某风电场35kV集电线路零序保护拒动原因分析

Cause Analysis of Zero Sequence Current Protection Miss Operation of 35 kV Collector Line in Wind Farm

对某风电场35 kV集电线路零序保护拒动越级跳闸故障进行原因分析,确定故障为35 kV 1号风电机组进线28号风机箱式变压器高压电缆室电缆头施工工艺不合格,内部存在薄弱点,长期高压作用下被击穿,引发电缆L3相单相接地。同时由于35 kV 1号风电机组进线电缆屏蔽线穿越零序电流互感器接线错误,导致35 kV 1号风电机组进线零序保护拒动,1号主变压器零序保护动作越级跳闸。提出修改接线、增加自产零序电流保护等改造措施,防范类似事故再次发生。

In view of a wind farm 35 kV collecting line zero sequence protection refusing to act,the fault causes are analyzed,and the fault is determined as the unqualified construction technology of the cable head in the high-voltage cable room of No.28 fan box type transformer,and there are weak points inside,which are broken down under long-term high-voltage action,leading to the cable L3 phase single-phase grounding.At the same time,due to the wiring error of the 35 kV No.1 wind turbine incoming cable shield wire crossing zero sequence current transformer,the zero sequence protection of 35 kV wind turbine generator unit No.1 refused to operate,and the zero sequence protection action of No.1 main transformer is trip.The modification measures such as modifying wiring and increasing self-produced zero sequence current protection are proposed to prevent similar accidents from happening again.