A method for controlling a wind turbine system may generally include controlling a wind turbine to operate at a speed and torque setting within a permissible operating region defined between maximum and minimum operating curves, receiving a speed de-rate request and/or a torque de-rate request to de-rate the wind turbine based on a limiting constraint of the wind turbine system, determining an adjusted speed setting and/or an adjusted torque setting for the wind turbine based on the speed de-rate request and/or the torque de-rate request, determining whether an adjustment of the wind turbine operation to the adjusted speed setting and/or the adjusted torque setting would place the turbine outside the permissible operating region and, if the adjustment would place the operation outside the permissible operating region, adjusting the speed setting and/or the torque setting to a new speed and/or torque setting defined along the maximum or minimum operating curve.