High Resistance Grounding Fault Detection Method Based On Odd Harmonic Morphology

High impedance fault (HIF) is one of the most common faults in smart distribution grid. When HIF occurs, the fault harmonic generated by HIF has a significant impact on the safety of power grid. The arc phenomenon accompanying HIF will also pose a threat to personal safety and cause significant economic losses. Therefore, HIF detection is very important for smart distribution grid. a HIF detection method based on odd harmonic morphology is proposed solving weak high resistance grounding fault current, difficult fault identification and low accuracy. Firstly, variational modal decomposition (VMD) optimized by chimpanzee optimization lgorithm(ChOA) is used to decompose the waveform, and multiple intrinsic modal functions (IMF) are obtained. Non odd harmonic components are screened by the minimum center frequency method and t-test statistic method; Calculate the upper root mean square envelope of all the remaining IMF and perform binarization. The purpose of detecting HIF was achieved by judging the mutation times of binary signal. The simulation deduce from that the high accuracy can be maintained applying the proposed detection method under the condition of noise interference and harmonic interference, a promotive to ameliorating the reliability and security of distribution grid.