应用矢量图判别接地相的方法探讨

EXPLORATION ON WAY OF DISCRIMINATING EARTHING PHASE BY APPLICATION OF VECTORGRAM

在中性点非直接接地电网中,绝大部分系统故障是单相接地故障。本文通过对单相接地故障的分析研究,总结出地电位(D)轨迹与系统电动势(E)之间,随系统参数、接地电阻变化的特性规律,利用该规律可在三相矢量图上迅速准确地判断出接地故障相,克服了仅用零序电压方向判断接地故障相可能产生的误差,提高了判断接地故障相的准确性,为系统及时采取防止过电压和消除单相接地故障措施提供了必要条件。

Because most of failures are single-phase earthing failures in neutral non-direct earthing electric network, this paper sums up the characteristics law between earth potential trace and electromotive force and changeable law of earthing resistance with changes of system parameters based on the analysis and study on single-phase earthing failure. The earthing fault phase can be discriminated on three-phase vectorgram rapidly and accurately by application of the law. In this way, the possible error caused by application of null sequence voltage to discriminate earthing failure can be eliminated, the accuracy of discriminating earthing fault phase can be improved and the necessary conditions are provided to the system for preventing over voltage and eliminating single-phase earthing failure.