土壤非线性击穿效应对垂直接地体散流特性的影响  

Influence Study of Soil Nonlinear Breakdown Effect on Dispersing Characteristics of Vertical Grounding Electrodes

作　　者：陶玉郎 侯文豪[1] 张其林[1] 王梦寒[1] 陈隆[1] 申元[2] 冯建伟 

机构地区：[1]气象灾害预报预警与评估协同创新中心(南京信息工程大学),江苏省南京市210044 [2]云南电网有限责任公司电力科学研究院,云南省昆明市650217 [3]苏州气象局,江苏省苏州市215000

出　　处：《电网技术》2017年第5期1689-1696,共8页Power System Technology

基　　金：国家重点基础研发项目(2014CB441405);国家自然科学基金项目面上项目(41575004)~~

摘　　要：基于L-D(Liew and Darveniza)提出的土壤非线性击穿模型,利用Taku Noda和Yoshihiro Baba等分别提出的导体在无耗介质和有耗介质中的细导线处理方案,开发了一套三维时域有限差分(three dimension finite-difference timedomain,3-D FDTD)算法,研究了在不同雷电流幅值和波形以及土壤低频电导率作用下,土壤非线性击穿效应对垂直接地体受土壤击穿影响的散流区域、冲击阻抗和暂态地电位升等参数的影响。结果表明,当土壤低频电导率为0.02 S/m和0.005 S/m时,垂直接地体横向散流半径分别约为0.5 m和1.2 m;接地极尖端部位的纵向散流区域分别约为0.3 m和0.9 m。此外,暂态地电位升的变化特性与注入的雷电流幅值和波头时间以及土壤低频电导率密切相关,但无论是否考虑土壤击穿效应,垂直接地极冲击阻抗最大值保持不变,仅决定于土壤低频电导率等相关土壤特性参数。工程上定义的冲击阻抗值仅表征了未考虑土壤击穿情况下的稳定阶段阻抗值,远小于文中计算的冲击阻抗最大值。Based on soil nonlinear breakdown process proposed by Liew and Darveniza and thin wire treatment scheme of conductor in lossless and lossy medium respectively proposed by Taku Noda and Yoshihiro Baba et al., an three-dimensional finite-difference time-domain（3-D FDTD） algorithm is developed to analyze effects of soil nonlinear breakdown process on dispersing area influenced by soil breakdown of vertical grounding electrode, surge impedance, transient ground potential rise and other key parameters of grounding techniques in different soil electric conductivities at low frequency and different intensity of lightning current and waveform. Results indicate that vertical grounding electrode has obvious transverse and longitudinal direction discharging characteristics, and the transverse discharging radiuses of vertical grounding electrode are roughly 0.6 m and 1.2 m, respectively, and longitudinal direction discharging radiuses along grounding electrode top are roughly 0.3 m and 0.9 m, respectively, for soil electric conductivities at low frequency of 0.02 S/m and 0.005 S/m. Transient ground potential rise is closely related with surge current wave front time and peak value and soil electric conductivity. However, whether considering soil nonlinear breakdown effect or not, maximum value of transient surge impedance remains the same, depending only on soil electric conductivity at low frequency. The defined surge impedance value in grounding engineering is similar to minimum value of transient surge impedance without considering soil breakdown effect, much less than peak value of surge impedance.

关 键 词：垂直接地体 冲击特性 土壤非线性击穿 三维时域有限差分(3-D FDTD)算法 冲击阻抗 

分 类 号：TM86[电气工程—高电压与绝缘技术]