Impedance Spectrum Measurement and Fault Detection for XLPE Coaxial Cables

XLPE coaxial cables are prone to faults and defects in the process of power transmission, seriously jeopardizing the safe operation of the power system. The limitations of the existing fault diagnosis methods are analyzed, and a new method is proposed to realize cable fault detection by doing an integral transformation on the phase difference. By establishing a baseline to improve the discrimination rate of fault defects, the fault information of the same cable is detected from the first and last ends respectively, and the distance between the two opposite-direction extreme points within the local range of the maximum jump point is taken as the fault length. Finally, multiple mechanical wears and thermal aging defective segments are designed on 15 kV coaxial cables, and the method is utilized to diagnose faults on actual cables, where the error between the actual fault center and the measured fault is less than 1% and the length error is less than 1 m. The results show that the method can effectively identify the characteristic quantities such as the length and location of the defects present in the cable.