Experimental Validation of a Novel Travelling Wave Based Fault Location Method for Unearthed Overhead Line Networks

This paper presents the improvement of an original fault location approach previously presented by the authors to the scientific community. The method is thought to identify the fault position in unearthed operated networks by exploiting a single measurement terminal and it is based on the travelling wave theory. The novelty introduced in this work is the experimental demonstration that the combination of the Continuous Wavelet Transform and the Discrete Fourier Transform applied to the earth mode component of the fault current is able to significantly increase the precision in the fault location. In order to verify the accuracy of the method, phase-to-ground short circuits have been triggered on a real overhead line in different positions, since the on-field application of travelling wave based fault location methods represents the most reliable bench test. The proposed algorithm proved to be reliable and accurate in the estimation of the fault distance despite its formal simplicity. The experimental results demonstrate the accuracy and robustness of the method for faults occurring before a line branch at a sampling rate of 1 MHz. In addition, the behavior of the proposed approach for faults occurring after a branch is investigated, highlighting the role of the sampling frequency in resolving closely spaced reflections. Simulation results show that higher sampling rates are required in branched configurations, thereby defining the current practical conditions for the applicability of the method.