alt.energy.renewable

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.

You may have noticed that induction motors are
rated at something like 1725 RPM where synchronous
speed is 1800 RPM. The amount of output power from
these motors is proportional to how much the RPM
differs from synchronous speed.

Induction generators do the same thing except they
run at a speed higher than synchronous speed. More
input torque results in more induction speed.

OK, yes the speed does go up a bit with increase in
speed but not so much as one would notice.

Why use one type or the other.
1. The synchronous generator is generally a bit more
efficient. However, it is more difficult to
synchronize with the power grid before it is
connected to the grid. Synchronizing is easier in
a power plant as the input speed can be controlled
until just right. With wind turbines this speed is
harder to control just before connecting.

2. The induction generator is generally a bit less
efficient. But is much easier to connect to the
grid. Basically the speed only needs to be close to
connect to the grid.

I understand that they can provide some emergency
breaking torque which the synchronous generator
can't do.

> Load = power output.....

True.

> ??????

> Duane C. Johnson wrote:

> > Hi eezie;

> > eezie wrote:
> > > "Punjab The Sailor Man" wrote:

> > > If it's not going faster, how is it generating
> > > more power?

> > Increased torque with increased wind speed.
> > Power is speed, which is constant,
> > times torque, which increases with wind speed.

> > > > It can't go faster, it just generates more power.

> > Duane

Duane

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