Rauma substation modernisation strengthens the reliability of Finland’s transmission grid
The Rauma Substation is one of the most important substations in Finland in terms of power system reliability. Due to the ageing of the existing facilities, a major modernisation programme was launched in 2022 to ensure the long-term reliability of both the substation and Finland’s national transmission grid. As part of the project, we constructed a new gas-insulated switchgear (GIS) building, replacing the existing outdoor 110 kV air-insulated substation.
The project included the construction of a two-storey, approximately 800 m² GIS building adjacent to the existing substation. The lower floor was cast in situ, while the upper floor was built using prefabricated concrete elements.
As part of the same contract, we also constructed a new 300 m² control building. In addition to the building works, we delivered all electrical and building services installations, including HVAC, plumbing and automation systems, for both buildings.
“The transmission connections from Rauma Substation provide up to 1,200 MW of cross-border electricity transfer capacity between Finland and Sweden. The substation also plays a critical role in the operation of the Olkiluoto nuclear power plant. Modernising the substation is therefore a highly important project that requires careful planning and precise execution to ensure that the work does not interfere with the normal operation of the electricity system,” says Jarmo Henttinen, Project Manager at Fingrid.
Both buildings were handed over to the client in autumn 2023 to enable the installation and commissioning of the switchgear. Following this phase, we will demolish the existing control building during summer and early autumn 2025 and complete the remaining civil works on the site, including a stormwater detention basin, associated drainage systems and inspection chambers. The entire project is scheduled for completion in autumn 2025.