> So we know there are deviations in line freq. But it seems strange in this > era of very accurate and inexpensive freq references. How much is related to > the generation?
Controlling the line frequency is a giant PLL, with horrible complications. The simple setup for a big generator is that if you add load, the generator will slow down slightly. You can feed it more fuel to get it back up to speed. I think that part is classic PLL theory. Given the inertia of the generator and time delay around the loop, you can predict the response to a simple change in load, watch for instabilities and such. In the real world, there are at least two levels of complications. The first is that you are doing it with many generators rather than one. When load is added, you have to decide which generator(s) will work harder. The other nasty complication is that you want to do it as cheaply as possible as well as follow all the rules from regulators. One of the complications from regulators is a requirement to make clocks that depend on the line frequency keep good time. There was a proposal a while ago to remove that constraint. I think it got dropped, but I could easily have missed an interesting announcement. --------- Has anybody collected data from a typical few-KW portable generator? It would be interesting to see if "interesting" things happen if you turn some lights on/off at the right frequency. Here is the Aurora video: Staged cyber attack reveals vulnerability in power grid http://www.youtube.com/watch?v=fJyWngDco3g (1 min) -- These are my opinions. I hate spam. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.