alt.energy.renewable

"Duane C. Johnson" wrote in message
news:46da1681$0$17210$39cecf19@ ...
> Hi eezie;
>
> eezie wrote:
>
> > Soooo.....
>
> > With more wind, add load to keep the speed constant....
>
> Essentially true.
> However, one doesn't have to actively adjust the load.
> It just happens because of the nature of this type
> of AC generator.
>
> There are two basic types of AC windmill generators.
> 1. Synchronous Generator. This type operates at
> synchronous speed. The amount of power these
> generators produce is defined by the magnitude
> of the phase leading the grid. The more torque
> the turbine inputs the greater the phase leads.
>
> 2. Induction Generator. This type operates essentially
> the same way as conventional AC induction motors we
> are so familiar with. The speed is usually a bit
> different from synchronous speed.
>

Actually, there is a third category that is gaining use in large units.
/wiki/Doubly-fed_electric_machine

The wound-rotor design allows the shaft speed to vary with wind speed and
still maintain a constant frequency output. By recovering the power induced
into the rotor (that would otherwise be lost in a simple induction
generator), the efficiency approaches that of the synchronous units and
remains easy to sync to the grid.

daestrom