How do power plants “know” the exact amount of energy that is in demand at a current moment by the millions of consumers within its distribution network?

Question

How do power plants “know” the exact amount of energy that is in demand at a current moment by the millions of consumers within its distribution network since they must produce near this amount of energy (either too much or too little energy being pumped into the grid in comparison to the energy demand has negative consequences, if I understand correctly?)

Is there some sort of signaling system that can tell how much power is being drawn at a exact moment or will be drawn one second/minute into the future?

What happens if too much energy is produced at a current moment compared to the demand?

In: 12

Answer 1

The grid is all interconnected. The power flowing through the grid is responding, in real time, to the amount of current being drawn or produced by consumers and the power plants. In other words, they know how much power is being drawn by monitoring the electrical load at the generators.

Power or current draw is essentially resistance that the generators are pushing against. Think of a water wheel in a river; if there’s nothing attached to the wheel’s axle, it’ll spin very freely. But if there’s huge machinery attached, it will resist the flow of the current.

So when the power load reduces, the water flows faster. The generators, acting like reverse water wheels, will spin faster. The people at the power plant will then dial back the amount of steam fed to the turbines to slow down the generators, so that they don’t overload the power grid. Thinking back to the river example, that would be like a flood; it would damage or destroy the water wheels by the sheer volume/speed of water.

But the key point is that, within reason, they can monitor it at the generators themselves. So long as the load on the grid changes gradually, they can adjust. In cases like power line breaks or overloads, where there’s a sudden interruption or change in the grid, the generators can be protected by automated cut-offs. In this sense, it’s better to cut the power to the grid rather than risk damage to the generators (again, generators are acting like reverse-water wheels; they are also susceptible to “flooding” damage).