500kV变电站3/2接线T区短引线保护方案探讨

Discussion on 3/2 connection T wiring short-lead zone protection scheme in 500 kV substation

针对500kV变电站3/2接线方式下采用GIS组合电器时,为了防止GIST区母管发生永久故障时线路保护重合于故障引起GIS母管的再次受损,通常采用出线配置CT线路保护动作范围不包含GIS串内CT与出线CT之间故障的方式来实现,因而针对GIS串内CT与出线CT之间T区故障需考虑配置完备的保护方案;本方案采用三端差动保护方案完成线路投入运行方式下T区故障的保护,采用两端差动保护方案完成对线路退出运行方式下线路隔刀及3/2串内CT之间故障的保护,采用配置过电流原理的线末保护完成对线路退出运行方式下线路隔刀及出线CT之间故障的保护;本方案已在500kV变电站成熟应用,具有广泛推广的现实意义。

When GIS switchgear used in 500kV substation with the configuration of the 3/2 CT connection mode, for preventing from GIS main pipe derided once again by line relay reclosing on permanent fault on GIST zone main pipe, the scheme that line relay acting range of line configure CT does not contain GIS string inside CT and CT lines between the T zone, then according to T zone fault in GIS string inside CT and CT lines between the T zone, the complete protection scheme needs to be configured. The paper puts forward a scheme for using three-terminal differential relay to protect the T zone fault with line put into running, and using two-terminal differential relay to protect the fault between line isolator and 3/2 string inside CT with line quit running, and using terminal line protection with over-current relay to protect the fault between line isolator and CT lines between the T zone with line quit running. The scheme has been maturity applied in 500kV substation, so it can be extended widely.