Current control for the grid-connected single-phase photovoltaic inverter in microgrid based on an equivalent-input-disturbance approach

In this paper, a current controller based on equivalent-input-disturbance (EID) approach for the grid-connected single-phase photovoltaic inverter in microgrid is proposed. First, a signal generator is employed to generate the amplitude and the phase of reference current. The amplitude is calculated according to the data obtained from experiment devices, while the phase is regulated by a phase-locked loop (PLL). Then, a state-feedback controller and an internal model of the current controller are used to track the reference current, which ensures that the maximum power is transferred from DC side to AC side. Besides, the outside disturbances from the point of common coupling (PCC) such as voltage sag/swell are estimated by the voltage sag/swell estimator. Then, the equivalent disturbance is used to modify the amplitude of the reference current, which maintains the stable power flowing between the grid-connected photovoltaic inverter and the utility grid. Finally, the simulations results in MATLAB/Simulink verify the effectiveness of the proposed current controller.