Partial discharge location in power cables using a phase difference method

This paper presents a new partial discharge (PD) location technique for power cables. Unlike commonly used time-domain reflectometry (TDR) methods, this technique is based on the analysis of phase difference between the direct and reflected waves of a PD pulse measured at the cable end. The phase difference at various frequencies can be obtained from the cross Fourier spectral density function. After implementing a phase unwrapping algorithm, the defect is located. This technique has been tested using the Electromagnetic Transient Program (EMTP) on the model of a 20 kV, 1-km underground cable. The simulation takes into account the frequency-dependent parameters of the cable and the measurement accuracy of the A/D converter (8-bit). The signal-to-noise ratio (SNR) varies from 10 dB to -5 dB for all computer simulations. The statistical results are given to demonstrate the performance of the proposed technique.