An Improved HVRT Control Strategy for DFIG

This paper studies the high voltage ride through (HVRT) technology of the doubly fed induction generator (DFIG). Presently, traditional vector control strategies based on stator flux orientation (SFO) for rotor-side converter (RSC) always ignore the dynamic variation process of stator magnetizing current. This simplification will degrade the performance of DFIG during symmetrical voltage swells, which may even destroy the wind power systems. To mitigate this problem, an improved RSC control strategy considering flux linkage compensation is proposed to achieve high voltage ride through. The instantaneous stator flux linkage is used to replace the differential term of excitation current as feedforward compensation to reduce the influence of power grid voltage disturbance, which can have good transient and steady-state response during fault conditions. After that, the effectiveness of this method has been validated by MATLAB/SIMULINK. The results show that the improved RSC control strategy can not only provide enough reactive power for the recovery of grid voltage, but also effectively suppress the transient impact during the occurrence and elimination of faults. Thus, the HVRT capability of DFIG is improved.