Single-phase earth fault section location based on wavelet packet energy relative entropy in distribution network

The transient zero sequence current waveforms show a great discrepancy on both sides of the fault point, and have different energy distribution at different frequencies, when single-phase earth fault occurs in distribution network. Wavelet packet energy relative entropy is defined to distinguish the differences combined with the information entropy and wavelet packet decomposition, realizing fault section location. The energy spectrum distribution characteristics of the transient zero sequence currents from FTU or other measurement device in feeder automation system are obtained based on the wavelet packets decomposition. Then the relative entropy of the zero sequence currents on both ends of every section is calculated. Comparing the results, the entropy of the fault section is the maximum. The influence of non-synchronous sampling is avoided by selecting the maximum energy data segment of transient zero sequence current to calculate relative entropy. This method is immune to transition resistance, fault position, and fault angle, and its effectiveness is proved through the simulation.