二次电压回路隐性故障的识别及仿真

Identification and Simulation of Midden Faults in Secondary Voltage Circuit

通过分析PT二次回路两点接地后发生系统接地故障的故障特征,总结PT二次回路两点接地判别的传统方法。针对该方法的不足,提出改进判据,构建参考零序电压公式,作用于PT二次回路两点接地后发生系统接地故障时,零序方向保护能正确动作,并通过PSCAD仿真验证该结论的正确性。

By analyzing the fault characteristics of system ground fault after the two point grounding of the PT secondary circuit.the traditional method of two-point grounding discrimination of the PT secondary circuit is summarized.In view of the shortcomings of this method,an improved criterion is proposed and a reference zero sequence voltage formula is con structed.When the system grounding fault occurs after the PT secondary circuit is grounded at two points,the zero se­quence directional protection can act correctly.PSCAD simulation verifies the correctness of this conclusion.