지그재그 변압기를 이용한 스타 결선 멀티레벨 전력변환 시스템의 클러스터 에너지 균형제어

초록

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.

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