Comparison of the performance of maximum power point tracking schemes applied to single-stage grid-connected photovoltaic systems

This work presents a comparison of various maximum power point tracking (MPPT) techniques applied to 1-Phi, single-stage, grid-connected photovoltaic (PV) systems. A representative single-stage grid-connected PV system, based on buck-boost converter topology operating in discontinuous current mode (DCM) with sine-triangle pulse width modulation (SPWM) and feeding sinusoidal power into the grid, is considered for this study. MPPT techniques are compared on the basis of the time taken to reach (track) the MPP, operating point oscillations in the vicinity of MPP and the dependence of the algorithms, if any, on array configuration and parameters. Comparison is also made on the basis of the energy extracted from the PV source during the transient tracking phase. In this context, an energy tracking factor term (E_TF) is introduced and defined. It is observed that all the MPPT schemes studied have their own merits and demerits. The ripple correlation and beta methods offer an overall good combination of desirable features. All the results of this study are presented.