The Equalization Potential Research To The Transformer Substation Grounding

In the past, the solutions to grounding problem were always focused on resistance reduction, rather than potential equalization and isolation. Meanwhile, the formula used in current standards can only calculate the resistivity of single layer soil, yet not capable of dealing with multi-layer resistivity reasonably and precisely. At the same time, grounding standards cannot quantitatively analyze ground grid electric potential distribution and step voltage distribution, especially the latter which is considerably important in handling grounding problem.It requires systematical plan to solve the grounding problem in substations that are built on hilly land with large short-circuit current. We can not over-emphasize resistance reduction and work the solution straight away, neglecting the ideas based on potential equalization and isolation.The ideal solution to grounding problem requires a start from the potential equalization and isolation point of view, with reference to the resistance reduction step. It is greatly suggested that all the grounding problems of a certain substation solved within the substation, not only because outward grounding cabling can cause regulation and compensation issues, but also to reduce the cost of grounding and resistance reduction.Therefore, this research uses high density resistivity method to test the soil resistivity, and quantitatively analyzes the grounding grid electric potential, step voltage and touch potential with the aid of CDEGS simulation software.And the author discovers that two-layer grounding grid has good potential equalization.