线路零序Ⅰ段方向过流保护误动原因分析

摘要

针对110 kV变压器中性点不接地系统中,由于线路区外发生单相接地故障导致零序Ⅰ段方向过流保护误动问题,对零序电压及零序电流的产生原因进行分析,找出误动原因及对策。分析结果表明：系统母线零序电压过大造成变压器中性点间隙击穿放电是导致零序方向过流Ⅰ段保护误动的主要原因。%Aiming at the problem of the single phase earth fault happened outside the work area leading to the zero sequence I section direction overcurrent protection device misoperation in neutral point unearthed system of 110 kV transformer,analyzes the occurred reasons of the zero sequence voltage and current,finds out causes of the misoperation and countermeasures.the result of analysis shows that the the high zero sequence voltage of the system bus caused the transformer neutral point gap breakdown and discharge is the main reason of zero sequence I section direction overcurrent protection device misoperation the high zero sequence voltage of the system bus caused the transformer neutral point gap breakdown and discharge.