Predictive direct power control of grid-connected voltage-sourced converters under unbalanced grid voltage conditions

This paper proposed a modified predictive direct power control (P-DPC) strategy for a grid-connected voltage-sourced converter under unbalanced grid voltage conditions. The proposed P-DPC strategy is implemented in the stationary reference frame without the necessity of either the space vector modulation or the synchronous speed d-q transformation. A compensation method is adopted in the conventional P-DPC to eliminate the negative sequence component of gird current for the purpose of obtaining the symmetrical and sinusoidal grid current under unbalanced grid voltage conditions. Positive and negative sequence components extraction is also avoided in the proposed method. Simulation results verified that the modified P-DPC strategy is effective to obtain symmetrical and sinusoidal grid currents under unbalanced grid voltage conditions.