Device and method for detecting SF6 gas based on time domain vernier infrared spectrum

Abstract

The invention provides a device for detecting SF6 gas based on time domain vernier infrared spectroscopy, which comprises a signal acquisition module and a data processing module, and the signal acquisition module comprises a light source emission unit, a gas insulated metal-enclosed switchgear SF6 gas monitoring unit, an interference light filtering unit and a light signal output unit. Light pulses emitted by the light source emitting unit in real time penetrate through the SF6 gas monitoring unit of the gas-insulated metal-enclosed switchgear to generate interference light, the interference light is filtered by the interference light filtering unit to obtain output light with a specific wavelength, the output light is converted into an electric signal through the light signal output unit, and the electric signal is transmitted to the data processing module to convert the electric signal into a time domain spectrogram. The method comprises the steps that a time-domain spectrogram is obtained through a data processing module, the time-domain spectrogram is analyzed and processed, the data processing module converts the phase difference delta d of the time-domain spectrogram into the drift distance M delta d of a superposed envelope signal, M is the amplification factor, the sensitivity is improved by several times, and the concentration of SF6 gas in the SF6 gas monitoring unit of the gas-insulated metal-enclosed switchgear is calculated according to the drift distance M delta d.

Description

Technical Field

[0001] The present invention relates to the technical field of gas detection, and in particular to a device and method for detecting SF6 gas based on time domain vernier infrared spectroscopy. Background Art

[0002] In gas-insulated metal-enclosed switchgear (GIS), the composition of SF6 gas decomposition products, the volume fraction of each component, the generation rate of decomposed gas, etc. are important indicators of GIS operating status and insulation defects. When insulation defects occur inside the GIS and local discharge or high temperature heating occurs, the SF6 gas in the GIS will continue to decompose and react chemically with trace water, trace oxygen in the equipment and the insulation materials inside the equipment to generate a series of stable or unstable chemical products. The types, contents and evolution laws of these decomposition chemical products mainly depend on factors such as the discharge fault type of the GIS equipment, the discharge energy, the duration of the discharge, the composition of the electrode materials and insulation materials of the equipment, and the moisture and oxygen content in the gas. Therefore, detecting the evolution law of the concentration of SF6 gas in the GIS over time is an important means to analyze and evaluate the insulation status and fault type of the GIS, and is of great significance for discovering potential faults, studying the fault generation mechanism and fault evolution law, and optimizing the insulation structure design.

[0003] The existing optical gas sensors for detecting the SF6 gas concentration in GIS are composed of multiple discrete optical instruments or components such as a light source, a lens (or a lens group), a gas absorption cell chamber, and a photodetector. This type of optical gas sensor obtains the concentration information of SF6 gas by measuring the absorption spectrum of SF6 gas. However, due to the limitations of the spectral resolution of existing spectrometers and the sensitivity of the detection system, there are serious errors in the detection results of the SF6 gas concentration in GIS. Summary of the invention

[0004] In view of this, in view of the above shortcomings, it is necessary to propose a device for detecting SF6 gas based on time domain vernier infrared spectroscopy to solve the technical problem that the detection results of SF6 gas concentration in GIS have serious errors due to the limitations of spectral resolution and detection system sensitivity of existing spectrometers;

[0005] It is also necessary to propose a detection method for a device for detecting SF6 gas based on time domain vernier infrared spectroscopy.

[0006] On the one hand, the device for detecting SF6 gas based on time domain vernier infrared spectrum provided by the present invention includes a signal acquisition module and a data processing module, wherein the signal acquisition module is electrically connected to the data processing module, and the signal acquisition module includes a light source emitting unit, a gas-insulated metal-enclosed switchgear SF6 gas monitoring unit, an interference light filtering unit, and an optical signal output unit, wherein the light source emitting unit, the gas-insulated metal-enclosed switchgear SF6 gas monitoring unit, the interference light filtering unit, and the optical signal output unit are sequentially connected through optical fibers, and the optical signal output unit is electrically connected to the data processing module;

[0007] The light source emitting unit is used to emit light pulses in real time, the gas-insulated metal-enclosed switchgear SF6 gas monitoring unit causes light pulses to interfere and generate interference light, the interference light filtering unit is used to filter out output light of a specific wavelength, the optical signal output unit converts the optical signal into an electrical signal, the data processing module is used to convert the electrical signal into a time domain spectrogram, and the data processing module is used to analyze and process the time domain spectrogram so that the phase difference Δδ of the time domain spectrogram is converted into a drift amount M×Δδ of the superimposed envelope signal, where M is the amplification factor, and the concentration of SF6 gas in the gas-insulated metal-enclosed switchgear SF6 gas monitoring unit is calculated based on the drift amount M×Δδ.

[0008] On the other hand, according to the above-mentioned detection method of the device for detecting SF6 gas based on time domain vernier infrared spectroscopy, the method specifically comprises the following steps:

[0009] Step 1: obtaining a real-time emitted light pulse through the light source emitting unit, the light pulse passing through the SF6 gas monitoring unit of the gas-insulated metal-enclosed switchgear causes interference of the light pulse and generates interference light, the interference light is filtered out by the interference light filtering unit to obtain output light of a specific wavelength, and the output light is converted into an electrical signal by the optical signal output unit and transmitted to the data processing module;

[0010] Step 2: The data processing module converts the electrical signal into a time domain spectrogram, and analyzes and processes the time domain spectrogram, converts the phase difference Δδ of the time domain spectrogram into a drift M×Δδ of the superimposed envelope signal, where M is the amplification factor, and calculates the concentration of SF6 gas in the SF6 gas monitoring unit of the gas-insulated metal-enclosed switchgear based on the drift M×Δδ.

[0011] It can be seen from the above technical solution that the device for detecting SF6 gas based on time domain vernier infrared spectrum provided by the present invention includes a signal acquisition module and a data processing module, the signal acquisition module is electrically connected to the data processing module, the signal acquisition module includes a light source emitting unit, a gas-insulated metal-enclosed switchgear SF6 gas monitoring unit, an interference light filtering unit, and an optical signal output unit, the light source emitting unit, the gas-insulated metal-enclosed switchgear SF6 gas monitoring unit, the interference light filtering unit, and the optical signal output unit are sequentially connected through optical fibers, and the optical signal output unit is electrically connected to the data processing module;

[0012] When detecting the SF6 gas concentration in the SF6 gas monitoring unit of the gas-insulated metal-enclosed switchgear, first, the light pulse emitted in real time by the light source emitting unit passes through the SF6 gas monitoring unit of the gas-insulated metal-enclosed switchgear to interfere with the light pulse and generate interference light. The interference light is filtered out by the interference light filtering unit to obtain output light of a specific wavelength. The output light is converted into an electrical signal by the optical signal output unit and transmitted to the data processing module; then the data processing module converts the electrical signal into a time domain spectrogram, and the data processing module analyzes and processes the time domain spectrogram. At the same time, the data processing module converts the phase difference Δδ of the time domain spectrogram into a drift amount M×Δδ of the superimposed envelope signal, where M is the amplification factor, thereby achieving a several-fold increase in sensitivity, and the concentration of SF6 gas in the SF6 gas monitoring unit of the gas-insulated metal-enclosed switchgear is calculated based on the drift amount M×Δδ, thereby preventing the occurrence of a phenomenon in which a serious error in the detection result occurs when the phase difference Δδ is too small and exceeds the spectral resolution limit of the existing spectrometer. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0014] Figure 1 A schematic diagram of a device for detecting SF6 gas based on time-domain vernier infrared spectroscopy provided in an embodiment of the present invention.

[0015] Figure 2 Schematic diagram of comparison of the judgment unit according to the embodiment of the present invention.

[0016] Figure 3 This is a result diagram of the envelope signal formed by superimposing it according to an embodiment of the present invention.

[0017] Figure 4 It is a periodogram of the time domain signal according to an embodiment of the present invention.

[0018] In the figure: signal acquisition module 1, light source emitting unit 11, gas insulated metal enclosed switchgear SF6 gas monitoring unit 12, light source branching part 121, gas insulated metal enclosed switchgear 122, electric optical fiber delay line 123, reference single-mode optical fiber 124, first interference light merging part 125, interference light branching part 126, second interference light merging part 127, interference light filtering unit 13, first interference light filtering part 131, second interference light filtering part 132, optical signal output unit 14, first optical signal output part 141, second optical signal output part 142, data processing module 2, storage unit 21, judgment unit 22, processing unit 23. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Please see Figure 1 The device for detecting SF6 gas based on time domain vernier infrared spectrum provided by the present invention comprises a signal acquisition module 1 and a data processing module 2. The signal acquisition module 1 is electrically connected to the data processing module 2. The signal acquisition module 1 comprises a light source emitting unit 11, a gas-insulated metal-enclosed switchgear SF6 gas monitoring unit 12, an interference light filtering unit 13, and an optical signal output unit 14. The light source emitting unit 11, the gas-insulated metal-enclosed switchgear SF6 gas monitoring unit 12, the interference light filtering unit 13, and the optical signal output unit 14 are sequentially connected through optical fibers, and the optical signal output unit 14 is electrically connected to the data processing module 2;

[0021] The light source emitting unit 11 is used to emit light pulses in real time, the gas-insulated metal-enclosed switchgear SF6 gas monitoring unit 12 causes the light pulses to interfere and generate interference light, the interference light filtering unit 13 is used to filter out the output light of a specific wavelength, the optical signal output unit 14 converts the optical signal into an electrical signal, the data processing module 2 is used to convert the electrical signal into a time domain spectrogram, and the data processing module 2 analyzes and processes the time domain spectrogram. At the same time, the data processing module 2 converts the phase difference Δδ of the time domain spectrogram into a drift amount M×Δδ of the superimposed envelope signal, where M is the amplification factor, thereby achieving a several-fold increase in sensitivity, and the concentration of SF6 gas in the gas-insulated metal-enclosed switchgear SF6 gas monitoring unit 12 is calculated based on the drift amount M×Δδ, thereby preventing the phase difference Δδ from being too small and exceeding the spectral resolution limit of the existing spectrometer, resulting in serious errors in the detection results.

[0022] In the present invention, the light source emitting unit 11 may be a broadband light source, and the data processing module 2 may be a PC.

[0023] In one embodiment, the SF6 gas monitoring unit 12 of the gas-insulated metal-enclosed switchgear includes a light source branching unit 121, a gas-insulated metal-enclosed switchgear 122, an electric optical fiber delay line 123, a reference single-mode optical fiber 124, a first interference light merging unit 125, an interference light branching unit 126, and a second interference light merging unit 127. The light source emitting unit 11 is connected to the light source branching unit 121 through an optical fiber. The light source branching unit 121, the gas-insulated metal-enclosed switchgear 122, the first interference light merging unit 125, and the second interference light merging unit 127 are connected to the light source branching unit 121 through an optical fiber. The interference light filtering unit 13 is connected in sequence through optical fibers, the light source branching unit 121, the reference single-mode optical fiber 124, the second interference light merging unit 127, and the interference light filtering unit 13 are connected in sequence through optical fibers, the light source branching unit 121, the electric optical fiber delay line 123, and the interference light branching unit 126 are connected in sequence through optical fibers, and at the same time, one of the output ends of the interference light branching unit 126 is connected to the first interference light merging unit 125 through optical fibers, and the other output end of the interference light branching unit 126 is connected to the second interference light merging unit 127 through optical fibers;

[0024] The light source branching section 121 divides the light pulses emitted in real time by the light source emitting unit 11 into three paths. The light source branching section 121, the gas-insulated metal-enclosed switchgear 122, and the first interference light merging section 125 constitute a monitoring path. The light source branching section 121, the reference single-mode optical fiber 124, and the second interference light merging section 127 constitute a reference path. The light source branching section 121, the electric optical fiber delay line 123, and the interference light branching section 126 constitute a delay path. The test path and the delay path together constitute a first interferometer. Meanwhile, the delay path and the reference path together constitute a second interferometer. The light source branching section 121 passes the pulse light emitted by the light source emitting unit 11 through the monitoring path, the reference path, and the delay path respectively. The pulse light of the monitoring path passes through the gas-insulated metal-enclosed switchgear 122 through the optical fiber and is output by the first interference light merging section 125. The pulse light of the delay path passes through the electric optical fiber delay line 123 and is output by the interference light branching section 126. It is divided into two output paths, one of which is output by the first interference light merging unit 125, and the other is output by the second interference light merging unit 127. The pulse light of the reference path passes through the reference single-mode optical fiber 124 and is output by the second interference light merging unit 127. When the light pulse passes through the gas-insulated metal-enclosed switchgear 122 through the optical fiber, the SF6 gas in the gas-insulated metal-enclosed switchgear 122 is freed in the hollow core of the optical fiber. After the SF6 gas absorbs the infrared light of a specific wavelength in the light pulse, the refractive index of the light pulse in the optical fiber changes due to the thermo-optical effect, thereby causing a phase difference in the first interference light output by the first interferometer. The change in the refractive index is linearly positively correlated with the concentration of SF6 gas. The first interference light of the first interferometer and the second interference light of the second interferometer are both filtered out by the interference light filtering unit 13 to obtain the first output light and the second output light of a specific wavelength.

[0025] In the present invention, the light source branching portion 121 may be a 1*3 fiber coupler, and the first interference light merging portion 125, the interference light branching portion 126, and the second interference light merging portion 127 may all be 1*2 fiber couplers.

[0026] In one embodiment, the interference light filtering unit 13 includes a first interference light filtering unit 131 and a second interference light filtering unit 132. The first interference light filtering unit 131 is connected to the first interference light merging unit 125 via an optical fiber, and the second interference light filtering unit 132 is connected to the second interference light merging unit 127 via an optical fiber. The first interference light of the first interferometer is filtered out by the first interference light filtering unit 131 to obtain a first output light with a specific wavelength, and the second interference light of the second interferometer is filtered out by the second interference light filtering unit 132 to obtain a second output light with a specific wavelength.

[0027] In the present invention, the first interference light filter 131 and the second interference light filter 132 can both be a fiber circulator + a fiber Bragg grating.

[0028] In one embodiment, the optical signal output unit 14 includes a first optical signal output unit 141 and a second optical signal output unit 142. The first optical signal output unit 141 is connected to the first interference light filter unit 131 via an optical fiber, and the second optical signal output unit 142 is connected to the second interference light filter unit 132 via an optical fiber. The first optical signal output unit 141 converts the first output light into a first electrical signal, and the second optical signal output unit 142 converts the second output light into a second electrical signal.

[0029] In the present invention, both the first optical signal output unit 141 and the second optical signal output unit 142 may be photodetectors.

[0030] In one embodiment, the data processing module 2 includes a storage unit 21, a judgment unit 22, and a processing unit 23, wherein the storage unit 21, the judgment unit 22, and the processing unit 23 are electrically connected in sequence, the judgment unit 22 is electrically connected to the first optical signal output unit 141, and the processing unit 23 is electrically connected to the second optical signal output unit 142;

[0031] The storage unit 21 is used to store the normal time domain spectrogram I1(δ), the judgment unit 22 converts the first electrical signal into the monitoring time domain spectrogram I1(δ-τ), and the judgment unit 22 is used to judge whether a drift occurs between the normal time domain spectrogram I1(δ) and the monitoring time domain spectrogram I1(δ-τ) to produce a phase difference Δδ, the processing unit 23 converts the second electrical signal into the reference time domain spectrogram I2(δ), and the processing unit 23 is used to process the normal time domain spectrogram I1(δ), the monitoring time domain spectrogram I1(δ-τ), and the reference time domain spectrogram I2(δ) to obtain the drift amount M×Δδ of the superimposed envelope signal, and calculate the concentration of SF6 gas in the gas-insulated metal-enclosed switchgear 122 based on the drift amount M×Δδ.

[0032] Please see Figure 2-4 On the other hand, the detection method of the device for detecting SF6 gas based on time domain vernier infrared spectroscopy provided by the present invention specifically includes the following steps:

[0033] Step 1: The light source emitting unit 11 emits light pulses in real time. The light pulses pass through the SF6 gas monitoring unit 12 of the gas-insulated metal-enclosed switchgear to interfere with the light pulses and generate interference light. The interference light is filtered out by the interference light filtering unit 13 to obtain output light of a specific wavelength. The output light is converted into an electrical signal by the optical signal output unit 14 and transmitted to the data processing module 2;

[0034] Step 2: The data processing module 2 converts the electrical signal into a time domain spectrogram, and the data processing module 2 analyzes and processes the time domain spectrogram. At the same time, the data processing module 2 converts the phase difference Δδ of the time domain spectrogram into a drift M×Δδ of the superimposed envelope signal, where M is the amplification factor, and calculates the concentration of SF6 gas in the SF6 gas monitoring unit 12 of the gas-insulated metal-enclosed switchgear according to the drift M×Δδ.

[0035] In one embodiment, the step 1 is specifically:

[0036] S 11 : A light pulse emitted in real time is obtained through the light source emitting unit 11, and the light pulse is divided into three light pulses through the light source branching part. The three light pulses pass through the monitoring path, the reference path, and the delay path respectively, and the first interference light is obtained through the first interferometer formed by the test path and the delay path, and the second interference light is obtained through the second interferometer formed by the delay path and the reference path;

[0037] S 12 : The first interference light is filtered through the first interference light filter 131 to obtain a first output light with a specific wavelength, and the second interference light is filtered through the second interference light filter 132 to obtain a second output light with a specific wavelength;

[0038] S 13 : The first output light is converted into a first electrical signal through the first optical signal output unit 141 and transmitted to the data processing module 2, and the second output light is converted into a second electrical signal through the second optical signal output unit 142 and transmitted to the data processing module 2.

[0039] In one embodiment, the step 2 is specifically:

[0040] S 21 :The first electrical signal is converted into a monitoring time domain spectrum I1 (δ-τ),

[0041] The judgment unit 22 obtains the normal time domain spectrum I1(δ) pre-stored in the storage unit 21;

[0042] S 22:The judgment unit 22 compares the normal time domain spectrum diagram I1 (δ) with the monitoring time domain spectrum diagram I1 (δ-τ) to determine whether there is a drift between the normal time domain spectrum diagram I1 (δ) and the monitoring time domain spectrum diagram I1 (δ-τ) to produce a phase difference Δδ. When there is no drift between the normal time domain spectrum diagram I1 (δ) and the monitoring time domain spectrum diagram I1 (δ-τ) to produce a phase difference Δδ, the judgment unit 22 determines that the concentration of SF6 gas in the gas-insulated metal-enclosed switchgear 122 has not changed at this time, and it is not necessary to calculate the concentration of SF6 gas in the gas-insulated metal-enclosed switchgear 122 through the processing unit 21. When there is a drift between the normal time domain spectrum diagram I1 (δ) and the monitoring time domain spectrum diagram I1 (δ-τ) to produce a phase difference Δδ, the judgment unit 22 transmits the normal time domain spectrum diagram I1 (δ) and the monitoring time domain spectrum diagram I1 (δ-τ) to the processing unit 23;

[0043] S 23 : When the normal time-domain spectrogram I1(δ) and the monitoring time-domain spectrogram I1(δ-τ) drift to produce a phase difference Δδ, the processing unit 23 obtains the reference time-domain spectrogram I2(δ) through the second electrical signal, and the processing unit 23 superimposes the monitoring time-domain spectrogram I1(δ-τ) and the reference time-domain spectrogram I2(δ), and the normal time-domain spectrogram I1(δ) and the reference time-domain spectrogram I2(δ) to form a periodically fluctuating envelope, and the phase difference Δδ is converted into a drift amount M×Δδ of the superimposed envelope signal;

[0044] S 24 : The processing unit 23 calculates the drift amount M×Δδ of the superimposed envelope signal, and the processing unit 23 infers the gas concentration of SF6 in the gas-insulated metal-enclosed switchgear 122 according to the drift amount M×Δδ of the envelope signal.

[0045] Specifically, the normal time domain spectrogram I1(δ) pre-stored in the storage unit 21 can, on the one hand, be flexibly set by the staff according to the actual gas concentration of SF6 in the gas-insulated metal-enclosed switchgear 122 and pre-stored in the storage unit 21. On the other hand, when the gas-insulated metal-enclosed switchgear 122 is in normal working condition, the light pulse can be emitted in real time by the light source emitting unit 11. The light pulse passes through the first interferometer to obtain a normal first interference light. The normal first interference light is filtered out by the first interference light filter 131 to obtain a normal first output light of a specific wavelength. The normal first output light is converted into a normal first electrical signal by the first optical signal output unit 141 and transmitted to the judgment unit 22. The judgment unit 22 converts the normal first electrical signal into a normal time domain spectrogram I1(δ) and pre-stores it in the storage unit 21.

[0046] In one embodiment, the step S 24 In the equation, M of the drift amount M×Δδ is the magnification factor,

[0047]

[0048] λ FBG1 is the wavelength of the light filtered out by the first interference light filter 131, λ FBG2 is the wavelength of light filtered out by the second interference light filter 132 .

[0049] Specifically, when the wavelength of light filtered out by the first interference light filter 131 is 1550 nm and the wavelength of light filtered out by the second interference light filter 132 is 1551 nm, the first optical signal output unit 141 and the second optical signal output unit 142 will receive two time domain signals with slightly different frequencies, and convert the optical signals into electrical signals with periods T1 and T2 respectively.

[0050] In one embodiment, the magnitude of the amplification factor M can be adjusted by controlling the wavelength of light filtered out by the first interference light filter 131 and the wavelength of light filtered out by the second interference light filter 132, thereby converting a smaller phase difference Δδ into a drift amount M×Δδ of an envelope signal that is easy to calculate, thereby achieving improved sensitivity.

[0051] What is disclosed above is only a preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. A person skilled in the art can understand that all or part of the processes of the above embodiments and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A device for detecting SF6 gas based on time domain vernier infrared spectroscopy, characterized in that: It includes a signal acquisition module and a data processing module, the signal acquisition module is electrically connected to the data processing module, the signal acquisition module includes a light source emitting unit, a gas-insulated metal-enclosed switchgear SF6 gas monitoring unit, an interference light filtering unit, and an optical signal output unit, the light source emitting unit, the gas-insulated metal-enclosed switchgear SF6 gas monitoring unit, the interference light filtering unit, and the optical signal output unit are sequentially connected through optical fibers, and the optical signal output unit is electrically connected to the data processing module; The light source emitting unit is used to emit light pulses in real time, the gas-insulated metal-enclosed switchgear SF6 gas monitoring unit causes light pulses to interfere and generate interference light, the interference light filtering unit is used to filter out output light of a specific wavelength, the optical signal output unit converts the optical signal into an electrical signal, the data processing module is used to convert the electrical signal into a time domain spectrogram, and the data processing module is used to analyze and process the time domain spectrogram so that the phase difference Δδ of the time domain spectrogram is converted into a drift amount M×Δδ of the superimposed envelope signal, where M is the amplification factor, and the concentration of SF6 gas in the gas-insulated metal-enclosed switchgear SF6 gas monitoring unit is calculated based on the drift amount M×Δδ.

2. The device for detecting SF6 gas based on time domain vernier infrared spectroscopy according to claim 1 is characterized in that: The SF6 gas monitoring unit of the gas-insulated metal-enclosed switchgear comprises a light source branching part, a gas-insulated metal-enclosed switchgear, an electric fiber-optic delay line, a reference single-mode optical fiber, a first interference light merging part, an interference light branching part, and a second interference light merging part. The light source emitting unit is connected to the light source branching part through an optical fiber. The light source branching part, the gas-insulated metal-enclosed switchgear, the first interference light merging part, and the interference light filtering unit are connected in sequence through optical fibers. The light source branching part, the reference single-mode optical fiber, the second interference light merging part, and the interference light filtering unit are connected in sequence through optical fibers. The light source branching part, the electric fiber-optic delay line, and the interference light branching part are connected in sequence through optical fibers. At the same time, one of the output ends of the interference light branching part is connected to the first interference light merging part through an optical fiber, and the other output end of the interference light branching part is connected to the second interference light merging part through an optical fiber. The light source branching part divides the light pulses emitted in real time by the light source emitting unit into three paths. The light source branching part, the gas-insulated metal-enclosed switchgear, and the first interference light merging part constitute a monitoring path. The light source branching part, the reference single-mode optical fiber, and the second interference light merging part constitute a reference path. The light source branching part, the electric optical fiber delay line, and the interference light branching part constitute a delay path. The test path and the delay path together constitute a first interferometer. Meanwhile, the delay path and the reference path together constitute a second interferometer. The first interference light of the first interferometer and the second interference light of the second interferometer are both filtered out by the interference light filtering unit to obtain a first output light and a second output light of a specific wavelength.

3. The device for detecting SF6 gas based on time domain vernier infrared spectroscopy according to claim 2 is characterized in that: The interference light filtering unit includes a first interference light filtering unit and a second interference light filtering unit. The first interference light filtering unit is connected to the first interference light merging unit via an optical fiber, and the second interference light filtering unit is connected to the second interference light merging unit via an optical fiber. The first interference light of the first interferometer is filtered out into a first output light of a specific wavelength through the first interference light filtering unit, and the second interference light of the second interferometer is filtered out into a second output light of a specific wavelength through the second interference light filtering unit.

4. The device for detecting SF6 gas based on time domain vernier infrared spectroscopy according to claim 3 is characterized in that: The optical signal output unit includes a first optical signal output part and a second optical signal output part. The first optical signal output part is connected to the first interference light filtering part through an optical fiber, and the second optical signal output part is connected to the second interference light filtering part through an optical fiber. The first optical signal output part converts the first output light into a first electrical signal, and the second optical signal output part converts the second output light into a second electrical signal.

5. The device for detecting SF6 gas based on time domain vernier infrared spectroscopy according to claim 4 is characterized in that: The data processing module includes a storage unit, a judgment unit, and a processing unit, wherein the storage unit, the judgment unit, and the processing unit are electrically connected in sequence, the judgment unit is electrically connected to the first optical signal output unit, and the processing unit is electrically connected to the second optical signal output unit; The storage unit is used to store the normal time domain spectrogram I1(δ), the judgment unit converts the first electrical signal into the monitoring time domain spectrogram I1(δ-τ), and the judgment unit is used to judge whether a drift occurs between the normal time domain spectrogram I1(δ) and the monitoring time domain spectrogram I1(δ-τ) to produce a phase difference Δδ, the processing unit converts the second electrical signal into a reference time domain spectrogram I2(δ), and the processing unit is used to process the normal time domain spectrogram I1(δ), the monitoring time domain spectrogram I1(δ-τ), and the reference time domain spectrogram I2(δ) to obtain a drift amount M×Δδ of the superimposed envelope signal, and calculate the concentration of SF6 gas in the gas-insulated metal-enclosed switchgear based on the drift amount M×Δδ.

6. The detection method of the device for detecting SF6 gas based on time domain vernier infrared spectroscopy according to any one of claims 1 to 5, characterized in that: The specific steps include: Step 1: obtaining a real-time emitted light pulse through the light source emitting unit, the light pulse passing through the SF6 gas monitoring unit of the gas-insulated metal-enclosed switchgear causes interference of the light pulse and generates interference light, the interference light is filtered out by the interference light filtering unit to obtain output light of a specific wavelength, and the output light is converted into an electrical signal by the optical signal output unit and transmitted to the data processing module; Step 2: The data processing module converts the electrical signal into a time domain spectrogram, and analyzes and processes the time domain spectrogram, converts the phase difference Δδ of the time domain spectrogram into a drift M×Δδ of the superimposed envelope signal, where M is the amplification factor, and calculates the concentration of SF6 gas in the SF6 gas monitoring unit of the gas-insulated metal-enclosed switchgear based on the drift M×Δδ.

7. The detection method of the device for detecting SF6 gas based on time domain vernier infrared spectroscopy according to claim 6 is characterized in that: The step 1 is specifically as follows: S 11 :A light pulse emitted in real time is obtained by the light source emitting unit, and the light pulse is divided into three light pulses through the light source branching part, and the three light pulses pass through the monitoring path, the reference path, and the delay path respectively, and the first interference light is obtained by the first interferometer formed by the test path and the delay path, and the second interference light is obtained by the second interferometer formed by the delay path and the reference path; S 12 :The first interference light is filtered through the first interference light filter to obtain a first output light with a specific wavelength, and the second interference light is filtered through the second interference light filter to obtain a second output light with a specific wavelength; S 13 : The first output light is converted into the first electrical signal through the first optical signal output unit and transmitted to the data processing module, and the second output light is converted into the second electrical signal through the second optical signal output unit and transmitted to the data processing module.

8. The detection method of the device for detecting SF6 gas based on time domain vernier infrared spectroscopy according to claim 7 is characterized in that: The step 2 is specifically as follows: S 21 :The first electrical signal is converted into the monitoring time domain spectrum I1 (δ-τ), The judgment unit obtains the normal time domain spectrogram I1(δ) pre-stored in the storage unit; S 22 :The judgment unit compares the normal time domain spectrum graph I1 (δ) with the monitoring time domain spectrum graph I1 (δ-τ) to judge whether there is a drift between the normal time domain spectrum graph I1 (δ) and the monitoring time domain spectrum graph I1 (δ-τ) to produce a phase difference Δδ. When there is no drift between the normal time domain spectrum graph I1 (δ) and the monitoring time domain spectrum graph I1 (δ-τ) to produce a phase difference Δδ, the judgment unit determines that the concentration of SF6 gas in the gas-insulated metal-enclosed switchgear has not changed at this time, and it is not necessary to calculate the concentration of SF6 gas in the gas-insulated metal-enclosed switchgear through the processing unit. When there is a drift between the normal time domain spectrum graph I1 (δ) and the monitoring time domain spectrum graph I1 (δ-τ) to produce a phase difference Δδ, the judgment unit transmits the normal time domain spectrum graph I1 (δ) and the monitoring time domain spectrum graph I1 (δ-τ) to the processing unit; S 23 :When the normal time-domain spectrogram I1(δ) and the monitoring time-domain spectrogram I1(δ-τ) drift to produce a phase difference Δδ, the processing unit obtains a reference time-domain spectrogram I2(δ) through the second electrical signal, and the processing unit superimposes the monitoring time-domain spectrogram I1(δ-τ) and the reference time-domain spectrogram I2(δ), and the normal time-domain spectrogram I1(δ) and the reference time-domain spectrogram I2(δ) to form a periodically fluctuating envelope, and the phase difference Δδ is converted into the drift amount M×Δδ of the superimposed envelope signal; S 24 : The processing unit calculates the drift amount M×Δδ of the superimposed envelope signal, and the processing unit infers the gas concentration of SF6 in the gas-insulated metal-enclosed switchgear according to the drift amount M×Δδ of the envelope signal.

9. The detection method of the device for detecting SF6 gas based on time domain vernier infrared spectroscopy according to claim 8 is characterized in that: The step S 24 In the above equation, M of the drift amount M×Δδ is the magnification factor. λ FBG1 is the wavelength of the light filtered out by the first interference light filter, λ FBG2 is the wavelength of light filtered out by the second interference light filter.

10. The detection method of the device for detecting SF6 gas based on time domain vernier infrared spectroscopy according to claim 9 is characterized in that: The magnitude of the magnification M can be adjusted by controlling the wavelength of the light filtered out by the first interference light filter and the wavelength of the light filtered out by the second interference light filter.

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