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The Spanish grid operator has dismissed the possibility of a cyber attack being the trigger for a significant power outage that affected Spain, Portugal, and parts of France on Monday.
Eduardo Prieto, the operations director of Red Eléctrica, stated that initial investigations indicate there was no disruption to the control systems that would suggest an attack, a point echoed by Portuguese Prime Minister LuÃs Montenegro the previous day.
Nevertheless, the precise reasons behind the power cut remain uncertain.
On Tuesday, the grid operator noted that they are unable to reach any conclusions until they gather more definitive data. Spanish Prime Minister Pedro Sánchez mentioned that investigators are actively working to identify the cause and will implement necessary measures to prevent future incidents.
Information is slowly emerging regarding the circumstances surrounding the outage, leading to various theories about its origin. Experts have suggested to the BBC that the outage may have resulted from multiple failures occurring simultaneously.
Here is what is known thus far and the questions that still linger.
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On Monday evening, Sánchez indicated that 15 gigawatts of power, equivalent to 60% of the demand at that time, was “suddenly lost from the system… in just five seconds.”
During a press briefing on Tuesday, Prieto indicated that two “disconnection events” occurred just a second apart in southwestern Spain, a region known for its significant solar power capacity.
It is possible that the grid operator was alluding to situations where power companies detect an imbalance between electricity supply and demand, prompting them to temporarily disconnect to safeguard their systems.
However, Sánchez later clarified that the outage was “not due to excessive renewables.” He explained that there was no issue with overall power supply, and the demand for electricity was relatively low—a typical situation in the days preceding the incident.
The exact mechanics of what transpired remain elusive, particularly since outages of this magnitude occur globally about once a year.
A disconnect between supply and demand can alter the frequency of the electricity grid, which operates at 50Hz in Europe and the UK.
If this frequency drifts outside a narrow margin, it can risk damaging equipment.
Prof. Hannah Christensen from the University of Oxford explained that when a large company detects frequency deviations beyond their tolerance, they may disconnect to protect their machinery.
If multiple companies perform this action in rapid succession, it could trigger a cascading failure leading to a blackout, she noted.
Renewable energy operators, however, typically utilize precise short-term weather forecasts to predict surplus production from wind or solar sources, allowing them to adjust supply accordingly.
Prof. Christensen remarked on the inherent unpredictability of renewable energy compared to fossil fuels, but emphasized that this is a known challenge that is planned for.
She added, “It is somewhat surprising that this could not have been anticipated.”
Prof. Keith Bell from the University of Strathclyde further highlighted that systems reliant on solar and wind energy are designed to accommodate these variables, suggesting that increased renewable energy supply should not have posed a problem for the grid.
“Spain has extensive experience with wind and solar energy and has established forecasting systems over time,” he noted.
He also mentioned, “Variety in failures can occur across all energy types,” noting that outages can stem from renewables, fossil fuels, or nuclear power. This could illustrate the Swiss cheese model, where various system vulnerabilities align.
Red Eléctrica further suggested that the power drop may have caused a trip in the grid interconnection between Spain and France.
Interconnections between different parts of a grid or countries utilize two fundamental technologies: standard transmission lines carrying alternating currents and high voltage direct current lines, increasingly common.
Spain employs a high voltage line that has been operational for seven years, validating its reliability, according to Prof. Bell.
The Iberian Peninsula is often described as an “electricity island” due to its limited connections with France through the Pyrenees, rendering it susceptible to failures.
According to Sánchez, power was restored thanks to interconnections with France and Morocco, in addition to gas and hydropower sources.
Portugal’s grid operator, REN, has discredited initial reports, attributed to them on Monday, linking the blackout to a rare atmospheric phenomenon.
A message in Portuguese suggested that “extreme temperature variations in inland Spain led to unusual oscillations in the very high voltage lines (400 KV), a phenomenon dubbed ‘induced atmospheric vibration’.”
These oscillations were said to cause synchronization failures between interconnected electrical systems, resulting in multiple disturbances across the European network.
However, REN spokesman Bruno Silva stated to AFP on Tuesday that the organization “did not issue this statement,” without elaborating further.
Source
www.bbc.com