Diminution of THD Level for a Tansformerless Grid-Connected PV Using Multi-Level Hybrid Inverter

Renewable energy is a recent trend used for generating the electricity due to its availability, High efficient and cheaper etc. Power electronics devices have become more advantageous in last three decades for grid utility. Multi-Level Inverter (MLI) is also used in grid applications to reduce the Harmonics caused by non-linear load, and it is necessary to diminish the Harmonics which is an important power quality problem in grid utility. This paper presents a Single-Phase Transformless Grid-connected PV system with Hybrid Multi-Level inverter with different DC source to diminish the Harmonics. This inverter has 2 asymmetrical Cascade Full Bridge whereas one is supplied by PV system and other is supplied by flying capacitor. Thus this inverter’s output reduces harmonics and Electromagnetic Interferences by increasing its stepped output levels. The Phase Opposite Disposition-PWM (POD-PWM) switching strategy is employed to regulate the flying capacitor, and improve efficiency by reducing the THD (Total Harmonics Distortion) level. In this work, the Grid connected PV system with Multi-Level inverter is obtained by interconnecting the Hybrid Multi-level inverter, POD-PWM with solar system and load. Simulation using MATLAB/Simulink software confirms the feasibility and good performance of the proposed inverter and the PWM strategy.
Finally this work reduced the THD level to 5% with±tolerance as per the IEEE standard by using grid-connected PV system with Hybrid Multi-Level inverter and POD-PWM.