After successful testing, grid operator TenneT and Siemens have now initiated the trial run of the BorWin2 direct current link.
After several weeks of trial operation, the grid link will be able to go into controlled operation in the first few months of 2015. With a transmission capacity of 800 megawatts (MW), the BorWin2 grid link can supply about 800,000 households with clean electricity.
In addition to the HelWin1 facility already undergoing testing, Siemens is currently preparing two additional high-voltage direct current (HVDC) transmission links in the North Sea for commercial operation for TenneT. Siemens received an order for a fifth direct current link in the spring of 2014.
Siemens installed the BorWin2 HVDC platform, located about 100 kilometers northwest of the North Sea island of Borkum, during the summer. Prysmian, a consortium partner and cable expert, was responsible for the installation of two 200-kilometer-long submarine cables. After successfully installing the platform, numerous commissioning tasks were necessary, at times requiring up to 100 employees to simultaneously work on the platform.
Following the connection of the Global Tech 1 wind farm, the BorWin2 link fed electricity into the grid for the first time in initial tests conducted in early September. Fifty percent of the grid connection’s capacity is planned for another wind farm. Since construction of the wind turbines has not yet begun, TenneT expects that the 800MW link will be used at only 50 percent capacity for the next two years.
Siemens will utilize HVDC technology, installed both on the offshore platform as well as in the land-based converter station in Diele, East Frisia, to efficiently bring the wind-generated electricity to land. The wind-generated power will first be transported as alternating current to the BorWin2 converter platform, converted there into direct current, and brought to land via submarine cables. The land-based station converts the direct current back into alternating current and feeds it into the high-voltage grid.
For lengths of 80 kilometers or more, HVDC is the only efficient transmission solution with a maximum loss of only 4 percent including the cable.
The HVDC Plus technology used by Siemens is less complex and particularly space-saving, which is absolutely necessary out at sea. In contrast to the classic HVDC technology which is widely used in land connections, systems with HVDC Plus feature self-stabilization. Because fluctuations can occur with wind-based power generation, the use of HVDC Plus technology from Siemens will significantly increase grid reliability.
In all, Siemens is now implementing five North Sea grid connection projects for TenneT. Projects to date are: HelWin1 (576 MW) and HelWin2 (690 MW) off of Helgoland, BorWin2 (800 MW) off of Borkum and SylWin1 (864 MW) off of Sylt. Siemens received the contract for the BorWin3 link in the spring of 2014; the four other grid link projects are in the advanced stages of completion and will successively go into operation between 2014 and 2015.
Press release; Image: Siemens