Variable-Inductance DC Grid Protection for Selective Fault Isolation
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Solution Overview
Problem
Existing DC electric grids face challenges in achieving selective disconnection of faulted grid portions due to uniform fault currents across different sections, leading to unnecessary out-of-service periods for normally operating parts.
Innovation Solution
A protection device with a magnetic device having variable inductance values based on current flow, combined with a switching assembly and control device, allows selective disconnection by differentiating fault current behavior based on position, using solid-state and electromechanical switching devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If protection devices are arranged in various positions in the DC electric grid with different fault threshold values, then the coverage of fault protection is improved, but selectivity in disconnecting only faulted portions deteriorates because all devices intervene at the same time
Solution Approach 1:
The patent applies dynamics by making the inductance value of the magnetic device variable rather than fixed. The inductance changes dynamically based on the current flowing through the protection device, allowing the device to adapt its response characteristics to different fault conditions and positions in the grid, thereby achieving selective disconnection while maintaining comprehensive protection coverage
Solution Approach 2:
The patent changes the inductance parameter of the magnetic device based on current magnitude. By adjusting the inductance value according to the current flowing through the device, the system creates differentiated response characteristics for protection devices at different positions, enabling selective operation while maintaining broad protection coverage
2Adaptability or versatility
If DC electric grid uses distributed capacitances architecture, then the grid can operate with multiple power sources and loads, but fault current values become uniform across all sections making selective protection almost impossible
Solution Approach 1:
The patent applies local quality by giving each protection device different inductance characteristics based on its position in the grid. The magnetic device's inductance is tailored to the specific location and operational requirements of that section, creating locally optimized protection characteristics that enable selective operation while maintaining overall grid flexibility
Solution Approach 2:
The patent changes the inductance parameter of the magnetic device based on current magnitude. By adjusting the inductance value according to the current flowing through the device, the system creates differentiated response characteristics for protection devices at different positions, enabling selective operation while maintaining broad protection coverage
3Reliability
If protection devices intervene quickly to prevent catastrophic consequences, then safety is improved, but unnecessary out-of-service periods for normally operating portions increase due to lack of selectivity
Solution Approach 1:
The patent applies segmentation by dividing the grid into distinct protected sections, each with its own protection device configured to operate independently. When a fault occurs, only the specific section containing the fault is disconnected while other sections remain operational, thereby preventing catastrophic failure without causing unnecessary widespread outages
Solution Approach 2:
The patent applies dynamics by making the inductance value of the magnetic device variable rather than fixed. The inductance changes dynamically based on the current flowing through the protection device, allowing the device to adapt its response characteristics to different fault conditions and positions in the grid, thereby achieving selective disconnection while maintaining comprehensive protection coverage
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
Enables high levels of selectivity in disconnecting faulted grid portions, reducing energy dissipation and harmonic content, and minimizing unnecessary shutdowns of normally operating parts.
Implementation Method 1
a magnetic device having an inductance value, which, in operation, varies depending on the current flowing through said protection device
Implementation Method 2
The magnetic device includes a magnetic circuit including a magnetic body and one or more permanent magnets coupled to said magnetic body and feeding said magnetic body with a corresponding magnetic flux
Data Source
AI summary
The present disclosure relates to a protection device for a DC electric grid. The protection device comprises a first terminal for coupling to a first branch portion of an electric grid and a second terminal for coupling to a second branch portion of an electric grid. The protection device further comprises a switching assembly including one or more switching devices and a magnetic device electrically connected in series with said switching assembly between the first and second terminals of said protection device. The magnetic device has an inductance value that can vary in operation depending on the current flowing through said protection device.