A non-destructive online monitoring method and device based on spectroscopy

Abstract

The present application belongs to the technical field of high-voltage electrical equipment, and particularly relates to a nondestructive on-line monitoring method and device based on spectroscopy. The device is connected in series through pipelines in sequence from the air inlet, the first electromagnetic valve, the pressure reducing valve, the SO2 fluorescence detection unit, the CO infrared absorption detection unit, the CF4 infrared absorption detection unit, the first pressure sensor, the flowmeter, the regulating valve, the second electromagnetic valve and the collection tank. One end of the third electromagnetic valve is communicated with the first electromagnetic valve through a pipeline, and the other end of the third electromagnetic valve is communicated with the rear end of the second electromagnetic valve through a pipeline. The first pressure sensor and the temperature sensor are connected to the upper part of the collection tank, and the temperature control unit is connected to the outer wall of the collection tank. The device has the characteristics of simple structure and flexible on-line monitoring of different gas chambers. The concentration of SF6 decomposition products is detected in a stable constant-pressure environment by using spectroscopy, so as to ensure that the insulation performance of the insulation gas in the gas chamber does not decrease, the measured gas is not polluted and wasted, and the sensitivity is high.

Description

Technical Field

[0001] This invention belongs to the field of high-voltage electrical equipment technology, and particularly relates to a non-destructive online monitoring method and device based on spectroscopy. Background Technology

[0002] SF6 gas possesses excellent insulating properties and is widely used in high-voltage electrical equipment. During operation, SF6 electrical equipment may develop various internal defects due to manufacturing, installation, and operation, leading to discharges such as arcing, sparking, corona discharge, or partial discharge, as well as overheating faults. These defects cause SF6 gas to decompose, generating various gaseous components, primarily SF4, SOF2, SO2F2, SOF4, SO2, CO, CF4, HF, and CF4. For operating electrical equipment, detecting SF6 gas decomposition products is a crucial method for fault diagnosis. Compared to other methods, its main advantages are good anti-interference capabilities, suitability for field use, and the gradual accumulation of SF6 gas decomposition products as internal defects develop and persist, making this method highly suitable for online monitoring.

[0003] Currently, there are various methods for detecting and analyzing SF6 decomposition products, mainly including gas chromatography, electrochemical methods, and spectroscopic methods. Gas chromatography is primarily used for laboratory testing, while the latter two can be used for on-site detection and online monitoring. Electrochemical methods are unsuitable for online monitoring due to issues such as the electrolyte drying out easily in dry gas environments and impurities generated during measurement preventing the refilling of the analyte gas. Gas chromatography requires the consumption of both the analyte gas and carrier gas during detection, and the chromatographic column needs cleaning and recalibration after a period of use. It also suffers from poor long-term stability, high environmental requirements, and long detection times, making it unsuitable for continuous online monitoring. Spectroscopic methods, due to their large gas cell volume, increase the demand for the analyte gas and can easily lead to a drop in gas pressure within the chamber. Given the shortcomings of traditional SF6 decomposition product detection methods, finding an online monitoring method that is highly sensitive, reliable, and allows for intact refilling of the analyte gas is crucial.

[0004] In the prior art, patent number CN201510075178.7 discloses a multi-channel online monitoring device and method for sulfur hexafluoride (SF6) insulated electrical equipment. This device achieves online detection of decomposition products of SF6 insulated electrical equipment by setting up a shared SF6 purity detection chamber, a shared return gas channel, and three independent SO2 detection chambers. The gas inside the insulated electrical equipment flows through a filter and then sequentially enters the SF6 purity detection unit and the SO2 concentration detection unit before being pressurized and refilled into the insulated electrical equipment by a vacuum pressurization pump.

[0005] However, this technology uses an electrochemical sensor to detect SO2 concentration, which requires the participation of O2 for detection and generates impurities after detection. If the electrochemical sensor is applied to online monitoring, the gas refilling into the gas chamber will affect the purity of SF6 gas, introducing impurities and reducing the insulation performance of the gas chamber. Moreover, electrochemical sensors suffer from irreversible degradation and have a short service life, which does not meet the long-term maintenance-free requirements of online monitoring. During the gas refilling process using a vacuum pressurization pump, impurities such as oil and gas are easily mixed in, causing the refilled gas to be mixed with impurities and reducing the insulation performance of the gas chamber. In addition, its structure is complex. Summary of the Invention

[0006] To address the shortcomings of existing technologies, such as those using electrochemical sensors, which introduce impurities during detection and those using pumps as power units for gas recharging, which easily introduce impurities like oil and gas, this invention provides a non-destructive online monitoring method and device based on spectroscopy. The purpose of this invention is to provide a highly sensitive online monitoring method and device that is pollution-free and loss-free for the gas to be measured.

[0007] The technical solution adopted by the present invention to achieve the above objectives is as follows:

[0008] A non-destructive online monitoring device based on spectroscopy comprises an air inlet, a first solenoid valve, a pressure reducing valve, an SO2 fluorescence detection unit, a CO infrared absorption detection unit, a CF4 infrared absorption detection unit, a first pressure sensor, a flow meter, a regulating valve, a second solenoid valve, and a collection tank connected in series via pipelines; one end of a third solenoid valve is connected to the first solenoid valve via a pipeline, and the other end of the third solenoid valve is connected to the rear end of the second solenoid valve via a pipeline; the first pressure sensor and a temperature sensor are connected to the upper part of the collection tank, and the temperature control unit is connected to the outer wall of the collection tank.

[0009] Furthermore, the regulating valve is an electrically operated regulating valve.

[0010] Furthermore, one end of the air inlet is connected to the existing vacuum device, and the other end of the air inlet is connected to the air inlet of the first solenoid valve via a pipeline. The other end of the first solenoid valve is connected to the air inlet of the SO2 fluorescence detection unit via a pipeline. The other end of the SO2 fluorescence detection unit is connected to the air inlet of the CO infrared absorption detection unit via a pipeline. The other end of the CO infrared absorption detection unit is connected to the air inlet of the CF4 infrared absorption detection unit via a pipeline. The other end of the CF4 infrared absorption detection unit is connected to the air inlet of the flow meter. A T-junction connects the CF4 infrared absorption detection unit and the flow meter, with the third end of the T-junction connected to the first pressure sensor. The air outlet of the flow meter is connected to the air inlet of the regulating valve, and the other end of the regulating valve is connected to the interface of the second solenoid valve via a pipeline. The other end of the second solenoid valve is connected to the gas port on the collection tank via a pipeline through a T-junction.

[0011] Furthermore, the first pressure sensor is installed on the upper part of the collection tank via a threaded connection, and the temperature sensor is installed on the upper part of the collection tank via an embedded connection; the inner surface of the temperature control unit is tightly connected to the outer wall of the collection tank.

[0012] A non-destructive online monitoring method based on spectroscopy includes the following steps:

[0013] Step 1. Preparation stage;

[0014] (1) Vacuuming: Vacuuming the online monitoring device;

[0015] (2) Cooling: Set the temperature of the gas inside the collection tank to -80℃;

[0016] Step 2. Detection phase;

[0017] The gas inside the collection tank is monitored until the pressure value stabilizes;

[0018] Step 3. Recharging phase;

[0019] After the temperature inside the collection tank is raised to 150°C, the gas is refilled into the SF6 insulating gas chamber.

[0020] Furthermore, the vacuuming process involves connecting the air inlet of the online monitoring device to a vacuuming device with a high-pressure gas pressure of 0.2 MPa (abs) or higher, opening all solenoid valves, including the first solenoid valve, the second solenoid valve, and the third solenoid valve; starting the vacuuming device to evacuate the online monitoring device of the present invention until the pressure detected by the first pressure sensor and the second pressure sensor is lower than 133 Pa, then closing all solenoid valves and stopping the vacuuming process.

[0021] The cooling process involves activating the temperature control unit to cool the collection tank until the temperature sensor detects that the gas temperature inside the collection tank is -70°C or below.

[0022] Furthermore, in the detection stage, the air inlet of the online monitoring device is connected to the air outlet of the SF6 insulating gas chamber. The first solenoid valve, the second solenoid valve, and the electric regulating valve are opened. The gas to be tested in the gas chamber flows through the first solenoid valve and is reduced to normal pressure by the pressure reducing valve. The temperature in the collection tank is reduced to -70°C or below. The saturated vapor pressure of SF6 at this temperature is calculated according to the saturated vapor pressure curve of formula (1) and confirmed to be lower than normal pressure. Under the action of pressure difference, the gas to be tested, which is reduced to normal pressure by the pressure reducing valve, flows into the collection tank. The concentration in the gas to be tested is detected by all detection units respectively. After each sensor completes the detection, the first solenoid valve is closed, and the gas in the detection unit enters the collection tank. The second solenoid valve is closed after the first pressure sensor detects that the pressure value is stable.

[0023] lg(10P)=(4.3514T-888.8485) / (T-0.5903) (1)

[0024] In equation (1): P is the liquefaction pressure of SF6 gas, MPa; T is the temperature of SF6 gas, K.

[0025] Furthermore, the saturated vapor pressure of the SF6 is less than 0.0946 MPa.

[0026] The concentration in the gas to be tested refers to the detection of the concentrations of SO2, CO, and CF4.

[0027] Furthermore, during the refilling stage, the temperature control unit raises the temperature inside the collection tank to 150°C or higher, converting the solidified SF6 into a gaseous state. Then, the third solenoid valve is opened to refill the gas inside the collection tank into the SF6 insulating gas chamber. Once the second pressure sensor detects that the pressure value has stabilized, the third solenoid valve is closed, and the temperature control unit is stopped.

[0028] The present invention has the following beneficial effects and advantages:

[0029] This invention provides a non-destructive online monitoring method and device based on spectrometry. The device has a simple structure and can flexibly monitor different gas chambers online. This monitoring method uses spectrometry to detect the concentration of SF6 decomposition products under stable atmospheric pressure, without chemical reactions or impurities. Specifically, ultraviolet fluorescence is used to detect SO2, and infrared spectroscopy is used to detect CO and CF4. This method causes no pollution or loss to the analyte gases, has relatively high sensitivity, and is suitable for online monitoring.

[0030] The online monitoring device of this invention can be filled with a certain amount of pure SF6 before use, allowing the same amount of SF6 released during the detection process to be refilled into the gas chamber, achieving non-destructive online monitoring of SF6 gas. The detection gas released from the gas chamber is first depressurized, and the flow rate is detected by a flow meter, which then controls the regulating valve to adjust the flow rate to the set value. The SF6 gas released from the detection gas chamber is collected in the tank using a cryogenic curing method. After detection is completed, the tank is heated in reverse to convert the solid SF6 into a gaseous state for refilling into the gas chamber. This avoids the gas chamber pressure from continuously dropping to the alarm pressure value and replaces the pump for gas refilling, preventing the introduction of impurities such as oil and gas into the refilled gas. Furthermore, this process does not require a pump as a power booster unit, ensuring that the insulating performance of the insulating gas in the gas chamber does not deteriorate. Attached Figure Description

[0031] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0032] Figure 1 This is a schematic diagram of the structure of the present invention.

[0033] In the picture:

[0034] Air inlet 1, first solenoid valve 2, pressure reducing valve 3, SO2 fluorescence detection unit 4, CO infrared absorption detection unit 5, CF4 infrared absorption detection unit 6, first pressure sensor 7, flow meter 8, regulating valve 9, second solenoid valve 10, second pressure sensor 11, temperature sensor 12, temperature control unit 13, collection tank 14, third solenoid valve 15. Detailed Implementation

[0035] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0036] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0037] The following reference Figure 1 The technical solutions of some embodiments of the present invention are described below.

[0038] Example 1

[0039] This invention provides an embodiment of a non-destructive online monitoring method and apparatus based on spectroscopy. For example... Figure 1As shown, Figure 1 This is a schematic diagram of the structure of the present invention.

[0040] exist Figure 1 In the process, the air inlet 1, the first solenoid valve 2, the pressure reducing valve 3, the SO2 fluorescence detection unit 4, the CO infrared absorption detection unit 5, the CF4 infrared absorption detection unit 6, the first pressure sensor 7, the flow meter 8, the regulating valve 9, the second solenoid valve 10, and the collection tank 14 are connected in series through pipelines; one end of the third solenoid valve 15 is connected to the first solenoid valve 2 through a pipeline, and the other end of the third solenoid valve 15 is connected to the rear end of the second solenoid valve 10 through a pipeline; the first pressure sensor 11 and the temperature sensor 12 are installed on the upper part of the collection tank 14; the temperature control unit 13 is attached to the outer wall of the collection tank 14.

[0041] The device of the present invention is further described as follows: one end of the air inlet 1 is connected to an existing vacuum device; the other end of the air inlet 1 is connected to the air inlet of the first solenoid valve 2 via a pipeline; the other end of the first solenoid valve 2 is connected to the air inlet of the SO2 fluorescence detection unit 4 via a pipeline; the other end of the SO2 fluorescence detection unit 4 is connected to the air inlet of the CO infrared absorption detection unit 5 via a pipeline; the other end of the CO infrared absorption detection unit 5 is connected to the air inlet of the CF4 infrared absorption detection unit 6 via a pipeline; and the other end of the CF4 infrared absorption detection unit 6 is connected to the flow rate... The air inlet of flow meter 8 is connected; a T-junction is connected between CF4 infrared absorption detection unit 6 and flow meter 8, and the third end of the T-junction is connected to the first pressure sensor 7; the air outlet of flow meter 8 is connected to the air inlet of regulating valve 9, and the air outlet of the other end of regulating valve 9 is connected to the interface of second solenoid valve 10 through a pipeline; the interface of the other end of second solenoid valve 10 is connected to the air port on collection tank 14 through a pipeline via a T-junction; the first pressure sensor 11 is installed on the upper part of collection tank 14 by threaded connection, and the temperature sensor 12 is installed on the upper part of collection tank 14 by embedding; the inner surface of temperature control unit 13 is in close contact with the outer wall of collection tank 14.

[0042] The regulating valve 9 is an electric regulating valve.

[0043] The temperature control unit 13 can be a refrigeration unit, which is connected to the outer wall of the collection tank 14.

[0044] The temperature sensor 12 detects the gas temperature inside the collection tank 14 and transmits the data to the circuit board. The circuit board controls the temperature control unit 13 to adjust the temperature of the collection tank 14; the first pressure sensor 7 is used to detect the gas pressure inside the SO2 fluorescence detection unit 4, the CO infrared absorption detection unit 5, and the CF4 infrared absorption detection unit 6; the second pressure sensor 11 is used to detect the gas pressure inside the collection tank 14.

[0045] Example 2

[0046] This invention provides another embodiment, which is a non-destructive online monitoring method based on spectroscopy. The method utilizes the non-destructive online monitoring device based on spectroscopy described in Embodiment 1 for online monitoring, specifically including the following steps:

[0047] Step 1. Preparation stage.

[0048] Includes: (1) Vacuuming: Vacuuming the online monitoring device;

[0049] Connect the air inlet 1 of the online monitoring device to a vacuum device with high-pressure gas of 0.2 MPa (abs) or higher, open all solenoid valves, including: first solenoid valve 2, second solenoid valve 10 and third solenoid valve 15; start the vacuum device to evacuate the online monitoring device of the present invention until the pressure detected by the first pressure sensor 7 and the second pressure sensor 11 is lower than 133 Pa, then close all solenoid valves and stop evacuating.

[0050] (2) Cooling: Reduce the gas temperature in the collection tank 14 to below -70℃.

[0051] The temperature control unit 13 is activated to cool the collection tank 14 until the temperature sensor 12 detects that the gas temperature inside the collection tank 14 is below -70°C.

[0052] Step 2. Detection phase.

[0053] Connect the inlet 1 of the online monitoring device to the outlet of the SF6 insulating gas chamber. Open the first solenoid valve 2, the second solenoid valve 10, and the electric regulating valve 9. The gas to be tested in the gas chamber flows through the first solenoid valve 2 and is reduced to atmospheric pressure by the pressure reducing valve 3. At this time, the temperature inside the collection tank 14 is below -70℃. According to the saturated vapor pressure curve of formula (1), the saturated vapor pressure of SF6 at this temperature is calculated to be below 0.0946MPa, which is below atmospheric pressure. Therefore, under the action of pressure difference, the gas to be tested, which has been reduced to atmospheric pressure by the pressure reducing valve 3, flows through the SO2 fluorescence detection unit 4, the CO infrared absorption detection unit 5, the CF4 infrared absorption detection unit 6, the flow meter 8, the regulating valve 9, and the second solenoid valve 10 into the collection tank 14. The SO2 fluorescence detection unit 4, CO infrared absorption detection unit 5, and CF4 infrared absorption detection unit 6 detect the concentrations of SO2, CO, and CF4 in the gas to be tested, respectively. After the first pressure sensor 7, the second pressure sensor 11, and the temperature sensor 12 complete their detection, the first solenoid valve 2 is closed, and the gas in the SO2 fluorescence detection unit 4, CO infrared absorption detection unit 5, and CF4 infrared absorption detection unit 6 enters the collection tank 14. The second solenoid valve 10 is closed after the first pressure sensor 7 detects that the pressure value has stabilized.

[0054] lg(10P)=(4.3514T-888.8485) / (T-0.5903) (1)

[0055] In equation (1): P is the liquefaction pressure of SF6 gas, MPa; T is the temperature of SF6 gas, K.

[0056] Step 3. Recharge phase.

[0057] The temperature control unit 13 raises the temperature of the collection tank 14 to 150°C or above, and the solidified SF6 is converted into a gaseous state. When the third solenoid valve 15 is opened, the gas in the collection tank 14 is refilled into the SF6 insulating gas chamber. When the second pressure sensor 11 detects that the pressure value is stable, the third solenoid valve 15 is closed and the temperature control unit 13 is stopped.

[0058] For example, the detection flow rate of SO2 fluorescence detection unit 4, CO infrared absorption detection unit 5, and CF4 infrared absorption detection unit 6 is 300 ml / min, and the detection time is 5 minutes. Therefore, approximately 1.5 L of gas needs to be released from the gas chamber for each detection. This means that after 10 detections, the collection tank will contain 15 L of SF6 gas. The collection tank 14 is designed with a volume of 300 ml. If all 1.5 L of SF6 gas is stored in collection tank 14, the density of SF6 gas at atmospheric pressure is 6.1 kg / m³. 3 According to formula (2), the gas density inside collection tank 14 is calculated to be 305 kg / m³. 3 .

[0059]

[0060] In equation (2): ρ is the gas density inside the collection tank, kg / m³ 3 m is the mass of gas in the collection tank, kg; V is the volume of the collection tank, m³. 3 .

[0061] When the temperature control unit 13 raises the temperature inside the collection tank 14 to 150℃ or above and refills the gas inside the collection tank 14, the gas pressure inside the collection tank 14 after stabilization is equal to the gas pressure inside the SF6 insulating gas chamber. Assuming the gas pressure is 0.7MPa (absolute pressure), the gas density inside the collection tank 14 after refilling is calculated to be 29.53kg / m³ according to formula (3). 3 .

[0062] Based on the above calculations, after refilling the gas in collection tank 14, the gas density inside collection tank 14 decreased to less than 1 / 10. This is equivalent to refilling more than 90% of the gas released from the gas chamber during the first 10 tests. Furthermore, the gas density inside collection tank 14 remained at 29.53 kg / m³ after each refill in subsequent tests. 3Without leakage or gas emission, the total gas volume in the gas chamber and the online monitoring device remains unchanged. Therefore, after subsequent testing, the online monitoring device can refill the gas released from the gas chamber into the gas chamber.

[0063] Example 3

[0064] This invention provides another embodiment, which is a non-destructive online monitoring method based on spectroscopy. It utilizes the non-destructive online monitoring device based on spectroscopy described in Embodiment 1 for online monitoring. Specifically, if it is necessary to refill all the gas released from the SF6 insulating gas chamber during the detection process to fully realize non-destructive online monitoring of the gas chamber on-site, the following operations can be performed:

[0065] Before using the device of this invention to monitor the gas chamber online, open the third solenoid valve 15 and, at room temperature, introduce pure SF6 gas into the collection tank 14 through the inlet 1 until the second pressure sensor 11 detects a pressure value of 0.4655 MPa. According to formula (3), the density of SF6 in the collection tank 14 at this time is calculated to be 29.53 kg / m³. 3 By employing the above method, the gas density in the collection tank 14 is consistent before and after testing, meaning the gas volume in the collection tank 14 is consistent before and after testing. This indicates that the online monitoring device refills all the gas released from the gas chamber during the testing process back into the gas chamber, achieving non-destructive online monitoring of SF6.

[0066] P=(RTB-A)ρ 2 +RTρ;

[0067] A = 73.882 × 10 -5 -5.132105×10 -7 ρ;

[0068] B = 2.50695 × 10 -3 -2.12283×10 -6 ρ;

[0069] R = 56.9502 × 10 -5 (3)

[0070] In equation (3): P is the liquefaction pressure of SF6 gas, ×0.1 MPa; T is the temperature of SF6 gas, K; ρ is the density of SF6 gas, kg / m³ 3 A, B, and R are all symbols used in the formula.

[0071] In this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "connection" and "fixed" should be interpreted broadly; for example, "connection" can mean a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0072] In the description of this invention, it should be understood that the indicated orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description, and is not intended to indicate or imply that the device or unit referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0073] In the description of this specification, the terms "one embodiment," "some embodiments," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0074] Finally, it should be noted that:

[0075] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A non-destructive online monitoring method based on spectroscopy, implemented using a non-destructive online monitoring device based on spectroscopy, characterized in that: The device consists of an air inlet (1), a first solenoid valve (2), a pressure reducing valve (3), an SO2 fluorescence detection unit (4), a CO infrared absorption detection unit (5), a CF4 infrared absorption detection unit (6), a first pressure sensor (7), a flow meter (8), a regulating valve (9), a second solenoid valve (10), and a collection tank (14), which are connected in series via pipelines. One end of a third solenoid valve (15) is connected to the first solenoid valve (2) via a pipeline, and the other end of the third solenoid valve (15) is connected to the rear end of the second solenoid valve (10) via a pipeline. The first pressure sensor (11) and the temperature sensor (12) are connected to the upper part of the collection tank (14), and the temperature control unit (13) is connected to the upper part of the collection tank (14). 14) on the outer wall; the regulating valve (9) is an electric regulating valve; one end of the air inlet (1) is connected to the existing vacuum device, the other end of the air inlet (1) is connected to the air inlet of the first solenoid valve (2) through a pipeline, the other end of the first solenoid valve (2) is connected to the air inlet of the SO2 fluorescence detection unit (4) through a pipeline, the other end of the SO2 fluorescence detection unit (4) is connected to the air inlet of the CO infrared absorption detection unit (5) through a pipeline, the other end of the CO infrared absorption detection unit (5) is connected to the air inlet of the CF4 infrared absorption detection unit (6) through a pipeline, the CF4 infrared absorption detection unit (6) The outlet of the other end is connected to the inlet of the flow meter (8); a three-way valve connects the CF4 infrared absorption detection unit (6) and the flow meter (8), and the third end of the three-way valve is connected to the first pressure sensor (7); the outlet of the flow meter (8) is connected to the inlet of the regulating valve (9), and the outlet of the other end of the regulating valve (9) is connected to the interface of the second solenoid valve (10) through a pipeline; the interface of the other end of the second solenoid valve (10) is connected to the air port on the collection tank (14) through a pipeline via a three-way valve; the first pressure sensor (11) is installed on the upper part of the collection tank (14) by a threaded connection, and the temperature sensor (12) is installed in the collection tank by an embedded method. 14) Upper part; the inner surface of the temperature control unit (13) is closely connected to the outer wall of the collection tank (14); including the following steps: Step 1. Preparation stage; (1) Vacuuming: vacuuming the online monitoring device; (2) Cooling: setting the gas temperature in the collection tank to -80℃; Step 2. Detection stage; detecting the gas in the collection tank until the pressure value is stable; Step 3. Refilling stage, the temperature control unit raises the temperature in the collection tank to 150℃ or above, converting the solidified SF6 into a gaseous state, opening the third solenoid valve, and refilling the gas in the collection tank into the SF6 insulating gas chamber. When the second pressure sensor detects that the pressure value is stable, the third solenoid valve is closed and the temperature control unit is stopped.

2. The non-destructive online monitoring method based on spectroscopy according to claim 1, characterized in that: the... Vacuuming: The air inlet of the online monitoring device is connected to a vacuuming device with high-pressure gas of 0.2 MPa (abs) or higher. All solenoid valves are opened, including the first solenoid valve, the second solenoid valve and the third solenoid valve. The vacuuming device is started to evacuate the online monitoring device of the present invention until the pressure detected by the first pressure sensor and the second pressure sensor is lower than 133 Pa. Then all solenoid valves are closed and the vacuuming is stopped. The cooling process involves activating the temperature control unit to cool the collection tank until the temperature sensor detects that the gas temperature inside the collection tank is -70°C or below.

3. The non-destructive online monitoring method based on spectroscopy according to claim 1, characterized in that: The detection stage involves connecting the air inlet of the online monitoring device to the air outlet of the SF6 insulating gas chamber, opening the first solenoid valve, the second solenoid valve, and the electric regulating valve, allowing the gas to be tested in the gas chamber to flow through the first solenoid valve and be reduced to atmospheric pressure by the pressure reducing valve; allowing the temperature in the collection tank to drop to -70°C or below, calculating the saturated vapor pressure of SF6 at this temperature according to the saturated vapor pressure curve of formula (1), and confirming that it is below atmospheric pressure; under the action of the pressure difference, the gas to be tested, which has been reduced to atmospheric pressure by the pressure reducing valve, flows into the collection tank; the concentration in the gas to be tested is detected by all detection units respectively, and after each sensor completes the detection, the first solenoid valve is closed, and the gas in the detection unit enters the collection tank until the first pressure sensor detects that the pressure value is stable, and then the second solenoid valve is closed; （1）; In equation (1): P is the liquefaction pressure of SF6 gas, MPa; T is the temperature of SF6 gas, K.

4. The non-destructive online monitoring method based on spectroscopy according to claim 3, characterized in that: The saturated vapor pressure of the SF6 is less than 0.0946 MPa.

5. The non-destructive online monitoring method based on spectroscopy according to claim 3, characterized in that: The concentration in the gas to be tested refers to the detection of the concentrations of SO2, CO, and CF4.

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