Accurate pressurizing device and method for cracking test of oil tank of distribution transformer

Abstract

The invention discloses an accurate pressurizing device for a cracking test of a distribution transformer oil tank, belongs to the field of power equipment detection, solves the problems of difficulty and inaccuracy in pressurizing in the cracking test of the distribution transformer oil tank in the prior art, and adopts the technical scheme that the accurate pressurizing device comprises a tested distribution transformer, a pressure monitoring module, a potential energy pressure storage unit and an oil storage tank, the oil storage tank and an oil tank of the tested distribution transformer are connected through a large-flow oil way and a small-flow oil way which are connected in parallel, the potential energy pressure storage unit stores energy through compressed air and releases hydraulic potential energy to the oil tank of the tested distribution transformer in a gradient mode through the small-flow oil way, and the pressure monitoring module is used for monitoring pressure in the oil tank of the tested distribution transformer. And when the pressure in the oil tank of the tested distribution transformer exceeds a threshold value, the small-flow oil path automatically conveys oil to the oil tank of the tested distribution transformer to supplement the threshold value. According to the invention, the pressurization for the cracking test of the distribution transformer oil tank is simpler and more accurate. The invention further discloses an accurate pressurization method for the cracking test of the distribution transformer oil tank.

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] To achieve the above object, the present invention adopts the following technical solutions: a precise pressure boosting device for the cracking test of a distribution transformer oil tank, comprising 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 through a large-flow oil circuit and a small-flow oil circuit in parallel. The potential energy storage unit is located between the small-flow oil circuit and the oil storage tank. The potential energy storage unit stores energy using compressed air and releases hydraulic potential energy to the oil tank of the distribution transformer under test in a gradient manner through the small-flow oil circuit. The pressure monitoring module is used to monitor the pressure inside the oil tank of the distribution transformer under test. When the pressure inside the oil tank of the distribution transformer under test exceeds the threshold, the small-flow oil circuit automatically supplies oil to the oil tank of the distribution transformer under test to supplement the threshold.

[0007] After adopting the above technical solutions, the present invention has the following advantages: First, the large-flow oil circuit can quickly inject hydraulic oil into the oil tank of the distribution transformer under test at the initial stage of the test, rapidly raising 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 approaching the target pressure and achieves more precise pressure boosting by more finely adjusting the oil volume. This dual-oil-circuit design takes into account both efficiency and precision, meeting the need for rapid pressure rise, avoiding the impact caused by excessive waveform oscillation, and ensuring the accuracy of the final pressure value as much as possible, thus meeting the requirements of the GB / T6451 standard for steady-state pressure maintenance and enabling precise voltage stabilization control at the 103 kPa critical point. Second, by using the potential energy storage unit and the small-flow oil circuit, a relatively stable potential energy reserve is formed by storing energy using compressed air, and the gradient release of hydraulic potential energy is achieved through Pascal's principle. Compared with the traditional direct-pressure pneumatic loading system, the pressure injected into the oil tank of the distribution transformer under test can be controlled more precisely, and the amplitude of waveform oscillation can be reduced as much as possible, thus more accurately meeting the requirements of the GB / T6451 standard for steady-state pressure maintenance. Then, both the large-flow oil circuit and the small-flow oil circuit adopt a closed oil circuit design, which helps prevent external contaminants from entering the system, reducing the risk of aerosol pollution. A buffer airbag is provided between the oil storage tank and the oil tank of the distribution transformer under test, and the buffer airbag can also form a dynamic pressure buffer mechanism, effectively suppressing oil circuit pulsation and playing a buffering role in the sudden pressure relief process, effectively absorbing the impact load and avoiding excessive pressure peaks caused by sudden pressure relief. Finally, a pressure monitoring module is set. When the pressure monitoring module monitors that the pressure inside the oil tank of the distribution transformer under test exceeds the set threshold, the system can automatically supplement the oil volume through the small-flow oil circuit to supplement the threshold, further enabling precise voltage stabilization control at the 103 kPa critical point. Thus, through the synergistic effect of potential energy storage and multi-stage buffering, while avoiding oil circuit pollution, the 103 kPa test pressure can be maintained more precisely, and the voltage stabilization accuracy of the oil tank cracking test required by the GB / T6451 standard can be met as much as possible.

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

[0009] With the foregoing technical solution, the buffer airbag can play a role in absorbing pressure fluctuations in the oil circuit system. When supplying oil to the transformer oil tank through the large-flow or small-flow oil circuit, instantaneous pressure peaks or fluctuations may occur, which may damage the equipment or affect the test accuracy. The buffer airbag can effectively absorb these pressure fluctuations, thereby protecting the equipment and maintaining the stability of the system.

[0010] Further, an oil injection pump is also provided on the oil circuit between the oil storage tank and the test distribution transformer, and the oil injection pump is located between the oil storage tank and the potential energy accumulator unit.

[0011] With the foregoing 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 delivered from the oil storage tank to the oil tank of the test distribution transformer. By placing the oil injection pump between the oil storage tank and the potential energy accumulator unit, the oil can reach a relatively ideal flow rate and flow state before entering the potential energy accumulator unit, which helps the potential energy accumulator unit store energy more efficiently and release the hydraulic potential energy to the oil tank of the test distribution transformer in a more precise manner.

[0012] Further, an oil injection switch is provided on the downstream oil circuit of the oil injection pump, and the oil injection switch is located between the oil injection pump and the potential energy accumulator unit.

[0013] With the foregoing technical solution, the oil injection switch can accurately control the process of oil flowing from the oil injection pump to the potential energy accumulator unit, which means that the operator can flexibly open or close the oil supply according to the specific requirements of the test, thereby achieving more refined control of the oil flow in the entire system. When detecting abnormal conditions (such as too high pressure, leakage or other emergency situations), the oil injection switch can be quickly closed to immediately cut off the oil circuit and prevent the accident from expanding.

[0014] Further, the potential energy accumulator 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 relatively large volume of the oil storage tank can store sufficient oil fluid, providing a continuous and stable oil source for the potential energy airbag and the oil tank of the distribution transformer under test. When energy storage is required, the potential energy airbag can quickly obtain an appropriate amount of oil fluid from the oil storage tank and use compressed air to compress and store the oil fluid energy. By setting a reasonable volume ratio, it can ensure the effective absorption and release of energy during the test, meeting both the requirements of rapid response and the stability of the system. If the volume ratio is less than 1:3, during the pressure regulation process, due to the small oil storage capacity of the potential energy airbag, when energy needs to be released to change the pressure, it is difficult to ensure a stable oil output volume, and it may also lead to a discontinuous energy release process, 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 cause too much oil fluid to be drawn from the oil storage tank when storing the same amount of energy, and the oil storage tank may not be able to replenish it in time, causing the oil fluid to be idle in the potential energy airbag, unable to efficiently utilize the oil fluid resources of the oil storage tank, reducing the overall energy storage efficiency. When releasing energy, due to the large amount of internal oil fluid, the response speed of pressure change is slow, and the overly large potential energy airbag will occupy a large amount of space, increasing the overall volume of the equipment.

[0016] Further, a large-flow oil circuit and a small-flow oil circuit are respectively provided with a large-flow switch and a small-flow switch.

[0017] Through the above technical solution, the large-flow switch and the small-flow switch allow the operator to independently control the opening and closing of the two oil circuits according to actual needs. This means that the large-flow oil circuit can be used when rapid filling is required and quickly adjusted through the large-flow switch; while for fine adjustment or maintaining a steady-state pressure, the oil fluid supply amount can be precisely controlled through the small-flow switch. In case of an emergency, either oil circuit can be quickly cut off through the large-flow switch and the small-flow switch to prevent, as much as possible, the problem of pressure out-of-control caused by misoperation or other unexpected situations.

[0018] Further, a viewing window facilitating the observation of oil level changes is provided on the oil storage tank.

[0019] Through the above technical solution, the viewing window allows the operator to directly see the oil level change situation in the oil storage tank. The operator can timely discover abnormal oil levels (such as too low an oil level may cause the injection oil pump to run idly and be damaged, and too high an oil level may cause overflow, etc.), so as to take measures to prevent potential safety hazards.

[0020] Further, an oil return circuit is also provided between the oil tank of the distribution transformer under test and the oil storage tank. The oil return circuit is provided with an oil pumping switch and an oil pump. The oil storage tank is provided with an oil storage chamber and a multi-stage filter screen. The oil storage chamber is communicated with the large-flow oil circuit and the small-flow oil circuit. The oil fluid of the oil return circuit flows through the multi-stage filter screen and then enters the oil storage chamber.

[0021] Through the above technical solution, the setting of the oil return circuit enables the oil flowing out of the tested distribution transformer tank after the test or during the test to return to the storage tank, avoiding waste of oil and improving the utilization rate of oil. The storage tank is provided with an oil storage bin and multiple-stage filters are arranged in the middle. When the oil return enters through the oil return circuit, after being filtered by the multiple-stage filters, impurities, particles and other pollutants in the oil can be effectively removed, making the oil entering the oil storage bin purer, realizing the cyclic purification and reuse of the test oil.

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

[0023] Through the above technical solution, the buffer airbag can effectively absorb the impact force and vibration generated during the oil return process. This can prevent pressure fluctuations caused by sudden oil backflow. The buffer airbag can also adjust the oil return flow rate to a certain extent. When the oil return flow rate is large, the buffer airbag will be compressed to store a part of the oil; when the oil return flow rate is small, the buffer airbag will gradually expand to release the stored oil, so that the oil return flow rate is more stable, which helps to improve the stability and accuracy of the entire test process.

[0024] Another object of the present invention is to provide a precise pressurization method for the cracking test of a distribution transformer tank. Using the precise pressurization device for the cracking test of a distribution transformer tank described in any of the above technical solutions, the potential energy storage unit is provided with a pressure relief valve. The precise pressurization method for the cracking test of a distribution transformer tank includes an initial oil injection stage: closing the small-flow oil circuit and opening the large-flow oil circuit, adopting a large-flow oil delivery mode of more than 300 L / min, injecting oil into the tank of the tested distribution transformer until 95% of the volume, and the buffer airbag absorbs the impact vibration of the oil in real time during the oil injection process;

[0025] Pressure pre-lift stage: closing the large-flow oil circuit, opening the small-flow oil circuit, injecting oil into the tank of the tested distribution transformer at an increment of 5-10 mL / s. When the pressure monitoring module shows that the pressure value breaks through the atmospheric pressure baseline, it indicates that the system enters the pressure-sensitive area, then closing the small-flow oil circuit;

[0026] Potential energy storage stage: starting the potential energy storage unit, injecting oil into the potential energy storage unit to increase the internal pressure of the potential energy storage unit to 0.2 MPa, then stopping the oil injection;

[0027] Precise pressure stabilization stage: opening the small-flow oil circuit, the hydraulic potential energy stored in the potential energy storage unit is released to the tank of the tested distribution transformer through the small-flow oil circuit. When the pressure monitoring module shows that the pressure value approaches 103 kPa, by adjusting the flow rate of the small-flow oil circuit, when the pressure monitoring module shows that the pressure value is stable within the range of 103 kPa ± 0.8 kPa, then entering the next stage;

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

[0029] Potential energy release and oil recovery stage: Turn on the oil pumping switch and start the oil pump. The potential energy accumulator unit releases pressure through the pressure relief valve.

[0030] Through the above technical solutions, by gradually increasing the pressure in the fuel tank in stages, from large-flow rapid filling to small-flow fine adjustment, it can ensure precise control of the pressure throughout the process. In the initial oil injection stage, the large-flow oil delivery mode is adopted, which can quickly fill the fuel tank of the test distribution transformer to 95% of its volume, greatly improving the test preparation efficiency and saving time costs. At the same time, the buffer airbag absorbs the oil impact vibration in real time, protecting the fuel tank and the oil circuit system from the impact force generated by large-flow oil injection and ensuring equipment safety; in the pressure pre-lift stage, a smaller oil volume increment is injected, which can precisely control the pressure rise process, timely detect that the system enters the pressure-sensitive area, and avoid test errors or equipment damage caused by too rapid pressure rise, laying a foundation for subsequent precise pressure stabilization; in the potential energy accumulation stage, compressed air energy storage is used to form a relatively stable potential energy reserve, raising the internal pressure of the potential energy accumulator unit to 0.2 MPa and providing a stable hydraulic potential energy source 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 Pascal's principle. The hydraulic potential energy in the potential energy accumulator unit is released through the small-flow oil circuit, and the flow rate of the small-flow oil circuit is adjusted according to the feedback of the pressure monitoring module, so that the pressure can be precisely stabilized within the range of 103 kPa ± 0.8 kPa, meeting the strict requirements of the test for pressure accuracy, improving the accuracy and reliability of the test results. The buffer airbag and the potential energy accumulator unit form a two-stage buffer, dynamically balancing the pressure fluctuations caused by the change in oil volume, and further improving the pressure shock attenuation rate; in the pressure holding test stage, the test pressure of 103 kPa is maintained for 10 minutes. During this period, pressure data is collected once every 5 seconds, and the oil volume can be fine-tuned and compensated in time for sudden pressure fluctuations, ensuring the stability of the pressure during the test process, enabling precise pressure stabilization control at the 103 kPa critical point, meeting the requirements of the GB / T6451 standard, effectively simulating the pressure conditions in actual operation, and being conducive to accurately detecting the cracking of the fuel tank. Finally, in the potential energy release and oil recovery stage, the oil pumping switch is turned on and the oil pump is started. At the same time, the potential energy accumulator unit releases pressure through the pressure relief valve, realizing the safe recovery of the oil and the stable drop of the system pressure, avoiding potential safety hazards and oil waste that may be caused by sudden pressure release, and improving the oil reuse rate. Description of the Drawings

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

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

[0033] Figure 2 Specific schematic diagram of the precise pressurizing device for the cracking test of the distribution transformer oil tank in the first embodiment of the present invention;

[0034] Figure 3 Structural schematic diagram of the precise pressurizing device for the cracking test of the distribution transformer oil tank in the first embodiment of the present invention;

[0035] Figure 4 Cross-sectional view of the precise pressurizing device for the cracking test of the distribution transformer oil tank in the first embodiment of the present invention;

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

[0037] Figure 6 Cross-sectional view of the precise pressurizing device for the cracking test of the distribution transformer oil tank in the first embodiment of the present invention from yet another perspective;

[0038] Figure 7 Cross-sectional views of the precise pressurizing device for the cracking test of the distribution transformer oil tank in the first embodiment of the present invention from other perspectives;

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

[0040] 20, the pressure monitoring module;

[0041] 30, the potential energy storage and pressurization unit; 31, the potential energy airbag; 32, the pressure controller;

[0042] 40, the oil storage tank; 41, the viewing window; 42, the oil storage chamber; 43, the filter screen; 44, the liquid thermometer; 45, the air filter; 46, the manual ball valve;

[0043] 50, the large-flow oil circuit; 51, the small-flow oil circuit; 52, the oil injection pump; 521, the motor; 522, the vane pump; 523, the check valve; 524, the pressure gauge; 525, the plate-type ball valve; 526, the overflow valve; 53, the oil injection switch; 54, the large-flow switch; 55, the small-flow switch; 551, the electromagnetic ball valve; 552, the servo regulating valve; 56, the shock-absorbing hose; 57, the butterfly valve;

[0044] 60, the buffer airbag;

[0045] 70, the oil return circuit; 71, the oil extraction switch; 72, the oil extraction pump; 73, the oil return filter. Detailed implementation manners

[0046] To make the objectives, 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 with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part rather than all of the embodiments of the present invention.

[0047] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present invention and the above accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data may be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order different from those illustrated or described herein.

[0048] It should be understood that in various embodiments of the present invention, the magnitude of the sequence numbers of the various processes does not mean the order of execution, and the order of execution of the various processes should be determined by their functions and internal logics, and should not constitute any limitation to the implementation process of the embodiments of the present invention.

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

[0050] It should be understood that in the present invention, "a plurality of" means two or more. "And / or" is merely a description of the relationship between associated objects, indicating that three relationships may exist. For example, X and / or Y may represent: X exists alone, X and Y exist simultaneously, and Y exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after. "Including X, Y, and Z", "including X, Y, Z" means that all of X, Y, and Z are included, "including X, Y, or Z" means including any one of X, Y, and Z, and "including X, Y, and / or Z" means including any one or any two or all three of X, Y, and Z.

[0051] The technical solutions of the present invention will be described in detail below with specific embodiments. These specific embodiments below can be combined or replaced according to the actual situation, and the same or similar concepts or processes may not be repeated in some embodiments.

[0052] Embodiment 1:

[0053] Such as Figures 1 to 7As shown in the figure, the present invention provides a precise pressurizing device for the cracking test of a distribution transformer oil tank, which includes a test distribution transformer 10, a pressure monitoring module 20, a potential energy storage unit 30, and an oil storage tank 40. The oil storage tank 40 and the oil tank 11 of the test distribution transformer 10 are connected through a large-flow oil circuit 50 and a small-flow oil circuit 51 in parallel. The potential energy storage unit 30 is located between the small-flow oil circuit 51 and the oil storage tank 40. The potential energy storage unit 30 stores energy using compressed air and releases hydraulic potential energy to the oil tank 11 of the test distribution transformer 10 in a gradient manner 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 test distribution transformer 10. When the pressure in the oil tank 11 of the test distribution transformer 10 exceeds the threshold, the small-flow oil circuit 51 automatically supplies oil to the oil tank 11 of the test distribution transformer 10 to supplement the threshold.

[0054] First of all, the large-flow oil circuit 50 can quickly inject hydraulic oil into the oil tank 11 of the test distribution transformer 10 at the initial stage of the test, rapidly raising the pressure to a range close to the target value, which can significantly shorten the test preparation time and improve work efficiency. The small-flow oil circuit 51 takes over the work when approaching the target pressure and achieves more precise pressurization by more finely adjusting the oil volume. This dual-oil-circuit design takes into account both efficiency and accuracy. It not only meets the requirement of rapid pressure rise, avoiding the influence caused by excessive waveform oscillation, but also ensures the accuracy of the final pressure value as much as possible, thus meeting the requirement of the GB / T6451 standard for steady-state pressure maintenance, enabling precise voltage stabilization control at the 103 kPa critical point. Secondly, by using the potential energy storage unit 30 and the small-flow oil circuit 51, a relatively stable potential energy reserve is formed by storing energy using compressed air, and the gradient release of hydraulic potential energy is achieved through Pascal's principle. Compared with the traditional direct-pressure pneumatic loading system, the pressure injected into the oil tank 11 of the test distribution transformer 10 can be controlled more precisely, and the amplitude of waveform oscillation can be reduced as much as possible, thus more accurately meeting the requirement of the GB / T6451 standard for steady-state pressure maintenance. 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, reducing the risk of aerosol pollution. A buffer airbag 60 is provided between the oil storage tank 40 and the oil tank 11 of the test distribution transformer 10. The buffer airbag 60 can also form a dynamic pressure buffering mechanism, effectively suppressing oil-circuit pulsation, playing a buffering role in the sudden pressure relief process, effectively absorbing the impact load, and avoiding excessive pressure peaks caused by sudden pressure relief. Finally, the pressure monitoring module 20 is set. When the pressure monitoring module 20 monitors that the pressure in the oil tank 11 of the test distribution transformer 10 exceeds the set threshold, the system can automatically supplement the oil volume through the small-flow oil circuit 51 to supplement the threshold, further enabling precise voltage stabilization control at the 103 kPa critical point. Thus, through the synergistic effect of potential energy storage and multi-stage buffering, while avoiding oil-circuit pollution, the 103 kPa test pressure can be maintained more precisely, and the voltage 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 can be a pressure gauge 524, which can provide real-time feedback on the oil tank 11 of the test distribution transformer 10.

[0056] When the transformer oil tank 11 is supplied with oil through the large-flow or small-flow oil circuit 51, instantaneous pressure peaks or fluctuations may occur, which may damage the equipment or affect the test accuracy. Among them, the buffer airbag 60 is located between the large-flow oil circuit 50 and the oil tank 11 of the test distribution transformer 10, and the buffer airbag 60 is located between the small-flow oil circuit 51 and the oil tank 11 of the test distribution transformer 10. The buffer airbag 60 can effectively absorb these pressure fluctuations, thereby protecting the equipment and maintaining the stability of the system.

[0057] Since the oil circuit path from the oil storage tank 40 to the oil tank 11 of the test distribution transformer 10 is relatively long, the oil delivery rate is attenuated. Therefore, in this application, an oil injection pump 52 is further provided on the oil circuit between the oil storage tank 40 and the test distribution transformer 10. The oil injection pump 52 is located between the oil storage tank 40 and the potential energy accumulator 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 test distribution transformer 10. By placing the oil injection pump 52 between the oil storage tank 40 and the potential energy accumulator unit 30, the oil can reach a relatively ideal flow rate and flow state before entering the potential energy accumulator unit 30, which helps the potential energy accumulator unit 30 store energy more efficiently and release the hydraulic potential energy to the oil tank 11 of the test distribution transformer 10 in a more precise manner.

[0058] In order to facilitate the control of the oil output of the oil storage tank 40, in this application, an oil injection switch 53 is provided on the downstream oil circuit of the oil injection pump 52. The oil injection switch 53 is located between the oil injection pump 52 and the potential energy accumulator unit 30. The oil injection switch 53 can accurately control the process of the oil flowing from the oil injection pump 52 to the potential energy accumulator unit 30, which means that the operator can flexibly open or close the oil supply according to the specific requirements of the test, so as to achieve more precise control of the oil flow in the whole system. When an abnormal situation (such as too high pressure, leakage or other emergency situations) is detected, the oil injection switch 53 can be quickly closed to immediately cut off the oil circuit and prevent the accident from expanding.

[0059] In addition, a large-flow oil circuit 50 and a small-flow oil circuit 51 are respectively provided with a large-flow switch 54 and a small-flow switch 55. The large-flow switch 54 and the small-flow switch 55 allow the operator to independently control the opening and closing of the two oil circuits according to actual needs. This means that the large-flow oil circuit 50 can be used when rapid filling is required and can be quickly adjusted through the large-flow switch 54. When fine adjustment or maintaining a steady-state pressure is carried out, the oil supply volume can be precisely controlled through the small-flow switch 55. In case of an emergency, either oil circuit can be quickly cut off through the large-flow switch 54 and the small-flow switch 55 to prevent, as much as possible, the problem of pressure out-of-control caused by misoperation or other unexpected situations.

[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 volume.

[0061] Among them, the potential energy accumulator unit 30 includes a potential energy airbag 31, and the volume ratio of the potential energy airbag 31 to the oil storage tank 40 is 1:3. The relatively large volume of the oil storage tank 40 can store sufficient oil, providing a continuous and stable oil source for the potential energy airbag 31 and the oil tank 11 of the test distribution transformer 10. When energy storage is required, the potential energy airbag 31 can quickly obtain an appropriate amount of oil from the oil storage tank 40 and use compressed air to compress and store the oil energy. By setting a reasonable volume ratio, it can ensure the effective absorption and release of energy during the test process, meeting both the requirements of rapid response and ensuring the stability of the system, and ensuring the linear controllability of subsequent pressure release. If the volume ratio is less than 1:3, during the pressure adjustment process, due to the small oil storage volume of the potential energy airbag 31, when energy needs to be released to change the pressure, it is difficult to ensure a stable oil output volume, and it may also lead to a discontinuous energy release process, 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 cause too much oil to be drawn from the oil storage tank 4 where the oil storage tank 40 may not be able to replenish it in time, resulting in the oil being idle in the potential energy airbag 31, unable to efficiently utilize the oil resources of the oil storage tank 40, reducing the overall energy storage efficiency. When releasing energy, due to the large amount of internal oil, the response speed of pressure change is slow, and the overly large potential energy airbag 31 will occupy a large amount of space, increasing the overall volume of the equipment.

[0062] Since multiple oil supplies are involved in this application, in order to ensure sufficient oil supply, the oil storage tank 40 is provided with a viewing window 41 that is conducive to observing the oil level change. The viewing window 41 allows the operator to directly see the oil level change in the oil storage tank 40. The operator can timely discover abnormal oil levels (such as too low an oil level may cause the injection oil pump 52 to run idly and be damaged, and too high an oil level may cause overflow, etc.), so as to take measures to prevent potential safety hazards.

[0063] In addition, in order to improve the reuse rate of the oil fluid, in this application, an oil return circuit 70 is also provided between the fuel tank 11 of the test distribution transformer 10 and the storage tank 40. The oil return circuit 70 is provided with an oil pumping switch 71 and an oil pump 72. The storage tank 40 is provided with an oil storage bin 42 and a multi-stage filter screen 43. The oil storage bin 42 is communicated with the large-flow oil circuit 50 and the small-flow oil circuit 51. The oil fluid in the oil return circuit 70 enters the oil storage bin 42 after flowing through the multi-stage filter screen 43. This enables the oil fluid flowing out of the fuel tank 11 of the test distribution transformer 10 after the test or during the test process to return to the storage tank 40, avoiding waste of the oil fluid and improving the utilization rate of the oil fluid. The storage tank 40 is provided with an oil storage bin 42 and a multi-stage filter screen 43. When the returned oil enters through the oil return circuit 70, after being filtered by the multi-stage filter screen 43, pollutants such as impurities and particles in the oil fluid can be effectively removed, making the oil fluid entering the oil storage bin 42 purer, and realizing the cyclic purification and reuse of the test oil fluid.

[0064] In order to make the oil return more stable, the oil return circuit 70 is connected to the fuel tank 11 of the test distribution transformer 10 through a buffer airbag 60. The buffer airbag 60 can effectively absorb the impact force and vibration generated during the oil return process, which can prevent pressure fluctuations caused by sudden oil fluid backflow. The buffer airbag 60 can also adjust the oil return flow rate to a certain extent. When the oil return flow rate is large, the buffer airbag 60 will be compressed to store a part of the oil fluid; when the oil return flow rate is small, the buffer airbag 60 will gradually expand to release the stored oil fluid, so that the oil return flow rate is more stable, which helps to improve the stability and accuracy of the entire test process.

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

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

[0067] It should be noted that during the oil injection stage, the large-flow oil circuit 50 can be used to quickly inject oil first. At this time, the oil injection pump 52 runs at a high speed to complete the injection of most of the oil fluid into the fuel tank 11 of the test distribution transformer 10, specifically 80% or 90% or 95% of the fuel tank 11 of the test distribution transformer 10. Then, fine-tuning oil injection is carried out through the small-flow oil circuit 51. At this time, the oil injection pump 52 runs at a low speed, and the oil fluid is injected into the fuel tank 11 at an increment 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] In this embodiment, a precise pressurization method for the cracking test of a distribution transformer oil tank is provided. Using the precise pressurization device for the cracking test of a distribution transformer oil tank according to any one of the above embodiments, the potential energy accumulator unit is provided with a pressure relief valve. The precise pressurization method for the cracking test of a distribution transformer oil tank includes an initial oil injection stage: closing the small-flow oil circuit and opening the large-flow oil circuit, adopting a large-flow oil transportation mode of more than 300 L / min, injecting oil into the oil tank of the distribution transformer to be tested until the oil volume reaches 95% of the volume. During the oil injection process, the buffer airbag absorbs the impact vibration of the oil in real time;

[0074] Pressure pre-lift stage: closing the large-flow oil circuit, opening the small-flow oil circuit, injecting oil into the oil tank of the distribution transformer to be tested at an increment of 5 - 10 mL / s. When the pressure monitoring module shows that the pressure value breaks through the atmospheric pressure baseline, it indicates that the system enters the pressure-sensitive area, then close the small-flow oil circuit;

[0075] Potential energy accumulation stage: starting the potential energy accumulator unit, injecting oil into the potential energy accumulator unit to increase the internal pressure of the potential energy accumulator unit to 0.2 MPa, then stop injecting oil;

[0076] Precise pressure stabilization stage: opening the small-flow oil circuit, the hydraulic potential energy stored in the potential energy accumulator unit is released to the oil tank of the distribution transformer to be tested through the small-flow oil circuit. When the pressure monitoring module shows that the pressure value approaches 103 kPa, adjust the flow rate of the small-flow oil circuit. When the pressure monitoring module shows that the pressure value is stable within the range of 103 kPa ± 0.8 kPa, then enter the next stage;

[0077] Pressure holding test stage: maintaining the test pressure of 103 kPa for 10 minutes, during which the pressure monitoring module collects pressure data every 5 seconds. If a sudden pressure fluctuation exceeds the threshold (±1.5 kPa), the small-flow oil circuit automatically compensates 0.5 - 2 mL of oil for fine adjustment;

[0078] Potential energy release and oil recovery stage: opening the oil pumping switch and starting the oil pump, the potential energy accumulator unit releases pressure through the pressure relief valve.

[0079] Through the above technical solutions, by gradually increasing the pressure in the fuel tank in stages, from rapid filling with a large flow rate to fine adjustment with a small flow rate, precise control of the pressure can be ensured throughout the process. In the initial fuel injection stage, a large-flow fuel delivery mode is adopted, which can quickly fill the fuel tank of the tested distribution transformer to 95% of its 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 fuel tank and the oil circuit system from the impact force generated by large-flow fuel injection and ensuring equipment safety; in the pressure pre-lift stage, a smaller oil increment is injected, which can precisely control the pressure rise process, timely detect that the system enters the pressure-sensitive area, and avoid test errors or equipment damage caused by too rapid pressure rise, laying a foundation for subsequent precise pressure stabilization; in the potential energy storage and pressure stage, compressed air energy storage is used to form a relatively stable potential energy reserve, and the internal pressure of the potential energy storage and pressure unit is increased to 0.2 MPa, providing a stable hydraulic potential energy source for the precise pressure stabilization stage and 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 Pascal's principle. The hydraulic potential energy in the potential energy storage and pressure unit is released through a small-flow oil circuit, and the flow rate of the small-flow oil circuit is adjusted according to the feedback of the pressure monitoring module, so that the pressure can be precisely stabilized within the range of 103 kPa ± 0.8 kPa, meeting the strict requirements of the test for pressure accuracy, improving the accuracy and reliability of the test results. The buffer airbag and the potential energy storage and pressure unit form two-stage buffering, dynamically balancing the pressure fluctuations caused by the change in oil volume, and further increasing the pressure impact attenuation rate to more than 92%; in the pressure holding test stage, the test pressure of 103 kPa is maintained for 10 minutes. During this period, pressure data is collected every 5 seconds, and fine adjustment compensation of the oil volume can be carried out in a timely manner for sudden pressure fluctuations, ensuring the stability of the pressure during the test process, enabling precise pressure stabilization control at the 103 kPa critical point, meeting the requirements of the GB / T6451 standard, effectively simulating the pressure conditions in actual operation, and being conducive to accurately detecting the cracking situation of the fuel tank. Finally, in the potential energy release and oil recovery stage, the oil pumping switch is turned on and the oil pump is started. At the same time, the potential energy storage and pressure unit releases pressure through the pressure relief valve, realizing the safe recovery of the oil and the smooth drop of the system pressure, avoiding potential safety hazards and oil waste that may be caused by sudden pressure release, and improving the reuse rate of the oil.

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

[0081] It should be noted that during the pressure holding test stage, if the sudden pressure fluctuation exceeds the threshold (±1.5 kPa), the buffer 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 oil volume fine adjustment of 0.5 - 2 mL.

[0082] It should be noted that during the potential energy release and oil recovery stage, the oil pump is started, and the oil in the tank of the tested distribution transformer is quickly pumped back to the storage tank at a flow rate of 200 L / min. The oil flows through a three-stage gradient filter screen, and the filtration degrees of the three-stage gradient filter screen include 100 μm, 50 μm, and 10 μm, achieving the interception of particles from large to small. The multi-layer filter screen in the storage tank continuously filters the circulating oil to ensure that the medium cleanliness meets the ISO4406 18 / 16 / 13 grade requirements. The purified oil is stored in the oil storage bin of the storage tank, and the recovery rate is ≥ 98%, breaking through the 98% technical bottleneck of the oil reuse rate. The potential energy airbag slowly releases the residual pressure through the pressure relief valve, and the system returns to the initial state.

[0083] In addition to the above preferred embodiments, the present invention has other implementation manners. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection claimed by the present invention.

Claims

1. Precision pressurization device for cracking test of distribution transformer oil tank, characterized in that, It includes a test distribution transformer, a pressure monitoring module, a potential energy accumulator unit and an oil storage tank. The oil storage tank and the oil tank of the test distribution transformer are connected through a large-flow oil circuit and a small-flow oil circuit in parallel. The potential energy accumulator unit is located between the small-flow oil circuit and the oil storage tank. The potential energy accumulator unit stores energy using compressed air and releases hydraulic potential energy to the oil tank of the test distribution transformer in a gradient manner through the small-flow oil circuit. A buffer airbag is also provided on the oil circuit between the oil storage tank and the oil tank of the test distribution transformer. The pressure monitoring module is used to monitor the pressure in the oil tank of the test distribution transformer. When the pressure in the oil tank of the test distribution transformer exceeds the threshold, the small-flow oil circuit automatically supplies oil to the oil tank of the test distribution transformer to supplement the threshold.

2. The precise pressure boosting device for the cracking test of the distribution transformer oil tank according to claim 1, wherein The buffer airbag is located between the large-flow oil circuit and the oil tank of the test distribution transformer, and the buffer airbag is located between the small-flow oil circuit and the oil tank of the test distribution transformer.

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

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

5. The precise pressure boosting device for the cracking test of the distribution transformer oil tank according to claim 1, wherein The potential energy accumulator 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 pressure boosting device for the cracking test of the distribution transformer oil tank according to claim 1, wherein, A large-flow switch and a small-flow switch are respectively provided on the large-flow oil circuit and the small-flow oil circuit.

7. The precise pressure boosting device for the cracking test of the distribution transformer oil tank according to claim 1, wherein, A viewing window is provided on the oil storage tank to facilitate observing the change of the oil level.

8. The precise pressurization device for the cracking test of the distribution transformer oil tank according to claim 1, characterized in that, A return oil circuit is also provided between the oil tank of the test distribution transformer and the oil storage tank. The return oil circuit is provided with an oil pumping switch and an oil pump. The oil storage tank is provided with an oil storage chamber and a multi-stage filter screen. The oil storage chamber is communicated with the large-flow oil circuit and the small-flow oil circuit. The oil fluid of the return oil circuit enters the oil storage chamber after flowing through the multi-stage filter screen.

9. The precise pressurizing device for the cracking test of the distribution transformer oil tank according to claim 8, wherein The return oil circuit is connected to the oil tank of the test distribution transformer through a buffer airbag.

10. A precise pressurization method for the cracking test of a distribution transformer oil tank, characterized in that, It includes the precise pressurization device for the cracking test of the distribution transformer oil tank as described in claim 8 or 9. The potential energy accumulator unit is provided with a pressure relief valve. The precise pressurization method for the cracking test of the distribution transformer oil tank includes the initial oil injection stage: closing the small-flow oil circuit and opening the large-flow oil circuit, adopting a large-flow oil supply mode of more than 300 L / min, injecting oil into the oil tank of the test distribution transformer until 95% of the volume of oil is filled. During the oil injection process, the buffer airbag absorbs the impact vibration of the oil fluid in real time; The pressure pre-lift stage: closing the large-flow oil circuit, opening the small-flow oil circuit, injecting oil fluid into the oil tank of the test distribution transformer at an increment of 5 - 10 mL / s. When the pressure monitoring module shows that the pressure value breaks through the atmospheric pressure baseline, it indicates that the system enters the pressure sensitive area, then close the small-flow oil circuit; The potential energy accumulation stage: starting the potential energy accumulator unit, injecting oil fluid into the potential energy accumulator unit to increase the internal pressure of the potential energy accumulator unit to 0.2 MPa, then stop injecting oil; Precise voltage stabilization stage: Open the small-flow oil circuit, and the hydraulic potential energy stored in the potential energy storage and pressure accumulation unit is released to the oil tank of the distribution transformer under test through the small-flow oil circuit. When the pressure monitoring module shows that the pressure value approaches 103 kPa, adjust the flow rate of the small-flow oil circuit. When the pressure monitoring module shows that the pressure value is stable within the range of 103 kPa ± 0.8 kPa, enter the next stage; Pressure holding test stage: Maintain the test pressure of 103 kPa for 10 minutes. During this period, the pressure monitoring module collects pressure data every 5 seconds. If a sudden pressure fluctuation exceeds the threshold (±1.5 kPa), the small-flow oil circuit automatically compensates 0.5 - 2 mL of oil for fine adjustment; Potential energy release and oil recovery stage: Turn on the oil pumping switch and start the oil pump, and the potential energy storage and pressure accumulation unit releases pressure through the pressure relief valve.

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