Double fed induction generators (DFIG) for wind turbines are very sensitive to grid disturbances especially voltage dips. Understanding and improving fault-ride-through (FRT) capacity of wind turbine generators (WTG) demands accurate assessment of the impact of voltage dips. In many FRT requirements, only voltage dip magnitude and duration are considered. However, additional characteristics point-on-wave (POW) and phase-angle-jump (PAJ) have great impact on DFIG. This paper aims to study the behavior of DFIG-based WTGs during various types of voltage dips. PAJ and POW are specifically taken into consideration; intensive simulation tests show that their impact is significant and should be included in FRT studies. Theorical analysis are also provided to explain the mechanism behind the observed phenomena. And conclusions of paper could be used to provide useful information for FRT related works and other applications.