Robust adaptive integral backstepping control for MPPT and UPF of PV system connected to the grid

Abstract

This work deals with the nonlinear control of a single-phase photovoltaic (PV) system connected to the grid via an adaptation circuit and LCL filter is proposed. The main aim is the achievement of three control objectives: i) regulating the DC voltage to a desired value (Vdc*) ii) supply a current with sinusoidal form, in phase with the grid voltage and presents both low harmonic distortion and robustness in front of system's perturbations (Unite Power Factor: UPF) iii) extracting the maximum power from the PV array by acting on the DC/DC converter (MPPT). The control strategy is based on the robust integral Backstepping control design to be applied to the DC_DC converter and the DC_AC inverter in order to optimize the PV energy extraction and to achieve unity power factor. In order to improve the robustness and the stability of the nonlinear control, an integral action is introduced and Lyapunov analysis is used. Representative computer simulations demonstrate the performances of the control strategy to track the maximum power point of the photovoltaic array panel and synchronization of grid current with the grid voltage under various climatic conditions.