A GMPPT Algorithm for PV Systems Using Current Reference and P-I Curve Under Partial Shading Conditions

Abstract

Photo-voltaic (PV) system has non-linear relation between its output power and operating voltage. It is desired to extract maximum power from the PV system i.e. by operating at maximum power point all the time. Under partial shading conditions, the conventional maximum power point tracking algorithms can’t detect the global peak. A most efficient global maximum power point tracking (GMPPT) technique with less tracking time is required when the change in shading is more rapid. In this paper, a novel GMPPT algorithm is proposed which tracks the global peak using P-I curve, PV curve and I-V curve of the PV system taking current as reference. As the PV current varies with irradiation, the tracking time for the proposed algorithm is low under shading conditions. The tracking time is minimized by calculating $I_{min}$ and $V_{min}$. The knee point regions are estimated by detecting the change in voltage at every iteration. Each knee point region will have one peak point. The regions where global peak does not exist is discarded by adopting a novel current skipping technique. These techniques reduces the tracking time. MATLAB Simulink is used to evaluate the performance of the proposed algorithm for different shading patterns and the results shows that tracking time is less.