In order to improve the voltage sag ability of doubly fed induction generator(DFIG) and its control system and to realize the low voltage ride-through(LVRT) function of DFIG
this paper analyzes the math model and focuses on the time when voltage sag happens
and the electromagnetic transition process with different voltage phase angle.On this basis we give the mechanism and characteristics of voltage sag and according to the qualitative analysis of different voltage phase angles give a method of ...