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From: Martin Brown <'''newspam'''@nonad.co.uk>
Newsgroups: sci.electronics.design
Subject: Grand Apagon - Electricity (not) in Spain
Date: Tue, 29 Apr 2025 13:24:46 +0100
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Spain suffered a very spectacular near total loss of its national grid 
yesterday taking parts of France and all of Portugal down with it. This 
is an unprecedented failure of a supergrid system by cascade failure.

It seems likely they had got the effect of widespread solar PV has on 
load shedding wrong (much like happened in the UK) and so it failed 
completely. Two events a second apart delivered the coup de grace.

They seem to have ruled out cyber attack and the electricity company is 
now trying to blame "the wrong sort of temperature variations"...

Their 400kV lines seemed to be taking the blame with the national power 
company blaming exceedingly rare atmospheric phenomena due to "large" 
temperature differences in central Spain. They claimed that the magical 
sounding "induced atmospheric vibration" was to blame.

https://www.theguardian.com/business/2025/apr/28/spain-and-portugal-power-outage-cause-cyber-attack-electricity

Another marginally plausible explanation given was that different 
impedances on cables at radically different temperatures on different 
paths messed up the phasing (but the numbers don't look right to me).

Anyone have any idea what actually happened?

The only one I am aware of that can take 400kV supergrid down is cables 
clashing together in older pylon configs where they are exactly one 
above the other and resonance effects allowing large amplitude standing 
waves to build up in the spans can occur in 70+mph winds.

Most UK ones now have a longer central pylon spur so that the lines are 
more widely separated and up-down motion cannot allow them to touch.

They do sing quite impressively in a gale though. The little weights at 
each end are apparently there to prevent such standing wave resonances 
damaging the pylon structure. Without them some pylons did fall down in 
the distant past during the most extreme of winter storms.

-- 
Martin Brown