Model of a 9-level transformerless RV Topology Grid-Tied-Inverter for PV applications

A 9-level Transformerless Grid-tied inverter is an electronic device especially designed to convert DC power into AC power, synchronized with the reference grid and capable to feed the surplus power of solar panels toward the grid. This paper presents a simulation model of a single-phase 9-level Grid-Tied-Inverter (GTI), implemented in the Matlab© software environment. The aim of this simulation model is to analyze the behavior of the 9-level reverse voltage topology and to design a filter to effectively reduce the ripple component injected into the grid to an acceptable value in order to reduce the total harmonics distortions (THD). The synchronization of the inverter to the reference grid is performed via a Phase Lock Loop (PLL). The focus is on developing a pure sine wave inverter that can synchronize with the grid in the shortest time possible and feed surplus power back into the grid.