Behavior of nine levels NPC three-phase inverter topology interfacing photovoltaic system to the medium electric grid under variable irradiance

To reach the increasing demand for power quality and power rating along with lower harmonic distortion and lesser electromagnetic interference, the multilevel inverter is needed. Solar energy is one of the favorable renewable energy resources, and the multilevel inverter has been proven to be one of the important enabling technologies in photovoltaic utilization. This paper is based on the study of behavior of a nine levels NPC three-phase inverter topology interfacing multistring photovoltaic system to the electric grid. This inverter is controlled by the pulse-width modulated strategy. Eight carrier waves of the same frequency and different amplitudes are compared with two references (a sine wave and its opposite) for generating the control signals of the switches. Some DC/DC boost converters are used to amplify the voltage produced by the photovoltaic generators. Each of these converters is controlled by a fuzzy Logic-based maximum power point tracking algorithm (FLBMPPTA) in order to track the maximum power point of the GPV; results of simulation in Matlab environment are given and discussed.