Airborne Kite Cable Force Control for Wind Turbine Tower Fatigue

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Solution Overview

Problem

Modern wind turbines experience tower movements during operation and erection, leading to fatigue and potential damage, which existing mechanical dampers fail to effectively mitigate in a fast and reliable manner.

Innovation Solution

A method involving an airborne object, such as a kite or glider, coupled to a wind turbine via a cable, where parameters related to tower movements are measured and the cable force is adjusted to counteract these movements, reducing or dampening tower oscillations and fatigue.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If mechanical dampers are applied at or in wind turbines to reduce tower movements, then tower fatigue is reduced, but the response speed and reliability are insufficient

Engineering Contradiction:
Improvetower movement mitigation reliabilityVSAvoidresponse speed
Core Design Contradiction:
ReliabilityVSSpeed

Solution Approach 1:

The patent replaces mechanical dampers with an airborne object (kite or glider) coupled to the wind turbine via a cable. The airborne object uses aerodynamic forces instead of mechanical damping mechanisms to counteract tower movements, achieving faster response and higher reliability while enabling energy generation

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent dynamically adjusts the cable force by controlling the airborne object's position and orientation, changing the aerodynamic parameters to match the tower movement characteristics. This allows adaptive response to varying wind conditions and tower motion patterns, improving both speed and reliability

Inventive Principle:
Principle #35Parameter changes

2Reliability

If mechanical dampers are applied to dampen tower movements, then tower fatigue is reduced, but the system complexity and maintenance requirements increase

Engineering Contradiction:
Improvetower fatigue resistanceVSAvoiddamper system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the damping function from the tower structure itself and relocates it to an airborne object operating in the air space around the turbine. This removes complex mechanical dampers from the tower, reducing system complexity and maintenance needs while maintaining fatigue resistance

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The airborne object serves multiple functions simultaneously: it dampens tower movements, generates electrical energy, and requires minimal maintenance. The system uses natural wind and aerodynamic forces rather than requiring external power or complex control mechanisms, achieving self-service operation

Inventive Principle:
Principle #25Self-service

3Reliability

If airborne objects are used to counteract tower movements, then tower movements are reduced, but additional components and control systems are required

Engineering Contradiction:
Improvetower movement reductionVSAvoidcontrol system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The airborne object is designed to perform multiple functions: generating electrical energy and dampening tower movements simultaneously. This multi-functionality reduces the need for separate dedicated damping systems, offsetting the added complexity by consolidating functions into a single integrated component

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 efficiently reduces tower movements and associated fatigue by dynamically adjusting the cable force, providing a fast, reliable, and maintenance-friendly solution that can also generate electrical energy while counteracting tower movements.

Implementation Method 1

the airborne object may be capable of producing electrical energy... the energy of the wind is extracted by the wind turbine blades... converting the energy of the wind into mechanical energy

Methodology Applied
Scientific EffectAerodynamic lift: Aerofoil

Implementation Method 2

the airborne object is controlled in such a manner that movements of the tower of the wind turbine are counteracted

Methodology Applied
Scientific EffectAerodynamic drag: Drag

Implementation Method 3

adjusting a cable force of the cable acting on the wind turbine... the cable force is adjusted in such a manner that the movements of the tower are counteracted

Methodology Applied
Scientific EffectTension force: Tension

Data Source

PatentEP3743621B1A method for controlling an airborne object coupled to a wind turbine
Publication Date: 2022.03.23 VESTAS WIND SYSTEMS AS
  • EP3743621B1 patent drawingFigure 1
  • EP3743621B1 patent drawingFigure 2
  • EP3743621B1 patent drawingFigure 3

AI summary

A method of controlling an airborne object (2), such as a kite or a glider, is disclosed. The airborne object (2) may be an airborne energy generating system. The airborne object (2) is coupled to a part of a wind turbine (1), such as a nacelle (4), a tower (3) or a foundation, via a cable (7). At least one parameter related to movements (8) of the tower (3) of the wind turbine (1) is measured, and a cable force (9) of the cable (7) acting on the wind turbine (1) is adjusted, based on the at least one measured parameter. Thereby the tower movements (8) can be counteracted and fatigue can be reduced.