Harmonic distortion reduction in modular multilevel converters by novel mixed harmonic injection

Abstract

This paper proposes a novel modulation scheme to reduce the harmonic content of voltages and currents caused by modular multilevel converters with embedded battery cell when employed for application in battery energy storage systems in the grid. The reduction in total harmonic distortion (THD) is obtained by injecting selected harmonics in modulating wave for phase disposition sinusoidal pulse width modulation. The main innovation is in the frequency of these injected harmonics, most of which are kept considerably higher than the carrier frequency. The injection has further been improved using closed-loop control for optimum reduction in the harmonic content of output. The simulations are performed and tested on MATLAB-SIMULINK and demonstrate a satisfactory reduction in both voltage and current THD without any counter effect. © 2021 John Wiley & Sons Ltd.