CN117590300A - Superconducting magnet quench detection system and method based on distributed optical fiber acoustic wave sensing - Google Patents

Abstract

The invention discloses a superconducting magnet quench detection system and method based on distributed optical fiber acoustic wave sensing, and belongs to the field of superconducting magnet quench detection. The system includes: distributed acoustic vibration sensing fiber, coherent laser, coupler, acoustic vibration demodulator, monitoring software and data storage. The invention provides a new type of quench detection method, which has the advantages of strong anti-electromagnetic interference capability, simple and flexible layout, etc., can realize continuous quench detection of superconducting magnets, and overcomes the need for traditional quench positioning to bury the sensor in Defects such as internal defects of superconducting magnets, difficulty in maintenance, and complex wiring.

Description

Superconducting magnet quench detection system and method based on distributed optical fiber acoustic wave sensing

Technical field

The invention belongs to the technical field of superconducting magnet quench, and specifically relates to a superconducting magnet quench detection system and method based on distributed optical fiber acoustic wave sensing.

Background technique

During the excitation operation of the superconducting magnet, it will be affected by disturbances such as deformation (mechanical disturbance) under the action of electromagnetic force, magnetic flux jump in the superconducting wire (magnetic disturbance), and its own AC loss (thermal disturbance). Quench occurs randomly inside the magnetic conductor. Once a quench occurs, the strain energy inside the superconducting magnet is instantly released and mechanical waves are emitted. Therefore, the quench can be determined by detecting the acoustic signal of the superconducting magnet. However, traditional acoustic emission sensors are easily affected by electromagnetic interference, and the quench signal is often annihilated by noise. In addition, traditional acoustic emission sensors are too large and require a large number of leads to be installed on the superconducting magnet structure, occupying a large space and even affecting the electromagnetic characteristics of the superconducting magnet. However, other quench detection methods are difficult to determine the location of the quench source of the superconducting magnet. Some sensors have many problems such as lead damage and difficulty in maintenance after being embedded inside the superconducting magnet. Therefore, the development of a fast and effective quench detection system can make timely and accurate judgments when quench occurs in superconducting magnets, accurately determine the location of the quench source of superconducting magnets, and provide information for ensuring the healthy operation of superconducting magnets and optimizing magnet design in the future. Important parameters.

Contents of the invention

The present invention aims to solve the deficiencies of the existing technology and propose a superconducting magnet quench detection system and method based on distributed optical fiber acoustic wave sensing. Based on the principle of coherent optical time domain reflectometry (C-OTDR), a soft distributed acoustic vibration sensing fiber is used to measure a large number of acoustic vibration signals released by the superconducting magnet during quench time. Based on the time dependence of the optical fiber return light, Determine where the quench occurs in the measured superconducting magnet.

To achieve the above objectives, the present invention provides the following solution: a superconducting magnet quench detection system based on distributed optical fiber acoustic wave sensing, including: distributed acoustic vibration sensing fiber, coherent laser, coupler, acoustic vibration demodulator, Monitoring software and data storage;

The distributed acoustic vibration sensing optical fiber is laid on the surface of the superconducting magnet and is used to detect whether the superconducting magnet has quench;

The coherent laser is used to send high-coherence laser pulses to the distributed acoustic vibration sensing fiber; the high-coherence laser pulses are transmitted to the distributed acoustic vibration sensing fiber after being acted on by the coupler, to obtain scattered light signal;

The acoustic wave demodulator is used to decode and analyze the scattered light signal to obtain a quench signal;

The monitoring software is used to express the quench signal in the form of frequency and phase, and obtain the quench source position and determine the cause of the quench of the superconducting magnet based on the quench signal;

The data memory is used to collect and store the quench signal in real time.

Further preferably, the method of laying out the distributed acoustic vibration sensing optical fiber includes:

The distributed acoustic vibration sensing optical fiber is wound into an optical fiber ring, and is placed freely or bonded to the surface of the superconducting magnet; or the distributed acoustic vibration sensing optical fiber is directly wound on the surface of the superconducting magnet.

Further preferably, the method for calculating the quench source position includes:

X ₁ =v*(t ₁ -t ₀ )

X ₂ =v*(t ₂ -t ₀ )

X ₃ =v*(t ₃ -t ₀ )

In the formula, X _{1 ,} X ₂ , _and t ₂ and t ₃ respectively represent the time when the distributed acoustic vibration sensing fiber A, B and C detect the quench of the superconducting magnet; t ₀ represents the time when the superconducting magnet starts to be excited.

The invention also provides a superconducting magnet quench detection method based on distributed optical fiber acoustic wave sensing. The detection method is applied to the detection system and includes the following steps:

Step 1. Fix the distributed acoustic vibration sensing fiber on the surface of the superconducting magnet;

Step 2: Emit high-coherence laser pulses to the distributed acoustic vibration sensing fiber to obtain scattered light signals;

Step 3: Demodulate and analyze the scattered light signal to obtain a quench signal;

Step 4: Formal expression and storage of the quench signal;

Step 5: Calculate the quench source location and quench cause based on the quench signal.

Further preferably, the method for fixing the distributed acoustic vibration sensing fiber to the surface of the superconducting magnet in step 1 includes:

The distributed acoustic vibration sensing optical fiber is wound into an optical fiber ring, and is placed freely or bonded to the surface of the superconducting magnet; or the distributed acoustic vibration sensing optical fiber is directly wound on the surface of the superconducting magnet.

Further preferably, the formal expression in step 4 includes: the frequency and phase of the quench signal.

Further preferably, the method for obtaining the quench source position in step five includes:

X ₁ =v*(t ₁ -t ₀ )

X ₂ =v*(t ₂ -t ₀ )

X ₃ =v*(t ₃ -t ₀ )

In the formula, X _{1 ,} X ₂ , _and t ₂ and t ₃ respectively represent the time when the distributed acoustic vibration sensing fiber A, B and C detect the quench of the superconducting magnet; t ₀ represents the time when the superconducting magnet starts to be excited.

Compared with the prior art, the beneficial effects of the present invention are:

The optical fiber layout method of the present invention can reduce the installation volume of the distributed optical fiber sensor, has the advantages of strong anti-electromagnetic interference ability, rapid response, simple and flexible layout method, etc., improves the spatial resolution of the acoustic vibration optical fiber, thereby improving the loss of superconducting magnets. The accuracy of super source positioning is based on the time difference between multiple quench sources arriving at the optical fiber. Through quench detection and identification of the quench signal frequency, the spatial positions of multiple quench sources can be determined simultaneously, and the quench source caused by the superconducting magnet can be identified. Super reason. It overcomes the shortcomings of traditional quench positioning such as the need to bury the sensor inside the superconducting magnet, difficulty in maintenance, and complex circuits.

Description of drawings

In order to explain the technical solutions of the present invention more clearly, the drawings required to be used in the embodiments are briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary people in the art, Technical personnel can also obtain other drawings based on these drawings without exerting creative labor.

Figure 1 is a schematic structural diagram of a superconducting magnet quench detection system based on distributed optical fiber acoustic wave sensing according to an embodiment of the present invention;

Figure 2 is a schematic diagram of quench detection and positioning of distributed acoustic vibration sensing optical fibers directly wound on the surface of a superconducting magnet according to an embodiment of the present invention;

Figure 3 is a schematic diagram of quench detection and multiple quench source positioning of distributed acoustic vibration sensing optical fibers attached to the surface of a superconducting magnet according to an embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

In order to make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

Example 1:

As shown in Figure 1, this embodiment provides a superconducting magnet quench detection system based on distributed optical fiber acoustic wave sensing. The application object is a superconducting magnet structure. The applicable environment is extremely low temperature, strong magnetic field, large current, Extreme multi-field environments such as strong radiation and high loads. Specifically including: distributed acoustic vibration sensing fiber, coherent laser, coupler, acoustic vibration demodulator, monitoring software and data storage. Distributed acoustic vibration sensing optical fiber is laid on the surface of the superconducting magnet to detect whether the superconducting magnet has quench. As shown in Figure 2, distributed optical fiber acoustic sensing (DAS) is directly wrapped around the surface of the entire superconducting magnet structure to detect quench and position. The coherent laser sends high-coherence laser pulses to the distributed acoustic vibration sensing fiber. After the high-coherence laser pulse passes through the coupler, it is transmitted to the distributed acoustic vibration sensing fiber. Part of the laser pulse light signal is transmitted out in the fiber sensor, and part of the laser pulse signal is transmitted through the fiber sensor. Scattering occurs and returns, becoming a scattered light signal. In the present invention, the acoustic wave demodulator only decodes and analyzes the scattered light signal to obtain the quench signal. The monitoring software expresses the quench signal in the form of frequency and phase, and obtains the position of the quench source and determines the cause of the quench based on the quench signal. The data memory collects and stores quench signals in real time.

Specifically, this system is based on the principle of coherent optical time domain reflectometry (C-OTDR). The highly coherent laser pulse is transmitted to the distributed acoustic vibration sensing fiber through the action of the coupler, and part of the optical signal is in the distributed fiber sensor. Transmission occurs, and another part of the optical signal is scattered in the distributed optical fiber sensor. When the superconducting magnet quenches (the superconducting conductor does not emit sound waves under normal operation of the superconducting magnet, only when the quench occurs, the superconducting magnet releases instantly A large number of acoustic vibration signals), the released acoustic vibration signal causes the distributed acoustic vibration sensing fiber to stretch or compress along the axial direction, resulting in a change in the phase relationship of the scattered light signal in the distributed acoustic vibration sensing fiber, and the acoustic vibration solution The instrument measures the changing parameters of the back Rayleigh scattered light signal over time in real time, thereby obtaining the quench signals at different positions on the distributed acoustic vibration sensing fiber, and can also obtain the positions of multiple quench sources on the superconducting magnet at the same time. Information. The monitoring software will express the analysis results, that is, the quench signal, in the form of frequency and phase. In addition, in the quench detection system, the change in the phase of the optical fiber signal is used to determine whether the superconducting magnet has quenched, and the change in the frequency of the optical fiber signal is used to analyze and determine the cause of the quench of the superconducting magnet.

The monitoring software calculates the position of the quench source, and determines the position of the quench source of the superconducting magnet by measuring the return time difference of the scattered light in the optical fiber. The calculation method of the quench source position includes:

X ₁ =v*(t ₁ -t ₀ )

X ₂ =v*(t ₂ -t ₀ )

X ₃ =v*(t ₃ -t ₀ )

In the formula, X _{1 ,} X ₂ , _and t ₂ and t ₃ respectively represent the time when the distributed acoustic vibration sensing fiber A, B and C detect the quench of the superconducting magnet; t ₀ represents the time when the superconducting magnet starts to be excited.

Assuming that the straight-line distances between points A, B, and C on the distributed acoustic vibration sensing fiber and the surface of the superconducting magnet structure are S ₁ , S ₂ , and S ₃ respectively, the space of the quench source of the ultrasonic magnet can be determined from the above parameters. Location.

Further, as shown in Figure 3, the distributed acoustic vibration sensing fiber is pre-wound into multiple optical fiber rings, similar to the array sensor, and is placed freely or bonded to the surface of the superconducting magnet; or the distributed acoustic vibration sensing fiber is The sensing fiber is directly wound on the surface of the superconducting magnet to detect quench and locate multiple quench sources. This layout method can reduce the installation volume of the distributed optical fiber sensor, improve the spatial resolution of the acoustic vibration fiber, thereby improving the positioning accuracy of the superconducting magnet quench source. Based on the time difference between multiple quench sources arriving at the fiber ring, it is convenient to The spatial positions of multiple quench sources can be determined simultaneously.

Example 2:

This embodiment provides a superconducting magnet quench detection method based on distributed optical fiber acoustic wave sensing. This embodiment describes the detection method in detail by combining various components of the detection system. Specifically, the detection method includes the following steps:

Step 1: Fix the distributed acoustic vibration sensing fiber on the surface of the superconducting magnet.

Methods for fixing distributed acoustic vibration sensing optical fibers on the surface of superconducting magnets include:

The distributed acoustic vibration sensing fiber is pre-wound into a fiber ring, similar to an array sensor, and is placed freely or bonded to the surface of the superconducting magnet; or the distributed acoustic vibration sensing fiber is directly wound on the surface of the superconducting magnet, such as As shown in Figure 2.

Step 2: Emit high-coherence laser pulses to the distributed acoustic vibration sensing fiber to obtain scattered light signals.

The coherent laser emits high-coherence laser pulses to the distributed acoustic vibration sensing fiber. The high-coherence laser pulse is transmitted to the distributed acoustic vibration sensing fiber through the action of the coupler. Part of the optical signal is transmitted in the distributed fiber sensor. In addition, A portion of the optical signal is scattered within the distributed fiber optic sensor.

Step 3: Demodulate and analyze the scattered light signal to obtain the quench signal.

When a superconducting magnet quenches (the superconducting conductor of a superconducting magnet does not emit sound waves under normal operating conditions, and only when it quenches, the superconducting magnet instantly releases a large amount of sound wave vibration signals), the released sound wave vibration signals cause distributed sound waves The elongation or compression of the vibration sensing fiber along the axial direction causes the phase relationship of the scattered light signal in the distributed acoustic vibration sensing fiber to change. The acoustic vibration demodulator measures the changing parameters of the back Rayleigh scattered light signal with time in real time. , thereby obtaining quench signals at different locations on the distributed acoustic vibration sensing fiber, and information on the positions of multiple quench sources on the superconducting magnet can also be obtained simultaneously.

Step 4: Formally express and store the quench signal;

Monitoring software is used to express the quench signal in the form of frequency and phase.

Step 5: Calculate the position of the quench source and determine the cause of the quench based on the quench signal.

Determining the position of the quench source of a superconducting magnet is achieved by measuring the return time difference of scattered light in the optical fiber. The calculation method of the quench source position includes:

X ₁ =v*(t ₁ -t ₀ )

X ₂ =v*(t ₂ -t ₀ )

X ₃ =v*(t ₃ -t ₀ )

In the formula, X _{1 ,} X ₂ , _and t ₂ and t ₃ respectively represent the time when the distributed acoustic vibration sensing fiber A, B and C detect the quench of the superconducting magnet; t ₀ represents the time when the superconducting magnet starts to be excited.

Assuming that the straight-line distances between points A, B, and C on the distributed acoustic vibration sensing fiber and the surface of the superconducting magnet structure are S ₁ , S ₂ , and S ₃ respectively, the space of the quench source of the ultrasonic magnet can be determined from the above parameters. Location.

Further, as shown in Figure 3, the distributed acoustic vibration sensing fiber is pre-wound into multiple optical fiber rings, similar to the array sensor, and is placed freely or bonded to the surface of the superconducting magnet; or the distributed acoustic vibration sensing fiber is The sensing fiber is directly wound on the surface of the superconducting magnet to detect quench and locate multiple quench sources. This layout method can reduce the installation volume of the distributed optical fiber sensor, improve the spatial resolution of the acoustic vibration fiber, thereby improving the positioning accuracy of the superconducting magnet quench source. Based on the time difference between multiple quench sources arriving at the fiber ring, it is convenient to The spatial positions of multiple quench sources can be determined simultaneously.

The above-described embodiments are only descriptions of preferred modes of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, those of ordinary skill in the art can make various modifications to the technical solutions of the present invention. All deformations and improvements shall fall within the protection scope determined by the claims of the present invention.

Claims (7)

1. Superconducting magnet quench detection system based on distributed optical fiber acoustic wave sensing, which is characterized by comprising: the device comprises a distributed acoustic vibration sensing optical fiber, a coherent laser, a coupler, an acoustic vibration demodulator, monitoring software and a data memory;

the distributed acoustic vibration sensing optical fiber is arranged on the surface of the superconducting magnet and is used for detecting whether the superconducting magnet is quenched or not;

the coherent laser is used for sending high-coherence laser pulses to the distributed acoustic vibration sensing optical fiber; the high-coherence laser pulse is transmitted to the distributed acoustic vibration sensing optical fiber after being acted by the coupler, so that a scattered light signal is obtained;

the sound wave demodulator is used for decoding and analyzing the scattered light signals to obtain quench signals;

the monitoring software is used for expressing the quench signal in the form of frequency and phase, obtaining the quench source position according to the quench signal and judging the cause of quench;

the data memory is used for collecting and storing the quench signal in real time.

2. The superconducting magnet quench detection system based on distributed optical fiber acoustic wave sensing according to claim 1, wherein the distributed acoustic wave vibration sensing optical fiber laying method comprises:

the distributed acoustic vibration sensing optical fiber is wound into an optical fiber ring in advance and is freely placed or adhered to the surface of the superconducting magnet; or the distributed acoustic vibration sensing optical fiber is directly wound on the surface of the superconducting magnet.

3. The fiber-optic acoustic wave sensing based high temperature superconducting magnet quench detection system of claim 1, wherein the quench source position calculation method comprises:

X ₁ ＝v*(t ₁ -t ₀ )

X ₂ ＝v*(t ₂ -t ₀ )

X ₃ ＝v*(t ₃ -t ₀ )

wherein X is ₁ 、X ₂ 、X ₃ Representing the distance from the quench source to the three points of the distributed acoustic vibration sensing fiber A, B, C; v represents the propagation velocity of the quench signal in the superconducting magnet; t is t ₁ 、t ₂ 、t ₃ Respectively representing the time when the three points of the distributed acoustic vibration sensing optical fiber A, B, C detect the quench of the superconducting magnet; t is t ₀ The time when the superconducting magnet starts to be excited is indicated.

4. A superconducting magnet quench detection method based on distributed optical fiber acoustic wave sensing, the detection method being applied to the detection system according to any one of claims 1 to 3, and comprising the steps of:

step one, fixing a distributed acoustic vibration sensing optical fiber on the surface of a superconducting magnet;

step two, transmitting high-coherence laser pulses to the distributed acoustic vibration sensing optical fiber to obtain a scattered light signal;

demodulating and analyzing the scattered light signals to obtain quench signals;

step four, the quench signal is expressed in a form and stored;

and fifthly, calculating the position of the quench source based on the quench signal and judging the cause of the quench.

5. The method for detecting a quench of a superconducting magnet based on distributed optical fiber acoustic wave sensing according to claim 4, wherein the method for fixing the distributed acoustic wave vibration sensing optical fiber to the surface of the superconducting magnet in the step one comprises:

winding the distributed acoustic vibration sensing optical fiber into an optical fiber ring, and freely placing or bonding the optical fiber ring on the surface of the superconducting magnet; or the distributed acoustic vibration sensing optical fiber is directly wound on the surface of the superconducting magnet.

6. The method for detecting a quench of a superconducting magnet based on distributed optical fiber acoustic wave sensing according to claim 4, wherein the formal expression in the fourth step includes: the frequency and phase of the quench signal.

7. The method for detecting a quench of a superconducting magnet based on distributed optical fiber acoustic wave sensing according to claim 4, wherein the method for obtaining the quench source position in the fifth step comprises:

X ₁ ＝v*(t ₁ -t ₀ )

X ₂ ＝v*(t ₂ -t ₀ )

X ₃ ＝v*(t ₃ -t ₀ )

wherein X is ₁ 、X ₂ 、X ₃ Representing the distance from the quench source to the three points of the distributed acoustic vibration sensing fiber A, B, C; v represents the propagation velocity of the quench signal in the superconducting magnet; t is t ₁ 、t ₂ 、t ₃ Respectively representing the time when the three points of the distributed acoustic vibration sensing optical fiber A, B, C detect the quench of the superconducting magnet; t is t ₀ The time when the superconducting magnet starts to be excited is indicated.