An improved control method to suppress DC injection to the grid for grid-connected single-phase PV inverter with less harmonic distortion

摘要

The transformer-less Photovoltaic (PV) power inverters are mostly well-liked and exceedingly recommended for grid-connected PV power systems because of low cost, small size and high efficiency. Nevertheless, the injection of Direct Current (DC) is effectively involved in grid-connected PV inverters without isolating transformers. An improved and efficient control method is presented in the paper, which is mainly based on the scheme of putting an additional PI controller into feedback closed-loop control of grid-connected inverter's system, and the integrator is used to achieve zero steady-state error in the controller for suppressing the DC injection into the grid for grid-connected single-phase PV inverter with less total harmonic distortion. A simulation test is suitably designed and the results verify the feasibility, enhanced performance and improved efficiency of the proposed control method.