Following the blackout incident in the Iberian Peninsula on 28 April, ENTSO-E and its members have set up a joint Expert Panel led by experts from TSOs that weren’t directly affected by the incident and includes experts from both affected and non-affected TSOs. The investigation will be split into two phases. First, the panel will collect and analyze all available data on the incident to reconstruct the events of 28 April and determine the causes of the blackout. These insights will be completed and published in a factual report. In the second phase, the panel will establish recommendations to help prevent similar incidents in future, which will be published as a final report.
ENTSO-E is providing a preliminary chronology with the information known so far. An in-depth analysis by the Expert Panel will be provided in a full technical report.
On 28 April 2025 at 12:33 CET, the power systems of Spain and Portugal suffered a total blackout. A small area in France, close to the border with Spain, was also affected by the incident, albeit for a very limited duration. The rest of the Continental European power system did not experience any disturbance.
During the half hour preceding the incident, two periods of oscillations (power and frequency swings) were observed in the Continental European synchronous area, between 12:03 and 12:07 CET and between 12:19 and 12:21 CET respectively. The TSOs of Spain (Red Electrica) and France (RTE) took actions to mitigate these oscillations. At the moment of the incident, there were no oscillations, and the power system variables were within normal operation range.
Before the incident, the international exchange programs of Spain were 1,000 MW to France, 2,000 MW to Portugal and 800 MW to Morocco, all in the exporting direction.
Data so far has yielded the following sequence of events during the incident:
- Starting at 12:32:57 CET and within 20 seconds afterwards, presumably a series of different generation trips were registered in the south of Spain, accounting to an initially estimated total of 2200 MW. No generation trips were observed in Portugal and France. As a result of these events the frequency decreased, and a voltage increase is observed in Spain and Portugal.
- Between 12:33:18 and 12:33:21 CET, the frequency of the Iberian Peninsula power system continued decreasing and reached 48,0 Hz. The automatic load shedding defense plans of Spain and Portugal were activated.
- At 12:33:21 CET, the AC overhead lines between France and Spain were disconnected by protection devices against loss of synchronism.
- At 12:33:24 CET, the Iberian electricity system collapsed completely and the HVDC lines between France and Spain stopped transmitting power.
As soon as the disruption of the electricity supply occurred, the affected TSOs worked together in a coordinated effort to restore the power in the affected region of France, as well as in Spain and Portugal.
For more information you can visit:
https://www.entsoe.eu/news/2025/05/09/entso-e-expert-panel-initiates-the-investigation-into-the-causes-of-iberian-blackout/
