GOLD Siemens SWT-6.0-154
Now market ready, Siemens commissioned a 6MW direct-drive turbine prototype with 120-metre rotor diameter in 2011. Another prototype followed in 2012, with a rotor diameter of 154 metres. In 2013 two offshore prototypes with the shorter blades were installed in the UK, and a "market-ready" unit with the longer blades at a high-wind onshore test site in Scotland.
The cylindrical-shaped 6MW nacelle looks like a bigger version of Siemens' SWT-3.0-101, the main difference being the helicopter-hoisting platform to the rear of the nacelle. The water-cooled PMG is based on previous designs but with a larger 6.5-metre diameter.
Inside the nacelle a huge cast main carrier forms the central structural element, and to the front there is a remarkably easy internal service hub access via the hollow generator shaft and single rotor bearing inner ring.Two individual power-electronic converters are located inside the nacelle with a medium-voltage transformer.
The first prototype used SWT-3.6-120 rotor blades and hub, but for the SWT-6.0-154 Siemens developed longer 75-metre blades.
Despite the incorporation of converters and transformer in the nacelle, the SWT-6.0-154's head weighs only 360 tonnes, already considered an industry benchmark. Systematic testing and validation, together with an already healthy-looking order book, suggests the SWT-6.0-154 is set to become a worthy successor to Siemens' current offshore turbines.
SILVER Alstom Haliade 150-6MW
The direct-drive Haliade 150-6MW has a 150.8-metre rotor diameter, and the drivetrain comprises a stationary hollow main shaft, a rotor hub with two bearings, and a 7.5-metre medium-voltage air-water cooled inner-rotor PMG. A clever and novel design solution is that the generator rotor part has its own bearing and is connected to the hub via flexible couplings. This Alstom pure torque principle enables full separation between rotor-bending moments, led directly into the support structure, and "pure" rotor torque fed into the generator without constraining the generator air gap.
The slender 73.5-metre GloBlade was developed with LM Wind Power. The power electronic converter and transformer are located in the tower foot to reduce head mass. A prototype was installed in early 2012, an offshore prototype in late 2013 with series production planned in 2014.
BRONZE Gamesa G128-5.0MW
This is the third medal for the Spanish firm that initially started making Vestas-type turbines, and gradually developed them in-house. The G128-4.5MW was the first major full turbine developmenet project for the company.
Gamesa's G128-5.0MW is developed from 2009's G128-4.5MW. Both models feature a tube-shaped CompacTrain drivetrain comprising a main shaft assembly flanged to a two-stage planetary gearbox and PMG drivetrain, pioneered with German engineering group ZF. It is claimed to enhance reliability by removing high-speed mechanical rotating components.
The 4.5MW onshore unit has segmented composite blades, but the 5MW versions for onshore and offshore use have single-piece blades. New is a G132-5.0MW onshore unit with 132-metre rotor and single-piece blades.
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