Transient Stability Analysis and Enhancement for BDFIG Based Virtual Synchronous Control

The brushless doubly-fed induction generators (BDFIG) has a promising application prospect in wind power generation, owing to their durability, reliability and low maintenance cost. Implemented with virtual synchronous control (VSynC), the BDFIG-based wind turbines are capable of exhibiting inertial characteristics and providing frequency support to the power grid. However, when facing significant disturbances, the VSynC-based BDFIG may experience transient instability phenomenon. To solve this problem, the instability mechanism of the VSynC-based BDFIG is analyzed via the equal-area criterion. Then, the influence of key parameters on the transient stability of the system is explicitly clarified. Besides, an improved VSynC is proposed based on an expansive state observer to enhance the transient stability of BDFIG system. Finally, the accuracy of the theoretical analysis and the effectiveness of the proposed method have been validated through simulations.