A New Two-stage Photovoltaic GMPPT Method under Partially Shaded Conditions

In a photovoltaic (PV) system that consists of multiple series-connected PV modules with bypass diode, multiple peak points could exist in the P-V curve of the PV system under partially shaded conditions (PSC), causing conventional MPPT methods sometimes unable to track the true global maximum power point (GMPP). In view of this problem, we propose in this paper a new two-stage global maximum power point tracking (GMPPT) method based on the distribution characteristic of the GMPP voltage and the dividing point voltage. The method proposed finds all the possible peak power points and compares the power of those points to find the GMPP in the first stage. In the second stage, the method sets the operation point to the point of the maximum power found in the first stage and uses the hill climbing (HC) method to keep the operation point at that point. The method proposed is validated by simulation. Simulation result shows that this method can track the GMPP effectively.