Transformer oil tank anti-explosion equivalent test device and method

Abstract

The invention discloses an anti-explosion equivalent test device and method for a transformer oil tank, and belongs to the technical field of transformer tests.The method comprises the steps that liquid is injected into the oil tank till the liquid filling rate reaches a set value; pressurizing the oil tank to target pressure by using a pressurizing device, and collecting a pressure signal and expansion displacement in real time; for each measuring point, performing fitting analysis on the internal pressure and the expansion displacement collected in the sampling time period, and establishing an analytical expression of the expansion displacement and the pressure increment; performing fast Fourier transform on the expansion displacement signal of one measuring point, and extracting the amplitude-frequency characteristic of the expansion displacement signal; calculating Pearson's correlation coefficients among the measuring points, and analyzing the consistency of mechanical behaviors of different measuring points according to the Pearson's correlation coefficients among the measuring points; the maximum expansion displacement value in the pressurization process is monitored, and whether the anti-explosion performance meets the requirement or not is judged according to the maximum expansion displacement value. A series of problems of high cost, poor universality and the like of the explosion-proof test in the current power transformer industry are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of transformer testing, and in particular relates to a transformer oil tank explosion proof equivalent testing device and method. Background Art

[0002] Oil-immersed power transformers utilize an oil-paper insulation system. However, as the transformers come into operation, a series of electrochemical processes, including insulation aging and gas generation, inevitably occur within the transformers due to the coupled electromagnetic-structural-fluid-solid-temperature field interaction. During this process, the pressure inside the transformer's oil tank rises dramatically. Despite the presence of pressure relief valves and other safeguards, a lack of structural strength in the oil tank can lead to significant safety hazards, such as oil tank explosions. Once a transformer explosion occurs, it can easily trigger a chain reaction, posing a significant threat to the safety, stability, and reliability of the power system. Current transformer oil tank explosion tests are mostly based on arc tests or TNT equivalent tests. These methods present significant safety risks, are uncontrollable, and can cause irreversible damage to the oil tank, site, and test equipment, leading to high testing costs. Furthermore, these methods are not widely available. Summary of the Invention

[0003] In order to overcome the defects of the above-mentioned prior art, the purpose of the present invention is to propose a transformer oil tank explosion proof equivalent test device and method to solve a series of problems in the current power transformer industry such as high cost and poor popularization of explosion proof testing.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] In a first aspect, the present invention provides a transformer oil tank explosion proof equivalent test method, comprising the following steps:

[0006] S1. Place pressure sensors at typical stress-bearing locations on the transformer tank. The locations where the pressure sensors are placed are recorded as measuring points. Place several distance meters outside the transformer tank to measure the displacement of each measuring point.

[0007] S2. Inject liquid into the fuel tank until the liquid filling rate reaches the set value; control the liquid temperature between 40°C and 60°C to simulate the thermal state of the gas-liquid mixing zone at the initial stage of explosion; use the booster device to pressurize the fuel tank to the target pressure, and collect the internal pressure and expansion displacement of each measuring point in real time;

[0008] S3. For each measuring point, perform fitting analysis on the internal pressure and expansion displacement collected during the sampling period to establish an analytical expression for the expansion displacement and pressure increment; perform a fast Fourier transform on the expansion displacement signal at one measuring point to extract its amplitude-frequency characteristics; calculate the Pearson correlation coefficient between each measuring point, and analyze the consistency of the mechanical behavior of different measuring points based on the Pearson correlation coefficient between each measuring point;

[0009] S4. Monitor the maximum expansion displacement value during the pressurization process and determine whether the anti-explosion performance meets the requirements based on the maximum expansion displacement value.

[0010] Furthermore, in S2, when pressurizing the fuel tank, the average pressurization rate is 5 kPa / min to 20 kPa / min, the pressurization time is adjusted according to the volume of the fuel tank, and the target pressure is 200 kPa to 500 kPa.

[0011] Furthermore, in S3, the analytical expression of the expansion displacement and the pressure increment is: d = a·Δp + b;

[0012] Where d is the expansion displacement, Δ p is the internal pressure increment, a is the expansion sensitivity coefficient, and b is the offset.

[0013] Furthermore, in S3, performing fast Fourier transform on the expansion displacement signal at a measuring point to extract its amplitude-frequency characteristics includes:

[0014] Perform fast Fourier transform on the expansion displacement signal to obtain the frequency domain complex spectrum D(f),

[0015] The amplitude spectrum is extracted by the following formula:

[0016]

[0017] Where |D(f)| is the amplitude spectrum; Re(·) represents the real part of the frequency domain complex spectrum, and Im(·) represents the imaginary part of the frequency domain complex spectrum;

[0018] By analyzing the maximum value in the amplitude spectrum, the peak frequency f corresponding to the maximum amplitude is determined peak , and obtain the amplitude-frequency characteristics.

[0019] Furthermore, in S3, the Pearson correlation coefficient between each measurement point is calculated by the following formula:

[0020]

[0021] Where r m,j is the Pearson correlation coefficient between measurement point m and measurement point j, d m,k is the expansion displacement value obtained at the mth measuring point at the kth sampling moment, represents the average expansion value of the mth measuring point, d j,k is the expansion displacement value obtained at the jth measuring point at the kth sampling moment, It represents the average expansion value of the jth measuring point, and n is the total number of sampling points.

[0022] Furthermore, in S4, whether the fuel tank's anti-explosion performance is qualified is determined by the following standards:

[0023] If the tank does not crack during the continuous pressurization process and the maximum expansion displacement Δd is monitored max Satisfy the following formula:

[0024] Δd max ≤Δd allow

[0025] Where Δd allow is the preset allowed deformation threshold;

[0026] It is determined that the anti-combustion and explosion performance meets the requirements.

[0027] Furthermore, in S3, the consistency of mechanical behavior of different parts is analyzed based on the Pearson correlation coefficient between each measuring point:

[0028] If the Pearson correlation coefficient between the two measuring points is greater than 0.7, it is determined that the mechanical properties of the points on both sides of the fuel tank are consistent and the expansion characteristics under combustion and explosion conditions are consistent;

[0029] If the Pearson correlation coefficient between two measuring points is less than 0.7, it is determined that there are certain differences in the mechanical properties at the points on both sides of the fuel tank, and there are significant differences in deformation under combustion and explosion.

[0030] In a second aspect, the present invention provides a transformer tank explosion proof equivalent test device, comprising a pressurizing device, a data acquisition system, a signal processing module, and a protective fence;

[0031] The boosting device is connected to the transformer oil tank through a pipeline and is used to continuously pressurize the oil tank after the liquid is injected into the oil tank to increase the pressure to the target pressure; an oil filling valve is installed on the pipeline;

[0032] The data acquisition is used to synchronously collect the internal pressure and expansion displacement of the fuel tank in real time;

[0033] The signal processing module is used to perform correlation analysis and frequency domain characteristic extraction on the collected internal pressure and expansion displacement of the fuel tank, and obtain analytical expressions for the expansion displacement and pressure increment, consistency of mechanical behavior between measurement points, and anti-explosion performance.

[0034] Furthermore, the data acquisition system includes several pressure sensors, several laser rangefinders and several high-speed cameras. The pressure sensors are used to collect the internal pressure of each measuring point in the fuel tank in real time, the laser rangefinders are used to measure the expansion displacement of each measuring point in real time, and the high-speed cameras are used to monitor the images of weak parts of the fuel tank in real time.

[0035] Furthermore, the pressure sensors are arranged at the top of the oil tank, the center of the side wall, the reinforcing iron and the weld joints.

[0036] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0037] Traditional methods rely on explosion tests, which have uncontrollable risks and high costs. The present invention replaces explosion with controllable pressurization, combines multi-channel data acquisition, integrates pressurization simulation, multi-dimensional monitoring of pressure, displacement and deformation, as well as frequency domain identification and data correlation analysis, and can repeatedly verify the true response of the oil tank under extreme working conditions, providing a new solution for transformer oil tank explosion test and saving verification costs. The oil tank explosion test is a destructive test. Taking a general 110kV / 50MVA power transformer as an example, it takes at least 1 million to conduct an arc test, and the safety requirements for the test site are extremely high. By adopting the equivalent method of the present invention, the relationship between the pressure increment and the expansion displacement in the non-explosion state can be studied to infer the expansion displacement corresponding to the pressure increment in the explosion state. This does not damage the oil tank, has small site restrictions, is highly safe, and the cost of consumables is only about 10,000 yuan.

[0038] Based on measurement data, this method establishes a quantitative analytical relationship model between pressure increment and displacement, quantifying the deformation sensitivity of the fuel tank. Combined with FFT frequency-domain analysis, it reveals structural vibration weaknesses, and uses a Pearson correlation coefficient matrix to precisely locate mechanical differences in areas such as welds and reinforcements. By linking deformation thresholds with correlation coefficient criteria, a dual mechanism of "threshold triggering + regional warning" is implemented, providing a scientific basis for fuel tank structural optimization.

[0039] The adjustable protective fence provided by the present invention supports rapid adaptation of oil tanks of various specifications and has a high device reuse rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A flow chart of a transformer oil tank explosion proof equivalent test method provided by the present invention;

[0041] Figure 2 A schematic diagram of a transformer oil tank explosion proof equivalent test equipment provided for the invention;

[0042] Figure 3 is the pressure-expansion displacement response curve of a certain measuring point;

[0043] Figure 4is the correlation coefficient matrix of the expansion values ​​at each measuring point. DETAILED DESCRIPTION

[0044] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0045] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0046] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be another element centered thereon. When an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be another element centered thereon at the same time. The terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc. used herein indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0048] Example 1

[0049] Reference Figure 2 This embodiment provides a transformer oil tank explosion proof equivalent test device, including a booster device, a data acquisition system, a signal processing module and a protective fence.

[0050] The boosting device is a boosting pump, which is connected to the transformer oil tank through a pipeline. A liquid injection valve is installed on the pipeline. After liquid is injected into the oil tank, it is continuously pressurized to a level far exceeding the normal working pressure to simulate the explosion condition; the data acquisition system synchronously collects the internal pressure, expansion displacement and surface deformation signals of the oil tank in real time, and the signal processing module performs correlation analysis and frequency domain characteristic extraction on the collected internal pressure, expansion displacement and surface deformation signals of the oil tank, thereby verifying the ultimate performance of the oil tank's explosion-proof design.

[0051] The data acquisition system includes a pressure sensor, a laser rangefinder, and a high-speed camera. The pressure sensor is used to collect real-time internal tank pressure, the laser rangefinder is used to measure the expansion and displacement of the tank wall, and the high-speed camera is used to monitor the deformation process of the tank's weak points in real time. Because the added protective fence blocks light, the camera light source is insufficient, so the recording process must be equipped with a flicker-free LED light. The high-speed camera (specific parameters are 5 million pixels, a resolution of 2560×2016, and 3600 frames per second, or 3600 fps) is mainly placed in specific areas such as the center of the long side of the tank and the weld seam. It is mainly used to capture the cracking moment in these specific areas for archiving and facilitating subsequent analysis of the fracture process.

[0052] Among them, pressure sensors are arranged at typical stress-bearing locations such as the top of the fuel tank, the center of the side wall, the reinforcement iron, and the weld joints to capture the internal pressure responses of these key locations; the pressure sensors are preferably patch pressure sensors; the number of laser rangefinders is not less than 3, and they are preferably arranged in the middle of the long side wall of the fuel tank, the reinforcement area and near the weld to measure the deformation of the above-mentioned areas; among them, pressure sensors are arranged densely at weak locations such as welds and reinforcement irons where stress is concentrated and connection failure is prone to occur, and the sampling interval is no more than 50% of the interval between other measuring points to improve the monitoring resolution and failure warning capabilities of key areas.

[0053] The "tank top, sidewall center, reinforcement iron, and weld joints" are selected as key locations. Transformer connection failures are typically concentrated in these areas, but theoretically, they can be expanded to encompass any measurement area of ​​interest. The data acquisition system features multi-channel synchronous sampling, with each channel sampling at a frequency of no less than 4096 Hz and a displacement measurement accuracy of no less than 0.3 mm, ensuring the synchronization and accuracy of pressure, displacement, and image signals.

[0054] For each measuring point, the signal processing module is used to obtain the pressure increment signal based on the synchronously collected expansion displacement signals (laser ranging instrument) at different times and the internal pressure signals at the corresponding times, and to establish a quantitative analytical relationship between the pressure increment and the expansion displacement through the least squares method and linear regression method.

[0055] The signal processing module is also used to collect expansion displacement values ​​from multiple measuring points and calculate the Pearson correlation coefficient between any two measuring points.

[0056] During the test, the transformer tank, booster device, data acquisition system, high-speed camera outside the signal processing module and peripherals are equipped with detachable and adjustable protective fences. The inner dimensions of the protective fence and the outer dimensions of the tank meet the following formula:

[0057] L ′ =L+2Δ,W ′ =W+2Δ,H ′ =H+Δ

[0058] Wherein, L' is the inner length of the fence, W' is the inner width of the fence, H' is the inner height of the fence, L is the length of the fuel tank, W is the width of the fuel tank, H is the height of the fuel tank, Δ is the safety margin, preferably in the range of 0.5m to 1.0m; the protective fence adopts a composite structure of a high-strength steel frame and an explosion-proof metal mesh. The mesh size of the explosion-proof metal mesh is preferably not larger than 50mm×50mm to effectively prevent fragments from splashing out during pressurized rupture and ensure the safety of test personnel and equipment.

[0059] Example 2

[0060] Reference Figure 1 This embodiment provides a transformer oil tank explosion proof equivalent test method, comprising the following steps:

[0061] Step 1: Pretreatment and device preparation

[0062] According to the structural dimensions and design grade of the transformer oil tank to be tested, an explosion-proof oil tank equivalent test device with matching size adjustment function is selected to complete the assembly of the booster device, data acquisition system, signal processing module and protective fence.

[0063] Pressure sensors are deployed at typical stress-bearing locations, such as the tank top, sidewall center, reinforcement iron, and weld joints. These locations are designated as measuring points. Laser rangefinders are deployed outside these typical stress-bearing locations to measure expansion displacement at each measuring point. Laser rangefinders can also be deployed more densely to identify weaker locations. High-speed cameras are also deployed to capture dynamic images of these locations. The number of laser rangefinders is equal to the number of pressure sensors.

[0064] Step 2: Liquid injection and pressurized environment setting

[0065] Liquid is injected into the fuel tank through the oil filling valve to ensure that the liquid filling rate reaches the preset value of 0.1MPA. Among them, mineral oil and other fluid materials are preferred. Water with lower cost is preferred. The liquid temperature is controlled between 40℃ and 60℃ to simulate the thermal state of the gas-liquid mixing zone at the initial stage of explosion. The fuel tank is pressurized with a booster device. The boosting process varies depending on the size of the fuel tank, with an average boosting rate preferably set within the range of 5 to 20kPa / min. The pressurization time is adjusted according to the fuel tank volume, and the target pressure is controlled at 200kPa to 500kPa. The larger the fuel tank volume, the faster the boosting rate and the longer the pressurization time. This is far higher than the conventional 98kPa water pressure test standard.

[0066] The target pressure can be set according to the pressure you want to study or verify, or it can be calculated using the following formula:

[0067]

[0068] Among them, P target The set pressure for the explosion test (unit: kPa); P0 is the basic reference pressure, specifically the pressure of the liquid medium (98kPa for water); V is the volume of the tank; k e is the explosion proportional factor; V0 is the fuel tank pressure fitting variable.

[0069] If the instantaneous state of explosion is simulated, a temperature of 250°C-800°C is used to simulate the instantaneous temperature of explosion.

[0070] Step 3: Multi-channel sensor deployment and synchronous acquisition startup

[0071] Start the multi-channel synchronous acquisition system and set the sampling frequency to no less than 4096Hz. From the start of pressurization and during the continuous pressurization process, real-time acquisition of pressure signals, expansion displacement signals, and image data is performed.

[0072] Step 4: Signal processing analysis

[0073] The signal processing module performs the least square fitting analysis on the expansion displacement and pressure increment of each measuring point, establishes the linear analytical expression of expansion displacement and pressure increment, and obtains the pressure increment-expansion displacement response curve of each measuring point (such as Figure 3 The expansion displacement signal is subjected to fast Fourier transform (FFT) to extract its amplitude-frequency characteristics; the Pearson correlation coefficient between each measuring point is calculated to generate the Pearson correlation matrix and thermal map to analyze the consistency of the mechanical behavior of different parts.

[0074] For each measuring point, the signal processing module is used to establish a fitting expression based on the synchronously collected expansion displacement signal and the internal pressure increment signal at the corresponding moment through the least squares method and linear regression method to describe the quantitative analytical relationship between the two. The expansion displacement under the unmeasured pressure increment can be calculated through the fitting expression through interpolation and other methods.

[0075] The fitting expression is:

[0076] d=a·Δp+b (1)

[0077] Where d is the expansion displacement, Δ p is the internal pressure increment, a is the expansion sensitivity coefficient, and b is the offset. Parameters a and b can be obtained based on the least squares method by minimizing the residual S of the following formula:

[0078]

[0079] Where n is the signal length, i is the signal retrieval, and it satisfies 1≤i≤n. i represents the expansion displacement of each measuring point at time i; Δp i is the pressure of each measuring point at time i;

[0080] d and Δp represent the expansion displacement signal collected by the laser ranging sensor and the internal pressure signal Δp obtained by the pressure sensor during the time period 0-n, respectively; they have an analytical solution:

[0081]

[0082] Through the above modeling process, the quantitative analysis of the expansion deformation characteristics of the fuel tank is achieved based on the real measured data.

[0083] The expansion displacement signal of the measuring point with the largest expansion displacement is selected for fast Fourier transform (FFT) analysis to obtain the frequency domain complex spectrum D(f), and the amplitude spectrum |D(f)| is extracted:

[0084]

[0085] By analyzing the maximum value in |D(f)|, Re(·) represents the real part of the frequency domain complex spectrum, Im(·) represents the imaginary part of the frequency domain complex spectrum, and determining the peak frequency f corresponding to the maximum amplitude peak , in order to identify the response characteristics of the local structure of the fuel tank to specific frequency excitation, and then quantitatively characterize the deformation sensitivity of the fuel tank under different frequency components during the combustion and explosion process.

[0086] The signal processing module also calculates the Pearson correlation coefficient between any two measurement points based on the expansion displacement collected at multiple measurement points according to the following formula:

[0087]

[0088] Where r m，j is the Pearson correlation coefficient between measurement point m and measurement point j, d m，k is the expansion displacement value obtained at the mth measuring point at the kth sampling moment, represents the average expansion value of the mth measuring point, d j,k is the expansion displacement value obtained at the jth measuring point at the kth sampling moment, It represents the average expansion value of the jth measuring point, and n is the total number of sampling points.

[0089] The signal processing module organizes the Pearson correlation coefficients calculated between multiple measurement points into a symmetric correlation coefficient matrix and generates Figure 4 The heat map shown is used to visualize the correlation between the expansion displacement values ​​of each measuring point;

[0090] Figure 4 In the above, the correlation coefficients of the expansion signal sampling points are visually analyzed. Combining with formula (5), it can be seen that the correlation coefficients meet the interactivity criterion, that is, r m,j =r j,m , and the autocorrelation, r j，j =1; further, the following general inference can be drawn:

[0091] (1) Pearson correlation coefficient m,j If it is greater than 0.7, it can be determined that the mechanical properties at the points on both sides of the fuel tank are relatively consistent, and the expansion characteristics under combustion and explosion conditions are relatively consistent;

[0092] (2) Pearson correlation coefficient m,j If the value is less than 0.7, it can be determined that there are certain differences in the mechanical properties at the points on both sides of the fuel tank, and there are significant differences in the deformation under combustion and explosion, which has the possibility of potential local pre-plastic failure.

[0093] Step 5: Evaluation of combustion and explosion response behavior and performance determination

[0094] Monitor the maximum expansion displacement value during the pressurization process. If the fuel tank does not crack and the maximum expansion displacement does not exceed the preset deformation threshold, it is determined that the anti-explosion performance meets the requirements; otherwise, the measuring point position where the maximum expansion displacement exceeds the preset deformation threshold is identified as a structural risk point.

[0095] The following standards are used to determine whether the fuel tank's anti-explosion performance is qualified: the fuel tank does not crack during continuous pressurization, and the maximum expansion displacement Δd is monitored. max satisfy:

[0096] Δd max ≤Δd allow (6)

[0097] Where Δd allow To preset the allowable deformation threshold, 8mm to 12mm is preferred. The specific value should also be combined with the material type and the tank design level.

[0098] The maximum static pressure that the transformer tank can withstand can also be obtained by the pressure applied to the transformer tank by the pressure device during cracking, Pmax = P 加压 , where Pmax is the maximum static pressure that the transformer tank can withstand, P 加压 It is the pressure applied to the transformer tank by the pressurizing device when cracking.

[0099] Step 6: End of experiment and data archiving

[0100] Stop pressurization, export the entire process signal data, use the open source Python Matplotlib library to process the pressure signal and expansion displacement, implement time domain and frequency domain visualization operations, complete the structural response visualization analysis, and output PDF reports and thermal map results to provide a basis for tank structure design optimization.

[0101] The term "consisting of" when describing a combination should include the identified elements, ingredients, components, or steps as well as other elements, ingredients, components, or steps that do not materially affect the basic novel characteristic of the combination. The use of the terms "comprising" or "including" to describe a combination of elements, ingredients, components, or steps herein also contemplates embodiments consisting essentially of these elements, ingredients, components, or steps. The use of the term "may" herein is intended to indicate that any of the attributes described as "may" be optional.

[0102] Multiple elements, ingredients, parts or steps can be provided by a single integrated element, ingredient, part or step. Alternatively, a single integrated element, ingredient, part or step can be divided into separate multiple elements, ingredients, parts or steps. The disclosure of "a" or "an" to describe an element, ingredient, part or step is not intended to exclude other elements, ingredients, parts or steps.

[0103] It should be understood that the above description is for illustrative purposes only and is not intended to be limiting. Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but rather with reference to the preceding claims and the full scope of equivalents to which such claims are entitled. For the purpose of completeness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein from the preceding claims is not a disclaimer of such subject matter, nor should it be considered that the applicants did not consider such subject matter to be part of the disclosed inventive subject matter.

Claims

1. A transformer oil tank explosion proof equivalent test method, characterized in that: The following steps are involved: S1. Place pressure sensors at typical stress-bearing locations on the transformer tank. The locations where the pressure sensors are placed are recorded as measuring points. Place several distance meters outside the transformer tank to measure the displacement of each measuring point. S2. Inject liquid into the fuel tank until the liquid filling rate reaches the set value; control the liquid temperature between 40°C and 60°C to simulate the thermal state of the gas-liquid mixing zone at the initial stage of explosion; use the booster device to pressurize the fuel tank to the target pressure, and collect the internal pressure and expansion displacement of each measuring point in real time; S3. For each measuring point, perform fitting analysis on the internal pressure and expansion displacement collected during the sampling period to establish an analytical expression for the expansion displacement and pressure increment; perform a fast Fourier transform on the expansion displacement signal at one measuring point to extract its amplitude-frequency characteristics; calculate the Pearson correlation coefficient between each measuring point, and analyze the consistency of the mechanical behavior of different measuring points based on the Pearson correlation coefficient between each measuring point; S4. Monitor the maximum expansion displacement value during the pressurization process, and determine whether the anti-explosion performance meets the requirements based on the maximum expansion displacement value.

2. A transformer oil tank explosion proof equivalent test method according to claim 1, characterized in that: In the above-mentioned S2, when the fuel tank is pressurized, the average pressurization rate is 5 kPa / min to 20 kPa / min, the pressurization time is adjusted according to the volume of the fuel tank, and the target pressure is 200 kPa to 500 kPa.

3. A transformer oil tank explosion proof equivalent test method according to claim 1, characterized in that: In S3, the analytical expression of the expansion displacement and the pressure increment is: d = a·Δp + b; Where d is the expansion displacement, Δ p is the internal pressure increment, a is the expansion sensitivity coefficient, and b is the offset.

4. A transformer oil tank explosion proof equivalent test method according to claim 1, characterized in that: In S3, performing fast Fourier transform on the expansion displacement signal at a measuring point to extract its amplitude-frequency characteristics includes: Perform fast Fourier transform on the expansion displacement signal to obtain the frequency domain complex spectrum D(f), The amplitude spectrum is extracted by the following formula: Where |D(f)| is the amplitude spectrum; Re(·) represents the real part of the frequency domain complex spectrum, and Im(·) represents the imaginary part of the frequency domain complex spectrum; By analyzing the maximum value in the amplitude spectrum, the peak frequency f corresponding to the maximum amplitude is determined peak , and obtain the amplitude-frequency characteristics.

5. A transformer oil tank explosion proof equivalent test method according to claim 1, characterized in that: In S3, the Pearson correlation coefficient between each measurement point is calculated by the following formula: Where r m,j is the Pearson correlation coefficient between measurement point m and measurement point j, d m,k is the expansion displacement value obtained at the mth measuring point at the kth sampling moment, represents the average expansion value of the mth measuring point, d j,k is the expansion displacement value obtained at the jth measuring point at the kth sampling moment, It represents the average expansion value of the jth measuring point, and n is the total number of sampling points.

6. A transformer oil tank explosion proof equivalent test method according to claim 1, characterized in that: In said S4, The following standards are used to determine whether the fuel tank's anti-explosion performance is qualified: If the tank does not crack during the continuous pressurization process and the maximum expansion displacement Δd is monitored max Satisfy the following formula: Δd max ≤Δd allow Where Δd allow is the preset allowed deformation threshold; It is determined that the anti-combustion and explosion performance meets the requirements.

7. A transformer oil tank explosion proof equivalent test method according to claim 1, characterized in that: In S3, the consistency of mechanical behavior of different parts is analyzed based on the Pearson correlation coefficient between each measuring point: If the Pearson correlation coefficient between the two measuring points is greater than 0.7, it is determined that the mechanical properties of the points on both sides of the fuel tank are consistent and the expansion characteristics under combustion and explosion conditions are consistent; If the Pearson correlation coefficient between two measuring points is less than 0.7, it is determined that there are certain differences in the mechanical properties at the points on both sides of the fuel tank, and there are significant differences in deformation under combustion and explosion.

8. A transformer oil tank explosion proof equivalent test device, characterized in that: It includes a pressurizing device, a data acquisition system, a signal processing module and a protective fence; The boosting device is connected to the transformer oil tank through a pipeline and is used to continuously pressurize the oil tank after the liquid is injected into the oil tank to increase the pressure to the target pressure; an oil filling valve is installed on the pipeline; The data acquisition is used to synchronously collect the internal pressure and expansion displacement of the fuel tank in real time; The signal processing module is used to perform correlation analysis and frequency domain characteristic extraction on the collected internal pressure and expansion displacement of the fuel tank, and obtain analytical expressions for the expansion displacement and pressure increment, consistency of mechanical behavior between measurement points, and anti-explosion performance.

9. A transformer oil tank explosion proof equivalent test device according to claim 8, characterized in that: The data acquisition system includes several pressure sensors, several laser rangefinders and several high-speed cameras. The pressure sensors are used to collect the internal pressure of each measuring point in the fuel tank in real time, the laser rangefinders are used to measure the expansion displacement of each measuring point in real time, and the high-speed cameras are used to monitor the images of weak parts of the fuel tank in real time.

10. A transformer oil tank explosion proof equivalent test device according to claim 9, characterized in that: The pressure sensors are arranged at the top of the oil tank, the center of the side wall, the reinforcing iron and the weld joints.

Images