Fiber Optic Quench Detection in HTS Cables
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Solution Overview
Problem
Conventional quench detection systems for superconductors, particularly in environments with electromagnetic interference, face challenges with false positives and increased downtime due to electromagnetic sensitivity and the need for multiple voltage taps, which can lead to adverse electrical events.
Innovation Solution
The implementation of an optics-based quench detection system using fiber optic thermometry with fiber Bragg gratings or ultra-long fiber Bragg gratings embedded in or adjacent to the superconductor, which measures temperature changes to detect quench events, reducing the risk of damage and downtime by quickly identifying and mitigating thermal runaway.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional voltage-based quench detection systems are used in electromagnetic environments, then quench events can be detected, but false positives increase and system reliability decreases due to electromagnetic sensitivity
Solution Approach 1:
The patent replaces the electrical/voltage-based detection system with an optical-based detection system using fiber optic sensors and Bragg gratings. This substitution eliminates the sensitivity to electromagnetic interference that plagues conventional voltage-based systems, as optical signals are immune to electromagnetic fields. The fiber optic sensors measure temperature changes directly through optical property changes rather than electrical voltage measurements, resolving the contradiction between detection capability and electromagnetic sensitivity.
Solution Approach 2:
The patent introduces fiber optic sensors as an intermediary between the superconductor and the detection system. These sensors convert thermal changes in the superconductor into optical signal changes through Bragg grating wavelength shifts. This intermediary approach allows indirect measurement of quench events without direct electrical contact, thereby eliminating electromagnetic interference issues while maintaining accurate quench detection capability.
2Reliability
If multiple voltage taps are installed for quench detection, then detection coverage is improved, but the risk of adverse electrical events and system complexity increases
Solution Approach 1:
The patent employs fiber optic cables that serve multiple functions simultaneously: they provide distributed temperature sensing along the entire superconductor length, act as thermal coupling elements, and serve as the detection medium itself. This multi-functionality eliminates the need for multiple separate voltage taps, as the single fiber optic cable provides comprehensive detection coverage through its distributed sensor array, reducing system complexity while maintaining or improving detection reliability.
Solution Approach 2:
The fiber optic cable serves itself by using its own optical properties (Bragg grating wavelength shifts) to detect temperature changes. The sensor is inherently part of the detection system rather than requiring separate measurement points. This self-service approach allows the fiber optic cable to provide distributed detection coverage along its entire length without requiring additional external sensors or complex wiring, thereby reducing device complexity while improving detection coverage.
3Loss of time
If fiber optic sensors with spaced gratings are used for quench detection, then detection speed improves and damage is minimized, but the manufacturing complexity increases
Solution Approach 1:
The patent utilizes changes in optical parameters (wavelength, intensity, or phase) of the fiber optic sensor in response to temperature changes to detect quenches. By monitoring shifts in Bragg grating wavelengths caused by thermal expansion and refractive index changes, the system achieves rapid quench detection. The spaced gratings create distinct wavelength signatures that enable fast localization of quench events, and these parameter changes can be detected with high sensitivity using standard optical interrogation equipment, balancing detection speed with manufacturing feasibility.
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 approach provides a robust and accurate method for detecting quench events in superconductors, reducing false positives and minimizing damage by utilizing temperature measurements from fiber optic sensors, thus ensuring timely energy removal and maintaining device integrity.
Implementation Method 1
at least one optical fiber having a plurality of gratings spaced apart from one another along the length of the HTS cable to detect a quench of the at least one HTS tape stack
Data Source
AI summary
A high temperature superconductor (HTS) cable includes at least one HTS tape stack extending along a length of the HTS cable; and at least one optical fiber extending along the HTS cable. The at least one optical fiber has a plurality of gratings spaced apart from one another along the length of the HTS cable to detect a quench of the at least one HTS tape stack.