Electrolysis Power Conversion with VSC and DC/DC Voltage Control
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Solution Overview
Problem
Existing electrolysis systems for industrial-scale hydrogen production face high complexity, cost, and operational limitations due to the use of thyristor-based rectification, which leads to substantial grid system perturbations, increased filtering requirements, and restricted operational flexibility.
Innovation Solution
An electrolysis system utilizing a voltage source converter (VSC), particularly a modular multilevel converter (MMC), with DC/DC converters and bridging switches, enables efficient and flexible power control for multiple electrolysis installations, reducing complexity and costs while minimizing grid system perturbations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If thyristor-based rectification is used for grid connection, then high DC power can be supplied to electrolysis installations, but grid system perturbations and harmonic emissions increase substantially
Solution Approach 1:
The patent replaces the mechanical/thyristor-based rectification system with an IGBT-based voltage source converter. This substitution eliminates the harmful harmonic emissions and grid perturbations associated with thyristor switching while maintaining the capability to supply high DC power to the electrolysis installations.
Solution Approach 2:
The invention changes the operating parameters of the power conversion system by using IGBTs with pulse-width modulation instead of thyristors with phase control. This parameter change enables sinusoidal current injection into the grid and clean DC output, resolving the contradiction between power supply capability and grid quality.
2Power
If multiple parallel-connected rectifier systems are employed, then high DC power demand can be met, but system complexity and filtering requirements increase substantially
Solution Approach 1:
The patent merges multiple rectifier functions into a single IGBT-based voltage source converter. This consolidation eliminates the need for multiple parallel rectifier systems and their associated complex filtering arrangements, while still meeting the high DC power demand through the converter's inherent capability and parallel-connected electrolysis installation architecture.
3Reliability
If thyristor systems are used for proven reliability, then operational stability can be achieved, but operational flexibility and energy efficiency are restricted
Solution Approach 1:
The invention introduces dynamic control capabilities through IGBT-based voltage source conversion, enabling real-time adjustment of power flow, voltage, and current characteristics. This dynamic operation maintains reliability while significantly improving operational flexibility compared to the static thyristor system.
Solution Approach 2:
The patent implements feedback control in the IGBT-based converter system, allowing continuous monitoring and adjustment of operating parameters. This feedback mechanism ensures stable operation while enabling flexible adaptation to different operating conditions, resolving the contradiction between reliability and flexibility.
4Power
If thyristor-based rectification is employed, then industrial-scale power supply is achievable, but additional costs for filtering systems and operation increase substantially
Solution Approach 1:
The patent replaces the costly thyristor-based rectification and filtering infrastructure with an IGBT-based voltage source converter. This substitution eliminates the need for expensive filtering systems while maintaining industrial-scale power supply capability, thereby reducing both installation and operational costs.
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 system achieves energy-efficient operation with improved flexibility, reduced costs, and enhanced operational security by using IGBT-based converters, allowing for bidirectional power transfer and network services, while minimizing harmonic emissions and reactive power demand.
Implementation Method 1
a voltage source converter (VSC) is connected at a network connection point, in particular a modular multilevel converter (MMC), which converts an input-side AC voltage into the output-side first DC voltage at the DC voltage output
Implementation Method 2
each electrolysis installation is respectively connected via a DC/DC converter which converts the first DC voltage into a second DC voltage
Implementation Method 3
by means of electrolysis, hydrogen and oxygen can be obtained from water
Data Source
AI summary
An electrolysis system has at least two electrolysis installations, a power supply source with a direct voltage output, and a central supply line connected to the direct voltage output. A direct current, at a first direct voltage, can be fed into the central supply line. The electrolysis installations are connected electrically in parallel to the central supply line. For a direct voltage supply from the public power grid a central voltage source converter converts an input-side alternating voltage into the output-side first direct voltage at a direct voltage output. Each electrolysis installation is connected via a DC/DC converter that converts the first direct voltage into a second direct voltage, parallel to the direct voltage output so that the second direct voltage drops across the electrolysis installation. Each of the DC/DC converters can be controlled and/or regulated for adapting a level of its second direct voltage.