DC Circuit Breaker Reclosing Using Parallel Resonance Branches
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Solution Overview
Problem
Conventional direct-current circuit breakers for HVDC transmission struggle with high-speed reclosing due to mechanical switch operation delays and capacitor recharging times, failing to meet the high-speed reclosing requirements similar to those for alternating-current circuit breakers.
Innovation Solution
A direct-current circuit breaker configuration that includes additional main circuit breakers and resonance circuits in parallel, along with a switch for high-speed reclosing, allowing for simultaneous operation without mechanical delays and immediate recharging of capacitors, enabling faster reclosing times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical switches are used as main circuit breaker and closing switch, then the direct-current circuit breaker can interrupt direct current, but the operation time becomes longer than required for high-speed reclosing
Solution Approach 1:
The circuit breaker is divided into two independent systems: a mechanical switch system (main circuit breaker and closing switch) for current interruption, and a power electronics system (IGBT module) for high-speed reclosing. Each system operates independently to fulfill its specific function, allowing the mechanical system to handle current interruption while the power electronics system achieves fast reclosing without being constrained by mechanical operation times.
Solution Approach 2:
The patent replaces the traditional mechanical reclosing mechanism with a power electronics-based reclosing system. The IGBT module and associated circuitry enable electronic switching for reclosing operations, which operates much faster than mechanical switches. This substitution eliminates the bottleneck of mechanical operation time while preserving the mechanical system's current interruption capability.
2Reliability
If capacitor of commutation circuit is charged in advance before main circuit breaker is opened, then current zero point can be formed, but the reclosing speed is limited by capacitor recharging time
Solution Approach 1:
The patent replaces the traditional capacitor-based commutation circuit with a power electronics-based commutation system using IGBT modules. This electronic commutation system can generate the necessary current zero point without requiring advance capacitor charging, eliminating the time delay associated with capacitor recharging and enabling faster reclosing operations.
Solution Approach 2:
The control system prepares the power electronics circuitry and IGBT modules in advance for reclosing operations, keeping them in a ready state that can immediately execute reclosing when needed. This eliminates the need to wait for capacitor charging while still ensuring the commutation circuit is prepared to form a current zero point when reclosing occurs.
3Speed
If additional main circuit breakers and resonance circuits are added in parallel, then high-speed reclosing capability is improved, but device complexity increases
Solution Approach 1:
The patent merges the commutation circuit functions with the reclosing circuit functions into a single integrated power electronics system. The IGBT module serves dual purposes: it performs commutation to form current zero points and simultaneously executes reclosing operations. This consolidation achieves high-speed reclosing while avoiding the complexity of completely separate additional circuits.
Solution Approach 2:
The power electronics circuitry and IGBT module are designed to perform multiple functions: current commutation, reclosing, and control. This multi-functional design eliminates the need for dedicated separate circuits for each function, reducing overall system complexity while maintaining high-speed reclosing 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
The proposed configuration enables direct-current circuit breakers to achieve high-speed reclosing in HVDC transmission, reducing operation times and addressing mechanical delay and recharging constraints, thus meeting or exceeding the 300 ms standard for high-speed reclosing.
Implementation Method 1
providing a commutation circuit including a capacitor and a reactor for superimposing a resonance current to thereby form a current zero point
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A direct-current circuit breaker (100) includes a main circuit breaker (1) inserted into a direct-current line (17), a resonance circuit (10) connected in parallel to the main circuit breaker (1), a MOSA (11) connected in parallel to the main circuit breaker (1) via the resonance circuit (10), a main circuit breaker (2) inserted into the direct-current line (18), a switch (4) connected in series to the main circuit breaker (2), a resonance circuit (20) connected in parallel to the main circuit breaker (2), and a MOSA (21) connected in parallel to the main circuit breaker (2) via the resonance circuit (20). The direct-current line (18) is a line that branches off from the direct-current line (17) and returns to the direct-current line (17). The switch (4) is inserted upstream of the direct-current line (18). A first switch circuit unit (30a) including a first auxiliary circuit breaker (31) and a second auxiliary circuit breaker (32) that are connected in parallel and a second switch circuit unit (30b) including a third auxiliary circuit breaker (33) and a fourth auxiliary circuit breaker (34) connected in parallel are inserted into the first direct-current line (17).