The 500 MW ±400 kV Fenno-Skan 1 & 2 HVDC links are owned by Fingrid Oyi and Svenska Kraftnät, transmission system operators in Finland and Sweden. Fenno-Skan 1 was commissioned in 1989; the Fenno-Skan 2 link became operational in Dec. 2011, increasing capacity by another 800 MW. The addition of Fenno-Skan 2 helps to strengthen the Nordic power grid, enhance the capacity for power trading and improve the security of power supplies in the region.
In parallel with the delivery of Fenno-Skan 2, the control system of the original Fenno-Skan link was upgraded to a fully digital MACH2 system. Fenno-Skan 1 was originally built as a 233-km long monopolar link using sea return for the current, but will now become a bipole. The stations were built to eventually accommodate a second pole.
The 200-km long undersea cable reaches Finland south of the town of Rauma. A 33-km long overhead line connects it with the Rauma converter station. Dannebo, the Swedish converter station for Fenno-Skan 1, is near the Forsmark nuclear power station on Sweden's east coast. The DC cable comes into the converter station area, since the station is only about 1 km from the coast.
For Fenno-Skan 2, due to AC grid constraints, the Swedish converter station is located further inland - at Finnböle, and a 70-km long overhead DC line will connect it to the submarine cable. The cable will be connected to the Finnish transmission grid at the Rauma substation.
Fenno-Skan reduces the electrical distance between major generation and load areas in Finland and Sweden from 1,500 km to 200 km.