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A wind turbine includes a rotor shaft having thereon rotor blades exposed to wind energy, a first stage gear set on the rotor shaft, a discretely variable ratio gear set coupled to the first stage gear output shaft and having a gear set output shaft, a differential on the gear set output shaft havin

A wind turbine includes a rotor shaft having thereon rotor blades exposed to wind energy, a first stage gear set on the rotor shaft, a discretely variable ratio gear set coupled to the first stage gear output shaft and having a gear set output shaft, a differential on the gear set output shaft having a differential control shaft facilitating changing the gear box ratio by whole numbers of gear teeth, and a generator operating at a constant frequency coupled to an electric grid operating at the constant frequency. The wind turbine may take a variable speed input of the gear box to create a fixed speed output fed to the generator operating at constant frequency and coupled directly to the power grid without power electronics. Existing wind turbines whether fixed speed fixed pitch or variable speed variable pitch can be retrofitted with the gear box of the present invention.

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1. A wind turbine, comprising: a rotor shaft having thereon rotor blades exposed to wind energy;a first stage gear set on the rotor shaft, the first stage gear having a first stage gear set output shaft;a discretely variable ratio gear set coupled to the first stage gear output shaft and having a ge

1. A wind turbine, comprising: a rotor shaft having thereon rotor blades exposed to wind energy;a first stage gear set on the rotor shaft, the first stage gear having a first stage gear set output shaft;a discretely variable ratio gear set coupled to the first stage gear output shaft and having a gear set output shaft;a differential on the gear set output shaft, the differential having a differential output shaft and a differential control shaft, the differential control shaft facilitating changing the gear box ratio; anda generator operating at a constant frequency and coupled to an electric grid that operates at the constant frequency. 2. The wind turbine of claim 1, wherein the discretely variable ratio gear set shifts a diameter of a gear wheel in the gear set by a discrete whole number of gear teeth. 3. The wind turbine of claim 1, wherein the discretely variable ratio gear set includes a first tooth sequence of a gear wheel displaced from a second tooth sequence of the gear wheel so as to vary a degree of peripheral coextension between the first and second tooth sequences on the gear wheel. 4. The wind turbine of claim 1, wherein the discretely variable diameter gear box is capable of shifting gears under full load without a clutch disengagement or torque discontinuation. 5. A method of harnessing wind energy to operate an electric power grid by means of a wind turbine, comprising: converting wind energy from wind striking rotor blades to mechanical energy of a rotating rotor shaft that the rotor blades are attached to, the rotor blades and rotor shaft having variable rotational speeds;transferring the variable rotational speed of the rotor shaft to a variable rotational speed of a gear box input shaft;converting the variable rotational speed of the gear box input shaft to a fixed rotational speed of a gear set output shaft by varying a diameter of a gear wheel in the gear box to create a variable gear ratio having non-continuous discrete magnitudes, the variable gear ratio reflecting the variable rotational speed of the rotor blades; andtransmitting the fixed rotational speed of the gear set output shaft to a generator operating at constant frequency, the generator coupled directly to an electric power grid. 6. The method of claim 5, further including the generator transmitting power to the electric power grid without a power converter. 7. The method of claim 5, further including preparing the shifting of the diameter of the gear wheel of the gear box by rotating a differential control shaft of a differential in a direction consistent with an increased speed of the rotor blades, an input of the differential either doubling as or being coupled to an output of the gear set output shaft. 8. The method of claim 5, further including using a differential to limit torque spikes from discrete changes in a gear ratio of the gear box. 9. A wind turbine, comprising: a rotor shaft having thereon rotor blades exposed to wind energy from varying wind speeds;a gear box including a discretely variable ratio gear set, the gear box receiving varying rotational energy from a varying rotational speed of the rotor shaft, the discretely variable ratio gear set having a fixed speed output and including a discretely variable diameter gear; anda generator receiving fixed speed output from the gear box, the generator operating at constant frequency and coupled to an electric power grid operating at the constant frequency. 10. The wind turbine of claim 9, wherein a differential is positioned between the discretely variable ratio gear set and the generator. 11. The wind turbine of claim 10, wherein the differential is gear set that has a planetary configuration. 12. The wind turbine of claim 10, wherein the differential is a gear set that acts as a speed increasing stage. 13. The wind turbine of claim 10, wherein the differential is configured to adjust rotor speed without shifting a diameter of the discretely variable diameter gear. 14. The wind turbine of claim 9, wherein the efficiency of the wind turbine is optimized. 15. An apparatus for wind turbines having a rotor shaft and rotor blades and having a generator connected to an electric power grid, the apparatus comprising: a discretely variable ratio gear set of a gear box receiving varying rotational energy from a varying rotational speed of the rotor shaft, the discretely variable diameter gear box having a fixed speed output and including a gear wheel whose diameter can be varied, the discretely variable diameter gear box having a gear set output shaft;a differential coupled to an output shaft of the discretely variable ratio gear set, the differential having a differential output shaft and a differential control shaft, the differential control shaft facilitating shifting of diameters of a gear wheel in the discretely variable ratio gear set, the gear box capable of being utilized in both fixed pitch and variable pitch turbines. 16. The apparatus of claim 15, wherein the discretely variable ratio gear set includes a pinion gear whose shaft is the discretely variable ratio gear set output shaft and an idler gear whose axle is not connected to power, the idler gear moving along the pinion gear and the gear wheel when a diameter of the gear wheel is shifted. 17. A method of retrofitting a wind turbine coupled to a power grid through power electronics, the wind turbine having a fixed ratio gear box, the method comprising: removing the power electronics between the generator and the power grid;connecting the generator to the power grid; andreplacing the fixed ratio gear box with a discretely variable ratio gear box that receives varying rotational energy from a varying rotational speed of the rotor shaft and that has a fixed speed output. 18. The method of claim 17, further including adding a differential between the discretely variable ratio gear box and the generator. 19. A method of retrofitting a fixed speed fixed pitch wind turbine that has a generator operating at a constant frequency, the generator coupled directly to a power grid that operates at the constant frequency, the method comprising: replacing the fixed ratio gear box situated between a rotor shaft and the generator with a discretely variable ratio gear box, the discretely variable ratio gear box receiving varying rotational energy from a varying rotational speed of the rotor shaft and having a fixed speed output that is transferred to the generator. 20. The method of claim 19, further including coupling the discretely variable ratio gear box to a planetary gear that is coupled to the rotor shaft. 21. The method of claim 19, further including using a differential positioned between the discretely variable ratio gear box and the generator to smoothen a shifting of a diameter of a gear wheel of the discretely variable ratio gear box and to limit a torque in the discretely variable ratio gear box. 22. A method of gear shifting in a wind turbine, comprising: coupling a differential to a gear set output shaft of a gear box of the wind turbine, the differential having a differential output shaft connected to a generator and having a differential control shaft; andas rotor speed increases from increased wind energy, in a first step accelerating a rotation of the differential control shaft in a direction consistent with increased rotor speed while maintaining fixed a diameter of a gear wheel in the gear box and in a second step shifting a diameter of a gear wheel in the gear box upward by a gear tooth while slowing the differential output shaft down to zero. 23. A method of limiting a power of a stall controlled wind turbine having rotor blades and having a generator coupled directly to an electric power grid, the method comprising: replacing the fixed ratio gear box situated between a rotor shaft and the generator with a discretely variable ratio gear box; andcontrolling a degree to which the rotor blades stall without varying a pitch of the rotor blades by using the discretely variable ratio gear box to vary a speed of the rotor blades, the discretely variable ratio gear box receiving varying rotational energy from a varying rotational speed of the rotor shaft and outputting a fixed speed. 24. A wind turbine, comprising: a rotor shaft having thereon rotor blades exposed to wind energy from varying wind speeds;a gear box including a variable ratio gear set, the gear box receiving varying rotational energy from a varying rotational speed of the rotor shaft, the variable ratio gear set having a fixed speed output and including a gear set output shaft;a generator receiving fixed speed output from the gear box, the generator operating at constant frequency and coupled to an electric power grid operating at the constant frequency, the generator transmitting power to the electric power grid without a power converter; anda differential between the variable ratio gear set and the generator, the differential including a differential control shaft, the differential control shaft configured to adjust rotor speed by increasing or decreasing a speed of the gear set output shaft. 25. The wind turbine of claim 24, wherein the differential is gear set that has a planetary configuration. 26. The wind turbine of claim 24, wherein the differential is a gear set that is configured to act as a speed increasing stage. 27. The wind turbine of claim 24, wherein the differential is a gear set that is configured to act as a speed decreasing stage. 28. A wind turbine, comprising: a rotor shaft having thereon rotor blades exposed to wind energy;a first stage gear set on the rotor shaft, the first stage gear set being a fixed ratio gear and having a first stage gear set output shaft;a variable ratio gear set coupled to the first stage gear output shaft and having a gear set output shaft;a generator operating at a constant frequency and coupled to an electric grid that operates at the constant frequency, the generator transmitting power to the electric power grid without a power converter; anda differential on the gear set output shaft, the differential having a differential output shaft and a differential control shaft, the differential control shaft facilitating changing the gear box ratio by increasing or decreasing a speed of the gear set output shaft in order to adjust rotor speed without shifting a diameter of the variable ratio gear, the differential output shaft coupled to the generator. 29. The wind turbine of claim 28, wherein the differential is gear set that has a planetary configuration. 30. The wind turbine of claim 28, wherein the differential is a gear set that is configured to act as a speed increasing stage. 31. The wind turbine of claim 28, wherein the differential is a gear set that is configured to act as a speed decreasing stage. 32. A wind turbine, comprising: a rotor shaft having thereon rotor blades exposed to wind energy from varying wind speeds;a gear box including a gear set, the gear box receiving rotational energy from a rotational speed of the rotor shaft, the gear set having a fixed ratio and including a gear set output shaft;a generator receiving fixed speed output from the gear box, the generator operating at constant frequency and coupled to an electric power grid operating at the constant frequency, the generator transmitting power to the electric power grid without a power converter; anda differential positioned between the gear set and the generator, the differential including a differential control shaft, the differential control shaft of the differential configured to adjust rotor speed by increasing or decreasing a speed of the gear set output shaft. 33. The wind turbine of claim 32, wherein the gear set is one of a fixed ratio gear set and a variable ratio gear set. 34. The wind turbine of claim 33, wherein the gear set is a variable ratio gear. 35. The wind turbine of claim 33, wherein the gear set is a fixed ratio gear. 36. A method of retrofitting a wind turbine coupled to a power grid through power electronics, the wind turbine having a fixed ratio gear box, the method comprising: removing the power electronics between the generator and the power grid;connecting the generator to the power grid so that the generator transmits power to the electric power grid without a power converter;replacing a fixed ratio gear box with a variable ratio gear box that receives varying rotational energy directly or indirectly from a varying rotational speed of the rotor shaft and that has a fixed speed output, the variable ratio gear box comprising a differential, the differential connected to the generator, the differential including a differential control shaft that is configured to adjust rotor speed by increasing or decreasing a speed of one of (i) a gear set output shaft connected to the rotor shaft and (ii) the rotor shaft. 37. The wind turbine of claim 36, wherein the differential is gear set that has a planetary configuration. 38. The wind turbine of claim 36, wherein the differential is a gear set that is configured to act as a speed increasing stage. 39. The wind turbine of claim 36, wherein the differential is a gear set that is configured to act as a speed decreasing stage.