The non ideality effect of optimizing the P&O MPPT algorithm for PV stand-alone applications

Maximum power point tracking (MPPT) techniques are used in photovoltaic (PV) systems to maximize the PV array output power by tracking continuously the maximum power point (MPP) which depends on panel´s temperature and irradiance conditions. The Perturb and Observe (P&O) MPPT algorithm is the most commonly used method due to its ease of implementation. But it has some drawbacks such as the oscillation of the operating point around the MPP at steady state which wastes some of the available energy. Also, the P&O algorithm can be confused by rapidly changing atmospheric conditions. In this paper, the P&O MPPT parameters have been optimized to the dynamic behavior of the PV system to limit the negative effects of the above drawbacks. Theoretical analysis has been performed using non-ideal dc-dc converter with resistive load. The optimal values of two main P&O algorithm parameters are determined, the amplitude of the duty cycle perturbation and the sampling interval. Also, the study is compared with the analysis of the ideal dc-dc converter to clarify the effect of non-ideality on the parameters design. Finally, both simulation and experimental results are presented as confirmation of the theoretical analysis.