1、比相法：对于中性点不接地系统，比较母线的零序电压和所有线路零序电流的幅值和相位，故障线路零序电流相位应滞后零序电压90°并与正常线路零序电流反相，若所有线路零序电流同相，则为母线接地。

1, the phase comparison method: for non grounding system, comparing the bus zero sequence voltage and zero sequence current all amplitude and phase, the fault line zero sequence current phase lag should be 90 degrees and zero sequence voltage and zero sequence current in normal phase, if all zero sequence current phase for bus grounding.

2、突变量法：在消弧线圈两侧并联电抗器和开关，正常运行时并联电抗不投入运行，发生永久性接地故障后将并联电抗短时投入，持续几秒再断开，使零序电流发生较大的突变量，这个突变的电流只会在故障线路中体现出来。

2, the amount of mutation method: in Petersen coil on both sides of shunt reactor and the switch, the normal operation of shunt reactor not put into operation, a permanent grounding fault will shunt reactance short-term investment, for a few seconds and then disconnect the zero sequence current mutation in large amount, the mutation will be reflected in the fault current only line.

3、首半波法：发生故障的最初半个周波内，故障线路零序电流与正常线路零续电流极性相反，因此可以通过比较首半波的零序电流极性进行故障选线。

3, the first half wave method: in the first half week of the fault, the zero sequence current of the fault line is opposite to the zero current of the normal line, so the fault line selection can be done by comparing the polarity of the zero sequence current of the first half wave.

4、有功分量法：对于中性点经消弧线圈接地系统，故障线路的零序电流的有功分量与正常线路极性相反，可以用这个特点进行选线。

4, active component method: for neutral point grounding system with arc suppression coil, the active component of fault sequence's zero sequence current is opposite to the normal line. This characteristic can be used for line selection.

5、谐波比幅比相法：对于中性点经消弧线圈接地系统，对谐波分量来说消弧线圈处于欠补偿状态，如果线路零序电流中含有丰富的谐波成分，则比较所有线路零序电流谐波分量的幅值与相位，故障线路零序电流幅值较大且相位应与正常线路零序电流反相，若所有线路零序电流同相，则为母线接地。

5, the harmonic amplitude and phase comparing method for neutral grounding via arc suppression coil system, the harmonic component for coil in a starved condition, if the rich harmonics of the zero sequence current, comparison of amplitude and phase of all line zero sequence current harmonic component, the fault line zero sequence current high amplitude and phase should the normal line and zero sequence current phase, if all zero sequence current phase for bus grounding.