Simulation Study on the Repair Effectiveness of Ablation Failure in High-Voltage Cable Buffer Layer Based on Electro-Thermal-Mechanical Coupling

In recent years, buffer layer (BFL) ablation repair technology has been developed in response to the frequent ablation failures, yet there remains hardly research analyzing their actual repair effects. To address this issue, this study first identified abnormal cable body heating via infrared thermography (IRT) in a certain power grid. Typical ablation features was observed within the dissected power cable, thereby establishing a three-dimensional electro-thermal-mechanical finite element model for <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{1 1 0 ~ k V}$</tex> high-voltage cables considering corrosion products and repair agent filling. The effects of repair agent parameters on internal temperature fields and electric field distributions.was systematically analyzed. Furthermore, under full-load conditions accounting for gravitational effects and structural expansion, stress-strain distribution within cable assemblies was investigated. It was demonstrate that electrical conductivity serves as the critical determinant for electrical and thermal field distributions within the power cables. When conductivity exceeds <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1 \times 10^{-5} ~\mathrm{S} / \mathrm{m}$</tex>, localized heating induced by capacitive current and electric field distortion were effectively mitigated. Under rated operating conditions, maximum strain of 1.18 mm was observed at the interface between cured repair agent and buffer layer. This research provides theoretical support and technical references for the evaluation on the repair effectiveness of the ablated BFL.