Partial Discharge Detection on 80 kV DC XLPE Cable with Artificial Defects under DC Voltage

Extruded cross-linked polyethylene (XLPE) cables have become the preferred choice for the VSC-HVDC, due to benefits like easier production, transportation, and installation compared with MI cable. For AC cables, partial discharge testing is a vital method to evaluate the condition of the cable. However, there is significantly less experience regarding the behavior of partial discharge under DC conditions. It is well known that failures arise more often in accessories than in the cable itself. In order to evaluate partial discharges for a typical installation defect, a sharp transition edge between the outer semicon and the insulation layer has been prepared on an 80kV DC-cable system. Under different cable conductor temperatures, partial discharge tests with DC voltage steps have been performed with and without pulsed xray. For comparison, PD measurements at AC have also been performed on the DC-cable. Finally, the partial discharge inception voltage (PDIV) under DC and AC has been compared, and the dependence of temperature and X-ray pulses for DC partial discharge is investigated.