Capacitive coupling detection and characteristic analysis of partial discharge in high-voltage XLPE power cable joints

Five models of typical internal insulation defects are designed and a test platform for partial discharge (PD) research on cable accessories also is constructed in order to study PD characteristics of internal insulation defects in 110 kV XLPE cable joints. By use of capacitive coupling method, plenty of PD data are obtained for various models and the construction of related phase-resolved PD diagrams. Based on the third-order and fourth-order characteristic parameters, discharge characteristic analysis of a single pulse current is presented. The experimental results show that capacitive coupling method is effective for detecting PD signals from internal defects of cable joints without harmful influence on insulation properties of cables and cable joints. In addition, there are significant differences in the some statistical parameters (e. g., discharge interval, discharge repetition rate)of PRPD (phase resolved partial discharge) diagrams and the third-order and fourth-order characteristic parameters of time-domain PD waveform which can be used as reference points for PD patterns.