INSUBCONTINENT EXCLUSIVE:
The blackout that took down the Iberian grid serving Spain and Portugal in April was the result of a number of smaller interacting problems,
according to an investigation by the Spanish government
The report concludes that several steps meant to address a small instability made matters worse, eventually leading to a self-reinforcing
cascade where high voltages caused power plants to drop off the grid, thereby increasing the voltage further
Critically, the report suggests that the Spanish grid operator had an unusually low number of plants on call to stabilize matters, and some
of the ones it did have responded poorly.The full report will be available later today; however, the government released a summary ahead of
The document includes a timeline of the events that triggered the blackout, as well as an analysis of why grid management failed to keep it
It also notes that a parallel investigation checked for indications of a cyberattack and found none.The document notes that for several days
been managed without incident
These continued through the morning of April 28 until shortly after noon, when an unusual frequency oscillation occurred
This oscillation has been traced back to a single facility on the grid, but the report doesn't identify it or even indicate its type, simply
About 15 minutes later, a weakened version of this oscillation occurred again, followed shortly thereafter by oscillations at a different
frequency, this one with properties that are commonly seen on European grids
That prompted the grid operators to take corrective steps again, which increased the voltages on the grid.The Iberian grid is capable of
handling this sort of thing
But the grid operator only scheduled 10 power plants to handle voltage regulation on the 28th, which the report notes is the lowest total it
had committed to in all of 2025 up to that point
The report found that a number of those plants failed to respond properly to the grid operators, and a few even responded in a way that
contributed to the surging voltages.
