The main objective of this paper is to investigate the behaviour of Doubly-Fed Induction Generator (DFIG) under various grid disturbances. In order to study the dynamic response of DFIG, to emerge the faults' consequences, a model has been simulated in Matlab/Simulink. In addition, FFT analysis has been done to achieve fault diagnosis and identification. The disturbances that have been investigated are 1ϕ to ground, phase to phase and three phase short-circuit. Also, the model of DFIG has been simulated under asymmetrical voltage sag. In these cases DFIG has been operated under subsynchronous mode.