Novel Analytical Method for Dynamic Design of Renewable SSG SPC Unit to Mitigate Low-Frequency Electromechanical Oscillations

Abstract

Grid operators require grid-connected renewable generation units (RGUs) to provide specific dynamic features. Among those features, the RGUs must support the dynamic performance of the power grid as well as operate in such a way to ward off new issues in the power system. Recently, unfavorable oscillatory modes have appeared through the grid connection of RGUs due to their dynamic interaction with other classical components of the grid. Therefore, it is essential to develop a novel technique for the dynamic design of RGUs to mitigate such risky oscillations. In this article, a novel analytical method is proposed for dynamic tuning of a renewable static synchronous generation unit controlled by synchronous power controller (RSSG-SPC). The proposed method is based on the mathematical analysis of the derivative function of general damping ratio formula. The analytical results establish generalized solutions that cover all operation mode of the RSSG-SPC. Further on, the solutions are implemented into the dynamic model of the RSSG-SPC to obtain clear, accurate, and trustable criteria for tuning of the virtual damping and virtual inertia. The dynamic tuning aims toward avoiding new oscillations in the system as well as to mitigate the natural oscillations of the power grid. The proposed approach was used for stability enhancement in high penetrated generation area as well as to support synchronization between interconnected areas in a two-area Kundur system. The proposed method was validated through modal analysis, time domain simulations as well as real-time evaluations which ensured that the proposed approach is a reliable technique for dynamic design of RSSG-SPCs.