GIS device non-power-off mixed gas replacement device and method

Abstract

The application discloses a GIS device non-power-off mixed gas replacement device, which comprises a recovery pipeline connected with a gas chamber of a GIS device and a mixing container, and is used for recycling part of SF6 gas in the gas chamber into the mixing container; a gas supplement pipeline connected with the mixing container and a nitrogen gas source, and is used for supplementing nitrogen gas into the mixing container and configuring SF6 and nitrogen gas in the mixing container into mixed gas with a set proportion. In the application, the GIS device mixed gas replacement is realized in the embodiment, the gas chamber is extracted to the lower limit of pressure, the gas chamber is kept at a certain pressure at all times, the pressure of adjacent gas chambers does not need to be reduced by half, the deformation and gas leakage of the connection of the gas chamber caused by excessively high pressure difference are avoided, the replacement process does not need to be powered off, the replacement efficiency is improved; meanwhile, the gas filled into the gas chamber each time is completely mixed, and the gas is repeatedly circulated and flowed in the gas chamber through multiple cycles, so that the mixed gas in the gas chamber is mixed, and the mixed gas in the gas chamber is in a mixed state when the replacement is completed.

Description

Technical Field

[0001] This invention relates to the field of gas replacement technology, and more specifically to a device and method for uninterrupted power-off mixed gas replacement of GIS equipment. Background Technology

[0002] SF6 gas has a strong greenhouse effect, with a global warming potential 23,500 times that of carbon dioxide, and it can persist in the atmosphere for approximately 3,200 years. It is one of the six greenhouse gases globally recognized as requiring regulated control. Statistics show that 70% of SF6 gas in China is used as an insulating and arc-quenching gas in high-voltage GIS equipment in the power industry.

[0003] The "SF6 / N2 Mixed Gas GIS Equipment Application Guide" specifies the workflow for mixed gas retrofitting. First, the pressure of the adjacent gas chambers of the retrofitted GIS equipment needs to be reduced by half. Then, the SF6 gas in the retrofitted gas chamber is recovered and evacuated. After that, a 30% SF6:70% N2 mixed gas is introduced into the retrofitted gas chamber to the rated pressure. Finally, the mixture is left to stand for 24 hours and the mixing ratio of the mixed gas is retested. Only after passing the test can the power be switched on. The retrofitting process takes about one week.

[0004] The above-mentioned modification process has the following defects: (1) The replacement process requires a power outage, which generally takes 4-6 days. This will reduce the power supply capacity of the power grid, especially during peak electricity consumption periods or in areas supplied to important users. Power outages may cause serious social and economic losses. (2) The modification process is complicated. First, special tools and equipment are needed to reduce the pressure of the adjacent gas chamber by half. Then, the SF6 gas in the modified gas chamber is recovered and vacuumed (the pressure is maintained for at least 5 hours, and the next step is carried out after it is qualified). Then, the mixed gas is prepared by the mixed gas filling device and the gas is filled. The operation steps are complicated and the efficiency is low. During the operation, the pipes and joints need to be disassembled and reinstalled many times, which increases the risk of equipment leakage. (3) The lack of a gas mixing device means that the SF6 / N2 mixed gas can only be mixed in the equipment in advance or rely on natural diffusion after being filled, which is time-consuming and inefficient.

[0005] The aforementioned retrofit process not only requires power outages and shutdowns of the GIS equipment, but also involves numerous steps and necessitates the use of multiple large pieces of equipment, including SF6 gas recovery units, vacuum pumping units, and mixed gas filling units. The transportation, installation, and commissioning of this equipment are complex and time-consuming, placing high demands on the on-site working environment and the technical skills of the operators. This not only increases transportation costs but also risks delays due to road conditions and weather, further increasing retrofit costs and safety risks. Therefore, the aforementioned mixed gas GIS equipment retrofit process, to some extent, reduces the enthusiasm of power systems to promote mixed gas equipment.

[0006] Patent document CN118896244A discloses a method and system for modifying high-voltage switchgear without power interruption using mixed gas. Under operating voltage conditions, when the gas chamber of the high-voltage switchgear operates at a standard gas pressure, a preset proportion of pure SF6 gas is recovered from the high-voltage switchgear until the preset proportion of pure SF6 gas is completely recovered. After the preset proportion of pure SF6 gas is recovered, N2 gas of the same volume as the recovered pure SF6 gas is introduced into the high-voltage switchgear, and the gas chamber of the high-voltage switchgear returns to the standard operating gas pressure. The uniformity of the mixing of SF6 gas and N2 gas in the high-voltage equipment is tested. When the uniformity of the mixing of SF6 gas and N2 gas reaches a preset standard, the modification of the high-voltage switchgear is completed.

[0007] However, this method lacks circulation; it directly extracts SF6 to 30% in one go. While ideally the equipment can still operate normally with 30% SF6, in reality, extracting SF6 to 30% in one go would cause a power outage. This solution is based on the design margin of the GIS equipment and the experimental proof that SF6 gas pressure reduced to "30%" still maintains "safe" insulation performance. It directly extracts SF6 gas from the GIS equipment's gas chamber to 30% pressure, then adds N2 and mixes it. However, to build a safe and highly reliable power grid, the GIS equipment must maintain sufficient insulation margin. The method described in this patent is only theoretically feasible and violates the strict requirement that the gas pressure of operating electrical equipment must be higher than the alarm pressure (generally 0.05 MPa lower than the rated pressure, which is generally 0.5 MPa-0.8 MPa). Furthermore, recovering to 30% gas pressure would result in an excessive pressure difference with adjacent gas chambers, potentially damaging the insulation at the chamber connection. In field operations, a recovery device is still needed to reduce the pressure of adjacent gas chambers by half. Summary of the Invention

[0008] The technical problem to be solved by this invention is how to replace pure SF6 gas in the gas chamber with a 30% SF6:70% N2 mixture without interrupting power supply, so that the mixture in the gas chamber is in a homogeneous state when the replacement is completed.

[0009] This invention solves the above-mentioned technical problems through the following technical means: a GIS equipment uninterrupted mixed gas replacement device, comprising: The recovery pipeline is connected to the gas chamber and mixing container of the GIS equipment and is used to recover part of the SF6 gas in the gas chamber into the mixing container. The gas supply line is connected to the mixing container and the nitrogen source. It is used to supply nitrogen into the mixing container and to mix the SF6 and nitrogen in the mixing container into a set ratio of gas mixture. The circulation line, connected to the recovery line and the mixing container, is used to mix the gas in the mixing container. The transfer pipeline, connected to the transfer container and the refill pipeline, is used to transfer the mixed gas in the mixing container to the transfer container through the transfer pipeline. The refill line is connected to the end of the recovery line near the gas chamber and the transfer container, and is used to refill the mixed gas in the transfer container back into the gas chamber. Part of the SF6 gas in the gas chamber is recovered into the mixing container until the lower limit of the gas chamber pressure is reached. Nitrogen is introduced into the mixing container to prepare a mixed gas in a set ratio. The mixed gas is mixed evenly and used as a charging gas source and transferred to the transfer container. The mixed gas in the transfer container is then charged into the gas chamber. The process of repeated charging and recovery is repeated to reduce the proportion of SF6 gas in the gas chamber to the set pressure. The lower limit of the gas chamber pressure is the gas chamber alarm pressure or the equivalent insulation strength pressure under the current gas chamber mixing ratio. The pressure is repeatedly charged to the set pressure, which is the rated pressure after the gas mixing modification or the upper limit of the gas chamber pressure.

[0010] As a preferred technical solution, the effective volume of the gas chamber is calculated by the SF6 gas pressure and temperature in the pre- and post-recovery gas chambers, the recovered gas flow rate, and the SF6 percentage in the recovered gas. The volume of the recovered gas is calculated based on the gas flow rate during the recovery process. The volume of supplemented nitrogen is calculated based on the effective volume of the gas chamber and the volume of the recovered gas. The partial pressure of nitrogen in the mixing container at a set ratio is calculated based on the supplemented nitrogen volume. Gas replenishment is stopped when the pressure in the mixing container reaches the partial pressure of nitrogen in the mixing container at the set ratio.

[0011] As a preferred technical solution, the volume of SF6 in the recovered gas is calculated using equation (2). : (2) In the formula, This represents the volume of SF6 standard condition gas recovered during the nth cycle, in cubic meters (m³). 3 , This is the nth iteration, with units of m. 3 / h, The percentage of SF6 in the gas recovered during the nth cycle. This represents the start time of recycling during the nth iteration. This represents the end time of recycling during the nth iteration. , The units are all h

[0012] The recovered SF6 gas mass is In the formula The mass of SF6 gas recovered during the nth cycle, in kg. The standard density of SF6 gas is taken as 6.08 kg / m³. 3 ; The SF6 gas density before and after gas chamber recovery is calculated using equation (1). and : (1) The effective volume of the gas chamber is calculated using equation (3) during the first cycle of recovery. : (3).

[0013] As a preferred technical solution, the standard volume of the recovered gas during the nth cycle is calculated using equation (4). : (4) The standard volume of N2 replenished each time is calculated using equation (5). : (5) The partial pressure of N2 added during the nth cycle in the mixing container is calculated using equation (6). : (6) Where V a P is the effective volume of the mixing container. a The pressure is the gas pressure inside the mixing container 13 as monitored by pressure sensor 2 15, in MPa.

[0014] As a preferred technical solution, temperature sensors and pressure sensors are installed on the end of the recovery pipeline near the gas chamber, the transfer container, and the mixing container; the mixed gas in the mixing container is mixed evenly through circulation.

[0015] As a preferred technical solution, the recovery pipeline is sequentially equipped with solenoid valve 1, pressure reducing valve 1, flow meter, buffer tank, solenoid valve 2, variable frequency compressor, solenoid valve 3, and solenoid valve 4. The recovery pipeline is connected to a non-destructive mixing ratio detector. The flow meter is used to measure the flow rate, and the non-destructive mixing ratio detector is used to measure the SF6 content in the recovered gas. The gas replenishment pipeline is equipped with solenoid valve 11, the circulation pipeline is equipped with solenoid valve 6 and pressure reducing valve 2, the transfer pipeline is equipped with solenoid valve 7, and the recharge pipeline is equipped with solenoid valve 8 and solenoid valve 10.

[0016] As a preferred technical solution, the circulation pipeline is connected to the recovery pipeline through a first connecting pipeline, and a solenoid valve five is provided on the first connecting pipeline. The recovery pipeline is connected to the recharge pipeline through a second connecting pipeline, and a solenoid valve nine is provided on the second connecting pipeline.

[0017] As a preferred technical solution, the connection end of the circulation pipeline and the recovery pipeline is located upstream of the variable frequency compressor, the connection end of the transfer pipeline and the recovery pipeline is located between the downstream of solenoid valve three and the upstream of solenoid valve four, the connection end of the transfer pipeline and the recharge pipeline is located upstream of solenoid valve eight, and the connection end of the recharge pipeline and the recovery pipeline is located upstream of solenoid valve one.

[0018] As a preferred technical solution, the mixed gas in the mixing container after nitrogen replenishment is mixed through circulation pipelines and recovery pipelines.

[0019] This invention also provides a non-power-off mixed gas replacement device and method for GIS equipment. The non-power-off mixed gas replacement device for GIS equipment recovers part of the SF6 gas in the gas chamber into the mixing container until the lower limit of the gas chamber pressure is reached. The mixing container is filled with nitrogen to prepare a mixed gas of 29% SF6:71% N2. The mixed gas is mixed evenly and used as a filling gas source and transferred to the transfer container. The mixed gas in the transfer container is filled into the gas chamber. The process of repeated filling and recovery reduces the proportion of SF6 gas in the gas chamber to a set value.

[0020] The beneficial effects of this invention are as follows: (1) In this invention, the mixed gas replacement of GIS equipment is realized by pumping the gas chamber to the lower pressure limit so that the gas chamber always maintains a certain pressure. There is no need to reduce the pressure of adjacent gas chambers by half, which avoids the deformation and leakage at the gas chamber connection due to excessive pressure difference. There is no need to stop the power during the replacement process, which improves the replacement efficiency. At the same time, the gas in the gas chamber is completely mixed and the SF6 ratio meets the State Grid operation requirements. This avoids the formation of a local "nitrogen column" near the gas inlet when the gas chamber is filled. It also ensures that the insulation strength of all positions inside the gas chamber meets the operation requirements at all times. In addition, the gas flows repeatedly in the gas chamber through multiple cycles of replacement, which promotes the mixing of the mixed gas in the gas chamber. Compared with the existing mixed gas filling method, there is no need to let it stand for 24 hours to wait for it to diffuse and mix naturally, which further improves the replacement efficiency. When the replacement is completed, the mixed gas in the gas chamber is in a mixed state. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the replacement device provided in an embodiment of the present invention; Reference numerals: 1. Gas chamber interface; 2. Temperature sensor one; 3. Pressure sensor one; 4. Solenoid valve one; 5. Pressure reducing valve one; 6. Flow meter; 7. Non-destructive mixing ratio detector; 8. Buffer tank; 9. Solenoid valve two; 10. Variable frequency compressor; 11. Solenoid valve three; 12. Solenoid valve four; 13. Mixing container; 14. Temperature sensor two; 15. Pressure sensor two; 16. Solenoid valve eleven; 17. Cylinder interface; 18. Solenoid valve six; 19. Pressure reducing valve two; 20. Solenoid valve five; 21. Solenoid valve seven; 22. Solenoid valve eight; 23. Transfer container; 24. Temperature sensor three; 25. Pressure sensor three; 26. Solenoid valve nine; 27. Solenoid valve ten; 28. Recovery pipeline; 29. ​​Gas replenishment pipeline; 30. Circulation pipeline; 31. Transfer pipeline; 32. Refilling pipeline; 33. First connecting pipeline; 34. Second connecting pipeline. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. 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.

[0023] See Figure 1 A non-power-off mixed gas replacement device for GIS equipment, comprising: The recovery pipeline 28 is connected to the gas chamber and mixing container of the GIS equipment and is used to recover part of the SF6 gas in the gas chamber into the mixing container. The gas supply line 29 is connected to the mixing container and the nitrogen source, and is used to supply nitrogen into the mixing container and configure the SF6 and nitrogen in the mixing container into a mixed gas with a set ratio. The circulation line 30 is connected to the recovery line 28 and the mixing container, and is used to mix the gas in the mixing container. The transfer pipeline 31 is connected to the transfer container and the refill pipeline 32, and is used to transfer the mixed gas in the mixing container to the transfer container through the transfer pipeline 31. The refill line 32 is connected to the end of the recovery line 28 near the gas chamber and the transfer container, and is used to refill the mixed gas in the transfer container back to the gas chamber. In this embodiment, the mixing container includes a mixing container 13, and the transfer container includes a transfer container 23. The ratio is set to 29%SF6:71%N2, but other ratios can be set as needed. The mixing container 13 is equipped with a pressure sensor 15 and a temperature sensor 14, and the transfer container 23 is equipped with a temperature sensor 24 and a pressure sensor 25. The end of the recovery pipeline 28 near the gas chamber interface 1 is equipped with a pressure sensor 3 and a temperature sensor 2.

[0024] See Figure 1 The recovery pipeline 28 is equipped with a solenoid valve 4, a pressure reducing valve 5, a flow meter 6, a buffer tank 8, a solenoid valve 9, a variable frequency compressor 10, a solenoid valve 11, and a solenoid valve 12 in sequence; a temperature sensor 2 and a pressure sensor 3 are provided at the end of the recovery pipeline 28 near the gas chamber; a non-destructive mixing ratio detector 7 is connected to the recovery pipeline 28. The gas supply line 29 is equipped with a solenoid valve 16 and a cylinder interface 17, wherein the cylinder interface 17 is located at the end of the gas supply line 29 that is connected to the nitrogen source; The circulation pipeline 30 is equipped with a solenoid valve 18 and a pressure reducing valve 19; the connection end of the circulation pipeline 30 and the recovery pipeline 28 is located upstream of the variable frequency compressor 10. The transfer pipeline 31 is equipped with a solenoid valve 21; the connection end between the transfer pipeline 31 and the recovery pipeline is located between the downstream of the solenoid valve 11 and the upstream of the solenoid valve 12. The recharge line 32 is equipped with solenoid valve 8 22 and solenoid valve 10 27. The connection end between the transfer line 31 and the recharge line 32 is located upstream of solenoid valve 8 22, and the connection end between the recharge line 32 and the recovery line 28 is located upstream of solenoid valve 1 4. The circulation pipeline 30 is connected to the recovery pipeline 28 via the first connecting pipeline 33. The connection end of the first connecting pipeline 33 and the circulation pipeline 30 is located between the mixing container and the pressure reducing valve 19. The connection end of the first connecting pipeline 33 and the recovery pipeline 28 is located between the solenoid valve 11 and the solenoid valve 12. The first connecting pipeline 33 is equipped with a solenoid valve 20. The recovery pipeline 28 is connected to the recharge pipeline 32 via the second connecting pipeline 34. The second connecting pipeline 34 is equipped with a solenoid valve 26. The connection end of the second connecting pipeline 34 and the recovery pipeline 28 is located between the downstream of the variable frequency compressor 10 and the upstream of the solenoid valve 11. The connection end of the second connecting pipeline 34 and the recharge pipeline 32 is located between the solenoid valve 22 and the solenoid valve 27.

[0025] In this embodiment, the end of the gas chamber away from the recovery pipeline 28 is connected to another gas chamber, namely the adjacent gas chamber. The gas chamber is a large gas chamber, which is spliced ​​together from multiple sections. In this embodiment, the mixed gas replacement of GIS equipment is realized. There is no need to stop the power during the replacement process. The gas chamber is pumped to the lower pressure limit, so that the gas chamber always maintains a certain pressure. There is no need to reduce the pressure of the adjacent gas chamber by half, which avoids the deformation and leakage at the gas chamber connection due to excessive pressure difference. The transformation process and efficiency are greatly improved. Meanwhile, the gas injected into the gas chamber each time is completely mixed, and the gas flows repeatedly in the gas chamber through multiple cycles of replacement, which promotes the mixing of the gas in the gas chamber. Compared with the existing mixed gas filling method, there is no need to let it stand for 24 hours to wait for it to diffuse and mix naturally.

[0026] The uninterrupted power supply replacement method includes the following steps, with the following steps taking the first loop as an example. If it is the nth loop, the subscript is n: S1. Recover a portion of the SF6 gas in the gas chamber to the lower limit of the gas chamber pressure; Open solenoid valves 1-4, 2-9, 3-11, and 4-12 to start the variable frequency compressor 10. This process recovers the pure SF6 gas from the gas chamber into the mixing container 13 until the pressure sensor 3 at the front end of solenoid valve 1-4 detects that the gas chamber pressure has reached the lower limit P. min During the recovery process, flow meter 6 continuously measures the flow rate Q of the recovered gas. 1n The non-destructive mixing ratio detector 7 detects the proportion of SF6 (C1) in the recovered gas. S2, calculation of effective volume of gas chamber and amount of SF6 gas in recovered gas; The SF6 gas pressures P0, P1 and T0, T1 in the gas chamber measured by pressure sensor-3 and temperature sensor-2 before and after recovery are substituted into equation (1) of the Bertie-Bridgeman equation to calculate the SF6 gas density before and after gas chamber recovery. and : (1) In the formula, P is the absolute pressure of SF6 gas, and the unit is MPa; This is the density of SF6 gas, in kg / m³. 3 T is the thermodynamic temperature of SF6 gas, in K. Then, based on the measured gas flow rate Q1 and the SF6 content C1 in the recovered gas, the standard condition (20℃, standard atmospheric pressure) volume of SF6 in the recovered gas is calculated using equation (2). : (2) In the formula, This represents the volume of SF6 gas recovered during the first cycle at standard conditions (20°C, standard atmospheric pressure), in cubic meters (m³). 3If it is the nth cycle, the subscript "1" can be represented by "n". Q1 is the flow rate of the recovered gas in the first cycle, in meters. 3 / h, if it is the nth cycle, the subscript "1" can be represented by "n", C1 is the proportion of SF6 in the gas recovered in the 1st cycle, if it is the nth cycle, the subscript "1" can be represented by "n", This represents the start time of recycling in the first iteration, in hours ("h"). For the nth iteration, the subscript "1" can be represented by "n". This represents the end time of recycling in the first cycle, in "h". If it is the nth cycle, the subscript "1" can be represented by "n". The density of SF6 gas under standard conditions is known to be 6.08 kg / m³. 3 Therefore, the mass of SF6 gas recovered is In the formula This represents the mass of SF6 gas recovered during the first cycle, in kg. For the nth cycle, the subscript "1" can be represented by "n". The standard density of SF6 gas is taken as 6.08 kg / m³. 3 ; Then, based on the SF6 gas density before and after recovery and The effective volume of the gas chamber is calculated using equation (3) only during the first cycle of recovery. : (3) Except for the first recovery, all subsequent recoveries are a mixture of SF6 and N2 gas, and the effective volume of the gas chamber is calculated only when pure SF6 gas is recovered for the first time; S3. Calculation of the volume and partial pressure of N2 gas required to prepare a 29%SF6:71%N2 mixed gas; The recovered gas needs to be prepared as a 29%SF6:71%N2 mixture as the charging gas source: the standard volume of the recovered gas during the first cycle is calculated using equation (4). (20℃, standard atmospheric pressure), unit: m 3 If it is the nth iteration, then the subscript "1" can be represented by "n": (4) Considering that the proportion of SF6 in the recovered gas is higher than 29%, N2 needs to be added to reduce the gas proportion to 29%. The standard condition volume of N2 added during the first cycle is calculated using equation (5). Unit m 3 If it is the nth iteration, then the subscript "1" can be represented by "n": (5) Since N2 is a typical ideal gas, according to Dalton's law of partial pressures, the partial pressure of the N2 added during the first cycle in the mixing container 13 can be calculated using equation (6). The unit is MPa. If it is the nth cycle, the subscript "1" can be represented by "n". (6) Where V a P is the effective volume of mixing container 13. a The pressure is the gas pressure inside the mixing container 13 monitored by pressure sensor 2 15, in MPa. Preparation, mixing and storage of S4, 29%SF6:71%N2 mixed gas; When solenoid valve 11 is opened, pressure sensor 15 on mixing container 13 detects pressure P. a P rise 1n When the solenoid valve 11 is closed, the mixing ratio of the gas mixture in the mixing container 13 is 29%:71%. Open solenoid valves 11, 12, and 18, close other valves, and start the variable frequency compressor 10 for a set time. In this embodiment, the set time is 2 minutes. The gas in the mixing container 13 is completely mixed by circulating the gas.

[0027] Open solenoid valves 11, 18, 21, and 22, start the variable frequency compressor 10, and transfer the 29% SF6:71% N2 mixed gas in mixing container 13 to storage container 23. Stop the transfer when the pressure in mixing container 13 drops to 0.1 MPa. S5, the 29%SF6:71%N2 mixed gas in transfer container 23 is refilled; The pressure in the gas chamber is generally no more than 0.7 MPa, while the pressure in the transfer container 23 is generally more than 1 MPa. The stored 29% SF6:71% N2 mixed gas will return to the gas filling chamber to the set pressure under the action of pressure difference. S6 and S1~S5 are considered as one replacement process. Through repeated replacements until a complete recovery process is completed, the proportion of SF6 C1 in the recovered gas detected by the non-destructive mixing ratio detector 7 is always between 29% and 31%. This can be considered as the complete replacement of the SF6 gas in the gas chamber with a mixture of 29% SF6 and 71% N2. At this time, the mixed gas in the gas chamber is completely mixed, and the GIS equipment completes the mixed gas replacement without power interruption.

[0028] It should be noted that, When the lower limit of the recovery pressure in S1 is the recovery to the alarm pressure of the gas chamber, the recharge to the set pressure in S5 refers to the recharge to the rated pressure after the gas mixing modification. In this embodiment, the rated pressure after the gas mixing modification is 1.33 times the rated pressure of the original SF6 gas equipment. When the lower limit of the recovery pressure in S1 is the equivalent insulation strength pressure at the current gas chamber mixing ratio, the recharge to the set pressure in S5 refers to the recharge to the upper limit of the gas chamber pressure.

[0029] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A non-power-off mixed gas replacement device for GIS equipment, characterized in that, include: The recovery pipeline is connected to the gas chamber and mixing container of the GIS equipment and is used to recover part of the SF6 gas in the gas chamber into the mixing container. The gas supply line is connected to the mixing container and the nitrogen source. It is used to supply nitrogen into the mixing container and to mix the SF6 and nitrogen in the mixing container into a set ratio of gas mixture. The circulation line, connected to the recovery line and the mixing container, is used to mix the gas in the mixing container. The transfer pipeline, connected to the transfer container and the refill pipeline, is used to transfer the mixed gas in the mixing container to the transfer container through the transfer pipeline. The refill line is connected to the end of the recovery line near the gas chamber and the transfer container, and is used to refill the mixed gas in the transfer container back into the gas chamber. Part of the SF6 gas in the gas chamber is recovered into the mixing container until the lower limit of the gas chamber pressure is reached. Nitrogen is introduced into the mixing container to prepare a mixed gas in a set ratio. The mixed gas is mixed evenly and used as a charging gas source and transferred to the transfer container. The mixed gas in the transfer container is then charged into the gas chamber. The process of repeated charging and recovery is repeated to reduce the proportion of SF6 gas in the gas chamber to the set pressure. The lower limit of the gas chamber pressure is the gas chamber alarm pressure or the equivalent insulation strength pressure under the current gas chamber mixing ratio. The pressure is repeatedly charged to the set pressure, which is the rated pressure after the gas mixing modification or the upper limit of the gas chamber pressure.

2. The GIS equipment uninterrupted mixed gas replacement device according to claim 1, characterized in that, The effective volume of the gas chamber is calculated by taking the SF6 gas pressure and temperature in the pre- and post-recovery chambers, the recovered gas flow rate, and the SF6 percentage in the recovered gas. The volume of the recovered gas is calculated based on the gas flow rate during the recovery process. The volume of supplemented nitrogen is calculated using the effective volume of the gas chamber and the volume of the recovered gas. The partial pressure of nitrogen in the mixing container at a set ratio is calculated using the supplemented nitrogen volume. Gas replenishment is stopped when the pressure in the mixing container reaches the partial pressure of nitrogen at the set ratio.

3. The GIS equipment uninterrupted mixed gas replacement device according to claim 1, characterized in that, The volume of SF6 in the recovered gas is calculated using equation (2). : （2） In the formula, This represents the volume of SF6 standard condition gas recovered during the nth cycle, in cubic meters (m³). 3 , This is the nth iteration, with units of m. 3 / h, The percentage of SF6 in the gas recovered during the nth cycle. This represents the start time of recycling during the nth iteration. This represents the end time of recycling during the nth iteration. , All units are in hours (h). The recovered SF6 gas mass is In the formula The mass of SF6 gas recovered during the nth cycle, in kg. The standard density of SF6 gas is taken as 6.08 kg / m³. 3 ; The SF6 gas density before and after gas chamber recovery is calculated using equation (1). and : （1） The effective volume of the gas chamber is calculated using equation (3) during the first cycle of recovery. : （3）。 4. The GIS equipment uninterrupted mixed gas replacement device according to claim 1 or 3, characterized in that, The standard volume of recovered gas during the nth cycle is calculated using equation (4). : （4） The standard volume of N2 replenished each time is calculated using equation (5). : （5） The partial pressure of N2 added during the nth cycle in the mixing container is calculated using equation (6). : （6） Where V a P is the effective volume of the mixing container. a The pressure is the gas pressure inside the mixing container 13 as monitored by pressure sensor 2 15, in MPa.

5. The GIS equipment uninterrupted mixed gas replacement device according to claim 1, characterized in that, Temperature and pressure sensors are installed at the end of the recovery pipeline near the gas chamber, the transfer container, and the mixing container; the mixed gas in the mixing container is mixed evenly through circulation.

6. The GIS equipment uninterrupted mixed gas replacement device according to claim 1, characterized in that, The recovery pipeline is equipped with, in sequence, solenoid valve 1, pressure reducing valve 1, flow meter, buffer tank, solenoid valve 2, variable frequency compressor, solenoid valve 3, and solenoid valve 4. The recovery pipeline is connected to a non-destructive mixing ratio detector. The flow meter is used to measure the flow rate, and the non-destructive mixing ratio detector is used to measure the SF6 content in the recovered gas. The gas replenishment pipeline is equipped with solenoid valve 11, the circulation pipeline is equipped with solenoid valve 6 and pressure reducing valve 2, the transfer pipeline is equipped with solenoid valve 7, and the recharge pipeline is equipped with solenoid valve 8 and solenoid valve 10.

7. The GIS equipment uninterrupted mixed gas replacement device according to claim 6, characterized in that, The circulation pipeline is connected to the recovery pipeline through the first connecting pipeline, which is equipped with solenoid valve five. The recovery pipeline is connected to the recharge pipeline through the second connecting pipeline, which is equipped with solenoid valve nine.

8. The GIS equipment uninterrupted mixed gas replacement device according to claim 6, characterized in that, The connection point between the circulation pipeline and the recovery pipeline is located upstream of the variable frequency compressor. The connection point between the transfer pipeline and the recovery pipeline is located between the downstream of solenoid valve three and the upstream of solenoid valve four. The connection point between the transfer pipeline and the recharge pipeline is located upstream of solenoid valve eight. The connection point between the recharge pipeline and the recovery pipeline is located upstream of solenoid valve one.

9. The GIS equipment uninterrupted mixed gas replacement device according to claim 1, characterized in that, The mixed gas in the mixing container after nitrogen replenishment is mixed through circulation and recovery pipelines.

10. A method for replacing mixed gas in GIS equipment without power interruption, characterized in that, Using the uninterrupted power supply mixed gas replacement device for GIS equipment as described in any one of claims 1-9, a portion of the SF6 gas in the gas chamber is recovered into the mixing container until the lower limit of the gas chamber pressure is reached. Nitrogen is introduced into the mixing container to prepare a mixed gas of 29% SF6: 71% N2. The mixed gas is mixed evenly and used as a gas source for filling and is transferred to a transfer container. The mixed gas in the transfer container is then filled into the gas chamber. Through multiple filling and recovery processes, the proportion of SF6 gas in the gas chamber is reduced to a set value.

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