High-Impedance Fault Detection Based on Single-Phase Instantaneous Reactive Power Theory

In a Low-Resistance Grounding System (LRGS), it is difficult to detect a high-impedance fault (HIF) using conventional over-current protections because of its low fault current. In this paper, a novel HIF detection method based on singlephase instantaneous reactive power theory (SPIP) is proposed. Because low resistance only exists in the network through which the faulty feeder zero-sequence current flows, the fundamental power factors between a faulty feeder and a healthy feeder are completely different. According to this difference, the proposed method calculates the power factor of the feeder rapidly with the use of SPIP and introduces the 4th harmonic in instantaneous active and reactive power to assist in the determination. The simulation in PSCAD verifies the validity of the proposed method. The proposed method shows high performance in both linear fault resistance grounding fault and arcing fault, and its sensitivity is affected by fault resistance only slightly.