In-situ detection device and method for dissolved gas in oil

Abstract

The invention relates to an in-situ detection device and method for gas dissolved in oil. Comprising a degassing module and a detection module, and the degassing module is in direct contact with transformer oil and used for separating dissolved gas in the transformer oil in a membrane degassing mode to obtain separated gas; the detection module comprises a distributed feedback laser, a coupler, a photoacoustic cell, a plurality of photoelectric detectors, an AD conversion module and an FPGA core control and demodulation system; the method comprises the following steps: introducing separated gas, exciting the separated gas in a photoacoustic cell by multiple beams of laser to generate a photoacoustic or optical signal, receiving the signal, demodulating the signal after AD conversion to obtain Raman scattering spectrum data, and analyzing the Raman scattering spectrum data to obtain the concentration of each component gas in the separated gas. And judging the internal fault type of the transformer according to the concentration of each component gas. The device can be in direct contact with transformer oil for gas separation detection, and interference possibly brought by a traditional detection method in the oil sample extraction and analysis process is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of power equipment detection devices, and particularly relates to an in-situ detection device and method for dissolved gases in oil. Background Art

[0002] When a transformer operates for a long time, faults such as oil overheating, partial discharge, and spark discharge may occur inside the transformer, causing the insulating oil (paper) to crack and generate characteristic gases such as CO, CO2, CH4, C2H4, C2H6, C2H2, and H2 to dissolve in the transformer insulating oil. When an overheating fault, a discharge fault, or internal insulation moisture occurs inside the transformer, the content of the decomposed gases will increase rapidly. Most of these gases dissolve in the insulating oil, and a small part rises to the surface of the insulating oil and enters the gas relay. It has been verified that the amount of various components of the gases in the oil is directly related to the nature and degree of the fault. The monitoring device for dissolved gases in transformer oil has been widely used in domestic transformers, especially extra-high voltage large transformers.

[0003] Existing monitoring devices for dissolved gases in oil-immersed transformers mostly use the dynamic headspace method for oil-gas separation. However, due to the large volume, many components, complex maintenance, and vibration interference with the transformer operation of such oil-gas separation devices, it is only possible to pump the oil inside the transformer out to the outside for oil-gas separation. The transfer of the insulating oil not only increases the time for oil-gas separation but also may consume the capacity of the insulating oil inside the transformer or contaminate the insulating oil, thus bringing additional safety hazards to the operation and maintenance personnel of the transformer. Summary of the Invention

[0004] The purpose of the present invention is to solve the deficiencies existing in the above background art and provide an in-situ detection device and method for dissolved gases in oil.

[0005] The technical solution adopted by the present invention is: an in-situ detection device for dissolved gases in oil, including a degassing module and a detection module,

[0006] The degassing module is in direct contact with the transformer oil and is used to separate the dissolved gases in the transformer oil by membrane degassing to obtain separated gases;

[0007] The detection module includes a distributed feedback laser, a coupler, a photoacoustic cell, a plurality of photodetectors, an AD conversion module, and an FPGA core control and demodulation system; the photoacoustic cell is used to introduce the separated gas, and the distributed feedback laser is used to emit a frequency-modulated light beam that is divided into multiple laser beams by the coupler to excite the separated gas in the photoacoustic cell to generate photoacoustic or optical signals. The plurality of photodetectors are used to receive the signals and transmit the signals to the AD conversion module and then input them into the FPGA core control and demodulation system for demodulation to obtain Raman scattering spectrum data. By analyzing the Raman scattering spectrum data, the concentrations of the component gases in the separated gas are obtained, and the internal fault type of the transformer is judged according to the concentrations of the component gases.

[0008] Preferably, the degassing module and the detection module are integrally installed inside a customized flange, and the customized flange is connected to the device under test through a matching interface.

[0009] The above technical solution is directly connected to the transformer through the built-in customized flange. The system does not require frequent external maintenance and adjustment, reduces manual intervention, and ensures the coherence and automation of the detection process. The integrated design of the degassing module, the detection module, and the flange not only saves space but also improves the stability and reliability of the system. The close cooperation of all key components can improve the detection efficiency and the real-time performance of data transmission.

[0010] Preferably, the frequency-modulated light beam is divided into a first laser, a second laser, and a third laser by the coupler. The first laser and the second laser are respectively used to excite the separated gas in the photoacoustic cell to generate photoacoustic or optical signals, and the third laser is used for light intensity calibration.

[0011] Preferably, the first laser and the second laser respectively act on different incident positions of the photoacoustic cell to improve the detection sensitivity of the separated gas. The third laser is used to calibrate and compensate for the drift of the first laser and the second laser in light intensity and phase, thereby improving the detection accuracy.

[0012] The FPGA core control and demodulation system sends the Raman scattering spectrum data to the host computer, and the host computer calculates the concentrations of at least characteristic gases including CO, CO2, CH4, C2H4, C2H6, C2H2, and H2.

[0013] Preferably, the fault type includes at least one of oil overheating, partial discharge, and spark discharge.

[0014] Preferably, the internal fault type of the transformer is diagnosed according to the concentration threshold or gas ratio of each gas, and when a predetermined trigger condition is met, a fault warning or alarm signal is sent to the monitoring system to realize continuous monitoring and early fault diagnosis of the operating state of the transformer.

[0015] An in-situ detection method for dissolved gases in oil, comprising

[0016] Adopting a membrane degassing method to separate the dissolved gases in transformer oil to obtain separated gases, exciting the separated gases with multiple laser beams to generate photoacoustic or optical signals, demodulating the signals to obtain Raman scattering spectrum data, analyzing the Raman scattering spectrum data to obtain the concentrations of each component gas in the separated gases, and judging the types of internal faults of the transformer according to the concentrations of each component gas.

[0017] More preferably, the multiple laser beams are divided into a first laser, a second laser and a third laser. The first laser and the second laser are respectively used to excite the separated gases in the photoacoustic cell to generate photoacoustic or optical signals, and the third laser is used for optical intensity calibration.

[0018] More preferably, the first laser and the second laser respectively act on different incident positions of the photoacoustic cell into which the separated gases are introduced to improve the detection sensitivity of the separated gases. The third laser is used to calibrate and compensate for the drift of the first laser and the second laser in terms of optical intensity and phase, thereby improving the detection accuracy.

[0019] More preferably, the Raman scattering spectrum data is sent to the host computer, and the host computer calculates the concentrations of at least characteristic gases including CO, CO2, CH4, C2H4, C2H6, C2H2, and H2.

[0020] More preferably, the types of faults include at least one of oil overheating, partial discharge and spark discharge.

[0021] More preferably, the types of transformer faults are diagnosed according to the concentration thresholds or gas ratios of each gas, and when a predetermined trigger condition is met, a fault warning or alarm signal is sent to the monitoring system to realize continuous monitoring of the operating state of the transformer and early fault diagnosis.

[0022] The present invention does not require pumping the oil inside the transformer to the outside for oil-gas separation and does not transfer the insulating oil. It belongs to an in-situ detection method. The in-situ dissolved gas detection device provided by the present invention is directly in contact with the transformer oil, uses membrane degassing technology to separate the dissolved gases in the oil for gas separation and detection, avoids the interference in the process of oil sample extraction and analysis that may be brought by traditional detection methods, and the in-situ detection method is more reliable, fast, and pollution-free, avoiding errors or delays that may occur during the sample transmission process; uses a laser to excite and a photodetector to detect, realizes the accurate concentration determination of each component of the separated gas, and can quickly judge the type of internal fault of the transformer by analyzing these concentrations and combining with the transformer fault diagnosis standard, so as to provide a safer and more reliable on-line monitoring means for the power system, improve the fault detection accuracy, realize early warning, enhance the system stability, reduce the occurrence of faults, and enhance the equipment safety, which helps to improve the overall reliability and operation efficiency of the transformer equipment and has a positive impact on the stability and safety of the power system. Description of the Drawings

[0023] Figure 1 Schematic diagram of the connection between the degassing module and the detection module in Embodiment 1 of the present invention;

[0024] Figure 2 Schematic diagram of an in-situ dissolved gas detection device in Embodiment 1 of the present invention;

[0025] Figure 3 Schematic diagram of the connection of internal components of the detection module in Embodiment 1 of the present invention;

[0026] Figure 4 Schematic diagram of the platform of the detection method in Embodiment 1 of the present invention;

[0027] Figure 5 Flow chart of an in-situ dissolved gas detection method in Embodiment 2 of the present invention. Detailed Embodiments

[0028] The following further describes the specific embodiments of the present invention in conjunction with the drawings. It should be noted here that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation to the present invention. In addition, the technical features involved in the following specific embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0029] In the following description, specific details such as specific system structures and technologies are presented for the purpose of illustration rather than limitation, so as to thoroughly understand the embodiments of the present application. However, those skilled in the art should clearly understand that the present application can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from interfering with the description of the present application.

[0030] Embodiment 1:

[0031] As Figure 1 shown, the present invention provides an in-situ detection device for dissolved gases in oil, including a degassing module 1 and a detection module 2;

[0032] The degassing module 1 is in direct contact with the transformer oil and is used to separate the dissolved gases in the transformer oil by means of membrane degassing to obtain separated gases;

[0033] The detection module 2 includes a distributed feedback laser 21, a coupler 22, a photoacoustic cell 24, several photodetectors 23, an AD conversion module 25, and an FPGA core control and demodulation system 26; the photoacoustic cell 24 is used to introduce the separated gases, and the distributed feedback laser 21 is used to emit a frequency-modulated light beam that is divided into multiple laser beams by the coupler 22 to excite the separated gases in the photoacoustic cell 24 to generate photoacoustic or optical signals. Several photodetectors 23 are used to receive the signals and transmit the signals to the AD conversion module 25 and then input them into the FPGA core control and demodulation system 26 for demodulation to obtain Raman scattering spectrum data. By analyzing the Raman scattering spectrum data, the concentrations of the component gases in the separated gases are obtained, and the types of internal faults of the transformer are judged according to the concentrations of the component gases.

[0034] In the above technical solution, since the degassing module is in direct contact with the transformer oil and uses the membrane degassing method, there is no need to pump the internal oil of the transformer out to the outside for oil-gas separation, thereby reducing the complexity of additional equipment and pipeline connections. The entire detection process does not require the insulating oil to be transferred to the outside for gas extraction or separation, avoiding problems such as safety risks, oil quality pollution, or deterioration of insulation performance caused by oil transfer. By integrating the degassing unit and the detection module and directly contacting the internal oil of the transformer, the dissolved gas information in the oil can be continuously and real-time obtained under the normal operating state of the equipment, improving the efficiency of fault diagnosis and early warning. There is no need for additional oil pumping pipelines and pumping systems, making the device structure more compact, installation and maintenance more convenient, reducing the on-site construction volume and the later maintenance cost.

[0035] In the above technical solution, the degassing module 1 and the detection module 2 are integrally installed inside the customized flange 4, and the customized flange 4 is connected to the transformer 5 through a matching interface. This facilitates the detection of the content of various gases in the transformer oil tank without stopping the operation of the transformer and without disassembling the transformer, realizing the on-line monitoring of transformer faults.

[0036] In the above technical solution, the frequency-modulated light beam is divided into a first laser, a second laser, and a third laser by the coupler 22. The first laser and the second laser are respectively used to excite the separated gas in the photoacoustic cell to generate photoacoustic or optical signals, and the third laser is used for light intensity calibration.

[0037] In the above technical solution, the first laser and the second laser respectively act on different incident positions of the photoacoustic cell 24 to improve the detection sensitivity of the separated gas. The third laser is used to calibrate and compensate for the drift of the first laser and the second laser in light intensity and phase, thereby improving the detection accuracy.

[0038] In the above technical solution, the FPGA core control and demodulation system 26 sends the Raman scattering spectrum data to the host computer, and the host computer calculates the concentrations of at least characteristic gases including CO, CO2, CH4, C2H4, C2H6, C2H2, and H2.

[0039] In the above technical solution, the fault types include at least one of oil overheating, partial discharge, and spark discharge.

[0040] In the above technical solution, the transformer fault type is diagnosed according to the concentration threshold or gas ratio of each gas, and when a predetermined trigger condition is met, a fault warning or alarm signal is sent to the monitoring system, realizing continuous monitoring of the transformer operation state and early fault diagnosis.

[0041] The above embodiments provide an in-situ detection device for dissolved gases in oil. By means of a membrane degassing module, real-time extraction of dissolved gases in oil is achieved. Combining with the high-sensitivity detection technology of a distributed feedback laser and a photoacoustic cell, gas component information can be quickly obtained, improving the accuracy and timeliness of on-line detection. By using high-sensitivity optical detection means such as photoacoustic / Raman scattering, accurate detection can be achieved at a relatively low gas concentration, and good resolution and selectivity for different types of gases are possessed. The combination of membrane degassing technology and a distributed feedback laser makes the overall volume of the detection module small and the integration degree high, being suitable for installation and operation on-site or in a narrow space, reducing the impact on the normal operation of the transformer. By quickly detecting the concentration change of key gases in transformer oil, the type of internal fault of the transformer can be judged in time and a warning can be issued, shortening the fault diagnosis and treatment time, and reducing the economic and safety risks brought by the fault. The on-line monitoring method can reduce the frequency and cost of traditional sampling and laboratory analysis; at the same time, by efficiently detecting faults and troubleshooting in time, the potential risks of shutdown or accidents are reduced, significantly improving the stable operation and safety of power equipment.

[0042] Embodiment 2:

[0043] As Figure 5 shown, the present invention also provides an in-situ detection method for dissolved gases in oil, comprising the following steps:

[0044] 1) Integrally install the degassing module 1 and the detection module 2 inside a customized flange 4, so that the transformer oil is in direct contact with the degassing module 1;

[0045] 2) Use membrane degassing technology to separate the dissolved gases in the transformer oil, and introduce the separated gases into the photoacoustic cell 24;

[0046] 3) Start the distributed feedback laser 21, and the emitted frequency-modulated light beam is divided into a first laser, a second laser and a third laser through a coupler 22. Among them, the first laser and the second laser are used to excite the separated gases in the photoacoustic cell 24, and the third laser is used for light intensity calibration; the first laser and the second laser act on different incident positions of the photoacoustic cell into which the separated gases are introduced respectively to improve the detection sensitivity of the separated gases, and the third laser is used to calibrate and compensate for the drift of the first laser and the second laser in light intensity and phase, thereby improving the detection accuracy;

[0047] 4) Use several photodetectors 23 to detect the three-way laser signals, and the AD conversion module 25 collects the photoelectric signals and transmits them to the FPGA core control and demodulation system 26;

[0048] 5) The FPGA core control and demodulation system 26 demodulates the received photoelectric signals to obtain Raman scattering spectrum data, and the upper computer analyzes the spectrum data to obtain the concentration of each component gas in the separated gases;

[0049] 6) Judge the type of internal fault of the transformer according to the concentration of each component gas, and realize the in-situ detection of dissolved gases in transformer oil.

[0050] In step 1), the customized flange 4 is provided with a general interface connected to the external power supply and signal line, so that the transformer can be detected online without power outage or disassembly.

[0051] In step 3), the light intensity distribution ratios of the first laser, the second laser and the third laser can be dynamically adjusted according to the actual detection requirements to balance the detection sensitivity and system stability.

[0052] In step 4), the optoelectronic signal output by the optoelectronic detector 23 is subjected to lock-in amplification or coherent demodulation to filter out the influence of environmental noise and mechanical vibration on the signal and improve the detection resolution of the weak Raman scattering spectrum.

[0053] In step 5), the FPGA core control and demodulation system 26 uploads the demodulated Raman scattering spectrum data to the host computer, and the host computer calculates the concentrations of gases such as CO, CO2, CH4, C2H4, C2H6, C2H2, H2, etc. in combination with the pre-calibrated gas characteristic peak information.

[0054] In step 6), diagnose the type of transformer fault according to the concentration threshold or gas ratio of each gas, and send a fault warning or alarm signal to the monitoring system when the predetermined trigger condition is met, so as to realize the continuous monitoring and early fault diagnosis of the transformer operation state.

[0055] The above embodiments provide an in-situ detection method for dissolved gases in oil. The degassing module 1 and the detection module 2 are integrally installed inside a customized flange 4, enabling the transformer oil to directly contact the degassing module 1, so that there is no need to pump the transformer oil to the outside for oil-gas separation. At the same time, the customized flange 4 is provided with a general interface connected to external power supply and signal lines, enabling on-line detection of the transformer without power outage or disassembly. Using membrane degassing technology, the gases dissolved in the transformer oil are separated from the oil phase to obtain separated gases, and the separated gases are introduced into the photoacoustic cell 24 to provide a stable and pure gas sample for subsequent Raman spectroscopy measurement. The distributed feedback laser 21 is started, and the emitted frequency-modulated light beam is divided into a first laser, a second laser, and a third laser by the coupler 22. Among them, the first laser and the second laser enter the photoacoustic cell 24 from different incident positions respectively to excite the separated gases to generate photoacoustic or optical signals, so as to improve the detection sensitivity of the dissolved gases; the third laser is used for calibration compensation of the first two lasers in terms of light intensity and phase drift, thereby further improving the detection accuracy of the system. In addition, the light intensity distribution ratio of the three lasers can be dynamically adjusted according to actual detection requirements, taking into account both detection sensitivity and system stability. Several photodetectors 23 respectively detect the three laser signals, and the output photoelectric signals are subjected to lock-in amplification or coherent demodulation to filter out the influence of environmental noise and mechanical vibration on the signals; subsequently, the AD conversion module 25 digitally acquires the analog signals output by the detectors and transmits the digital signals to the FPGA core control and demodulation system 26. The FPGA core control and demodulation system 26 demodulates the received digital signals to obtain Raman scattering spectrum data, and uploads the data to the host computer for further analysis. Combining the pre-calibrated gas characteristic peak information, the concentrations of each component gas such as CO, CO2, CH4, C2H4, C2H6, C2H2, H2, etc. can be calculated. According to the concentration thresholds of the above component gases or different gas ratio relationships, the possible fault types inside the transformer can be judged, such as partial discharge, overheating, thermal fault, etc. When any parameter meets the predetermined fault trigger condition, the detection system can send a fault warning or alarm signal to the monitoring center to realize continuous monitoring of the transformer operation state and early fault diagnosis.

[0056] Through the above steps, while achieving high-precision, on-line, and real-time detection of dissolved gases in transformer oil, this method avoids the traditional oil pumping and external separation processes, greatly improves the applicability and detection efficiency of the system, and effectively reduces the impact on the normal operation of the transformer.

[0057] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. The content not described in detail in this specification belongs to the well-known prior art of those skilled in the art.

Claims

1. An in-situ detection device for dissolved gas in oil, characterized in that: It comprises a degassing module (1) and a detection module (2), The degassing module (1) is in direct contact with the transformer oil and is used to separate the dissolved gas in the transformer oil by membrane degassing to obtain separated gas; The detection module (2) comprises a distributed feedback laser (21), a coupler (22), a photoacoustic cell (24), a plurality of photodetectors (23), an AD conversion module (25) and an FPGA core control and demodulation system (26); the photoacoustic cell (24) is used to introduce the separated gas, the distributed feedback laser (21) is used to emit a frequency modulated light beam which is divided into a plurality of laser beams through the coupler (22) for exciting the separated gas in the photoacoustic cell (24) to generate photoacoustic or optical signals, the plurality of photodetectors (23) are used to receive signals and transmit the signals to the AD conversion module (25) and then input the signals to the FPGA core control and demodulation system (26) for demodulation to obtain Raman scattering spectrum data, the concentration of each component gas in the separated gas is obtained by analyzing the Raman scattering spectrum data, and the type of internal fault of the transformer is determined according to the concentration of each component gas.

2. The in-situ detection device for dissolved gas in oil according to claim 1, characterized in that: The degassing module (1) and the detection module (2) are integrated and installed on the inner side of a customized flange (4), and the customized flange (4) is connected to the device to be tested through a matching interface.

3. The in-situ detection device for dissolved gas in oil according to claim 1, characterized in that: The frequency modulated light beam is divided into a first laser, a second laser and a third laser through the coupler (22); the first laser and the second laser are respectively used to excite the separated gas in the photoacoustic cell to generate photoacoustic or optical signals; the third laser is used for light intensity calibration.

4. The in-situ detection device for dissolved gas in oil according to claim 3, characterized in that: The first laser and the second laser act on different incident positions of the photoacoustic cell (24) respectively, and the third laser is used to calibrate and compensate for the drift of the first laser and the second laser in terms of light intensity and phase.

5. The in-situ detection device for dissolved gas in oil according to claim 1, characterized in that: The FPGA core control and demodulation system (26) sends the Raman scattering spectrum data to a host computer, and the host computer calculates the concentration of at least the characteristic gases including CO, CO2, CH4, C2H4, C2H6, C2H2, and H2.

6. The in-situ detection device for dissolved gas in oil according to claim 1, characterized in that: The fault type includes at least one of oil overheating, partial discharge and spark discharge.

7. The in-situ detection device for dissolved gas in oil according to claim 1, characterized in that: The transformer fault type is diagnosed according to the concentration threshold or gas ratio of each gas, and a fault warning or alarm signal is sent to the monitoring system when the predetermined trigger conditions are met.

8. A method for in-situ detection of dissolved gas in oil, characterized in that: include The dissolved gas in the transformer oil is separated by membrane degassing to obtain separated gas. The separated gas is excited by multiple laser beams to generate photoacoustic or optical signals. The signals are demodulated to obtain Raman scattering spectrum data. The concentration of each component gas in the separated gas is obtained by analyzing the Raman scattering spectrum data. The internal fault type of the transformer is judged according to the concentration of each component gas.

9. The method for in-situ detection of dissolved gas in oil according to claim 8, characterized in that: The multiple laser beams are divided into a first laser, a second laser and a third laser. The first laser and the second laser are respectively used to excite the separated gas in the photoacoustic cell to generate photoacoustic or optical signals, and the third laser is used for light intensity calibration.

10. The method for in-situ detection of dissolved gas in oil according to claim 9, characterized in that: The first laser and the second laser act on different incident positions of the photoacoustic cell into which the separation gas is introduced, respectively, and the third laser is used to calibrate and compensate for the drift of the first laser and the second laser in terms of light intensity and phase.

11. The method for in-situ detection of dissolved gas in oil according to claim 8, characterized in that: The Raman scattering spectrum data is sent to a host computer, and the host computer calculates the concentration of at least characteristic gases including CO, CO2, CH4, C2H4, C2H6, C2H2, and H2.

12. The method for in-situ detection of dissolved gas in oil according to claim 8, characterized in that: The fault type includes at least one of oil overheating, partial discharge and spark discharge.

13. The method for in-situ detection of dissolved gas in oil according to claim 8, characterized in that: The transformer fault type is diagnosed according to the concentration threshold or gas ratio of each gas, and a fault warning or alarm signal is sent to the monitoring system when the predetermined trigger conditions are met.

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