对称和不对称故障下的并网光伏逆变器低电压穿越研究

从改变控制策略上,成功实现电网故障下光伏逆变器的低电压穿越。分别提出了抑制对称故障的直接功率控制策略和抑制不对称故障的基于正序、负序电流的双闭环矢量控制策略。在对称故障时,采用限功率运行的方法改变输入功率指令,减少光伏电池对电网的输出功率,实现电网对称故障下的成功穿越。在不对称故障时,提取出电网中的正序和负序分量,采用正序和负序电流双闭环矢量控制,有效地抑制了瞬时电流冲击。仿真结果表明,两种不同故障工况下控制策略的合理性和有效性。

Low Voltage Ride Through under Balance Fault and Unbalance fault for Grid-Connected PV Inverter

By means of the change of control strategy, successfully achieve the low voltage ride through of PV inverter under the grid fault. The direct power control strategy and double closed-loop vector control based on positive sequence, negative sequence current are respectively proposed under the balance fault and unbalance fault. When the voltage of grid is balanced, adopt the method of limiting active power to change the input power order, thus reduces the output active power of PV and realize LVRT successfully. When the unbalanced fault happens, carry out positive and negative sequence separation, positive and negative sequence current double-loop vector control are controlled. The simulation results show that the reasonable and effectiveness of the control strategy.