Effect of the Earth’s lateral conductivity variations on geomagnetically induced currents in power grids

Abstract

Modeling the geomagnetically induced currents (GIC) is essential to assess the GIC risk to power systems with geomagnetic disturbances. Lateral variations in the Earth’s conductivity significantly influence the behavior of GIC created in a large power grid. To figure out the influence, this study developed block and thin shell models of the Earth’s conductivity considering abrupt conductivity variations. Simulations were then conducted to analyze the GIC distortion near the boundary. We presented four different scenarios to investigate different Earth models with lateral conductivity changes, and we evaluated the effects on GIC in case studies with two-node transmission line models that were executed parallel or perpendicular to the boundary. The results demonstrate that the influence of lateral conductivity variations on GIC can be significant, and that these effects should be considered in GIC modeling, except in cases where the percent difference owing to the effect does not exceed 10%. In these cases, the GIC can be calculated directly using the piecewise model. The methods and results presented herein can provide a theoretical basis for GIC modeling and risk assessment for power systems.