Novel DC-link voltage regulation and seamless transfer control strategy of a battery-based microgrid system

Abstract

The main challenge of modern microgrids (MGs) is the capability to operate in either grid-connected mode (GC) or islanding (IS) mode with DC-link voltage regulation for all the utilized parallel-connected DC-AC converters in the MG during all operating modes and, at the same time, is capable of transferring seamlessly between these two operating modes. This paper suggests a novel control strategy capable of operating a battery-based MG system in each of the GC and the IS modes and, at the same time, seamlessly transferring it between these two operating modes. A PQ controller is utilized to realize the GC operation, whereas a V/f controller is used for the IS operation. The smooth transfer between the two modes is accomplished by minimizing the transient variations in the MG voltage, current, frequency and phase at the point of common coupling (PCC). Additionally, the suggested strategy is qualified to deliver a novel regulation and a transient-free transition for the DC-link voltage of the used bi-directional DC-AC converter of the considered battery-based MG system. Therefore, the suggested control strategy can potentially improve the reliability of the considered battery-based MG system. The considered battery-based MG system is simulated and controlled by utilizing MATLAB/Simulink. The simulation results demonstrate that the suggested control strategy can effectively act during the operation of the considered battery-based MG system, either in the GC mode or the IS mode, and it can also effectively control the transitions between the two operating modes.