Floating Hub Mooring Layout for Stable Offshore Power Groups
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Solution Overview
Problem
Existing mooring arrangements for floating wind turbines in deep water are unstable, leading to excessive movement and fatigue in power transfer cables, and the water column becomes congested with mooring lines, increasing the risk of clashes and failures.
Innovation Solution
A floating power-generation group comprising a floating hub anchored to subsea foundations by anchor lines, with power producer units connected mechanically and electrically to the hub via inward and outward mooring lines, and optionally sharing subsea foundations, allowing for stable power transfer and reduced seabed clutter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional mooring arrangements are used in deep water, then the structure can be simple, but stability is insufficient leading to excessive movement
Solution Approach 1:
The mooring system is divided into multiple independent mooring lines radiating from the floating structure to different anchor points on the seabed. This segmentation allows each line to independently contribute to stability while distributing mechanical loads, enabling stable mooring in deep water without requiring a single complex anchor system
Solution Approach 2:
The invention transitions from shallow-water horizontal mooring to deep-water three-dimensional mooring by extending anchor lines vertically and diagonally across the water column. This dimensional change allows anchors to be placed on the seabed far from the structure while maintaining stability through the radial geometric configuration
2Productivity
If multiple floating wind turbines are grouped together, then power generation capacity increases, but the water column becomes congested with mooring lines
Solution Approach 1:
Each floating turbine is equipped with its own dedicated mooring lines and anchor points, creating localized stable zones around each structure. This local quality approach prevents mooring line interference between adjacent turbines while allowing high-density grouping for increased power generation capacity
Solution Approach 2:
Multiple mooring lines from different turbines are combined and shared at the seabed anchor level, where anchor lines from adjacent turbines can terminate at common anchor points or closely spaced foundations. This merging reduces the total number of anchor points required while maintaining individual turbine stability
3Force
If turbines are allowed to move excessively, then mooring line tension is reduced, but fatigue in power transfer cables increases
Solution Approach 1:
The radial mooring arrangement with multiple tensioned lines pre-establishes a stable geometric configuration that cushions and distributes dynamic loads from wave action and turbine movement. This prior cushioning through geometric stability prevents excessive movements that would cause cable fatigue while maintaining appropriate mooring line tensions
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 solution provides stable power transfer and reduces seabed congestion, enabling deep-water stability and efficient power generation and storage, accommodating large turbines and high-voltage umbilicals, while minimizing engineering costs and installation complexity.
Implementation Method 1
The anchor lines and/or the mooring lines may, for example, be catenaries or taut legs that are held in tension by buoyant upthrust of the hub and/or the power producer units.
Data Source
AI summary
A floating power-generation group comprises a floating hub such as a spar buoy that is anchored to subsea foundations by anchor lines. Floating power producer units such as wind turbines are connected electrically and mechanically to the hub. The power producer units are each moored by mooring lines. At least one mooring line extends inwardly toward the hub to effect mechanical connection to the hub and at least one other mooring line extends outwardly toward a subsea foundation. The groups are combined as a set whose hubs are connected electrically to each other via subsea energy storage units. Anchor lines of different groups can share subsea foundations. The storage units comprise pumping machinery to expel water from an elongate storage volume and generating machinery to generate electricity from a flow of water entering the storage volume. The pumping machinery can be in deeper water than the generating machinery.