Method of identifying a fault in a system of gears in a wind turbine

A controller for controlling a wind turbine, the controller being configured to perform an operation identifying a fault in a system of gears in a wind turbine, the operation comprising:

• determining a first centre harmonic frequency amplitude according to vibrations of the system of gears;
• determining a plurality of sideband amplitudes of the first centre harmonic frequency amplitude;
• calculating an average sideband amplitude from the plurality of sideband amplitudes;
• and
• determining a value indicative of damage incurred by the system of gears based upon the first centre harmonic frequency amplitude and the average sideband amplitude.

A wind turbine, comprising:

• a tower;
• a nacelle disposed on the tower;
• a rotor extending from the nacelle;
• a plurality of blades coupled to one end of the rotor;
• and
• a controller configured to perform an operation identifying a fault in a system of gears in a wind turbine, the operation comprising:
• determining a first centre harmonic frequency amplitude according to vibrations of the system of gears;
• determining a plurality of sideband amplitudes of the first centre harmonic frequency amplitude;
• calculating an average sideband amplitude from the plurality of sideband amplitudes;
• and
• determining a value indicative of damage incurred by the system of gears based upon the first centre harmonic frequency amplitude and the average sideband amplitude.