Algr said:
https://en.wikipedia.org/wiki/Cascading_failure
Yes, the question is a general one, not specific to this heat wave or power loss. Shouldn't cutting off demand or brownouts happen
before power generation is forced to actually shut down?
It does. Or at least it is supposed to.
The #1 defense is reserve capacity. Each area purchases about 20% excess power plant capacity specifically to handle situations when weather or other problems cause loss of the regular supplies. Things like industrial gas turbines are expensive to run, but they make very good backup reserves.
The #2 defense is to reduce demand by cutting voltage. Sometimes called brownouts.
#3 is voluntary or contractual load reduction by consumers consuming less. This is mostly done at the commercial level, not residential homeowners. For example, in the NW US mining companies can use 20-30% of all electric power produced. But they can also afford to easily shut down mining during periods of high electric demand.
#4 is called load shedding, either automatic or manual. That refers to involuntary termination of power supply to some customers. Sometimes that is called rolling blackouts. But load shedding that is unplanned and not announced in advance is something that power companies hate to do because of the bad PR. The 1977 blackout in NYC was such a case. The NY State operator ordered the NYC operators to shed big fractions of the NYC load. The operators were afraid to do that. As a result, the whole state was pulled down.
Cascading failures tend to happen in two cases. First, dynamic oscillations in the grid caused by design flaws in the controls. Se cond, are limitations on how much power can be shipped from one area to another. If there are 3 routes to get power from Idaho to Southern California, and one of them gets overloaded and trips, the remaining 2 need to handle all the power themselves. That may overload a second line, and it trips. Then the third trips and we have a cascade. The limitations there are more often in the transmission system, than in the power plants. Ontario Canada may have surplus power that could help Texas, but moving it all that distance and across borders doesn't work. Texas is special, in that it has no transmission connections to the rest of North America.
But think back to what I said before. No matter how things are designed, no matter how much money we spend, they can not be expected to never fail. Power grids are no exception.
How often is acceptable? The acceptable limit was set at once per ten years for major blackouts. But blackouts that might affect only one customer at a time, happen several thousand times every day. Between those extremes is a continuum of intermediate cases. State regulators set performance goals for mean time between outages, mean time to repair, and other quality metrics.
But politics and public reactions can be emotional. Every time there is a major outage event, people get on TV and claim "I'll make sure this will never happen again." Never say never.
Edit:
@russ_watters , we crossed posts. See if this answers your question. Short form, excess demand strains the transmission system. So it is transmission that cascades, not the power plants
per se. Things like load shedding prevent the loads from becoming more than what the generating capacity can handle. Of course, involuntary load shedding can be described as a deliberate blackout, but we don't use that terminology. Figuratively, the PJM region could say "Dump Pennsylvania to save the PJM region." They would be correct in PJM's view, but PA customers would not see it that way.
