CN114858781B - System for detecting dissolved gas in transformer oil based on Raman enhanced spectroscopy - Google Patents
System for detecting dissolved gas in transformer oil based on Raman enhanced spectroscopy Download PDFInfo
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- CN114858781B CN114858781B CN202210776414.8A CN202210776414A CN114858781B CN 114858781 B CN114858781 B CN 114858781B CN 202210776414 A CN202210776414 A CN 202210776414A CN 114858781 B CN114858781 B CN 114858781B
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- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
- G01N21/63—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light optically excited
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Abstract
The invention discloses a detection system for gas dissolved in transformer oil without oil-gas separation, and relates to a detection system for multi-component gas dissolved in transformer oil based on Raman spectroscopy and oil core photonic crystal fiber. The method comprises the following steps: the device comprises a laser power supply, a solid laser, a single-mode fiber, a Raman probe, an oil core photonic crystal fiber, an insulating packaging box, a Raman spectrometer, a collection card and an upper computer. The system is based on the principle of Raman spectroscopy, utilizes the interaction of laser emitted by a solid laser and gas molecules entering an oil core photonic crystal fiber through a Raman probe to generate Raman scattering, wherein backward Raman scattering light is transmitted to a Raman spectrometer through the Raman probe to obtain Raman spectrograms of various gases, and the Raman spectrograms are acquired by an acquisition card and then analyzed by an upper computer to obtain the types and the contents of various gases. Based on this, this system need not oil-gas separation and mist separation alright realize the normal position detection of dissolving multicomponent gas in the transformer oil, and then appraise transformer running state.
Description
Technical Field
The invention relates to the technical field of optical sensing systems, in particular to a system for detecting dissolved gas in transformer oil based on Raman enhanced spectroscopy.
Background
When the transformer runs for a long time, faults such as partial discharge, transformer overheating and the like often occur due to various uncertain factors, if the fault factors are not found and eliminated in time, the insulation aging of the transformer is accelerated to damage the transformer, and even serious personnel and property loss is caused. Therefore, the real-time monitoring of the running state of the transformer is carried out aiming at the fault characteristics of the transformer, and the early discovery, early alarm and early elimination of the fault are very important.
During common faults of the transformer, such as partial discharge, transformer overheating and the like, a plurality of fault characteristic gases are often generated. The type and concentration of fault gas generated when the transformer fails are closely related to whether the transformer fails or not and even the type of the fault, and the method is an important monitoring object for realizing transformer fault early warning. Especially, oil-immersed transformer, its inside oil, paper insulation system are easy to be because above-mentioned trouble takes place ageing rotten, produce multiple fault characteristic gas, include: hydrogen (H) 2 ) Methane (CH) 4 ) Acetylene (C) 2 H 2 ) Ethylene (C) 2 H 4 ) Ethane (C) 2 H 6 ) Carbon monoxide (CO), carbon dioxide (CO) 2 ) And the like. Different from other types of transformers, most fault gas generated by the oil-immersed transformer is directly dissolved in transformer oil, and direct detection is difficult to realize.
The traditional detection of dissolved gas in transformer oil adopts gas chromatography technology. On one hand, fault characteristic gas generated after the transformer breaks down diffuses to the position near the oil taking port to be extracted, oil-gas separation is carried out, mixed gas separation is carried out on multi-component gas, several hours or even more than ten hours are consumed, and even fault characteristic gas generated in a dead oil area of the transformer cannot easily reach the oil taking port, so that real-time detection is difficult to realize by the technology. On the other hand, the gas chromatography has poor quantitative detection capability, the performance of the chromatographic column is reduced along with the increase of time, and the trace gas dissolved in the oil is difficult to accurately detect.
In recent years, with the development of optical technology, people have attracted much attention to the detection of dissolved gas in oil by using an optical system. The detection method for the dissolved gas in the transformer oil at home and abroad mainly comprises the following steps: photoacoustic spectroscopy, raman spectroscopy, and infrared spectral absorption. Compared with the traditional gas chromatography, the Raman spectroscopy has the advantages of good repeatability, high sensitivity, wide detection range and the like, and can realize the simultaneous detection of multiple gases by using laser with single frequency without separating mixed gases. However, the problem that the oil-gas separation is long in time is still needed in the practical application of the Raman spectroscopy; on the other hand, the content of dissolved gas in the transformer oil is low, the Raman scattering area of gas molecules is small, the detection sensitivity needs to be improved by enhancing Raman scattering,
therefore, there is a need for a system based on raman spectroscopy technology, which can enhance raman scattering and improve detection sensitivity without oil-gas separation and real-time monitoring of the concentration of dissolved multi-component gases in transformer oil.
Disclosure of Invention
The invention aims to provide a system for detecting dissolved gas in transformer oil based on Raman enhanced spectroscopy, which is characterized by comprising a laser power supply, a solid laser, a single-mode fiber, a Raman probe, an oil core photonic crystal fiber, an insulating packaging box, a Raman spectrometer, a collection card and an upper computer.
Preferably, the solid laser is a CW 532nm laser (DPGL-2200) produced by Shanghai high-grade laser technology, inc., the output light wavelength of the laser is 532nm, the stable output power is not lower than 150mW, and the power is continuously adjustable. The laser power supply is LCD-2500 small laser power supply for controlling the solid laser.
The Raman probe comprises a main body part, an excitation optical fiber, a collection optical fiber and a transmission optical fiber, wherein the excitation optical fiber is used for transmitting light emitted by a light source to the main body part of the Raman probe and then transmitting the light to the inside of the oil core photonic crystal optical fiber through the transmission optical fiber, and the collection optical fiber is used for transmitting backward Raman scattering light generated in the oil core photonic crystal optical fiber to a Raman spectrometer.
Preferably, the excitation fiber, the collection fiber and the transmission fiber of the raman probe are all common single-mode fibers, and the measurement range of the raman probe is 200cm -1 ～4000cm -1 。
Preferably, the oil core photonic crystal fiber is prepared from an HC-800-02 type hollow photonic crystal fiber, and a plurality of micro-channels extending to a central core area are processed on the surface of the oil core photonic crystal fiber along the axial direction of the fiber. The oil core photonic crystal fiber is arranged in a transformer oil tank, transformer oil to be detected is filled in the fiber core, the refractive index of the transformer oil in the central core area is higher than that of the cladding, and not less than 95% of laser can be effectively bound in the micron-scale central core area of the oil core photonic crystal fiber to be transmitted. The oil core photonic crystal fiber is not only used as a gas chamber for generating Raman scattering by light and gas dissolved in oil, but also utilizes the hollow structural characteristic of the oil core photonic crystal fiber to reduce Raman scattering loss and realize the Raman enhancement effect.
Preferably, the diameter of the micro-channel processed on the surface of the oil core photonic crystal fiber and extending to the central core area is not more than 4 μm, the micro-channels are uniformly arranged along the axial direction of the fiber, the interval between the adjacent micro-channels is not more than 15cm, so that dissolved gas molecules in transformer oil can be timely diffused into the oil core photonic crystal fiber, and meanwhile, the good light transmission performance of the oil core photonic crystal fiber is ensured.
Preferably, one end of the oil core photonic crystal fiber is connected with the single-mode fiber in a low-loss fusion mode and used for connecting the Raman probe so as to transmit optical signals, wherein the fusion loss is not more than 2dB. The other end of the oil core photonic crystal fiber is sealed in a melting mode, and the reflectivity of the sealing section is not lower than 0.6, so that backward Raman scattering is formed.
Preferably, the central wavelength of the oil core photonic crystal fiber is 532nm, the radius of the central core area of the fiber is not more than 5 μm, and the length of the fiber is not less than 1m, so as to ensure that the dissolved gas in the oil fully interacts with the laser, thereby ensuring the stability of the generated backward Raman scattering intensity.
Preferably, the oil core photonic crystal fiber is wound in a single-layer disc shape, and the inner diameter of the wound optical fiber disc is not less than 4cm, and the outer diameter of the wound optical fiber disc is not more than 5cm, so that good optical transmission performance of the optical fiber disc is guaranteed. And placing the wound optical fiber disc into an insulating packaging box as a sensing unit on the upper part of a high-voltage winding in the transformer oil tank, wherein the distance between the optical fiber disc and the top of the oil tank is 10-15 cm. By the arrangement method, the time for convection diffusion of the fault gas of the transformer to the oil core photonic crystal fiber can be shortened, and the detection instantaneity is improved.
Preferably, the insulating packaging box is made of an insulating laminated board, so that the whole insulating packaging box has good oil resistance, pressure resistance and high temperature resistance, and the tolerance temperature is not lower than 150 ℃. The insulating packaging box does not break within the pressure range of 0.1MPa to 1MPa, and the detection performance of the internal oil core photonic crystal fiber in the oil tank environment is ensured.
Preferably, the insulating packaging box is integrally disc-shaped, the inside of the insulating packaging box is hollow, a circular opening is reserved in the middle of the side face and used for leading out a single-mode optical fiber which is welded with the oil core photonic crystal optical fiber, circular openings with the same size as the side face are uniformly distributed in the upper bottom face and the lower bottom face, and the center distance between the circular openings in the same bottom face is not smaller than 4mm, so that oil exchange between the inside of the insulating packaging box and the outside is guaranteed. The height of the insulating packaging box is 6mm, the thickness of the insulating packaging box is 1mm, the diameter of the disc is 6cm, and the diameter of the circular opening is 2mm. And after the wound oil core photonic crystal fiber is placed in an insulating packaging box, leading out the single mode fiber welded with the wound oil core photonic crystal fiber and filling the opening on the closed side with epoxy resin so as to fix the outlet part.
Preferably, the Raman spectrometer is an inVia micro Raman spectrometer of Renisshaw, UK with a spectral resolution of 1cm -1 Spatial longitudinal resolution of 2 μm and measurement range of 200cm -1 ~4000cm -1 So as to ensure that all kinds of fault characteristic gas can be scanned and detected.
Compared with the prior art for detecting the dissolved gas in the transformer oil, the invention has the beneficial effects that: (1) The oil core photonic crystal fiber is directly used as a place where light interacts with dissolved gas in oil to generate Raman scattering, so that the problem of long time consumption of oil-gas separation is solved, and real-time detection of the dissolved gas in the transformer oil is realized; (2) The hollow structure of the oil core photonic crystal fiber restrains gas molecules in the fiber core, reduces the loss of Raman scattering, overcomes the problem that Raman scattering signals generated by the small Raman scattering sectional area of the gas molecules are weak, and realizes the optical fiber enhancement of the Raman scattering; (3) The method for detecting the dissolved gas in the transformer oil based on the Raman enhanced spectrum avoids the problem of cross sensitivity of multiple fault characteristic gases, does not need to separate mixed gases, and realizes simultaneous detection of multi-component gases.
Drawings
In order to facilitate understanding of the effects and technical embodiments of the present invention, the following detailed description is given with reference to the accompanying drawings.
FIG. 1 is a topology of a system for detecting dissolved gas in oil immersed transformer oil based on Raman spectroscopy.
FIG. 2 is a schematic diagram of an oil core photonic crystal fiber.
Fig. 3 is a schematic view of an insulating enclosure.
Detailed Description
Referring to fig. 1, the invention provides a system for detecting dissolved gas in transformer oil based on raman enhanced spectroscopy, which comprises a laser power supply, a solid laser, a single-mode fiber, a raman probe, an oil core photonic crystal fiber, an insulating packaging box, a raman spectrometer, a collection card and an upper computer.
Referring to fig. 1, a laser power supply controls a solid laser to emit continuous laser with a single frequency, the continuous laser passes through a raman probe main body part along an excitation optical fiber and enters an oil core photonic crystal fiber placed in transformer oil through a transmission optical fiber, and light interacts with gas molecules entering the inside of the oil core photonic crystal fiber to generate inelastic raman scattering. Wherein the backward Raman scattering light is transmitted to the Raman spectrometer along the collecting optical fiber through the main body part of the Raman probe. According to the Raman scattering effect, a Raman spectrometer scans to obtain Raman spectrograms of various gases in the multi-component gas, data are collected by a collection card and processed by an upper computer, and the types and the contents of the gases in the multi-component gas can be obtained by quantitatively analyzing the Raman spectrograms of the various gases.
Referring to fig. 2, the oil core photonic crystal fiber is prepared from an HC-800-02 hollow photonic crystal fiber, and a plurality of microchannels reaching a central core region are axially processed on the surface of the oil core photonic crystal fiber, so as to allow dissolved gas molecules in oil to enter and ensure that laser is effectively bound in the central core region for transmission. The oil core photonic crystal fiber is arranged in the transformer oil tank, not only serves as a Raman scattering air chamber generated by dissolved gas in light and oil, but also can realize Raman enhancement and improve detection sensitivity by utilizing the hollow structural characteristic of the photonic crystal fiber. One end of the oil core photonic crystal fiber is connected with the single-mode fiber in a low-loss melting mode and used for being connected with the Raman probe to transmit optical signals, and the other end of the oil core photonic crystal fiber is sealed in a melting mode to form backward Raman scattering.
Referring to fig. 3, the oil core photonic crystal fiber of the present invention is wound in a single layer disk shape and placed in an insulating packaging box made of an insulating laminate. The insulating packaging box is disc-shaped, the inside is hollow, a round opening is reserved on the side face of the insulating packaging box, the insulating packaging box is used for leading out a single mode fiber connected with the oil core photonic crystal fiber, and the insulating packaging box is conveniently connected to a Raman probe. Circular openings with the same size as the side surfaces are uniformly distributed on the upper bottom surface and the lower bottom surface of the insulating packaging box, so that oil exchange between the inside of the insulating packaging box and the outside is guaranteed. And after the wound oil core photonic crystal fiber is placed in an insulating packaging box, leading out the single mode fiber which is welded with the oil core photonic crystal fiber, filling the opening on the closed side with epoxy resin, and fixing the outlet part.
Claims (3)
1. A detection system for dissolved gas in transformer oil based on Raman enhanced spectroscopy is characterized by comprising a laser power supply, a solid laser, a single-mode fiber, a Raman probe, an oil core photonic crystal fiber, an insulating packaging box, a Raman spectrometer, a collection card and an upper computer;
the oil core photonic crystal fiber is prepared from a hollow photonic crystal fiber, the length of the oil core photonic crystal fiber is not less than 1m, micro-channels with the diameter not more than 4 mu m and reaching the central core area are uniformly processed along the axial direction of the fiber, and the interval between every two adjacent micro-channels is not more than 15cm; the oil core photonic crystal fiber is arranged in a transformer oil tank, transformer oil to be detected is filled in the fiber core, the refractive index of the transformer oil in the central core area is higher than that of the cladding, and not less than 95% of laser can be effectively bound in the micron-scale central core area of the fiber to be transmitted; one end of the oil core photonic crystal fiber is connected with the single mode fiber in a melting mode, and the other end of the oil core photonic crystal fiber is sealed in a melting mode to form backward Raman scattering.
2. The system for detecting the dissolved gas in the transformer oil based on the Raman enhanced spectrum according to claim 1, wherein the oil core photonic crystal fiber is wound in a single-layer disc shape, the inner diameter of the wound optical fiber disc is not less than 4cm, the outer diameter of the wound optical fiber disc is not more than 5cm, and the optical fiber disc is placed in an insulating packaging box to be used as a sensing unit and directly placed in a transformer oil tank.
3. The system for detecting the dissolved gas in the transformer oil based on the raman enhanced spectrum according to claim 1, wherein the insulating packaging box is in a shape of a disk overall, the inside of the disk is hollow, the diameter of the disk is 6cm, the height of the disk is 6mm, and the upper bottom surface, the lower bottom surface and the side surfaces of the disk are made of insulating laminated boards with equal thickness, so as to form a hollow disk packaging structure with the thickness of 1 mm; a round opening with the diameter of 2mm is reserved in the middle of the side surface of the insulating packaging box; after the wound oil core photonic crystal fiber is placed in an insulating packaging box, leading out the single mode fiber which is welded with the oil core photonic crystal fiber from a side circular opening of the insulating packaging box, and filling and sealing the side circular opening with epoxy resin; circular openings with the same diameter as the side surface and 2mm are uniformly distributed on the upper bottom surface and the lower bottom surface of the insulating packaging box, and the center distance between the circular openings on the same bottom surface is not less than 4mm, so that the oil exchange between the inside and the outside of the insulating packaging box is realized.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004090510A1 (en) * | 2003-04-14 | 2004-10-21 | Alight Technologies A/S | Optical fibre needle for spectroscopic analysis of liquids |
| CN104807805A (en) * | 2015-05-04 | 2015-07-29 | 华北电力大学 | Detection device for gas dissolved in transformer oil based on Raman spectrum |
| CN104819880A (en) * | 2015-05-04 | 2015-08-05 | 华北电力大学 | Transformer oil-gas separation device based on hollow photonic crystal fiber |
| CN106940311A (en) * | 2017-05-03 | 2017-07-11 | 重庆大学 | The in-situ detection method of fault characteristic gases is dissolved in a kind of transformer oil |
| CN109781707A (en) * | 2019-03-13 | 2019-05-21 | 重庆大学 | It is a kind of based on optical fiber enhancing transformer oil in failure gas on-Line Monitor Device |
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- 2022-07-04 CN CN202210776414.8A patent/CN114858781B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004090510A1 (en) * | 2003-04-14 | 2004-10-21 | Alight Technologies A/S | Optical fibre needle for spectroscopic analysis of liquids |
| CN104807805A (en) * | 2015-05-04 | 2015-07-29 | 华北电力大学 | Detection device for gas dissolved in transformer oil based on Raman spectrum |
| CN104819880A (en) * | 2015-05-04 | 2015-08-05 | 华北电力大学 | Transformer oil-gas separation device based on hollow photonic crystal fiber |
| CN106940311A (en) * | 2017-05-03 | 2017-07-11 | 重庆大学 | The in-situ detection method of fault characteristic gases is dissolved in a kind of transformer oil |
| CN109781707A (en) * | 2019-03-13 | 2019-05-21 | 重庆大学 | It is a kind of based on optical fiber enhancing transformer oil in failure gas on-Line Monitor Device |
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