GIS中局部放电与超高频电磁波关系的仿真研究

GIS内部由于存在各种绝缘缺陷而发生局部放电时,会激发起数百MHz至数GHz的超高频(UHF)电磁波在GIS腔体内传播。笔者根据电磁波在同轴波导中的传播理论,运用有限差分时域(FDTD)算法,对局部放电脉冲波形与其激发UHF电磁波之间的关系进行了仿真分析。首先研究了局部放电量与电磁波电场强度的关系,指出在一定的局放脉冲电流变化率下局放量的变化对电磁波电场强度的影响较小;然后研究了局放脉冲电流变化率与电磁波电场强度的关系,指出在局放量一定时二者近似呈线性关系;最后研究了局放脉冲电流变化率对电磁波中高次模成分的影响,运用变异系数对高次模成分在电磁波中所占比例大小进行分析,指出高次模成分所占比例随局放脉冲电流变化率的增大而增大。

Simulating the Relationship between PD Waveform and UHF Electromagnetic Wave in GIS

Partial discharge appears when GIS is contaminated by the defects such as needle protrusion,metallic particle,etc., exciting ultra high frequency(UHF)electromagnetic waves ranging from several hundreds of MHz to several GHz in GIS.In this paper,the finite difference time domain method is used to simulate the relationship between PD waveform and PD-induced UHF electromagnetic wave in GIS.Firstly,the relationship between PD magnitude and the peak to peak(p-p)value of PD-induced electromagnetic wave is evaluated,and the simulation results show that p-p value of PD-induced electromagnetic wave is not sensitive to the variation of PD magnitude.Secondly,the relationship between PD current change rate and p-p value of PD- induced electromagnetic wave is studied,and the simulation results show that the two factors are about correlated linearly. Finally,the relationship between PD current change rate and the proportion of higher order modes in the PD induced electromagnetic wave is investigated using the coefficient of variation,and the simulation results show that the proportion of higher order modes increases when the change rate of PD current increases.