Geomagnetically Induced Currents in European High-Voltage Power Systems

Geomagnetically induced currents (GIC) in power systems are a ground manifestation of space weather arising from solar activity. Most of the research on GIC done in Europe so far refers to Scandinavian power grids. A power outage due to GIC occurred in southern Sweden in October 2003. The principal reason that similar GIC problems as in Sweden have not occurred in Finland is in the use of different transformer types in these two countries. However, due to the northern location, research on GIC in the Finnish high-voltage system is continued. The largest GIC recorded in 400 kV transformer neutrals are 320 A and 201 A in Sweden and Finland, respectively. GIC magnitudes in a system do not only depend on the intensity of magnetic disturbances but network parameters (resistances and topology) also play a significant role. The increasing size of the European high-voltage power grids, the complex interconnections and the extensive transport of energy between different countries make today's systems more prone to GIC problems