土壤非线性电离对单根水平接地体冲击特性参数的影响研究

土壤非线性电离效应是影响接地体散流能力的重要因素。为了研究冲击电流作用下土壤非线性电离对接地体泄流能力的影响规律,以单根水平接地体为研究对象,采用三维时域有限差分(3-D FDTD)数值分析方法,基于L-D(Liew and Darveniza)提出的土壤非线性电离效应模型;根据电磁场理论,建立了水平接地体仿真模型,然后从暂态冲击接地电阻、最大暂态地电位升(GPR)和电导率分布等接地体特性参数角度来研究水平接地体冲击散流的物理过程。研究表明:1雷电流在接地体及其周围土壤的散流是复杂的电磁暂态过程,接地体的散流极不均匀;2土壤非线性电离效应减小暂态冲击接地电阻,而且考虑了土壤非线性电离效应的最大暂态地电位升要远远低于未考虑土壤非线性电离的情况;3接地体端部附近土壤电离区域大于中部附近电离区域,具有明显的端部效应。

Influence Study of Soil Nonlinear Ionization effect on impulse Characteristic parameters of Single Horizontal Grounding Electrode

Soil nonlinear ionization effect is an important factor of influencing the dispersing capacity of the grounding electrode.In order to study the effct of soil nonlinear ionization on the dispersing capacity of the grounding electrode under the impulse current conditions, based on soil nonlinear ionization model proposed by L-D(Liew and Darveniza), based on electromagnetic field theory, this paper chooses single horizontal grounding electrode as research object and uses three-dimensional finite-difference time-domain method(3-D FDTD) to develop vertical grounding electrode simulation model and then it is easy to analyze the impulse dispersing of horizontal grounding electrodes from the maximum transient ground potential rise and impulse grounding resistance and electric conductivity distribution and so on . The results indicate that 1)the dispersing of lightning current in grounding electrodes and its surrounding soil is a complicated electromagnetic transient process, the dispersing of grounding electrodes is extremely inhomogeneous; 2)soil nonlinear breakdown effect decreases impulse grounding resistance, the maximum transient ground potential rise when considering the soil nonlinear ionization effect is much smaller than that when not considering the soil nonlinear ionization effect;3) the ionization region of the surrounding soil of the terminal of grounding electrode is larger than that of the surrounding soil of the central section of grounding electrode,which has obvious end effect.