Gas-Insulated Converter Submodules for Compact High-Voltage Design

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Solution Overview

Problem

Conventional air-insulated power converters require significant space due to the need for considerable distances between submodules to prevent voltage flashovers, limiting their compactness and efficiency.

Innovation Solution

The use of gaseous substances within housings surrounding submodules to achieve higher dielectric strength per unit length, allowing for reduced distances between submodules and housings, thereby enabling a more compact design. This involves introducing a suitable gas, increasing its pressure, adjusting humidity, and controlling temperature to optimize dielectric strength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If air insulation is used in power converters, then the insulating material is simple and readily available, but the distance between submodules and housing must be considerable to prevent voltage flashovers, resulting in large space requirements

Engineering Contradiction:
Improvespace requiredVSAvoiddistance between submodules
Core Design Contradiction:
Quantity of substanceVSLength of stationary object

Solution Approach 1:

The patent changes the physical parameters of the insulating medium by using gas mixtures with higher dielectric strength than air, and by operating at elevated pressures (e.g., 3-10 bar), thereby reducing the required insulation distance while maintaining electrical safety

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite gas mixtures (e.g., SF6/N2, SF6/CF4, or other combinations) that combine the high dielectric strength of SF6 with the electrical stability and safety benefits of non-SF6 gases, achieving superior insulation performance compared to pure air

Inventive Principle:
Principle #40Composite materials

2Volume of moving object

If the distance between submodules is reduced to save space, then the power converter becomes more compact, but the risk of voltage flashovers increases with conventional air insulation

Engineering Contradiction:
Improvevolume of power converterVSAvoidprevention of voltage flashovers
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

By changing the dielectric strength parameter through gas composition and pressure adjustments, the system achieves reliable flashover prevention at reduced submodule spacing, allowing compact design without compromising electrical safety

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The system incorporates sensors and control mechanisms that monitor gas pressure, temperature, and humidity, automatically adjusting parameters to maintain optimal dielectric strength and prevent flashovers under varying operating conditions

Inventive Principle:
Principle #23Feedback

3Length of stationary object

If SF6 gas is used for insulation, then the dielectric strength is significantly increased allowing compact design, but the environmental harm and safety concerns increase

Engineering Contradiction:
Improveinsulation distanceVSAvoidenvironmental harm
Core Design Contradiction:
Length of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The patent uses composite gas mixtures that combine SF6 (providing high dielectric strength) with environmentally benign gases like N2, CO2, or CF4 (providing electrical stability and reduced environmental impact), achieving a balance between compactness and environmental safety

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The system applies different gas compositions to different regions or applications based on specific requirements - using higher SF6 content where maximum compactness is needed and lower SF6 content or alternative gases where environmental concerns are paramount

Inventive Principle:
Principle #3Local quality

4Quantity of substance

If the pressure of insulating gas is increased to enhance dielectric strength, then the insulation performance improves, but the complexity of pressure control and safety systems increases

Engineering Contradiction:
Improvedielectric strength per unit lengthVSAvoidpressure control system
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

The system incorporates automatic pressure regulation mechanisms that maintain optimal gas pressure without continuous external intervention, using pressure sensors and controlled gas injection or release systems that self-adjust based on measured conditions

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

The approach significantly reduces the space required for power converters, enabling more compact and efficient designs, particularly beneficial for high-voltage applications where conventional air insulation would otherwise necessitate extensive space.

Implementation Method 1

By introducing a suitable gaseous substance into the first housing and the second housing, a higher dielectric strength per unit length can be achieved than with air insulation

Methodology Applied
Scientific EffectDielectric strength: Dielectric Permittivity

Implementation Method 2

The arrangement has a pressure increasing device for increasing the pressure of the gaseous substance (compared to the external pressure prevailing outside the housing)

Methodology Applied
Scientific EffectPressure increase: Pressurisation

Implementation Method 3

The arrangement has a cooling device for reducing the temperature in the housings

Methodology Applied
Scientific EffectCooling: Cooling

Implementation Method 4

The arrangement has a humidification device for increasing the amount of water vapor trapped in the housings

Methodology Applied
Scientific EffectHumidification:

Data Source

PatentEP3245726B1Arrangement having a converter
Publication Date: 2022.12.14 SIEMENS ENERGY GLOBAL GMBH & CO KG
  • EP3245726B1 patent drawingFigure 1
  • EP3245726B1 patent drawingFigure 2
  • EP3245726B1 patent drawingFigure 3

AI summary

The invention relates to a first arrangement (1) comprising a converter (3), which has at least one phase module (15, 24, 31), an AC voltage connection (5), a first DC voltage connection (16), and a second DC voltage connection (17). A first phase module branch (11) is formed between the AC voltage connection (5) and the first CD voltage connection (16); a second phase module branch (13) is formed between the AC voltage connection (5) and the second DC voltage connection (17). Each phase module branch has at least two submodules (1_1, 1_2, 1_3, 2_1, 2_2, 2_3). The submodules (1_1, 1_2, 1_3) of the first phase module branch (11) are surrounded by a first housing (35) which is suitable for receiving a gaseous substance (88), and the submodules (2_1, 2_2, 2_3) of the second phase module branch (13) are surrounded by a second housing (37) which is suitable for receiving the gaseous substance (88).