A method for real-time verification of the metering performance of a natural gas flow standard device

Abstract

The application discloses a kind of natural gas flow standard device's measurement performance real-time checking method, it is related to natural gas flow measurement field, it is proposed that a kind of method can be according to dynamic state parameter constantly adjust and summarize checking data, can different standard device combination under comparative state data and natural gas under different checking system under state data, calculate the flow error of checking system relative to the flowmeter to be examined, establish measurement performance real-time checking mapping relationship database and measurement performance abnormality disposal database, provide guidance and error processing data comparison for different working conditions of natural gas checking.Can adapt to the real-time checking of natural gas flow standard device measurement performance under a variety of conditions and circumstances, achieve the purpose of reducing error, ensure that customer flowmeter is accurate and reliable each time flowmeter calibration.

Description

Technical Field

[0001] This invention relates to the field of natural gas flow measurement, and in particular to a method for real-time verification of the metering performance of a flow standard device for natural gas. Background Technology

[0002] With the large volume of natural gas trade transactions, the rapid development of instrumentation technology, and the implementation and updating of natural gas energy measurement methods in my country, the accuracy class of natural gas flowmeter calibration has been upgraded from the original 1.0 class to 0.5 class to ensure fairness and impartiality for both parties in trade transactions, meeting the urgent needs of market development. Currently, the uncertainty of the first domestically established standard device capable of calibrating 0.5 class flowmeters is 0.16%–0.19%.

[0003] Flow standard devices for natural gas, especially those based on combined sonic nozzles, have begun to adapt to the accuracy class of 0.5 natural gas flow meters due to the reduced uncertainty of primary flow standard devices in the traceability chain and the improved performance of instruments.

[0004] However, the metering performance of the aforementioned flow standard devices for natural gas is not stable. During long-term operation, they are affected by various subjective and objective factors, such as the model of the main standard and its associated pressure transformers, temperature variations, process installation conditions, and environmental conditions (whether valves leak, temperature differences between inside and outside the pipeline). The cumulative effect of these multiple influencing factors over a long period can drastically increase the overall impact, easily leading to larger errors during the calibration of 0.5-class flow meters.

[0005] Existing technical means to solve the above problems include:

[0006] 1. Use flow meters with different operating principles in series and set a certain difference limit for on-site verification;

[0007] 2. Regularly conduct inter-laboratory comparisons using transfer standards (comparison components) to maintain the metrological performance of the standards;

[0008] 3. Periodically conduct exchange experiments to test the differences in metering performance between nozzles with different sonic speeds;

[0009] 4. Use multiple chromatographic analyzers to compare and verify the gas chromatographic parameters.

[0010] Existing methods essentially reduce verification errors by increasing testing and comparative experiments. They cannot verify the working status of the flowmeter under test in real time when the standard device is calibrating, nor can they establish methods to obtain accurate difference limits. In practical use, the operation is often more complex, and the improvement in verification accuracy is limited. They are only suitable for single verifications and cannot guarantee the accuracy of long-term dynamic verification. Therefore, there is an urgent need for a technology that can verify metrological performance in real time and prevent and control quality risks in flowmeter calibration. Summary of the Invention

[0011] This invention addresses the problem that changes in time and state parameters of natural gas flow standard devices lead to continuously changing verification errors, resulting in reduced accuracy of verification results. It proposes a method that can continuously adjust and summarize verification data based on dynamic state parameters. This method can establish dynamic parameter and error databases for different standard devices to adapt to real-time verification of the metering performance of natural gas flow standard devices under various conditions, thereby reducing errors and ensuring accurate and reliable calibration of each customer's flow meter.

[0012] This invention is achieved through the following technical solution:

[0013] A method for real-time verification of the metering performance of a flow standard device for natural gas includes the following steps:

[0014] S1. Establish a verification system covering the flow and pressure range of flow standard devices, which includes multiple verification flow meters;

[0015] S2. Obtain status data of the flow meter under test, the flow standard device, and the verification system under different status parameters;

[0016] S3. By comparing the state data under different state parameters, determine the volumetric flow rate indication error and energy flow rate indication error of the flow standard device and the verification system relative to the flow meter under test, and use them to establish a correspondence table between indication error and state parameters;

[0017] S4. Based on the volumetric flow rate indication error and energy flow rate indication error of the flow rate standard device and the verification system, record the status data corresponding to different error data, and establish a real-time verification mapping relationship library of the metering performance of the flow rate standard device and the verification system.

[0018] S5. Based on the real-time verification mapping relationship database of metering performance, determine the volumetric flow rate deviation control limit and energy flow rate deviation control limit of the flow standard device relative to the verification system, and establish a database for handling abnormal metering performance of the flow standard device;

[0019] S6. Based on the real-time verification mapping relationship database and the metering performance anomaly handling database, and combined with the status parameters at each verification, select the optimal combination of the flow standard device to achieve the target operating conditions, and determine the performance status of the natural gas flow standard device in real time.

[0020] The expansion of natural gas demand has led to more frequent and larger natural gas transactions. The accuracy class of 0.5 natural gas flow meters requires higher precision in measuring natural gas flow. Therefore, it is necessary to obtain status data on natural gas and related metering equipment. While the installation of multiple data devices improves flow measurement, the errors in the measurement of various devices and status data will accumulate, reducing the accuracy of natural gas flow measurement. The actual metering environment varies under different conditions, and the parameters after the equipment group are also quite different.

[0021] In step S1, the flow meter is a device that records the flow rate of natural gas under specific conditions. The principle of the natural gas flow standard device is similar to that of the water flow standard device. It can be used to calibrate, test, prototype, and provide technical services for parameters such as the flow rate of the natural gas flow meter. In order to ensure the collection of status data under various conditions, the flow rate and pressure range of the verification system formed by combining multiple meters during natural gas transportation should at least cover the flow rate and pressure range of the flow standard device.

[0022] Step S2 includes the following steps:

[0023] S21. Obtain raw state data of the natural gas at the flow meter under test, mainly in terms of pressure, temperature, volumetric flow rate, and energy flow rate;

[0024] S22. Obtain comparative state data of the target natural gas at the flow standard device under different state parameters, including combination mode, pressure point, and flow point conditions;

[0025] S23. Obtain the comprehensive status data of natural gas in the entire system under different status parameters by the verification system.

[0026] In step S2, the original status data is a single set of data obtained from the verification of each flow meter, the comparative status data is multiple sets of data obtained from different combinations of various flow standard devices for mutual comparison, and the comprehensive status data is comprehensive data obtained from detection under different verification systems.

[0027] The raw state data includes pressure, temperature, volumetric flow rate, and energy flow rate. The comparative state data and comprehensive state data also include the combination of flow standard devices, which should also be recorded to facilitate the establishment of a complete database in subsequent steps.

[0028] The volumetric flow rate indication error and energy flow rate indication error mentioned in step S3 are derived from the difference between the comparative state data and the comprehensive state data mentioned in step S2 above. The recording and comparison of the comprehensive state data can be used to select and recommend the most suitable combination of verification systems under different scenarios and environmental conditions. The recording and comparison of the comparative state data can be used to find the error value when there are differences in certain conditions, so as to find the parameters or environmental conditions that cause the error.

[0029] The main body of the real-time verification mapping relationship library for metering performance in step S4 is a relationship library that reflects the volumetric flow rate deviation and energy flow rate deviation of the flow standard device relative to the verification system based on the target natural gas pressure and flow rate.

[0030] The metering performance anomaly handling database mentioned in step S5 is used to record the status parameters corresponding to data anomalies when metering deviations are categorized. After the establishment of the metering performance real-time verification mapping database and the metering performance anomaly handling database is completed, the optimal combination of target operating conditions can be selected by comparing the database during each verification. This allows for real-time determination of the performance status of the natural gas flow standard device, maximizing the accuracy of the error, establishing the most suitable verification method, preventing and controlling quality risks in flow meter calibration, and ensuring the accuracy and reliability of each flow meter calibration for customers.

[0031] Furthermore, the real-time verification mapping database for metering performance includes a dotted distribution map with natural gas flow rate as the horizontal axis and the volumetric flow rate deviation or energy flow rate deviation of the flow rate standard device relative to the verification system as the vertical axis.

[0032] Furthermore, the process of determining the volumetric flow rate deviation control limit and energy flow rate deviation control limit of the flow rate standard device relative to the verification system based on the real-time verification mapping relationship database is as follows:

[0033] Based on the basic data of the real-time verification mapping relationship database of the flow standard device and the verification system, a pattern recognition feature model is established using the basic data to identify outliers in the data points within the boundary.

[0034] A dynamic control model is established using the points within the boundary to obtain the metering deviation control limit between the flow standard device and the verification flow meter. This metering deviation control limit is used to establish a database for handling abnormal metering performance of the flow standard device.

[0035] Preferably, the statistical process control method is implemented using a mean-standard deviation control chart.

[0036] Furthermore, the metering performance anomaly handling database includes classified records of the types of the main standard device and matching voltage transformer of the flow standard device, as well as process installation conditions and environmental conditions, under abnormal metering deviation data conditions.

[0037] Furthermore, the process by which the flow standard device achieves the optimal combination of target operating conditions and determines the metering performance status of the natural gas flow standard device in real time is as follows:

[0038] Based on the real-time verification mapping relationship library and the abnormal handling database of metrological performance, select the best combination of the target working conditions and the metrological deviation control limit;

[0039] The flow standard device is used to verify the metering performance of the flow meter under test by comparing real-time parameters. Data that exceeds the metering deviation control limit is selected, recorded, and disposal suggestions are given.

[0040] Furthermore, the flow rate standard device flow pressure range verification system employs different numbers of single or multiple types of verification flow meters;

[0041] Furthermore, the flow rate standard device flow pressure range verification system includes:

[0042] The repeatability of the flow meter was found to be less than 0.05%.

[0043] The coverage area for natural gas flow is 5m 3 / h~8000m 3 / h;

[0044] The pressure range is 0.4 MPa to 10 MPa;

[0045] Furthermore, in step S1, the state parameters of the target natural gas include the combination of various pressure points, flow rate points, and flow rate standard devices. The comparative state data and comprehensive state data of the target natural gas include natural gas volumetric flow rate, energy flow rate, pressure, and temperature.

[0046] Compared with the prior art, the beneficial effects of the technical solution provided by the embodiments of the present invention are as follows:

[0047] By comparing data from different combinations of standard devices and under different natural gas state parameters, a real-time verification mapping database for metering performance and a database for handling metering performance anomalies can be established. The optimal combination of the flow standard devices to achieve different target operating conditions can be selected and recommended, and the metering performance status of the natural gas flow standard devices can be determined in real time. This ensures that the standard devices maintain a high level of confidence in their verification or calibration, and that the values ​​of the natural gas flow standard devices are accurately transmitted to the 0.5-grade flowmeter under test, thereby preventing and controlling quality risks in flowmeter verification. Attached Figure Description

[0048] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0049] Figure 1 This is a flowchart of a method for real-time verification of the metering performance of a flow standard device for natural gas, according to the present invention.

[0050] Figure 2 This is a detailed flowchart of step S2 in the present invention;

[0051] Figure 3 This is a detailed flowchart of step S5 in the present invention;

[0052] Figure 4 This is a diagram showing the relative standard flow rate deviation of the turbine working table under the optimal combination of nozzle and turbine working table in this invention.

[0053] Figure 5 This is a distribution diagram showing the influence of nozzle differential pressure variation on the relative standard flow deviation of the turbine working gauge in this invention. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0055] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known structures, circuits, materials, or methods have not been specifically described in order to avoid obscuring the invention.

[0056] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. Moreover, those skilled in the art will understand that the illustrations provided herein are for illustrative purposes and are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0057] In the description of this invention, the terms "front", "rear", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0058] Example

[0059] A method for real-time verification of the metering performance of a flow standard device for natural gas, such as... Figure 1 As shown, it includes the following steps:

[0060] S1. Establish a verification system covering the flow and pressure range of flow standard devices, which includes multiple verification flow meters;

[0061] S2. Obtain status data of the flow meter under test, the flow standard device, and the verification system under different status parameters;

[0062] S3. By comparing the state data under different state parameters, determine the volumetric flow rate indication error and energy flow rate indication error of the flow standard device and the verification system relative to the flow meter under test, and use them to establish a correspondence table between indication error and state parameters;

[0063] S4. Based on the volumetric flow rate indication error and energy flow rate indication error of the flow rate standard device and the verification system, record the status data corresponding to different error data, and establish a real-time verification mapping relationship library of the metering performance of the flow rate standard device and the verification system.

[0064] S5. Based on the real-time verification mapping relationship database of metering performance, determine the volumetric flow rate deviation control limit and energy flow rate deviation control limit of the flow standard device relative to the verification system, and establish a database for handling abnormal metering performance of the flow standard device;

[0065] S6. Based on the real-time verification mapping relationship database and the metering performance anomaly handling database, and combined with the status parameters at each verification, select the optimal combination of the flow standard device to achieve the target operating conditions, and determine the performance status of the natural gas flow standard device in real time.

[0066] The standard device verification method described in this embodiment is mainly based on existing process equipment and data acquisition and evaluation systems. Within their respective process zones and flow ranges, it implements various verification methods, including one-to-one verification, many-to-one verification, many-to-many verification, and total quantity verification. It monitors six technical indicators—natural gas calorific value fluctuation rate, pressure-temperature stability coefficient, nozzle-to-nozzle temperature difference, nozzle differential pressure, turbine working standard table relative standard volume, and energy flow deviation and repeatability—to achieve error monitoring. It primarily obtains flow deviation, establishes a mapping relationship library between flow and deviation, and sets control limits for flow deviation, i.e., the maximum allowable error range during the verification process. It records and summarizes error data exceeding this range for comparison in subsequent verification processes.

[0067] First, use a standard device to test the repeatability and reproducibility of the verification component at multiple flow points within its range. Establish a database of instrument coefficients for each flow point of the standard device and the verification flowmeter. Then, apply the standard to verify the flowmeter under test and record the data from the standard device and the verification flowmeter. Analyze and determine whether the current verification data of the flowmeter under test is valid. If it exceeds the target, the verification should be stopped and a self-check should be carried out.

[0068] Step S1 involves establishing a verification system covering the entire flow and pressure range of the flow standard device through a combination of multiple verification flow meters. This verification system can employ one or more verification flow meters, or one or more types of verification flow meters. Any combination of types and quantities can provide more sufficient data and comparison groups for the subsequent database establishment.

[0069] Furthermore, in the flow rate and pressure range verification system of the aforementioned flow rate standard device, the repeatability of the verification flow meter is less than 0.05%; covering a natural gas flow rate range of 5m³. 3 / h~8000m 3 / h, pressure range is 0.4MPa~10MPa.

[0070] The control indicators for real-time verification of the metering performance of the natural gas flow standard device involve six items, including the fluctuation rate of natural gas calorific value, pressure and temperature weighting coefficient, temperature difference between nozzles, nozzle differential pressure, repeatability of turbine working standard meter relative to standard volumetric flow rate, and deviation of turbine working standard meter relative to standard volumetric flow rate.

[0071] Among them, the natural gas calorific value fluctuation rate control index can effectively reflect the repeated exceedance of natural gas composition. The relative deviation of the combined turbine working standard table from the standard volumetric flow rate has a certain change. Therefore, the preferred natural gas calorific value fluctuation rate early warning index is 0.05%; the control index is 0.08%.

[0072] Volatility of high heating value of natural gas = (high heating value of natural gas - average high heating value of natural gas) / average high heating value of natural gas.

[0073] The preferred warning index for the pressure and temperature weighting coefficients is 1.000 to 1.012; the preferred control index is 1.000 to 1.018.

[0074] The preferred warning index for the temperature difference between nozzles is -0.3℃ to 0.3℃; the preferred control index is -0.5℃ to 0.5℃.

[0075] The preferred warning index for the repeatability of the turbine operating standard table relative to the standard volumetric flow rate is 0.04%; the preferred control index is 0.06%.

[0076] Among them, such as Figure 2 As shown, step S2 includes the following steps:

[0077] S21. Obtain raw state data of the natural gas at the flow meter under test, mainly in terms of pressure, temperature, volumetric flow rate, and energy flow rate;

[0078] S22. Obtain comparative state data of the target natural gas at the flow standard device under different state parameters, including combination mode, pressure point, and flow point conditions;

[0079] S23. Obtain the comprehensive status data of natural gas in the entire system under different status parameters by the verification system.

[0080] In step S2, the original status data is a single set of data obtained from the verification of each flow meter, the comparative status data is multiple sets of data obtained from different combinations of various flow standard devices for mutual comparison, and the comprehensive status data is comprehensive data obtained from detection under different verification systems.

[0081] The raw state data includes pressure, temperature, volumetric flow rate, and energy flow rate. The comparative state data and comprehensive state data also include the combination of flow standard devices, which should also be recorded to facilitate the establishment of a complete database in subsequent steps.

[0082] In step S3, the volumetric flow rate indication error and energy flow rate indication error are derived from the difference between the comparative state data and the comprehensive state data mentioned in step S2 above. Recording and comparing the comprehensive state data can be used to select and recommend the most suitable verification system combination under different scenarios and environmental conditions. Recording and comparing the comparative state data can be used to identify the error values ​​when certain conditions differ, in order to find the parameters or environmental conditions that cause the errors.

[0083] Step S4 involves determining the real-time verification mapping relationship library of the metering performance of the flow standard device and the verification system based on the volumetric flow rate indication error, energy flow rate indication error, and state parameters (pressure, flow rate, temperature, and combination method) of the flow standard device and the verification system.

[0084] This real-time verification mapping database for metering performance is a point-based distribution chart with natural gas flow rate as the x-axis and the volumetric flow rate deviation or energy flow rate deviation of the flow rate standard device relative to the verification system as the y-axis, such as... Figure 4 The point distribution map of volumetric flow rate and relative deviation is obtained under the optimal combination of nozzle and turbine working table, including maximum, minimum and average values.

[0085] In this embodiment, the nozzle differential pressure of 40 kPa is used as a variable, such as Figure 5 As shown, the distribution diagram of the relative standard flow deviation of the turbine working gauge under different nozzle differential pressures can be obtained. When the flow rate is 32m... 3 / h~1280m 3 When the nozzle differential pressure is greater than 40 kPa, the flow deviation between the working standard gauge and the working gauge will increase significantly. As the nozzle differential pressure increases, the average value of the relative deviation under different flow rates begins to approach 0.1%. Therefore, the early warning index of the nozzle differential pressure is preferably 40 kPa, and the control index is preferably 60 kPa.

[0086] Step S5 as follows Figure 3 As shown, the steps may include the following:

[0087] S51. Based on a large amount of basic data from the real-time verification mapping relationship database of the flow standard device and the verification system, a pattern recognition feature model is established using this basic data. The pattern recognition feature model uses decision theory and neural network technology to identify abnormal patterns in the process.

[0088] S52. Use basic data to establish a pattern recognition feature model and identify outliers in the data points within the boundary.

[0089] S53. For the points within the boundary, establish a dynamic control model using the statistical process control (SPC) method to obtain the metering deviation control limit between the flow standard device and the verification flow meter;

[0090] S54. The statistical process control method described above is implemented using a mean-standard deviation control chart or a Z-value control chart;

[0091] S55. Based on the above control chart, establish a database for handling abnormalities in the metering performance of flow standard devices.

[0092] The flow standard device metering performance anomaly handling database, which categorizes and records abnormal metering deviation data, establishes a detection and handling knowledge base including the main standard device of the flow standard device, its matching pressure transformer, temperature transformer, process installation conditions, and environmental conditions. If the metering deviation data is consistently below the average deviation, it will prompt that the environmental conditions, process valves, and matching pressure and temperature transformer data should be checked for correctness.

[0093] In this step, based on the standard flow deviation distribution map obtained from S4, the flow rate from 32m³ can be obtained. 3 / h~5115m 3 The optimal nozzle and turbine operating standard combination table for 139 different flow points per hour. Figure 4 Therefore, at a flow rate of 1100m 3 / h~5115m 3 At a flow rate of 32 m³ / h, the turbine operating gauge's flow deviation relative to the standard ranges from -0.10% to 0.14%. 3 / h~1100m 3 At a flow rate of / h, the flow deviation of the turbine working gauge relative to the standard should be controlled within the range of -0.20% to 0.20%. Therefore, the control limit table for the turbine working gauge's relative standard volumetric flow rate deviation can be obtained:

[0094]

[0095] The relative deviation control limits and warning limits corresponding to different flow segments are recorded as standard values ​​and are part of the metering performance anomaly handling database. This database is used to quickly filter and identify state parameters that exceed control limits. The metering performance anomaly handling database is a dynamic database that can be updated in real time after each verification.

[0096] Step S6 involves selecting the optimal combination of the flow standard device to achieve the target operating conditions based on the real-time verification mapping relationship database and the flow standard device anomaly handling database, combined with the status parameters at each verification, and determining the flow standard device's flow standard device's flow performance status in real time.

[0097] The intelligent push function of the flow standard device can realize the optimal combination of target operating conditions and the metering deviation control limit. By comparing parameters in real time, the flow standard device can determine the metering performance status of the flow meter under test. If the metering deviation control limit is exceeded, the corresponding status data can be recorded in real time. Combined with other data in the metering performance anomaly handling database, handling suggestions can be obtained to increase the verification accuracy and reduce the error.

[0098] The real-time verification method for the metering performance of a flow standard device for natural gas provided in this embodiment of the invention is applicable to the real-time verification of the metering performance of gas flow standards from 0.4MPa to 10MPa (for example, it can be 0.4MPa, 1.0MPa, 2.0MPa, 3.0MPa, 4.0MPa, 5.0MPa, 6.0MPa, 7.0MPa, 8.0MPa, 9.0MPa, 10.0MPa, etc.).

[0099] In summary, the real-time verification method for the metering performance of a natural gas flow standard device provided in this embodiment of the invention can verify the metering performance of the natural gas flow standard device in real time under conditions of 0.4MPa to 10MPa, obtain the optimal combination of the flow standard device to achieve the target operating conditions, and determine the metering performance status of the natural gas flow standard device in real time. It can ensure that the standard device maintains a verification or calibration state with good confidence, ensure that the measurement value of the natural gas flow standard device is accurately transmitted to the 0.5-grade flow meter under test, and can also record abnormal data found after each verification and update the metering performance anomaly handling database in real time.

[0100] All the above-mentioned optional technical solutions can be combined in any way to form the optional embodiments of this disclosure, and will not be described in detail here. The specific embodiments described above have further explained the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for real-time verification of the metering performance of a natural gas flow standard device, characterized in that, Includes the following steps: S1. Establish a verification system covering the flow and pressure range of flow standard devices, which includes multiple verification flow meters; S2. Acquire status data of the flow meter under test, the flow standard device, and the verification system under different status parameters; S3. By comparing the state data under different state parameters, determine the volumetric flow rate indication error and energy flow rate indication error of the flow standard device and the verification system relative to the flow meter under test, and use them to establish a correspondence table between indication error and state parameters; S4. Based on the volumetric flow rate indication error and energy flow rate indication error between the flow rate standard device and the verification system, record the status data corresponding to different error data, and establish a real-time verification mapping relationship library for the metering performance between the flow rate standard device and the verification system. The real-time verification mapping relationship library for the metering performance includes a dot distribution map with natural gas flow rate as the horizontal axis and the volumetric flow rate deviation or energy flow rate deviation of the flow rate standard device relative to the verification system as the vertical axis. S5. Based on the real-time verification mapping relationship database of metering performance, determine the volumetric flow rate deviation control limit and energy flow rate deviation control limit of the flow standard device relative to the verification system, and establish a metering performance anomaly handling database for the flow standard device. The metering performance anomaly handling database includes the types of the main standard device and matching voltage transformer of the flow standard device, as well as the process installation conditions and environmental conditions, under the condition of abnormal metering deviation data. S6. Based on the real-time verification mapping relationship database and the metering performance anomaly handling database, and combined with the status parameters at each verification, select the optimal combination of the flow standard device to achieve the target operating conditions, and determine the performance status of the natural gas flow standard device in real time.

2. The method for real-time verification of the metering performance of a natural gas flow standard device according to claim 1, characterized in that, The process of determining the volumetric flow rate deviation control limit and energy flow rate deviation control limit of the flow standard device relative to the verification system based on the real-time verification mapping relationship database of the metering performance is as follows: Based on the basic data of the real-time verification mapping relationship database of the flow standard device and the verification system, a pattern recognition feature model is established using the basic data to identify outliers in the data points within the boundary. For the points within the boundary, a dynamic control model is established using statistical process control methods to obtain the metering deviation control limit between the flow standard device and the verification flow meter. This metering deviation control limit is used to establish a database for handling abnormal metering performance of the flow standard device.

3. The method for real-time verification of the metering performance of a natural gas flow standard device according to claim 2, characterized in that, The statistical process control method is implemented through a mean-standard deviation control chart.

4. The method for real-time verification of the metering performance of a natural gas flow standard device according to claim 1, characterized in that, The process by which the flow standard device achieves the optimal combination of target operating conditions and determines the metering performance status of the natural gas flow standard device in real time is as follows: Based on the real-time verification mapping relationship library and the abnormal handling database of metrological performance, select the best combination of the target working conditions and the metrological deviation control limit; The flow standard device is used to assess the metering performance of the flow meter under test by comparing real-time parameters. Data that exceeds the metering deviation control limit is selected, recorded, and disposal suggestions are given.

5. The method for real-time verification of the metering performance of a natural gas flow standard device according to claim 1, characterized in that, The verification system covering the flow pressure range of the flow standard device uses a different number of single or multiple types of verification flow meters.

6. The method for real-time verification of the metering performance of a natural gas flow standard device according to claim 1, characterized in that, The verification system covering the flow rate and pressure range of the flow rate standard device includes: The repeatability of the flow meter was found to be less than 0.05%. The coverage area for natural gas flow is 5m 3 / h~8000m 3 / h; The pressure range is 0.4MPa to 10MPa.

7. The method for real-time verification of the metering performance of a natural gas flow standard device according to claim 1, characterized in that, Step S2 includes the following steps: S21. Obtain raw state data of the natural gas at the flow meter under test, mainly in terms of pressure, temperature, volumetric flow rate, and energy flow rate; S22. Obtain comparative state data of the target natural gas at the flow standard device under different state parameters, including combination mode, pressure point, and flow point conditions; S23. Obtain the comprehensive status data of natural gas in the entire system under different status parameters by the verification system.

8. The method for real-time verification of the metering performance of a natural gas flow standard device according to claim 7, characterized in that, The original status data is a single set of data obtained from the verification of each flow meter. The comparative status data is multiple sets of data obtained from various flow standard devices under different combinations for mutual comparison. The comprehensive status data is comprehensive data obtained from detection under different verification systems.

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