Research on the configuration strategy of active support long-and short-term energy storage devices based on ESD-considered short circuit ratio

Although the evaluation of system strength under high penetration of renewable energy sources (RESs) has been widely studied, traditional short-circuit ratio (SCR) indicators mainly focus on the interactions among RESs and are concentrated on steady-state research, neglecting the dynamic regulation effect of energy storage devices (ESDs) on system stability. In addition, most of the existing optimization methods aim to improve economic efficiency and lack system stability analysis based on SCR quantification. Therefore, this paper proposes an ESD-considered short-circuit ratio (ECSCR) that incorporates the contribution of ESDs to the short-circuit capacity of nodes. A bi-layer optimization strategy for the active support long-and short-term energy storage device is developed. The upper-layer optimizes the installation locations of ESDs by maximizing the minimum ECSCR (MinECSCR) on the RES buses, while the lower-layer uses the Newton-Raphson algorithm to dynamically adjust the power distribution of ESD to balance stability and economy. Specifically, when the ECSCR is less than the critical short-circuit ratio (CSCR), the fast-response flywheel energy storage (FES) and battery energy storage (BES) prioritize the restoration of stability; when the ECSCR is greater than the CSCR, the lower-cost thermal energy storage (TES) serves as the main power generation unit to minimize operating costs. The verification of the improved IEEE 9-bus, 39-bus system, and 14-bus system shows that compared with traditional SCR indicators, the proposed ECSCR can significantly enhance the nodal strength and reduce operating costs while ensuring system stability.