不平衡情况下光伏多电平逆变器的控制策略研究

A Study on the Control Strategy for Multi-level PV Inverters under Unbalanced Conditions

电网发生不对称故障时,电网电压中存在的负序分量会对光伏并网控制造成影响。为了消除逆变器交流侧电流和直流侧电压的谐波,采用了正、负序独立旋转坐标系的控制方法,做了基于光伏三电平逆变器的电网不平衡情况下的并网控制策略仿真。仿真结果表明采用正、负序独立旋转坐标系的控制方法,逆变器交流侧电流和直流侧电压的谐波得到有效抑制。

When an unbalanced fault occurs in the power grid,PV grid connection will be affected by the negative sequence component existing in the grid voltage. To eliminate harmonics of the current on the inverter AC side and the voltage on its DC side,grid connection control strategy is simulated under unbalanced grid conditions based on the 3-level PV inverter by adopting a coordinate system with independently rotating positive and negative sequences. Simulation results show that this approach can effectively suppress the harmonics of the current on the inverter AC side and the voltage on its DC side.