Controlling wind turbine rotor blade pitch in accordance with a dynamic maximum pitch amplitude value

A method for a wind turbine having a rotor and two or more rotor blades, the method being for adjusting pitch of the rotor blades, the method comprising:

• determining a collective pitch reference for the rotor blades;
• receiving a collective pitch signal indicative of collective pitch angle of the rotor blades;
• receiving a power signal indicative of power output of the wind turbine;
• for each of one or more pitch offset control modules of a controller of the wind turbine, determining a respective dynamic maximum pitch amplitude value based on the received collective pitch signal and on the received power signal, and determining a respective pitch reference offset value in accordance with the respective dynamic maximum pitch amplitude value;
• and,
• determining an overall pitch reference based on the collective pitch reference and the one or more pitch reference offset values, and transmitting a control signal to adjust the pitch of the rotor blades in accordance with the overall pitch reference.

A wind turbine, comprising:

• a tower;
• a nacelle;
• a rotor extending from the nacelle and having a plurality of rotor blades;
• a controller configured for adjusting pitch of the plurality of rotor blades, the controller comprising:
• a collective pitch control module for determining a collective pitch reference for the rotor blades;
• and,
• one or more pitch offset control modules;
• the controller being configured to:
• receive a collective pitch signal indicative of collective pitch angle of the rotor blades;
• receive a power signal indicative of power output of the wind turbine;
• and,
• for each of the one or more pitch offset control modules, determine a respective dynamic maximum pitch amplitude value based on the received collective pitch signal and on the received power signal,
• wherein each pitch offset control module is configured to determine a respective pitch reference offset value in accordance with the respective dynamic maximum pitch amplitude value,
• the controller being configured to determine an overall pitch reference based on the collective pitch reference and the one or more pitch reference offset values, and to transmit a control signal to adjust the pitch of the rotor blades in accordance with the overall pitch reference.