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0 pointsoersted11mo ago0 comments

I'm seeing some reports saying that a significant frequency oscillation happened, which triggered automatic shut-downs, which cascaded. Could an event like this have that effect?

I suppose it makes sense that it was an automatic shutdown rather than infrastructure failing on such a wide area. And then once it's shut down, a black-start is a logistical challenge as other comments have explained.

I'm also seeing some reports about it being more likely that something happened on the east side, somewhere like the Ebro valley or north across the Pyrenees. Catalonia seems to have been particularly affected, and it's on the path of important lines coming from France. High heat at noon could have caused a line to fail and short against a tree, which would be similar to the 2003 nation-wide outage in Italy.

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wongarsu11mo ago

The grid is supposed to tolerate any single failure, even under full load. Of course sometimes the first failure is a fire or equipment malfunction and the second failure is a planning failure or someone pressing the wrong button.

alexey-salmin11mo ago

Cascade failures are common. The weakest link fails, load gets re-distributed evenly, the second-weakest link fails and so on.

In theory [a flawed one] you've had enough spare capacity to survive N failures and N+1 failures are statistically unlikely because p^(N+1) is close to zero.

On practice [or with a better theory] you can't multiply probabilities in a grid system because random variables aren't independent. 30% spare capacity can go to -100% in a second.

AdamN11mo ago

Grey failures are harder for large systems to handle. If a chunk goes hard down that's usually easy. Something like voltage oscillations that trigger cascading failures in a sequence can lead to negative feedback loops that bring it all down.

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