To solve the problems of neutral point displacement overvoltage and incomplete arc suppression caused by distribution network parameter asymmetry, closed-loop control is used to regulate the neutral point voltage during the normal operation of the distribution network. It automatically tracks the changes of the distribution network structure parameters, and realizes rapid and accurate suppression of the unbalanced voltage. An injection current feedback control link is designed. It is combined with the unbalanced voltage regulation process and the zero-sequence current and zero-sequence voltage after the fault. Then fault identification, fault phase selection and the reference value of the injection current required for reliable arc suppression can be achieved by injecting only one current. The simulation analysis shows that the closed-loop control can effectively track and suppress the unbalanced voltage of the neutral point. The proposed flexible arc suppression method has high fault discrimination accuracy and good fault arc suppression when there are asymmetric system parameters.