The active arc-suppression mechanism under single-phase grounding faults in distribution networks is described. And an active arc-suppression method based on double closed-loop control is proposed. When the single-phase grounding fault occurs

the inverter device injects zero-sequence current into the neutral point to force the faulted phase voltage to zero

and the fault arcs can thus be reliably extinguished. The control system consists of a neutral voltage outer-loop and an injecting current inner-loop using a proportional-integral(PI)controller and proportional-resonant(PR)controller each

respectively. The output of the outer-loop is used as the reference signal for the inner-loop. The stability of the outer-loop and that of the inner-loop controllers are analyzed. Simulation analysis and prototype testing results show that the system has good steady-state and transient response performance

and is able to quickly and precisely suppress the fault current without measuring the impedance parameters of the distribution network.