3 ms·

One interesting thing about the "load changes the frequency" thing is that if you measure the frequency in enough places, you can actually see how large load ch

One interesting thing about the "load changes the frequency" thing is that if you measure the frequency in enough places, you can actually see how large load changes "ripple" through the system. For example, there was a big power outage in Florida in 2008 that caused a generator to suddenly go offline, and several orgs had a couple dozen power frequency meters running on the grid at the time, so they were able to make an animation of the east coast power grid "ringing" over the course of about 10 seconds as the load changed rapidly throughout the grid. The animation for that is here: https://www.youtube.com/watch?v=bdBB4byrZ6U https://www.youtube.com/watch?v=bdBB4byrZ6U

hexane360 9y ago
Really interesting to see how some chunks lag more or less than would be indicated by geography alone. For example, the Chicago and Indianapolis areas seem to be much more affected from the northwest than the southeast. I wonder if this is mostly due to topology or just grid capacity. Do you know how the power plant's control loops are tuned? It seems like just tuning your plant to be properly damped isn't enough, because there's also lots of feedback from other power plants.
- elfchief 9y ago
  I don't know for a fact how they manage it, but I bet the feedback is slow enough (those generators are heavy, and it probably takes a few cycles to even accurately measure a change) that they might not have to do much in the way of actively managing that feedback. The system will oscillate a bit (as it did in that video), but there's nothing inherently wrong with that, as long as it's within a certain set of limits. (And really, the load changes are typically more gradual. Even "everyone just got home from work" is a fairly spread out event, compared to, say, the sudden loss of a few hundred MW of generating capacity...)
_trampeltier 9y ago
Break time in big sport events also leave there fingerprints in the grid frequency. Everybody start to make a coffee, go to toilet (light), etc.

hexane360 9y ago

Really interesting to see how some chunks lag more or less than would be indicated by geography alone. For example, the Chicago and Indianapolis areas seem to be much more affected from the northwest than the southeast. I wonder if this is mostly due to topology or just grid capacity. Do you know how the power plant's control loops are tuned? It seems like just tuning your plant to be properly damped isn't enough, because there's also lots of feedback from other power plants.

elfchief 9y ago
I don't know for a fact how they manage it, but I bet the feedback is slow enough (those generators are heavy, and it probably takes a few cycles to even accurately measure a change) that they might not have to do much in the way of actively managing that feedback. The system will oscillate a bit (as it did in that video), but there's nothing inherently wrong with that, as long as it's within a certain set of limits. (And really, the load changes are typically more gradual. Even "everyone just got home from work" is a fairly spread out event, compared to, say, the sudden loss of a few hundred MW of generating capacity...)

_trampeltier 9y ago

Break time in big sport events also leave there fingerprints in the grid frequency. Everybody start to make a coffee, go to toilet (light), etc.