TenneT’s 900 MW DolWin6 Goes Into Operation

Grid Connection

September 26, 2023, by Adnan Memija

The Dutch-German transmission system operator (TSO), TenneT, has commissioned the 900 MW DolWin6 offshore grid connection, bringing the transmission capacity in the German North Sea to 8,032 MW.

DolWin6, TenneT’s 13th German offshore grid connection, has now been officially handed over to the TSO for regular operation after several weeks of trial operation by Siemens Energy.

Siemens Energy supplied the entire technology for efficient direct current transmission for DolWin6, while Dragados Offshore was responsible for the construction and offshore installation of the associated platform, and Nexans supplied the direct current cables.

DolWin kappa offshore platform, which is the centerpiece of the 900 MW DolWin6, was installed at its offshore construction site in September last year.

The 11,000-tonne platform was placed on top of the 5,000-tonne foundation structure by Allseas’ Pioneering Spirit.

Combined, the two have a total height of 82 metres, so the platform rises 53 metres above the surface of the North Sea.

The platform will now convert alternating current generated by offshore wind farms into direct current, which will then be transmitted to Hilgenriedersiel on the mainland via an approximately 45-kilometre-long subsea cable.

From there, the electricity is transmitted to Emden/Has via an underground cable, which is also about 45 kilometres long. Here, a converter station and a transformer station convert the direct current back into three-phase alternating current and feed it into the high-voltage grid on land.

Apart from Germany, in the Dutch North Sea, TenneT has now realised 3,500 MW of connection capacity, bringing the total offshore capacity in both countries to more than 11,500 MW.

TenneT started preparing for what the TSO said was a ”large-scale” offshore tender to connect 40 GW of new offshore wind capacity in Germany and the Netherlands last year.

The TSO will build 20 GW in each of the German and Dutch sectors of the North Sea with its new 2 GW programme.

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“Wind energy generated far out at sea is the essential building block for the energy supply of the future. The North Sea countries of Germany, the Netherlands, Denmark and Belgium set ambitious targets in Esbjerg last year and agreed to expand offshore to 65 gigawatts by 2030,” said Tim Meyerjürgens, COO of TenneT.

“With 40 gigawatts, TenneT alone will transport almost two-thirds of this energy onshore. And the good news is: we are making great strides forward! With 11.5 gigawatts, we are already more than a quarter of the way there.”