Validating GIC Models With Measurements in Austria: Evaluation of Accuracy and Sensitivity to Input Parameters

Space weather events can cause geomagnetically induced currents (GICs) in power transmission networks. Over the past years, these currents have been measured in multiple substations in Austria, and the measurements have been tested against a model of local GIC with the aim of producing an optimized model, which can be developed through evaluation of various input parameters. We show the impact the choice of the local resistivity, in particular the surface conductivity in thin-sheet modeling, and the source of geomagnetic variations has on GIC modeling. In addition, the sensitivity of the model to the accuracy of the network configuration is also investigated. This encompasses the inclusion of power grids outside of Austria in the model as well as the consequences of removal of a substation either through transformer failure or active disconnection. Results show that a detailed surface conductivity model brings benefits to areas with large lateral conductivity variations and that there are certain substations that lead to increases and decreases of GIC in the rest of the network when removed. The importance of regionally representative geomagnetic field measurements is also highlighted and shown to impact model accuracy. This study concentrates on regional effects, but the results are also valid for large-scale studies elsewhere.