Comparison of fixed speed and doubly-fed induction wind turbines during power system disturbances; Comparison of the weak grid dynamic behavior by the WECS connection of different power; Investigation of faults in autonomous wind-diesel hybrid energy system by simulation; Investigation of the three phase short circuit in a weak power system including WECS; Mathematical Model of an Asynchronous Generator Taking the Iron Losses into Account; Mathematical modeling of an asynchronous switched generator;