Switching-level simulation model of MMC-based back-to-back converter for HVDC application

Switching-level simulation model of MMC-based BTB (back-to-back) converter for HVDC (high voltage DC transmission) application is very important to analyze its operation and transient. However, switching-level simulation model for the actual MMC-based BTB converter is very difficult because it consists of more than 150 sub-modules for each arm. In this paper a switching-level simulation model for the 11-level MMC-based BTB converter was developed with PSCAD/EMTDC software. It has 12 sub-modules for the positive arm and another 12 sub-modules for the negative arm. The developed simulation model includes the DC-voltage balance algorithm, the circulating-current reduction algorithm, the harmonic reduction algorithm, and the redundancy operation algorithm. So, the developed simulation model can be utilized to design the MMC-based BTB converter and to develop its protection scheme.