The direct drive onshore wind turbine has a rotor diameter of 101 meters. Siemens will thoroughly test and validate the performance of the SWT-3.0-101 wind turbine before the new product will be officially launched for sale in 2010.

“Compared to a standard wind turbine with gearboxes we managed to reduce the number of parts in the new SWT -3.0-101 DD by half”, says Henrik Stiesdal, CTO of the Siemens Wind Power Business Unit. “With fewer moving parts, the direct drive technology has the potential to significantly reduce maintenance time, which could result in even higher turbine availability.”

The SWT-3.0-101 DD direct drive wind turbine features a new, compact synchronous generator excited by permanent magnets. The generator was produced by the Large Drives Business Unit within the Siemens Industry Sector. The main advantage of permanent magnet generators is their simple and robust design that requires no excitation power, slip rings or excitation control systems. This leads to high efficiency even at low load, Siemens says.

“One and a half years after starting the testing of two direct-drive concept wind turbines we are now confident that this technology is a sound base for future Siemens wind turbines”, says Stiesdal.

In July 2008, Siemens installed the first of two 3.6 MW direct drive concept wind turbines. The purpose was to assess whether direct drive technology is competitive with geared machines.

Stiesdal says: “We can now conclude that the concept machines are operating with an excellent performance and that we are ready to move ahead with developing the concept into a commercially competitive product.”

“We will continue to develop new wind turbines based on the standard gearbox design as these machines have proven to be exceptionally robust and reliable.

“And like in the past we will pursue a careful product introduction strategy also with our new direct drive wind turbines, because rushing to the market with immature technology is not an option for Siemens.”