Research and Optimization of Spatial Electric Field Evolution Characteristics in High-Voltage Polypropylene Cable Joints under Multiple Defects

This study investigates electric field distortion in high-voltage polypropylene (PP) cable splice joints under the interaction of multiple defects. A two-dimensional axisymmetric model was established using finite element simulation to systematically examine the spatial evolution of electric fields influenced by three interfacial defects: air gaps, moisture ingress, and metallic particle residues. Based on a mechanistic analysis of defect coupling effects, a dual optimization approach is proposed. The first aspect involves a conductivity-matching strategy, achieved by adjusting the electrical properties of the PP layer to align with those of the silicone rubber layers. The second aspect is a structural modification involving localized thickening of the PP layer to optimize the electric field distribution. The results show that electric field distortion caused by multiple defects exhibits nonlinear superposition behavior, with the combined effects of air gaps and metallic particles demonstrating mutual suppression compared to individual defects. The conductivity-matching strategy effectively reduces the maximum field strength at the interfaces and suppresses charge accumulation. While the structural optimization introduces localized field fluctuations at specific interfaces, it significantly enhances overall electric field uniformity and maintains stable optimization performance under multi-defect conditions. This research elucidates the spatial evolution mechanisms of electric fields in cable joints with compound defects and provides a theoretical foundation for improving reliability and practical solutions for mitigating multidefect risks in high-voltage cable connections.