A comprehensive LPF-droop control based on virtual impedance and matching power command switching in DFIG

This paper delves into the key issues faced by doubly fed induction generators (DFIGs) under voltage dip (VD) scenarios when employing LPF-droop control, including transient angle stability, reactive power compensation requirements, and overcurrent suppression. To address these challenges, an innovative LPF-droop control integrated with virtual impedance and matching power command switching is proposed. By designing a power command switching module, the power input value of the P-f branch is dynamically adjusted, effectively enhancing the transient angle stability of the control system. To strictly control overcurrent, a virtual impedance mechanism considering both converter tolerance and surge current verification is introduced, ensuring the safe operation of the DFIG and its converter during FRT. Furthermore, to accelerate the recovery of the DFIG stator voltage, while locking the Q-U branch, reactive current components are compensated in the current control loop, achieving maximized reactive power compensation under current limiting and unit capacity constraints. Finally, simulation results demonstrate that the proposed control strategy can effectively suppress the overcurrent phenomenon on the rotor side of DFIG during FRT processes. It also achieves rapid dynamic reactive power compensation, significantly accelerating grid voltage recovery and thereby comprehensively enhancing the FRT capability of DFIG.