Wind Turbine Tower Damping via Blade Flap Actuators
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Solution Overview
Problem
Existing methods for active tower damping in wind turbines, such as pitch angle changes, can strain pitch systems and lead to increased damage, particularly for large and heavy blades where pitch system capacity is a concern, making effective damping of tower oscillations challenging.
Innovation Solution
The implementation of add-on members on wind turbine blades that alter aerodynamic properties to reduce thrust and counteract tower movements, using measured acceleration signals to generate actuating signals for these members, thereby reducing tower oscillations without overloading the pitch system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If pitch angle changes are used for active tower damping, then tower oscillations are reduced, but pitch system capacity and pitch bearing capacity are exceeded
Solution Approach 1:
The patent introduces flaps as intermediary aerodynamic surfaces mounted on the blades, which serve as mediators to modify airflow and generate damping forces. These flaps act as a separate control mechanism that does not burden the pitch system, allowing tower damping to be achieved through flap deflection rather than pitch angle changes, thereby protecting the pitch system from overload.
Solution Approach 2:
The patent segments the control function by separating pitch control (for power regulation) from tower damping control. The flaps are independently controlled to provide damping forces, while the pitch system maintains its primary function. This segmentation allows each system to operate within its capacity limits without interfering with the other.
2Stability of the object's composition
If additional pitching is applied for tower damping, then tower oscillations are reduced, but pitch activity and pitch bearing damages increase
Solution Approach 1:
The flaps serve as intermediary elements that generate the necessary aerodynamic forces for damping without requiring the pitch system to act. By mounting flaps on the blades and controlling their deflection independently, the patent creates a dedicated damping mechanism that eliminates the need for additional pitch movements, thereby preventing pitch bearing damage.
Solution Approach 2:
The patent replaces the mechanical pitch system with an aerodynamic flap system for the specific function of tower damping. Instead of using the heavy mechanical pitch bearings to generate damping forces, the system uses aerodynamic forces generated by flap deflection, substituting a mechanical solution with an aerodynamic one that has no moving parts in the pitch bearing.
3Stability of the object's composition
If pitch system is used for tower damping in large and heavy blade designs, then damping is achieved, but pitch system capacity constraints are violated
Solution Approach 1:
The flaps act as intermediary aerodynamic surfaces that generate the necessary damping forces through airflow modification. By controlling flap deflection angles, the system can generate significant aerodynamic forces without requiring the pitch system to exert equivalent mechanical forces, thus solving the capacity constraint problem in large blade designs.
Solution Approach 2:
The patent changes the control parameter from pitch angle to flap deflection angle. This parameter change allows the system to achieve the same damping effect with a different actuation mechanism that has not reached its capacity limits, enabling effective damping in large and heavy blade designs where the pitch system would be overloaded.
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 method effectively reduces tower base loads and oscillations by adjusting thrust forces dynamically, minimizing stress on the pitch system and preventing damage, while maintaining optimal performance across various operating conditions.
Implementation Method 1
The flaps change an airflow to regulate a rotation speed of the rotor
Implementation Method 2
The add-on members will lower the thrust of the rotor when they are activated (similar to pitching the blade towards feather will lower the thrust in the traditional set up)
Implementation Method 3
filtering the time signal to extract at least one frequency component
Implementation Method 4
the active add-on members will apply a thrust change that will dampen the tower oscillation
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
The present invention is related to a device and a method of damping front and backward movements of a tower of a wind turbine, wherein the wind turbine comprises the tower and a rotor, the rotor being mounted at the top of the tower to rotate about a rotational axis in which the front and backward movements of the tower occur, and the rotor has a plurality of blades (15), wherein each blade has at least one corresponding active add-on member which is actuated by a corresponding actuator to alter aerodynamic properties of the blade. Each add-on member is actuated by the corresponding actuator (17) to alter the aerodynamic properties of the blade in a manner that the rotor is configured to damp the front and backward movements of the tower of the wind turbine.