Circulating Current Suppression Strategy for Parallel Matrix Converters

With the annual increase of the installed capacity of new energy power generation systems, the parallel matrix converter system has become one of the hotspots in current research. However, due to the discrepancy of line impedances, conventional droop control cannot achieve reasonable reactive power sharing according to the droop coefficient, thus leading to the circulating current between the parallel converters. In order to solve the problem caused by the difference of line parameters in the parallel matrix converter system, this paper proposes a circulating current suppression strategy with improved virtual impedance, introducing the voltage compensation generated by the virtual impedance in the voltage control link, and taking the synthesis of circulating current and load current sharing error as the feedback, so as to form the equivalent virtual impedance to correct the reactive power allocation and suppress the circulating current of the parallel system. The simulation results show that the proposed strategy improves the reactive power allocation accuracy, reduces the voltage deviation, inhibits the circulating current between the parallel converters, and realizes the friendly interconnection of multiple machines.