The operation of an electrical grid is a balancing act – you have to produce *exactly* the same amount of energy as is needed, otherwise bad things happen. I don’t understand how does this rule apply on anything other than the largest scale of things.
I understand that *in general* you can predict a higher load on the grid during Monday evening when everyone is at home, and plan your energy production accordingly. But a power station can’t predict smaller load fluctuations like if I decide to turn on or off my TV at this very moment.
So, how does the electrical grid cope with unpredictable load that differs from the planned & expected one?
In: Engineering
Im going to handwave away the electrical part and instead look at a generator and a motor and treat the power lines as a solid shaft between them.
A generator is spinning at a certain speed. You connect a motor on your end, and it spins up to the same speed. That instant you connect, the generator slows down as your motor spins up. The generator is much much much bigger than your motor, so the difference is more or less negligible. Your motor has friction and losses, it doesn’t just spin infinitely, so it requires the generator to push to keep spinning at that speed. If the speed drops too much, the power plant outputs more power to the generator, causing it to speed back up.
Everyone is connected to the same spinning shaft, so there is a ton of inertia. The power plants can very precisely determine the speed of their generator, so they can apply more power if it is going too slow, or less power if it is spinning too fast, and all the power plants are working together to maintain this same speed.
The shaft is the power lines and the speed is the voltage/frequency of the cables. There are gear boxes/transformers that change the voltage but everyone is still locked together. The force slowing down and speeding up the shaft is current.
And that is where my analogy and knowledge start to break down. But fundamentally, the reason you can flip a switch without crashing the electrical grid is immense amounts of inertia in the electrical system compared to the tiny power draw of whatever any individual electrical device might pull.
Latest Answers