An increasing number of wind market entrants and established wind turbine suppliers are focusing on designed direct drive wind turbines for onshore and/or offshore applications. One of the latest examples is leading German automotive production technology specialist supplier Schuler AG. The company is at an advanced development phase with a new in-house developed 2.7MW Schuler SDD 100 direct drive turbine.
A prototype featuring a 100-metre rotor diameter optimised for medium wind-speed inland site operation (calculated rated power at 11.5 m/s) is planned for erection this fall for a one-year test phase. After certification, Schuler plans to produce a pilot series comprising six wind turbines in 2011. Full-scale production is scheduled for 2013.
Trouble-free operation
The automotive industry is characterised by a high volume round-the-clock manufacturing process requiring uniform product quality and trouble-free operation. That in turn puts great emphasis at the use of highly reliable and very efficient production technology and methods.
Schuler claims the new SDD100 turbine is claimed to combine its in-house key skills in the fields of innovation, quality and engineering knowledge with those of dedicated "creative and high-performing partners". The IEC WC IIIA* (optional IIA) turbine among others features a 100-metre rotor diameter, electric individual pitch control and a custom-developed 3MW permanent magnet (PM) air-cooled generator.
This generator is a fully enclosed concept supplied by Finnish drive specialist The Switch and has been optimized to function with 2.7MW full-power converters (FPC). The 0.3MW capacity difference between the generator and converters is explained by internal system losses. ‘Fully enclosed' means that direct contact between the sensitive generator coils and magnets with the outside air is prevented, whereas cooling performance is enhanced by an air-air heat exchanger.
Diversification strategy
The development of complete wind turbines is part of the Schuler Group's long-term diversification strategy. Company board member Joachim Beyer in a press release earlier this year: "In order to tap additional business beyond the scope of the car industry and its suppliers, we began to systematically examine the wind power sector over three years ago."
One major outcome was that Schuler's in-house expertise with the construction of large-scale machinery matches wind power sector technology demands in many respects.
Beyer: "There are also signs that the prevailing wind technology is shifting toward low-maintenance, direct drive turbines. This combination of factors would enable us to transfer our know-how in the development of complex, electro-mechanical systems and high-torque drive systems one-to-one. Moreover, we are capable of producing turbines with pioneering technology offering greater efficiency and availability performance than most turbines currently available."
Schuler further plans at manufacturing its wind turbines initially for the German market only, but expand in the medium term to international markets as well. It can thereby benefit from a strong existing global presence including main wind markets in Europe, North America, and Asia.
*IEC IB/IIA and IEC IIIA are wind classes (I, II, and III) with each representing a maximum wind speed range (I = highest). A, B, and C represent maximum allowable turbulence levels (A = highest).
