DC Blocking Device Using Reverse Current Injection
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Solution Overview
Problem
Existing DC current interrupting systems face challenges in rapidly interrupting fault currents in high voltage direct current (HVDC) systems due to the complexity and cost associated with using active power semiconductor elements, which complicate signal control and system insulation.
Innovation Solution
A DC interrupting device and method utilizing a mechanical switch for current conduction, a reverse current power supply unit with a capacitor and polarity reversing inductor, and vacuum gap switches to generate a reverse current, eliminating the need for active power semiconductor elements and simplifying signal control and system insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If active power semiconductor elements are used in the high voltage unit for DC current interruption, then rapid current interruption can be achieved, but signal control and system insulation become complex and costly
Solution Approach 1:
The patent replaces active power semiconductor elements with a hybrid configuration consisting of mechanical switches and semiconductor elements used only for reverse current generation. The mechanical switch handles the main current interruption, eliminating the need for complex gate signal control and high-voltage insulation requirements associated with fully semiconductor-based solutions.
Solution Approach 2:
The patent divides the DC interrupter into separate functional units: a mechanical switch for current interruption and a semiconductor-based reverse current generation unit. This segmentation allows each component to be optimized for its specific function, reducing overall system complexity while maintaining rapid interruption capability.
2Speed
If active power semiconductor elements are used in the high voltage unit, then rapid current interruption is achieved, but cost increases due to power losses and system configuration requirements
Solution Approach 1:
The patent substitutes mechanical switches for active power semiconductor elements in the high-voltage current path, eliminating gate driver circuits, snubber networks, and associated control electronics, thereby reducing system configuration complexity and cost.
Solution Approach 2:
The patent employs a simple RC circuit for reverse current generation instead of expensive active power semiconductor-based reverse current sources, reducing component costs while achieving the necessary current interruption function.
3Device complexity
If mechanical switches are used for DC current interruption, then system simplicity is maintained, but rapid current interruption cannot be achieved due to transient voltage issues
Solution Approach 1:
The patent charges a capacitor in advance during normal operation, so that when a fault occurs, the pre-charged capacitor can immediately provide reverse current to force current zero, enabling rapid interruption without waiting for mechanical switch operation.
Solution Approach 2:
The patent generates reverse current through a pre-charged capacitor and RC circuit before fault current reaches dangerous levels, creating a counteracting current that forces the total current to zero and prevents fault current escalation.
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 allows for efficient and cost-effective DC current interruption by generating a reverse current to create a current zero, simplifying the high voltage unit and reducing power losses, thereby enhancing system reliability and economic viability.
Implementation Method 1
a first reverse current dedicated capacitor charged by a voltage applied to an input terminal of the main current conduction unit
Implementation Method 2
a polarity reversing inductor configured to reverse a polarity of the first reverse current dedicated capacitor
Implementation Method 3
vacuum gap switches to generate a reverse current
Data Source
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AI summary
A reverse current injection type DC current interrupting device and method using a vacuum gap switch are disclosed. The DC interrupting device includes a main current conduction unit including a main interrupting switch, which is a mechanical switch, a reverse current power supply unit connected to an input terminal of the main current conduction unit and configured to generate a predetermined reverse current, and a reverse current conduction unit configured to supply the reverse current to an output terminal of the main current conduction unit. The reverse current power supply unit includes a first reverse current dedicated capacitor charged by a voltage applied to an input terminal of the main current conduction unit, a polarity reversing inductor configured to reverse a polarity of the first reverse current dedicated capacitor, and a reverse current power supply unit switch configured to perform circuit connection such that the polarity reversing inductor reverses the polarity of the first reverse current dedicated capacitor.