光伏并网逆变器故障穿越暂态电流抑制及实证

Fault Ride-through Transient Current Suppression of Photovoltaic Grid-connected Inverter and Demonstration

根据相关国家标准要求,大型光伏并网逆变器需要具备零电压故障穿越能力以防止其发生低压自动脱网,从而影响电力系统正常稳定运行。在分析光伏并网逆变器零电压穿越(ZVRT)标准的基础上,详细讨论了逆变器实现ZVRT的各项关键技术,包括:电网电压正负序分离及锁相、逆变器有功无功电流控制、电网电压不平衡时系统控制等。在此基础之上,进一步提出向系统电流环引入电网电压前馈分量超前相位补偿环节,以改善逆变器故障穿越瞬间并网电流过冲现象。最后利用RTDS硬件在环平台和一台500 kW样机的实验结果充分验证了所提光伏并网逆变器ZVRT控制策略的正确性和有效性。

According to the national standard,the high-power photovoltaic gird-connected inverter should need to have the zero voltage ride-through(ZVRT)ability for avoiding to take off the power grid automatically under the condition of lower voltage,which would affect the stable operation of power system.Based on the analysis of the standard about ZVRT of photovoltaic gird-connected inverter,some key technologies including the separation of positive and negative sequence of grid voltage,phase-lock loop,the control strategy of active/reactive current,the control strategy of inverter under the condition of unbalanced grid voltage,etc is discussed.In addition,the leading phase compensation for the feed-forward component of grid voltage is proposed and introduced into the current loop of control system,in order to limit the current overshoot during the transient of ZVRT.The effectiveness of the proposed ZVRT control strategy is verified by simulation on RTDS and experimental results of a 500 kW prototype.