Fallout continues from Spanish power outage
The Spanish electricity operator Red Electrica (REE) is at odds with its government on the cause of the massive power outage that plunged most of the country into darkness in April.
The Spanish government report ruled out a cyber attack as the cause but appears to blame the operator for miscalculating the amount of inertia required in the system to keep the voltage and frequency stable. This has been put down to the increasing use of renewable energy, particularly solar farms which struggle to absorb the reactive power.
“Initial reports on the cause of the Iberian blackout indicate that commentators who blamed renewables jumped the gun and oversimplified the cause. The government’s findings seem to suggest that a combination of a miscalculation by the Spanish grid operator, voltage instability and thermal power plants – like gas – not properly operating despite being paid to contributed to the outages,” said Jess Ralston, analyst at the Energy and Climate Intelligence Unit (ECIU).
However the electrical system operator (SO) REE strongly disputes this.
It says one generation system tripped incorrectly and another did not comply with the voltage control regulations, causing an overvoltage condition.
“As it does every day, the OS performed the appropriate calculations for scheduling technical restrictions, always ensuring that all groups comply with the obligations imposed by current regulations,” it said in its report. “The incident was not caused by an inertia problem; it is explained by the balance of reactive power (voltage control) and not active power (frequency control).”
It proposes 15 recommendations, including the implementation of a dynamic voltage control service covering all generation systems.
“The first conclusion of this report is that, unlike other major incidents, this one was caused by a series of cumulative circumstances that far exceeded the safety criterion and resulted in an overvoltage problem and a cascading tripping of generation,” it said.
“From that moment on, the operator describes the succession of several significant events that led to the system’s collapse: two “forced” oscillations, i.e., triggered by possible internal anomalies in a generating plant, and three generation loss events due to incorrect tripping.”
On the other hand, it is evident that the means of the transmission network that the OS has to control the voltage, such as reactances and capacitors, acted correctly, although because they are static elements they are not suitable instruments to compensate for the lack of dynamic control that certain groups have to carry out in accordance with the regulations that apply to them.
The high voltage DC link into Baixas, France, was key in the restoration process, demonstrating once again that its reinforcement must remain a priority for the country and for the European Union as a whole, said REE.
The ENTSO-E Expert Panel, set up by the European Union to investigate the April 28th power outage in Spain and Portugal, met last week is reviewing both reports, together will all other relevant information, in particular from other concerned TSOs and from third parties. It will report again next month.
- “Report from the Committee for the analysis of the electricity crisis of April 28th 2025”, published by the Spanish government and including data from all relevant actors within Spain.
- “Blackout in Spanish Peninsular Electrical System the 28th of April 2025” by the Spanish Transmission System Operator (TSO), Red Eléctrica, in which the TSO provides its own analysis and conclusions.
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