Constrained Predictive Control Based on a Large-Signal Model for a Three-Phase Inverter Connected to a Microgrid

Small-signal models are mostly used to model and design inverter-dominated microgrids. Conversely, this article proposes a large-signal model for grid-forming inverters connected to a microgrid based on the active and reactive power dynamic equations. In this work, it is proposed to use this nonlinear model to develop a constrained predictive control for the inverters connected to a microgrid. The main features of this proposed control are follows: first, direct voltage control (in amplitude and frequency) is not necessary; second, stability is guaranteed under a wide range of line impedances (hence, the virtual impedance is not needed); third, the proposed control can operate with unbalanced and nonlinear loads. Moreover, a theoretical stability analysis is presented. Selected experimental results show that the proposed control operates satisfactorily in case of a load step change, a load imbalance, and nonlinear loads.

Automated summary

This article proposes a large-signal model and control method for microgrids. The model does not require direct voltage control and is able to maintain stability under different impedances and loads. Experimental results demonstrate satisfactory performance of the proposed control method in case of load variations and non-linear loads.