Grid synchronization and maximum power point tracking for wind energy generation system with Brushless Doubly Fed Induction Generator

The vector control of the brushless doubly fed induction generator (BDFIG) was implemented in Matlab/Simulink/SymPowerSystems using a rotating reference frame fixed on the power winding flux. The control algorithms of the grid-side and control-side converters can regulate the active and reactive power independently. The measure of the power winding flux angle, realized using a phase locked loop (PLL), showed good performance during the system startup and has demonstrated a robust behavior under noisy voltage and current signals. A synchronization strategy is proposed that acts on the control-side converter current control loops to ensure the conditions for a smooth connection. Soft and fast synchronization is achieved at the minimum rotating speed. The simulation results of the dynamic performance of maximum power point tracking (MPPT) under speed mode control are presented.