I think I’m missing the point of the strategies in regulating the 60 Hz frequency of the US power grid.
I have not found one single reference that explains everything in a way that seems reasonable.
But I have pieced together an unreasonable story using many references.
Apparently, the US power grid is in about 4 segments that do not maintain phase relationships between them. I’m in the largest one, which handles the Eastern US. For mine (or for any of the others by itself), the power company recognizes that it is hard to bring generators online if you don’t know the phase you have to match.
Back in the day, people would add a generator to a polyphase AC system by stringing lightbulbs in a circle and adjusting the generator speed to make the light stop chasing around the circle, and then throw the switch. Now it’s more complicated of course.
So what they do is keep the phase under very precise control, by guaranteeing that there will be 5,184,000 cycles in any day (that’s 60 times the number of seconds in a day, 86400).
But they let this thing get several cycles out of phase during the day, and trim things at the end of the day to hit the 5184000 mark precisely at midnight.
Note that if they do it this way, it actually doesn’t make bringing a generator on line any easier. As long as you’re a big part of a cycle out of phase, the timing is worthless.
Note also that when you are bringing a generator on line to match a power grid, you obviously have access to both the generator phase and the power grid phase, so it’s not as if you need an accurate clock to do it.
I read that power companies consider the 60 Hz frequency a timing service for which they don’t charge.
I also read that on the time scale of a few milliseconds to a few seconds, the physical rotating inertia of all the generating equipment actually forms the reservoir that does load leveling, so it has to be able to speed up or slow down with some freedom. It’s obvious they don’t regulate steam turbine valves or hydroelectric gates or house-sized deisel generators on a 1 second timescale.
So - anybody an expert on this? Or can you send me someplace that is?
While we’re on the subject, everybody should go check out leapsecond.com. It’s incredible.