A Fault Section Location Method for Small Current Grounding System Based on HHT

A fault section location method for small current grounding system based on Hilbert-Huang Transform (HHT) is proposed. When a single-phase grounding fault occurs in the distribution network, the transient zero sequence current uploaded by the FTU on the feeder is decomposed by empirical mode decomposition (EMD) to obtain a limited number of intrinsic modal function (IMF) components, from the high frequency to the low frequency. Select the highest frequency IMF component for Hilbert transform to detect the instantaneous frequency saltation point and mark it as the fault time. Find the first-order difference value of the highest frequency IMF component at the fault time, and find the difference product between the adjacent detection points. The positive and negative values form the section location criterion. This section location method is not affected by the grounding transition resistance, fault location, and fault angle. The effectiveness of the method is verified by simulation analysis.