防止500kV线路单相接地保护故障误动的规范校验方法

A Standard Check Method to Prevent the 500kV Line Protection from Maloperation for Single-phase Ground Fault

华中电网某500 kV线路发生单相接地故障时,线路上一变电站开关单跳后直接三跳,重合闸未动作。通过事故调查发现常规单套保护检验方法难以发现保护在相互配合中出现的不能正确动作的问题。文中给出防止类似事故发生的规范校验方法:装置检验过程中,需以"模拟两套保护同时动作"的方式检验装置功能与回路配合的正确性,并在串联校验过程中要注意断开二套保护屏中的TA接地点,以保证串联校验零序和单相接地保护能够正确动作。

During a Single-phase ground fault occurring on a 500 kV line in Central China Power Grid, the single-phase and three-phase circuit breaker tripped successively without reclosing. Through the investigation of the accident,using the routine check method, as with checking single-set of protection,it＇s hard to find out the problem of maloperation due to the coordination among the protections. This paper gives a standard check method to prevent similar accident. During the check process, it is necessary to simulate that two sets of protections are simultaneously operating to check the correctness of their functions and circuits coordination. In the series check process, the TA earthing points of two sets of protections in cubicles should be broken off with attention to ensure the correct operation for series checking zero sequence and single phase ground protection.