Re: power-grid physics

[James Frysinger <frysingerj@COFC.EDU>]

On Wednesday 2003 August 20 22:18, you wrote:
....
> As the load shifts - so shifts the phase of the two generating plants.
>
> The phase shift determines which generator is selling power to the
> other and which is buying. i.e. a phase shift creates a power shift
> in the grid.
>
> Does this make sense??

        Yep, the "slow" one is "buying power". If there are only the two generators
and the wires connecting them, then the "slow generator" is actually a motor.
But in reality, grid sectors are linked with a lot of load between the links
and the generators. So the "slow sector" is buying power. That means that the
sector's own generators and the "foreign" generator are sharing its load. If
a sector is "fast" then it is "selling" power to the linked system.

        In reality, and for the moment ignoring the distance-time-phase effects of
very long wires, all the generators are running at the same frequency. They
have to; they have synchronous windings, not inductive windings. When we talk
about "slow" and "fast" with respect to generators, we are actually talking
about the "no load" settings.

Jim

> He also described the 'small' local generating station going
> 'off-grid' at a particular time during the night so that the
> generator speed could be adjusted to guarantee exactly 60 Hz averaged
> over the entire day. (they counted cycles!)
>
> He also had some of the absolutely BEST practical jokes, as a kid,
> directed against the phone company. He now works for AT&T.
> --
> I never teach my pupils; I only attempt  to provide the conditions in
> which they can learn.
>   - Albert Einstein

--
James R. Frysinger
Lifetime Certified Advanced Metrication Specialist
Senior Member, IEEE

http://www.cofc.edu/~frysingj
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j.frysinger@ieee.org

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