Source - EIFS 2018-2 Nätanslutning av generatorer

EIFS 2018:2 — Energimarknadsinspektionens föreskrifter om fastställande av generellt tillämpliga krav för nätanslutning av generatorer. Sweden’s national implementing regulation for RFG (EU 2016/631). Specifies the nationally determined parameter values that RFG leaves open for member states and NRAs to set for the Nordic synchronous area.

Document metadata

Summary

EIFS 2018:2 fills in the nationally variable parameters that RFG leaves to member states and NRAs — primarily frequency operating ranges, ramp rates by technology type, fault ride-through profiles, and FSM (Frequency Sensitive Mode) settings for the Nordic synchronous area. The regulation is structured in six chapters corresponding to generator type and capability category.

Key content

Chapter 3 — General requirements (all types)

Frequency operating ranges (§§ 1–2): All types A–D must remain connected within:

• 47.5–48.5 Hz: ≥ 30 minutes
• 48.5–49.0 Hz: ≥ 30 minutes
• 49.0–51.0 Hz: unlimited
• 51.0–51.5 Hz: ≥ 30 minutes

Rate of change of frequency (RoCoF) tolerance: ≥ 2.0 Hz/s, measured over 500 ms.

LFSM-O (overfrequency response, §§ 3–6): All types must reduce active power output when frequency exceeds 50.5 Hz. Droop setting (statikfaktor): primary setting 8 %. Automatic disconnection is prohibited as an alternative to power reduction.

LFSM-U (underfrequency response, §§ 20–22): Types C and D must also increase active power output when frequency drops below 49.5 Hz.

Reconnection rules (§§ 8–9): Types A–C may reconnect automatically when frequency is within 47.5–50.1 Hz, provided the frequency has been within this band for ≥ 3 consecutive minutes. Reconnection ramp: max 10 % of nominal output per minute at 49.9–50.1 Hz.

Chapter 3 — Ramp rates by technology (§§ 31–32)

Ramp rates for Type C and D generators (active power control per §19):

The 100 %/min ramp rate for kraftparksmoduler (wind, solar, batteries) is the highest in the table by a significant margin. This reflects that power electronics enable essentially instantaneous power adjustment, limited only by converter design and grid stability considerations rather than mechanical or thermal constraints. This underpins the flexibility value of battery storage and controllable wind/solar in fast-response services.

Step-change response for kraftparksmoduler: 30 % within 15 seconds (§32).

Chapter 3 — FSM (Frequency Sensitive Mode, §§ 23–29)

FSM (frekvenskänslighetsläge) applies to Type C and D only:

• Capability is mandatory for Type C/D generators.
• Activation is TSO-controlled: “FSM ska endast vara aktiverat om den systemansvariga myndigheten beordrar det” (§23). Svenska kraftnät (Svk) decides when FSM is engaged; it is not a continuous operating requirement.
• Droop range: 2–12 % statikfaktor (§24).
• Frequency insensitivity: ≤ 10 mHz (§25).
• Deadband: ±100 mHz by default (§26).
• Active power range for FSM: 5–10 % of max continuous power (§27).
• Duration of full response: ≥ 15 minutes (§28).
• Response delay (for inertia-free generators, i.e. kraftparksmoduler): < 2 seconds (§29).

The TSO-activation condition means that kraftparksmoduler and other Type C/D generators have FSM capability but are only used for primary frequency regulation when Svk explicitly engages it — typically through FCR market participation agreements (Balancing Markets).

Chapter 3 — Fault ride-through (§§ 11–16, 35–40)

Fault ride-through (feltålighet) parameters define how generators must behave during and after voltage dips caused by grid faults. Different profiles for synchronous generators vs. kraftparksmoduler:

Kraftparksmodul Type B/C fault ride-through: Minimum voltage during fault: 0.15 p.u. (more lenient than synchronous generators which must hold 0.25 p.u.). Recovery to 0.85 p.u. within 2 seconds; full recovery to 0.90 p.u. assumed within 10 seconds.

Kraftparksmodul Type D fault ride-through: Even more demanding — must ride through 0.0 p.u. (complete voltage collapse) for up to 200 ms, recovering to 0.85 p.u. within 2 seconds.

Chapter 4 — Synchronous generator requirements

Voltage regulation, magnetisation, and power system stabiliser (PSS) requirements for synchronous machines. Types B–D require automatic voltage regulators. Types C–D must provide reactive power (≥ 1/3 of instantaneous active power for generation, ≥ 1/6 for consumption) within 90–105 % voltage range. Type D generators > 75 MVA require PSS (kraftsystemstabilisator) for damping power oscillations at 0.25–1 Hz.

Chapter 5 — Power park module requirements

Active power recovery for kraftparksmoduler after fault: within 2 seconds of voltage recovering above 90 %, active power must return to within 5 % of pre-fault level (§1). Types C/D require reactive power capability equal to synchronous generators.

Chapter 6 — Offshore requirements

Offshore kraftparksmoduler (types A–D) connected at 300–400 kV must operate for ≥ 60 minutes in the 105–110 % voltage range, and must provide reactive power (generation and absorption) equal to 1/3 of instantaneous active power.

Relevance to wiki topics