Enhancing Partial Discharge Sensitivity Over Distance by Active Capacitive Sensors

This paper investigates the effectiveness of noninvasive partial discharge (PD) detection using capacitive coupling-based sensors for the remote monitoring of mediumand high-voltage cable systems. Partial discharges represent critical insulation defects and, if left undetected, may lead to catastrophic failures in power distribution networks. Conventional PD detection techniques often require galvanic contact or proximity to the defect location, limiting their applicability in installed networks. This study presents a field case study where active capacitive sensors successfully detected PD activity at significant distances, up to few kilometers from the defect source. In addition to field data, the paper introduces a distributed parameter circuit model developed to simulate the propagation of PD pulses over a coaxial cable, accounting for attenuation and dispersion phenomena. The comparison between measured and simulated waveforms demonstrates good agreement, validating the accuracy of both the sensing technology and the simulation model. The findings confirm the suitability of capacitive sensors for remote PD diagnostics and emphasize the importance of waveform-based features-such as rise time and spectral content-for accurate localization and classification of PD events over distance.