摘要
随着超特高压电网的出现和系统容量的不断扩大,入地故障电流也随之不断增加,此时接地装置周围土壤在散流过程中将呈现明显的非线性特性。为此,针对大幅值故障电流下土壤的非线性特性,提出一种计算接地装置特性的有限元模型。对有限元计算中的无穷边界问题引入空间坐标变换方法,通过改变介质参数将电场控制在有限范围内,在保证计算精度的基础上降低了计算量;对于由接地导体与土壤分界面处介质突变引起的病态方程,采用有限元方程的弱解形式,降低了微分方程对场量连续性的要求,加快了方程的收敛速度;针对大幅值入地电流下土壤的非线性特性,在有限元计算中令单元土壤电阻率为该单元电场强度的函数,采用非线性有限元算法加以考虑。将此模型对典型接地装置的仿真结果与相关实测及文献计算结果对比,验证了其分析接地装置非线性特性的有效性。
With the development of the power system,the nonlinear characteristic of soil in the vicinity of the grounding electrode is so serious that it should be included in the calculation of grounding system.Consequently,a finite-element model which calculates the response of grounding system under high-magnitude fault current is presented.Moreover,open boundaries of earth environment are processed by introducing a spatial transformation,the ill conditioning of the matrix to be solved because of the marked rise in conductivity between ground and copper are resolved by the weak form of finite element method,and the nonlinear characteristic of soil under an accidental short circuit is taking into account by setting the resistivity of soil element varying with the electric field intensity.The suggested model is validated by comparing the calculated results from grounding rod and grounding grid with experimental tests results and simulations results found in literatures.
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2011年第1期249-256,共8页
High Voltage Engineering
基金
国家重点基础研究发展计划(973计划)(2009CB724504)~~
关键词
接地网
土壤非线性特性
有限元法
弱解形式
空间变换
地表电位分布
grounding grid
soil nonlinear characteristics
finite element method
weak form
spatial transformation
earth surface potential distribution
