一起220kV主变差动保护异常跳闸的分析

Analysis on an Abnormal Tripping of Differential Protection of 220 kV Main Transformer

通过对一起220 k V主变差动保护RCS978异常跳闸的现场检查和差动电流波形分析,发现差动电流回路存在两点接地,在受外界干扰时造成了差动保护的误动。揭示电流回路两点接地对继电保护系统的危害,为主变保护异常跳闸特别是大电流试验端子引起的保护误动事故的处理分析提供借鉴。

By field detection and analysis on differential current wave after abnormal tripping of differentialprotection RCS978 of 220 kV main transformer, it is founded that there is two-point grounding in differentialcurrent circuit,which results in misoperation of differential protection in case of external interference. Thepaper expounds harm of two-point grounding of current circuit to relaying protection system and hence pro-vides reference for handling and analysis of abnormal tripping of differential protection of main transformer,especially protection misoperation accident caused by large-current testing terminals.