Adaptive controller design for grid current regulation of a CSI based PV system

A nonlinear adaptive controller for regulating the grid of a current source inverter (CSI) based three-phase grid-connected photovoltaic (PV) system is proposed in this paper. The proposed control structure is composed of an outer current loop which is responsible for controlling the DC-side inductor current and the inner current control loop is responsible for controlling injected current into the grid. The proposed controller is designed recursively by considering some parameters of the system parameters as unknown and these unknown parameters are estimated through the adaption laws. In order to prove the overall stability of the whole system control Lyapunov functions (CLFs) are formulated at different stages of the design process. Finally, the effectiveness of the proposed control scheme is tested on a CSI based three-phase grid-connected PV system under different atmospheric conditions. Simulation results show that the proposed control scheme can effectively meet the desired control objectives.