Integrated Prequalification for Combined Delivery of Instantaneous and Primary Reserves in Germany

This paper proposes a unified prequalification framework for the combined provision of Instantaneous Reserve (IR) and Frequency Containment Reserve (FCR) in Germany. In accordance with the technical requirements defined by the VDE-FNN and the ENTSO-E System Operation Guideline, the framework facilitates joint procurement and enables simultaneous delivery of both services by a single energy asset. The methodology is validated through a defined dynamic test scenario and analytical verification of the applicable regulatory criteria. A 4.5 MW battery-based inverter operating as a Virtual Synchronous Machine is used as a case study, allocating 2 MW each for IR and FCR. Simulation results demonstrate that the system delivers 2 MW of IR within 1 s under a$2 \text{Hz} \mathrm{s}^{-1}$rate of change of frequency and achieves full FCR activation within 30 s, remaining within all regulatory tolerance bands. Furthermore, the results confirm that the IR and FCR power and energy contributions can be distinctly separated and verified, enabling flexible service activation strategies under operational and energy constraints. The proposed framework therefore supports coordinated reserve provision and enhanced frequency stability in future balancing markets.