Measurement system and evaluation method for measurement uncertainty of pressure maintaining instrument

Abstract

The invention discloses a measurement system and evaluation method for measurement uncertainty of a pressure maintaining instrument, and the evaluation method comprises the steps: S1, carrying out the pipeline pressure detection based on the measurement system for the measurement uncertainty of the pressure maintaining instrument, and building a correction pressure drop measurement mathematical model; s2, performing multiple tests based on the measurement system for measuring uncertainty of the pressure maintaining instrument to obtain multiple groups of measurement data, observing the distribution rule of the measurement data, and determining random variables and probability distribution; s3, determining the number of tests based on a Monte Carlo algorithm; and S4, sampling based on probability distribution to obtain a corresponding number of input quantities, substituting the input quantities into the corrected pressure drop measurement mathematical model, and calculating to obtain uncertainty. The uncertainty measurement system and evaluation method provided by the invention are based on test equipment which is simpler and easier to implement and more scientific and reasonable theories and models, the result has better comparability, data exchange, sharing and integration are facilitated, and the accuracy is improved.

Description

Technical Field

[0001] The invention relates to the field of measurement technology, and in particular to a measurement system and an evaluation method for the measurement uncertainty of a pressure maintaining instrument. Background Art

[0002] The pressure tester is a precision instrument used in engineering tests. In the pipeline project acceptance test, it can accurately measure the pressure strength that the pipeline can withstand, determine whether there are small leaks in the pipeline, and ensure the safe operation of the pipeline under the designed pressure conditions. However, there are many factors in the measurement process of the pressure tester that lead to uncertainty in the measurement results. These uncertain factors are intertwined, resulting in a deviation between the pressure measurement results and the true value. In practical applications, if the measurement uncertainty of the pressure tester cannot be accurately evaluated, it may lead to misjudgment of the pipeline project acceptance.

[0003] In the existing technology, the measurement uncertainty assessment of the pressure maintaining instrument mostly relies on traditional methods. Not only is the operation process cumbersome and the accuracy is limited, but even in some complex working conditions, the traditional assessment method is difficult to fully consider the impact of various factors on the measurement results, resulting in a large deviation between the assessment results and the actual results. Summary of the invention

[0004] The present invention provides a measurement system and evaluation method for the measurement uncertainty of a pressure-maintaining instrument that is easier to implement and has higher accuracy, and can solve at least one of the above-mentioned technical problems.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A measuring system for measuring uncertainty of a pressure maintaining instrument, comprising a pressure maintaining instrument, an energy storage container, a test switch valve, an environmental test chamber, a high-pressure gas source unit and a cooling water source unit, wherein the energy storage container is connected to the pressure maintaining instrument via the test switch valve, and the pressure maintaining instrument is placed in the environmental test chamber;

[0007] The high-pressure gas source unit includes a gas source end, a pressure relief end, a gas source main valve, a pressure reducing valve, a pressure proportional valve, a pressure relief switch valve and a pressure sensor. The gas source main valve, the pressure reducing valve and the pressure proportional valve are sequentially connected to the energy storage container via the gas source end. The pressure relief switch valve is connected between the pressure relief end and the energy storage container. The pressure sensor is installed on the energy storage container. A gas pressure control loop is formed between the gas source end, the pressure relief end and the energy storage container.

[0008] The cooling water source unit includes a cooling water end, a recovery water end, a cooling water proportional valve, a temperature sensor and a heater. The cooling water proportional valve is connected to the energy storage container via the cooling water end. The temperature sensor and the heater are both installed on the energy storage container. The recovery water end is connected to the energy storage container. A temperature control loop is formed among the cooling water end, the recovery water end and the energy storage container.

[0009] Furthermore, in the air pressure control circuit, the air source end is connected to the air inlet of the energy storage container for inputting a high-pressure air source into the energy storage container, and the pressure relief end is connected to the air outlet of the energy storage container for discharging exhaust gas in the energy storage container.

[0010] Furthermore, in the temperature control loop, the cooling water end is connected to the water inlet of the energy storage container for inputting cooling water into the energy storage container, and the recovery water end is connected to the water outlet of the energy storage container for discharging the recovered waste water in the energy storage container.

[0011] Furthermore, it also includes a control unit, which is connected to the air pressure control circuit and the temperature control circuit, and is connected to the pressure proportional valve, the cooling water proportional valve, the temperature sensor and the pressure sensor. The control unit is used to obtain the real-time measurement value of the temperature sensor / pressure sensor, judge the difference between the current temperature / air pressure and the threshold, and regulate the opening of the cooling water proportional valve / pressure proportional valve based on the PID algorithm.

[0012] Furthermore, an environmental parameter control module is provided in the environmental test box, and the environmental parameter control module establishes a communication connection with the control unit for receiving instructions or feedback signals to adjust the air pressure, temperature and humidity in the environmental test box.

[0013] A method for evaluating the measurement uncertainty of a pressure-maintaining instrument is implemented by using a measurement system for the measurement uncertainty of the pressure-maintaining instrument, and comprises the following steps:

[0014] S1. Conduct pipeline pressure detection based on the measurement system of the pressure maintaining instrument with measurement uncertainty, and establish a mathematical model for correcting pressure drop measurement;

[0015] S2. Conduct multiple tests on the measurement system based on the measurement uncertainty of the pressure holding instrument to obtain multiple sets of measurement data, observe the distribution law of the measurement data, and determine the random variables and probability distribution;

[0016] S3, determining the number of tests based on a Monte Carlo algorithm, and then determining the number of sample values ​​input into a modified pressure drop measurement mathematical model;

[0017] S4. Based on the probability distribution sampling, a corresponding number of input quantities are obtained, substituted into the corrected pressure drop measurement mathematical model, a corresponding number of output quantities are obtained, and the uncertainty is calculated.

[0018] Furthermore, in S1, according to the ideal gas state equation:

[0019] PV=nRT

[0020] Where P is the natural gas pipeline pressure, in Pa, and V is the natural gas pipeline volume, in m 3 , T is the natural gas temperature, unit is K, n is the amount of gas substance, unit is mole, R is the molar gas constant, R = 8.314Pa*m 3 *mol -1 *K -1 ;

[0021] For the same pipeline without leakage, the following formula should be met under different temperature environments:

[0022]

[0023] Among them, P1 and P2 are pipeline pressures before and after the natural gas temperature changes, and T1 and T2 are natural gas temperatures before and after the changes;

[0024] At the same time, since P1=H1+B1, P2=H2+B2, the corrected pressure drop measurement mathematical model is:

[0025]

[0026] Among them, H1 and H2 are the pressure gauge readings before and after the natural gas temperature changes, respectively, in Pa, B1 and B2 are the atmospheric pressure gauge readings before and after the natural gas temperature changes, respectively, in Pa, t1 and t2 are the medium temperatures in the pipeline before and after the natural gas temperature changes, respectively, in K.

[0027] Furthermore, the S2 further includes:

[0028] S21. Before the test, close the test switch valve and open the main gas source valve. The high-pressure gas source passes through the pressure reducing valve along the test pipeline from the gas source end. The gas source in the energy storage container is reduced from a high-pressure state to a relatively stable low-pressure state. The control unit reads the real-time measurement value of the pressure sensor, determines the difference between the current air pressure value and the set threshold value, and uses the PID algorithm to adjust the opening of the pressure proportional valve. The pressure proportional valve and the pressure relief switch valve work together until the air pressure value in the energy storage container reaches the set threshold value, and then the main gas source valve is closed;

[0029] S22, the control unit reads the real-time measurement value of the temperature sensor, determines the difference between the current temperature value and the set threshold value, and uses the PID algorithm to adjust the opening of the cooling water proportional valve, and the cooling water proportional valve works in conjunction with the heater until the temperature value in the energy storage container reaches the set threshold value;

[0030] S23, the control unit regulates the environmental parameter regulation module until the environmental test box reaches the environmental conditions of constant atmospheric pressure, constant temperature and constant humidity;

[0031] S24, opening the test switch valve, and after the pressure sensor and the temperature sensor measure the air pressure and temperature in the energy storage container to be stable, the pressure maintaining instrument collects and records data at a certain sampling frequency and a certain collection time;

[0032] S25. Observe whether the distribution law of the collected measurement data conforms to the normal distribution with high in the middle, low on both sides and left-right symmetry. The probability density function of the normal distribution is:

[0033]

[0034] Here, u is the mean and σ is the standard deviation.

[0035] Furthermore, in S3, the formula for estimating the number of trials using the Monte Carlo algorithm is:

[0036]

[0037] Where M is the number of trials, z is the quantile of the standard normal distribution associated with the confidence level, σ is the standard deviation of the variable or statistic under study, and ε is the allowable error range.

[0038] Furthermore, the S4 further comprises:

[0039] S41, generating M random pressure measurement values ​​H before the temperature of the pressure holding instrument changes according to the probability density function of the measurement data and the MATLAB random generator 11 , H 12 ...H 1M Similarly, the remaining variables are obtained to obtain M random values, and the M random values ​​of all variables are substituted into the corrected pressure drop measurement mathematical model to obtain:

[0040]

[0041] Wherein, k = 1, 2, ... M;

[0042] S42, the obtained multiple sample values ​​Y k Arrange them in ascending order, that is, M sample values ​​of Y, Y1, Y2...Yk ;

[0043] S43, calculation results:

[0044] The average value of the output y for:

[0045]

[0046] The standard uncertainty u(y) of the output y is:

[0047]

[0048] The output y contains the following intervals:

[0049] [y (1-p)M / 2 ,y (1+p)M / 2 ]

[0050] Among them, (1-p)M / 2 represents the lower limit point of the inclusive interval, and (1+p)M / 2 represents the upper limit point of the inclusive interval;

[0051] Expanded uncertainty U of output quantity y y for:

[0052]

[0053] The corresponding coverage factor is:

[0054] k=U(Y) / u(Y).

[0055] The beneficial effects of the present invention are embodied in:

[0056] The new uncertainty measurement system and evaluation method provided by the present invention are based on simpler and easier to implement test equipment, as well as more scientific and reasonable theories and models. They can provide unified evaluation standards and specifications for the measurement results of different testing instruments or different laboratories, so that the results of measurements performed under the same or similar conditions have better comparability, facilitate data exchange, sharing and integration, and help improve accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The drawings described herein are used to provide further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute improper limitations on the present application.

[0058] Figure 1 Schematic diagram of the overall structure of the measurement system according to the embodiment of the present invention.

[0059] Figure 2 4 is a control structure block diagram of a measurement system according to an embodiment of the present invention.

[0060] Figure 3 It is a schematic diagram of the overall flow of the evaluation method according to an embodiment of the present invention.

[0061] Figure 4 It is a flowchart of the evaluation method according to an embodiment of the present invention.

[0062] Figure 5 It is a simulation diagram of random distribution of input variables of an embodiment of the present invention.

[0063] Figure 6 It is a probability density distribution simulation diagram of the output amount of the embodiment of the present invention.

[0064] Figure 7 It is a structural block diagram of a computer device according to an embodiment of the present invention.

[0065] The markings of the components in the accompanying drawings are:

[0066] 1. Air source main valve; 2. Pressure reducing valve; 3. Pressure proportional valve; 4. Pressure relief switch valve; 5. Energy storage container; 6. Test switch valve; 7. Pressure maintaining instrument; 8. Environmental test chamber; 9. Cooling water proportional valve; 10. Temperature sensor; 11. Pressure sensor; 12. Heater; 13. Environmental parameter control module. DETAILED DESCRIPTION

[0067] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. In the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0068] It should be noted that the meaning of "and / or" appearing in the full text includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, "multiple" means more than two. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0069] See also Figure 1The embodiment of the present invention provides a measurement system for measuring uncertainty of a pressure maintaining instrument, including a pressure maintaining instrument 7, an energy storage container 5, a test switch valve 6, an environmental test box 8, a high-pressure gas source unit and a cooling water source unit. The energy storage container 5 is connected to the pressure maintaining instrument 7 via the test switch valve 6, and the pressure maintaining instrument 7 is placed in the environmental test box 8;

[0070] The high-pressure gas source unit includes a gas source end, a pressure relief end, a gas source main valve 1, a pressure reducing valve 2, a pressure proportional valve 3, a pressure relief switch valve 4 and a pressure sensor 11. The gas source main valve 1, the pressure reducing valve 2 and the pressure proportional valve 3 are sequentially connected to the energy storage container 5 via the gas source end. The pressure relief switch valve 4 is connected between the pressure relief end and the energy storage container 5. The pressure sensor 11 is installed on the energy storage container 5. A gas pressure control loop is formed between the gas source end, the pressure relief end and the energy storage container 5.

[0071] The cooling water source unit includes a cooling water end, a recovery water end, a cooling water proportional valve 9, a temperature sensor 10 and a heater 12. The cooling water proportional valve 9 is connected to the energy storage container 5 via the cooling water end. The temperature sensor 10 and the heater 12 are both installed on the energy storage container 5. The recovery water end is connected to the energy storage container 5. A temperature control loop is formed between the cooling water end, the recovery water end and the energy storage container 5.

[0072] See also Figure 1 In this embodiment, in the air pressure control circuit, the air source end is connected to the air inlet of the energy storage container 5 for inputting a high-pressure air source into the energy storage container 5, and the pressure relief end is connected to the air outlet of the energy storage container 5 for discharging the exhaust gas in the energy storage container 5.

[0073] See also Figure 1 In this embodiment, in the temperature control loop, the cooling water end is connected to the water inlet of the energy storage container 5 for inputting cooling water into the energy storage container 5, and the recovery water end is connected to the water outlet of the energy storage container 5 for discharging the recovered waste water in the energy storage container 5.

[0074] See also Figure 1-Figure 2 In this embodiment, it also includes a control unit, which is connected to the air pressure control circuit and the temperature control circuit, and is connected to the pressure proportional valve 3, the cooling water proportional valve 9, the temperature sensor 10 and the pressure sensor 11. The control unit is used to obtain the real-time measurement value of the temperature sensor 10 / pressure sensor 11, determine the difference between the current temperature / air pressure and the threshold, and regulate the opening of the cooling water proportional valve 9 / pressure proportional valve 3 based on the PID algorithm.

[0075] In the present application, the control unit may use a controller or microcontroller with a built-in PID algorithm, which is an existing technology, and the specific style or model is not specifically limited in the present application.

[0076] See also Figure 1 In this embodiment, an environmental parameter control module 13 is provided in the environmental test box 8, and the environmental parameter control module 13 establishes a communication connection with the control unit for receiving instructions or feedback signals to adjust the air pressure, temperature and humidity in the environmental test box 8.

[0077] See also Figure 3-Figure 4 The embodiment of the present invention further provides a method for evaluating the measurement uncertainty of a pressure maintaining instrument, which is implemented by using the measurement system of the pressure maintaining instrument, and includes the following steps:

[0078] S1. Conduct pipeline pressure detection based on the measurement system of the pressure maintaining instrument with measurement uncertainty, and establish a mathematical model for correcting pressure drop measurement;

[0079] S2. Conduct multiple tests on the measurement system based on the measurement uncertainty of the pressure holding instrument to obtain multiple sets of measurement data, observe the distribution law of the measurement data, and determine the random variables and probability distribution;

[0080] S3, determining the number of tests based on a Monte Carlo algorithm, and then determining the number of sample values ​​input into a modified pressure drop measurement mathematical model;

[0081] S4. Based on the probability distribution sampling, a corresponding number of input quantities are obtained, substituted into the corrected pressure drop measurement mathematical model, a corresponding number of output quantities are obtained, and the uncertainty is calculated.

[0082] See also Figure 4 In this embodiment, in S1, according to the ideal gas state equation:

[0083] PV=nRT

[0084] Where P is the natural gas pipeline pressure, in Pa, and V is the natural gas pipeline volume, in m 3 , T is the natural gas temperature, unit is K, n is the amount of gas substance, unit is mole, R is the molar gas constant, R = 8.314Pa*m 3 *mol -1 *K -1 ;

[0085] For the same pipeline without leakage, the following formula should be met under different temperature environments:

[0086]

[0087] Among them, P1 and P2 are pipeline pressures before and after the natural gas temperature changes, and T1 and T2 are natural gas temperatures before and after the changes;

[0088] At the same time, since P1=H1+B1, P2=H2+B2, the corrected pressure drop measurement mathematical model is:

[0089]

[0090] Among them, H1 and H2 are the pressure gauge readings before and after the natural gas temperature changes, respectively, in Pa, B1 and B2 are the atmospheric pressure gauge readings before and after the natural gas temperature changes, respectively, in Pa, t1 and t2 are the medium temperatures in the pipeline before and after the natural gas temperature changes, respectively, in K.

[0091] See also Figure 4 In this embodiment, S2 further includes:

[0092] S21. Before the test, the test switch valve 6 is closed first, and the main gas source valve 1 is opened. The high-pressure gas source passes through the pressure reducing valve 2 along the test pipeline from the gas source end, and the gas source in the energy storage container 5 is reduced from the high-pressure state to a relatively stable low-pressure state. The control unit reads the real-time measurement value of the pressure sensor 11, determines the difference between the current air pressure value and the set threshold value, and uses the PID algorithm to adjust the opening of the pressure proportional valve 3. The pressure proportional valve 3 and the pressure relief switch valve 4 work together until the air pressure value in the energy storage container 5 reaches the set threshold value, and then the main gas source valve 1 is closed;

[0093] S22, the control unit reads the real-time measurement value of the temperature sensor 10, determines the difference between the current temperature value and the set threshold value, and uses the PID algorithm to adjust the opening of the cooling water proportional valve 9, and the cooling water proportional valve 9 works in conjunction with the heater 12 until the temperature value in the energy storage container 5 reaches the set threshold value;

[0094] S23, the control unit regulates the environmental parameter regulation module 13 until the environmental test box 8 reaches the environmental conditions of constant atmospheric pressure, constant temperature and constant humidity;

[0095] S24, open the test switch valve 6, and after the pressure sensor 11 and the temperature sensor 10 measure the air pressure and temperature in the energy storage container 5 to be stable, the pressure maintaining instrument 7 collects and records data at a certain sampling frequency and a certain collection time, generally at a frequency of 6 seconds each time and 1 minute of sampling;

[0096] S25. Observe whether the distribution law of the collected measurement data conforms to the normal distribution with high in the middle, low on both sides and left-right symmetry. The probability density function of the normal distribution is:

[0097]

[0098] Here, u is the mean and σ is the standard deviation.

[0099] The main reason why the measured data is normally distributed is that there are many small, independent random factors that affect the measurement results during the measurement process. For example, environmental factors, the accuracy limit of the instrument itself, etc. These factors combined make the measured values ​​fluctuate around the true value. From a probability perspective, most of the measured values ​​will be concentrated near the average value. The greater the deviation from the average value, the smaller the probability of occurrence.

[0100] See also Figure 4 In this embodiment, in S3, the formula for estimating the number of trials using the Monte Carlo algorithm is:

[0101]

[0102] Where M is the number of trials, z is the quantile of the standard normal distribution associated with the confidence level, σ is the standard deviation of the variable or statistic under study, and ε is the allowable error range.

[0103] See also Figure 4 In this embodiment, S4 further includes:

[0104] S41, generating M random values ​​H of the pressure measurement before the temperature of the pressure-maintaining instrument 7 is changed according to the probability density function of the measured data and the MATLAB random generator 11 , H 12 ...H 1M Similarly, the remaining variables are obtained to obtain M random values, and the M random values ​​of all variables are substituted into the corrected pressure drop measurement mathematical model to obtain:

[0105]

[0106] Wherein, k = 1, 2, ... M;

[0107] S42, the obtained multiple sample values ​​Y k Arrange them in ascending order, that is, M sample values ​​of Y, Y1, Y2...Y k ;

[0108] S43, calculation results:

[0109] The average value of the output y for:

[0110]

[0111] The standard uncertainty u(y) of the output y is:

[0112]

[0113] The output y contains the following intervals:

[0114] [y (1-p)M / 2 ,y (1+p)M / 2 ]

[0115] Among them, (1-p)M / 2 represents the lower limit point of the inclusive interval, and (1+p)M / 2 represents the upper limit point of the inclusive interval;

[0116] Expanded uncertainty U of output quantity y y for:

[0117]

[0118] The corresponding coverage factor is:

[0119] k=U(Y) / u(Y).

[0120] Below, this application will further explain this assessment method in conjunction with an actual case:

[0121] The corrected pressure drop measurement mathematical model Y is established to conduct a tightness test based on the measurement system of the pressure holding instrument measurement uncertainty:

[0122]

[0123] In the measurement system of the uncertainty of the pressure maintaining instrument, each component is tightly connected to ensure that there is no leakage point. The environmental conditions in the environmental test box 8 are controlled at a constant temperature of 6°C and a constant standard atmospheric pressure environment. At the same time, the gas source end uses compressed air as the medium, and the closed-loop system composed of the gas source main valve 1 and the pressure relief switch valve 4 is slowly pressurized in sections to increase the pipeline gas pressure to the set pressure value of 467Kpa. After stabilization, the gas source main valve 1 stops working and closes the test switch valve 6. The measurement reading value of the pressure maintaining instrument 7 is sampled every 6 seconds, and the sampling time lasts for 1 minute. The data is shown in Table 1 below:

[0124] Table 1 Measurement data of variables in state 1

[0125]

[0126] The arithmetic mean is:

[0127]

[0128] The standard deviation of a single experiment is:

[0129]

[0130]

[0131] It can be seen that the pipeline pressure measurement value H1 follows the normal distribution N1 (467000,571.5476 2 ), the pipeline temperature measurement value t1 follows the normal distribution N2(6,0.1155 2 ), the atmospheric pressure measurement value B1 follows the normal distribution N3(101332,51.3809 2 );

[0132] Under the condition that other conditions remain unchanged, the ambient temperature in the environmental test box 8 is slowly changed in stages until the temperature is stable at 2°C. At this time, the measurement reading of the pressure maintaining instrument 7 is sampled once every 6 seconds, and the sampling lasts for 1 minute. The data are shown in Table 2 below:

[0133] Table 2 Measurement data of variables in state 2

[0134]

[0135] Similarly, the settlement result can be obtained. The pipeline pressure measurement value H2 follows the normal distribution N3 (449370,758.7270 2 ), the pipeline temperature measurement value t2 follows the normal distribution N4(1.98,0.1317 2 ), the atmospheric pressure measurement value B2 follows the normal distribution N5(101299,67.5689 2 );

[0136] The confidence level p is 95%, and the relative error of the estimated value ε≤0.1%. According to the Monte Carlo algorithm, the formula for estimating the number of trials is:

[0137]

[0138] For p=95%, z is 1.95, and M is calculated to be 4*10 6 ;

[0139] The random generator of MATLAB is used to generate M random values ​​H of the pipeline pressure measurement before the temperature of the pressure maintaining instrument 7 is changed. 11 , H 12 …H 1M , and similarly, we can obtain M random values ​​of the remaining variables, such as Figure 5 As shown;

[0140] Substituting the M random values ​​of the input variables into the modified pressure drop measurement mathematical model yields:

[0141]

[0142] Wherein, k = 1, 2, ... M;

[0143] The multiple sample values ​​Yk Arrange them in ascending order, that is, M sample values ​​of Y, Y1, Y2...Y k , the calculation results are:

[0144] The average value of the output y for:

[0145]

[0146] The standard uncertainty u(y) of the output y is:

[0147]

[0148] The output y contains the following intervals:

[0149] [y (1-p)M / 2 ,y (1+p)M / 2 ]=[8486Pa,10737Pa]

[0150] Among them, the confidence level p is 95%, (1-p)M / 2 represents the lower limit of the included interval, and (1+p)M / 2 represents the upper limit of the included interval;

[0151] Expanded uncertainty U of output quantity y y for:

[0152]

[0153] The corresponding coverage factor is:

[0154]

[0155] The probability density distribution of the output is as follows: Figure 6 shown.

[0156] An embodiment of the present invention further provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the processor executes the steps of the above-mentioned method for evaluating the measurement uncertainty of a pressure maintaining instrument.

[0157] See also Figure 7 An embodiment of the present invention further provides a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the above-mentioned method for evaluating the measurement uncertainty of the pressure maintaining instrument.

[0158] The embodiment of the present invention further provides a computer program product comprising instructions, which, when executed on a computer, enables the computer to execute the steps of the above-mentioned method for evaluating the measurement uncertainty of a pressure maintaining instrument.

[0159] It is understandable that the system, device and storage medium provided in the embodiments of the present invention correspond to the method provided in the embodiments of the present invention, and the explanation, examples and beneficial effects of the relevant contents can refer to the corresponding parts in the above-mentioned method for evaluating the measurement uncertainty of the pressure maintaining instrument.

[0160] It should be noted that those skilled in the art can understand that all or part of the steps implemented in the embodiments of the present invention can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using hardware, it can be implemented in whole or in part in the form of purchasing standard parts or modified parts. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium may be a magnetic medium (eg, a floppy disk, a hard disk, a magnetic tape), an optical medium (eg, a DVD), or a semiconductor medium (eg, a solid state disk (SSD)).

[0161] In summary, the present invention aims at the deficiencies of the existing uncertainty assessment of pressure maintaining instruments, and provides a measurement system and assessment method for the uncertainty of pressure maintaining instruments, which helps users understand the credibility of the measured values ​​and provides a more reliable basis for pipeline inspection standards. Through a careful analysis of the sources of uncertainty, it is possible to discover weak links and potential problems that may exist in the measurement process, and then make targeted improvements and optimizations to improve the overall performance and stability of the measurement system, reduce the occurrence of errors, and ultimately improve the accuracy and reliability of the measurement results. Accurate uncertainty assessment helps to establish a more effective quality monitoring system, and monitor and trace the measurement process and results in real time. During the production process, quality fluctuations can be discovered in a timely manner and corresponding measures can be taken to make adjustments, ensuring the consistency and stability of product quality and meeting the requirements of quality management and quality assurance.

[0162] It should be understood that the examples and implementation modes described herein are for illustrative purposes only and are not intended to limit the present invention. Those skilled in the art may make various modifications or changes based on the examples and implementation modes. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A system for measuring the measurement uncertainty of a pressure maintaining instrument, comprising a pressure maintaining instrument (7), characterized in that: It also includes an energy storage container (5), a test switch valve (6), an environmental test box (8), a high-pressure gas source unit and a cooling water source unit. The energy storage container (5) is connected to the pressure maintaining device (7) via the test switch valve (6), and the pressure maintaining device (7) is placed in the environmental test box (8); The high-pressure gas source unit comprises a gas source end, a pressure relief end, a gas source main valve (1), a pressure reducing valve (2), a pressure proportional valve (3), a pressure relief switch valve (4) and a pressure sensor (11); the gas source main valve (1), the pressure reducing valve (2) and the pressure proportional valve (3) are sequentially connected to the energy storage container (5) via the gas source end; the pressure relief switch valve (4) is connected between the pressure relief end and the energy storage container (5); the pressure sensor (11) is installed on the energy storage container (5); and a gas pressure control circuit is formed between the gas source end, the pressure relief end and the energy storage container (5); The cooling water source unit comprises a cooling water end, a recovery water end, a cooling water proportional valve (9), a temperature sensor (10) and a heater (12); the cooling water proportional valve (9) is connected to the energy storage container (5) via the cooling water end; the temperature sensor (10) and the heater (12) are both installed on the energy storage container (5); the recovery water end is connected to the energy storage container (5); and a temperature control loop is formed between the cooling water end, the recovery water end and the energy storage container (5).

2. The measurement system for measuring the uncertainty of the pressure maintaining instrument according to claim 1, characterized in that: In the air pressure control circuit, the air source end is connected to the air inlet of the energy storage container (5) for inputting a high-pressure air source into the energy storage container (5), and the pressure relief end is connected to the air outlet of the energy storage container (5) for discharging waste gas in the energy storage container (5).

3. The measurement system for measuring the uncertainty of the pressure maintaining instrument according to claim 1, characterized in that: In the temperature control loop, the cooling water end is connected to the water inlet of the energy storage container (5) for inputting cooling water into the energy storage container (5), and the recovery water end is connected to the water outlet of the energy storage container (5) for discharging the recovered waste water in the energy storage container (5).

4. The measurement system for measuring the uncertainty of the pressure maintaining instrument according to claim 1, characterized in that: The invention also comprises a control unit, wherein the control unit is connected to the air pressure control circuit and the temperature control circuit, and is connected to the pressure proportional valve (3), the cooling water proportional valve (9), the temperature sensor (10) and the pressure sensor (11), and the control unit is used to obtain the real-time measurement value of the temperature sensor (10) / pressure sensor (11), determine the difference between the current temperature / air pressure and the threshold value, and regulate the opening of the cooling water proportional valve (9) / pressure proportional valve (3) based on the PID algorithm.

5. The measurement system for measuring the uncertainty of the pressure-maintaining instrument according to claim 4, characterized in that: An environmental parameter control module (13) is provided in the environmental test box (8), and the environmental parameter control module (13) establishes a communication connection with the control unit and is used to receive instructions or feedback signals to adjust the air pressure, temperature and humidity in the environmental test box (8).

6. A method for evaluating the measurement uncertainty of a pressure-maintaining instrument, implemented by using the measurement uncertainty measurement system of the pressure-maintaining instrument as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: S1. Conduct pipeline pressure detection based on the measurement system of the pressure maintaining instrument with measurement uncertainty, and establish a mathematical model for correcting pressure drop measurement; S2. Conduct multiple tests on the measurement system based on the measurement uncertainty of the pressure holding instrument to obtain multiple sets of measurement data, observe the distribution law of the measurement data, and determine the random variables and probability distribution; S3, determining the number of tests based on a Monte Carlo algorithm, and then determining the number of sample values ​​input into a modified pressure drop measurement mathematical model; S4. Based on the probability distribution sampling, a corresponding number of input quantities are obtained, substituted into the corrected pressure drop measurement mathematical model, a corresponding number of output quantities are obtained, and the uncertainty is calculated.

7. The method for evaluating the measurement uncertainty of a pressure maintaining instrument according to claim 6, characterized in that: In S1, according to the ideal gas state equation: PV=nRT Where P is the natural gas pipeline pressure, in Pa, and V is the natural gas pipeline volume, in m 3 , T is the natural gas temperature, unit is K, n is the amount of gas substance, unit is mole, R is the molar gas constant, R = 8.314Pa*m 3 *mol -1 *K -1 ; For the same pipeline without leakage, the following formula should be met under different temperature environments: Among them, P1 and P2 are pipeline pressures before and after the natural gas temperature changes, and T1 and T2 are natural gas temperatures before and after the changes; At the same time, since P1=H1+B1, P2=H2+B2, the corrected pressure drop measurement mathematical model is: Among them, H1 and H2 are the pressure gauge readings before and after the natural gas temperature changes, respectively, in Pa, B1 and B2 are the atmospheric pressure gauge readings before and after the natural gas temperature changes, respectively, in Pa, t1 and t2 are the medium temperatures in the pipeline before and after the natural gas temperature changes, respectively, in K.

8. The method for evaluating the measurement uncertainty of a pressure maintaining instrument according to claim 6, characterized in that: The S2 further comprises: S21. Before the test, the test switch valve (6) is closed first, and the main gas source valve (1) is opened. The high-pressure gas source passes through the pressure reducing valve (2) from the gas source end along the test pipeline, and the gas source in the energy storage container (5) is reduced from a high-pressure state to a relatively stable low-pressure state. The control unit reads the real-time measurement value of the pressure sensor (11), determines the difference between the current air pressure value and the set threshold value, and uses the PID algorithm to adjust the opening of the pressure proportional valve (3). The pressure proportional valve (3) and the pressure relief switch valve (4) work together until the air pressure value in the energy storage container (5) reaches the set threshold value, and then the main gas source valve (1) is closed; S22, the control unit reads the real-time measurement value of the temperature sensor (10), determines the difference between the current temperature value and the set threshold value, and uses the PID algorithm to adjust the opening of the cooling water proportional valve (9), wherein the cooling water proportional valve (9) and the heater (12) work together until the temperature value in the energy storage container (5) reaches the set threshold value; S23, the control unit regulates the environmental parameter regulation module (13) until the environmental test box (8) reaches environmental conditions of constant atmospheric pressure, constant temperature and constant humidity; S24, opening the test switch valve (6), and after the pressure sensor (11) and the temperature sensor (10) measure the air pressure value and the temperature value in the energy storage container (5) to be stable, the pressure maintaining instrument (7) collects and records data at a certain sampling frequency and a certain collection time; S25. Observe whether the distribution law of the collected measurement data conforms to the normal distribution with high in the middle, low on both sides and left-right symmetry. The probability density function of the normal distribution is: Here, u is the mean and σ is the standard deviation.

9. The method for evaluating the measurement uncertainty of a pressure maintaining instrument according to claim 6, characterized in that: In S3, the formula for estimating the number of trials using the Monte Carlo algorithm is: Where M is the number of trials, z is the quantile of the standard normal distribution associated with the confidence level, σ is the standard deviation of the variable or statistic under study, and ε is the allowable error range.

10. The method for evaluating the measurement uncertainty of a pressure maintaining instrument according to claim 6, characterized in that: The S4 further comprises: S41, generating M random values ​​H of the pressure measurement of the pressure holding instrument (7) before the temperature changes according to the probability density function of the measurement data and the MATLAB random generator 11 , H 12 ...H 1M Similarly, the remaining variables are obtained to obtain M random values, and the M random values ​​of all variables are substituted into the corrected pressure drop measurement mathematical model to obtain: Wherein, k = 1, 2, ... M; S42, the obtained multiple sample values ​​Y k Arrange them in ascending order, that is, M sample values ​​of Y, Y1, Y2...Y k ; S43, calculation results: The average value of the output y for: The standard uncertainty u(y) of the output y is: The output y contains the following intervals: [and (1-p)M / 2 ,and (1+p)M / 2 ] Among them, (1-p)M / 2 represents the lower limit point of the inclusive interval, and (1+p)M / 2 represents the upper limit point of the inclusive interval; Expanded uncertainty U of output quantity y y for: The corresponding coverage factor is: k=U(Y) / u(Y).

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