Energinet.dk Selects AC Connection for Kriegers Flak

Energinet.dk is preparing for the construction of a traditional grid connection system for the wind turbines at Kriegers Flak. This means that the system is based on AC like the systems connecting Denmark’s existing offshore wind farms with the electricity grid.

Originally, the grid connection should have been based on a DC system to be combined with an electrical connection to Germany via the Danish and German offshore wind farms in the Baltic Sea. However, this technical solution has been abandoned, as a call for tenders for the converter stations showed that especially the offshore converter station was far more expensive than estimated. Consequently, the electrical connection in the planned solution would not be economically profitable.

“To be able to complete our grid connection system by mid-2018, to which we are obligated, we are about to invite tenders for the large-scale components. At the same time, we continue our cooperation with our German partner, 50 Hertz Transmission, to develop a new technical solution for an electrical connection between Denmark and Germany which can be connected to the AC grid connection,” said Dorthe Vinther, Vice President, at Energinet.dk.

In 2012, the Danish Minister for Climate, Energy and Building ordered Energinet.dk to have the grid connection of the 600 MW offshore wind farm at Kriegers Flak ready by mid-July 2018.

Energinet.dk will now submit an application to the Danish Minister for Climate, Energy and Building for approval of the investment before Energinet.dk can start building the grid connection.

Besides, Energinet.dk will ask the Danish Nature Agency to start the EIA assessment of the new systems on dry land, as these are probably not included in the ongoing EIA assessment.

The grid connection has a budget of approximately DKK 3.5 billion.

The offshore grid connection system will consist of two 220 kV offshore trans-former platforms, which accumulate the electricity generated by the wind turbines in the 600 MW offshore wind farm. The two platforms are mutually connected by a submarine cable. An approximately 45 km long 220 kV submarine cable will be laid from each platform to the Zealand coast.

Two 220 kV land cables are laid on dry land. The two cables are connected sepa-rately to the existing substations. Finally, the grid connection also includes a new 400 kV cable, which is necessary to prevent overload of an existing 400 kV line when the offshore wind turbines at Kriegers Flak are put into operation.