Analysis of High Impedance Faults Current Using Fourier, Wavelet and Stockwell Transforms
Detection of high impedance faults (HIFs) in distribution systems is a challenging task, which has attracted the interest of the researchers for decades. The HIF current random behavior and its low
magnitude cause difficulties for a reliable detection by traditional protection methods. Therefore, the hazards for grid devices, people and animals safety, associated with HIFs, motivate the research of new detection techniques. However, there is no fully efficient solution for this problem. In this context, this paper aimed to characterize HIFs by a set of real measurements considering different type of soils employing Fourier (FT), Wavelet (WT) and Stockwell Transforms (ST). The measurements were performed at the fault spot in a medium voltage test field specially built for this purpose. The idea is to highlight key characteristics of the HIF current waveforms pointed out by each of transform and assess which ones can be used as a promising tool for HIF detection. The results showed that the HIF current can be characterized by the interharmonic behavior during the fault, extracted by FT and by the high degree of energy variations at specific decomposition levels of WT and ST.