Control winding quantities orientation modeling and control for stand-alone brushless doubly-fed power generation system

Brushless Doubly-Fed Induction Generator (BDFIG) is potential for power generation applications for its high reliability and low maintenance-cost. There are two operation modes for BDFIG: grid-tied and stand-alone modes. The grid-tied mode usually uses the power winding (PW) synchronous and orientation frame since PW is connected to the grid; however in stand-alone mode, the PW is connected to the load rather than the grid, the control winding (CW) synchronous and orientation frame would be preferred. In order to improve the performance of stand-alone power generation system, this paper presents the CW synchronous frame model of BDFIG, and three kinds of orientation methods aiming to further simplify the BDFIG control are deduced and compared. Based on the derivations, the proper current inner-loop and voltage outer-loop structures (dual-loops) are also designed and compared. The experimental system based on one of the orientation methods is also built, and experimental results show the validity of the mathematical model and the adapted control structure.