基于正序电压替代的零序功率方向补充比相方案

A New Supplement Scheme of Zero Sequence Directional Pilot Relay Based on Positive Sequence Voltage Replacement

输电线路发生接地故障时,可能因零序电压不满足灵敏度要求,导致零序方向元件不能正确动作。针对上述问题,文中系统阐述了各种不对称接地故障下,系统各点故障前后正序电压的相位偏差、过渡电阻对各序分量相位的影响、正序与零序电压间最大相位偏差、送端与受端功角对该相位差的影响等,并据此提出了零压不够时采用正序电压代替零序电压进行比相的补充方案。理论研究及实时数字仿真系统(RTDS)仿真表明,新方案区外故障时不误动,区内故障基本正确动作,从而较大程度地改善了零序方向保护的整体性能。

To address the problem of zero sequence direction relay＇ s non-operating under the zero sequence voltage＇ s threshold, a new method of phase comparison is presented by using positive sequence voltage instead of zero sequence voltage, Based on the systematic exposition of phase deviation of positive sequence voltage between pre and post fault, the effects of fault resistance to positive sequence, negative sequence and zero sequence component, the maximum phase deviation of positive sequence voltage and negative sequence voltage caused by fault resistance, and the effects of sending and receiving ends powerangle of power grid on the phase deviation are systematically described when asymmetrical earth fault occurs. The research result shows that when using the new method, real-operation will not happen under external faults, and operation will be correct under internal faults except some special cases.