When the rotor-side converter (RSC) in the doubly-fed wind power generation system adopts the threelevel structure, the neutral point voltage (NPV) is diffcult to balance. In this video, two types of average neutral point current (NPC) models in the three-level converter (TLC) are summarized. Symmetric SVPWM and virtual SVPWM based on space vector are analyzed. CBPWM with zerosequence voltage injection and changing duty ratio CBPWM (CDR-CBPWM) based on carrier wave are investigated. CDRCBPWM is simplified for application. The effects of symmetric SVPWM and simplified CDR-CBPWM applied to RSC are compared through simulation.
Comparison of Different Neutral Point Balance Strategies Applied to Three-Level DFIG System Pengcheng Dai; Zhen Xie; Chao Wang; Xing Zhang