Research on Non-Uniform Thermal Aging Mechanisms in Submarine Cables Based on Multiphysics Coupling Analysis

Submarine cables, as critical infrastructure for global energy interconnection and information transmission, face insulation aging issues that have become a major bottleneck constraining system reliability. First, this study focuses on the non-uniform thermal aging phenomenon in submarine cables during operation induced by multi-field coupling effects. By constructing an electromagnetic-thermal-fluid multi-physics coupling model based on actual environmental variations in cable operation, the study reveal the gradient influence patterns of different laying sections (deep-water, transitional, and nearshore zones) on the thermal aging lifespan of insulation layers. Second, through a scaled-down accelerated aging experimental platform for defect assessment in aging states, the research discovers that defects cause subtle distortions in the surface magnetic field signals of submarine cables. Specifically, the magnetic field distribution along the cable surface becomes non-uniform, demonstrating the utility of magnetic field analysis for thermal aging detection. The study systematically uncovers the non-uniform characteristics of submarine cable thermal aging processes under the coupled effects of operational conditions and environmental parameters. A magnetic signature-based aging state evaluation model is established, providing theoretical support and engineering guidance for ensuring submarine cable operational safety, condition assessment, and the formulation of differentiated maintenance strategies.