The power generation system uses a closed-loop control. It's easier to visualize if you think of a single traditional rotating generator connected to resistive

The power generation system uses a closed-loop control. It's easier to visualize if you think of a single traditional rotating generator connected to resistive loads like incandescent bulbs. The electrical power being used by the lamps acts as a "brake" on the generator: it takes energy from its rotation, so you need more mechanical power to spin the generator shaft at the same RPM. Now suppose some of these incandescent lamps are turned off. The power being consumed is reduced, so the power being taken from the shaft rotation is reduced, so you need less effort to spin the shaft. If the mechanical input is the same, the shaft will spin faster. And here is the trick: there's a mechanism which senses the shaft increasing its speed, and reduces the mechanical input, for instance by partially closing a water gate, until the speed returns to normal. The same happens in the opposite direction: if more of the incandescent lamps are turned on, the shaft slows its speed, the mechanism senses this and opens the water a little more, until it's back to the correct speed. What we have on modern continent-wide power networks is basically a scaling up of that principle. So the answer to your question is: the extra power is not produced, the production automatically reduces until only 95 units of energy are being produced, matching generation and demand. What happens if that's not the case? Simple, if production and demand are not within a few percent of each other, protective relays cut the generators and/or loads until it matches, to prevent damage to the generators, power distribution devices, and loads.