New approach to select the fault line based on transient energy features of fault phase

A new approach for fault line detection using Wavelet energy feature of fault-phase transient current is proposed. This novel method utilizes the phase selection function of insulation monitoring system and the differences of transient current between fault line and non-fault line. Firstly, the transient current signals of each phase fault are extracted to identify the faulty phase effectively. The pure fault component is obtained by noise elimination. Then, each phase wavelet energy feature can be achieved by the decomposition and reconstruction of wavelet packet. The fault line can be detected by comparing energy feature of each phase for the reason that the fault line's energy characteristics of fault phase are much greater than that of non-fault line under single phase grounding fault. This approach is clear in physical mechanism and unaffected by operating mode, circuit components, fault conditions and other factors. It can also effectively overcome the system noise, the interference of asymmetrical component. The line selection method has broad margin and high reliability, which is practical to applications.