Multilevel converter system for photovoltaic panels

This paper presents a photovoltaic energy conversion project for the production of electricity to the electrical grid, using a multilevel converter, optimizing power transfer and improving the AC current form shape. Multilevel conversion is a topology which has some advantages over the 2-level topology, in particular it allows to work with higher voltage levels and improves the power quality. The neutral-point-clamped (NPC) multilevel converter uses capacitors to create the voltage levels that, in this project, will be used to connect the panels, thus optimizing power transfer. Control methods are applied to AC currents to have the alternating and sinusoidal waveform and to be in phase with the grid voltage, as well as to regulate DC voltage. The simulation (Matlab/Simulink) and experimental results (lab prototype) showed that the used control methods allowed to extract the photovoltaic power, where the state variables converge to its references, according to the solar irradiation and the panels temperature conditions.