220 kV主变保护在旁路代运时的若干问题探讨

Analysis of some problems on 220 kV transformers in bypassing transformer's breaker

在主接线形式为双母线带旁路的变电站操作中,转带操作占有很大比重,对于220 kV主变,在高压侧开关停电检修时由旁路开关代运的情况下,提出了220 kV变电站旁路开关代主变开关运行时存在保护死区的问题,如不切换主变高压侧失灵保护回路,则无法正确启动断路器失灵保护,提出了220 kV旁路代运时主变失灵回路的改造方案。并要求在旁路代运时,注意差动保护的电流切换和保护操作。

In substations with double busbar and bypass system,the operation using bypass circuit breaker to substitute a line circuit breaker is often needed. For the 220 kV transformers,when the higher voltage breaker is replaced by bypass breaker, how to eliminate the protection＇s dead-zone when by-pass circuit breaker replaces the CB of 220 kV main transformer, is presented, The breaker failure protection may startup incorrectly if the startup circuit of higher voltage breaker failure protection is not switched on. This paper brings forward a modified scheme to the startup circuit of failure protection for 220 kV transformers. In bypassing transformer＇s breaker, attention should be paid to the current switching and operation of the differential protection.