Modular DC Power Switching Assembly for High Voltage Fault Isolation
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Solution Overview
Problem
Current DC power distribution systems in high voltage applications, such as offshore platforms and drilling rigs, lack effective static switching solutions to prevent fault propagation across DC bus sections, as existing low voltage bus tie switches are inadequate for voltages above 1000V, particularly in the range of 10 to 15kV, necessitating the use of mechanical breakers which are not suitable for fast disconnection.
Innovation Solution
A DC power switching assembly comprising series connected power switching units with semiconductor devices, current limiters, and voltage blocking capacitors, allowing for controlled current flow and voltage blocking during faults, enabling fast disconnection and isolation of faulty sections without interrupting the entire system, and a method for monitoring and operating the system to detect and clear short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical breakers are used for high voltage DC systems, then fault isolation capability is provided, but disconnection speed is slow and system availability is reduced
Solution Approach 1:
The patent replaces mechanical breakers with a static switching assembly using semiconductor devices (IGBTs, MOSFETs, or diodes) for high voltage DC fault isolation. The switching assembly provides electrical switching without mechanical moving parts, achieving fast disconnection speeds while maintaining reliable fault isolation capability across DC bus sections.
Solution Approach 2:
The patent changes the operating parameters by using semiconductor devices rated for high voltage (above 1000V, particularly 10-15kV range) and incorporating voltage blocking capacitors to handle the high voltage DC conditions. This enables fast electronic switching at high voltages where mechanical breakers would be too slow.
2Speed
If low voltage bus tie switches are used, then fast disconnection is achieved, but they are inadequate for voltages above 1000V
Solution Approach 1:
The patent modifies the voltage handling capability by using series-connected semiconductor devices and voltage blocking capacitors rated for high voltage applications (10-15kV range). This allows the switching assembly to maintain fast disconnection speeds while being adaptable to high voltage DC systems above 1000V where low voltage bus tie switches fail.
Solution Approach 2:
The patent divides the high voltage switching function into multiple series-connected power switching units, each handling a portion of the total voltage. This segmentation allows the use of available semiconductor devices while achieving the required high voltage blocking capability and maintaining fast switching performance.
3Reliability
If separate power sections with open bus ties are used, then fault propagation is prevented, but system redundancy and availability are reduced
Solution Approach 1:
The patent implements dynamic switching capability that allows the bus tie to transition between open and closed states based on system conditions. During normal operation, the bus tie can be closed to provide redundancy and maintain system availability. Upon detecting a fault, the switching assembly rapidly opens to prevent fault propagation, thus achieving both goals dynamically.
Solution Approach 2:
The patent incorporates fault detection and control logic that monitors system conditions and automatically controls the switching assembly. When a fault is detected in one DC bus section, the system automatically opens the bus tie to isolate the fault while keeping other sections operational, maintaining system availability while preventing fault propagation.
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 provides a high voltage modular DC bus tie switch capable of fast disconnection and isolation, preventing fault propagation across DC bus sections, ensuring continuous power supply to critical systems while maintaining component safety and stability.
Implementation Method 1
the sub-unit comprises at least one semiconductor device, which conducts in normal operation and no longer conducts in the event of a fault arising at one of the first and second terminals
Implementation Method 2
the current limiter comprises an inductance
Implementation Method 3
a voltage blocking capacitor is connected to the other terminal of the semiconductor device to block voltage when the semiconductor devices no longer conduct
Implementation Method 4
the series connected diodes allow current flow to continue until the current limiter has discharged, if the semiconductor device no longer conducts
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A DC power switching assembly (22) comprises a plurality of series connected power switching units (21). Each power switching unit (21, 45) comprises a first terminal (23) of the unit and a second terminal (24) of the unit, the terminals having the same polarity. A power switching sub-unit (46, 47) is electrically coupled between the first terminal and the second terminal of the unit to control current flow between the first terminal and the second terminal. The sub-unit (46, 47) comprises at least one semiconductor device (Q1, Q2), a current limiter (L1, L2) and a pair of series connected diodes (D1, D11, D2, D21) in parallel with the current limiter. The series connected diodes and current limiter are connected to one terminal of the semiconductor device; and a capacitor (C1, C2) is connected to the other terminal of the semiconductor device.