Identification and Location of Local Defects in Power Cable Body Based on Input Impedance Spectroscopy

Abstract

In order to solve the shortcomings of partial discharge (PD) method and reflection coefficient spectrum (RCS) method in local defect identification and location in power cable body, a method is proposed based on input impedance spectrum. Firstly, the input impedance spectrum characteristics with capacitive / inductive defects were analyzed by simulation based on the distributed parameter model of the power cable. Then, the input impedance spectrum and Kaiser window were used to locate the local defects in power cables with high sensitivity, and the location spectrum was extremely intuitive. Finally, to verify the effectiveness of the proposed method, two kinds of local defect samples (copper shield defects and thermally aged defects) were made on a 13m long power cable in the laboratory. The results indicate that this method has high recognition sensitivity for local defects with a length of more than 5cm or a change in capacitance more than ±5%. The method can not only identify the local defect types of power cable body, but also effectively locate the local weak defects.