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Case Study
Grid-scale battery storage for aFRR balancing in Hungary
19 Oct 2026
5 min read
Project overview
At Sopronkövesd in western Hungary, KKS-Energy Kft. has designed and built a grid-scale battery energy storage (BESS) plant of 11,077 kVA / 22,154 kWh, collocated with an existing wind farm operated by the renewable generation arm of MVM Group, Hungary's state-owned energy utility. ComAp controllers aggregate the plant's 53 containerised storage units into a single control layer, handling site-wide optimisation, automatic Frequency Restoration Reserve (aFRR), and the feed-in limit shared with the wind farm. The project was delivered under Hungary's Recovery and Resilience Facility (RRF) programme and qualified to provide aFRR balancing service on the Hungarian market.
Key objectives
- Operation of 53 storage units as a single, coordinated plant qualified for aFRR balancing service
- Keep the combined feed-in of the wind farm and storage within the 23,000 kVA limit set by the Distribution System Operator (DSO) at the shared connection point
- Satisfying MVM's IT/OT security protocol within a control layer developed and maintained against ISA/IEC 62443-4-2
- Delivery of replicable control architecture independent of a BESS or Power Conversion System (PCS) supplier
The challenge
As a grid-connected asset of a state-owned utility group, the plant had to meet several sets of requirements at once. Cyber security was a hard condition rather than a preference: controllers must comply with ISA/IEC 62443-4-2, category "Embedded devices", to a minimum security level 2. Storage is classified as a type "D" generation module under Commission Regulation (EU) 2016/631, and the Hungarian Grid Code requires aFRR capability from day one. E.ON, the DSO, additionally capped combined feed-in at the shared connection point and called for protection and anti-islanding logic that strictly prevents parallel operation with the network when grid voltage is lost. Due to the number of involved stakeholders – an investor, a DSO, a transmission system operator (TSO), a BESS supplier, and a power conversion system (PCS) supplier all involved – a dedicated control platform locked to one supplier's energy management system (EMS) was never an option.
The solution
Rather than controlling 53 units individually, KKS-Energy structured the site as a single ComAp bank of four BESS groups, aligned with the four 3,150 kVA transformer stations and their four Power Conversion Systems. Each group is operated by an InteliNeo 530 BESS controller, which operates the battery circuit breaker, measures BESS voltage and current, synchronises the group to the busbar, and supports parallel operation with the other groups including load sharing and SOC balancing. Above the four groups sits a single InteliNeo 6000, which manages the bank as a whole. Site-wide optimisation, aFRR setpoint handling, and the feed-in limit are all resolved at bank level, giving one testable interface towards the plant SCADA and the system operator.
The result
KKS-Energy applied a control layer that sits above the PCS and BMS rather than inside them, so the same architecture can be copied to the next project with a different PCS or battery supplier. Grid-code compliance and cyber security are properties of the ComAp products themselves: InteliNeo 6000 conforms to EN 50549-1, EN 50549-2, VDE-AR-N 4105:2018, VDE-AR-N 4110:2018, and Austrian TÖR Erzeuger Typ A and Typ B, and the ComAp controller family is developed against ISA/IEC 62443-4-2 SL2, so neither grid compliance nor cyber security had to be proven project by project. With Hungary building out grid-scale storage rapidly, KKS-Energy now has a repeatable solution independent of any BESS supplier for a type "D", aFRR-capable plant delivered under a state utility's cyber security regime.
Sopronkövesd project had to comply with the Hungarian DSO and TSO requirements, meet RRF need and comply with the national utility's cyber security demands. With ComAp we got one control layer over 53 storage units, independent on the battery supplier, that provides grid-code and IEC 62443 compliance by default. That combination is why we chose ComAp and thanks to the solution scalability we will use the same architecture on our next storage project.
Balázs Magyari, Construction Director, KKS-Energy Kft.