Power quality analysis of multilevel grid-interactive converter system with varying DC source and switching angle

Abstract

This paper aims to present the power quality analysis of Multilevel Inverter (MLI) phase controlled systems. The analysis is achieved by developing models for five-level MLI systems in continuous conduction mode. In this mode, the switching angle of the thyristor is varied in order that it can be operated in inversion mode. As compared to conventional line commutated DC-AC inverters which have higher order harmonics, the proposed MLI system has output with reduced higher order harmonics. In addition, the performance of proposed system has been tested at Resistance Inductance DC source (RLE) load, with changing DC voltage levels. Furthermore, the operation of proposed topology has been demonstrated under changing switching modes. It has been analyzed that the level of Total Harmonic Distortion (THD) is reduced whereas, the real output power is injected to utility-grid. Output waveforms with low harmonic content are desirable in MLI systems. The simulation models developed are well suited for practicing engineers, who are keen to their pursue studies in power quality, especially while integrating any renewable energy technology into the higher level MLI systems.