Insights into Non-uniform Aging Effects on Broadband Dielectric Behaviors for High-voltage XLPE Cable Insulation: A Novel Fractional-order Circuit Modeling Approach

A non-uniform aging pattern inside insulation systems is a significant contributor to the degradation of high-voltage (HV) power equipment. Therefore, this article presents a comprehensive investigation into the effects of non-uniform aging patterns on broadband dielectric properties of polymer insulation, with a focus on XLPE power cables, aiming to provide a deeper understanding of these effects. By examining two uniformly aged and five non-uniformly aged XLPE insulation cases, the study comparatively analyzes the influence of diverse aging patterns on broadband dielectric properties. Furthermore, a novel fractional-order circuit model is proposed to characterize broadband dielectric behaviors influenced by insulation structure heterogeneity caused by non-uniform aging patterns. The results indicate that non-uniform aging effects on real part of capacitance in XLPE insulation are highly sensitive, though the analysis remains qualitative. Subsequently, the proposed fractional-order circuit model following power-law behaviors successfully reconstructs broadband dielectric properties of non-uniformly aged XLPE insulation systems with average relative errors of less than 10%, making it a potential quantification tool to unveil underlying dynamic behaviors. This model offers a rational physical explanation and characterization of XLPE dielectric properties subject to diverse aging patterns, providing theoretical support for the aging analysis of HV cable equipment.