https://www.reuters.com/business/energy/investigation-into-spains-april-28-blackout-shows-no-evidence-cyberattack-2025-06-17/

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Miscalculation by Spanish power grid operator REE contributed to
massive blackout, report finds

By Pietro Lombardi and David Latona
June 17, 20257:23 PM UTCUpdated ago

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Aftermath of power outage in Ronda
Power outage in Ronda
Item 1 of 2 Friends greet each other on an illuminated shopping
street, the day after a sudden major blackout in the Iberian
Peninsula, in Ronda, Spain April 29, 2025. REUTERS/Jon Nazca/File
Photo
[1/2]Friends greet each other on an illuminated shopping street, the
day after a sudden major blackout in the Iberian Peninsula, in Ronda,
Spain April 29, 2025. REUTERS/Jon Nazca/File Photo Purchase Licensing
Rights, opens new tab

  * Summary
  * Companies

  * REE did not have enough thermal power stations switched on when
    surge occurred
  * Some conventional power plants failed to help control voltage in
    the power system
  * Blackout on April 28 caused gridlock in cities and left thousands
    stranded in trains and lifts

MADRID, June 17 (Reuters) - Spanish grid operator REE's (REDE.MC),
opens new tab failure to calculate the correct mix of energy was one
of the factors hindering the grid's ability to cope with a surge in
voltage that led to the massive blackout across Spain and Portugal on
April 28, a government investigation concluded.
The report, made public on Tuesday, also blames power generators for
the worst-ever blackout to have hit Spain and Portugal, since some
conventional power plants, such as nuclear and gas-fired plants,
failed to help maintain an appropriate voltage level in the power
system that day.

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"The system did not have sufficient voltage control capabilities,"
Spanish Energy Minister Sara Aagesen told a news briefing in Madrid.
"Either because they were not sufficiently programmed, or because
those that were programmed did not adequately provide what was
required by the standard, or a combination of both," she said.
While several factors played a role that day, Aagesen confirmed that
the ultimate cause was a surge in voltage that the grid was unable to
absorb. It triggered a cascade of disconnections of generation.
Voltage surges can be caused by multiple factors ranging from
lightning strikes, faulty equipment, or grid instability. The probe
pointed to grid instability earlier that morning.

PLANNING AND PLANTS' SHORTCOMINGS

REE, which is partly state-owned, did not have enough thermal power
stations switched on when the voltage surge caused a chain reaction
leading to the power outage, Aagesen said.
REE "told us that they made their calculations and estimated that
(switching on more thermal plants) was not necessary at this time.
They only set it for the early hours of the day, not the central
hours."
The blackout caused massive gridlock in cities and left thousands
stranded on trains and in elevators across the Iberian peninsula.
Power plants "should have controlled voltage and, moreover, many of
them were economically remunerated to do so. They did not absorb all
the reactive power that was expected," Aagesen said.
Utilities lobby Aelec, which represents Spain's main electricity
companies including Iberdrola (IBE.MC), opens new tab and Endesa
(ELE.MC), opens new tab, said in a statement it agreed that voltage
control was the main cause of the outage, adding that "the
responsibility for ensuring such control lies with" REE as system
operator.
It has evidence that the power plants controlled by the companies it
represents "have complied with the regulatory requirements regarding
voltage control" even "operating above the regulatory obligations" to
help stabilise grid.
Despite having sufficient resources to guarantee voltage control, REE
"opted to manage voltage with limited synchronous capacity and an
unbalanced geographical distribution, which left the system in a
vulnerable situation," it said.
REE did not immediately reply to requests for comment. Its chairman
will hold a press conference on Wednesday.
The government said on Tuesday it would propose measures to
strengthen the grid and improve its ability to control voltage in the
system. It would also push to further integrate the peninsula with
the European grid, it said.
Pratheeksha Ramdas, Senior New Energies Analyst and Iberia power
market expert at Rystad Energy said the incident highlighted the
essential role thermal power plants, especially gas-fired plants
continued to play.
"It appears that the blackout reflects a critical failure in the
Spanish electricity system not due to lack of installed capacity but
due to mismanagement of available energy resources and accountability
in grid operations," Ramdas said.

Reporting by Inti Landauro, David Latona and Pietro Lombardi;
Additional reporting by Corina Pons; Writing by Charlie Devereux;
Editing by David Evans, Tomasz Janowski and Sandra Maler

Our Standards: The Thomson Reuters Trust Principles., opens new tab

  * Suggested Topics:
  * Energy
  * Grid & Infrastructure
  * Gas
  * Nuclear
  * Climate Change

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Purchase Licensing Rights

 
[https]
David Latona

Thomson Reuters

Madrid-raised German-American breaking news in Spain and Portugal.
Previously covered markets in Germany, Austria and Switzerland, with
a special focus on chemical companies and regular contributions to
Reuters' German-language service. Worked at Spanish news agency EFE
(Madrid/Bangkok) and the European Pressphoto Agency (Frankfurt).

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