Transferable Crane for Floating Wind Turbine Component Maintenance

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Solution Overview

Problem

The maintenance of offshore wind turbines with increasing dimensions on floating foundations is challenging due to limited operational windows caused by sea-state induced motions, making it impractical to use stable jack-up vessels, and towing the entire turbine to shore is a slow process.

Innovation Solution

A transferable crane system is used on a floating foundation, comprising a revolving superstructure, boom, and hoisting winch, allowing for maintenance operations at sea by arranging the crane on buoyant stabilizing columns, reducing relative motion and enabling larger operational weather windows.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a stable jack-up vessel is used for maintenance operations, then the stability of the crane platform is improved, but the operational window is limited to calm seas and low wind speeds

Engineering Contradiction:
Improvestability of crane platformVSAvoidoperational window
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent introduces a motion compensation system as an intermediary between the crane and the sea state. This system includes sensors that detect platform motion and active compensation mechanisms that counteract these motions in real-time, allowing the crane to operate stably even when the vessel is moving due to waves and wind.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent transitions from a static stability approach (jack-up vessels that are stable only in calm conditions) to a dynamic stability approach. The crane system actively adapts to changing sea conditions through real-time motion compensation, enabling operational versatility across a wider range of weather conditions while maintaining crane stability.

Inventive Principle:
Principle #15Dynamics

2Ease of repair

If the entire floating wind turbine is towed to shore for maintenance, then maintenance operations can be performed, but the process is slow and time-consuming

Engineering Contradiction:
Improvemaintenance capabilityVSAvoidmaintenance time
Core Design Contradiction:
Ease of repairVSLoss of time

Solution Approach 1:

The patent extracts the maintenance capability from the shore-based facility and places it directly on the floating wind turbine platform. By mounting a crane system on the floating platform itself, the system enables maintenance operations to be performed at sea without requiring the time-consuming process of towing the entire turbine to shore.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent prepares the floating platform with a mounted crane system in advance, so that when maintenance is needed, the equipment is already in position and ready for immediate operation. This eliminates the delay associated with transporting maintenance equipment or the turbine itself to a suitable location.

Inventive Principle:
Principle #10Preliminary action

3Adaptability or versatility

If a floating crane vessel is used for maintenance at sea, then the operational flexibility is improved, but the relative motion between the crane and wind turbine increases due to sea-state induced motions

Engineering Contradiction:
Improveoperational flexibilityVSAvoidrelative motion between crane and turbine
Core Design Contradiction:
Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent merges the crane system with the floating wind turbine platform by mounting the crane directly on the platform structure. This integration ensures that the crane and turbine move together as a single unit, minimizing relative motion between them while maintaining the operational flexibility of working at sea.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent employs motion compensation systems as intermediaries that actively counteract sea-state induced motions. Sensors detect the platform's movement relative to the turbine, and the system applies compensating forces to maintain stable relative positioning, enabling precise maintenance operations despite wave and wind effects.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Facilitates maintenance of floating wind turbines at sea without towing, using smaller vessels, and reduces relative motion between the crane and turbine, allowing for efficient installation and removal of components like blades and generators.

Implementation Method 1

floating foundation that is in floating condition, e.g. at the site of an offshore windfarm

Methodology Applied
Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Data Source

PatentEP4402365B1Installation and/or removal of a wind turbine component for a floating foundation wind turbine
Publication Date: 2025.10.29 ITREC BV
  • EP4402365B1 patent drawingFigure 1
  • EP4402365B1 patent drawingFigure 2~3
  • EP4402365B1 patent drawingFigure 4

AI summary

For the installation and/or removal of a wind turbine component on or from an offshore wind turbine that has a tower erected on a floating foundation and in floating condition, e.g. at the site of an offshore windfarm, use is made of a transferrable crane. The transferrable crane comprises a revolving superstructure, a boom mounted or to be mounted to the revolving superstructure, a hoisting winch and associated hoisting cable departing from the boom to lift and/or lower a wind turbine component, e.g. a wind turbine blade.The method comprises - with the floating foundation in floating condition – the steps of:- arranging the transferable crane on the floating foundation,- using the transferable crane arranged on the floating foundation to lift and/or lower a wind turbine component, e.g. a wind turbine blade, e.g. for installing, removing, or replacing a wind turbine component of the offshore wind turbine, e.g. for performing maintenance,- removing the transferable crane from the floating foundation.