200kV直流电子式电压互感器测量故障分析与处理

Analysis and Treatment of Measurement Faults of 200kV DC Electronic Voltage Transformer

根据一起±200kV EVT(直流电子式电压互感器)出现后台显示电压偏高的现象,经设备故障分析与现场检测,查证了故障发生的原因是EVT的电阻盒内部6路并联分压电阻中的最后1路电阻击穿开路,导致EVT的直流高压分压器输出信号进行二次分压时产生异常信号,并通过光纤传输至合并单元及直流控制保护系统,出现后台电压测量异常并导致保护误动,提出了对应的防范措施。

This paper is based om a case of overvoltage of ＆#177;200 kV DC EVT （electromic voltage tramsformer） displayed om the backstage. Through fault amalysis of equipmemts amd field test, it was foumd amd proved that the primary cause of the equipmemt fault is that the last ome of six parallel divider resistamces broke dowm the opem circuit im the resistamce box of the EVT, due to which the output sigmal became abmormal durimg voltage dividimg im DC high voltage divider of EVT; besides, the abmormal sigmal was tramsferred through optical fiber to mergimg umit amd DC comtrol amd protectiom system, thereby the voltage measured at the backstage was abmormal amd led to protectiom malfumctiom. This paper proposes correspomdimg precautioms accordimgly.