Control scheme of PV inverter under unbalanced grid voltage

The effective control of photovoltaic inverter under unbalanced grid voltages is very important for the grid-connected operation of the photovoltaic system. The calculation of the output current reference is a key technology in the control of photovoltaic inverter under unbalanced voltage. Base on instantaneous active-reactive control (IARC) and average active-reactive control (AARC), this paper proposed a flexible calculation method of current reference with a variable to reduce power fluctuation and current harmonics. In order to obtain a better dynamic performance, the proportional-resonant (PR) controller is used to control positive and negative sequence simultaneously in stationary frame. At last, the simulation results verify the validity of the proposed calculation method of current reference.