Evaluation of global MPPT for stand-alone PV system

Abstract

Under partial shading conditions (e.g., due to buildings, trees, and clouds), multiple peaks may exist on the power-voltage (P-V) characteristic curve of photovoltaic (PV) array, leading to the conventional maximum power point tracking methods fail to extract the global maximum power point (GMPP). To further complicate matters, most conventional Maximum Power Point Tracking methods develop errors under certain circumstances (for example, they detect the local Maximum Power Point (LMPP) instead of the global MPP) and reduce the efficiency of PV systems even further. Presently, much research has been undertaken to improve upon them. This work describes a new fast and efficient technique based on Particle Swarm Optimization (PSO), compared with the conventional technique Perturb and Observe (P&O) which is inadequate to track the GMPP subject to these conditions resulting in a dramatic reduction in the efficiency of the PV system. Simulations are performed in MATLAB/SIMULINK software. A system includes a DC-DC buck-boost converter to step up or down the voltage to required magnitude. P&O and PSO maximum power point tracking (MPPT) algorithms have been used to extract the possible maximum power point from the PV system. A DSP microcontroller is also used to control the duty cycle of the IGBT accompanied with this system. The results verify the accuracy of the proposed scheme. Also the results show that the proposed method has better characteristic and performance in compare with P&O methods.