An online sampling detection gas taking and refilling device and method for GIS equipment

Abstract

The application is suitable for the technical field of GIS equipment detection, and provides an online gas taking and recharging device and method for GIS equipment sampling detection, which comprises a gas taking and supplying gas path and a recharging gas path arranged between a detection gas chamber and a detection unit, wherein the detection gas chamber is connected to the two gas paths through a first three-way joint, the gas taking and supplying gas path comprises a first electromagnetic valve, a second electromagnetic valve and a pressure stabilizing valve connected in sequence, and the device further comprises a second three-way joint, a first pressure sensor and a gas cylinder, the recharging gas path comprises a third electromagnetic valve, a back pressure valve, a buffer tank, a vacuum booster pump and a fourth electromagnetic valve connected in sequence, and a second pressure sensor is further arranged. The device comprises the gas taking and supplying gas path and the recharging gas path, and can ensure accurate gas taking and supplying and recharging according to the set operation method and parameter setting, so that environmental pollution caused by direct discharge of SF6 greenhouse gas is avoided, and the SF6 in the GIS equipment is ensured not to be reduced, and the product performance is ensured.

Description

Technical Field

[0001] This invention belongs to the field of substation GIS equipment testing technology, and particularly relates to an online gas sampling and recharging device and method for GIS equipment sampling and testing. Background Technology

[0002] The State Grid's electricity load is increasing year by year, and to cope with this, the construction of substations is constantly being invested. The number of GIS (Gas Insulated Switchgear) devices is also increasing annually, requiring significant human and material resources for safety monitoring.

[0003] Safety in production is not only a matter of safety itself, but also a matter of economic loss for users in the power distribution area where GIS equipment malfunctions and shuts down. This loss due to power outages can be enormous and unacceptable. Therefore, the State Grid Corporation of China equips GIS equipment with appropriate testing equipment and conducts regular operational status inspections. From past methods like on-site sampling to laboratory testing, and then to on-site testing with portable devices, these methods suffer from time delays, high manpower requirements, and safety concerns for operators, especially in rainy, foggy weather and under live-line operating conditions.

[0004] Given the imbalance in operational safety, real-time performance, and human and financial resources, the State Grid Corporation of China has been increasing its investment in and application of online monitoring devices in recent years. Online monitoring offers enhanced real-time performance and can analyze continuous monitoring data to provide trend information and early warnings. This reduces production safety issues caused by analytical errors resulting from human error and varying levels of operator skill.

[0005] Currently, most portable SF6 gas analyzers for GIS equipment use a flow-type emission detection method. Electrochemical methods have a detection flow rate of 200-300 mL / min and a detection cycle of 3-5 minutes, while optical methods have a detection flow rate of 300-500 mL / min and a detection cycle of 5-10 minutes. Each detection releases a certain amount of SF6 gas from the corresponding gas chamber of the GIS equipment, thus reducing the SF6 gas pressure and density, which affects the insulation and arc-quenching properties of SF6 gas. Furthermore, there are few online monitoring devices on the market that utilize this flow-type detection method for GIS equipment, primarily because it is limited by the inability to achieve flow and gas refill. Summary of the Invention

[0006] In view of the above problems, the purpose of this invention is to provide an online gas sampling and recharging device and method for GIS equipment sampling and testing, in order to solve the above technical problems.

[0007] The present invention adopts the following technical solution:

[0008] On one hand, the online gas sampling and recharging device for GIS equipment sampling and detection includes a gas supply path and a recharging path disposed between the detection gas chamber and the detection unit. The detection gas chamber is connected to the two paths respectively through a first three-way valve S1. The gas supply path includes a first solenoid valve F1, a second solenoid valve F2 and a pressure regulating valve T1 connected in sequence. A second three-way valve S2 and a first pressure sensor P1 are also disposed on the pipeline between the first and second solenoid valves. The second three-way valve S2 is also connected to a cylinder G. The recharging path includes a third solenoid valve F3, a back pressure valve T2, a buffer pool Bp, a vacuum booster pump Pum and a fourth solenoid valve F4 connected in sequence. A second pressure sensor P2 is also disposed on the pipeline between the back pressure valve T2 and the buffer pool Bp.

[0009] Furthermore, a one-way valve T3 is provided at the inlet or outlet of the fourth solenoid valve F4.

[0010] Furthermore, the pressure point of the back pressure valve is set between 101 kPa and 120 kPa.

[0011] Furthermore, there are several detection chambers, and each detection chamber is equipped with a fifth solenoid valve F5 at its gas path port. All fifth solenoid valves F5 are connected to the first three-way valve S1 through a main pipe.

[0012] Furthermore, a detachable adsorbent chamber Ads is provided between the buffer tank Bp and the vacuum booster pump Pum, and manual switches are provided on both ends of the pipeline ports of the adsorbent chamber Ads and the buffer tank Bp.

[0013] On the other hand, the online gas sampling and recharging method for GIS equipment includes the following steps:

[0014] Step S1, Preparatory Steps

[0015] Connect the online gas intake and recharge device according to the gas circuit connection method. Use pure SF6 gas to flush the gas circuit and fill the buffer tank with pure SF6 gas. After the device is powered on, adjust the pressure of the buffer tank so that the pressure is less than the pressure difference value at which the back pressure valve is stable. Record the pressure of the buffer tank as the initial pressure value. Reset the stroke of the cylinder to the zero position.

[0016] Step S2, Gas Extraction Step

[0017] Open the first solenoid valve, obtain the pressure value P of the detection chamber through the first pressure sensor, and determine the target stroke L of the cylinder = r*[mRT / (M*P*S)], where r is the redundancy, m is the gas mass, R is the molar gas constant, T is the ambient temperature, M is the gas molar mass, P is the current detection chamber pressure value, and S is the cross-sectional area of ​​the cylinder.

[0018] The target stroke L is calculated to control the cylinder to take in air, and then the first solenoid valve is turned off to complete the sample gas extraction.

[0019] Step S3, Gas Supply Step

[0020] After opening the third solenoid valve, the second solenoid valve is opened. Under the pressure difference between the back pressure valve and the pressure regulating valve, gas is supplied to the detection pool of the detection unit according to the required flow rate. During the gas supply process, the pressure at the outlet of the back pressure valve is controlled to be less than the set pressure point, and the pressure values ​​of the two pressure sensors are monitored. The detected gas enters the buffer pool through the back pressure valve.

[0021] If the pressure value of the first pressure sensor is close to the air supply pressure threshold of the pressure regulator, the motor is started to slowly compress the cylinder, so that the air supply pressure is greater than the fixed value of the air supply pressure threshold, forming a pressure difference. This process is repeated until the detection cycle ends.

[0022] Step S4, Recharge Step

[0023] During the gas supply process, if the pressure value of the second pressure sensor rises and approaches the pressure point of the back pressure valve, the fourth solenoid valve is opened, and the vacuum booster pump is started to pump the gas in the buffer tank back into the detection chamber, while simultaneously depressurizing the buffer tank. When the pressure value of the second pressure sensor drops to the lower pressure threshold, the vacuum booster pump is turned off and the fourth solenoid valve is closed. This process is repeated until the detection cycle ends. Then, the vacuum booster pump and the fourth solenoid valve are turned on to pump the gas in the buffer tank back into the detection chamber, restoring the buffer tank to its initial pressure value. Finally, the vacuum booster pump is turned off again and the fourth solenoid valve is closed.

[0024] Furthermore, step S4 also includes:

[0025] After the test cycle ends, if the cylinder does not return to the zero position, the residual air in the cylinder will be refilled after the buffer tank is refilled. The process is as follows: open the first solenoid valve, close the fourth solenoid valve, start the cylinder to compress until it reaches the zero position, and finally close the first solenoid valve and stop the cylinder compression drive.

[0026] The beneficial effects of this invention are as follows: This invention designs an online gas extraction and refilling device and method. The device includes a gas extraction and supply path and a refilling path. By rationally selecting the connection relationship of valves, buffer tanks, cylinders and other components of the two paths, and by setting the operating method and parameters, it can ensure accurate gas extraction and refilling, avoid direct emission of SF6 greenhouse gas causing environmental pollution, and also ensure that SF6 in GIS equipment is not reduced, thus ensuring product performance. Attached Figure Description

[0027] Figure 1This is a schematic diagram of an online gas extraction and recharging device provided in an embodiment of the present invention;

[0028] Figure 2 This is another schematic diagram of the online gas extraction and recharging device provided in this embodiment of the invention;

[0029] Figure 3 This is a flowchart of the online gas sampling and recharging method for GIS equipment sampling and testing;

[0030] Figure 4 This is a schematic diagram of the air flushing connection. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0032] To illustrate the technical solution described in this invention, specific embodiments are described below.

[0033] like Figure 1 As shown, this embodiment provides an online gas sampling and recharging device for GIS equipment sampling and detection, including a gas supply path and a recharging path disposed between the detection gas chamber and the detection unit. The detection gas chamber is connected to the two paths respectively through a first three-way valve S1. The gas supply path includes a first solenoid valve F1, a second solenoid valve F2 and a pressure regulating valve T1 connected in sequence. A second three-way valve S2 and a first pressure sensor P1 are also disposed on the pipeline between the first and second solenoid valves. The second three-way valve S2 is also connected to a cylinder G. The recharging path includes a third solenoid valve F3, a back pressure valve T2, a buffer pool Bp, a vacuum booster pump Pum and a fourth solenoid valve F4 connected in sequence. A second pressure sensor P2 is also disposed on the pipeline between the back pressure valve T2 and the buffer pool Bp.

[0034] The gas supply path is used to extract SF6 gas from the detection chamber and deliver the extracted gas to the detection unit at a predetermined flow rate. The return path is used to return the SF6 gas after detection to the detection chamber according to a set configuration. The core of this embodiment is the selection and connection of the gas path components. The detection chamber is the SF6 gas chamber in the GIS equipment to be tested. The detection unit is the module inside the online detection device (such as an SF6 gas analyzer) of the GIS equipment used to detect SF6 gas.

[0035] Currently, most portable SF6 gas analyzers on the market use the electrochemical method. Electrochemical detection requires a flow rate of 200-300 mL / min and a detection cycle of 3-5 minutes; while optical detection requires a flow rate of 300-500 mL / min and a detection cycle of 5-10 minutes, but the quantity is smaller. Based on the above data, the gas consumption for a single detection can be calculated as follows: electrochemical method: maximum 1.5 L; optical method: maximum 5 L.

[0036] SF6 gas has a liquefaction temperature of -62℃ at one atmosphere (0.1 MPa) and 0℃ at 1.2 MPa. The pressure of sulfur hexafluoride gas generally used in GIS equipment (such as circuit breakers) is in the range of 0.40 to 0.80 MPa (determined by the ambient temperature during filling), and its liquefaction temperature is -40℃.

[0037] When a gas is compressed (under pressure), its volume increases when it is released to normal pressure. The relationship between pressure and volume is: pV=mRT / M=nRT, where m is the mass of the gas in g; p is the gas pressure in MPa; T is the temperature in K; V is the gas volume in L; M is the molar mass of the gas in g / mol; and R is the molar gas constant (R=0.0082MPa•L / (K•mol)).

[0038] It can be seen that when the temperature T is constant, the product of pressure and volume is a constant, and the greater the pressure, the smaller the volume.

[0039] Therefore, for cylinders, when selecting electric cylinders, the volume of the electric cylinder in the air supply path can be chosen based on the volume of air consumed in a single detection by the GIS equipment. This volume is then multiplied by the redundancy factor (the higher the inflation pressure of the GIS equipment, the smaller the required redundancy factor, e.g., 1.4, to facilitate gas delivery to the detection unit) to determine the cylinder's size. Similarly, the volume of the buffer tank in the return inflation path can also be determined, but this buffer tank size should be calculated based on the normal pressure volume, i.e., the total amount of gas consumed in the detection cycle multiplied by the redundancy factor.

[0040] The functions of a pressure regulating valve are twofold: first, to limit the inlet pressure supplied to the instrument's detection unit to prevent high pressure from damaging the instrument; and second, to adjust the output pressure to meet the flow rate requirements of the instrument (i.e., under a given flow rate, the pressure difference determines the flow rate).

[0041] The back pressure valve is used to provide a constant outlet pressure environment for the instrument, preventing flow / pressure fluctuations in the analyzer caused by the vacuum booster pump at the back end refilling the gas in the buffer tank into the detection chamber.

[0042] Furthermore, several currently popular detection methods, such as electrochemical, optical, and photoacoustic spectroscopy, are quite sensitive to ambient temperature and pressure. In practice, instrument calibration is performed under local atmospheric pressure conditions, but the application areas of these instruments vary in pressure, leading to a decrease in detection accuracy due to pressure changes. In this embodiment, by incorporating a pressure regulating valve and a back pressure valve, a constant pressure environment can be provided to the instrument, reducing the impact of pressure factors during calibration.

[0043] During the selection of back pressure valves, the calibration technology for back pressure valves with absolute gauge pressure of zero (one atmosphere) is quite demanding and difficult to achieve at a low cost. Among the various detection methods, electrochemical sensors have the smallest pressure tolerance range, typically ranging from 80 kPa to 120 kPa absolute pressure. Considering all factors, a fixed pressure point for the back pressure valve can be set between 101 kPa and 120 kPa. This ensures that the instrument is calibrated and used in the field under a specific pressure environment, eliminating the influence of pressure and effectively improving the accuracy of the detection data.

[0044] The inlet or outlet of the fourth solenoid valve F4 is equipped with a one-way valve T3. This is to prevent the gas in the detection chamber from impacting the vacuum booster pump when the solenoid valve F4 is open, and also to prevent gas from backflowing from the vacuum booster pump circuit into the instrument's detection unit in case of an anomaly.

[0045] Figure 1 The device shown can detect one GIS device. If multiple GIS devices need to be detected on-site, a parallel sample injection switch solenoid valve can be installed between the detection chamber and the device's air inlet and return port to expand it into a multi-chamber online monitoring and sampling device.

[0046] Specifically, such as Figure 2 As shown, each detection gas chamber is equipped with a fifth solenoid valve F5 (i.e., a sample injection switch solenoid valve) at its gas path port, and all fifth solenoid valves F5 are connected to the first three-way valve S1 via a main pipe.

[0047] When adding interfaces for multiple detection chambers, further improvements to the buffer pool are needed. For example... Figure 2 As shown, it is divided into two stages, with an additional adsorbent chamber in the latter stage for placing the adsorbent. Specifically, a detachable adsorbent chamber Ads is provided between the buffer tank Bp and the vacuum booster pump Pum. Manual switches are installed at both ends of the pipelines of both the adsorbent chamber Ads and the buffer tank Bp. After the manual switches at both ends of the adsorbent chamber are turned off, the adsorbent can be easily replaced, thus purifying the detected gas and reducing the occurrence of cross-contamination between the multiple chambers.

[0048] Based on the above-described device, this embodiment also provides an online gas sampling and recharging method for GIS equipment sampling and detection, such as... Figure 3 As shown, it includes the following steps:

[0049] Step S1, Preparatory Steps

[0050] Connect the online gas intake and recharge device according to the gas circuit connection method. Use pure SF6 gas to flush the gas circuit and fill the buffer tank with pure SF6 gas. After the device is powered on, adjust the pressure of the buffer tank so that the pressure is less than the pressure difference value at which the back pressure valve is stable. Record the pressure of the buffer tank as the initial pressure value. Reset the stroke of the cylinder to the zero position.

[0051] In this step, the device is first connected to the detection unit via the gas path before use, and airtightness is ensured. Then, pure SF6 gas is used to flush the gas path, purging air or other gases from the internal gas path to ensure that no other gases are introduced into the detection chamber of the GIS equipment during operation, thus affecting the gas composition in the GIS equipment's detection chamber. During the gas path flushing operation, if... Figure 4 As shown, the inlet and outlet for flushing are connected to the two ends of the first solenoid valve F1, respectively. When F1 is closed, the air flushing cycle is realized.

[0052] The buffer tank should be pre-filled with pure SF6 gas at a pressure less than or equal to atmospheric pressure. Specifically, a connector is installed on the buffer tank and connected with a shut-off three-way valve to inject pure SF6 gas.

[0053] After the device is powered on, the pressure of the buffer tank is adjusted according to the initial parameters to ensure that the pressure is lower than the pressure difference required for the back pressure valve to operate stably, thus meeting the working requirements of the back pressure valve. The adjusted pressure is recorded as the initial pressure value. For example, if the working pressure point of the back pressure valve is set to 110 kPa, then the pressure of the buffer tank must be less than 110 kPa. If an additional pressure difference of ak Pa is required, then the pressure of the buffer tank must be less than (110-a) kPa. Simultaneously, to meet the needs of the detection process, an additional pressure difference of b kPa is required, with b being a larger value to reduce the number of times the refill pump operates. Therefore, the final pressure of the buffer tank must be less than (110-ab) kPa. Then, the cylinder stroke is reset to the zero position, i.e., the 0% position. Upon completion, a waiting signal is given, indicating that the next step of the detection process can proceed.

[0054] Step S2, Gas Extraction Step

[0055] S21. Open the first solenoid valve, obtain the pressure value P of the detection chamber through the first pressure sensor, and determine the target stroke L of the cylinder = r*[mRT / (M*P*S)], where r is the redundancy, m is the gas mass, R is the molar gas constant, T is the ambient temperature, M is the gas molar mass, P is the current detection chamber pressure value, and S is the cross-sectional area of ​​the cylinder.

[0056] S22. Control the cylinder to take in air according to the calculated target stroke L, and then turn off the first solenoid valve to complete the sample gas extraction.

[0057] In this embodiment, the pressure value P of the detection chamber is obtained through pressure sensor P1 to determine the size of the cylinder's air intake stroke L. Using the formula PV=mRT / M=nRT, the required gas mass m can be obtained first based on the volume usage at normal pressure. Then, substituting the current ambient temperature T and the current pressure P of the GIS equipment's air chamber into the formula, we get PV=mRT / M=nRT=constant C. From this, V=C / P can be calculated, yielding the air intake volume required for a single detection at the current pressure. It can be seen that P and V are inversely proportional; the higher the pressure, the smaller the volume. Combining the cylinder's cross-sectional area S, stroke L, and redundancy r setting, we can obtain L=r*C / (P*S)=r*[mRT / (M*P*S)] from S*L=r*V=r*C / P, thus calculating the cylinder stroke L.

[0058] The gas extraction process begins with an instruction or signal from the instrument. Upon detecting this instruction or signal, the device opens solenoid valve F1, connecting the cylinder to the detection chamber. Pressure sensor P1 then acquires the current pressure value in the chamber. Using the formula described above, the required sampling volume for a single test can be calculated, determining and controlling the cylinder's stroke for sample gas extraction. After the device's drive motor completes the calculated stroke L, solenoid valve F1 closes, completing the sample gas extraction.

[0059] Step S3, Gas Supply Step

[0060] S31. After opening the third solenoid valve, open the second solenoid valve. Under the pressure difference between the back pressure valve and the pressure regulating valve, supply gas to the detection pool of the detection unit according to the required flow rate. During the gas supply process, control the pressure at the outlet of the back pressure valve to be less than the set pressure point, and monitor the pressure values ​​of the two pressure sensors. The detected gas enters the buffer pool through the back pressure valve.

[0061] S32. If the pressure value of the first pressure sensor is close to the air supply pressure threshold of the pressure regulator, the motor is started to slowly compress the cylinder, so that the air supply pressure is greater than the fixed value of the air supply pressure threshold, forming a pressure difference. This process is repeated until the detection cycle ends.

[0062] After gas intake is complete, the solenoid valve F3 is opened first, followed by solenoid valve F2, to supply gas to the gas path of the instrument's detection unit. Under the pressure difference set by the back pressure valve and the pressure regulating valve, gas is supplied to the detection unit's gas path at the required flow rate. Simultaneously, to ensure the normal operation of the back pressure valve, the pressure at the valve's outlet must be controlled during gas supply to be lower than the valve's set pressure point and within the required pressure range to ensure stable operation. As mentioned earlier, the pressure point is 110 kPa. The pressure at the back pressure valve's outlet is also the pressure of the buffer tank, i.e., the pressure shown in P2, and must be less than 110 kPa. If an additional pressure difference of akPa is required, the buffer tank pressure must be less than (110-a) kPa. During gas supply, the pressure values ​​of P1 and P2 are monitored in real time. When the pressure value of P1 approaches the air supply pressure point set by the pressure regulator, the motor is started to slowly compress the cylinder, ensuring that the air supply pressure is greater than a certain pressure value set by the pressure regulator, thus creating a pressure difference. This continues until the detection cycle ends, at which point a stop air supply command is issued. After the detection process is completed, upon receiving a command or signal, solenoid valves F2 and F3 are shut off.

[0063] Step S4, Recharge Step

[0064] During the gas supply process, if the pressure value of the second pressure sensor rises and approaches the pressure point of the back pressure valve, the fourth solenoid valve is opened, and the vacuum booster pump is started to pump the gas in the buffer tank back into the detection chamber, while simultaneously depressurizing the buffer tank. When the pressure value of the second pressure sensor drops to the lower pressure threshold, the vacuum booster pump is turned off and the fourth solenoid valve is closed. This process is repeated until the detection cycle ends. Then, the vacuum booster pump and the fourth solenoid valve are turned on to pump the gas in the buffer tank back into the detection chamber, restoring the buffer tank to its initial pressure value. Finally, the vacuum booster pump is turned off again and the fourth solenoid valve is closed.

[0065] When gas is supplied to the detection unit for testing, the detected gas is output to the return gas path. During this process, when the pressure value of P2 rises and approaches the pressure point set by the back pressure valve (if the pressure difference akPa is considered, the pressure point is 110kPa, then it is determined whether it is close to (110-a)kPa), the solenoid valve F4 is opened, and the vacuum booster pump is started to evacuate the gas in the buffer tank and return it to the gas chamber while depressurizing the buffer tank. When P2 drops to a certain pressure threshold (i.e., the lower pressure limit threshold), the solenoid valve F4 is turned off and the vacuum booster pump stops working, thereby ensuring the stable operation of the back pressure valve and ultimately achieving a constant pressure difference in the gas path of the detection unit, thus ensuring a constant flow rate.

[0066] During this recharge process, the pressure value of pressure sensor P2 is monitored in real time to ensure that the pressure value at this location meets the pressure requirements for stable operation of the back pressure valve. When the pressure value at this location exceeds the pressure range and approaches the pressure point, solenoid valve F4 is opened and the vacuum booster pump is started to extract the gas from the buffer tank and pump it back into the detection gas chamber; when pressure sensor P2 detects that the current pressure value has dropped to the lower pressure threshold, the gas pump is turned off and solenoid valve F4 is closed.

[0067] The buffer tank has an initial operating pressure. When testing begins, the pressure in the buffer tank is much lower than the operating pressure set by the back pressure valve, used to accommodate or receive incoming gas. The buffer tank pressure rises as the gas is input for testing. When it exceeds a certain pressure value, approaching the pressure point, a vacuum booster pump is activated to evacuate the gas and refill the testing chamber, reducing the buffer tank pressure so that the back pressure valve can function properly. After the pressure drops, the buffer tank can continue to accommodate gas input during the testing process. Once the testing is complete, the buffer tank returns to its initial pressure value.

[0068] After the detection cycle ends, if the cylinder has not returned to the zero position, the remaining gas in the cylinder will be refilled after the buffer tank is refilled. The process is as follows: open the first solenoid valve F1, close the fourth solenoid valve F4, start the cylinder to compress until it reaches the zero position, and finally close the first solenoid valve F1 and stop the cylinder compression drive. Since the gas extraction is performed according to a redundancy multiple, under normal circumstances, the cylinder will not return to the zero position after the detection cycle ends, and a certain volume of gas will remain in the cylinder. Therefore, the remaining gas needs to be sent back to the detection chamber to avoid reducing the gas volume in the detection chamber. This invention, by extracting gas with a redundancy multiple and quantitatively detecting the gas, pushes the remaining gas back into the detection chamber, ensuring that each detection process is complete and has sufficient detection gas volume, preventing situations where there is insufficient detection gas.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for online gas sampling and recharging in GIS equipment, characterized in that, The method is applied to an online gas intake and recharge device. The online gas intake and recharge device includes a gas intake and supply path and a recharge path disposed between a detection gas chamber and a detection unit. The detection gas chamber is connected to the two paths respectively through a first three-way valve (S1). The gas intake and supply path includes a first solenoid valve (F1), a second solenoid valve (F2), and a pressure regulating valve (T1) connected in sequence. A second three-way valve (S2) and a first pressure sensor (P1) are also disposed on the pipeline between the first and second solenoid valves. The second three-way valve (S2) is also connected to a cylinder (G). The recharge path includes a third solenoid valve (F3), a back pressure valve (T2), a buffer tank (Bp), a vacuum booster pump (Pum), and a fourth solenoid valve (F4) connected in sequence. A second pressure sensor (P2) is also disposed on the pipeline between the back pressure valve (T2) and the buffer tank (Bp). The method includes the following steps: Step S1, Preparatory Steps Connect the gas circuit according to the gas circuit connection method of the online gas intake and recharge device. Use pure SF6 gas to flush the gas circuit and fill the buffer tank with pure SF6 gas. After the device is powered on, adjust the pressure of the buffer tank so that the pressure is lower than the pressure difference value of the back pressure valve when it is stable. Record the pressure of the buffer tank as the initial pressure value. Reset the stroke of the cylinder to the zero position. Step S2, Gas Extraction Step Open the first solenoid valve, obtain the pressure value P of the detection chamber through the first pressure sensor, and determine the target stroke L of the cylinder = r*[mRT / (M*P*S)], where r is the redundancy, m is the gas mass, R is the molar gas constant, T is the ambient temperature, M is the gas molar mass, P is the current detection chamber pressure value, and S is the cross-sectional area of ​​the cylinder. The target stroke L is calculated to control the cylinder to take in air, and then the first solenoid valve is turned off to complete the sample gas extraction. Step S3, Gas Supply Step After opening the third solenoid valve, the second solenoid valve is opened. Under the pressure difference between the back pressure valve and the pressure regulating valve, gas is supplied to the detection pool of the detection unit according to the required flow rate. During the gas supply process, the pressure at the outlet of the back pressure valve is controlled to be less than the set pressure point, and the pressure values ​​of the two pressure sensors are monitored. The detected gas enters the buffer pool through the back pressure valve. If the pressure value of the first pressure sensor is close to the air supply pressure threshold of the pressure regulator, the motor is started to slowly compress the cylinder, so that the air supply pressure is greater than the fixed value of the air supply pressure threshold, forming a pressure difference. This process is repeated until the detection cycle ends. Step S4, Recharge Step During the gas supply process, if the pressure value of the second pressure sensor rises and approaches the pressure point of the back pressure valve, the fourth solenoid valve is opened, and the vacuum booster pump is started to pump the gas in the buffer tank back into the detection chamber, while simultaneously depressurizing the buffer tank. When the pressure value of the second pressure sensor drops to the lower pressure threshold, the vacuum booster pump is turned off and the fourth solenoid valve is closed. This process is repeated until the detection cycle ends. Then, the vacuum booster pump and the fourth solenoid valve are turned on to pump the gas in the buffer tank back into the detection chamber, restoring the buffer tank to its initial pressure value. Finally, the vacuum booster pump is turned off again and the fourth solenoid valve is closed.

2. The online gas sampling and recharging method for GIS equipment sampling and testing as described in claim 1, characterized in that, Step S4 further includes: After the test cycle ends, if the cylinder does not return to the zero position, the residual air in the cylinder will be refilled after the buffer tank is refilled. The process is as follows: open the first solenoid valve, close the fourth solenoid valve, start the cylinder to compress until it reaches the zero position, and finally close the first solenoid valve and stop the cylinder compression drive.

3. The online gas sampling and recharging method for GIS equipment sampling and testing as described in claim 2, characterized in that, The inlet or outlet of the fourth solenoid valve (F4) is equipped with a check valve (T3).

4. The online gas sampling and recharging method for GIS equipment sampling and testing as described in claim 3, characterized in that, The pressure point of the back pressure valve is set between 101 kPa and 120 kPa.

5. The online gas sampling and recharging method for GIS equipment sampling and testing as described in claim 4, characterized in that, There are several detection chambers, and each detection chamber is equipped with a fifth solenoid valve (F5) at its gas port. All fifth solenoid valves (F5) are connected to the first tee (S1) through a main pipe.

6. The online gas sampling and recharging method for GIS equipment sampling and testing as described in claim 5, characterized in that, A detachable adsorbent chamber (Ads) is also provided between the buffer tank (Bp) and the vacuum booster pump (Pum). Manual switches are provided at both ends of the pipeline ports of the adsorbent chamber (Ads) and the buffer tank (Bp).

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