Nowadays stochastic occurrence of main grid disturbances (LVRT, FRT) leads to high level vibrational excitation of the drive train during operation of wind turbines. Regardless of the drivetrain design as a direct, hybrid or multi-stage geared one in this case high mechanical and electrical stresses should be expected. This voltage-induced stress resulting from the generator-load input function, in which the air gap torque of the generator changes with high dynamic rates. The momentum is sufficient to excite any significant natural frequencies of the above-mentioned power train variants and of all mechanically coupled systems, such as the rotor blades, main frames, nacelle and tower structures. The effects within the drivetrain are shown by simulation by means of a physically discretized torsional oscillator model of a typical multi-megawatt wind turbine with a conventional multi-stage gearbox and fast running DFIG drivetrain design. A general method for a controller setting will be discussed to handle these abormal grid side conditions. Using FOC for the DFIG-converter system electrical stress will be limited by the rotor current control.