Hybrid DC Breaker Simplifies Structure and Reduces Power Loss
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Solution Overview
Problem
Existing DC current breakers for high-voltage DC systems are complex and costly due to the need for numerous power semiconductor elements, leading to increased power loss and cooling requirements, especially when applied to super-high-voltage systems.
Innovation Solution
A DC current breaker configuration using three high-speed mechanical switches in series for the main conduction path, with a power semiconductor switch in parallel and a capacitor on a secondary commutate circuit, along with a surge arrester, to simplify the structure and reduce power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a hybrid DC breaker uses power semiconductor switches for main breaking, then short breaking time is achieved, but device complexity and cost increase due to needing many power semiconductor elements for super-high-voltage systems
Solution Approach 1:
The breaker is divided into two functional segments: a power semiconductor switch for current commutation and a mechanical switch for main breaking. This segmentation allows each component to perform its specialized function efficiently, with the mechanical switch handling the high-voltage main breaking without requiring multiple series-connected power semiconductor elements
Solution Approach 2:
The power semiconductor switch acts as an intermediary that facilitates current transfer from the main conduction path to the shunt path, enabling the mechanical switch to interrupt the current without direct arc exposure during normal operation. This intermediary role allows the mechanical switch to be optimized for high-voltage breaking without the complexity of power semiconductor series connections
2Speed
If power semiconductor switches are used in the main conduction path, then short breaking time is achieved, but power loss increases and cooling systems become burdensome
Solution Approach 1:
The conduction path is segmented such that the mechanical switch handles normal conduction without power loss, while the power semiconductor switch is only activated during fault conditions for current commutation. This segmentation minimizes the time the power semiconductor is conducting, thereby reducing overall power loss and cooling requirements
Solution Approach 2:
The power semiconductor switch operates periodically only during fault conditions rather than continuously, allowing the system to benefit from fast breaking capability when needed while minimizing power loss during normal operation when the mechanical switch handles conduction without significant losses
3Speed
If power semiconductor breakers are used, then breaking speed is improved, but adaptability to various systems decreases due to directionality requirements and surge current limitations
Solution Approach 1:
The mechanical switch is designed to perform multiple functions: normal current conduction, fault current breaking, and withstanding surge currents. This multi-functionality makes the breaker adaptable to various DC transmission systems without requiring directionality-specific configurations or surge current capacity limitations that constrain power semiconductor-based solutions
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 simplifies the breaker design, reduces power loss, and enhances surge current capability, making it more economical and reliable for high-voltage DC applications.
Implementation Method 1
a capacitor installed on a secondary commutate circuit which is a circuit connected in parallel to the two high-speed mechanical switches connected in series to each other in the main conduction path
Implementation Method 2
a surge arrester installed on a tertiary commutate circuit which is a circuit connected in parallel to the capacitor on the circuit connected in parallel to the two high-speed mechanical switches connected in series to each other in the main conduction path
Data Source
AI summary
Provided is a DC current breaker having a high-speed breaking function appropriate to a voltage-type converter and a DC current breaking method. In addition, provided is a DC current breaker and a DC current breaking method capable of reducing cost of the breaker and securing economical competiveness by using a relatively simple configuration. The DC current breaker for breaking a DC current at the time of occurrence of an accident includes: a main conduction unit including three high-speed mechanical switches installed to be connected in series to a main conduction path for conducting a normal-operation-state current; a power semiconductor switch installed to be connected in parallel to one high-speed mechanical switch among the high-speed mechanical switches installed in the main conduction unit for current breaking of the main conduction unit; a capacitor installed on a circuit connected in parallel to the main conduction path; and a surge arrester installed to be connected in parallel to the capacitor connected in parallel to the main conduction path. The DC current breaking method uses the DC current breaker.