Quantifying Stacked Benefits of an Battery Energy Storage System for Frequency Stabilization

Climate conscious policies created by jurisdictional governments have spurred the adoption of small and utility-scale renewable energy. Established technologies predominantly rely on wind and solar PV generation which are almost invariably interfaced via full scale inverters. As more inverter-based generation is interconnected, instantaneous energy production from conventional rotating generation reduces accordingly, and the system characteristics begin to reflect a behavior inherent to inverters, notably those of inertia and short-circuit. However, some inverter technologies can counter these effects and become a powerful resource in adapting to this new reality as well. This paper studies the addition of a utility-scale energy storage used to stabilize frequency of the Puerto Rico Island system. Dynamic simulations using PSSe suggest that where well-tuned and adequately operated, these inverters can arrest frequency and reduce rate of frequency change as well as increase frequency nadir, and subsequently reduce the occurrence and amount of load shedding events. Although the capabilities of grid-forming inverters have been demonstrated to be vastly superior, in very strong system locations, such as near major generation centers, inverters operating in either grid-forming or grid-following control modes can stabilize the system equally well.