According to the recently released Phase II technical report by the European Network of Transmission System Operators for Electricity (ENTSO-E), all newly built or substantially renovated energy storage systems and renewable energy installations with a capacity above 1MW will be required to have grid-forming functions.
Energy storage systems will no longer merely connect to the grid passively but must actively participate in regulating grid voltage and frequency, much like synchronous generators, to support grid stability. The Phase II report provides detailed technical guidance for the future implementation of the NC RfG 2.0 draft.
Key Technical Indicators for Grid-Forming Energy Storage
Based on the Phase II report, grid-forming energy storage systems must meet the following core indicators:
▍ Voltage and Frequency Control Capability
The system must maintain voltage stability during grid frequency or phase fluctuations, instantaneously provide reactive current, and maintain synchronization without external references.
▍ Rapid Response and Damping Requirements
- Current response time: <10 milliseconds
- Power oscillation damping rate: ≥5%
▍ Synthetic Inertia Support
The system must provide millisecond-level synthetic inertia, equivalent to the inertia constant of a virtual synchronous machine, to support frequency fluctuations.
▍ Disturbance Tolerance
The system must pass tests for voltage dips, step changes, and phase angle jumps to ensure stable operation during grid disturbances.
Implementation Timeline
According to the DSO Entity document, NC RfG 2.0 is expected to be finalized in 2026. After the regulation takes effect in EU member states, countries may set transition periods based on local grid conditions, typically around three years.
Therefore, most energy storage projects are expected to fully comply with the grid-forming capability requirements starting in 2028–2029. For developers, now is a critical time to proactively plan and upgrade energy storage control systems, grid-forming PCS, and testing solutions.
