Wind Turbine Blade Pitch Control for Tower Clearance
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Solution Overview
Problem
The increasing length of rotor blades in wind turbines has heightened the risk of collisions with the tower, necessitating a method to reduce this risk while minimizing annual energy production loss and main shaft loads.
Innovation Solution
A method that involves controlling the pitch angles of rotor blades individually based on bending moment measurements, allowing temporary adjustments only when maximum allowed bending moments are exceeded in critical sectors near the tower, thereby reducing deflection and collision risk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the length of rotor blades is increased, then the energy capture capability is improved, but the risk of collision with the tower increases
Solution Approach 1:
The patent applies dynamic pitch angle adjustment during rotor blade rotation. The pitch angle is not fixed but dynamically changed based on the blade's position in its rotation cycle, specifically increasing the pitch angle when the blade is in the critical sector near the tower to reduce deflection and collision risk, while maintaining optimal pitch angles during other phases to preserve energy capture capability.
Solution Approach 2:
The patent changes the pitch angle parameter dynamically during operation. By modifying the pitch angle from its optimal value to a higher value (reducing the angle of attack) when the blade approaches the tower, the system alters the blade's aerodynamic characteristics to reduce bending moment and deflection, thereby preventing collision while maintaining overall energy production.
2Object-affected harmful factors
If pitch angles are controlled continuously to prevent collision, then collision risk is reduced, but annual energy production loss increases
Solution Approach 1:
The patent implements periodic pitch angle adjustment rather than continuous control. The pitch angle is modified only during the critical sector when the blade is near the tower, and returned to its optimal value afterward. This periodic intervention prevents collision only when needed, avoiding unnecessary energy loss during phases when the blade is not in danger of colliding with the tower.
Solution Approach 2:
The patent applies different pitch angle control strategies to different parts of the rotation cycle. The pitch angle is adjusted only in the critical sector (local region of high risk) while maintaining optimal values in non-critical sectors. This localized control approach ensures collision prevention where needed while preserving energy capture efficiency in safe operating zones.
3Object-affected harmful factors
If individual pitch angle control is implemented, then collision risk is reduced with minimal energy loss, but control system complexity increases
Solution Approach 1:
The patent segments the control strategy by implementing individual pitch angle control for each rotor blade independently. Each blade's pitch angle is adjusted based on its own position and bending moment, rather than controlling all blades uniformly. This segmentation allows precise collision prevention for each blade while keeping the control logic relatively simple and manageable.
Solution Approach 2:
The patent employs feedback control by continuously monitoring the bending moment of each rotor blade and using this information to adjust its pitch angle. The feedback loop compares the actual bending moment with acceptable limits and automatically adjusts the pitch angle accordingly, providing an intuitive and manageable control mechanism that reduces collision risk while maintaining clarity in system operation.
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
Effectively reduces the risk of rotor blade collisions with the tower while maintaining minimal annual energy production loss and reducing main shaft loads by dynamically adjusting pitch angles in real-time.
Implementation Method 1
The pitch angles of the rotor blades are changed in order to reduce a deflection of the rotor blades towards the tower when they pass the tower
Implementation Method 2
first information is representative for bending moments of the at least two rotor blades and the assigned positions of the rotor blades
Data Source
AI summary
The method is for operating a wind turbine having a rotor with at least two rotor blades, a tower and a pitch setting system. First information representative for bending moments of the at least two rotor blades and the assigned positions of the blades is provided. Second information representative for maximum allowed bending moments of blades when in a critical sector close to the tower is provided. Third information is determined depending on the first and second information representative for whether the bending moment of at least one rotor blade exceeds the maximum allowed bending moment when the blade is in the critical sector. If so, an output signal configured to cause the pitch setting system to individually change the pitch angles of the rotor blades in order to reduce a deflection of the blades towards the tower when they pass the tower is generated.