一起线路高阻接地故障引起的主变越级跳闸事故分析

Analysis on Over Tripping Accident of Main Transformer Caused by a Line High Resistance Grounding Fault

线路发生高阻接地故障时,由于故障特征不明显,难以实现单端电气量的保护装置全线可靠速动,甚至可能无法识别出故障。文中介绍了一起110 kV线路单相高阻接地故障,对故障后相关线路、主变压器的保护动作进行了详细分析,指出了故障原因,得出了非稳定性和稳定性高阻接地故障时保护装置都可能拒动,其选择性、灵敏性都难以满足要求的结论。

When the high resistance ground fault occurs in the line,the fault characteristics are not obvious.At present,it is difficult for the protection device with single terminal electric quantity to realize the reliable and quick operation of the wholeline,and identify the fault.This paper introduces a single-phase high resistance grounding fault of 110 kV transmission line,analyzes the protection action of relevant lines and main transformer after the fault,points out the fault cause.It draws a conclusion that when the high resistance grounding fault is unstable and stable,protection devices may be refused to move,and its selectivity and sensitivity is difficult to meet the requirements.