平行双回线路高阻接地故障保护的新思路

通过实例分析说明平行双回线路在强磁弱电联系运行方式下,一回线路末端发生高阻接地故障时,非故障线路纵联零序方向保护会误动,而纵联负序方向保护不会误动,提出在使用纵联零序方向保护切除高阻接地故障的保护装置中,增加纵联负序方向保护,退出纵联零序方向保护以防止误动的发生,并讨论了纵联负序方向保护新方案,方案增加负序电抗继电器和负序电流、电压闭锁,并带小延时动作,从而确保平行线之一故障时,非故障线路纵联负序方向保护不会误动,而故障线路发生高阻接地故障时,纵联负序方向保护能带小延时可靠切除故障.

New Protection Scheme for High Resistance Ground Fault on the Parallel Double-circuit Transmission Lines

Operational experiences indicate that when a high resistance ground fault occurs on one of two parallel double-circuit lines under the strong-magnetic and weak-current operation condition,the pilot zero sequence directional protection of the non-fault line may mal-function while the pilot negative sequence directional protection will not.If a pilot negative sequence directional protection is used to replace the zero sequence one,the mal-function caused by high resistance ground faults can be avoided.A new pilot negative sequence directional protection scheme is also presented,which combines a negative sequence reactance relay,negative sequence current and voltage blocking,and a short time delay.The scheme can avoid mal-function of the protection on the non-fault line and isolate the faulty line reliably.