Insights Into Nonuniform Aging Effects on Broadband Dielectric Behaviors for High-Voltage XLPE Cable Insulation: A Novel Fractional-Order Circuit Modeling Approach

A nonuniform 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 nonuniform 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 nonuniformly 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 nonuniform aging patterns. The results indicate that nonuniform aging effects on the 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 nonuniformly 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.