Study on Space Charge Characteristics between XLPE and SR for HVDC Cable Insulation and Accessory Insulation under Temperature Difference Field

During normal operation of high-voltage cables, space charges accumulate at the composite insulation interface composed of the cable body and its accessories. At the same time, due to the thermal effect of the cable copper conductor resistance, a temperature difference is formed on both sides of the composite insulation, that affects the space charge properties of the composite medium. Therefore, in this paper, the space charge characteristics of composite dielectric sheet samples consisting of cross-linked polyethylene as the main insulation and silicone rubber as the auxiliary stress cone insulation have been studied under different field strengths and temperature differences. Based on the Maxwell Wagner polarization model, space charge and electric field distribution within the double layer dielectric was simulated. The results show that the polarity of the interfacial charge is consistent with that of the silicone rubber side charge, and as the temperature difference increases, the spatial charge density at the composite dielectric interface gradually increases, while the electric field distortion at the interface becomes more severe. The M-W polarization model successfully simulates the internal space charge characteristics of composite media under different temperature differences.