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 Photovoltaic(PV)plants are significantly different from the conventional synchronous generators in terms of physical and electrical characteristics,as it connects to the power grid through the voltage-source conve...The Photovoltaic(PV)plants are significantly different from the conventional synchronous generators in terms of physical and electrical characteristics,as it connects to the power grid through the voltage-source converters.High penetration PV in power system will bring several critical challenges to the safe operation of power grid including transient stability.To address this problem,the paper proposes a control strategy to help the PVs work like a synchronous generator with variable inertia by energy storage system(ESS).First,the overall control strategy of the PV-based virtual synchronous generator(PV-VSG)is illustrated.Then the control strategies for the variable inertia of the PV-VSG are designed to attenuate the transient energy of the power system after the fault.Simulation results of a simple power system show that the PV-VSG could utilize the energy preserved in the ESS to balance the transient energy variation of power grid after fault and improve the transient stability of the power system.展开更多
The photovoltaic virtual synchronous generator(PV-VSG)solves the problem of lack of inertia in the PV power-generation system.The existing PV plants without energy storage are required to participate in the power grid...The photovoltaic virtual synchronous generator(PV-VSG)solves the problem of lack of inertia in the PV power-generation system.The existing PV plants without energy storage are required to participate in the power grid’s frequency modulation(FM),but existing PV-VSGs with energy storage have high requirements for coordinated control.Therefore,the active power reserve PV-VSG(APR-PV-VSG)is studied.Based on the different methods to obtain the maximum power point(MPP),the peer-to-peer and master-slave APR-PV-VSG strategies are proposed.The PV inverters are deviated from the MPP to reserve active power,which is used as the virtual inertia and primary FM power.These methods equip the PV power station with FM capability.The effectiveness of the proposed control strategies is verified by simulation results.展开更多
针对具有固定转动惯量的常规光伏储能虚拟同步发电机并网发电系统容易出现功率振荡以及频率超调等问题,提出光储并网系统的虚拟同步发电机(virtual synchronous generator,VSG)自适应控制策略。首先,搭建虚拟同步发电机控制的光伏储能...针对具有固定转动惯量的常规光伏储能虚拟同步发电机并网发电系统容易出现功率振荡以及频率超调等问题,提出光储并网系统的虚拟同步发电机(virtual synchronous generator,VSG)自适应控制策略。首先,搭建虚拟同步发电机控制的光伏储能并网发电系统模型,系统前级采用光伏最大功率点跟踪(maximum power point tracking,MTTP)控制以及储能控制策略;然后,根据功角特性和转子角频率特性曲线分析转动惯量对VSG动态特性的影响,将RBF神经网络应用到VSG中,对转动惯量进行自适应调整,同时,在固定阻尼比的基础上,随着转动惯量的变化自适应调整阻尼系数;在MATLAB/SIMULINK上建立光储并网系统的VSG自适应控制仿真模型,验证此控制策略的可行性;最后,将自适应转动惯量阻尼控制策略与其他控制策略进行对比,仿真结果表明:采用此控制策略能够使光储并网系统的有功功率振荡得到抑制,改善转子角频率超调。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.
文摘The Photovoltaic(PV)plants are significantly different from the conventional synchronous generators in terms of physical and electrical characteristics,as it connects to the power grid through the voltage-source converters.High penetration PV in power system will bring several critical challenges to the safe operation of power grid including transient stability.To address this problem,the paper proposes a control strategy to help the PVs work like a synchronous generator with variable inertia by energy storage system(ESS).First,the overall control strategy of the PV-based virtual synchronous generator(PV-VSG)is illustrated.Then the control strategies for the variable inertia of the PV-VSG are designed to attenuate the transient energy of the power system after the fault.Simulation results of a simple power system show that the PV-VSG could utilize the energy preserved in the ESS to balance the transient energy variation of power grid after fault and improve the transient stability of the power system.
基金Supported by the Joint Funds of the National Natural Science Foundation of China(U1766207).
文摘The photovoltaic virtual synchronous generator(PV-VSG)solves the problem of lack of inertia in the PV power-generation system.The existing PV plants without energy storage are required to participate in the power grid’s frequency modulation(FM),but existing PV-VSGs with energy storage have high requirements for coordinated control.Therefore,the active power reserve PV-VSG(APR-PV-VSG)is studied.Based on the different methods to obtain the maximum power point(MPP),the peer-to-peer and master-slave APR-PV-VSG strategies are proposed.The PV inverters are deviated from the MPP to reserve active power,which is used as the virtual inertia and primary FM power.These methods equip the PV power station with FM capability.The effectiveness of the proposed control strategies is verified by simulation results.
文摘针对具有固定转动惯量的常规光伏储能虚拟同步发电机并网发电系统容易出现功率振荡以及频率超调等问题,提出光储并网系统的虚拟同步发电机(virtual synchronous generator,VSG)自适应控制策略。首先,搭建虚拟同步发电机控制的光伏储能并网发电系统模型,系统前级采用光伏最大功率点跟踪(maximum power point tracking,MTTP)控制以及储能控制策略;然后,根据功角特性和转子角频率特性曲线分析转动惯量对VSG动态特性的影响,将RBF神经网络应用到VSG中,对转动惯量进行自适应调整,同时,在固定阻尼比的基础上,随着转动惯量的变化自适应调整阻尼系数;在MATLAB/SIMULINK上建立光储并网系统的VSG自适应控制仿真模型,验证此控制策略的可行性;最后,将自适应转动惯量阻尼控制策略与其他控制策略进行对比,仿真结果表明:采用此控制策略能够使光储并网系统的有功功率振荡得到抑制,改善转子角频率超调。
