Amirkabir University of Technology AUT Journal of Electrical Engineering 2588-2910 55 1 2023 03 01 GPR of Multiple Vertical Rods under Lightning Strokes Considering Ionization, Dispersion, and Non-Homogeneity of Lossy Soils 107 114 4978 10.22060/eej.2022.21747.5491 EN Saeed Reza Ostadzadeh Faculty of Engineering, Arak University, Arak, Iran. Research Institute of Renewable Energy, Arak University, Arak, 38156-88349, Iran. 0000-0002-9463-5642 Seyyed Sajjad Sajjadi Faculty of Engineering, Arak University, Arak, Iran, 0009-0009-7504-6680 Seyed Hossein Hesamedin Sadeghi Faculty of Electrical Engineering, Amirkabir University of Technology, Tehran, Iran. 0000-0003-4266-5978 Journal Article 2022 09 03 In this paper, the effects of ionization and dispersion of a lossy soil on the Grounding Potential Rise (GPR) of buried multiple vertical rods under lightning return strokes are simultaneously studied. In all studies, an efficient modeling method, called improved Multiconductor Transmission Line, is adopted. In the case of a single rod, it is shown that the simultaneous occurrence of soil ionization and dispersion causes further reduction in the value of GPR as compared to the case where each phenomenon takes place separately. The amount of reduction is further accentuated when treating highly resistive soils and fast-fronted lightning currents. In the case of multiple rods, however, the value of GPR in both ionized and dispersed soil lies between those of the only-ionized and only-dispersive soils. Besides, the sensitivity analysis of the non-homogeneity effect in ionized and dispersive soils provides a comprehensive platform to study the soil dependence of the GPR of buried rods in a multi[1]layer soil. Finally, closed-form expressions are proposed that can accurately predict the value of GPR for both single and multiple rods buried in a dispersive and ionized lossy soil when subjected to a lightning current waveform. https://eej.aut.ac.ir/article_4978_10ff0b5e85e5b85cc3095d431d8c08b4.pdf