DC Circuit Breaker Topology for Fault and Load Current Interruption
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Solution Overview
Problem
Existing direct-current circuit breakers face challenges in interrupting both fault currents and load currents with a simple configuration, particularly in high-voltage direct current (HVDC) power transmission, as they struggle to manage residual voltages after current interruption, leading to arc-regeneration issues.
Innovation Solution
A direct-current circuit breaker design that incorporates a fault current interrupter and a load current interrupter, utilizing a shared resonant circuit with a capacitor and reactor, allows for both fault and load current interruption through separate methods: forced extinction for fault currents and self-excited oscillation for load currents, with a control circuit managing operations to minimize residual voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a direct-current circuit breaker uses a single interrupter with a shared resonant circuit to interrupt both fault currents and load currents, then the configuration becomes simpler, but the interrupter must handle much higher residual voltages from fault current interruption which causes arc-regeneration issues
Solution Approach 1:
The patent divides the circuit breaker into two separate interrupters: a fault current interrupter for interrupting fault currents and a load current interrupter for interrupting load currents. This segmentation allows each interrupter to be optimized for its specific function, with the fault current interrupter handling high-voltage fault interruption and the load current interrupter handling lower-voltage load interruption, thereby preventing arc-regeneration issues while maintaining overall system functionality.
Solution Approach 2:
The patent employs a shared resonant circuit that serves dual purposes: it assists the fault current interrupter in creating current zero points for fault current interruption, and it assists the load current interrupter in creating current zero points for load current interruption. This multi-functional resonant circuit reduces overall device complexity while maintaining the benefits of separate interrupters.
2Speed
If a direct-current circuit breaker is designed to interrupt fault currents by the forced extinction method, then fast interruption capability is achieved, but the capacitor retains much electric charge when interrupting load currents, leading to high residual voltages
Solution Approach 1:
The patent segments the interruption functions between two separate interrupters. The fault current interrupter uses the forced extinction method with the resonant circuit for fast fault current interruption. The load current interrupter uses a different method where the resonant circuit is configured to minimize residual voltage. This segmentation allows each interrupter to be optimized for its specific current type without compromise.
Solution Approach 2:
The patent changes the operational parameters of the resonant circuit based on the type of current being interrupted. For fault current interruption, the resonant circuit operates in forced extinction mode with specific capacitance and inductance values optimized for fast interruption. For load current interruption, the resonant circuit parameters are adjusted or reconfigured to minimize residual voltage and energy loss.
3Reliability
If separate circuit breakers are provided for fault current interruption and load current interruption, then each can be optimized for its specific function, but the overall configuration becomes more complex
Solution Approach 1:
The patent segments the interruption functions into two separate interrupters, each optimized for its specific function. The fault current interrupter is designed specifically for high-voltage fault interruption, while the load current interrupter is designed for lower-voltage load interruption. This segmentation improves reliability by ensuring each interrupter is properly optimized.
Solution Approach 2:
The patent implements multi-functionality through a shared resonant circuit that serves both the fault current interrupter and the load current interrupter. This shared component reduces overall device complexity by eliminating the need for separate resonant circuits for each interrupter, while still allowing each interrupter to be optimized for its specific function.
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 both fault and load currents with a simpler configuration by optimizing the resonant circuit for both types of currents, reducing the need for separate circuit breakers and minimizing arc-regeneration.
Implementation Method 1
The capacitor and the reactor constitute a resonant circuit... superimposing a resonant current generated by discharging the capacitor on a direct current
Implementation Method 2
an oscillating current, which is generated by interaction of an arc of the load current interrupter (4) and the resonant circuit
Implementation Method 3
When the load current interrupter (4) is opened, an oscillating current is generated by interaction of an arc of the load current interrupter (4) and the resonant circuit
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A direct-current circuit breaker (1) interrupts a direct current flowing through a direct-current line (2). The direct-current circuit breaker (1) includes a fault current interrupter (3), which is a first interrupter, and a load current interrupter (4), which is a second interrupter, connected in series with each other, and a capacitor (5) and a reactor (6) connected in parallel with the fault current interrupter (3) and the load current interrupter (4). Upon occurrence of a fault on the direct-current line (2), the fault current interrupter (3) performs an opening operation in accordance with a command input to the fault current interrupter (3). In a steady state in which a direct current flows to a load connected with the direct-current line (2), the load current interrupter (4) performs an opening operation in accordance with a command input to the load current interrupter (4).