A Single-Phase to Ground Fault Identification Method Based on Extremely Low Frequency Current Detection in Distribution Grids

The single-phase to ground fault (SPGF) is very common in power grids. To decrease the fault’s influence on the power supply’s reliability, the neutral point is usually grounded via the Petersen coil, significantly reducing the outage rate. Nevertheless, this coil would weaken the fault current and make the faulty line identification much more difficult. To address such an issue, an identifying method for the faulty line is proposed in this paper based on the detection of an extremely low frequency current(ELFC), after analyses are made on the electrical signal’s characteristics when the fault exists based on a common physical model of a medium-voltage distribution system. Then, to coordinate with this method, a set of devices are developed to accurately measure the ELFC and ensure feasibility. At last, a simulation and an experiment are conducted, and the results prove this method’s validity in the identification of a faulty line.