Online detection of XLPE cable operation failure in low-temperature environments using distributed optical fibre temperature sensing

Reliable condition monitoring of cross-linked polyethylene (XLPE) power cables is essential for preventing insulation failure, ensuring stable power transmission, particularly under low-temperature operating environments where conventional diagnostic methods exhibit limited sensitivity and accuracy. Existing cable conditions assessment approaches often rely on periodic inspections or visual analysis, which are insufficient for detecting early-stage insulation degradation and may lead to unexpected failures. To address this limitation, this research proposes an online XLPE cable operation failure finding technique based on distributed optical fibre temperature sensing integrated with statistical evaluation of thermal behaviour, focusing on thermal-field-based indicators rather than direct electrical or mechanical characterisation. Controlled experimental investigations were conducted by introducing different insulation damage depths and lengths under simulated operating conditions. The resulting temperature field variations were systematically analysed using parametric and non-parametric statistical techniques, including t-tests, Mann–Whitney U test, and Wilcoxon signed-rank tests. The results demonstrate that insulation damage depth has a statistically significant influence on cable surface temperature rise (p < 0.05), whereas insulation damage length shows a comparatively weaker and statistically insignificant effect. In addition, optical fibre temperature sensing exhibited superior measurement stability and spatial accuracy compared with conventional thermocouple-based measurements under various laying environments.