Bulgaria's national electricity Transmission System Operator, contributing grid infrastructure expertise in cross-border energy trading, RES integration, and energy cybersecurity.
ESO EAD is Bulgaria's national Transmission System Operator (TSO), responsible for managing and operating the country's high-voltage electricity grid. In H2020, they contribute real-world grid infrastructure and operational expertise to projects focused on cross-border energy trading, renewable energy integration, grid flexibility, and cybersecurity of critical energy systems. Their role across projects is to provide a live transmission network as a testbed and to bring the operator's perspective on market coupling, congestion management, and grid stability challenges in Southeast Europe.
Central theme across CROSSBOW, FARCROSS, INTERRFACE, FLEXITRANSTORE, and TRINITY — covering RES integration, cross-border trading, congestion management, and wholesale market design.
CROSSBOW focuses on variable RES and storage, X-FLEX on extended grid flexibility, FARCROSS on RES forecasting and capacity reserves, and TRINITY on intelligent market technology for transmission.
EnergyShield (vulnerability assessment, SIEM, DDoS mitigation), FORESIGHT (cyber-range simulation platforms, threat forecasting), and SDN-microSENSE (resilient energy systems) form a dedicated cybersecurity cluster.
SMART5GRID (their most recent project, 2021) demonstrates 5G solutions for energy grids, signaling a move toward network softwarisation and edge computing for grid operations.
Their early projects (2017–2019) focused on foundational cross-border energy challenges: market coupling, wholesale market design, network codes implementation, and RES storage — the core business of a TSO modernizing its operations. From 2019 onward, two new threads emerged: cybersecurity of energy infrastructure (three projects in quick succession) and advanced grid technologies like dynamic line rating, power flow controllers, and RES forecasting. Their latest project (SMART5GRID, 2021) signals a pivot toward telecom-energy convergence with 5G-enabled grid applications.
ESO is moving from pure energy market integration toward the digitalization and cyber-resilience of transmission infrastructure, positioning itself for the security-aware, software-defined grid of the future.
ESO participates exclusively as a partner, never as coordinator — consistent with their role as a national infrastructure operator contributing real-world grid assets and operational knowledge rather than driving research agendas. With 208 unique partners across 28 countries and all 10 projects being Innovation Actions (IA), they operate in large, deployment-oriented consortia where their value lies in providing a Southeast European transmission grid as a demonstration environment. Their broad partner network suggests they are well-connected across the European TSO community and open to new collaborations.
ESO has collaborated with 208 unique partners across 28 countries, reflecting extensive reach across the European energy research ecosystem. Their geographic position in Southeast Europe makes them a natural bridge for projects targeting cross-border challenges in the Balkans and Eastern Europe.
As Bulgaria's sole TSO, ESO offers something most project partners cannot: access to a national-scale transmission grid in a strategically important Southeast European border region with multiple cross-border interconnections. Their dual expertise in energy markets and cybersecurity is uncommon among TSOs and makes them particularly valuable for projects that need to address both operational and security dimensions of grid modernization. For consortium builders, they bring the perspective of a smaller, non-Western European TSO navigating RES integration and market liberalization — a perspective underrepresented in many EU projects.
