Neutral line anomaly judgment method based on non-fault phase second harmonic component proportion

The invention relates to a neutral line anomaly judgment method based on a non-fault phase second harmonic component proportion. The method comprises the following steps: identifying a non-fault phase in each phase line, and obtaining a second harmonic component proportion in a secondary current of the non-fault phase; when the proportion of the second harmonic component in the at least one non-fault-phase secondary current is greater than the first proportion value, acquiring a secondary zero-sequence electric signal; and according to the secondary zero-sequence electric signal, determining the abnormal type of the neutral line. The proportion of the secondary harmonic component of the secondary current corresponding to the non-fault phase of the three-phase power supply system is used as the judgment basis of the abnormality of the neutral line, a secondary zero-sequence electric signal is further obtained, and the abnormality type of the neutral line is analyzed based on the secondary zero-sequence electri