Finite Control Set Model Predictive Control for Grid-Connected AC-DC Converters With LCL Filter

This paper presents two new implementations of finite control set model predictive control (FCSMPC) methods applied to ac-dc converters with an inductive. capacitive. inductive (LCL) filter. The LCL filter, despite its advantages, can cause a strong resonance in the grid current and also pose a substantially more complex control problem. The new solutions improve the FCS-MPC with an active damping algorithm by eliminating low-order grid current harmonics and decreasing sensitivity to grid voltage distortion. The new methods, i.e., PCi(1) i(2)u(c) and PCi(1) i(2)uc-2steps propose multivariable approaches using converterside current, line-side current, and capacitor voltage. Another improvement involves extending the prediction horizon in PCi(1) i(2)uc-2steps. Both methods have been tested and compared in steady and transient states as well as under grid voltage disturbances. The methods were also compared with a predictive control algorithm with active damping. The simulation results and experimental-measurements validate the developed control schemes and show high quality of grid current (low THDi value), high dynamic performance, and immunity under distorted grid voltage conditions.