Shunt Inductances for HVAC Cable Reactive Power Compensation

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Solution Overview

Problem

Existing methods for subsea HVAC power transmission over long distances are inefficient due to reactive power generation, leading to reduced efficiency and high costs, with existing solutions being expensive and not well-suited for cost-effective transmission.

Innovation Solution

A power cable assembly with continuous conductors and shunt inductances connected at regular intervals to compensate for reactive power, providing a high voltage tuneable inductance that eliminates length limitations and avoids the need for subsea reactors or AC to DC converters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If shunt inductances are connected at regular intervals to compensate for reactive power, then transmission efficiency is improved and loss is reduced, but device complexity increases

Engineering Contradiction:
Improvereactive power lossVSAvoidcable assembly structure
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The cable assembly is segmented into multiple sections along its length, with shunt inductances connected at regular intervals. This segmentation allows reactive power compensation to be distributed throughout the cable rather than concentrated at single points, reducing overall reactive power loss while maintaining manageable device complexity through modular placement.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Shunt inductances serve as intermediary components connected between the conductor and neutral/ground. These inductances act as mediators that compensate for capacitive reactive power generated by the cable, improving transmission efficiency by reducing the net reactive power flow without requiring fundamental changes to the cable structure.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Loss of energy

If the conductor is divided into two parts separated by dielectric material to provide distributed capacitive compensation, then power loss is reduced, but manufacturing complexity increases

Engineering Contradiction:
Improvepower lossVSAvoidcable construction
Core Design Contradiction:
Loss of energyVSEase of manufacture

Solution Approach 1:

Instead of using distributed capacitive compensation by dividing the conductor (as in US 4204129), this invention inverts the approach by using shunt inductances connected to the continuous conductor. This inversion simplifies the manufacturing process while achieving the same goal of reducing power loss through reactive power compensation.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The invention extracts the compensation function from the cable insulation structure itself and implements it separately through shunt inductances connected to the conductor. This separation allows the conductor to remain continuous and simple to manufacture, while the compensation function is added as a distinct component.

Inventive Principle:
Principle #2Taking out (Extraction)

3Loss of energy

If subsea reactors are placed at the seabed at required intervals, then reactive power compensation is achieved, but cost and maintenance requirements increase

Engineering Contradiction:
Improvereactive power compensationVSAvoidsubsea component installation
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The shunt inductances are merged with the cable assembly itself, forming an integrated solution where the compensation components are part of the cable structure. This merging eliminates the need for separate subsea reactor installations, reducing both cost and maintenance requirements while achieving the same reactive power compensation.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The cable assembly is designed to serve multiple functions: power transmission and reactive power compensation. The shunt inductances integrated into the cable provide compensation functionality without requiring additional dedicated subsea equipment, making the solution more universal and cost-effective.

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

4Loss of energy

If DC transmission is used instead of AC to eliminate reactive power issues, then transmission efficiency is improved, but conversion cost and system complexity increase

Engineering Contradiction:
Improvereactive power lossVSAvoidconverter installation
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The AC cable system serves itself by providing reactive power compensation through integrated shunt inductances. This self-service capability allows the system to maintain transmission efficiency comparable to DC without requiring external conversion infrastructure, eliminating the need for expensive AC-DC converters while maintaining AC compatibility with existing grids.

Inventive Principle:
Principle #25Self-service

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

Enables efficient and cost-effective transmission of AC power over longer distances by effectively compensating for reactive power, reducing losses and eliminating the need for expensive subsea reactors or converters, making it suitable for offshore installations and subsea power transmission.

Implementation Method 1

Induction is used instead of capacitance, resulting in different constructional features. According to the new solution, the conductor for transmitting power is continuous

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3220503B1Shunt compensation of long HVAC cables
Publication Date: 2019.11.20 NEXANS SA
  • EP3220503B1 patent drawingFigure 1~2
  • EP3220503B1 patent drawingFigure 3~4
  • EP3220503B1 patent drawingFigure 5

AI summary

A power cable assembly for transferring high voltage alternating current over long distances. The assembly comprises continuous power cables 10 where each power cable 10 comprises a core 20, a conductor 30 and cable insulation 40. It further comprises shunt inductances 50 connected to each conductor 30 at regular intervals along each conductor 30. The invention further comprises a method for providing a power cable assembly for transferring high voltage alternating current over long distances by means of continuous power cables 10 where each power cable 10 comprises a core 20, a conductor 30 and cable insulation 40. The method is characterized in connecting shunt inductances 50 to each conductor 30 at regular intervals.