of invertor’s operating by means of calculation ratio of active power consumption and power from solar module. Originality. The offered control law and device, which realize it, is working out on secondary loop from power network smart grid with active and reactive power consumption monitoring. That provides the optimal operation of solar station both from solar module and from power network. Practical value. The proposed control law and structure of the network multilevel invertor for solar power station provide the operate mode of solar module in maximum power point and increasing the solar module’s productivity.

  12. Web-based collaboration in individual care planning challenges the user and the provider roles – toward a power transition in caring relationships

    Directory of Open Access Journals (Sweden)

    Bjerkan J

    2014-12-01

    Full Text Available Jorunn Bjerkan,1,2 Solfrid Vatne,3 Anne Hollingen4 1Norwegian Research Centre for Electronic Health Records (EHR, Medical Faculty, Norwegian University of Science and Technology, Trondheim, 2Faculty of Health Science, Nord-Trøndelag University College, Levanger, 3Faculty of Health Science, Molde University College, 4Møre og Romsdal Hospital Trust, Molde, Norway Background and objective: The Individual Care Plan (ICP was introduced in Norway to meet new statutory requirements for user participation in health care planning, incorporating multidisciplinary and cross-sector collaboration. A web-based solution (electronic ICP [e-ICP] was used to support the planning and documentation. The aim of this study was to investigate how web-based collaboration challenged user and professional roles. Methods: Data were obtained from 15 semistructured interviews with users and eight with care professionals, and from two focus-group interviews with eight care professionals in total. The data were analyzed using systematic text condensation in a stepwise analysis model. Results: Users and care professionals took either a proactive or a reluctant role in e-ICP collaboration. Where both user and care professionals were proactive, the pairing helped to ensure that the planning worked well; so did pairings of proactive care professionals and reluctant users. Proactive users paired with reluctant care professionals also made care planning work, thanks to the availability of information and the users' own capacity or willingness to conduct the planning. Where both parties were reluctant, no planning activities occurred. Conclusion: Use of the e-ICP challenged the user–professional relationship. In some cases, a power transition took place in the care process, which led to patient empowerment. This knowledge might be used to develop a new understanding of how role function can be challenged when users and care professionals have equal access to health care

  13. Camelid Ig V genes reveal significant human homology not seen in therapeutic target genes, providing for a powerful therapeutic antibody platform

    Science.gov (United States)

    Klarenbeek, Alex; Mazouari, Khalil El; Desmyter, Aline; Blanchetot, Christophe; Hultberg, Anna; de Jonge, Natalie; Roovers, Rob C; Cambillau, Christian; Spinelli, Sylvia; Del-Favero, Jurgen; Verrips, Theo; de Haard, Hans J; Achour, Ikbel

    2015-01-01

    Camelid immunoglobulin variable (IGV) regions were found homologous to their human counterparts; however, the germline V repertoires of camelid heavy and light chains are still incomplete and their therapeutic potential is only beginning to be appreciated. We therefore leveraged the publicly available HTG and WGS databases of Lama pacos and Camelus ferus to retrieve the germline repertoire of V genes using human IGV genes as reference. In addition, we amplified IGKV and IGLV genes to uncover the V germline repertoire of Lama glama and sequenced BAC clones covering part of the Lama pacos IGK and IGL loci. Our in silico analysis showed that camelid counterparts of all human IGKV and IGLV families and most IGHV families could be identified, based on canonical structure and sequence homology. Interestingly, this sequence homology seemed largely restricted to the Ig V genes and was far less apparent in other genes: 6 therapeutically relevant target genes differed significantly from their human orthologs. This contributed to efficient immunization of llamas with the human proteins CD70, MET, interleukin (IL)-1β and IL-6, resulting in large panels of functional antibodies. The in silico predicted human-homologous canonical folds of camelid-derived antibodies were confirmed by X-ray crystallography solving the structure of 2 selected camelid anti-CD70 and anti-MET antibodies. These antibodies showed identical fold combinations as found in the corresponding human germline V families, yielding binding site structures closely similar to those occurring in human antibodies. In conclusion, our results indicate that active immunization of camelids can be a powerful therapeutic antibody platform. PMID:26018625

  14. Research on the Voltage Fluctuation Rules of Power System Containing Wind Farms

    Science.gov (United States)

    Chen, Yixi; Xu, Guchao; Ma, Gang; Li, Feng; Ju, Rong

    2017-05-01

    The global energy shortage and environmental problems have contributed to the rapid development of wind power. However, due to the randomness and volatility of wind power, large-scale access may cause voltage fluctuation in power grid. Therefore, the reactive power control of power system containing wind farms has become a hot research topic in recent years, in which finding key nodes of voltage fluctuation is a foundation work. In this paper, the power model of wind farm is established first. Then, the influence on nodes voltage when wind farms access simple power system is analysed, and promoted to complex power systems in order to reveal the fluctuation rules of nodes voltage, and to summarize the distribution characteristics of key nodes of voltage fluctuation, which can provide the basis for reactive power optimization. At last, the conclusions are verified by IEEE 30-node system.

  15. Reactive Kripke semantics

    CERN Document Server

    Gabbay, Dov M

    2013-01-01

    This text offers an extension to the traditional Kripke semantics for non-classical logics by adding the notion of reactivity. Reactive Kripke models change their accessibility relation as we progress in the evaluation process of formulas in the model. This feature makes the reactive Kripke semantics strictly stronger and more applicable than the traditional one. Here we investigate the properties and axiomatisations of this new and most effective semantics, and we offer a wide landscape of applications of the idea of reactivity. Applied topics include reactive automata, reactive grammars, rea

  16. OA21 The power to choose: developing community capacity to provide palliative care in four first nations communities in canada.

    Science.gov (United States)

    Kelley, Mary Lou; Prince, Holly; Monture, Lori; Maki, Luanne; Crow, Maxine; Smith, Jeroline

    2015-04-01

    First Nations people in Canada are ageing with a high burden of chronic, progressive, and life-limiting illness. The majority now die in urban hospitals or long term care homes far away from family and culture. Today, First Nations community leaders are working to build local community capacity to support people and their families who choose to die at home. This presentation describes a five year participatory action research project that has enhanced local palliative care capacity in four First Nations communities using innovative strategies for collaboration, education, and advocacy (www.eolfn.lakeheadu.ca). The process of community capacity development was locally driven and controlled. A local leader and advisory committee implemented a palliative care community assessment that identified resources and needs for community awareness, health provider education, service development and improved partnerships with external health care providers (physicians, hospitals etc) providing care to community members. Innovative strategies to address these needs were developed, implemented and evaluated. If services and community supports were available, 87% of the FN community participants would prefer to die at home. Each of the four participating FN communities developed a unique palliative care program model responsive to community culture and context. Culturally appropriate videos and print resources for education and community development were created to share internationally. First Nations communities have the desire and capacity to care for community members to the end of their lives. Community development and advocacy are required to support First Nations in addressing existing barriers and gaps in education, policy and service delivery. © 2015, Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  17. Increasing Integration of Wind Power in Medium Voltage Grid by Voltage Support of Smart Transformer

    OpenAIRE

    Gao, Xiang; De Carne, Giovanni; Liserre, Marco; Vournas, Costas

    2016-01-01

    The voltage rise during wind energy penetration represents a limit of the wind power integration in the distribution grid. The Smart Transformer (ST), a power electronics-based transformer, can provide additional services to the distribution grids, for instance the voltage support in MV grid by means of reactive power injection. In this paper, this service is applied to increase the hosting capacity of wind power in MV grids.

  18. {sup 18}F-FDG PET/CT provides powerful prognostic stratification in the primary staging of large breast cancer when compared with conventional explorations

    Energy Technology Data Exchange (ETDEWEB)

    Cochet, Alexandre [Centre Georges-Francois Leclerc, Department of Nuclear Medicine, Dijon Cedex (France); Le2i UMR CNRS 6306, Dijon (France); Dygai-Cochet, Inna; Riedinger, Jean-Marc; Berriolo-Riedinger, Alina; Toubeau, Michel [Centre Georges-Francois Leclerc, Department of Nuclear Medicine, Dijon Cedex (France); Humbert, Olivier; Brunotte, Francois [Centre Georges-Francois Leclerc, Department of Nuclear Medicine, Dijon Cedex (France); Le2i UMR CNRS 6306, Dijon (France); CHU Dijon, MRI and Spectroscopy Unit, Dijon (France); Guiu, Severine; Coudert, Bruno [Centre Georges-Francois Leclerc, Department of Oncology, Dijon (France); Coutant, Charles; Fumoleau, Pierre [Centre Georges-Francois Leclerc, Department of Surgery, Dijon (France)

    2014-03-15

    The objective of this study was to assess the impact on management and the prognostic value of {sup 18}F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT for initial staging of newly diagnosed large breast cancer (BC) when compared with conventional staging. We prospectively included 142 patients with newly diagnosed BC and at least grade T2 tumour. All patients were evaluated with complete conventional imaging (CI) procedures (mammogram and/or breast ultrasound, bone scan, abdominal ultrasound and/or CT, X-rays and/or CT of the chest), followed by FDG PET/CT exploration, prior to treatment. The treatment plan based on CI staging was compared with that based on PET/CT findings. CI and PET/CT findings were confirmed by imaging and clinical follow-up and/or pathology when assessable. Progression-free survival (PFS) was analysed using the Cox proportional hazards regression model. According to CI staging, 79 patients (56 %) were stage II, 46 (32 %) stage III and 17 (12 %) stage IV (distant metastases). Of the patients, 30 (21 %) were upstaged by PET/CT, including 12 (8 %) from stage II or III to stage IV. On the other hand, 23 patients (16 %) were downstaged by PET/CT, including 4 (3 %) from stage IV to stage II or III. PET/CT had a high or medium impact on management planning for 18 patients (13 %). Median follow-up was 30 months (range 9-59 months); 37 patients (26 %) experienced recurrence or progression of disease during follow-up and 17 patients (12 %) died. The Cox model indicated that CI staging was significantly associated with PFS (p = 0.01), but PET/CT staging provided stronger prognostic stratification (p < 0.0001). Moreover, Cox regression multivariate analysis showed that only PET/CT staging remained associated with PFS (p < 0.0001). FDG PET/CT provides staging information that more accurately stratifies prognostic risk in newly diagnosed large BC when compared with conventional explorations alone. (orig.)

  19. Analysis of the design and economics of molten carbonate fuel cell tri-generation systems providing heat and power for commercial buildings and H2 for FC vehicles

    Science.gov (United States)

    Li, Xuping; Ogden, Joan; Yang, Christopher

    2013-11-01

    This study models the operation of molten carbonate fuel cell (MCFC) tri-generation systems for “big box” store businesses that combine grocery and retail business, and sometimes gasoline retail. Efficiency accounting methods and parameters for MCFC tri-generation systems have been developed. Interdisciplinary analysis and an engineering/economic model were applied for evaluating the technical, economic, and environmental performance of distributed MCFC tri-generation systems, and for exploring the optimal system design. Model results show that tri-generation is economically competitive with the conventional system, in which the stores purchase grid electricity and NG for heat, and sell gasoline fuel. The results are robust based on sensitivity analysis considering the uncertainty in energy prices and capital cost. Varying system sizes with base case engineering inputs, energy prices, and cost assumptions, it is found that there is a clear tradeoff between the portion of electricity demand covered and the capital cost increase of bigger system size. MCFC Tri-generation technology provides lower emission electricity, heat, and H2 fuel. With NG as feedstock the CO2 emission can be reduced by 10%-43.6%, depending on how the grid electricity is generated. With renewable methane as feedstock CO2 emission can be further reduced to near zero.

  20. Monadic Functional Reactive Programming

    NARCIS (Netherlands)

    A.J. van der Ploeg (Atze); C Shan

    2013-01-01

    htmlabstractFunctional Reactive Programming (FRP) is a way to program reactive systems in functional style, eliminating many of the problems that arise from imperative techniques. In this paper, we present an alternative FRP formulation that is based on the notion of a reactive computation: a

  1. RAD genotyping reveals fine-scale genetic structuring and provides powerful population assignment in a widely distributed marine species, the American lobster (Homarus americanus).

    Science.gov (United States)

    Benestan, Laura; Gosselin, Thierry; Perrier, Charles; Sainte-Marie, Bernard; Rochette, Rémy; Bernatchez, Louis

    2015-07-01

    Deciphering genetic structure and inferring connectivity in marine species have been challenging due to weak genetic differentiation and limited resolution offered by traditional genotypic methods. The main goal of this study was to assess how a population genomics framework could help delineate the genetic structure of the American lobster (Homarus americanus) throughout much of the species' range and increase the assignment success of individuals to their location of origin. We genotyped 10 156 filtered SNPs using RAD sequencing to delineate genetic structure and perform population assignment for 586 American lobsters collected in 17 locations distributed across a large portion of the species' natural distribution range. Our results revealed the existence of a hierarchical genetic structure, first separating lobsters from the northern and southern part of the range (FCT  = 0.0011; P-value = 0.0002) and then revealing a total of 11 genetically distinguishable populations (mean FST  = 0.00185; CI: 0.0007-0.0021, P-value < 0.0002), providing strong evidence for weak, albeit fine-scale population structuring within each region. A resampling procedure showed that assignment success was highest with a subset of 3000 SNPs having the highest FST . Applying Anderson's (Molecular Ecology Resources, 2010, 10, 701) method to avoid 'high-grading bias', 94.2% and 80.8% of individuals were correctly assigned to their region and location of origin, respectively. Lastly, we showed that assignment success was positively associated with sample size. These results demonstrate that using a large number of SNPs improves fine-scale population structure delineation and population assignment success in a context of weak genetic structure. We discuss the implications of these findings for the conservation and management of highly connected marine species, particularly regarding the geographic scale of demographic independence. © 2015 John Wiley & Sons Ltd.

  2. Airborne measurement of OH reactivity during INTEX-B

    Directory of Open Access Journals (Sweden)

    J. Mao

    2009-01-01

    Full Text Available The measurement of OH reactivity, the inverse of the OH lifetime, provides a powerful tool to investigate atmospheric photochemistry. A new airborne OH reactivity instrument was designed and deployed for the first time on the NASA DC-8 aircraft during the second phase of Intercontinental Chemical Transport Experiment-B (INTEX-B campaign, which was focused on the Asian pollution outflow over Pacific Ocean and was based in Hawaii and Alaska. The OH reactivity was measured by adding OH, generated by photolyzing water vapor with 185 nm UV light in a moveable wand, to the flow of ambient air in a flow tube and measuring the OH signal with laser induced fluorescence. As the wand was pulled back away from the OH detector, the OH signal decay was recorded; the slope of −Δln(signal/Δ time was the OH reactivity. The overall absolute uncertainty at the 2σ confidence levels is about 1 s−1 at low altitudes (for decay about 6 s−1, and 0.7 s−1 at high altitudes (for decay about 2 s−1. From the median vertical profile obtained in the second phase of INTEX-B, the measured OH reactivity (4.0±1.0 s−1 is higher than the OH reactivity calculated from assuming that OH was in steady state (3.3±0.8 s−1, and even higher than the OH reactivity that was calculated from the total measurements of all OH reactants (1.6±0.4 s−1. Model calculations show that the missing OH reactivity is consistent with the over-predicted OH and under-predicted HCHO in the boundary layer and lower troposphere. The over-predicted OH and under-predicted HCHO suggest that the missing OH sinks are most likely related to some highly reactive VOCs that have HCHO as an oxidation product.

  3. Group excitation control of generators in state regional electric power plant transformer station automatic control systems

    Energy Technology Data Exchange (ETDEWEB)

    Gumin, M.I.; Rosman, L.V.; Tarnavskii, V.M.

    1983-01-01

    Group excitation control of electric generators according to standard methods is essential for the management of power plant conditions according to voltage and reactive power. A system is described that provides coordinated changes in the automatic excitation controller set point for generators that operate on common buses. The advantages of the excitation control system are discussed.

  4. Power flow controller with a fractionally rated back-to-back converter

    Science.gov (United States)

    Divan, Deepakraj M.; Kandula, Rajendra Prasad; Prasai, Anish

    2016-03-08

    A power flow controller with a fractionally rated back-to-back (BTB) converter is provided. The power flow controller provide dynamic control of both active and reactive power of a power system. The power flow controller inserts a voltage with controllable magnitude and phase between two AC sources at the same frequency; thereby effecting control of active and reactive power flows between the two AC sources. A transformer may be augmented with a fractionally rated bi-directional Back to Back (BTB) converter. The fractionally rated BTB converter comprises a transformer side converter (TSC), a direct-current (DC) link, and a line side converter (LSC). By controlling the switches of the BTB converter, the effective phase angle between the two AC source voltages may be regulated, and the amplitude of the voltage inserted by the power flow controller may be adjusted with respect to the AC source voltages.

  5. The Effect of Verbal Reminders on Memory Reactivation in 2-, 3-, and 4-Year-Old Children

    Science.gov (United States)

    Imuta, Kana; Scarf, Damian; Hayne, Harlene

    2013-01-01

    For adults, verbal reminders provide a powerful key to unlock our memories. For example, a simple question, such as "Do you remember your wedding day?" can reactivate rich memories of the past, allowing us to recall experiences that may have occurred days, weeks, and even decades earlier. The ability to use another person's language to…

  6. Control of Solar Power Plants Connected Grid with Simple Calculation Method on Residential Homes

    Science.gov (United States)

    Kananda, Kiki; Nazir, Refdinal

    2017-12-01

    One of the most compatible renewable energy in all regions to apply is solar energy. Solar power plants can be built connected to existing or stand-alone power grids. In assisting the residential electricity in which there is a power grid, then a small scale solar energy power plants is very appropriate. However, the general constraint of solar energy power plants is still low in terms of efficiency. Therefore, this study will explain how to control the power of solar power plants more optimally, which is expected to reactive power to zero to raise efficiency. This is a continuation of previous research using Newton Rapshon control method. In this study we introduce a simple method by using ordinary mathematical calculations of solar-related equations. In this model, 10 PV modules type of ND T060M1 with a 60 Wp capacity are used. The calculations performed using MATLAB Simulink provide excellent value. For PCC voltage values obtained a stable quantity of approximately 220 V. At a maximum irradiation condition of 1000 W / m2, the reactive power value of Q solar generating system maximum 20.48 Var and maximum active power of 417.5 W. In the condition of lower irradiation, value of reactive power Q almost close to zero 0.77Var. This simple mathematical method can provide excellent quality control power values.

  7. Power Capability Investigation Based on Electrothermal Models of Press-pack IGBT Three-Level NPC and ANPC VSCs for Multimegawatt Wind Turbines

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk; Helle, Lars; Munk-Nielsen, Stig

    2012-01-01

    capability investigations regarding a sample grid code's reactive power requirement show that 3L-ANPC-VSC results in 32% better power capability than 3L-NPC-VSC at the switching frequency of 1050 Hz. Furthermore, 3L-ANPC-VSC with 57% higher switching frequency (1650 Hz) and 33% smaller switching ripple...... to provide reactive power support as an ancillary service. For multimegawatt full-scale wind turbines, power capability depends on converter topology and semiconductor switch technology. As power capability limiting factors, switch current, semiconductor junction temperature, and converter output voltage...

  8. Reactive Programming in Java

    CERN Multimedia

    CERN. Geneva

    2017-01-01

    Reactive Programming in gaining a lot of excitement. Many libraries, tools, and frameworks are beginning to make use of reactive libraries. Besides, applications dealing with big data or high frequency data can benefit from this programming paradigm. Come to this presentation to learn about what reactive programming is, what kind of problems it solves, how it solves them. We will take an example oriented approach to learning the programming model and the abstraction.

  9. Development of Reactivity Calculation Code for HANARO

    Energy Technology Data Exchange (ETDEWEB)

    Park, B. G.; Kim, M. S. [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    Reactivity of the reactor core is measured by a multi-channel wide range reactivity computer (or called reactivity meter), which uses current signals from the compensated ion chamber (CIC) mounted on the courtside wall of the reflector tank in the pool [1]. Because there were a few difficulties in operating the reactivity meter in the MS-DOS environment, some researches have been carried out to improve and upgrade it on the Windows environment [2]. Nevertheless, it is still hard for reactor operators to immediately check the time-dependent reactivity in case of power excursion because of some limitations such as aging of devices and compatibility issues. In this study, a simple off-line tool which can estimate the timedependent reactivity by using the fission chamber signals has been developed, and utilized to the case of loose parts of dummy rod in the 86-2th cycles of HANARO. In order to check the reactivity quickly for reactor operators, the inverse kinetic quations have been incorporated, and several useful functions have been implemented to the code. in the case of 86-2th cycles of HANARO, the developed code showed good performance to estimate time dependent reactivity. In the future, the on line analysis modules will be implanted to the code with upgrade of the measrement equipment such as current meters and data acquisition devices. Additionally, reactivity will be estimated by using the reactivity meter in the MS-DOS enviroment, and the new Windows version, for the verification of the developed code.

  10. Photovoltaic power conditioning subsystem: state of the art and development opportunities

    Energy Technology Data Exchange (ETDEWEB)

    Krauthamer, S.; Bahrami, K.; Das, R.; Macie, T.; Rippel, W.

    1984-01-15

    Photovoltaic sytems, the state of the art of power conditioning subsystem components, and the design and operational interaction between photovoltaic systems and hot utilities are detailed in this document. Major technical issues relating to the design and development of power conditioning systems for photovoltaic application are also considered, including: (1) standards, guidelines, and specifications; (2) cost-effective hardware design; (3) impact of advanced components on power conditioning development; (4) protection and safety; (5) quality of power; (6) system efficiency; and (7) system integration with the host utility. In addition, theories of harmonic distortion and reactive power flow are discussed, and information about power conditioner hardware and manufacturers is provided.

  11. Fully Enzymatic Membraneless Glucose|Oxygen Fuel Cell That Provides 0.275 mA cm(-2) in 5 mM Glucose, Operates in Human Physiological Solutions, and Powers Transmission of Sensing Data.

    Science.gov (United States)

    Ó Conghaile, Peter; Falk, Magnus; MacAodha, Domhnall; Yakovleva, Maria E; Gonaus, Christoph; Peterbauer, Clemens K; Gorton, Lo; Shleev, Sergey; Leech, Dónal

    2016-02-16

    Coimmobilization of pyranose dehydrogenase as an enzyme catalyst, osmium redox polymers [Os(4,4'-dimethoxy-2,2'-bipyridine)2(poly(vinylimidazole))10Cl](+) or [Os(4,4'-dimethyl-2,2'-bipyridine)2(poly(vinylimidazole))10Cl](+) as mediators, and carbon nanotube conductive scaffolds in films on graphite electrodes provides enzyme electrodes for glucose oxidation. The recombinant enzyme and a deglycosylated form, both expressed in Pichia pastoris, are investigated and compared as biocatalysts for glucose oxidation using flow injection amperometry and voltammetry. In the presence of 5 mM glucose in phosphate-buffered saline (PBS) (50 mM phosphate buffer solution, pH 7.4, with 150 mM NaCl), higher glucose oxidation current densities, 0.41 mA cm(-2), are obtained from enzyme electrodes containing the deglycosylated form of the enzyme. The optimized glucose-oxidizing anode, prepared using deglycosylated enzyme coimmobilized with [Os(4,4'-dimethyl-2,2'-bipyridine)2(poly(vinylimidazole))10Cl](+) and carbon nanotubes, was coupled with an oxygen-reducing bilirubin oxidase on gold nanoparticle dispersed on gold electrode as a biocathode to provide a membraneless fully enzymatic fuel cell. A maximum power density of 275 μW cm(-2) is obtained in 5 mM glucose in PBS, the highest to date under these conditions, providing sufficient power to enable wireless transmission of a signal to a data logger. When tested in whole human blood and unstimulated human saliva maximum power densities of 73 and 6 μW cm(-2) are obtained for the same fuel cell configuration, respectively.

  12. Microturbine Power Conversion Technology Review

    Energy Technology Data Exchange (ETDEWEB)

    Staunton, R.H.

    2003-07-21

    In this study, the Oak Ridge National Laboratory (ORNL) is performing a technology review to assess the market for commercially available power electronic converters that can be used to connect microturbines to either the electric grid or local loads. The intent of the review is to facilitate an assessment of the present status of marketed power conversion technology to determine how versatile the designs are for potentially providing different services to the grid based on changes in market direction, new industry standards, and the critical needs of the local service provider. The project includes data gathering efforts and documentation of the state-of-the-art design approaches that are being used by microturbine manufacturers in their power conversion electronics development and refinement. This project task entails a review of power converters used in microturbines sized between 20 kW and 1 MW. The power converters permit microturbine generators, with their non-synchronous, high frequency output, to interface with the grid or local loads. The power converters produce 50- to 60-Hz power that can be used for local loads or, using interface electronics, synchronized for connection to the local feeder and/or microgrid. The power electronics enable operation in a stand-alone mode as a voltage source or in grid-connect mode as a current source. Some microturbines are designed to automatically switch between the two modes. The information obtained in this data gathering effort will provide a basis for determining how close the microturbine industry is to providing services such as voltage regulation, combined control of both voltage and current, fast/seamless mode transfers, enhanced reliability, reduced cost converters, reactive power supply, power quality, and other ancillary services. Some power quality improvements will require the addition of storage devices; therefore, the task should also determine what must be done to enable the power conversion circuits to

  13. Alkali-aggregate reactivity (AAR) facts book.

    Science.gov (United States)

    2013-03-01

    This document provides detailed information on alkali-aggregate reactivity (AAR). It primarily discusses alkali-silica reaction (ASR), covering the chemistry, symptoms, test methods, prevention, specifications, diagnosis and prognosis, and mitigation...

  14. Elementary surface processes during reactive magnetron sputtering of chromium

    Energy Technology Data Exchange (ETDEWEB)

    Monje, Sascha; Corbella, Carles, E-mail: carles.corbella@rub.de; Keudell, Achim von [Research Group Reactive Plasmas, Ruhr-University Bochum, Universitystr. 150, 44801 Bochum (Germany)

    2015-10-07

    The elementary surface processes occurring on chromium targets exposed to reactive plasmas have been mimicked in beam experiments by using quantified fluxes of Ar ions (400–800 eV) and oxygen atoms and molecules. For this, quartz crystal microbalances were previously coated with Cr thin films by means of high-power pulsed magnetron sputtering. The measured growth and etching rates were fitted by flux balance equations, which provided sputter yields of around 0.05 for the compound phase and a sticking coefficient of O{sub 2} of 0.38 on the bare Cr surface. Further fitted parameters were the oxygen implantation efficiency and the density of oxidation sites at the surface. The increase in site density with a factor 4 at early phases of reactive sputtering is identified as a relevant mechanism of Cr oxidation. This ion-enhanced oxygen uptake can be attributed to Cr surface roughening and knock-on implantation of oxygen atoms deeper into the target. This work, besides providing fundamental data to control oxidation state of Cr targets, shows that the extended Berg's model constitutes a robust set of rate equations suitable to describe reactive magnetron sputtering of metals.

  15. Analytical Solution for Reactive Solute Transport Considering Incomplete Mixing

    Science.gov (United States)

    Bellin, A.; Chiogna, G.

    2013-12-01

    The laboratory experiments of Gramling et al. (2002) showed that incomplete mixing at the pore scale exerts a significant impact on transport of reactive solutes and that assuming complete mixing leads to overestimation of product concentration in bimolecular reactions. We consider here the family of equilibrium reactions for which the concentration of the reactants and the product can be expressed as a function of the mixing ratio, the concentration of a fictitious non reactive solute. For this type of reactions we propose, in agreement with previous studies, to model the effect of incomplete mixing at scales smaller than the Darcy scale assuming that the mixing ratio is distributed within an REV according to a Beta distribution. We compute the parameters of the Beta model by imposing that the mean concentration is equal to the value that the concentration assumes at the continuum Darcy scale, while the variance decays with time as a power law. We show that our model reproduces the concentration profiles of the reaction product measured in the Gramling et al. (2002) experiments using the transport parameters obtained from conservative experiments and an instantaneous reaction kinetic. The results are obtained applying analytical solutions both for conservative and for reactive solute transport, thereby providing a method to handle the effect of incomplete mixing on multispecies reactive solute transport, which is simpler than other previously developed methods. Gramling, C. M., C. F. Harvey, and L. C. Meigs (2002), Reactive transport in porous media: A comparison of model prediction with laboratory visualization, Environ. Sci. Technol., 36(11), 2508-2514.

  16. Relationship between global indices of reactivity, electrodonating ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 123; Issue 5. Relationship between global indices of reactivity, electrodonating and electroaccepting powers, and the hammet constant in isatoic anhydride derivatives. J S Durand-Niconoff L Cruz-Kuri M H Matus J Correa-Basurto J S Cruz-Sánchez F R Ramos- ...

  17. Nigerian electric power supply quality improvement | Ibe | Scientia ...

    African Journals Online (AJOL)

    Improving the quality of the Nigeria electric power supply means improving voltage, transient and frequency stabilities. Power system voltages are controlled by the reactive power component of the power supply; hence voltage and transient stabilities can be improved by using reactive power compensators to either supply ...

  18. Flows of Reactive Fluids

    CERN Document Server

    Prud'homme, Roger

    2010-01-01

    The modeling of reactive flows has progressed mainly with advances in aerospace, which gave birth to a new science called aerothermochemistry, as well as through developments in chemical and process engineering. The methods employed, the phenomena investigated, and the aims of modeling differ for each field; however, in all cases, the results obtained have considerably enriched the working knowledge of reactive flows. This work examines basic concepts and methods necessary to study reactive flows and transfer phenomena in areas such as fluid mechanics, thermodynamics, and chemistry. Specific topics covered include: * Equations of state * Transfer phenomena and chemical kinetics * Balance equations of reactive flows * Dimensionless numbers and similarity * Chemical reactors * Coupled phenomena * Turbulent flow concepts * Boundary layers and fluid layers * Reactive and nonreactive waves * Interface phenomena * Multiphase flow concepts The book presents tools of interest to graduate students, researchers in math...

  19. A LAIR-1 insertion generates broadly reactive antibodies against malaria variant antigens

    OpenAIRE

    Tan, Joshua; Pieper, Kathrin; Piccoli, Luca; Abdi, Abdirahman; Perez, Mathilde Foglierini; Geiger, Roger; Tully, Claire Maria; Jarrossay, David; Maina Ndungu, Francis; Wambua, Juliana; Bejon, Philip; Fregni, Chiara Silacci; Fernandez-Rodriguez, Blanca; Barbieri, Sonia; Bianchi, Siro

    2015-01-01

    Plasmodium falciparum antigens expressed on the surface of infected erythrocytes are important targets of naturally acquired immunity against malaria, but their high number and variability provide the pathogen with a powerful means of escape from host antibodies 1?4 . Although broadly reactive antibodies against these antigens could be useful as therapeutics and in vaccine design, their identification has proven elusive. Here, we report the isolation of human monoclonal antibodies that recogn...

  20. First OH reactivity measurements in Harvard Forest

    Science.gov (United States)

    Herdlinger-Blatt, I. S.; Martin, S. T.; Hansel, A.; McKinney, K. A.

    2013-12-01

    The OH reactivity provides critical insight into the HOx budget under actual atmospheric conditions, and has implications for the production of ozone and the formation of secondary organic material. Previous studies have indicated that the OH reactivity measured at field sites often exceeds model estimations, but current experiments remain inconclusive about the origin of the discrepancy between the modeled and measured OH reactivity (Lou et al., 2010). As of now there are only a limited number of atmospheric studies of total OH reactivity available, so to improve understanding of the OH reactivity more studies are needed. The first OH reactivity measurements in the northeastern United States are being performed during the summer of 2013 at Harvard Forest. Harvard forest, is located about 100 km west of the Boston metropolitan area, is one of the most intensively studied forests in North America. The main biogenic VOC emitted from Harvard Forest is isoprene followed by monoterpenes and methanol. Sampling for the OH reactivity measurements will be conducted from a 30m tall meteorological tower at the Harvard Forest site. The air is drawn into a reaction cell where the OH reactivity is determined using the Comparative Reactivity Method (Sinha et al., 2008) employing a High-Sensitivity Proton Transfer Reaction Mass Spectrometer (Lindinger et al., 1998, Hansel et al., 1998). In addition to the OH reactivity measurements, the most abundant compounds present in the air sample will be quantified using PTR-MS. The quantification of these compounds is needed to compare the theoretical calculated OH reactivity with the measured OH reactivity data. The measurements will be used to evaluate our understanding of the OH budget at Harvard Forest. References: A. Hansel, A. Jordan, C. Warneke, R. Holzinger, and W. Lindinger.: Improved Detection Limit of the Proton-transfer Reaction Mass Spectrometer: On-line Monitoring of Volatile Organic Compounds at Mixing Ratios of a Few PPTV

  1. Reactive transport modeling of trichloroethene treatment with declining reactivity of iron.

    Science.gov (United States)

    Jeen, Sung-Wook; Mayer, K Ulrich; Gillham, Robert W; Blowes, David W

    2007-02-15

    Evolving reactivity of iron, resulting from precipitation of secondary minerals within iron permeable reactive barriers (PRBs), was included in a reactive transport model for trichloroethene (TCE) treatment. The accumulation of secondary minerals and reactivity loss were coupled using an empirically derived relationship that was incorporated into an existing multicomponent reactive transport code (MIN3P) by modifying the kinetic expressions. The simulation results were compared to the observations from long-term column experiments, which were designed to assess the effects of carbonate mineral formation on the performance of iron for TCE treatment. The model successfully reproduced the evolution of iron reactivity and the dynamic changes in geochemical conditions and contaminant treatment. Predictions under various hydrogeochemical conditions showed that TCE would be treated effectively for an extended period of time without a significant loss of permeability. Although there are improvements yet to be made, this study provides a significant advance in our ability to predict long-term performance of iron PRBs.

  2. COAL SLAGGING AND REACTIVITY TESTING

    Energy Technology Data Exchange (ETDEWEB)

    Donald P. McCollor; Kurt E. Eylands; Jason D. Laumb

    2003-10-01

    Union Fenosa's La Robla I Power Station is a 270-MW Foster Wheeler arch-fired system. The unit is located at the mine that provides a portion of the semianthracitic coal. The remaining coals used are from South Africa, Russia, Australia, and China. The challenges at the La Robla I Station stem from the various fuels used, the characteristics of which differ from the design coal. The University of North Dakota Energy & Environmental Research Center (EERC) and the Lehigh University Energy Research Center (LUERC) undertook a program to assess problematic slagging and unburned carbon issues occurring at the plant. Full-scale combustion tests were performed under baseline conditions, with elevated oxygen level and with redistribution of air during a site visit at the plant. During these tests, operating information, observations and temperature measurements, and coal, slag deposit, and fly ash samples were obtained to assess slagging and unburned carbon. The slagging in almost all cases appeared due to elevated temperatures rather than fuel chemistry. The most severe slagging occurred when the temperature at the sampling port was in excess of 1500 C, with problematic slagging where first-observed temperatures exceeded 1350 C. The presence of anorthite crystals in the bulk of the deposits analyzed indicates that the temperatures were in excess of 1350 C, consistent with temperature measurements during the sampling period. Elevated temperatures and ''hot spots'' are probably the result of poor mill performance, and a poor distribution of the coal from the mills to the specific burners causes elevated temperatures in the regions where the slag samples were extracted. A contributing cause appeared to be poor combustion air mixing and heating, resulting in oxygen stratification and increased temperatures in certain areas. Air preheater plugging was observed and reduces the temperature of the air in the windbox, which leads to poor combustion

  3. Modeling and simulation of reactive flows

    CERN Document Server

    Bortoli, De AL; Pereira, Felipe

    2015-01-01

    Modelling and Simulation of Reactive Flows presents information on modeling and how to numerically solve reactive flows. The book offers a distinctive approach that combines diffusion flames and geochemical flow problems, providing users with a comprehensive resource that bridges the gap for scientists, engineers, and the industry. Specifically, the book looks at the basic concepts related to reaction rates, chemical kinetics, and the development of reduced kinetic mechanisms. It considers the most common methods used in practical situations, along with equations for reactive flows, and va

  4. Reactive Turing machines

    National Research Council Canada - National Science Library

    Baeten, Jos; Luttik, Bas; Tilburg, P.J.A

    2013-01-01

    textabstractWe propose reactive Turing machines (RTMs), extending classical Turing machines with a process-theoretical notion of interaction, and use it to define a notion of executable transition system...

  5. What Is Reactive Arthritis?

    Science.gov (United States)

    ... Information Artritis reactiva: Esenciales: hojas informativas de fácil lectura View/Download/Order Publications Reactive Arthritis, Easy-to- ... Media Moderation Policy FOIA Privacy Statement Accessibility Disclaimer Digital Strategy Open Source Data Public Data Listing NIH... ...

  6. Reactive Attachment Disorder

    Science.gov (United States)

    ... treatment plan Reactive Attachment Disorder and Disinhibited Social Engagement Disorder are serious clinical conditions. However, close and ongoing ... you find Facts for Families © helpful and would like to make good mental health a reality, consider donating to the ...

  7. Taskable Reactive Agent Communities

    National Research Council Canada - National Science Library

    Myers, Karen

    2002-01-01

    The focus of Taskable Reactive Agent Communities (TRAC) project was to develop mixed-initiative technology to enable humans to supervise and manage teams of agents as they perform tasks in dynamic environments...

  8. Reactive sputter deposition

    CERN Document Server

    Mahieu, Stijn

    2008-01-01

    In this valuable work, all aspects of the reactive magnetron sputtering process, from the discharge up to the resulting thin film growth, are described in detail, allowing the reader to understand the complete process. Hence, this book gives necessary information for those who want to start with reactive magnetron sputtering, understand and investigate the technique, control their sputtering process and tune their existing process, obtaining the desired thin films.

  9. Hamming generalized corrector for reactivity calculation

    Energy Technology Data Exchange (ETDEWEB)

    Suescun-Diaz, Daniel; Ibarguen-Gonzalez, Maria C.; Figueroa-Jimenez, Jorge H. [Pontificia Universidad Javeriana Cali, Cali (Colombia). Dept. de Ciencias Naturales y Matematicas

    2014-06-15

    This work presents the Hamming method generalized corrector for numerically resolving the differential equation of delayed neutron precursor concentration from the point kinetics equations for reactivity calculation, without using the nuclear power history or the Laplace transform. A study was carried out of several correctors with their respective modifiers with different time step calculations, to offer stability and greater precision. Better results are obtained for some correctors than with other existing methods. Reactivity can be calculated with precision of the order h{sup 5}, where h is the time step. (orig.)

  10. Power manager and method for managing power

    NARCIS (Netherlands)

    Burchard, A.T.; Kersten, G.; Molnos, A.M.; Milutinovic, A.; Goossens, K.G.W.; Steffens, E.F.M.

    2009-01-01

    A power manager (106) and method for managing the power supplied to an electronic device is provided. Furthermore, a system wherein the power supplied to an electronic device is managed is provided. The power manager (106) is operative to monitor a hardware monitor (104) during a monitoring time

  11. Reactor-Capaсitor Device for Flexible Link Between Non-Synchronous Power Systems

    Directory of Open Access Journals (Sweden)

    Bosneaga V.

    2016-04-01

    Full Text Available In present flexible interconnections for transmission of required active power between different power systems is used, as a rule, so-called DC back-to-back link. The aim of this work is the investigation of proposed reactor-capacitor device for flexible connection of asynchronously alternating current power systems with the same nominal values of frequencies for parallel operation. The reactor-capacitor device was elaborated. The installation develops the idea of controlled reactor alternating current link, and provides reactive power balance in the unit and needed value of the output voltage module. The basic characteristics of reactor-capacitor device for controlled power transmission were investigated. Analytical expressions for device elements parameters were derived. These ensure necessary ratio of voltages modules of linked power systems and reactive power balance of the device at circular output voltage vector rotation for a given load admittance. Obtained parameters ensure constant active power flow between linked asynchronously power systems and device reactive power internal balance.

  12. Neutron fluence effects on SLOWPOKE-2 beryllium reflector composition and reactivity

    Energy Technology Data Exchange (ETDEWEB)

    Puig, Francesc, E-mail: fpuig@anl.gov [Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Dennis, Haile, E-mail: haile.dennis02@uwimona.edu.jm [International Centre for Environmental and Nuclear Sciences, 2 Anguilla Close, University of the West Indies, Mona, Kingston 7 (Jamaica)

    2016-08-15

    Highlights: • SLOWPOKE-2 reflector composition evolution estimated using two different methods. • Reactivity effects of reflector composition changes calculated using MCNP5. • Impurities depletion dominates over poisons buildup, increasing reactivity. • Results contradict previously published behavior estimates for MNSR reactors. • Identified main factors explaining the observed prediction discrepancies. - Abstract: Within the scope of the conversion process from HEU to LEU of the Jamaican SLOWPOKE-2 reactor (JM-1), the effects of the neutron fluence on the beryllium reflector composition, and the corresponding effect on reactivity throughout the life of the reactor core, have been studied. Two different methods have been used and compared involving MCNP5, ORIGEN2.2, ORIGEN-S and COUPLE codes, reaching excellent agreement between them. The neutron flux profile and energy spectrum specific to the beryllium reflectors of this reactor design have been taken into account to analyze several scenarios, comprising both real and hypothetical conditions and involving different initial reflector compositions and reactor burnups. The analysis has been extended to provide estimates for the similar MNSR reactor design and compared with previously published predictions for the Syrian MNSR. The results show small overall reactivity effects in most cases, being dominated by impurity depletion as opposed to poison buildup, contrarily to what generally occurs in beryllium reflected reactors of far higher power and to MNSR predictions. The resulting reactivity increases are typically of less than 0.4 mk for usual impurity levels and maximum HEU core burnup achievable.

  13. Power Service Shops

    Data.gov (United States)

    Federal Laboratory Consortium — TVA's Power Service Shops provides expert repair and maintenance of power system components and large industrial equipment. With world-class maintenance facilities...

  14. Coordinated control for low voltage ride-through of a PMSG-based wind power plant

    Directory of Open Access Journals (Sweden)

    Khagendra Thapa

    2016-01-01

    Full Text Available Wind turbine generators should be kept connected to a power grid, while supporting the voltage recovery in the case of a grid fault to meet low voltage ride-through requirement in some grid codes. This paper proposes a coordinated control scheme that prevents the increase in the DC-link voltage by reducing the active power in the machine side converter of permanent magnet synchronous generators (PMSGs in proportion to the voltage dip at the terminal of PMSGs. The proposed scheme changes the current priorities from the active current to the reactive current to inject more reactive power for a severe fault depending on the voltage dip. In addition, the grid-side converter operates in a voltage control mode with the slope, which is the ratio of reactive current capability to the voltage tolerance around a rated value. Moreover, during the fault, the slope is changed depending on the voltage dip to inject more reactive current. The performance of the proposed scheme is validated for a wind power plant consisting of 20 units of 5-MW PMSGs using an EMTP-RV simulator. The results demonstrate that the scheme enables the PMSGs not only to survive during the fault, but also to provide a dynamic reactive power support.

  15. First reactivity determination of a subcritical reactor using a single beam-trip and fission chambers operating in current mode

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Ordonez, M.; Villamarin, D.; Becares, V.; Gonzalez-Romero, E.M. [Nuclear Innovation Group, CIEMAT, Avda. Complutense, Madrid (Spain); Bergloef, C. [Reactor Physics Department, Royal Institute of Technology, Stockholm (Sweden); Bournos, V.; Fokov, Y.; Kiyavitskaya, H. [Joint Institute for Power and Nuclear Research, National Academy of Sciences, Minsk (Belarus)

    2009-06-15

    Transmutation of spent nuclear fuel in Accelerator-Driven Systems (ADS) is considered as a key technology for achieving sustainable nuclear energy. In the design of future ADS facilities, the reactivity monitoring system is of highest importance. An extensive experimental program devoted to reactivity monitoring of ADS has been carried out at the subcritical facility YALINA-Booster in the framework of IP-EUROTRANS. The main objective, besides the qualification of the reactivity monitoring techniques, has been to develop electronic chains that can be used in a full power ADS. For this purpose, YALINA-Booster couples a D-T neutron generator to a flexible zero-power subcritical assembly with a coupled fast-thermal neutron spectrum. The high intensity of the accelerator and the possibility to work in continuous or pulsed mode allowed the study of the current-to-flux relationship and beam-trip experiments. In addition, the experimental facility provided the opportunity to test electronic chains in current mode, which correspond to the most probable condition in a full power ADS. There exists a relationship between the reactivity of a subcritical core, the intensity of the accelerator and the neutron source intensity. Hence, by monitoring these three quantities it should be possible to determine the origin of any reactivity or power change within the subcritical assembly. We have developed the necessary acquisition system to monitor the conditions of these three variables in the millisecond scale. The current-to-flux technique provides relative changes in the behavior of the core, however, in order to determine absolute values of the reactivity, we have taken profit of short imposed beam interruptions in the millisecond scale, thus providing the possibility for applying the Source-Jerk method within few milliseconds. It is the first time that the reactivity of an ADS is determined in a single beam-trip using fission chambers operating in current mode. The experiments

  16. The effect of exercise training on cutaneous microvascular reactivity: A systematic review and meta-analysis.

    Science.gov (United States)

    Lanting, Sean M; Johnson, Nathan A; Baker, Michael K; Caterson, Ian D; Chuter, Vivienne H

    2017-02-01

    This study aimed to review the efficacy of exercise training for improving cutaneous microvascular reactivity in response to local stimulus in human adults. Systematic review with meta-analysis. A systematic search of Medline, Cinahl, AMED, Web of Science, Scopus, and Embase was conducted up to June 2015. Included studies were controlled trials assessing the effect of an exercise training intervention on cutaneous microvascular reactivity as instigated by local stimulus such as local heating, iontophoresis and post-occlusive reactive hyperaemia. Studies where the control was only measured at baseline or which included participants with vasospastic disorders were excluded. Two authors independently reviewed and selected relevant controlled trials and extracted data. Quality was assessed using the Downs and Black checklist. Seven trials were included, with six showing a benefit of exercise training but only two reaching statistical significance with effect size ranging from -0.14 to 1.03. The meta-analysis revealed that aerobic exercise had a moderate statistically significant effect on improving cutaneous microvascular reactivity (effect size (ES)=0.43, 95% CI: 0.08-0.78, p=0.015). Individual studies employing an exercise training intervention have tended to have small sample sizes and hence lacked sufficient power to detect clinically meaningful benefits to cutaneous microvascular reactivity. Pooled analysis revealed a clear benefit of exercise training on improving cutaneous microvascular reactivity in older and previously inactive adult cohorts. Exercise training may provide a cost-effective option for improving cutaneous microvascular reactivity in adults and may be of benefit to those with cardiovascular disease and metabolic disorders such as diabetes. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  17. Optimal Power Flow Pursuit

    Energy Technology Data Exchange (ETDEWEB)

    Dall' Anese, Emiliano

    2016-08-01

    Past works that focused on addressing power-quality and reliability concerns related to renewable energy resources (RESs) operating with business-as-usual practices have looked at the design of Volt/VAr and Volt/Watt strategies to regulate real or reactive powers based on local voltage measurements, so that terminal voltages are within acceptable levels. These control strategies have the potential of operating at the same time scale of distribution-system dynamics, and can therefore mitigate disturbances precipitated fast time-varying loads and ambient conditions; however, they do not necessarily guarantee system-level optimality, and stability claims are mainly based on empirical evidences. On a different time scale, centralized and distributed optimal power flow (OPF) algorithms have been proposed to compute optimal steady-state inverter setpoints, so that power losses and voltage deviations are minimized and economic benefits to end-users providing ancillary services are maximized. However, traditional OPF schemes may offer decision making capabilities that do not match the dynamics of distribution systems. Particularly, during the time required to collect data from all the nodes of the network (e.g., loads), solve the OPF, and subsequently dispatch setpoints, the underlying load, ambient, and network conditions may have already changed; in this case, the DER output powers would be consistently regulated around outdated setpoints, leading to suboptimal system operation and violation of relevant electrical limits. The present work focuses on the synthesis of distributed RES-inverter controllers that leverage the opportunities for fast feedback offered by power-electronics interfaced RESs. The overarching objective is to bridge the temporal gap between long-term system optimization and real-time control, to enable seamless RES integration in large scale with stability and efficiency guarantees, while congruently pursuing system-level optimization objectives. The

  18. Wind Turbine Providing Grid Support

    DEFF Research Database (Denmark)

    2011-01-01

    A variable speed wind turbine is arranged to provide additional electrical power to counteract non-periodic disturbances in an electrical grid. A controller monitors events indicating a need to increase the electrical output power from the wind turbine to the electrical grid. The controller...

  19. Reactivity Measurement and Analysis System (RMAS-7)

    Energy Technology Data Exchange (ETDEWEB)

    Cordero, D.; Izquierdo, J.

    2015-07-01

    This paper tries to describe the Reactivity Measurement and Analysis System 7 (RMAS-7), which is an Areva’s hardware and software solution capable of accomplishing the physic startup tests in a work shift. RMAS-7 is a modular solution designed to be a powerful, convenient data collection and analysis system based on Ethernet communication network. This last feature allows RMAS-7 to have a distributed architecture. (Author)

  20. Modeling of SPERT IV Reactivity Initiated Transient Tests in EUREKA-2/RR Code

    Directory of Open Access Journals (Sweden)

    N. H. Badrun

    2014-01-01

    Full Text Available EUREKA-2/RR code has been used for SPERT IV reactor benchmark calculations against the experimental results provided by IAEA (International Atomic Energy Agency obtained for a series of transient tests initiated by step insertion of different magnitudes of positive reactivity with varying degrees of different controlled parameters such as reactor initial power, coolant temperature and coolant flow condition. 20 out of 39 tests that fall under forced convection mode have been considered for the present simulation provided the reactor scram system is disabled. Peak power and peak clad temperature due to transient have been calculated and it was found that although peak clad temperature values agreed, the peak power values seem to underestimate the experimental values. Further study appears to be needed to identify the limitations in modeling or examining the effect of input parameters during modeling to obtain the better simulation results.

  1. Clojure reactive programming

    CERN Document Server

    Borges, Leonardo

    2015-01-01

    If you are a Clojure developer who is interested in using Reactive Programming to build asynchronous and concurrent applications, this book is for you. Knowledge of Clojure and Leiningen is required. Basic understanding of ClojureScript will be helpful for the web chapters, although it is not strictly necessary.

  2. Optimization of reactive mufflers

    Science.gov (United States)

    Komkin, A. I.

    2010-05-01

    A new approach to optimization of reactive mufflers, which is based on use of muffler prototype with nondimensional geometrical parameters and integral criterion of acoustic performance of mufflers, is proposed. Implementation of the approach using the example of chamber mufflers is considered.

  3. Chemical reactivities of bleomycin.

    Science.gov (United States)

    Padbury, G; Sligar, S S

    1985-07-05

    Ferric bleomycin was tested for its ability to catalyze a set of six oxidative reactions characteristic of the heme-containing proteins, cytochrome P-450 and chloroperoxidase. These reactions included peroxyacid decarboxylation and aliphatic hydroxylation as typical cytochrome P-450 chemistries. Peroxyacid-supported oxygen evolution and hydrogen peroxide-mediated chlorination were utilized as characteristic chloroperoxidase reactivities. A typical peroxidative reaction and heteroatom dealkylation, common to both O2 activating enzymes, were also studied. Bleomycin was found to catalyze peroxidation of o-dianisidine. The ferric drug complex was found competent in carrying out N-demethylation of N,N-dimethylaniline when peroxides or peroxyacids or iodosobenzene were used as the oxidants. N-Demethylation was not achieved when N,N-dimethylaniline-N-oxide was substituted as the oxidant under similar conditions. Hydroxylation of cumene and decarboxylation of phenylperacetic acid were not found to be catalyzed by bleomycin. Oxygen evolution from m-chloroperbenzoic acid and chlorination of monochlorodimedone from chloride ion and hydrogen peroxide were found to be catalyzed by bleomycin. Cytochrome P-450cam was also evaluated for O2 evolution, and halogenation activity and was found not to demonstrate such reactivities. The results of this initial survey, along with those of previous studies, appear to indicate that the chemical reactivity of bleomycin can be more closely aligned with the reactivities demonstrated by chloroperoxidase than those of cytochrome P-450.

  4. Reactive Turing machines

    NARCIS (Netherlands)

    J.C.M. Baeten (Jos); S.P. Luttik (Bas); P.J.A. van Tilburg

    2013-01-01

    textabstractWe propose reactive Turing machines (RTMs), extending classical Turing machines with a process-theoretical notion of interaction, and use it to define a notion of executable transition system. We show that every computable transition system with a bounded branching degree is simulated

  5. Hydroxyquinones: Synthesis and Reactivity

    Directory of Open Access Journals (Sweden)

    Spyros Spyroudis

    2000-12-01

    Full Text Available Quinones having hydroxy groups directly attached to the quinone ring constitute a very interesting class of quinoid compounds. A great number of hydroxyquinones are found in nature and the majority of them exhibit unique biological activity. Their syntheses and their main reactivity patterns are reviewed in this paper.

  6. Chemical Reactivity Test (CRT)

    Energy Technology Data Exchange (ETDEWEB)

    Zaka, F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-12-13

    The Chemical Reactivity Test (CRT) is used to determine the thermal stability of High Explosives (HEs) and chemical compatibility between (HEs) and alien materials. The CRT is one of the small-scale safety tests performed on HE at the High Explosives Applications Facility (HEAF).

  7. Applications of the Conceptual Density Functional Theory Indices to Organic Chemistry Reactivity.

    Science.gov (United States)

    Domingo, Luis R; Ríos-Gutiérrez, Mar; Pérez, Patricia

    2016-06-09

    Theoretical reactivity indices based on the conceptual Density Functional Theory (DFT) have become a powerful tool for the semiquantitative study of organic reactivity. A large number of reactivity indices have been proposed in the literature. Herein, global quantities like the electronic chemical potential μ, the electrophilicity ω and the nucleophilicity N indices, and local condensed indices like the electrophilic P k + and nucleophilic P k - Parr functions, as the most relevant indices for the study of organic reactivity, are discussed.

  8. Abiotic/biotic coupling in the rhizosphere: a reactive transport modeling analysis

    Science.gov (United States)

    Lawrence, Corey R.; Steefel, Carl; Maher, Kate

    2014-01-01

    A new generation of models is needed to adequately simulate patterns of soil biogeochemical cycling in response changing global environmental drivers. For example, predicting the influence of climate change on soil organic matter storage and stability requires models capable of addressing complex biotic/abiotic interactions of rhizosphere and weathering processes. Reactive transport modeling provides a powerful framework simulating these interactions and the resulting influence on soil physical and chemical characteristics. Incorporation of organic reactions in an existing reactive transport model framework has yielded novel insights into soil weathering and development but much more work is required to adequately capture root and microbial dynamics in the rhizosphere. This endeavor provides many advantages over traditional soil biogeochemical models but also many challenges.

  9. EVALUATION OF THE APPLICABLE REACTIVITY RANGE OF A REACTIVITY COMPUTER FOR A CANDU-6 REACTOR

    Directory of Open Access Journals (Sweden)

    EUN KI LEE

    2014-04-01

    Full Text Available Recently, a CANDU digital reactivity computer system (CDRCS to measure the worth of the liquid zone controller in a CANDU-6 was developed and successfully applied to a physics test of refurbished Wolsong Unit 1. In advance of using the CDRCS, its measureable reactivity range should be investigated and confirmed. There are two reasons for this investigation. First, the CANDU-6 has a larger reactor and smaller excore detectors than a general PWR and consequently the measured reactivity is likely to reflect the peripheral power variation only, not the whole core. The second reason is photo neutrons generated from the interaction of the moderator and gamma-rays, which are never considered in a PWR. To evaluate the limitations of the CDRCS, several tens of three-dimensional steady and transient simulations were performed. The simulated detector signals were used to obtain the dynamic reactivity. The difference between the dynamic reactivity and the static worth increases in line with the water level changes. The maximum allowable reactivity was determined to be 1.4 mk in the case of CANDU-6 by confining the difference to less than 1%.

  10. Electrical Power Converter

    NARCIS (Netherlands)

    Ferreira, J.A.

    2014-01-01

    Electrical power converter for converting electrical power of a power source connected or connectable at an input to electrical DC-power at an output, wherein between the input and the output a first circuit of submodules is provided, wherein said first circuit of submodules and the power source

  11. Cluster Control of Offshore Wind Power Plants Connected to a Common HVDC Station

    DEFF Research Database (Denmark)

    Göksu, Ömer; Sakamuri, Jayachandra N.; Rapp, C. Andrea

    2016-01-01

    In this paper a coordinated control for cluster of offshore WPPs connected to the same HVDC connection is being implemented and analyzed. The study is targeting two cases as; coordination of reactive power flow between HVDC converter and the WPP cluster while providing offshore AC grid voltage co...

  12. Comparison of Standards and Technical Requirements of Grid-Connected Wind Power Plants in China and the United States

    Energy Technology Data Exchange (ETDEWEB)

    Gao, David Wenzhong [Alternative Power Innovations, LLC; Muljadi, Eduard [National Renewable Energy Lab. (NREL), Golden, CO (United States); Tian, Tian [National Renewable Energy Lab. (NREL), Golden, CO (United States); Miller, Mackay [National Renewable Energy Lab. (NREL), Golden, CO (United States); Wang, Weisheng [China Electric Power Research Inst. (China)

    2016-09-01

    The rapid deployment of wind power has made grid integration and operational issues focal points in industry discussions and research. Compliance with grid connection standards for wind power plants (WPPs) is crucial to ensuring the reliable and stable operation of the electric power grid. This report compares the standards for grid-connected WPPs in China to those in the United States to facilitate further improvements in wind power standards and enhance the development of wind power equipment. Detailed analyses of power quality, low-voltage ride-through capability, active power control, reactive power control, voltage control, and wind power forecasting are provided to enhance the understanding of grid codes in the two largest markets of wind power. This study compares WPP interconnection standards and technical requirements in China to those in the United States.

  13. Reactive dispersive contaminant transport in coastal aquifers: Numerical simulation of a reactive Henry problem

    KAUST Repository

    Nick, H.M.

    2013-02-01

    The reactive mixing between seawater and terrestrial water in coastal aquifers influences the water quality of submarine groundwater discharge. While these waters come into contact at the seawater groundwater interface by density driven flow, their chemical components dilute and react through dispersion. A larger interface and wider mixing zone may provide favorable conditions for the natural attenuation of contaminant plumes. It has been claimed that the extent of this mixing is controlled by both, porous media properties and flow conditions. In this study, the interplay between dispersion and reactive processes in coastal aquifers is investigated by means of numerical experiments. Particularly, the impact of dispersion coefficients, the velocity field induced by density driven flow and chemical component reactivities on reactive transport in such aquifers is studied. To do this, a hybrid finite-element finite-volume method and a reactive simulator are coupled, and model accuracy and applicability are assessed. A simple redox reaction is considered to describe the degradation of a contaminant which requires mixing of the contaminated groundwater and the seawater containing the terminal electron acceptor. The resulting degradation is observed for different scenarios considering different magnitudes of dispersion and chemical reactivity. Three reactive transport regimes are found: reaction controlled, reaction-dispersion controlled and dispersion controlled. Computational results suggest that the chemical components\\' reactivity as well as dispersion coefficients play a significant role on controlling reactive mixing zones and extent of contaminant removal in coastal aquifers. Further, our results confirm that the dilution index is a better alternative to the second central spatial moment of a plume to describe the mixing of reactive solutes in coastal aquifers. © 2012 Elsevier B.V.

  14. Distributed Generation Units as Ancillary Services Providers in a Pre Smart Grid Environment

    Science.gov (United States)

    Donadel, Clainer Bravin; Fardin, Jussara Farias; Encarnação, Lucas Frizera

    2017-10-01

    Nowadays, ancillary services in electrical distribution networks (e. g. voltage support and reactive power control), usually provided by capacitor banks, start to be performed by distributed generation units (DGs). In this way, several papers have been studying the use of DGs as reactive power providers, and the power electronic/market regulation involved in this new scenario. However, the authors commonly consider a full implementation of Smart Grid philosophy, i. e., there are appropriate communications between DGs and distribution network operator (DNO)'s control centers, but it is not a close reality in many developing countries, due to high costs involved in their implementation. Therefore, this paper proposes a new method in order to use DGs as ancillary services providers in a short and medium-term (called in the literature Pre Smart Grid), in which there are not effective communications between DGs and control centers of DNOs. The proposed method uses a non-uniform DGs distribution, obtained from local atlas of wind, solar, hydraulic and biomass power. The methodology presented accurate results when compared with a PSO-based method, widely used to solve optimization problems, but needs a complete Smart Grid philosophy implementation to work.

  15. Treatment of dyeing wastewater including reactive dyes (Reactive ...

    African Journals Online (AJOL)

    2013-08-15

    Aug 15, 2013 ... Treatment of dyeing wastewater including reactive dyes. (Reactive Red RB, Reactive Black B, ... Keywords: Rhizopus arrhizus, wastewater treatment, decolourisation, textile dye. INTRODUCTION. Dyeing effluents ... as bacteria, yeasts, algae and fungi, are able to remove differ- ent classes of dyes (Fu and ...

  16. Treatment of dyeing wastewater including reactive dyes (Reactive ...

    African Journals Online (AJOL)

    The decolourisation potential of growing Rhizopus arrhizus fungal strain in liquid medium containing thiamine was investigated for the removal of anionic reactive dyes such as Reactive Red RB (RR), Reactive Black B (RBB) and Remazol Blue (RB) and a cationic basic dye Methylene Blue (MB). To determine the optimal ...

  17. The Effect of Information Access Strategy on Power Consumption and Reliability in Wireless Sensor Network

    DEFF Research Database (Denmark)

    Tobgay, Sonam; Olsen, Rasmus Løvenstein; Prasad, Ramjee

    2013-01-01

    This paper examines the effect of different information access strategies on power consumption and information reliability, considering the wireless sensor network as the source of information. Basically, the paper explores three different access strategies, namely; reactive, periodic and hybrid...... and computes power consumption and mismatch probability [1] in each of these access strategies. Based on our study, we make some recommendations when and where, which access strategy is suitable depending upon the application's requirements and network behavior. It also provides the model implementation...

  18. Changes in reactivity and in the margins to thermal limits by the inclusion of control rods of advanced type in the Laguna Verde Power plant; Cambios en la reactividad y en los margenes a limites termicos por la inclusion de barras de control de tipo avanzado en la Central Laguna Verde

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez, J.L.; Perusquia, R.; Montes, J.L.; Ortiz, J.J.; Ramirez, J.R. [ININ, Depto. de Sistemas Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)]. E-mail: jlhm@nuclear.inin.mx

    2004-07-01

    The obtained results are presented when simulating with CM-PRESTO code the cycle 10 of the unit 1 of the Laguna Verde Central, using two advanced types of control bars, besides the originally loaded ones. The two advanced types, to those that are denominated 1AV and 2AV in this work, are of different design, however both have in some place of the bar, a section with hafnium like neutron absorber material. They thought about three different scenarios, in the first one, used as reference, is simulated the cycle 10 using the original control bars, while in the other two cases the advanced types are used. The values of the reactivity were compared and of some margins to the thermal limits obtained when using the bars of advanced type, with those obtained in the case in that alone they are considered those original bars. It was found that in condition of power both advanced types present bigger absorber power of neutrons that the original bars, being quantified in average this bigger power in 0.22 pcm/notch for the type 1AV and in 0.51 pcm/notch for the type 2AV. The affectation of the margins to the observed thermal limits is minimum. (Author)

  19. Power Flow Analysis Algorithm for Islanded LV Microgrids Including Distributed Generator Units with Droop Control and Virtual Impedance Loop

    DEFF Research Database (Denmark)

    Li, Chendan; Chaudhary, Sanjay; Vasquez, Juan Carlos

    2014-01-01

    In this paper, an improved power flow analysis algorithm for distributed generation (DG) units controlled with P/Q droop functions and virtual impedances in a low voltage (LV) microgrid is proposed. The proposed analysis provides in contrast to conventional power flow calculation techniques: (i......) consideration of virtual impedance parameters and (ii) higher accuracy in reactive power flow calculation. The improved power flow analysis algorithm proposed in this paper is validated by comparing the calculation results with detailed time domain simulation results. Case studies have been carried out...... by analyzing the effects of control parameter variation in the power flow results obtained by the proposed algorithm....

  20. Reactivation System for Proton-Exchange Membrane Fuel-Cells

    Directory of Open Access Journals (Sweden)

    Roberto Giral

    2012-07-01

    Full Text Available In recent years, Proton-Exchange Membrane Fuel Cells (PEMFCs have been the focus of very intensive researches. Manufacturers of these alternative power sources propose a rejuvenation sequence after the FC has been operating at high power for a certain period of time. These rejuvenation methods could be not appropriate for the reactivation of the FC when it has been out of operation for a long period of time or after it has been repaired. Since the developed reactivation system monitors temperature, current, and the cell voltages of the stack, it could be also useful for the diagnostic and repairing processes. The limited number of published contributions suggests that systems developing reactivation techniques are an open research field. In this paper, an automated system for reactivating PEMFCs and results of experimental testing are presented.

  1. Combined short and long term rating of static Var system components for steady state and transient voltage support in a 500 kV power grid

    Energy Technology Data Exchange (ETDEWEB)

    Paulsson, L.; Silva, A.; Thorvaldsson, B. [ABB Power Systems AB, Vaesteraas (Sweden); Gonzalez, R. [Northern States Power Co., Minneapolis, MN (United States)

    1994-12-31

    One efficient way to improve the power transmission performance is to provide appropriate reactive power balance and control in the network. Reactive power compensation by means of static var compensation (SVC) and series compensation (SC) are well established ways to achieve such improvement. The SVC, which is a relatively new concept, has now been used successfully for more than 15 years in EHV systems. This paper discusses a more general type of shunt compensation, designated Static var System (SVS), which may include breaker switched capacitor banks and other special features besides conventional SVC technology. (author) 4 figs.

  2. Episodic Memory Retrieval Functionally Relies on Very Rapid Reactivation of Sensory Information.

    Science.gov (United States)

    Waldhauser, Gerd T; Braun, Verena; Hanslmayr, Simon

    2016-01-06

    Episodic memory retrieval is assumed to rely on the rapid reactivation of sensory information that was present during encoding, a process termed "ecphory." We investigated the functional relevance of this scarcely understood process in two experiments in human participants. We presented stimuli to the left or right of fixation at encoding, followed by an episodic memory test with centrally presented retrieval cues. This allowed us to track the reactivation of lateralized sensory memory traces during retrieval. Successful episodic retrieval led to a very early (∼100-200 ms) reactivation of lateralized alpha/beta (10-25 Hz) electroencephalographic (EEG) power decreases in the visual cortex contralateral to the visual field at encoding. Applying rhythmic transcranial magnetic stimulation to interfere with early retrieval processing in the visual cortex led to decreased episodic memory performance specifically for items encoded in the visual field contralateral to the site of stimulation. These results demonstrate, for the first time, that episodic memory functionally relies on very rapid reactivation of sensory information. Remembering personal experiences requires a "mental time travel" to revisit sensory information perceived in the past. This process is typically described as a controlled, relatively slow process. However, by using electroencephalography to measure neural activity with a high time resolution, we show that such episodic retrieval entails a very rapid reactivation of sensory brain areas. Using transcranial magnetic stimulation to alter brain function during retrieval revealed that this early sensory reactivation is causally relevant for conscious remembering. These results give first neural evidence for a functional, preconscious component of episodic remembering. This provides new insight into the nature of human memory and may help in the understanding of psychiatric conditions that involve the automatic intrusion of unwanted memories. Copyright

  3. Improved Real-Power Loss Minimisation | Ekwue | Nigerian Journal ...

    African Journals Online (AJOL)

    The problem of the reactive control of a power system is formulated as a static optimisation technique to ensure the minimisation of the real-power system losses by controlling the switchable reactive power sources, generator terminal voltages, transformer tap ratios and phase shiftet's. The objective function as well as the ...

  4. Consistency of heart rate and sympathovagal reactivity across different autonomic contexts.

    Science.gov (United States)

    Sloan, R P; Shapiro, P A; Bagiella, E; Fishkin, P E; Gorman, J M; Myers, M M

    1995-09-01

    Theories that psychophysiological reactivity constitutes a risk factor for coronary artery disease assume that reactivity is a consistent individual characteristic. We tested this assumption by measuring reactivity to three psychologically challenging tasks performed by 22 healthy subjects across different autonomic contexts produced by positional change. Dependent variables included heart rate (HR), low-frequency (LF; 0.04-0.15 Hz) and high-frequency (HF; 0.15-0.50 Hz) heart period variability, and the LF/HF ratio. HR (r = .44, p < .05) and LF/HF ratio (r = .48, p = .03) reactivity were modestly correlated across the different autonomic contexts, but HF and LF power reactivity were not. These findings suggest that HR reactivity to psychological challenge is a modestly consistent characteristic of individuals, despite differences in autonomic context. Although the same is true of cardiac sympathovagal balance, reactivity of HF and LF power were less consistent.

  5. Programming Reactive Extensions and LINQ

    CERN Document Server

    Liberty, Jesse

    2011-01-01

    Pro Reactive Extensions and LINQ is a deep dive into the next important technology for .NET developers: Reactive Extensions. This in-depth tutorial goes beyond what is available anywhere else to teach how to write WPF, Silverlight, and Windows Phone applications using the Reactive Extensions (Rx) to handle events and asynchronous method calls. Reactive programming allows you to turn those aspects of your code that are currently imperative into something much more event-driven and flexible. For this reason, it's sometimes referred to as LINQ for Events. Reactive programming hinges on the concep

  6. Towards a quantitative understanding of total OH reactivity: A review

    Science.gov (United States)

    Yang, Yudong; Shao, Min; Wang, Xuemei; Nölscher, Anke C.; Kessel, Stephan; Guenther, Alex; Williams, Jonathan

    2016-06-01

    Over the past fifty years, considerable efforts have been devoted to measuring the concentration and chemical speciation of volatile organic compounds (VOCs) in ambient air and emissions. Recently, it has become possible to directly determine the overall effect of atmospheric trace gases on the oxidant hydroxyl radicals (OH), by measuring OH reactivity (OH loss frequency). Quantifying total OH reactivity is one way to characterize the roles of VOCs in formation of ground-level ozone and secondary organic aerosols (SOA). Approaches for measuring total OH reactivity in both emissions and ambient air have been progressing and have been applied in a wide range of studies. Here we evaluate the main techniques used to measure OH reactivity, including two methods directly measuring OH decay and one comparative reactivity method (CRM), and summarize the existing experimental and modeling studies. Total OH reactivity varies significantly on spatial, diurnal, seasonal and vertical bases. Comparison with individually detected OH sinks often reveals a significant missing reactivity, ranging from 20% to over 80% in some environments. Missing reactivity has also been determined in most source emission studies. These source measurements, as well as numerical models, have indicated that both undetected primary emissions and unmeasured secondary products could contribute to missing reactivity. A quantitative understanding of total OH reactivity of various sources and ambient environments will enhance our understanding of the suite of compounds found in emissions as well as chemical processes, and will also provide an opportunity for the improvement of atmospheric chemical mechanisms.

  7. A Comparative Study of the Application of FACTS Devices in Wind Power Plants of the Southeast Area of the Mexican Electric System

    Energy Technology Data Exchange (ETDEWEB)

    Beltran-Valle, Omar; Pena-Gallardo, Rafael; Segundo-Ramirez, Juan; Muljadi, Eduard

    2017-01-26

    This paper presents a comparative study of the application of Flexible AC Transmission System (FACTS) devices, as Thyristor Controlled Series Capacitor (TCSC), Static Synchronous Compensator (STATCOM) and Unified Power Controller (UPFC) on congestion management and voltage support in the area of the Istmo of Tehuantepec, Oaxaca, Mexico. The present work provides an analysis about the performance of the control of active and reactive power of the FACTS controllers applied to mentioned problems in the power system.

  8. Targeted Memory Reactivation during Sleep Depends on Prior Learning

    Science.gov (United States)

    Creery, Jessica D.; Oudiette, Delphine; Antony, James W.; Paller, Ken A.

    2015-01-01

    Study Objectives: When sounds associated with learning are presented again during slow-wave sleep, targeted memory reactivation (TMR) can produce improvements in subsequent location recall. Here we used TMR to investigate memory consolidation during an afternoon nap as a function of prior learning. Participants: Twenty healthy individuals (8 male, 19–23 y old). Measurements and Results: Participants learned to associate each of 50 common objects with a unique screen location. When each object appeared, its characteristic sound was played. After electroencephalography (EEG) electrodes were applied, location recall was assessed for each object, followed by a 90-min interval for sleep. During EEG-verified slow-wave sleep, half of the sounds were quietly presented over white noise. Recall was assessed 3 h after initial learning. A beneficial effect of TMR was found in the form of higher recall accuracy for cued objects compared to uncued objects when pre-sleep accuracy was used as an explanatory variable. An analysis of individual differences revealed that this benefit was greater for participants with higher pre-sleep recall accuracy. In an analysis for individual objects, cueing benefits were apparent as long as initial recall was not highly accurate. Sleep physiology analyses revealed that the cueing benefit correlated with delta power and fast spindle density. Conclusions: These findings substantiate the use of targeted memory reactivation (TMR) methods for manipulating consolidation during sleep. TMR can selectively strengthen memory storage for object-location associations learned prior to sleep, except for those near-perfectly memorized. Neural measures found in conjunction with TMR-induced strengthening provide additional evidence about mechanisms of sleep consolidation. Citation: Creery JD, Oudiette D, Antony JW, Paller KA. Targeted memory reactivation during sleep depends on prior learning. SLEEP 2015;38(5):755–763. PMID:25515103

  9. Application of Voltage-regulating and Phaseshifting Transformers to Control Power Flows in the Power System

    Directory of Open Access Journals (Sweden)

    Maksymilian Przygrodzki

    2015-12-01

    Full Text Available Transmission system performance results from, among other factors, the use of devices for electricity transmission and transformation. Proper operation and control of these devices allows maintaining proper electricity parameters and the continuous supply to end consumers. In the group of electricity transforming devices transformers can be distinguished by the ability to control both the magnitude and phase angle of voltage. In this way transmission system state parameters are adjusted, which enable selecting the reactive and active power. On the one hand, these are devices of a complex structure, resulting in difficult operating conditions, while on the other hand they provide a potential opportunity to influence the power flow (including active power in power grids. This article presents the idea of voltage and phase regulation and a transformer regulating unit model. Using the transformer unit’s grid model power analyses were conducted with a focus on evaluating load flow control capabilities. The results of the calculations for the selected transformer unit are presented.active power in power grids. This article presents the idea of voltage and phase regulation and a transformer regulating unit model. Using the transformer unit’s grid model power analyses were conducted with a focus on evaluating load flow control capabilities. The results of the calculations for the selected transformer unit are presented.

  10. Lunar solar-power system: Commerical power

    Science.gov (United States)

    Criswell, David R.

    1995-01-01

    The proposed Lunar Solar-Power (LSP) System collects solar power on the moon. The power is converted to beams of microwaves and transmitted to fields of microwave receivers (rectennas) on Earth that provide electric power to local and regional power grids. LSP can provide abundant and low cost energy to Earth to sustain several centuries of economic development on Earth and in space. The LSP power is independent of the biosphere (global warming, weather, and climate changes), independent of reserves of terrestrial non-renewable and renewable power, and is low in total costs compared to other large scale power systems. Efficient utilization of the moon as a platform for solar collectors/power transmitters and as a source of building materials is key to the development and emplacement of the LSP System. LSP development costs can be significantly reduced by the establishment of a manned lunar base.

  11. A Universal Reactive Machine

    DEFF Research Database (Denmark)

    Andersen, Henrik Reif; Mørk, Simon; Sørensen, Morten U.

    1997-01-01

    Turing showed the existence of a model universal for the set of Turing machines in the sense that given an encoding of any Turing machine asinput the universal Turing machine simulates it. We introduce the concept of universality for reactive systems and construct a CCS processuniversal...... in the sense that, given an encoding of any CCS process, it behaves like this process up to weak bisimulation. This construction has arather non-constructive use of silent actions and we argue that this would be the case for any universal CCS process....

  12. ORIGINAL ARTICLES Potential impact of reactive vaccination in ...

    African Journals Online (AJOL)

    and debate regarding reactive vaccination to control cholera outbreaks. It provides insights into the practical challenges that might be associated with reactive vaccination and the potential value of the intervention, and suggests areas of future study. The Zimbabwe cholera outbreak is considered to be over. However,.

  13. Reactivity Monitoring of Accelerator-Driven Nuclear Reactor Systems

    NARCIS (Netherlands)

    Uyttenhove, W.

    2016-01-01

    This thesis provides a methodology and set-up of a reactivity monitoring tool for Accelerator-Driven Systems (ADS). The reactivity monitoring tool should guarantee the operation of an ADS at a safe margin from criticality. Robustness is assured in different aspects of the monitoring tool: the choice

  14. Permanent Magnet Synchronous Condenser for Wind Power Plant Grid Connection Support: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, P.; Muljadi, E.

    2015-04-03

    A synchronous condenser (SC) using a permanent magnet synchronous generator (PMSG) is proposed for providing necessary reactive power to a wind power plant to support its connection to a weak grid. A PMSG has the advantage of higher efficiency and reliability. Because of its lack of a field winding, a PMSG is typically controlled by a full-power converter, which can be costly. In the proposed system, the reactive power of the SC is controlled by a serially connected compensator operating in a closed-loop configuration. The compensator also damps the PMSG's tendency to oscillate. The compensator's VA rating is only a fraction of the rating of the SC and the PMSG. In this initial investigation, the proposed scheme is shown to be effective by computer simulations.

  15. Reactivation of small hydroelectric power plant St. Marienthal Monastery, Ostritz. Final report from the 2nd part from planning to achievement; Reaktivierung der Wasserkraftanlage des Klosterstiftes St. Marienthal, Ostritz. Abschlussbericht zum zweiten Teil fuer die Bearbeitungsphasen der Projektierung bis zur Fertigstellung

    Energy Technology Data Exchange (ETDEWEB)

    Hesse, M.

    2001-07-01

    The hydroelectric power plant St. Marienthal Monastery on the river Lausitzer Neisse, which forms part of the border between Poland and Germany, was rehabilitated and modernized in the period between October 1999 and September 2000. The scheme to reactivate this plant was implemented as an external EXPO 2000 project for renewable energy production and sustainable management. On 6 October 2000, the hydroelectric power plant was officially put back into operation by Steffen Flath, Minister for the Environment and Agriculture in the German state of Saxony. The paper describes the special planning factors involved and the execution of construction work. (orig.) [German] Wiederbelebung der 1967 eingestellten Stromerzeugung bei weit hoeherer Effizienz unter Beibehaltung der oertlichen Gegebenheiten, die von den Rahmenbedingungen des Denkmalschutzes vorgegeben werden. Verzicht auf tiefe Eingriffe in den Unterlauf des Flusses, der durch Brueckentruemmer des zweiten Weltkrieges im Ablauf Stoerungen zeigt. Trotz hoeherer Wasserentnahme als bei der historischen Anlage soll die Durchgaengigkeit fuer Fische mittels einer Fischtreppe garantiert werden. Ziel ist es, das Kloster selbst und das auf seinem Territorium eingerichtete Internationale Begenungszentrum St. Marienthal vom Jahresertrag her selbst zu versorgen und ueberschuessigen Strom in das Netz der Energieversorgung Sachsen Ost AG einzuspeisen. Die Besonderheit dieser Anlage besteht darin, schon bestehende Bauwerke wieder zu nutzen, die erzeugte Energie zu demonstrieren, messen und in bei der EXPO 2000 zur energieoekologischen Modellstadt Ostritz darzustellen. (orig.)

  16. Electric power system applications of optimization

    CERN Document Server

    Momoh, James A

    2008-01-01

    Introduction Structure of a Generic Electric Power System  Power System Models  Power System Control Power System Security Assessment  Power System Optimization as a Function of Time  Review of Optimization Techniques Applicable to Power Systems Electric Power System Models  Complex Power Concepts Three-Phase Systems Per Unit Representation  Synchronous Machine Modeling Reactive Capability Limits Prime Movers and Governing Systems  Automatic Gain Control Transmission Subsystems  Y-Bus Incorporating the Transformer Effect  Load Models  Available Transfer Capability  Illustrative Examples  Power

  17. Model-based predictive direct power control of brushless doubly fed reluctance generator for wind power applications

    OpenAIRE

    Moazen, Maryam; Kazemzadeh, Rasool; Azizian, Mohammad-Reza

    2016-01-01

    In this paper, a predictive direct power control (PDPC) method for the brushless doubly fed reluctance generator (BDFRG) is proposed. Firstly, the BDFRG active and reactive power equations are derived and then the active and reactive power variations have been predicted within a fixed sampling period. The predicted power variations are used to calculate the required voltage of the secondary winding so that the power errors at the end of the following sampling period are eliminated. Switching ...

  18. Power amplifier circuit

    NARCIS (Netherlands)

    Takeya, Hideaki; Nauta, Bram

    2015-01-01

    PROBLEM TO BE SOLVED: To provide a power amplifier circuit which has high power efficiency while suppressing a fluctuation of output power relatively to a fluctuation of a power supply voltage in a high-efficiency switching amplifier which operates in a radio frequency band.SOLUTION: A duty ratio

  19. Estimation of the electrical power needed for LHC magnets and radiofrequency at 7 TeV

    CERN Document Server

    Thiesen, H; Burnet, J P

    2012-01-01

    The purpose of this paper is to provide the electrical power needed from the grid for the power converters feeding the magnets (superconducting, warm and experiments) and the radiofrequency of the LHC. At 4 TeV, the active power required for the magnets is 17.6MW and the estimation is 25.5MW at 7 TeV. The active power needed for the radiofrequency depends on the beam intensity and on the bunch spacing. It will grow from 7MW to 10MW with 25ns bunch spacing operation. This does not include the power needed for the cryogenic and magnet auxiliary systems. This paper gives also the instantaneous profile of the power needed from the grid during the ramp and the reactive power which needs to be compensated by the static VAR compensators.

  20. Optimization of Power Distribution Networks in Megacities

    Science.gov (United States)

    Manusov, V. Z.; Matrenin, P. V.; Ahyoev, J. S.; Atabaeva, L. Sh

    2017-06-01

    The study deals with the problem of city electrical networks optimization in big towns and megacities to increase electrical energy quality and decrease real and active power losses in the networks as well as in domestic consumers. The optimization is carried out according to the location selection and separate reactive power source in 10 kW networks of Swarm Intelligence algorithms, in particular, of Particle Swarm one. The problem solution based on Particle Swarm algorithm is determined by variables being discrete quantities and, in addition, there are several local minimums (troughs) to be available for a global minimum to be found. It is proved that the city power supply system optimization is carried out by the additional reactive power source to be installed at consumers location reducing reactive power flow, thereby, ensuring increase of power supply system quality and decrease of power losses in city networks.

  1. Mechanical power, thrust power

    OpenAIRE

    Gatta, Giorgio; Cortesi, Matteo; Swaine, Ian; Zamparo, Paola

    2017-01-01

    The purpose of this study was to explore the relationships between mechanical power, thrust power, propelling efficiency and sprint performance in elite swimmers. Mechanical power was measured in 12 elite sprint male swimmers: i) in the laboratory, by using a whole body swimming ergometer (W’TOT); and ii) in the pool, by measuring full tethered swimming force (FT) and maximal swimming velocity (Vmax): W’T = FT .Vmax. Propelling efficiency ( P) was estimated based on the “paddle wheel model“ a...

  2. Ancillary Services Provided from DER

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, J.B.

    2005-12-21

    Distributed energy resources (DER) are quickly making their way to industry primarily as backup generation. They are effective at starting and then producing full-load power within a few seconds. The distribution system is aging and transmission system development has not kept up with the growth in load and generation. The nation's transmission system is stressed with heavy power flows over long distances, and many areas are experiencing problems in providing the power quality needed to satisfy customers. Thus, a new market for DER is beginning to emerge. DER can alleviate the burden on the distribution system by providing ancillary services while providing a cost adjustment for the DER owner. This report describes 10 types of ancillary services that distributed generation (DG) can provide to the distribution system. Of these 10 services the feasibility, control strategy, effectiveness, and cost benefits are all analyzed as in the context of a future utility-power market. In this market, services will be provided at a local level that will benefit the customer, the distribution utility, and the transmission company.

  3. Internet Medline providers.

    Science.gov (United States)

    Vine, D L; Coady, T R

    1998-01-01

    Each database in this review has features that will appeal to some users. Each provides a credible interface to information available within the Medline database. The major differences are pricing and interface design. In this context, features that cost more and might seem trivial to the occasional searcher may actually save time and money when used by the professional. Internet Grateful Med is free, but Ms. Coady and I agree the availability of only three ANDable search fields is a major functional limitation. PubMed is also free but much more powerful. The command line interface that permits very sophisticated searches requires a commitment that casual users will find intimidating. Ms. Coady did not believe the feedback currently provided during a search was sufficient for sustained professional use. Paper Chase and Knowledge Finder are mature, modestly priced Medline search services. Paper Chase provides a menu-driven interface that is very easy to use, yet permits the user to search virtually all of Medline's data fields. Knowledge Finder emphasizes the use of natural language queries but fully supports more traditional search strategies. The impact of the tradeoff between fuzzy and Boolean strategies offered by Knowledge Finder is unclear and beyond the scope of this review. Additional software must be downloaded to use all of Knowledge Finders' features. Other providers required no software beyond the basic Internet browser, and this requirement prevented Ms. Coady from evaluating Knowledge Finder. Ovid and Silver Platter offer well-designed interfaces that simplify the construction of complex queries. These are clearly services designed for professional users. While pricing eliminates these for casual use, it should be emphasized that Medline citation access is only a portion of the service provided by these high-end vendors. Finally, we should comment that each of the vendors and government-sponsored services provided prompt and useful feedback to e

  4. [Schizophrenia and pain reactivity].

    Science.gov (United States)

    Bonnot, Olivier; Tordjman, Sylvie

    2008-11-01

    Medical practitioners do not for a long time pay enough attention to patient's pain. This approach is in the line of society feelings. Pain was long consider to be a contingency to withstand as showed in Christian's bible or Stoicism's principle. Changes in mentality appear in present times. It Seems obvious that for sociological and scientific reasons pain's care in medical and psychiatric disorders is now an important subject. Recent research in autistic disorders suggest that insensitivity observed in autism is not and analgesic phenomenon but a different behavioural reactivity to pain. Prevalence of schizophrenic disorder is from 0.5 to 1%. It is also a complex disorder that has defied decades of concerted efforts to uncover its origins and attenuate its symptoms. The most promising hypotheses suggest that neurodevelopmental impairment increases the risk of later schizophrenia. Most of recent researches in this topic did focus to trait or state markers. According to the vulnerability models of schizophrenia, trait marker are clinical, psychological, physiological, anatomical or cognitive impairments found in patients with schizophrenia during all the course of the illness and even before the onset. Several lines of evidence (case report, epidemiological studies, experimental studies) suggest that patients with schizophrenia shows a relative insensitivity to physical pain. We will review and critic the scientific literature in this specific topic. We will see if datas are relevant with the neurodevelopmental hypothesis and vulnerability models. An OLDMEDLINE/MEDLINE query was performed to identify 50 articles relevant to our subject. 9 were case report or case series, 21 were clinical or epidemiological studies, 15 were experimental studies and we also found 5 previous review. Clinical and experimental data strongly suggest a decrease of Behavioural Reactivity to Pain (BRP) but there is a lack of argument to prove a real analgesia. Because schizophrenia is a

  5. Pembrolizumab reactivates pulmonary granulomatosis

    Directory of Open Access Journals (Sweden)

    Majdi Al-dliw

    2017-01-01

    Full Text Available Sarcoid like reaction is a well-known entity that occurs as a consequence to several malignancies or their therapies. Immunotherapy has gained a lot of interest in the past few years and has recently gained approval as first line therapy in multiple advanced stage malignancies. Pneumonitis has been described as complication of such therapy. Granulomatous inflammation has been only rarely reported subsequent to immunotherapy. We describe a case of granulomatous inflammation reactivation affecting the lungs in a patient previously exposed to Pembrolizumab and have evidence of a distant granulomatous infection. We discuss potential mechanisms of the inflammation and assert the importance of immunosuppression in controlling the dis-inhibited immune system.

  6. Homogenization in chemical reactive flows

    Directory of Open Access Journals (Sweden)

    Carlos Conca

    2004-03-01

    Full Text Available This paper concerns the homogenization of two nonlinear models for chemical reactive flows through the exterior of a domain containing periodically distributed reactive solid grains (or reactive obstacles. In the first model, the chemical reactions take place on the walls of the grains, while in the second one the fluid penetrates the grains and the reactions take place therein. The effective behavior of these reactive flows is described by a new elliptic boundary-value problem containing an extra zero-order term which captures the effect of the chemical reactions.

  7. "IMPROVED REAL-POWER LOSS MINIMISATION"

    African Journals Online (AJOL)

    user

    1985-09-01

    Sep 1, 1985 ... and Vicks, L.W., Benefits of voltage scheduling in pdwer systems, IEEE Trans. on. Power Apparatus and Systems,. Vol. PAS-99, Sept./oct.1980, pp. 1701-1712. 2. Peschon, J., Piercy, D.S.. Tinney, W.F., Tveit, O.J. and Cuenod ,M., Optimum control of reactive power flow, IEEE Trans. on Power. Apparatus and.

  8. Dune field reactivation from blowouts: Sevier Desert, UT, USA

    Science.gov (United States)

    Barchyn, Thomas E.; Hugenholtz, Chris H.

    2013-12-01

    Dune field reactivation (a shift from vegetated to unvegetated state) has important economic, social, and environmental implications. In some settings reactivation is desired to preserve environmental values, but in arid regions reactivation is typically a form of land degradation. Little is known about reactivation due to a lack of published records, making modeling and prediction difficult. Here we detail dune reactivations from blowout expansion in the Sevier Desert, Utah, USA. We use historical aerial photographs and satellite imagery to track the transition from stable, vegetated dunes to actively migrating sediment in 3 locations. We outline a reactivation sequence: (i) disturbance breaches vegetation and exposes sediment, then (ii) creates a blowout with a deposition apron that (iii) advances downwind with a slipface or as a sand sheet. Most deposition aprons are not colonized by vegetation and are actively migrating. To explore causes we examine local sand flux, climate data, and stream flow. Based on available data the best explanation we can provide is that some combination of anthropogenic disturbance and climate may be responsible for the reactivations. Together, these examples provide a rare glimpse of dune field reactivation from blowouts, revealing the timescales, behaviour, and morphodynamics of devegetating dune fields.

  9. Streaming Pool: reuse, combine and create reactive streams with pleasure

    CERN Multimedia

    CERN. Geneva

    2017-01-01

    When connecting together heterogeneous and complex systems, it is not easy to exchange data between components. Streams of data are successfully used in industry in order to overcome this problem, especially in the case of "live" data. Streams are a specialization of the Observer design pattern and they provide asynchronous and non-blocking data flow. The ongoing effort of the ReactiveX initiative is one example that demonstrates how demanding this technology is even for big companies. Bridging the discrepancies of different technologies with common interfaces is already done by the Reactive Streams initiative and, in the JVM world, via reactive-streams-jvm interfaces. Streaming Pool is a framework for providing and discovering reactive streams. Through the mechanism of dependency injection provided by the Spring Framework, Streaming Pool provides a so called Discovery Service. This object can discover and chain streams of data that are technologically agnostic, through the use of Stream IDs. The stream to ...

  10. The Kinetic Determinants of Reactive Strength in Highly Trained Sprint Athletes.

    Science.gov (United States)

    Douglas, Jamie; Pearson, Simon; Ross, Angus; McGuigan, Mike

    2017-09-11

    The purpose of this study was to determine the braking and propulsive phase kinetic variables underpinning reactive strength in highly trained sprint athletes in comparison to a non-sprint trained control group. Twelve highly trained sprint athletes and twelve non-sprint trained participants performed drop jumps (DJs) from 0.25m, 0.50m and 0.75m onto a force plate. One familiarization session was followed by an experimental testing session within the same week. Reactive strength index (RSI), contact time, flight time, and leg stiffness were determined. Kinetic variables including force, power and impulse were assessed within the braking and propulsive phases. Sprint trained athletes demonstrated higher RSI versus non-sprint trained participants across all drop heights (3.02 vs 2.02; ES [±90% CL]: 3.11 ±0.86). This difference was primarily attained by briefer contact times (0.16 vs 0.22 s; ES: -1.49 ±0.53) with smaller differences observed for flight time (0.50 vs 0.46 s; ES: 0.53 ±0.58). Leg stiffness, braking and propulsive phase force and power were higher in sprint trained athletes. Very large differences were observed in mean braking force (51 vs 38 Nkg; ES: 2.57 ±0.73) which was closely associated with contact time (r ±90% CL: -0.93 ±0.05). Sprint trained athletes exhibited superior reactive strength than non-sprint trained participants. This was due to the ability to strike the ground with a stiffer leg spring, an enhanced expression of braking force, and possibly an increased utilization of elastic structures. The DJ kinetic analysis provides additional insight into the determinants of reactive strength which may inform subsequent testing and training.

  11. Green Power Markets

    Science.gov (United States)

    The U.S. EPA's Green Power Partnership defines Green power is a subset of renewable energy and represents those renewable energy resources and technologies that provide the highest environmental benefit.

  12. What Is Green Power?

    Science.gov (United States)

    The U.S. EPA's Green Power Partnership defines Green power is a subset of renewable energy and represents those renewable energy resources and technologies that provide the highest environmental benefit.

  13. Optimization of direct power control of three-phase shunt active power filter by using PSO algorithm

    Directory of Open Access Journals (Sweden)

    Mohamed Rida BENGOURINA

    2017-12-01

    Full Text Available This paper presents the modelling and simulation of a three-phase shunt active power filter (SAPF using the direct power control (DPC based on the Particle Swarm Optimization (PSO algorithm for power quality improvement. In the DPC technique, the switches states of the inverter are selected from a table of switching based on the immediate errors between the active and reactive powers and their reference values. PSO algorithm is used in order to optimize the PI controller gains of the DC link voltage. This PI-PSO gives better results for robustness, harmonic minimization and reduces the overshoot and undershoot of PI controller. A MATLAB/SIMILINK simulation is provided to demonstrate the performance of the proposed approach.

  14. Weigle Reactivation in Acinetobacter Calcoaceticus

    DEFF Research Database (Denmark)

    Berenstein, Dvora

    1982-01-01

    Weigle (W)-reactivation was demonstrated in Acinetobacter calcoaceticus for the UV-irra-diated lysogenic phage P78. The reactivation factor (survival of irradiated phage on irradiated bacteria/ survival on unirradiated bacteria) reached a maximum value of 20. This was obtained at UV-doses giving...

  15. Stress Reactivity in Male Undergraduates.

    Science.gov (United States)

    Sharpley, Christopher F.; Fleming, Richard K.

    1989-01-01

    Measured heart rate reactivity of typical sample of male undergraduates. Found cardiac reactivity of undergraduate males in response to a stressor task was not a function of success at or familiarity with task but was more likely an outcome of genetic factors. (Author/ABL)

  16. Cortisol reactivity in young infants

    NARCIS (Netherlands)

    Jansen, J.; Beijers, R.; Riksen-Walraven, J.M.A.; Weerth, C. de

    2010-01-01

    In this systematic review on empirical studies of cortisol reactivity to acute stressors in infants, we specifically focus on the role of infant age in the early development of cortisol reactivity to stressors. Our findings indicate that many psychological stressors do not provoke a cortisol

  17. Power oscillation damping controller

    DEFF Research Database (Denmark)

    2012-01-01

    A power oscillation damping controller is provided for a power generation device such as a wind turbine device. The power oscillation damping controller receives an oscillation indicating signal indicative of a power oscillation in an electricity network and provides an oscillation damping control...... signal in response to the oscillation indicating signal, by processing the oscillation damping control signal in a signal processing chain. The signal processing chain includes a filter configured for passing only signals within a predetermined frequency range....

  18. Temporal Dynamics of Proactive and Reactive Motor Inhibition

    Directory of Open Access Journals (Sweden)

    Ulrike M. Krämer

    2017-04-01

    Full Text Available Proactive motor inhibition refers to endogenous preparatory mechanisms facilitating action inhibition, whereas reactive motor inhibition is considered to be a sudden stopping process triggered by external signals. Previous studies were inconclusive about the temporal dynamics of involved neurocognitive processes during proactive and reactive motor control. Using electroencephalography (EEG, we investigated the time-course of proactive and reactive inhibition, measuring event-related oscillations and event-related potentials (ERPs. Participants performed in a cued go/nogo paradigm with cues indicating whether the motor response might or might not have to be inhibited. Based on the dual mechanisms of control (DMC framework by Braver, we investigated the role of attentional effects, motor preparation in the sensorimotor cortex and prefrontal cognitive control mechanisms, separating effects before and after target onset. In the cue-target interval, proactive motor inhibition was associated with increased attention, reflected in reduced visual alpha power and an increased contingent negative variation (CNV. At the same time, motor inhibition was modulated by reduced sensorimotor beta power. After target onset, proactive inhibition resulted in an increased N1, indicating allocation of attention towards relevant stimuli, increased prefrontal beta power and a modulation of sensorimotor mu activity. As in previous studies, reactive stopping of motor actions was associated with increased prefrontal beta power and increased sensorimotor beta activity. The results stress the relevance of attentional mechanisms for proactive inhibition and speak for different neurocognitive mechanisms being involved in the early preparation for and in later implementation of motor inhibition.

  19. Conceptual design and analysis of ITM oxy-combustion power cycles.

    Science.gov (United States)

    Mancini, N D; Mitsos, A

    2011-12-28

    Ion transport membrane (ITM)-based oxy-combustion systems could potentially provide zero-emissions power generation with a significantly reduced thermodynamic penalty compared to conventional carbon capture applications. This article investigates ITM-based oxy-combustion power cycles using an intermediate-fidelity model that captures the complex physical coupling between the two systems and accurately accounts for operational constraints. Coupled ITM-cycle simulation reveals hidden design challenges, facilitates the development of novel cycle concepts, and enables accurate assessment of new and existing power cycles. Simulations of various ITM-based zero and partial-emissions power cycles are performed using an intermediate-fidelity ITM model coupled to power cycle models created in ASPEN Plus®. The objectives herein are to analyze the prevalent ITM-based power cycle designs, develop novel design modifications, and evaluate the implementation of reactive ITMs. An assessment of the potential for these ITM power cycles to reduce both the thermodynamic penalty and reactor size associated with ITM air separation technology is conducted. The power cycle simulation and analysis demonstrate the various challenges associated with implementing reactive ITMs; hybridization (the use of both reactive and separation-only ITMs) is necessary in order to effectively utilize the advantages of reactive ITMs. The novel hybrid cycle developed herein displays the potential to reduce the size of the ITM compared to the best separation-only concept while maintaining a comparable First Law efficiency. Next, the merit of implementing partial-emissions cycles is explored based on a proposed linear-combination metric. The results indicate that the tradeoff between the main thermodynamic performance metrics efficiency and CO(2) emissions does not appear to justify the use of partial-emissions cycles.

  20. A comparative classification of coal reactivity

    Energy Technology Data Exchange (ETDEWEB)

    Zolin, A.; Jensen, A.; Storm Pedersen, L. [Technical Univ. Lyngby (Denmark). Dept. of Chemical Engineering; Toerslev Jensen, P.; Dam-Johansen, K. [Elsam I/S, Fredericia (Denmark)

    1997-12-31

    Based on thermogravimetric analysis (TGA) tests, a qualitative reactivity classification of nine different coals ranking from subbituminous to low volatile bituminous with respect to one coal, Cerrejon, is presented. The classification agrees well with a corresponding one obtained from another study by entrained flow reactor (EFR) experiments. Two Southern Hemisphere coals (Australia), however, showed a higher reactivity with respect to the Northern Hemisphere coal Cerrejon (Colombia) in the low temperature TGA experiments. It appears that TGA can provide a simple means for determining a fuel reactivity classification that may be applied to full scale suspension fired plants. The combustion behaviour of the Cerrejon coals was investigated at different temperatures and oxygen concentrations to determine the activation energy and reaction order. In addition, TGA tests revealed that for this coal, increasing values of the heat treatment temperature and holding time during pyrolysis result in lower char reactivities. This is attributed to the severity of the pyrolysis process and thereby the influence of thermal annealing effects. (orig.)

  1. Cytomegalovirus reactivation in ICU patients.

    Science.gov (United States)

    Papazian, Laurent; Hraiech, Sami; Lehingue, Samuel; Roch, Antoine; Chiche, Laurent; Wiramus, Sandrine; Forel, Jean-Marie

    2016-01-01

    Approximately 20 years have passed since we reported our results of histologically proven cytomegalovirus (CMV) pneumonia in non-immunocompromised ICU patients. Even if there are more recent reports suggesting that CMV may worsen the outcomes for ICU patients, there is no definite answer to this question: is CMV a potential pathogen for ICU patients or is it simply a bystander? We will describe the pathophysiology of active CMV infection and the most recent insights concerning the epidemiological aspects of these reactivations. Cytomegalovirus can be pathogenic by a direct organ insult (such as for the lung), by decreasing host defences against other microorganisms and/or by enhancing the body's inflammatory response (as in acute respiratory distress syndrome). The incidence of active CMV infection is dependent on the diagnostic method used. Using the most sophisticated available biological tools, the incidence can reach 15-20% of ICU patients (20-40% in ICU patients with positive CMV serology). In adequately powered cohorts of patients, active CMV infection appears to be associated with worse outcomes for mechanically ventilated ICU patients. There is no absolute direct proof of a negative impact of active CMV infection on the health outcomes of mechanically ventilated patients. Prospective randomized trials are lacking. Future trials should examine the potential benefits for health outcomes of using antiviral treatments. Such treatments could be prophylactic, pre-emptive or used only when there is an end-organ disease. Cytomegalovirus infection may affect health outcomes for ICU patients. Additional prospective trials are necessary to confirm this hypothesis.

  2. Balancing modern Power System with large scale of wind power

    DEFF Research Database (Denmark)

    Basit, Abdul; Altin, Müfit; Hansen, Anca Daniela

    2014-01-01

    Power system operators must ensure robust, secure and reliable power system operation even with a large scale integration of wind power. Electricity generated from the intermittent wind in large propor-tion may impact on the control of power system balance and thus deviations in the power system...... frequency in small or islanded power systems or tie line power flows in interconnected power systems. Therefore, the large scale integration of wind power into the power system strongly concerns the secure and stable grid operation. To ensure the stable power system operation, the evolving power system has...... to be analysed with improved analytical tools and techniques. This paper proposes techniques for the active power balance control in future power systems with the large scale wind power integration, where power balancing model provides the hour-ahead dispatch plan with reduced planning horizon and the real time...

  3. [Synthesis and luminescence properties of reactive ternary europium complexes].

    Science.gov (United States)

    Guo, Dong-cai; Shu, Wan-gen; Zhang, Wei; Liu, You-nian; Zhou, Yue

    2004-09-01

    In this paper, five new reactive ternary europium complexes were synthesized with the first ligand of 1,10-phenanthroline and the reactive second ligands of maleic anhydride, acrylonitrile, undecenoic acid, oleic acid and linoleic acid, and also characterized by means of elemental analysis, EDTA titrimetric method, FTIR spectra and UV spectra. The fluorescence spectra show that the five new ternary complexes have much higher luminescence intensity than their corresponding binary complexes, and the synergy ability sequence of the five reactive ligands is as follows: linoleic acid > oleic acid > acrylonitrile > maleic anhydride > undecenoic acid. At the same time, the reactive ternary europium complexes coordinated with the reactive ligands, which can be copolymerized with other monomers, will provide a new way for the synthesis of bonding-type rare earth polymer functional materials with excellent luminescence properties.

  4. Genome reactivation after the silence in mitosis: recapitulating mechanisms of development?

    Science.gov (United States)

    Zaret, Kenneth S

    2014-04-28

    Transcription is silenced during mitosis and reactivated at mitotic exit. The dynamics and identities of "bookmarking" transcription factors and chromatin marks that mediate reactivation often recapitulate those observed during cell identity establishment in development. Thus, features of postmitotic gene reactivation can provide insights into mechanisms of developmental cell fate establishment. Copyright © 2014 Elsevier Inc. All rights reserved.

  5. OPF-Based Optimal Location of Two Systems Two Terminal HVDC to Power System Optimal Operation

    Directory of Open Access Journals (Sweden)

    Mehdi Abolfazli

    2013-04-01

    Full Text Available In this paper a suitable mathematical model of the two terminal HVDC system is provided for optimal power flow (OPF and optimal location based on OPF such power injection model. The ability of voltage source converter (VSC-based HVDC to independently control active and reactive power is well represented by the model. The model is used to develop an OPF-based optimal location algorithm of two systems two terminal HVDC to minimize the total fuel cost and active power losses as objective function. The optimization framework is modeled as non-linear programming (NLP and solved by Matlab and GAMS softwares. The proposed algorithm is implemented on the IEEE 14- and 30-bus test systems. The simulation results show ability of two systems two terminal HVDC in improving the power system operation. Furthermore, two systems two terminal HVDC is compared by PST and OUPFC in the power system operation from economical and technical aspects.

  6. Utilizing MATPOWER in Optimal Power Flow

    Directory of Open Access Journals (Sweden)

    Tarjei Kristiansen

    2003-01-01

    Full Text Available This paper shows how MATPOWER, a MATLAB Power System Simulation Package can be used for optimal power flow (OPF simulations. MATPOWER is a package of MATLAB files for solving power flow and optimal power flow problems. It is a simulation tool for researchers and educators which is easy to use and modify. An OPF simulation gives the active/reactive power generated and purchased at each bus and the nodal prices. The nodal prices are of special interest because they reflect the marginal generation and load at each bus (node. These prices are also called locational prices and are found to be the optimal prices, maximizing social welfare and taking transmission constraints into account. They can provide the right incentives to market players and to society. When transmission congestion is present this creates market inefficiency, since cheap distant generation may be replaced with more expensive local generation. We are especially interested in OPF as utilized by a centralized dispatcher, and we also describe the features relevant for the Norwegian and Nordic markets. We optimize three cases and analyze the economic consequences of different network topologies and transmission congestion.

  7. Performance of U3Si2 Fuel in a Reactivity Insertion Accident

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Lap Y.; Cuadra, Arantxa; Todosow, Michael; Gamble, Kyle A.; Medvedev, Pavel G.

    2016-04-01

    In this study we examined the performance of the U3Si2 fuel cladded with Zircaloy (Zr) in a reactivity insertion accident (RIA) in a PWR core. The power excursion as a result of a $1 reactivity insertion was calculated by a TRACE PWR plant model using point-kinetics, for alternative cores with UO2 and U3Si2 fuel assemblies. The point-kinetics parameters (feedback coefficients, prompt-neutron lifetime and group constants for six delayed-neutron groups) were obtained from beginning-of-cycle equilibrium full core calculations with PARCS. In the PARCS core calculations, the few-group parameters were developed utilizing the TRITON/NEWT tools in the SCALE package. In order to assess the fuel response in finer detail (e.g. the maximum fuel temperature) the power shape and thermal boundary conditions from the TRACE/PARCS calculations were used to drive a BISON model of a fuel pin with U3Si2 and UO2 respectively. For a $1 reactivity transient both TRACE and BISON predicted a higher maximum fuel temperature for the UO2 fuel than the U3Si2 fuel. Furthermore, BISON is noted to calculate a narrower gap and a higher gap heat transfer coefficient than TRACE. This resulted in BISON predicting consistently lower fuel temperatures than TRACE. This study also provides a systematic comparison between TRACE and BISON using consistent transient boundary conditions. The TRACE analysis of the RIA only reflects the core-wide response in power. A refinement to the analysis would be to predict the local peaking in a three-dimensional core as a result of control rod ejection.

  8. Integrated Design and Control of Reactive and Non-Reactive Distillation Processes

    DEFF Research Database (Denmark)

    Mansouri, Seyed Soheil; Sales-Cruz, Mauricio; Huusom, Jakob Kjøbsted

    , an alternative approach is to tackle process design and controllability issues simultaneously, in the early stages of process design. This simultaneous synthesis approach provides optimal/near optimal operation and more efficient control of conventional (non-reactive binary distillation columns) (Hamid et al......., 2010) as well as complex chemical processes; for example, intensified processes such as reactive distillation (Mansouri et al., 2015). Most importantly, it identifies and eliminates potentially promising design alternatives that may have controllability problems later. To date, a number...... of methodologies have been proposed and applied on various problems to address the interactions between process design and control, and they range from optimization-based approaches to model-based methods (Sharifzadeh, 2013). In this work, integrated design and control of non-reactive distillation, ternary...

  9. Reatividade animal Confinement reactivity

    Directory of Open Access Journals (Sweden)

    Walsiara Estanislau Maffei

    2009-07-01

    Full Text Available A reatividade é definida como a reação do animal quando contido num ambiente de contenção móvel. Ela é quantificada por meio do teste de reatividade animal em ambiente de contenção móvel - REATEST®. Este teste consiste num dispositivo eletrônico acoplado à balança e num software específico. O dispositivo capta a movimentação que o animal provoca na balança, durante 20 segundos e a envia para o software que a processa determinando a reatividade do animal numa escala contínua de pontos. Pontuações maiores são de animais mais reativos (mais agressivo. A reatividade foi criada com os objetivos de solucionar os problemas até então existentes na seleção para temperamento e de permitir estimação de parâmetros genéticos mais confiáveis. Ela é uma característica objetiva que tem grande variabilidade fenotípica e é de quantificação rápida, fácil e segura, além de poder ser quantificada em qualquer tipo de balança, o que permite maior aplicabilidade. Ela não interfere nas práticas de manejo das fazendas porque é quantificada no momento da pesagem dos animais. Sua herdabilidade na raça Nelore é de 0,39 ao ano e 0,23 ao sobreano e suas correlações genéticas com ganho de peso diário são de -0,28 do nascimento até desmama e de -0,49 do desmame até ano. Já suas correlações genéticas com desenvolvimento do perímetro escrotal do ano ao sobreano variam de -0,25 e -0,41.The confinement reactivity (CR has been used as a measure of temperament in Brazil and it is defined as the animal reaction when contained in the scale. It is quantified through the animal reactivity test - REATEST®. This test consists of an electronic device coupled to the scale and of specific software. The device captures the movement that the animal provokes in the scale, during 20 seconds and sends it for the software that processes this movement and determines the animal CR in a continuous scale of points. Higher punctuations belong to

  10. Optimising Reactive Control in non-ideal Efficiency Wave Energy Converters

    DEFF Research Database (Denmark)

    Strager, Thomas; Lopez, Pablo Fernandez; Giorgio, Giuseppe

    2014-01-01

    . These have been derived under the assumptions of monochromatic incoming waves and linear system behaviour. This allows to establish the power factor of a system with non-ideal efficiency. The locus of the optimal reactive control parameters is then studied and an alternative method of representation......When analytically optimising the control strategy in wave energy converters which use a point absorber, the efficiency aspect is generally neglected. The results presented in this paper provide an analytical expression for the mean harvested electrical power in non-ideal efficiency situations...... is developed to model the optimal control parameters. Ultimately we present a simple method of choosing optimal control parameters for any combination of efficiency and wave frequency....

  11. Sexual Orientation Modulates Endocrine Stress Reactivity

    Science.gov (United States)

    Juster, Robert-Paul; Hatzenbuehler, Mark L.; Mendrek, Adrianna; Pfaus, James G.; Smith, Nathan Grant; Johnson, Philip Jai; Lefebvre-Louis, Jean-Philippe; Raymond, Catherine; Marin, Marie-France; Sindi, Shireen; Lupien, Sonia J.; Pruessner, Jens C.

    2015-01-01

    BACKGROUND Biological sex differences and sociocultural gender diversity influence endocrine stress reactivity. Although numerous studies have shown that men typically activate stronger stress responses than women when exposed to laboratory-based psychosocial stressors, it is unclear whether sexual orientation further modulates stress reactivity. Given that lesbian, gay, and bisexual (LGB) individuals frequently report heightened distress secondary to stigma-related stressors, we investigated whether cortisol stress reactivity differs between LGB individuals and heterosexual individuals in response to a well-validated psychosocial stressor. METHODS The study population comprised 87 healthy adults (mean age, 25 years) who were grouped according to their biological sex and their gendered sexual orientation: lesbian/bisexual women (n = 20), heterosexual women (n = 21), gay/bisexual men (n = 26), and heterosexual men (n = 20). Investigators collected 10 salivary cortisol samples throughout a 2-hour afternoon visit involving exposure to the Trier Social Stress Test modified to maximize between-sex differences. RESULTS Relative to heterosexual women, lesbian/bisexual women showed higher cortisol stress reactivity 40 min after exposure to the stressor. In contrast, gay/bisexual men displayed lower overall cortisol concentrations throughout testing compared with heterosexual men. Main findings were significant while adjusting for sex hormones (estradiol-to-progesterone ratio in women and testosterone in men), age, self-esteem, and disclosure status (whether LGB participants had completed their “coming out”). CONCLUSIONS Our results provide novel evidence for gender-based modulation of cortisol stress reactivity based on sexual orientation that goes beyond well-established between-sex differences. This study raises several important avenues for future research related to the physiologic functioning of LGB populations and gender diversity more broadly. PMID:25444167

  12. Wind Power Impact to Transient and Voltage Stability of the Power System in Eastern Denmark

    DEFF Research Database (Denmark)

    Rasmussen, Joana; Jørgensen, Preben; Palsson, Magni Thor

    2005-01-01

    Voltage stability, transient stability and reactive power compensation are extremely important issues for largescale integration of wind power in areas distant from the main transmission system in Eastern Denmark. This paper describes the application of a dynamic wind farm model in simulation...... studies for assessments of a large wind power penetration. The simulation results reveal problems with voltage stability due to the characteristic of wind turbine generation as well as the inability of the power system to meet the reactive power demand. Furthermore, the established model is applied...

  13. Concept and controllability of virtual power plant

    Energy Technology Data Exchange (ETDEWEB)

    Setiawan, E.A.

    2007-07-01

    In the end of 20th century the conception of electrical power supply is morphing gradually from centralized into decentralized system, indicated by increasing the installation of distributed generation on the main grid. With emerging of advanced communication and information technology, the aggregation control of several DG units can be developed as virtual power plant in order to provide added-value to the electric power system. This thesis presents definitions and types of Virtual Power Plants (VPP), then developing control through numerical simulation. The thesis proposes three DG controls namely Basic Autocontrol System (BAS), Smart Autocontrol System (SAS) and Tracking Efficiency Autocontrol System (TEAS). The BAS controls the DG output power with the objective to cover the local load demand. The drawback of this system is that the coordination among DG units is not established yet. In contrast to the BAS, the SAS has a control coordination centre which is responsible of controlling a certain number of DG units. The SAS controls and coordinates the operation of the dedicated DG units in order to minimize power exchange with the superior grid. However the efficiency issue is not considered at two previous control systems, therefore the TEAS was developed. Principally this system is similar to the SAS in terms of information exchange but additionally optimizes the operation efficiency of DG units. This is accomplished by tracking the systems' most efficient operation point. All control systems have been implemented into a simulation environment. The simulation results show that all developed control systems are capable to minimize the power exchange with the superior grid. The systems are able to follow changing load conditions. Furthermore the simulation results prove the ability of TEAS to optimize the system efficiency. Finally the contribution of VPP to voltage regulation is investigated with several scenarios. The influence of both, active and reactive

  14. Preliminary Analysis on Reactivity Insertion Transient of Natural Circulation Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Son, Hyung Min [KAERI, Daejeon (Korea, Republic of); Suh, Kune Yull [Seoul National University, Seoul (Korea, Republic of)

    2015-05-15

    When a malfunction of the reactor control system occurs, there's a chance that the positive reactivity is inserted into the core, resulting in the increase of the core power. With the combination of the failure of the related safety features, this may raise the temperature of the core material beyond the design limit to break its integrity. For the fast nuclear reactors like FFTF and CRBRP, the overpower trip is initiated when the power reaches 115% of rated value to keep the fuel from melting. In this study, the system response to the reactivity insertion transient on a liquid metal cooled natural circulation reactor is analyzed utilizing an in-house code based on a momentum integral model. Utilizing an in-house system analysis code, a set of numerical simulation is carried out on the reactivity ramp insertion transients which showed that the role of reactivity feedback is significant in mitigating the time to failure, and the evolution of the natural circulation mass flow is rather slow to generate meaningful feedback effect. It is also observed that in terms of the peak cladding temperature, smaller reactivity insertion transient generated more severe outcome owing to increased accumulation of the thermal energy within fuel pins. Thus, it may require an extra attention to carefully monitor and capture the mild transients to avoid potential drastic results.

  15. Solar technical assistance provided to Forest City military communities in Hawaii for incorporation of 20-30 MW of solar energy generation to power family housing for US Navy personnel.

    Energy Technology Data Exchange (ETDEWEB)

    Dominick, Jeff (National Renewable Energy Laboratory, Golden, CO); Merrigan, Tim (National Renewable Energy Laboratory, Golden, CO); Boudra, Will (Forest City Military Communities, Honolulu, HI); Miller, Ryan (CH2M Hill, Englewood, CO); Cisneros, Gabriela (New Mexico State University, Las Cruces, NM); Rosenthal, Andrew L. (New Mexico State University, Las Cruces, NM); Kuszmaul, Scott S.; Gupta, Vipin P.

    2010-06-01

    In May 2007, Forest City Military Communities won a US Department of Energy Solar America Showcase Award. As part of this award, executives and staff from Forest City Military Communities worked side-by-side with a DOE technical assistance team to overcome technical obstacles encountered by this large-scale real estate developer and manager. This paper describes the solar technical assistance that was provided and the key solar experiences acquired by Forest City Military Communities over an 18 month period.

  16. Static compensation of reactive for increasing the energy availability; Compensacao estatica de reativos para aumentar a disponibilidade de energia

    Energy Technology Data Exchange (ETDEWEB)

    Grunbaum, Rolf; Rasmussen, J.; Silva, A. [ABB Suica (Sweden); Canal, Mauricio [ISA Brasil (Brazil)

    2010-03-15

    This paper describes the implementation of a static compensation system of the reactive at an oil field which was experiencing frequent production interruptions due to power level variations and shutdown. Besides the increasing of energy power absorbed from the grid and the power stabilization of the installation, the system increased the dynamic answer when occurring voltage slags, load rejection and power generator shutdowns.

  17. Advanced power cycles for concentrated solar power

    OpenAIRE

    Stein, W. H.; Buck, Reiner

    2017-01-01

    This paper provides a review of advanced power cycles under consideration for CSP. As variable renewables make rapid commercial progress, CSP with thermal energy storage is in an excellent position to provide low cost stability and reliability to the grid, however higher efficiency and lower costs are critical. Steam turbines provide a robust commercial option for today but more advanced power cycles offering greater agility and flexibility are needed. Supercritical steam turbines are attract...

  18. {sup 18}F-FDG PET/CT following chemoradiation of uterine cervix cancer provides powerful prognostic stratification independent of HPV status: a prospective cohort of 105 women with mature survival data

    Energy Technology Data Exchange (ETDEWEB)

    Siva, Shankar; Hicks, Rodney J.; Callahan, Jason [Peter MacCallum Cancer Centre, Division of Radiation Oncology and Cancer Imaging, East Melbourne, Victoria (Australia); University of Melbourne, Sir Peter MacCallum Department of Oncology, Parkville (Australia); Deb, Siddhartha [Peter MacCallum Cancer Centre, Department of Pathology, East Melbourne (Australia); Young, Richard J. [Peter MacCallum Cancer Centre, Molecular Therapeutics and Biomarkers Laboratory, East Melbourne (Australia); Bressel, Mathias [Peter MacCallum Cancer Centre, Department of Biostatistics and Clinical Trials, East Melbourne (Australia); Mileshkin, Linda [Peter MacCallum Cancer Centre, Department of Cancer Medicine, East Melbourne (Australia); Rischin, Danny [University of Melbourne, Sir Peter MacCallum Department of Oncology, Parkville (Australia); Peter MacCallum Cancer Centre, Department of Cancer Medicine, East Melbourne (Australia); Bernshaw, David; Narayan, Kailash [Peter MacCallum Cancer Centre, Division of Radiation Oncology and Cancer Imaging, East Melbourne, Victoria (Australia)

    2015-11-15

    not multivariable analysis (p = 0.11). At 5 years CMR remains a powerful factor predicting survival after initial and salvage therapy. Metabolic response was not associated with HPV infection risk. Further studies are required to establish the association with HPV infection risk and survival after chemoradiation. (orig.)

  19. Wind power soars

    Energy Technology Data Exchange (ETDEWEB)

    Flavin, C. [Worldwatch Inst., Washington, DC (United States)

    1996-12-31

    Opinions on the world market for wind power are presented in this paper. Some data for global wind power generating capacity are provided. European and other markets are discussed individually. Estimated potential for wind power is given for a number of countries. 3 figs.

  20. Power Plant Cycling Costs

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, N.; Besuner, P.; Lefton, S.; Agan, D.; Hilleman, D.

    2012-07-01

    This report provides a detailed review of the most up to date data available on power plant cycling costs. The primary objective of this report is to increase awareness of power plant cycling cost, the use of these costs in renewable integration studies and to stimulate debate between policymakers, system dispatchers, plant personnel and power utilities.