“直流接地查找设备”对保护误动的分析

Analysis of DC Ground Search Equipment to Protection Misoperation

变电站直流系统接地会导致继电保护的误动作,对电网的可靠性运行危害极大。当发生直流接地时,为了快速、准确地找到接地点,除了常规的直流拉路排除法外,最普遍的方法就是使用"直流接地查找设备"对各个直流回路进行排查,找到并消除接地点。但"直流接地查找设备"的原理及工艺不一,有可能在接地查找过程中发生继电保护误动的现象。本文就"直流接地查找设备"的工况,对现场发生实际接地的各种状态量进行分析,研究发生保护误动作的原因,并提出使用"直流接地查找设备"的工作流程。

The grounding of substation DC system will lead to malfunction of relay protection,it greatly harms to power system reliability running.When the DC grounding,in order to find the ground quickly and accurately,the most common way is to use the＂DC ground search equipment＂ in checking each DC circuit besides the conventional DC pull road,find and eliminate the site.But the＂DC ground search equipment＂may cause relay malfunction because of the differences of the principle and technics.This paper analyses actual ground state variable occurred on site,researches the causes of relay malfunction,and brings forward the working flow of using DC ground search equipment.