A wind energy installation control device includes a wind rotor, a generator driven by the wind rotor, a torque control unit configured to control a torque of the generator, and a control system. The control system includes a detector configured to identify a grid dip and an end of the grid dip, a residual torque transmitter configured to provide a set point for a torque of the generator after identification of the grid dip, and an initializer configured to initialize a component of the torque control unit at the set point. Accordingly, upon return of grid power after a grid dip, the vibration behavior of a wind power system can be significantly improved. Overload of a drive train upon return of grid voltage can thus be reduced.