The engineering practice and case analysis of substation grounding grid design

Abstract

To meet the requirement of developing electric power grid, safety performance of substation grounding grid becomes one of the most common focused issue of substation grounding grid design. Characteristic parameters is the key to achieve an accurate evaluation for substation grounding grid. Several measures such as formula calculation, simulation, and actual test were utilized to compare the accuracy in grounding grid characteristic parameters evaluating, taking one typical 500kV substation with high soil resistivity for instance. Analysis of problem existing and factor contributing is also involved in this article. The analysis results show that the depth of the grounding grid soil resistivity is not enough and the influence of the fault current provided by the substation lines on the shunt coefficient is not the main factor of the accuracy of the grounding grid design. In the substation grounding project design stage, test the depth of the soil resistivity of at least 2/3 diagonal substation system, maximum operating mode and through the scheduling of parts of the single phase grounding short circuit current grounding shunt coefficient calculation, can significantly improve the accuracy of design parameters of grounding grid.