Blackouts and major grid disruptions can immobilize entire countries for days. Although the root causes are complex and rarely attributable to a single event, there are readily available options to enhance the resilience of power grids across the world.

In April 2025, the Iberian Peninsula experienced a sudden drop of energy in the space of a few seconds. As a result, the Spanish grid shut down and had repercussions on the grids of neighboring countries.

Like many similar events before, this blackout serves as an urgent call to action for grid operators, regulators and policymakers to work towards enhanced grid stability measures to prevent future blackouts and ensure a reliable energy supply.

While investigations to determine all contributing factors proceed, ENTSO-e, the European Network of Transmission System Operators for Electricity, observed that “during the half hour preceding the incident, two periods of oscillations (power and frequency swings) were observed in the Continental European synchronous area”¹

Triggered by low-frequency inter-area oscillations that led to grid separation and frequency collapse, this event underscores the challenges in interconnected power systems.

Recognizing the role of oscillations and mapping out an actionable plan is paramount to reducing the risk of encountering such disturbances in the future.

A critical contribution to stability comes from optimally tuned power system stabilizers.

Power system stabilizers (PSS) are vital components for damping power oscillations and maintaining synchronism across large power grids. However, the effectiveness of PSS depends on regular evaluation and adjustment of their parameters to respond to changing grid conditions, such as, for example, the integration of renewable energy sources.

Great support to stability comes from excitation systems with integrated PSS that provide advanced, adaptive damping capabilities, but their effectiveness hinges on proper tuning and continuous monitoring.

A comprehensive, coordinated PSS re-evaluation and re-tuning campaign across power grids would increase grid resilience, thus reducing the risk of major disrupting events such as the April 2025 blackout.

Here are some key focus areas to consider:

Investing in PSS re-tuning would be a strategic investment in the reliability and security of any energy infrastructure. It is a cost-effective measure that can prevent devastating blackouts, protect critical infrastructure, and ensure a stable energy supply for consumers and businesses, paving the way for a more resilient and sustainable energy future.