Wind turbine control

A method for controlling a wind turbine comprising:

• receiving a wind direction signal indicative of an instantaneous wind direction at the wind turbine;
• receiving one or more signals indicative of an instantaneous wind speed at the wind turbine;
• determining a rate of change of the wind direction at the wind turbine and a rate of change of wind speed at the wind turbine;
• determining one or more control signals for a pitch system for blades of the wind turbine at least partially based on the rate of change of the wind direction and the rate of change of wind speed;
• changing the pitch of the blades with the pitch system based on the control signals to reduce loads on the wind turbine from changes in the wind direction simultaneous with changes in the wind speed;
• wherein the control signals include a setpoint for the pitch system based on a comparison between an indicated maximum load for the blades of the wind turbine and a measured load on one or more of the blades;
• and
• wherein the setpoint for the pitch system is determined based on a comparison between a bending moment on one or more of the blades and a maximum bending threshold.

A control system for a wind turbine, the control system configured to:

• receive a wind direction signal indicative of an instantaneous wind direction at a wind turbine;
• receive one or more signals indicative of an instantaneous wind speed at the wind turbine;
• determine a rate of change of the wind direction at the wind turbine and a rate of change of wind speed at the wind turbine;
• determine one or more control signals for a pitch system for blades of the wind turbine based on the rate of change of the wind direction and the rate of change of the wind speed;
• and
• change the pitch of the blades with the pitch system based on the control signals to reduce loads on the wind turbine from changes in the wind direction simultaneous with changes in the wind speed.

A control system for a wind turbine, the control system configured to:

• receive a wind direction signal indicative of an instantaneous wind direction at a wind turbine;
• receive one or more signals indicative of an instantaneous wind speed at the wind turbine;
• determine a rate of change of the wind direction at the wind turbine and a rate of change of wind speed at the wind turbine;
• determine one or more control signals for a pitch system for blades of the wind turbine based on the rate of change of the wind direction and the rate of change of the wind speed;
• and
• change the pitch of the blades with the pitch system based on the control signals to reduce loads on the wind turbine from changes in the wind direction simultaneous with changes in the wind speed;
• wherein the control signals include a setpoint for the pitch system based on a comparison between an indicated maximum load for the blades of the wind turbine and a measured load on one or more of the blades;
• and
• wherein the setpoint for the pitch system is determined based on a comparison between a bending moment on one or more of the blades and a maximum bending moment threshold, wherein the maximum bending moment threshold is determined as a function of the rate of change of the wind direction and the rate of change of the wind speed.

A method for operating a wind turbine, comprising:

• measuring a wind direction at a wind turbine and determining a rate of change of the wind direction at the wind turbine;
• determining a rate of change of a wind speed or rotor speed at the wind turbine;
• reducing loads on the wind turbine when the rate of change of the wind speed or rotor speed is above an acceleration threshold;
• wherein the acceleration threshold is based at least partially on the rate of change of the wind direction such that the loads on the wind turbine from changes in the wind direction acting simultaneously with changes in the wind speed are reduced.

A method for operating a wind turbine, comprising:

• measuring a wind direction at a wind turbine and determining a rate of change of the wind direction at the wind turbine;
• determining a rate of change of a wind speed or rotor speed at the wind turbine;
• reducing loads on the wind turbine when the rate of change of the wind speed or rotor speed is above an acceleration threshold;
• wherein the acceleration threshold is based at least partially on the rate of change of the wind direction;
• pitching one or more blades of the wind turbine in order to keep a bending moment on the blades below a maximum bending moment threshold;
• and
• wherein the maximum bending moment threshold is lowered when the rate of change of wind speed or rotor speed is above the acceleration threshold.