Blade pitch

About: Blade pitch is a research topic. Over the lifetime, 5321 publications have been published within this topic receiving 63134 citations.

Method and apparatus for controlling windmill blade pitch

Abstract: In order to control the turbine speed of a windmill employed for power generation, the pitch of the turbine blades is based on a dual-deadband control strategy. If the current turbine speed is determined to be outside of a relatively wide deadband, action is taken to correct the speed by changing blade pitch accordingly. If the current speed is not outside of the relatively wide deadband, then the average of the turbine speed over a recent interval is compared with a relatively narrow deadband within the wider deadband. Action is then taken to change the blade pitch if the average speed is outside the narrow deadband. In this way, wide excursions of turbine speed are corrected promptly, but the frequency of control actions is minimized by requiring only the average speed to be kept within tight limits.

Blade pitch varying mechanism

Abstract: An apparatus for varying the pitch of propulsor blades of a gas turbine engine by eccentrically driven gears. The gas turbine engine includes a rotating structure, an annular gas flowpath coaxial with the rotating structure, a plurality of rotor blades coupled to the rotating structure and extending into the gas flowpath such that a gas stream flowing through the flowpath causes the rotating structure to rotate with respect to the stationary member and a plurality of variable pitch propulsor blades coupled to and disposed radially outwardly of the rotating structure. The pitch of the blade is varied by a pinion gear coaxially coupled to one of the propulsor blades and an internal gear radially disposed about the pinion gear for driving the pinion gear. Annular displacement of the pinion gear causes angular displacement of the propulsor blade with respect to the rotating structure. The internal gear is revolved about the pinion gear whereby the pinion gear is angularly displaced with respect to the rotating structure.

Performance of a Vertical Axis Wind Turbine with Variable-Pitch Straight Blades utilizing a Linkage Mechanism

Abstract: This paper describes the performance of a micro vertical-axis wind turbine with variable-pitch straight blades. The proposed variable-pitch angle mechanism has an eccentric point that is different from the main rotational point. One feature of the mechanism is its ability to vary the pitch angle of the blades according to the azimuth angle of the main links, without actuators. The performance of the wind turbine was measured in an open-circuit wind tunnel. The performance of the vertical-axis wind turbine with variable-pitch straight blades was better than one with fixed-pitch blades. A wind turbine with variable-pitch straight blades has wind directivity. It was found that the performance of a wind turbine is dependent upon the blade offset pitch angle, the blade pitch angle amplitude, the size of the turbine, the number of blades, and the airfoil profile.

Disturbance Tracking and Blade Load Control of Wind Turbines in Variable-Speed Operation

Abstract: A composite state-space controller was developed for a multi-objective problem in the variable-speed operation of wind turbines. Disturbance Tracking Control theory was applied to the design of a torque controller to optimize energy capture under the influence of persistent wind disturbances. A limitation in the theory for common multi-state models is described, which led to the design of a complementary pitch controller. The goal of the independent blade pitch design was to minimize blade root fatigue loads. Simulation results indicate an 11% reduction in fatigue damage using the proposed controllers, compared to a conventional torque-only design. Meanwhile, energy capture is almost identical, partly because of nonlinear effects.

System and method for reducing rotor loads in a wind turbine upon detection of blade-pitch failure and loss of counter-torque

Abstract: A system and method for reducing rotor loads in a wind turbine that includes a brake and one or more rotor blades coupled to a rotor. Upon detection of a loss of counter torque and a blade-pitch failure in at least one rotor blade, a processor reduces a generator overspeed threshold value by a predetermined amount and determines a brake-release threshold value. The brake is applied to slow the rotor if the generator/rotor speed exceeds the reduced generator/rotor overspeed threshold value. In addition, the brake is applied to slow the rotor until the generator/rotor speed is below the brake-release threshold value. The rate of change of the pitch angle of the rotor blade may be varied as the blade moves toward feather in response to the detected blade-pitch failure.