电导非线性对HVDC电缆绝缘空间电荷动态过程的影响

Effect of nonlinear conductivity on dynamic process of space charge in HVDC cable insulation

针对HVDC电缆绝缘中的空间电荷问题,采用有限元分析方法,仿真研究绝缘材料电导非线性属性对HVDC电缆绝缘中由非线性电导率引起的空间电荷极化与退极化动态过程的影响。通过改变电导活化能与电场依赖系数,得到极化与退极化过程中空间电荷密度随时间的变化规律。分析结果表明:降低电导活化能或增大电场依赖系数可降低HVDC电缆绝缘中由非线性电导率引起的空间电荷量,抑制极化与退极化过程中的空间电荷“过冲”与“反极性过冲”现象,并且会加快极化与退极化过程达到稳态,但同时会使绝缘介质中的电流密度增大。

In order to research the space charge problems caused by nonlinear conductivity in HVDC cable insulation,the finite elements method was adopted to study the effect of non-linear conductivity attributes on dynamic process of space charge polarization and depolarization in HVDC cable insulation.The space charge density patterns during polarization and depolarization over time were attained while changing the conductivity activation energy and the field-dependent coefficient.The results show that reducing the conductivity activation energy or increasing the field-dependent coefficient diminishes the space charge amount and the“overshoot”during polarization and depolarization which are all induced by nonlinear conductivity and also makes the polarization and depolarization reach the steady more quickly.But meanwhile that increases the current density in cable insulation.