Improving partial discharges location under dispersion and multi-path propagation

Abstract

Dispersion and multi-path propagation distort partial discharge (PD) pulses that travel along power cables. Two new techniques to improve the location accuracy using double-ended methods are proposed: the inclusion of a pre-filter (PF), that increases the signal to noise ratio by properly selecting the filter bandwidth and the center frequency, and an echo suppression (ES) technique, that reduces the peak value of the interfering echoes.Two location algorithms (based on cross-correlation and the energy criterion function) are combined with the proposed techniques and their performances against noise, dispersion, and multi-path propagation are evaluated. Simulation results show that the proposed PF technique improves the location accuracy, even for high dispersion conditions, where the location error can be reduced down to half a meter. In addition, the proposed ES technique reduces the number of false detections in those cases where the first PD echo is close to the original PD. Experimental results confirm the benefits of the proposed PF technique, showing that, even under adverse conditions, the location error can be smaller than 1m in a 300m long cable.