An optimal method for designing the controllers used in grid-connected PV systems

As the fast development of grid-connected solar photovoltaic (PV) power supplies in recent years, the grid-connected voltage source converters (VSCs) are being considered as prime candidates for interfacing these resources to power network. In order to better meet the grid code, the control scheme of the converter becomes crucial. Currently the voltage-oriented control strategy is widely utilized. But for the control scheme it is difficult to obtain the optimal PI parameters. In this paper, a novel design method to obtain optimal parameters of two current proportional-integral (PI) controllers and a voltage PI controller is proposed so as to fulfilling the requirements, which have the characteristic of rapid dynamics, low harmonic distortion, and superior disturbance rejection capability. Meanwhile, the method can be useful for the PI controllers of the wind power generation system. Based on real time digital simulator, the performance of the controllers designed by the presented method is experimentally evaluated.