Virtual inertia emulation and RoCoF control of a microgrid with high renewable power penetration

Abstract

High renewable power (RP) penetration in a microgrid (MG) reduces the inertia of the MG. As a result, small load perturbation, or weather dependent fluctuations in RP generation, causes a high rate of change of frequency (RoCoF) and severe frequency instability problems. To cope with such issues, virtual inertia (VI) needs to be emulated in the MG for RoCoF and frequency control of a low-inertia MG. An MG consisting of thermal, wind, and solar photovoltaic power plants has been considered for the present study. In the proposed work, Genetic Algorithm (GA) optimized derivative-type VI control system has been designed considering both inertia and damping in the VI loop along with an energy storage device. The RoCoF and frequency responses of the MG using the proposed VI control strategy have been studied for variations in loads, weather dependent inputs, and MG parameters. Additionally, mathematical analysis has been provided to highlight the significance of adding a VI loop on steady-state stability and sensitivity of the MG. Furthermore, the performance of the proposed controller has been examined by comparing it with numerous pre-existing VI control topologies from recent literature for the same MG.