Patent ID: 9593669
Date: 2017-03-14
CPC Classifications: F03D,F05B,Y02E

Claim:
1. A method of controlling a wind turbine that includes a rotor, one or more blades mounted to the rotor, a variable displacement hydraulic pump mechanically connected to the rotor, a variable displacement hydraulic motor, and a high pressure circuit that connects the hydraulic pump to the hydraulic motor, the method comprising: harvesting power from wind to rotate the rotor; driving the hydraulic pump with the rotor to provide a pressurized flow of hydraulic fluid to the high pressure circuit; driving the hydraulic motor with the pressurized flow of hydraulic fluid from the high pressure circuit; in a first mode of operation, controlling displacement of the hydraulic motor to control power produced from the motor at a substantially constant power; and in a second mode of operation different than the first mode of operation, controlling a speed of the rotor by altering displacement of the hydraulic pump, and controlling pressure of the high pressure circuit by altering displacement of the hydraulic motor to produce power from the hydraulic motor that varies with respect to the variable displacement of the hydraulic motor; wherein the wind turbine is operated in the second mode of operation when a wind level is below a level capable of sustaining operation of the hydraulic motor at a constant value associated with a rated power level of the wind turbine; wherein the wind turbine is operated in the first mode of operation when the wind level is above the level.