Maximum Power Point Tracking for PV Array Under Partially Shaded Conditions

Solar photovoltaic (PV) array which is exposed to the uniform solar irradiance shows the non-linear P-V characteristic. Nevertheless, the P-V characteristic becomes more complex with multiple maximum power point (MPP) when the array is operated under partially shaded condition. Conventional maximum power point tracking (MPPT) approach which is designed to track the MPP will be trapped at the local MPP. Therefore, one of the challenges is to continuously track the absolute MPP while the environmental factors such as solar irradiation, PV temperature and partial shaded condition are rapidly changing. This paper presents a novel method of parallel tracking function to assist the on-line fuzzy logic perturb and observe (P&O) MPPT to continuously search beyond the trapped MPP operating voltage point. The information of PV array such as the operating voltage and the corresponding generation current are stored in the database. The characteristics of the shaded array can be estimated via simulation and the absolute MPP is identified via the tracking function. The simulation results show that the enhanced fuzzy logic P&O MPPT is capable of tracking the real absolute MPP during the partially shaded condition.