Model Predictive Control for Parallel Connected Three-Phase Four-Leg Inverters in Islanded AC Microgrids

In this paper, a model predictive control (MPC) based primary control strategy is proposed for parallel three-phase four-leg inverters in islanded AC microgrids. To regulate the frequency and voltage in the AC microgrid, a cascaded control structure is used. The used structure consists of a droop control loop, a virtual impedance control loop, and the MPC based voltage control loop. Compared to traditional proportional integral (PI) based cascaded control, the proposed technique offers faster dynamic response and better steady state operation. The performance of the proposed control system is validated by hardware-in-the-loop (HIL) simulation studies.