Building a utility scale battery energy storage control platform for a national power system
To support Estonia’s energy transition and strengthen grid resilience, Eesti Energia AS launched a pilot initiative to validate the role of utility scale battery energy storage systems in the national power system.
As part of this program, Diotech Group partnered with CGI to design and implement Diotech's intelligent control platform for a 26.5 MW / 53.1 MWh battery energy storage system at the Auvere industrial complex.
The facility forms part of a €19.6 million investment and was commissioned to assess the suitability of large scale BESS technologies for operation in Estonia and the wider Baltic region.
We served as Diotech’s key technology partner, delivering the control capabilities required to operate the asset as a high-performance grid supporting resource prepared for participation in the Baltic frequency containment reserve market.
Meeting frequency containment reserve requirements with battery storage in a synchronizing grid
The Auvere BESS project was awarded through an international tender to Diotech OÜ and Solar Wheel OÜ, with LG Energy Solution supplying the battery technology.
As lead system integrator, Diotech required a control solution capable of meeting strict technical, operational and market requirements.
The BESS control platform needed to support:
- Fast response flexibility services
- Compliance with Baltic FCR market rules
- Safe and predictable operation under dynamic grid conditions
- Integration with renewable generation assets
- Future extensibility across markets and services
Meeting these requirements demanded precise control logic and deterministic real time behavior under both normal and stressed grid conditions.
Designing a real time BESS control architecture with PLC integration
CGI and Diotech worked as a single integrated delivery team focused on the BESS control domain.
Together, we delivered the core control capabilities required for safe, reliable and intelligent operation, including:
- Control algorithm design and validation governing energy flows, operating modes and safety logic
- PLC development and integration testing to ensure deterministic real time performance
- Unified communication architecture connecting customer systems, station control layers and market interfaces
- Support for multi market service stacking within a single control framework
This architecture enables consistent system behavior across operating scenarios while supporting future replication.
Validating grid ready battery storage through real time testing and simulation
Together with Diotech, we executed extensive scenario-based testing to validate operational readiness.
Testing activities included:
- Functional validation under normal and edge case operating modes
- Simulated grid disturbances and ramping events
- Verification of response behavior under frequency deviations
- Confirmation of compliance with Baltic FCR technical requirements
This approach ensured the BESS could respond predictably and safely under real world grid conditions.
Demonstrating grid stability and energy security through utility scale battery storage
The intelligent control platform enabled the Auvere BESS to perform as a dependable grid asset beyond laboratory conditions.
Key milestones included:
- February 4, 2025: Successful completion of the official grid test meeting all Baltic FCR compliance requirements
- February 9, 2025: Participation in the Baltic desynchronization event where the BESS contributed to frequency stabilization and national energy security
These events demonstrated both technical compliance and operational reliability.
Delivering measurable outcomes from intelligent battery energy storage control
The project delivered tangible system level and market benefits:
- Enhanced grid stability through fast response frequency regulation
- Optimized charge and discharge strategies enabling participation in electricity and balancing markets
- Improved renewable integration by absorbing variability and reducing peak demand stress
- Consumer scale impact with storage capacity equivalent to supplying up to 75,000 households for two hours
- A scalable control blueprint for future utility scale battery deployments
Delivered consumer scale impact with storage capacity equivalent to supplying up to 75,000 households for two hours
CGI and its team was approaching the cooperation with Diotech in a professional and proactive manner. While our teams collaborating closely in solving the challenge for creating a BESS control technology from scratch, we felt that we were collaborating in a mutually beneficial manner as a single team geared towards shared objective.
Member of the board, Diotech Group
