Suppression Strategy on Neutral Point Overvoltage in Resonant Grounding System Considering Single Line-to-ground Fault

Abstract

The resonant grounding system (RGS) has problems with neutral point overvoltage and single line-to-ground (SLG) fault. The existing active equipment can only suppress the neutral point overvoltage or the SLG fault arc, which has a single function and low utilization rate. In order to maintain the stable operation of the distribution networks and improve equipment utilization, the research on active equipment integrating the two functions is of great significance. Therefore, this paper proposes active equipment based on a cascaded H-bridge (CHB) inverter that integrates the functions of neutral point overvoltage suppression and arc suppression. The CHB inverter can switch from overvoltage suppression to arc suppression by the characteristics of zero-sequence voltage amplitude during overvoltage suppression. The arc suppression effect of the proposed arc suppression method is better than the existing flexible current arc suppression method in case of asymmetric phase-to-ground parameters. The simulation and experimental results verify the effectiveness of the proposed method under different influencing factors.