Substation Grounding Study Input Parameter Sensitivity Analysis and Simulation Strategies

This paper focuses on the substation grounding study input parameters that significantly impact the touch or step potential calculations and the ground grid design. The input information includes the soil resistivity measurement, fault current, clearing time, and transmission line information, which are discussed in detail. Many of those input parameters are difficult to be accurately gathered or vary due to environmental or system changes. As a result, a sensitivity analysis of the input parameters is useful to identify the most influential parameters. The result shows soil resistivity, number of overhead ground wires (OHGW), and OHGW materials have the greatest impact on grounding study results. In addition, distinguishing the switching and auto-transformer stations from the true source stations during the fault current distribution analysis is also necessary. A few recommendations for improving the input parameter qualities are also provided.