Denmark — Grid Code for Energy Storage
Energinet's grid code framework for battery energy storage systems connected to the Danish electricity supply system. The primary specification is Technical Regulation 3.3.1 (Revision 6), effective from 1 May 2025. Denmark operates in two synchronous areas: DK1 (Continental Europe) and DK2 (Nordic).
What makes TR 3.3.1 different
Two synchronous areas (DK1 / DK2)
Denmark spans Continental Europe (DK1, West) and Nordic (DK2, East). Frequency control settings differ: LFSM-O breakpoint is 50.20 Hz in DK1 vs 50.50 Hz in DK2. FSM bands also differ between areas.
Dedicated storage regulation
TR 3.3.1 is a standalone regulation written specifically for energy storage facilities — not a repurposed generation code. It covers both synchronous and non-synchronous storage, plus V2G.
V2G explicitly in scope
Vehicle-to-Grid (V2G) bi-directional charging stations are explicitly included. The regulation specifies that either the charging station or transport owner must comply, depending on where conversion occurs.
Lower type thresholds
Type boundaries are lower than many EU countries: Type A up to 125 kW, Type B 125 kW – 3 MW, Type C 3 – 25 MW, Type D ≥ 25 MW or ≥ 110 kV. Most utility-scale BESS fall under Type C or D.
Type categories (TR 3.3.1 Section 2)
Most utility-scale BESS projects in Denmark fall under Type C or D. Type D also requires island mode capability and simulation models.
Main specification
Technical Regulation 3.3.1 — Requirements for Energy Storage Facilities (Revision 6)
93-page regulation covering 20 parts: scope and definitions, requirements per type (A–D), synchronous and non-synchronous storage, transmission-connected facilities, compliance testing, simulation, and grid connection procedure.
View all TR 3.3.1 requirements
Full requirement breakdown by functional category — operating ranges, FRT, frequency control, reactive power, protection, compliance testing.
Key technical parameters (Type C/D)
| Parameter | DK1 (Continental) | DK2 (Nordic) |
|---|---|---|
| Continuous frequency | 49.0–51.0 Hz | 49.0–51.0 Hz |
| Extended frequency (30 min) | 47.5–49.0 / 51.0–51.5 Hz | 47.5–49.0 / 51.0–51.5 Hz |
| LFSM-O breakpoint | 50.20 Hz, 5% droop | 50.50 Hz, 4% droop |
| LFSM-U breakpoint | 49.80 Hz, 5% droop | 49.50 Hz, 4% droop |
| FSM band | 49.80–50.20 Hz | 49.50–50.50 Hz |
| RoCoF withstand | ± 2 Hz/s | ± 2 Hz/s |
| Phase jump withstand | 20° | 20° |
| OV-FRT | 1.20 Uc for 5s, 1.15 Uc for 60s | 1.20 Uc for 5s, 1.15 Uc for 60s |
| Voltage control (90%) | Within 1 second | Within 1 second |
| System protection levels | 5 levels: 70/50/40/10/0% | 5 levels: 70/50/40/10/0% |
Grid connection process
The compliance process for connecting a BESS to the Danish grid follows TR 3.3.1 Part 19. The relevant system operator (DSO or Energinet for transmission) manages the process.
Application
Before connection agreementSubmit facility information to the relevant system operator (DSO or Energinet): rated power (Pnl/Pno), usable energy storage capacity, storage medium details, and CE declaration of conformity.
Grid connection agreement
Before constructionAgree on connection point, rated power, reactive power requirements, protection settings, and signal exchange. Type D facilities require Energinet authorisation for automatic connection.
Simulation models (Type D)
Before commissioningType D facility owners must prepare and submit simulation models equivalent to those required for generation facilities under NC RfG and NC DC.
Compliance testing
Before commercial operationDemonstrate compliance through commissioning tests or simulations as agreed with the relevant system operator. Tests cover frequency response, reactive power, FRT, protection, and power quality.
Interim Operating Notification (ION)
After testingThe relevant system operator issues an ION once compliance is demonstrated. The facility may operate commercially while any remaining compliance items are resolved.
Final compliance
OngoingFacility must maintain compliance throughout its operational life. The DSO or Energinet may require changes to protection settings after commissioning.
Documents
Energinet publishes technical regulations and supplementary documents for grid-connected energy storage facilities.
Technical Regulation 3.3.1 — Revision 6 (PDF)
Full specification: 93 pages covering all type categories (A–D), synchronous and non-synchronous storage, frequency control, FRT, reactive power, protection, compliance testing, and grid connection procedure.
IEC 61850 Communication Deadline Extension
Energinet postpones the IEC 61850 communication protocol requirement originally set for 1 January 2026. Until Regulation 5.8.12 takes effect, TSO/DSO and facility owner agree on protocol.
Energinet — Electricity Rules, Conditions and Methods
Energinet's main page for all electricity technical regulations, grid connection rules, and regulatory framework.
Key stakeholders
Energinet (TSO)
Transmission system operator for Denmark. Sets technical regulations, manages transmission-connected facilities, and authorises Type D automatic connection. Operates both DK1 and DK2.
Electricity regulationsDSO (Distribution System Operator)
The relevant system operator for distribution-connected facilities. Coordinates protection settings, approves grid connection, and receives compliance test results. First point of contact for most BESS projects.
Facility Owner
Legally responsible for ensuring the energy storage facility meets all requirements. Must bear all compliance costs, provide facility information, and maintain compliance throughout operation.