Subsea Pressure Compensator With Integrated Transformer Retrieval

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Solution Overview

Problem

Existing subsea transformer systems have a high number of separate components, which complicates maintenance and retrieval, especially in the event of an auxiliary transformer failure.

Innovation Solution

A pressure compensator integrates transformer active parts and liquid-filled subsea transformers with pressure compensation and cooling functions into a single vessel, providing a double-barrier feature and minimizing components, allowing for separate retrieval and visual monitoring.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If auxiliary transformer is placed inside control pod, then space is optimized, but retrieval of entire pod is required in case of failure

Engineering Contradiction:
Improvespace utilizationVSAvoidretrieval complexity
Core Design Contradiction:
Volume of moving objectVSEase of repair

Solution Approach 1:

The patent separates the auxiliary transformer from the control pod by placing it inside the integrated pressure compensator vessel. This segmentation allows the auxiliary transformer to be part of a separately retrievable unit (the pressure compensator) rather than being permanently integrated into the control pod. In case of failure, only the pressure compensator containing the auxiliary transformer needs to be retrieved, not the entire control pod, thereby improving ease of repair while still optimizing space.

Inventive Principle:
Principle #1Segmentation

2Reliability

If separate external pressure compensator is used, then pressure compensation function is provided, but the number of components increases

Engineering Contradiction:
Improvepressure compensation functionVSAvoidnumber of components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the pressure compensation function with the transformer tank into a single integrated pressure compensator vessel. The bellows chamber is incorporated directly into the transformer tank structure, eliminating the need for separate external pressure compensators. This reduces the number of components while maintaining the reliability of pressure compensation through the integrated bellows mechanism that equalizes internal pressure with surrounding water pressure.

Inventive Principle:
Principle #5Merging (Combining)

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

This integration reduces the number of components, facilitates easier maintenance, and meets IEC subsea standards, ensuring reliable operation and compliance with environmental pressures and temperatures.

Implementation Method 1

the bellows chamber is configured to compensate for volume changes of the transformer active part

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

to equalize the internal pressure close to the surrounding water pressure

Methodology Applied
Scientific EffectPressure equalization: Pascal's Law

Implementation Method 3

the bellows chamber to be filled with a first insulation liquid

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 4

pressure compensator to equalize the internal pressure close to the surrounding water pressure

Methodology Applied
Scientific EffectHydraulic pressure equalization: Pascal's Law

Data Source

PatentEP4668297A1Pressure compensator and subsea transformer system
Publication Date: 2025.12.24 HITACHI ENERGY LTD
  • EP4668297A1 patent drawingFigure 1~3
  • EP4668297A1 patent drawingFigure 4
  • EP4668297A1 patent drawingFigure 5~7

AI summary

In at least one embodiment, the pressure compensator (1) is configured for subsea-use and comprises: - a first bellows chamber (21) configured to be filled with a first insulation liquid (61), - an electrical equipment (3) placed in the first bellows chamber (21), and - electrical feedthroughs (4) connecting the electrical equipment (3) with an exterior of the pressure compensator (1) .