| Title |
Energy Balancing Control of Star-Connected Multilevel Converter using Injected Zero-Sequence Current |
| Authors |
Yeongung Kim ; Shenghui Cui ; Jae-Jung Jung |
| DOI |
https://doi.org/10.6113/TKPE.2024.29.2.106 |
| Keywords |
CHB(Cascaded H-bridge Converter); Cluster balancing; Leg balancing; STATCOM(Static Synchronous Compensator); Zero-sequence current injection |
| Abstract |
STATCOM systems are increasingly being integrated into the grid to enhance grid stability and power quality. Star-connected CHB converters are preferred for medium- and high-voltage STATCOM applications. One limitation of CHB converters is their inability to automatically balance three-phase unbalanced active power due to their distributed DC capacitors. Zero-sequence voltage injection is commonly employed to address this limitation. However, with increasing negative-sequence currents, the zero-sequence voltage can escalate to a point where it surpasses the maximum permissible output voltage, consequently restricting the system capacity for negative-sequence current compensation. In this paper, a cluster balancing control approach for the star-connected CHB converter was introduced to circumvent this challenge by utilizing a zigzag transformer to inject zero-sequence current. The effectiveness of the proposed method was verified through simulations and experimental results. |