A Three-Level Inverter-Based Model Predictive Control Design for Optimal Wind Energy Systems

Abstract

This paper introduces an innovative model predictive control strategy for a grid-connected wind energy system using a three-level inverter. The method features a command structure with a single DC/AC multilevel three-phase inverter, which significantly decreases the number of converters required, thereby reducing the system design costs in comparison to the traditional back-to-back configuration that requires both DC/AC and AC/DC converters. The inverter is modelled discretely at the synchronous reference frame with a discrete-time prediction for future direct and quadrature components of the grid current and DC-link capacitor voltages. The controller evaluates each possible switching state of the inverter with a cost function and chooses the state that minimizes this cost for realization during the next sampling period. The proposed approach is verified using a processor-in-the-loop methodology along with a software simulation. The results show that this approach optimizes wind power generation and enhances the energy quality injected into the grid, as indicated by the lower total harmonic distortion compared with previous methods.