Dynamic Maximum Power Point Tracking Method including Detection of Varying Partial Shading Conditions for Photovoltaic Systems

Photovoltaic (PV) systems, being one of the promising power generation systems, need performance optimization typically under partial shading conditions (PSCs). In such non-uniform irradiation conditions, not only conventional maximum power point tracking (MPPT) algorithms but also advanced techniques fail in operating at the power peak. So, global maximum power point tracking (GMPPT) methods are needed when several local maximum power points exist under PSCs. The major difficulty is not in detecting the GMPP but in finding the new one when the PSCs change. Consequently, the challenge becomes in detecting the variation of PSCs. The proposed method relies on monitoring the rate change on power at the output of the PV panel. Proving that this criterion alone is not accurate, a measurement Q is introduced and used as a watchdog for critical partially shaded cases. When in such case, a timer alternates between a scanning process and a dual-mode MPPT method based on perturb and observe (P&O) and constant voltage algorithms. Otherwise, the MPPT work in not interrupted unless a drastic power change takes place. The proposed algorithm proved its efficiency in all partially shaded irradiation conditions when implemented in a MATLAB/Simulink environment. Furthermore, it is compared to other partial shading detection (PSD) methods to verify the algorithm's performance in a generic case.