Finite Control Set Model Predictive Control for LCL-Filter-Based Grid-Tied NPC Inverter

Recently, finite control set model predictive control (FCS-MPC) has been successfully used in the two-level grid-tied inverter with LCL filter. This method can be also adopted for the three-level inverter. However, the DC link capacitor voltages of three-level inverter need to be balanced. This paper presents a new implementation using FCS-MPC for a grid-connected neutral-point-clamped (NPC) inverter with LCL filter in stationary αβ frame, which is capable to balance the DC link capacitor voltages, damp the oscillation caused by the LCL filter, and generate a sinusoidal grid-injected current by adopting the multivariable control. Simulation model is built to verify the performance of the proposed modified control method under stiff and weak grid, distorted grid voltage and unbalanced grid voltages conditions.