High-voltage direct current power transmission line protection method based on wavelet transformation and energy spectrum analysis

The invention discloses a high-voltage direct current power transmission line protection method based on wavelet transformation and energy spectrum analysis. According to the method, a starting criterion is formed through setting a threshold value on the voltage fluctuation, the frequent starting of a protection device caused by system voltage non-fault fluctuation is prevented, and in addition, the reliable starting can be realized when a direct current power transmission line fails; a fault voltage traveling-wave head wavelet transformation metatype maximum value polarity comparison method is utilized for distinguishing in-area and out-area faults; the energy distribution features of transient voltage in different frequency bands are utilized for distinguishing the fault and the lightning stroke interference, and meanwhile, fault poles and perfect poles of a double-pole system are identified.