Image credit: Lepti
Whether a wind turbine is a horizontal axis or vertical axis turbine, it will have four main components: a foundation, tower, nacelle and rotor. Some components, like the foundation are relatively simple, while others, like the nacelle contain high tech instruments, but they are all critical to ensure that the system operates safely and at peak efficiency.
FoundationIn most cases, wind turbines are mounted to a concrete foundation on the ground. Other types of installations can include off-shore turbines which are connected to concrete foundations embedded in the ocean floor and smaller turbines which can be attached to rooftops.
TowerThe purpose of the tower is simple - to raise the nacelle and blades above the ground to a height where the wind speed is greater. Typical wind turbines are 150-300 feet above the ground.
NacelleThe nacelle, also referred to as the turbine housing, sits at the top of the tower and contains the majority of a wind turbine's components.
- Low speed shaft - Transfers the rotational energy from the rotor to the gearbox.
- High speed shaft - Drives the electrical generator.
- Brake - Prevents the blades from rotating for performing repairs or to prevent damage from high winds (typically 50 mph or greater).
- Gearbox - By reducing the torque, the gearbox increases the rotation speed of the low speed shaft (from the blades) to the high speed shaft (of the generator).
- Generator - Converts the mechanical/rotational energy into electrical energy.
- Transformer - Converts the electricity from the generator to the correct voltage needed for the power grid.
- Electrical control system
- Anemometer - Measures wind speed, which is critical to determining when to engage the brake to shutdown the turbine during heavy winds which could damage the turbine.
- Wind Vane - For small wind turbines, the wind vane aligns the turbine in the direction of the wind. Large turbines generally use a computerized wind sensor with a yaw motor to control the direction of the turbine.
RotorThe rotor is often considered the most important component of a wind turbine as this is where wind energy is converted into mechanical energy. The rotor is attached to the front of the nacelle and is the hub where the blades are attached. The size of the rotor and size of the blades are critical in determining how much power the wind turbine can generate. Also a factor is that in order to extract the maximum amount of power, the rotor needs to turn faster as the number of blades go down. The tip speed ratio helps to determine the optimum speed of the turbine so that the maximum amount of power is captured.
The swept area of the blades is the circular area of space that the blades spin through. The larger the swept area of the blades, the higher the power output becomes. The size of the swept area is increased by increasing the length of the blades.
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