Improved Modeling of Geomagnetically Induced Currents Utilizing Derivation Techniques for Substation Grounding Resistance

This paper focuses on estimating the substation grounding resistance to improve the modeling of geomagnetically induced currents (GICs). Grounding resistances are not included in the standard power flow models, and their approximate values are often used for performing GIC studies. This paper provides an algorithm to estimate the resistances from the GIC measurements. This algorithm calculates the linear sensitivity factors of the GICs around the local grounding resistive components and uses linear regression to solve for the resistances. The effectiveness of the proposed algorithm is demonstrated using both a small test case as well as a 62 500-bus model of the North American Eastern Interconnection.