Environmental Engineering Reference
In-Depth Information
Fig. 14.4 Aerodynamics: 3-blade and 6-blade rotor options
14.2.1.2 Mechanics: Main Structures, Power Train, Tower, Nacelle,
Gearboxes
The structure of the wind turbine is built around the pitch and yaw gearboxes. In
order to change the angle of attack of the wind on the blades a pitch-controlled full
sized wind turbine changes the pitch angle of the blades relative to the center of the
rotor. This is infeasible on a small scale, so in order to implement control of the
angle of attack in a comparable manner the actuators move the entire nacelle pitch
angle relative to the horizontal axis. The effect on the rotor speed is very strong, as
it is in a commercial wind turbine, so high precision is necessary, making a direct
drive method (motor directly connected to the pitch shaft) ineffective. Thus a
gearbox is implemented which gives the controller very high precision control of
the pitch angle of the nacelle with minimal backlash (see Fig.
14.5
). Then, the
