HVDC Circuit Breaker with Extraction Capacitor for Bidirectional Current Interruption
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Solution Overview
Problem
Conventional high-voltage direct current circuit breakers are complex, expensive, and unreliable, struggling to efficiently break bidirectional currents and requiring multiple IGBTs and complex charging loops, which increases production costs and control difficulties.
Innovation Solution
A high-voltage direct current circuit breaker design incorporating a coupling reactor with a reduced number of trigger modules, an energy-absorbing and voltage-limiting module, and a commutation branch circuit that uses a charging commutation module and commutation capacitor to produce high-frequency reverse currents for arc extinction, allowing for bidirectional current interruption and reduced production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If forced zero-crossing mechanical direct current circuit breakers use pre-charged capacitors to produce artificial current zero, then direct current can be extinguished, but the charging loop becomes complex in structure, large in size, difficult to control, and expensive to produce
Solution Approach 1:
The patent extracts the capacitor from the complex charging loop and connects it directly to the circuit breaker module. This simplifies the charging loop structure by eliminating intermediate charging components while maintaining the ability to produce artificial current zero for extinguishing direct current
Solution Approach 2:
The capacitor serves multiple functions: it is charged during normal operation and then discharged to produce reverse current for extinguishing both forward and reverse faults. This multi-functionality reduces the need for separate components for different fault conditions, simplifying the overall structure
2Reliability
If hybrid direct current circuit breakers use multiple IGBTs connected in series and parallel, then direct current can be interrupted, but the structure becomes bulky, expensive, unreliable, and difficult to control
Solution Approach 1:
The patent replaces the complex electronic switching system (multiple IGBTs) with a mechanical circuit breaker combined with a simpler capacitor-based commutation system. The mechanical switch provides reliable current interruption while the capacitor handles the commutation function, eliminating the need for multiple series-parallel IGBT configurations
Solution Approach 2:
The circuit breaker is divided into modular units with each module containing a mechanical switch and associated capacitor. This segmentation allows for simplified control of individual modules while maintaining the ability to handle high voltage and current through series connection of multiple modules
3Reliability
If conventional high-voltage direct current circuit breakers are designed to break heavy currents, then they meet system requirements, but they cannot break currents in a bidirectional way
Solution Approach 1:
The patent employs asymmetric capacitor connections where capacitors are connected in opposite polarities for different modules. This asymmetric configuration enables the system to handle both forward and reverse current faults by directing the discharge current in the appropriate direction, achieving bidirectional current breaking capability
Solution Approach 2:
For reverse fault conditions, the patent inverts the normal operation by discharging capacitors in the opposite direction to produce reverse current. This inversion technique allows the same hardware configuration to handle both forward and reverse faults, providing bidirectional current breaking capability
4Reliability
If conventional direct current circuit breakers use complex charging loops, then they can produce artificial current zero, but production costs increase significantly
Solution Approach 1:
The patent extracts the capacitor from the expensive complex charging loop and connects it directly to the circuit breaker module. This eliminates the need for complex charging infrastructure while maintaining arc extinction capability, significantly reducing production costs
Solution Approach 2:
The design uses relatively simple, cost-effective components like capacitors and mechanical switches instead of expensive power electronic devices. These components can be replaced if needed, providing a cost-effective solution that maintains reliability while reducing manufacturing costs
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 solution enables efficient, cost-effective bidirectional current interruption with reduced complexity and increased reliability, lowering production costs and simplifying control, while maintaining high-voltage and heavy current handling capabilities.
Implementation Method 1
The charging commutation module is configured to charge up the commutation capacitor and produces high-frequency reverse currents to cut off the mechanical switches
Implementation Method 2
The energy-absorbing and voltage-limiting module is configured to absorb the energy stored in inductive elements of power systems after a fault current is cut off to protect the mechanical switch
Data Source
AI summary
A direct current circuit breaker, including: n in number circuit breaker modules connected in series, one energy-absorbing and voltage-limiting module connected in parallel to the n in number circuit breaker modules, and a trigger module. The n in number circuit breaker modules each includes a mechanical switch and a commutation branch circuit which are connected in parallel; each commutation branch circuit includes a charging commutation module and a commutation capacitor which are connected in series; the charging commutation module is configured to charge up the commutation capacitor and produce reverse current to cut off the mechanical switch; the one energy-absorbing and voltage-limiting module is configured to absorb energy stored in inductive elements of power systems after a fault current is cut off, so as to limit voltage and protect the mechanical switch, and n is a positive integer greater than or equal to 1.