Floating Wind Turbine Yaw Motion Control via Blade Pitch
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Solution Overview
Problem
Floating wind turbines experience large amplitude, low-frequency motions due to their unmoored nature, which can reduce efficiency and cause structural stress, and existing control systems often result in negative damping, exacerbating vibrations.
Innovation Solution
A motion controller for floating wind turbines adjusts the blade pitch of each rotor blade to create net forces that counteract yaw, in-plane, and axial motions, using proportional and integral control actions to achieve simultaneous control of these motions, thereby reducing vibrations and maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If blade pitch is adjusted to maintain constant power output above rated wind speed, then power output is regulated, but thrust is reduced and damping force decreases leading to negative damping and exacerbated vibrations
Solution Approach 1:
The patent divides the blade pitch control into two independent components: collective pitch control for power regulation and individual blade pitch control for vibration suppression. This segmentation allows each control objective to be achieved without compromising the other, resolving the contradiction between maintaining constant power output and reducing vibrations above rated wind speed
Solution Approach 2:
The patent changes the control parameter from purely collective pitch adjustment to a combination of collective and individual blade pitch adjustments. By modifying the pitch parameters of individual blades based on their respective positions and the turbine's motion state, the system maintains constant power output while actively counteracting vibrations through differential pitch control
2Adaptability or versatility
If floating wind turbine structure is made buoyant and unmoored, then installation flexibility is improved, but large amplitude low-frequency motions occur reducing efficiency and causing structural stress
Solution Approach 1:
The patent implements dynamic blade pitch control that continuously adjusts pitch angles in response to real-time turbine motions. This dynamic control adapts to the floating turbine's large amplitude low-frequency motions, optimizing power capture efficiency and reducing structural stresses by actively counteracting excessive movements throughout the turbine's operational cycle
Solution Approach 2:
The patent employs feedback control mechanisms that use sensors to detect turbine motions and feed this information back to the pitch control system. The controller processes this feedback and adjusts blade pitch angles accordingly, creating a closed-loop system that maintains optimal efficiency while mitigating the adverse effects of floating motions on power output and structural integrity
3Productivity
If blade pitch is kept constant below rated wind speed for maximum power output, then power capture is optimized, but thrust increases with wind speed causing increased axial motions
Solution Approach 1:
The patent applies partial individual blade pitch adjustments in addition to collective pitch control. By introducing small differential pitch angles to individual blades below rated wind speed, the system maintains optimal power capture while partially counteracting the increased axial motions that result from higher thrust at elevated wind speeds
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 controller effectively dampens and stabilizes the wind turbine's motions, reducing structural stress and maintaining efficiency by dynamically adjusting blade pitch to counteract yaw, in-plane, and axial motions, even above rated wind speeds.
Implementation Method 1
the controller is arranged to adjust the blade pitch of each rotor blade so as to create a net force to control a motion of the floating wind turbine
Data Source
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AI summary
A motion controller for a floating wind turbine with a plurality of rotor blades, is arranged to control a motion of the floating wind turbine in a yaw direction. The controller adjusts the blade pitch of each rotor blade so as to create a net force to control the motions. The controller includes a control action which is proportional to a yaw offset angle and/or a control action which is proportional to an integral of the yaw offset angle.