Abstract: A method for determining a bending angle of a rotor blade of a wind turbine system includes step of reading in an acceleration signal which represents an acceleration of the rotor blade acting essentially perpendicularly with respect to a rotor plane. In addition, the method includes a step of determining the bending angle of the rotor blade of the wind turbine using the acceleration signal.

Abstract: The disclosure relates to a method for determining an estimated value for at least one measured variable of a wind turbine. The measured variable represents a bending torque on a blade root of a rotor blade of the wind turbine from a rotor plane. The method includes reading in the measured variable and an angle of attack for the rotor blade. The method further includes adapting a model, which simulates an estimated value of the measured variable on the basis of a modeling instruction for a relationship between the measured variable and the angle of attack. The model is adapted using the read-in measured variable and the read-in angle of attack. The method also includes providing the estimated value for the at least one measured variable using the model.