Comparison of Predictive Direct Power Control Methods for Grid-Connected Converter in B4 Configuration

A model predictive direct power control of the three-phase converter with only four converter branches (B4) connected to an unbalanced grid is introduced. The developed infinite-control-set and usual finite-control-set MP DPC strategies are presented. The relations for predicted powers are developed in the form enabling analytical solution of the selected objective function for the infinite-control-set MP DPC. The alternative instantaneous non-active power theory is used, which preserves harmonic free grid currents not only for a symmetrical but also unsymmetrical voltage system. Simulation results for the L grid filter are presented, analyzed and compared for both the option of the MP DPC.