A leakage protection method for low-voltage power supply systems based on flexible regulation of the neutral point voltage

Abstract

Low-voltage power supply systems, which are very prone to leakage faults, are deep in the customer terminal, and the operation environment is complex. The traditional leakage protection devices applied in TN-S systems cannot isolate single-phase leakage faults while maintaining power supply. Thus, a leakage protection method based on flexible regulation of the neutral point voltage for a low-voltage power supply system is proposed. By extracting the potential of the fault phase, using a single-phase regulating transformer to reverse the voltage applied between the zero line and the protection ground line, and adjusting the ratio of the single-phase regulating transformer to regulate the fault phase to ground voltage, the fault phase to ground voltage is suppressed to 0 V and the leakage fault residual current is eliminated. In the PSCAD/EMTDC simulation environment and in a 10 kV real-type distribution network laboratory, a TN-S system model was built to simulate various fault conditions. The simulation and experimental test results show that the method can actively isolate single-phase leakage faults and eliminate potential leakage problems without affecting the power supply of users.