Research on Online Partial Discharge Detection Technology of Underground Power Distribution Cabinets Based on Capacitive Insulator Coupling

Abstract

Aiming to address the susceptibility of existing capacitive insulator coupling technology to ground grid interference in partial discharge (PD) monitoring for underground distribution cabinets, and its unreliable performance in humid environments, this paper proposes a real-time wireless PD monitoring method us-ing capacitive insulator coupling. By analyzing the response characteristics of coupled signals from dis-charge defects, a simulation model for signal propagation and ground interference was developed and validated on an experimental platform. Results show: 1) The model accurately simulates air-gap dis-charge mechanisms and signal propagation, aligning with experimental time-domain responses; 2) Ground grid interference propagates via common-ground impedance wide-frequency coupling, and the "common grounding point" method effectively suppresses it, significantly improving the signal-to-noise ratio; 3) Phase-resolved PD patterns exhibit typical "bimodal" features, consistent with the simulated in-ternal air-gap discharge model, verifying the system's capability to identify typical insulation defects. This study offers theoretical and practical insights for optimizing capacitive coupling technology and enabling high-sensitivity PD detection in complex environments.