DC Branch Switching Circuit With Bridging Thyristor Fault Isolation
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Solution Overview
Problem
Existing DC voltage switching devices struggle to selectively trip and isolate faults in DC voltage networks without overdimensioning, which is costly and uneconomical.
Innovation Solution
A switching device with a bridging semiconductor switching element, such as a thyristor, connected in parallel with the series circuit of two switching modules, allowing current to flow in reverse direction and enabling selective tripping of switching devices in other DC voltage branches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switching devices are overdimensioned to prevent interference from other branches during faults, then reliability of fault isolation is improved, but device complexity and cost increase
Solution Approach 1:
The switching device is segmented into two functional parts: the original switching modules (first and second) for normal operation, and the bridging semiconductor switching element for fault conditions. This segmentation allows each part to be optimized for its specific function, preventing the need to overdimension the entire device.
Solution Approach 2:
The bridging semiconductor switching element is dynamically activated only during fault conditions when voltage on the DC voltage branch exceeds voltage on the DC voltage bus. During normal operation, it remains inactive, allowing the switching device to maintain smaller dimensions while providing enhanced fault isolation reliability when needed.
2Productivity
If switching devices are overdimensioned to handle reverse current from all branches, then productivity of fault clearance is improved, but loss of substance and cost increase
Solution Approach 1:
The current path during faults is segmented and redirected through the bridging semiconductor switching element. This allows fault current to be cleared rapidly without requiring the main switching modules to be overdimensioned, thus improving fault clearance productivity while reducing material usage.
Solution Approach 2:
The bridging semiconductor switching element acts as an intermediary during fault conditions, providing a dedicated path for reverse current flow. This mediator enables rapid fault clearance without requiring other branches to be overdimensioned, reducing material consumption while maintaining high productivity.
3Reliability
If switching devices are overdimensioned to ensure selective tripping, then reliability of selective disconnection is improved, but device complexity increases
Solution Approach 1:
The bridging semiconductor switching element provides localized protection specifically for the DC voltage branch where a fault occurs. By placing this element only where needed (in parallel with the switching modules of each branch), selective disconnection reliability is improved without requiring all switching devices in the network to be overdimensioned or complexified.
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 selective disconnection of faulty branches while minimizing interference from other branches, reducing the need for overdimensioning and associated costs.
Implementation Method 1
a bridging semiconductor switching element QU, in particular a thyristor, is connected in parallel with the series circuit or parallel circuit comprising the two switching modules SM1, SM2 or the four switching modules SM1, SM2, SM3, SM4. The bridging semiconductor switching element QU is used in this case to conduct the current for an exceptional case
Data Source
AI summary
A switching device is for coupling a DC voltage branch to a DC voltage bus. The switching device includes a series circuit including a first switching module and a second switching module. A first diode is connected in parallel with the first semiconductor switching element and a second diode is connected in parallel with the second semiconductor switching element. A third semiconductor switching element is connected in parallel with the series circuit. A control device is connected to the first and second semiconductor switching elements, to the bridging semiconductor switching element, to the voltage sensor and to the current sensor. The control device is configured to, upon a first threshold value of the voltage being undershot and current flowing in an exceptional case, switch the bridging semiconductor switching element to the conducting state in order to facilitate a current flow from the DC voltage branch to the DC voltage bus.