Abstract
Designing an effective grounding system for AC substations needs predetermination of ground resistance and ground potential distribution caused by fault current’s presence in the ground. Therefore, it is necessary to have a suitable grounding grid structure in the soil properties in which the grid is buried. Though the soil composition where the grounding grid is located is typically non-homogeneous, the soil is often presumed to be homogeneous due to the complexities of grounding system analysis in non-homogeneous soil. This assumption will lead to inaccuracies in the computation of ground resistance and ground potentials. Although extensive research has been done on non-homogeneous soil structure, comprehensive literature on grounding system performance in non-homogeneous soil is yet to be reviewed. Thus, this paper reviews the effect of non-homogeneous soil on the grounding system, with different soil characteristics in horizontal and vertical two-layer soil structure and the horizontal three-layer soil structure. In addition, the effect of design parameters on the grounding performance in non-homogeneous soil conditions for non-transient fault conditions is also studied. The significance of this study is that it provides a comprehensive review of grounding performance as grounding design changes and their effects as soil layers and their corresponding features change. This knowledge will be useful in developing safe grounding designs in non-homogeneous soil.
Highlights
The earth is made of multiple compositions with distinct soil properties.The electric constants of soil, such as permittivity (ε) and resistivity (ρ) depend on the type of soil such as sand, limestone, clay, or gravel [1,2,3,4,5,6,7]
Some fundamental information and equations on two-layer soil structure are available—most standards and regulations specify grounding grid designs based on homogenous soil conditions
Owing to the complexities of computations needed to resolve the problem, often the soils are assumed to be homogenous, which resulted in significant inaccuracies
Summary
The earth is made of multiple compositions with distinct soil properties. The electric constants of soil, such as permittivity (ε) and resistivity (ρ) depend on the type of soil such as sand, limestone, clay, or gravel [1,2,3,4,5,6,7]. Some fundamental information and equations on two-layer soil structure are available—most standards and regulations specify grounding grid designs based on homogenous soil conditions. Due to the ifdifficulty of the numerical computations required, grounding design will be inaccurate non-homogeneous soil conditions are not taken multiple soil during layers are ignored when designing a grounding system. Various characteristics groundoffers a comprehensive ing system performance.review of the effects of non-homogeneous soil structure (two and three-layered horizontal soil and two-layer vertical soil), with various characteristics on grounding performance. Effect of Horizontal Two-Layer Soil Characteristics on Grounding System Performances
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
