Finland — Grid Code for Energy Storage
Fingrid's grid code framework for battery energy storage systems connected to the Finnish transmission and distribution network. The primary specification is SJV2024, supported by complementary documents covering modelling, cybersecurity, and stability studies.
What makes SJV2024 different
Grid-forming is mandatory
All new BESS must operate in grid-forming mode at all times — not configurable, not optional. Finland is one of the first countries in Europe to require this.
Zero-voltage FRT for Type D
Type D systems must ride through 0.00 pu for 200 ms. Type B/C ride through 0.05 pu for 150 ms. Among the most demanding FRT profiles in Europe.
RoCoF relays banned (Type C/D)
Rate-of-change-of-frequency protection relays are explicitly prohibited for Type C and D. Only allowed for Type A/B with ≥ 4 Hz/s threshold.
16 commissioning tests
Type C/D systems must pass 16 on-site tests with ≥ 90% of converters operational — covering LFSM, FSM, voltage control, FRT, island detection, and more. One of the most extensive test programs in Europe.
Type categories (SJV2024 Table 3.1)
Most utility-scale BESS projects in Finland fall under Type C or D. SJV2024 focuses on these categories.
Main specification
SJV2024 — Grid Code Specifications for Grid Energy Storage Systems
161 requirements across 15 categories: operating ranges, FRT, grid-forming, active/reactive power control, protection, SCADA interfaces, commissioning tests, and simulation models.
Grid connection process
The compliance process for connecting a BESS to the Finnish grid follows a staged approach. Each stage shows the documents you need at that point.
Stage 0 — Preliminary planning
Before connection agreementComplete the Stage 0 questionnaire. Provide preliminary technical data, site layout, and planned capacity to Fingrid and the relevant network operator (RNO).
Stage 1 — Connection agreement
Before connection agreementDeliver detailed technical data, reactive power capacity calculation, and preliminary simulation models (PSS/E + PSCAD).
Dynamic studies
6 months before first power supplyPrepare and submit dynamic study results and simulation models to RNO and Fingrid. Covers voltage disturbance, constant voltage control, vector shift, island operation, and impedance scan.
Test plan
2 months before commissioningSubmit test plan, preliminary instructions, and practical arrangements for commissioning tests.
Commissioning
Before commercial operationExecute 16 commissioning tests (Type C/D) with ≥ 90% of converters operational. Tests cover LFSM, FSM, voltage control, reactive power, FRT, island mode, and more.
Model verification
After commissioningCompare simulation results against commissioning test data. Deliver verification report and update models if needed.
Complementary documents
Fingrid publishes supplementary documents that apply alongside SJV2024. These cover modelling deliverables, cybersecurity requirements, and grid stability studies.
Stage 0 Questionnaire (SJV2024)
Excel questionnaire for preliminary planning. Entry point for the grid connection process — required information before Stage 1.
Cybersecurity Survey
Mandatory questionnaire for B/C/D type power plants and energy storage systems. Required before interim operational notice and after commissioning for C and D types.
Application of Modelling Instructions
Governs all modelling project submissions for C and D type facilities. Defines when and how simulation models must be delivered to Fingrid.
PSS/E Modelling Instruction
Power system simulation model specifications. Required for steady-state and dynamic analysis of grid-connected BESS.
PSCAD Modelling Instruction
Electromagnetic transient simulation requirements. Required for detailed converter-level transient analysis.
ESCR & Voltage Control Guidance
White paper on using the Effective Short-Circuit Ratio approach for assessing converter-driven stability and tuning voltage controllers.
SSO Study Requirements
Specific study requirements for power park modules related to subsynchronous oscillation risk in series-compensated networks.
Key stakeholders
Fingrid (TSO)
Sets grid code specifications. Receives dynamic studies, reviews simulation models, and may attend commissioning tests for Type D systems.
Grid connection processRNO (Relevant Network Operator)
The DSO or TSO at the connection point. Coordinates protection settings, approves test plans, and receives commissioning results. First point of contact for most compliance steps.
RO (Relevant Operator)
Designated by the asset owner to operate the BESS. Responsible for 24/7 availability, remote control interfaces, SCADA signals, and reporting status information to Fingrid.