I’ve seen lots of posts lately on Texas being “minutes and seconds away” from months long blackouts. What could’ve happened, what was avoided that caused that?
In: Engineering
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An electric grid is a balance of push and pull. Most grids right now have little or no storage, which means the grid has to maintain enough flow to feed the demand without exceeding the maximum amount the grid can handle. Because it is a network there is some capacity to buffer by opening and closing distribution nodes and varying the amount of production coming from power plants. You want to do this within a fairly short period of changes to demand– seconds to minutes, no more.
If you have a smaller network like Texas that normally has some number of plants running (let’s say ten for the sake of discussion) and one of those plants stops its production, in this case valves and other machinery that moved the gas (which drove the plant’s generators) iced up. Now the grid is operating at 90% output.
Once this happens, either a percentage of the remaining nine need to pick up the slack by increasing their output, or… you shut down a percentage of the grid equivalent to that plant’s output. Either up the output or decrease the demand.
Long story short, this sequence of balancing can set off a cascade of ups and downs that ripple through the network as the system tries to maintain the narrow window of balance mentioned up top. If two plants still online try to compensate for the decrease of the plant that went down and overshoot, then cut back and drop under. Then plant five may ice up and things get more complicated. The push and pull becomes the equivalent of a truck that starts fishtailing– the more the driver struggles to correct things, the bigger the oscillations grow.
At some point this push and pull results in a power dump so big that you are in danger of overloading some major piece of equipment, and you have to cut off production entirely and start turning things back on one-by-one.
It must be stated that these type of situations are actually somewhat common, but MOST of the time the electricity can be shunted around the network enough to allow the operators to get the situation under control without cutting anyone off. There are exceptions, some very notable, but those are unusual.
The other possibility is that so much production went down that the remaining plants tried to take up the demand and ended up overloading their capacity, which would also fry equipment.
Either way, once the problem moves from the category of “evolving, use the network’s buffer volume now to correct” to “overload imminent, you’re f’d” the only good option is to literally throw the switch and completely knock out the whole thing in order to prevent equipment loss. Then you can start turning things back on in a controlled fashion, though in this case the gas lines feeding the power plants are iced up and can’t get the gas they need to turn their turbines, so there is no turning on that can be done.
[https://en.wikipedia.org/wiki/Cascading_failure](https://en.wikipedia.org/wiki/Cascading_failure)
Operators shut down switching equipment that was very close to overloading. Well, “seconds” may have been hyperbolic, but this equipment is extremely specialized and there are not huge stockpiles of unused equipment waiting for someone to want it. Losing too much switching equipment might lead to months of rolling blackouts as replacement equipment was manufactured.
Most world power grids are susceptible to this sort of thing, nobody has a spare power grid to use for fallback. A large solar storm or coronal mass ejection could fry enough transformers that it would take months for worldwide power to return to normal.
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