Study on Matching Characteristic of XLPE/EPDM Interface in HVDC Cable System

The high voltage DC cable insulation and accessory insulation form a double-layer composite insulation structure, and its matching characteristics are an important basis for the safe and stable operation of the DC transmission system. In this paper, the effects of conductivity properties and material microstructure of cross-linked polyethylene（XLPE）and ethylene propylene diene monomer（EPDM）on insulation interface matching characteristics were studied. Then the space charge distribution characteristics and electric field distribution characteristics of the com posite interface and the influence of material modification on the insulation matching characteristics are studied. The experimental results show that the conductivity characteristic parameters of XLPE and EPDM（material coefficient A, electric field dependence coefficient B, activation energy φ）. The difference is an important factor for the unsatisfactory insulation matching characteristics. The maximum electric field distortion rate of composite XLPE/EPDM inter face can reach 209.49%. EPDM modified by nano doping has lower conductivity and less space charge accumulation, and has better insulation coordination with XLPE. The research of this paper provides a theoretical and experimen tal basis for the material development, performance optimization and structural design of HVDC cables and accessories.