Method and system for detecting concentration of dissolved gas in transformer oil

Abstract

The present invention provides a concentration detection method and system for dissolved gas in transformer oil, the concentration detection method comprising: degassing the dissolved gas in the transformer oil injected into a degassing bottle, passing the degassed gas into a White pool, measuring the gas phase concentration in the White pool based on a tunable diode laser absorption spectrum, and correcting the measured gas phase concentration; searching a preset gas-liquid conversion table according to the corrected gas phase concentration, and applying a linear interpolation method to obtain a liquid phase concentration corresponding to the gas phase concentration. The present invention can detect the concentration of dissolved gas in transformer oil, improves measurement accuracy, and has wide applicability.

Description

Technical Field

[0001] The invention belongs to the field of gas concentration detection, and in particular relates to a method and a system for detecting the concentration of dissolved gas in transformer oil. Background Art

[0002] Transformers are important power equipment in power systems. The status of transformers directly affects the operation of power systems. Once a transformer fails, it may cause a local power outage or even an explosion. There are three main types of transformer operation failures: mechanical failure, electrical failure, and thermal failure, among which electrical failure and thermal failure are the most common.

[0003] At present, most transformers in the power system use transformer oil and solid insulating materials as insulating materials for insulation and heat dissipation. With long-term operation, transformer oil and solid insulating materials gradually age under the influence of temperature, electric field, oxidation and other factors, which easily leads to the cracking of transformer oil and produces a small amount of H2 and low molecular hydrocarbon gases, such as CH4, C2H6, C2H4, etc. Through long-term research on the production mechanism of transformer oil, it is found that there is a certain correspondence between the type and content of dissolved gas in transformer oil and the potential fault of transformer. For example, CO and CO2 are produced by overheating and decomposition of solid insulating materials, and the production of C2H2 represents a discharge fault in the transformer. Therefore, the potential fault of the transformer can be obtained by analyzing the concentration of dissolved gas in transformer oil.

[0004] The existing method for detecting the concentration of dissolved gas in transformer oil is to separate the gas dissolved in transformer oil through vacuum degassing, membrane degassing, headspace degassing and other measures and send it to the gas detection module for detection and analysis. The gas detection module can use the gas chromatography detection principle, photoacoustic spectroscopy principle, infrared spectroscopy principle and other technologies to detect the gas concentration. The existing technology detects the gas phase concentration of the gas released from the transformer oil, rather than the actual concentration in the transformer oil, and the measurement is not accurate enough. Summary of the invention

[0005] The present invention provides a method and system for detecting the concentration of dissolved gas in transformer oil, which can solve the problem of insufficient measurement accuracy in the prior art.

[0006] In order to solve the above technical problems, the present invention proposes a method for detecting the concentration of dissolved gas in transformer oil, comprising: degassing the dissolved gas in the transformer oil injected into a degassing bottle, passing the degassed gas into a White cell, measuring the gas phase concentration in the White cell based on a tunable diode laser absorption spectrum, and correcting the measured gas phase concentration; searching a preset gas-liquid conversion table according to the corrected gas phase concentration, and applying a linear interpolation method to obtain a liquid phase concentration corresponding to the gas phase concentration.

[0007] Optionally, before degassing the dissolved gas in the transformer oil injected into the degassing bottle, the method includes: establishing a relationship between the gas concentration and the gas pressure in the White pool.

[0008] Optionally, establishing the relationship between the gas concentration and the air pressure in the White pool includes: using an air pump to pump the White pool to a first air pressure, establishing a concentration inversion relationship under the first air pressure state; introducing a gas of a preset concentration into the White pool, pumping the gas to a second air pressure, and using the concentration inversion relationship under the first air pressure state to calculate the gas concentration corresponding to the second air pressure; gradually pumping the White pool to the first air pressure, and calculating the corresponding gas concentration at every preset air pressure interval; for each air pressure, calculating the ratio of the preset concentration to the calculated gas concentration, and obtaining a correction coefficient for the gas at each air pressure as the relationship between the gas concentration and the air pressure in the White pool.

[0009] Optionally, the correcting the measured gas phase concentration includes: determining a correction coefficient according to a relationship between the gas concentration and the gas pressure in the White cell; and multiplying the gas phase concentration by the correction coefficient to obtain a corrected gas phase concentration.

[0010] Optionally, before degassing the dissolved gas in the transformer oil injected into the degassing bottle, the method includes: using an air pump to pump the degassing bottle to a third preset air pressure, wherein the third preset air pressure is the lowest air pressure to which the degassing bottle can be pumped.

[0011] Optionally, degassing the dissolved gas in the transformer oil injected into the degassing bottle includes: heating the temperature in the degassing bottle to a constant preset temperature; using an air pump to degas the dissolved gas in the transformer oil injected into the degassing bottle until the rate of change of the air pressure is lower than a preset difference after a preset number of connected blowings.

[0012] Optionally, searching a preset gas-liquid conversion table according to the corrected gas phase concentration, and applying a linear interpolation method to obtain a liquid phase concentration corresponding to the gas phase concentration, includes: searching a preset gas-liquid conversion table according to the corrected gas phase concentration to obtain a liquid phase concentration corresponding to the corrected gas phase concentration; if the liquid phase concentration corresponding to the corrected gas phase concentration is not found in the gas-liquid conversion table, searching the gas-liquid conversion table for a gas-phase low concentration value and a gas-phase high concentration value adjacent to the corrected gas phase concentration, as well as a liquid-phase low concentration value and a liquid-phase high concentration value corresponding to the gas-phase low concentration value and the gas-phase high concentration value, respectively, in the gas-liquid conversion table; and applying a linear interpolation method to calculate the liquid phase concentration corresponding to the gas phase concentration according to the found gas-phase low concentration value, the gas-phase high concentration value, the liquid-phase low concentration value, and the liquid-phase high concentration value.

[0013] Optionally, the calculating the liquid phase concentration corresponding to the gas phase concentration by applying a linear interpolation method according to the found gas phase low concentration value, the gas phase high concentration value, the liquid phase low concentration value, and the liquid phase high concentration value comprises: calculating the liquid phase concentration corresponding to the gas phase concentration by applying the following relationship according to the found gas phase low concentration value, the gas phase high concentration value, the liquid phase low concentration value, and the liquid phase high concentration value:

[0014]

[0015] Among them, C om is the liquid concentration, C ol is the liquid phase low concentration value, C oh is the liquid phase high concentration value, C gm is the corrected gas phase concentration, C gl is the gas phase low concentration value, C gh is the gas phase high concentration value.

[0016] Based on the same inventive concept, the present invention also proposes a concentration detection system for dissolved gas in transformer oil, comprising: a degassing bottle, an air pump and a White cell connected to the degassing bottle, a laser, a photoelectric converter, a phase-locked amplifier connected to the photoelectric converter, and a processor connected to the phase-locked amplifier; the degassing bottle is injected with transformer oil, the air pump is used to degas the dissolved gas in the transformer oil, the degassed gas is passed into the White cell, the laser emits laser into the White cell, the photoelectric converter converts the optical signal into an electrical signal at the output end of the White cell, the phase-locked amplifier processes the electrical signal to obtain a second harmonic, the processor measures the gas phase concentration in the White cell according to the second harmonic and corrects it, searches a preset gas-liquid conversion table according to the corrected gas phase concentration, and applies a linear interpolation method to obtain a liquid phase concentration corresponding to the gas phase concentration.

[0017] Optionally, the concentration detection system further comprises a heating device connected to the degassing bottle, wherein the heating device is used to heat the temperature in the degassing bottle to a constant preset temperature.

[0018] It can be seen from the above that the beneficial effects of the technical solution provided by the present invention are as follows: the present invention proposes a method and system for detecting the concentration of dissolved gas in transformer oil, the concentration detection method comprising: degassing the dissolved gas in the transformer oil injected into a degassing bottle, passing the degassed gas into a White pool, measuring the gas phase concentration in the White pool based on a tunable diode laser absorption spectrum, and correcting the measured gas phase concentration; searching a preset gas-liquid conversion table according to the corrected gas phase concentration, and applying a linear interpolation method to obtain a liquid phase concentration corresponding to the gas phase concentration, thereby realizing the detection of the dissolved gas concentration in the transformer oil, improving the measurement accuracy, and being widely applicable. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 Schematic diagram of the structure of the concentration detection system of dissolved gas in transformer oil according to an embodiment of the present invention;

[0021] Figure 2 Schematic diagram of the flow of a method for detecting the concentration of dissolved gas in transformer oil according to an embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0023] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present invention should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the embodiments of the present invention do not represent any order, quantity or importance, but are only used to distinguish different components. "Including" or "comprising" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0024] The embodiment of the present invention provides a system for detecting the concentration of dissolved gas in transformer oil. Figure 1 As shown, the concentration detection system includes: a degassing bottle 21, an air pump 22 and a White cell 23 connected to the degassing bottle 21, a laser 24, a photoelectric converter 25, a phase-locked amplifier 26 connected to the photoelectric converter 25, and a processor 27 connected to the phase-locked amplifier. First, the oil inlet valve of the degassing bottle 21 is opened, and the negative pressure in the degassing bottle 21 is pumped to a higher level using the air pump 22. The negative pressure can be controlled according to the performance of the air pump, preferably -96 kPa, and then the transformer oil to be tested is drawn out of the transformer into the degassing bottle 21 using the existing oil pump. After the degassing bottle 21 is filled with 1 liter of oil, the internal cavity is compressed so that the negative pressure in the degassing bottle 21 is reduced. The air pump 22 is used to start degassing the dissolved gas in the transformer oil to be tested, and the dissolved gas is precipitated from the transformer oil. The negative pressure of the degassing bottle 21 is further reduced. The more the dissolved gas is precipitated, the more the negative pressure of the degassing bottle 21 is reduced. When the negative pressure of the degassing bottle 21 no longer changes, it means that all the dissolved gas in the transformer oil to be tested has been precipitated. All the precipitated dissolved gases are passed into the White pool 23, and the laser 24 emits a laser into the White pool 23 to irradiate the dissolved gas to obtain an output light. The laser 24 may preferably be a distributed feedback laser. After detecting the output light, the photoelectric converter 25 converts the optical signal into an electrical signal, and transmits the electrical signal to the phase-locked amplifier 26. The phase-locked amplifier 26 demodulates the electrical signal and filters the noise, and obtains the twice-frequency signal amplitude and transmits it to the processor 27. The processor 27 measures the gas phase concentration of the dissolved gas according to the twice-frequency signal amplitude and corrects it, searches the preset gas-liquid conversion table according to the corrected gas phase concentration, and applies the linear interpolation method to obtain the liquid phase concentration corresponding to the gas phase concentration. Among them, the preset gas-liquid conversion table can be established during the experimental calibration stage through a TDLAS (Tunable Diode Laser Absorption Spectroscopy) device and a gas chromatograph. The concentration detection system of dissolved gas in transformer oil of the embodiment of the present invention can realize accurate detection of the concentration of dissolved gas in transformer oil. During the detection process, it is not necessary to measure the size of the internal cavity of the degassing bottle 21, which further reduces the workload. Figure 1 Concentration detection system of dissolved gas in transformer oil.

[0025] Furthermore, the concentration detection system also includes a heating device 28 connected to the degassing bottle 21. The heating device 28 is used to heat the temperature in the degassing bottle 21 to a constant preset temperature, and the preset temperature is preferably 50 degrees Celsius. By providing the heating device 28, the degassing bottle 21 can be kept in a sealed constant temperature state during the degassing process, and the degassing bottle 21 is airtight and prevents external air from entering.

[0026] The embodiment of the present invention also implements a method for detecting the concentration of dissolved gas in transformer oil, such as Figure 2 As shown, the concentration detection method includes:

[0027] Step S1: degas the dissolved gas in the transformer oil injected into the degassing bottle, and pass the degassing gas into the White cell. The gas phase concentration in the White cell is measured based on the tunable diode laser absorption spectroscopy, and the measured gas phase concentration is corrected.

[0028] Transformer oil is injected into the degassing bottle 21 to degas the transformer oil. During the degassing process, a closed constant temperature state is maintained to ensure that external air cannot enter. The gas in the liquid can be degassed by oil-gas separation method. Common oil-gas separation methods are vacuum method and dissolution equilibrium method. Dissolution equilibrium method is further divided into membrane separation method, mechanical oscillation method and dynamic headspace method. In the embodiment of the present invention, the dynamic headspace method in the oil-gas separation method is preferred, and the escaping dissolved gas is passed into the White pool 23. The laser 24 is driven to emit laser to optically measure the gas in the White pool 23, and the photoelectric converter 25 extracts the optical signal and converts the photoelectric signal to realize the measurement of the gas phase concentration in the White pool 23, and then the obtained gas phase concentration value in the White pool 23 is corrected according to the correction coefficient established in the experimental calibration stage.

[0029] Step S2: searching a preset gas-liquid conversion table according to the corrected gas phase concentration, and applying a linear interpolation method to obtain a liquid phase concentration corresponding to the gas phase concentration.

[0030] The preset gas-liquid conversion table can be established by the TDLAS device and the gas chromatograph during the experimental calibration stage. The chromatographic data obtained by the gas chromatograph when detecting the gas is similar to the gas phase data detected in the aforementioned concentration detection system of the dissolved gas in the transformer oil. The embodiment of the present invention establishes corresponding gas-liquid conversion tables for different transformer devices, thereby avoiding the deviation of the measurement results caused by the difference in equipment. The embodiment of the present invention searches the preset gas-liquid conversion table according to the corrected gas phase concentration value actually measured to obtain the gas phase concentration and liquid phase concentration of the table. If the corresponding gas phase concentration is not found in the preset gas-liquid conversion table, the gas phase low concentration value and the gas phase high concentration value adjacent to the gas phase concentration are found, and the interpolation formula is substituted to calculate the liquid phase concentration corresponding to the gas phase concentration. The interpolation calculation is performed based on the chromatographic data of the gas chromatograph and the gas phase data of the TDLAS device, thereby improving the detection accuracy.

[0031] In step S1 of the embodiment of the present invention, before degassing the dissolved gas in the transformer oil injected into the degassing bottle 21, it includes: establishing the relationship between the gas concentration and the air pressure in the White pool 23. Specifically, first, the White pool 23 is pumped to the first air pressure by an air pump, and the concentration inversion relationship under the first air pressure is established. In the embodiment of the present invention, the first air pressure can be preferably -90kpa. Then, a gas of a preset concentration is introduced into the White pool 23, and the gas is pumped to the second air pressure, and the concentration inversion relationship under the first air pressure state is used to calculate the gas concentration corresponding to the second air pressure; then the White pool 23 is gradually pumped to the first air pressure, and the corresponding gas concentration is calculated at each preset interval of air pressure; during this period, for each air pressure, the ratio of the preset concentration to the calculated gas concentration is calculated to obtain the correction coefficient of the gas at each air pressure, as the relationship between the gas concentration and the air pressure in the White pool 23, a corresponding correction coefficient table can be established to facilitate the correction calculation of the gas phase concentration in the subsequent actual measurement stage. The preset concentration and the preset interval can be set as needed, and the preset concentration is preferably 100ppm (parts per million), and the preset interval is preferably 1kPa. Taking acetylene gas as an example, 100ppm of acetylene is introduced into the degassing bottle 21, and the pressure is pumped to -70kpa. The acetylene gas concentration is measured to be 80ppm, and the correction factor of -70kpa is 100 / 80=1.25. During actual measurement, the pressure of the acetylene gas is measured to be -70kpa, and the gas concentration is 200ppm. According to the correction factor of -70kpa, the acetylene gas concentration can be corrected to 200*1.25=250ppm.

[0032] In an embodiment of the present invention, when correcting the measured gas phase concentration, a correction coefficient is determined based on the relationship between the gas concentration and the gas pressure in the White pool 23, and a corresponding correction coefficient table can be established to facilitate subsequent correction of the gas phase concentration; the gas phase concentration is multiplied by the correction coefficient to obtain the corrected gas phase concentration, and the gas phase concentration is the gas phase concentration of the dissolved gas in the measured transformer oil.

[0033] In step S1 of the embodiment of the present invention, before degassing the dissolved gas in the transformer oil injected into the degassing bottle 21, the air pump 22 can be used to pump the degassing bottle 21 to a third preset air pressure, and the third preset air pressure is the lowest air pressure that the degassing bottle 21 can be pumped to. The third preset air pressure value is set according to the performance of the air pump 22 used, and is preferably set to -96kpa.

[0034] In step S1 of the embodiment of the present invention, when degassing the dissolved gas in the transformer oil injected into the degassing bottle 21, the temperature in the degassing bottle 21 is also heated to a constant preset temperature, and the constant preset temperature can preferably be 50 degrees Celsius; the air pump 22 is used to degas the dissolved gas in the transformer oil injected into the degassing bottle 21 until the rate of change of the air pressure is lower than the preset difference after the preset number of connected blowings, indicating that the air pressure value in the degassing bottle 21 no longer changes, indicating that the degassing is sufficient. The preset number of times and the preset difference are set according to the actual measured situation and are not limited. If the rate of change of the negative pressure in the degassing bottle 21 is less than 0.01 after 10 consecutive blowings, it means that the degassing of the dissolved gas in the transformer oil is completed.

[0035] In step S2 of the embodiment of the present invention, optionally, a preset gas-liquid conversion table is searched according to the corrected gas phase concentration, and a linear interpolation method is applied to obtain the liquid phase concentration corresponding to the gas phase concentration. It is determined whether the preset gas-liquid conversion table has a corrected gas phase concentration value. If there is a consistent gas phase concentration value in the gas-liquid conversion table, the liquid phase concentration value corresponding to the corrected gas phase concentration is directly obtained. Taking acetylene gas as an example, Table 1 is a partial acetylene gas-liquid conversion table.

[0036] Table 1 Partial acetylene gas-liquid conversion table

[0037] TDLAS gas phase (μL / L) Chromatography (μL / L) 0.17 0.13 0.42 0.57 0.73 0.8 1.06 0.96 4.02 2.67 6.4 4.06 8.05 4.7 8.97 5.43 11.01 6.1 14.41 8.92 16.17 9.02 21.57 13.02 26.59 18.43 39.96 24 41.39 24.63 55.66 36.35 113.28 67.36

[0038] If the measured corrected acetylene gas concentration is 16.17 μL / L, then according to Table 1, the corresponding acetylene liquid phase concentration is 9.02 μL / L;

[0039] If the liquid phase concentration corresponding to the corrected gas phase concentration is not found in the gas-liquid conversion table, the gas phase low concentration value and gas phase high concentration value adjacent to the corrected gas phase concentration in the gas-liquid conversion table, as well as the liquid phase low concentration value and liquid phase high concentration value corresponding to the gas phase low concentration value and gas phase high concentration value in the gas-liquid conversion table, are searched; and the liquid phase concentration corresponding to the gas phase concentration is calculated using the linear interpolation method based on the found gas phase low concentration value, gas phase high concentration value, liquid phase low concentration value, and liquid phase high concentration value. Specifically, the liquid phase concentration corresponding to the gas phase concentration is calculated using the following relationship based on the found gas phase low concentration value, gas phase high concentration value, liquid phase low concentration value, and liquid phase high concentration value:

[0040]

[0041] Among them, C om is the liquid concentration, C ol is the low concentration value of liquid phase, C oh is the liquid phase high concentration value, C gm is the corrected gas phase concentration, C gl is the low concentration value in the gas phase, C ghis the gas phase high concentration value. For example, if the measured corrected acetylene gas concentration is C gm =25, we can find out from Table 1 that: C ol =13.02, C oh =18.43, C gl =21.57, C gh =26.59, substituting the value into the above interpolation formula, we can get C om =16.7, that is, the measured liquid concentration is 16.7μL / L.

[0042] The embodiment of the present invention provides a method and system for detecting the concentration of dissolved gas in transformer oil. The method comprises the following steps: degassing the dissolved gas in the transformer oil injected into a degassing bottle, passing the degassed gas into a White pool, measuring the gas phase concentration in the White pool based on a tunable diode laser absorption spectrum, and correcting the measured gas phase concentration; searching a preset gas-liquid conversion table according to the corrected gas phase concentration, and applying a linear interpolation method to obtain a liquid phase concentration corresponding to the gas phase concentration, thereby realizing the detection of the dissolved gas concentration in the transformer oil, improving the measurement accuracy, and being widely applicable.

[0043] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present disclosure (including the claims) is limited to these examples. Based on the concept of the present disclosure, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present invention as described above, which are not provided in detail for the sake of simplicity.

[0044] The embodiments of the present invention are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the scope of protection of this disclosure.

Claims

1. A method for detecting the concentration of dissolved gas in transformer oil, characterized in that: The concentration detection method comprises: Degassing the dissolved gas in the transformer oil injected into the degassing bottle, passing the degassing gas into a White cell, measuring the gas phase concentration in the White cell based on tunable diode laser absorption spectroscopy, and correcting the measured gas phase concentration; Searching a preset gas-liquid conversion table according to the corrected gas phase concentration, and applying a linear interpolation method to obtain a liquid phase concentration corresponding to the gas phase concentration; Before degassing the dissolved gas in the transformer oil injected into the degassing bottle, include: Establish the relationship between gas concentration and pressure in the White Pool; The method of establishing the relationship between the gas concentration and the gas pressure in the White Pool comprises: Using an air pump to pump the White Pool to a first air pressure, and establishing a concentration inversion relationship under the first air pressure state; Passing a gas of a preset concentration into the White cell, pumping the gas to a second pressure, and calculating the gas concentration corresponding to the second pressure by applying the concentration inversion relationship under the first pressure state; The White pool is gradually evacuated to the first air pressure, and the corresponding gas concentration is calculated at each preset air pressure interval; For each gas pressure, a ratio of a preset concentration to a calculated gas concentration is calculated to obtain a correction coefficient of the gas at each gas pressure as a relationship between the gas concentration and the gas pressure in the White cell; The step of searching a preset gas-liquid conversion table according to the corrected gas phase concentration and obtaining a liquid phase concentration corresponding to the gas phase concentration by applying a linear interpolation method includes: Searching a preset gas-liquid conversion table according to the corrected gas phase concentration to obtain a liquid phase concentration corresponding to the corrected gas phase concentration; If the liquid phase concentration corresponding to the corrected gas phase concentration is not found in the gas-liquid conversion table, then the gas phase low concentration value and the gas phase high concentration value adjacent to the corrected gas phase concentration in the gas-liquid conversion table are searched, as well as the liquid phase low concentration value and the liquid phase high concentration value corresponding to the gas phase low concentration value and the gas phase high concentration value in the gas-liquid conversion table, respectively; and the liquid phase concentration corresponding to the gas phase concentration is calculated by applying a linear interpolation method based on the found gas phase low concentration value, the gas phase high concentration value, the liquid phase low concentration value and the liquid phase high concentration value; Calculating the liquid phase concentration corresponding to the gas phase concentration by applying a linear interpolation method according to the found gas phase low concentration value, the gas phase high concentration value, the liquid phase low concentration value, and the liquid phase high concentration value, including: The liquid phase concentration corresponding to the gas phase concentration is calculated by applying the following relationship according to the found gas phase low concentration value, the gas phase high concentration value, the liquid phase low concentration value and the liquid phase high concentration value: in, is the liquid concentration, is the liquid phase low concentration value, is the liquid phase high concentration value, is the corrected gas phase concentration, is the gas phase low concentration value, is the gas phase high concentration value.

2. The concentration detection method according to claim 1, characterized in that: The step of correcting the measured gas phase concentration comprises: Determining a correction factor based on the relationship between gas concentration and gas pressure in the White cell; The gas phase concentration is multiplied by the correction coefficient to obtain the corrected gas phase concentration.

3. The concentration detection method according to claim 1, characterized in that: Before degassing the dissolved gas in the transformer oil injected into the degassing bottle, the method comprises: The degassing bottle is pumped to a third preset air pressure using an air pump, wherein the third preset air pressure is the lowest air pressure to which the degassing bottle can be pumped.

4. The concentration detection method according to claim 1, characterized in that: Degassing the dissolved gas in the transformer oil injected into the degassing bottle comprises: Heating the temperature in the degassing bottle to a constant preset temperature; An air pump is used to degas the dissolved gas in the transformer oil injected into the degassing bottle until the rate of change of the air pressure is lower than a preset difference after a preset number of continuous blowing.

5. A system for detecting the concentration of dissolved gas in transformer oil, comprising: A degassing bottle, an air pump and a White cell connected to the degassing bottle, a laser, a photoelectric converter, a phase-locked amplifier connected to the photoelectric converter, and a processor connected to the phase-locked amplifier; the degassing bottle is filled with transformer oil, the air pump is used to degas the dissolved gas in the transformer oil, the degassed gas is passed into the White cell, the laser emits laser light into the White cell, the photoelectric converter converts the optical signal into an electrical signal at the output end of the White cell, the phase-locked amplifier processes the electrical signal to obtain a second harmonic, the processor measures the gas phase concentration in the White cell according to the second harmonic and corrects it, searches a preset gas-liquid conversion table according to the corrected gas phase concentration, and applies a linear interpolation method to obtain a liquid phase concentration corresponding to the gas phase concentration; Before degassing the dissolved gas in the transformer oil injected into the degassing bottle, include: Establish the relationship between gas concentration and pressure in the White Pool; The method of establishing the relationship between the gas concentration and the gas pressure in the White Pool comprises: Using an air pump to pump the White Pool to a first air pressure, and establishing a concentration inversion relationship under the first air pressure state; Passing a gas of a preset concentration into the White cell, pumping the gas to a second pressure, and calculating the gas concentration corresponding to the second pressure by applying the concentration inversion relationship under the first pressure state; The White pool is gradually evacuated to the first air pressure, and the corresponding gas concentration is calculated at each preset air pressure interval; For each gas pressure, a ratio of a preset concentration to a calculated gas concentration is calculated to obtain a correction coefficient of the gas at each gas pressure as a relationship between the gas concentration and the gas pressure in the White cell; The step of searching a preset gas-liquid conversion table according to the corrected gas phase concentration and obtaining a liquid phase concentration corresponding to the gas phase concentration by applying a linear interpolation method includes: Searching a preset gas-liquid conversion table according to the corrected gas phase concentration to obtain a liquid phase concentration corresponding to the corrected gas phase concentration; If the liquid phase concentration corresponding to the corrected gas phase concentration is not found in the gas-liquid conversion table, then the gas phase low concentration value and the gas phase high concentration value adjacent to the corrected gas phase concentration in the gas-liquid conversion table are searched, as well as the liquid phase low concentration value and the liquid phase high concentration value corresponding to the gas phase low concentration value and the gas phase high concentration value in the gas-liquid conversion table, respectively; and the liquid phase concentration corresponding to the gas phase concentration is calculated by applying a linear interpolation method based on the found gas phase low concentration value, the gas phase high concentration value, the liquid phase low concentration value and the liquid phase high concentration value; Calculating the liquid phase concentration corresponding to the gas phase concentration by applying a linear interpolation method according to the found gas phase low concentration value, the gas phase high concentration value, the liquid phase low concentration value, and the liquid phase high concentration value, including: The liquid phase concentration corresponding to the gas phase concentration is calculated by applying the following relationship according to the found gas phase low concentration value, the gas phase high concentration value, the liquid phase low concentration value and the liquid phase high concentration value: in, is the liquid concentration, is the liquid phase low concentration value, is the liquid phase high concentration value, is the corrected gas phase concentration, is the gas phase low concentration value, is the gas phase high concentration value.

6. The concentration detection system according to claim 5, characterized in that: The concentration detection system further comprises a heating device connected to the degassing bottle, and the heating device is used to heat the temperature in the degassing bottle to a constant preset temperature.

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