The Prysmian Group, Italian cable specialist, and Siemens have now completed and delivered the BorWin2 and HelWin1 projects to TenneT in the North Sea. Commercial operations have since commenced at the project. TenneT contracted the consortium for the HelWin1 offshore grid connection in 2010.
BorWin2 and HelWin1 are high voltage direct current (HVDC) offshore grid connection projects off the coast of Germany.
BorWin2 now links the Global Tech 1 offshore wind farm in the North Sea to mainland Germany and has the same grid connection capacity available for further offshore wind farm connections.
In our webinar, TenneT's strategy to address European congestion issues, TenneT discusses its plans for connecting new offshore wind in Germany via HVDC to their old German grid.
Commercial offshore grid connection
This project is the first large-category offshore grid connection worldwide to take up commercial operation with HVDC technology, employing an extruded cable connection along a 200km route (125km offshore and 75km onshore) with the highest power transmission capacity (800MW) and the highest DC voltage level (± 300kV DC) worldwide, a record previously also held by Prysmian with the ±200kV DC Transbay Project in San Francisco, California.
HelWin1 is the second HVDC grid connection to be handed over to TenneT in the first weeks of this year and links the offshore wind farms Nord See Ost and MeerWind to mainland Germany with a ± 250kV DC, 576 MW cable connection along a total route of 130km (85km submarine and 45km land).
Both BorWin2 and HelWin1 use extruded HVDC cable technology from Prysmian together with Siemens HVDC Plus converter technology at the offshore platform and onshore stations. Prysmian Group has also installed the multiple 155kV HVAC submarine cables which connect the converter platforms to the respective individual offshore wind farm transformer platforms.
Connecting the North Sea grid
Siemens is now implementing three additional North Sea grid connection projects for TenneT:
HelWin2 (690 MW) off of Helgoland
BorWin3 (900 MW) off of Borkum
SylWin1 (864 MW) off of Sylt
The next two grid connections, Sylwin1 and HelWin2, are scheduled to take up commercial operation in the first half of 2015.
Siemens received its latest order for a grid connection in the North Sea, BorWin3, in a consortium with Petrofac in the spring of 2014. Commissioning of this fifth grid connection from Siemens is scheduled for 2019.
The grid connections implemented by Siemens for TenneT will have a total transmission capacity of theoretically more than 3.8GW, providing electricity from offshore wind power to supply around 5 million households.
Germany’s offshore wind capacity doubles
Germany's offshore wind capacity more than doubled in 2014. At the end of last year, total installed offshore wind capacity stood at 2.35GW, compared with 915MW at the end of 2013, according to German engineering association VDMA.[Engerati- Germany’s Offshore Wind On The Increase.]
Of the 2.35GW, about 1.05GW is connected to the grid, highlighting the need to speed up network connections to reach Germany's goal of having 6.5 GW of capacity installed and connected by 2020.
"At the end of 2015 we will have about 3GW of capacity connected to the grid, which equals an investment of about 10 billion euros (US$11.7 billion) in the German offshore wind industry," says Norbert Giese of VDMA.
Overall, 543 offshore wind turbines have been installed off Germany's coast so far.
Unlike onshore farms, offshore parks face no limit on turbine size, while steady sea winds allow them to turn about 42% of the time- this is about double the effectiveness of onshore wind.
However, currently offshore wind accounts for less than 1% of Europe's power consumption. The technology’s growth in adoption is hampered by high costs and limited evidence on long-term impact from storms, states the VDMA.