The existing grounding protection for low resistance grounding system mainly adopts zero-sequence definite-time overcurrent protection

whose setting value is too high to act when high impedance grounding fault occurs. Considering the characteristics of inverse-time overcurrent protection

based on the analysis of the fault current distribution characteristics of single-phase grounding fault in low resistance grounding distribution network

an improved zero-sequence inverse-time overcurrent protection method is proposed. The starting current setting value of the protection doesn't need to escape from the maximum capacitance current of the outlet

with the crosswise coordination among each outlet

so that the starting threshold is greatly reduced

which can effectively improve the protection ability of the high impedance grounding fault. The speed and reliability of the proposed zero-sequence inverse-time overcurrent protection are verified by MATLAB simulations.