Geoelectric Field Model Validation in the Southern California Edison System: Case Study

In this study, we test the accuracy of the NOAA/USGS geoelectric field model during two geomagnetic storms in a regional power grid of the Southern California Edison system. Our approach is to calculate geomagnetically induced current (GIC) by integrating the modeled geoelectric field along the power transmission lines, analyze the flow of current based on the system configuration, and compare the modeled GIC flow in a transformer with measurements. Our comparison with measurements shows reasonable agreement, having linear correlation of 0.82 for the first storm and 0.83 for the second storm. We also demonstrate the improved accuracy of modeled GIC relative to a simpler geoelectric field model based on regional 1D conductivity profiles for which we found lower correlations of 0.46 and 0.49 for the first and second storms respectively.