Comparison of Insulation Performance Between PP and XLPE at 110 kV High Voltage Cable Joints Based on Electro-Thermal-Stress Coupling Simulation

Currently, high-voltage cables with cross-linked polyethylene (XLPE) as the main insulation are widely used in the power industry. Nevertheless, polypropylene-based (PP) materials have a broad application prospect due to their advantages such as higher temperature stability and good recyclability, offering options as an alternative to XLPE cables for global electrical industry. In this paper, key material parameters such as relative dielectric constant, Young’s modulus, Poisson’s ratio and coefficient of thermal expansion of XLPE and PP materials at different temperatures were measured. The coupling simulation model of 110 kV high voltage cable joint was established to obtain the distributions of electric, thermal and stress fields when XLPE and PP were used as the main insulation of the joints, respectively. The results show that the intensity of electirc field at composite interface is lower for XLPE/SR (silicone rubber) due to its larger relative dielectric constant, leading to better insulation performance. Moreover, the thermal deformation of XLPE cable is smaller than that of PP, as its smaller heat capacity of constant pressure. As a result, the degree of electric field distortion is lower, bringing about better working stability at high temperature.