That’s not exactly true.
You can’t magically tell electrons where to go, they’re going to follow the path of least resistance.
The whole “Florida selling power to [insert any neighboring state] thing is really a misnomer, and I promise I’m not trying to be a jerk, it’s a common misconception. What you’re seeing is basically Generator A ramps up to the point where Utility 1 is now producing 100 MW more than their customer base is consuming. Utility 2 is now safe to ramp down Generator B and they can produce 100 MW less than their customer base is consuming, because they have a financial transaction with Utility 1 in the amount of 100 MW. As long is everything is accounted for and the system frequency stays at 60 Hz aka 3600 rpm, all is good.
The whole idea is to produce exactly the amount of power your customer base is consuming, even if that means purchasing it on the open market. But it’s not always that simple.
Because like we talked about earlier, you can’t really tell the power where to go. Those are real life power lines out there of varying conductor size, operating voltage and impedance. There is a lot that goes into dispatching power generation.
For example, ramping Generator A up and ramping Generator B down could theoretically cause an overload on a transmission line or bulk power transformer. So most utilities and/or regional power conglomerates have “transfer limits” which only allow them to pass a certain amount of transacted power through their system.
You also can’t create a real time or contingency overload. Or cause a voltage violation.
So that was a very long winded way of saying, unfortunately, it’s not always that simple. LOL.