介电弛豫过程对基于电声脉冲法的空间电荷测量的影响

Influence of dielectric relax on space charge measurement based on pulsed electro-acoustic method

空间电荷引发的电场畸变严重威胁电介质的绝缘性能,针对目前空间电荷研究中没有考虑松弛极化过程对电场分布的影响,基于电声脉冲法原理,考虑单一形式松弛极化和空间电荷分布动态变化过程,对介电弛豫影响下的空间电荷进行仿真分析。结果表明:极化达到稳态的时间与空间电荷测量的持续时间可比拟时,松弛极化会阻挡对电极附近电荷运动过程的认知,给测量到的电场分布引入严重误差;极化随时间变化的幅度越大、速度越快,松弛极化所造成的影响就越大。根据电位边界条件建立优化模型,初步提出了一种基于最小二乘法的修正方法来有效消除误差。

The electric field distortion caused by space charge is a serious threat to the dielectric insulation,but the effect of relaxation polarization process on electric field distribution is not considered in the present study of space charge.Based on the principle of pulsed electro-acoustic method,and considering the process of single-form relaxation polarization and dynamics of space charge distribution variation,the influence of dielectric relaxation on space charge measurement is simulated.The results show that when the time for dielectric relaxation reaching the stable state is comparable to the duration of space charge measurement,the relaxation polarization will block the recognition of space charge movement near the electrodes and introduce serious errors into the measured electric field distribution.Moreover,the greater the variation amplitude with time and the speed of polarization is,the greater the influence will be.An optimization model is established according to the potential boundary,and a simple least square method based correction means through optimization is proposed to eliminate the error.