Estimating velocity in a fore-aft direction of a top of a wind turbine tower based on blade flap loads

A controller for estimating a velocity of a top of a tower of a wind turbine, the wind turbine comprising a rotor and a plurality of rotor blades, the controller being configured to:

• obtain a measured acceleration signal indicative of measured acceleration of the top of the tower in the fore-aft direction of the wind turbine;
• obtain an estimated thrust force signal indicative of estimated thrust force experienced by the rotor, and provide the estimated thrust force signal as input to a defined observer model describing motion of the top of the tower;
• determine an error signal based on a difference between the measured acceleration signal and an estimated acceleration signal obtained using the defined observer model, and provide the error signal as input to the observer model as part of a feedback loop;
• and,
• determine, using the defined observer model, a velocity signal indicative of estimated velocity of the top of the tower in the fore-aft direction of the wind turbine,
• wherein the estimated thrust force signal is obtained based on an obtained blade flap load signal indicative of measured flap loading on the rotor blades.

A wind turbine, comprising:

• a tower;
• a nacelle disposed on the tower;
• a rotor extending from the nacelle;
• a plurality of rotor blades coupled to the rotor;
• and
• a controller, configured to perform an operation:
• obtain a measured acceleration signal indicative of measured acceleration of the top of the tower in the fore-aft direction of the wind turbine;
• obtain an estimated thrust force signal indicative of estimated thrust force experienced by the rotor, and provide the estimated thrust force signal as input to a defined observer model describing motion of the top of the tower;
• determine an error signal based on a difference between the measured acceleration signal and an estimated acceleration signal obtained using the defined observer model, and provide the error signal as input to the observer model as part of a feedback loop;
• and
• determine, using the defined observer model, a velocity signal indicative of estimated velocity of the top of the tower in the fore-aft direction of the wind turbine,
• wherein the estimated thrust force signal is obtained based on an obtained blade flap load signal indicative of measured flap loading on the rotor blades.