Exploring a Modulation Strategy by Experiments for Modular Multilevel Converter in Faulty Operation

Abstract

Modular Multilevel Converter (MMC) technology is rapidly evolving, and research is ongoing to make the MMC suitable for more applications. This topology comprises multiple Sub-Modules (SM) to form the output voltage levels with lower order harmonic contributions. In this paper, a reconfiguration control method for continuous operation during bypassed faulty SM is presented. The method accomplish to keep the same line-to-line voltage as in steady-state condition without deterioration of modulation index. A level-shifted modulation scheme and capacitor voltage balancing algorithm for a 6-level MMC converter are simulated and experimentally validated through Hardware-In-the-Loop (HIL) platform.