Many region-wide blackouts (like this one or this one) are described as follows: some high-voltage equipment (like a generator or a transformer) fails and the grid gets overloaded and then protective devices start tripping everywhere and millions of consumers are in the outage.
I don't get it. Okay, some generator or transformer fails, but there's dozens of such generators and transformers in the region grid.
Why is the load not partially disconnected so that the consumption matches the production again? Why would a relatively small deficit of delivered power lead to a region-wide blackout?
Best Answer
TLDR: better design is not affordable.
Technical root cause is the limited speed of light. Natural root cause is the conflict of economy of scale vs redundancy requirement.
Every energy supplying element in system is protecting itself by disconnecting, stopping the supply. Disapperance of supplier, causes increase of individual load on other suppliers. Which in their turn disconnect themself. The blackout escalation behaves very much like an avalanche.
The proper design must have granularity of demand control (consumer's pool) be finer than smallest individual supplier, and total supply capacity must be greater than total demand by at least one unit of supplier's granularity. In theory the redundance of suppliers must protect from blackouts. But in reality the granularity on both sides is too coarse, and is impossible to be made finer. Because downsizing is in conflict with economy of scale. Every power plant, distribution line and other elements are built to be as large as possible and point of connection to consumer always exceeds the optimal size granularity wise. Just because of market competition it is not possible to limit the size of lines, power plants and other elements.
The solution can be found only in regulatory space. Say: add the smart load control capability to all household Energy-Star rated equipment and introduce concept of "quality of service", complex system of tariffs, uplinks, protocols, etc.