Wind Turbines of CTC
Today’s utility scale wind turbine market is principally addressed by wind turbine designs that have evolved over the last thirty years. The conventional megawatt scale design incorporates a set of three fiberglass blades that have variable pitch to regulate power output and operate in a variable speed mode to maximize energy capture and to minimize loads arising from gusts. The blades are attached via a hub to a rotor shaft that turns at low rotational rates that change with the variation in wind speeds. The rotor shaft connects to a heavy-duty gearbox to increase the rotational speed to a level suitable to run an electrical generator.
The power generated by variable speed generators is typically produced at variable frequencies and, as such, requires modification by power conversion electronics in order to be able to synchronize with the steady frequency (either at 60 or 50 Hz) of an electrical grid. This is most commonly accomplished by partial power conversion using a DFIG, where only approximately 25% of the power needs to be converted, or sometimes by full power conversion, which has certain grid compliance advantages compared to a DFIG but comes at a higher cost.
The DeWind family of turbines has always been one of three-bladed, horizontal axis, upwind, pitch regulated, variable speed machines. In addition to its long history of supplying DFIG based turbines, DeWind developed an alternative which does not require power conversion electronics as it uses a synchronous generator with high voltage (13.8 kV) output which can be directly synchronized and connected to the grid. The current DeWind turbine products are the culmination of 15 years of research and development. Including an older D4 (600 kW) turbine class that is no longer produced, DeWind has 580 turbines installed worldwide (equivalent to 560 MW). The company currently markets three turbine models:
1.2.0 MW D8.2 turbine (60 Hz and 50Hz).
2.2.0 MW D8 (50 Hz).
3.1.25 MW D6 (50 Hz) – through a licensed manufacturer.
DeWind D8.2 turbine
The D8.2 series has a rated power output of 2.0 MW and is offered in both 50 Hz and 60 Hz versions. The turbine has a rotor diameter of 80 meters and is available with a hub height of 80 meters. The DeWind D8.2 eliminates the need for power conversion electronics and wind project dynamic VaR support units by using a synchronous generator. To eliminate the rotational energy variability, DeWind inserted a key turbine drive train innovation, the WinDrive®, a hydro-dynamic torque converter by Voith, to modulate the rotational energy. The grid-friendly synchronous electricity generator is of the type used by nearly all non-wind generation systems such as steam, gas and hydro driven turbines.