Laser monitoring device

Abstract

The present application provides a laser monitoring device, which is applied to the online monitoring of the operation failure of oil-immersed equipment, and includes an oil circuit unit, a degassing unit, a gas circuit unit, a measuring unit and a control unit; the oil circuit unit is used to obtain a cooling oil sample from the oil-immersed equipment; the degassing unit is used to degas the cooling oil sample to obtain a gas sample to be tested; the gas circuit unit is used to input the gas sample to be tested into the measuring unit; the measuring unit includes a laser, the laser includes a laser diode for generating a narrow-bandwidth laser and a dual optical isolator for filtering and adjusting the polarization direction of the narrow-bandwidth laser, and the measuring unit is used to use the narrow-bandwidth laser corresponding to the characteristic gas to respectively measure the concentration of the characteristic gas in the gas sample to be tested, so as to determine the operation failure of the oil-immersed equipment. The laser monitoring device can realize real-time and online monitoring of the characteristic gas generated in the oil-immersed equipment.

Description

Technical Field

[0001] The present application relates to the field of oil-immersed equipment monitoring, and in particular to a laser monitoring device. Background Art

[0002] Oil-immersed equipment is a type of equipment that is immersed in protective oil for a long time and works. The more common oil-immersed equipment is oil-immersed power transformers. Oil-immersed power transformers refer to transformers immersed in oil, and oil is used to protect the transformers. However, during the use of oil-immersed transformers, due to heat and discharge and other reasons, the oil-paper insulation material in the oil-filled electrical equipment will age and decompose, producing a variety of low-molecular hydrocarbons and gases such as carbon dioxide and carbon monoxide that dissolve in the oil. Therefore, the fault and abnormal state of the oil-immersed voltage transformer can be detected according to the type and content of gas in the oil. The existing method for detecting gas in oil is mainly gas chromatography. Gas chromatography refers to manual inspection of the transformer, and the extraction of oil samples and centralized analysis in the laboratory using a gas chromatograph. This method has problems such as high labor and time costs, the test elements are sensitive to oil vapor and humidity, poor environmental adaptability, low detection efficiency, and inability to achieve real-time monitoring.

[0003] Therefore, the existing detection equipment for oil-immersed power transformers has technical problems such as high manpower and time costs, poor environmental adaptability, low detection efficiency, and inability to monitor gas concentration in real time, and needs to be improved. Summary of the invention

[0004] The present application provides a laser monitoring device for solving the technical problems of existing oil-immersed power transformer detection equipment, such as high manpower and time costs, poor environmental adaptability, low detection efficiency, and inability to monitor oil and gas status in real time. The device can realize real-time, online monitoring of operating faults of oil-immersed equipment.

[0005] The embodiment of the present application provides a laser monitoring device, which includes an oil circuit unit, a degassing unit, a gas circuit unit, a measuring unit and a control unit; wherein:

[0006] The oil circuit unit is used to obtain a cooling oil sample from the oil-immersed device and input the cooling oil sample into the degassing unit under the control of a sampling enable signal sent to the oil circuit unit by the control unit;

[0007] The degassing unit is used to degas the cooling oil sample to obtain a gas sample to be tested, and input the gas sample to be tested into the gas circuit unit under the control of the degassing enable signal sent thereto by the control unit;

[0008] The gas circuit unit is used to input the gas sample to be measured into the measurement unit under the control of the measurement enable signal sent to it by the control unit;

[0009] The measuring unit comprises a laser, the laser comprises a laser diode for generating narrow-bandwidth laser light and a dual optical isolator arranged on a laser path emitted by the laser diode, the dual optical isolator is used to filter and adjust the polarization direction of the narrow-bandwidth laser light so that the narrow-bandwidth laser light is emitted as parallel light, and the measuring unit is used to respectively measure the concentration of the characteristic gas in the gas sample to be measured using the narrow-bandwidth laser light corresponding to the characteristic gas;

[0010] The control unit is also used to determine the operation failure of the oil-immersed device according to the characteristic gas concentration in the gas sample to be tested.

[0011] The beneficial effects of the present application are as follows: the laser monitoring device provided by the present application includes an oil circuit unit, a degassing unit, a gas circuit unit, a measuring unit and a control unit connected to the oil-immersed equipment. Through the joint action of each unit module, real-time and online monitoring of the characteristic gas generated in the oil-immersed equipment is realized, so as to timely and accurately determine the operating fault type of the oil-immersed equipment; at the same time, a double optical isolator is arranged on the path of the narrow-bandwidth laser emitted by the laser diode to filter the narrow-bandwidth laser and adjust the polarization direction, thereby improving the parallelism of the narrow-bandwidth laser and the consistency of the narrow-bandwidth laser frequency, which is beneficial to improving the accuracy and sensitivity of the test unit in detecting the characteristic gas concentration; in addition, the test unit can also accurately control the laser diode to operate within a preset temperature range according to the light leakage parameters and real-time temperature of the laser diode, thereby ensuring that the laser diode outputs a narrow-bandwidth laser with stable frequency and power, further improving the accuracy and sensitivity of the test unit in detecting the characteristic gas concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0013] Figure 1 is a schematic diagram of a scene of a laser monitoring system provided in an embodiment of the present application;

[0014] Figure 2 is a structural principle diagram of a laser monitoring device provided in an embodiment of the present application;

[0015] Figure 3 is a schematic diagram of the structure of a laser monitoring device provided in an embodiment of the present application;

[0016] Figure 4 is a structural principle diagram of a measurement unit provided in an embodiment of the present application;

[0017] Figure 5 A schematic diagram of a first structure of a measurement unit provided in an embodiment of the present application;

[0018] Figure 6 A second structural schematic diagram of a measurement unit provided in an embodiment of the present application;

[0019] Figure 7 is a schematic diagram of the structure of a laser provided in an embodiment of the present application;

[0020] Figure 8 It is a schematic diagram of the connection structure between the voltage processing module, the thermistor and the monitoring photodiode in the measurement unit provided in an embodiment of the present application;

[0021] Fig. 9 is a schematic diagram of the structure of the temperature control module provided in an embodiment of the present application;

[0022] Fig.10 is a schematic diagram of a temperature control circuit in a temperature control module provided in an embodiment of the present application;

[0023] Fig.11 A circuit schematic diagram of a photoelectric conversion circuit in a signal processor provided in an embodiment of the present application;

[0024] Fig.12 A circuit schematic diagram of a first signal amplifying circuit in a signal processor provided in an embodiment of the present application;

[0025] Fig.13 A circuit schematic diagram of a bandpass filter circuit in a signal processor provided in an embodiment of the present application;

[0026] Fig.14 A circuit schematic diagram of a second signal amplifying circuit in a signal processor provided in an embodiment of the present application;

[0027] Fig.15 A circuit schematic diagram of an A / D conversion circuit in a signal processor provided in an embodiment of the present application. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0029] See also Figure 1 and Figure 2 , Figure 1 A schematic diagram of a laser monitoring system according to an embodiment of the present application. Figure 2It is a structural principle diagram of the laser monitoring device provided in the embodiment of the present application. The laser monitoring system may include an oil-immersed device 11 and a laser monitoring device 12, and the laser monitoring device 12 is connected to the oil-immersed device 11 through a pipeline. Among them, the oil-immersed device 11 includes an oil-immersed transformer, etc., and the oil-immersed transformer includes a transformer and oil for cooling the transformer, and the oil-immersed transformer is used to change the transmission voltage in the line; the laser monitoring device 12 includes an oil circuit unit 121, a degassing unit 122, a gas circuit unit 123, a measuring unit 124 and a control unit 125, etc., which are used to monitor the operating status of the oil-immersed device 11 to determine the operating failure of the oil-immersed device 11.

[0030] It should be noted that Figure 1 The system scenario diagram shown is only an example. The server and scenario described in the embodiment of the present application are intended to more clearly illustrate the technical solution of the embodiment of the present application, and do not constitute a limitation on the technical solution provided by the embodiment of the present application. It is known to those skilled in the art that with the evolution of the system and the emergence of new business scenarios, the technical solution provided by the embodiment of the present application is also applicable to similar technical problems. The following are detailed descriptions. It should be noted that the description order of the following embodiments is not intended to limit the preferred order of the embodiments.

[0031] The laser monitoring device 12 can realize real-time monitoring of the gas in the cooling oil of the oil-immersed equipment 11 to determine the type of fault that already exists in the oil-immersed equipment 11, or the type of fault that is about to occur; for the type of fault determined to be about to occur, the laser monitoring device 12 can also estimate the time when the fault type will occur.

[0032] In the laser monitoring device 12, the oil circuit unit 121 is used to obtain a cooling oil sample from the oil-immersed device 11 under the control of the sampling enable signal sent to it by the control unit 125, and input the cooling oil sample into the degassing unit 122. Optionally, an oil valve and an oil pump are provided in the pipeline connecting the oil circuit unit 121 and the oil-immersed device 11. When the control unit 125 sends the sampling enable signal to the oil circuit unit 121, the oil valve between the oil circuit unit 121 and the oil-immersed device 11 is opened, and the oil pump extracts the cooling oil sample from the oil-immersed device 11 into the oil circuit unit 121, wherein the volume of the extracted cooling oil sample is set according to demand, for example, 60 ml of cooling oil sample is extracted from the oil-immersed device 11. The oil circuit unit 121 inputs the extracted cooling oil sample into the degassing unit 122 for the next stage of degassing operation.

[0033] The degassing unit 122 is used to degas the cooling oil sample to obtain the gas sample to be tested, and input the gas sample to be tested into the gas circuit unit 123, under the control of the degassing enable signal sent to it by the control unit 125. Optionally, the degassing unit 122 can degas the cooling oil sample by headspace degassing, or by using a degassing membrane tube. The headspace degassing method refers to allowing the cooling oil sample to enter the oil tank, discharging the gas above the oil tank, avoiding the original gas in the oil tank from affecting the gas sample to be tested, forming a negative pressure in the oil tank, and then heating the bottom of the oil tank and stirring the cooling oil at the same time to separate the gas sample to be tested in the cooling oil. The degassing method using a degassing membrane tube refers to first extracting the gas in the degassing membrane tube to prevent the original gas in the degassing membrane tube from affecting the gas sample to be tested in the cooling oil sample, and forming a negative pressure in the degassing membrane tube, and then allowing the cooling oil sample to enter the degassing membrane tube, and the degassing membrane tube is provided with a polytetrafluoroethylene nano-separation membrane, and the polytetrafluoroethylene nano-separation membrane is used to separate the gas sample to be tested in the cooling oil sample. The degassing unit 122 is also used to input the obtained gas sample to be tested into the gas circuit unit 123 for the next step of operation.

[0034] The gas circuit unit 123 is used to input the gas sample to be detected into the measuring unit 124 under the control of the measurement enable signal sent to it by the control unit 125. Optionally, the gas circuit unit 123 includes a gas valve and an air pump. When the control unit 125 sends the measurement enable signal to the gas circuit unit 123, the gas valve in the gas circuit unit 123 is opened, and the air pump is started to input the gas sample to be detected in the gas circuit unit 123 into the measuring unit 124, so as to perform the next stage of gas composition and content detection operation.

[0035] The measuring unit 124 is used to detect the composition and content of the gas sample to be detected under the control of the measurement enable signal sent to it by the control unit 125. Optionally, the measuring unit 124 includes a photoacoustic spectrometer, which uses a narrow bandwidth laser corresponding to the characteristic gas to respectively measure the concentration of each characteristic gas in the gas sample to be detected, and the characteristic gas includes hydrogen, carbon monoxide, methane, acetylene, ethylene, carbon dioxide, and ethane. The working principle of the photoacoustic spectrometer is: the gas sample to be detected is irradiated with a laser having a specific frequency, and the gas corresponding to the laser of the specific frequency in the gas sample to be detected absorbs the laser energy and is in an excited state, and then returns to the ground state by releasing heat energy. In the process of releasing heat energy, the surrounding medium is periodically heated at a specific frequency, thereby generating a periodic pressure wave, and then the pressure wave is collected by a device such as a microphonic pickup to form a data curve. The area enclosed by the data curve represents the content of the gas corresponding to the laser of the specific frequency in the gas sample to be detected, thereby realizing qualitative and quantitative analysis of the gas sample to be detected. It should be noted that the so-called narrow-bandwidth laser refers to a laser beam with a small laser frequency fluctuation range and good laser frequency consistency; in the embodiment of the present application, a narrow-bandwidth laser is used to detect the concentration of the characteristic gas. Compared with a laser with ordinary bandwidth, the sensitivity and accuracy of characteristic gas detection are improved, which is conducive to timely and accurate detection of characteristic gases, and determination or early prediction of operating failures of oil-immersed equipment.

[0036] In one embodiment, the characteristic gas refers to the gas separated from the cooling oil that causes the oil-immersed equipment to malfunction; different types of characteristic gases and different concentrations of different types of characteristic gases cause different types of operating failures of the oil-immersed equipment, and when the concentrations of different types of characteristic gases are low, the operating failure of the oil-immersed equipment will not occur, but the operating failure of the oil-immersed equipment can be predicted by predicting each type of characteristic gas. The characteristic gases that cause the oil-immersed equipment to malfunction include hydrogen, carbon monoxide, methane, acetylene, ethylene, carbon dioxide, and ethane. When measuring the concentration of the characteristic gas in the gas sample to be tested, there may be only one characteristic gas, that is, only one characteristic gas has a concentration greater than 0, while the concentrations of the other characteristic gases are 0.

[0037] See also Figure 3 , Figure 3 : is a schematic diagram of the structure of the laser monitoring device provided in an embodiment of the present application. The process of the laser monitoring device obtaining the gas sample to be measured from the oil-immersed device and transmitting it to the measuring unit includes the following stages:

[0038] The first stage is mainly to pump the pressure in the oil tank 210 to the first target pressure, so that a negative pressure is formed between the oil-immersed device 11 and the oil tank 210, so that the cooling oil sample in the oil-immersed device 11 enters the oil tank 210. First, the control unit controls the first drive motor 223 in the air extraction device 220 in the degassing unit to drive the piston 222 to suck the gas in the oil tank 210 into the cylinder 221 in the air extraction device 220, and discharges the gas in the cylinder 221 through the air circuit unit, so that a negative pressure is formed in the oil tank 210. The air circuit unit includes a first air valve 310, a second air valve 320, a third air valve 330 and a fourth air valve 340. For example, the first port 311 and the second port 312 in the first gas valve 310 are connected, and the gas extraction device 220 extracts part of the gas in the oil tank 210 into the cylinder 221, and then the first port 311 and the third port 313 in the first gas valve 310 are connected, and the gas in the cylinder 221 is discharged through the third gas valve 330. Repeat the above steps to reduce the pressure in the oil tank 210 to the first target pressure. For example, the external atmospheric pressure is the standard atmospheric pressure of 100Kpa, and the first target pressure in the oil tank 210 can be 2Kpa. The pressure in the oil tank 210 can be directly obtained by the pressure sensor 230.

[0039] In the second stage, the pressure difference between the oil tank 210 and the oil-immersed device 11 causes the cooling oil sample in the oil-immersed device 11 to enter the oil tank 210. First, the control unit controls the first valve S1 to open so that the oil-immersed device 11 and the oil tank 210 are connected. Due to the pressure difference between the oil-immersed device 11 and the oil tank 210, the cooling oil sample in the oil-immersed device 11 enters the oil tank 210; when the cooling oil sample in the oil tank 210 reaches the height measured by the upper liquid level sensor 211, the control unit controls the first valve S1 to close. The height of the upper liquid level sensor 211 can be set according to the height of the oil tank 210, for example, the height of the upper liquid level sensor 211 can be 75% of the height of the oil tank 210, or the height of the upper liquid level sensor 211 can be set according to the stirring speed of the stirring member 213 in the oil tank 210, for example, when the stirring speed of the stirring member 213 is 2400rpm, the height of the upper liquid level sensor 211 can be 75% of the height of the oil tank 210, when the stirring speed of the stirring member 213 is 3000rpm, the height of the upper liquid level sensor 211 can be 70% of the height of the oil tank 210, To avoid the liquid level height of the cooling oil sample exceeding the critical height of the oil tank 210 when being stirred due to the excessive rotation speed of the stirring member 213, the stirring mechanism 213 is driven to rotate by a rotating magnet 214 connected to a driving motor 215; or, the height of the upper liquid level sensor 211 can be set according to the stirring temperature of the cooling oil sample in the oil tank 210. For example, when the stirring temperature of the cooling oil sample is 50°C, the height of the upper liquid level sensor 211 can be 75% of the height of the oil tank 210; when the stirring temperature of the cooling oil sample is 70°C, the height of the upper liquid level sensor 211 can be 70% of the height of the oil tank 210.

[0040] In the third stage, the gas to be tested in the cooling oil sample enters the measuring unit through the air extraction device 220 and the gas path unit. First, the control unit controls the first port 311 and the second port 312 of the first gas valve 310 to be connected, so that the air extraction device 220 is connected to the oil tank 210, and then the control unit controls the stirring member 213 to stir the cooling oil sample in the oil tank 210, and then the air extraction device 220 extracts the gas to be tested in the cooling oil sample into the cylinder 221 in the air extraction device 220, and then the control unit controls the first port 311 and the second port 312 of the first gas valve 310 to be disconnected, and controls the first port 311 and the third port 313 of the first gas valve 310 to be connected, opens the second gas valve 320 and the fourth gas valve 340, and closes the third gas valve 330, so that the gas to be tested enters the measuring unit through the gas path unit; secondly, repeat the above steps until the pressure in the oil tank 210 reaches the second target pressure, the above air extraction step stops, and the first gas valve 310 is in a closed state. The second target pressure may be equal to or different from the first target pressure, and the specific value of the second target pressure may be limited according to actual conditions.

[0041] In the fourth stage, the cooling oil sample in the oil tank 210 flows back into the oil-immersed device 11. First, the control unit controls the second valve S2 to connect the oil-immersed device 11 with the oil tank 210, and then controls the oil pump S3 to pump the cooling oil sample in the oil tank 210 into the oil-immersed device 11. When the liquid level of the cooling oil sample in the oil tank 210 reaches the height measured by the lower liquid level sensor 212 in the oil tank 210, the control unit controls the oil pump S3 to stop working and close the second valve S2. The height measured by the lower liquid level sensor 212 can be the bottom of the oil tank 210, and the specific position is not limited in detail in this application.

[0042] According to the working process of the above-mentioned laser monitoring device, since the gas to be tested in the oil tank 210 needs to be degassed within the target degassing time, the stirring speed of the stirring member 213 directly affects the degassing rate of the gas to be tested. For sample oils of different viscosities or temperatures, and at different stirring speeds, the degassing rate of the gas to be tested in the sample oil from the oil-gas separation device in the operating status monitoring device of the oil-immersed device 11 is different. However, the existing operating status monitoring device of the oil-immersed device 11 is usually unable to accurately set the stirring speed of the stirring member 213 in the oil-gas separation device, resulting in a technical problem that the gas to be tested in the sample oil cannot be separated from the oil-gas separation device within the target time. This embodiment mainly determines the first stirring speed of the stirring member 213 by the predicted concentration of the gas to be tested in the cooling oil sample.

[0043] In one embodiment, due to the influence of various uncertain factors, the concentration value of the gas to be measured actually obtained by the measuring unit is generally greater than the initial predicted concentration of this embodiment. Since the cooling oil samples belong to the same batch of cooling oil samples, the stirring speed of the stirring member 213 of the next cycle can be adjusted according to the difference between the characteristic gas concentration value of the current cycle and the predicted concentration. This step may include: obtaining a first difference between the concentration of the characteristic gas in the current measurement cycle and the predicted concentration of the gas to be measured in the cooling oil sample; judging whether the first difference is greater than a fourth threshold; if the first difference is greater than the fourth threshold, according to the correlation between the concentration, degassing time and stirring speed, based on the first difference and the target degassing time, determining the second stirring speed of the stirring member 213 of the next measurement cycle; if the first difference is less than the fourth threshold, the first stirring speed of the stirring member 213 is the target stirring speed of the stirring member 213 in the current measurement cycle.

[0044] In one embodiment, when the first difference between the concentration of the characteristic gas in the current measurement cycle and the predicted concentration of the gas to be measured in the cooling oil sample is greater than a fourth threshold value, the stirring speed needs to be adjusted, and the stirring speed of the stirring member 213 has an upper limit, namely, a critical stirring speed. If the difference between the concentration of the characteristic gas in the previous measurement cycle and the predicted concentration of the gas to be measured in the cooling oil sample is large, the stirring speed of the stirring member 213 needs to be increased to a second stirring speed exceeding the critical stirring speed, and then other adjustment factors need to be adjusted to compensate for the limitation of the stirring speed.

[0045] Specifically, this embodiment uses the correlation between temperature and stirring speed to adjust the stirring temperature of the stirring member 213, that is, the temperature of the cooling oil sample, to compensate for the limitation of the stirring speed when the stirring speed cannot be increased. This step may include: determining whether the second stirring speed is greater than the critical stirring speed of the stirring member 213; if the second stirring speed is greater than the critical stirring speed of the stirring member 213, the critical stirring speed is the target stirring speed of the stirring member 213 for the next measurement cycle; according to the correlation between temperature, concentration and stirring speed, based on the critical stirring speed and the concentration of the characteristic gas, the initial temperature of the cooling oil sample in the next measurement cycle is determined; if the second stirring speed is less than the critical stirring speed of the stirring member 213, the second stirring speed is the target stirring speed of the stirring member 213 for the next measurement cycle.

[0046] In one embodiment, when the first difference between the concentration of the characteristic gas in the current measurement cycle and the predicted concentration of the gas to be measured in the cooling oil sample is greater than a fourth threshold value, the stirring speed needs to be adjusted; and after the stirring speed of the stirring member 213 is increased, the liquid level of the cooling oil sample in the corresponding oil tank 210 will increase. Since the oil tank 210 is connected to the corresponding oil and gas pipeline, the increase in the liquid level of the cooling oil sample may cause the cooling oil sample to enter other devices through the oil and gas pipeline. Therefore, the cooling oil sample in the oil tank 210 has a critical liquid level to prevent the cooling oil sample from entering other components. Therefore, this step may include: obtaining the cooling oil sample in the current measurement cycle The liquid level of the cooling oil sample; judging whether the liquid level of the cooling oil sample is greater than the critical liquid level of the cooling oil sample; if the liquid level of the cooling oil sample is greater than the critical liquid level of the cooling oil sample, the critical liquid level is the liquid level of the cooling oil sample in the next measurement cycle, and according to the correlation between the liquid level, concentration and stirring speed, based on the critical liquid level and the concentration of the characteristic gas, determining the stirring speed of the stirring member 213 in the next measurement cycle; if the liquid level of the cooling oil sample is less than the critical liquid level of the cooling oil sample, the second stirring speed is the target stirring speed of the stirring member 213 in the next measurement cycle.

[0047] In one embodiment, the degassing time of the current measurement cycle is also an important reference value for setting the stirring speed. The degassing time represents the degassing rate of the gas to be measured in the cooling oil sample. If the degassing time is short, the degassing rate of the gas to be measured is large, corresponding to a larger stirring speed, and the stirring speed of the next measurement cycle needs to be reduced to make the degassing time of the gas to be measured equal to the target degassing time; if the degassing time is long, the degassing rate of the gas to be measured is small, corresponding to a smaller stirring speed, and the stirring speed of the next measurement cycle needs to be increased to make the degassing time of the gas to be measured equal to the target degassing time. Therefore, this step may include: obtaining the degassing time of the gas to be measured in the cooling oil sample in the current measurement cycle; judging whether the degassing time in the current measurement cycle is equal to the target degassing time; if the degassing time in the current measurement cycle is not equal to the target degassing time, according to the correlation between the concentration, degassing time and stirring speed, based on the concentration of the characteristic gas in the current measurement cycle and the target degassing time, determine the stirring speed of the stirring member 213 in the next measurement cycle.

[0048] In one embodiment, the suction pressure and suction speed of the suction device 220 in the oil tank 210 can also be used as variables for adjusting the degassing speed, which will not be described in detail in this application.

[0049] In this step, the concentration of the characteristic gas in the gas sample to be measured obtained by the measuring unit is compared with the predicted concentration of the gas to be measured, and the stirring speed or / temperature of the next measuring cycle is adjusted according to the difference between the two, so that the gas to be measured in the cooling oil sample in the next measuring cycle is separated from the degassing unit within the target degassing time.

[0050] For further information, see Figure 4 , Figure 4 1 is a schematic diagram of the structure of the measuring unit provided in the embodiment of the present application. The measuring unit 124 includes a laser 101, a photoacoustic cell 102 and a signal processor 103. Among them, the laser 101 is used to generate a narrow-bandwidth laser of a specific frequency; the photoacoustic cell 102 is a flow channel for the gas sample to be measured in the measuring unit 124, and is also the place where the narrow-bandwidth laser emitted by the laser 101 and the gas to be measured have energy transfer effects, and a micro-pickup is arranged inside the photoacoustic cell 102, which is used to collect the photoacoustic signal generated after the narrow-bandwidth laser is irradiated to the characteristic gas, and convert the photoacoustic signal into an electrical signal and transmit it to the signal processor 103; the signal processor 103 is used to amplify, denoise and other processing operations on the electrical signal transmitted by the photoacoustic cell 101, and generate a data curve, and output the concentration of the characteristic gas in the gas sample to be measured.

[0051] like Figure 5 , Figure 5 This is a schematic diagram of a first structure of a measuring unit 124 provided in an embodiment of the present application, wherein the measuring unit 124 includes a plurality of detection units 21 that do not interfere with each other.

[0052] Specifically, the gas circuit unit 123 is used to control the gas sample to be measured to flow from the gas circuit unit 123 into all the detection units 21 according to the measurement enable signal.

[0053] The detection unit 21 is used to measure the concentration of the characteristic gas using the narrow bandwidth laser corresponding to the characteristic gas to be detected by the detection unit 21 according to the measurement enable signal.

[0054] It should be noted that the characteristic gas to be measured by the detection unit 21 refers to the characteristic gas that the detection unit 21 needs to measure; the detection unit 21 controls the photoacoustic spectrometer in the detection unit 21 according to the measurement enable signal to use a narrow bandwidth laser corresponding to the characteristic gas to be measured by the detection unit 21.

[0055] It should be noted that each of the detection units 21 can independently realize the measurement of a characteristic gas. The gas sample to be measured is flushed into multiple detection units 21. The characteristic gas in the gas sample to be measured can be measured simultaneously by using multiple detection units 21 that do not interfere with each other. Different types of characteristic gases correspond to narrow-bandwidth lasers of different wavelengths. Different detection units 21 can use narrow-bandwidth lasers of different wavelengths to measure different types of characteristic gases in the gas sample to be measured, thereby being able to simultaneously measure the concentrations of multiple characteristic gases in the gas sample to be measured.

[0056] In one embodiment, a plurality of the detection units 21 are connected in series, which can also be understood as a plurality of the detection units 21 being connected in cascade; the gas circuit unit 123 is used to control the gas sample to be tested to flow from the gas circuit unit 123 into all the detection units 21 in sequence according to the measurement enable signal.

[0057] The two adjacent detection units 21 are connected via a connecting pipe L, and a valve is provided on the connecting pipe L, so that the gas samples to be tested can flow into the detection units 21 in sequence, and at the same time, it can be ensured that all detection units 21 do not interfere with each other.

[0058] It should be noted that each of the detection units 21 is provided with an air inlet Lb and an air outlet Lc. When the measuring unit 124 includes m detection units 21, the m detection units 21 are connected in cascade, and the air inlet Lb of the detection unit 21 located at the first stage can also be connected to the gas circuit unit 123 through a connecting pipe L provided with a valve, so as to be connected to the gas sample to be tested flowing out of the gas circuit unit 123; after the gas sample to be tested flows into the detection unit 21 of the first stage, the gas sample to be tested flows into all the detection units 21 in turn through the connecting pipe L; the air outlet Lc of the detection unit 21 located at the last stage can also be connected to the gas circuit unit 123 through a connecting pipe L provided with a valve, so as to flow the gas sample to be tested after the measurement from the detection unit 21 into the gas circuit unit 123, and the gas sample to be tested after the measurement is processed by the gas circuit unit 123 is discharged, so as to avoid the gas to be tested from polluting the environment.

[0059] The air inlet Lb and the air outlet Lc may be located at the same side of the detection unit 21 , so that two adjacent detection units 21 are connected via the connecting pipe L.

[0060] like Figure 6 , Figure 6 This is a schematic diagram of a second structure of the measurement unit 124 provided in an embodiment of the present application.

[0061] In one embodiment, the measuring unit 124 further includes a box K, and all the detection units 21 are disposed in the box K.

[0062] In one embodiment, the box body K may be a cubic structure, and a plurality of slide rails K1 for supporting the detection unit 21 are arranged on the inner wall of the box body K. The plurality of slide rails K1 are arranged at intervals along the height direction of the box body K, and the detection unit 21 corresponds to the slide rails K1 one by one; the detection unit 21 is slidably connected to the slide rails K1 along the length direction of the slide rails K1 to facilitate the inspection and replacement of the detection unit 21. For example, when a detection unit 21 fails, the staff can pull the detection unit 21 out of the box body K for inspection. When the detection unit 21 cannot be repaired, a normally functioning detection unit 21 can be used to replace the faulty detection unit 21 to avoid the measurement unit 124 from failing to work when a single detection unit 21 fails.

[0063] In one embodiment, the box body K is further provided with an interface K2, at least one of which is connected to the control unit 125, and the detection unit 21 is provided with a connector K3 matching the interface K2, and the connector K3 is plugged into the interface K2. An information interaction bridge is built by connecting the interface K2 and the connector K3 to realize information interaction between the control unit 125 and the detection unit 21, thereby realizing the control of the detection unit 21 by the control unit 125 and the information feedback of the detection unit 21 to the control unit 125.

[0064] For further information, see Figure 7 , Figure 7 1 is a schematic diagram of the structure of the laser provided in the embodiment of the present application. The laser 101 includes a laser diode 1011, and the laser diode 1011 is used to generate a narrow-bandwidth laser, and the narrow-bandwidth laser transfers energy with the gas sample to be measured to generate a photoacoustic signal. It should be noted that because the narrow-bandwidth laser has a stable and consistent laser frequency, it can accurately transfer energy to a single characteristic gas without interacting with other types of gases, thereby maintaining a high accuracy of the detection result of the characteristic gas concentration, and because the interference of other types of gases on the detection result is eliminated, the sensitivity of the detection of the concentration of a single characteristic gas is correspondingly improved.

[0065] Optionally, the laser diode 1011 can generate narrow-bandwidth lasers of multiple frequencies, each of which corresponds to a characteristic gas. For example, the characteristic gases to be detected in the embodiment of the present application may include hydrogen, carbon monoxide, methane, acetylene, ethylene, carbon dioxide, and ethane. When detecting the concentration of characteristic gases, the laser diode 1011 can sequentially emit narrow-bandwidth lasers of specific frequencies corresponding to each characteristic gas to detect the concentration of each characteristic gas in sequence. It should be noted that the embodiment of the present application does not limit the order in which the measurement unit 124 is used to detect multiple characteristic gases.

[0066] Please continue reading Figure 7 In one embodiment, the laser 101 further includes a dual optical isolator 1015 disposed on the laser path emitted by the laser diode 1011, and the dual optical isolator 1015 is used to filter and adjust the polarization direction of the laser so that the narrow bandwidth laser emitted by the laser diode 1011 forms parallel light emission.

[0067] Specifically, the dual optical isolator 1015 includes a first optical isolator L1 and a second optical isolator L2, the distance between the first optical isolator L1 and the second optical isolator L2 is less than or equal to a first threshold, and the light transmission axis direction of the second optical isolator L2 is consistent with the polarization direction of the laser passing through the first optical isolator L1. Optionally, the first threshold can be 0. When the first threshold is 0, the first optical isolator L1 is set close to the second optical isolator L2, and the parallelism and consistency of the narrow-bandwidth laser passing through the dual optical isolator 1015 are the best; the first threshold can also be a non-zero constant, for example, the first threshold can be 5 microns, that is, a distance can be kept between the first optical isolator L1 and the second optical isolator L2, but the distance must be kept within a certain range and cannot be too large, so as to ensure that the dual optical isolator 1015 has a better effect on the parallelism adjustment of the narrow-bandwidth laser. It should be noted that when the narrow bandwidth laser emitted by the laser diode 1011 passes through the first optical isolator L1, the first optical isolator L1 performs the first filtering and polarization direction adjustment on it to filter out part of the non-parallel stray light in the narrow bandwidth laser and rotate the polarization direction of the narrow bandwidth laser by a first angle; then the narrow bandwidth laser continues to pass through the second optical isolator L2, and the second optical isolator L2 performs the second filtering and polarization direction adjustment on it to further filter the non-parallel stray light in the narrow bandwidth laser and continue to rotate the polarization direction of the narrow bandwidth laser by a second angle. After the double filtering and polarization direction adjustment of the dual optical isolator 1015, the narrow bandwidth laser emitted by the laser diode 1011 is formed into parallel light and emitted, and the frequency consistency and stability of the narrow bandwidth laser are also improved after the double filtering; in addition, after the two polarization direction adjustments of the dual optical isolator 1015, part of the reflected light generated by the narrow bandwidth laser in the laser 101 cannot pass through the dual optical isolator 1015 again to the laser diode 1011, thereby eliminating the influence of the reflected light on the performance of the laser diode 1011.

[0068] Further, the first optical isolator L1 includes a first polarizer L11 and a first magneto-optical rotator L12, the second optical isolator L2 includes a second polarizer L21 and a second magneto-optical rotator L22, the transmission axis direction of the second polarizer L21 is consistent with the polarization direction of the laser light passing through the first optical isolator L1. The first polarizer L11 performs a first filtering of non-parallel stray light in the narrow-bandwidth laser light, the first magneto-optical rotator L12 rotates the polarization direction of the narrow-bandwidth laser light by the first angle, the second polarizer L21 performs a second filtering of non-parallel stray light in the narrow-bandwidth laser light, and the second magneto-optical rotator L22 continues to rotate the polarization direction of the narrow-bandwidth laser light passing through the first magneto-optical rotator L12 by the second angle. Optionally, the sum of the first angle and the second angle is equal to 90 degrees, that is, the polarization direction of the narrow-bandwidth laser emitted from the dual optical isolator 1015 is perpendicular to the polarization direction of the narrow-bandwidth laser emitted into the dual optical isolator 1015, completely eliminating the possibility of reflected light passing through the dual optical isolator 1015 again and emitting to the laser diode 1011.

[0069] Furthermore, the laser 101 further includes an optical window 1016 disposed on the laser path emitted by the laser diode 1011, and the dual optical isolator 1015 is disposed between the laser diode 1011 and the optical window 1016, and the light transmission axis direction of the optical window 1016 is consistent with the polarization direction of the laser passing through the dual optical isolator 1015. The optical window 1016 further filters the narrow-bandwidth laser emitted from the dual optical isolator 1015, thereby improving the polarization direction consistency and parallelism of the narrow-bandwidth laser.

[0070] Furthermore, the laser 101 further includes an optical lens 1017 disposed between the laser diode 1011 and the dual optical isolator 1015 , and the optical lens 1017 is used to preliminarily adjust the parallelism of the narrow-bandwidth laser emitted from the laser diode 1011 .

[0071] The laser 101 also includes a housing, which has a cavity, in which the laser diode 1011, the dual optical isolator 1015, and the optical lens 1017 are all disposed, and an optical window 1016 is disposed on the housing, which is a channel for the narrow-bandwidth laser to be emitted from the cavity. A pin area 101a is also disposed on the housing, and the pin area 101a is an interface end for connecting the internal circuit of the laser 101 with the external circuit.

[0072] Further, in the embodiment of the present application, the measuring unit 124 can control the laser diode 1011 to work within a preset temperature range according to the light leakage parameter of the laser diode 1011 and the real-time temperature of the laser diode 1011. It should be noted that the real-time temperature of the laser diode 1011 will affect the working voltage of the laser diode 1011, and then affect the stability of the laser diode 1011 emitting narrow-bandwidth laser. The laser diode 1011 can only output a narrow-bandwidth laser beam with stable frequency and power within a specific temperature range, and only a narrow-bandwidth laser beam with stable frequency and power can accurately detect the characteristic gas concentration. The laser diode 1011 provided in the embodiment of the present application has an optimal operating temperature T. The closer the actual operating temperature of the laser diode 1011 is to the optimal operating temperature T, the higher the stability of the frequency and power of the narrow-bandwidth laser output by the laser diode 1011, and the higher the accuracy of the corresponding characteristic gas concentration detection. It should be noted that the optimal operating temperature T can have different values ​​due to different lasers, and the optimal operating temperature T is not limited here.

[0073] The measuring unit 124 controls the working temperature of the laser diode 1011 in real time based on the light leakage parameters and real-time temperature of the laser diode 1011, so as to ensure that the laser diode 1011 works within a preset temperature range. The preset temperature range can be a temperature range formed by a specific temperature value fluctuating around the optimal working temperature T. The laser diode 1011 can output a narrow-bandwidth laser with a frequency and power that meet the requirements within this temperature range. The embodiment of the present application uses the light leakage parameters and real-time surface temperature of the laser diode 1011 as indicators for temperature control of the laser diode 1011, so as to achieve accurate control of the working temperature of the laser diode 1011, so that the working temperature of the laser diode 1011 is maintained within a temperature range of 0.001°C before and after the optimal working temperature T, thereby ensuring a high level of characteristic gas concentration detection accuracy.

[0074] In one embodiment, the laser 101 further includes a thermistor 1012, which is used to measure the real-time temperature of the laser diode 1011; the distance between the thermistor 1012 and the laser diode 1011 is less than or equal to a second threshold value, so as to ensure the accuracy of the real-time temperature measurement of the laser diode 1011 by the thermistor 1012. Optionally, the second threshold value may be 0, when the second threshold value is 0, the thermistor 1012 is set close to the laser diode 1011, at which time the accuracy of the real-time temperature measurement of the laser diode 1011 by the thermistor 1012 is the highest; the second threshold value may also be a non-zero constant, for example, the second threshold value may be 5 microns, that is, a distance may be kept between the thermistor 1012 and the laser diode 1011, but the distance must be kept within a certain range and cannot be too large, so as to ensure that the thermistor 1012 can accurately measure the real-time temperature of the laser diode 1011.

[0075] In one embodiment, the laser 101 further includes a monitoring photodiode 1013, which is disposed on the back side of the laser emitting surface of the laser diode 1011 and is used to detect light leakage of the narrow-bandwidth laser emitted by the laser diode 1011. It should be noted that the narrow-bandwidth laser generated by the laser diode 1011 is emitted from its laser emitting surface, and at the same time, part of the laser deviates from the emission direction and is captured by the monitoring photodiode 1013. The light leakage parameter of the laser diode 1011 is determined by the amount of laser captured by the monitoring photodiode 1013.

[0076] For further information, see Figure 8 , Figure 8This is a schematic diagram of the connection structure of the voltage processing module, the thermistor and the monitoring photodiode in the measurement unit provided in the embodiment of the present application. The measurement unit 124 also includes a voltage processing module U, and the voltage processing module U includes a first voltage acquisition module U1. The first voltage acquisition module U1 is used to obtain the real-time working voltage of the laser diode 1011 through the thermistor 1012. The specific method is: the first voltage acquisition module U1 obtains the real-time voltage and real-time current of the thermistor 1012, and compares the real-time voltage and real-time current to obtain the real-time resistance value of the thermistor 1012; pre-establish a first comparison between the resistance value of the thermistor 1012, the temperature of the thermistor 1012 and the temperature of the laser diode 1011 A data table is prepared and stored in the first voltage acquisition module U1. After obtaining the real-time resistance value of the thermistor 1012, the first voltage acquisition module U1 calls the first data comparison table to obtain the real-time temperature of the laser diode 1011. A second data comparison table between the temperature of the laser diode 1011 and the operating voltage of the laser diode 1011 is pre-established and stored in the first voltage acquisition module U1. After obtaining the real-time temperature of the laser diode 1011, the first voltage acquisition module U1 calls the second data comparison table to obtain the real-time operating voltage of the laser diode 1011.

[0077] The voltage processing module U also includes a second voltage acquisition module U2, which is used to obtain the real-time loss voltage of the laser diode 1011 by monitoring the photodiode 1013. The specific method is: the second voltage acquisition module U2 obtains the real-time voltage and real-time current of the monitoring photodiode 1013, and compares the real-time voltage and the real-time current to obtain the real-time resistance of the monitoring photodiode 1013; a third data comparison table between the resistance of the monitoring photodiode 1013 and the leakage parameter of the laser diode 1011 is pre-established and stored in the second voltage acquisition module U2. After obtaining the real-time resistance of the monitoring photodiode 1013, the second voltage acquisition module U2 calls the third data comparison table to obtain the leakage parameter of the laser diode 1011; a fourth data comparison table between the leakage parameter of the laser diode 1011 and the loss voltage of the laser diode 1011 is pre-established and stored in the second voltage acquisition module U2. After obtaining the leakage parameter of the laser diode 1011, the second voltage acquisition module U2 calls the fourth data comparison table to obtain the real-time loss voltage of the laser diode 1011.

[0078] The voltage processing module U further includes a third voltage acquisition module U3, and the third voltage acquisition module U3 is used to calculate the effective working voltage of the laser diode 1011 according to the real-time working voltage of the laser diode 1011 obtained by the first voltage acquisition module U1 and the real-time loss voltage of the laser diode 1011 obtained by the second voltage acquisition module U2. The specific calculation method is: the effective working voltage of the laser diode 1011 is equal to the difference between the real-time working voltage of the laser diode 1011 and the real-time loss voltage of the laser diode 1011.

[0079] It should be noted that the entire narrow-bandwidth laser generated by the laser diode 1011 can be divided into two parts. One part of the narrow-bandwidth laser is emitted in a straight line from the light-emitting surface of the laser diode 1011, and this part of the narrow-bandwidth laser is called collimated light; the other part of the narrow-bandwidth laser is not emitted in a straight line, but is captured by the monitoring photodiode 1013, and this part of the narrow-bandwidth laser is called leakage light; the real-time operating voltage of the laser diode 1011 obtained by the first voltage acquisition module U1 through the thermistor 1012 is the voltage used by the laser diode 1011 to generate the entire narrow-bandwidth laser; the real-time loss voltage of the laser diode 1011 obtained by the second voltage acquisition module U2 through the monitoring photodiode 1013 is the voltage used by the laser diode 1011 to generate the leakage light part; the difference between the voltage used by the laser diode 1011 to generate the entire narrow-bandwidth laser and the voltage used to generate the leakage light part is the voltage used by the laser diode 1011 to generate the collimated light part, which is the effective operating voltage of the laser diode 1011 obtained by the third voltage acquisition module U3. It should be understood that the effective operating voltage of the laser diode 1011 is a direct factor affecting the frequency and power of the narrow-bandwidth laser used for gas analysis, and maintaining it within a predetermined voltage range is the key to ensuring that the measuring unit 124 accurately measures the concentration of characteristic gases in the gas sample to be measured; and the temperature of the laser diode 1011 will affect the effective operating voltage of the laser diode 1011. Therefore, if the effective operating voltage of the laser diode 1011 is to be maintained stable within a preset voltage range, the temperature of the laser diode 1011 needs to be controlled.

[0080] See also Fig. 9 and Fig.10 , Fig. 9 is a schematic diagram of the structure of the temperature control module provided in the embodiment of the present application, Fig.10It is a schematic diagram of the temperature control circuit in the temperature control module provided in the embodiment of the present application. In one embodiment, the measuring unit 124 also includes a temperature control module, and the temperature control module is used to control the temperature of the laser diode 1011 according to the effective working voltage of the laser diode 1011, so that the laser diode 1011 works within a preset temperature range. Specifically, the temperature control module includes a voltage controller 201, a voltage stabilizer 202, a voltage comparator 203, a microprogram controller 204 and a thermostat 205, wherein the voltage controller 201, the voltage stabilizer 202, the voltage comparator 203 and the microprogram controller 204 constitute the temperature control circuit TC of the temperature control module. The voltage controller 201 is used to provide a reference voltage, which is the optimal value of the effective working voltage of the laser diode 1011. That is, when the effective working voltage of the laser diode 1011 is equal to the reference voltage, the laser diode 1011 can emit a narrow-bandwidth laser of a specific frequency and power, and is used to detect the concentration of the characteristic gas in the gas sample to be measured, so that the measurement accuracy and sensitivity of the measurement unit 124 are both optimal; in addition, the closer the effective working voltage of the laser diode 1011 is to the reference voltage, the higher the accuracy and sensitivity of the measurement unit 124 for measuring the concentration of the characteristic gas. The input end of the voltage regulator 202 is electrically connected to the output end of the voltage controller 201, and is used to stabilize the reference voltage provided by the voltage controller 201, eliminate the fluctuation of the reference voltage, and improve the stability and consistency of the reference voltage. The first input terminal of the voltage comparator 203 is electrically connected to the output terminal of the voltage regulator 202, and the second input terminal of the voltage comparator 203 is electrically connected to the output terminal of the third voltage acquisition module U3. The voltage comparator 203 is used to compare the effective working voltage of the laser diode 1011 with the voltage value of the reference voltage provided by the voltage controller 201, and transmit the comparison result to the microprogram controller 204. The input end of the microprogram controller 204 is electrically connected to the output end of the voltage comparator 203, and is used to receive and analyze the comparison result, and send a corresponding temperature adjustment instruction to the thermostat 205 according to the comparison result; specifically, when the comparison result is that the effective working voltage of the laser diode 1011 is less than the reference voltage, the microprogram controller 204 sends a temperature adjustment instruction to the thermostat 205 to reduce the temperature of the laser diode 1011; when the comparison result is that the effective working voltage of the laser diode 1011 is greater than the reference voltage, the microprogram controller 204 sends a temperature adjustment instruction to the thermostat 205 to increase the temperature of the laser diode 1011; when the comparison result is that the effective working voltage of the laser diode 1011 is equal to the reference voltage, the microprogram controller 204 sends a temperature adjustment instruction to the thermostat 205 to maintain the temperature of the laser diode 1011.The input end of the thermostat 205 is electrically connected to the output end of the microprogram controller 204, and is used to adjust the temperature of the laser diode 1011 under the control of the temperature adjustment instruction, so that the laser diode 1011 works within a preset temperature range.

[0081] Continue reading Figure 7 and Fig. 9 As shown, in one embodiment, the thermostat 205 includes a semiconductor refrigerator 1014, and the distance between the semiconductor refrigerator 1014 and the laser diode 1011 is less than or equal to a third threshold value, so as to ensure that the semiconductor refrigerator 1014 can accurately and sensitively regulate the temperature of the laser diode 1011. Optionally, the third threshold value can be 0. When the third threshold value is 0, the semiconductor refrigerator 1014 is set close to the laser diode 1011, and the semiconductor refrigerator 1014 has the highest accuracy and sensitivity in regulating the temperature of the laser diode 1011. The third threshold value can also be a non-zero constant, for example, the third threshold value can be 10 microns, that is, a distance can be kept between the semiconductor refrigerator 1014 and the laser diode 1011, but the distance must be kept within a certain range and cannot be too large, so as to ensure that the semiconductor refrigerator 1014 can accurately and sensitively regulate the real-time temperature of the laser diode 1011.

[0082] The embodiment of the present application obtains the real-time loss voltage of the laser diode through the light leakage parameter of the laser diode, and obtains the real-time operating voltage of the laser diode through the real-time temperature of the laser diode, and uses the real-time operating voltage and the real-time loss voltage to obtain the effective operating voltage of the laser diode, and uses the comparison result of the effective operating voltage with the reference voltage as the basis for temperature control of the laser diode, and according to the influence of the temperature of the laser diode on the effective operating voltage of the laser diode, the laser diode is regulated to operate within a preset temperature range, thereby ensuring that the effective operating voltage of the laser diode is maintained within the preset voltage range, and further ensuring that the laser diode emits a narrow-bandwidth laser with stable frequency and power, thereby improving the accuracy and sensitivity of the measurement unit in detecting the concentration of characteristic gases in the gas sample to be measured.

[0083] See also Figure 4 , Figures 11 to 15 In one embodiment, the signal processor 103 includes:

[0084] Photoelectric conversion circuit 1031, the photoelectric conversion circuit 1031 is used to convert the photoacoustic signal into an electrical signal. The electrical signal at this time is an analog signal. Fig.11 ;

[0085] The first signal amplifying circuit 1032 is connected to the output end of the photoelectric conversion circuit 1031 and is used to amplify the analog signal. Fig.12 ;

[0086] Bandpass filter circuit 1033, the input end of the bandpass filter circuit 1033 is connected to the output end of the first signal amplifying circuit 1032, and the bandpass filter circuit 1033 is used to filter the signal output by the first signal amplifying circuit 1032, and its purpose is to filter out useless high-frequency and low-frequency signals and extract useful intermediate-frequency signals, see Fig.13 ;

[0087] The second signal amplifying circuit 1034 has an input end connected to the output end of the bandpass filtering circuit 1033, and transmits the output signal of the bandpass filtering circuit 1033 to the A / D conversion circuit 1035 after amplification. This is equivalent to a secondary amplification of the signal, and the purpose is to make the signal obtained by the A / D conversion circuit 1035 more accurate and easier to convert. Fig.14 ;as well as

[0088] The A / D conversion circuit 1035, the input end of the A / D conversion circuit 1035 is connected to the output end of the second signal amplification circuit 1034, and is used to convert the analog quantity output by the second signal amplification circuit 1034 into a digital quantity, which is a process of converting a discrete quantity into a continuous quantity, and transmit the obtained digital quantity to the concentration adjustment unit, see Fig.15 .

[0089] Please continue reading Figure 1After the measuring unit 124 uses the narrow bandwidth laser corresponding to the characteristic gas to measure the concentration of the characteristic gas in the gas sample to be measured, the control unit 125 determines the operating failure of the oil-immersed device 11 according to the concentration of the characteristic gas in the gas sample to be measured. When predicting the operation failure of the oil-immersed equipment 11, considering that the fault types of the oil-immersed equipment 11 are different and the corresponding types of characteristic gases are different, the operation failure type of the oil-immersed equipment can be preliminarily judged in advance, and the fault type is predicted by analyzing the type of characteristic gas that appears. After predicting the fault type, it is determined whether the characteristic gas corresponding to the fault type is formed, and after the characteristic gas corresponding to the fault type is formed, the fault type is determined; the specific steps include: determining the type of the characteristic gas according to the concentration of the characteristic gas; presetting the standard concentration change curve corresponding to each fault type, predicting the operation failure type of the oil-immersed equipment according to the standard concentration change curve and the type of the characteristic gas, and obtaining a prediction result; predicting the occurrence of other characteristic gases corresponding to the preset fault type according to the prediction result and the concentration change curve of the characteristic gas; when the other characteristic gases corresponding to the preset fault type appear, determining the operation failure type of the oil-immersed equipment; specifically, the standard concentration change curve corresponding to each fault type is preset to contain the curve of each characteristic gas, and the type of characteristic gas corresponding to each fault type is sorted into a table, as shown in Table 1 below:

[0090]

[0091] Table 1

[0092] It can be seen from Table 1 that when the fault type of the oil-immersed equipment 11 is different, the types of characteristic gases measured from the gas sample to be tested are different. For example, when the fault type is cooling oil overheating, the corresponding characteristic gas types are hydrogen, ethylene, methane and ethane; when the fault type is cooling oil and paper overheating, the corresponding characteristic gas types are hydrogen, carbon monoxide, carbon dioxide, ethylene, methane, and ethane; when the fault type is cooling oil and partial discharge in paper insulation, the corresponding characteristic gas types are hydrogen, carbon monoxide, carbon dioxide, acetylene, and methane. , methane, ethane; when the fault type is spark discharge in the cooling oil, the corresponding characteristic gases are hydrogen and acetylene; when the fault type is arc discharge in the cooling oil, the corresponding characteristic gases are hydrogen, acetylene, ethylene, methane and ethane; when the fault type is arc discharge in the cooling oil and paper, the corresponding characteristic gases are hydrogen, carbon monoxide, carbon dioxide, acetylene, ethylene, methane and ethane; when the fault type is damp paper or bubbles in the cooling oil, the corresponding characteristic gas is hydrogen; "-" in Table 1 indicates that the concentration of the characteristic gas in this fault type is 0.

[0093] Based on Table 1, when hydrogen, carbon monoxide, carbon dioxide, ethylene, methane, and ethane are detected, it can be judged that the operating fault type of the oil-immersed equipment may be overheating of the cooling oil and paper or arc discharge in the cooling oil and paper. According to the prediction, and based on the concentration change curve of the characteristic gas, the formation of acetylene, a characteristic gas corresponding to the preset fault type, is predicted. When acetylene is formed, the operating fault type of the oil-immersed equipment is determined to be arc discharge in the cooling oil and paper. When acetylene is not formed, the operating fault type of the oil-immersed equipment is determined to be overheating of the cooling oil and paper, thereby determining the operating fault type of the oil-immersed equipment.

[0094] It should be noted that the characteristic gas can be any one of methane, ethane, ethylene, acetylene, carbon monoxide, carbon dioxide and hydrogen. When measuring the gas sample to be tested, it is necessary to measure the concentration of all types of characteristic gases in the gas sample to be tested; the standard gas sample includes methane, ethane, ethylene, acetylene, carbon monoxide, carbon dioxide and hydrogen, and the sample standard concentration of the characteristic gas in the standard gas sample is a known concentration.

[0095] The laser monitoring device provided in the embodiment of the present application can realize real-time, online monitoring of characteristic gases in oil-immersed equipment. Compared with the existing method of manual sampling and sending to the laboratory for characteristic gas detection, it greatly improves the timeliness and accuracy of equipment failure warning, and saves time and labor costs. In some special periods, such as during major epidemics, there are fewer workers on duty. The detection of characteristic gases through the existing manual sampling method is not only time-effective, but also difficult to complete the test due to the small number of staff, and the accuracy of the test cannot be guaranteed. At this time, the use of the laser monitoring device provided in the embodiment of the present application for characteristic gas monitoring further reflects its advantages of low time and labor costs, and timely and accurate detection.

[0096] In summary, the laser monitoring device provided in the embodiment of the present application includes an oil circuit unit, a degassing unit, a gas circuit unit, a measuring unit and a control unit connected to the oil-immersed device. Through the joint action of each unit module, real-time and online monitoring of the characteristic gas generated in the oil-immersed device is realized, so as to timely and accurately determine the operating fault type of the oil-immersed device; at the same time, a double optical isolator is arranged on the path of the narrow-bandwidth laser emitted by the laser diode to filter the narrow-bandwidth laser and adjust the polarization direction, thereby improving the parallelism of the narrow-bandwidth laser and the consistency of the narrow-bandwidth laser frequency, which is beneficial to improving the accuracy and sensitivity of the test unit in detecting the characteristic gas concentration; in addition, the test unit can also accurately control the laser diode to operate within a preset temperature range according to the light leakage parameters and real-time temperature of the laser diode, thereby ensuring that the laser diode outputs a narrow-bandwidth laser with stable frequency and power, further improving the accuracy and sensitivity of the test unit in detecting the characteristic gas concentration.

[0097] It should be noted that although the present application is disclosed as above with specific embodiments, the above embodiments are not intended to limit the present application. Ordinary technicians in this field can make various changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be based on the scope defined in the claims.

Claims

1. A laser monitoring device, characterized in that: Applied to the online monitoring of oil-immersed equipment operation failure, the laser monitoring device includes an oil circuit unit, a degassing unit, a gas circuit unit, a measuring unit and a control unit; wherein: The oil circuit unit is used to obtain a cooling oil sample from the oil-immersed device and input the cooling oil sample into the degassing unit under the control of a sampling enable signal sent to the oil circuit unit by the control unit; The degassing unit is used to degas the cooling oil sample to obtain a gas sample to be tested, and input the gas sample to be tested into the gas circuit unit under the control of the degassing enable signal sent thereto by the control unit; The gas circuit unit is used to input the gas sample to be measured into the measurement unit under the control of the measurement enable signal sent to it by the control unit; The measuring unit comprises a laser, wherein the laser comprises a laser diode for generating narrow-bandwidth laser light and a dual optical isolator arranged on a laser path emitted by the laser diode, wherein the dual optical isolator is used to filter and adjust the polarization direction of the narrow-bandwidth laser light so that the narrow-bandwidth laser light is emitted as parallel light, and the measuring unit is used to respectively measure the concentration of the characteristic gas in the gas sample to be measured using the narrow-bandwidth laser light corresponding to the characteristic gas, and the measuring unit is further used to control the laser diode to operate within a preset temperature range according to the light leakage parameter of the laser diode and the real-time temperature of the laser diode; The control unit is also used to determine the operation failure of the oil-immersed device according to the characteristic gas concentration in the gas sample to be tested; The dual optical isolator includes a first optical isolator and a second optical isolator, the distance between the first optical isolator and the second optical isolator is less than or equal to a first threshold, and the light transmission axis direction of the second optical isolator is consistent with the polarization direction of the laser passing through the first optical isolator.

2. The laser monitoring device according to claim 1, characterized in that: The first optical isolator comprises a first polarizer and a first magneto-optical rotator, wherein the first magneto-optical rotator is used to rotate the polarization direction of the narrow-bandwidth laser emitted by the laser diode by a first angle; The second optical isolator comprises a second polarizer and a second magneto-optical rotator, wherein the second magneto-optical rotator is used to rotate the polarization direction of the narrow-bandwidth laser light passing through the first magneto-optical rotator by a second angle; The transmission axis direction of the second polarizer is consistent with the polarization direction of the laser light passing through the first optical isolator.

3. The laser monitoring device according to claim 1, characterized in that: The laser also includes an optical window arranged on the narrow-bandwidth laser path emitted by the laser diode, the dual optical isolator is arranged between the laser diode and the optical window, and the transmission axis direction of the optical window is consistent with the polarization direction of the narrow-bandwidth laser passing through the dual optical isolator.

4. The laser monitoring device according to claim 1, characterized in that: The laser includes a thermistor, and a distance between the thermistor and the laser diode is less than or equal to a second threshold; The measuring unit also includes a voltage processing module, which is used to obtain the real-time resistance value of the thermistor according to the real-time voltage and real-time current of the thermistor, obtain the real-time temperature of the laser diode according to the real-time resistance value of the thermistor, and obtain the real-time operating voltage of the laser diode according to the real-time temperature of the laser diode.

5. The laser monitoring device according to claim 4, characterized in that: The laser further comprises a monitoring photodiode, which is used to detect light leakage of the narrow-bandwidth laser emitted by the laser diode; The voltage processing module is also used to obtain the real-time resistance value of the monitoring photodiode according to the real-time voltage and real-time current of the monitoring photodiode, obtain the leakage parameter of the laser diode according to the real-time resistance value of the monitoring photodiode, and obtain the real-time loss voltage of the laser diode according to the leakage parameter of the laser diode.

6. The laser monitoring device according to claim 5, characterized in that: The voltage processing module is further used to obtain the effective working voltage of the laser diode by subtracting the real-time working voltage of the laser diode from the real-time loss voltage of the laser diode.

7. The laser monitoring device according to claim 6, characterized in that: The measuring unit also includes a temperature control module, which is used to compare the voltage value of the effective working voltage of the laser diode with the voltage value of the reference voltage, and adjust the temperature of the laser diode through a thermostat according to the comparison result so that the laser diode operates within a preset temperature range.

8. The laser monitoring device according to claim 7, characterized in that: The thermostat comprises a semiconductor refrigerator, and a distance between the semiconductor refrigerator and the laser diode is less than or equal to a third threshold.

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