Single-Phase Cascaded Grid Connected Multilevel Inverter for Interfacing Renewable Energy Sources With Microgrid

In this paper, a novel single-phase cascaded grid connected multilevel inverter (MLI) is proposed for feeding power to microgrid from renewable energy sources (RESs). The proposed inverter is capable of feeding power to microgrid with low total harmonic distortion (THD). The proposed inverter consists of two H bridge inverters connected in cascade, namely, upper and lower inverters. The upper inverter is fed from photovoltaic (PV) array through a DC–DC boost converter, whereas the lower inverter is fed from wind turbine (WT) coupled to permanent magnet synchronous generator (PMSG) through an uncontrolled rectifier and DC–DC boost converter. The upper inverter operates at high frequency, whereas the lower inverter operates at fundamental frequency. To extract maximum power from the WT and PV array, a sliding mode control based maximum power point tracker (MPPT) is used. The proposed inverter is connected to the single phase 230 V, 50 Hz grid, and the control algorithm is implemented in the SPARTAN 3A digital signal processor (DSP) board. The proposed inverter is simulated using matlab/simulink, and detailed experimental results are presented to show the efficacy of the proposed inverter under different environmental conditions.