分层土壤中接地装置冲击散流特性的有限元分析模型  

Finite Element Model of Impulse Dispersing Characteristics of Grounding Equipment in Layered Soil

作　　者：朱时阳[1] 袁涛[2] 朱彬[2] 

机构地区：[1]广西电网公司电力科学研究院,广西壮族自治区南宁市530023 [2]重庆大学电气工程学院,重庆市沙坪坝区400044

出　　处：《电网技术》2014年第8期2304-2309,共6页Power System Technology

基　　金：国家自然科学基金项目(51107153)~~

摘　　要：冲击电流在分层土壤中的散流过程具有明显的非线性变化特征,从电磁场理论出发,建立了分层土壤结构中接地装置冲击特性分析的有限元模型。在非线性过程的分析中考虑了传导和位移电流,准确地反映了冲击散流的物理过程;针对接地导体与土壤分界面、土壤分层界面的电阻率突变而造成有限元计算不易收敛的问题,采取了具有连续偏导数的平滑阶跃函数进行过渡的方法;在将无限散流空间变换为有限计算区域的问题上,提出了分层结构土壤的几何坐标变换方法,既减少了计算量又保证了计算准确度,并将仿真计算结果与试验结果进行对比分析。结果表明该模型能较好地模拟分层土壤结构中,土壤电离不均匀性和放电通道随机性带来的非线性变化问题,验证了模型的有效性。The process of impulse current scattering into layered soil possesses obvious feature of nonlinear variation. Based on electromagnetic field theory a finite element model is established to analyze the impulse characteristics of grounding device in layered soil. In the analysis on the nonlinear process, both conduction current and displacement current are taken into account to reflect the physical process of impulse current scattering into layered soil accurately. To cope with the problem that the finite element computation is not easy to converge due to the sudden change of resistivity at the boundary surface between the grounding conductor and that between the interfaces of layered soil, a method, in which the smooth step function with continuous partial derivative is used for the transition, is adopted; to transform the infinitive scattering space into finite computational region, a geometric coordinate transform method for the soil with layered structure is proposed, thus the calculated amount is reduced while the computation accuracy can be ensured. Simulation results and experimental results are compared and analyzed, and it is shown that using the proposed model the non-linear variation due to non-uniform ionization of soil and the randomness of discharge channel in layered soil structure can be simulated well, thus the effectiveness of the proposed model is validated.

关 键 词：接地装置 分层土壤 几何坐标变换 平滑函数 有限元模型 

分 类 号：TM85[电气工程—高电压与绝缘技术]