500kV第4串三相电流不平衡原因分析及处理

Analysis and Treatment for Three-phase Current Imbalance in the 4th String Line of 500kV Part

亭卫站是上海电网500kV主网架的支撑点之一,站内500kV线路采用3/2接线方式,共有7串,8条出线,采用高压全封闭组合电器(HGIS)。针对第4串线路出现三相电流严重不平衡甚至缺相运行的现象,进行了故障分析和隐患排摸,确诊为缺相运行的主要原因是HGIS隔离开关传动连杆走偏,导致隔离开关合闸不到位,使得动静触头没能完全接触,由于接触面过热部分烧熔,造成接触电阻增大,最终电流为零。经过厂家及时处理,恢复了线路正常运行。

Ting Wei substation is one of the 500 kV main network supporting points of the Shanghai Power Grid. 500 kV part adopts the 3/2 connection mode with a total of 7 string and 8 outgoing lines, and uses hybrid gas insulated switchgear （HGIS）. In view of the serious three-phase current imbalance, even phase- deficient operation for the 4th string line, failure analysis and troubleshooting are carried out. The main reason is the HGIS disconnector linkage deviation, which results in the disconnector closing not in place, the moving contact and stationary contact not full engagement. Part of the contact surface are melt due to overheating, resulting in increased contact resistance, and finally zero current. After a timely process by the manufacturers, the line is restored to normal operation.