Madrid — Spain’s third vice president and minister for the Ecological Transition, Sara Aagesen, has confirmed that the April 28 blackout affecting the Iberian Peninsula originated from overvoltage events in Granada, Badajoz, and Sevilla. Speaking before Congress, Aagesen noted that the cascading disconnection of generation was likely triggered by a surge in voltage at a critical moment.
The incident, which caused a major blackout across Spain and Portugal, is now being examined by a government committee analyzing millions of data points.
2.2 GW Lost in 20 Seconds
According to Aagesen, the blackout was preceded by the loss of more than 2.2 gigawatts (GW) of power generation within just 20 seconds, mostly concentrated in southern Spain. Following these losses, cascading shutdowns were observed across multiple generation sites.
Operators reported “volatility” in voltage levels that same morning. Preliminary data also indicates that, 30 minutes before the blackout, at least two periods of oscillations in frequency and voltage were detected—both within and beyond the Iberian Peninsula.
Timeline of Grid Oscillations
ENTSO-E, the European Network of Transmission System Operators, previously reported two key anomalies:
- 12:03 PM – Strong oscillations in voltage and frequency lasting nearly five minutes.
- 12:19 PM – A second, shorter oscillation from central Spain interacting with the synchronous European grid (Germany, Austria, Italy, and Denmark).
Red Eléctrica, the Spanish grid operator, intervened during both events. However, the full sequence of reactions is still under investigation.
Cyberattack Ruled Out
Aagesen also addressed cybersecurity concerns, stating that no evidence of a cyberattack against Red Eléctrica has been found. The cybersecurity subcommittee reviewed operator logs, control centers, and generation facilities. “The good news is that no intrusion indicators were detected,” said the minister.
Complexity of the European Grid
Describing the European grid as “the largest machine in the world”, Aagesen emphasized the technical complexity involved. She reminded Congress that the Iberian system is deeply interconnected with continental Europe, and that Spain and Portugal have been granted three months to deliver a detailed incident report to ENTSO-E.
A joint presentation by both countries to the European Electricity Coordination Group is scheduled in the coming days.