Evaluation of Lightning-Induced Voltages on Multiconductor Overhead Lines Located Above A Lossy Dispersive Ground

The paper presents a comprehensive study on the effect of soil dispersion (i.e., frequency dependence of soil conductivity and relative permittivity) on the lightning-induced voltages on single/multiconductor overhead distribution lines. For this aim, a full-wave approach based on the finite-element method is utilized. The soil dispersion is incorporated into the model using available analytical formulae obtained from experimental data. It is shown that for soils characterized by relatively moderate and low resistivity values (less than 1000 Ω.m), lightning-induced voltages are not significantly affected by the soil dispersion property. In the analyses, two different integration paths are used for obtaining the induced voltages by integrating the total vertical component of the electric field. It is shown that the soil dispersion effect on the induced voltages is negligible if the integration path continues vertically from the conductor surface to a point well below the ground surface at which the electric field vanishes. However, the soil dispersion for poorly conducting soils can markedly change the induced voltages if the integration path is considered as a vertical path between the conductor surface and the ground surface.