A Study on the Propagation Characteristics of Partial Discharge in Cable Joints Based on the FDTD Method

Partial discharge (PD) is the main cause of cable insulation deterioration. It is of great theoretical significance and practical value to carry out PD research on high voltage (HV) cable joints for fault detection and operational status evaluation. In this paper, a three-dimensional finite-difference time-domain (FDTD) simulation model of cable joint is built. According to typical fault types of PD in 110kV XLPE cable, four types of insulation defect models, including electrical tree discharge, surface sliding discharge, air gap discharge, and floating discharge, are designed and manufactured. Based on the three-dimensional simulation model of cable joint, the propagation characteristics of PD signals caused by the aforementioned insulation defects are analyzed, the effects of different types of insulation defects and fault locations on the propagation characteristics are investigated. A PD experimental platform based on a cross-bonded three-phase 110 kV cross-linked polyethylene (XLPE) cable system is built for verifying the feasibility of the three-dimensional simulation model. Results show that the model can reasonably explain propagation characteristics of PD signals in cable joints, including polarity, peak values, attenuation characteristics and symmetry, which provided the theoretical basis for judging the fault locations and types of PD caused by insulation defects in cable joints.