Spanish government provides further details in blackout update

From pv magazine Spain

Sara Aagesen, Spain's minister for ecological transition, has stated that, while it is not yet known what caused the blackout that left the Iberian Peninsula without power 16 days ago — the commission created by the government is still gathering information — there are “elements that we do know.”

During the government oversight session in the Congress of Deputies, Aagesen confirmed that the generation losses occurred in three provinces: Granada, Badajoz and Seville.

Aagesen also assured that, after six meetings of that committee regarding the blackout, it can be “clearly” concluded that the issue was not a reserve or coverage problem that resulted in insufficient scheduled generation to cover demand on that particular Monday or to guarantee system security, “nor was it due to the size of the grids.”

“It was an exceptional event. We are working to identify the causes that will allow us to implement the necessary measures to prevent it from happening again. Our goal is to determine the causes as soon as possible and to do so with certainty,” she said.

“I can assure you that we will not be guided by political considerations” when elucidating the causes of the blackout, and that “work is being done analyzing millions of data points.”

The minister released a chronological breakdown of the incident based on the provisional information available, and noted that the analysis “is much more complex than blaming one generation source or another.”

Aagesen, who appeared this Wednesday at her own request to provide the latest information on the commission and the causes of the incident, recalled that half an hour before the blackout there were two oscillations in the Iberian system and with the rest of the continent.

Two oscillations in the system variables detected at 12:03 pm were observed, lasting five minutes, during which strong fluctuations in voltage and frequency occurred.

The second, at 12:19 pm, lasted three minutes. This, according to Aagesen, “is more common within the European system, comes from the center-east, and oscillates with respect to the European synchronous system, which, in turn, oscillates with respect to Turkey. The system operator acted to dampen these oscillations.”

After these oscillations, demand was 25,184 MW at 12:30 pm, at which time there was 3 GW of pumping. A few minutes later, a process of progressive generation losses began.

The first was detected at a substation in the province of Granada, three seconds before 12:33 pm on April 28; then, just 19 seconds later, in the province of Badajoz; and 20 seconds later, in the province of Seville. These three events resulted in a cumulative loss of 2.2 GW in just a few seconds.

“Immediately afterward, the cascading overvoltage disconnection phase begins,” Aagesen stated, “rises and drops,” and, shortly after, demand shedding and the loss of synchronization occurred. This loss triggered interconnection losses, she added, detailing that, at 12:33 am, the frequency dropped and the first load shedding threshold was crossed (demand was no longer supplied). As generation losses continued, the following load-shedding steps were activated. The last and sixth was activated at 12:33 pm, and finally, the peninsular electricity grid was reached.

In other words, Spanish transmission system operator REE unsuccessfully attempted six demand-shedding measures to try to avoid a total blackout. “None of these procedures managed to stop the system from failing, and finally, the peninsular grid was reached.” It remains to be determined why these firewalls were insufficient.

At 12:44 pm, the interconnection with France was reconnected. “As soon as the grid was zero, work began to restore supply,” the minister said.

Aagesen stated, for the first time, that a cyberattack on the system operator has been ruled out, as “there is no indication that leads us to believe so,” which the minister considers “very good news.”

Furthermore, she explained that the focus of the data analysis on the incident had been expanded, not only to that morning or the previous week, but also to the time period of the analysis.

At the same time, Aagesen defended Spain's commitment to renewable energy. “We're not just talking about sustainability, but about energy autonomy and competitive prices, new investments, and a real opportunity for re-industrialization,” she noted. “A more renewable energy mix reduces external risks,” she argued, concluding that Spain's low electricity prices, thanks to the high penetration of renewables, are “an opportunity for the country that we cannot miss.”

Regarding the importance of nuclear technology in the wake of the blackout, Aagesen believes that linking the timing of the nuclear shutdown with the incident “is not serious.” She noted that it was the companies that own and operate the nuclear power plants that proposed a timeline for the shutdown, and the government supported that closure. “If companies want to propose a new schedule, this government will study it rigorously, taking into account that it guarantees the safety of the population — for which a favorable report from the National Security Council is required — that it is economically viable, meaning that its extension does not affect citizens' pockets, and that it contributes to the security of supply,” she concluded.

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