Abstract:
Low-voltage ride through (LVRT) capability is one of the most critical performance indicators for grid connected wind turbines. In this paper, a crowbarless symmetrical LVRT method for brushless doubly fed induction generators (BDFIG) based on direct flux linkage tracking control is proposed. Based on the switch table, the method controls the amplitude and phase of the BDFIG control winding (CW) flux linkage by directly selecting the voltage space vector, so as to suppress the induced overvoltage rapidly, causing overcurrent in the CW during LVRT, while rapidly injecting dynamic reactive current into the grid to support voltage recovery. The method requires no coordinate transformation, with the advantages of simple system structure and quick flux dynamic response. The experimental results show that during the LVRT, active power recovery and reactive power dynamic response meet the relevant requirements of the Chinese national standard, and the CW current is effectively suppressed, which verifies the effectiveness of the proposed control strategy.