ABB, the leading power and automation technology group, has won an order from the Dutch-German transmission system operator, TenneT to provide maintenance services for the DolWin2 link bringing power from offshore wind farms, located in the North Sea, to the mainland German grid.

This contract follows ABB’s success earlier this year when it won an order worth around $1 billion to supply the power link itself, which was the biggest power transmission order in ABB's history. DolWin2 will deploy the world’s largest offshore HVDC (high-voltage direct current) system with a rating of over 900 megawatts (MW), keeping electrical losses to less than 1 percent per converter station. The completed link will be capable of supplying more than 1.5 million households with clean wind-generated electricity.

“Service and maintenance are key elements in the efficient and reliable operation of these advanced offshore renewable energy transmission links and we are pleased to support TenneT with our technical expertise and competence in this area,” said Peter Leupp, head of ABB’s Power Systems division. “This also reinforces our growing focus on service as a key business driver.”

As part of the maintenance contract, ABB will keep up the land- and sea-based HVDC converter stations connecting the wind farms via an offshore platform to the grid. The three-year contract for an undisclosed sum has extension options. The order was booked in the third quarter.

DolWin2 will have onshore and offshore HVDC converter stations and 135 kilometers of underwater and underground DC cables. With a rated voltage of 320 kilovolts (kV), the link will have the highest voltage level of extruded cable ever used for HVDC transmission. Scheduled to be operational in 2015, DolWin2 links the 400 MW Gode Wind II wind farm and other offshore wind farms to the grid. It will avoid more than three million tons of carbon dioxide emissions per year in support of Germany’s ambitious renewable energy plans to replace its fossil-fuel-based generation.

DolWin2 is the third offshore wind connection order for ABB in Germany, following the 800 MW DolWin1 link awarded last year and the earlier BorWin1 project. ABB was previously entrusted by TenneT to provide maintenance services for the BorWin1 and DolWin1 offshore wind farm transmission connections.