Evaluation of insulation condition detection methods applied to DC XLPE cable

Abstract

At present, with the construction and operation of new energy grid-connected and offshore wind power projects in China, DC XLPE cables have been widely used. Under the operating conditions, there are mainly two feasible technical means of DC cable insulation state detection, partial discharge (PD) and leakage current. However, it is still a blank in the world to apply it to the validity and condition of DC cable operation detection. Based on the semi-conductive layer residual defect model of XLPE cable, the characteristics of PD and leakage current under different voltage values and polarities are studied by setting up an experimental platform for detecting PD and leakage current of DC XLPE cable. The results show that both PD and leakage current can detect cable defects, among which PD is easier to detect cable defects under negative polar voltage and higher voltage. Leakage current characteristics change obviously under positive polar voltage. When applied voltage is lower than rated voltage, obvious changes can also be measured. In this paper, the feasibility of live detection of leakage current of DC cables under operating conditions is proposed, which is of great value to improve the detection capability of DC XLPE cables.