A novel single-ended fault location scheme and applications considering secondary circuit transfer characteristics

Identification of the wave fronts is the precondition of travelling wave based fault location. Many factors may affect a precise identification of the wave fronts, among which the transfer characteristics of the secondary circuit are in focus. The resonance nature of the secondary circuit which consists of current transformers and secondary cables causes certain noises in the recorded travelling waves. Hence, travelling wave based single-ended fault location is affected. Transfer characteristics of the secondary circuit are analyzed in the paper. High-frequency model of the secondary circuit is obtained and the transfer function is derived. The noises are proved to be two damped oscillation components mixed together. To overcome this, a novel single-ended fault location scheme is proposed. Impedance fault location algorithm, dyadic wavelet transform and Prony analysis are involved. A high-precise fault recording and location device is developed and implemented in several 220 kV substations in Shandong, China. Recorded waveforms of a single-phase-to-ground fault have proven both the analysis and the proposed fault location scheme.