Bob Ammerman wrote:
>
> > I have always been curious whether in a big country with a unified grid
> > centralized timing signalling is used to sync the plants ? Because I think
> > that it is very hard to do it otherwise (plants syncing to what they
> > 'see' on the outgoing lines) on a grid with significant time lags.
>
> Syncronization to the grid is actually pretty easy. You just have to get
> away from the thinking of 'outgoing' lines.
>
> When a plant first comes online, it brings its generator up to speed, and
> then waits until it is in phase with the voltage seen on the 'outgoing' line
> (which, since the big generator circuit breaker is open, at this point is
> just a reference signal). When everything is reasonable (ie: generator
> frequency is very close to line frequency, generator voltage is pretty close
> to line voltage and generator phase is close to line phase) the generator
> breaker is then closed to connect the unit to the grid.
>
> Once the breaker is closed in, there is no way the generator can get out of
> phase/frequency lock with the grid.


Takes me back! When I was an apprentice we did some labs on grid-sync,
the ancient system of three light bulbs from our phases to their phases.
As you bring your MG up to sync the lights flash in a circle, getting
slower and slower until they are in phase, then you flip the switch.
Like something out of a 50's horror movie to see it done. :o)

I have noticed that the wind turbine power generators have gotten
smaller for the grid-synched ones now. When the wind blows stronger
than x mph the wind turbine propeller gets close to the right speed,
then a microporcessor "clicks" the relay and connects it to the grid
when it hits the exact speed and phase angle. Pretty cool. Beats having
dc batteries and inverters before you can sell your power. I want a few
of them in my backyard, and a backyard big enough to put them in! :o)
-Roman

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