Finnish Meteorological Institute models geomagnetically induced currents in Norway’s power grid
Space weather refers to the changing conditions in the region of space near Earth, which can have an impact on human activities. On the surface of the Earth, geomagnetic storms cause rapid changes in the magnetic field. These in turn create currents in all conductive materials including power grids. Such geomagnetically induced currents (GIC) can even cause power grid blackouts, such as those that took place in Canada in Quebec Province in March 1989 and in Sweden in Malmö in October 2003.
Statistics on GIC activity in Norway were compiled by using magnetic measurements collected in Norway and Northern Finland from 1994 to 2011. Although variations in the magnetic field are on average stronger in the north in the auroral zone, the largest GICs, reaching up to a few hundred amperes, were modelled in Southern Norway. There are three reasons for this: the national grid's geometry favours the occurrence of GICs in the country's southern part. The ground conductivity is also generally smaller in the south than in the north, which means that electric fields that create currents reach larger values more easily in the south. Additionally, during the strongest geomagnetic storms the entire auroral zone can shift up to 1,000 km to the south of its normal location.
The study also includes an estimate on the largest possible GIC over a 100 year period. The top currents could reach at least twice those modelled for the period of the study (1994-2011). Thus far, no significant problems directly linked to GICs have been observed in Norway. However, the grid will be expanded and possible GIC-impacts must be taken into account in the planning stage.
The study was carried out in cooperation with Statnett, the enterprise responsible for the Norwegian high-voltage power grid. The results of the EURISGIC project (European Risk from GeomagneticallyInduced Currents), which was funded by the European Community's Seventh Framework Programme and coordinated by the Finnish Meteorological Institute, were utilised in this study.
Further information:
Head of Group Ari Viljanen (Finnish Meteorological Institute ari.viljanen@fmi.fi, tel. +358 29 539 4668.
Minna Myllys (University of Helsinki)minna.myllys@helsinki.fi
Myllys, M., A. Viljanen, Ø.A. Rui and T.M. Ohnstad (2014). Geomagnetically induced currents in Norway: the northernmost high-voltage power grid in the world. J. Space Weather Space Clim.