Faulty Phase and Faulty Line Selection Method Based on Three-Phase Transient Current

The neutral point of distribution network is usually ungrounded or grounded through arc suppression coil in China. When a single-phase-to-ground fault occurs, the fault current is small, which brings difficulties to fault diagnosis. A method of faulty phase and faulty line selection for single-phase-to-ground fault based on three-phase transient current is proposed. Firstly, the faulty phase is identified by the difference in the transient current between the faulty phase and the healthy phase. Then, the transient current of each line is decomposed and reconstructed by the wavelet packet, and the ratio of the transient current energy in the selected frequency band of each line is calculated to identify the faulty line. Finally, several groups of artificial grounding experiments have been carried out in a 10kV real type test field to verify the correctness of the proposed faulty phase selection and faulty line selection method.