A Novel Fault Section Location Method for Small Current Grounding Fault Based on Hilbert-Huang Transform with Wavelet Packet Transform Preprocessing

In accordance with the characteristic of small current grounding fault, transient zero-mode current on both sides of the healthy section having high similarity and both sides of the fault section having low similarity, this paper proposed a novel fault section location method for small current grounding fault based on Hilbert-Huang transform with wavelet packet transform preprocessing(WPT-HHT). First, as the small current grounding fault occurred, taken transient zero-mode current on both sides of the section within the first 1/2 power frequency period as fault feature. Then, using wavelet packet transform to process the transient zero-mode current to different frequency bands, a series of intrinsic mode function (IMF) components were obtained from the narrow band signals by using empirical mode decomposition algorithm, and frequency and amplitude of signals were calculated by the Hilbert transform, the time-frequency matrixes obtained by Hilbert spectrum band pass filter. Finally, calculated and compared the coefficient of various sections to determine fault section. The simulation results verified the proposed section location method in different fault angles and transition resistances.