交联聚乙烯绝缘高压直流电缆电场分布计算

Simulation of electrical field distribution of XLPE insulated HVDC cable

为设计交联聚乙烯(XLPE)绝缘高压直流电缆的结构,在实验基础上总结出进口高压直流电缆XLPE绝缘材料的电导特性方程,利用COMSOL Multiphysics软件通过电场和热场耦合仿真计算了电缆在不同负荷下的电场分布。研究表明,在电场强度较低和较高时,进口高压直流电缆XLPE绝缘材料的电导率随温度变化明显,电场强度变化几乎不对其产生影响;在某一电场强度范围内,温度和电场强度的改变均会使XLPE的电导率发生明显变化,该场强范围随温度而变化;所设计高压直流电缆在两种敷设环境下100%负荷时电场分布均匀;在电缆传输电流较大时,电缆XLPE绝缘内的温度梯度增大,电缆绝缘外表面处电场强度最大。基于有限元法的多物理场耦合仿真计算是研究XLPE绝缘高压直流电缆电场分布的有效手段。

In order to design the structure of cross-linked polyethylene（ XLPE） insulated high voltage direct current（ HVDC） cable,the electrically conductive characteristic equation of imported XLPE insulation materials for HVDC cable is derived based on experimental results,and the electrical field distribution of cable under different loads is calculated through electro-thermal filed coupling simulation by using the COMSOL Multiphysics software. The research results show that the electrical conductivity of imported XLPE insulation materials for HVDC cable is sensitive to temperature variation and free to change in electrical field strength when the electrical field strength is lower or higher. The change in temperature and electrical filed strength can lead to remarkable change of electrical conductivity of XLPE in some range of electrical field strength that depends on temperature. The electrical field distribution inside the designed HVDC cable is uniform under 100% of load at two laying conditions. As transport current is higher,the temperature gradient inside HVDC insulation cable increases and the electrical field strength of outside surface of insulation cable is maximal. These findings indicate that the multi-physical field coupling simulation based on the finite element method is an effective way to investigate the electrical field distribution of XLPE insulated HVDC cable.