Modified Beta Algorithm for GMPPT and Partial Shading Detection in Photovoltaic Systems

Abstract

When the photovoltaic (PV) string is under the partial shading condition (PSC), the conventional maximum power point tracking (MPPT) techniques may fail to track the global maximum power point (GMPP). Although some global MPPT (GMPPT) techniques have been proposed, they may overlook the GMPP and fail to detect the PSC occurrence. Therefore, a novel GMPPT technique is proposed in this paper by modifying the conventional beta method. The proposed technique is more accurate than the previous techniques since it can guarantee that all the peaks in the $\beta$ range and never overlook the GMPP. Furthermore, the proposed technique can inherently detect the PSC occurrence without setting any additional threshold parameters or periodical interruption, which is simpler and more effective. In order to verify the advantages of the proposed technique, a prototype with buck-boost converter was constructed. For a fair comparison, two popular GMPPT techniques were also implemented and tested in the same prototype under various scenarios. The performance improvement with the proposed technique for different PSCs has been validated by both simulation and experimental results.