Hardware Implementation of Modular Multilevel Converter Prototype for HVDC Transmission System

Abstract

Due to its modularity, scalability and low power losses, the modular multilevel converter (MMC) is being considered as the most promising converter for high voltage direct current (HVDC) transmission system against conventional two-level and three-level voltage source converters (VSC). This paper presents hardware implementation of MMC labora-tory prototype for HVDC transmission system. The hardware prototype is made of MMC with four submodules (SM) per arm while the digital signal processor (DSP) used in the programming is Texas Instrument (TI) TMS320F28377D Dual-Core DelfinoTM Microcontroller board with the code written in code composer studio (CCS). The results of the experiment show that the MMC prototype exhibits improved quality of the AC side current with reduced harmonic distortion, improved quality of the output staircase voltage of nearly sinusoidal waveform, high efficiency, reduced electromagnetic interference (EMI) noise, and low switching frequency which are the major requirement of HVDC system that could not be achieved with the conventional two-level and three-level VSCs.