I was thinking on the drive home for work that the ever increasing number of electric vehicles will likely mean an increasing demand on the energy infrastructure’s of countries.
But what is actually happening in the electricity grid if supply can’t meet demand? Is it simply the devices furthest away from the generation of power won’t receive current?
Whilst this is ELI5, I also wouldn’t mind a slightly more technical answer. Thanks!
In: 9
Two things can happen on generator side.
If the generator excitation current is maxed out to provide the rated power, pulling more load from the circuit will cause the voltage to sag.
If the generator excitation continues to rise to try to generate more power to feed more current so the voltage doesn’t sag, the torque required to turn the generator will also increase. if the engine driving the generator cannot produce enough torque, the RPM will decrease and the generator slowly drops out of phase.
Voltage dropping will be noticable as light dimming, stuff like TVs, computers tripping off, users starts to complain about the quality of electrical power, but there is no blackout.
Phasing issues on the other hand is much more worse. Different parts of the grid that have interconnections to share the load must be synced in frequency, phase and voltage. Inconsistencies in frequency will quickly result in phase differences, which will cause massive voltage differences inside each oscillation, overloading the interconnections despite no real power being transmitted.
Therefore the grid operator will be forced to either slow the whole grid frequency down a bit, increase voltage of other parts of the grid to try to feed the overloaded grid, or just cut the overloaded part off.
Slowing the grid down results in the frequency going out of spec, it’s another quality issue and if there are interconnections to other parts of the grid not under his/her control, they will also be forced to disconnect them.
Feeding the grid risks overloading the other plants/transmission lines, especially at the interconnections, because they are typically designed to only carry the load differencesof normal days between the grid, not situations like this when there is a massive shortage. Overloading the grid risks in tripping various parts of it.
If a trip happens, it could be a downward spiral from there, the grid quickly collapses and it may take hours or even days to restart it.
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