"Michael A. Terrell" wrote in message
...


daestrom wrote:

You seem to be laboring under the idea that all the AC generators tied to
the grid have to be carefully regulated to stay in sync with each other
through some incredibly precise timing.


I never said that at all, but I did say that the sped and phase have
to match to connect a new generator to a grid.


That isn't the case. A generator is brought on-line by carefully
regulating
the speed and getting it in phase. That is a bit tricky. But once tied
to
the grid, 'keeping in sync' is done by the load current and physics. In
fact, base load units don't even have frequency control once on-line.
The
speed set-point for the governor is run several hz up out of the way and
the
turbine controls are controlled by a 'load' setting. The operator dials
in
the amount of MW load they are supposed to carry, and the controls
monitor
MW and steam flow. They don't respond at all to frequency changes unless
the frequency rises to the point the unit is in danger of over-speeding.


If you would have read the entire thread, I described how the
generators are synched, and that the grid keeps them in sync unless
something goes wrong. I also stated that the generator was fed more
fuel or water to actually produce power for the grid rather than just
coasting along, in phase, one it was connected to the grid. I studied
the subject with college textbooks on power generation and distribution
when I was 13.


Then why do you keep repeating....

"generators are connected via AC than DC and those DO have to be in phase
and have the frequency controlled to keep the rest of the grid happy."

And similar phrases about AC generators needing extremely accurate frequency
control. As I pointed out, most generators on the grid are *not* frequency
regulating. Once tied in, they just follow the grid frequency. Base load
units are a prime example of this. The governors are run up out of the way
so they are not controlling the turbine at all once connected.

snip

Of course the larger the spinning mass in the generator, the more the
inertia, and the less likely to be kicked out of phase. The
experimental nuclear power plant at Ft. Greely, Alaska was steam driven
and unable to adapt to rapid load changes so they blew out quite a few
bearings in the turbines before they finally gave up and shut it down.
They would barely get it running an synchronized to the Alaskan power
grid when someone would fire up another generator and switch it on line
without contacting other providers on the grid. The system was
unstable, in frequency, voltage and a lot of outages. I watched my 120
VAC feed climb to over 190 volts one day, as circuit breakers all over
the complex were tripping out. It took me a couple hours to get all the
studio equipment and transmitters back in service that day. It was one
of the few times that I was happy that the towers were too short to need
lights.


Not familiary with Ft Greely, but I would guess that such a system was not
really part of a large grid. Sounds more like a small number of units with
a relatively small amount of load ( 500 MW???). Yes, controlling such a
setup does require more coordination. Especially since one unit can make a
rapid change to the system's frequency.

daestrom