Siemens has completed installation of the BorWin2 offshore HVDC converter platform in the North Sea west of the island of Borkum.

Siemens said that the platform has 800MW transmission capacity and this marks Siemens’ achievement of the second key milestone in the German grid connection projects.

The project is part of the German offshore contract with TenneT.

Earlier, Siemens installed its first converter platform for the HelWin1 connection off Heligoland in the North Sea in August 2013.

At the new platform, the alternating current (AC) produced by the wind turbines is transformed into low-loss direct current for transmission to the mainland by using Siemens technology.

The BorWin2 onshore converter station, also supplied by Siemens, is located in Diele.

Thie onshore converter station will receive electric power from wind farms and convert it back into the AC required to feed into the power grid.

Siemens Power Transmission Division CEO Karlheinz Springer said, "Once more we have mastered the challenging offshore installation part. We are now in the final stretch to achieve commissioning in the first half of 2015, as promised. When the two platforms yet installed by us go on line, they will be able to supply more than 1.3 million households."

TenneT has awarded the contract for the BorWin2 offshore grid connection with a consortium comprising Siemens and the Italy-based Prysmian in 2012.

"The project is part of the German offshore contract with TenneT."

In total, Siemens is setting up five North Sea grid link-ups for Tennet: HelWin1, HelWin2, BorWin2, BorWin3 and SylWin1.

Siemens along with Petrofac has secured the order for the BorWin3 grid connection in the North Sea.

It is scheduled to be operational in 2019.

Once commissioned, the grid connections set up by Siemens will have a total transmission capacity of more than 3.8GW.

Siemens is using HVDC Plus converter technology and is essentially a voltage-sourced converter of the modular multi-level converter type (VSC MMC).

BorWin2 is designed for decades of operation in the rugged North Sea. The platform is installed 20m above sea level in order to protect it against giant waves, the platform.

Image: Siemens installed the offshore platform for the BorWin2 grid connection at sea in April 2014.Photo: courtesy of Siemens.