Large wind turbines turn an induction motor (large three phase squirrel 
cage motor - through suitable gearing).  The turbine can be brought up 
to speed from the grid or from wind.  Power in or out is determined by 
the slip frequency (if you are running behind the grid, you are drawing 
power and if you are ahead of the grid you are supplying power).  This 
can be regulated by controlling blade tilt. 

Dave

Mark Scoville wrote:

>>There's a large wind-turbine "farm" going up on the Gippsland
>>coast here in
>>Victoria. The wind doesn't blow all the time (duh!) and when it does the
>>turbine blades (3-bladed model in this case) can rotate at any
>>speed from dead
>>slow to damn fast. The power grid they contribute to is 3-phase,
>>415V, 50Hz in
>>Australia. So how to they synchronise the turbines' output to the required
>>frequency and phase? Just curious.
>>
>>Thanks - Debbie
>>
>>    
>>
>
>Hmmm. Good question. Maybe they rectify to DC (If they aren't generating DC)
>and then have an inverter to output AC to the grid. Just a guess though -
>don't really know. Hope somebody else knows for sure.
>
>-- Mark
>
>
>
>  
>


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