Romania begins building 50 MW battery storage site with 63 MVA substation

Ground works have commenced in Romania on a utility-scale battery energy storage system designed to deliver 50 MW and 100 MWh of balancing capacity. The installation incorporates twenty battery enclosures alongside power conversion apparatus, connecting into the national transmission system through a newly built 20/110 kV substation. Central to this grid interface is a 63 MVA power transformer tasked with handling bidirectional power flows between the local distribution network and the 110 kV transmission grid.

The deployment represents an expanding portfolio across southeastern Europe, where developers who entered the market in 2025 are scaling installations towards a combined 200 MWh of storage assets. Regional contracting programmes are already progressing across several counties to deliver 514 MWh of operational storage capacity. Full commissioning for this initial scheme, designated BESS 1, is targeted for 2027.

For high-voltage network planners and substation engineers, utility-scale battery interfaces present unique duty cycles compared to conventional generation. The 63 MVA unit must withstand severe thermal cycling caused by rapid switches between charging and discharging regimes. These dynamic fluctuations accelerate mechanical fatigue on winding clamping structures and place continuous dielectric stress on solid insulation and on-load tap-changers. Specifying units strictly under standards such as IEC 60076 ensures that core losses, temperature rise limits, and winding hot-spot dynamics are properly calculated for non-linear inverter loads, which introduce harmonic distortions into the 20 kV collector bus.

Furthermore, integrating large-scale inverter-based storage into the 110 kV grid requires careful coordination of protection schemes. Rapid fault-current contribution from converter stations differs sharply from synchronous machines, demanding specialised differential and distance protection settings at the collector substation boundary.

What this means for asset owners in the Balkans and the Black Sea region: developers and transmission engineers in Romania must prepare collector substation designs for severe cycling profiles well ahead of target operation dates in 2027. Sizing transformers like the 63 MVA unit requires adherence to IEC 60076 thermal and loading guidelines to prevent premature insulation degradation under intense bidirectional duty cycles.