Iterative decremented step-size scanning-based MPPT algorithms for photovoltaic systems

Iterative decremented step-size scanning-based maximum power point tracking (MPPT) algorithms are presented in this paper. The change of partial shading conditions is a main problem in photovoltaic systems. Power curves of the systems will contain some local maximum power points, beside a global maximum power point. The curves also change depending on environmental climates, which affect the partial shading conditions. Three iterative scanning-based MPPT algorithms are proposed to solve the problem, i.e. decremented window scanning, peak bracketing (PB) method and PB with initial scanning. A photovoltaic system coupled with a DC/DC converter is modeled in SPICE for verification and simulation purposes. The simulation results have presented that, for some cases, those MPPT algorithms can find out effectively the global maximum power points of the considered photovoltaic system. They also required efficiently with relatively small number perturb-and- observe steps to reach global maximum power points.