Galvanically Isolated DC Link for Electrolysis Power Decoupling

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Solution Overview

Problem

Existing systems for connecting renewable energy sources to electrolysis plants require multiple conversions between AC and DC, leading to efficiency losses, increased costs, and power quality issues due to voltage distortions and circular currents.

Innovation Solution

A direct current transmission and distribution network using bidirectional galvanically isolated DC-DC converters to connect electrolysis plants directly to renewable energy sources, decoupling them from the AC grid and allowing flexible power management and operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If multiple AC-DC converter systems are used to connect renewable energy sources to electrolysis plants, then the electrolysis plants can receive DC power from the AC grid, but conversion losses increase and system efficiency decreases

Engineering Contradiction:

Improveconversion lossVSAvoidnumber of converter stages

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The invention extracts and eliminates the unnecessary AC-DC conversion stages from the power transmission system. By directly connecting renewable energy sources (which generate DC power) to DC loads (electrolysis plants) through a DC transmission network, the patent removes the redundant AC conversion环节, thereby reducing conversion losses and simplifying the overall system architecture.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of following the conventional AC grid distribution path (DC-AC-DC), the invention inverts the approach by establishing a direct DC transmission path from renewable energy sources to DC loads. This inversion eliminates the need for AC conversion and fundamentally changes the power transmission architecture to be more efficient.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If AC-DC converters are used to supply electrolysis systems, then power can be converted from AC to DC, but voltage distortions are introduced that degrade power quality

Engineering Contradiction:

Improvepower qualityVSAvoidvoltage distortion

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The invention converts the harmful voltage distortions generated by AC-DC converters into a beneficial situation by completely eliminating the converters from the system. By establishing direct DC connections between renewable energy sources and electrolysis plants, the system transforms the problematic AC-DC conversion process into a clean DC transmission approach, thereby eliminating the source of voltage distortions and improving power quality.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Productivity

If multiple electrolysis systems are connected in parallel to the AC grid, then large-scale hydrogen production is enabled, but circular currents cause equipment corrosion

Engineering Contradiction:

Improvehydrogen production capacityVSAvoidequipment corrosion

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The invention introduces a DC transmission network as an intermediary between renewable energy sources and parallel-connected electrolysis systems. This DC network acts as a mediator that enables multiple electrolysis systems to operate in parallel for large-scale hydrogen production while preventing circular currents from forming, thereby eliminating the corrosion problem that would otherwise occur with AC grid connections.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Ease of manufacture

If AC power grid connection is used for electrolysis plants, then power supply is available, but the number of conversion stages increases leading to higher costs

Engineering Contradiction:

Improvesystem costVSAvoidnumber of conversion stages

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The invention extracts and removes the unnecessary AC-DC conversion stages from the power supply chain. By directly connecting DC-powered electrolysis plants to DC sources (renewable energy systems) through a DC transmission network, the patent eliminates redundant conversion equipment, thereby reducing system complexity and lowering overall manufacturing and operational costs.

Inventive Principle:

Principle #2Taking out (Extraction)

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

Enhances power quality, reduces conversion losses, and enables efficient partial load operation of electrolysis systems, while minimizing grid disruptions and equipment corrosion.

Implementation Method 1

bidirectional galvanically isolated DC-DC converters

Methodology Applied

Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Data Source

PatentEP4611206A1Direct current transmission and distribution network and galvanically isolated connected electrolysis plant

Publication Date: 2025.09.03 SIEMENS ENERGY GLOBAL GMBH & CO KG

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AI summary

A direct current transmission and distribution network (100) comprises a plurality of DC-based network units (102) comprising a set of direct current loads (104) and a set of DC power supplies (106), and a direct current link (108) connects the DC-based network units (102). The DC-based network units (102) are connected to the direct current link (108) via their bidirectional galvanically isolated DC-DC converters (110).