高压直流输电系统抑制换相失败的最小关断面积控制策略

A minimum extinction area control strategy to suppress commutation failure in HVDC transmission system

根据逆变器的换相过程,分析了换相失败机理。比较了两种高压直流输电系统换相失败判别方法:最小关断角判别和最小关断面积判别;为了提高逆变站抑制换相失败的能力,提出了最小关断面积控制策略。以林枫直流为研究对象,在PSCAD/EMTDC中建立了相应的控制保护模型,对最小关断角控制策略和最小关断面积控制策略进行对比实验。仿真结果表明最小关断面积控制策略抑制换相失败的效果优于最小关断角控制;交流电压跌落幅度过大,换相失败无法避免。

According to commutation process of inverter, the mechanism of commutation failure is analyzed. Two methods to distinguish commutation failure in HVDC transmission system are compared, which are minimum extinction angle distinguishing and minimum extinction area distinguishing. A minimum extinction area control strategy is presented to improve ability of suppressing commutation failure in inverter station. Taking Lingfeng DC project as research object, a control and protection model based on PSCAD/EMTDC is built, and control experiment with minimum extinction angle control strategy and extinction area control strategy is done. The simulation results show that minimum extinction area control strategy is more effective than minimum extinction angle control strategy in suppressing commutation failure, and commutation failure can not be avoided ifAC voltage dropped seriously.