Two-layer earth structure parameter estimation and seasonal analysis

The determination of soil parameters is an important topic regarding the safe and efficient design of electrical grounding systems as well as the accurate calculation of the per-unit-length parameters of overhead transmission lines and underground cable systems. Scope of this paper is to investigate the seasonal variation of the two-layer earth structure parameters and propose simple generic models for this type of the analysis. For the determination of the two-layer earth parameters the application of different optimization methods is evaluated. Furthermore, soil resistivity measurements are conducted at three different sites during a period of a whole year. The obtained results of the two-layer earth structure are analyzed, in order to investigate the seasonal variation and their correlation to changes of rainfall. From the analysis of the results significant conclusions are drawn regarding the accuracy of the resulting soil parameters as well as their annual variation.