Romania and Bulgaria are developing CARMEN, a grid-modernisation programme aimed at supporting the electricity system they are building rather than the one they inherited. The project has a total budget of almost €208 million, with around half expected to come from European grants. Implementation is scheduled to continue through 2032.
The initiative is being delivered by Bulgaria’s Electricity System Operator, Romania’s transmission system operator Transelectrica, and Romanian distribution company Delgaz Grid. Bulgaria’s share of the investment exceeds €59 million. Of that amount, approximately €29 million is expected to come from the Connecting Europe Facility.
Substation, automation and telecommunications scope
CARMEN covers a coordinated package of works focused on existing network assets. The scope includes substation reconstruction, automation, telecommunications and control-system upgrades. The objective is to increase usable capacity and improve visibility across the electricity network.
In Bulgaria, the works include substations such as Dobrudzha, Varna, Gorna Oryahovitsa, Mizia and Balkan. More than 1,100 kilometres of optical telecommunications infrastructure are planned along overhead lines. The plan includes the 400 kV Druzhba and Saedinenie interconnectors with Romania.
Digitalisation needs for operating higher shares of renewables
The project’s approach reflects grid constraints in Southeast Europe that cannot be addressed solely by adding transmission lines. Renewable generation is described as geographically dispersed and able to change rapidly depending on weather conditions. Real-time data, automated controls and coordinated remedial actions are identified as increasingly important for safe and efficient operation of existing infrastructure.
In some cases, digitalisation is expected to unlock additional network capacity faster and at lower cost than conventional grid expansion. The programme’s focus on controllability and visibility is linked to areas with wind and solar potential in northeastern Bulgaria and southeastern Romania. It also targets the wider north-south electricity corridor connecting renewable-rich areas with major demand centres and neighbouring markets.
Transmission-distribution coordination and regional balancing impacts
CARMEN also reflects operational links between transmission and distribution networks. Rooftop solar, batteries, electric vehicles and flexible industrial consumers are largely connected at distribution level, but their combined behaviour can influence national balancing and cross-border electricity flows. Delgaz Grid’s participation is tied to the need for an intelligent distribution layer alongside smart transmission operations.
The broader financing environment includes additional support for Delgaz Grid outside CARMEN. In July 2026, the EBRD provided Delgaz Grid with a RON 300 million loan, equivalent to around €57 million. The funds support Delgaz Grid’s 2026–2030 electricity-network investment programme covering modernisation, digitalisation and smart-meter deployment.
Implementation risks across borders
CARMEN implementation is expected to require interoperable digital systems, cybersecurity measures, skilled personnel and disciplined procurement. Installing sensors is described as having limited value if operators cannot exchange data or incorporate it into real-time capacity calculations. Cross-border delivery also carries the risk of asynchronous implementation between national systems.
The programme is positioned as more than an interconnector build-out by focusing on information, automation and control upgrades for existing infrastructure. Better information and coordinated control are intended to support accommodating more renewable generation, managing contingencies and facilitating cross-border trade . For Southeast Europe, improving performance of the network already in place is described as important where permitting and constructing major new transmission infrastructure can take many years .
