Identification of At-Risk Substations in the German Transmission Grid from Space Weather

Kurzfassung

Geomagnetically induced currents (GICs) are a space weather phenomenon resulting from natural geomagnetic disturbances and have the potential to cause the malfunction of grounded power systems. GICs are considered quasi-direct currents (DC) and can lead to half-cycle saturation in transformers. The impacts of these currents on the German power grid remain uncertain due to the lack of Germany-wide estimates or measurements. To address this gap, GICs were modelled in the German transmission grid for two geomagnetic storms: one in April 2023 and another in May 2024. These storms provide valuable cases for analysing GIC behaviour under different space weather conditions. This study highlights that the spatial distribution of high GICs does not only depend on the geomagnetic fields but is also heavily influenced by the overall configuration and orientation of connected lines. Substations that exhibit maximum GIC amplitudes in the top 5% during both events were identified as high-risk stations.