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. Phase-comparison method: For neutral non-grounded systems, comparing the zero-sequence voltage of buses with the amplitude and phase of zero-sequence current of all lines, the phase of zero-sequence current of fault lines should lag 90 degrees behind the zero-sequence voltage of normal lines and reverse phase with zero-sequence current of normal lines. If zero-sequence current of all lines is in phase, the buses are grounded.
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. Catastrophe method: Parallel reactor and switch are connected on both sides of arc suppression coil. Parallel reactor is not put into operation in normal operation. After permanent grounding fault occurs, the parallel reactor is put into operation for a short time, and then disconnected for several seconds. This sudden change of zero-sequence current can only be reflected in the fault 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. First half-wave method: In the first half cycle of fault, the zero-sequence current of fault line is opposite to the zero-sequence current polarity of normal line, so the fault line can be selected by comparing the zero-sequence current polarity 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 the neutral grounding system through arc suppression coil, the active component of zero sequence current of fault line is opposite to the polarity of normal line, which 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. Harmonic amplitude comparison method: For the neutral grounding system through arc suppression coil, the arc suppression coil is under-compensated for the harmonic component. If there are abundant harmonic components in the zero sequence current of the line, the amplitude and phase of the harmqitixielou.37ix.com.cnbileiqi.37ix.com.cntanceqi.37ix.com.cnlingxu.37ix.com.cnguodianya.37ix.com.cn baohuqi.37ix.com.cnonic component of the zero sequence current of all lines are compared. The amplitude and phase of the zero sequence current of the fault line are larger and should be inversely phased with the zero sequence current of the normal line, if all lines have abundant harmonic components. If the zero sequence current of the circuit is in phase, the bus is grounded.