Blade pitch

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

Variable pitch propeller

Abstract: An automatic variable pitch propeller including a central hub defining an axis of propeller rotation and a plurality of blades connected to and extending from the central hub substantially normal to the axis of rotation, each blade being mounted for rotation about a pitch axis, a cam mechanism to translate centrifugal forces imposed on that blade into a force tending to rotate that blade toward a course pitch, that force being opposed by water pressure tending to decrease blade pitch. The cam mechanism including a cam groove formed in an insert, of a material harder than the blades, in each blade shaft and the propeller being provided with variable minimum and maximum blade pitch stops, resilient bias toward minimum blade pitch and manual a pitch-up shift mechanism.

Blade gripping device

Abstract: The present invention concerns a blade gripping device (1) for gripping a rotor blade (9), in particular a rotor blade (9) of a wind turbine, comprising a blade gripping assembly (16) with a number of blade gripping tools (11a, 11b) and a sensor arrangement (14) realized to sense a specific feature of the rotor blade (9). Thereby, the specific feature is such that it can be used to orientate the blade holding device relative to the rotor blade (9) in a blade gripping manoeuvre. Further the invention concerns a method of moving a blade gripping device (1) for gripping a rotor blade (9), in particular a rotor blade (9) of a wind turbine, relative to the rotor blade (9).

Control of power generated by a floating offshore wind turbine perturbed by sea waves

Abstract: Offshore wind energy is expected to provide a significant contribution to the achievement of the European Renewable Energy targets. One of the main technological issues affecting floating offshore wind turbines concerns generated power fluctuations and structural fatigue caused by sea-wave/platform interactions. This paper presents a fully-coupled aero/hydro/servo-mechanic model for response and control of floating offshore wind turbines in waves, suitable for preliminary design. The wind-turbine is described by a multibody model consisting of rigid bodies (blades and tower) connected by hinges equipped with springs and dampers (for realistic low-frequency simulation). The aerodynamic loads are evaluated through a sectional aerodynamic approach coupled with a wake inflow model. A spar buoy floating structure supports the wind turbine. The hydrodynamic forces are evaluated through a linear frequency-domain potential solver, with the free surface deformation effects included through a reduced-order, state-space model. An optimal controller is identified and applied for rejection of annoying fluctuations of extracted power and structural loads. The developed comprehensive model has been successfully applied to a floating version of the NREL 5 MW wind turbine for stability analysis, as well as for the analysis of uncontrolled and controlled responses to regular and irregular short-crested sea waves. The proposed controller, based on the combined use of blade pitch and generator torque as control variables and the application of an observer for non-measurable aerodynamic and hydrodynamic states estimation, has been demonstrated to be effective in a wide frequency range for alleviation of both generated power fluctuations and vibratory loads.

Control system and method for mitigating rotor imbalance on a wind turbine

Abstract: A wind turbine includes multiple blades, multiple Micro Inertial Measurement Units (MIMUs) for sensing parameter signals of the blades, and a control system. The control system includes a blade bending moment calculation unit, a blade bending moment error signal calculation unit, and a pitch angle compensation command calculation unit. The blade bending moment calculation unit is used for calculating blade bending moment values of the blades based at least on the sensed parameters. The blade bending moment error signal calculation unit is used for calculating blade bending moment error signals of the blades based on the calculated blade bending moment values of the blades and multiple blade bending moment commands. The pitch angle compensation command calculation unit is used for calculating pitch angle compensation commands of the blades based on the calculated blade bending moment error signals to adjust pitch angles of the blades respectively.