Transformer low oil flow area oil sampling device and method

Abstract

The invention belongs to the technical field of power equipment, and particularly relates to an oil sampling device and method for a low oil flow area of a transformer. The device comprises a sampling assembly, a positioning assembly, a driving assembly, an observation assembly, a driving assembly and a quantity control and monitoring assembly. According to the invention, through integration of the flexible sampling tube, magnetic type accurate positioning, endoscope visual observation, automatic monitoring and protection and a standardized pretreatment process, a representative oil sample is directly, accurately and cleanly extracted from a low oil flow area in the transformer; the technical problems that in a traditional method, sampling cannot be conducted on the area, secondary pollution is prone to being introduced, and the sampling process is uncontrollable are effectively solved, and the comprehensiveness and accuracy of transformer insulating oil state monitoring are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of power equipment technology, specifically relating to a device and method for sampling oil in the low oil flow zone of a transformer. Background Technology

[0002] Transformers are core basic power facilities in substations, and most large transformers operating in the power grid are oil-immersed power transformers. The insulating oil inside the transformer plays a dual crucial role: firstly, as an internal insulating medium, it ensures the electrical insulation performance between the windings, core, and tank; secondly, as a heat dissipation medium, it transfers the heat generated by the core and windings during operation to the cooling system, thereby ensuring the transformer operates stably under rated conditions. Therefore, the physicochemical state and cleanliness of the insulating oil directly affect the transformer's insulation strength and heat dissipation efficiency, and are key factors influencing its safe and reliable operation.

[0003] During long-term operation, the insulating oil of a transformer is subjected to the combined effects of various physical and chemical factors, including sunlight, temperature, oxygen, humidity, and electric field strength, gradually aging and decomposing. This process not only produces low-molecular-weight hydrocarbon gases such as hydrogen, methane, ethylene, acetylene, and ethane, but also solid impurities such as carbon fibers, carbon particles, and metal wear debris. These impurities are dispersed throughout the transformer's interior as the insulating oil circulates. However, in "low oil flow zones"—areas with complex structures and poor oil circulation, such as riser blocks, outgoing line devices, and bushings—the oil flow is slow or even stagnant, making it easy for impurities to gradually settle and accumulate in these areas.

[0004] Currently, conventional methods for collecting transformer oil samples mainly rely on fixed sampling valves pre-installed in the main circulating oil circuit or at the bottom of the tank. These sampling points are all located in areas with relatively active oil flow, while the aforementioned low oil flow areas typically lack dedicated sampling interfaces due to structural limitations and safety considerations. Therefore, existing technologies cannot directly obtain representative oil samples from these critical low oil flow areas. Oil samples collected from other active oil flow areas, because they fail to contain the characteristic impurities accumulated in low oil flow areas, cannot accurately reflect the degree of insulation oil degradation and contaminant deposition in these localized areas. This results in blind spots in the assessment of the overall health of the transformer's internal components, making it difficult to provide sufficient basis for early warning of latent faults and accurate operation and maintenance decisions. Summary of the Invention

[0005] The purpose of this invention is to provide an oil sampling device and method for the low oil flow zone of a transformer, so as to solve the problems existing in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an oil sampling device for the low oil flow zone of a transformer, comprising: The sampling assembly includes a flexible sampling tube with a sampling end and a connecting end, wherein the connecting end is provided with a three-way structure to form a pump connection port, a sampling port and a flushing port; The positioning component includes a guide positioning seat disposed at the sampling end, an internal iron block disposed within the guide positioning seat, and an external magnetic calibration component disposed on the outer wall of the transformer and magnetically engaged with the internal iron block to achieve positioning of the sampling end. The drive assembly includes a vacuum pump connected to the pump connection port; The observation assembly includes an endoscope disposed at the guide positioning seat or the sampling tube near the sampling end; A sampling container connected to the sampling port; and The control and monitoring components include a level switch for monitoring the liquid level in the sampling container, a pressure sensor for monitoring pipeline pressure, and a data recording and control unit connected to the level switch, pressure sensor, and vacuum pump. The data recording and control unit is configured to control the start and stop of the vacuum pump based on the liquid level or pressure signal.

[0007] Preferably, the sampling tube is an oil-resistant silicone tube with length graduations on its outer wall; the rinsing port is equipped with a removable sealing plug.

[0008] Preferably, the positioning component further includes a wireless transmission module, and the external magnetic calibration component has a built-in position sensor for detecting the distance between itself and the built-in iron block. The position sensor is connected to the display unit via the wireless transmission module to provide real-time feedback of positioning information.

[0009] Preferably, the guide positioning seat has a conical structure, and its outer surface is covered with an elastic protective sleeve.

[0010] Preferably, the observation component further includes an LED supplementary light disposed on the endoscope lens, and the endoscope lens or display screen is provided with scale reference lines.

[0011] Preferably, the vacuum pump is a variable frequency vacuum pump with a one-way valve at its outlet; the sampling container is a glass sampling bottle with a screw cap with a sealing ring and a magnetic stir bar at the bottom.

[0012] Preferably, the level switch is a float level switch; the data recording and control unit is configured to control the vacuum pump to stop and issue an alarm when the level reaches a preset value or the pressure exceeds a preset threshold.

[0013] This invention also discloses a method for sampling oil in the low oil flow zone of a transformer, using the aforementioned oil sampling device, and including the following steps: The sampling tube, sampling container, and guide positioning seat are cleaned and dried. With the transformer out of service, open the inspection port near the target low oil flow area; insert the sampling end of the sampling tube into the transformer, observe through the observation component and combine the magnetic attraction between the external magnetic calibration component and the internal iron block to position the sampling end to the target low oil flow area; connect the pump connection port, the sampling port, the drive component, and the sampling container; The vacuum pump is started to extract insulating oil from the low oil flow zone into the sampling container; the liquid level and pipeline pressure are monitored in real time by the control and monitoring components, and the vacuum pump is automatically stopped when the preset sampling volume is reached or the pressure is abnormal. After sampling is completed, disconnect the connection, rinse the sampling tube, remove it, seal and label the sampling container to complete the sampling.

[0014] Preferably, the pretreatment step of the device includes sequential ultrasonic cleaning, solvent cleaning and vacuum drying steps.

[0015] Preferably, in the automatic sampling and monitoring step, the inside of the sampling tube is rinsed through the rinsing port before or after sampling; after sampling is completed, the oil sample in the sampling container is magnetically stirred to make it uniform.

[0016] The beneficial effects of this invention are as follows: By integrating flexible sampling tubes, magnetic precise positioning, endoscopic visualization observation, automatic monitoring and protection, and standardized pretreatment processes, this invention enables the direct, accurate, and clean extraction of representative oil samples from low oil flow areas inside transformers. It effectively solves the technical problems of traditional methods, such as the inability to sample this area, the easy introduction of secondary pollution, and the uncontrollable sampling process. It significantly improves the comprehensiveness and accuracy of transformer insulating oil condition monitoring, providing a reliable basis for early warning of latent transformer faults and operation and maintenance decisions. At the same time, it has the advantages of safe operation, traceable process, modular structure, and easy promotion. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the sampling component in an embodiment of the present invention; Figure 2 This is a schematic diagram of the positioning component in an embodiment of the present invention; Figure 3 This is a schematic diagram of the observation component in an embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of the driving component in an embodiment of the present invention; Figure 5 This is a schematic diagram of the sampling container in an embodiment of the present invention; Figure 6 This is a schematic diagram illustrating the connection and working principle of the control and monitoring components in an embodiment of the present invention; In the picture: 1 - Sampling assembly; 11 - Flexible sampling tube; 12 - Sampling end; 13 - Connection end; 14 - Pump connection port; 15 - Sampling port; 16 - Flushing port; 17 - Sealing plug; 2 - Positioning component; 21 - Guide positioning seat; 22 - Built-in iron block; 24 - External magnetic calibration component; 25 - Wireless transmission module; 26 - Position sensor; 27 - Display unit; 3 - Drive assembly; 31 - Vacuum pump (variable frequency vacuum pump); 32 - Check valve; 33 - Flow control knob; 4 - Observation components; 41 - Endoscope; 42 - LED supplemental lighting; 5 - Sampling container; 51 - Sampling bottle (glass sampling bottle); 52 - Bottle cap (sealable screw cap); 53 - Magnetic stir bar; 6 - Quantity control and monitoring components; 61 - Level switch (float level switch); 62 - Pressure sensor; 63 - Data logging and control unit; 64 - Relay. Detailed Implementation

[0018] like Figure 1-6 As shown, a transformer low oil flow zone oil sampling device includes a sampling component 1, a positioning component 2, a driving component 3, an observation component 4, a driving component 5, and a control and monitoring component 6. The specific structure is as follows: The sampling component 1 is a sampling tube 11 made of oil-resistant silicone material, which can be bent at will to adapt to the complex internal space of the transformer. One end is the sampling end 12, and the other end is the connection end 13 with an integrated three-way valve. The connection end branches into three independent ports, namely the pump connection port 14, the sampling port 15, and the flushing port 16. The flushing port is equipped with a sealing plug to realize the pipeline flushing function before sampling and avoid residual impurities from contaminating the oil sample. The outer wall of the sampling tube has scale markings along the length direction with an accuracy of 1cm to help determine the insertion depth. The inner diameter of the sampling tube is 0.3-0.5cm, the wall thickness is 0.1-0.2cm, and the flushing port is equipped with a threaded sealing plug.

[0019] The positioning component 2 includes a guide positioning seat 21 detachably fixed to the sampling end 12 of the sampling tube, an internal iron block 22, a magnetic positioning calibrator 23, and an external magnetic calibrator 24. The guide positioning seat has a conical guide structure and is covered with an elastic rubber protective sleeve to prevent collision damage to the internal components of the transformer when inserted. The internal iron block is embedded inside the guide positioning seat to ensure the center of gravity is concentrated. The magnetic calibrator is attached to the outer wall of the transformer and has a built-in position sensor linked with the endoscope display screen. The relative position of the magnet and the iron block is fed back in real time through the wireless module 25 to achieve accurate positioning of the sampling end and avoid accidental adsorption of internal metal components of the transformer. The guide positioning seat has a conical structure and the thickness of the elastic rubber protective sleeve is 2-3mm. The magnetic calibrator has a built-in Hall sensor that can provide real-time feedback on the distance to the iron block, with a distance detection accuracy of 0.5cm.

[0020] The drive assembly 3 includes a small variable frequency vacuum pump 31 connected to the pump connection port 14, equipped with a flow rate adjustment knob, which can adjust the extraction rate according to the viscosity of the oil sample to avoid impurity particles from accumulating and clogging the pipeline due to excessive flow rate; a one-way valve 32 is provided at the pump body outlet end to prevent oil sample backflow from contaminating the pump body and pipeline. The observation component 4 is integrated into the industrial-grade miniature waterproof endoscope 41 on the side of the guide positioning seat. The lens is equipped with an adjustable LED supplement light 42 to adapt to the dim environment inside the transformer. The endoscope has a scale reference line, and the distance between the sampling end and the target area can be intuitively judged through the display screen to improve the positioning accuracy. The sampling container 5 is a sampling bottle made of high borosilicate glass. The bottle mouth is sealed with a polytetrafluoroethylene screw cap 51 (non-frosted design), which is connected to the sampling port 15 at the top. The screw cap has a built-in silicone sealing ring to enhance the sealing performance. The side wall of the sampling bottle is equipped with liquid level scale 52, and the bottom of the bottle integrates a detachable micro magnetic stirrer. After sampling, the oil sample can be uniformly stirred by an external magnetic stirrer, which is convenient for subsequent testing. The control and monitoring component 6 includes a float level switch 61 placed inside the sampling bottle, a miniature pressure sensor 62 installed at the sampling port of the sampling tube, and a portable data logger 63. The float level switch is electrically connected to a small variable frequency vacuum pump via a relay to control the sampling volume. The pressure sensor monitors the pressure changes in the pipeline in real time. When the pressure rises abnormally (indicating pipeline blockage) or drops abnormally (indicating leakage), the data logger issues an audible and visual alarm and triggers the pump to stop. The data logger simultaneously records the sampling time, pressure, flow rate, and liquid level data, enabling traceability of the sampling process.

[0021] This method, based on the aforementioned apparatus, includes the following steps: 1) Pre-treatment of sampling components: The sampling tube, sampling bottle, guide positioning seat, and matching toolbox are cleaned and dried in stages. The specific steps are as follows: ① Ultrasonic cleaning: Place the above components into an ultrasonic cleaner, add deionized water and neutral cleaning agent, and ultrasonically clean for 10-15 minutes to remove solid impurities attached to the surface; ② Solvent cleaning: Wipe and clean the inner and outer walls of the sampling tube, the inner and outer walls of the sampling bottle, and the surface of the guide positioning seat with anhydrous ethanol. After standing for 2 minutes, pour out the residual anhydrous ethanol; ③ Vacuum drying: Place the components cleaned with anhydrous ethanol into a vacuum oven and dry them at 60-80℃ for 2-3 hours; ④ Sealing for later use: After drying, assemble the sampling tube, sampling bottle, and guide positioning seat into a pre-assembled body, place it in the toolbox, seal it, and store it to avoid secondary contamination; 2) Pipeline Connection and Precise Positioning of Sampling End: ① During transformer power outage maintenance, open the handhole or manhole near the target low oil flow area (straight-line distance not exceeding 1m) and tighten the sealing plug; ② Insert the sampling end of the sampling tube, equipped with a guide positioning seat and endoscope, into the transformer through the handhole or manhole, and initially control the insertion depth through the scale markings on the outer wall of the sampling tube; ③ The operator observes the internal environment through the endoscope display screen, adjusts the brightness of the LED supplementary light, and judges the distance between the sampling end and the target area using the lens scale reference line; at the same time, attach the magnetic calibration piece to the target position on the outer wall of the transformer, and adjust the position of the magnet through the position signal feedback from the display screen until the magnetic calibration piece displays "positioning successful". When the distance between the magnet and the iron block displayed by the magnetic calibration piece is not more than 1cm, the positioning is considered successful. The precise fixing of the sampling end is completed; ④ Seal the pump connection port of the sampling tube connection end to the small variable frequency vacuum pump, seal the sampling port to the sampling bottle, and complete the signal connection between the data logger, pressure sensor, and float level switch; 3) Automatic Sampling and Data Recording: ① Turn on the data logger, set the pressure alarm threshold (upper limit 0.1MPa, lower limit 0.01MPa) and the upper limit of the sampling liquid level; ② Adjust the flow knob of the small variable frequency vacuum pump, set the initial pumping rate to 5-10mL / s, and turn on the pump; ③ The insulating oil in the low oil flow zone flows into the sampling bottle through the sampling tube under the suction of the pump, and the data logger records the sampling time, pipeline pressure, and oil flow rate data simultaneously; ④ When the oil sample level in the sampling bottle reaches the preset upper limit, the float level switch triggers the on / off signal, and controls the pump to stop through the relay; if pipeline blockage or leakage occurs during the sampling process, the data logger immediately issues an audible and visual alarm and triggers the shutdown; ⑤ After sampling is completed, turn off the data logger, disconnect the sampling tube from the pump and sampling bottle in sequence, open the flushing port, flush the residual oil sample inside the sampling tube with a small amount of anhydrous ethanol, and then slowly remove the sampling tube from the transformer; ⑥ Tighten the sealing cap of the sampling bottle, place the sampling bottle on a magnetic stirrer and stir for 30 seconds to homogenize the oil sample, and label the sampling information; finally, close the sealing cap of the transformer manhole or handhole to complete the sampling operation.

[0022] In this embodiment, the sampling tube is made of oil-resistant silicone, with an inner diameter of 0.4cm, a wall thickness of 0.15cm, a length of 6m, and an outer wall graduation accuracy of 1cm. The guide positioning seat is an ABS plastic conical structure with a cone angle of 60°, covered with a 2.5mm thick elastic rubber protective sleeve, and contains an 80g stainless steel block. It is detachably connected to the sampling tube via threads. The endoscope is an industrial-grade miniature waterproof endoscope with a diameter of 0.3cm, equipped with a 3W adjustable LED supplementary light, an effective observation distance of ≥5m, and a lens with a 0.5cm graduation reference line. The magnetic calibration component has a built-in Hall sensor for detection. It features a measurement accuracy of 0.5cm and a 3.5-inch display screen; a small variable frequency vacuum pump with a rated power of 50W and a flow rate adjustment range of 5-20mL / s; a one-way valve with a pressure resistance of ≥0.2MPa; a 500mL high borosilicate glass sampling bottle with a built-in 10mm diameter PTFE magnetic stirrer at the bottom and a silicone sealing ring in the sealing cap; a float level switch with a trigger level setting of 400mL; a miniature pressure sensor with a range of 0-0.2MPa; a data logger capable of storing 100 sets of sampling data and supporting USB export; and an M10 threaded sealing plug at the flushing port.

[0023] The oil sampling steps in this embodiment are as follows: (1) Pretreatment of sampling components: Place the sampling tube, 500mL glass sampling bottle, guide positioning seat, and toolbox into an ultrasonic cleaner, add deionized water and neutral industrial cleaning agent (5% cleaning agent concentration), set the power to 400W, and turn on ultrasonic cleaning for 12min; after taking it out, wipe the inner and outer walls of the sampling tube, the inner and outer walls of the sampling bottle, and the surface of the guide positioning seat evenly with anhydrous ethanol, let it stand for 2min and pour out the residual anhydrous ethanol; put the above components into a vacuum oven, set the temperature to 70℃, the vacuum degree to -0.09MPa, and dry for 2.5h; after drying, thread the guide positioning seat to the sampling end of the sampling tube, and put the sampling tube and sampling bottle into the toolbox for sealed storage.

[0024] (2) Pipeline connection and positioning: Select a 220kV oil-immersed transformer, with the target low oil flow area being the riser seat area, and the straight-line distance between the nearby maintenance manhole and the riser seat being 0.8m; during power outage maintenance, open the manhole sealing cover and tighten the sampling tube flushing port plug; insert the sampling end into the manhole, and control the insertion depth to 3.5m through the outer wall scale markings; the operator observes through the endoscope display screen, adjusts the LED supplementary light to clearly display the inner wall of the riser seat, and uses the lens scale reference line to determine the distance between the sampling end and the inner wall of the riser seat. The wall distance is 2cm; attach the magnetic calibration piece to the corresponding position on the outer wall of the transformer. The display shows that the distance between the magnet and the iron block is 0.8cm, indicating successful positioning. Fix the magnet; then use clamps to seal the connection port of the sampling tube pump to the input end of the frequency converter vacuum pump, and use PTFE connectors to seal the connection between the sampling port and the sampling bottle. Connect the data logger to the pressure sensor and the float level switch signal respectively, and set the upper limit of pressure to 0.1MPa, the lower limit to 0.01MPa, and the upper limit of liquid level to 400mL.

[0025] (3) Automatic sampling in stages: Adjust the flow rate knob of the variable frequency vacuum pump, set the extraction rate to 8 mL / s, and turn on the pump. The insulating oil in the riser area flows into the sampling bottle under the vacuum suction. The data recorder records the sampling time, pipeline pressure and flow data simultaneously. When the oil sample level rises to 400 mL, the float level switch triggers the signal, the relay disconnects the power supply to the pump, and the pump stops working. The data recorder displays the sampling time as 4 min 20 s, the average pressure as 0.05 MPa, and no abnormal alarm. Turn off the main power, disassemble all connecting parts, open the flushing port and flush the sampling tube with anhydrous ethanol for 30 s, and slowly remove the sampling tube. Tighten the sealing cap of the sampling bottle, place the sampling bottle on the magnetic stirrer, set the speed to 300 r / min, and stir for 30 s to homogenize the oil sample. Mark the sampling time, transformer number, sampling location and other information, close the manhole sealing cap, and complete the sampling operation.

[0026] It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention.

Claims

1. A device for sampling oil in the low oil flow zone of a transformer, characterized in that, include: The sampling assembly (1) includes a flexible sampling tube (11) having a sampling end (12) and a connecting end (13). The connecting end (13) is provided with a three-way structure to form a pump connection port (14), a sampling port (15) and a flushing port (16). The positioning component (2) includes a guide positioning seat (21) disposed on the sampling end (12), an internal iron block (22) disposed in the guide positioning seat (21), and an external magnetic calibration component (24) disposed on the outer wall of the transformer and magnetically engaged with the internal iron block (22) to achieve positioning of the sampling end (12). The drive assembly (3) includes a vacuum pump (31) connected to the pump connection port (14). The observation component (4) includes an endoscope (41) disposed on the guide positioning seat (21) or the sampling tube (11) near the sampling end (12). A sampling container (5) is connected to the sampling port (15); and The control and monitoring component (6) includes a level switch (61) for monitoring the liquid level in the sampling container (5), a pressure sensor (62) for monitoring pipeline pressure, and a data recording and control unit (63) connected to the level switch (61), the pressure sensor (62) and the vacuum pump (31) by signal connection. The data recording and control unit (63) is configured to control the start and stop of the vacuum pump (31) according to the liquid level or pressure signal.

2. The transformer low oil flow zone oil sampling device according to claim 1, characterized in that, The sampling tube (11) is an oil-resistant silicone tube with length markings on its outer wall; the rinsing port (16) is equipped with a removable sealing plug.

3. The transformer low oil flow zone oil sampling device according to claim 1, characterized in that, The positioning component (2) also includes a wireless transmission module (25). The external magnetic calibration component (24) has a built-in position sensor for detecting the distance between itself and the built-in iron block (22). The position sensor is connected to the display unit via the wireless transmission module (25) to provide real-time feedback of positioning information.

4. The transformer low oil flow zone oil sampling device according to claim 1, characterized in that, The guide positioning seat (21) has a conical structure and its outer surface is covered with an elastic protective sleeve.

5. The transformer low oil flow zone oil sampling device according to claim 1, characterized in that, The observation component (4) also includes an LED fill light (42) disposed on the lens of the endoscope (41), and the lens or display screen of the endoscope (41) is provided with scale reference lines.

6. The transformer low oil flow zone oil sampling device according to claim 1, characterized in that, The vacuum pump (31) is a variable frequency vacuum pump, and its outlet is equipped with a one-way valve (32); the sampling container (5) is a glass sampling bottle, and its bottle cap (51) is a screw cap with a sealing ring, and the bottom of the bottle is equipped with a magnetic stir bar (52).

7. The transformer low-oil-flow zone oil sampling device according to any one of claims 1 to 6, characterized in that, The liquid level switch (61) is a float liquid level switch; the data recording and control unit (63) is configured to control the vacuum pump (31) to stop and issue an alarm when the liquid level reaches a preset value or the pressure exceeds a preset threshold.

8. A method for taking oil samples in the low oil flow zone of a transformer, characterized in that, The oil sampling device as described in any one of claims 1 to 7 includes the following steps: S1: Clean and dry the sampling tube (11), sampling container (5) and guide positioning seat (21); S2: When the transformer is out of service, open the inspection hole near the target low oil flow area; insert the sampling end (12) of the sampling tube (11) into the transformer, observe through the observation component (4) and combine the magnetic attraction between the external magnetic calibration component (24) and the internal iron block (22) to position the sampling end (12) to the target low oil flow area; connect the pump connection port (14), the sampling port (15) to the drive component (3) and the sampling container (5). S3: Start the vacuum pump (31) to extract insulating oil from the low oil flow area to the sampling container (5); monitor the liquid level and pipeline pressure in real time through the control and monitoring component (6), and automatically control the vacuum pump (31) to stop when the preset sampling amount is reached or the pressure is abnormal; S4: After sampling is completed, disconnect the connection, rinse the sampling tube (11) and take it out, seal and mark the sampling container (5) to complete the sampling.

9. The method for taking oil samples from the low oil flow zone of a transformer according to claim 8, characterized in that, In step S1, the pretreatment includes sequential ultrasonic cleaning, solvent cleaning, and vacuum drying steps.

10. The method for sampling oil in the low oil flow zone of a transformer according to claim 8, characterized in that, In step S3, before or after sampling, the inside of the sampling tube (11) is rinsed through the rinsing port (16); after sampling, the oil sample in the sampling container (5) is magnetically stirred to make it uniform.

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