Single‐Phase Ground Fault Current Mitigation in Distribution Network Considering the Influence of Grounding Grid Resistance

ABSTRACT Existing single‐phase ground fault mitigation device (SPGFMD) is usually equipped with a grounding terminal, but the resistance of the grounding grid may change during the long‐term operation of the power system. To analyze the influence of the grounding grid resistance on the effectiveness of ground fault current mitigation, the relationship between the grounding grid resistance and the residual ground fault current is derived. This article conducts simulation and experiment to investigate the impact of various grounding grid resistances on the suppression effect of ground fault current under different ground transition resistance circumstances. The critical grounding grid resistance that affects the single‐phase ground fault current mitigation effect has been identified, offering a theoretical foundation for the on‐site evaluation of the grounding grid status of SPGFMD. The influence mechanism of grounding grid resistance is verified by the simulation and experiment results. The results indicate that the SPGFMD with current‐based method can withstand a certain range of grounding grid resistance variation under the condition of a single‐phase ground fault in the distribution networks. However, the effectiveness of ground fault current mitigation deteriorates when the grounding grid resistance exceeds the critical threshold.