基于静电探头法的表面电荷密度分布及电场分布的改进反演算法研究  

Improved Reverse Algorithm of Surface Charge Density Distribution and Electric Field Distribution Based on Electrostatic Probe

作　　者：邓军波[1] 王涵 薛建议 郭宝烘 王艺博[1] 张冠军[1] 

机构地区：[1]电力设备电气绝缘国家重点实验室(西安交通大学)

出　　处：《中国电机工程学报》2018年第4期1239-1247,共9页Proceedings of the CSEE

基　　金：国家自然科学基金项目(51577150);国家重点基础研究计划项目(973项目)(2015CB251003)~~

摘　　要：积聚在绝缘材料表面的电荷会畸变电场并降低绝缘水平,因此表面电荷积聚现象引起越来越广泛的关注。该文首先讨论了表面电荷密度分布与静电探头输出电位之间的关系,进而提出一种根据输出电位分布反演计算表面电荷密度和电场分布的改进反演算法。该算法利用二维离散傅里叶变换（2D-DFT）将时域中的卷积运算转化为频域中的乘积运算,大大减小了计算量。考虑了测量过程中静电探头对表面电位的影响,并采用维纳滤波技术减小噪声信号的影响。此外研究了电荷分布半径对噪声抑制以及算法精确度的影响,并评估了测量系统的空间分辨率以及算法的计算准确度。利用改进算法计算了雷电冲击电压下PMMA样品的表面电荷密度以及表面电场。结果表明：计算得到的电荷密度与电场分布具有良好的分辨率,当静电探头与材料表面间距1mm时,该测量系统分辨率达到0.3341mm,均方误差峰值仅为0.23%;减小网格单元的大小可以有效地抑制噪声干扰,对于提高算法精度具有重要作用。因此,该改进反演算法具有良好的分辨率和准确度,可准确计算绝缘材料表面积聚的电荷密度及电场分布。Surface charge accumulation on insulating materials is a major factor that distorts the electrical field and thus reduces the insulation level.Therefore,the phenomenon of surface charge accumulation has drawn more and more attention.In this paper,the relationship between the surface charge density distribution and the output voltage of electrostatic probe was discussed,and an improved algorithm was built to calculate the charge density and electrical field distribution from the output voltage.Two-dimensional Discrete Fourier Transformation（2 D-DFT） was used to reduce the amount of calculation by transferring the convolution in spatial domain to multiplication in spatial frequency domain.The algorithm considered the influence of electrostatic probe,and the Wiener filter was employed to reduce the noise.The influence of the meshed size on noise suppression and algorithm＇s accuracy was studied,and the spatial resolution of this measurement system including the reverse calculation process and the accuracy of algorithm was investigated.The charge density distribution as well as the field distribution was calculated by this improved algorithm,when a lightning impulse voltage was applied to a PMMA plate.The results show that the surface charge density and electric field distribution calculated by this algorithm have a good resolution.The spatial resolution of this measurement system with 1 mm gap between the electrostatic probe and the surface of the insulation is 0.3341 mm,and the peak-mean square error is only 0.23%.Reduce the size of the meshed unit can effectively suppress the noise and increase the algorithm＇s accuracy.The improved reverse algorithm has great resolution and accuracy,and can exactly calculate the surface accumulating charge density and electrical field distribution of insulating materials.

关 键 词：表面电荷密度分布 表面电场分布 二维离散傅里叶变换 维纳滤波 空间分辨率 

分 类 号：TM85[电气工程—高电压与绝缘技术]