Method and system for determining explosion risk of transformer oil under action of electric arc in oxygen-poor environment

Abstract

This invention discloses a method and system for determining the explosion risk of transformer oil under the influence of an electric arc in an oxygen-deficient environment. The method includes: collecting free mixed gas generated in the oxygen-deficient space inside a transformer or oil-filled equipment under the influence of an electric arc or thermal fault; directly determining the composition and volume fraction of each component of the mixed gas using a Fourier transform infrared spectroscopy analyzer, wherein the components include at least methane, ethane, ethylene, and acetylene; calculating the lower and upper explosive limits of the mixed gas using the Richardley formula based on the volume fraction of each component; calculating the characteristic gas ratios C2H2 / C2H4 and C2H4 / C2H6, and determining the fault type according to a preset judgment logic based on the changing trend of the acetylene volume fraction; and comprehensively assessing the explosion risk level of the equipment by combining the explosion limits and the fault type. This invention replaces traditional chromatography with infrared spectroscopy analysis, eliminating the need for degassing and providing faster detection speed; it corrects the fault judgment logic using experimental data, compensating for the shortcomings of traditional guidelines under specific operating conditions; and it introduces explosion limit calculation to directly quantify the ease with which the gas can be ignited, providing more intuitive data support for explosion-proof safety.

Description

Technical Field

[0001] This invention relates to the field of power equipment safety protection technology, and more specifically, to a method and system for determining the risk of transformer oil explosion under the action of electric arc in an oxygen-deficient environment. Background Technology

[0002] Transformer bushings, instrument transformers, and other oil-limited equipment are typically housed in a completely sealed, oxygen-deficient environment. When internal faults occur (such as partial discharge, arcing, or overheating), the insulating oil decomposes, producing hydrogen and various hydrocarbon gases (such as methane, ethane, ethylene, and acetylene). These gases accumulate at the top of the equipment or at defects, forming bubbles that can easily ignite or explode upon contact with air or under excessive internal pressure.

[0003] Current fault diagnosis mainly relies on the three-ratio method in the "Guideline for Analysis and Judgment of Dissolved Gases in Transformer Oil" (GB / T 7252-2001), which analyzes the gases dissolved in the oil using gas chromatography. However, the existing technology has the following shortcomings: 1. Long detection time: Gas chromatography analysis requires cumbersome steps such as degassing, which makes it difficult to meet the needs of rapid real-time monitoring of sudden arc faults.

[0004] II. Determining the blind zone: The traditional three-ratio method has certain limitations in distinguishing the coupling relationship between arc energy, insulating oil aging degree and overheating fault.

[0005] Third, lack of explosion limit assessment: Existing standards focus more on the judgment of fault type and lack direct quantitative assessment of the combustion explosion limit (LEL / UEL) of the gas mixture, making it difficult to directly characterize the explosion risk level.

[0006] Furthermore, existing research and standards do not adequately address the changes in fire hazard caused by aging of transformer insulating oil during actual operation. Insulating oil undergoes thermo-oxidative aging under long-term high temperatures, electric arcs, and interactions with insulating materials, leading to an increase in key parameters such as dielectric loss factor and acid value, and the production of oxygen-containing small molecules such as alcohols, aldehydes, ketones, and acids. This aging process not only affects the oil's insulating properties but also significantly alters its gas-generating composition and characteristics under fault conditions (especially under electric arcs), thereby affecting the explosion limits of mixed flammable gases. However, the current standard GB2536-2011 primarily regulates unused new oil, lacking systematic research on the gas-generating characteristics, explosion hazards, and ignition characteristics of aged oil under real fault scenarios.

[0007] Meanwhile, existing fault gas studies, particularly those concerning the oxygen-deficient environment inside oil-poor equipment like transformer bushings, are mostly conducted in air, which differs from the actual conditions of gas generation and initial accumulation within the equipment. In an oxygen-deficient environment, the electric arc acting on the insulating oil primarily produces a flammable hydrocarbon mixture. These gases accumulate inside the equipment, and their explosion hazard depends on their specific composition. Traditional dissolved gas analysis (DGA) cannot directly and quickly assess the immediate explosion risk of this free gas mixture. Summary of the Invention

[0008] This invention aims to address the shortcomings of existing technologies by providing a method and system for determining the explosion risk of transformer oil under the influence of electric arc in an oxygen-deficient environment. This method combines gas infrared spectroscopy analysis with an improved three-ratio method, enabling rapid assessment of the explosion hazard of gas mixtures and accurate diagnosis of fault evolution trends.

[0009] The technical solution provided by this invention is, as one aspect of this invention, a method for determining the risk of transformer oil explosion under the action of electric arc in an oxygen-deficient environment, which includes the following steps: Step S1: Collect the free mixed gas generated in the oxygen-deficient space inside the transformer or oil-filled equipment under the action of electric arc or thermal fault; Step S2: The composition and volume fraction of each component of the mixed gas are directly determined using a Fourier transform infrared spectrometer. The components include at least methane, ethane, ethylene, and acetylene. Step S3: Calculate the lower and upper explosive limits of the gas mixture using the Richardley formula based on the volume fraction of each component. Step S4: Calculate the characteristic gas ratios C2H2 / C2H4 and C2H4 / C2H6, and determine the fault type according to the preset judgment logic, based on the changing trend of the volume fraction of acetylene. Step S5: Combine the explosion limits calculated in step S3 with the fault type determined in step S4 to assess the explosion risk level of the equipment.

[0010] Preferably, the preset determination logic in step S4 includes: When the C2H2 / C2H4 ratio is observed to show a downward trend, it is determined that the aging of the transformer insulating oil has intensified. When a significant increase in the proportion of acetylene and a simultaneous significant increase in the C2H4 / C2H6 ratio are detected, it is determined that the internal arc energy of the equipment is enhanced. When the acetylene content is observed to fluctuate or increase slowly while the C2H4 / C2H6 ratio increases sharply, it is determined that an overheating fault has occurred inside the equipment.

[0011] Preferably, the preset judgment logic is established based on experimental data of arc gas generation characteristics in oxygen-deficient environments under different insulating oil aging degrees, different arc energies, and different oil temperatures; wherein: The degree of aging of insulating oil is characterized by dielectric loss factor and acid value; The increase in arc energy was positively correlated with the simultaneous increase in the proportion of acetylene and the C2H4 / C2H6 ratio. The increase in oil temperature is positively correlated with the sharp increase in the C2H4 / C2H6 ratio, while it is weakly correlated or non-monotonic with the increase in the proportion of acetylene.

[0012] Preferably, step S3 further includes: The calculated lower explosive limit is compared with a preset threshold. When the lower explosive limit is lower than the minimum threshold, the risk of the gas mixture being ignited is determined to be increased. The difference between the upper and lower explosion limits is calculated as the explosion concentration interval. When the explosion concentration interval increases, the explosion risk is considered to have increased.

[0013] Preferably, the oxygen-deficient space in step S1 includes the enclosed space inside the transformer bushing, the enclosed space inside the current transformer, or the enclosed space inside the transformer oil tank; the mixed gas is a free combustible hydrocarbon mixture generated by an electric arc or thermal fault acting on the transformer insulating oil in an oxygen-deficient environment, including at least methane, ethane, ethylene, and acetylene, and also including one or more of methanol, formaldehyde, acetaldehyde, propane, and propylene.

[0014] Accordingly, as another aspect of the present invention, a system for determining the risk of transformer oil explosion under the action of electric arc in an oxygen-deficient environment is also provided, comprising: The gas acquisition module is used to collect free mixed gas generated in the oxygen-deficient space inside transformers or oil-filled equipment under the action of electric arc or thermal fault. The gas analysis module includes a Fourier transform infrared spectrometer for directly determining the composition and volume fraction of the mixed gas, wherein the components include at least methane, ethane, ethylene, and acetylene; The explosion limit calculation module is used to calculate the lower explosion limit and upper explosion limit of the gas mixture based on the volume fraction of each component using the Richardley formula. The fault type determination module is used to calculate the characteristic gas ratios C2H2 / C2H4 and C2H4 / C2H6, and, in conjunction with the changing trend of the volume fraction of acetylene, determine the fault type according to the preset determination logic. The risk assessment module is used to assess the explosion risk level of the equipment by combining the explosion limit output by the explosion limit calculation module and the fault type determined by the fault type determination module.

[0015] Preferably, the preset determination logic in the fault type determination module includes: The oil aging judgment unit is used to determine that the transformer insulating oil is aging more rapidly when the C2H2 / C2H4 ratio shows a downward trend. The arc energy determination unit is used to determine that the internal arc energy of the equipment is enhanced when a significant increase in the proportion of acetylene and a simultaneous significant increase in the C2H4 / C2H6 ratio are detected. The overheating fault determination unit is used to determine that an overheating fault has occurred inside the equipment when the acetylene content fluctuates or increases slowly while the C2H4 / C2H6 ratio increases sharply.

[0016] Preferably, the preset judgment logic of the fault type determination module is established based on experimental data of arc gas generation characteristics in oxygen-deficient environments under different insulating oil aging degrees, different arc energies, and different oil temperatures; wherein: The degree of aging of insulating oil is characterized by dielectric loss factor and acid value; The increase in arc energy was positively correlated with the simultaneous increase in the proportion of acetylene and the C2H4 / C2H6 ratio. The increase in oil temperature is positively correlated with the sharp increase in the C2H4 / C2H6 ratio, while it is weakly correlated or non-monotonic with the increase in the proportion of acetylene.

[0017] Preferably, the explosion limit calculation module further includes: The lower explosive limit comparison unit is used to compare the calculated lower explosive limit with a preset threshold. When the lower explosive limit is lower than the minimum threshold, it is determined that the risk of the gas mixture being ignited has increased. The explosion concentration interval calculation unit is used to calculate the difference between the upper and lower explosion limits as the explosion concentration interval. When the explosion concentration interval increases, the explosion risk is determined to be higher.

[0018] Preferably, the oxygen-deficient space collected by the gas collection module includes the enclosed space inside the transformer bushing, the enclosed space inside the current transformer, or the enclosed space inside the transformer oil tank; the mixed gas is a free combustible hydrocarbon mixture generated by an electric arc or thermal fault acting on the transformer insulating oil in an oxygen-deficient environment, including at least methane, ethane, ethylene, and acetylene, and also including one or more of methanol, formaldehyde, acetaldehyde, propane, and propylene.

[0019] Implementing the embodiments of the present invention has the following beneficial effects: This invention provides a method and system for determining the risk of transformer oil explosion under electric arc in an oxygen-deficient environment. By utilizing infrared spectroscopy analysis instead of traditional chromatography, it eliminates the need for degassing, offers rapid detection, and is suitable for quick identification. In the embodiments of the present invention, the fault judgment logic was corrected by experimental data, and the correspondence between C2H2 / C2H4 and oil aging, and between C2H4 / C2H6 and arc energy and overheating was clarified, making up for the shortcomings of traditional guidelines under specific working conditions. In the embodiments of the present invention, explosion limit calculation is introduced, which directly quantifies the ease with which the gas can be ignited, providing more intuitive data support for explosion-proof safety.

[0020] The method provided by the embodiments of the present invention is particularly suitable for fault monitoring in oxygen-deficient environments inside oil-poor equipment such as transformer bushings and current transformers. By directly analyzing the free gas accumulated inside the equipment, it can more accurately reflect the gas composition and explosion risk generated immediately by the fault, avoiding the lag and equilibrium process effects that may exist in dissolved gas analysis.

[0021] In the embodiments of the present invention, by establishing the correlation between gas composition ratio, explosion limit and aging state of insulating oil (dielectric loss factor, acid value), fault energy (arc energy), and fault nature (overheating), an upgrade from "fault type judgment" to "quantitative assessment of explosion risk" is achieved, providing a technical basis for formulating graded early warning and precise operation and maintenance strategies. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention. Figure 1 This is a schematic diagram of the main flow of an embodiment of a method for determining the risk of transformer oil explosion under the action of electric arc in an oxygen-deficient environment provided by the present invention. Figure 2 A more detailed flowchart of one embodiment of the method provided by the present invention; Figure 3 This is a logic diagram for determining the fault type based on the gas ratio in the method provided by the present invention; Figure 4 This invention provides a schematic diagram illustrating the effect of arc energy on the proportion of C2H2 and the C2H4 / C2H6 ratio in an example. Figure 5 This invention provides a schematic diagram illustrating the effect of insulating oil aging on the C2H2 / C2H4 ratio in an example. Figure 6 To illustrate the present invention, an example is provided showing the effect of oil temperature on the C2H4 / C2H6 ratio and the proportion of C2H2. Figure 7This is a schematic diagram of an embodiment of the system for determining the risk of transformer oil explosion under the action of electric arc in an oxygen-deficient environment, provided by the present invention. Figure 8 for Figure 7 Schematic diagram of the explosion limit calculation module; Figure 9 for Figure 7 A schematic diagram of the fault type determination module. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0024] like Figure 1 The diagram shows the main flow of an embodiment of a method for determining the risk of transformer oil explosion under the action of an electric arc in an oxygen-deficient environment, provided by the present invention; combined with... Figures 2 to 6 As shown, in this embodiment, the method includes the following steps: Step S1: Collect the free mixed gas generated in the oxygen-deficient space inside the transformer or oil-filled equipment under the action of electric arc or thermal fault; The oxygen-deficient space mentioned in step S1 includes the enclosed space inside the transformer bushing, the enclosed space inside the current transformer, or the enclosed space inside the transformer oil tank; the mixed gas is a free combustible hydrocarbon mixture generated by the electric arc or thermal fault acting on the transformer insulating oil in an oxygen-deficient environment, including at least methane, ethane, ethylene, and acetylene, and also including one or more of methanol, formaldehyde, acetaldehyde, propane, and propylene.

[0025] Step S2: The composition and volume fraction of each component of the mixed gas are directly determined using a Fourier transform infrared spectrometer. The components include at least methane, ethane, ethylene, and acetylene. Step S3: Calculate the lower and upper explosive limits of the gas mixture using the Richardley formula based on the volume fraction of each component. Step S3 further includes: The calculated lower explosive limit is compared with a preset threshold. When the lower explosive limit is lower than the minimum threshold, the risk of the gas mixture being ignited is determined to be increased. The difference between the upper and lower explosion limits is calculated as the explosion concentration interval. When the explosion concentration interval increases, the explosion risk is considered to have increased.

[0026] Step S4: Calculate the characteristic gas ratios C2H2 / C2H4 and C2H4 / C2H6, and determine the fault type according to the preset judgment logic, based on the changing trend of the volume fraction of acetylene. The preset judgment logic in step S4 is established based on experimental data on the gas generation characteristics of arcs in oxygen-deficient environments under different insulating oil aging degrees, different arc energies, and different oil temperatures; wherein: The degree of aging of insulating oil is characterized by dielectric loss factor and acid value; The increase in arc energy was positively correlated with the simultaneous increase in the proportion of acetylene and the C2H4 / C2H6 ratio. The increase in oil temperature is positively correlated with the sharp increase in the C2H4 / C2H6 ratio, while it is weakly correlated or non-monotonic with the increase in the proportion of acetylene.

[0027] Specifically, the preset determination logic includes: When the C2H2 / C2H4 ratio is observed to show a downward trend, it is determined that the aging of the transformer insulating oil has intensified. When a significant increase in the proportion of acetylene and a simultaneous significant increase in the C2H4 / C2H6 ratio are detected, it is determined that the internal arc energy of the equipment is enhanced. When the acetylene content is observed to fluctuate or increase slowly while the C2H4 / C2H6 ratio increases sharply, it is determined that an overheating fault has occurred inside the equipment.

[0028] Step S5: Combine the explosion limits calculated in step S3 with the fault type determined in step S4 to assess the explosion risk level of the equipment.

[0029] To further understand the method provided by this invention, the following will be combined with Figures 2 to 6 To provide a more detailed explanation.

[0030] In a specific example, the present invention provides a method for determining the risk of transformer oil explosion under the action of an electric arc in an oxygen-deficient environment, comprising the following steps: Step 1: Gas Collection and Composition Analysis. Free gases generated by electric arcs or thermal faults are collected in the oxygen-deficient space of transformers or oil-filled equipment (such as the gas collection area at the top of the bushing). The collected mixed gas is analyzed using a Fourier Transform Infrared Spectrometer (FTIR) to determine the volume fraction of each component. The component gases include at least: methane (CH4), ethane (C2H6), ethylene (C2H4), and acetylene (C2H2). Preferably, the component gases also include one or more of methanol, formaldehyde, acetaldehyde, propane, and propylene to more comprehensively reflect the gas generation characteristics under insulating oil aging and different fault conditions. FTIR analysis eliminates the need for complex sample pretreatment (such as degassing), allowing for rapid, simultaneous multi-component determination of the collected free gases, significantly improving detection efficiency and making it suitable for rapid on-site diagnosis.

[0031] Step 2: Based on the volume fraction of each component gas measured in Step 1, calculate the lower explosive limit (LEL) and upper explosive limit (UEL) of the gas mixture using the Le Chatelier formula to quantify the explosion risk range.

[0032] The formula for calculating the lower explosive limit is:

[0033] The formula for calculating the upper limit of explosion is:

[0034] in, The lower explosive limit (%) of the gas mixture. The upper explosive limit (%) of the gas mixture. The first in the mixed gas Volume fraction (%) of each component. For the first The lower explosive limit (%) of each component when it exists alone. For the first The upper explosive limit (%) of a single component. This represents the number of combustible components in the gas mixture.

[0035] If the calculated lower explosion limit is lower than the preset threshold (e.g., lower than 2.8%), or the explosion concentration interval... An increase in the concentration indicates a higher risk of explosion. When the lower explosion limit is below the minimum threshold, the gas is considered highly flammable, indicating a high risk level. A larger concentration range indicates a wider range of flammable gases that can be ignited in air, and thus a higher level of danger. By calculating the explosion limits, the gas composition data is directly converted into intuitive quantitative indicators of explosion risk, overcoming the shortcomings of traditional methods that only qualitatively determine the type of fault.

[0036] Step 3: Determine the fault type based on the improved three-ratio method. First, calculate the characteristic gas ratios: R1 = C2H2 / C2H4 and R2 = C2H4 / C2H6. Then, combine the changes in the composition ratio of acetylene (C2H2) to determine the fault type and evolution trend according to the following logic: 1. Insulating oil aging judgment: If the C2H2 / C2H4 ratio is observed to show a downward trend and the C2H4 / C2H6 ratio shows a systematic shift, it is judged that the aging degree of the transformer insulating oil has intensified and the oil quality has declined.

[0037] 2. Judgment of enhanced arc energy: If a significant increase in the proportion of acetylene is detected, and the C2H4 / C2H6 ratio increases significantly at the same time, it is determined that the arc energy is enhanced, and it is determined that a larger arc fault has occurred inside the oil-filled equipment.

[0038] 3. Overheating fault determination: If the proportion of acetylene (C2H2) is detected to fluctuate or increase slowly, but the ratio of R2=C2H4 / C2H6 increases, it is determined that an overheating fault has occurred inside the equipment.

[0039] The above judgment logic is based on a large amount of experimental data summarizing the gas generation characteristics of transformer insulating oil under oxygen-deficient arc conditions, including different aging degrees (characterized by dielectric loss factor and acid value), different arc energies, and different oil temperatures. Experiments have shown that: 1. As insulating oil ages more rapidly (resulting in an increased dielectric loss factor), the generation of ethylene (C2H4) in the generated gases intensifies, while the generation of acetylene (C2H2) is relatively suppressed at certain stages. This leads to a decreasing trend in the C2H2 / C2H4 ratio, while the change in the C2H4 / C2H6 ratio is coupled with the aging stage and oil temperature / arc energy. However, overall, aging causes a systematic shift in the characteristic gas ratio relationship.

[0040] 2. Increased arc energy significantly promotes the formation of acetylene (C2H2) (because the formation of its C≡C bond requires high energy), while also promoting the formation of ethylene (C2H4) and inhibiting ethane (C2H6), resulting in a simultaneous and significant increase in the proportion of acetylene and the C2H4 / C2H6 ratio.

[0041] 3. Increased oil temperature primarily promotes the breaking of C-C bonds and their conversion to C=C bonds, significantly increasing the production of ethylene (C2H4) and decreasing ethane (C2H6), leading to a sharp increase in the C2H4 / C2H6 ratio and consequently overheating failure. However, the promoting effect of simple overheating (without a high-energy arc) on acetylene formation is far less than that of a high-energy arc. Therefore, the proportion of acetylene may only fluctuate slightly or increase slowly, rather than rising sharply in sync with the C2H4 / C2H6 ratio.

[0042] For a detailed logic diagram of fault type determination based on gas ratio, please refer to [link / reference]. Figure 3 As shown.

[0043] Step 4: Conduct a risk assessment by combining the explosion limit data from Step 2 with the fault type from Step 3. When the lower explosion limit of the mixed gas decreases and it is determined to be a high-energy electric arc fault, issue a high-level alarm.

[0044] The invention will be further explained below with reference to specific experimental data: Example 1: The gas generated by the electric arc in transformer oil under an oxygen-deficient environment is collected in the simulation device.

[0045] 1. Gas Analysis: Infrared analysis revealed that the gas contained high concentrations of acetylene and ethylene.

[0046] 2. Explosion limit calculation: Substituting the lower explosion limit of each component, the calculated lower explosion limit of the gas mixture is reduced to below 2.81%, and the upper explosion limit is increased to above 33%, indicating that the gas is extremely easy to ignite with a small amount of energy.

[0047] 3. Fault Diagnosis: Calculations revealed a significant increase in the proportion of C2H2, while the C2H4 / C2H6 ratio also increased significantly.

[0048] According to logic 2 in step 3 of this invention, it is determined that the arc energy inside the device is continuously increasing (corresponding to the process of arc energy increasing from 6J to 13.8J in the experiment), and the power supply must be cut off immediately to prevent an explosion.

[0049] Experimental Background Reference: This embodiment controls the oil temperature at 20℃ and conducts gas generation experiments by applying electric arcs of different energies (6J, ​​9.6J, 13.8J) to transformer insulating oil aged for 0 hours. When the arc energy increases from 9.6J to 13.8J, the measured acetylene (C2H2) content increases sharply from 49.90% to 69.65%, while the C2H4 / C2H6 ratio increases from 1.81 to 5.53. The calculated lower explosive limit of the gas mixture generated by this 13.8J arc is as low as 2.68%, while the upper explosive limit is as high as 39.98%, with an explosive concentration range of 37.30%. This indicates that if air leaks into the equipment at this level, the gas mixture is highly ignitable across a wide concentration range, posing an extremely high explosion risk. This example verifies the effectiveness of the method of this invention in assessing the sensitivity and risk quantification of high-energy arc faults. For a schematic diagram illustrating the influence of arc energy on the C2H2 content and the C2H4 / C2H6 ratio in this example, please refer to [link to relevant documentation]. Figure 4 As shown.

[0050] Example 2: 1. Fault diagnosis: Monitoring revealed that the C2H2 / C2H4 ratio showed a decreasing trend over time.

[0051] 2. Judgment: Based on logic 1 in step 3 of this invention, it is determined that the aging degree of the transformer insulating oil is accelerating and the dielectric loss factor is increasing, so it is necessary to arrange oil sample testing or oil replacement.

[0052] Experimental Background Reference: This embodiment simulates the aging process of insulating oil over operating time. Under the same arc energy (9.6J) and oil temperature (20℃), comparing oil samples aged 0h and 288h, the C2H2 / C2H4 ratio in the generated gas decreased from 9.34 to 3.13 (the description of "gradually increasing" in this example may indicate a trend comparing different aging stages; the specific trend needs to be based on actual monitoring data. The core of Logic 1 is that the ratio shows a significant changing trend related to oil quality decline). Simultaneously, the lower explosive limit of the gas produced by the 288h aged oil sample was 2.87%, slightly higher than that of new oil, but its gas production rate was significantly accelerated, and the oil quality decline itself after long-term aging is an important risk factor. By monitoring the changing trend of this ratio, the trend of oil quality deterioration can be predicted earlier between traditional oil aging test cycles. In this example, a schematic diagram of the effect of insulating oil aging on the C2H2 / C2H4 ratio can be found [link to schematic diagram]. Figure 5 As shown.

[0053] Example 3: 1. Fault diagnosis: Monitoring revealed that the C2H4 / C2H6 ratio increased rapidly, but the proportion of C2H2 did not increase monotonically and significantly, but instead fluctuated.

[0054] 2. Judgment: Based on logic 3 in step 3 of this invention, it is determined that the main fault inside the equipment is overheating, rather than a simple high-energy arc discharge (corresponding to the effect of oil temperature rise on gas production characteristics in the experiment).

[0055] Experimental Background Reference: This embodiment controls the arc energy at 9.6 J to conduct gas generation experiments on transformer insulating oil aged for 0 hours at different oil temperatures (20℃, 45℃, 90℃). When the oil temperature rises from 20℃ to 90℃, the C2H4 / C2H6 ratio increases sharply from 1.81 to 23.95, while the proportion of acetylene (C2H2) changes from 49.90% to 40.80% (fluctuating, not a monotonically large increase). The calculated lower explosive limit of the gas mixture generated at 90℃ is 2.84%, and the upper explosive limit is 29.17%. This example shows that although a simple overheating fault (increased oil temperature) will significantly change the C2H4 / C2H6 ratio and significantly increase the explosive concentration interval (increased risk), its gas composition characteristics are different from those of a high-energy arc fault (the proportion of acetylene does not increase synchronously). By distinguishing this characteristic, the method of this invention can more accurately identify overheating faults. In this example, the effect of oil temperature on the C2H4 / C2H6 ratio and the proportion of C2H2 can be found in the graph. Figure 6 As shown.

[0056] like Figure 7 The diagram shows a schematic representation of an embodiment of a system for determining the risk of transformer oil explosion under an electric arc in an oxygen-deficient environment, provided by the present invention; in conjunction with... Figure 7As shown, in this embodiment, the transformer oil explosion risk determination system 1 under the action of an electric arc in an oxygen-deficient environment includes at least: Gas acquisition module 10 is used to collect free mixed gas generated in the oxygen-deficient space inside a transformer or oil-filled equipment under the action of electric arc or thermal fault; The gas analysis module 11 includes a Fourier transform infrared spectrometer for directly determining the composition and volume fraction of each component of the mixed gas, wherein the components include at least methane, ethane, ethylene and acetylene; The explosion limit calculation module 12 is used to calculate the lower explosion limit and upper explosion limit of the gas mixture based on the volume fraction of each component using the Richardley formula; The fault type determination module 13 is used to calculate the characteristic gas ratios C2H2 / C2H4 and C2H4 / C2H6, and, in conjunction with the changing trend of the volume fraction of acetylene, determine the fault type according to the preset determination logic. Risk assessment module 14 is used to assess the explosion risk level of the equipment by combining the explosion limit output by the explosion limit calculation module and the fault type determined by the fault type determination module.

[0057] The oxygen-deficient space collected by the gas acquisition module 10 includes the enclosed space inside the transformer bushing, the enclosed space inside the current transformer, or the enclosed space inside the transformer oil tank; the mixed gas is a free combustible hydrocarbon mixture generated by electric arc or thermal fault acting on the transformer insulating oil in an oxygen-deficient environment, including at least methane, ethane, ethylene, and acetylene, and also including one or more of methanol, formaldehyde, acetaldehyde, propane, and propylene.

[0058] like Figure 8 As shown, in one example, the explosion limit calculation module 12 further includes: The lower explosion limit comparison unit 120 is used to compare the calculated lower explosion limit with a preset threshold. When the lower explosion limit is lower than the minimum threshold, it is determined that the risk of the mixed gas being ignited has increased. The explosion concentration interval calculation unit 121 is used to calculate the difference between the upper and lower explosion limits as the explosion concentration interval. When the explosion concentration interval increases, the explosion risk is determined to be higher.

[0059] like Figure 9 As shown, in one example, the fault type determination module 13 further includes: The oil aging judgment unit 130 is used to determine that the transformer insulating oil aging degree has intensified when the C2H2 / C2H4 ratio shows a downward trend. The arc energy determination unit 131 is used to determine that the arc energy inside the equipment is enhanced when a significant increase in the proportion of acetylene and a simultaneous significant increase in the C2H4 / C2H6 ratio are detected. The overheating fault determination unit 132 is used to determine that an overheating fault has occurred inside the equipment when the acetylene ratio fluctuates or increases slowly and the C2H4 / C2H6 ratio increases sharply.

[0060] It is understood that the preset judgment logic of the fault type determination module 13 is established based on experimental data of arc gas generation characteristics in oxygen-deficient environments under different insulating oil aging degrees, different arc energies, and different oil temperatures; wherein: The degree of aging of insulating oil is characterized by dielectric loss factor and acid value; The increase in arc energy was positively correlated with the simultaneous increase in the proportion of acetylene and the C2H4 / C2H6 ratio. The increase in oil temperature is positively correlated with the sharp increase in the C2H4 / C2H6 ratio, while it is weakly correlated or non-monotonic with the increase in the proportion of acetylene.

[0061] For more details, please refer to and combine with the above. Figures 1 to 6 The description will not be repeated here.

[0062] Implementing the embodiments of the present invention has the following beneficial effects: This invention provides a method and system for determining the risk of transformer oil explosion under electric arc in an oxygen-deficient environment. By utilizing infrared spectroscopy analysis instead of traditional chromatography, it eliminates the need for degassing, offers rapid detection, and is suitable for quick identification. In the embodiments of the present invention, the fault judgment logic was corrected by experimental data, and the correspondence between C2H2 / C2H4 and oil aging, and between C2H4 / C2H6 and arc energy and overheating was clarified, making up for the shortcomings of traditional guidelines under specific working conditions. In the embodiments of the present invention, explosion limit calculation is introduced, which directly quantifies the ease with which the gas can be ignited, providing more intuitive data support for explosion-proof safety.

[0063] The method provided by the embodiments of the present invention is particularly suitable for fault monitoring in oxygen-deficient environments inside oil-poor equipment such as transformer bushings and current transformers. By directly analyzing the free gas accumulated inside the equipment, it can more accurately reflect the gas composition and explosion risk generated immediately by the fault, avoiding the lag and equilibrium process effects that may exist in dissolved gas analysis.

[0064] In the embodiments of the present invention, by establishing the correlation between gas composition ratio, explosion limit and aging state of insulating oil (dielectric loss factor, acid value), fault energy (arc energy), and fault nature (overheating), an upgrade from "fault type judgment" to "quantitative assessment of explosion risk" is achieved, providing a technical basis for formulating graded early warning and precise operation and maintenance strategies.

[0065] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 Units that specify functions within one or more boxes.

[0066] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for determining the risk of transformer oil explosion under electric arc in an oxygen-deficient environment, characterized in that, Includes the following steps: Step S1: Collect the free mixed gas generated in the oxygen-deficient space inside the transformer or oil-filled equipment under the action of electric arc or thermal fault; Step S2: The composition and volume fraction of each component of the mixed gas are directly determined using a Fourier transform infrared spectrometer. The components include at least methane, ethane, ethylene, and acetylene. Step S3: Calculate the lower and upper explosive limits of the gas mixture using the Richardley formula based on the volume fraction of each component. Step S4: Calculate the characteristic gas ratios C2H2 / C2H4 and C2H4 / C2H6, and determine the fault type according to the preset judgment logic, based on the changing trend of the volume fraction of acetylene. Step S5: Combine the explosion limits calculated in step S3 with the fault type determined in step S4 to assess the explosion risk level of the equipment.

2. The method according to claim 1, characterized in that, The preset determination logic in step S4 includes: When the C2H2 / C2H4 ratio is observed to show a downward trend, it is determined that the aging of the transformer insulating oil has intensified. When a significant increase in the proportion of acetylene and a simultaneous significant increase in the C2H4 / C2H6 ratio are detected, it is determined that the internal arc energy of the equipment is enhanced. When the acetylene content is observed to fluctuate or increase slowly while the C2H4 / C2H6 ratio increases sharply, it is determined that an overheating fault has occurred inside the equipment.

3. The method according to claim 2, characterized in that, The preset judgment logic is established based on experimental data of arc gas generation characteristics in oxygen-deficient environments under different insulating oil aging degrees, different arc energies, and different oil temperatures; wherein: The degree of aging of insulating oil is characterized by dielectric loss factor and acid value; The increase in arc energy was positively correlated with the simultaneous increase in the proportion of acetylene and the C2H4 / C2H6 ratio. The increase in oil temperature is positively correlated with the sharp increase in the C2H4 / C2H6 ratio, while it is weakly correlated or non-monotonic with the increase in the proportion of acetylene.

4. The method according to claim 3, characterized in that, Step S3 further includes: The calculated lower explosive limit is compared with a preset threshold. When the lower explosive limit is lower than the minimum threshold, the risk of the gas mixture being ignited is determined to be increased. The difference between the upper and lower explosion limits is calculated as the explosion concentration interval. When the explosion concentration interval increases, the explosion risk is considered to have increased.

5. The method according to claim 4, characterized in that, The oxygen-deficient space mentioned in step S1 includes the enclosed space inside the transformer bushing, the enclosed space inside the current transformer, or the enclosed space inside the transformer oil tank; the mixed gas is a free combustible hydrocarbon mixture generated by the electric arc or thermal fault acting on the transformer insulating oil in an oxygen-deficient environment, including at least methane, ethane, ethylene, and acetylene, and also including one or more of methanol, formaldehyde, acetaldehyde, propane, and propylene.

6. A system for determining the risk of transformer oil explosion under electric arc in an oxygen-deficient environment, characterized in that, include: The gas acquisition module is used to collect free mixed gas generated in the oxygen-deficient space inside transformers or oil-filled equipment under the action of electric arc or thermal fault. The gas analysis module includes a Fourier transform infrared spectrometer for directly determining the composition and volume fraction of the mixed gas, wherein the components include at least methane, ethane, ethylene, and acetylene; The explosion limit calculation module is used to calculate the lower explosion limit and upper explosion limit of the gas mixture based on the volume fraction of each component using the Richardley formula. The fault type determination module is used to calculate the characteristic gas ratios C2H2 / C2H4 and C2H4 / C2H6, and, in conjunction with the changing trend of the volume fraction of acetylene, determine the fault type according to the preset determination logic. The risk assessment module is used to assess the explosion risk level of the equipment by combining the explosion limit output by the explosion limit calculation module and the fault type determined by the fault type determination module.

7. The system according to claim 6, characterized in that, The fault type determination module further includes: The oil aging judgment unit is used to determine that the transformer insulating oil is aging more rapidly when the C2H2 / C2H4 ratio shows a downward trend. The arc energy determination unit is used to determine that the internal arc energy of the equipment is enhanced when a significant increase in the proportion of acetylene and a simultaneous significant increase in the C2H4 / C2H6 ratio are detected. The overheating fault determination unit is used to determine that an overheating fault has occurred inside the equipment when the acetylene content fluctuates or increases slowly while the C2H4 / C2H6 ratio increases sharply.

8. The system according to claim 7, characterized in that, The preset judgment logic of the fault type determination module is established based on experimental data of arc gas generation characteristics in oxygen-deficient environments under different insulating oil aging degrees, different arc energies, and different oil temperatures; wherein: The degree of aging of insulating oil is characterized by dielectric loss factor and acid value; The increase in arc energy was positively correlated with the simultaneous increase in the proportion of acetylene and the C2H4 / C2H6 ratio. The increase in oil temperature is positively correlated with the sharp increase in the C2H4 / C2H6 ratio, while it is weakly correlated or non-monotonic with the increase in the proportion of acetylene.

9. The system according to claim 8, characterized in that, The explosion limit calculation module further includes: The lower explosive limit comparison unit is used to compare the calculated lower explosive limit with a preset threshold. When the lower explosive limit is lower than the minimum threshold, it is determined that the risk of the gas mixture being ignited has increased. The explosion concentration interval calculation unit is used to calculate the difference between the upper and lower explosion limits as the explosion concentration interval. When the explosion concentration interval increases, the explosion risk is determined to be higher.

10. The system according to claim 9, characterized in that, The oxygen-deficient space collected by the gas acquisition module includes the enclosed space inside the transformer bushing, the enclosed space inside the current transformer, or the enclosed space inside the transformer oil tank; the mixed gas is a free combustible hydrocarbon mixture generated by electric arc or thermal fault acting on the transformer insulating oil in an oxygen-deficient environment, including at least methane, ethane, ethylene, and acetylene, and also one or more of methanol, formaldehyde, acetaldehyde, propane, and propylene.

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