Shared Semiconductor DC Breaker for Multi-Line Fault Interruption
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Solution Overview
Problem
Existing DC circuit breakers for multi-terminal DC transmission systems require multiple high-voltage semiconductor breakers, which are expensive, due to the need for creating a current zero point in DC power transmission systems without a natural zero crossing point.
Innovation Solution
A DC circuit breaker design that includes a plurality of DC power transmission lines branching into auxiliary lines, with a shared semiconductor breaker and energy consumption unit, utilizing mechanical contacts and commutation units to interrupt fault currents and consume surplus energy, reducing the need for multiple high-voltage semiconductor breakers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple high-voltage semiconductor breakers are provided for each DC power transmission line, then fault current interruption capability is improved, but system cost increases significantly
Solution Approach 1:
Multiple DC power transmission lines are merged to share a common semiconductor breaker through auxiliary lines and DC buses. The auxiliary lines branch from each DC power transmission line and connect to common DC buses, which then connect to the shared semiconductor breaker. This merging approach allows one semiconductor breaker to protect multiple transmission lines, significantly reducing the total number of semiconductor breakers needed while maintaining fault current interruption capability across all lines.
Solution Approach 2:
The shared semiconductor breaker is designed to perform multiple functions: it can interrupt fault currents from any of the multiple DC power transmission lines that connect to it through the auxiliary lines and DC buses. This multi-functionality allows a single semiconductor breaker to replace what would traditionally require multiple dedicated breakers, reducing system cost while maintaining comprehensive protection capability.
2Device complexity
If a shared semiconductor breaker configuration is used, then system cost is reduced, but the ability to interrupt fault currents in specific lines may be compromised
Solution Approach 1:
The system is segmented into auxiliary lines for each DC power transmission line that connect to common DC buses. This segmentation allows the shared semiconductor breaker to selectively interrupt fault currents from specific lines by controlling the auxiliary line connections. When a fault occurs on a particular line, the semiconductor breaker can isolate that line through the auxiliary line configuration while maintaining power transmission on other lines, thus preserving both cost efficiency and selective fault interruption capability.
3Device complexity
If mechanical contacts are used without active current zero point creation, then device simplicity is improved, but DC fault current cannot be interrupted
Solution Approach 1:
The semiconductor breaker acts as an intermediary device between the DC power transmission lines and the mechanical contacts. It actively creates a current zero point by controlling the commutation of DC current to AC current through the auxiliary lines and transformers, enabling the subsequent mechanical contacts to successfully interrupt the current. This intermediary approach combines the simplicity of mechanical contacts with the active current zero point creation capability of semiconductor devices.
Solution Approach 2:
The system changes the current parameters from DC to AC through the semiconductor-controlled commutation process. By converting DC current to AC current with zero crossing points, the mechanical contacts can naturally interrupt the current at these zero points. This parameter change enables the use of simpler mechanical contacts while maintaining effective current interruption capability that would be impossible with pure DC currents.
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
Enables efficient interruption of fault currents in DC power transmission lines while minimizing the use of expensive semiconductor breakers, maintaining power transmission in faultless circuits, and effectively managing surge energy.
Implementation Method 1
a semiconductor breaker configured to interrupt a current flowing through the DC power transmission line
Implementation Method 2
an energy consumption element configured to consume at least energy between a first end of the semiconductor breaker and a second end opposite the first end
Implementation Method 3
The first DC bus connects a first terminal of the first mechanical contact belonging to each first auxiliary line to a first end of the interruption and consumption unit. The second DC bus connects a first terminal of the first mechanical contact belonging to each second auxiliary line to a second end opposite the first end of the interruption and consumption unit
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
According to an embodiment, a direct current (DC) circuit breaker includes a plurality of DC power transmission lines, an interruption and consumption unit, a plurality of opening and closing commutation units, a first DC bus, and a second DC bus. The DC power transmission line branches into a first auxiliary line and a second auxiliary line each having a first mechanical contact at a predetermined branch point. The interruption and consumption unit includes a semiconductor breaker configured to interrupt a current flowing through the DC power transmission line and an energy consumption element configured to consume at least energy between both ends of the semiconductor breaker. The opening and closing commutation unit corresponds to the first auxiliary line or the second auxiliary line. The first DC bus connects a first terminal of the first mechanical contact belonging to each first auxiliary line to a first end of the interruption and consumption unit. The second DC bus connects a first terminal of the first mechanical contact belonging to each second auxiliary line to the first end of the interruption and consumption unit and a second end opposite the first end.