Method and system for controlling wind turbine rotor oscillations

A method of controlling operation of a wind turbine, the method comprising:

• receiving operational data indicative of oscillations in a wind turbine rotor;
• from the operational data, deriving a first signal representative of first loads acting in a first direction in a reference plane corresponding to or parallel to a rotational plane of the wind turbine rotor;
• from the operational data, deriving a second signal representative of second loads different from the first loads acting in a second direction in the reference plane that is different from the first direction;
• determining an amplitude of each of the first and second signals;
• determining a phase offset between the first and second signals;
• controlling the wind turbine based at least partially based on the determined amplitudes and the determined phase offset;
• and
• wherein amplitude thresholds are predefined for the determined amplitudes and a band is predefined for the determined phase offset, the method further comprising identifying a wind turbine rotor oscillation mode based on a comparison between the determined amplitudes and the predefined amplitude thresholds, and on a comparison between the determined phase offset and the band.