A novel control strategy for load converter of renewable energy under unbalanced loading

In this paper, a novel control strategy for the load converter supplying the unbalanced AC load in the renewable energy resources system is presented. This novel control strategy is implemented in the a-b-c coordinate, so reference-frame transformation from a-b-c coordinate to d-q-0 rotating coordinate and inverse transformation from d-q-0 rotating coordinate to a-b-c coordinate are not required which decreases the controller operation time comparing with conventional d-q-0 controller. The control algorithm results in balanced and sinusoidal load voltages under unbalanced AC loading. The unbalanced load is characterized in both the a-b-c and d-q-0 coordinates. Also, the mathematical model of the load converter in both a-b-c and d-q-0 coordinates is derived by using the average large signal model. Then, two control strategies for the load converter are presented. The first one uses the conventional d-q-0 controller to ensure the voltage and current regulation. The second one is this novel proposed control strategy based on the power conservation theory. The two control strategies have been applied to the reference voltages generation of the load converter. The performance of the load converter with these two control strategies is compared with each other. Simulation and experimental results show the validity and capability of the novel proposed control strategy.