Effect of Segmented Thermal Aging on Defect Location Accuracy in XLPE Distribution Cables

Abstract

Frequency domain reflectometry (FDR) technologies could be applied to locate defects in cables effectively. Owing to the large space span and complex operating environment of the actual XLPE distribution cables, segmented thermal aging phenomenon occurs easily, causing the nonuniform distribution of electrical parameters along cables, which might affect the defect location accuracy ultimately. In this paper, the segmented thermal aging cable models were established and the effect of segmented-aging in XLPE distribution cables on defect location accuracy was explored based on simulation. It was found the floating range of defect location deviation in segmented thermal aging cable models could reach 10% of the whole cable length, which could not be ignored. Further research and analysis revealed that the defect location deviation in the segmented-aging cable mainly attributes to the differences of distributed wave velocities in the cable. On this basis, a correction coefficient of defect location $M$ was put forward for the segmented-aging cable models established, which has achieved remarkable results. Finally, a segmented-aging cable model with a length of 119 m was built in the laboratory, and the validity for improving defect location accuracy by considering the differences of wave velocities was verified through experiments. Results show the defect location deviation can be reduced from 2.19% to 0.39% by introducing $M$ .

Keywords

• Segmented-aging cable
• frequency domain reflection
• broadband impedance spectrum
• defect location
• electromagnetic wave velocity