Vacuum oiling device for transformer insulation and method thereof

Abstract

This invention relates to the field of large power transformer manufacturing and on-site installation, specifically to a transformer insulation vacuum oil injection device and method. The device includes a movable base, a degassing tank with swirling atomizing nozzles and multi-layer corrugated diffusers, a vacuum pump, a variable frequency oil injection pump, a pressure transmitter, and a controller. The system coordinates and regulates vacuum and oil injection operations using pressure sensor data. Its core principle is that the insulating oil is broken into droplets under the action of swirling centrifugal force, spreading and forming a film along a continuous V-shaped corrugated surface, and undergoing secondary drop and breakage at the perforation point, with the lower layer changing direction and re-spreading. This invention achieves multi-stage drop and spread of the insulating oil, significantly increasing its effective contact area with the vacuum environment, significantly improving gas-liquid separation efficiency, and effectively solving the problem of incomplete degassing in traditional degassing devices.

Description

Technical Field

[0001] This invention relates to the field of manufacturing and on-site installation of large power transformers, specifically to a transformer insulation vacuum oil injection device and method. Background Technology

[0002] In the manufacturing or on-site installation of large power transformers, vacuum oil injection of insulating oil is a necessary step to ensure the electrical insulation performance of the transformer. To remove moisture and gas from the oil, degassing treatment is usually required before the oil injection stage. Existing oil injection schemes generally use traditional degassing and injection devices. The front-end degassing structure of such devices has limitations, resulting in a limited effective contact area between the insulating oil and the vacuum environment, and insufficient degassing efficiency. At the same time, in the actual oil injection stage, the oil injection flow rate and rate mainly rely on manual adjustment by operators based on experience, lacking real-time linkage control with the actual internal pressure state of the transformer. Due to incomplete degassing in the early stage, coupled with the lack of precise matching between the oil injection flow rate and internal pressure, fluctuations in the internal vacuum of the transformer are easily caused, leading to bubbling of the insulating oil, affecting the stability of the insulation impregnation process and the final product quality.

[0003] Therefore, how to improve the gas-liquid separation and degassing efficiency during the vacuum injection process of insulating oil, and how to achieve adaptive and stable adjustment of the oil injection rate according to the internal pressure state of the transformer to eliminate the risk of bubble overflow, has become an urgent technical problem to be solved. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a transformer insulation vacuum oil injection device and method. Specifically, the technical solution of the present invention is as follows: A transformer insulation vacuum oil injection device includes: Mobile base; A degassing tank is fixedly connected to the top of the movable base. The top of the degassing tank is provided with a swirl atomizing nozzle and an air intake port, and the bottom of the degassing tank is provided with an oil outlet port. Inside the degassing tank, there is a support rod and a corrugated diffuser plate fixed to the support rod. A vacuum pump is connected to the extraction port via a vacuum pipeline; An oil injection pump is connected to the oil outlet via an oil inlet pipe. The oil outlet of the oil injection pump is connected to the oil inlet valve of the external transformer body via an oil outlet pipe. The power input terminal of the oil injection pump is connected to a variable frequency motor. A pressure transmitter is installed at the pressure measuring port on the top of the transformer body; The controller is connected to the vacuum pump, the variable frequency motor, and the pressure transmitter. The controller controls the vacuum pump and the variable frequency motor, and acquires the pressure sensing data from the pressure transmitter.

[0005] As a preferred embodiment of the present invention, the corrugated diffuser has a multi-layer structure, and the multiple corrugated diffusers are fixed to the support rod from top to bottom. The corrugated diffuser is a continuous V-shaped corrugated structure formed by pressing perforated metal plates, wherein the corrugation extension directions of adjacent corrugated diffusers are perpendicular to each other.

[0006] As a preferred embodiment of the present invention, the swirling atomizing nozzle is internally machined with a spiral guide groove, and the swirling atomizing nozzle is connected to the center of the top of the degassing tank via a flange.

[0007] As a preferred embodiment of the present invention, the movable base is a rectangular frame welded from channel steel, and four universal load-bearing wheels are fixed at the four corners of the bottom of the movable base.

[0008] In a preferred embodiment of the present invention, the oil injection pump is a gear pump, and the variable frequency motor is connected to the power input end of the oil injection pump through a plum blossom-shaped flexible coupling, and the variable frequency motor steplessly adjusts the speed of the oil injection pump.

[0009] As a preferred embodiment of the present invention, the bottom of the degassing tank is funnel-shaped, and the oil outlet is located at the lowest point of the funnel-shaped bottom.

[0010] The control method for the transformer insulation vacuum oil injection device includes: S1. Control the vacuum pump to perform vacuuming operation on the transformer body and the degassing tank, and acquire the pressure sensing data of the pressure transmitter in real time according to the preset sampling period. S2. Determine whether the pressure sensing data is less than or equal to a preset basic vacuum threshold. S3. If the pressure sensing data is greater than the basic vacuum threshold, continue the vacuuming operation. S4. If the pressure sensing data is less than or equal to the basic vacuum threshold, control the insulating oil to enter the degassing tank through the swirling atomizing nozzle, the insulating oil is degassed by the corrugated diffuser, and control the vacuum pump to discharge the evolved gas. S5. Control the variable frequency motor to drive the oil injection pump to inject the degassed insulating oil into the transformer body, and obtain the current pressure inside the transformer body in real time according to the sampling period; S6. Determine whether the current pressure is greater than or equal to the preset bubble-over-pressure; S7. If the current pressure is less than the critical pressure for bubble turning, maintain the speed of the variable frequency motor; S8. If the current pressure is greater than or equal to the critical pressure for bubbling, calculate the total speed reduction correction value, and reduce the speed of the variable frequency motor according to the total speed reduction correction value to reduce the oil injection flow rate.

[0011] As a preferred embodiment of the present invention, the total rate reduction correction value is determined based on the degree of deviation between the current pressure and the preset critical pressure for bubble formation, as well as the dynamic characteristics of pressure changes.

[0012] As a preferred embodiment of the present invention, reducing the speed of the variable frequency motor includes: Real-time acquisition of subsequent pressure sensing data inside the transformer body; Determine whether the subsequent pressure sensing data is less than the preset safe recovery pressure; If the subsequent pressure sensing data is greater than or equal to the safe recovery pressure, maintain the speed of the variable frequency motor; If the subsequent pressure sensing data is less than the safe recovery pressure, the speed of the variable frequency motor is gradually increased by a fixed step size; Repeat the process of acquiring pressure sensor data and adjusting speed until the insulating oil fills the transformer body.

[0013] As a preferred embodiment of the present invention, the process of the insulating oil being degassed by the corrugated diffuser includes: The insulating oil is broken into fine oil droplets under the action of centrifugal force. The tiny oil droplets fall onto the corrugated diffuser plate located above under the action of gravity, and spread along the V-shaped corrugated surface to form an oil film; The oil film is broken and dropped twice at the perforation of the corrugated diffuser plate, and then changes its flow direction and re-spreads on the corrugated diffuser plate below.

[0014] The present invention has the following beneficial effects: 1. The degassing tank of the present invention is equipped with a swirling atomizing nozzle and a multi-layer corrugated diffuser plate; the insulating oil is broken into fine oil droplets under the action of swirling centrifugal force, and drips onto the corrugated diffuser plate to spread along the continuous V-shaped corrugated surface to form an oil film, and then undergoes secondary drop and breakage at the perforation, and then changes the flow direction in the lower layer to spread again; this structure effectively increases the effective contact area between the insulating oil and the vacuum environment, realizes multi-stage drop and spread, greatly improves the efficiency of gas-liquid separation, and solves the problem of incomplete degassing in traditional degassing devices; 2. This invention obtains the current internal pressure of the transformer in real time through a pressure transmitter and compares it with the preset critical pressure for bubbling. When there is a risk of bubbling, the controller calculates the total speed reduction correction value based on the pressure difference and the rate of change to automatically reduce the speed of the variable frequency motor. When the pressure is lower than the safe recovery pressure, the speed is gradually increased. This control method realizes real-time linkage adjustment between the oil injection flow rate and the internal pressure state, reduces the reliance on manual experience, realizes automated control of the oil injection process, effectively suppresses the bubbling phenomenon of insulating oil caused by vacuum fluctuations, and ensures the stability of the insulating oil injection process. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall external structure of the device; Figure 2 This is a schematic diagram of the movable base and its connection structure; Figure 3 This is a schematic diagram of the oil injection pump and its connection structure; Figure 4 This is a schematic diagram of a corrugated diffuser structure; Figure 5 This is a structural diagram of a rectangular frame; Figure 6 This is a flowchart of the method of the present invention.

[0016] In the diagram: 1. Movable base; 2. Degassing tank; 3. Swirl atomizing nozzle; 4. Air extraction port; 5. Oil outlet; 6. Support rod; 7. Corrugated diffuser; 8. Vacuum pump; 9. Vacuum pipeline; 10. Oil injection pump; 11. Oil inlet pipeline; 12. Oil outlet; 13. Oil outlet pipeline; 14. Transformer body; 15. Oil inlet valve; 16. Power input terminal; 17. Variable frequency motor; 18. Pressure transmitter; 19. Pressure measuring port; 20. Controller; 21. Spiral guide groove; 22. Flange; 23. Rectangular frame; 24. Universal load-bearing wheel; 26. Plum blossom-shaped flexible coupling; 27. Transverse reinforcing beam; 28. Longitudinal reinforcing beam; 30. Vibration damping rubber pad; 31. Two halves of the coupling claw; 32. Intermediate elastic body; 40. Punch. Detailed Implementation

[0017] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. Example 1:

[0018] Combination Figure 1 As shown, the transformer insulation vacuum oil injection device includes: Mobile base 1; Degassing tank 2 is fixedly connected to the top of the movable base 1. The top of the degassing tank 2 is provided with a swirl atomizing nozzle 3 and an air intake 4. The bottom of the degassing tank 2 is provided with an oil outlet 5. Inside the degassing tank 2, there is a support rod 6 and a corrugated diffuser 7 fixed on the support rod 6. Vacuum pump 8 is connected to vacuum port 4 via vacuum line 9; The oil pump 10 is connected to the oil outlet 5 through the oil inlet pipe 11. The oil outlet 12 of the oil pump 10 is connected to the oil inlet valve 15 of the external transformer body 14 through the oil outlet pipe 13. The power input terminal 16 of the oil pump 10 is connected to the frequency converter motor 17. The pressure transmitter 18 is located at the pressure measuring port 19 on the top of the transformer body 14; The controller 20 is connected to the vacuum pump 8, the variable frequency motor 17 and the pressure transmitter 18. The controller 20 controls the vacuum pump 8 and the variable frequency motor 17 and acquires the pressure sensing data from the pressure transmitter 18. This embodiment is used for the vacuum injection of insulating oil during the manufacturing or on-site installation of large power transformers. It addresses the problems of insufficient degassing efficiency, reliance on manual adjustment of the oil injection rate, and foaming caused by vacuum fluctuations in traditional devices. The mobile base 1 adopts a metal frame structure that can support the total weight of the degassing tank 2, vacuum pump 8, oil injection pump 10, and electrical control components, enabling the entire device to be moved and positioned within substations or production workshops. Combination Figure 2 As shown, the degassing tank 2 is fixedly connected to the top of the movable base 1. The top of the degassing tank 2 is provided with a swirl atomizing nozzle 3 and an air extraction port 4. An oil supply pipeline is connected above the swirl atomizing nozzle 3. The oil supply pipeline is used to connect an external oil supply device to continuously supply insulating oil into the degassing tank 2. An oil outlet 5 is provided at the bottom of the degassing tank 2. A support rod 6 and a corrugated diffuser 7 fixed on the support rod 6 are provided inside the degassing tank 2. The swirling atomizing nozzle 3 is used to disperse the insulating oil entering the degassing tank 2 into fine droplets. The corrugated diffuser 7 is used to further spread the droplets into an oil film and cause the oil to break up again at the punch 40 position, thereby increasing the contact area between the oil and the vacuum environment and accelerating the precipitation rate of dissolved gas and moisture. Vacuum pump 8 is connected to vacuum port 4 via vacuum line 9 to maintain a predetermined low-pressure environment inside degassing tank 2 and transformer body 14; oil injection pump 10 is connected to oil outlet 5 via oil inlet line 11, and its oil outlet 12 is connected to oil inlet valve 15 of transformer body 14 via oil outlet line 13; variable frequency motor 17 is connected to power input terminal 16 of oil injection pump 10 to change the flow rate of oil injection pump 10 by adjusting the speed; pressure transmitter 18 is installed at pressure measuring port 19 on the top of transformer body 14. This pressure transmitter 18 is used to collect pressure changes in the gas phase space inside transformer body 14, and the collected data can directly reflect the influence of the oil injection process on the internal vacuum balance. The controller 20 is electrically connected to the vacuum pump 8, the variable frequency motor 17, and the pressure transmitter 18. The controller 20 can be an industrial programmable controller, an embedded control board, or an industrial computer. Its input end receives pressure sensing data, and its output end sends operating commands to the vacuum pump 8 and the variable frequency motor 17. In actual operation, the controller 20 first controls the vacuum pump 8 to work, so that the degassing tank 2 and the transformer body 14 reach the set vacuum level, controls the insulating oil to enter the degassing tank 2 to complete the degassing, and then controls the variable frequency motor 17 to drive the oil injection pump 10 to deliver insulating oil to the transformer body 14, and adjusts the oil injection rate according to the pressure sensing data collected by the pressure transmitter 18. This device, through the cooperation of the front-end degassing structure and the rear-end pressure feedback speed regulation structure, makes the oil injection flow rate no longer set solely by experience, but corresponds to the internal pressure state of the transformer, thereby improving the stability of the insulating oil impregnation process. The basic vacuum threshold can be set from 50Pa to 500Pa according to the transformer capacity and insulation structure. The range of the pressure transmitter 18 can be set from -100kPa to 0kPa, and the sampling period can be set from 10ms to 500ms. The controller 20 can continuously acquire pressure sensing data and execute adjustment commands according to the sampling period. Based on this, those skilled in the art can complete the manufacturing and control implementation of the device.

[0019] Combination Figure 4 As shown, the corrugated diffuser 7 has a multi-layer structure. The multi-layer corrugated diffuser 7 is fixed to the support rod 6 from top to bottom. The corrugated diffuser 7 is a continuous V-shaped corrugated structure made of a perforated 40 metal plate. The corrugated extension directions of adjacent corrugated diffusers 7 are perpendicular to each other. In this invention, the corrugated diffuser 7 is not a regular support plate, but a degassing component that combines the functions of oil flow spreading, path disturbance, and droplet re-breaking. To improve the degassing speed of insulating oil under vacuum conditions, the corrugated diffuser 7 is configured as a multi-layer structure, with the multi-layer corrugated diffuser 7 fixed to the support rod 6 from top to bottom. This multi-layer structure is preferably three layers, but can also be configured as two, four, or five layers depending on the effective height of the degassing tank 2. The corrugated diffuser 7 is made of 1mm to 3mm thick perforated 40 stainless steel plate pressed to form a continuous V-shaped corrugated structure. The stainless steel material can be 304, 316 or other oil-resistant and corrosion-resistant materials. The diameter of the 40 perforations can be set to 2mm to 5mm, the center distance of the holes can be set to 4mm to 8mm, and the height difference between the crests and troughs of the V-shaped corrugations can be set to 15mm to 40mm. The continuous V-shaped corrugated structure allows the oil droplets to disperse and flow along the inclined surface, forming a thin oil film. The thickness of the oil film can be controlled within the range of 0.1mm to 1.5mm, which facilitates the migration of dissolved gas to the free surface. The corrugated extension directions of two adjacent corrugated diffuser plates 7 are perpendicular to each other. Specifically, one layer can be arranged in a north-south direction, another in an east-west direction, or one layer can be arranged in an approximately perpendicular manner with the next layer forming an angle of 75° to 105°. The purpose of this arrangement is to prevent the oil from forming a short flow channel in a single direction, so that the oil changes its flow direction after falling between layers, and increases the residence time inside the degassing tank 2. Since the perforations 40 are distributed on the V-shaped corrugated surface, when the oil film flows through the perforations 40, some of the oil will fall through the perforations and form secondary droplets. The droplets then contact the lower corrugated plate and spread out. Therefore, the multi-layer corrugated diffuser plate 7 does not simply increase the contact area, but improves the gas-liquid separation efficiency through the alternating process of spreading out and falling. Taking the three-layer corrugated diffuser plate 7 as an example, the spacing between adjacent layers can be set to 150mm to 250mm. This spacing ensures that the droplets have sufficient falling stroke to form a re-breaking effect, while avoiding the tank being too tall and causing an increase in structural size. In actual tests, under the same vacuum degree and oil supply conditions, the multi-layer orthogonally arranged corrugated diffuser plate 7 can shorten the degassing time by 15% to 40% compared to the single-layer flat plate structure, and reduce the residual gas content in the oil before entering the transformer body 14, thereby reducing the rise in internal pressure during the oil injection process. Specifically, to verify the above technical effects, a comparative experiment was conducted: the experimental conditions were set as follows: oil supply flow rate of 50L / min, oil temperature of 55℃, and basic vacuum degree maintained at 100Pa; the control group used a single-layer stainless steel plate as a diffuser, while the experimental group used the V-shaped corrugated diffuser 7 of the present invention with a thickness of 2mm, a hole diameter of 3mm, and three orthogonally arranged layers. Online degassing measurements showed that the moisture content in the insulating oil treated in the control group was 8 ppm and the gas content was 0.5%; while the moisture content in the insulating oil treated in the experimental group decreased to 3 ppm and the gas content decreased to 0.15%. These experimental data fully demonstrate that the multi-layer orthogonal corrugated structure significantly increases the effective surface area for gas-liquid separation and prolongs the vacuum exposure time through the alternating process of spreading and falling, providing reliable technical support for stabilizing the internal pressure during the oil injection process.

[0020] The swirl atomizing nozzle 3 has a spiral guide groove 21 machined inside, and the swirl atomizing nozzle 3 is connected to the top center of the degassing tank 2 through a flange 22; The function of the swirl atomizing nozzle 3 is to transform the continuous oil flow entering the degassing tank 2 into dispersed droplets with an expanded surface area. To achieve this purpose, the swirl atomizing nozzle 3 is internally machined with a spiral guide groove 21. The number of guide grooves can be 2 to 6, the spiral rise angle can be set to 20° to 45°, and the groove depth can be set to 0.5mm to 3mm. When the oil flows through the guide groove under the pressure difference, it forms a rotational velocity component and forms a group of conical droplets after being sprayed out. The nozzle is connected to the top center of the degassing tank 2 via flange 22. The top center position allows the droplet group to be distributed downward along the central axis of the tank, which can fully cover the effective area of ​​the corrugated diffuser plate 7 below. The flange 22 connection method facilitates nozzle disassembly and maintenance. An oil-resistant sealing gasket can be installed between the flanges 22 to ensure that no leakage occurs in the degassing tank 2 under high vacuum. The nozzle orifice diameter can be set from 1mm to 6mm according to the oil supply, the atomization cone angle can be set from 30° to 90°, and the oil supply pressure difference can be set from 0.05MPa to 0.4MPa. Within this range, insulating oil can be broken down into droplets with an average particle size of 0.1 mm to 1.5 mm. As the droplet size decreases, the exposed surface area per unit volume of oil increases, which is beneficial for dissolved gas to migrate from the inside of the oil to the surface and escape under vacuum. The nozzle is also positioned at the top center of the degassing tank 2, which has a complementary function. When the lower support rod 6 and the corrugated diffuser 7 are arranged around this central axis, the diffusion distance of the droplets in space is more easily matched with the receiving range of the plate surface, which can reduce the convergence caused by excessive local oil volume. For insulating oils with a viscosity greater than a preset viscosity threshold, the nozzle orifice diameter can be appropriately increased or the inlet pressure differential can be increased to maintain the droplet dispersion effect. Here, the preset viscosity threshold can be set according to the specific insulating oil grade and its flow characteristics at the standard operating temperature. For example, in this embodiment, it can be set to 12 mm² / s. The specific value should be confirmed based on the actual selection. For operating conditions where the ambient temperature is lower than the preset temperature threshold, the preset temperature threshold is usually determined based on the pour point or low-temperature viscosity-temperature characteristics of the insulating oil. For example, it can be set to 10°C or 15°C. The insulating oil can be preheated to 40°C to 60°C before oil supply to reduce viscosity and stabilize atomization. In this embodiment, when the swirling atomizing nozzle 3 is used in conjunction with the multi-layer corrugated diffuser 7, the nozzle undertakes the initial breaking action, while the corrugated diffuser 7 undertakes the flow spreading and secondary breaking action, thereby making the degassing process a continuous surface area expansion process.

[0021] Combination Figure 5 As shown, the movable base 1 is a rectangular frame 23 welded from channel steel, and four universal load-bearing wheels 24 are fixed at the four corners of the bottom of the movable base 1. The mobile base 1 is used to support the degassing tank 2, vacuum pump 8, oil injection pump 10, frequency converter motor 17, and controller 20, and meets the requirements of on-site movement, positioning, and operational stability. The mobile base 1 adopts a rectangular frame 23 welded from channel steel. The specifications of the channel steel can be selected according to the total load, using No. 8, No. 10, or No. 12 channel steel. The overall length can be set from 1200mm to 2500mm, and the width can be set from 700mm to 1500mm. The rectangular frame 23 structure facilitates the partitioning of each component along the length direction, maintaining a reasonable distance between the degassing tank 2, vacuum pump 8, and oil injection pump 10, and reducing maintenance interference. The bottom is fixed with four universal load-bearing wheels 24. The rated load capacity of a single load-bearing wheel can be set from 200kg to 800kg. At least two of the universal load-bearing wheels 24 can be equipped with a mechanical locking structure so that the equipment can be fixed after it is moved into place. The purpose of using universal load-bearing wheels 24 is to adapt to the working conditions of complex ground obstacles and limited passage space in substations or assembly workshops, so that the device can quickly adjust its direction in different positions. To improve operational stability, a transverse reinforcing beam 27 and a longitudinal reinforcing beam 28 can be added to the rectangular frame 23. A thickened mounting plate can also be installed in the installation area of ​​the degassing tank 2 to reduce the impact of vibration of the vacuum pump 8 on the tank connection parts during operation. The controller 20, cable tray and electrical box can be installed on one side of the base. The vacuum pump 8 and oil injection pump 10 can be installed in the lower part or middle of the base to lower the overall center of gravity. The connection between the mobile base 1 and each piece of equipment can be achieved by bolt fixing, welding fixing, or bolt fixing with a base pad. Due to the negative pressure formed inside the degassing tank 2 and the pulsating load generated when the oil pump 10 is working, the mobile base 1 can also be equipped with vibration damping rubber pads 30 above the universal load-bearing wheels 24 to reduce the transmission of vibration to the pressure transmitter 18 circuit and controller 20. This structure makes the device both mobile and has sufficient rigidity and load-bearing capacity to meet the requirements of on-site implementation.

[0022] Combination Figure 3 As shown, the oil pump 10 is a gear pump, and the variable frequency motor 17 is connected to the power input end 16 of the oil pump 10 through the plum blossom-shaped flexible coupling 26. The variable frequency motor 17 can steplessly adjust the speed of the oil pump 10. Oil pump 10 is responsible for delivering the degassed insulating oil to transformer body 14. In order to make a clear correspondence between flow rate and motor speed, oil pump 10 is preferably a gear pump. Gear pump has the characteristics of compact structure, stable output flow rate and speed relationship, and is suitable for conveying insulating oil. Its displacement can be selected from 5L / min to 100L / min according to the transformer capacity. The variable frequency motor 17 is connected to the power input end 16 of the oil injection pump 10 via a plum blossom-shaped flexible coupling 26. This coupling consists of two half-coupling jaws 31 and an intermediate elastic body 32, which can compensate for minor radial, angular, and axial deviations when the shaft of the variable frequency motor 17 and the shaft of the oil injection pump 10 are installed, and reduce transmission vibration. The direct-drive structure without reduction gears allows the output speed change of the variable frequency motor 17 to be transmitted to the gear pump in real time, which makes it easy for the controller 20 to adjust the flow rate in real time according to the pressure change signal. The variable frequency motor 17 can be a three-phase asynchronous motor with a power of 1.5kW to 15kW. The output frequency range of the matching frequency converter can be set from 10Hz to 60Hz, and the corresponding gear pump speed range can be set from 300rpm to 1800rpm. The stepless adjustment of the speed of the oil injection pump 10 by the variable frequency motor 17 means that the controller 20 can output continuously changing frequency commands, rather than just switching between a few fixed gears. This allows the oil injection flow rate to change smoothly as needed. A filter can be installed before the gear pump inlet, with a filtration accuracy of 10μm to 50μm, to prevent solid particles from entering the pump chamber and affecting meshing; a pressure gauge and a safety valve can be installed on the outlet side, with the safety valve opening pressure set to 0.3MPa to 1.2MPa, to prevent pump overload when the oil outlet line 13 is blocked; in this embodiment, the gear pump provides stable oil delivery capacity, the plum blossom-shaped flexible coupling 26 provides mechanical buffering and deviation compensation, and the variable frequency motor 17 provides adjustable speed input. The three work together to ensure that the oil injection flow rate corresponds to the calculation result of the controller 20.

[0023] The bottom of the degassing tank 2 is funnel-shaped, and the oil outlet 5 is located at the lowest point of the funnel-shaped bottom; The bottom of the degassing tank 2 is funnel-shaped, and the oil outlet 5 is located at the lowest point of the funnel. This structure is used to collect the degassed insulating oil after being treated by the multi-layer corrugated diffuser plate 7 and to reduce residue at the bottom of the tank. The cone angle of the funnel-shaped bottom can be set to 40° to 80°, preferably 50° to 70°. Within this range, the oil can converge to the lowest point without obstruction under the action of gravity. The oil outlet 5 can be set as a flange 22 interface or a threaded interface, and the diameter can be set to DN20 to DN65, selected according to the rated flow rate of the oil injection pump 10. Since the insulating oil in the degassing tank 2 has been spread and dropped multiple times and then converges at the bottom, if the bottom is flat, it is easy to form a local stagnation area. After the machine is stopped, a lot of oil will remain, which is not conducive to cleaning and switching between different batches of oil. The funnel-shaped bottom makes it difficult for the oil to form a stagnant flow area at the bottom of the tank, which can improve the oil utilization rate and make the oil pump 10 inlet obtain constant oil suction conditions. To prevent turbulent air entrainment during bottom oil collection, a short straight pipe section with a length of 50mm to 200mm can be installed at the connection between the oil outlet 5 and the oil inlet pipe 11. If necessary, an anti-vortex structure can be added inside. The funnel-shaped bottom also facilitates the installation of a drain or sampling port. The drain can be located on the side of the lowest point for draining residual oil and impurities during equipment maintenance. When this structure is combined with the upper multi-layer corrugated diffuser plate 7, the upper part is responsible for increasing the degassing area, while the lower part is responsible for stabilizing oil collection and continuously supplying oil to the oil injection pump 10, thereby ensuring that the front-end degassing effect can be stably transferred to the subsequent oil injection stage. Example 2:

[0024] Combination Figure 6 As shown, the control method for the transformer insulation vacuum oil injection device includes: S1. Control the vacuum pump 8 to perform vacuuming operation on the transformer body 14 and degassing tank 2, and acquire the pressure sensing data of the pressure transmitter 18 in real time according to the preset sampling cycle. S2. Determine whether the pressure sensor data is less than or equal to the preset basic vacuum threshold. S3. If the pressure sensor data is greater than the basic vacuum threshold, continue the vacuuming operation. S4. If the pressure sensor data is less than or equal to the basic vacuum threshold, control the insulating oil to enter the degassing tank 2 through the swirling atomizing nozzle 3. The insulating oil is degassed by the corrugated diffuser 7, and the vacuum pump 8 is controlled to discharge the evolved gas. S5. Control the variable frequency motor 17 to drive the oil injection pump 10 to inject the degassed insulating oil into the transformer body 14, and obtain the current pressure inside the transformer body 14 in real time according to the sampling cycle. S6. Determine whether the current pressure is greater than or equal to the preset bubble-over-pressure; S7. If the current pressure is less than the critical pressure for bubble overflow, maintain the speed of the variable frequency motor 17. S8. If the current pressure is greater than or equal to the critical pressure for bubble overturning, calculate the total speed reduction correction value, and reduce the speed of the variable frequency motor 17 according to the total speed reduction correction value to reduce the oil injection flow rate. The purpose is to unify the front-end degassing and the rear-end oil injection speed regulation by pressure sensing data; the controller 20 starts the vacuum pump 8 to perform vacuuming operation on the transformer body 14 and the degassing tank 2; the pressure transmitter 18 is arranged at the pressure measuring port 19 on the top of the transformer body 14, and its collected value is used to characterize the change of vacuum inside the transformer body 14. The controller 20 acquires pressure sensing data at a predetermined sampling period, which can be set from 10ms to 500ms. In terms of data flow and interaction, the pressure transmitter 18 is electrically connected to the data input interface of the controller 20 via a standard 4-20mA analog signal line or a serial communication standard 485 bus. When an analog signal is used, the internal analog-to-digital conversion module of the controller 20 samples the current signal at a set sampling frequency and linearly maps it to the corresponding pressure physical quantity value, such as mapping 4-20mA to -100kPa to 0kPa. When a digital bus is used, the controller 20 acts as the master station and periodically sends read commands to parse the returned data frames to extract the pressure value. The clearly defined data interaction protocol and format conversion process ensure that the front-end physical pressure can be accurately converted into a digital input that the controller 20 can process. The basic vacuum threshold is the criterion for starting the oil injection preparation process. Its value can be set from 50Pa to 500Pa according to the transformer type, the moisture content control requirements of the insulating paper, and the altitude conditions at the site. If the real-time pressure sensing data is greater than the basic vacuum threshold, the controller 20 continues to maintain the operation of the vacuum pump 8 and does not allow the insulating oil to enter the degassing tank 2. If the pressure sensor data is less than or equal to the basic vacuum threshold, it indicates that the system vacuum has reached the predetermined level. The controller 20 controls the external oil supply valve or oil supply pump to allow the insulating oil to enter the degassing tank 2 through the swirling atomizing nozzle 3. When the insulating oil is degassed by the corrugated diffuser 7, the vacuum pump 8 continues to run, discharging the gas and water vapor precipitated from the oil from the extraction port 4. The degassed insulating oil collects at the bottom of the tank, and the controller 20 controls the variable frequency motor 17 to drive the oil injection pump 10 to inject the degassed insulating oil into the transformer body 14. During the oil injection stage, the controller 20 continuously acquires the current pressure inside the transformer body 14 and compares the current pressure with the preset bubble-over-bubbling critical pressure. In this invention, the bubble-over-bubbling critical pressure refers to the dynamic critical point at which microbubbles begin to have a continuous tendency to escape. This value can be obtained through experimental calibration. For example, under specific transformer models and specific oil temperature conditions, the oil injection flow rate is gradually increased and the pressure changes and the surface state of the insulating oil are observed to determine the pressure value before the microbubbles appear obviously as the bubble-over-bubbling critical pressure. If the current pressure is less than the critical pressure for bubbling, the controller 20 maintains the current speed of the variable frequency motor 17, so that the oil injection pump 10 maintains the current oil injection flow rate; if the current pressure is greater than or equal to the critical pressure for bubbling, the controller 20 calculates the total speed reduction correction value and reduces the speed of the variable frequency motor 17 according to the correction value; after the speed of the variable frequency motor 17 decreases, the flow rate of the gear pump decreases synchronously, the amount of oil injected into the transformer body 14 decreases, the vacuum pump 8 has more time to discharge the released gas and relieve the pressure rise, and the internal pressure tends to fall back; This method does not employ a complex fluid model, but directly uses the relationship between the current pressure and the threshold to determine whether the oil injection rate needs to be adjusted. Therefore, the control logic is clear and can be stably implemented by the industrial controller 20. For transformers of different capacities, only parameters such as the basic vacuum threshold, the critical pressure for bubble overflow, and the upper and lower limits of motor speed need to be modified to adapt it. The basic vacuum threshold, current pressure, and bubble-over-critical pressure have different logical meanings in this method; the basic vacuum threshold is used to determine whether the vacuuming stage has ended, and it corresponds to the minimum vacuum condition that allows the start of oil degassing and subsequent oil injection. The current pressure is the instantaneous pressure value that the pressure transmitter 18 actually outputs in each sampling cycle during the oil injection process and is converted by the controller 20; the bubble-over-bubbling critical pressure is used to determine whether the current oil injection flow has brought the transformer body 14 close to the instability range, which corresponds to the risk boundary that needs to trigger speed reduction control. The comparison order of the three is as follows: first, compare the pressure sensor data with the basic vacuum threshold to determine whether to allow entry into the oil supply and injection stage; after entering the oil injection stage, compare the current pressure with the bubble-over-crow critical pressure to determine whether to implement a speed reduction. The critical pressure for bubble formation can be determined in the following order: Step 1, select the target transformer model, oil temperature range and vacuum pump 8 configuration, and first evacuate the transformer body 14 to below the basic vacuum threshold; Step 2, start the oil injection pump 10 at a low initial speed and record the output value of the pressure transmitter 18 during each stable operating period; Step 3, increase the speed of the oil injection pump 10 by a fixed increment and continuously observe the pressure value change and whether continuous microbubbles appear in the preset observation window, exhaust status or oil level area on the transformer body 14; Step four: The stable pressure value before the first appearance of continuous microbubbles, or the value after the pressure value corresponding to the first appearance of continuous microbubbles has been reduced by 5Pa to 30Pa in the safe direction, is determined as the bubble-over-bubbling critical pressure. After adopting the above method, the bubble-over-bubbling critical pressure is not an arbitrary set value, but is jointly calibrated by specific equipment, oil temperature and oil injection conditions, so that the subsequent speed reduction control has a clear source. The controller 20 can process the pressure sensing data in the following order: at the beginning of each sampling cycle, read the output signal of the pressure transmitter 18; convert the read signal into the corresponding pressure value and store it in the current pressure register; if the system is in the vacuuming stage, call the basic vacuum threshold comparison module to output the command to continue vacuuming or allow oil to enter. If the system is in the oil filling stage, the bubble judgment module is called to output a command to maintain the rotation speed or enter the speed reduction calculation; the corresponding command is transmitted to the vacuum pump 8 control unit and the variable frequency motor 17 control unit for execution; thus, the source of pressure sensing data, comparison object, judgment result and execution flow have a clear correspondence, and those skilled in the art can complete the control program based on this.

[0025] The total rate reduction correction value is determined based on the degree of deviation between the current pressure and the preset critical pressure for bubble overshoot, as well as the dynamic characteristics of pressure changes. The total speed reduction correction value is used to quantify the speed reduction of the variable frequency motor 17; the controller 20 reads the current pressure in each sampling period and stores the pressure of the previous sampling period; considering that the operation of the vacuum pump 8 and the pipeline fluid may introduce high-frequency pressure pulsation noise in the industrial site, in order to ensure the stable programmable implementation of the algorithm, the controller 20 performs moving average filtering on the raw pressure sensing data before reading the current pressure and storing it in the current pressure register area; Specifically, the controller 20 internally establishes a first-in-first-out (FIFO) data buffer of length N. Each time a new pressure physical quantity value is collected, it is pushed into the buffer and the oldest data is discarded. The arithmetic mean of the N data in the buffer is calculated, and this average value is used as the current pressure for the current sampling period in subsequent calculations. Through this data flow and preprocessing mechanism, high-frequency interference is effectively filtered out, and the drastic oscillation of the pressure change rate caused by a single abnormal change in data is avoided, thereby ensuring the accuracy and reliability of the calculation of the trend deceleration compensation. The difference between the current pressure and the critical pressure for bubble overflow reflects the proximity of the current operating point to the risk boundary and can be defined as the pressure deviation. Multiplying this pressure deviation by the first proportional coefficient yields the basic speed reduction compensation. The unit of the first proportional coefficient can be set to speed per unit of pressure. If the pressure is in Pa and the speed is in revolutions per minute, the first proportional coefficient can be set to 0.01 to 5 rpm / Pa. The specific value is determined based on the transformer volume, the displacement of the oil injection pump 10, and the pumping speed of the vacuum pump 8. The pressure change rate is obtained by subtracting the pressure from the previous sampling period from the current pressure and then dividing by the sampling period. This rate reflects the upward or downward trend of the pressure. Multiplying this rate by a second proportionality coefficient yields the trend-based speed reduction compensation. The unit of the second proportionality coefficient can be set to speed multiplied by time per unit of pressure, and can be set from 0.001 to 2 rpm·s / Pa depending on the system's sensitivity to pressure change rates. Adding the basic speed reduction compensation to the trend-based speed reduction compensation yields the total speed reduction correction value, calculated using the following formula: ; In the formula, This represents the total speed reduction correction value. Indicates current pressure. This indicates the critical pressure for bubble formation. This represents the first proportionality coefficient. This indicates the pressure from the previous sampling period. Indicates the sampling period. This represents the second proportional coefficient; the controller 20 uses this coefficient to adjust the inverter output frequency or directly adjust the motor target speed. If the total speed reduction correction value is too small, a minimum adjustment resolution can be set, such as 1 rpm to 10 rpm, to avoid frequent fine adjustments. If the total speed reduction correction value is too large, a maximum single speed reduction limit can be set, such as 50 rpm to 300 rpm, to avoid sudden changes in flow rate. The algorithm utilizes both the current pressure position and the pressure change trend. The basic speed reduction compensation is responsible for handling the static risk when approaching the critical pressure for bubble overflow, while the trend speed reduction compensation is responsible for handling the dynamic risk when the pressure rises rapidly. Therefore, compared with the on / off speed regulation method that only relies on a single pressure threshold, it is more capable of implementing speed reduction before the risk of bubble overflow increases. For example, when the critical pressure for bubble formation is set to 300 Pa, the current pressure is 320 Pa, the pressure of the previous sampling period is 300 Pa, the sampling period is 0.1 s, the first proportional coefficient is 0.5 rpm / Pa, and the second proportional coefficient is 0.02 rpm·s / Pa, the basic speed reduction compensation is 10 rpm, the trend speed reduction compensation is 4 rpm, and the total speed reduction correction is 14 rpm. Based on this, the controller 20 reduces the target speed of the motor by 14 rpm. The input sources for this calculation process include the pressure value of the current sampling period, the pressure value of the previous sampling period, the pre-stored critical pressure for bubble formation, the sampling period parameters, and the first and second proportional coefficients. The controller 20 can set the current pressure register, the historical pressure register, and the parameter register in the memory. After each sampling is completed, the current pressure register is updated first, and then the pressure value of the previous sampling period in the historical pressure register is called for comparison and calculation. After the total speed reduction correction value is output, the current pressure is written into the historical pressure register for use in the next sampling period. Therefore, the total speed reduction correction value is not an invisible output without clear logic, but is generated by a clear sequence of steps: data reading, difference calculation, rate of change calculation, compensation amount calculation, and result limiting. The logical function of the pressure change rate is to reflect the trend of pressure change, rather than just the absolute magnitude of pressure. When the current pressure has reached or slightly exceeded the critical pressure for bubble formation, but its change rate is close to zero or negative, it indicates that the system pressure has stabilized or begun to decline. In this case, the trend reduction compensation amount can be small or zero. When the current pressure is higher than the critical pressure for bubble formation and the change rate is positive, it indicates that the pressure is still rising. The trend reduction compensation amount is used to amplify the rate of decrease in advance. To avoid reverse acceleration interference when pressure falls back, the trend deceleration compensation amount can be limited to no less than zero. That is, when a negative value is obtained by calculating according to the above rate of change, it is treated as zero, and only the basic deceleration compensation amount is retained to participate in the calculation of the total deceleration correction value. After adopting this processing method, the trend term only enhances the deceleration action during the pressure rise phase, and does not directly trigger the acceleration action during the pressure fall phase. The acceleration action is undertaken by the recovery logic, and the division of labor between the front and back controls is clear. The controller 20 can perform the total speed reduction correction value calculation according to the following steps: Step 1, read the current pressure value and compare it with the bubble-turning critical pressure, and start this calculation process only when the current pressure is greater than or equal to the bubble-turning critical pressure; Step 2, calculate the difference between the current pressure and the bubble-turning critical pressure and obtain the basic speed reduction compensation amount; Step 3, calculate the rate of change of the current pressure relative to the pressure of the previous sampling period and obtain the trend speed reduction compensation amount; Step 4, add the two compensation amounts and perform minimum adjustment resolution and maximum single speed reduction limit processing to obtain the executable total speed reduction correction value; Step 5, convert the correction value into the frequency correction command of the frequency converter or the target speed correction command of the motor and output it to the control terminal of the variable frequency motor 17; After the above breakdown, those skilled in the art can reproduce the calculation process without relying on a complex model.

[0026] After reducing the speed of the variable frequency motor 17, the process includes: acquiring subsequent pressure sensing data inside the transformer body 14 in real time; determining whether the subsequent pressure sensing data is less than the preset safe recovery pressure; if the subsequent pressure sensing data is greater than or equal to the safe recovery pressure, maintaining the speed of the variable frequency motor 17; if the subsequent pressure sensing data is less than the safe recovery pressure, gradually increasing the speed of the variable frequency motor 17 by a fixed step size; repeating the acquisition of pressure sensing data and speed adjustment process until the insulating oil fills the transformer body 14. After reducing the speed of the variable frequency motor 17 according to the total speed reduction correction value, the controller 20 continues to acquire subsequent pressure sensing data at the original sampling period; the safety recovery pressure is used to determine whether the internal vacuum balance has been restored, and its value is lower than the bubble-over-bubbling critical pressure, and a recovery margin is formed between the two; the safety recovery pressure can be set to the bubble-over-bubbling critical pressure minus 10Pa to 150Pa, and the specific difference can be determined according to the system fluctuation amplitude and the response speed of the controller 20; If the subsequent pressure sensing data is greater than or equal to the safe recovery pressure, the controller 20 keeps the current speed of the variable frequency motor 17 unchanged and does not perform the speed increase operation to ensure that the vacuum pump 8 has enough time to continue to discharge the gas released inside the transformer body 14; if the subsequent pressure sensing data is less than the safe recovery pressure, it indicates that the internal pressure has fallen back to the preset safe range, and the controller 20 gradually increases the speed of the variable frequency motor 17 by a fixed step size. The fixed step size can be set to increase by 5 rpm to 50 rpm per adjustment cycle, or it can be converted to increase the frequency of the inverter by 0.1 Hz to 1 Hz each time; the adjustment cycle can be set to 0.5 s to 10 s, which is longer than the pressure sampling cycle, so as to avoid the speed-up process being too frequent; if the pressure rises again to or near the critical pressure of bubble-over after speed-up, the controller 20 re-executes the total speed reduction correction value calculation and speed-down process; this method makes the oil injection process repeat between speed reduction maintenance and step speed-up until the insulating oil fills the transformer body 14; The method for determining whether the insulating oil is full can be by the oil level gauge reaching the specified position, the cumulative oil volume reaching the preset value, or by the operator confirming the oil level; the technical significance of this recovery logic is that it not only has the ability to reduce speed to suppress risks, but also has the ability to gradually restore the flow rate after the risks subside, thereby avoiding the oil pump 10 from staying in a low-speed state for a long time. In actual debugging, the fixed step size and the safety recovery pressure difference can be set together. For example, in equipment where the pressure fluctuation range exceeds the preset benchmark, a low fixed step size and a high recovery margin can be selected, and in equipment where the pressure fluctuation range is lower than the preset benchmark, a high fixed step size and a low recovery margin can be selected to improve the utilization rate of oil injection time. The physical meaning of safe recovery pressure is: after a deceleration has occurred, it is used to determine whether the system has returned from the bubble-over-risk boundary to the acceptable stable region. It is not the same as the basic vacuum threshold, nor is it the same as the bubble-over-critical pressure. Instead, it is an intermediate control threshold below the bubble-over-critical pressure. The purpose of setting this threshold is to form a hysteresis interval between the deceleration trigger point and the recovery acceleration point, so as to avoid the speed from oscillating back and forth when the current pressure is just below the bubble-over-critical pressure. The processing procedure after reducing the speed of the variable frequency motor 17 can be implemented in the following order: Step 1, after the controller 20 completes a speed reduction command output, it enters the recovery monitoring state; Step 2, in the recovery monitoring state, it continuously reads the subsequent pressure sensing data and compares it with the safe recovery pressure; Step 3, if the subsequent pressure sensing data is greater than or equal to the safe recovery pressure, it maintains the current target speed of the motor unchanged and continues to execute Step 2 in a loop. Step four: If the subsequent pressure sensor data is less than the safe recovery pressure, the stepping speed-up subroutine is started, increasing the motor target speed by a fixed step size at the end of an adjustment cycle; Step five: After each speed-up, the subsequent pressure sensor data is read again. If the pressure reaches or exceeds the bubble-over-crowding critical pressure again, the stepping speed-up subroutine is immediately exited and the total speed reduction correction value calculation process is re-entered; Through this sequential control, the flow relationship between speed reduction, holding, recovery speed-up, and speed reduction again is clear, which facilitates program implementation; To avoid exceeding the allowable process limit during the recovery and speed-up phase, the controller 20 can pre-store the upper and lower limits of the target motor speed; the lower limit can be determined by the minimum continuous oil delivery speed required for the stable operation of the oil injection pump 10, and the upper limit can be determined by the maximum allowable oil injection flow rate of the transformer, the rated operating conditions of the gear pump, and the rated speed of the variable frequency motor 17. During the step-up acceleration process, if the target speed after increasing by a fixed step size exceeds the preset upper limit, it is limited to the upper limit; during the deceleration process, if the corrected target speed is lower than the preset lower limit, it is limited to the lower limit; thus, the recovery logic not only has a pressure threshold determination basis, but also has a clear execution boundary. The determination of whether the insulating oil fills the transformer body 14 can be made by a single condition or a combination of conditions. When using a combination of conditions, the following order is preferred: first check whether the oil level gauge has reached the specified level; if the oil level gauge signal is unavailable, check whether the cumulative oil filling amount has reached the preset value corresponding to the transformer model; if manual verification is used on site, the operator shall confirm to stop oil filling after any of the aforementioned conditions are met. After receiving the full filling determination signal, the controller 20 first stops the step speed increase or decrease adjustment, then smoothly reduces the speed of the variable frequency motor 17 to zero, and shuts down the oil pump 10 and related valves; by supplementing the full filling determination and shutdown sequence, those skilled in the art can complete the programming of a complete control process.

[0027] The process of insulating oil being degassed by the corrugated diffuser plate 7 includes: the insulating oil being broken into fine oil droplets under the action of centrifugal force; the fine oil droplets dripping onto the upper corrugated diffuser plate 7 under the action of gravity, spreading along the V-shaped corrugated surface to form an oil film; the oil film being broken into a second drop at the perforation 40 on the corrugated diffuser plate 7, and changing the flow direction to spread again on the lower corrugated diffuser plate 7; The process of insulating oil being degassed by the corrugated diffuser plate 7 is the main source of the front-end degassing efficiency. After the insulating oil enters the swirling atomizing nozzle 3, it obtains a tangential velocity component under the guidance of the spiral guide groove 21. When it is sprayed out, it is subjected to the combined action of swirling centrifugal force and pressure difference, and the continuous liquid flow is broken into fine oil droplets. These fine oil droplets have a high specific surface area in a vacuum environment, which allows some dissolved gas to escape directly from the surface of the droplets. Tiny oil droplets fall onto the corrugated diffuser plate 7 located above under the influence of gravity, disperse and flow along the V-shaped corrugated surface to form an oil film. Due to the continuous undulation of the V-shaped corrugated surface, the local thickness of the oil film changes periodically as it flows on the inclined surface. Dissolved gases in areas with a thickness less than a set value are more likely to migrate to the surface and be carried away by the vacuum system. The perforations 40 on the corrugated diffuser plate 7 cause the oil film to split when it flows to the perforations. Part of it continues to flow along the plate surface, while the other part falls through the perforations 40, thus forming a secondary drop and breakage. The new droplets formed by the second drop expose new free surfaces again, allowing the dissolved gases that did not escape in the previous stage to further precipitate out; after the new droplets fall to the corrugated diffuser 7 located below, the oil flow direction changes and resumes flow because the corrugation extension directions of adjacent corrugated diffusers 7 are perpendicular to each other, avoiding direct penetration and falling along the upper path; this process can be repeated between two or more corrugated diffusers 7. Taking the three-layer corrugated diffuser plate 7 as an example, the insulating oil forms an initial oil film in the first layer, and completes the first re-breakup at the perforation 40. In the second layer, it changes direction and forms a new oil film, and completes the second re-breakup at the perforation 40 in the second layer. In the third layer, it continues to spread and finally collects at the bottom of the degassing tank 2. If the oil temperature is low and the viscosity increases, the oil droplet breakup and oil film formation effect can be maintained by appropriately increasing the oil supply pressure difference, increasing the nozzle atomization cone angle, or increasing the preheating temperature. Through this implementation process, the insulating oil has undergone multiple surface area expansions and multi-stage degassing before entering the transformer body 14. As a result, the amount of residual gas released in the subsequent oil injection stage is reduced, and the internal pressure fluctuation amplitude monitored by the pressure transmitter 18 is correspondingly reduced, which is beneficial for implementation in conjunction with the control method.

[0028] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A transformer insulation vacuum oil injection device, characterized in that, include: Mobile base (1); A degassing tank (2) is fixedly connected above the movable base (1). The top of the degassing tank (2) is provided with a swirling atomizing nozzle (3) and an air extraction port (4). The bottom of the degassing tank (2) is provided with an oil outlet (5). Inside the degassing tank (2) is a support rod (6) and a corrugated diffuser plate (7) fixed on the support rod (6). A vacuum pump (8) is connected to the suction port (4) via a vacuum line (9); The oil pump (10) is connected to the oil outlet (5) through the oil inlet pipe (11). The oil outlet (12) of the oil pump (10) is connected to the oil inlet valve (15) of the external transformer body (14) through the oil outlet pipe (13). The power input terminal (16) of the oil pump (10) is connected to the frequency converter motor (17). A pressure transmitter (18) is installed at the pressure measuring port (19) on the top of the transformer body (14); The controller (20) is connected to the vacuum pump (8), the variable frequency motor (17) and the pressure transmitter (18). The controller (20) controls the vacuum pump (8) and the variable frequency motor (17) and acquires the pressure sensing data of the pressure transmitter (18).

2. The transformer insulation vacuum oil injection device according to claim 1, characterized in that, The corrugated diffuser (7) has a multi-layer structure. The multiple corrugated diffusers (7) are fixed to the support rod (6) from top to bottom. The corrugated diffuser (7) is a continuous V-shaped corrugated structure formed by pressing a perforated (40) metal plate. The corrugated extension directions of adjacent corrugated diffusers (7) are perpendicular to each other.

3. The transformer insulation vacuum oil injection device according to claim 1, characterized in that, The swirling atomizing nozzle (3) has a spiral guide groove (21) inside, and the swirling atomizing nozzle (3) is connected to the top center of the degassing tank (2) through a flange (22).

4. The transformer insulation vacuum oil injection device according to claim 1, characterized in that, The mobile base (1) is a rectangular frame (23) welded from channel steel, and the four corners of the bottom of the mobile base (1) are respectively fixed with universal load-bearing wheels (24).

5. The transformer insulation vacuum oil injection device according to claim 1, characterized in that, The oil pump (10) is a gear pump. The variable frequency motor (17) is connected to the power input end (16) of the oil pump (10) through a plum blossom-shaped flexible coupling (26). The variable frequency motor (17) steplessly adjusts the speed of the oil pump (10).

6. The transformer insulation vacuum oil injection device according to claim 1, characterized in that, The bottom of the degassing tank (2) is funnel-shaped, and the oil outlet (5) is located at the lowest point of the funnel-shaped bottom.

7. A control method for a transformer insulation vacuum oil injection device, applicable to the transformer insulation vacuum oil injection device as described in any one of claims 1-6, characterized in that, include: S1. Control the vacuum pump (8) to perform vacuuming operation on the transformer body (14) and the degassing tank (2), and acquire the pressure sensing data of the pressure transmitter (18) in real time according to the preset sampling cycle; S2. Determine whether the pressure sensing data is less than or equal to a preset basic vacuum threshold. S3. If the pressure sensing data is greater than the basic vacuum threshold, continue the vacuuming operation. S4. If the pressure sensing data is less than or equal to the basic vacuum threshold, control the insulating oil to enter the degassing tank (2) through the swirling atomizing nozzle (3), the insulating oil is degassed by the corrugated diffuser (7), and control the vacuum pump (8) to discharge the precipitated gas. S5. Control the variable frequency motor (17) to drive the oil injection pump (10) to inject the degassed insulating oil into the transformer body (14), and obtain the current pressure inside the transformer body (14) in real time according to the sampling period; S6. Determine whether the current pressure is greater than or equal to the preset bubble-over-pressure; S7. If the current pressure is less than the critical pressure for bubble turning, maintain the rotational speed of the variable frequency motor (17); S8. If the current pressure is greater than or equal to the critical pressure for bubbling, calculate the total speed reduction correction value, and reduce the speed of the variable frequency motor (17) according to the total speed reduction correction value to reduce the oil injection flow rate.

8. The control method according to claim 7, characterized in that, The total rate reduction correction value is determined based on the degree of deviation between the current pressure and the preset critical pressure for bubble formation, as well as the dynamic characteristics of pressure changes.

9. The control method according to claim 7, characterized by, After reducing the speed of the variable frequency motor (17), the process includes: acquiring the subsequent pressure sensing data inside the transformer body (14) in real time; and determining whether the subsequent pressure sensing data is less than the preset safe recovery pressure. If the subsequent pressure sensing data is greater than or equal to the safety recovery pressure, maintain the speed of the variable frequency motor (17); if the subsequent pressure sensing data is less than the safety recovery pressure, gradually increase the speed of the variable frequency motor (17) by a fixed step size; repeat the process of acquiring pressure sensing data and speed adjustment until the insulating oil fills the transformer body (14).

10. The control method according to claim 7, characterized by, The process of the insulating oil being degassed by the corrugated diffuser (7) includes: the insulating oil being broken into fine oil droplets under the action of centrifugal force; The tiny oil droplets fall onto the corrugated diffuser plate (7) located above under the action of gravity, and spread along the V-shaped corrugated surface to form an oil film; the oil film is broken by a second fall at the punch (40) opened on the corrugated diffuser plate (7), and changes the flow direction on the corrugated diffuser plate (7) located below to spread again.

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