光伏并网逆变器及其低电压穿越技术

从光伏并网逆变器拓扑结构和工作原理入手,建立其数学模型,并对光伏并网逆变器在同步旋转坐标系下基于电网电压定向矢量控制的电压外环、电流内环双闭环控制策略进行了分析。阐述了光伏并网发电系统低电压穿越（LVRT）原理和相应的控制策略。利用Matlab/Simulink软件搭建了光伏并网发电系统仿真模块,给出了仿真波形。仿真结果表明,该方法能保证并网点电压跌落时光伏并网逆变器不过流,并根据电网电压跌落深度发出一定的无功电流来支撑并网点电压,使逆变器继续并网运行,从而提高了LVRT能力,为光伏逆变器在光伏电站中的应用提供可靠的理论依据。

Grid-Connected Photovoltaic Inverter and Its Low Voltage Ride-Through Technology

Starting from the topological structure and working principle of the grid-connected photovoltaic inverter,its mathematical model was established.This paper analyzed the double closed-loop controlling strategy based on grid voltage oriented vector control in two-phase synchronous rotating coordinates for the grid-connected photovoltaic inverter,and the double closed-loop includes the outside loop of voltage and the current inner loop.This paper also elaborated the principle of low voltage ride-through（LVRT） and the corresponding control strategy of grid-connected PV systems,constructing simulink module of grid-connected PV systems by Matlab/Simulink and giving the simulation waveforms.The simulation results show that the method can ensure that the output current of grid-connected PV inverter does not exceed the current value of protection when voltage sags happen.And according to the depth of grid voltage drop,the inverter provides a certain amount of reactive current to support the network voltage,making inverter keep grid-connected state and improving the low voltage ride-through capability.It provides reliable theory basis for the application of grid-connected photovoltaic inverter in photovoltaic power station.