Parametric Control Design for Recovery of Fast Storage Systems after Virtual Inertia Provision

The increasing penetration of inertia-less Converter-Interfacted Distributed Renewable Energy Sources (CIDRES) and the gradual decommissioning of synchronous generators (SGs) jeopardizes the electric power systems stability. If CIDRES are properly controlled and equipped with Energy Storage Systems (ESS), they can provide ancillary services (AS) similarly to SGs. Namely, Fast ESS (FSS) can offer short-term AS, e.g., Virtual Inertia (VI). Despite the plethora of existing CIDRES/ESS control algorithms, little effort has been made to develop a proper Energy Recovery System (ERS) for FSS, to provide an almost ideal AS and to return its State of Charge (SoC) to a nominal steady state. An immediate SoC restoration of the FSS could cause further frequency deviations instead of properly restoring the frequency. Towards this, building upon previous work, this paper presents a parametric design for the control variables of a ERS considering a FSS. Specifically, a time delay is introduced between the VI provision and the SoC recovery. This delay and other control parameters are analytically formulated to allow the system operators decide user-defined parameters of the FSS ERS and avoid continuous frequency oscillations. The proposed control is validated via simulations in Simulink demonstrating its adequate performance.