A nonlinear integral sliding mode controller for optimizing the performance of a standalone PV system under partial shading conditions

Power generation from photovoltaic (PV) systems is strongly affected by partial shading conditions (PSC). Under PSC, the power–voltage characteristics of the PV system present several local maximum power points and a single global maximum power point, which complicates the extraction of the optimal operating point. Traditional maximum power point tracking algorithms have some limitations in the global maximum power point tracking (GMPPT). To overcome these limitations, this paper proposes a nonlinear integral sliding mode controller (ISMC) designed for GMPPT of a standalone PV system under PSC. This PV system is used to generate electricity for standalone sites via a boost converter. The PV system and the proposed control scheme were simulated in the MATLAB/Simulink environment. The performance of the proposed ISMC was compared to that of two conventional controllers, the Perturb and Observe algorithms, and the classic sliding mode controller in three PSC scenarios. The simulation results show that, in the three scenarios studied, the proposed ISMC improves the performance of the PV system under PCS in terms of reducing the chattering phenomenon and the dynamic response time. The ISMC also significantly reduces power overshoots during rapid variations in irradiation.