适用于光伏逆变器的低压穿越控制策略

摘要

In the actual operation of the power grid,the power quality of the three-phase grid connected photovoltaic inverter will deteriorate rapidly when the voltage sag occurs.The output current of inverter will be serious distortion,and even the inverter would disconnect due to overcurrent,the output power will fluctuate,which brings a serious security risk to the PV generation system.A low voltage ride through control strategy for photovoltaic inverters was presented.The control strategy could limit the increase of active currents,eliminate the fluctuation of active power and reduce the voltage of PCC unbalance degree when the power grid voltage was sagged.At the same time,it could also inject certain reactive power to support the grid.Simulation results verify the feasibility of the proposed control method.%在电网的实际运行中,当发生电压暂降时,三相光伏并网逆变器的电能质量将急剧恶化.逆变器输出电流将发生严重畸变,甚至会因过流而脱网,这给电网带来了严重的安全隐患.提出了一种适用于光伏逆变器的低压穿越控制策略,在电网电压跌落时,采用的控制策略可以限制有功电流的增加,消除有功功率的波动,降低PCC点电压不平衡度.同时,还可以注入一定的无功功率来支撑电网.仿真实验结果验证了所提出控制方法的可行性.