THD Analysis of Modular Multi-level Converter with BESS

This paper proposes the selection of modulation strategies Phase shift pulse width modulation (PS-PWM) Level shift pulse width modulation (LS-PWM) through Total Harmonic Distortion (THD) analysis of Modular Multi-level Converter (MMC) with Battery Energy Storage System (BESS) system. The MMC-BESS system is delta-connected to the grid through a transformer in parallel, and the MMC-BESS Submodule (SM) is an existing MMC full-bridge SM with a DC/DC converter and a battery. It is a STATCOM structure with a battery that can act as an ESS. The THD of the modulation strategies PS-PWM and LS-PWM were compared by selecting different MMC SM levels and switching frequencies. The THD analysis was performed using MATLAB, and the MMC-BESS simulation was verified using PSCAD.