The European Commission has released its second catalogue of Projects of Common and Mutual Interest: a long document of 235 energy initiatives that are meant to shape Europe’s power system for the next decade. Somewhere between large continental corridors and smaller digital upgrades sit two projects from Bulgaria’s Electricity System Operator (ESO). Their inclusion is less of a formality and more of a signal: Southeast Europe is becoming a place where the EU expects real, measurable progress.
CARMEN: A Smart-Grid Upgrade Built Around Real Operational Needs
One of the selected projects, known as CARMEN, brings together ESO, the Western Bulgaria distribution operator, Romania’s transmission company Transelectrica, and Delgaz Grid S.A.. The project sits in the “Smart Electricity Grids” category, but its goals are much more grounded than the label suggests.
The northeastern part of Bulgaria has seen a rapid rise in planned renewable capacity, mostly solar and wind, and several regions are already approaching local saturation of the 110 kV and 220 kV networks. CARMEN is designed to ease these constraints by upgrading substation automation, improving SCADA visibility and adding modern load-management tools.
Although many details vary by segment, the project includes the installation of phasor measurement units (PMUs), digital relays and improved data exchange between Bulgaria and Romania, allowing operators to track grid stability at a much finer time resolution. This helps reduce congestion along the North–South transmission corridor, where flows can fluctuate by several hundred megawatts depending on renewable output.
Instead of being a quick upgrade, CARMEN is planned to run until 2032, essentially turning the region into a testbed for next-generation grid operations. If successful, the same approach could be extended toward Hungary, Moldova and Ukraine, where similar bottlenecks have already appeared.
The Bulgaria–Serbia Interconnector: A Corridor with Very Real Capacity Implications
The second ESO project recognised by the Commission is the new 400 kV interconnector linking the Bobov Dol substation in Bulgaria with Leskovac in Serbia. Even though the line is not exceptionally long, its effect on regional transmission capacity is non-trivial.
Today, power flows between Bulgaria and Serbia rely mostly on older infrastructure with limited cross-border capability. The new link is expected to increase the transfer capacity on this border by roughly 600–800 MW, depending on operational conditions and the parallel paths used by Serbia and North Macedonia. This matters for several reasons: Serbia plans to integrate more renewable generation, while Bulgaria is steadily becoming a net exporter of solar energy during daylight hours.
With the new interconnector, electricity produced in eastern Bulgaria will be able to move more easily toward Montenegro and Bosnia and Herzegovina, essentially unlocking a western route for renewable surplus that currently has nowhere to go during peak production periods. The project also adds redundancy to a region where n-1 security is sometimes difficult to maintain during outages and seasonal maintenance.
Why Power Loop Readers Should Care?
From a strategic standpoint, these two projects reveal a pattern. CARMEN is not just another digitalisation effort; it hints at a future in which Southeast Europe becomes a fully instrumented, data-driven part of the European grid. The installation of PMUs, automated controls and upgraded substation equipment essentially lays the groundwork for AI-assisted operations, something that aligns sharply with broader trends in system optimisation, predictive maintenance and congestion forecasting.
The Bulgaria–Serbia interconnector, on the other hand, shows where the EU expects future renewable flows to move. As the solar capacity in Bulgaria grows past the 7–8 GW mark by the early 2030s, export corridors will define market prices, flexibility needs and opportunities for storage developers. For investors and analysts, this is a direct hint toward where balancing markets may open up, where new infrastructure could cluster, and which countries are positioning themselves as regional transit hubs.
In short, for anyone following Power Loop, these developments are not just technical notes from Brussels. They are early indicators of how Southeast Europe’s electricity map is being redrawn, and how the region could shift from a passive consumer of European trends to an active shaper of them.
