Monday, March 3, 2008

Wind Energy Update

By Wyatt


Wind energy has been used for centuries by converting it into mechanical energy move boats, in mills for grain transformation, or to pump water. Nowadays, technology allows us to use wind energy more efficiently. Wind mills allow us to produce electricity using a generator coupled to blades.
The first commercial applications date from the 1980’s with turbines of typically 50kW and rotors with diameter of 12 meters. Currently, manufacturers are able to provide turbines with a capacity of 5MW and above, with rotors that can go up to 130 meters.
Here are three types of wind turbines:
• squirrel-cage induction generator with a gear box increasing the number of revolutions from the shaft to the desired number in the generator - only available for less then 1.5 MW because of resonance problems
• double-feed (wound rotor) induction generator with a gear box increasing the number of revolutions from the shaft to the desired number in the generator. Includes a converter that injects a current with variable frequency into the rotor windings of the generator to decouple electrical and mechanical frequencies
• direct drive synchronous generator with a directive drive (possible with variable speed) and generator and grid fully decoupled through power electronics.

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