TenneT starts the new year with a major progress in its transmission capacity extension project. The BorWin2 offshore grid connection system of transmission system operator TenneT was completed on 28 January 2015 and is now available for the infeed of offshore wind power. The connection is capable of transmitting 800 megawatts (MW) of offshore wind power from the German North Sea to the coast, where the offshore wind power is fed into the transmission grid. "BorWin2 provides a crucial contribution to the energy transition", said Lex Hartman, Member of the Management Board of TenneT TSO GmbH. "The capacity of 800 megawatts corresponds to an output that is sufficient to supply around one million private households in Germany."
TenneT thus completes a milestone with regards to the offshore extension plans of the Federal Government, as, with BorWin2, four grid connections with a total capacity of some 1,400 MW have been completed. Another eight grid connection systems are under construction. Two of these will equally be completed in the coming weeks and months. An invitation to tender has been issued for another system. Overall, TenneT expects that 7,100 megawatts of connection capacity will be constructed in the North Sea by 2019. TenneT is therefore fulfilling the expansion targets of the Federal Government, of 6,500 megawatts by 2020, in good time.
BorWin2 is the first of four offshore grid connection systems in this capacity class, which will be completed in the coming weeks and months. In addition, this is the first system enabling the connection of more than one offshore wind farm. The extension of the grid connections for offshore wind farms will see another major progress with the completion of the HelWin1 and SylWin1 grid connection systems.
A test operation of several weeks preceded the completion. Wind power from the Global Tech I wind farm could already be fed into the grid during this phase. Furthermore, fifty percent of the grid connection capacity are reserved for the Veja Mate wind farm.
BorWin2 also marks the completion of a direct current grid connection with a length of 200 km for offshore wind farms. A consortium consisting of Siemens and Prysmian as contractors of TenneT had already finished the construction of offshore and onshore converter stations in summer 2014. BorWin2 is a joint investment project of TenneT and Mitsubishi Corporation. In this context, the two project partners who have been working together on three other projects in the field of offshore grid connections will continue their close cooperation.
The offshore wind power is transmitted as three-phase electric power to a converter plat-form (BorWin beta in this case) operated by TenneT, converted to direct current and transmitted to an onshore converter station via direct current cable. The converter station for BorWin2 was erected in Diele, Rheiderland, Lower-Saxony. Here, the DC power is converted back to three-phase electric power and fed into the extra high-voltage grid.