Precision pressurizing device and method for distribution transformer oil tank cracking test

Abstract

The present invention discloses a precise pressurization device for a distribution transformer oil tank cracking test. This device, which belongs to the field of power equipment testing, addresses the difficulty and inaccuracy of pressurization for distribution transformer oil tank cracking tests in the prior art. The technical solution to this problem includes a distribution transformer under test, a pressure monitoring module, a potential energy storage unit, and an oil storage tank. The oil storage tank and the oil tank of the distribution transformer under test are connected via a parallel high-flow oil circuit and a low-flow oil circuit. The potential energy storage unit uses compressed air to store energy and releases hydraulic potential energy in a gradient pattern to the oil tank of the distribution transformer under test via the low-flow oil circuit. The pressure monitoring module is used to monitor the pressure within the oil tank of the distribution transformer under test. When the pressure within the oil tank of the distribution transformer under test exceeds a threshold, the low-flow oil circuit automatically supplies oil to the oil tank of the distribution transformer under test to replenish the threshold. The present invention simplifies and improves the accuracy of pressurization for distribution transformer oil tank cracking tests. The present invention also discloses a precise pressurization method for a distribution transformer oil tank cracking test.

Description

Technical Field

[0001] The present invention relates to the field of power equipment detection, and in particular to a precise pressurizing device and method for a distribution transformer oil tank cracking test. Background Art

[0002] The distribution transformer oil tank serves as the last physical barrier against transformer short-circuit arcing incidents. Its mechanical strength directly impacts the power system's ability to suppress faults. This structural component effectively restrains the transient expansion of high-temperature oil vapor, preventing cascading accidents and playing a key role in protecting residents' lives and property.

[0003] The current GB / T6451 standard lists the fuel tank cracking test as a special test item, and clearly stipulates that the sample samples must maintain a hydraulic load of 103kPa for 10 minutes without cracking. The test results intuitively reflect the safety margin of the fuel tank structure.

[0004] However, the direct-pressure pneumatic loading system currently widely used in the industry faces significant technical bottlenecks. First, insufficient pressure control accuracy causes waveform oscillations exceeding ±15%, failing to meet the steady-state pressure maintenance requirements stipulated by the standard. Second, the open oil circuit design presents a risk of aerosol contamination, increasing the cost of oil purification and treatment by over 30% after testing. Third, the lack of a buffer mechanism during sudden pressure relief can result in peak impact loads reaching 2.5 times the rated pressure. This is particularly true when inspecting the integrity of fuel tank welds. Traditional methods are constrained by the incompressible nature of the oil medium. When the residual air volume in the system falls below 1.5%, the injection of a very small amount of oil will trigger a sudden pressure step, making precise pressure control at the 103kPa critical point a common problem that needs to be urgently addressed within the industry. Summary of the Invention

[0005] The purpose of the present invention is to provide a precise pressurizing device for the oil tank cracking test of a distribution transformer, which solves the problem of difficulty and inaccuracy in pressurizing the oil tank cracking test of the distribution transformer in the prior art, making the pressurizing of the oil tank cracking test of the distribution transformer simpler and more accurate.

[0006] In order to achieve the above-mentioned objectives, the present invention adopts the following technical solution: a precise pressurizing device for a distribution transformer oil tank cracking test, comprising a tested distribution transformer, a pressure monitoring module, a potential energy pressure storage unit and an oil storage tank. The oil storage tank and the oil tank of the tested distribution transformer are connected via a large-flow oil circuit and a small-flow oil circuit in parallel. The potential energy pressure storage unit is located between the small-flow oil circuit and the oil storage tank. The potential energy pressure storage unit uses compressed air to store energy and releases hydraulic potential energy in a gradient manner to the oil tank of the tested distribution transformer through the small-flow oil circuit. The pressure monitoring module is used to monitor the pressure in the oil tank of the tested distribution transformer. When the pressure in the oil tank of the tested distribution transformer exceeds a threshold value, the small-flow oil circuit automatically supplies oil to the oil tank of the tested distribution transformer to supplement the threshold value.

[0007] After adopting the above technical solution, the present invention has the following advantages: First, the large-flow oil circuit can quickly inject hydraulic oil into the oil tank of the tested distribution transformer at the beginning of the test, and quickly increase the pressure to a range close to the target value, thereby significantly shortening the test preparation time and improving work efficiency. The small-flow oil circuit takes over the work when it is close to the target pressure, and achieves more accurate pressurization by more fine-tuning the oil volume. This dual-oil circuit design takes into account both efficiency and precision, which not only meets the needs of rapid pressure increase and avoids the impact of excessive waveform oscillation, but also ensures the accuracy of the final pressure value as much as possible, thereby meeting the requirements of GB / T6451 standard for maintaining steady-state pressure, and enables precise pressure stabilization control of the 103kPa critical point. Secondly, by using a potential energy storage unit and a small-flow oil circuit, compressed air energy storage is used to form a relatively stable potential energy reserve, and the gradient release of hydraulic potential energy is achieved through the Pascal principle. Compared with the traditional direct-pressure pneumatic loading system, the pressure injected into the oil tank of the tested distribution transformer can be more accurately controlled, and the waveform oscillation amplitude can be minimized as much as possible. The pressure monitoring module is set up. When the pressure monitoring module detects that the pressure in the oil tank of the tested distribution transformer exceeds the set threshold, the system can automatically replenish the oil through the small flow oil circuit to replenish the threshold, further enabling precise pressure stabilization control of the 103kPa critical point. Through the synergistic effect of potential energy pressure storage and multi-stage buffering, the 103kPa test pressure can be more accurately maintained while avoiding oil circuit contamination, thus meeting the pressure stabilization accuracy of the tank cracking test required by the GB / T6451 standard as much as possible.

[0008] Furthermore, the buffer airbag is located between the large-flow oil circuit and the oil tank of the tested distribution transformer, and the buffer airbag is located between the small-flow oil circuit and the oil tank of the tested distribution transformer.

[0009] The aforementioned technical solution uses a cushioning airbag to absorb pressure fluctuations in the oil system. When supplying oil to the transformer tank through high- or low-flow oil circuits, transient pressure spikes or fluctuations may occur. These fluctuations can damage the equipment or affect test accuracy. The cushioning airbag effectively absorbs these pressure fluctuations, protecting the equipment and maintaining system stability.

[0010] Furthermore, an oil injection pump is provided on the oil circuit between the oil storage tank and the tested distribution transformer, and the oil injection pump is located between the oil storage tank and the potential energy pressure storage unit.

[0011] By adopting the above-mentioned technical solution, the oil injection pump can provide a stronger and more stable oil delivery capacity, ensuring that the oil can be quickly and stably transported from the oil storage tank to the oil tank of the tested distribution transformer. By placing the oil injection pump between the oil storage tank and the potential energy storage unit, the oil can reach a more ideal flow rate and flow state before entering the potential energy storage unit. This helps the potential energy storage unit to store energy more efficiently and release hydraulic potential energy to the oil tank of the tested distribution transformer in a more precise manner.

[0012] Furthermore, an oil filling switch is provided on the downstream oil circuit of the oil filling pump, and the oil filling switch is located between the oil filling pump and the potential energy pressure storage unit.

[0013] Using the aforementioned technical solution, the oil injection switch can precisely control the process of oil flowing from the oil injection pump to the potential energy pressure storage unit. This means that the operator can flexibly open or close the oil supply according to the specific needs of the test, thereby achieving more precise control of the oil flow in the entire system. When an abnormal situation is detected (such as excessive pressure, leakage or other emergency conditions), the oil circuit can be immediately cut off by quickly closing the oil injection switch to prevent the accident from escalating.

[0014] Furthermore, the potential energy pressure storage unit includes a potential energy airbag, and the volume ratio of the potential energy airbag to the oil storage tank is 1:3.

[0015] Through the above technical solution, the larger volume of the oil storage tank can store sufficient oil, providing a continuous and stable oil source for the potential energy airbag and the oil tank of the tested distribution transformer. When energy storage is needed, the potential energy airbag can quickly obtain an appropriate amount of oil from the oil storage tank and use compressed air to compress the oil to store energy. By setting a reasonable volume ratio, it can ensure that energy is effectively absorbed and released during the test, which not only meets the needs of rapid response but also ensures the stability of the system. If the volume ratio is less than 1:3, during the pressure regulation process, due to the small amount of oil stored in the potential energy airbag, when energy needs to be released to change the pressure, it is difficult to ensure a stable oil output, and the energy release process may be discontinuous, resulting in pressure fluctuations or step changes; if the volume ratio is greater than 1:3, the volume of the potential energy airbag is too large, which will result in too much oil being drawn from the oil tank when storing the same amount of energy, and the oil tank may not be replenished in time, causing the oil to be idle in the potential energy airbag, and the oil resources of the oil tank cannot be efficiently utilized, reducing the overall energy storage efficiency. When releasing energy, due to the large amount of internal oil, the pressure change response speed is slow, and the overly large potential energy airbag will occupy a large amount of space, which increases the overall volume of the equipment.

[0016] Furthermore, a large flow switch and a small flow switch are provided on the large flow oil circuit and the small flow oil circuit respectively.

[0017] The above technical solution allows the operator to independently control the opening and closing of the two oil circuits based on actual needs. This means that when rapid filling is required, the high-flow circuit can be used and quickly adjusted using the high-flow switch; while when making fine adjustments or maintaining steady-state pressure, the low-flow switch can precisely control the oil supply. In an emergency, the high-flow switch or the low-flow switch can quickly shut off either oil circuit, minimizing pressure loss caused by misoperation or other unexpected situations.

[0018] Furthermore, the oil storage tank is provided with a visual window which is helpful for observing the changes in the oil level.

[0019] Through the above technical solution, the visual window allows the operator to intuitively see the changes in the oil level in the oil tank. The operator can promptly detect oil level abnormalities (such as low oil level may cause idling damage of the oil filling pump, and high oil level may cause overflow), and thus take measures to prevent potential safety hazards.

[0020] Furthermore, an oil return line is provided between the oil tank of the tested distribution transformer and the oil storage tank. The oil return line is provided with an oil extraction switch and an oil extraction pump. The oil storage tank is provided with an oil storage bin and a multi-stage filter. The oil storage bin is connected to the large-flow oil circuit and the small-flow oil circuit. The oil in the oil return line flows through the multi-stage filter and then enters the oil storage bin.

[0021] Through the above technical solution, the setting of the return oil circuit allows the oil flowing out of the oil tank of the tested distribution transformer after the test or during the test to return to the oil storage tank, thereby avoiding oil waste and improving oil utilization. The oil storage tank is provided with an oil storage bin and a multi-stage filter is provided in the middle. When the return oil enters through the return oil circuit, it is filtered by the multi-stage filter, which can effectively remove impurities, particles and other pollutants in the oil, making the oil entering the oil storage bin purer, thereby realizing the circulation purification and reuse of the test oil.

[0022] Furthermore, the oil return line is connected to the oil tank of the tested distribution transformer through a buffer airbag.

[0023] Through this technical solution, the airbag effectively absorbs the impact and vibration generated during the oil return process. This prevents pressure fluctuations caused by sudden oil backflow. The airbag also regulates the return oil flow rate to a certain extent. When the return oil flow rate is high, the airbag is compressed, storing some oil. When the return oil flow rate is low, the airbag gradually expands, releasing the stored oil, thus stabilizing the return oil flow rate and improving the stability and accuracy of the entire test process.

[0024] Another object of the present invention is to provide a precise pressurization method for a distribution transformer oil tank cracking test, using the precise pressurization device for a distribution transformer oil tank cracking test described in any of the above technical solutions, wherein the potential energy pressure storage unit is provided with a pressure relief valve. The precise pressurization method for a distribution transformer oil tank cracking test comprises an initial oil filling stage: closing the low-flow oil circuit and opening the high-flow oil circuit, using a high-flow oil delivery mode of 300 L / min or more, and filling the oil tank of the tested distribution transformer to 95% of its volume. During the oil filling process, the cushioning airbag absorbs the impact and vibration of the oil in real time;

[0025] Pressure pre-increase stage: close the high-flow oil circuit, open the low-flow oil circuit, and inject oil into the oil tank of the tested distribution transformer at an increment of 5-10mL / s. When the pressure value displayed by the pressure monitoring module exceeds the normal pressure baseline, indicating that the system has entered the pressure sensitive area, the low-flow oil circuit is closed;

[0026] Potential energy pressure accumulation stage: start the potential energy pressure accumulation unit, inject oil into the potential energy pressure accumulation unit, and raise the internal pressure of the potential energy pressure accumulation unit to 0.2MPa, then stop injecting oil;

[0027] Precise pressure stabilization stage: Open the small flow oil circuit, and the hydraulic potential energy stored in the potential energy accumulator unit is released to the oil tank of the tested distribution transformer through the small flow oil circuit. When the pressure value displayed by the pressure monitoring module approaches 103kPa, the flow of the small flow oil circuit is adjusted. When the pressure value displayed by the pressure monitoring module is stable within the range of 103kPa±0.8kPa, the next stage is entered;

[0028] Pressure holding test phase: Maintain a test pressure of 103kPa for 10 minutes. During this period, the pressure monitoring module displays the pressure value and collects pressure data every 5 seconds. If the sudden pressure fluctuation exceeds the threshold (±1.5kPa), the small flow oil circuit automatically compensates with a fine adjustment of 0.5-2mL of oil volume;

[0029] Potential energy release and oil recovery stage: turn on the oil extraction switch and start the oil extraction pump, and the potential energy pressure accumulation unit releases pressure through the pressure relief valve.

[0030] Through the above technical solution, by gradually increasing the pressure in the oil tank in stages, from rapid filling with a large flow rate to fine adjustment with a small flow rate, it is possible to ensure precise control of the pressure throughout the entire process. The initial oil filling stage adopts a large flow oil delivery mode, which can quickly fill the oil tank of the tested distribution transformer to 95% of the volume, greatly improving the test preparation efficiency and saving time costs. At the same time, the buffer airbag absorbs the impact vibration of the oil in real time, protecting the oil tank and the oil circuit system from the impact force generated by large flow oil filling, ensuring equipment safety; in the pressure pre-rise stage, a smaller oil increment is used. Injection can accurately control the pressure rising process, timely detect the system entering the pressure sensitive area, avoid the pressure rising too fast which may cause test error or equipment damage, and lay the foundation for the subsequent precise pressure stabilization; in the potential energy storage stage, the compressed air energy storage is used to form a relatively stable potential energy reserve, and the internal pressure of the potential energy storage unit is increased to 0.2MPa, providing a stable source of hydraulic potential energy for the precise pressure stabilization stage, ensuring the stability and controllability of the pressure release process; in the precise pressure stabilization stage, the gradient release of hydraulic potential energy is realized through the Pascal principle, and the hydraulic potential energy in the potential energy storage unit is released through the small flow oil circuit. The pressure monitoring module is used to adjust the flow rate of the small flow oil circuit according to the feedback from the pressure monitoring module, so that the pressure can be accurately stabilized within the range of 103kPa±0.8kPa, meeting the strict requirements of the test on pressure accuracy and improving the accuracy and reliability of the test results. The buffer airbag and the potential energy pressure storage unit form a two-stage buffer to dynamically balance the pressure fluctuation caused by the change of oil volume, and further improve the pressure shock attenuation rate. The pressure holding test stage maintains the test pressure of 103kPa for 10 minutes, during which the pressure data is collected every 5 seconds, and the sudden pressure fluctuation can be timely responded to. Fine-tuning compensation ensures the stability of pressure during the test, making precise pressure stabilization control of the 103kPa critical point meet the requirements of GB / T6451 standard, effectively simulating the pressure conditions in actual operation, which is conducive to accurately detecting the cracking of the oil tank. Finally, in the potential energy release and oil recovery stage, the oil extraction switch is turned on and the oil extraction pump is started. At the same time, the potential energy pressure storage unit releases pressure through the pressure relief valve, realizing the safe recovery of oil and the steady drop of system pressure, avoiding the safety hazards and oil waste caused by sudden pressure release, and improving the oil reuse rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be further described below in conjunction with the accompanying drawings:

[0032] Figure 1 Schematic diagram of a precise pressurizing device for a distribution transformer oil tank cracking test according to a first embodiment of the present invention;

[0033] Figure 2 This is a detailed schematic diagram of a precise pressurizing device for a distribution transformer oil tank cracking test according to a first embodiment of the present invention;

[0034] Figure 3 This is a schematic structural diagram of a precise pressurizing device for a distribution transformer oil tank cracking test according to a first embodiment of the present invention;

[0035] Figure 4 A cross-sectional view of a precise pressurizing device for a distribution transformer oil tank cracking test according to a first embodiment of the present invention;

[0036] Figure 5 A cross-sectional view of the precise pressurizing device for oil tank cracking test of a distribution transformer according to the first embodiment of the present invention from another perspective;

[0037] Figure 6 A cross-sectional view from another perspective of the precise pressurizing device for oil tank cracking test of a distribution transformer according to the first embodiment of the present invention;

[0038] Figure 7 sectional views of the precise pressurizing device for oil tank cracking test of a distribution transformer according to the first embodiment of the present invention from other viewing angles;

[0039] In the figure, 10, the tested distribution transformer; 11, the oil tank; 12, the liquid level transmitter;

[0040] 20. Pressure monitoring module;

[0041] 30. Potential energy pressure accumulator unit; 31. Potential energy airbag; 32. Pressure controller;

[0042] 40. Oil storage tank; 41. Viewing window; 42. Oil storage tank; 43. Filter; 44. Liquid temperature gauge; 45. Air filter; 46. Manual ball valve;

[0043] 50. High-flow oil circuit; 51. Low-flow oil circuit; 52. Oil injection pump; 521. Motor; 522. Vane pump; 523. Check valve; 524. Pressure gauge; 525. Plate-type ball valve; 526. Relief valve; 53. Oil injection switch; 54. High-flow switch; 55. Low-flow switch; 551. Solenoid ball valve; 552. Servo control valve; 56. Shock absorber throat; 57. Butterfly valve;

[0044] 60. Cushioning airbag;

[0045] 70. Oil return line; 71. Oil extraction switch; 72. Oil extraction pump; 73. Oil return filter. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0047] The terms "first," "second," "third," "fourth," and so forth (if any) in the description and claims of the present invention and in the accompanying drawings are used to distinguish similar items and are not necessarily used to describe a particular order or sequential sequence. It should be understood that the terms used in this manner are interchangeable where appropriate, such that the embodiments of the present invention described herein can be practiced in sequences other than those illustrated or described herein.

[0048] It should be understood that in various embodiments of the present invention, the size of the serial numbers of the processes does not mean the order of execution. The execution order of the processes should be determined by their functions and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0049] It should be understood that in the present invention, "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0050] It should be understood that in the present invention, "plurality" refers to two or more. "And / or" is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, X and / or Y can represent three situations: X exists alone, X and Y exist at the same time, and Y exists alone. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "Including X, Y and Z" and "Including X, Y, Z" means that X, Y, and Z are all included. "Including X, Y or Z" means that one of X, Y, and Z is included. "Including X, Y and / or Z" means that any one, any two, or any three of X, Y, and Z are included.

[0051] The following specific embodiments are used to describe the technical solution of the present invention in detail. The following specific embodiments can be combined or replaced with each other according to actual conditions, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0052] Example 1:

[0053] like Figures 1 to 7As shown, the present invention provides a precise pressurizing device for a distribution transformer oil tank cracking test, comprising a tested distribution transformer 10, a pressure monitoring module 20, a potential energy pressure storage unit 30, and an oil storage tank 40. The oil storage tank 40 and the oil tank 11 of the tested distribution transformer 10 are connected via a large-flow oil circuit 50 and a small-flow oil circuit 51 connected in parallel. The potential energy pressure storage unit 30 is located between the small-flow oil circuit 51 and the oil storage tank 40. The potential energy pressure storage unit 30 uses compressed air to store energy and releases hydraulic potential energy in a gradient manner to the oil tank 11 of the tested distribution transformer 10 through the small-flow oil circuit 51. The pressure monitoring module 20 is used to monitor the pressure in the oil tank 11 of the tested distribution transformer 10. When the pressure in the oil tank 11 of the tested distribution transformer 10 exceeds a threshold value, the small-flow oil circuit 51 automatically supplies oil to the oil tank 11 of the tested distribution transformer 10 to replenish the threshold value.

[0054] First, the large-flow oil circuit 50 can quickly inject hydraulic oil into the oil tank 11 of the tested distribution transformer 10 at the beginning of the test, and quickly increase the pressure to a range close to the target value, thereby significantly shortening the test preparation time and improving work efficiency. The small-flow oil circuit 51 takes over the work when it approaches the target pressure, and achieves more accurate pressurization by more finely adjusting the oil volume. This dual-oil circuit design takes into account both efficiency and precision, meeting the needs of rapid pressure increase, avoiding the impact of excessive waveform oscillation, and ensuring the accuracy of the final pressure value as much as possible, thereby meeting the requirements of the GB / T6451 standard for maintaining steady-state pressure, and achieving precise pressure stabilization control of the 103kPa critical point. Secondly, by using the potential energy accumulator unit 30 and the small-flow oil circuit 51, compressed air energy storage is used to form a relatively stable potential energy reserve, and the gradient release of hydraulic potential energy is achieved through the Pascal principle. Compared with the traditional direct-pressure pneumatic loading system, the pressure injected into the oil tank 11 of the tested distribution transformer 10 can be more accurately controlled, the amplitude of waveform oscillation can be minimized as much as possible, thereby more accurately meeting the GB / T6451 standard. 451 standard for maintaining steady-state pressure. Then, both the large-flow oil circuit 50 and the small-flow oil circuit 51 adopt a closed oil circuit design, which helps prevent external pollutants from entering the system and reduces the risk of aerosol contamination. A buffer air bag 60 is set between the oil storage tank 40 and the oil tank 11 of the tested distribution transformer 10. The buffer air bag 60 can also form a dynamic pressure buffer mechanism, effectively suppressing oil circuit pulsation, playing a buffering role in the sudden pressure relief process, effectively absorbing impact loads, and avoiding excessive pressure peaks caused by sudden pressure relief. Finally, a pressure monitoring module 20 is set. When the pressure monitoring module 20 detects that the pressure in the oil tank 11 of the tested distribution transformer 10 exceeds the set threshold, the system can automatically replenish oil through the small-flow oil circuit 51 to replenish the threshold, further enabling precise pressure stabilization control of the 103 kPa critical point. Therefore, through the synergistic effect of potential energy pressure storage and multi-stage buffering, while avoiding oil circuit contamination, the 103 kPa test pressure can be more accurately maintained, and the pressure stabilization accuracy of the oil tank 11 cracking test required by the GB / T6451 standard can be met as much as possible.

[0055] It should be noted that the pressure monitoring module 20 may be a pressure gauge 524 , which provides real-time feedback on the oil tank 11 of the tested distribution transformer 10 .

[0056] When oil is supplied to the transformer tank 11 through the high-flow or low-flow oil circuit 51, transient pressure peaks or fluctuations may occur. These fluctuations may damage the equipment or affect test accuracy. The buffer airbag 60 is located between the high-flow oil circuit 50 and the tank 11 of the tested distribution transformer 10, and between the low-flow oil circuit 51 and the tank 11 of the tested distribution transformer 10. The buffer airbag 60 can effectively absorb these pressure fluctuations, thereby protecting the equipment and maintaining system stability.

[0057] Since the oil path between the oil storage tank 40 and the oil tank 11 of the tested distribution transformer 10 is long, the oil delivery rate is attenuated. For this reason, in the present application, an oil injection pump 52 is further provided on the oil path between the oil storage tank 40 and the tested distribution transformer 10. The oil injection pump 52 is located between the oil storage tank 40 and the potential energy pressure storage unit 30. The oil injection pump 52 can provide a stronger and more stable oil delivery capacity, ensuring that the oil can be quickly and stably delivered from the oil storage tank 40 to the oil tank 11 of the tested distribution transformer 10. By placing the oil injection pump 52 between the oil storage tank 40 and the potential energy pressure storage unit 30, the oil can reach a relatively ideal flow rate and flow state before entering the potential energy pressure storage unit 30, which helps the potential energy pressure storage unit 30 to store energy more efficiently and release hydraulic potential energy to the oil tank 11 of the tested distribution transformer 10 in a more precise manner.

[0058] In order to facilitate the control of the oil output from the oil storage tank 40, in the present application, an oil filling switch 53 is provided on the downstream oil circuit of the oil filling pump 52, and the oil filling switch 53 is located between the oil filling pump 52 and the potential energy pressure accumulator unit 30. The oil filling switch 53 can accurately control the process of oil flowing from the oil filling pump 52 to the potential energy pressure accumulator unit 30, which means that the operator can flexibly open or close the oil supply according to the specific needs of the test, thereby achieving more precise control of the oil flow in the entire system. When an abnormal situation is detected (such as excessive pressure, leakage or other emergency conditions), the oil circuit can be immediately cut off by quickly closing the oil filling switch 53 to prevent the accident from escalating.

[0059] Furthermore, high-flow oil circuit 50 and low-flow oil circuit 51 are equipped with high-flow switches 54 and low-flow switches 55, respectively. These switches allow the operator to independently open and close the two circuits according to actual needs. This means that when rapid filling is required, high-flow oil circuit 50 can be used, and rapid adjustments can be made via high-flow switch 54. For fine adjustments or maintaining steady-state pressure, the low-flow switch 55 can be used to precisely control the oil supply. In an emergency, high-flow switch 54 or low-flow switch 55 can quickly shut off either circuit, minimizing pressure runaway caused by misoperation or other unexpected circumstances.

[0060] It should be noted that the adjustment accuracy of the opening of the small flow switch 55 is ±0.1 mL (100 μL) / min, which can more accurately adjust the oil delivery amount.

[0061] The potential energy accumulator unit 30 includes a potential energy bladder 31, and the volume ratio of the potential energy bladder 31 to the oil tank 40 is 1:3. The large capacity of the oil tank 40 allows for ample oil storage, providing a continuous and stable oil source for the potential energy bladder 31 and the oil tank 11 of the tested distribution transformer 10. When energy storage is needed, the potential energy bladder 31 can quickly obtain an appropriate amount of oil from the oil tank 40 and compress the oil using compressed air to store energy. By setting a reasonable volume ratio, the effective absorption and release of energy during the test can be ensured, meeting the requirements for rapid response while ensuring system stability and ensuring linear controllability of subsequent pressure release. If the volume ratio is less than 1:3, during the pressure regulation process, due to the small amount of oil stored in the potential energy airbag 31, when energy needs to be released to change the pressure, it is difficult to ensure a stable oil output, and the energy release process may also be discontinuous, resulting in pressure fluctuations or step changes; if the volume ratio is greater than 1:3, the volume of the potential energy airbag 31 is too large, which will result in too much oil being drawn from the oil tank 40 when storing the same amount of energy, and the oil tank 40 may not be replenished in time, causing the oil to be idle in the potential energy airbag 31, and the oil resources of the oil tank 40 cannot be efficiently utilized, thereby reducing the overall energy storage efficiency. When releasing energy, due to the large amount of internal oil, the pressure change response speed is slow, and the overly large potential energy airbag 31 will occupy a large amount of space, which increases the overall volume of the equipment.

[0062] Since the present application involves multiple oil supplies, in order to ensure sufficient oil supply, a visual window 41 is provided on the oil storage tank 40 to facilitate observation of oil level changes. The visual window 41 allows the operator to intuitively see the oil level changes in the oil storage tank 40. The operator can promptly detect oil level abnormalities (for example, a too low oil level may cause idling damage to the oil filling pump 52, and a too high oil level may cause overflow, etc.), and thus take measures to prevent potential safety hazards.

[0063] In addition, in order to improve the reuse rate of oil, in this application, a return oil circuit 70 is further provided between the oil tank 11 of the tested distribution transformer 10 and the oil storage tank 40. The return oil circuit 70 is provided with an oil extraction switch 71 and an oil extraction pump 72. The oil storage tank 40 is provided with an oil storage bin 42 and a multi-stage filter 43. The oil storage bin 42 is connected to the large-flow oil circuit 50 and the small-flow oil circuit 51. The oil in the return oil circuit 70 flows through the multi-stage filter 43 and then enters the oil storage bin 42. The oil flowing out of the oil tank 11 of the tested distribution transformer 10 after or during the test can be returned to the oil storage tank 40, thereby avoiding waste of oil and improving the utilization rate of oil. The oil storage tank 40 is provided with an oil storage bin 42 and a multi-stage filter 43. When the return oil enters through the return oil line 70, it is filtered by the multi-stage filter 43, which can effectively remove impurities, particles and other pollutants in the oil, making the oil entering the oil storage bin 42 purer, thereby realizing the circulation purification and reuse of the test oil.

[0064] To ensure more stable oil return, the oil return line 70 is connected to the oil tank 11 of the distribution transformer 10 under test via a buffer airbag 60. The buffer airbag 60 effectively absorbs the impact and vibration generated during the oil return process, preventing pressure fluctuations caused by sudden oil backflow. The buffer airbag 60 also regulates the return oil flow rate to a certain extent. When the return oil flow rate is high, the buffer airbag 60 is compressed, storing some oil. When the return oil flow rate is low, the buffer airbag 60 gradually expands, releasing the stored oil, thus stabilizing the return oil flow rate and helping to improve the stability and accuracy of the entire test process.

[0065] It should be noted that in the present application, only one of the large flow oil circuit 50, the small flow oil circuit 51 and the return oil circuit 70 is opened at the same time during testing. In the present application, the large flow oil circuit 50, the small flow oil circuit 51 and the return oil circuit 70 share a buffer air bag 60, which can reduce the number of components and simplify the pipeline layout.

[0066] It should be noted that the cushioning airbag 60 absorbs impact energy through the rapid deformation of the silicon-based composite material, and the deformation range of the elastic deformation of the cushioning airbag 60 is 0-15 mm.

[0067] It should be noted that during the oil filling phase, rapid oil filling can be performed first through the high-flow oil circuit 50. At this time, the oil filling pump 52 maintains high speed operation to complete the filling of most of the oil in the oil tank 11 of the tested distribution transformer 10, specifically 80%, 90%, or 95% of the oil tank 11 of the tested distribution transformer 10. Then, fine-tuning the oil filling is performed through the low-flow oil circuit 51. At this time, the oil filling pump 52 maintains low speed operation, injecting oil into the oil tank 11 at increments of 5-10 mL / s.

[0068] It should be noted that during the test, a test pressure of 103 kPa must be maintained for 10 minutes, during which pressure gauge 524 collects pressure data every 5 seconds. If a sudden pressure fluctuation exceeds a threshold (±1.5 kPa), the cushioning airbag 60 absorbs the impact energy through rapid deformation of the silicon-based composite material, while the low-flow switch 55 automatically compensates by fine-tuning the oil volume by 0.5-2 mL.

[0069] To further enhance test safety, the oil circuit inserted into the oil tank 40 is equipped with a shock absorber 56 and a butterfly valve 57 to absorb vibration and noise in the oil circuit. The oil tank 40 is also equipped with a liquid thermometer 44 and an air filter 45 to monitor the liquid temperature in the oil tank 40 in real time and filter the air surrounding the oil tank 40. A parallel branch circuit is also provided between the oil tank 40 and the potential energy airbag 31. Each branch circuit is equipped with a motor 521, a vane pump 522, a one-way valve 523, a pressure gauge 524, a plate-type ball valve 525, and a relief valve 526 to control the oil output from the oil tank 40. In addition to the potential energy airbag 31, the potential energy accumulator unit 30 is also equipped with a plate-type ball valve 525, a pressure gauge 524, and a pressure controller 32 to control the pressure of the potential energy accumulator unit 30. The high-flow switch 54 and low-flow switch 55 respectively include a plate-type ball valve 525 and a solenoid-operated ball valve 551, enabling dual control. The low-flow switch 55 also includes a servo-controlled valve 552 for more precise flow adjustment. The oil return branch is also equipped with a return oil filter 73, a plate-type ball valve 525, a check valve 523, and other components to facilitate oil recovery. A manual ball valve 46 is also installed at the bottom of the oil tank 40 for manual oil draining. The potential energy airbag 31 is also connected to a manual ball valve 46 for manual pressure relief. The oil tank 11 of the tested distribution transformer 10 is also equipped with a liquid level transmitter 12 for measuring the liquid level.

[0070] It is understood that in other embodiments, the high-flow oil circuit, low-flow oil circuit, and return oil circuit may each be equipped with a separate cushioning airbag. Each cushioning airbag can be specifically designed based on the characteristics of each oil circuit. For example, the cushioning airbag in the high-flow oil circuit can be larger to accommodate higher flow rates and greater impact forces, while the cushioning airbag in the low-flow oil circuit can focus on fine-tuning and absorbing minor pressure fluctuations, and can also be designed to be wear-resistant due to the high concentration of impurities in the return oil circuit.

[0071] It is understandable that in other embodiments, the oil storage tank may also be provided with a liquid level measuring instrument to intuitively and accurately display the liquid level of the oil storage tank.

[0072] Example 2:

[0073] This embodiment provides a precise pressurization method for a distribution transformer oil tank cracking test. A precise pressurization device for a distribution transformer oil tank cracking test employing a technical solution of any of the above embodiments is employed. The potential energy pressure storage unit is provided with a pressure relief valve. The precise pressurization method for a distribution transformer oil tank cracking test comprises an initial oil filling phase: closing a low-flow oil circuit and opening a high-flow oil circuit, using a high-flow oil delivery mode of 300 L / min or more, and filling the oil tank of the tested distribution transformer to 95% of its volume. During the oil filling process, a buffer airbag absorbs oil impact and vibration in real time.

[0074] Pressure pre-increase stage: close the high-flow oil circuit, open the low-flow oil circuit, and inject oil into the oil tank of the tested distribution transformer at an increment of 5-10mL / s. When the pressure value displayed by the pressure monitoring module exceeds the normal pressure baseline, indicating that the system has entered the pressure sensitive area, the low-flow oil circuit is closed;

[0075] Potential energy pressure accumulation stage: start the potential energy pressure accumulation unit, inject oil into the potential energy pressure accumulation unit, and raise the internal pressure of the potential energy pressure accumulation unit to 0.2MPa, then stop injecting oil;

[0076] Precise pressure stabilization stage: Open the small flow oil circuit, and the hydraulic potential energy stored in the potential energy accumulator unit is released to the oil tank of the tested distribution transformer through the small flow oil circuit. When the pressure value displayed by the pressure monitoring module approaches 103kPa, the flow of the small flow oil circuit is adjusted. When the pressure value displayed by the pressure monitoring module is stable within the range of 103kPa±0.8kPa, the next stage is entered;

[0077] Pressure holding test phase: Maintain a test pressure of 103kPa for 10 minutes. During this period, the pressure monitoring module displays the pressure value and collects pressure data every 5 seconds. If the sudden pressure fluctuation exceeds the threshold (±1.5kPa), the small flow oil circuit automatically compensates with a fine adjustment of 0.5-2mL of oil volume;

[0078] Potential energy release and oil recovery stage: turn on the oil extraction switch and start the oil extraction pump, and the potential energy pressure accumulation unit releases pressure through the pressure relief valve.

[0079] Through the above technical solution, by gradually increasing the pressure in the oil tank in stages, from rapid filling with a large flow rate to fine adjustment with a small flow rate, it is possible to ensure precise control of the pressure throughout the entire process. The initial oil filling stage adopts a large flow oil delivery mode, which can quickly fill the oil tank of the tested distribution transformer to 95% of the volume, greatly improving the test preparation efficiency and saving time costs. At the same time, the buffer airbag absorbs the impact and vibration of the oil in real time, protecting the oil tank and the oil circuit system from the impact force generated by large flow oil filling, ensuring equipment safety; the pressure pre-increase stage is injected with smaller oil increments, which can Precisely control the pressure rising process, timely detect the system entering the pressure sensitive area, avoid the test error or equipment damage caused by excessive pressure rise, and lay the foundation for subsequent precise pressure stabilization; in the potential energy storage stage, compressed air energy storage is used to form a relatively stable potential energy reserve, and the internal pressure of the potential energy storage unit is increased to 0.2MPa, providing a stable source of hydraulic potential energy for the precise pressure stabilization stage, ensuring the stability and controllability of the pressure release process; in the precise pressure stabilization stage, the gradient release of hydraulic potential energy is achieved through the Pascal principle, and the hydraulic potential energy in the potential energy storage unit is released through a small flow oil circuit and is adjusted according to the pressure monitoring. The feedback of the measuring module adjusts the flow of the small flow oil circuit, so that the pressure can be accurately stabilized within the range of 103kPa±0.8kPa, meeting the strict requirements of the test on pressure accuracy and improving the accuracy and reliability of the test results. The buffer airbag and the potential energy pressure storage unit form a two-stage buffer, dynamically balancing the pressure fluctuations caused by the change of oil volume, and further improving the pressure shock attenuation rate to more than 92%; the pressure holding test stage maintains a test pressure of 103kPa for 10 minutes, during which pressure data is collected every 5 seconds, and can respond to sudden pressure fluctuations and Fine-tuning compensation of oil volume was performed at the same time to ensure the stability of pressure during the test, so that the precise pressure stabilization control of the critical point of 103kPa met the requirements of GB / T6451 standard, effectively simulated the pressure conditions in actual operation, and was conducive to the accurate detection of oil tank cracking. Finally, in the potential energy release and oil recovery stage, the oil extraction switch was turned on and the oil extraction pump was started. At the same time, the potential energy pressure storage unit released pressure through the pressure relief valve, realizing the safe recovery of oil and the steady drop of system pressure, avoiding the safety hazards and oil waste caused by sudden pressure release, and improving the oil reuse rate.

[0080] It should be noted that during the precise pressure stabilization stage, by adjusting the opening of the small flow switch, the adjustment accuracy of the small flow switch is ±0.1mL (100μL) / min, combined with the elastic deformation of the buffer airbag, the deformation range of the buffer airbag is 0-15mm, and the pressure fluctuations caused by the change in oil volume are dynamically balanced.

[0081] It should be noted that during the pressure holding test phase, if the sudden pressure fluctuation exceeds the threshold (±1.5kPa), the cushioning airbag absorbs the impact energy through the rapid deformation of the silicon-based composite material, and at the same time the small flow switch automatically compensates for the 0.5-2mL oil volume fine-tuning.

[0082] It should be noted that during the potential energy release and oil recovery phase, the oil pump is started to rapidly pump the oil from the test distribution transformer's tank back to the oil storage tank at a flow rate of 200L / min. The oil flows through a three-stage gradient filter with filtration degrees of 100μm, 50μm, and 10μm, intercepting particles from large to small. The multi-layer filter in the oil storage tank continuously filters the circulating oil to ensure that the medium cleanliness meets the ISO440618 / 16 / 13 level requirements. The purified oil is stored in the oil storage tank's storage bin, with a recovery rate of ≥98%, breaking the technical bottleneck of oil reuse rate of 98%. The potential energy airbag slowly releases residual pressure through the pressure relief valve, and the system returns to its initial state.

[0083] In addition to the above-mentioned preferred embodiments, the present invention has other implementation modes. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection requested by the present invention.

Claims

1. The precise pressurizing device for the cracking test of the oil tank of the distribution transformer is characterized by: The utility model comprises a tested distribution transformer, a pressure monitoring module, a potential energy pressure accumulator unit and an oil storage tank. The oil storage tank and the oil tank of the tested distribution transformer are connected through a large flow oil circuit and a small flow oil circuit in parallel. The potential energy pressure accumulator unit is located between the small flow oil circuit and the oil storage tank. The potential energy pressure accumulator unit uses compressed air to store energy and releases hydraulic potential energy in a gradient manner to the oil tank of the tested distribution transformer through the small flow oil circuit. A buffer air bag is also provided on the oil circuit between the oil storage tank and the oil tank of the tested distribution transformer. The pressure monitoring module is used to monitor the pressure in the oil tank of the tested distribution transformer. When the pressure in the oil tank of the tested distribution transformer exceeds a threshold value, the small flow The oil measuring circuit automatically supplies oil to the oil tank of the tested distribution transformer to replenish the threshold value. A return oil circuit is also provided between the oil tank of the tested distribution transformer and the oil storage tank. The return oil circuit is provided with an oil extraction switch and an oil extraction pump. The return oil circuit is connected to the oil tank of the tested distribution transformer through a buffer airbag. A precise pressurization method for the cracking test of the distribution transformer oil tank is also included. The potential energy pressure storage unit is provided with a pressure relief valve. The precise pressurization method for the cracking test of the distribution transformer oil tank includes an initial oil filling stage: closing the small flow oil circuit and opening the large flow oil circuit, adopting a large flow oil delivery mode of more than 300L / min, and injecting oil into the oil tank of the tested distribution transformer to a volume of 95 % of oil volume, and the buffer airbag absorbs the oil impact and vibration in real time during the oil filling process; pressure pre-rise stage: close the large-flow oil circuit, open the small-flow oil circuit, and inject oil into the oil tank of the tested distribution transformer at an increment of 5-10mL / s. When the pressure value displayed by the pressure monitoring module breaks through the normal pressure baseline, it indicates that the system has entered the pressure sensitive area, and then close the small-flow oil circuit; potential energy storage stage: start the potential energy storage unit, inject oil into the potential energy storage unit, and increase the internal pressure of the potential energy storage unit to 0.2MPa, then stop oil filling; precise pressure stabilization stage: open the small-flow oil circuit, and the hydraulic potential energy stored in the potential energy storage unit is discharged to the tested distribution transformer through the small-flow oil circuit. The oil tank of the decompressor is released. When the pressure monitoring module displays a pressure value approaching 103kPa, the flow of the small flow oil circuit is adjusted. When the pressure monitoring module displays a pressure value that is stable within the range of 103kPa±0.8kPa, the next stage is entered; pressure holding test stage: maintain the test pressure of 103kPa for 10 minutes. During this period, the pressure monitoring module displays the pressure value and collects pressure data every 5 seconds. If the sudden pressure fluctuation exceeds the threshold of ±1.5kPa, the small flow oil circuit automatically compensates with 0.5-2mL of oil volume for fine-tuning; potential energy release and oil recovery stage: turn on the oil extraction switch and start the oil extraction pump. The potential energy pressure storage unit releases pressure through the pressure relief valve.

2. The precise pressurizing device for cracking test of distribution transformer oil tank according to claim 1 is characterized in that: The buffer airbag is located between the large-flow oil circuit and the oil tank of the tested distribution transformer, and the buffer airbag is located between the small-flow oil circuit and the oil tank of the tested distribution transformer.

3. The precise pressurizing device for cracking test of distribution transformer oil tank according to claim 1 is characterized in that: An oil injection pump is further provided on the oil circuit between the oil storage tank and the oil tank of the tested distribution transformer. The oil injection pump is located between the oil storage tank and the potential energy pressure storage unit.

4. The precise pressurizing device for cracking test of distribution transformer oil tank according to claim 3 is characterized in that: An oil filling switch is provided on the downstream oil line of the oil filling pump, and the oil filling switch is located between the oil filling pump and the potential energy pressure storage unit.

5. The precise pressurizing device for cracking test of distribution transformer oil tank according to claim 1 is characterized in that: The potential energy pressure storage unit includes a potential energy airbag, and the volume ratio of the potential energy airbag to the oil storage tank is 1:

3.

6. The precise pressurizing device for cracking test of distribution transformer oil tank according to claim 1, characterized in that: The large flow oil circuit and the small flow oil circuit are respectively provided with a large flow switch and a small flow switch.

7. The precise pressurizing device for cracking test of distribution transformer oil tank according to claim 1, characterized in that: The oil storage tank is provided with a visual window which is helpful for observing the changes in the oil level.

8. The precise pressurizing device for cracking test of distribution transformer oil tank according to claim 1, characterized in that: The oil storage tank is provided with an oil storage bin and a multi-stage filter screen. The oil storage bin is connected to a large flow oil circuit and a small flow oil circuit. The oil in the oil return circuit flows through the multi-stage filter screen and then enters the oil storage bin.

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