Arc extinguishing of grounding faults is a problem for neutral non-effective grounding distribution networks. In consideration of line parameters and load

a flexible arc-suppression optimization method under the single-phase-to-ground fault in the distribution network is proposed. When a single-phase-to-ground fault occurs

the compensation current is injected by a cascaded H-bridge converter. By measuring the zero sequence voltage of the bus

the grounding resistance can be calculated. For the higher grounding resistance

the fault phase is selected according to the variation trend determined of the three-phase voltage on the bus after compensation current injection. Then the voltage in the fault phase is controlled to be zero by adjusting the injection current according to the result of fault phase selection

which means to adopt the voltage-based arc-suppression method. Otherwise

the compensation current will be injected continuously

which means to adopt the current-based arc-suppression method. The simulation result has proved that the proposed method is able to suppress the arc flexibly and effectively and overcome the shortages of current-based and voltage-based arc-suppression methods due to line parameters and load. This work is supported by National Natural Science Foundation of China(No. 51677030)and Fujian Provincial Natural Science Foundation of China(No. 2016J01218).