A new InC-based method for MPPT of PV array under partial shading conditions

Under uniform solar irradiation, the power-voltage (P-V) characteristic curve of a PV array has only one maximum power point (MPP) which is easily captured by traditional MPPT methods. However, under partial shading conditions (PSCs), the P-V characteristic curve has more than one MPP. One of them is called global maximum power point (GMPP) and the others are local maximum power points (LMPPs). The conventional MPPT methods can fail to capture the GMPP with a subsequent energy losses. This paper presents a proposed method that depends on the incremental conductance (InC) technique to track efficiently the GMPP under PSCs with small tracking time. The idea of the proposed method is to increase the duty cycle of the MPP tracking controller in steps, the corresponding array current and voltage are measured and the equality condition of InC and instantaneous conductances (IC) is checked. If the check is satisfied, the array voltage and current determine the local MPP. Then, the duty cycle is increased more and the procedure is repeated to determine the coming LMPPs and hence the GMPP is selected among the LMPPs. The proposed method is verified with simulation results using MATLAB/SIMULINK program at different solar irradiation levels and varying number of LMPPs. The proposed method tracks the GMPP faster than a previous method reported in the literature. Different from the previous method, the tracking time on using the proposed method doesn’t depend on the location of GMPP with respect to the LMPPs.