High Impedance Fault Detection and Discrimination Using a Wavelet Packet Transform-Based Algorithm

High Impedance Fault Detection and Discrimination Using a Wavelet Packet Transform-Based Algorithm

High-impedance faults (HIFs) on power transmission systems are one of the great challenges to protection engineers. HIFs do not cause that much fault current to be detected by conventional relays. This paper presents an algorithm for high impedance fault detection and zone discrimination in high voltage transmission lines which is evaluated by EMTP simulation studies. The scheme recognizes the distortion of voltage and current waveforms caused by HIF. Wavelet packet transform (WPT) is firstly applied to extract the special features of three phase voltages and currents in the high frequency range which are sent to a classifier for fault detection and zone discrimination. The classifier is based on an algorithm that uses a recursive method to add up the absolute values of the high frequency signal coefficients generated over one last cycle and shifting one sample. Several simulation results, which are obtained using an appropriate model, obviously show that the proposed technique can accurately recognize the HIF in overhead transmission lines. Efficiency of the proposed algorithm from the viewpoints of dependability and security of HIF detection is verified by a comprehensive simulation study.