The blackout that took down the Iberian grid serving Spain and Portugal in April was the results of a variety of smaller interacting issues, based on an investigation by the Spanish authorities. The report concludes that a number of steps meant to deal with a small instability made issues worse, ultimately resulting in a self-reinforcing cascade the place excessive voltages induced energy vegetation to drop off the grid, thereby rising the voltage additional. Critically, the report means that the Spanish grid operator had an unusually low variety of vegetation on name to stabilize issues, and among the ones it did have responded poorly.
The complete report will probably be out there later at this time; nevertheless, the federal government launched a abstract forward of its launch. The doc features a timeline of the occasions that triggered the blackout, in addition to an evaluation of why grid administration did not maintain it in test. It additionally notes {that a} parallel investigation checked for indications of a cyberattack and located none.
Oscillations and a cascade
The doc notes that for a number of days previous to the blackout, the Iberian grid had been experiencing voltage fluctuations—merchandise of a mismatch between provide and demand—that had been managed with out incident. These continued by means of the morning of April 28 till shortly after midday, when an uncommon frequency oscillation occurred. This oscillation has been traced again to a single facility on the grid, however the report would not determine it and even point out its kind, merely referring to it as an “instalación.”
The grid operators responded in a approach that suppressed the oscillations however elevated the voltages on the grid. About quarter-hour later, a weakened model of this oscillation occurred once more, adopted shortly thereafter by oscillations at a special frequency, this one with properties which might be generally seen on European grids. That prompted the grid operators to take corrective steps once more, which elevated the voltages on the grid.
The Iberian grid is able to dealing with this form of factor. However the grid operator solely scheduled 10 energy vegetation to deal with voltage regulation on the twenty eighth, which the report notes is the bottom complete it had dedicated to in all of 2025 as much as that time. The report discovered that a variety of these vegetation failed to reply correctly to the grid operators, and some even responded in a approach that contributed to the surging voltages.
