基于leap-frog算法的考虑土壤频率特性对配电线路耦合入、散射电压的影响  

Influence of Soil Frequency Characteristics on Coupling and Scattering Voltage of Distribution Lines Based on Leap-Frog Algorithm

作　　者：李国昌 LI Guochang(State Grid Beijing Electric Power Research Institute,Beijing 100075,China)

机构地区：[1]国网北京市电力公司电力科学研究院,北京100075

出　　处：《电瓷避雷器》2020年第6期64-68,共5页Insulators and Surge Arresters

基　　金：国网北京电科院项目(编号:630223170060)。

摘　　要：针对土壤电导率与不同频率下的电磁场衰减具有一定的相关性,且在雷电过电压计算过程中简单的将土壤电导率考虑为定值存在较大缺陷的现状。笔者首先采用跳跃时间步进(leapfrog)技术结合FDTD算法对Maxwell方程组在柱坐标系下进行离散处理,对闪电回击电磁场进行快速计算,同时结合Agrawal耦合模型对总感应过电压进行计算,并将总感应过电压拆分成入射、散射电压,主要研究雷击地面情况下,土壤变频特性对线路中点、端点位置处耦合入射、散射电压峰值及波形的影响。研究表明:土壤变频特性使中点位置处总感应过电压峰值削减28%,入射电压峰值抬升38%,对散射电压峰值影响较小,该位置处感应过电压主要由垂直电场决定;土壤变频特性使端点位置处总感应过电压峰值削减39%,散射电压峰值削减58%,远距离感应过电压主要由水平电场决定,同时土壤变频特性使总感应过电压、散射电压双极性波形在一定程度上进行了削弱。因此在线路耦合雷电过电压计算研究工作中,必须要考虑土壤变频特性对其影响。In view of the fact that soil conductivity is correlated with electromagnetic field attenuation at different frequencies,and there are some defects in simply considering soil conductivity as a fixed value in the calculation of lightning overvoltage. Firstly,Maxwell equations are discretized in cylindrical coordinates by leap-frog technique and FDTD algorithm. The electromagnetic field of lightning return stroke is calculated rapidly. At the same time,the total induced overvoltage is calculated by Agrawal coupling model. The total induced overvoltage is divided into incident and scattering voltages. The main research is about the frequency conversion of soil under lightning strike. The influence of the characteristics on the coupling incidence,peak scattering voltage and waveform at the neutral and terminal positions of the transmission line. The results show that the peak value of total induced overvoltage at the midpoint is reduced by 28% and the peak value of incident voltage is increased by 38%,which has little effect on the peak value of scattering voltage. The induced overvoltage at the midpoint is mainly determined by vertical electric field;the peak value of total induced overvoltage at the endpoint is reduced by 39%,the peak value of scattering voltage is reduced by 58%,and the long-distance induced overvoltage is mainly determined by horizontal electric field. At the same time,the bipolar waveforms of total induced overvoltage and scattering voltage are weakened to some extent due to the characteristics of soil frequency conversion.Therefore,the influence of soil frequency conversion characteristics on the calculation of lightning over-voltage in circuit coupling must be considered.

关 键 词：leap-frog 土壤频率 入射 散射 垂直电场 

分 类 号：S153.2[农业科学—土壤学] TM86[农业科学—农业基础科学]