基于零序导纳幅值比的同母两回线异相接地复故障选线方法

Fault line selection method for earth faults occurred in different phases of two feeders connected to the same bus based on the ratio of zero-sequence admittance amplitude

消弧线圈接地系统发生同母两回线异相接地故障时,常规选线装置存在准确率不高的问题。针对消弧线圈接地系统发生的同母两回线异相接地复故障选线难的问题,文中通过线路首端的零序电流和母线零序电压信息获得线路的零序导纳,分析消弧线圈接地系统发生同母两回线异相接地故障特征,发现故障线路零序导纳的幅值大于非故障线路零序导纳的幅值,在高阻接地时仍呈现出此特征。在此基础上提出了基于零序导纳幅值比的消弧线圈接地系统同母两回线异相接地复故障选线方法,利用故障线路与非故障线路零序导纳幅值的差异建立故障选线判据,将所有故障线路全部选出。PSCAD仿真结果表明,该选线方法准确率高,不受故障位置、消弧线圈补偿度的影响,具有较强的耐受过渡电阻的能力。

When the earth faults occur in different phases of two feeders connected to the same bus in the resonant grounding system,the conventional fault line selection devices are inaccurate.To address the difficulties of fault line selection in the earth faults that occurred in different phases of two feeders connected to the same busbar for resonant grounding system,the line zero-sequence admittance is calculated by the zero-sequence current at the first end of the line and the zero-sequence voltage of the bus.The analysis of the fault characteristics indicates that,the zero-sequence admittance amplitude in faulty lines is larger than that in the non-faulty line,and this characteristic also appears in the high-impedance grounding faults.Based on the ratio of zero-sequence admittance amplitude,a fault line selection method for earth faults occurring in different phases of two feeders connected to the same bus in a resonant grounding system is proposed.The difference in zero-sequence admittance amplitude between fault and non-fault lines is used to establish a line selection criterion,which allows all fault lines to be selected.The results simulated by PSCAD confirmed that the proposed method works effectively,with high accurary.This method is not affected by the fault location and the compensation degree of the arc suppression coil,and it can also withstand high fault resistances.