Predictive current control for utility interactive renewable energy systems in the face of weak utility grids

This paper presents a predictive current control method for utility interactive renewable energy system and its application to the weak utility grid. The grid voltage is estimated in the d-q frame using the current value and the filtered inverter voltage for the next sampling cycle. The method uses the discrete time model of the system to predict the value of the phase current at the next sampling interval and from that updating the current regulation accordingly. The simulation results of the new current regulation technique provide very good dynamic and steady state results than the PI current controller of the weak grid and the delay effect of the system. The controller performance is analyzed by observing the total harmonic distortion (THD) of the inverter output current in the grid connected (GC) mode.