Multiple chirp reflectometry for determination of fault direction and localization in live branched network cables

This paper proposes a multiple inductive coupler chirp reflectometry system with multiple resolutions that can determine fault direction, and localize fault is proposed to apply the live target cable. The multiple resolution method enables us to detect and localize the faults, regardless of their location. Time delay information from multiple couplers, which is derived from the time-frequency cross correlation, indicates the fault direction and fault distance, even in cable branched network. The multiple inductive couplers system is proposed to obtain the velocity of propagation and fault direction in cable branch. Using the overcomplete wavelet transform, the signal restoration process can be carried out under signal distortion due to the propagation characteristics of the inductive coupler and target cable. In addition, combining notch filtering techniques and chirp reflectometry method is proposed to cancel 60-Hz harmonic noise, which is acquired from the actual substation. Through the experiments, impedance discontinuity localization and direction determination performance of the proposed method and the adaptability of the proposed method in live cable under harmonic noise by comparing with the existing method were verified.