Extreme Value Analysis of Geomagnetically Induced Currents Based on Historical Magnetic Field Data

Geomagnetically induced current (GIC) occurring in the transmission network due to geomagnetic disturbance (GMD) events may cause power system equipment damage and/or lead to large-scale power outages. The 1-in-100 year benchmark GMD scenario, considered to be a high impact low-frequency event, is intended for use in planning for GMD events. In this paper, we estimate the 95% confidence interval for the 100-year return level of GIC flows for the transmission network of Iowa, based on extreme value analysis (EVA) of historical GIC flows calculated using historical (1979-2017) geomagnetic field data. The EVA is performed by fitting the distribution of the extreme GIC data on the family of distributions that include Generalized Extreme Value and Generalized Pareto Distribution. We compare this 100-year return level of GIC with that obtained using the NERC benchmark definition.