PV-to-Electrolyzer DC/DC Isolation for Ground Fault Scaling
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Solution Overview
Problem
Existing systems for connecting photovoltaic generators to electrolyzers using DC/DC converters face limitations in scalability and safety, particularly in large systems over 500 kW, where ground fault detection and isolation are challenging.
Innovation Solution
A device comprising an electrolyzer, a DC/DC converter, and at least one photovoltaic sub-generator, where the DC/DC converter feeds DC power to the electrolyzer via a DC bus, and includes disconnection mechanisms for fault current monitoring and isolation, enabling scalable and safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a DC/DC converter is used to connect PV generators to electrolyzers, then power conversion and matching is improved, but system complexity and grounding restrictions increase
Solution Approach 1:
The PV generator system is segmented into multiple independent PV sub-generators, each with its own disconnection capability. This allows individual modules to be isolated without affecting the entire system, reducing grounding complexity while maintaining power conversion flexibility through the DC/DC converter.
2Reliability
If PV generators are grounded via GFDI or operated ungrounded in large systems, then safety is improved, but system design flexibility is restricted
Solution Approach 1:
The grounding configuration is made dynamic through the introduction of disconnectors that can switch between grounded and ungrounded states. The first disconnector enables flexible grounding configuration, while the second disconnector provides dynamic isolation capability, allowing the system to adapt grounding based on operational requirements and fault conditions.
Solution Approach 2:
Disconnectors are introduced as intermediary devices between the PV sub-generators and the DC/DC converter. These intermediaries provide controlled access to grounding while maintaining safety isolation, thereby reconciling safety requirements with design flexibility.
3Power
If multiple PV sub-generators are connected to scale power output, then power supply capability is improved, but fault detection and isolation complexity increases
Solution Approach 1:
The system is divided into independently manageable PV sub-generators, each equipped with its own second disconnector and fault monitoring. This segmentation allows faults to be isolated at the individual sub-generator level without affecting other modules, simplifying fault detection and isolation in scaled systems.
Solution Approach 2:
Fault monitoring circuits provide continuous feedback on the status of each PV sub-generator. When a fault is detected in one sub-generator, the system automatically isolates only that specific module through its dedicated second disconnector, enabling simple and localized fault management even as the system scales.
4Productivity
If electrolyzers are supplied with high power from PV, then productivity is improved, but grounding and safety requirements become more stringent
Solution Approach 1:
The high-power PV system is segmented into multiple PV sub-generators that can be independently controlled and isolated. This segmentation allows the electrolyzer to receive high total power while maintaining simplified grounding and safety management at each individual sub-generator level, as faults can be isolated without shutting down the entire system.
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 solution allows for the highest possible power scaling from photovoltaics to electrolyzers while ensuring reliable ground fault detection and disconnection, enhancing safety and flexibility in large-scale systems.
Implementation Method 1
a photovoltaic (PV) sub-generator connected to the DC/DC converter
Implementation Method 2
In the case of water electrolysis, the decomposition of water into hydrogen and oxygen takes place
Data Source
AI summary
The disclosure relates to a device and associated method for electrolysis from photovoltaically generated DC power, including an electrolyzer and a DC/DC converter. The DC/DC converter feeds DC power to the electrolyzer, the DC power is generated by a photovoltaic (PV) sub-generator connected to the DC/DC converter. The PV sub-generator is connected to the DC/DC converter via a first disconnector that is coupled to an isolation monitoring structure in such a way that closure of the first disconnector requires a successful check for sufficient isolation of the PV sub-generator. The PV sub-generator has a main string and a second disconnector arranged between the main string and the first disconnector. The second disconnector is coupled to a fault current monitoring circuit in such a way that the second disconnector is opened in the event that a predefinable limit value of the fault current is exceeded.