Geomagnetically induced currents in the German power grid

Kurzfassung

Space weather driven geomagnetically induced currents (GICs) occur under conditions of intense geomagnetic disturbance (GMD), which is particularly strong in the vicinity of the high-latitude ionospheric electrojets during magnetospheric substorms. By now, it is well established that even mid-latitude regions are at risk of GICs disrupting ground conducting systems in response to the storm-time expansion of the auroral electrojets. Nevertheless, GIC research in Germany is still in its infancy. Here, we present our current progress toward a comprehensive assessment of the GIC risk in the German high-voltage power grid. Our analyses comprise both the geophysical as well as the engineering side of the problem. The first part is concerned with the quantification of the GIC hazard imposed by critically large induced electric fields. Given the scarcity of direct measurements, we calculate the induced electric field by applying the plane wave approach with a 1-D conductivity model (EURISGIC) to maps of GMD generated from spatially interpolated INTERMAGNET observatory measurements. The engineering part of the problem deals with the exposure and vulnerability of the power grid to the hazard imposed by the induced electric fields. This requires knowledge of the technical specifications of the German high-voltage transmission network, which we collect from publicly available sources. Future efforts will include the validation of the outlined calculation scheme by direct measurements of GICs at German transformer substations.