Wind Turbine Speed Control Decoupling Tower Vibration

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Solution Overview

Problem

Existing wind turbine speed control methods stimulate tower vibrations, leading to undesirable loads and interference with the structural integrity of wind turbines, as they fail to decouple the disturbance caused by tower vibrations from the speed control system.

Innovation Solution

A method that determines the aerodynamic tower oscillation performance by calculating the difference between apparent wind power and pure wind power, allowing for precise control of wind turbines and decoupling the disturbance variable, thereby reducing the stimulation of tower vibrations and minimizing the need for damping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If speed control is used to optimize rotor performance, then rotor speed control is improved, but tower vibrations are excited and structural integrity deteriorates

Engineering Contradiction:
Improverotor speed controlVSAvoidtower vibrations
Core Design Contradiction:
SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the harmful disturbance component (tower vibration) from the speed control system by calculating apparent wind speed that compensates for tower head motion. This separates the useful speed control function from the harmful vibration excitation, allowing optimized rotor performance without tower vibration penalties.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces an intermediary calculation step that determines apparent wind speed by combining measured wind speed with tower head speed compensation. This intermediary variable serves as a mediator between the speed control system and the actual aerodynamic conditions, preventing direct coupling that causes tower vibrations.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If tower vibrations are damped by adjusting blade pitch, then tower vibration is reduced, but rotor performance and speed control deteriorate

Engineering Contradiction:
Improvetower vibration dampingVSAvoidrotor performance
Core Design Contradiction:
Object-affected harmful factorsVSProductivity

Solution Approach 1:

The patent converts the harmful tower vibration into a useful compensation signal. By measuring tower head speed and using it to calculate apparent wind speed, the system transforms the vibration disturbance into a corrective term that improves speed control accuracy without requiring additional pitch adjustments for damping.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Strength

If blade pitch is adjusted to compensate for tower vibration, then tower load is reduced, but pitch control precision and response time deteriorate

Engineering Contradiction:
Improvetower loadVSAvoidpitch control precision
Core Design Contradiction:
StrengthVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by pre-calculating the apparent wind speed compensation based on tower head speed before pitch control is needed. This anticipatory approach provides accurate wind speed information in advance, allowing smooth pitch adjustments that reduce tower loads without sacrificing control precision or response time.

Inventive Principle:
Principle #10Preliminary action

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 approach enables more precise and rapid control of wind turbines, reducing unnecessary pitch movements and loads, and effectively decouples the control system from tower vibrations, minimizing the importance of damping tower vibrations.

Implementation Method 1

an aerodynamic rotor with rotor blades adjustable in their pitch angle, which generates a rotor thrust

Methodology Applied
Scientific EffectAerodynamic: Aerofoil

Implementation Method 2

As the tower swings forward, the relative wind speed increases by the component of the tower head speed (and vice versa)

Methodology Applied
Scientific EffectRelative motion:

Data Source

PatentEP3931438B1Method for operating a wind turbine, controller structure, wind turbine and wind farm
Publication Date: 2024.04.10 WOBBEN PROPERTIES GMBH
  • EP3931438B1 patent drawingFigure 1
  • EP3931438B1 patent drawingFigure 2~3
  • EP3931438B1 patent drawingFigure 4

AI summary

The present invention relates to a method (600) for operating a wind turbine (100), the wind turbine (100) having a tower (102) with external tower loads acting thereon, and an aerodynamic rotor (106) having rotor blades (108) the pitch angle of which is adjustable, which rotor generates a rotor thrust, the method (600) comprising the following steps: determining (610) a speed of a tower head (v TK ) of the tower and/or of a nacelle of the wind turbine (100); determining (620) an absolute wind speed (v w ) in the area of the wind turbine (100); determining (630) a pure wind power (P wind ) on the rotor on the basis of the absolute wind speed (v w ); determining (640) an apparent wind power (P apparent ) on the rotor on the basis of the speed of the tower head and/or of the nacelle; determining (650) an aerodynamic tower vibration power (P AT ) on the basis of a difference between the apparent wind power (Papparent) and the pure wind power (P wind ); and controlling (660) the wind turbine using the aerodynamic tower vibration power (P AT ).