Spain’s grid operator, Red Eléctrica, proudly declared that electricity demand across the country’s peninsular system was met entirely by renewable energy sources for the first time on a weekday, on 16 April 2025.
Just 12 days later, at 12.33 p.m. on Monday, 28 April, Spain and Portugal’s grids collapsed completely, plunging some 55 million people into one of the largest blackouts the region has ever seen. Entire cities lost electricity in the middle of the day. In the bustling airports of Madrid, Barcelona, and other key hubs, departure boards went blank. No power. No Internet. Even mobile phone service—something most people take for granted—was severely compromised. It was just disconnection and disruption. On the roads, traffic lights stopped functioning, snarling traffic and leaving people wondering when the power would return.
While the size and scale of the impact were unsettling, the speed at which it happened was the scariest part. Within minutes, the whole of the Iberian Peninsula’s energy generation dropped from roughly 25GW to less than 1.2GW.
While this may sound like a freak accident, incidents like this will continue to happen, especially given the rapid changes to the electrical grid over the past few decades. Worldwide, power systems are evolving from large centralized generation to a multitude of diverse, distributed generation sources, representing a major paradigm shift. This is not merely a “power” problem but is also a “systems” problem. It involves how all the parts of the power grid interact to maintain stability, and it requires a holistic solution.
Power grids are undergoing a massive transformation—from coal- and gas-fired plants to millions of solar panels and wind turbines scattered across vast distances. It’s not just a technology swap. It’s a complete reimagining of how electricity is generated, transmitted, and used. And if we get it wrong, we’re setting ourselves up for more catastrophic blackouts like the one that hit all of Spain and Portugal. The good news is that a solution developed by our group at Illinois Institute of Technology over the last two decades and commercialized by our company, Syndem, has achieved global standardization and is moving into large-scale deployment. It’s called Virtual Synchronous Machines, and it might be the key to keeping the lights on as we transition to a renewable future.
Rapid Deployment of Renewable Energy
The International Energy Agency (IEA) created a Net Zero by 2050 roadmap that calls for nearly 90% of global electricity generation to come from renewable, distributed sources, with solar photovoltaic (PV) and wind accounting for almost 70%. We are witnessing firsthand a paradigm shift in power systems, moving from centralized to distributed generation.
The IEA projects that renewable power installations will more than double between 2025 and 2030, underscoring the urgent need to integrate renewables smoothly into existing power grids. A key technical nuance is that many distributed energy resources (DERs) produce direct current (DC) electricity, while the grid operates on alternating current (AC). To connect these resources to the grid, inverters convert DC into AC. To understand this further, we need to discuss inverter technologies.
Professor Beibei Ren’s team at Texas Tech University built modules for a SYNDEM test bed with 12 modules and a substation module, consisting of 108 converters. Beibei Ren/Texas Tech University
Most of the inverters currently deployed in the field directly control the current (power) injected to the grid while constantly following the grid voltage, often referred to as grid-following inverters. Therefore, this type of inverter is a current source, meaning that its current is controlled, but its terminal voltage is determined by what it connects to. Grid-following inverters rely on a stable grid to inject power from renewable sources and operate properly. This is not a problem when the grid is stable, but it becomes one when the grid is less stable. For instance, when the grid goes down or experiences severe disturbances, grid-following inverters typically trip off, meaning they don’t provide support when the grid needs them most.
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