Whirling mode control of a wind turbine based on tower measurements

A method for adjusting pitch of rotor blades of a wind turbine, the method comprising:

• receiving an acceleration signal from an acceleration sensor located in a tower or a nacelle of the wind turbine, the acceleration signal being indicative of side-to-side motion of the tower or nacelle of the wind turbine;
• determining a first component in a fixed coordinate frame of the wind turbine based on the received acceleration signal, the first component being indicative of an edgewise whirling mode of the wind turbine;
• generating, based on the determined first component, a second component in the fixed coordinate frame that is orthogonal to the first component, the second component is generated by application of a second-order generalised integrator to the first component;
• applying a control action to the first and second components to obtain respective first and second control components for mitigating the edgewise whirling mode;
• applying an inverse m-blade coordinate transformation to the first and second control components to obtain pitch reference offset values for the respective rotor blades in a rotor coordinate frame of the wind turbine;
• and,
• transmitting a control signal to adjust pitch of the rotor blades based on the obtained pitch reference offset values.

A non-transitory, computer-readable storage medium storing instructions thereon that when executed by one or more processors cause the one or more processors to perform an operation of adjusting pitch of rotor blades of a wind turbine, the operation comprising:

• receiving an acceleration signal from an acceleration sensor located in a tower or a nacelle of the wind turbine, the acceleration signal being indicative of side-to-side motion of the tower or nacelle of the wind turbine;
• determining a first component in a fixed coordinate frame of the wind turbine based on the received acceleration signal, the first component being indicative of an edgewise whirling mode of the wind turbine;
• generating, based on the determined first component, a second component in the fixed coordinate frame that is orthogonal to the first component, the second component is generated by application of a second-order generalised integrator to the first component;
• applying a control action to the first and second components to obtain respective first and second control components for mitigating the edgewise whirling mode;
• applying an inverse m-blade coordinate transformation to the first and second control components to obtain pitch reference offset values for the respective rotor blades in a rotor coordinate frame of the wind turbine;
• and
• transmitting a control signal to adjust pitch of the rotor blades based on the obtained pitch reference offset values.

A wind turbine, comprising:

• a tower;
• a nacelle disposed on the tower;
• a generator disposed in the nacelle;
• a rotor operably coupled to the generator;
• rotor blades operably coupled to an end of the rotor;
• and
• a controller configured to perform an operation for adjusting pitch of the rotor blades, the operation comprising:
• receiving an acceleration signal from an acceleration sensor located on the tower or the nacelle of the wind turbine, the acceleration signal being indicative of side-to-side motion of the tower or nacelle of the wind turbine;
• determining a first component in a fixed coordinate frame of the wind turbine based on the received acceleration signal, the first component being indicative of an edgewise whirling mode of the wind turbine;
• generating, based on the determined first component, a second component in the fixed coordinate frame that is orthogonal to the first component, the second component is generated by application of a second-order generalised integrator to the first component;
• applying a control action to the first and second components to obtain respective first and second control components for mitigating the edgewise whirling mode;
• applying an inverse m-blade coordinate transformation to the first and second control components to obtain pitch reference offset values for the respective rotor blades in a rotor coordinate frame of the wind turbine;
• and
• transmitting a control signal to adjust pitch of the rotor blades based on the obtained pitch reference offset values.