Three-Core to Single-Core Submarine Cable Layout for Thermal Bottlenecks

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Solution Overview

Problem

Submarine power cables face a thermal bottleneck at landfall due to inefficient heat transfer, limiting their power capacity, and existing solutions like increasing conductor size or using copper materials have limitations.

Innovation Solution

A high voltage or extra high voltage submarine power cable system comprising a three-core cable connected to three single-core cables via a rigid joint, with improved cooling and reduced AC losses, using polymeric materials and non-magnetic armour wires, allowing for increased power capacity without increasing conductor size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the conductor size is increased to improve power capacity, then the power capacity increases, but the amount of cable material increases and cost increases

Engineering Contradiction:
Improvepower capacityVSAvoidcable material
Core Design Contradiction:
PowerVSQuantity of substance

Solution Approach 1:

The invention divides the three-core cable into three separate single-core cables. This segmentation allows each cable to be cooled independently and efficiently, particularly at the landfall section where thermal bottlenecks occur. By separating the cores, each cable can dissipate heat more effectively to the surrounding soil, enabling higher current density and power capacity without proportionally increasing material usage.

Inventive Principle:
Principle #1Segmentation

2Power

If copper conductor material is used instead of aluminium to improve power capacity, then the power capacity increases, but the cost and weight increase

Engineering Contradiction:
Improvepower capacityVSAvoidcable weight
Core Design Contradiction:
PowerVSWeight of moving object

Solution Approach 1:

The invention changes the thermal parameter (heat transfer efficiency) rather than the electrical parameter (conductor material). By improving the thermal coupling between the cable and surrounding soil through better burial depth and thermal management of separated single-core cables, the system achieves higher power capacity with aluminium conductors, avoiding the need to switch to heavier and more expensive copper while maintaining or improving power transmission capability.

Inventive Principle:
Principle #35Parameter changes

3Power

If the conductor size is increased to improve power capacity, then the power capacity increases, but the installation complexity and space requirements increase

Engineering Contradiction:
Improvepower capacityVSAvoidinstallation complexity
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The three-core cable is segmented into three separate single-core cables at the landfall section. This segmentation simplifies the thermal management and installation process, as each cable can be independently buried and cooled. The separated cables can be installed in standard burial configurations without requiring the complex handling and installation procedures needed for oversized multi-core cables, thereby reducing installation complexity while achieving higher power capacity.

Inventive Principle:
Principle #1Segmentation

4Loss of energy

If non-magnetic armour materials are used to reduce cable losses, then the AC losses decrease, but the mechanical strength and protection may be reduced

Engineering Contradiction:
ImproveAC lossesVSAvoidmechanical strength
Core Design Contradiction:
Loss of energyVSStrength

Solution Approach 1:

The invention uses composite armouring structures combining non-magnetic materials (such as stainless steel or aluminium armour wires) with protective polymeric layers. This composite approach reduces AC losses by eliminating magnetic hysteresis and eddy current losses in the armour, while the polymeric protective layers and proper armour wire selection maintain adequate mechanical strength and environmental protection for the cable system.

Inventive Principle:
Principle #40Composite materials

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 enhances the maximal power capacity of submarine power cables by improving cooling efficiency and reducing AC losses, enabling reduced material usage while maintaining the original power rating.

Implementation Method 1

an insulation layer comprising a first polymeric material

Methodology Applied
Scientific EffectElectrical insulation: Dielectric

Implementation Method 2

the cooling of the three single core submarine power cables by the surroundings is improved at landfall

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentEP4407637A1Three-core to three single core HV or EHV submarine power cable system
Publication Date: 2024.07.31 NKT HV CABLES AB
  • EP4407637A1 patent drawingFigure 1~2
  • EP4407637A1 patent drawingFigure 3~4
  • EP4407637A1 patent drawing

AI summary

A high voltage, HV, or extra high voltage, EHV, submarine power cable system (47) comprising: a three-core submarine power cable (1) comprising three stranded power cores, each comprising a respective conductor and an insulation system arranged around the conductor, comprising an inner semiconducting layer, an insulation layer comprising a first polymeric material, and an outer semiconducting layer, three single core submarine power cables (25), each comprising a respective conductor and insulation system arranged around the conductor, comprising an inner semiconducting layer, an insulation layer comprising the first polymeric material, and an outer semiconducting layer, and a rigid joint (49) connecting each power core of the three-core submarine power cable (1) to a respective one of the single core submarine power cables (25).