A method for diagnosing aging of a transformer based on insulating oil color development technology

Abstract

The application relates to a transformer aging diagnosis method based on an insulating oil color developing technology, and steps are as follows: S1: adopting transformer insulating oil and ordinary kraft paper to carry out oil-paper insulation accelerated thermal aging test, and selecting different aging times to sample, so as to obtain oil-paper insulation combinations with different aging degrees; S2: developing color observation is carried out on the insulating oil with different aging degrees in different wavelength excitation light sources, color developing images of the insulating oil with different aging degrees under the light emission of different excitation light sources are obtained, and a data model corresponding to the aging time of the insulating oil and RGB three-color numerical values is established, so that the aging state of the transformer is monitored and diagnosed. The change of the color developing characteristics of the insulating oil in the aging process is utilized, the aging degree of the transformer is directly reflected, and the defects that the current main physical and chemical and electrical characteristic quantities are limited in the field application to different degrees, there are many influencing factors, or the transformers are damaged due to oil replacement, oil filtration and other operations are solved.

Description

Technical Field

[0001] This invention belongs to the field of insulating materials technology, and in particular relates to a diagnostic method for transformer aging based on insulating oil color development technology. Background Technology

[0002] Power transformers are core equipment in power systems, connecting power generation, transmission, and distribution. Their safe and stable operation determines the safety and reliability of the power grid and is crucial for maintaining the stability of power supply and the economic efficiency of power equipment investment. Currently, many transformers in my country have been in operation for over 20 years, and some even exceed 30 years. This increasing aging significantly increases the probability of transformer failures. Therefore, accurately assessing the degree of transformer aging and predicting its remaining lifespan is of paramount importance for transformer operation, maintenance, and decommissioning.

[0003] Chinese patent document CN110031443A discloses a portable Raman spectroscopy diagnostic device and method for the aging state of oil-paper insulation, belonging to the field of online monitoring and fault diagnosis of electrical equipment insulation. It solves the problems of existing oil-paper insulation aging state diagnostic methods, such as the need for numerous devices, complex testing procedures, and the inability to achieve in-situ detection in oil. The technical solution of this invention obtains Raman spectra of oil-paper insulation samples in different aging states based on different Raman signals generated when irradiated by laser, establishing a Raman fingerprint database of oil-paper insulation in different aging states. The aging state of the oil-paper insulation sample corresponding to the closest Raman spectrum in the database is used as the diagnostic result output. However, establishing the oil-paper insulation Raman fingerprint database requires a large amount of sample accumulation. Although the method is effective, it consumes a significant amount of time. Furthermore, during actual sampling and comparison, it is impossible to completely guarantee that the environmental conditions during actual sampling are exactly the same as the sampling conditions of the aging samples corresponding to the database, which leads to a decrease in the reliability of the judgment.

[0004] Chinese patent document CN114018885A discloses a method for monitoring the aging degree of transformer insulating oil, belonging to the technical field of transformer aging degree monitoring in power equipment. The technical solution of this invention includes measuring the three-dimensional fluorescence of transformer insulating oil at different aging degrees, constructing an aging degree model of the transformer insulating oil, and determining the aging degree of the transformer insulating oil based on the aging degree model. This invention can predict potential equipment faults through early and real-time diagnostic results, thereby effectively monitoring the insulation performance of transformer insulating oil, improving the real-time nature of detection, avoiding equipment accidents, reducing major losses, improving the reliability of equipment operation, and ultimately ensuring the safe operation of the power system. However, this invention only focuses on the analysis of fluorescence intensity spectra; while effective, the method is not intuitive enough. If the spectral data could be directly expressed through simple color information, the correlation between color rendering characteristics and aging degree could be more clearly and intuitively reflected through color conversion, making it clearer, simpler, and more convenient.

[0005] Oil-immersed power transformers are a core component of power systems, and oil-paper insulation is the primary insulation method within them, significantly determining their service life. Existing online monitoring methods for transformer service life rely on characteristic quantities such as polymerization degree, furfural, and carbon and oxygen gases in the oil, which suffer from drawbacks such as requiring power outages, insensitivity in the early and mid-stages of aging, and susceptibility to loss. Therefore, proposing a rapid, sensitive, and non-destructive method for assessing the aging status of transformer oil-paper insulation systems is crucial for the safe operation of transformers. Vegetable insulating oils are mainly composed of unsaturated fatty acids and linoleic acid, which produce fatty acids and oils during aging. These substances contain numerous electron-donating groups such as hydroxyl and alkoxy groups, exhibiting a colorimetric reaction similar to that of mineral insulating oils upon exposure to light. The aromatic hydrocarbons in insulating oils endow them with unique colorimetric properties, providing feasibility for the application of colorimetric technology in online transformer monitoring. Zhao Yue et al. disclosed a method for monitoring the aging degree of transformer insulating oil, which belongs to the field of power equipment transformer aging degree monitoring technology. The problem to be solved is how to establish a transformer fault diagnosis model based on the fluorescence characteristics of transformer insulating oil after aging, so as to realize the judgment of transformer discharge breakdown or oxidation degree. However, it only stays at the analysis of photoluminescence spectrum. Although the method is effective, it is not intuitive enough. Summary of the Invention

[0006] The purpose of this invention is to provide a diagnostic method for transformer aging based on insulating oil colorimetric technology. This method utilizes the changes in the colorimetric characteristics of insulating oil during aging, combined with RGB three-color values, to intuitively reflect the degree of transformer aging. In other words, spectral data information is directly expressed through simple color information, which more clearly reflects the correlation between colorimetric characteristics and the degree of aging through color conversion. This method is clearer, simpler, and more convenient. It solves the problems of current methods where major physicochemical and electrical characteristics are limited in field application, influenced by numerous factors, or lost due to transformer oil changes, filtration, and other operations.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is a method for diagnosing transformer aging based on insulating oil color development technology, which specifically includes the following steps:

[0008] S1: The accelerated thermal aging test of oil-paper insulation was carried out using transformer insulating oil and ordinary kraft paper to simulate the thermal aging process of oil-paper insulation inside the transformer. Samples were taken at different aging times to obtain oil-paper insulation combinations with different aging degrees.

[0009] S2: Colorimetric observations are performed on insulating oils with different aging degrees under excitation light sources of different wavelengths to obtain colorimetric images of insulating oils with different aging degrees under different excitation light sources. A data model is established to correspond the aging time of the insulating oil with the RGB three-color values, thereby monitoring and diagnosing the aging status of the transformer.

[0010] Using the above-mentioned technical solution, with mineral insulating oil as the test object, it has advantages such as speed, non-destructiveness, sensitivity, and convenience. It is not easily affected by transformer oil filtration or oil change operations. Transformer insulating oil has a conjugated system of polycyclic aromatic hydrocarbons. This structure allows it to absorb energy when irradiated by a light source, and electrons undergo energy level transitions. Subsequently, the high-energy electrons lose activity and emit photons, thus displaying light with different properties. Once the light source is removed, the colored light beams also quickly disappear. Plant-based insulating oil mainly consists of unsaturated fatty acids, linoleic acid, etc. During aging, it produces fatty acids and oils. These substances contain a large number of electron-donating groups such as hydroxyl and alkoxy groups, which produce a similar color reaction to mineral insulating oil when irradiated by a light source. Utilizing the changes in the color characteristics of insulating oil during aging, the aging degree of the transformer can be intuitively reflected. This solves the shortcomings of current methods for assessing the aging of major physicochemical and electrical characteristics, such as limited field application, numerous influencing factors, and loss due to transformer oil changes or filtration operations. This provides a new approach and a practical method for assessing transformer aging.

[0011] As a preferred technical solution of the present invention, the specific steps of step S1 are as follows: selecting 120-130℃ as the thermal aging temperature for accelerated thermal aging test; setting the sampling time for vegetable insulating oil to 0-90 days, and setting the sampling time for mineral insulating oil to 0-60 days.

[0012] As a preferred embodiment of the present invention, the specific steps of step S2 are as follows:

[0013] S21: First, perform colorimetric observation on the insulating oil obtained at the selected sampling time of 0, obtain its colorimetric image, and then transmit the data to the data processing system for colorimetric image processing and recording.

[0014] S22: Place the insulating oils with different aging degrees obtained at other sampling times selected in step S1 into the colorimetric characteristic observation platform for colorimetric observation, obtain colorimetric images of insulating oils with different aging degrees, and transmit the data to the data processing system for colorimetric image processing and recording.

[0015] S23: Change the excitation light source and repeat steps S21 to S22 to obtain color images of insulating oil with different aging degrees under different excitation light sources;

[0016] S24: Obtain the RGB three-color values ​​corresponding to the color development colors of insulating oil at different aging levels through color development image processing software, and establish a data model corresponding to the aging time of insulating oil and the RGB three-color values.

[0017] Using the above technical solution, the same type of insulating oil exhibits different color development characteristics under different excitation light. When the insulating oil is not aged, its color development characteristics fall into the blue, green, and yellow ranges, respectively, when excited by ultraviolet, blue, and green light. For insulating oils at different aging stages, the color intensity gradually decreases with increasing aging, and the color development characteristics shift towards longer wavelengths. Under ultraviolet, blue, and green light excitation, the color of mineral insulating oil changes to green, yellow, and orange, while the color of plant-based insulating oil changes to blue-green, yellow-orange, and orange-red. After processing by an RGB three-color detector, the displayed colors are converted into RGB three-color values. Mineral insulating oil corresponds to the color range of green (0, 255, 0), yellow (255, 255, 0), and orange (255, 15, 0); plant insulating oil corresponds to the color range of blue-green (0, 255, 255), yellow-orange (255, 215, 0), and orange-red (255, 69, 0). Therefore, the RGB three-color values ​​corresponding to the displayed colors of the insulating oil are selected as aging characteristic quantities to intuitively reflect the different degrees of aging of the insulating oil, thus serving as a new assessment method for transformer aging diagnosis.

[0018] As a preferred technical solution of the present invention, the specific steps of step S21 are as follows:

[0019] S211: At room temperature, turn on the colorimetric characteristic observation platform switch and select ultraviolet excitation light with a wavelength range of 330-400nm;

[0020] S212: Clean the liquid sample cell with anhydrous ethanol. After the anhydrous ethanol evaporates, place 5 mL of the selected insulating oil sample with a sampling time of 0 into the liquid sample cell.

[0021] S213: Excitation light of a specific wavelength is transmitted through an excitation monochromator and irradiates the insulating oil. After being irradiated by light, the insulating oil absorbs energy, and electrons achieve energy level transitions, completing the color development process of rapid deactivation and emitting photons.

[0022] S214: The color-developing light of the insulating oil is filtered by the emission monochromator to remove stray light and noise. The light is then focused along the optical path to the photomultiplier tube to obtain an enhanced light signal. The light is then transmitted through the optical fiber to the RGB three-color detector. The RGB three-color detector transmits the collected color-developing light signal to the data processing system, which converts the light signal into an electrical signal for color image processing and recording.

[0023] As a preferred technical solution of the present invention, the liquid sample cell is cleaned with anhydrous ethanol at room temperature. After the anhydrous ethanol evaporates, 5 mL of insulating oil with different aging degrees is placed in the liquid sample cell. Steps S213 to S214 are repeated to obtain color images of insulating oil with different aging degrees under ultraviolet excitation light.

[0024] As a preferred technical solution of the present invention, the specific steps of step S23 are as follows: the excitation light source is replaced with blue light with a wavelength range of 420-485nm and green light with a wavelength range of 490-550nm respectively; samples of mineral insulating oil with an aging time of 0-60 days are selected, and samples of plant insulating oil with an aging time of 0-90 days are selected; steps S21-S22 are repeated to obtain color images of the insulating oil under blue and green excitation light respectively.

[0025] As a preferred technical solution of the present invention, the specific steps of step S23 are as follows: the excitation light source is replaced with blue excitation light with a wavelength range of 420-485nm and green excitation light with a wavelength range of 490-550nm respectively, and steps S21-S22 are repeated to obtain color images of insulating oil with different aging degrees under blue excitation light and green excitation light respectively.

[0026] As a preferred embodiment of the present invention, in step S1, 130°C is selected as the thermal aging test temperature. The sampling time for vegetable insulating oil is set to 0, 7, 15, 22, 35, 60, and 90 days, and the sampling time for mineral insulating oil is set to 0, 7, 15, 22, 35, and 60 days. The selection of 130°C as the thermal aging test temperature allows for the acquisition of oil-paper insulation combinations with different aging degrees through sampling at different times. Vegetable insulating oil retains its fluorescent color-developing characteristics even after 90 days of thermal aging, and the non-specific fluorescent carbonaceous particles formed during the thermal aging process help maintain these characteristics. Polycyclic aromatic hydrocarbons in mineral insulating oil are degraded into smaller molecular fragments, and samples after 60 days of thermal aging lose their fluorescent color-developing characteristics. Therefore, the sampling time for vegetable insulating oil is set to 0, 7, 15, 22, 35, 60, 90, and 120 days, and the sampling time for mineral insulating oil is set to 0, 7, 15, 22, 35, and 60 days.

[0027] Compared with existing technologies, the transformer aging diagnosis method based on insulating oil color development technology of the present invention has the following advantages: by utilizing the changes in the color development characteristics of insulating oil during the aging process, the RGB three-color values ​​corresponding to the color development of the insulating oil are selected as aging characteristic quantities, which intuitively reflect the different degrees of aging of the insulating oil, thereby intuitively reflecting the aging degree of the transformer. This solves the shortcomings of the current main physical, chemical and electrical characteristic quantities, such as limited field application, numerous influencing factors, or loss due to transformer oil replacement, oil filtration and other operations. It will provide a new idea and a practical method for transformer aging assessment, and can serve as a new assessment method for transformer aging diagnosis. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the mineral insulating oil colorimetric observation platform in the transformer aging diagnosis method based on insulating oil colorimetric technology of the present invention;

[0029] Figure 2 These are color images of mineral insulating oils at different aging levels in the transformer aging diagnosis method based on insulating oil color development technology of the present invention. Detailed Implementation

[0030] Example: This method for diagnosing transformer aging based on insulating oil color development technology specifically includes the following steps:

[0031] S1: An accelerated thermal aging test of oil-paper insulation was conducted using transformer insulating oil and ordinary kraft paper to simulate the thermal aging process of oil-paper insulation inside a transformer. Samples were taken at different aging times to obtain oil-paper insulation combinations with different aging degrees. The specific steps of step S1 are as follows: an accelerated thermal aging test was conducted at a thermal aging temperature of 120-130℃; the sampling time for vegetable insulating oil was set to 0-90 days, and the sampling time for mineral insulating oil was set to 0-60 days.

[0032] The specific steps of step S1 are as follows:

[0033] S11: Treat the insulating paper and mineral insulating oil separately under vacuum conditions of 50Pa / 90℃ for 48h;

[0034] S12: The insulating paper and mineral insulating oil are mixed in a certain proportion and placed in a 5L ground glass reagent bottle. The mixture is then treated under vacuum conditions of 50Pa / 90℃ for 48 hours to ensure that the insulating paper is fully impregnated with the mineral insulating oil. After drying and degassing, moisture and gas are removed. In step S12, the insulating paper and mineral insulating oil are mixed at a mass ratio of 1:15. After drying and degassing, the initial moisture content of the insulating paper is 0.5%, the initial moisture content of the mineral insulating oil is approximately 10μg / mL, and the dielectric loss is 0.05%.

[0035] S13: After the oil paper insulation has dried and degassed, remove the ground glass bottle and add a copper strip; the dimensions of the copper strip added in step S13 are: 50cm × 1.5cm × 0.1cm; the surface area of ​​the copper strip is approximately 150cm². 2 The thickness of the copper strip is very thin and has no impact on the results; therefore, the thickness of the copper strip can be ignored.

[0036] S14: After the ground glass reagent bottle has been dried, it is sealed with a 180℃ high-temperature resistant plastic wrap. The bottle is not completely filled with mineral insulating oil during sealing, leaving 15% of the space remaining. The bottle is then placed in an aging chamber for accelerated thermal aging testing. The accelerated thermal aging test is conducted at a temperature of 120–130℃. The sampling time for vegetable insulating oil is set to 0–90 days, and for mineral insulating oil, it is set to 0–60 days. Preferably, the thermal aging temperature for the accelerated thermal aging test is 130℃. The aging time for sampling is set to 0, 7, 15, 22, 35, 60, 90, and 120 days. With 130℃ selected as the thermal aging test temperature, oil-paper insulation combinations with different aging degrees are obtained by sampling at different times. The vegetable insulating oil still exhibits fluorescent color-developing characteristics after 90 days of thermal aging, and the non-specific fluorescent carbon particles formed during the thermal aging process help maintain its fluorescent color-developing characteristics. Polycyclic aromatic hydrocarbons in mineral insulating oils are degraded into smaller molecular fragments, and samples aged for 60 days lose their fluorescent color development properties. Therefore, the sampling times for plant-based insulating oils were set at 0, 7, 15, 22, 35, 60, and 90 days, and the sampling times for mineral insulating oils were set at 0, 7, 15, 22, 35, and 60 days.

[0037] S2: Colorimetric observations are performed on insulating oils with different aging degrees under excitation light sources of different wavelengths to obtain colorimetric images of the insulating oils with different aging degrees under different excitation light sources. A data model corresponding to the aging time of the insulating oil and the RGB three-color values ​​is established to monitor and diagnose the aging status of the transformer; the principle of the colorimetric observation platform is as follows: Figure 1 As shown;

[0038] The specific steps of step S2 are as follows:

[0039] S21: First, perform colorimetric observation on the insulating oil obtained at the selected sampling time of 0, obtain its colorimetric image, and then transmit the data to the data processing system for colorimetric image processing and recording.

[0040] The specific steps of step S21 are as follows:

[0041] S211: At room temperature, turn on the colorimetric characteristic observation platform switch and select ultraviolet excitation light with a wavelength range of 330-400nm;

[0042] S212: Clean the liquid sample cell with anhydrous ethanol. After the anhydrous ethanol evaporates, place 5 mL of the selected insulating oil sample with a sampling time of 0 into the liquid sample cell.

[0043] S213: Excitation light of a specific wavelength is transmitted through an excitation monochromator and irradiates the insulating oil. After being irradiated by light, the insulating oil absorbs energy, and electrons achieve energy level transitions, completing the color development process of rapid deactivation and emitting photons.

[0044] S214: The color-developing light of the insulating oil is filtered by the emission monochromator to remove stray light and noise. The light is then focused along the optical path to the photomultiplier tube to obtain an enhanced light signal. The light is then transmitted through the optical fiber to the RGB three-color detector. The RGB three-color detector transmits the collected color-developing light signal to the data processing system, which converts the light signal into an electrical signal for color image processing and recording.

[0045] S22: Place the insulating oils with different aging degrees obtained at other sampling times selected in step S1 into the colorimetric characteristic observation platform for colorimetric observation, obtain colorimetric images of insulating oils with different aging degrees, and transmit the data to the data processing system for colorimetric image processing and recording.

[0046] The specific steps of step S22 are as follows: at room temperature, the liquid sample cell is cleaned with anhydrous ethanol. After the anhydrous ethanol evaporates, 5 mL of insulating oil with different aging degrees is placed in the liquid sample cell. Steps S213 to S214 are repeated to obtain color images of insulating oil with different aging degrees under ultraviolet excitation light.

[0047] S23: Change the excitation light source and repeat steps S21-S22 to obtain color images of insulating oils with different aging levels under different excitation light sources; the specific steps of step S23 are as follows: replace the excitation light source with blue excitation light with a wavelength range of 420-485nm and green excitation light with a wavelength range of 490-550nm respectively; select samples of mineral insulating oil with an aging time of 0-60 days and samples of plant insulating oil with an aging time of 0-90 days; repeat steps S21-S22 to obtain color images of insulating oils with different aging levels under blue excitation light and green excitation light respectively;

[0048] S24: Obtain the RGB three-color values ​​corresponding to the color development colors of insulating oil at different aging levels through color development image software, and establish a data model corresponding to the aging time of insulating oil and the RGB three-color values.

[0049] After processing by an RGB three-color detector, the displayed colors are converted into RGB three-color values. Mineral insulating oil corresponds to the color range of green (0, 255, 0), yellow (255, 255, 0), and orange (255, 15, 0); plant-based insulating oil corresponds to the color range of blue-green (0, 255, 255), yellow-orange (255, 215, 0), and orange-red (255, 69, 0). Therefore, the RGB three-color values ​​corresponding to the displayed colors of the insulating oil are selected as aging characteristic quantities to intuitively reflect the different degrees of aging of the insulating oil. That is, by selecting the displayed color as the characteristic quantity and correlating the displayed color with the degree of aging, and through the direct change in the displayed color accompanying the deepening of the aging of the insulating oil, this new quantitative assessment method for the aging of insulating oil transformers can quickly and intuitively monitor and diagnose the condition of the transformer.

[0050] The following three specific embodiments will be described in detail.

[0051] Specific Implementation Example 1: Karamay 25# mineral insulating oil and ordinary kraft paper were used to conduct an accelerated thermal aging test of oil-paper insulation to simulate the thermal aging process of oil-paper insulation inside the transformer. The above materials were provided by China National Petroleum Corporation and Taizhou Xinyuan Electrical Equipment Co., Ltd., respectively. In step S2, the FLS 1000 stable / transient fluorescence color rendering characteristic test platform and RGB three-color detector were used to observe the insulating oil with different aging degrees. The test light source was an ozone-removing xenon lamp with a wavelength range of 230-870nm and a power of 450W.

[0052] The method for diagnosing transformer aging based on insulating oil color development technology specifically includes the following steps:

[0053] S1: An accelerated thermal aging test was conducted on oil-paper insulation using Karamay 25# mineral insulating oil and ordinary kraft paper to simulate the thermal aging process of oil-paper insulation inside a transformer. 130℃ was selected as the thermal aging temperature for the accelerated thermal aging test. Sampling times were set to 0, 7, 15, 22, 35, and 60 days to obtain oil-paper insulation combinations with different aging degrees. Polycyclic aromatic hydrocarbons in the mineral insulating oil will be degraded into smaller molecular fragments, and the sample after 60 days of thermal aging will lose its fluorescent color development characteristics.

[0054] S2: Colorimetric observations were conducted on Karamay 25# mineral insulating oil with different aging degrees under different wavelength excitation light sources to obtain colorimetric images of insulating oil with different aging degrees under different excitation light sources. A data model corresponding to the aging time of insulating oil and RGB three-color values ​​was established to monitor and diagnose the aging status of transformers.

[0055] The specific steps of step S2 are as follows:

[0056] S21: First, conduct colorimetric observation of Karamay 25# insulating oil with a selected sampling time (aging time) of 0 days, obtain its colorimetric image, and then transmit the data to the data processing system for colorimetric image processing and recording.

[0057] The specific steps of step S21 are as follows:

[0058] S211: At room temperature, turn on the colorimetric characteristic observation platform switch and select ultraviolet excitation light of 330-400nm;

[0059] S212: Clean the liquid sample cell with anhydrous ethanol. After the anhydrous ethanol evaporates, place 5 ml of Karamay 25# mineral insulating oil sample with a sampling time of 0 days into the liquid sample cell.

[0060] S213: When the Karamay 25# insulating oil sample is irradiated with 330-400nm ultraviolet excitation light, it absorbs energy, and the electrons achieve energy level transition, completing the color development process of rapid deactivation and emitting photons.

[0061] S214: The color-developing light of Karamay 25# insulating oil is filtered by the emission monochromator to remove stray light and noise. The light is then focused along the optical path to the photomultiplier tube to obtain an enhanced light signal. The light is then transmitted through the optical fiber to the RGB three-color detector. The RGB three-color detector transmits the collected color-developing light signal to the data processing system, which converts the light signal into an electrical signal for color image processing and recording.

[0062] S22: Place the Karamay 25# insulating oil samples to be tested, which have been obtained at other selected sampling times in step S14 and at different aging times, into the colorimetric characteristic observation platform for colorimetric observation, obtain colorimetric images of Karamay 25# insulating oil at different aging degrees, and transmit the data to the data processing system for colorimetric image processing and recording.

[0063] The specific steps of step S22 are as follows: at room temperature, the liquid sample cell is cleaned with anhydrous ethanol. After the anhydrous ethanol evaporates, 5 ml of Karamay 25# insulating oil samples with different aging degrees are placed in the liquid sample cell. Steps S213 to S214 are repeated to obtain color images of insulating oil with different aging degrees under ultraviolet excitation light.

[0064] S23: Replace the excitation source with blue excitation light of 420-485nm and green excitation light of 490-550nm respectively. The aging time of the mineral insulating oil is selected as 0, 7, 15, 22, 35 and 60 days respectively. Repeat steps S21 to S22 to obtain the color development images of the insulating oil under blue and green excitation light respectively.

[0065] S24: Obtain the RGB three-color values ​​corresponding to the color development colors of insulating oil at different aging levels through color development image processing software, and establish a data model corresponding to the aging time of insulating oil and the RGB three-color values.

[0066] Observational results show that Karamay 25# mineral insulating oil exhibits different color development characteristics under different excitation light. Before aging, when excited by ultraviolet, blue, and green light, the oil's color falls within the blue, green, and yellow ranges, respectively. With increasing aging, electron deactivation leads to a gradual decrease in the intensity of the color generated by photon emission, and the color shows a trend towards longer wavelengths. The deeper the aging, the less pronounced the green component and the more pronounced the red component in the mineral insulating oil's color, until, after reaching a certain aging stage, its color changes to the green, yellow, and orange range under ultraviolet, blue, and green light excitation. The RGB values ​​corresponding to the color development are selected as characteristic quantities, corresponding to the ranges of green (0, 255, 0), yellow (255, 255, 0), and orange (255, 15, 0), respectively. By mapping the RGB three-color values ​​to the degree of aging, and directly observing the changes in the RGB three-color values ​​that accompany the deepening of the aging of the mineral insulating oil, the color of the transformer is selected as a characteristic quantity. This method, which maps the color of the transformer to the degree of aging and directly observes the changes in the color of the transformer as the aging of the insulating oil deepens, serves as a new quantitative assessment method for the aging of insulating oil transformers. It can quickly and intuitively monitor and diagnose the condition of the transformer.

[0067] Specific Implementation Example 2: An accelerated thermal aging test of oil-paper insulation was conducted using FR3 soybean insulating oil and ordinary kraft insulating paper to simulate the thermal aging process of oil-paper insulation inside a transformer. The materials were provided by COOPER Industries, Inc. (USA) and Taizhou Xinyuan Electrical Equipment Co., Ltd., respectively. In step S2, an FLS 1000 stable / transient fluorescence colorimetric characteristic testing platform and an RGB three-color detector were used to observe the insulating oil at different aging levels. The test light source was an ozone-removing xenon lamp with a wavelength range of 230–870 nm and a power of 450 W.

[0068] The method for diagnosing transformer aging based on insulating oil color development technology specifically includes the following steps:

[0069] S1: An accelerated thermal aging test was conducted on the insulating paper and FR3 soybean insulating oil to simulate the thermal aging process of the oil-paper insulation inside the transformer. 130℃ was selected as the thermal aging temperature for the accelerated thermal aging test. The sampling time was set to 0, 7, 15, 22, 35, 60, and 90 days to obtain oil-paper insulation combinations with different aging degrees. The polycyclic aromatic hydrocarbons in the mineral insulating oil will be degraded into smaller molecular fragments, and the sample after 60 days of thermal aging will lose its fluorescent color development characteristics.

[0070] S2: Colorimetric observations are performed on FR3 soybean insulating oil with different aging degrees under excitation light sources of different wavelengths to obtain colorimetric images of FR3 insulating oil with different aging degrees under different excitation light sources. A data model corresponding to the aging time of FR3 insulating oil and RGB three-color values ​​is established to monitor and diagnose the aging status of transformers. The specific steps of step S2 are as follows:

[0071] S21: First, perform colorimetric observation on FR3 soybean insulating oil with a sampling time of 0 days, obtain its colorimetric image, and then transmit the data to the data processing system for colorimetric image processing and recording.

[0072] The specific steps of step S21 are as follows:

[0073] S211: At room temperature, turn on the colorimetric characteristic observation platform switch and select ultraviolet excitation light of 330-400nm;

[0074] S212: Clean the liquid sample cell with anhydrous ethanol. After the anhydrous ethanol evaporates, place 5 mL of FR3 soybean insulating oil sample with a sampling time of 0 days into the liquid sample cell.

[0075] S213:FR3 soybean insulating oil samples absorb energy after being irradiated with 330-400nm ultraviolet excitation light, and electrons achieve energy level transitions, completing the color development process of rapid deactivation and photon emission;

[0076] S214: The color-developing light of FR3 soybean insulating oil is filtered by the emission monochromator to remove stray light and noise. The light is then focused along the optical path to the photomultiplier tube to obtain an enhanced light signal. The light is then transmitted through the optical fiber to the RGB three-color detector. The RGB three-color detector transmits the collected color-developing light signal to the data processing system, which converts the light signal into an electrical signal for color image processing and recording.

[0077] S22: Place the FR3 soybean insulating oil samples to be tested, which have been obtained at other sampling times selected in step S14 and at different aging times, into the colorimetric characteristic observation platform for colorimetric observation, obtain colorimetric images of insulating oil at different aging degrees, and transmit the data to the data processing system for colorimetric image processing and recording.

[0078] The specific steps of step S22 are as follows: at room temperature, the liquid sample cell is cleaned with anhydrous ethanol. After the anhydrous ethanol evaporates, 5 mL of FR3 soybean insulating oil samples with different aging degrees obtained at other selected sampling times are placed in the liquid sample cell. Steps S213 to S214 are repeated to obtain color images of FR3 soybean insulating oil with different aging degrees under ultraviolet excitation light.

[0079] S23: Change the excitation source to blue light of 420-485nm and green light of 490-550nm respectively. Select the aging time of the plant insulating oil as 0, 7, 15, 22, 35, 60 and 90 days. Repeat steps S21 to S22 to obtain the color development images of FR3 soybean insulating oil under blue and green excitation light.

[0080] S24: Obtain the RGB three-color values ​​corresponding to the color development colors of insulating oil at different aging levels through color development image processing software, and establish a data model corresponding to the aging time of FR3 insulating oil and the RGB three-color values.

[0081] The results show that FR3 insulating oil exhibits different colors under different excitation light. Before aging, when excited by ultraviolet, blue, and green light, the oil displays colors belonging to the blue, green, and yellow ranges, respectively. With increasing aging, electron deactivation leads to a gradual decrease in the intensity of the color generated by photon emission, and the color shows a trend towards longer wavelengths. The deeper the aging, the less pronounced the green component and the more pronounced the red component in the FR3 insulating oil's color, until, after reaching a certain aging stage, its color changes to a range of blue-green, yellow-orange, and orange-red under ultraviolet, blue, and green light excitation. The RGB values ​​corresponding to the displayed colors are selected as characteristic quantities, corresponding to the ranges of blue-green (0, 255, 255), yellow-orange (255, 215, 0), and orange-red (255, 69, 0), respectively. By mapping the RGB three-color values ​​to the degree of aging, and directly observing the changes in the RGB three-color values ​​corresponding to the deepening of the aging of FR3 soybean insulating oil, the color of the aging material is selected as a characteristic quantity. By mapping the color of the aging material to the degree of aging, and observing the direct changes in the color of the aging material corresponding to the deepening of the aging of the insulating oil, a new quantitative assessment method for the aging of insulating oil transformers is proposed. This method can quickly and intuitively monitor and diagnose the condition of the transformer.

[0082] Specific Implementation Example 3: An accelerated thermal aging test of oil-paper insulation was conducted using PFAE palm insulating oil and ordinary kraft insulating paper to simulate the thermal aging process of oil-paper insulation inside a transformer. The materials were provided by AE Power Co., Ltd. of Japan and Taizhou Xinyuan Electrical Equipment Co., Ltd., respectively. In step S2, an FLS 1000 stable / transient fluorescence colorimetric characteristic testing platform and an RGB three-color detector were used to observe insulating oils at different aging levels. The test light source was an ozone-removing xenon lamp with a wavelength range of 230–870 nm and a power of 450 W.

[0083] The method for diagnosing transformer aging based on insulating oil color development technology specifically includes the following steps:

[0084] S1: The accelerated thermal aging test of oil-paper insulation with PFAE palm oil was conducted to simulate the thermal aging process of oil-paper insulation inside the transformer. 130℃ was selected as the thermal aging temperature for the accelerated thermal aging test. The sampling time was set to 0, 7, 15, 22, 35, 60, and 90 days to obtain oil-paper insulation combinations with different aging degrees. The polycyclic aromatic hydrocarbons in the mineral insulating oil will be degraded into smaller molecular fragments, and the sample after 60 days of thermal aging will lose its fluorescent color development characteristics.

[0085] S2: Colorimetric observations were performed on PFAE palm insulating oil with different aging degrees under different wavelength excitation light sources to obtain colorimetric images of PFAE palm insulating oil with different aging degrees under different excitation light sources. A data model corresponding to the aging time of PFAE palm insulating oil and the RGB three-color values ​​was established to monitor and diagnose the aging status of transformers.

[0086] The specific steps of step S2 are as follows:

[0087] S21: First, perform colorimetric observation of PFAE palm insulating oil with a selected sampling time of 0 days, obtain its colorimetric image, and then transmit the data to the data processing system for colorimetric image processing and recording.

[0088] The specific steps of step S21 are as follows:

[0089] S211: At room temperature, turn on the colorimetric characteristic observation platform switch and select ultraviolet excitation light of 330-400nm;

[0090] S212: Clean the liquid sample cell with anhydrous ethanol. After the anhydrous ethanol evaporates, place 5 mL of PFAE palm insulating oil sample with a sampling time of 0 days into the liquid sample cell.

[0091] S213: When the PFAE palm insulating oil sample is irradiated with 375nm ultraviolet excitation light, it absorbs energy, and the electrons achieve energy level transitions, completing the color development process of rapid deactivation and emitting photons.

[0092] S214: The color-developing light of PFAE palm insulating oil is filtered by an emitting monochromator to remove stray light and noise. The light is then focused along the optical path to a photomultiplier tube to enhance the light signal. The signal is then transmitted through an optical fiber to an RGB three-color detector. The RGB three-color detector transmits the acquired color-developing light signal to a data processing system, which converts the light signal into an electrical signal for color image processing and recording.

[0093] S22: Place the PFAE palm insulating oil samples with different aging times obtained at other selected sampling times in step S14 into the colorimetric characteristic observation platform for colorimetric observation, obtain colorimetric images of PFAE palm insulating oil with different aging degrees, and transmit the data to the data processing system for colorimetric image processing and recording.

[0094] The specific steps of step S22 are as follows: at room temperature, the liquid sample cell is cleaned with anhydrous ethanol. After the anhydrous ethanol evaporates, 5 mL of PFAE palm insulating oil samples with different aging degrees obtained at other selected sampling times are placed in the liquid sample cell. Steps S213 to S214 are repeated to obtain color images of PFAE palm insulating oil with different aging degrees under ultraviolet excitation light.

[0095] S23: Change the excitation source to blue excitation light of 420-485nm and green excitation light of 490-550nm respectively. Select the aging time of plant insulating oil as 0, 7, 15, 22, 35, 60 and 90 days. Repeat steps S21 to S22 to obtain the color development images of PFAE palm insulating oil under blue excitation light and green excitation light.

[0096] S24: Obtain the RGB three-color values ​​corresponding to the color development colors of PFAE palm insulating oil at different aging levels through color development image processing software, and establish a data model corresponding to the aging time of PFAE palm insulating oil and the RGB three-color values.

[0097] The results showed that PFAE palm insulating oil exhibited different colors under different excitation light. Before aging, when excited by ultraviolet, blue, and green light, the oil displayed colors in the blue, green, and yellow ranges, respectively. With increasing aging, electron deactivation led to a gradual decrease in the intensity of the color generated by photon emission, and the color shifted towards longer wavelengths. The deeper the aging, the less pronounced the green component and the more pronounced the red component in the PFAE palm insulating oil's color, until, after a certain aging stage, the color changed to blue-green, yellow-orange, and orange-red under ultraviolet, blue, and green light excitation. Using the RGB values ​​corresponding to the color as characteristic quantities, the RGB values ​​were mapped to the aging level, corresponding to the ranges of blue-green (0, 255, 255), yellow-orange (255, 215, 0), and orange-red (255, 69, 0), respectively. A novel quantitative aging assessment method is proposed, based on the direct change in RGB values ​​corresponding to the deepening aging of PFAE palm oil insulating oil. This method enables rapid and intuitive monitoring and diagnosis of transformer condition. Therefore, color development is selected as a characteristic quantity, and the color is correlated with the degree of aging. By observing the direct change in color development accompanying the deepening of insulating oil aging, this method serves as a new quantitative assessment method for the aging of insulating oil transformers, enabling rapid and intuitive monitoring and diagnosis of transformer condition.

[0098] The wavelengths of ultraviolet excitation light, blue light, and green light in the specific embodiments 1 to 3 described above can all be changed within the wavelength range.

[0099] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention, such as changes in wavelength range, should be included within the protection scope of the present invention.

Claims

1. A method for diagnosing transformer aging based on insulating oil colorimetric technology, characterized in that, Specifically, the following steps are included: S1: The accelerated thermal aging test of oil-paper insulation was carried out using transformer insulating oil and ordinary kraft paper to simulate the thermal aging process of oil-paper insulation inside the transformer. Samples were taken at different aging times to obtain oil-paper insulation combinations with different aging degrees. S2: Colorimetric observations are performed on insulating oils with different aging degrees under excitation light sources of different wavelengths to obtain colorimetric images of insulating oils with different aging degrees under different excitation light sources. A data model is established to correspond the aging time of insulating oil with RGB three-color values, thereby monitoring and diagnosing the aging status of transformers. The specific steps of step S2 are as follows: S21: First, perform colorimetric observation on the insulating oil obtained at the selected sampling time of 0, obtain its colorimetric image, and then transmit the data to the data processing system for colorimetric image processing and recording. S22: Place the insulating oils with different aging degrees obtained at other sampling times selected in step S1 into the colorimetric characteristic observation platform for colorimetric observation, obtain colorimetric images of insulating oils with different aging degrees, and transmit the data to the data processing system for colorimetric image processing and recording. S23: Change the excitation light source and repeat steps S21~S22 to obtain color images of insulating oil with different aging degrees under different excitation light sources; S24: Obtain the RGB three-color values ​​corresponding to the color development colors of insulating oil at different aging levels through color development image software, and establish a data model corresponding to the aging time of insulating oil and the RGB three-color values. The specific steps of step S21 are as follows: S211: At room temperature, turn on the colorimetric characteristic observation platform and select ultraviolet excitation light with a wavelength range of 330~400nm; S212: Clean the liquid sample cell with anhydrous ethanol. After the anhydrous ethanol evaporates, place 5 mL of the selected insulating oil sample with a sampling time of 0 into the liquid sample cell. S213: Excitation light of a specific wavelength is transmitted through an excitation monochromator and irradiates the insulating oil. After being irradiated by light, the insulating oil absorbs energy, and electrons achieve energy level transitions, completing the color development process of deactivation and emitting photons. S214: The color-developing light of the insulating oil is filtered by the emission monochromator to remove stray light and noise. The light is then focused along the optical path to the photomultiplier tube to obtain an enhanced light signal. The light is then transmitted through the optical fiber to the RGB three-color detector. The RGB three-color detector transmits the collected color-developing light signal to the data processing system, which converts the light signal into an electrical signal for color image processing and recording.

2. The method for diagnosing transformer aging based on insulating oil color development technology according to claim 1, characterized in that, The specific steps of step S1 are as follows: select 120~130℃ as the thermal aging test temperature; set the sampling time for vegetable insulating oil to 0~90 days and the sampling time for mineral insulating oil to 0~60 days.

3. The method for diagnosing transformer aging based on insulating oil color development technology according to claim 1, characterized in that, The specific steps of step S22 are as follows: At room temperature, the liquid sample cell was cleaned with anhydrous ethanol. After the anhydrous ethanol evaporated, 5 mL of insulating oil with different aging degrees was placed in the liquid sample cell. Steps S213 to S214 were repeated to obtain color images of insulating oil with different aging degrees under ultraviolet excitation light.

4. The method for diagnosing transformer aging based on insulating oil color development technology according to claim 3, characterized in that, The specific steps of step S23 are as follows: replace the excitation light source with blue excitation light with a wavelength range of 420~485nm and green excitation light with a wavelength range of 490~550nm respectively, repeat steps S21~S22, and obtain color images of insulating oil with different aging degrees under blue excitation light and green excitation light respectively.

5. The method for diagnosing transformer aging based on insulating oil color development technology according to claim 2, characterized in that, In step S1, 130℃ is selected as the thermal aging test temperature; the sampling time for vegetable insulating oil is set to 0, 7, 15, 22, 35, 60 and 90 days, and the sampling time for mineral insulating oil is set to 0, 7, 15, 22, 35 and 60 days.

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