山区35 kV电网单相接地故障类型判断方法

Judgement Method on Single-phase-to-ground Fault Type of 35 kV Grids in Mountainous Area

为了克服山区35 kV电网消弧线圈的整定与三相电压的对称不能兼顾的矛盾,有必要对单相接地故障类型进行判断。笔者通过对山区35 kV电网建立等值电路图并进行仿真分析,得出电网分别发生永久金属性接地和电弧接地故障时故障相电压的特点和区别,据此提出了一种接地故障类型判断的判据及其实现电路,并讨论了接地电阻及电弧重燃时刻对故障判断的影响。仿真显示,该判据及其实现电路对上述故障类型的判断是相当准确的,且基本不受接地电阻及电弧重燃时刻的影响。该判据及其实现电路的提出,对于降低雷击跳闸率、提高山区35 kV电网的运行水平具有重要意义。

In order to overcome the contradictory of setting the arc-suppression coil and symmetry of three-phase voltage in 35 kV mountainous area grid can not both take into account, it＇s necessary to make judgement on single-phase-to-ground fault type. In this paper, via building of equivalent circuit and simulation ＆ analysis of 35 kV grids in mountainous area, voltage features of phase respectively in the aforesaid faults have been obtained as well as the differences between them, and judgement method for fault types and corresponding circuit are proposed with the discussion of influence of grounding resistance and arc re-burn time. Simulation result indicates that this judgement method and circuit gives a good performance for the judgement of fault types, and besides, there is basically no threat to its judging result from earthing resistance and re-burn time of arc. The proposal of this judgement method and circuit is of great significance in decreasing trip-out rate ＆ improving operation level of 35 kV grids in mountainous area.