Constrained Predictive Control Based on a Large-Signal Model for a Three-Phase Inverter Connected to a Microgrid
Carlos Alfaro, Ramón Guzmán Solà, Luis García de Vicuña, Jaume Miret, Miguel Castilla
Abstract
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.