| Title |
Improved Modulation Scheme for Medium Voltage Modular Multi-level Converter Operated in Nearest Level Control |
| Authors |
Do-Hyun Kim ; Jae-Hyuk Kim ; Byung-Moon Han |
| DOI |
https://doi.org/10.6113/TKPE/2017.22.4.285 |
| Keywords |
MMC(Modular Multi-level Converter) ; MVDC(Medium Voltage Direct Current) system ; NLC (Nearest Level Control) ; SM(Sub-Module) ; DC voltage balancing ; MI(Modulation Index) ; THD (Total Harmonic Distortion) |
| Abstract |
This paper proposes an improved modulation scheme for the medium voltage modular multi-level converter (MMC), which operates in the nearest level control and applies in the medium voltage direct current (MVDC) system. In the proposed modulation scheme, the offset (neutral-to-zero output) voltage is adjusted, with the phase voltage magnitude, thereby maintaining a constant value with N+1 level in the controllable modulation index (MI) range. In order to confirm the proposed scheme’s validity, computer simulations for the 22.9 kV ? 25 MVA MMC were performed with PSCAD/EMTDC, as well as hardware experiments for the 380 V ? 10 kVA MMC. The proposed modulation scheme offers to build a constant pole voltage regardless of the MI value, and to build a phase voltage with improved total harmonic distortion (THD). |