Grid development and maintenance

National grid planning always has a holistic and forward-looking approach. Fingrid’s current grid vision extends to 2040. The grid vision is insight into the long-term development needs of the main transmission grid, including follow-up plans for the current projects. Our objective is to carry out the investments in the transmission grid in an effective and timely manner, both in terms of the national economy and grid maintenance. Transmission grid planning anticipates future needs decades in advance, as we build and maintain the grid safely and in a flexible manner to meet society’s electricity production and consumption needs. 

The vision is based on anticipated future challenges as well as requirements for the transmission of electricity due to changes in production and consumption. The current grid vision is dominated by the transition from fossil fuels to renewable forms of energy that are becoming more competitive by the day. This means growing transmission needs that also vary in time, particularly between northern and southern Finland.



Grid planning has a market-oriented approach. A well-functioning electricity market benefits all: extensive international markets and strong transmission connections boost competition and ensure that electricity is always produced in the most efficient way. A bottleneck in the transmission link between Finland and Sweden, for example, may cost consumers several million euros a day. Reinforcing the domestic and cross-border transmission systems in Finland will improve the operations of the electricity market. In a strong transmission network, electricity can freely flow to where demand is highest.


Completed and ongoing projects

Power lines and substations were built extensively throughout Finland in 2018. The following transmission lines were commissioned: Lieto–Forssa, Elovaara–Pinsiö, Onnela–Vuoksi, Vanaja–Tikinmaa, Vihtavuori–Koivisto and Koria–Yllikkälä. A total of approximately 250 kilometres of new transmission lines were built. Seven substation projects were completed (Hikiä, Huutokoski, Lieto, Porvoo, Iisalmi, Vuoksi and Rännäri).

New Vihtavuori–Koivisto connection vital for bioproduct mill

In January 2018, we commissioned a 110-kilovolt transmission line between Vihtavuori and Koivisto. The line extends roughly 26 kilometres and was built parallel to the existing Jyväskylä/Vihtavuori–Äänekoski/Koivisto transmission line to serve Metsä Group’s new Äänekoski bioproduct mill.

Iron Lady II

The transmission line system from Imatra to Turku received a name that celebrates history, Iron Lady II. In the early years of Finland’s independence, after 1917, it was thought that the Imatra hydropower plant alone would be sufficient to supply the entire country with electricity. However, its current output, 192 megawatts, only covers a small percentage of Finland’s peak consumption of around 15,000 megawatts. The grid has adapted to changing times.

This transmission link is being modernised stage by stage, between Lieto and Forssa, Koria and Yllikkälä, and Hikiä and Orimattila. The final sections of the first high-voltage transmission line in Finland, between Imatra and Turku, ‘Iron Lady’, will be dismantled next year.

The 400-kilovolt + 110-kilovolt line between Lieto, close to Turku, and Forssa, totalling 67 kilometres, is already in use. The modernised 110-kilovolt and 82-kilometre transmission connection from the Kouvola Koria substation to Yllikkälä, close to Lappeenranta, was completed and successfully commissioned during the review period.

The last section of the old line will be replaced by a new line to be built between Hikiä and Orimattila, which will be completed by the end of 2019. The new transmission will run from Hikiä to Iso-Henna, following the old Iron Lady’s right-of-way. A 16-kilometre section of transmission line from Iso-Henna to Orimattila will be built on a new right-of-way, loosely following the Lahti highway.

Transmission lines starting from the Vuoksi substation

A new Vuoksi substation has been built between Joutseno and Imatra, and the transmission lines east and west of there will be modernised. The new 110-kilovolt substation was commissioned in 2018 and the new transmission lines will be completed in stages in 2018 and 2019. As the need for energy grows in the future, a 400-kilovolt substation will be built at Vuoksi, with a possibility to link it to Fingrid’s 400-kilovolt network via the 400/110-kilovolt Lempiälä–Vuoksi transmission line currently under construction.

The new substation and the transmission line routes to the east (to Onnela) and west (to Lempiälä) became topical when Kemira decided to expand the production capacity at its chlor-alkali site in Joutseno. The area, in general, is highly industrialised, and the grid investment will improve the operating conditions for other companies as well.

Third AC connection to Sweden

The new 400-kilovolt connection from Pyhänselkä in Muhos to Keminmaa and further on to the Messaure substation in Sweden is a strategic transmission link for us. The detailed planning of the right-of-way and the environmental impact assessment (EIA) for the project are currently underway. The transmission link will be built in stages simultaneously in both countries. The agreed border crossing site is at Vuennonkoski on the Tornionjoki river. A total of around 200 kilometres of new powerline will be built on the Finnish side. The goal is to use the existing power line right-of-ways as much as possible. EU support will be applied for, and all stages of the connection are expected to be completed in 2025. The busiest construction stage will be in 2023 and 2024.

The need to build a third AC connection between Sweden and Finland is a telltale sign of the ongoing energy transformation. Finland has a growing need to link up with its neighbours and at the same time reinforce the north–south transmission connections. While helping to scale down the use of fossil fuels for electricity production, these capacity upgrades will also enable the transmission of wind power produced in northern Finland to southern Finland.


Investment decisions and planned investments

A record-breaking 600 kilometres of new transmission lines are in the general planning stage in 2019. Our projects will proceed to the construction stage within the next few years.

Forest Line to reinforce north–south transmission connections

The bulk of electricity consumption in Finland is in the south, which is the destination of electricity transferred from northern Finland and Sweden to serve the needs of energy consumers. The electricity production of the thermal power plants in the south of Finland is decreasing and being replaced with affordable and carbon-neutral energy production from the north. Moreover, Fingrid is planning, in co-operation with the Swedish TSO, a third transmission link between the countries, to be completed in 2025. These changes will further increase the need for north–south transmission capacity.

The transmission line that is currently in the general planning stage, which we have named the Forest Line, is more heavy duty and modern than the previous transmission line from central Finland to Oulu. This is a 310-kilometre-long 400-kilovolt transmission line.

The planned start of construction of the Forest Line is autumn of 2019, and it is expected to be completed by the end of 2022.

Grid reinforcing measures in North Karelia

We are replacing 110-kilovolt transmission lines between Uimaharju and Pamilo, Kontiolahti and Uimaharju, and Kontiolahti and Pamilo in North Karelia. These transmission lines built in the municipality of Kontiolahti and the city of Joensuu in the 1960s are rather aged and no longer have sufficient transmission capacity. After the grid reinforcing measures, the lines will be better positioned to meet future needs.

The grid reinforcing measures in North Karelia are in the general planning stage. The first section, from Uimaharju to Pamilo, will be built between January and September of 2019. The second stretch to be replaced, from Kontiolahti to Uimaharju, is scheduled to start in summer 2019. The third stage will replace the Kontiolahti–Pamilo transmission line. A total of 112 kilometres of transmission lines will be replaced. A new substation will be built at Pamilo, and the Kontiolahti and Uimaharju substations will be updated. The entire project is due for completion in 2022.


Investment decisions

Developing the grid on the Oulujoki river

We are modernising the power grid around the river Oulujoki, which was built in the 1950s and is approaching the end of its service life. The grid upgrade will start with the modernisation of two substations and the expansion of one substation, and with the construction of new 400-kilovolt + 110-kilovolt transmission lines between Pyhänselkä and Nuojuakangas.

The grid development measures have been planned in close co-operation with our customers; more specifically, with the local electricity producers and regional distribution network companies. The local electricity production mainly consists of hydropower, while there are also new wind power projects to boost the existing wind power production. 

The upgrades will change the regional grid voltage from 220 to 110 kilovolts. Voltage compatibility with the rest of the grid will enable a simpler and, from a systemic point of view, more efficient grid structure. 

The Oulujoki grid will be modernised in stages. The first stage, to be completed in 2020–2022, will include the construction of the transmission line section between the Pyhänselkä substation in Muhos and the Nuojua substation in Vaala. The Pyhänselkä substation will be expanded, and the Nuojua and Utanen substations will be modernised during this stage. A new, approximately 45-kilometre-long transmission line will be built between Pyhänselkä and Nuojua, with most of this right-of-way situated west of the current transmission lines. This connection will be built in such a way that part of it can later be upgraded to the 400-kilovolt voltage level, when more transmission capacity is again needed between northern and southern Finland.

Modernisation of the historical Imatra substation respects landscape values

The first substation of Finland’s grid system, in the historical Imatrankoski rapids landscape, continues to be an important component of the transmission system in South Karelia. The substation serves the local hydropower plants and industries, and is the starting point of a cross-border transmission connection to Russia. The 110-kilovolt Imatra substation, originally completed in 1929, has been expanded and modernised over the years. Some foundations and other structures of the original station still remain.

The modernisation of the historical Imatra substation will be carried out with due respect for the historical, protected site. The original buildings of the Imatra hydropower plant, which have architectural-historical value and are protected by the municipal master plan, are located next to the substation. The project is due for completion in 2020.

Ongoing search for a transmission solution for Helsinki

In order to secure the Helsinki region’s electricity supply, we are pursuing a new type of operating model in which the City of Helsinki, the region’s distribution network company Helen Sähköverkko and Fingrid collaborate to carry out an infrastructure project that will serve the Helsinki region’s electricity supply and facilitate land use. In connection with this, Fingrid is preparing to build a new 400-kilovolt cable link from Länsisalmi to Viikinmäki, with plans to have it up and running as soon as the mid-2020s.

The parties have committed to drawing up a joint review of the transmission solution to prepare for the implementation of Helsinki master and city plans and Vihdintie boulevard and to enable a smooth planning process. According to tentative calculations, an overall cost-effective solution would be to build a new 400-kilovolt cable link from Länsisalmi to Viikinmäki, which would enable other solutions in the 110-kilovolt distribution network that promote more effective land use. In several cases the solution is an underground cable.

Based purely on electricity production and consumption predictions in Helsinki, the cable link would be needed by around 2035. However, Fingrid is ready to speed up the construction of the new 400-kilovolt grid cable link and the new substation if the City of Helsinki and Helen Sähköverkko participate in the costs that the project entails.

The common goal of the parties is to carry out the area’s electricity network projects in a way that is compatible with urban development projects during the 2020s. Alternative right-of-ways for the cable link were planned and an environmental impact study was carried out in 2018.


The three-year contracts on basic maintenance of substations and power lines and on basic and special maintenance of secondary equipment tendered by Fingrid in 2017 started on 1 January 2018.

The first year of the basic maintenance period included fault repair exercises to maintain fault repair capabilities both on transmission lines and substations. Some 40 people participated in the exercise on transmission lines and around 110 people participated in the substation exercise.

Top achiever in maintenance

Fingrid again scored excellent results in the International Transmission Operations & Maintenance Study (ITOMS), being the only TSO to achieve a Top Performer mention both in the substation and transmission line maintenance categories. ITOMS looks into the effectiveness of maintenance based on criteria such as maintenance costs and disturbance statistics. A total of 28 TSOs from all over the world participate in the comparison study. Fingrid achieved particularly good results in the inspections and maintenance of transmission lines and in the maintenance of switchgear and substation areas. 

Fingrid is in a class of its own in maintenance efficiency.

Developing occupational safety, digitalisation and smart systems are some of Fingrid’s strong focus areas. Digitalising grid substations is one of our strategic development programmes, aiming at a substantial increase in component status data and optimised investment and maintenance costs.

Occupational safety

One of Fingrid’s long-term goals is to improve the safety culture at work sites and in this way achieve its zero accident objective.

In 2018, Fingrid’s own personnel had no workplace accidents resulting in absence from work (2). A total of 4 (9) lost-time accidents were recorded among Fingrid’s service providers. None of the lost-time accidents resulted in an absence of more than 30 days. The suppliers’ and Fingrid’s combined accident frequency rate decreased significantly from the previous year, to 3.2 (8.5).

Results from Fingrid’s OHS development project:

  • Safer work practices
  • Production of training animations on additional worksite earthing and work at heights
  • Fingrid’s online training was updated and translated into five additional languages
  • Occupational safety training for personnel
  • Development of our mobile reporting system for occupational safety, quality and environmental issues was continued
  • Two issues of our occupational safety magazine “Safety on the lines” were published
  • Safety observation campaign and OHS seminar

Key events of 2018

A grid substation can be art – architecture awards for Fingrid’s Länsisalmi substation

Digital substation makes maintenance easier