Faulty line selection based on time-frequency characteristics of transient zero-sequence current

When single-phase grounding fault occurs in the power distribution system with its neutral point grounded through arc suppression coil,the distribution characteristics of transient zero-sequence current in short-window time-domain and frequency-domain are different between sound feeder and faulty feeder. The fault transient zero-sequence current data of different feeders are extracted for the last quarter of power cycle,which are then decomposed by the wavelet packet and reconstructed into different frequency bands.The time-frequency characteristics obtained for a short window can fully reflect the time-frequency characteristics of the signal. The correlation coefficients are then used to characterize the time-frequency distribution and variation law of transient zero-sequence current,which are combined with the complex correlation coefficient to form the criterion for faulty line selection. Electromagnetic transient simulations show the proposed method of faulty line selection is accurate and reliable.