A method and device for replenishing an SF6 gas mixture

Abstract

The application discloses a kind of SF6 mixed gas's method and device of supplementing warehouse, comprising: based on the mixed ratio, pressure and temperature of current SF6 mixed gas in the electrical equipment detected, the rated value of the proportion of SF6 gas in SF6 mixed gas required by electrical equipment and rated pressure, the proportion of SF6 gas in SF6 mixed gas that needs to be supplemented is calculated;If the proportion of SF6 gas that needs to be supplemented is not less than 0 and not more than 1, then SF6 gas in SF6 gas cylinder and other gas in other gas cylinder are output to the first gas storage tank, mixed uniformly, and then supplemented into the electrical equipment;If the proportion of SF6 gas that needs to be supplemented is less than 0, then according to the size relationship between ideal pressure relief pressure and preset pressure threshold, the SF6 mixed gas in the electrical equipment is discharged according to the discharge mode, and then the SF6 mixed gas is supplemented into the electrical equipment.The application can accurately control the gas pressure to be rated pressure after supplementing warehouse, and the mixing ratio meets the requirements.

Description

Technical Field

[0001] This invention relates to the field of SF6 mixed gas replenishment technology, and more particularly to a method and apparatus for replenishing SF6 mixed gas. Background Technology

[0002] Power grid companies are gradually adopting SF6 mixed gas, doped with N2 or CF4, to replace pure SF6 gas as the insulating and arc-quenching medium. During operation, SF6 mixed gas electrical equipment inevitably experiences micro-leakage. Over time, this accumulation leads to a significant pressure drop, reducing insulation and arc-quenching performance, and in severe cases, potentially causing equipment failure and widespread power outages.

[0003] Currently, there is no dedicated replenishment device for electrical equipment using SF6 / CF4 mixed gas. Power grid companies generally use a pressure-dividing replenishment method based on Dalton's law of partial pressure to replenish the two components sequentially. This method has the following problems: 1) The initial SF6 mixture ratio may not meet the standard, or the SF6 mixture ratio may change due to latent faults such as discharge, leakage / seepage. The pressure-dividing replenishment method cannot correct the mixture ratio to the normal range when replenishing according to the rated mixture ratio; 2) Even if the mixture ratio is tested before pressure-dividing replenishment and the ratio is adjusted according to the results, it is still impossible to replenish the mixture ratio to the standard value at the rated pressure if the SF6 gas content is too high (some staff often choose to add more SF6 gas to ensure insulation performance); 3) The two components of gas replenished in stages by the pressure-dividing replenishment method are not completely mixed, which may have a certain impact on insulation and arc-extinguishing performance; 4) The pressure-dividing replenishment method generally only roughly estimates the pressure of the two gases to be replenished, making it difficult to accurately control the pressure after replenishment to near the rated pressure. Summary of the Invention

[0004] This invention provides a method and apparatus for replenishing SF6 mixed gas, in order to solve the problem that existing replenishment methods cannot meet the standards required by electrical equipment, resulting in poor performance of the mixed gas.

[0005] Firstly, a method for replenishing SF6 mixed gas is provided, including:

[0006] Based on the current mixing ratio, pressure, and temperature of the SF6 mixture within the detected electrical equipment, as well as the rated percentage of SF6 gas in the SF6 mixture required by the electrical equipment and the rated pressure of the SF6 mixture, the percentage of SF6 gas in the SF6 mixture that needs to be replenished to the electrical equipment is calculated.

[0007] If the proportion of SF6 gas in the SF6 mixture to be replenished is not less than 0 and not greater than 1, then the SF6 gas in the SF6 storage cylinder and the other gases in the other gas storage cylinders are output to the first storage tank. After the SF6 gas and the other gases are mixed evenly, they are replenished into the electrical equipment until the pressure of the SF6 mixture after replenishment in the electrical equipment is the required rated pressure of the SF6 mixture.

[0008] If the proportion of SF6 gas in the SF6 mixture to be replenished is less than 0, then according to the calculated relationship between the ideal pressure relief pressure and the preset pressure threshold, the SF6 mixture in the electrical equipment is depressurized according to different pressure relief methods, and then the SF6 mixture is replenished into the electrical equipment until the pressure of the SF6 mixture after replenishment in the electrical equipment is the required rated pressure of the SF6 mixture.

[0009] The SF6 mixed gas includes SF6 gas and other gases, wherein the other gases are CF4 or N2 gas.

[0010] Secondly, a replenishment apparatus is provided that applies the replenishment method for SF6 mixed gas as described in the first aspect embodiment.

[0011] Thus, in this embodiment of the invention, replenishment can be performed while the electrical equipment is energized; the pressure of the mixed gas inside the electrical equipment after replenishment can be precisely controlled to the rated pressure, and the mixing ratio of the mixed gas meets the requirements; the degree of uniformity of the replenished mixed gas is high; precise replenishment can be achieved when the proportion of SF6 gas is too high by depressurization, and SF6 gas is adsorbed by an adsorption tower to obtain N2 and CF4 gas with higher purity, which is then refilled, reducing the amount of N2 and CF4 cylinder gas used. Attached Figure Description

[0012] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a flowchart of the SF6 mixed gas replenishment method according to an embodiment of the present invention;

[0014] Figure 2 This is a schematic diagram of the SF6 mixed gas replenishment device according to an embodiment of the present invention. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] This invention discloses a method for replenishing SF6 mixed gas. For example... Figure 1 As shown, the method includes the following steps:

[0017] Step S101: Based on the current mixing ratio, pressure, and temperature of the SF6 mixture in the detected electrical equipment, as well as the rated percentage of SF6 gas in the SF6 mixture required by the electrical equipment and the rated pressure of the SF6 mixture, calculate the percentage of SF6 gas in the SF6 mixture that needs to be replenished to the electrical equipment.

[0018] Specifically, the SF6 mixture includes SF6 gas and other gases. The other gases are CF4 or N2 gas.

[0019] The mixing ratio, pressure, and temperature can be detected using existing equipment such as appropriate detectors and sensors.

[0020] Specifically, the calculation process for this step is as follows:

[0021] 1. Based on the current mixing ratio and pressure of the SF6 mixture, use Dalton's law of partial pressures to calculate the first partial pressure of SF6 gas and the first partial pressure of other gases in the current SF6 mixture at the current temperature.

[0022] Specifically, the equation for Dalton's law of partial pressures is as follows:

[0023]

[0024] Where P1 is the partial pressure of SF6 gas, P2 is the partial pressure of other gases, and P0 is the pressure of the SF6 mixture, in MPa. The mixing ratio of SF6 gas and other gases in the SF6 mixture is denoted as a%:b%.

[0025] During the calculation, the mixing ratio and pressure of the detected SF6 mixed gas are substituted into a%, b%, and P0 in equation (1) to obtain P1 as the first partial pressure of SF6 gas and P2 as the first partial pressure of other gases.

[0026] 2. Based on the first partial pressure of SF6 gas, the Beattie-Bridgman gas law is used to calculate the first density of SF6 gas in the current SF6 mixture at the current temperature.

[0027] Since SF6 is a large molecule, the ideal gas law does not apply. Therefore, the Beattie-Bridgman gas law is used for calculation. The specific gas law is as follows:

[0028]

[0029] Where ρ1 is the density of SF6 gas, in kg / m³. 3 K1 is the thermodynamic temperature of the SF6 mixture, with a value of T0+273, in K; T0 is the current temperature of the SF6 mixture.

[0030] Substitute the first partial pressure of SF6 gas obtained from the above calculation into P1, and the current temperature of the SF6 mixed gas T0+273 into K1, and solve equation (2) simultaneously to obtain ρ1 as the first density of SF6 gas.

[0031] 3. Based on the first density of SF6 gas, the Beattie-Bridgman gas law is used to calculate the second partial pressure of SF6 gas of equal density in the current SF6 mixture at 20℃.

[0032] Specifically, substituting the previously calculated ρ1 and K1 = 273 + 20 into equation (2), the calculated P1 is taken as the second partial pressure of SF6 gas at 20℃ under isodense conditions. The second partial pressure of SF6 gas is denoted as P. 1,t .

[0033] 4. Based on the first partial pressure of other gases and the current temperature of the SF6 mixture, calculate the second partial pressure of other gases of equal density in the current SF6 mixture at 20℃.

[0034] Specifically, the second partial pressure P of other gases 2,t The calculation formula is as follows:

[0035]

[0036] Where P2 is the first partial pressure of other gases.

[0037] 5. Calculate the sum of the second partial pressure of SF6 gas and the second partial pressure of other gases to obtain the pressure of the current SF6 mixture at 20℃.

[0038] With P t This represents the pressure of the SF6 mixture at 20℃, i.e.:

[0039] P t =P 1,t +P 2,t (4)

[0040] 6. Calculate the percentage of SF6 gas in the SF6 mixture that needs to be added to the electrical equipment according to the mixing ratio calculation formula.

[0041] Specifically, the formula for calculating the mixing ratio is as follows:

[0042]

[0043] Among them, C 1,S C represents the percentage of SF6 gas in the SF6 mixture that needs to be supplemented. 1,r and C 1,t P represents the required nominal percentage of SF6 gas in the SF6 mixture and the current percentage of SF6 gas in the SF6 mixture, respectively. r This refers to the required rated pressure of the SF6 mixture. That is, C. 1,t =a%.

[0044] C was calculated 1,S Then, according to C 1,S Depending on the differences, subsequent replenishment will be carried out through different replenishment methods in steps S102 and S103.

[0045] Step S102: If the proportion of SF6 gas in the SF6 mixture to be replenished is not less than 0 and not greater than 1, then output the SF6 gas in the SF6 storage cylinder and the other gases in the other gas storage cylinders to the first storage tank, so that the SF6 gas and the other gases are mixed evenly, and then replenish the electrical equipment until the pressure of the SF6 mixture after replenishment in the electrical equipment is the required rated pressure of the SF6 mixture.

[0046] In 0≤C 1,S If the ratio is ≤1, you can directly replenish your position according to the mixing ratio.

[0047] Specifically, the process of outputting SF6 gas from the SF6 storage cylinder and other gases from other gas storage cylinders to the first storage tank can be configured such that the flow rate and pressure output from the SF6 storage cylinder are set as a first flow rate and a first pressure, and the flow rate and pressure output from the other gas storage cylinders are set as a second flow rate and a first pressure, respectively.

[0048] It should be understood that the first pressure can be controlled by the pressure reducing valves installed at the outlets of the SF6 gas cylinder and other gas cylinders, and the first flow rate can be controlled by the flow controllers installed at the outlets of the SF6 gas cylinder and other gas cylinders.

[0049] In addition, during the process of replenishing the mixed gas in the first gas storage tank to the electrical equipment, a compressor can be installed on the pipeline between the two to increase the pressure.

[0050] The first flow rate can be set according to the actual situation. For example, the first flow rate Q1 can be set to 100 ml / min at 20℃ and 0.1 MPa.

[0051] Specifically, the second flow rate Q2 can be determined based on C. 1,S The formula for calculating the second flow rate Q2 is as follows:

[0052]

[0053] It should be understood that the second flow rate is also the flow rate under the conditions of 20℃ and 0.1MPa.

[0054] Both the first and second pressures can be set according to the actual situation. For example, the first pressure is 0.3 MPa and the second pressure is 3 MPa.

[0055] Step S103: If the proportion of SF6 gas in the SF6 mixture to be replenished is less than 0, then according to the calculated relationship between the ideal pressure relief pressure and the preset pressure threshold, the SF6 mixture in the electrical equipment is depressurized according to different pressure relief methods, and then the SF6 mixture is replenished into the electrical equipment until the pressure of the SF6 mixture after replenishment in the electrical equipment is the required rated pressure of the SF6 mixture.

[0056] In C 1,S When the pressure is less than 0, direct replenishment will not achieve the required mixing ratio when the pressure reaches the rated level. In this case, the pressure must be released before replenishment. It should be understood that since SF6 gas is generally overcharged on-site, C will not occur. 1,S The case where the value is greater than 1.

[0057] Specifically, the ideal pressure relief pressure P t,S The calculation formula is as follows:

[0058]

[0059] Because this embodiment of the invention can replenish the power supply to the electrical equipment without interrupting power, and the pressure of the electrical equipment during operation cannot be lower than the alarm pressure, which is generally P. r -0.05, based on this, a preset pressure threshold can be set slightly larger than the alarm pressure. For example, in this embodiment of the invention, a preset pressure threshold P is set. e For P r -0.04.

[0060] Specifically, according to P t,S With P e The size relationship, this step includes the following two cases:

[0061] I. First case P t,S ≥P e :

[0062] 1. If the ideal pressure relief is not less than the preset pressure threshold, the SF6 mixed gas in the electrical equipment is extracted until the current pressure of the SF6 mixed gas in the electrical equipment is the preset pressure relief, and at least part of the SF6 gas in the extracted SF6 mixed gas is adsorbed to obtain the remaining SF6 mixed gas and stored in the second gas storage tank.

[0063] The preset pressure relief is denoted as P. t,D This can be set based on experience. Since the second gas storage tank contains a small amount of SF6 gas, the ideal pressure relief is calculated based on the compensation gas being pure N2 / CF4. Therefore, further pressure relief is required based on the ideal pressure relief. In this embodiment of the invention, P... t,D =P t,S -0.005.

[0064] The adsorption operation can be achieved by setting up an adsorption tower. It should be understood that the remaining SF6 mixture obtained after adsorption is mostly composed of other gases, namely N2 or CF4 (with a purity of about 95%).

[0065] 2. Replenish the electrical equipment with the remaining SF6 mixture from the second gas storage tank.

[0066] 3. Initially, SF6 gas from the SF6 storage cylinder and other gases from other gas storage cylinders are discharged into the first storage tank to ensure uniform mixing. Then, the mixture is replenished into the electrical equipment. The total percentage of SF6 gas in the replenished SF6 storage cylinder, the replenished other gases in the other gas storage cylinder, and the remaining SF6 mixture in the second storage tank is equal to the percentage of SF6 gas in the SF6 mixture that needs to be replenished into the electrical equipment.

[0067] Specifically, in the process of initially outputting SF6 gas from the SF6 storage cylinder and other gases from other gas storage cylinders into the first storage tank, the flow rate and duration of the output from the SF6 storage cylinder are set as the third flow rate and the second time, and the flow rate and duration of the output from the other gas storage cylinders are set as the fourth flow rate and the first time, respectively.

[0068] The third flow rate generally adopts the first flow rate mentioned above.

[0069] The fourth flow rate can be calculated according to equations (5) and (6). At this time, since the current pressure of the SF6 mixture in the electrical equipment is the preset pressure relief pressure P... t,D Therefore, C needs to be recalculated following the steps described above. 1,S Then, the fourth flow rate is calculated using equations (5) and (6).

[0070] Specifically, the formula for calculating the first time step t1 is as follows:

[0071]

[0072] Specifically, the formula for calculating the second time t2 is as follows:

[0073]

[0074] Where Q3 and Q4 are the third and fourth flow rates, respectively; V1 and V2 are the first volume of SF6 gas and the second volume of other gases in the remaining SF6 mixture at 20℃ and 0.1MPa, respectively; a1% and b1% are the proportions of SF6 gas and other gases in the remaining SF6 mixture in the second storage tank, respectively; ρ g1 and ρ f1 The two densities are the second density of SF6 gas in the remaining SF6 mixture at the given temperature and the third density of SF6 gas in the remaining SF6 mixture at 20°C and 0.1 MPa, respectively. V is the volume of the second gas storage tank. T0 is the temperature of the remaining SF6 mixture, where T0 is the temperature of the remaining SF6 mixture.

[0075] Among them, based on the mixing ratio and pressure of the remaining SF6 mixture in the detected second gas storage tank, Dalton's law of partial pressures is used to calculate the second partial pressure of SF6 gas and the second partial pressure of other gases in the remaining SF6 mixture at the temperature.

[0076] Specifically, by substituting the measured mixing ratio and pressure of the remaining SF6 mixture into a%, b%, and P0 in equation (1), we can obtain P1 and P2 as the second partial pressures of the SF6 gas, respectively. S Second partial pressure of other gases

[0077] The second density of SF6 gas is calculated based on the second partial pressure of SF6 gas using the Beattie-Bridgman gas equation of state.

[0078] Specifically, the second partial pressure P1 of SF6 gas obtained from the aforementioned calculation... S Substituting P1, the temperature of the remaining SF6 mixture T0+273 is measured and then substituted into K1. Solving equation (2) simultaneously yields ρ1 as the second density ρ of the SF6 gas. g1 It should be understood that the temperature of the remaining SF6 mixture is the same as the current temperature of the SF6 mixture inside the electrical equipment.

[0079] The third density of SF6 gas was calculated using the Beattie-Bridgman gas law.

[0080] Specifically, the third density is the density under conditions of 20℃ and 0.1MPa. Therefore, substituting 0.1 into P1 and 20+273 into K1, and solving equation (2) simultaneously, we obtain ρ1 as the third density ρ of SF6 gas. f1 .

[0081] 4. Again, output the SF6 gas from the SF6 storage cylinder and the other gases from the other gas storage cylinders into the first storage tank, so that the SF6 gas and the other gases are mixed evenly, and then replenish them into the electrical equipment until the pressure of the SF6 mixed gas after replenishment into the electrical equipment reaches the required rated pressure of the SF6 mixed gas.

[0082] This step is the same as step S102, and the relevant flow rate and pressure are determined in the same way as in step S102, so it will not be repeated here.

[0083] II. Second case P t,S Less than P e :

[0084] 1. If the ideal pressure relief is less than the preset pressure threshold, the SF6 mixed gas in the electrical equipment will be extracted until the current pressure of the SF6 mixed gas in the electrical equipment is the preset pressure threshold. At least part of the SF6 gas in the extracted SF6 mixed gas will be adsorbed to obtain the remaining SF6 mixed gas and store it in the second gas storage tank.

[0085] This step is the same as the previous one, except that the pressure released is different, so it will not be described again here.

[0086] 2. After replenishing the electrical equipment with the remaining SF6 mixture from the second gas storage tank, replenish the electrical equipment with the other gases from the other gas storage cylinders until the pressure of the replenished SF6 mixture in the electrical equipment reaches the required rated pressure of the SF6 mixture.

[0087] Specifically, the pressure of the SF6 mixture in the electrical equipment after replenishment can be measured in real time to determine whether the required rated pressure of the SF6 mixture has been achieved.

[0088] 3. Return to the step of calculating the proportion of SF6 gas in the SF6 mixture that needs to be replenished to the electrical equipment, and repeat all steps until the ideal pressure relief is not less than the preset pressure threshold, and the pressure of the SF6 mixture after replenishment to the electrical equipment is the required rated pressure of the SF6 mixture.

[0089] That is, the mixing ratio, pressure and temperature of the SF6 mixture in the electrical equipment are re-detected, and the corresponding processing is performed according to the method of the present invention. This process is repeated until the ideal pressure relief is not less than the preset pressure threshold, and the pressure of the SF6 mixture after replenishment of the electrical equipment is the required rated pressure of the SF6 mixture.

[0090] The above method can be used to replenish the SF6 mixture in electrical equipment under different circumstances.

[0091] Furthermore, this invention also provides a replenishment device that applies the SF6 mixed gas replenishment method described in the above embodiments.

[0092] Specifically, the replenishment device includes: SF6 storage cylinder 1, other gas storage cylinder 2, first gas storage tank 8, second gas storage tank 13, buffer tank 10, adsorption tower 27 and replenishment port 25.

[0093] SF6 storage cylinder 1 and other gas storage cylinders 2 are all connected to a merging pipeline. The merging pipeline, the first storage tank 8, the buffer tank 10, and the replenishment port 25 are connected in series via pipelines. The second storage tank 13, the adsorption tower 27, and the replenishment port 25 are connected in series via pipelines.

[0094] More specifically, a first pressure-reducing valve 3 and a first mass flow controller 5 are sequentially installed on the pipeline connecting SF6 storage cylinder 1 to the merging pipeline. A second pressure-reducing valve 4 and a second mass flow controller 6 are sequentially installed on the pipeline connecting other gas storage cylinders 2 to the merging pipeline. A first solenoid valve 7 is installed on the merging pipeline. The first pressure-reducing valve 3 and the first mass flow controller 5 are used to control the pressure and flow rate of the gas output from SF6 storage cylinder 1, the second pressure-reducing valve 4 and the second mass flow controller 6 are used to control the pressure and flow rate of the gas output from other gas storage cylinders 2, and the first solenoid valve 7 is used to control the on / off state of the pipeline.

[0095] The first gas storage tank 8 is connected to the first compressor 9 via a pipeline, forming a closed-loop circuit. The first compressor 9 is used to switch the pipeline on and off, and after starting, it can mix the gas in the first gas storage tank 8.

[0096] The second gas storage tank 13 is equipped with a first pressure sensor 12, which is used to detect the pressure of the remaining SF6 mixed gas in the second gas storage tank 13.

[0097] A second solenoid valve 15 and a second compressor 18 are sequentially installed on the first pipeline connecting the buffer tank 10 and the replenishment port 25, both used to open and close the pipeline. The second compressor 18 can also control the output pressure.

[0098] A second pressure sensor 23 and a temperature sensor 24 are installed near the replenishment port 25 of the first pipeline to detect the pressure and temperature of the SF6 mixture gas inside the electrical equipment, respectively.

[0099] A third solenoid valve 11, a mixture ratio detector 14, and a needle valve 16 are sequentially installed on the second pipeline connecting the buffer tank 10 and the replenishment port 25. The third solenoid valve 11 is used to control the on / off state of the pipeline. The mixture ratio detector 14 is used to detect the current mixture ratio of SF6 gas in the electrical equipment and the remaining mixture ratio of SF6 gas in the second gas storage tank 13. The needle valve 16 is used to control the gas flow rate. The second pipeline connects the first pipeline between the second compressor 18 and the replenishment port 25.

[0100] A fourth solenoid valve 26 is installed on the pipeline connecting the adsorption tower 27 and the replenishment port 25 to control the on / off state of the pipeline. A fifth solenoid valve 28 is installed on the third pipeline connecting the second gas storage tank 13 and the adsorption tower 27 to control the on / off state of the pipeline.

[0101] The second gas storage tank 13 is connected to the mixing ratio detector 14 via the fourth pipeline. The sixth solenoid valve 19 and the seventh solenoid valve 17 are installed sequentially on the fourth pipeline. The fourth pipeline is connected to the first pipeline between the second solenoid valve 15 and the second compressor 18, and is also connected to the third pipeline.

[0102] The fourth pipe connects to the vacuum exhaust port 22. A vacuum gauge 20 and a vacuum pump 21 are installed on the fourth pipe near the vacuum exhaust port 22. After the vacuum pump 21 is started, it can evacuate the SF6 mixture replenishment device. The vacuum gauge 20 is used to detect the vacuum level of the device.

[0103] The method of this invention can be applied to this device. Specifically, the usage process of this device is as follows:

[0104] 1. First, evacuate the inside of the replenishment device to eliminate interference from residual gas. The specific operation is as follows:

[0105] Open the second solenoid valve 15 and the sixth solenoid valve 19, start the vacuum pump 21, and let the gas in the replenishment device be discharged from the vacuum exhaust port 22. Evacuate until the reading of the vacuum gauge 20 is 133 Pa. Then close the vacuum pump 21 and the second solenoid valve 15 and the sixth solenoid valve 19. The vacuuming is then complete.

[0106] 2. The specific process for testing the mixing ratio within electrical equipment is as follows:

[0107] Open the third solenoid valve 11, start the mixing ratio detector 14, adjust the needle valve 16 to make the detection flow rate 300ml / min, and the SF6 mixed gas in the electrical equipment enters the first gas storage tank 10 (the pressure is 0 after vacuuming) from the replenishment port 25 under the action of pressure difference. After 3 minutes, the mixing ratio detector 14 automatically records the mixing ratio detection result as a%:b.

[0108] 3. The second pressure sensor 23 and temperature sensor 24 respectively detect the pressure P0 and temperature T0 of the current SF6 mixed gas in the electrical equipment, and calculate the proportion of SF6 gas in the SF6 mixed gas that needs to be replenished to the electrical equipment based on the mixing ratio a%:b%, pressure P0 and temperature T0.

[0109] The calculation process is as described above and will not be repeated here.

[0110] 4. According to different C 1,S Choose different methods to add to your position.

[0111] (1) If 0 ≤ C 1,S If the value is ≤1, then the aforementioned method should be used to add to the position, which will not be repeated here. An example illustrating the specific steps is as follows:

[0112] The output pressures of the first pressure reducing valve 3 and the second pressure reducing valve 4 are set to 0.3 MPa, the output flow rate Q1 of the first mass flow controller 5 is set to 100 ml / min (20℃, 0.1 MPa), and the output flow rate Q2 of the second mass flow controller 6 is set to 20℃, 0.1 MPa. The specific values ​​can be obtained through the aforementioned calculations and will not be repeated here.

[0113] Opening the first solenoid valve 7 allows the two component gases to enter the first gas storage tank 8. Starting the first compressor 9 promotes the circulation of the two gases in the first gas storage tank 8 through an external pipeline, accelerating mixing. Under pressure, the mixed gas enters the buffer tank 10. Opening the second solenoid valve 15 and starting the second compressor 18 pressurizes the mixed gas to 3.0 MPa and replenishes it to the electrical equipment. When the second pressure sensor 23 detects that the current pressure of the mixed gas in the conductive gas equipment is at the rated pressure, replenishment stops, and all modules and solenoid valves in the replenishment device are closed.

[0114] (2) If C 1,S If the value is ≤0, then add to the position using the method described above, which will not be repeated here. An example illustrating the specific steps is as follows:

[0115] ①If P t,S ≥P r If the pressure is -0.04, the pressure in the air chamber will be directly released to P. t,S -0.005.

[0116] Specifically, first, the fourth solenoid valve 26 and the fifth solenoid valve 28 are opened. Under the action of the pressure difference, the mixed gas in the electrical equipment enters the adsorption tower 27 (which contains an adsorbent that only adsorbs SF6 gas). The gas after adsorption is mostly CF4 gas (with a purity of about 90%), and enters the second gas storage tank 13. When the pressure is released to P... t,S When the pressure reaches -0.005, the fourth solenoid valve 26 and the fifth solenoid valve 28 are closed. At this time, the reading of the first pressure sensor 12 is P.g .

[0117] Open the third solenoid valve 11, the seventh solenoid valve 17, and the sixth solenoid valve 19, start the mixture ratio detector 14, and adjust the needle valve 16 to make the detection flow rate 300 ml / min. The gas in the second gas storage tank 13 enters the buffer tank 10 under the action of pressure difference (the pressure is 0 after vacuuming). After 3 minutes, the mixture ratio detector 14 automatically records the mixture ratio detection result as a1%:b1%. After the detection is completed, close the above solenoid valves and the mixture ratio detector 14.

[0118] Then, the output times t1 and t2 of the first mass flow controller 5 and the second mass flow controller 6 at flow rates Q3 and Q4, respectively, are calculated according to the aforementioned method.

[0119] Open the sixth solenoid valve 19, start the second compressor 18 to charge the electrical equipment with gas from the second gas storage tank 13, then close the sixth solenoid valve 19, open the first solenoid valve 7 and the second solenoid valve 15, open the first mass flow controller 5 to output Q3 for time t2 and then close it, and simultaneously open the second mass flow controller 6 to output Q4 for time t1 and then close it. This ensures that the SF6 gas ratio of the gas output from the two mass flow controllers plus the gas in the second gas storage tank 13 meets the C standard. 1,S Then follow the steps 0≤C 1,S Replenish the pressure to the rated pressure using the method in ≤1.

[0120] ②If P t,S <P r If the pressure is -0.04, directly depressurizing to this pressure may cause the equipment to alarm, so multiple depressurizations are required.

[0121] First, depressurize to P. r -0.04, then open the sixth solenoid valve 19, start the second compressor 18 to fill the electrical equipment with gas from the second gas tank 13, and then close the sixth solenoid valve 19. Then open the second solenoid valve 6 to replenish pure N2 or CF4 gas to the rated pressure P. r Then, based on the gas mixing ratio a2%:b2% in the tested electrical equipment, the proportion of SF6 gas in the gas mixture to be supplemented is calculated. Continue using the aforementioned method, based on different C 1,S The process of determining whether to release pressure and how to replenish the position is not elaborated here.

[0122] In summary, the embodiments of the present invention can replenish the gas cylinder while the electrical equipment is energized; can precisely control the pressure of the mixed gas inside the electrical equipment after replenishment to the rated pressure, and the mixing ratio of the mixed gas meets the requirements; the mixed gas after replenishment has a high degree of homogeneity; can achieve precise replenishment when the proportion of SF6 gas is too high by depressurization, and can obtain high-purity N2 and CF4 gas by adsorbing SF6 gas through an adsorption tower, and then refill it, thereby reducing the amount of N2 and CF4 cylinder gas used.

[0123] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for replenishing SF6 mixed gas, characterized in that, include: Based on the current mixing ratio, pressure, and temperature of the SF6 mixture within the detected electrical equipment, as well as the rated percentage of SF6 gas in the SF6 mixture required by the electrical equipment and the rated pressure of the SF6 mixture, the percentage of SF6 gas in the SF6 mixture that needs to be replenished to the electrical equipment is calculated. If the proportion of SF6 gas in the SF6 mixture to be replenished is not less than 0 and not greater than 1, then the SF6 gas in the SF6 storage cylinder and the other gases in the other gas storage cylinders are output to the first storage tank. After the SF6 gas and the other gases are mixed evenly, they are replenished into the electrical equipment until the pressure of the SF6 mixture after replenishment in the electrical equipment is the required rated pressure of the SF6 mixture. If the proportion of SF6 gas in the SF6 mixture to be replenished is less than 0, then according to the calculated relationship between the ideal pressure relief pressure and the preset pressure threshold, the SF6 mixture in the electrical equipment is depressurized according to different pressure relief methods, and then the SF6 mixture is replenished into the electrical equipment until the pressure of the SF6 mixture after replenishment in the electrical equipment is the required rated pressure of the SF6 mixture. The SF6 mixed gas includes SF6 gas and other gases, wherein the other gases are CF4 or N2 gas. The step of depressurizing the SF6 mixture in the electrical equipment according to different depressurization methods, and then replenishing the SF6 mixture into the electrical equipment, includes: If the ideal pressure relief is not less than the preset pressure threshold, the SF6 mixed gas in the electrical equipment is extracted until the current pressure of the SF6 mixed gas in the electrical equipment is the preset pressure relief, and at least part of the SF6 gas in the extracted SF6 mixed gas is adsorbed to obtain the remaining SF6 mixed gas and stored in the second gas storage tank. The remaining SF6 mixture in the second gas storage tank is added to the electrical equipment; The SF6 gas in the SF6 storage cylinder and other gases in other gas storage cylinders are initially output to the first storage tank. After the SF6 gas and other gases are mixed evenly, they are replenished into the electrical equipment. The total percentage of all SF6 gas in the remaining SF6 mixture in the second storage tank is the percentage of SF6 gas in the SF6 mixture that needs to be replenished into the electrical equipment. The SF6 gas in the SF6 storage cylinder and other gases in the other gas storage cylinder are output to the first storage tank again. After the SF6 gas and other gases are mixed evenly, they are replenished into the electrical equipment until the pressure of the SF6 mixed gas after replenishment in the electrical equipment is the required rated pressure of the SF6 mixed gas. Wherein, the ideal pressure relief P t,S The calculation formulas include: ； in, C 1,S The percentage of SF6 gas in the SF6 mixture that needs to be replenished. C 1,r and C 1,t These refer to the specified nominal percentage of SF6 gas in the required SF6 mixture and the current percentage of SF6 gas in the SF6 mixture, respectively. P r The rated pressure of the required SF6 mixture; The step of depressurizing the SF6 mixture in the electrical equipment according to different depressurization methods, and then replenishing the SF6 mixture into the electrical equipment, includes: If the ideal pressure relief is less than the preset pressure threshold, the SF6 mixed gas in the electrical equipment is extracted until the current pressure of the SF6 mixed gas in the electrical equipment is the preset pressure threshold, and at least part of the SF6 gas in the extracted SF6 mixed gas is adsorbed to obtain the remaining SF6 mixed gas and stored in the second gas storage tank. After replenishing the electrical equipment with the remaining SF6 mixed gas in the second gas storage tank, other gases from other gas storage cylinders are then added to the electrical equipment until the pressure of the replenished SF6 mixed gas in the electrical equipment reaches the required rated pressure of the SF6 mixed gas. Return to the step of calculating the percentage of SF6 gas in the SF6 mixture that needs to be replenished to the electrical equipment, and repeat all steps until the ideal pressure relief is not less than the preset pressure threshold, and the pressure of the SF6 mixture after replenishment to the electrical equipment is the required rated pressure of the SF6 mixture.

2. The method for replenishing SF6 mixed gas according to claim 1, characterized in that, The step of calculating the percentage of SF6 gas in the SF6 mixture that needs to be replenished for the electrical equipment includes: Based on the current mixing ratio and pressure of the SF6 mixture, Dalton's law of partial pressures is used to calculate the first partial pressure of SF6 gas and the first partial pressure of other gases in the current SF6 mixture at the current temperature. Based on the first partial pressure of SF6 gas, the first density of SF6 gas in the current SF6 mixture at the current temperature is calculated using the Beattie-Bridgman gas law. Based on the first density of the SF6 gas, the Beattie-Bridgman gas law is used to calculate the second partial pressure of SF6 gas of equal density in the current SF6 mixture at 20°C. Based on the first partial pressure of the other gases and the temperature of the current SF6 mixture, calculate the second partial pressure of the other gases at the same density in the current SF6 mixture at 20°C, wherein the second partial pressure of the other gases... P 2,t The formula for calculation is: , P 2 represents the first partial pressure of the other gases. T 0 represents the current temperature of the SF6 mixture; The pressure of the current SF6 mixture at 20°C is obtained by calculating the sum of the second partial pressure of the SF6 gas and the second partial pressure of the other gases. The proportion of SF6 gas in the SF6 mixture that needs to be replenished for the electrical equipment is calculated according to the mixing ratio calculation formula. The formula for calculating the mixing ratio includes: ； in, C 1,S The percentage of SF6 gas in the SF6 mixture that needs to be replenished. C 1,r and C 1,t These refer to the specified nominal percentage of SF6 gas in the required SF6 mixture and the current percentage of SF6 gas in the SF6 mixture, respectively. P r The rated pressure of the required SF6 mixture.

3. The method for replenishing SF6 mixed gas according to claim 1, characterized in that, The process of outputting SF6 gas from the SF6 storage cylinder and other gases from other gas storage cylinders to the first storage tank is described in which the flow rate and pressure output from the SF6 storage cylinder are set as the first flow rate and the first pressure, respectively, and the flow rate and pressure output from the other gas storage cylinders are set as the second flow rate and the first pressure, respectively. Among them, the second flow rate Q The formula for calculating 2 includes: ； in, C 1,S The percentage of SF6 gas in the SF6 mixture that needs to be supplemented.

4. The method for replenishing SF6 mixed gas according to claim 1, characterized in that: The process of initially outputting SF6 gas from the SF6 storage cylinder and other gases from other gas storage cylinders to the first storage tank is described in which the flow rate and duration of the output from the SF6 storage cylinder are set as the third flow rate and the second time, and the flow rate and duration of the output from the other gas storage cylinders are set as the fourth flow rate and the first time, respectively. Among them, the first time t The formula for calculating 1 includes: ； Among them, the second time t The formula for calculating 2 includes: ； in, Q 3 and Q 4 represents the third flow rate and the fourth flow rate, respectively. V 1 and V 2 represents the first volume of SF6 gas and the second volume of other gases in the remaining SF6 mixture at 20℃ and 0.1MPa, respectively. a 1% and b 1% represents the proportion of SF6 gas and the proportion of other gases in the remaining SF6 mixture in the second gas storage tank, respectively. ρ g1 and ρ f1 The two values ​​are the second density of SF6 gas in the remaining SF6 mixture at a given temperature and the third density of SF6 gas in the remaining SF6 mixture at 20°C and 0.1 MPa, respectively. V Let V be the volume of the second gas storage tank. The second partial pressure of other gases in the remaining SF6 mixture at the temperature of the remaining SF6 mixture. T 0 represents the temperature of the remaining SF6 mixture. Among them, based on the mixing ratio and pressure of the remaining SF6 mixed gas in the detected second gas storage tank, Dalton's law of partial pressures is used to calculate the second partial pressure of SF6 gas and the second partial pressure of other gases in the remaining SF6 mixed gas at the temperature. The second density of SF6 gas is calculated based on the second partial pressure of the SF6 gas using the Beattie-Bridgman gas equation of state. The third density of the SF6 gas was calculated using the Beattie-Bridgman gas law.

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