A novel power-increment based GMPPT algorithm for PV arrays under partial shading conditions

Abstract

Due to dust, structural interfering from surrounding buildings or trees, partial shading conditions (PSCs) are frequently occurred in photovoltaic (PV) arrays, which affects the generated power and system reliability significantly. Under PSCs, PV arrays exhibit multiple local maximum power points (LMPPs), which make the conventional maximum power point tracking (MPPT) algorithms difficult to quickly allocate the optimal operating point with the maximum output power. In order to solve this issue, a novel power-increment based global MPPT (GMPPT) algorithm is proposed by combining the voltage line, the load line, and the power line altogether in determining the tracking direction and the step size. The proposed algorithm retains the advantages of the conventional power incremental based GMPPT technique. Moreover, it can realize a successful convergence to the GMPP under any pattern of PSC, which is difficult to accomplish for some GMPPT algorithms. It simplifies the control implementation since it is not necessary to know exactly the internal connection of the PV array for the practical implementation of the algorithm. Furthermore, the proposed algorithm shows improved tracking speed and higher accuracy than other GMPPT techniques. It directly regulates the duty-cycle of the power interface rather than the output power command. Thus, the circuit design becomes easier. Finally, various partial shading scenarios are evaluated experimentally in order to validate the effectiveness of the proposed algorithm.