平行互感线路纵联零序方向保护动作行为分析

通过电磁暂态仿真和向量图定性分析相结合的方法,详细分析了无电磁联系、弱电强磁联系和强电强磁联系三种情况下,两平行互感线路在接地故障时其四个端口的零序电流、电压之间的相位关系,从而得出两平行互感线路纵联零序方向保护在没有电联系的非故障线路一定会误动,弱电强磁联系的非故障线路误动的可能性较大,强电强磁联系的非故障线路一般不会误动的分析结论。另外,还给出了弱电强磁联系的非故障线路的某一端综合零序电压或电流有可能等于零或者接近于零的情况的分析结论。

Behavior Analysis on Zero-sequence Pilot Protection of Parallel Mutual Inductance Transmission Lines

Based on the methods of electromagnetic transient simulation and vector qualitative analysis,this paper analyses the phase relationships between zero-sequence current and voltage under the conditions of non-electrical connections,electrically weak and magnetically strong connections and strong electromagnetic connections.The analysis leads to the conclusion that when there is no electrical connection,malfunction will occur on the protection with transmission line under normal conditions;malfunction will much more probably occur when lines without faults are under magnetically strong and electrically weak connections;and malfunction will not occur when lines without faults are under strong electromagnetic connections.In addition,zero-sequence voltage or current of the non-fault lines which have magnetically strong and electrically weak connection may be zero or close to zero.