Y形链式STATCOM的相间电容电压平衡控制策略研究

摘要

Y形链式H桥形STATCOM在不对称运行工况下容易出现严重的直流侧电压不平衡问题,特别是各相之间的直流侧电压均衡控制非常困难.针对这个问题,在经典的分层控制策略的基础之上,重点针对Y形结构相间均压控制困难这一问题进行了深入分析和研究,提出了在不影响系统外部功率输出特性的前提下,通过注入零序电压分量的方法,使系统内部不平衡的功率可以在三相之间交换,确保各相的直流侧电压都能得到平衡.仿真试验证实了该控制方法的正确性和有效性.%The severe DC capacitor voltage imbalance easily occurs in Y-type cascaded H-bridge STATCOM under asymmetric operating condition,and it is difficult to implement DC side voltage balance control between phases. To address this problem,the paper is focused on the DC capacitor voltage balance control between phases for Y-type STATCOM based on the classic hierarchical control strategy,and proposes that the inner three-phase unbalanced power of the system can be balanced by injecting the zero-sequence voltage without affecting the external power output characteristics,ensuring the DC side voltage balance of each phase. The simulation results show that the proposed method is correct and effective.