一起110kV线路零序保护拒动分析

Analysis of zero-sequence protection resist-operation in 110kV line

2008年4月在对一条新上的110kV线路保护进行测试时,发现零序保护一直拒动,通过对二次接线、试验仪器及装置本身的仔细检查,排除了二次接线、仪器及保护装置本身的问题,最终发现设计二次接线与典型接线不同,导致外接零序电流未接入保护装置,从而引起了零序保护的拒动。并进一步分析了微机保护采用自产零序电流、电压工作,同时还要使用外接零序零序电流的原因及作用。

A new 110 kV line protection is tested in April, 2008, to fred zero-sequence protection always resist operating. Checking the secondary connection, test equipment and the device, no fault is found. Finally, the error is found. The secondary connection is different with the typical connection, thus the protection device has no external zero-sequence, so zero-sequence protection always resists operating. This paper analyses the self-produced zero-sequence current and self-produced zero-sequence voltage. Finally, the paper describes the reason and function of using external zero-sequence current.