What caused it?
The Portuguese prime minister, Luís Montenegro, said that the issue originated in Spain. Portugal’s REN said a “rare atmospheric phenomenon” had caused a severe imbalance in temperatures that led to the widespread shutdowns.
REN said: “Due to extreme temperature variations in the interior of Spain, there were anomalous oscillations in the very high voltage lines (400 kV), a phenomenon known as ‘induced atmospheric vibration’. These oscillations caused synchronisation failures between the electrical systems, leading to successive disturbances across the interconnected European network.”
They have data and probable causes, but nobody will tell until forensic studies take place, which seems a good decission. No need to spread speculations.
A cold start from zero generation took 6 to 10 h. No casualties, hospitals and crtitical infrastructure kept working all day.
Whatever the cause, this has been a great test of the emergency protocols.
REN said: “Due to extreme temperature variations in the interior of Spain, there were anomalous oscillations in the very high voltage lines (400 kV), a phenomenon known as ‘induced atmospheric vibration’. These oscillations caused synchronisation failures between the electrical systems, leading to successive disturbances across the interconnected European network.”
https://www.theguardian.com/business/2025/apr/28/spain-and-p...