Wind availability factor and turbine components

Major factor determining availability of wind power

Wind speed is the major factor, because wind power is proportional to the cube of wind speed (P = ½ ρ A v³). A small increase in speed gives a large increase in power. Other factors are air density, swept area, height and the terrain.

Major components of a wind turbine

1. Rotor blades: capture wind energy; made of fibreglass or carbon fibre (usually 2 or 3 blades).
2. Hub: connects blades to the main shaft; may include a pitch mechanism.
3. Nacelle: housing on top of the tower that contains the gearbox, generator and controller.
4. Low-speed shaft, gearbox and high-speed shaft: gearbox raises 15–30 rpm up to 1000–1800 rpm for the generator.
5. Generator: converts mechanical energy into electricity (induction, synchronous or permanent magnet).
6. Controller, anemometer and wind vane: measure wind speed and direction and start or stop the turbine.
7. Yaw drive: turns the nacelle to face the wind.
8. Brake: stops the rotor for maintenance and in strong wind.
9. Tower and foundation: support the rotor at height (60–120 m for large turbines).
10. Transformer and power cables.

     \ | /   rotor + hub
  [ gearbox | generator ]  nacelle
        ||
        ||  tower
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