Avoiding Large-Scale Outages with Advanced Grid Software Applications

We’ve all experienced the unpleasant surprise of power outages, most of which are relatively localized and quickly remedied.

The events of April 28, 2025 were neither of the above.

On that date, starting at 12:33pm, a massive power outage struck Spain and Portugal, severing their connection to the larger Continental Europe Synchronous Area (CESA ) of Europe. The sheer multinational scale of this event meant that in less than a minute, tens of millions of people were suddenly, inexplicably left without power.

Trains ground to a halt. Phone and internet service vanished. Traffic signals, lampposts , and air conditioners shut off like blown-out candles. Both Spain and Portugal, two countries known for strong grid reliability, were at a standstill. The outage ultimately lasted around 10 hours, shortened thanks to electricity contributions from France and Morocco.

As is typically the case following a major disaster like this, speculations over the cause ran rampant. Theories ranged from over-reliance on renewables, to a solar flare, to a cyberattack. But recently, the official incident report was released and provided real answers.

According to the official investigation, the 2025 Iberian Peninsula blackout was caused by a sequence of events starting with unstable oscillations in frequency and voltage, progressing to losses of distributed generation and larger generation trips, eventually leading to an uncontrolled rise in voltage. In the progression of the event, Spain and Portugal transitioned from exporting energy to a large import situation, and at the point of the voltage rise, Spain split from France and Morocco. The resulting power deficit led to frequency drops that triggered automated emergency load shed protocols -- but this was insufficient to prevent the system collapsing.

While this may be an extraordinary situation, outages of this scale are becoming an ever-growing possibility for modern utilities. Utilities can minimize that risk by investing in modern software solutions for the transmission control room, such as the following:

It’s important to note that the events of April 28, 2025 escalated into such a widespread and prolonged outage situation due to inadequate mitigation capabilities, which failed to quell the disturbances in their infancy . There is always a risk of outages on the transmission side of the grid, especially as the line between generation and transmission continues to blur. Thus, transmission utilities must have sufficient restoration capabilities in place to get power flowing again quickly.

Utilities should seek out an Energy Management System with some degree of automation and real-time situation awareness for optimal coverage. Both can be found in GridOS AEMS Real-Time System Restoration Manager (SRM). SRM defines in real time the best outage restoration plan for an active outage situation by analyzing the actual, current system conditions. This makes for a much faster and effective restoration, versus traditional models that rely on pre-defined scenarios. AEMS Platform can make an auto-restoration plan in less than 10 seconds for an area covering 3.5 million people.

In the energy transition, the resources for traditional top-down restoration services by large central generators are becoming scarce as fossil plants retire. GE Vernova’s innovative approach to distribution-based restoration zones provides the opportunity for many smaller renewable and distributed generators to participate in Electricity System Restoration Services. Automated co-ordination and fast-response control of network zones and the available generation, load, and storage resources all provide a route for faster restoration of customers’ power while also accelerating the transmission-level restoration. The demonstrated solution of Advanced Distribution Management System for supervised automated network switching, fast closed-loop WAMPAC control of the zone’s power balance, and GridOS WAMS to observe the stability of the zone for island operation through its reconnection to transmission.

A key cause of the Iberian Peninsula outage was found to be insufficient voltage control capability. Automated voltage control is crucially important for modern grids – particularly those with significant Distributed Energy Resources and renewables integration. The number of voltage fluctuations on such grids can be immense, and some GE Vernova customers report needing more than 300 corrective actions per day to maintain the voltage profile.

Voltage management can (and should) be automated on a modern transmission grid, to ensure that any voltage fluctuations are quickly identified and corrected in near-real time. When GridOS® Advanced Energy Management System detects a fluctuation, for example, the solution quickly calculates how to best bring all voltages as close to nominal value as possible, perhaps by switching capacitators or re-dispatching generators. It then issues the right remedial actions to the relevant assets. Automated voltage management is a component of a well-equipped EMS.

There’s no denying the importance of seeing the future in the utility industry, and the Iberian Peninsula outage underscored that. There is a window between a grid disturbance occurring and it actually impacting grid operations. Utilities need every second of that window to identify the root cause of the disturbance and take corrective action before emergency measures like disconnects automatically kick in.

In normal operation of CESA, the huge scale of the interconnection means that frequency is very stable and close to 50Hz. However, a disturbance that causes a split between areas or countries leads to much more volatile frequency. In the Iberian Peninsula outage, a split from CESA led to a large power deficit without the stabilising effect of the rest of the interconnection, leading to Spain and Portugal’s plummeting frequency.

A good WAMPAC system can make a huge difference in staving off blackout situations, for both operational awareness and early warning in the control room, and for fast automated defensive action. Take GridOS WAMS, for example, which can analyze and pull critical stability insights from up to 5,000 PMUs. GridOS WAMS can provide system dynamic awareness for real-time and post operation processes. It can monitor and locate system oscillations in real-time, reporting them directly to the control room for fast intervention, thus reducing risk of unnecessary power disconnections.

Good observability and analytics of system dynamics are important for control room operation, but some cascades of disturbance require faster response than can be achieved by a human. Wide area control and protection solutions offer fast-acting responses to rebalance the system and reduce stress across interconnections, thus either avoiding system splits or greatly improving the ability to ride through a separation without the islanded section collapsing.

Although Spain’s high levels of renewables integration were found not to have caused the blackout, the events of that day brought another outage risk to the surface: inertia management . As renewables integration increases, utilities are less able to rely on traditional spinning turbines powered by fossil fuels. Because inverter-based resources such as solar panels, batteries and wind turbines have no direct inertia contribution to the grid, it’s important for utilities to both monitor what inertia they do have and have technology and procedures in place to manage it. Otherwise, the risks relating to low inertia can be significant.

Effective Area Inertia monitoring and forecasting is a module of GridOS WAMS. Through passive monitoring of the system using WAMS, it determines the combined contribution of physical inertia (mainly from synchronous generation) and all other contributions that reduce the changes in frequency as the area’s power balance changes. An operator can use this information to maintain an inertia floor level for secure operation even if the network separates from the external interconnected system, without excessive cost. The system operator can also use the forecasting facility to ensure that system has a sufficient level of effective inertia throughout the forecast period.

In one example, it was found that the effective inertia was up to 40% greater than the known physical inertia from traditional methods. This significantly reduces the costs incurred in maintaining sufficient inertial response in the region. The GridOS WAMS effective inertia approach also works together with innovative WAMPAC control to mitigate risks of system splits.

For more information on GridOS AEMS and its uses in avoiding outage situations, check out its webpage.