Blade pitch

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

Tail rotor mounting for coning relief

Abstract: Helicopter tail rotors provide anti-torque forces to maintain stabilized flight and further provide aircraft heading control. Aerodynamic forces generated on the rotor blade cause the tip thereof to move out of line with the pitch change axis of the blade, an effect known as ''''coning,'''' which produces undesirable forces on the rotor blade, the hub and the tail rotor control system. Each tail rotor blade is attached to a blade grip which is coupled to a yoke through laminated elastomeric bearings that provide in-plane stiffness while permitting blade coning in such a manner as to relieve the undesired coning effect forces.

Horizontal axis wind turbine

Abstract: A horizontal axis wind turbine is disclosed. When a wind direction changes to blow against a rotor from a rear side, a pitch angle of a rotor blade of the rotor are controlled to reverse a rotation of the rotor, without turning of the rotor to the rear side.

Power Smoothing Control Strategy of Direct-driven Permanent Magnet Synchronous Generator for Wind Turbine With Pitch Angle Control and Torque Dynamic Control

Abstract: The uncertainty of wind energy and the inherent features of the wind turbine make the output active power of the wind-power generator fluctuate with the change of the wind speed, which affects the output power quality of the wind turbine and even the stability of the power grid. Based on analyzing of the operational characteristics about the direct-driven permanent magnet synchronous generator (DD-PMSG), an active power smoothing control strategy had been proposed through the pitch angle control and variable speed control of the generator in all operating regions. Considering the stochastic behavior of the wind energy and the highly nonlinear feature of the DD-PMSG, the pitch angle controller had been investigated based on the fuzzy theory and the generator torque dynamic sliding-mode controller. The operational characteristics of a DD-PMSG with the fuzzy pitch angle control and the torque dynamic sliding-mode control were studied through the computer simulation. The simulation results show that the speed operation range of the wind turbine can be effectively controlled by the fuzzy pitch angle control strategy and the output active power of the generator can be smoothed by the dynamic sliding-mode control strategy. Compared with the traditional maximum power point tracking (MPPT) control strategy, the proposed control strategy can effectively reduce the output active power fluctuations of the DD-PMSG and limit the operation range of the generator speed.

Fault-tolerant apparatus for controlling blade pitch

Abstract: Fault-tolerant apparatus for controlling first and second input members of a mechanical actuator includes first and second electrical machines and at least two controllers. The first and second electrical machines, which apply braking forces to the first and second input members, respectively, are provided with stators having pluralities of isolated phase windings. Each controller is coupled to a phase winding of the first electrical machine, and also to a phase winding of the second electrical machine. Any one controller can excite the first electrical machine to apply the braking force to the first input member or the second electrical machine to apply the braking force to the second input member.

Correlation between Rotating LIDAR Measurements and Blade Effective Wind Speed

Abstract: Preview wind speed measurements from a forward looking Light Detection and Ranging (LIDAR) system located in the hub of a wind turbine can be used by a feedforward blade pitch control system to mitigate structural loads. For individual blade pitch control, a separate preview estimate of the e ective wind speed encountered by each blade must be available. One way of providing an estimate of the blade e ective wind speed is to implement a hub mounted spinning lidar that scans the wind eld at the rotational rate of the rotor such that the measured wind will reach the blade after some delay. In this way, both the lidar measurement and the wind turbine blade rotationally sample the wind eld. The bene t gained by using preview wind speed measurements strongly depends on the correlation between the measured wind and the wind that interacts with the blades. In this research, the coherence between rotating lidar measurements and blade e ective wind speed is calculated and analyzed using a spectral model of the wind eld. The simulated wind eld uses an isotropic von Karman spectrum and contains a model of wind evolution described by a longitudinal spatial coherence function. The coherence between stationary measurements and stationary blade e ective wind speeds decreases to zero near the 1P rotational frequency of the turbine. However, measurement coherence between rotating lidar measurements and blade e ective wind speed remains much higher and does not decay until higher frequencies.