Sizing of Energy Storage for Virtual Inertia Emulation and Primary Frequency Control in Low-Inertia Systems

High penetration of converter-interfaced renewable generation is leading to low-inertia systems from the interconnected power systems to micro-grids and isolated power systems. This paper proposes a new approach for virtual inertia emulation which eliminates the counteractive action of inertia. A frequency response model is also proposed which reduces the energy storage (ES) rating when inertia response (IR) and primary frequency response (PFR) are deployed. The region reduction iterative algorithm (RRIA) is used to size the ES power and energy ratings for PFR. The ES rating for IR is derived analytically. A case study of an Offshore Oil and Gas Platform (OOGP) in the North Sea, which is a typical low-inertia system, is presented. The results show that the new approach for inertia emulation reduces the ES rating when IR is deployed alone. Also, the results showed that the frequency response model is able to reduce the ES rating when using IR and PFR.