Due to the characteristics of intermittent photovoltaic power generation and power fluctuations in distributed photovoltaic power generation,photovoltaic grid-connected systems are usually equipped with energy storage...Due to the characteristics of intermittent photovoltaic power generation and power fluctuations in distributed photovoltaic power generation,photovoltaic grid-connected systems are usually equipped with energy storage units.Most of the structures combined with energy storage are used as the DC side.At the same time,virtual synchronous generators have been widely used in distributed power generation due to their inertial damping and frequency and voltage regulation.For the PV-storage grid-connected system based on virtual synchronous generators,the existing control strategy has unclear function allocation,fluctuations in photovoltaic inverter output power,and high requirements for coordinated control of PV arrays,energy storage units,and photovoltaic inverters,which make the control strategy more complicated.In order to solve the above problems,a control strategy for PV-storage grid-connected system based on a virtual synchronous generator is proposed.In this strategy,the energy storage unit implements maximum power point tracking,and the photovoltaic inverter implements a virtual synchronous generator algorithm,so that the functions implemented by each part of the system are clear,which reduces the requirements for coordinated control.At the same time,the smooth power command is used to suppress the fluctuation of the output power of the photovoltaic inverter.The simulation validates the effectiveness of the proposed method from three aspects:grid-connected operating conditions,frequency-modulated operating conditions,and illumination sudden-drop operating condition.Compared with the existing control strategies,the proposed method simplifies the control strategies and stabilizes the photovoltaic inverter fluctuation in the output power of the inverter.展开更多
The utilization of renewable energy in sending-end power grids is increasing rapidly,which brings difficulties to voltage control.This paper proposes a coordinated voltage control strategy based on model predictive co...The utilization of renewable energy in sending-end power grids is increasing rapidly,which brings difficulties to voltage control.This paper proposes a coordinated voltage control strategy based on model predictive control(MPC)for the renewable energy power plants of wind and solar power connected to a weak sending-end power grid(WSPG).Wind turbine generators(WTGs),photovoltaic arrays(PVAs),and a static synchronous compensator are coordinated to maintain voltage within a feasible range during operation.This results in the full use of the reactive power capability of WTGs and PVAs.In addition,the impact of the active power outputs of WTGs and PVAs on voltage control are considered because of the high R/X ratio of a collector system.An analytical method is used for calculating sensitivity coefficients to improve computation efficiency.A renewable energy power plant with 80 WTGs and 20 PVAs connected to a WSPG is used to verify the proposed voltage control strategy.Case studies show that the coordinated voltage control strategy can achieve good voltage control performance,which improves the voltage quality of the entire power plant.展开更多
This paper presentsa voltage control strategy for power distribution systems with interconnected renewable energy based distributed generators (DGs). The control strategy coordinating conventional voltage control devi...This paper presentsa voltage control strategy for power distribution systems with interconnected renewable energy based distributed generators (DGs). The control strategy coordinating conventional voltage control devices and reactive power from DG.A mixed-integer nonlinear programming problem was formulated and solved by particle swarm optimization (PSO). The code is written using DigSILENT programming language (DPL) and implemented inside DigSILENT power factory simulation software. All system constraints and operating limits are considered. The optimal power flow based approach can incorporate various uncertainties such as intermittent power characteristics and varying load demand. The proposed method is tested using real distribution network to demonstrate its effectiveness. The merits of the proposed method over the classical local-based control are presented in the simulation results. It is demonstrated that the proposed method is capable of keeping the system voltage within operating limit. Power losses is at the same time is minimized in comparison to the losses using conventional method.展开更多
实施紧急有功控制可解决风光水汇集外送直流闭锁导致的频率安全问题,但事故后可能衍生出电压安全问题,控制策略制定需要统筹考虑频率与电压安全。针对现有离线策略存在有功控制与无功控制割裂、控制代价大及控制手段不完备的问题,分析...实施紧急有功控制可解决风光水汇集外送直流闭锁导致的频率安全问题,但事故后可能衍生出电压安全问题,控制策略制定需要统筹考虑频率与电压安全。针对现有离线策略存在有功控制与无功控制割裂、控制代价大及控制手段不完备的问题,分析了弱支撑电网有功控制对系统电压影响的机理,为完善现有控制方案,提出综合连续型与离散型控制手段的有功、无功一体化在线紧急控制方案。以控制代价最小为目标,考虑暂态电压和频率安全约束,建立了计及多类控制措施的水风光汇集外送直流系统紧急频率电压协调控制优化模型,并采用逐次线性规划方法求解线性化后的模型。基于西北电网实际案例的实时数字模拟(real time digital simulation,RTDS)试验结果对所提控制进行验证,结果表明,所提控制策略实现了从离线到在线、离散到连续、割裂到协调的整体性提升。展开更多
基于自动电压控制技术对电网无功支撑与安全稳定运行的重要作用,介绍光伏并网点无功电压调节机理,以逆变器和静止无功发生器(static var generator,SVG)为研究对象,对光伏电站无功分配策略、SVG无功置换方法进行研究分析,并通过光伏电...基于自动电压控制技术对电网无功支撑与安全稳定运行的重要作用,介绍光伏并网点无功电压调节机理,以逆变器和静止无功发生器(static var generator,SVG)为研究对象,对光伏电站无功分配策略、SVG无功置换方法进行研究分析,并通过光伏电站现场试验验证光伏逆变器与SVG协调控制、无功置换的有效性,对新能源并网电站实现区域电网自动电压控制具有参考意义。展开更多
基金supported by National Natural Science Foundation of China Key program(51937003)。
文摘Due to the characteristics of intermittent photovoltaic power generation and power fluctuations in distributed photovoltaic power generation,photovoltaic grid-connected systems are usually equipped with energy storage units.Most of the structures combined with energy storage are used as the DC side.At the same time,virtual synchronous generators have been widely used in distributed power generation due to their inertial damping and frequency and voltage regulation.For the PV-storage grid-connected system based on virtual synchronous generators,the existing control strategy has unclear function allocation,fluctuations in photovoltaic inverter output power,and high requirements for coordinated control of PV arrays,energy storage units,and photovoltaic inverters,which make the control strategy more complicated.In order to solve the above problems,a control strategy for PV-storage grid-connected system based on a virtual synchronous generator is proposed.In this strategy,the energy storage unit implements maximum power point tracking,and the photovoltaic inverter implements a virtual synchronous generator algorithm,so that the functions implemented by each part of the system are clear,which reduces the requirements for coordinated control.At the same time,the smooth power command is used to suppress the fluctuation of the output power of the photovoltaic inverter.The simulation validates the effectiveness of the proposed method from three aspects:grid-connected operating conditions,frequency-modulated operating conditions,and illumination sudden-drop operating condition.Compared with the existing control strategies,the proposed method simplifies the control strategies and stabilizes the photovoltaic inverter fluctuation in the output power of the inverter.
基金supported by National Natural Science Foundation Joint Key Project of China(2016YFB0900900).
文摘The utilization of renewable energy in sending-end power grids is increasing rapidly,which brings difficulties to voltage control.This paper proposes a coordinated voltage control strategy based on model predictive control(MPC)for the renewable energy power plants of wind and solar power connected to a weak sending-end power grid(WSPG).Wind turbine generators(WTGs),photovoltaic arrays(PVAs),and a static synchronous compensator are coordinated to maintain voltage within a feasible range during operation.This results in the full use of the reactive power capability of WTGs and PVAs.In addition,the impact of the active power outputs of WTGs and PVAs on voltage control are considered because of the high R/X ratio of a collector system.An analytical method is used for calculating sensitivity coefficients to improve computation efficiency.A renewable energy power plant with 80 WTGs and 20 PVAs connected to a WSPG is used to verify the proposed voltage control strategy.Case studies show that the coordinated voltage control strategy can achieve good voltage control performance,which improves the voltage quality of the entire power plant.
文摘This paper presentsa voltage control strategy for power distribution systems with interconnected renewable energy based distributed generators (DGs). The control strategy coordinating conventional voltage control devices and reactive power from DG.A mixed-integer nonlinear programming problem was formulated and solved by particle swarm optimization (PSO). The code is written using DigSILENT programming language (DPL) and implemented inside DigSILENT power factory simulation software. All system constraints and operating limits are considered. The optimal power flow based approach can incorporate various uncertainties such as intermittent power characteristics and varying load demand. The proposed method is tested using real distribution network to demonstrate its effectiveness. The merits of the proposed method over the classical local-based control are presented in the simulation results. It is demonstrated that the proposed method is capable of keeping the system voltage within operating limit. Power losses is at the same time is minimized in comparison to the losses using conventional method.
文摘实施紧急有功控制可解决风光水汇集外送直流闭锁导致的频率安全问题,但事故后可能衍生出电压安全问题,控制策略制定需要统筹考虑频率与电压安全。针对现有离线策略存在有功控制与无功控制割裂、控制代价大及控制手段不完备的问题,分析了弱支撑电网有功控制对系统电压影响的机理,为完善现有控制方案,提出综合连续型与离散型控制手段的有功、无功一体化在线紧急控制方案。以控制代价最小为目标,考虑暂态电压和频率安全约束,建立了计及多类控制措施的水风光汇集外送直流系统紧急频率电压协调控制优化模型,并采用逐次线性规划方法求解线性化后的模型。基于西北电网实际案例的实时数字模拟(real time digital simulation,RTDS)试验结果对所提控制进行验证,结果表明,所提控制策略实现了从离线到在线、离散到连续、割裂到协调的整体性提升。
文摘基于自动电压控制技术对电网无功支撑与安全稳定运行的重要作用,介绍光伏并网点无功电压调节机理,以逆变器和静止无功发生器(static var generator,SVG)为研究对象,对光伏电站无功分配策略、SVG无功置换方法进行研究分析,并通过光伏电站现场试验验证光伏逆变器与SVG协调控制、无功置换的有效性,对新能源并网电站实现区域电网自动电压控制具有参考意义。