The invention relates to a method for determining dynamic parameters associated with damping properties of a wind turbine. The method involves active excitation of tower oscillations by adjusting the pitch or rotor torque. After the active excitation, the parameters can be determined from the passive decay of the excited oscillations. Alternatively, the oscillations can be actively damped, so that the parameters can be determined from the active decay of the excited oscillations. The method for promoting oscillations may be triggered in response to different events or in response to predetermined times for determining the actual dynamic parameters.