A wind turbine yaw system is provided that includes a yaw gear, at least two pinion gears, and at least two drive units, each of which is associated to one of the pinion gears for driving that pinion gear. The yaw system also includes a control system with a controller for generating a drive unit control signal for each drive unit for controlling the respective drive unit according to a reference signal having a desired operational parameter value for the respective drive unit, so as to realize the desired operational parameter value in the respective drive unit. The control system includes a feedback loop for each drive unit feeding a drive unit feedback signal including at least the actual value of one operational parameter of the respective drive unit back to the controller. The controller generates the drive unit control signals based on the reference signal and the feedback signals.