how do power company regulate output power and frequency?

[peter]

I studied electrical engineering in school but was never taught this topic:

How does a hydro/coal electrical generation plant regulate the power output
and frequency?

Let's say it needs to increase frequency by 0.1Hz, does it burn more coal or
allow more water through to make the generator to spin faster?

What about the other way around. At peak hours when it needs to produce more
current, does it make the generator spin faster? But that would increase the
frequency as well. Or maybe it adds more generators in parallel, which I
assume are mechanically linked to the other generators so they all generate
the same voltage and frequency.

[Windad]

Well, it has been a long time since I was involved, but "in the old days"
the big coal and nuke plants did not closely vary their output in response
to load changes. Instead, smaller oil or natural gas, and occasionally
hydro plants would vary their output to create a load match on a system
basis. The big plants would come on as "blocks". The reason for this
approach was that the big nuke & coal plants were difficult to modulate on a
real time basis, while the smaller liquid & gas tirbines could be ramped up
or down quickly. So for example, on a day when it is steadily getting
hotter and load is growing, gas or oil turbines would spin up, and as the
big plants came online, the gas or oil turbines would be throttled back, and
then throttled up again as load continued to grow.

With the higher prices of oil and gas, progress has been made in getting the
big coal plants to be more load responsive. But very efficient combined
cycle gas generation probably still makes them a great choice for load
following.

So the answer to your question is "burn more fuel". However, everything is
done on a system-wide basis. So it might be a generator far away that picks
up the load, not necessarily the one next door. And just to make things
interesting for you, the dispatch of electricity is also done on a market
basis as well as a "meet the load" basis. That is your homework assignment.
Good luck.

"peter" <nos...@nospam.com> wrote in message
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