The power system in Finland
The power system in Finland consists of power plants, the main grid, regional networks, distribution networks, and consumers of electricity. The Finnish system is a part of the Nordic power system together with the systems in Sweden, Norway and Eastern Denmark. Moreover, there is a direct current connection from Russia and Estonia to Finland, enabling connection between these systems which apply different principles. Correspondingly, the Nordic power system has been connected to the system in Continental Europe through direct current connections.
Fingrid is responsible for the operational planning and supervision of the main grid and for grid maintenance and grid development. The main grid serves power producers and consumers, enabling electricity trade between these throughout Finland and also across Finnish borders. Most of the power consumed in Finland is transmitted through the main grid.
The main grid in Finland managed by Fingrid encompasses approximately
- 4,100 km of 400 kV transmission lines (kV = kilovolt = 1,000 volts)
- 2,350 km of 220 kV transmission lines
- 7,500 km of 110 kV transmission lines
- 106 substations.
In the grid, high voltage levels are used when operating with long transmission connections and high transmission capacities in order to minimise losses in electricity transmission. No need to use higher voltages can be seen.
The Finnish grid has mainly been constructed by using air isolation, in other words, substations have been installed outdoors and the transmission lines are open-wire lines. Underground cables are used minimally, because they are unreasonably expensive at long transmission distances typical of Finland and because they restrict land use in the area where the cable has been buried. When old substations are extended or when the space available is otherwise very limited, so-called gas-insulated switchgears are used, in which the live parts have been enclosed in a metal casing which contains pressurised insulation gas.
To achieve a sufficient transmission capacity combined with operational reliability as efficiently and economically as possible, the adoption and development of new technologies is considered continuously. This normally takes place with the help of research and development projects.
Regional networks are connected to the main grid, and they transmit electricity regionally, usually by means of one or more 110 kilovolt lines.
Distribution networks are either connected directly to the main grid or they utilise the grid services through a regional network. Distribution networks operate at a voltage level of 0.4 to 110 kV. Households are connected to distribution networks. Industries, commerce, services and other consumption (such as agriculture) are connected to distribution or regional networks or to the main grid, depending on each individual case.
Power plants are connected to distribution or regional networks or to the main grid depending on each individual case.
