Blade pitch

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

Wide-range blade pitch control for a folding rotor

Abstract: A blade pitch control system for a rotary wing aircraft which incorporates a mast and rotor which is pivotally adapted for movement of the mast between a generally horizontal stored position and a vertical position for operation in a helicopter mode. The pitch control system incorporates a motion amplification mechanism such as a star gear arrangement connected to the pitch horn to amplify control motions which are transmitted to the pitch horns through a push-pull control tube generally parallel to the folding axis of the rotor blade. In another embodiment, the push-pull tube inputs parallel to the mast axis. A locking mechanism retains the blades so pitch changes cannot be made during a predetermined portion of the blade coning cycle.

Combining Standard Feedback Controllers with Feedforward Blade Pitch Control for Load Mitigation in Wind Turbines

Abstract: Combined feedback/feedforward blade pitch control is compared to industry standard feedback control when simulated in realistic turbulent winds. The feedforward controllers are designed to reduce fatigue loads, increasing turbine lifetime and therefore reducing the cost of energy. Various collective pitch and individual pitch versions of two feedforward designs are studied: Gain-Scheduled Model-Inverse and Gain-Scheduled Shaped Compensator. The input to the feedforward controller is a measurement of incoming wind speed, which could potentially be provided by LIDAR. Three of the designs reduce structural loading compared to standard feedback control, without reducing power production.

Method for predicting a power curve for a wind turbine

Abstract: A method for calculating a high-altitude power curve for a wind turbine is provided, the method including the steps of determining a cp-λ curve for a predetermined blade pitch angle of said wind turbine; calculating a first power curve without power limit based on the cp-λ curve; and calculating the high-altitude power curve with power limit from said first power curve, thereby using a site air density.

Pitch angle control of a wind turbine operating above the rated wind speed: A sliding mode control approach

Abstract: The paper focuses on variable-rotor-speed/variable-blade-pitch wind turbines operating in the region of high wind speeds, where control is aimed at limiting the turbine energy capture to the rated power value. A robust sliding mode approach is proposed, using the blade pitch as control input, in order to regulate the rotor speed to a fixed rated value, in the presence of uncertainties characterizing the wind turbine model. Closed loop convergence of the overall control system is proved. The proposed control solution has been validated on a 5 − M W three-blade wind turbine using the National Renewable Energy Laboratory (NREL) wind turbine simulator FAST (Fatigue, Aerodynamics, Structures, and Turbulence) code. A comparison with the standard FAST baseline controller (NWTC 2012 and Jonkman et al. 2009) has been also included.

An aerodynamic analysis of the autogiro rotor with a comparison between calculated and experimental results

Abstract: This report presents an extension of the autogiro theory of Glauert and Lock in which the influence of a pitch varying with the blade radius is evaluated and methods of approximating the effect of blade tip losses and the influence of reversed velocities on the retreating blades are developed. A comparison of calculated and experimental results showed that most of the rotor characteristics could be calculated with reasonable accuracy, and that the type of induced flow assumed has a secondary effect upon the net rotor forces, although the flapping motion is influenced appreciably. An approximate evaluation of the effect of parasite drag on the rotor blades established the importance of including this factor in the analysis.