Author: Dr. Nenad Končar, M.Sc.Eng.

Date: May 2, 2025

After the historic power grid failure that affected almost the entire Iberian Peninsula on April 28, the president of the Spanish transmission system operator, Red Eléctrica, Beatriz Corredor, addressed the public with a message: “It won't happen again.”
It was a statement that, understandably, was intended to instill confidence in the system and its experts. But how can we interpret this statement from a technical perspective?

Rapid Response – A Reason for Praise

Red Eléctrica indeed demonstrated a high level of operational readiness. By 4 a.m. the following day, 100% of substations were back online.
This is an exceptional technical and organizational achievement and should not be underestimated.
In complex and interconnected power systems, recovery speed is crucial — and Spain passed that test.

But What Do We Actually Know About the Cause?

In the same address, the REE president emphasized that the cause of the failure has not yet been determined.
If we do not know exactly what caused the cascading outage, then — with due respect — the statement “it won’t happen again” is more of an expression of hope than a fact-based assurance.
As one of the world’s leading experts on grid stability once said: “Zero risk does not exist.”

The Role of Oscillations and Reduced Inertia

Data released by independent grid monitors show that voltage oscillations of increasing amplitude occurred in the hours leading up to the outage.
This is often a sign of declining grid inertia — the physical stability provided by large synchronous generators.
As Europe transitions to renewable energy, that natural stability decreases, and the need for active regulation increases.

Can We Do More?

Yes. Instead of relying solely on hope, the technical community increasingly advocates for:

• Decentralized storage systems,
• Battery plants with black-start capability,
• Grid-forming inverters that simulate the behavior of traditional generators.
  These technologies represent the new line of defense — not against renewables themselves, but against their operational challenges.

“It Won’t Happen Again” with Proven Technical Solutions

Long-term grid security is based on investments in technologies that can respond quickly, flexibly, and predictably.
The statement “it won’t happen again” will best be validated if it is accompanied by concrete measures.
Because the future of the grid cannot be secured by statements — but it can be secured by technology.