There are entire courses that cover the automation you're describing. Controllers that manage the I/O of large complicated systems are really difficult and expensive to automate due to the varying delays, gain rates, and trip scenarios that go into programming these things. This is something strong AI might be able to do some day but presently there's an asymptote to exactly how much automation you can put into a system due to either cost or complexity.

If you go look at some of the behind the scenes videos or TV specials of energy distribution, you'll see that there are a lot of correlations these operators are tracking when it comes to anticipating overall power consumption. There's a notable one about how they time the power generation in Britain with the breaks in certain television programs because a large number of people tend to turn on their electric kettles at the same time. If a computer waited until it sensed the frequency started to drop they'd overload the grid before they could ramp up production to meet demand.

These are big generators with a lot of input lag. Without anticipation of potential real world cause/effects you wouldn't be able to program enough gain to ramp up capacity for load spikes. Set the gain too low and the controller is too slow to increase output quick enough. Set the gain too high and it will ramp up for every small dip causing oscillating spikes and dips as the controller overcorrects around the target value.

I'm currently working with a small setup to control a gas flare/evaporator setup and that extremely limited system is still around $60,000 just in programming alone. We're talking about four motors,maybe a dozen block valves, and more sensors than you'd expect. The cost for automating something as big as a power plant would be in the tens of millions of dollars and it would be somewhat bespoke to each plant. You can cover a lot of man hours with that money and probably get better efficiency while you're at it. All the subsystems would be automated to a pretty good extent but right now you just can't beat having a human working the knobs and levers.