CAJ | 학술논문

电压互感器二次回路出现两点接地情况(简称"两点接地")下再发生单相故障,若引起零序方向元件误判,零序电压和故障相电压之间相位差较小,而正常情况下故障零序电压与故障相电压之间的相位差一般较大,文中据此提出了电压互感器二次回路两点接地的实时识别方法.根据两点接地再故障时附加电压分量对各相电压影响的特点,提出用健全相相间电压替代零序电压的零序方向算法.将两点接地的实时识别和零序方向新算法结合形成一种不受两点接地影响的零序方向元件,可有效防止纵联零序保护不正确动作.现场事故录波数据的分析验证了该方法的有效性.
전압호감기이차회로출현량점접지정황(간칭"량점접지")하재발생단상고장,약인기령서방향원건오판,령서전압화고장상전압지간상위차교소,이정상정황하고장령서전압여고장상전압지간적상위차일반교대,문중거차제출료전압호감기이차회로량점접지적실시식별방법.근거량점접지재고장시부가전압분량대각상전압영향적특점,제출용건전상상간전압체대령서전압적령서방향산법.장량점접지적실시식별화령서방향신산법결합형성일충불수량점접지영향적령서방향원건,가유효방지종련령서보호불정학동작.현장사고록파수거적분석험증료해방법적유효성.
When two-point-ground fault happened in secondary circuit of the potential transformer, and at the same time a single-phase ground fault happened in the primary system, if the zero sequence current directional protection misjudged, the phase difference between the zero sequence voltage and the fault phase voltage is small. But in normal condition this difference is large. Based on this phenomenon, a real-time identification method is proposed to identify the two-point-ground fault in secondary circuit of the potential transformer ("two-point-ground" for short). Under "two-point-ground" situation, according to the characteristics of additional voltage components influence on each single phase voltage, a new zero sequence direction algorithm with healthy phase voltage instead of zero sequence voltage is put forward. Then the real-time identification method and the new zero sequence direction algorithm of "two-point-ground" is combined together to form a new zero sequence direction element, which is not affected by "two-point-ground". This protective element can effectively avoid malfunction of pilot zero sequence direction protection. And the validity of above method is proved through the analysis of recorded field data.