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Case Study

ÅL-link

HVDC Light® technology secures power supply and grid reliability to Finnish archipelago.

Kraftnät Åland AB is responsible for electricity transmission in the Åland Islands, an autonomous Finnish province situated at the entrance of the Gulf of Bothnia in the Baltic Sea. Kraftnät awarded Hitachi Energy a contract to supply a turnkey, 100 MW  ±80 kV HVDC Light® transmission link to ensure security of the energy supply on the main island of Åland, where most of the population lives, and allow more renewables into the energy mix.

Åland presently receives 70 percent of its power via subsea AC cables from Sweden, in addition to some locally produced renewable generation. The existing fossil fuel powered back-up system will be closed once the new HVDC Light® link is in operation, saving CO2 emissions.

The HVDC Light® system incorporates special features such as active AC voltage support providing greater network stability and the unique ‘Black-start’ capability, which provides faster grid restoration in the event of a blackout.

With the ‘Black Start’ feature restoration time can be reduced to fractions of a second under operational conditions. This functionality when incorporated with Hitachi Energy's HVDC Light® technology, performs an intelligent and controlled injection of electricity into the grid to quickly re-energize the system. Even when the link is not in active operation, the black-start system can restore power in under five minutes - many times faster than in the absence of this feature. 

The ÅL-link is grid enabled, i.e. prepared for a multi-terminal configuration, which allows for additional in-feed from stations, such as future wind power plants.

Hitachi Energy delivered two converter stations, one situated in Ytterby, Åland and the other in Nådendal, Finland, and two 80 kV submarine cables, each 158 km long.

Main data
Commissioning year: 2015
Configuration: Symmetrical monopole
Power transmitted: 100 MW
Direct voltage: ±80 kV
Application: Interconnecting grids