DC Circuit Breaker Commutation Circuit for Fast Low-Loss Interruption
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Direct-current circuit breakers face challenges in quickly breaking currents without significant conduction loss and high equipment costs, particularly in long-distance or underwater power transmission systems, where existing solutions either incur high conduction losses or increased equipment costs due to the use of semiconductor circuit breakers.
Innovation Solution
A direct-current circuit breaker design incorporating a mechanical circuit breaking section, a surge absorber, and a commutation device with a commutation circuit formed by a reactor, capacitor, and high-speed closing device, allowing for current breaking without the need for semiconductor circuit breakers, thereby reducing conduction losses and equipment costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a semiconductor circuit breaker is used to break direct current, then the current breaking speed is improved, but the conduction loss increases significantly
Solution Approach 1:
The circuit breaker is divided into two functional segments: a semiconductor circuit breaker for rapid current interruption and a mechanical contact type circuit breaker for normal current conduction. This segmentation allows each component to optimize its function, resolving the contradiction between breaking speed and conduction loss.
Solution Approach 2:
The system dynamically switches between two operational modes: during normal operation, the mechanical contact type circuit breaker conducts current with minimal loss; during fault conditions, the semiconductor circuit breaker rapidly interrupts the current. This dynamic switching resolves the contradiction by adapting the conduction path to the operational state.
2Loss of energy
If a hybrid circuit breaker with auxiliary semiconductor circuit breaker is used, then the conduction loss is reduced compared to full semiconductor solution, but the equipment cost and complexity increase
Solution Approach 1:
The invention extracts the semiconductor component's essential function (rapid current interruption) and separates it from the conduction function. The auxiliary semiconductor circuit breaker is taken out from the main conduction path, placing it only in the fault interruption path, thereby reducing conduction loss while maintaining breaking capability.
Solution Approach 2:
The mechanical contact type circuit breaker is pre-positioned in parallel with the semiconductor circuit breaker, ready to immediately assume the conduction path when the semiconductor breaker interrupts fault current. This preliminary arrangement reduces the need for complex switching mechanisms.
3Ease of manufacture
If mechanical contact type circuit breaker is used for direct current breaking, then the equipment cost is reduced, but the current breaking capability is insufficient
Solution Approach 1:
The semiconductor circuit breaker acts as an intermediary that enables direct current breaking capability. It facilitates the interruption of fault current by creating a high-impedance path, allowing the mechanical contact type circuit breaker to subsequently open without carrying fault current, thereby achieving reliable DC breaking with cost-effective mechanical components.
Solution Approach 2:
The invention replaces the mechanical arc extinction mechanism with a semiconductor-based current interruption mechanism. The semiconductor circuit breaker uses electronic switching to interrupt current, substituting the mechanical arc quenching process with a controllable electronic switching action, thereby enabling DC breaking capability.
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 design enables rapid current breaking with reduced conduction losses and lower equipment costs compared to traditional solutions, effectively addressing the limitations of existing direct-current circuit breakers.
Implementation Method 1
a commutation circuit that generates a commutation current for forcing the mechanical contact portion into a circuit-broken state, formed by connecting a reactor 211, a capacitor bank 221, and a closing device 241 in series
Implementation Method 2
a surge absorber 100 connected in parallel to the mechanical contact module 90
Implementation Method 3
The closing device 241 is a high-speed closing device
Implementation Method 4
The mechanical contact portion has a fixed contact and a movable contact. The operation mechanism is configured to bring the movable contact in and out of contact with the fixed contact
Implementation Method 5
The mechanical contact portion is electrically insulated from the ground. The sealed container encloses the mechanical contact portion and is filled with an insulation gas. The sealed container is electrically insulated from the ground
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A direct-current circuit breaker according to an embodiment comprises a mechanical breaking part, an arrester, and a commutation device. The mechanical breaking part lias at least one mechanical breaking unit. The at least one mechanical breaking unit has at least one unitized breaking part. Each of the at least one unitized breaking part has a mechanical contact section. All of the at least one unitized breaking part are connected in series to form a mechanical contact module. Both ends of the mechanical contact module are connected to a direct-current transmission system. The arrester is connected in parallel with the mechanical contact module. The commutation device has a commutation circuit. The commutation circuit is formed by connecting a reactor, a capacitor, and a closing device. The commutation circuit is connected in parallel with the mechanical contact module. The closing device is a high-speed closing device.