A Thermal Excitation Based Partial Discharge Detection Method for Cable Accessory

Partial discharge (PD) test has been widely used in condition assessment for power cables. However, discharge extinguish phenomenon occurred in PD detection hinders the effective detection of potential defects in cable accessories. For this reason, a novel PD detection method based on thermal excitation is proposed in this article to eliminate the extinguish phenomenon and to detect the potential defects in earlier stage. First, the physical processes in PD activity and the reasons for discharge extinguishing are introduced. Then, the principle and mechanism of the thermal excitation detection method are described and analyzed respectively, that is excitation by external heating to break the dynamic equilibrium of charge movement within the defect and further stimulate new discharges. And a finite element simulation model is constructed to determine the thermal excitation parameters. Finally, the effectiveness is validated by performing thermal excitation-based PD test on some defective cables. The experimental results show that this method can significantly increase the number of discharges in off-line test, while also stimulating PD of higher amplitudes in on-line monitoring. This method can improve the sensitivity of PD detection for cable accessories and detect potential defects in early stage.