Stacked Mechanical Switching Units for Compact HVDC Circuit Breakers
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Solution Overview
Problem
Direct-current circuit breakers face challenges in increasing voltage without enlarging size and ensuring responsive interrupting operations, particularly in high-voltage direct-current transmission systems, where conventional mechanical contact type circuit breakers require larger sizes and increased insulating distances, leading to higher costs and reduced responsiveness.
Innovation Solution
A mechanical switching device for direct-current circuit breakers is designed with stacked mechanical switching units and insulating columns, where each unit includes high voltage and current interrupting contacts with sealed containers filled with insulating gases, and operation mechanisms that operate in opposite directions to minimize size and maximize voltage handling capability, while maintaining responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If conventional mechanical contact type circuit breakers are used for high-voltage direct-current transmission, then the voltage handling capability is improved, but the device size and weight increase significantly
Solution Approach 1:
The circuit breaker is divided into multiple independent switching units connected in series, where each unit handles a portion of the total voltage. This segmentation allows the overall voltage handling capability to be increased without proportionally increasing the size of each individual unit, as each unit can be optimized for its specific voltage portion.
Solution Approach 2:
The patent transitions from a single large-scale mechanical contact design to a multi-unit stacked configuration, effectively moving from a two-dimensional scaling approach to a three-dimensional modular arrangement. This allows voltage increase through vertical stacking of units rather than horizontal expansion of a single unit.
2Stress or pressure
If the insulating distance is increased to handle higher voltages, then the voltage handling capability is improved, but the device size increases
Solution Approach 1:
The total insulating distance requirement is segmented across multiple switching units, each with its own insulating structure. This distributes the insulation burden and allows each unit to be compact while the series connection achieves the total voltage insulation requirement.
Solution Approach 2:
The patent employs nested insulating structures where insulating columns and sealed containers are arranged concentrically and in overlapping configurations. This nesting allows multiple insulating functions to be achieved within a compact spatial footprint, reducing the overall insulating distance required for high voltage handling.
3Reliability
If the mechanical switching unit size is increased to improve interrupting performance, then the fault current interrupting capability is improved, but the device complexity and size increase
Solution Approach 1:
The fault current interrupting function is segmented across multiple switching units, where each unit contributes to the overall interrupting capability. This segmentation allows each unit to be simpler in design while the collective system achieves high interrupting performance through the series connection of multiple units.
Solution Approach 2:
The patent incorporates pre-charged capacitors and auxiliary switching mechanisms that prepare the system in advance for fault interruption. This preliminary action allows the main mechanical contacts to operate more efficiently by reducing the actual interrupting burden during fault conditions, thereby improving interrupting capability without requiring oversized mechanical components.
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 allows for easy voltage increase without significant size expansion, enhances interrupting performance, and maintains operational responsiveness by offsetting operational forces and reducing the need for extensive insulation, thus curbing the increase in size and weight of the circuit breaker.
Implementation Method 1
a sealed container which encloses the mechanical contact part and an insulating gas and is electrically insulated from the ground
Implementation Method 2
operation mechanisms that operate in opposite directions to minimize size and maximize voltage handling capability, while maintaining responsiveness
Data Source
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AI summary
A direct-current circuit breaker according to an embodiment of the present invention has a mechanical switching part, a semiconductor switching part and a commutation device. The mechanical switching part has at least one mechanical switching unit and an insulating column which supports the at least one mechanical switching unit. The mechanical switching unit has at least one unitary switching part. The unitary switching part has a mechanical contact part, a sealed container, an operation rod and an operation mechanism. The mechanical contact part has a fixed contact and a movable contact. The mechanical contact part is electrically insulated from the ground. The sealed container encloses the mechanical contact part and an insulating gas. The sealed container is electrically insulated from the ground. The operation rod is connected to the movable contact. The operation rod extends from the inside of the sealed container towards the outside thereof. The operation mechanism is connected to the operation rod. The operation mechanism causes the movable contact and the fixed contact to be brought into contact with and separated from each other. The operation mechanism is provided at the same electric potential as that of the movable contact.