High-impedance ground faulted line-section location method for a resonant grounding system based on the zero-sequence current's declining periodic component

摘要

The probability of single-phase high-impedance faults (HIFs) in a resonant grounding system is high, and the existing fault detection and line-section location methods have drawbacks such as low accuracy and implementation difficulties. In this paper, an efficient method based on the zero-sequence current's declining periodic components is presented to locate a high-impedance ground faulted line-section for resonant grounding systems. It analyses the parallel resonance process when a single-phase HIF occurs in a resonant grounding system. The distribution characteristics of the declining periodic component of the zero-sequence current at the fault point are studied. Moreover, we indicate that the zero-sequence current's declining periodic components upstream and downstream of the fault point have large differences in phase. By utilizing this feature, a novel high-impedance ground faulted line-section location method is proposed. This method uses feeder terminal units (FTUs) to obtain the declining periodic components in phase based on the extended Prony method and a distribution automation master station to estimate the transition resistance; then, the protection criterion established by using the phase difference and fault resistance can be applied to identify the fault line-section. Based on a real-time digital simulator (RTDS) and the FTU developed with a faulted line-section location function, the proposed method is verified. The experimental results show that the scheme has good feasibility.