Doubly Fed Induction Generators (DFIGs) are nowadays extensively used in variable speed wind power plants. Doubly fed induction generators (DFIG) offer many advantages such as reduced converter rating, low cost and reduced losses with an improved efficiency, easy implementation of power factor correction schemes, variable speed operation and four quadrants active and reactive power control capabilities. Due to variable speed operation total energy output is much more in case of DFIG based WECS so capacity utilization factor is improved and cost of per unit energy is reduced. But the main disadvantage of DFIG is that it is very sensitive to grid disturbance/fault, especially for the voltage dip. Since the doubly-fed induction generator (DFIG) has been widely used in wind energy conversion, the low voltage ride through (LVRT) technology of the DFIG has been investigated extensively in recent times. This paper focuses on the fault ride-through capability of doubly fed induction generator (DFIG) based WECSs Under three phase symmetrical fault. The paper also provides an overview on the interaction between variable-speed DFIG based WECSs and the power system subjected to three phase symmetrical fault. The Steady state behaviour under normal condition and dynamic behaviour of DFIG wind turbines during grid faults is simulated and assessed.