Research on Improved Perturbation and Observation Method of MPPT Used in Grid-connected Photovoltaic System

摘要

This paper introduces the Maximum Power Point Tracking(MPPT)algorithm used in grid-connected photovoltaic system. For the shortcomings of traditional Perturb and Observe (PO), this paper presents an improved method combining Open-Circuit Voltage and the PO with variable perturbation steps.The proposed algorithm takes different tracking measures according to working states of the system.In order to realize the stability of maximum power point (MPP), small perturbation is adopted around MPP to control tracking speed of the system. When in steady state, oscillation phenomenon will be effectively eliminated in the vicinity of MPP. As a result, it would enhance the utilization of solar energy and achieve MPPT system's performance.