If all the power that goes into the electric grid must be consumed and the sum must be 0, how the hell are they able to generate same amount of eletric energy that is consumed?

850 views
0

If all the power that goes into the electric grid must be consumed and the sum must be 0, how the hell are they able to generate same amount of eletric energy that is consumed?

In: Engineering

If the load of the power grid increased the load on the generators will be higher and the will slow down and the voltage will drop a bit. Lower voltage result in less power use and the system is self regulating. The same way the voltage can increase i the load drops.

What humans do is to add and remove power production capacity to keep the voltage and frequency correct.

By monitoring grid voltage and frequency we can monitor imbalances between the grid demand and the grid supply. If they are going up then we are making too much power. If they are going down then we are making too little.

Small variations in overall demand are managed by automated systems. Note that while they are pretty much all computer controlled now, this isn’t strictly necessary. We’ve been doing this for a century with analog electrical and even mechanical solutions.

Example of a mechanical solution is a centrifugal governor. Basically, the faster it spins, the higher the centrifugal force is on a spinning weight attached to a turbine- generator. The position of that weight is fed back – mechanically – into the valve that controls how much steam is admitted to the turbine. As the turbine speeds up it closes the valve to reduce steam, and vice versa. By carefully calibrating such a setup, you can make it so it will apply as exactly much steam as necessary to keep the generator spinning at 60Hz (desired grid frequency) to meet demand – and when demand changes, the valve will automatically admit more/less steam to bring the frequency back up or down .

Large changes are predictable based on time of day, time of year, and to a lesser extent the weather. Planners tell generators to turn on and off, or to reduce power, in a coarse way to follow this predicted demand – and then the automated systems manage the second-by-second variation.