High frequency response of grounding electrodes: effect of soil dielectric constant

Abstract

Grounding electrodes have an important role in electric power transmission and distribution systems. They are used to prevent excessive hazardous voltages due to ground potential rise in the case of system faults or lightning surges. The electrical properties of soil, which vary substantially with geographical location and time of year, affect the process considerably along with the properties of the grounding electrode itself, such as its dimensions. To have an accurate estimation of the induced overvoltages due to lightning strike, one has to take into account the effect of the value of the soil electrical parameters, such as the electrical conductivity and dielectric constant. This study investigates the high frequency behaviour of the grounding electrodes by solving a full-wave electromagnetic problem using the finite element method. The focus of this paper is on the effect of the variation of soil relative permittivity on the induced transient voltage in grounding electrodes. This allows an evaluation of the response of grounding systems due to seasonal changes, which would cause its electrical properties to vary significantly. This study demonstrates the importance of considering the variation of relative permittivity of the soil especially in the modelling of electrodes buried in highly resistive soil.

Analysis of the Influence of Complex Terrain around DC Transmission Grounding Electrodes on Step Voltage

“…That study is not yet complete [6,7]. In recent years, research on the influence of a geomorphic soil environment on HVDC transmission has made some progress [8][9][10]. For example, Professor Xiong Qi [11] established an anisotropic three-dimensional model for complex landforms.…”

Remote sensing assessment of land use and crop parameters in irrigated systems

“…Because the penetration capacity of a radiation increases with wavelength, the radiation in the microwave region can penetrate in the surface and, therefore, it is also affected by internal leaf structure, soil structure or soil roughness among other parameters (McNairn and Shang, 2016). The radiation backscattering in this region is sensitive to the dielectric constant, and typically increases with water content due to the high dielectric constant (~ 80) of the water relative to the dry soil (~ 4) or air (~ 1) (Fawwaz et al, 1996;Mandal et al, 2020;Salarieh et al, 2020). Because the microwave radiation reflected by a crop field is driven by the canopy and soil structure, and water content, the radiation reflected in this region is sensitive to biomass, plant growth dynamics, and soil and vegetation water content, among other parameters (McNairn and Shang, 2016;Mandal et al, 2020).…”