This paper analyzes the influence of ground capacitance of lines on the distribution of both the zero-sequence and negative-sequence fault current. A novel method for resonance tuning in distribution networks is then presented. In the proposed method

the minimal negative-sequence current of the fault line is the tuning goal after the fault line is chosen in terms of the relative maximal value of the negative-sequence currents of lines. At the same time

the phase difference between the negative-sequence current of the fault line and the current of the arc-suppression coil (ASC) is used to direct the change of the ASC inductance. In particular

the selection of the fault line and the resonance tuning can also be achieved using the proposed method

that is

the fault line may be chosen during the tuning for the resonance. The capacitance of the distribution network does not need to be measured and the network operation mode imposes no impact on the tuning. Even when the operation mode changes

the proposed method can detect the change and adjust the ASC inductance for the network resonance again. The effectiveness of a prototype device has been verified by the results of the dynamic simulation experiments.