同杆线路零序互感对纵联零序保护的影响

Influence of Zero Mutual Inductance on the Pilot Zero Sequence Protection in Multi-circuit Lines on the Same Tower

由于同杆线路故障时电磁耦合的特殊性,纵联零序保护误动的情况时有发生,而其零序方向元件在故障位置的判断中起着关键的作用。双回线系统发生接地故障时,由于零序互感的影响,零序功率方向元件不能正确判断故障发生的位置,导致纵联零序保护误动。结合电网运行实际,基于不用运行方式和同杆架设形式,对不同运行方式下零序互感对纵联零序保护的影响进行了分析。结果表明,在特定电气参数及运行方式下,纵联零序保护可能误动。通过PSCAD仿真,验证了分析的正确性。

Because of the complexity of electromagnetic coupling,mal-operation of pilot zero sequence protection happens occasionally in multi-circuit lines on the same tower.The zero sequence directional relay,plays a key role in fault locating,can＇t identify the fault location with the influence of zero mutual inductance,and potentially lead to mal-operation.Considering the inherence of power system states,analysis of the influence from zero mutual inductance on the zero sequence directional relay is given based on the various operating modes and arrangements of multi-circuit lines.The results show that mal-operation of pilot zero sequence protection happens at the special operating modes and parameters.At last,the PSCAD simulation results prove the analysis is correct.