Control strategy of BESS for providing both virtual inertia and primary frequency response in the Korean power system

As the battery energy storage system (BESS) has been considered to be a solution to the diminished performance of frequency response in the Korean power system, in which renewable energy resources (RESs) are expected to increase rapidly, this paper proposes a control strategy for providing both the virtual inertia and primary frequency response considering the MW-scale BESS installed by the Korea Electricity Power Corporation (KEPCO). The benefit of such a fast and flexible BESS can be maximized by the proposed control strategy for making it provide both the inertia and primary frequency response, which would be deficit with the increased RES. In the proposed control strategy, the state of charge (SOC) is maintained in the specific range in which the life cycle is maximized, the interference of SOC recovery by frequency control is minimized, the responding capacity for providing the virtual inertia response is maximized during the transient period, and the performance requirements for frequency response are satisfied. The effectiveness of the proposed strategy is verified by both Korean power system model-based simulation and on-site operations.