The influence of the coast effect on geomagnetically induced currents: A modeling study

Assessing the risk to power systems from geomagnetically induced currents (GIC) requires calculations of the geoelectric fields at the Earth's surface. These geoelectric fields are influenced by the boundary between different Earth conductivity structures such as the coastline. This paper uses the finite element method (FEM) to model a three-region conductivity structure to examine the influence of the coast effect on geoelectric fields. A simple power system model consisting of two substations linked by a single power line is used to illustrate how the geoelectric field changes influence GIC in a power grid. The results show that different ocean structures have a significant impact on the GIC especially at lower frequencies. This demonstrates that geoelectric field shifts near coastlines should be taken into account when assessing GIC risk for power grids located within the coastal influence range.