DC Circuit Breaker Merging Components for Compact Fault Interruption
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Solution Overview
Problem
Existing DC circuit breakers for power transmission line networks require a large number of components, leading to increased cost and size, as each transmission line needs a separate breaker to interrupt fault currents efficiently at coupling points of multiple DC power lines.
Innovation Solution
A compact DC circuit breaker design is implemented at the coupling point of three or more DC power transmission lines, utilizing a configuration of series circuits with mechanical contact type current disconnectors and commutation circuits, reducing the number of components by half through a delta-star connection and commutation circuit setup, allowing for efficient fault current interruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional DC circuit breaker is installed at each transmission line to interrupt fault currents, then fault current interruption capability is improved, but the number of components and device size increase
Solution Approach 1:
Multiple DC circuit breakers are merged into a single shared circuit breaker by connecting multiple transmission lines to a common busbar structure. The circuit breaker is shared among multiple lines, reducing the total number of breakers from one per line to one for all lines combined.
Solution Approach 2:
The circuit breaker is designed to serve multiple functions by protecting multiple transmission lines simultaneously. A single breaker handles fault current interruption for all connected lines, making the device universal rather than line-specific.
2Reliability
If a conventional DC circuit breaker is installed at each transmission line, then fault current interruption is achieved, but cost increases
Solution Approach 1:
Multiple expensive DC circuit breakers are replaced by a single shared breaker, directly reducing material costs, installation costs, and maintenance costs while maintaining fault protection capability across all transmission lines.
3Speed
If mechanical contact type current disconnectors are used, then high-speed current interruption is achieved, but conduction loss increases when semiconductor elements are used for large current flow
Solution Approach 1:
The current path is segmented into two distinct stages: a semiconductor element handles normal large current flow with low conduction loss, while a mechanical contact type current disconnector handles fault current interruption at high speed. Each component operates in its optimal performance range.
Solution Approach 2:
The semiconductor element acts as an intermediary that transfers normal operating current from the transmission line to the mechanical disconnector, allowing the mechanical disconnector to remain idle during normal operation and only activate when fault current interruption is required.
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
This configuration reduces the overall number of components and size of the circuit breaker, achieving a low-cost, compact solution capable of high-speed fault current interruption at multiple DC power transmission line coupling points.
Implementation Method 1
each of the wire connection circuits including a commutation circuit in which a current is commutated
Data Source
Figure 1(A)~1(B)
Figure 2(A)~2(C)
Figure 3
AI summary
A direct current circuit breaker is provided at a coupling point where three or more direct current power transmission lines (11 to 13) are electrically coupled in a direct current power transmission line network. The direct current circuit breaker includes three or more series circuits (2), each of the series circuit being connected to ends of two different direct current power transmission lines, and including a serial connection of two or more current disconnectors (21), and three or more wire connection circuits (3), one end of each of the wire connection circuits being connected to a middle point of the series circuit, and another end being connected to one point where other ends of the wire connection circuits are connected to, each of the wire connection circuits including a commutation circuit (31) in which a current is commutated.