Abstract: The present invention relates to controlling a wind turbine with a scaled power coefficient where the scaled power coefficient is determined in an adjustment process. In particular is disclosed control of a wind turbine in a partial load operation mode based on a tip-speed ratio (TSR) tracking scheme which based on an estimated wind speed determines a power setpoint. The disclosed adjustment process comprises setting a scaled power coefficient as a predetermined power coefficient multiplied by a scaling factor; adding a time-varying perturbation signal to the power setpoint; determining a transfer function from the perturbation signal to a power error; evaluate the frequency response of the transfer function over a time period to determine the scaling factor which minimizes the gain of the transfer function; and setting the operating power coefficient as the scaled power coefficient.

Abstract: Techniques for controlling rotor speed of a wind turbine. One technique includes defining a system model describing resonance dynamics of a wind turbine component, such as a wind turbine tower, where the system model has a nonlinear input term, e.g. a periodic forcing term. A transform is applied to the system model to obtain a transformed model for response oscillation amplitude of the wind turbine component, where the transformed model has a linear input term. A wind turbine model describing dynamics of the wind turbine is then defined, and includes the transformed model. A model-based control algorithm, e.g. model predictive control, is applied using the wind turbine model to determine at least one control output, e.g. generator torque, and the control output is used to control rotor speed of the wind turbine.

Abstract: The invention provides a method for controlling rotor speed of a wind turbine. The method includes defining a system model describing resonance dynamics of a wind turbine component, such as a wind turbine tower, where the system model has a nonlinear input term, e.g. a periodic forcing term. The method includes applying a transform to the system model to obtain a transformed model for response oscillation amplitude of the wind turbine component, where the transformed model has a linear input term. The method includes defining a wind turbine model describing dynamics of the wind turbine, and including the transformed model. A model-based control algorithm, e.g. model predictive control, is applied using the wind turbine model to determine at least one control output, e.g. generator torque, and the control output is used to control rotor speed of the wind turbine.