A Hybrid ESS/Hydro Simulation Model to Meet FCR-D Requirements

Abstract

Abstract A hydropower plant (HPP) combined with a fast acting energy storage system (ESS) was modeled as a hybrid unit in Simulink. The main objective was to develop a control structure for the hybrid solution that fulfills the revised 2023 technical requirements for frequency containment reserve disturbance (FCR-D). A parallel control structure is proposed, where the HPP and ESS are controlled independently. The ESS is governed by a filter tuned according to the HPPs dynamic response. A drawback of this method is that the filter must be tuned based on the HPPs operating point where it has the slowest dynamic response. In practice, finding this operating point might be difficult due to system nonlinearities. The developed simulation model fulfills all technical requirements with margin. Additionally, the independent control structure allows the stability of the hybrid system to be improved by fine tuning the ESS filter, while still satisfying the time domain requirements. Both batteries and supercapacitors are evaluated for their suitability in the hybrid configuration. Their technological characteristics do not clearly favor one or the other, instead cost is the deciding factor. For the studied HPP, the lowest cost is achieved with a combination of the two technologies. However, the thesis does not assess whether the increased revenue from FCR-D participation offsets the ESS investment cost. The results suggest that the proposed hybrid solution can fulfill all FCR-D technical requirements and may enable HPPs that no longer meet the updated standards to remain active in the market. Nevertheless, due to increasing participation from other energy sources, implementing such a solution is not essential for maintaining sufficient FCR-D capacity in the future.