Multi-point gas detection device and method

Abstract

The invention relates to the technical field of gas detection, and mainly discloses a multi-point gas detection device.A detection unit comprises a laser used for emitting laser of the wave band wavelength absorbed by gas to be detected; the light splitting unit comprises a light splitting module and is used for distributing the laser into a plurality of paths of independent light signals according to a preset proportion, the tail end layout of a light splitting path covers a discharge hot spot area in the to-be-detected equipment, and the detection scheme is high in anti-interference capability, supports multi-point synchronous detection and is suitable for a severe environment, so that the accuracy of SF6 decomposition component detection is improved; and comprehensive data support is provided for equipment state evaluation. The invention further discloses a multi-point gas detection method, a single light source is divided into a plurality of independent detection channels through laser emission, laser splitting, gas measurement, concentration inversion and display uploading, all potential discharge hot spot areas in equipment are covered, the problem of leak detection of traditional TDLAS single-point detection is solved, SO2 absorption interference is avoided, and the error rate is reduced.

Description

Technical Field

[0001] The present invention relates to the field of gas detection, and in particular to a multi-point gas detection device and method. Background Art

[0002] As a high-voltage insulating medium, sulfur hexafluoride has excellent insulating properties and arc extinguishing properties compared with air and oil. Compared with traditional electrical equipment, the volume of sulfur hexafluoride electrical equipment is smaller than that of traditional electrical equipment under the same electrical insulation performance.

[0003] However, during the production and long-term operation of sulfur hexafluoride electrical equipment, various insulation defects inevitably exist inside the equipment. The partial discharge or abnormal overheating phenomena inside the equipment caused by these defects will lead to the decomposition of sulfur hexafluoride gas, and low-fluoride sulfides such as SF2, SF3, SF4, S2F 10 etc. will be generated during the decomposition process of sulfur hexafluoride gas.

[0004] If the sulfur hexafluoride gas in the equipment is pure gas, the low-fluoride sulfides will quickly undergo a reduction reaction and be reduced to sulfur hexafluoride. When there is a trace amount of water and oxygen inside the equipment, the low-fluoride sulfides generated by the decomposition of sulfur hexafluoride will react with them to generate a series of complex chemical reactions to form products such as SOF4, SOF2, SO2F2, SO2, etc. Among them, SOF4 can continue to react with trace amounts of water to generate SO2F2 and HF.

[0005] The decomposition components of sulfur hexafluoride, especially SO2F2, SOF2, and HF, have certain corrosiveness and toxicity, which will damage the inside of sulfur hexafluoride electrical equipment, pose a potential threat to the safe operation of the equipment, be unfavorable to the safe and stable operation of the power grid, and also bring a potential threat to the personal health and safety of on-site workers.

[0006] On the other hand, SO2F2, SOF2, and HF are generated when there are insulation defects inside the equipment. Detecting these typical decomposition components can effectively judge the operating state inside the equipment. The concentration information of SO2F2, SOF2, and HF can provide guiding suggestions for the maintenance of the equipment, and at the same time, it is helpful for on-site operators to operate safely, playing a positive role in the normal and safe operation of the equipment and the personal safety of operation and maintenance personnel.

[0007] Although the general TDLAS technology can achieve gas concentration detection, the absorption spectral bands of SOF2 and SO2 overlap (especially in the range of 7460 - 7470 nm), which will cause cross-interference errors in the detection data. In addition, the traditional TDLAS system uses single-point detection and cannot comprehensively reflect the SOF2 distribution in multiple discharge hot-spot areas inside the equipment. Therefore, there is an urgent need for a detection scheme with strong anti-interference ability, supporting multi-point synchronous detection and suitable for harsh environments, so as to improve the accuracy of SF6 decomposition component detection and provide comprehensive data support for equipment status evaluation. Summary of the Invention

[0008] Therefore, the technical problem to be solved by the present invention is that the general TDLAS technology adopts a single light source and single probe structure, which can only detect the SOF2 concentration at a single position inside the equipment. However, the distribution of discharge hot spots inside SF6 electrical equipment is random and dispersed, and single-point detection cannot comprehensively reflect the gas decomposition state inside the equipment, resulting in a high risk of missed detection. Moreover, since the decomposition components contain SO2, a single detection point cannot comprehensively reflect the SOF2 distribution in multiple discharge hot-spot areas inside the equipment.

[0009] The above technical problem is solved by the following technical solutions:

[0010] The present invention proposes a multi-point gas detection device, which includes a detection unit and a spectroscopic unit.

[0011] In a preferred embodiment of the multi-point gas detection device of the present invention: the detection unit includes a laser for emitting laser light with a wavelength in the absorption band of the gas to be measured; and,

[0012] The spectroscopic unit is connected to the detection unit and includes a spectroscopic module for distributing the laser light into several independent optical signals according to a preset ratio, and the end layout of the spectroscopic path covers the discharge hot-spot areas inside the equipment to be measured.

[0013] In a preferred embodiment of the multi-point gas detection device of the present invention: the detection unit further includes a drive demodulation module, and the drive demodulation module is connected to the laser for driving the laser to emit the laser light through an electrical signal.

[0014] In a preferred embodiment of the multi-point gas detection device of the present invention: the spectroscopic unit further includes a sensing probe for detecting the concentration of the gas to be measured and returning the absorbed optical signal to the spectroscopic module, and the sensing probe corresponds to each of the several optical signals;

[0015] The spectroscopic unit further includes an optical fiber channel for transmitting the several optical signals to the sensing probe.

[0016] In a preferred embodiment of the multi-point gas detection device of the present invention: The detection unit further includes a photoelectric detection module, connected to the optical fiber channel, for receiving several paths of the optical signals returned by the sensing probe and converting the optical signals into electrical signals.

[0017] In a preferred embodiment of the multi-point gas detection device of the present invention: The detection unit further includes a multiplexing module, connected to the photoelectric detection module. The multiplexing module sequentially switches several paths of electrical signals using time-division logic to avoid crosstalk between channels caused by parallel processing of multiple signals and ensure independent demodulation of each path of signal.

[0018] In a preferred embodiment of the multi-point gas detection device of the present invention: The detection unit further includes an interaction module for displaying the concentration of the gas to be measured. The interaction module is connected to the multiplexing module and can control multiplexing switching.

[0019] In a preferred embodiment of the multi-point gas detection device of the present invention: The detection unit further includes a power supply module, which is connected to the interaction module and the drive demodulation module and supplies power to the interaction module and the drive demodulation module.

[0020] In a preferred embodiment of the multi-point gas detection device of the present invention: The multiplexing module is also connected to the drive demodulation module, and transmits the electrical signal to the drive demodulation module. The drive demodulation module inversely calculates the concentration of the gas to be measured according to the electrical signal.

[0021] In a preferred embodiment of the multi-point gas detection device of the present invention: The sensing probe is a passive optical structure, including a metallurgical powder filter and a stainless steel shell. The metallurgical powder filter is used for waterproof and breathable, and the stainless steel shell is used to improve the vibration resistance and shock resistance of the sensing probe;

[0022] The drive demodulation module includes a thermoelectric cooler for controlling the temperature of the laser and adjusting the drive current.

[0023] The present invention also proposes a multi-point gas detection method, which includes emitting laser and dividing the laser into several paths to pass through the gas to be measured, and analyzing the returned laser to obtain the gas concentration near the probe, so as to improve the detection effect and comprehensively reflect the SOF2 distribution in multiple discharge hot spot areas inside the equipment.

[0024] In a preferred embodiment of the multi-point gas detection method of the present invention: Control the laser to emit laser through the drive demodulation module;

[0025] Divide the laser into several paths through the beam splitting module and transmit it to the sensing probe through the optical fiber channel;

[0026] The sensor probe is used to guide the laser through the gas to be measured, and the remaining light signal is returned to the photoelectric detection module;

[0027] The multi-channel switching module collects several electrical signals in a time-sharing manner and transmits them to the drive demodulation module to invert the concentration of the gas to be measured;

[0028] The multi-channel switching module receives the concentration information of the gas to be measured and transmits it to the interactive module, displays the concentration data of the detection points detected by several sensor probes, and uploads it to the information library through the interactive module.

[0029] The beneficial effect of the present invention is that a single light source is divided into several independent detection channels through a light splitting module, covering all potential discharge hotspots inside the equipment, such as the GIS cavity and circuit breaker contacts, etc., solving the missed detection problem of traditional TDLAS single-point detection, avoiding SO2 absorption interference, and reducing the error rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings of the embodiments of the present invention. Obviously, the drawings described below only relate to some embodiments of the present invention, and are not intended to limit the present invention.

[0031] Figure 1 shows a schematic diagram of a multi-point gas detection device;

[0032] Figure 2 A flow chart of a multi-point gas detection method is shown. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in detail below with reference to specific embodiments and the accompanying drawings.

[0034] The terms used in the present invention are those commonly used in the art in view of the functions of the present invention, but these terms may vary according to the intentions of those skilled in the art, precedents, or new technologies in the art. In addition, specific terms may be selected by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the present invention. Therefore, the terms used in the specification should not be understood as simple names, but rather as the meanings of the terms and the overall description of the present invention.

[0035] Reference Figure 1 This embodiment provides a multi-point gas detection device, including a detection unit 1, including a laser 11, for emitting laser light of a wavelength band absorbed by the gas to be detected; a spectrometer unit 2, connected to the detection unit 1, including a spectrometer module 21, for distributing the laser light into a plurality of independent optical signals according to a preset ratio, and the end layout of the spectrometer path covers the discharge hotspot area inside the device to be detected.

[0036] The core component of the detection unit 1 is the laser 11, which is used to emit laser light. The laser 11 is a distributed feedback semiconductor laser with a drive current of 90 mA, an output power of 16.1 mW, and is stabilized at 28.5 °C through a built-in thermoelectric cooler to ensure wavelength stability. It emits laser light with a wavelength of 7462.69 nm, which precisely matches the characteristic absorption peak of SOF2 gas and simultaneously avoids the absorption peak interference band of 7460.5 nm of SO2.

[0037] The core component of the beam splitting unit 2 is the beam splitting module 21, which is used to split the laser beam to increase the number of detection points, facilitating the placement of the gas detection probe of the beam splitting unit 2 at common partial discharge locations. The beam splitting module 21 can be a 16:1 fiber optic splitter, which evenly distributes the single beam emitted by the laser 11 into 16 independent optical signals and transmits them through optical fibers to 16 discharge hot spots inside the device to be measured, such as GIS cavities, circuit breaker contacts, etc., facilitating the gas detection probe to detect the gas composition and concentration.

[0038] As an alternative embodiment, the splitting ratio of the fiber optic splitter is evenly divided into 16 paths, and the optical power of each path is approximately 1.006 mW. The fiber type is single-mode fiber with a core diameter of 9 μm and a numerical aperture of 0.13; the layout logic is that the end of the splitting path covers all potential discharge hot spots inside the device, ensuring no blind spots in the detection by the gas detection probe.

[0039] During use, the laser 11 emits laser light with a wavelength of 7462.69 nm, which is split into 16 optical signals by the beam splitting module 21. Each optical signal is transmitted through an optical fiber to a preset discharge hot spot area. The SOF2 gas at each detection point absorbs the corresponding optical signal, and the absorption intensity is positively correlated with the concentration. The remaining optical signals return to the beam splitting module 21 through the original optical fiber. The 16 returned optical signals are aggregated by the beam splitting module 21, and the concentration of SOF2 at each point is inversely calculated using Beer's law based on the optical intensity attenuation value.

[0040] Refer to Figure 1 In this embodiment, a multi-point gas detection device is provided, including a detection unit 1, which includes a laser 11 for emitting laser light with a wavelength in the absorption band of the gas to be measured; a beam splitting unit 2, connected to the detection unit 1, which includes a beam splitting module 21 for distributing the laser light into a plurality of independent optical signals according to a preset ratio, and the end of the splitting path is arranged to cover the discharge hot spot area inside the device to be measured.

[0041] The core component of the detection unit 1 is the laser 11, and it also includes a drive and demodulation module 12, a photoelectric detection module 13, and a multi-channel switching module 14.

[0042] The laser 11 is used to emit laser light. The laser 11 is a distributed feedback semiconductor laser with a drive current of 90 mA, an output power of 16.1 mW, and is stabilized at 28.5 °C through a built-in thermoelectric cooler to ensure wavelength stability. It emits laser light with a wavelength of 7462.69 nm, which precisely matches the characteristic absorption peak of SOF2 gas and simultaneously avoids the absorption peak interference band of 7460.5 nm of SO2.

[0043] The drive demodulation module 12 drives the laser 11 to emit laser light through an electrical signal and processes the reflected laser light to invert the concentration of the gas.

[0044] The photoelectric detection module 13 consists of photodetectors. The number of photodetectors is the same as the number of spectral divisions, which converts the optical signal into an electrical signal. The electrical signal is amplified and then enters the multiplexing module 14, and through time-sharing logic, it enters the microcontroller processor of the drive demodulation module 12 to invert the concentration, and the SOF2 gas concentrations at 16 different positions are obtained in sequence.

[0045] The core component of the spectral division unit 2 is the spectral division module 21, and it also includes a sensing probe 23. The spectral division module 21 is used to split the laser beam to increase the number of detection points, facilitating the placement of the gas detection probe of the spectral division unit 2 at common partial discharge locations.

[0046] The spectral division module 21 can be a 16:1 fiber optic splitter, which evenly distributes the single beam emitted by the laser 11 into 16 independent optical signals and transmits them through optical fibers to 16 discharge hot spots inside the device to be measured, such as GIS cavities, circuit breaker contacts, etc., facilitating the gas detection probe to detect the gas composition and concentration.

[0047] As an alternative embodiment, the splitting ratio of the fiber optic splitter is evenly divided into 16 paths, the optical power of each path is approximately 1.006 mW, the fiber type is single-mode fiber, the core diameter is 9 μm, and the numerical aperture is 0.13; the layout logic is that the end of the splitting path covers all potential discharge hot spots inside the device to ensure no blind spots in the detection by the gas detection probe.

[0048] The sensing probe 23 consists of SOF2 probes with the same number as the spectral division. Each probe works independently, and its placement position is determined according to actual needs, basically placed at common partial discharge locations. The diameter and length of the SOF2 probe are 4 mm and 60 mm respectively, and it mainly consists of armored optical fiber, lens, mirror, etc.

[0049] The laser is transmitted to the SOF2 probe through armored optical fiber. After being collimated by a lens, it is reflected by two mirrors. The sensing probe 23 is connected to the detection unit 1 through armored optical cable. Each optical cable encapsulates two single-mode optical fibers. The core diameter of the optical fiber is about 9μm, and the numerical aperture is 0.13. The first optical fiber is the transmitting optical path, which is used to transmit the 7462.69nm laser emitted by the laser 11 from the detection unit 1 to the sensing probe 23 for irradiating the gas to be measured. The second optical fiber is the return optical path, which is used to reflect the remaining laser after being absorbed by the gas from the sensing probe 23 back to the detection unit 1 for the photoelectric detection module 13 to receive and demodulate. The double-fiber design realizes a closed optical path, ensuring the independent emission and recovery of the laser, avoiding signal crosstalk in single-fiber bidirectional transmission, such as backscattering interference, and improving the signal-to-noise ratio.

[0050] The metallurgical powder filter used for encapsulating the sensing probe 23 is made by high-temperature sintering and pressing of metal titanium and titanium alloy powder, and the pore diameter is 0.2 - 50μm. The filter has a pore diameter of 5 - 10μm and a thickness of 2mm. It has good permeability to gas molecules but can prevent water from entering. Of course, water vapor molecules may also enter, but water molecules do not have absorption in the 7462.69nm band, so it has no impact on the SOF2 detection.

[0051] The light absorption path of the sensing probe 23 is about 10cm. All components are pasted inside a stainless-steel shell, making it have anti-vibration and anti-impact capabilities. A waterproof and breathable metallurgical powder filter is provided on the side of the sensing probe 23, effectively preventing dust and water from entering the gas chamber and polluting the lens, and improving the robustness of the probe in harsh environments.

[0052] During use, the laser 11 emits 7462.69nm laser, which is divided into 16 optical signal paths by the beam splitting module 21. Each optical signal path is transmitted to a preset discharge hot spot area through an optical fiber. The SOF2 gas at each detection point absorbs the corresponding optical signal, and the absorption intensity is positively correlated with the concentration. The remaining optical signals return to the beam splitting module 21 through the original optical fiber. The 16 returned optical signal paths are aggregated by the beam splitting module 21, and the SOF2 concentration at each point is inversely calculated using the Beer-Lambert law based on the light intensity attenuation value.

[0053] Refer to Figure 2 , this embodiment provides a multi-point gas detection method, which includes emitting a laser, dividing the laser into several paths to pass through the gas to be measured, and analyzing the returned laser to obtain the gas concentration near the probe, thereby enhancing the detection effect and comprehensively reflecting the SOF2 distribution in multiple discharge hot spot areas inside the equipment.

[0054] Specifically, the driving and demodulation module 12 controls the laser 11 to emit laser light. The laser is a distributed feedback semiconductor laser with a working wavelength of 7462.69 nm. The driving current is set to 90 mA, and the output power is stabilized at 16.1 mW. The temperature of the laser is precisely controlled at 28.5 °C by a thermoelectric cooler to ensure wavelength stability and avoid detection errors caused by temperature drift.

[0055] The splitting module 21 splits the laser light into several paths and transmits it to the sensing probe 23 through the optical fiber channel 22; the splitting module 21 evenly distributes the single beam of laser light emitted by the laser into 16 independent optical signals through a 16:1 optical fiber splitter. Each optical signal is transmitted through a single-mode optical fiber with a core diameter of 9 μm and a numerical aperture of 0.13 to ensure low-loss and high-fidelity transmission characteristics. The optical fiber channel 22 adopts a dual-fiber encapsulation structure. Two optical fibers are encapsulated in each armored optical cable, which respectively undertake the functions of transmitting and receiving optical signals to form a closed-loop optical path system. The end of the splitting path is arranged according to the distribution law of internal discharge hot spots of the equipment. The 16 detection points are basically placed at common partial discharge locations.

[0056] The sensing probe 23 guides the laser light through the gas to be measured and returns the remaining optical signal to the photoelectric detection module 13; the sensing probe 23 guides the laser light through the gas environment to be measured through a passive optical structure. A lens group inside the probe collimates the light beam, and after reflection by a mirror, an effective absorption optical path of 10 cm is formed, enabling the SOF2 gas molecules to fully absorb the laser energy. The metallurgical powder filter is made of high-temperature sintered titanium alloy. The 5-10 μm pore size structure allows gas to permeate while blocking water vapor and particulate matter. The optical components encapsulated in a stainless steel shell have the ability to resist mechanical shock and electromagnetic interference. The residual optical signal after gas absorption returns along the original path of the receiving optical fiber and is transmitted to the photoelectric detection module 13 for signal conversion.

[0057] The multiplexing module 14 collects several electrical signals in a time-sharing manner and transmits them to the driving and demodulation module 12 to invert the concentration of the gas to be measured; the multiplexing module 14 adopts time-division multiplexing technology and sequentially collects 16 electrical signals according to a preset time sequence to effectively avoid signal crosstalk problems in parallel processing. The collected electrical signals are transmitted to the driving and demodulation module 12 after gain adjustment by a preamplifier, and concentration inversion calculation is performed based on the Beer-Lambert law. An environmental temperature compensation module can be embedded in the demodulation algorithm to eliminate the influence of temperature drift on the detection result through real-time calibration, and finally output the SOF2 concentration values at each detection point.

[0058] The gas concentration information to be measured is received by the multiplexing module 14 and transmitted to the interaction module 15, which displays the concentration data of the detection points detected by several sensing probes 23 and uploads them to the information database through the interaction module 15; after receiving the concentration data from the multiplexing module 14, the interaction module 15 displays the spatial distribution heat map of 16 detection points in real time through the human-machine interface. The display interface supports the historical data backtracking function and can retrieve the concentration change curves of each channel within any time period. The communication module packages and uploads the detection data to the cloud database and sends device status warning information when necessary. The operation and maintenance personnel can access the detection data on-site or remotely through the web page or mobile terminal to realize the intelligent status monitoring and fault diagnosis of electrical equipment.

[0059] Finally, it should be noted that the methods and devices described in detail above are only examples, and those skilled in the art can modify these examples in different ways as long as they do not depart from the scope of the present invention.

Claims

1. A multi-point gas detection device, characterized in that: including, a detection unit (1), including a laser (11) for emitting laser light with wavelengths in the absorption band of the gas to be measured; and, a spectroscopic unit (2) connected to the detection unit (1), including a spectroscopic module (21) for distributing the laser light into several independent optical signals according to a preset ratio, and the end layout of the spectroscopic path covers the internal discharge hot spot area of the device to be measured.

2. The multi-point gas detection device according to claim 1, characterized in that: The detection unit (1) further includes a drive demodulation module (12), and the drive demodulation module (12) is connected to the laser (11) for driving the laser (11) to emit the laser light through an electrical signal.

3. The multi-point gas detection device according to claim 2, characterized in that: The spectroscopic unit (2) further includes a sensing probe (23) for detecting the concentration of the gas to be measured and returning the absorbed optical signal to the spectroscopic module (21), and the sensing probe (23) corresponds to each of the several optical signals one by one; The spectroscopic unit (2) further includes an optical fiber channel (22) for transmitting the several optical signals to the sensing probe (23).

4. The multi-point gas detection device according to claim 3, characterized in that: The detection unit (1) further includes a photoelectric detection module (13) connected to the optical fiber channel (22) for receiving the several optical signals returned by the sensing probe (23) and converting the optical signals into electrical signals.

5. The multi-point gas detection device according to claim 4, characterized in that: The detection unit (1) further includes a multi-channel switching module (14) connected to the photoelectric detection module (13), and the multi-channel switching module (14) sequentially switches several electrical signals using time-division logic to avoid crosstalk between channels caused by parallel processing of multiple signals and ensure independent demodulation of each signal.

6. The multi-point gas detection device according to claim 5, characterized in that: The detection unit (1) further includes an interaction module (15) for displaying the concentration of the gas to be measured, and the interaction module (15) is connected to the multi-channel switching module (14) and can control multi-channel switching.

7. The multi-point gas detection device according to claim 6, characterized in that: The detection unit (1) further includes a power supply module (16), and the power supply module (16) is connected to the interaction module (15) and the drive demodulation module (12) and supplies power to the interaction module (15) and the drive demodulation module (12).

8. The multi-point gas detection device according to claim 7, characterized in that: The multi-channel switching module (14) is further connected to the drive demodulation module (12) to transmit the electrical signal to the drive demodulation module (12), and the drive demodulation module (12) inversely calculates the concentration of the gas to be measured according to the electrical signal.

9. The multi-point gas detection device according to claim 8, characterized in that: The sensing probe (23) is a passive optical structure, comprising a metallurgical powder filter and a stainless steel housing, wherein the metallurgical powder filter is used for waterproofing and breathability, and the stainless steel housing is used for improving the vibration and impact resistance of the sensing probe (23); The driving demodulation module (12) comprises a thermoelectric cooler for controlling the temperature of the laser (11) and regulating the driving current.

10. A multi-point gas detection method, applicable to the multi-point gas detection device described in claims 1 to 9, characterized in that: include, Controlling the laser (11) to emit laser light by driving the demodulation module (12); The laser light is divided into several paths by a light splitting module (21) and transmitted to a sensing probe (23) via an optical fiber channel (22); Using the sensing probe (23) to guide the laser through the gas to be measured, and returning the remaining light signal to the photoelectric detection module (13); A plurality of electrical signals are collected in a time-sharing manner through a multi-channel switching module (14), and are transmitted to a driving demodulation module (12) to invert the concentration of the gas to be measured; The concentration information of the gas to be measured is received through the multi-channel switching module (14) and transmitted to the interactive module (15), the concentration data of the detection points detected by the plurality of sensor probes (23) are displayed, and uploaded to the information library through the interactive module (15).

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