Spanish blackout report: Power plants meant to stabilize voltage didn’t
The electricity breakdown that killed the Iberian grid serving Spain and Portugal in April is the result of a number of smaller interaction problems, according to a survey by the Spanish government. The report concludes that several stages intended to resolve a small instability have aggravated things, ultimately leading to a self-reproductive cascade where the high voltages have dropped the grid, thus increasing the tension. Above all, the report suggests that the Spanish grid operator had an unusual number of plants on call to stabilize things, and some of those she had badly answered.
The full report will be available later during the day; However, the government published a summary before its release. The document includes a chronology of events that have triggered the power failure, as well as an analysis of the reason why network management has failed to keep them in check. He also noted that a parallel investigation checked the indications of a cyber attack and found none.
Oscillations and cascade
The document notes that for several days before the power failure, the Iberian grid had undergone voltage fluctuations – the products of a gap between supply and demand – which had been managed without incident. These continued throughout the morning of April 28 until afternoon, when an unusual frequency oscillation occurred. This oscillation was traced with a single installation on the grid, but the report does not identify it or even does not indicate its type, by simply referring it as a “instalación”.
Network operators responded in a way that removed the oscillations but increased tensions on the grid. About 15 minutes later, a weakened version of this oscillation criticized, followed shortly after by oscillations at a different frequency, that with properties that are commonly observed on European networks. This prompted network operators to take corrective steps again, which increased tensions on the grid.
The Iberian grid is able to manage this kind of thing. But the network operator only provided for 10 power plants to manage the regulation of the tension on the 28th, what the report is the lowest total that he had engaged in all 2025 to this point. The report revealed that a number of these factories had not responded correctly to network operators, and some even responded in a way that contributed to the increased tensions.
