Multi-rotor turbine arranged for coordinated rotational speeds

A method of controlling a wind turbine system comprising a plurality of wind turbine modules mounted to a support structure including a tower, each of the plurality of wind turbine modules including a rotor, wherein, in use, each rotor has an associated rotational imbalance, the method comprising:

• determining, for each rotor, a respective imbalance vector corresponding to the associated rotational imbalance;
• and
• based on a comparison of the respective imbalance vectors, coordinating the rotational speeds of the rotors to attenuate oscillations of the support structure caused by the rotational imbalances associated with the rotors.

A computer program product comprising a non-transitory computer-readable medium, the computer-readable medium comprising program code instructions which, when executed by one or more processors, perform an operation for controlling a plurality of rotors mounted to a support structure including a tower, each rotor having an associated rotational imbalance, the operation comprising:

• determining, for each rotor, a respective imbalance vector corresponding to the associated rotational imbalance;
• and
• based on a comparison of the respective imbalance vectors, coordinating the rotational speeds the rotors to attenuate oscillations of the support structure caused by the rotational imbalance associated with the rotors.