Wind Turbine Blade Pitch Control to Prevent Stall During Derating
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Solution Overview
Problem
Wind turbines face the challenge of avoiding stall during derating, particularly in low air density conditions, where derating by reducing speed can lead to stall, and existing systems lack effective methods to mitigate this issue.
Innovation Solution
A method and system for operating wind turbines that involve providing an initial pitch setting for rotor blades, monitoring environmental and operational conditions, and modifying the pitch setting when conditions indicative of stall are detected, such as low air density, to prevent stall by adjusting the pitch towards a feather position, thereby maintaining a safe angle of attack.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the wind turbine speed set point is reduced to derate the turbine, then the loads on turbine components are mitigated, but the rotor blades may enter stall especially in low air density conditions
Solution Approach 1:
The system changes the pitch angle parameter of the rotor blades in response to detected stall conditions. When stall is detected (through sensor inputs or calculated conditions), the controller adjusts the pitch angle to a less aggressive setting, thereby changing the aerodynamic parameters to prevent stall while maintaining the derated speed setting.
Solution Approach 2:
The system implements a feedback mechanism where sensors monitor operational conditions (such as blade pitch angle, wind speed, power output) and feed this information back to the controller. The controller continuously compares actual conditions against stall thresholds and automatically adjusts the pitch setting accordingly, creating a closed-loop control system that prevents stall during derating.
2Reliability
If the pitch setting is modified to prevent stall during derating, then the rotor blades maintain safe angle of attack, but the system complexity increases
Solution Approach 1:
The control system performs self-adjustment by automatically detecting stall conditions through sensor inputs and calculating appropriate pitch corrections without requiring external intervention. The system serves itself by monitoring its own operational state and making necessary adjustments to maintain safe operating conditions, thereby managing complexity through automation rather than manual control.
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
The solution effectively prevents stall during derating by dynamically adjusting the pitch of the rotor blades based on real-time conditions, ensuring continued operation without excessive loads on turbine components, even in low air density conditions.
Implementation Method 1
The rotor blades capture kinetic energy of wind using known airfoil principles
Implementation Method 2
A pitch bearing is typically configured operably between the hub and the rotor blade to allow for rotation about a pitch axis
Data Source
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AI summary
A method 100 for operating a wind turbine 10 to avoid stall during derating thereof includes providing 102 an initial pitch setting for one or more rotor blades 22 of the wind turbine 10. Further, the method 100 includes operating 104 the wind turbine 10 based on a rated power curve with the one or more rotor blades 22 fixed at the initial pitch setting. Further, the method 100 includes identifying 106 at least one condition of the wind turbine 10 that is indicative of stall. The method 100 also includes derating 108 the wind turbine 10. Further, the method 100 includes modifying 110 the initial pitch setting to an updated pitch setting when the at least one condition is identified.