Control of a wind turbine comprising multi-axial accelerometers

A method of controlling a wind turbine, the wind turbine comprising a tower supporting a nacelle and a rotor with a number of pitch-adjustable rotor blades, the wind turbine further comprising a control system for changing the pitch of the rotor blades and/or the generator torque, and a plurality of multi-axial accelerometers mounted at different positions in the nacelle and/or in a top portion of the tower, each accelerometer being mounted in a defined orientation, the method comprising:

• obtaining the position and orientation of each accelerometer as mounted;
• measuring accelerations in at least two different directions by each accelerometer during operation of the wind turbine;
• obtaining a number of pre-determined mode shapes for the movement of the wind turbine based at least on dimensions of the tower and a weight of the nacelle and the rotor as supported by the tower, the number of pre-determined mode shapes including at least one natural mode shape in a plane corresponding to fore-aft movements and at least one natural mode shape in a plane corresponding to side-side movements;
• determining an absolute position of at least one of the accelerometers during operation of the wind turbine based on the measured accelerations, the mount position and orientation of each accelerometer and the pre-determined mode shapes;
• determining a control parameter of the wind turbine as a function of the determined absolute position;
• and
• controlling the wind turbine according to the control parameter.