An alternator, powered by a wind rotor having pitch changeable blades, is maintained at a fixed speed despite variations in wind speed and cyclic perturbations in rotor shaft speed due to rotor dynamics. In one embodiment, a geared speed increaser, coupling the rotor to the alternator, is mounted for reversible rotation relative to the rotor shaft. A fluid transfer means, such as a torque motor, coupled to a pressurized accumulator, applies such a torsional reaction to the speed increaser to permit its rotation at a rate which accommodates the difference between the instantaneous rotor shaft speed and that rotor shaft speed corresponding to the alternator's fixed speed. The fluid transfer means and accumulator means together permit a maximum angular displacement of the speed increaser sufficient to provide a time interval in which the rotor blade pitch may be corrected and the rotor shaft returned to normal speed. Pitch changes are effected, in part, responsive to rotation of the speed increaser.