非线性复合结构的界面极化特性

Interface Polarization Characteristic of Nonlinear Composite Structure

为了探讨非线性复合绝缘结构的界面极化特性,以平板电极结构下线性/非线性复合介质为研究对象,仿真分析了不同幅值阶跃电压和极性反转电压作用下双层介质中的电荷分布及电场分布。仿真发现:当线性介质与非线性介质的时间常数有交点时,在阶跃电压作用下,界面积聚电荷随外施电压幅值的增大而减少;当外施电压增加到2层介质时间常数相交的临界电压时,界面电荷极性反转,且随外施电压幅值增大而增多;外施电压幅值越高,界面极化建立速度越快,退极化速度越慢;在极性反转电压作用下,最大瞬时界面电荷和双层介质中的电场强度均比阶跃电压下的最大初始电场强度值高。从上述结果可以看出:阶跃电压作用下,场致增强型电导率非线性介质对界面积聚电荷具有一定的改善作用;但在电压极性反转瞬间,由于非线性介质承受较高电场强度,所以可能使绝缘系统的可靠性下降。

To investigate the interface polarization characteristic of nonlinear composite insulation structure, taking a linear / nonlinear composite material with the plate electrode structure as a research object, we simulated the distribution of charge and the electric field in two-layer dielectric under step voltage and polarity reversal voltage with different am- plitudes. The simulation results show that, under the condition of the time constants of two-layer dielectric intersection, interface charges decrease with the increase of amplitude of step voltage. When the applied voltage is increased to the critical voltage that time constants of two-layer dielectric intersect, the polarity of interface charges will reverse. Then in- terface charges increase with the increase of the voltage amplitude. And the polarization is quikened and the depolarization gets slower with the increase of the voltage amplitude. The maximum instantaneous interracial charge and electric field in two-layer dielectric under polarity reversal voltage are both higher than those under the step voltage. The results reveal that the accumulation of charge is improved by nonlinear dielectric with field enhanced conductivity. But in the moment of voltage polarity reversal, the reliability of insulation system may be decreased due to the high field strength in the nonlinear dielectric.