Siemens and Prysmian win €500m Nordsee-Ost wind farm contract

A consortium made up of engineering giant Siemens and cable manufacturer Prysmian has won a €500m ($649.3) order to connect RWE’s Nordsee-Ost offshore wind farm to the German national grid.

The consortium will undertake the work for transmission system operator Transpower, a subsidiary of the Dutch grid operator TenneT.

The wind farm will be connected via submarine cables using high-voltage direct current (HVDC) transmission technology.

The Nordsee-Ost wind farm is located about 85km offshore to the north-west of the island of Helgoland. The grid connection will have a transmission capacity of up to 576MW.

Siemens will be supplying a Voltage Sourced Converter (VSC) system using itsHVDC Plus technology to transport the wind-generated power to the mainland.

Siemens says the converter will be set up on an offshore platform, on which alternating current (AC) voltage of 155 kilovolts (kV) will be transformed to 250 kV and then converted into direct current (DC) at the same voltage level.

The platform will carry the entire equipment package required for the HVDC converter, essentially comprising the converter itself, two transformers, and the gas-insulated, high-voltage switchgear.

The wind-power offshore substation (WIPOS) supplied by Siemens will be delivered on a floating, self-erecting platform.

Wind power will be transmitted by submarine and land cable to Büttel, north-west of Hamburg, where it will be converted back from DC to AC in a station on the mainland for further transmission and distribution.

Structural design and engineering work on the project, known as HelWin1, is due to be completed by the middle of 2011.

The onshore station will be constructed in 2011, while installation of the offshore platform is scheduled for mid-2012. Laying of the cables is planned to start in spring 2011, and the entire grid connection is scheduled to be up and running by 2013.

Udo Niehage, chief executive of the power transmission division within the energy sector at Siemens, says the company has received a total of 4.6GW in orders for connecting up offshore wind farms so far.