1. Study Committee C2
System operation and control
Paper C
New primary reserve requirements in the Nordic synchronous area – Designing the disturbance reserve
M. KUIVANIEMI1, N. MODIG2, R. ERIKSSON2
Fingrid Oyj1, Svenska kraftnät (Swedish National Grid)2
Motivation
Reduced inertia and availability of primary reserves challenges frequency stability during severe power imbalances
Current requirements on Frequency Containment Reserve for Disturbances (FCR-D) are not alone sufficient to guarantee frequency above load shedding threshold
Aim: Develop method to design requirements on FCR-D
Meet system needs in terms of dynamic response - frequency above 49.0 Hz during dimensioning incidents
Ensure closed loop stability
Locally testable, functional requirements
Nordic power system
4 countries – 4 TSOs
Kinetic energy 120–300 GWs
Load shedding Hz
Dimensioning incident MW
Load 20–70 GW
Performance requirement design
A large number of open and closed loop simulations with varying system and unit parameters are performed to find mapping between open and closed loop performance
Different requirement combinations are studied to find the one that in the best way captures unit performance from the system point of view
 Power and energy delivered in the open loop test are used to calculate unit's FCR-D capacity
𝐶 FCR−D = min 𝑃 5 s 𝑃 ref 5 s , 𝐸 5 s 𝐸 ref 5 s ,1 ∙ ∆𝑃 ss MW
Capacity scaling is allowed if closed loop stability is fulfilled
Approach
Two requirements
Stability The closed loop system must be stable and have large enough stability margin
Performance System level performance requirement is translated into unit level requirement on the open loop response of the unit
Frequency before capacity scaling
Frequency after capacity scaling
Nyquist plot
Conclusion
A method to design requirements on FCR-D based on system needs was developed
Locally testable requirements are put on the closed loop stability and the performance of the providers