The space weather hazard to the German power grid derived from geomagnetically induced electric field modeling

Kurzfassung

Space weather driven geomagnetic disturbances can induce geoelectric fields in the subsurface that give rise to currents flowing through the groundings of power transformers into the high voltage transmission grid. Those parasitic currents, commonly referred to as geomagnetically induced currents (GICs), can potentially damage and/or cause malfunction of inductive grid components with significant socioeconomic ramifications. In terms of a GIC risk assessment the hazard posed by large geoelectric field amplitudes can be quantified based on extreme value statistics. This contribution focuses on the geoelectric field modeling approach adopted to derive meaningful GIC hazard maps for Germany down the line. The solution of the induction problem requires an appropriate processing of oneminute mean geomagne tic measurements from four German and surrounding INTERMAGNET observatories as well as their connection with a conductivity model derived from magnetotelluric surveys across Germany. The electric field modeling is imbedded within our GIC calculation scheme which is illustrated exemplarily by means of resulting GICs in the northwestern part of the German power grid during historic geomagnetic storms. Given the interdisciplinary nature of the GIC topic combining elements of extraterrestrial physics, geo-electromagnetism, electrical engineering and natural hazard research we appreciate this opportunity to touch base with experts of the German geoelectric community.