Motion Compensating Pile Upender for Offshore Wind
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Solution Overview
Problem
Existing methods for installing monopiles for offshore wind turbines face challenges such as excessive loads on cranes and equipment during upending, and limited weather windows due to vessel motion and sea conditions.
Innovation Solution
The method involves operating controllable motion actuators of the motion compensating support assembly to provide controlled motion of the lower end portion of the monopile, reducing or counteracting swing motion during upending, thereby reducing loads on equipment and increasing the weather window for installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the monopile is upended by lifting the upper end portion by means of the crane, then the monopile can be installed in vertical orientation, but excessive loads are caused on the crane and motion compensating device during upending
Solution Approach 1:
The support assembly is made dynamically movable along the monopile length via motion actuators, allowing the support position to adapt during upending. This dynamic adjustment optimizes the load distribution and reduces peak loads on the crane by maintaining optimal leverage throughout the upending process
Solution Approach 2:
The position parameter of the support assembly is changed during the upending operation. By moving the support assembly along the monopile, the system changes the mechanical parameters (lever arms, support points) to minimize loads on the crane while maintaining control over the monopile's motion
2Ease of operation
If the monopile is upended in floating condition, then installation can proceed without jack-up operations, but swing motion of the monopile increases due to vessel motion
Solution Approach 1:
The motion actuators are controlled based on feedback from motion sensors that detect vessel motion and monopile position. This closed-loop control allows the support assembly to actively compensate for vessel motion, reducing monopile swing and improving stability during upending in floating condition
Solution Approach 2:
The motion compensating support assembly acts as an intermediary between the floating vessel and the monopile. It isolates the monopile from vessel motions by providing active compensation, allowing floating operation without excessive swing motion
3Stability of the object's composition
If controllable motion actuators are operated to provide controlled motion of the lower end portion, then swing motion is reduced, but device complexity increases
Solution Approach 1:
The motion actuators serve multiple functions: they position the support assembly along the monopile, compensate for vessel motion, and reduce swing during upending. This multi-functionality justifies the added complexity by consolidating multiple control requirements into a single integrated system
Data Source
Figure 1
AI summary
Installation of a monopile adapted to support an offshore wind turbine is done using a vessel comprising a hull, a crane mounted on the hull, and a motion compensating integrated pile upending and holding device. The device comprises a motion compensating support assembly mounted to the hull of the vessel and a pile holder that is supported by the support assembly and is tiltable about horizontal tilt axis relative to the support assembly between a horizontal orientation and a vertical orientation. The device allows for upending of the monopile by means of the crane of the vessel whilst the lower end portion remains received and supported by the pile holder. During at least a phase of the upending of the monopile, one or more of the controllable motion actuators of the motion compensating support assembly are operated to provide controlled motion of the lower end portion of the monopile so as to reduce swing motion of the monopile.