A novel segmented sampling numerical calculation method for grounding parameters in horizontally multilayered soil

Abstract

The grounding devices guarantee the safe and stable operation of the power system and electrical apparatus. The accurate calculation of grounding parameters lays the theoretical basis for the design and maintenance of grounding devices. The existing calculation methods for grounding parameters in layered soils are mainly based on the complex image method with global sampling. On the one hand, the global sampling method cannot accurately approximate the integral kernel of Green’s function in complicated horizontally layered soils with many thick layers, which would cause large calculation errors or divergent results. On the other hand, the number of complex images is often twice the number of soil layers, which would cause the calculation amount blindly increases linearly with the number of soil layers. To solve the above disadvantages, this paper proposes a novel segmented sampling numerical calculation method (SSNCM) for grounding parameters in horizontally layered soils. The segmented sampling calculation method of Green’s function based on the extreme points of the integral kernel function of Green’s function in layered soils and the unequal potential calculation method for grounding devices in layered soils are studied to form the SSNCM. The cases study on 3 typical grounding devices are calculated by the SSNCM and the software CDEGS. The results show that the SSNCM has better calculation efficiency and adaptability for different layered soils, and can provide a theoretical foundation for grounding parameters analysis and grounding devices design.