换流器阀侧零序电压保护异常原因分析及对策

Cause Analysis and Countermeasures on Maloperation of Zero-sequence Voltage Protection at Converter Valve Side

通过对一起舟山±200 kV多端柔性直流输电工程换流站启动试验中换流器阀侧零序电压保护的异常动作波形分析,找到保护动作异常的原因是:在有源HVDC(高压直流输电)运行模式下,换流阀不控充电完成后,充电电阻旁路闸刀三相不同步合闸产生的零序基波电压将大于保护定值。分析表明,抬高零序电压保护动作定值,同时加入三次谐波制动判据,可以有效防止换流器阀侧零序电压保护误动。

The paper introduces maloperation of zero-sequence voltage protection at converter valve side dur- ing startup test in converter station of Zhoushan _＋200 kV multi-terminal VSC-HVDC project. By waveform analysis, it is found that in the operation mode of active HVDC when uncontrolled charging of converter valve is finished, zerosequence voltage of fundamental wave caused by three phase asynchronous closing of charging resistor bypass switch is larger than the protection setting. The analysis shows that protection maloperation of zero-sequence voltage at converter valve side can be effectively prevented by means of rising the protection setting of zero-sequence voltage and adding criterion of third harmonic restraint.