Device and method for detecting hydrogen dissolved in transformer oil

Abstract

The invention relates to a device and a method for detecting dissolved hydrogen in transformer oil, and the device comprises a first single-mode optical fiber, a second single-mode optical fiber, a silicon dioxide column, a palladium-silver alloy column and a laser anti-reflection film which are obtained by cutting the same single-mode optical fiber, square holes are formed in non-fiber-core positions of cutting end faces of the first single-mode optical fiber and the second single-mode optical fiber, one end of the palladium-silver alloy column is fixedly connected with the first single-mode optical fiber through the square hole of the first single-mode optical fiber, and the other end of the palladium-silver alloy column is fixedly connected with the second single-mode optical fiber through the square hole of the second single-mode optical fiber. One end of the silicon dioxide column is fixedly attached to the non-fiber-core position of the cutting end face of the first single-mode optical fiber, and the other end of the silicon dioxide column is fixedly attached to the non-fiber-core position of the cutting end face of the second single-mode optical fiber. And the laser anti-reflection film is attached to optical fiber cores on the cutting end surfaces of the first single-mode optical fiber and the second single-mode optical fiber. According to the invention, the concentration of the hydrogen dissolved in the transformer oil can be detected without oil-gas separation.

Description

Technical Field

[0001] The invention relates to the technical field of transformer fault detection in an electric power system, and in particular to a device for detecting hydrogen dissolved in transformer oil. Background Art

[0002] As a key equipment in the power system, the safe and stable operation of the transformer is of vital importance. However, in the long-term operation of the transformer, it is inevitable that faults such as overheating and partial discharge will occur. These faults will cause the insulating oil and insulating paper materials inside the transformer to crack, producing various hydrocarbon characteristic gases such as acetylene. Therefore, the type and severity of the transformer fault can be reflected by monitoring the concentration of fault characteristic gases in the oil. Among them, optical fiber sensing technology has become an important means of transformer status monitoring due to its advantages such as small size, good insulation, and strong anti-electromagnetic interference ability.

[0003] Fiber optic sensing technologies include: Photothermal spectroscopy (PTS) sensing technology. PTS sensing technology is based on the principle of the photothermal effect of gas. Bulk molecules absorb part of the laser energy, transition to an excited state and release heat energy, which causes the gas temperature to rise. Temperature changes cause changes in the refractive index, which in turn affects the phase of the detection light. By monitoring the phase change of the emitted light, the concentration of the gas can be indirectly determined.

[0004] Fiber optic sensing technology also includes: photoacoustic spectroscopy (PAS) sensing technology. PAS sensing technology is based on the principle of the photoacoustic effect of gas. After gas molecules absorb infrared lasers, they will generate pressure waves, and their intensity is proportional to the gas concentration. Therefore, the gas concentration can be measured by inverting the intensity of the pressure wave.

[0005] PTS sensing technology relies on oil-gas separation. First, oil samples need to be taken at the transformer oil outlet, and then returned to the laboratory for oil-gas separation, chromatograph calibration, component detection and analysis. The above overall operation process is cumbersome and complicated. The detection is greatly affected by the sampling and degassing process, and the analysis results may have large errors. PAS sensing technology is sensitive to electromagnetic interference noise on site, which limits the possibility of field application of this method.

[0006] In summary, the existing PTS sensing technology and PAS sensing technology have the problems of large detection errors and being greatly affected by interference, and are not suitable for actual detection. Summary of the invention

[0007] Therefore, the technical problem to be solved by the present invention is to overcome the problems of large detection error and large interference influence in the prior art of transformer fault detection technology for power system.

[0008] In order to solve the above technical problems, the present invention provides a device for detecting dissolved hydrogen in transformer oil, comprising a first single-mode optical fiber and a second single-mode optical fiber cut from the same single-mode optical fiber, a silica column, a palladium-silver alloy column, and a laser anti-reflection and anti-reflection film, wherein: A square hole is provided at the non-core portion of the cut end surface of the first single-mode optical fiber and the second single-mode optical fiber, one end of the palladium-silver alloy column is fixedly connected to the first single-mode optical fiber through the square hole of the first single-mode optical fiber, and the other end of the palladium-silver alloy column is fixedly connected to the second single-mode optical fiber through the square hole of the second single-mode optical fiber; One end of the silica column is fixedly attached to the non-core portion of the cut end face of the first single-mode optical fiber, and the other end of the silica column is fixedly attached to the non-core portion of the cut end face of the second single-mode optical fiber; The laser anti-reflection and anti-reflection film is attached to the optical fiber cores of the cut end surfaces of the first single-mode optical fiber and the second single-mode optical fiber to enhance the transmittance of light in the optical fiber cores.

[0009] In one embodiment of the present invention, the silica column is in a straight state between the first single-mode optical fiber and the second single-mode optical fiber.

[0010] In one embodiment of the present invention, one end of the palladium-silver alloy column is fixedly connected to the square hole of the first single-mode optical fiber by means of a mixed glue, and the other end of the palladium-silver alloy column is fixedly connected to the square hole of the second single-mode optical fiber by means of a mixed glue; One end of the silica column is fixedly bonded to the cut end face of the first single-mode optical fiber by means of mixed glue, and the other end of the silica column is fixedly bonded to the cut end face of the second single-mode optical fiber by means of mixed glue.

[0011] In one embodiment of the present invention, the mixed glue is formed by mixing epoxy resin and epoxy resin curing agent in a ratio of 1:1.

[0012] In one embodiment of the present invention, the ratio of palladium to silver in the palladium-silver alloy column is 83%:27%.

[0013] In one embodiment of the present invention, the palladium-silver alloy column has a length of 1 cm, a width of 95 μm, and a height of 60 μm.

[0014] In one embodiment of the present invention, the length of the silica column is 1 cm, the width is 95 μm, and the height is 60 μm.

[0015] In one embodiment of the present invention, the square hole has a length of 100 μm, a width of 100 μm, and a height of 80 μm.

[0016] In one embodiment of the present invention, both ends of the palladium-silver alloy column are semi-elliptical, and both ends of the silicon dioxide column are semi-elliptical.

[0017] In order to solve the above technical problems, the present invention provides a method for detecting dissolved hydrogen in transformer oil, which is characterized by comprising: Step S1: Immerse the above-mentioned transformer oil dissolved hydrogen detection device in the oil sample at the transformer oil outlet, the palladium-silver alloy column will absorb the dissolved hydrogen in the oil and generate strain, resulting in bending, and the silicon dioxide column will not generate strain due to gas absorption; Step S2: After the palladium-silver alloy column bends due to hydrogen absorption, the entire transformer oil dissolved hydrogen detection device changes from a straight state to a bent state, thereby causing the path of the transmitted light in the first single-mode optical fiber and the second single-mode optical fiber to change, and a part of the light cannot be bound and escapes, resulting in a decrease in the optical power of the transmitted light; Step S3: Since the bending degree of the Pd-Ag alloy column subjected to strain is related to the concentration of absorbed hydrogen, the concentration of hydrogen dissolved in the transformer oil can be inverted by measuring the reduction in the optical power of the transmitted light.

[0018] The above technical solution of the present invention has the following advantages compared with the prior art: The device for detecting hydrogen dissolved in transformer oil of the present invention uses a palladium-silver alloy column to replace a part of the optical fiber area to form a sensing probe. Due to the specific absorption of hydrogen by the palladium-silver alloy column, cross interference of various gases dissolved in the oil can be eliminated. When the palladium-silver alloy absorbs hydrogen, it will deform, resulting in a decrease in the optical power of the transmitted light. By measuring the decrease in the optical power of the transmitted light, the concentration of hydrogen dissolved in the transformer oil can be inferred by inversion. The transformer oil dissolved hydrogen detection device of the present invention can detect the oil dissolved hydrogen without oil-gas separation, and has a short detection cycle and high detection efficiency. The palladium-silver alloy column in the device for detecting hydrogen dissolved in transformer oil of the present invention has a reversible process of absorbing and releasing hydrogen, has high reliability, long service life, high hardness and strong anti-interference performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0020] Figure 1 It is a structural schematic diagram of a device for detecting dissolved hydrogen in transformer oil according to the present invention. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention. Example

[0022] Reference Figure 1 As shown, the present invention relates to a device for detecting dissolved hydrogen in transformer oil, comprising: The first single-mode optical fiber 11 and the second single-mode optical fiber 12, the silica column 2, the palladium-silver alloy column 3, and the laser anti-reflection and anti-reflection film 5 are obtained by cutting the same single-mode optical fiber, wherein: The first single-mode optical fiber 11 and the second single-mode optical fiber 12 are both provided with square holes at the non-core locations of the cut end faces, one end of the palladium-silver alloy column 3 is fixedly connected to the first single-mode optical fiber 11 through the square hole of the first single-mode optical fiber 11, and the other end of the palladium-silver alloy column 3 is fixedly connected to the second single-mode optical fiber 12 through the square hole of the second single-mode optical fiber 12; One end of the silica column 2 is fixedly attached to the non-core portion of the cut end face of the first single-mode optical fiber 11, and the other end of the silica column 2 is fixedly attached to the non-core portion of the cut end face of the second single-mode optical fiber 12; the silica column 2 of this embodiment plays a supporting role to prevent the transformer oil dissolved hydrogen detection device from breaking in the middle.

[0023] from Figure 1 It can be seen that the two square holes are located in a straight line. The two non-core parts of the cut end faces of the first single-mode optical fiber 11 and the second single-mode optical fiber 12 used to connect the silica column 2 are also located in a straight line.

[0024] The laser anti-reflection and anti-reflection film 5 is attached to the fiber core of the cut end face of the first single-mode optical fiber 11 and the second single-mode optical fiber 12. The laser anti-reflection and anti-reflection film 5 is also called an anti-reflection film or an AR (Anti-Reflection) film, which belongs to the prior art. Its main function is to reduce the reflection of light, thereby increasing the transmittance of light. When hydrogen is detected specifically, light (transmitted light) is passed between the first single-mode optical fiber 11 and the second single-mode optical fiber 12. When no detection is performed, the light between the first single-mode optical fiber 11 and the second single-mode optical fiber 12 is turned off.

[0025] It is worth mentioning that in this embodiment, a palladium-silver alloy column 3 is used to replace part of the optical fiber area to form a sensing area; when the palladium-silver alloy column 3 absorbs hydrogen and deforms, the optical power of the transmitted light is reduced, and the concentration of hydrogen dissolved in the transformer oil can be inferred by measuring the reduction in the optical power of the transmitted light.

[0026] Palladium has special hydrogen absorption and specific selectivity due to the structure of its atomic electron layer. Therefore, the palladium-silver alloy column 3 used in this embodiment can effectively improve the hydrogen embrittlement phenomenon of pure palladium due to excessive hydrogen absorption concentration, accelerate the adsorption and desorption of hydrogen, and reduce the response time of the sensor probe.

[0027] Furthermore, the silica column 2 is in a straight state between the first single-mode optical fiber 11 and the second single-mode optical fiber 12 .

[0028] Furthermore, one end of the palladium-silver alloy column 3 is fixedly connected to the square hole of the first single-mode optical fiber 11 via a mixed glue 4, and the other end of the palladium-silver alloy column 3 is fixedly connected to the square hole of the second single-mode optical fiber 12 via a mixed glue 4; one end of the silica column 2 is fixedly bonded to the cut end face of the first single-mode optical fiber 11 via a mixed glue 4, and the other end of the silica column 2 is fixedly bonded to the cut end face of the second single-mode optical fiber 12 via a mixed glue 4.

[0029] Furthermore, the mixed glue 4 is formed by mixing epoxy resin and epoxy resin curing agent in a ratio of 1:1.

[0030] Furthermore, the ratio of palladium to silver in the palladium-silver alloy column 3 is 83%:27%.

[0031] The following is a detailed introduction to this embodiment: See also Figure 1 In this embodiment, a single-mode optical fiber is first cut into two sections with an optical fiber cutter to obtain a first single-mode optical fiber 11 and a second single-mode optical fiber 12, and the cut surface is ensured to be flat. Then, the first single-mode optical fiber 11 and the second single-mode optical fiber 12 are processed by using a focused ion beam technology, and a square hole with a length of 100 μm, a width of 100 μm, and a height of 80 μm is drilled into the end faces (not at the core) of the first single-mode optical fiber 11 and the second single-mode optical fiber 12, respectively. Then, a section of a palladium-silver alloy column 3 with a length of 1 cm, a width of 95 μm, a height of 60 μm, and a semi-elliptical shape at both ends is cut out using femtosecond laser technology, and a section of a silica column 2 with a length of 1 cm, a width of 95 μm, a height of 60 μm, and a semi-elliptical shape at both ends is cut out, wherein the composition ratio of the palladium-silver alloy column 3 is palladium: silver = 83%: 27%. Then, epoxy resin and epoxy resin curing agent are mixed and modulated in a ratio of 1:1 to form the mixed epoxy resin glue (i.e., mixed glue 4), and the palladium silver alloy column 3 is inserted into the square hole through micro-nano operation control technology and fixed by the mixed glue 4; the silica column 2 is straightly attached to the cutting plane (non-core) of the first single-mode optical fiber 11 and the second single-mode optical fiber 12, and the structure is fixed by the mixed glue 4. Finally, the laser anti-reflection mode 5 is attached to the core of the first single-mode optical fiber 11 and the second single-mode optical fiber 12 by magnetron sputtering technology to reduce the attenuation of the transmitted light and enhance the sensitivity of the detection device for dissolved hydrogen in transformer oil. Example

[0032] This embodiment provides a method for detecting dissolved hydrogen in transformer oil, comprising: Step S1: Immerse the transformer oil dissolved hydrogen detection device described in Example 1 in the oil sample at the transformer oil outlet. The palladium-silver alloy column 3 absorbs the hydrogen dissolved in the oil and generates strain, resulting in bending, while the silicon dioxide column 2 does not generate strain due to gas absorption; Step S2: After the palladium-silver alloy column 3 is bent due to hydrogen absorption, the entire transformer oil dissolved hydrogen detection device is changed from a straight state to a bent state, thereby causing the path of the transmitted light in the first single-mode optical fiber 11 and the second single-mode optical fiber 12 to change, and a part of the light cannot be restrained and escapes (in layman's terms, the palladium-silver alloy column 3 absorbs hydrogen and bends, causing the first single-mode optical fiber 11 and the second single-mode optical fiber 12 to be misaligned, and a part of the light will be dissipated due to the misalignment), resulting in a reduction in the optical power of the transmitted light; Step S3: Since the bending degree of the Pd-Ag alloy column 3 subjected to strain is related to the concentration of absorbed hydrogen, the concentration of hydrogen dissolved in the transformer oil can be inverted by measuring the reduction in the optical power of the transmitted light.

[0033] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0034] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A device for detecting dissolved hydrogen in transformer oil, characterized in that: It comprises a first single-mode optical fiber (11) and a second single-mode optical fiber (12) obtained by cutting the same single-mode optical fiber, a silica column (2), a palladium-silver alloy column (3), and a laser anti-reflection and anti-reflection film (5), wherein: The first single-mode optical fiber (11) and the second single-mode optical fiber (12) are both provided with square holes at non-core locations on the cut end faces, one end of the palladium-silver alloy column (3) is fixedly connected to the first single-mode optical fiber (11) via the square hole therein, and the other end of the palladium-silver alloy column (3) is fixedly connected to the second single-mode optical fiber (12) via the square hole therein; One end of the silica column (2) is fixedly attached to a non-core portion of a cut end surface of a first single-mode optical fiber (11), and the other end of the silica column (2) is fixedly attached to a non-core portion of a cut end surface of a second single-mode optical fiber (12); The laser anti-reflection and anti-reflection film (5) is attached to the optical fiber cores of the cut end faces of the first single-mode optical fiber (11) and the second single-mode optical fiber (12) to enhance the transmittance of light in the optical fiber cores.

2. The device for detecting dissolved hydrogen in transformer oil according to claim 1, characterized in that: The silica column (2) is in a straight state between the first single-mode optical fiber (11) and the second single-mode optical fiber (12).

3. The device for detecting dissolved hydrogen in transformer oil according to claim 1, characterized in that: One end of the palladium-silver alloy column (3) is fixedly connected to the square hole of the first single-mode optical fiber (11) via a mixed glue (4), and the other end of the palladium-silver alloy column (3) is fixedly connected to the square hole of the second single-mode optical fiber (12) via a mixed glue (4); One end of the silica column (2) is fixedly bonded to the cut end face of the first single-mode optical fiber (11) via a mixed glue (4), and the other end of the silica column (2) is fixedly bonded to the cut end face of the second single-mode optical fiber (12) via a mixed glue (4).

4. The device for detecting dissolved hydrogen in transformer oil according to claim 3, characterized in that: The mixed glue (4) is formed by mixing epoxy resin and epoxy resin curing agent in a ratio of 1:

1.

5. The device for detecting dissolved hydrogen in transformer oil according to claim 1, characterized in that: The ratio of palladium to silver in the palladium-silver alloy column (3) is 83%:27%.

6. The device for detecting dissolved hydrogen in transformer oil according to claim 1, characterized in that: The palladium-silver alloy column (3) has a length of 1 cm, a width of 95 μm, and a height of 60 μm.

7. The device for detecting dissolved hydrogen in transformer oil according to claim 1, characterized in that: The silica column (2) has a length of 1 cm, a width of 95 μm, and a height of 60 μm.

8. The device for detecting dissolved hydrogen in transformer oil according to claim 1, characterized in that: The square hole has a length of 100 μm, a width of 100 μm, and a height of 80 μm.

9. The device for detecting dissolved hydrogen in transformer oil according to claim 1, characterized in that: Both ends of the palladium-silver alloy column (3) are semi-elliptical, and both ends of the silicon dioxide column (2) are semi-elliptical.

10. A method for detecting dissolved hydrogen in transformer oil, characterized in that: include: Step S1: Immerse the transformer oil dissolved hydrogen detection device as described in any one of claims 1 to 9 in the oil sample at the transformer oil outlet, the palladium-silver alloy column (3) absorbs the hydrogen dissolved in the oil and generates strain, resulting in bending, and the silicon dioxide column (2) does not generate strain due to gas absorption; Step S2: after the palladium-silver alloy column (3) bends due to hydrogen absorption, the entire transformer oil dissolved hydrogen detection device changes from a straight state to a bent state, thereby causing the path of the transmitted light in the first single-mode optical fiber (11) and the second single-mode optical fiber (12) to change, and a part of the light cannot be restrained and escapes, resulting in a reduction in the optical power of the transmitted light; Step S3: Since the bending degree of the palladium-silver alloy column (3) subjected to strain is related to the concentration of absorbed hydrogen, the concentration of hydrogen dissolved in the transformer oil can be inverted by measuring the reduction in the optical power of the transmitted light.

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