A Three-Phase Nine-Level MLI for Grid-Tied AC Microgrid with Synchronverter Control

Due to the high penetration of Green Energy Power Generation (GEPG), such as PV-Solar, wind, etc., the power system has evolved from a conventional power generation system to an inverter-based system. Distributed Generation (DG) could run as a grid-tied or an islanding system. The synchronization of the grid-tied Multilevel Inverter (MLI) in a DG system is significantly influenced by the uncertainty of the grid at the Point of Common Coupling (PCC). When using an efficient grid MLI control strategy, grid-connected AC microgrids may sustain optimum performance at the PCC. In this paper, the control approach for a grid-integrated, 3-phase, 9-level MLI using a synchronverter control technique is presented. The presented asymmetrical MLI configuration comprises the polarity and level generation units along with 3:1 ratio DC source input. This paper presents the mathematical modeling and control design of a synchronverter. A 15-kVA, three-phase, nine-level MLI grid-tied simulation model is developed in MATLAB/Simulink. The robustness and effectiveness of controller with MLI are tested under various conditions, including steady-state and dynamic scenarios such as instantaneous changes in available powers at the DC end (i.e., P
ref
, Q
ref
) and variations in loads (i.e., P
load
, Q
load
).