Grounding system analysis and design considerations for large hydroelectric power plant are analyzed and discussed in this paper. The main work that has been carried out includes: constructing adequate soil structures and analyzing the effects of the finite heterogeneous soil structure, the modeled river length and the water reservoir levels; conducting accurate fault current distribution calculations and studying the influence of circulating current on the touch and step voltages. The paper discusses the design of the grounding system and its safety performance while considering the impact of the circulating current and inductive coupling from cables and long parallel conductors inside the plant. Two practical examples have been provided in this paper. Furthermore, the paper demonstrates the effectiveness of using heterogeneous finite soil volumes to analyze large hydroelectric power stations and confirms that accurate grounding software packages are required to account for large circulating currents within the ground conductors and strong inductive coupling that exists between metallic elements within the substation. The results and discussions presented here can be used as a reference for engineers to analyze extensive grounding systems and to design appropriate grounding systems for large hydroelectric power plant.
Comparative study between transmission line theory and the electromagnetic field approach in grounding system analysis