Multi-rotor wind turbine oscillation damping

A multi-rotor wind turbine comprising:

• a wind turbine support structure;
• a first nacelle with a first rotor and a first pitch controller, operatively coupled to the first rotor for controlling the pitch thereof;
• a second nacelle with a second rotor and a second pitch controller, operatively coupled to the second rotor for controlling the pitch thereof;
• at least one of the nacelles being located at a position away from a central longitudinal axis of the wind turbine support structure;
• and
• an oscillation control unit, operably coupled to the first and the second pitch controller and being configured to perform an operation of damping oscillations in the multi-rotor wind turbine, the operation comprising:
• receiving motion data representing a movement of the first nacelle and of the second nacelle;
• processing the received motion data to determine at least two prominent oscillation modes of the wind turbine support structure;
• for each prominent oscillation mode selecting a corresponding damping algorithm;
• based on each one of the selected damping algorithm and the received motion data, generating a partial pitch control signal for a pitch controller of at least one of the rotors;
• combining the generated partial pitch control signals into a combined pitch control signal for the pitch controller of the at least one of the rotors;
• and
• based on the combined pitch control signal instructing the respective pitch controller to adapt a pitch of the at least one of the rotors.