Travelling wave time-frequency characteristic-based fault location method for transmission lines

Single-ended travelling wave fault location methods have the advantages of avoiding the complexities and costs of the remote-end synchronisation. However, the determination of the arrival time of the travelling wave and its corresponding propagation velocity is a difficult problem which is apt to limit the algorithms´ accuracy. A novel single-ended fault location method based on travelling wave time´frequency characteristics for transmission lines is proposed in this study. The time´frequency characteristics of the travelling wave signal are described by the Lipschitz exponent. The Lipschitz exponent of the second transient wave-front signal is estimated by using the wavelet transform and the least square method. Afterwards the frequency component of the travelling wave, which is best for fault location, and its corresponding arrival time and propagation velocity can be determined. Then the proposed method calculates the fault distance precisely based on the determined time and velocity. Extensive simulations have been carried out in PSCAD/EMTDC, and the results demonstrate that the accuracy of the proposed fault location method is significantly improved comparing with that of the traditional travelling wave fault location method. The proposed method is insensitive to different fault conditions, and it adapts to both transposed and untransposed lines well.