Gas decomposition product concentration measurement method based on gas circulation

Abstract

The embodiment of the present application proposes a gas decomposition product concentration measurement method based on gas circulation, which is applied to a gas circulation device, the gas circulation device comprises a first gas chamber and a second gas chamber, both of which are used to be connected with a to-be-measured gas chamber, the first gas chamber is connected with the second gas chamber, and the method comprises the following steps: controlling the gas circulation device to perform gas mixing for a preset number of times; controlling the gas in the to-be-measured gas chamber to be transported into the first gas chamber, and stopping the gas transportation when the current pressure value is equal to the first pressure value; when the gas decomposition product concentration collected during the gas transportation is not less than a preset concentration threshold value, calculating a target gas decomposition product concentration. Through the gas circulation mode, the gas in the to-be-measured gas chamber is more fully mixed, the influence of the concentration change characteristic difference caused by the volume difference of the gas chamber on the detection result is reduced, the problem that it is difficult to obtain representative gas due to the slow gas diffusion speed is solved, and the accuracy of detecting the gas decomposition product concentration is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas concentration detection, and in particular to a gas decomposition product concentration measurement method based on gas circulation. BACKGROUND

[0002] Sulfur hexafluoride (SF6) is widely used in high-voltage electrical equipment (such as GIS combined electrical apparatus, circuit breakers, transformers, etc.) due to its excellent insulation and arc extinguishing performance. However, internal arc discharge or overheating faults in high-voltage electrical equipment can cause SF6 gas to decompose, producing toxic and corrosive products such as SO2, HF, H2S, etc., leading to insulation degradation, equipment explosion, and environmental hazards. Therefore, monitoring SF6 decomposition products is crucial for assessing the insulation condition inside the equipment, diagnosing potential faults (especially partial discharge), and predicting equipment life, and is a key means for equipment condition maintenance and ensuring safe operation of the power grid.

[0003] The SF6 decomposition products generated by equipment faults are naturally diffused to the detection port through molecular motion, with slow diffusion speed. It is difficult to obtain representative gas during gas sampling, which cannot reflect the true state inside the equipment. Moreover, the total amount of SF6 decomposition products generated by faults of the same order of magnitude is relatively fixed, but due to different diffusion conditions in different volume chambers, the same discharge level shows significantly different concentration variation characteristics in different volume chambers, which makes the judgment result obtained by simply relying on the concentration threshold as a warning indicator have large errors. Therefore, the existing online monitoring technology of decomposition products in the industry has the problem of large detection result error. SUMMARY

[0004] Therefore, it is necessary to propose a gas decomposition product concentration measurement method based on gas circulation to improve the accuracy of the detection result by mixing the gas in the to-be-measured gas chamber more fully through the gas circulation mode.

[0005] To achieve the above-mentioned purpose, the first aspect of the present application provides a gas decomposition product concentration measurement method based on gas circulation, which is applied to a gas circulation device, the gas circulation device includes a first gas chamber and a second gas chamber, the first gas chamber and the second gas chamber are both used to connect with a to-be-measured gas chamber, the first gas chamber is connected with the second gas chamber, and the method includes:

[0006] controlling the gas circulation device to perform a preset number of gas mixing, the gas mixing refers to a process of controlling the gas in the to-be-measured gas chamber to be transported between the first gas chamber, the second gas chamber and the to-be-measured gas chamber according to a preset path and finally returned to the to-be-measured gas chamber;

[0007] controlling the gas in the to-be-tested gas chamber to be transported into the first gas chamber, and collecting the gas decomposition product concentration and the gas flow rate in real time before a current pressure value in the to-be-tested gas chamber reaches a preset first pressure value, and stopping the gas transportation when the current pressure value is equal to the first pressure value;

[0008] When the gas decomposition product concentration is not less than a preset concentration threshold value, a target gas decomposition product concentration is calculated according to the gas decomposition product concentration and the gas flow rate.

[0009] Further, the target gas decomposition product concentration is calculated by the following formula:

[0010]

[0011] In the formula, is the target gas decomposition product concentration, is the gas decomposition product concentration collected at t, t is any time between the time when the to-be-tested gas chamber starts to transport gas to the first gas chamber and the time when the current pressure value reaches the first pressure value, is the gas flow rate at t.

[0012] Further, the one-time gas mixing process specifically includes:

[0013] controlling the gas in the to-be-tested gas chamber to be transported into the first gas chamber, and collecting the gas decomposition product concentration and the gas flow rate in real time before a current pressure value in the to-be-tested gas chamber reaches a preset first pressure value, and stopping the gas transportation when the current pressure value is equal to the first pressure value;

[0014] controlling the gas in the to-be-tested gas chamber to be transported into the second gas chamber until the gas transportation is stopped after the pressure between the to-be-tested gas chamber and the second gas chamber is balanced;

[0015] After the to-be-tested gas chamber stops transporting gas to the second gas chamber, the gas in the first gas chamber is controlled to be transported into the second gas chamber until the gas transportation is stopped after the pressure between the first gas chamber and the second gas chamber is balanced;

[0016] After the first gas chamber stops transporting gas to the second gas chamber, the gas in the second gas chamber is controlled to be transported into the to-be-tested gas chamber until the gas transportation is stopped after the pressure between the second gas chamber and the to-be-tested gas chamber is balanced, so as to realize one-time gas mixing.

[0017] Further, the one-time gas mixing process specifically includes:

[0018] controlling the gas in the to-be-tested gas chamber to be delivered into the first gas chamber, and collecting the current pressure value of the to-be-tested gas chamber in real time; when the current pressure value of the to-be-tested gas chamber reaches a preset third pressure value, stopping the gas delivery;

[0019] controlling the gas in the to-be-tested gas chamber to be delivered into the second gas chamber, and stopping the gas delivery after the pressure between the to-be-tested gas chamber and the second gas chamber is balanced;

[0020] after the to-be-tested gas chamber stops delivering the gas into the second gas chamber, controlling the gas in the first gas chamber to be delivered into the to-be-tested gas chamber, and stopping the gas delivery when the current pressure value of the to-be-tested gas chamber reaches a preset fourth pressure value;

[0021] controlling the gas in the second gas chamber to be delivered into the to-be-tested gas chamber, and stopping the gas delivery when the current pressure value of the to-be-tested gas chamber reaches a preset fifth pressure value, so as to realize the gas mixing once.

[0022] Further, the method further comprises:

[0023] when the gas decomposition product concentration is less than a preset concentration threshold value, after a preset time interval, continuing to execute the step of controlling the gas circulating device to perform the gas mixing for a preset number of times.

[0024] Further, the gas circulating device further comprises a first density table, a flow meter and an infrared gas analyzer, wherein the first density table is used to be connected with the to-be-tested gas chamber, and the flow meter and the infrared gas analyzer are both arranged between the to-be-tested gas chamber and the first gas chamber.

[0025] the first density table is used to measure the pressure value of the to-be-tested gas chamber;

[0026] the flow meter is used to collect the gas flow rate when the gas in the to-be-tested gas chamber is delivered into the first gas chamber;

[0027] the infrared gas analyzer is used to collect the gas decomposition product concentration when the gas in the to-be-tested gas chamber is delivered into the first gas chamber.

[0028] Further, the gas circulating device further comprises a first electromagnetic valve, a second electromagnetic valve, a pressure reducing valve, a third electromagnetic valve, a fourth electromagnetic valve, a fifth electromagnetic valve and a second density table.

[0029] the second density table is connected with the second gas chamber and is used to measure the pressure value of the second gas chamber;

[0030] One end of the first electromagnetic valve is connected with the gas chamber to be measured, one end of the pressure reducing valve is connected with the other end of the first electromagnetic valve and one end of the second electromagnetic valve respectively, the other end of the second electromagnetic valve is connected with one gas port of the second gas chamber, the other end of the pressure reducing valve is connected with one end of the flow meter, one end of the flow meter is connected with one end of the third electromagnetic valve, the other end of the third electromagnetic valve is connected with one end of the infrared gas analyzer, the other end of the infrared gas analyzer is connected with one end of the fourth electromagnetic valve, the other end of the fourth electromagnetic valve is connected with one gas port of the first gas chamber, the other gas port of the first gas chamber is connected with one end of the fifth electromagnetic valve, the other end of the fifth electromagnetic valve is connected with the other gas port of the second gas chamber;

[0031] When the gas in the gas chamber to be measured is transmitted into the first gas chamber, the first electromagnetic valve, the pressure reducing valve, the third electromagnetic valve and the fourth electromagnetic valve are controlled to be opened; when the gas in the gas chamber to be measured stops being transmitted into the first gas chamber, the first electromagnetic valve, the pressure reducing valve, the third electromagnetic valve and the fourth electromagnetic valve are controlled to be closed;

[0032] When the gas in the gas chamber to be measured is transmitted into the second gas chamber, the first electromagnetic valve and the second electromagnetic valve are controlled to be opened; when the gas in the gas chamber to be measured stops being transmitted into the second gas chamber, the first electromagnetic valve and the second electromagnetic valve are controlled to be closed;

[0033] When the gas in the first gas chamber is transmitted into the second gas chamber, or the gas in the second gas chamber is transmitted into the first gas chamber, the fifth electromagnetic valve is controlled to be opened; when the gas in the first gas chamber stops being transmitted into the second gas chamber, or the gas in the second gas chamber stops being transmitted into the first gas chamber, the fifth electromagnetic valve is controlled to be closed.

[0034] Further, a thermoelectric refrigerator is installed inside the first gas chamber cavity, for refrigerating the first gas chamber, reducing the pressure value in the first gas chamber, so as to realize the transmission of the gas in the gas chamber to be measured into the first gas chamber, or the transmission of the gas in the second gas chamber into the first gas chamber;

[0035] The thermoelectric refrigerator is also used for heating the first gas chamber, increasing the pressure value in the first gas chamber, so as to realize the transmission of the gas in the first gas chamber into the second gas chamber, or the transmission of the gas in the first gas chamber into the gas chamber to be measured.

[0036] Further, an electric heating wire is installed outside the second gas chamber cavity, for heating the second gas chamber, increasing the pressure value in the second gas chamber, so as to realize the transmission of the gas in the second gas chamber into the gas chamber to be measured, or the transmission of the gas in the second gas chamber into the first gas chamber.

[0037] Further, a gas diffuser is installed at the gas port of the second gas chamber, for when the gas enters the second gas chamber, the gas drives the paddle of the gas diffuser to rotate.

[0038] By adopting the embodiment of the present application, the following beneficial effects are achieved:

[0039] The embodiment of the present application provides a gas decomposition product concentration measurement method based on gas circulation. The method is applied to a gas circulation device. The gas circulation device comprises a first gas chamber and a second gas chamber. The first gas chamber and the second gas chamber are both used for being connected with a to-be-measured gas chamber. The first gas chamber is connected with the second gas chamber. The method comprises the following steps: controlling the gas circulation device to perform gas mixing for a preset number of times. The gas mixing refers to the process that the gas in the to-be-measured gas chamber is transported between the first gas chamber, the second gas chamber and the to-be-measured gas chamber according to a preset path and finally returns to the to-be-measured gas chamber. The gas in the to-be-measured gas chamber is transported to the first gas chamber. Before a current pressure value in the to-be-measured gas chamber reaches a preset first pressure value, the concentration of a gas decomposition product and the flow rate of the gas are collected in real time. When the current pressure value is equal to the first pressure value, the gas transportation is stopped. When the concentration of the gas decomposition product is not less than a preset concentration threshold value, the target concentration of the gas decomposition product is calculated according to the concentration of the gas decomposition product and the flow rate of the gas. According to the method, the gas in the to-be-measured gas chamber can be more fully mixed by the gas circulation. Through multiple gas circulation, the influence of the concentration change characteristic difference caused by the volume difference of the gas chamber on the detection result is reduced. The problem that it is difficult to obtain representative gas due to the slow natural diffusion speed of molecules is solved. Therefore, the real state inside the equipment can be more accurately reflected, and the accuracy of the detection result is improved. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only show some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0041] In the drawings:

[0042] Figure 1 The embodiment of the present application provides a gas decomposition product concentration measurement method based on gas circulation;

[0043] Figure 2 The embodiment of the present application provides a gas decomposition product concentration measurement method based on gas circulation;

[0044] Figure 3 The embodiment of the present application provides a gas decomposition product concentration measurement method based on gas circulation; DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0046] To solve the problem of large error of detection result of gas decomposition product concentration, an embodiment of the present application provides a gas circulating device capable of realizing online undisturbed microcirculation of gas decomposition product, and the gas circulating device is used for mixing the gas, so that the detected gas is more representative, and the error of detection result of gas decomposition product concentration is greatly reduced.

[0047] In an embodiment of the present application, a gas decomposition product concentration measurement method based on gas circulation is provided, please refer to Figure 1 , Figure 1 The gas decomposition product concentration measurement method based on gas circulation in the embodiments of the present application is applied to a gas circulating device, the gas circulating device includes a first gas chamber and a second gas chamber, the first gas chamber and the second gas chamber are both used for connecting with a to-be-measured gas chamber, the first gas chamber is connected with the second gas chamber, and the method includes the following steps.

[0048] In step 110, the gas circulating device is controlled to perform gas mixing for a preset number of times, and the gas mixing refers to a process that the gas in the to-be-measured gas chamber is transported between the first gas chamber, the second gas chamber and the to-be-measured gas chamber according to a preset path and finally returns to the to-be-measured gas chamber.

[0049] In the embodiments of the present application, in order to ensure that the collected gas sample can more reflect the real concentration of the decomposition product, the gas sample can be mixed before the concentration detection, so that the decomposition product is fully mixed in the gas, and then the concentration detection of the decomposition product is performed based on the mixed gas sample.

[0050] In an embodiment, the to-be-measured gas chamber is filled with SF6 gas, and before the decomposition product concentration measurement of the SF6 gas in the to-be-measured gas chamber, the SF6 gas in the to-be-measured gas chamber needs to be mixed, so as to accelerate the diffusion speed of the decomposition product in the to-be-measured gas chamber, so that the representative gas can be taken for detection, and the real state in the to-be-measured gas chamber can be more accurately reflected.

[0051] The gas mixing process is realized based on the gas circulating device, the first gas chamber and the second gas chamber in the gas circulating device are both communicated with the to-be-measured gas chamber, and the first gas chamber is communicated with the second gas chamber. Once the gas mixing process is controlled to transport the gas in the to-be-measured gas chamber according to a preset path in the first gas chamber, the second gas chamber and the to-be-measured gas chamber, and finally return to the to-be-measured gas chamber.

[0052] In an embodiment, the preset number of gas mixing times can be determined based on actual conditions. If one-time gas mixing can achieve the expected mixing effect, one time can be set. If n times can achieve the expected mixing effect, n times can be set, where n is any positive integer, which is not limited herein.

[0053] In the embodiment, the gas in the to-be-tested gas chamber is controlled to be transported between the first gas chamber, the second gas chamber and the to-be-tested gas chamber according to the preset path and finally returned to the to-be-tested gas chamber. On the one hand, this helps to accelerate the diffusion speed of the gas decomposition products in the to-be-tested gas chamber, so that the representative gas that is difficult to obtain at the time of gas sampling due to the slow natural diffusion speed can be fully mixed in a short time, ensuring that the collected gas sample can more truly reflect the overall concentration of the gas decomposition products in the to-be-tested gas chamber, and avoiding measurement errors caused by local concentration differences of the gas. On the other hand, this can eliminate the concentration variation characteristic differences caused by different gas diffusion conditions in different volume gas chambers, so that the measurement method has better adaptability to to-be-tested gas chambers of different volumes, reduces the judgment errors caused by the volume differences of the gas chambers, and enhances the universality of the measurement method in different high-voltage electrical equipment.

[0054] In step 120, the gas in the to-be-tested gas chamber is controlled to be transported to the first gas chamber, and the concentration of the gas decomposition products and the flow rate of the gas are collected in real time before the current pressure value in the to-be-tested gas chamber reaches the preset first pressure value, and the gas transportation is stopped when the current pressure value is equal to the first pressure value.

[0055] After the preset number of times of gas circulation by the gas circulation device, the concentration of the gas decomposition products in the to-be-tested gas chamber can be detected by the gas circulation device.

[0056] In an embodiment, a flow meter and an infrared gas analyzer can be installed between the first gas chamber and the to-be-tested gas chamber, and a density meter can be installed on the to-be-tested gas chamber, so as to collect the concentration of the gas decomposition products and the flow rate of the gas in real time when the gas in the to-be-tested gas chamber is transported to the first gas chamber, and the current pressure value in the to-be-tested gas chamber.

[0057] In the embodiment, the gas in the to-be-tested gas chamber is controlled to be transported to the first gas chamber until the current pressure value in the to-be-tested gas chamber is equal to the first pressure value, and the gas transportation is stopped. The first pressure value can be randomly set, but the pressure value in the to-be-tested gas chamber should be higher than the preset alarm pressure value. By monitoring the current pressure value in the to-be-tested gas chamber in real time and stopping the gas transportation when the preset first pressure value is reached, it is helpful to prevent the pressure in the to-be-tested gas chamber from exceeding the safety range or being lower than the normal working pressure, to ensure the normal operation and safe use of the equipment, and to avoid equipment damage or safety accidents caused by abnormal pressure.

[0058] In the process of gas transmission, the gas decomposition product concentration and the gas flow rate corresponding to the sampling point time are collected in real time, so as to calculate the target gas decomposition product concentration in the gas chamber to be measured. By collecting the gas decomposition product concentration and the gas flow rate in real time in the process of gas transmission, the related data of the gas can be obtained in time and accurately, which provides a more accurate basis for subsequent calculation of the gas decomposition product concentration, thereby improving the reliability of the detection result.

[0059] In step 130, when the gas decomposition product concentration is not less than the preset concentration threshold, the target gas decomposition product concentration is calculated according to the gas decomposition product concentration and the gas flow rate.

[0060] In the embodiment, in the process of transmitting the gas from the gas chamber to be measured to the first gas chamber, it is judged in real time whether the currently collected gas decomposition product concentration is less than the preset concentration threshold. The concentration threshold can be 0 or a negligible gas decomposition product concentration value. If the collected gas decomposition product concentration is less than the concentration threshold before the current pressure value in the gas chamber to be measured reaches the first pressure value, it is considered that there is no gas decomposition product or the gas decomposition product can be neglected in the gas chamber to be measured, or the gas in the gas chamber to be measured can not be fully mixed. At this time, steps 210-230 are executed again after a preset interval of time, so as to realize real-time gas mixing and gas decomposition product concentration detection. If the collected gas decomposition product concentration is not less than the concentration threshold before the current pressure value in the gas chamber to be measured reaches the first pressure value, it is considered that there is a gas decomposition product in the gas chamber to be measured. At this time, the target gas decomposition product concentration is calculated based on the collected gas decomposition product concentration and the gas flow rate.

[0061] In the embodiment, the further calculation and analysis are performed only when the concentration reaches the threshold, so as to avoid misjudgment caused by background noise or other interference factors, and improve the accuracy of the concentration detection. Based on the accurate target gas decomposition product concentration, the operation and maintenance personnel can quantitatively analyze the fault degree inside the high-voltage electrical equipment, so as to more accurately judge the health condition of the equipment, which is helpful for formulating a more targeted maintenance strategy and reasonably arranging the maintenance time and resources.

[0062] In the embodiment of the application, the gas mixing and concentration detection are realized by the gas circulating device, which is suitable for different volumes of the gas chamber to be measured, reduces the judgment error caused by slow gas diffusion and volume difference of the gas chamber, and enhances the universality of the measurement method in different high-voltage electrical equipment.

[0063] In an embodiment of the application, the gas mixing process once includes:

[0064] Step 210, control the gas in the to-be-tested gas chamber to be delivered to the first gas chamber, and collect the current pressure value of the to-be-tested gas chamber in real time; when the current pressure value in the to-be-tested gas chamber reaches a preset second pressure value, stop the gas delivery.

[0065] In the embodiment, the gas mixing process can be implemented based on the gas circulating device. First, the gas in the to-be-tested gas chamber is delivered to the first gas chamber until the current pressure value in the to-be-tested gas chamber reaches a preset second pressure value. The second pressure value can be randomly set, but it is required to ensure that the current pressure value in the to-be-tested gas chamber is not lower than a preset alarm pressure value. The first pressure value and the second pressure value can be the same or different, which is not limited herein.

[0066] Step 220, control the gas in the to-be-tested gas chamber to be delivered to the second gas chamber until the pressure balance between the to-be-tested gas chamber and the second gas chamber is achieved and the gas delivery is stopped.

[0067] Specifically, after the pressure value in the to-be-tested gas chamber reaches the second pressure value, the gas in the to-be-tested gas chamber is delivered to the second gas chamber until the pressure balance between the to-be-tested gas chamber and the second gas chamber is achieved, and the gas delivery from the to-be-tested gas chamber to the second gas chamber is stopped.

[0068] Step 230, after the to-be-tested gas chamber stops delivering the gas to the second gas chamber, control the gas in the first gas chamber to be delivered to the second gas chamber until the pressure balance between the first gas chamber and the second gas chamber is achieved and the gas delivery is stopped.

[0069] Specifically, after the pressure balance between the to-be-tested gas chamber and the second gas chamber is achieved and the gas delivery is stopped, the gas in the first gas chamber is delivered to the second gas chamber for gas mixing until the pressure balance between the first gas chamber and the second gas chamber is achieved and the gas delivery is stopped.

[0070] Step 240, after the first gas chamber stops delivering the gas to the second gas chamber, control the gas in the second gas chamber to be delivered to the to-be-tested gas chamber until the pressure balance between the second gas chamber and the to-be-tested gas chamber is achieved and the gas delivery is stopped, so as to achieve one-time gas mixing.

[0071] Specifically, after the pressure balance between the first gas chamber and the second gas chamber is achieved and the gas delivery is stopped, the gas in the second gas chamber is delivered to the to-be-tested gas chamber for gas mixing until the pressure balance between the second gas chamber and the to-be-tested gas chamber is achieved and the gas delivery is stopped, thereby achieving one-time gas mixing operation.

[0072] The embodiment of the present application realizes the circulation flow of the gas between different gas chambers by controlling the gas in the to-be-tested gas chamber to be sequentially delivered to the first gas chamber, the second gas chamber, and then back to the to-be-tested gas chamber, so that the decomposition products of the gas in the to-be-tested gas chamber can be fully mixed, the diffusion speed of the decomposition products in the to-be-tested gas chamber is accelerated, the defect of slow natural diffusion speed is overcome, the gas sample collected based on the fully mixed gas is more representative, the measurement error caused by the local concentration difference of the gas is avoided, and thus the accuracy of the concentration detection of the decomposition products of the gas is improved. In addition, the gas mixing operation is applicable to to-be-tested gas chambers of different volumes, the concentration change characteristics caused by the different diffusion conditions of the gas in the gas chambers of different volumes are reduced, the judgment error caused by the volume difference of the gas chambers is reduced, and the universality of the measurement method in different high-voltage electrical equipment is enhanced.

[0073] In another embodiment of the present application, the one-time gas mixing process specifically includes:

[0074] Step 310, the gas in the to-be-tested gas chamber is controlled to be delivered to the first gas chamber, and the current pressure value of the to-be-tested gas chamber is collected in real time; when the current pressure value of the to-be-tested gas chamber reaches a preset third pressure value, the gas delivery is stopped.

[0075] In the embodiment, the gas mixing process can be realized based on the gas circulation device. First, the gas in the to-be-tested gas chamber is delivered to the first gas chamber until the current pressure value of the to-be-tested gas chamber reaches a preset third pressure value. The third pressure value can be randomly set, but it is required to ensure that the current pressure value of the to-be-tested gas chamber is not lower than a preset alarm pressure value, and the second pressure value and the third pressure value can be the same or different, which is not limited herein.

[0076] Step 320, the gas in the to-be-tested gas chamber is controlled to be delivered to the second gas chamber, and the gas transmission is stopped after the pressure balance between the to-be-tested gas chamber and the second gas chamber.

[0077] Specifically, after the pressure value of the to-be-tested gas chamber reaches the third pressure value, the gas in the to-be-tested gas chamber is delivered to the second gas chamber until the pressure of the to-be-tested gas chamber and the second gas chamber is balanced, and then the gas transmission from the to-be-tested gas chamber to the second gas chamber is stopped.

[0078] Step 330, after the to-be-tested gas chamber stops transmitting the gas to the second gas chamber, the gas in the first gas chamber is controlled to be delivered to the to-be-tested gas chamber, and when the current pressure value of the to-be-tested gas chamber reaches a preset fourth pressure value, the gas delivery is stopped.

[0079] Specifically, after the pressure of the to-be-tested gas chamber and the second gas chamber is balanced and the gas transmission is stopped, the gas in the first gas chamber is controlled to be delivered to the to-be-tested gas chamber for gas mixing, and when the current pressure value of the to-be-tested gas chamber reaches a preset fourth pressure value, the gas delivery is stopped.

[0080] Step 340, control the gas in the second gas chamber to be transported to the chamber to be measured, and stop the gas transportation when the current pressure value in the chamber to be measured reaches the preset fifth pressure value, so as to realize the gas mixing.

[0081] Specifically, after the first gas chamber stops transmitting gas to the chamber to be measured, the gas in the second gas chamber is controlled to be transported to the chamber to be measured for gas mixing, and the gas transportation is stopped when the current pressure value in the chamber to be measured reaches the preset fifth pressure value.

[0082] The embodiment of the present application realizes the circulation flow of the gas between different gas chambers by controlling the gas in the chamber to be measured to be transported to the first gas chamber, the second gas chamber, and then back to the chamber to be measured. This circulation flow can fully mix the decomposition products of the gas in the chamber to be measured, accelerate the diffusion speed of the decomposition products in the chamber to be measured, and overcome the defect of slow natural diffusion speed. The fully mixed gas can ensure that the collected gas sample is more representative, avoid measurement errors caused by local concentration differences of the gas, and thus improve the accuracy of the concentration detection of the gas decomposition products. The gas mixing operation is suitable for chambers to be measured of different volumes, reduces the concentration variation characteristics caused by different diffusion conditions of the gas in different volume gas chambers, and reduces the judgment errors caused by the volume difference of the gas chamber. This makes the measurement method have better universality in different high-voltage electrical equipment and can adapt to the detection needs of various equipment.

[0083] In an embodiment of the present application, the target gas decomposition product concentration is calculated by the following formula:

[0084]

[0085] In the formula, is the target gas decomposition product concentration, is the gas decomposition product concentration collected at t, t is any time between the time when the chamber to be measured starts to transmit gas to the first gas chamber and the time when the current pressure value reaches the first pressure value, is the gas flow rate at t.

[0086] The embodiment of the present application calculates the average value of the gas decomposition product concentration in the gas transmission time period by integral method, so as to obtain the target gas decomposition product concentration excluding noise interference, so that the measured gas decomposition product concentration is more accurate.

[0087] In an embodiment of the present application, the specific method for calculating the total amount of gas decomposition products in the gas chamber is as follows:

[0088] The volume of the gas chamber to be measured is measured at each gas mixing, and the volume of the decomposition product in the gas chamber to be measured is calculated according to the average value of the gas chamber volume obtained by each measurement and the target gas decomposition product concentration as follows:

[0089]

[0090] wherein, is the target gas decomposition product concentration, is the average value of the gas chamber volume, , is the gas chamber volume measured at the i-th gas mixing.

[0091] The pressure value P of the gas chamber to be measured at the time when the target gas decomposition product concentration is calculated is read, and the gas molar number of the decomposition product is obtained according to the ideal gas state equation as follows:

[0092]

[0093] wherein, is the gas molar number of the decomposition product, is the volume of the decomposition product in the gas chamber to be measured, R is the ideal gas constant, T is the thermodynamic temperature at the moment.

[0094] The total amount of the decomposition product gas is calculated according to the gas molar number of the decomposition product and the gas molar mass of the decomposition product as follows:

[0095]

[0096] wherein, is the gas molar mass of the decomposition product, is the total amount of the gas decomposition product in the gas chamber.

[0097] In an embodiment of the present application, the measurement method of the volume of the gas chamber to be measured at each gas mixing is as follows:

[0098] A, the initial pressure value of the gas chamber to be measured at the current gas mixing is collected.

[0099] The initial pressure value in the gas chamber to be measured is collected before the gas circulating device is controlled to mix the gas in the gas chamber to be measured.

[0100] B, the gas circulating device is controlled to perform one gas mixing, and the volume of the gas chamber to be measured calculated at the current gas mixing is obtained according to the gas flow rate when the gas in the gas chamber to be measured is transported to the first gas chamber, the gas decomposition product concentration, the initial pressure value and the current pressure value.

[0101] In the embodiment, the flow meter and the infrared gas analyzer are installed between the first gas chamber and the to-be-tested gas chamber, and the densimeter is installed on the to-be-tested gas chamber. When the gas circulating device mixes the gas in the to-be-tested gas chamber, the current pressure value of the to-be-tested gas chamber is collected by the flow meter, and the gas flow rate and the gas decomposition product concentration when the gas in the to-be-tested gas chamber is transported to the first gas chamber are collected in real time by the infrared gas analyzer. In the process of gas transportation, the gas decomposition product concentration and the gas flow rate corresponding to the sampling point moment are collected in real time, so as to calculate the target gas decomposition product concentration in the to-be-tested gas chamber. By collecting the gas decomposition product concentration and the gas flow rate in real time in the process of gas transportation, the related data of the gas can be obtained in time and accurately, which provides a more accurate basis for subsequent calculation of the gas decomposition product concentration, thereby improving the reliability of the detection result.

[0102] In the embodiment of the present application, the volume of the to-be-tested gas chamber during current gas mixing is calculated by the following formula:

[0103]

[0104] In the formula, is the volume of the to-be-tested gas chamber calculated during current gas mixing, is the pressure value under normal pressure, is the gas flow rate when the gas in the to-be-tested gas chamber is transported to the first gas chamber; is the gas transportation time when the gas in the to-be-tested gas chamber is transported to the first gas chamber; is the initial pressure value in the to-be-tested gas chamber during current gas mixing; is the current pressure value of the to-be-tested gas chamber during current gas mixing.

[0105] The embodiment of the present application proposes a gas circulating device based on thermal cycle. For details, please refer to Figure 2 , Figure 2 is the structural diagram of the gas circulating device in the embodiment of the present application. In the embodiment, the gas circulating device comprises a first densimeter 5, a flow meter 15 and an infrared gas analyzer 6. The first densimeter 5 is used to be connected with the to-be-tested gas chamber 16, and the flow meter 15 and the infrared gas analyzer 6 are both arranged between the to-be-tested gas chamber 16 and the first gas chamber 1. The first densimeter 5 is used to measure the pressure value of the to-be-tested gas chamber 16. The flow meter 15 is used to collect the gas flow rate when the gas in the to-be-tested gas chamber 16 is transported to the first gas chamber 1. The infrared gas analyzer 6 is used to collect the gas decomposition product concentration when the gas in the to-be-tested gas chamber 16 is transported to the first gas chamber 1.

[0106] In the embodiment, the gas circulation device further comprises a first electromagnetic valve 7, a second electromagnetic valve 8, a pressure reducing valve 11, a third electromagnetic valve 9, a fourth electromagnetic valve 10, a fifth electromagnetic valve 12 and a second density meter 13. The second density meter 13 is connected with the second gas chamber 2 and used for measuring the pressure value of the second gas chamber 2. One end of the first electromagnetic valve 7 is connected with the to-be-measured gas chamber 16. One end of the pressure reducing valve 11 is connected with the other end of the first electromagnetic valve 7 and one end of the second electromagnetic valve 8 respectively. The other end of the second electromagnetic valve 8 is connected with one gas port of the second gas chamber 2. The other end of the pressure reducing valve 11 is connected with one end of the flow meter 15. One end of the flow meter 15 is connected with one end of the third electromagnetic valve 9. The other end of the third electromagnetic valve 9 is connected with one end of the infrared gas analyzer 6. The other end of the infrared gas analyzer 6 is connected with one end of the fourth electromagnetic valve 10. The other end of the fourth electromagnetic valve 10 is connected with one gas port of the first gas chamber 1. The other gas port of the first gas chamber 1 is connected with one end of the fifth electromagnetic valve 12. The other end of the fifth electromagnetic valve 12 is connected with the other gas port of the second gas chamber 2. When the gas in the to-be-measured gas chamber 16 is transmitted into the first gas chamber 1, the first electromagnetic valve 7, the pressure reducing valve 11, the third electromagnetic valve 9 and the fourth electromagnetic valve 10 are controlled to be opened. When the to-be-measured gas chamber 16 stops transmitting the gas into the first gas chamber 1, the first electromagnetic valve 7, the pressure reducing valve 11, the third electromagnetic valve 9 and the fourth electromagnetic valve 10 are controlled to be closed. When the gas in the to-be-measured gas chamber 16 is transmitted into the second gas chamber 2, the first electromagnetic valve 7 and the second electromagnetic valve 8 are controlled to be opened. When the to-be-measured gas chamber 16 stops transmitting the gas into the second gas chamber 2, the first electromagnetic valve 7 and the second electromagnetic valve 8 are controlled to be closed. When the gas in the first gas chamber 1 is transmitted into the second gas chamber 2 or the gas in the second gas chamber 2 is transmitted into the first gas chamber 1, the fifth electromagnetic valve 12 is controlled to be opened. When the first gas chamber 1 stops transmitting the gas into the second gas chamber 2 or the second gas chamber 2 stops transmitting the gas into the first gas chamber 1, the fifth electromagnetic valve 12 is controlled to be closed.

[0107] In the embodiment, the thermoelectric cooler 4 is installed inside the cavity of the first gas chamber 1 and used for refrigerating the first gas chamber 1, reducing the pressure value in the first gas chamber 1, realizing the transmission of the gas in the to-be-measured gas chamber 16 into the first gas chamber 1 or the transmission of the gas in the second gas chamber 2 into the first gas chamber 1. The thermoelectric cooler 4 is also used for heating the first gas chamber 1, increasing the pressure value in the first gas chamber 1, realizing the transmission of the gas in the first gas chamber 1 into the second gas chamber 2 or the transmission of the gas in the first gas chamber 1 into the to-be-measured gas chamber 16.

[0108] In the embodiment, the electric heating wire 3 is installed outside the cavity of the second gas chamber 2 and used for heating the second gas chamber 2, increasing the pressure value in the second gas chamber 2, realizing the transmission of the gas in the second gas chamber 2 into the to-be-measured gas chamber 16 or the transmission of the gas in the second gas chamber 2 into the first gas chamber 1.

[0109] In the embodiment, a gas diffuser 14 is installed at the gas port of the second gas chamber 2, for when the gas enters the second gas chamber 2, the gas drives the paddle 17 of the gas diffuser 14 to rotate.

[0110] The working principle of the gas circulation device according to the embodiment is as follows: the first gas chamber 1 is communicated with the second gas chamber 2, and the fifth electromagnetic valve 12 controls the on-off between the first gas chamber 1 and the second gas chamber 2; the first gas chamber 1 is connected with the infrared gas analyzer 6 through the fourth electromagnetic valve 10, and the on-off is controlled by the fourth electromagnetic valve 10; the first gas chamber 1 is an elongated cavity, and a thermoelectric refrigerator 4 is installed on the inner side of the cavity, which is a device for realizing refrigeration or heating based on the thermoelectric effect (Peltier effect), and after being electrified, one end absorbs heat and the other end releases heat, and the cold and hot ends can be switched by reversing the current; an electric heating wire is installed on the outer side of the cavity of the second gas chamber 2; the second density meter 13 monitors the gas pressure of the second gas chamber 2 in real time; the pressure reducing valve 11 is connected with the second gas chamber 2 through the second electromagnetic valve 8, and the on-off is controlled by the second electromagnetic valve 8. By controlling the electric heating wire 3 of the first gas chamber 1 and the thermoelectric refrigerator 4 of the second gas chamber 2 to work, online thermal circulation is realized to achieve the effect of uniform distribution of the gas in the to-be-measured gas chamber 16, so as to eliminate the sampling deviation of the non-representative gas taking, and the pump-free thermal driving circulation mechanism can eliminate the disadvantage of insufficient sealing of the pump body structure in the traditional technology.

[0111] In an embodiment, the initial pressure value P0 (pressure value at 20℃) of the to-be-measured gas chamber 16 is read by the first density meter 5. The first electromagnetic valve 7, the pressure reducing valve 11, the third electromagnetic valve 9 and the fourth electromagnetic valve 10 are opened, the refrigeration function of the thermoelectric refrigerator 4 is opened, and the first gas chamber 1 is refrigerated to reduce the temperature in the first gas chamber 1 to the liquefaction temperature T0 of SF6 gas at the initial pressure value P0. At this time, the pressure of the first gas chamber 1 is less than the pressure of the to-be-measured gas chamber 16, and the gas in the to-be-measured gas chamber 16 will enter the first gas chamber 1 through the flowmeter 15 and the infrared gas analyzer 6, the current pressure value of the to-be-measured gas chamber 16 is read in real time by the first density meter 5, the concentration data of the gas decomposition product is detected by the infrared gas analyzer 6, and when the current pressure value of the to-be-measured gas chamber 16 reaches the preset first pressure value / second pressure value, the first electromagnetic valve 7, the pressure reducing valve 11, the third electromagnetic valve 9 and the fourth electromagnetic valve 10 are closed.

[0112] In an embodiment, the first electromagnetic valve 7 and the second electromagnetic valve 8 are opened, so that the gas in the to-be-measured gas chamber 16 quickly enters the second gas chamber 2, until the pressure balance, that is, the pressure values monitored by the first density meter 5 and the second density meter 13 are equal, and then the first electromagnetic valve 7 and the second electromagnetic valve 8 are closed.

[0113] In one embodiment, the fifth electromagnetic valve 12 is opened, and the thermoelectric refrigerator 4 is switched to the heating function, so that the gas in the first gas chamber 1 is vaporized and pressurized to enter the second gas chamber 2, and in this condition, the volume of the second gas chamber 2 is greater than that of the first gas chamber 1. The gas port of the second gas chamber 2 is provided with a gas diffuser 14, which can be referred to Figure 3 , Figure 3 The structure diagram of the gas diffuser 14 in the embodiment of the present application can be seen that the gas diffuser 14 includes a paddle 17, when the gas enters the second gas chamber 2, the gas drives the paddle 17 to rotate, expands the diffusion direction of the gas, and further ensures the mixing effect of the gas in the second gas chamber 2. The gas in the first gas chamber 1 continues to be heated, the higher the temperature, the more gas enters the second gas chamber 2; when the pressure of the second gas chamber 2 and the first gas chamber 1 is balanced, the fifth electromagnetic valve 12 is closed, and the thermoelectric refrigerator 4 stops heating and reversely refrigerates for the next gas circulation.

[0114] In one embodiment, the heating wire 3 of the second gas chamber 2 is opened, and the first electromagnetic valve 7 and the second electromagnetic valve 8 are opened, so that the gas in the second gas chamber 2 is heated by the heating wire 3, and thus the pressure of the gas in the second gas chamber 2 is increased due to the temperature rise, and the gas in the second gas chamber 2 is backfilled to the test gas chamber 16. Since the temperature of the gas backfilled to the test gas chamber 16 is high, a turbulent flow is formed into the test gas chamber 16 to accelerate the movement of the gas molecules in the test gas chamber 16, and further accelerate the gas mixing process. When the pressure value recorded by the first density meter 5 no longer changes, that is, after the pressure of the test gas chamber 16 and the second gas chamber 2 is balanced, the heating wire 3 of the second gas chamber 2, the first electromagnetic valve 7 and the second electromagnetic valve 8 are closed.

[0115] The technical features of the above embodiments can be combined in any way. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, but as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the present application.

[0116] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent of the present application. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A method for measuring the concentration of gas decomposition products based on gas circulation, characterized in that, The method is applied to a gas circulation device, which includes a first gas chamber and a second gas chamber. Both the first and second gas chambers are connected to a gas chamber to be tested. The first gas chamber is connected to the second gas chamber. The method includes: The gas circulation device is controlled to perform gas mixing a preset number of times. Gas mixing refers to the process of controlling the gas in the test chamber to be transported between the first chamber, the second chamber and the test chamber according to a preset path and finally returning to the test chamber. The gas in the test chamber is controlled to be delivered to the first chamber, and the concentration of gas decomposition products and gas flow rate are collected in real time before the current pressure value in the test chamber reaches the preset first pressure value. When the current pressure value is equal to the first pressure value, the gas delivery is stopped. When the concentration of the gas decomposition products is not less than a preset concentration threshold, the target concentration of the gas decomposition products is calculated based on the concentration of the gas decomposition products and the gas flow rate. The primary gas mixing process specifically includes: The gas in the chamber to be tested is controlled to be delivered to the first chamber, and the current pressure value of the chamber to be tested is collected in real time; when the current pressure value in the chamber to be tested reaches the preset second pressure value, the gas delivery is stopped. The gas in the chamber to be tested is controlled to be transported to the second chamber until the pressure between the chamber to be tested and the second chamber is balanced, and then the gas transmission is stopped. After the gas supply from the test chamber to the second chamber is stopped, the gas in the first chamber is controlled to be delivered to the second chamber until the pressure between the first chamber and the second chamber is balanced and the gas supply is stopped. After the first gas chamber stops transmitting gas to the second gas chamber, the gas in the second gas chamber is controlled to be delivered to the gas chamber to be tested until the pressure between the second gas chamber and the gas chamber to be tested is balanced and then the gas transmission is stopped to achieve gas mixing once. or The gas mixing process specifically includes: The gas in the chamber to be tested is controlled to be delivered to the first chamber, and the current pressure value of the chamber to be tested is collected in real time; when the current pressure value in the chamber to be tested reaches a preset third pressure value, the gas delivery is stopped. The gas in the chamber to be tested is controlled to be transported to the second chamber until the pressure between the chamber to be tested and the second chamber is balanced, and then the gas transmission is stopped. After the gas supply to the second gas chamber is stopped in the test chamber, the gas in the first gas chamber is controlled to be supplied to the test chamber. When the current pressure value in the test chamber reaches the preset fourth pressure value, the gas supply is stopped. The gas in the second chamber is controlled to be delivered to the test chamber. When the current pressure value in the test chamber reaches the preset fifth pressure value, the gas delivery is stopped to achieve gas mixing once.

2. The method as described in claim 1, characterized in that, The concentration of the target gas decomposition products is calculated using the following formula: In the formula, The concentration of the decomposition products of the target gas. Let t be the concentration of gas decomposition products collected at time t, where t is any time between the moment when the gas chamber to be tested begins to transfer gas to the first gas chamber and the moment when the current pressure value reaches the first pressure value. Let be the gas flow rate at time t.

3. The method as described in claim 1, characterized in that, The method further includes: When the concentration of the gas decomposition products is less than a preset concentration threshold, the gas mixing step of controlling the gas circulation device to perform a preset number of times is continued after a preset time interval.

4. The method as described in claim 1, characterized in that, The gas circulation device further includes: a first density meter, a flow meter, and an infrared gas analyzer, wherein the first density meter is used to connect to the gas chamber to be tested, and the flow meter and the infrared gas analyzer are both disposed between the gas chamber to be tested and the first gas chamber; The first density meter is used to measure the pressure value of the gas chamber to be tested; The flow meter is used to collect the gas flow rate when the gas in the gas chamber to be measured is transferred to the first gas chamber; The infrared gas analyzer is used to collect the concentration of gas decomposition products when the gas in the test chamber is transferred to the first chamber.

5. The method as described in claim 4, characterized in that, The gas circulation device further includes: a first solenoid valve, a second solenoid valve, a pressure reducing valve, a third solenoid valve, a fourth solenoid valve, a fifth solenoid valve, and a second density gauge. The second density meter is connected to the second air chamber and is used to measure the pressure value of the second air chamber; One end of the first solenoid valve is connected to the gas chamber to be tested. One end of the pressure reducing valve is connected to the other end of the first solenoid valve and one end of the second solenoid valve. The other end of the second solenoid valve is connected to one gas port of the second gas chamber. The other end of the pressure reducing valve is connected to one end of the flow meter. One end of the flow meter is connected to one end of the third solenoid valve. The other end of the third solenoid valve is connected to one end of the infrared gas analyzer. The other end of the infrared gas analyzer is connected to one end of the fourth solenoid valve. The other end of the fourth solenoid valve is connected to one gas port of the first gas chamber. The other gas port of the first gas chamber is connected to one end of the fifth solenoid valve. The other end of the fifth solenoid valve is connected to the other gas port of the second gas chamber. When the gas in the test chamber is transferred to the first chamber, the first solenoid valve, the pressure reducing valve, the third solenoid valve, and the fourth solenoid valve are opened; when the test chamber stops transferring gas to the first chamber, the first solenoid valve, the pressure reducing valve, the third solenoid valve, and the fourth solenoid valve are closed. When the gas in the test chamber is transferred to the second chamber, the first and second solenoid valves are opened; when the test chamber stops transferring gas to the second chamber, the first and second solenoid valves are closed. When gas in the first chamber is transferred to the second chamber, or gas in the second chamber is transferred to the first chamber, the fifth solenoid valve is opened; when the first chamber stops transferring gas to the second chamber, or the second chamber stops transferring gas to the first chamber, the fifth solenoid valve is closed.

6. The method as described in claim 4, characterized in that, A thermoelectric cooler is installed inside the first air chamber to cool the first air chamber and reduce the pressure value inside the first air chamber, so as to realize the transfer of gas from the test air chamber to the first air chamber, or the transfer of gas from the second air chamber to the first air chamber. The thermoelectric cooler is also used to heat the first gas chamber and increase the pressure value inside the first gas chamber, so as to realize the transfer of gas from the first gas chamber to the second gas chamber, or the transfer of gas from the first gas chamber to the gas chamber to be tested.

7. The method as described in claim 4, characterized in that, An electric heating wire is installed on the outside of the second air chamber to heat the second air chamber and increase the pressure value inside the second air chamber, so as to realize the transfer of gas in the second air chamber to the air chamber to be tested, or the transfer of gas in the second air chamber to the first air chamber.

8. The method as described in claim 4, characterized in that, A gas diffuser is installed at the air inlet of the second air chamber, which drives the blades of the gas diffuser to rotate when gas enters the second air chamber.

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