A fast MPPT algorithm for single stage grid-connected PV inverter

In this paper, the power coupling relationship between the PV array, the filtering capacitor, and the grid-connected PV inverter was analyzed. The P/V characteristic was categorized into three sections, the unstable area, the stable area, and the sliding-mode stable area, a judging criterion was given. Through theoretical and mathematical analysis, the periodic power coupling can be reflected by the capacitor voltage and its change in monotony. Based on the power decoupling of the capacitor in a power cycle, by precisely calculating the required power reference for the inverter in the following cycle, the MPPT process can be optimized. The proposed method is especially efficient during the MPPT dynamic process, i.e. during start-up or when solar radiation changes sharply. An experimental 180W prototype is designed for verification of the theoretical analysis.