Wind Turbine Blade Stall Control via Segmented Pitch
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Solution Overview
Problem
Wind turbine blades experience negative stall at the outboard region when the pitch angle is increased, leading to reduced lift, increased drag, stability issues, and noise, which limits operational efficiency and increases wear, especially in high winds.
Innovation Solution
A method that involves measuring wind turbine parameters to detect impending negative stall at the outboard region and activating a lift disrupting device at the mid-board region to reduce airflow over the suction side, preventing stall and allowing the turbine to operate efficiently in higher wind speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the pitch angle of the wind turbine blade is increased to reduce rotational speed, then the rotational speed is reduced, but negative stall occurs at the outboard region causing reduced lift and increased drag
Solution Approach 1:
The blade is divided into different regions (inboard, mid-board, outboard) with different pitch angles. The outboard region is pitched further out of the on-coming wind than the inboard region, creating a segmented pitch configuration that prevents negative stall at the outboard region while allowing rotational speed control
Solution Approach 2:
Different regions of the blade have different local pitch angles tailored to their specific operational requirements. The outboard region has a higher pitch angle to prevent negative stall, while the inboard region maintains a lower pitch angle for optimal lift generation
2Speed
If the pitch angle is increased to reduce rotational speed, then the rotational speed is reduced, but stability problems and vibrations occur
Solution Approach 1:
The blade is segmented into regions with different pitch angles, preventing negative stall at the outboard region which causes vibrations and stability problems
Solution Approach 2:
The control system monitors blade performance and adjusts pitch angles in real-time to maintain stability and prevent vibrations caused by negative stall
3Speed
If the pitch angle is increased to reduce rotational speed, then the rotational speed is reduced, but noise increases
Solution Approach 1:
The blade is segmented with different pitch angles in different regions, preventing negative stall at the outboard region which is a major source of noise
Solution Approach 2:
The outboard region has a higher pitch angle to prevent negative stall and reduce noise, while other regions maintain optimal pitch for power generation
4Speed
If the pitch angle is increased to reduce rotational speed, then the rotational speed is reduced, but the operational wind speed range is limited
Solution Approach 1:
The segmented pitch configuration allows the blade to operate effectively across a wider range of wind speeds by preventing negative stall at the outboard region
Solution Approach 2:
The pitch angles are dynamically adjusted based on operating conditions, allowing the turbine to adapt to different wind speeds and maintain optimal performance
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
Prevents negative stall at the outboard region, reduces rotational speed and loads on the turbine, and extends the operational wind speed range, enhancing efficiency and reducing wear by controlling lift and drag effectively.
Implementation Method 1
activating a lift disrupting device for disrupting airflow over the suction side of the wind turbine blade such that the lift generated by the wind turbine blade is reduced
Implementation Method 2
In operation, wind turbine blades experience aerodynamic lift due to the on-coming wind. This lift causes a wind turbine hub, to which the wind turbine blades are attached at their inboard ends, to rotate
Implementation Method 3
If the angle of attack of the wind turbine blade is reduced, the aerodynamic lift generated by the wind turbine blade is also reduced which in turn can reduce the rotational speed of the rotor. The angle of attack of the wind turbine blade can be reduced by increasing the pitch angle of the wind turbine blade
Implementation Method 4
Negative stall occurs in wind turbine blades when the airflow separation occurs on the pressure side of the turbine blade. The flow separation on the pressure side of the wind turbine blade causes large reductions in lift generated by the blade and also increases drag
Data Source
Figure 1
Figure 2
Figure 3a~4b
AI summary
A method for controlling a wind turbine, the wind turbine comprising a wind turbine blade, the method comprising: measuring one or more wind turbine parameters; determining, based on the one or more wind turbine parameters, whether negative stall will occur at an outboard region of the wind turbine blade; generating a first signal if it is determined negative stall will occur at the outboard region of the wind turbine blade; and activating a lift disrupting device for disrupting airflow over the suction side of the wind turbine blade in response to the generated first signal such that the lift generated by the wind turbine blade is reduced; wherein the lift disrupting device for disrupting airflow over the suction side of the wind turbine blade is disposed at a mid-board region of the wind turbine blade.