Based on Vector Proportional Integral (VPI) Control of Brushless Doubly Fed Induction Generator under Load Imbalance

Compared with the doubly-fed induction generator (DFIG), the brushless doubly-fed induction generator (BDFIG) with the high reliability and low maintenance cost due to the cancellation of slip rings and brushes, having broad application prospects. The diversity and complexity of the load in the power generation system greatly cause the load imbalance when the system operations under stand-alone mode, resulting in the decrease of the system stability. This paper presents the vector proportional integral (VPI) strategy for imbalance problems of BDFIG. First, the positive and negative sequence current inner-loop and voltage outer-loop are obtained in their respective coordinate systems when load imbalance faults occur; Second, the vector proportional integral control is analyzed and designed in detail for compensating the load imbalance faults; Finally, the negative sequence component can be suppressed by the VPI control in order to achieve the balance control of output voltage when the load imbalance faults occur, which will significantly improve the stability of the system.