Model predictive control of three-phase Voltage Source Rectifiers under unbalanced grid voltage conditions

A new indirect power control strategy based on Model Predictive Current Control (MPCC) for the three-phase Voltage Source Rectifiers (VSR) is proposed in this paper. The proposed strategy regulates the instantaneous AC-side power to ensure stable DC-side voltage under unbalanced gird voltage conditions while no Phase Locked Loop (PLL) or coordinate transformations are needed. This paper analyzes the influence of AC-side inductance on the reference currents, and deduces the direct relationship between the Grid-side current and the AC-side power with a basis of AC-side power mathematical model. To eliminate the impact of AC-side inductance on AC-side power and stabilize the AC-side power under the unbalanced input voltages, MPCC was utilized to regulate the grid-side current. Experiments on a VSR prototype were carried out to validate the effectiveness of the proposed strategy, and the results demonstrated that the ripple of DC-side voltage was reduced and the performance of VSR under unbalanced grid conditions was improved.