Investigation on Perturbation Step-Size and Frequency of P&O Algorithm for MPPT under Dynamic Weather Conditions

This paper aims to analyze the influence of setting different perturbation step-size and frequency in Perturb and Observe (P&O) Maximum Power Point Tracking (MPPT) algorithm for photovoltaic (PV) systems. P&O algorithm is commonly used in commercial PV converters due to easy implementation, low computational burden and low cost. However, P&O MPPT algorithm suffers high steady-state oscillation around the maximum power point (MPP) and tracking confusion during rapid change in irradiance. This results in a considerable high energy loss and low tracking efficiency. Thus, this paper presents an improved method on how to determine a suitable perturbation step-size and frequency for P&O algorithm under dynamic weather conditions. Both static and dynamic MPPT efficiency were tested according to the European Standard 50530 (EN50530). A dc-dc single-ended primary inductor converter (SEPIC) is employed as an intermediate stage between the PV generator and the load. The tracking performance in terms of convergence speed toward MPP and the amplitude of oscillation around the MPP is investigated to observe the effect of different perturbation step-size and frequency.