High Impedance Faults Detection in Distribution Systems Using Signal Correlations

High impedance fault (HIF) detection is a problem in distribution power systems protection. Detection of these faults by overcurrent protection relays is difficult or impossible. Therefore, system recovery is postponed, and individuals may be exposed to the risk of electrical shock. This article defines a family of HIF current-time patterns with different ignition angles. To detect the HIF current, the proposed detection method searches in its family of HIF patterns and finds the pattern that has the highest correlation to the HIF current. Based on the measured correlations, a time-domain algorithm is proposed for the HIF current. If the highest correlation between the family of HIF patterns and the measured current signal is above a given threshold value, then the fault is detected as an HIF. Verified by simulations and experimental results, the proposed method can correctly detect HIF within one power system cycle.