An Enhanced Framework for Sequence-Based Model Predictive Control applied to Grid-Tied Converters with LCL Filters

This paper presents a novel generalized framework for sequence-based Model Predictive Control (MPC) strategies applied to power converters. This work aims to generalize most of the existing strategies in the literature and consolidate them into a unified formulation. These strategies enable converters to operate at a constant switching frequency while generating a discrete grid current harmonic spectrum. Additionally, they retain the well–known advantages of MPC techniques, such as easy implementation, flexibility in control objectives, rapid dynamic response, and the ability to handle complex systems with multiple inputs and outputs (MIMO). Furthermore, the new formulation includes improvements that modify the state estimation model, obtaining more accurate predictions that lead to better control strategy performance. The proposed technique is applied to a case study involving a two-level converter connected to the grid through an LCL filter and is compared with the state–of–the-art sequence–based MPC strategies. Compared to the strategies in the literature and considering delay compensation, our proposal achieves a significant reduction in the grid current’s THD in all the study cases. It reaches a value of 3.76%, corresponding to a 50% reduction concerning the best strategy in the literature. In addition, the fast dynamic response of this type of control technique is maintained.