Wind Turbine Movable Aerodynamic Device Control
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Solution Overview
Problem
Modern wind turbines face challenges in rapidly adjusting blade positions to counteract wind gusts and turbulence due to the slow nature of blade pitching, leading to potential excessive loading on rotor blades, especially when using movable aerodynamic devices like trailing edge flaps.
Innovation Solution
A method and controller for a movable aerodynamic device that prevents operation at predetermined frequency bands, specifically removing frequency components at the edgewise resonant frequency of the rotor blade to avoid stimulating structural coupling and excessive loading, using filters like band-stop or notch filters to adjust the device position demand based on wind disturbances and loading changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the movable aerodynamic device operates to reduce flapwise loading on the rotor blade, then the fatigue loading of the rotor blade is reduced, but the edgewise loading on the blade may be increased due to structural coupling effects
Solution Approach 1:
The patent identifies that operating the movable aerodynamic device can inadvertently excite edgewise resonant frequencies, causing harmful edgewise loading. The solution converts this harmful effect into a beneficial control strategy by actively detecting resonant frequency excitation and adjusting the device operation to avoid these frequencies, thereby preventing the harmful structural coupling effects while maintaining the beneficial flapwise loading reduction
Solution Approach 2:
The patent implements a feedback control mechanism where the operation of the movable aerodynamic device is continuously monitored and adjusted based on the detected structural response of the rotor blade. When edgewise resonant frequencies are detected, the control system modifies the device operation to prevent excitation, creating a closed-loop system that adapts to prevent harmful loading conditions
2Force
If blade pitching is used to regulate loads on the rotor, then load regulation is achieved, but the response speed is too slow to account for wind gusts and turbulence
Solution Approach 1:
The patent transitions from static blade pitching to dynamic control of movable aerodynamic devices. The movable devices can be rapidly actuated to respond to transient wind conditions, providing dynamic load regulation that matches the speed of wind gusts and turbulence, thereby resolving the speed limitation of traditional pitch control
Solution Approach 2:
The patent changes the aerodynamic parameters of the blade by deploying movable devices such as flaps or spoilers that can rapidly alter the airfoil shape and surface area. This provides a faster response mechanism compared to blade pitching, enabling rapid adjustment of aerodynamic forces to counteract wind gusts and turbulence
3Force
If the movable aerodynamic device is designed to operate at certain frequencies to reduce loading, then loading reduction is achieved, but operation at edgewise resonant frequency causes excessive edgewise loading
Solution Approach 1:
The patent applies preliminary action by identifying and avoiding edgewise resonant frequencies before they can cause harmful effects. The control system proactively detects potential resonant excitation and adjusts the movable device operation in advance to prevent the harmful structural coupling from occurring, thereby maintaining structural integrity while achieving loading reduction
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces flapwise loading and movement of the blade while preventing increases in edgewise loading, thereby minimizing fatigue and potential damage by ensuring the movable aerodynamic device operates within safe frequency ranges, maintaining optimal aerodynamic performance and structural integrity.
Implementation Method 1
The movable aerodynamic device, which may for example be a trailing edge flap, is configured to move in order to alter the aerodynamic profile of the blade
Implementation Method 2
The step of preventing the movable aerodynamic device from operating in a predetermined frequency band comprises: removing frequency components from the device position demand at the edgewise resonant frequency of the rotor blade
Implementation Method 3
The weight of the rotor blade itself generates alternating tensile and compression forces along its length as it rotates, which results in cyclic loading of each rotor blade
Implementation Method 4
The movable aerodynamic devices are operated to reduce loading on the wind turbine blade by counteracting wind disturbances in the oncoming wind flow
Data Source
Figure 1
Figure 2~3b
Figure 4~5
AI summary
A method of controlling a movable aerodynamic device on a wind turbine rotor blade, the method comprising the steps of: determining a device position demand as a function of time, the device position demand being calculated to reduce loading in the blade; moving the device according to the device position demand; and preventing the device from operating in a predetermined frequency band.