Geoelectric field model validation in the southern California Edison system: Case study

Geomagnetic storms are a natural phenomenon that cause magnetic field variations at the surface of the Earth. These variations induce electrical current in natural and artificial conductors at and below the surface, resulting in geomagnetically induced currents (GIC) in power systems. The key to modeling GIC is to estimate the geoelectric field in the region of the power grid. The estimation of GIC follows by integrating the geoelectric field along the power transmission lines. 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 comparison of modeled GIC with measurements shows reasonable agreement and gives confidence that the modeling is physically realistic. We also demonstrate the improved accuracy of modeled GIC relative to a simpler geoelectric field model based on regional 1D conductivity profiles.