Know Your Wind Turbine (part 2)

The part 1 of this article introduced you to four of the important components of the wind turbine. These are the heavy weights that make up the rest.

• Gear box
Gears connect the low-speed shaft of the turbine hub to the high-speed shaft of the generator and increase the rotational speed from about 30 to 60 rpm to about 1000 to 1800 rpm, the conventional speed requirement of an alternator. It also constitutes a major cost component of a wind turbine and imposes a heavy weight on the whole structure as well. Currently researches are on for “direct-drive” generators that operate at lower rotational speeds and exclude the gear box.

• Generator (of electrical power)

This is really an alternator of commercial variety that generate standard power supply of 230v/50z/1 ph or 415v/50hz/3ph. (This may vary according to the country of usage for eg. USA)

• High-speed shaft
This interfaces the rotational speed of the turbine blades (available on the low speed shaft) to the alternator through the gear coupling. In reality this is also the extension of the alternator rotor shaft.

• Low-speed shaft
This serves as the means to transmit the turbine blade generated mechanical power to the gear box at about 30 to 60 rpm.

• Nacelle (enclosure)
The nacelle is the enclosure of the gear box, low- and high-speed shafts, generator, controller, and brake. These are generally huge and are very sturdy to with stand all the rigors of extreme elements while being capable of bearing the load of the turbine components.

• Pitch:
The device to turn, or pitch the blades out of the wind in order to control the rotor speed and prevent the rotor from turning in extreme winds that are too high (or too low) .

• Rotor
The blades and the hub together constitute the rotor and can be made of Fibre Glass or metal. Present day designs can generally withstand the stresses if the rotor runs out of control in extreme weather.

• Tower:

These are commonly available in two basic designs. viz. as Guy wire or Free standing and Lattice type. The most familiar one is the former while the latter is more suited for industrial and low wind speed applications. Towers may be constructed of steel tubulars, steel lattice or concrete. The taller the tower the better it will be to trap the wind’s kinetic energy.

• Wind vane:
Wind vane measures wind direction and signals the yaw drive to align the turbine properly to the wind. Also its feedback may be useful for brake operation and pitch control.

• Yaw drive:
In horizontal axis design the upwind turbines face into the wind and the yaw drive is used to keep the rotor facing into the wind as the wind direction changes. If there is a “yaw error” the full wind power will not be available to the rotors and thus less electricity will be produced. Thankfully the downwind turbines don’t require a yaw drive because the wind will blow the rotor downwind.

• Yaw motor:
This powers the yaw drive depending on the wind vane feedback..

Now you know what you can find inside the gigantic nacelle and the roles the innards play. The wind turbine is one of the most reliable and environmentally friendly power generators and is ideally suited for Ireland, especially so in the western coastal areas. Think of it! You would be totally above the high handed acts of the global energy merchants! I am sure you would appreciate that as much as the (drastically) reduced energy bills.

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