Method, terminal and system for correcting metering flow channel in NB (Narrow Band) remote ultrasonic gas meter

Abstract

The invention relates to a method, terminal and system for correcting a metering flow channel in an NB remote transmission ultrasonic gas meter, and the method comprises the steps: obtaining a plurality of pieces of first ultrasonic signal data in a first time period under the condition of zero flow; preliminarily judging whether the gas meter has a zero offset problem or not according to the first ultrasonic signal data; when the zero offset problem exists in the gas meter, obtaining a plurality of second ultrasonic signal data in a second time period to judge whether the time offset of the gas meter caused by the zero offset problem is a fixed value or not; and when the time deviation is a fixed value, the gas meter is corrected according to the first deviation curve and the second deviation curve, and a correction result is obtained. According to the gas meter, an accurate flow value can still be obtained when small-flow gas flows, and the problem that the measurement accuracy of the gas meter is low due to zero-flow time deviation measured only depending on a standard test environment is effectively solved.

Description

Technical Field

[0001] The present application relates to the technical field of flow zero bias correction, and in particular to a method, terminal and system for correcting a metering flow channel in an NB remote ultrasonic gas meter. Background Art

[0002] In the modern gas metering system, NB remote ultrasonic gas meter is gradually becoming the mainstream equipment in the field of gas metering due to its significant advantages such as high precision, no mechanical wear and remote data transmission. NB remote ultrasonic gas meter relies on NB-IoT Internet of Things technology to achieve remote and stable data transmission, and at the same time uses the propagation time difference of ultrasonic waves in gas to accurately measure the gas flow rate, and then accurately calculate the gas flow.

[0003] At present, the time difference method is the main way for NB remote ultrasonic gas meters to measure the gas flow in the flow channel. The core is to accurately calculate the gas flow through the upstream and downstream time of the ultrasonic wave flying in the flow channel. In the ideal static zero flow state, in theory, the upstream and downstream flight times should be completely equal, but in real scenarios, even if the user does not use gas, there will often still be a certain amount of gas or other gases remaining in the flow channel, and it is not in an absolute zero flow state. This situation will cause the upstream and downstream time of the ultrasonic wave to deviate, which will cause the gas meter to still measure a smaller flow value at zero flow, which is the so-called zero point offset (abbreviated as zero offset) problem.

[0004] In response to the above-mentioned zero bias problem, the traditional solution is usually to conduct a zero flow experiment in a standard test environment before the gas meter leaves the factory, thereby obtaining a zero flow time deviation value; and when the gas meter subsequently calculates the upstream and downstream flight time difference, the zero bias is corrected by directly subtracting the zero flow time deviation; however, due to the large difference between the actual application scenario of the gas meter and the standard test environment, the gas meter cannot simply rely on the zero flow time deviation determined in the standard test environment at the time of leaving the factory to achieve accurate measurement of small flow gas in other working environments such as temperature, pressure, and non-parallel installation of the internal transducer of the gas meter; therefore, relying solely on the zero flow time deviation measured at the time of leaving the factory for correction in non-standard environment scenarios will result in low actual measurement accuracy of the gas meter, which is far from meeting the high requirements for measurement accuracy of the gas meter in actual use. Summary of the invention

[0005] In order to improve the problem of low gas meter measurement accuracy caused by relying solely on the zero flow time deviation measured under the standard test environment at the factory for correction, the present application provides a method, terminal and system for calibrating the metering flow channel in an NB remote ultrasonic gas meter.

[0006] In a first aspect, the present application provides a method for calibrating a metering flow channel in an NB remote ultrasonic gas meter, which adopts the following technical solution: A method for calibrating a metering flow channel in a NB remote ultrasonic gas meter is applied to an ultrasonic gas meter, wherein the ultrasonic gas meter includes a flow sensor for detecting and obtaining ultrasonic signal data of an ultrasonic wave in a flow channel to be measured, each of the ultrasonic signal data includes a set of upstream flight time and downstream flight time, including: Under zero flow conditions, obtaining a plurality of first ultrasonic signal data within a preset first time period; Preliminarily determine whether the gas meter has a zero bias problem based on the first ultrasonic signal data; When the gas meter has a zero bias problem, obtaining a plurality of second ultrasonic signal data within a preset second time period; Obtaining a first offset curve according to the first ultrasonic signal data, and obtaining a second offset curve according to the second ultrasonic signal data, wherein the first offset curve and the second offset curve are used to reflect the continuous change of the difference between the upstream flight time and the downstream flight time in a corresponding time period; Obtaining an initial zero bias function according to the first offset curve and the second offset curve, wherein the initial zero bias function is used to calculate an approximate zero bias value of the gas meter in the first time period and the second time period; Determine whether the time deviation of the gas meter caused by the zero bias problem is a fixed value according to the approximate zero bias value; When the time deviation is a fixed value, obtaining a zero offset value for correction based on the first offset curve and the second offset curve; The difference between each group of upstream flight time and downstream flight time is corrected according to the correction zero bias value to obtain a correction result.

[0007] By adopting the above technical solution, under the condition of zero flow, a number of first ultrasonic signal data within the first time period are first obtained to make a preliminary judgment on whether the gas meter has a zero bias problem. This preliminary detection mechanism provides a prerequisite for subsequent precise calibration, avoids unnecessary complex processing of gas meters without zero bias problems, and can also promptly detect gas meters with zero bias problems, taking a critical first step in improving measurement accuracy. When it is determined that the gas meter has a zero bias problem, a number of second ultrasonic signal data in the second time period are further obtained, and combined with the first ultrasonic signal data to determine whether the time deviation caused by the zero bias problem is a fixed value. This step breaks through the limitation of the traditional method that only relies on a zero flow test before leaving the factory. In this way, it can accurately determine what kind of correction method needs to be selected later; When the time deviation is determined to be a fixed value, the gas meter is calibrated using the first ultrasonic signal data and the second ultrasonic signal data, which fully considers the complexity of the gas meter in the actual use scenario, and takes into account a series of interference factors that may affect the time deviation, such as temperature, pressure, and transducer installation conditions. A fixed time deviation obtained through comprehensive analysis and processing of multiple groups of data is used to uniformly indicate the impact of these interference factors. This avoids the situation where the single zero flow time deviation obtained under a standard test environment is still used for correction when there are multiple factors acting together on the time deviation of the gas meter, resulting in low measurement accuracy of the gas meter after correction. This comprehensively improves the measurement accuracy of the gas meter in actual use, while meeting the high requirements for gas meter measurement accuracy under small flow conditions, and overcomes the problem of low measurement accuracy of traditional calibration methods under non-standard environments.

[0008] In a specific implementation scheme, the first time period is composed of a plurality of initial acquisition cycles, each initial acquisition cycle in the first time period corresponds to a first ultrasonic signal data, and each first ultrasonic signal data specifically includes a set of first upstream flight time and first downstream flight time; the preliminary determination of whether the gas meter has a zero bias problem based on the first ultrasonic signal data includes: Calculating an average phase difference between each group of the first upstream flight time and the first downstream flight time; If the average phase difference value is zero, it is determined that the gas meter does not have a zero bias problem; If the average phase difference value exceeds the preset value fluctuation range, it is determined that the gas meter has an abnormal fault, and an alarm is triggered; If the average phase difference value is within the numerical fluctuation range, it is determined that the gas meter has a zero bias problem.

[0009] In a specific implementation scheme, the second time period is composed of a plurality of initial acquisition cycles, each initial acquisition cycle in the second time period corresponds to a second ultrasonic signal data, and each second ultrasonic signal data specifically includes a set of second upstream flight time and second downstream flight time; the first offset curve is obtained according to the first ultrasonic signal data, and the second offset curve is obtained according to the second ultrasonic signal data, including: Determine a plurality of first target acquisition cycles corresponding to the first time period according to all of the first upstream flight times, and determine a plurality of second target acquisition cycles corresponding to the second time period according to all of the second upstream flight times; A plurality of first time differences corresponding to each first target acquisition cycle are calculated based on the first upstream flight time and the first downstream flight time, and a plurality of second time differences corresponding to each second target acquisition cycle are calculated based on the second upstream flight time and the second downstream flight time, wherein the first time difference represents the difference between a certain group of the first upstream flight time and the first downstream flight time within the first time period; and the second time difference represents the difference between a certain group of the second upstream flight time and the second downstream flight time within the second time period; A first offset curve corresponding to the first time period is obtained based on all the first time differences, and a second offset curve corresponding to the second time period is obtained based on all the second time differences, wherein the first offset curve is specifically used to reflect the continuous change of the first time difference within the first time period, and the second offset curve is specifically used to reflect the continuous change of the second time difference within the second time period.

[0010] In a specific implementation scheme, the initial zero bias function is used to obtain an approximate zero bias value corresponding to each of the initial acquisition cycles according to the first time difference and the second time difference, and the approximate zero bias value is used to represent the actual bias value of the gas meter in the initial acquisition cycle; the calculation formula of the initial zero bias function is as follows: ; in, represents the initial zero bias function; represents the first offset curve; represents the second offset curve; The determining, according to the approximate zero offset value, whether the time offset caused by the zero offset problem of the gas meter is a fixed value comprises: Calculating an average zero bias of the initial zero bias function in the first time period or the second time period, the average zero bias being an average of all consecutive approximate zero bias values ​​on the initial zero bias function in the first time period or the second time period; Calculate the sum of the square errors between the approximate zero bias values ​​corresponding to all the initial acquisition cycles in the first time period or the second time period and the average zero bias; If the sum of the variances is less than or equal to a preset sum of the variances threshold, it is determined that the time deviation corresponding to the gas meter is a fixed value; If the sum of the variances is greater than the sum of the variances threshold, it is determined that the time deviation corresponding to the gas meter is not a fixed value.

[0011] In a specific implementation manner, determining a plurality of first target acquisition cycles corresponding to the first time period according to all the first upstream flight times comprises: determining a reference upstream flight time corresponding to the first time period from among all the first upstream flight times; Calculate a first phase difference between the reference upstream flight time and all other first upstream flight times; If the first phase difference is less than or equal to a preset phase difference threshold, the initial acquisition period corresponding to the first phase difference is used as the first target acquisition period.

[0012] In a second aspect, the present application provides a smart terminal, which adopts the following technical solution: An intelligent terminal comprises a memory and a processor, wherein the memory stores at least one instruction, at least one program, a code set or an instruction set, and the at least one instruction, at least one program, a code set or an instruction set is loaded and executed by the processor to implement the metering flow channel calibration method in the NB remote ultrasonic gas meter as described in the first aspect.

[0013] In the third aspect, the present application provides a NB remote ultrasonic gas meter internal metering flow channel calibration system, which adopts the following technical solution: A metering flow channel calibration system for an NB remote ultrasonic gas meter, comprising: A temperature sensor is used to measure the temperature of the gas in the flow channel to be metered; A pressure sensor is used to measure the gas pressure in the flow channel to be measured; The intelligent terminal as described in the second aspect is communicatively connected to the flow sensor, the temperature sensor and the pressure sensor, and is used to calibrate the ultrasonic gas meter according to the gas temperature, the gas pressure, the upstream flight time and the downstream flight time to obtain a calibration result.

[0014] In a fourth aspect, the present application provides a computer-readable storage medium, which adopts the following technical solution: A computer-readable storage medium, wherein at least one instruction, at least one program, code set or instruction set is stored in the readable storage medium, and the at least one instruction, at least one program, code set or instruction set is loaded and executed by a processor to implement the metering flow channel calibration method in a NB remote ultrasonic gas meter as described in the first aspect.

[0015] In summary, the present application includes at least one of the following beneficial technical effects: 1. This application provides a more comprehensive and accurate detection and correction scheme for zero bias problems of ultrasonic gas meters: in the case of zero flow, a simple first ultrasonic signal data is first used to preliminarily determine whether the gas meter has a zero bias problem; when a zero bias problem exists, the second ultrasonic signal data is added to perform a comparison and analysis of the two sets of data, thereby avoiding blind operation and effectively improving the correction efficiency; 2. When the time deviation is a fixed value, the correction zero deviation value is obtained based on the first and second offset curves, and the difference between the upstream and downstream flight times of the flow sensor is accurately corrected. This correction method can effectively deal with the different time deviations caused by the zero deviation problem of each gas meter, especially in the case of small flow gas circulation, which can significantly improve the measurement accuracy and make the measurement results of the gas meter in the actual complex environment closer to the true value, thus improving the problem of low measurement accuracy of the gas meter caused by only relying on the correction of the zero flow time deviation measured under the standard test environment at the factory; 3. This application overcomes the problem of inconsistent calibration standards due to differences between actual application scenarios (such as non-parallel installation of transducers, different flow channel structures, different temperatures, different pressures, etc.) and standard test environments, so that each gas meter can be accurately calibrated according to its own situation while excluding most possible interference factors (determining whether the time deviation is a fixed value), thereby achieving high-precision measurement of ultrasonic gas meters in various complex working environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of a metering flow channel calibration system in a NB remote ultrasonic gas meter according to an embodiment of the present application.

[0017] Figure 2 It is a flow chart of a method for calibrating a metering flow channel in a NB remote ultrasonic gas meter according to another embodiment of the present application.

[0018] Figure 3 is a schematic diagram of a first offset curve and a second offset curve according to another embodiment of the present application.

[0019] Figure 4 It is a schematic diagram of an initial zero bias function according to another embodiment of the present application.

[0020] Figure 5 It is a flowchart diagram of steps S700-S900 after determining whether the time deviation corresponding to the gas meter is a fixed value in S600 according to another embodiment of the present application. DETAILED DESCRIPTION

[0021] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0022] The following is a further detailed description of the embodiments of the method, terminal, and system for calibrating the metering flow channel in the NB remote ultrasonic gas meter of the present application in conjunction with all the drawings in the specification.

[0023] Reference Figure 1 An embodiment of the present application discloses a metering flow channel calibration system in an NB remote ultrasonic gas meter. The zero bias automatic calibration system is applied to an ultrasonic gas meter. The ultrasonic gas meter includes a first transducer, a second transducer, a flow sensor and a display. The first transducer and the second transducer are respectively installed on opposite sides of the flow channel to be metered. The second transducer is used to emit an ultrasonic wave along the gas flow direction (the time from the emission of the ultrasonic wave to the reception by the first transducer corresponds to the downstream flight time described below), and the first transducer is used to emit an ultrasonic wave against the gas flow direction (the time from the emission of the ultrasonic wave to the reception by the second transducer corresponds to the upstream flight time described below); the flow sensor is used to detect the ultrasonic wave. Several groups of ultrasonic signal data of the signal in the flow channel to be measured, each group of ultrasonic signal data includes an upstream flight time and a downstream flight time; the ultrasonic gas meter in this embodiment takes the NB remote ultrasonic gas meter as an example. The NB remote ultrasonic gas meter has a powerful data storage function, which can organize and record the upstream flight time, downstream flight time and various test parameters (including gas temperature, gas pressure, etc.) measured by the flow sensor during each complete ultrasonic transmission and reception process, and the test process mentioned below. Provide data support for the smart terminal described below for realizing zero bias correction, thereby continuously ensuring the measurement accuracy of the NB remote ultrasonic gas meter. It is a prior art and will not be repeated here.

[0024] Reference Figure 1 , a NB remote ultrasonic gas meter internal metering flow channel correction system includes a temperature sensor, a pressure sensor and an intelligent terminal; the temperature sensor is used to measure the gas temperature at the inlet and outlet of the flow channel to be measured; the pressure sensor is used to measure the gas pressure at the inlet and outlet of the flow channel to be measured; the flow sensor is also used to send each set of upstream flight time and downstream flight time measured to the intelligent terminal in real time; the intelligent terminal is used to automatically correct the zero bias of the ultrasonic gas meter flow channel according to the upstream flight time, the downstream flight time, the temperature parameter and the pressure parameter, and the intelligent terminal is connected to the display in the ultrasonic gas meter, the display is installed on the outer wall of the flow channel to be measured and is used to present the flow size after correction by the intelligent terminal. The intelligent terminal includes a processor and a memory, the memory is used to store at least one instruction, at least one program, code set or instruction set; the processor executes the following steps of a NB remote ultrasonic gas meter internal metering flow channel correction method when running at least one instruction, at least one program, code set or instruction set.

[0025] The following is a detailed description of the implementation of a NB remote ultrasonic gas meter internal metering flow channel calibration method in conjunction with the above-mentioned NB remote ultrasonic gas meter internal metering flow channel calibration system: Reference Figure 2 Another embodiment of the present application provides a method for calibrating a metering flow channel in a NB remote ultrasonic gas meter, comprising: S100, acquiring a plurality of first ultrasonic signal data within a preset first time period under a zero flow condition; Among them, the first time period is composed of several initial acquisition cycles. To facilitate the detailed explanation of the subsequent calculation process, the duration of the first time period in this embodiment is taken as 1 hour. The number of first ultrasonic signal data in the first time period is determined by the acquisition frequency of the transducer. In this embodiment, the two transducers in the flow channel to be measured take an initial acquisition cycle of every 10 minutes, and the processor will obtain 6 first ultrasonic signal data within one hour as an example (the number of first ultrasonic signal data obtained in the actual calibration process will be more; in addition, in each initial acquisition cycle, a complete cross-transmission and reception process of an ultrasonic signal includes: first, the first transducer sends a signal A, then the second transducer sends a signal B in response to the signal A after receiving the signal A sent by the first transducer, and finally the first transducer receives the signal B sent by the second transducer); the first ultrasonic signal data is used to calculate the flow rate of the gas in the flow channel to be measured, and each initial acquisition cycle in the first time period corresponds to a first ultrasonic signal data.

[0026] S200, preliminarily determining whether the gas meter has a zero bias problem based on the first ultrasonic signal data; The first ultrasonic signal data includes a first upstream flight time corresponding to the first transducer and a first downstream flight time corresponding to the second transducer during a certain initial acquisition cycle within the first time period; the first upstream flight time indicates the flight time of the ultrasonic signal from the first transducer to the second transducer, and the first downstream flight time indicates the flight time of the ultrasonic signal from the second transducer to the first transducer; specifically, S200 includes: S210, calculating an average phase difference between each group of first upstream flight time and first downstream flight time in the first time period; Among them, the average phase difference value is the average value of the difference between each group of first upstream flight time and first downstream flight time corresponding to each initial acquisition cycle. The average phase difference value is used to reflect the overall difference in the propagation characteristics of the ultrasonic signal between the first transducer and the second transducer in the first time period. It can be used as a preliminary indicator to evaluate whether the gas meter has potential zero bias problems or other abnormal conditions.

[0027] S220: If the average phase difference value is zero, it is determined that the gas meter does not have a zero bias problem.

[0028] S230, if the average phase difference value exceeds the preset value fluctuation range, it is determined that the gas meter has an abnormal fault, and an alarm is triggered; Among them, the numerical fluctuation range is related to the timing accuracy of the ultrasonic sensor itself in the gas meter. The numerical fluctuation range mainly takes into account the error of the sensor itself and the possible difference in the transmission time of the ultrasonic signal under slight environmental fluctuations; the numerical fluctuation range can be manually input by humans before the zero bias correction of the gas meter begins, or it can be automatically matched by the intelligent terminal according to the gas meter model to be corrected; in this embodiment, under normal working and zero flow conditions, the numerical fluctuation range is [-100ns, 100ns] as an example. For sensors with higher accuracy requirements, the corresponding numerical fluctuation range can reach [-10ns, 10ns]; When the average phase difference value exceeds the corresponding numerical fluctuation range, it indicates that there are significant factors affecting the propagation time of the ultrasonic wave. It may be a serious deviation in the installation angles of the two transducers (including torsion, pitch angle, roll angle, etc.), which makes the propagation path length of the ultrasonic wave in the flow channel to be measured very different in the downstream and upstream directions. There may also be serious blockage, foreign matter or local deformation inside the flow channel to be measured, which changes the propagation path and speed of the ultrasonic wave. There may also be strong electromagnetic interference near the flow channel to be measured or a mechanical failure of the transducer (such as abnormal transmission and receiving functions). The above factors often cannot be reduced by simple data correction, so a direct alarm is issued to notify relevant technicians to perform maintenance.

[0029] S240: If the average phase difference value is within the numerical fluctuation range, it is determined that the gas meter has a zero bias problem.

[0030] S300, when the gas meter has a zero bias problem, obtaining a plurality of second ultrasonic signal data within a preset second time period; The second time period is similar to the first time period in S100, and the second time period is equal to the first time period in length, and similarly, the second time period is composed of a number of initial acquisition cycles; the second ultrasonic signal is also used to calculate the flow rate of the gas in the flow channel to be measured, and each initial acquisition cycle in the second time period corresponds to a second ultrasonic signal data; the second ultrasonic signal data includes a first upstream flight time corresponding to the first transducer and a first downstream flight time corresponding to the second transducer during a certain initial acquisition cycle in the second time period; the second upstream flight time represents the flight time of the ultrasonic signal from the first transducer to the second transducer, and the second downstream flight time represents the flight time of the ultrasonic signal from the second transducer to the first transducer; The first ultrasonic signal data of this embodiment is shown in Table 1 below, and the second ultrasonic signal data is shown in Table 2 below: Table 1 The first period All first ultrasonic signal data tables within

[0031] Table 2 The second time period All second ultrasonic signal data tables within

[0032] It should be noted that, in terms of signal processing, since the various component parameters of the signal processing circuit in the ultrasonic gas meter can be regarded as relatively stable in the first time period and the second time period, the present embodiment does not consider the influence of circuit component aging, performance fluctuation (such as change in the leakage rate of the capacitor, gain drift of the amplifier), etc. on the ultrasonic signal flight time measurement, and other interference factors in the signal transmission process, such as the intensity and frequency characteristics of electromagnetic interference, etc., these interference factors are also basically consistent in the first time period and the second time period, so these interference factors are also not taken into account in the present embodiment; From an environmental perspective, in the selected first time period and second time period, factors such as ambient temperature, pressure, and gas composition (humidity, impurity content) in the flow channel may fluctuate due to factors such as air flow and equipment heat dissipation, resulting in deviations in the measured first upstream flight time, second upstream flight time, first downstream flight time, and second downstream flight time under zero flow conditions, resulting in a lower accuracy of the final time deviation, which in turn affects the correction effect of the present application; therefore, in order to ensure as much as possible that the effects of various environmental factors on the ultrasonic propagation speed remain relatively stable in the zero flow experiment, this embodiment adopts the following step S410 after step S300 to screen out the first (second) target acquisition period that can be used as effective comparison data in the zero flow experiment from all first (second) ultrasonic signal data.

[0033] S410, determining a plurality of first target acquisition cycles corresponding to a first time period according to all first upstream flight times, and determining a plurality of second target acquisition cycles corresponding to a second time period according to all second upstream flight times; Among them, the first upstream flight times corresponding to all first target acquisition cycles have very small numerical differences, which can be regarded as ultrasonic signal flight times measured under basically the same environmental factors; similarly, the second upstream flight times corresponding to the second target acquisition cycle also have very small numerical differences; specifically, since the determination method of the first target acquisition cycle and the second target acquisition cycle has the same principle, this embodiment takes the first target acquisition cycle as an example for detailed description, and S410 determines a number of first target acquisition cycles corresponding to the first time period according to all first upstream flight times, including: S411, determining a reference upstream flight time corresponding to the first time period from among all first upstream flight times; The reference upstream flight time may be any one of all first upstream flight times. In this embodiment, the reference upstream flight time takes the first upstream flight time corresponding to the first initial acquisition cycle as an example.

[0034] S412, determining a plurality of first target acquisition cycles corresponding to the first time period according to the reference upstream flight time; Specifically, S412 includes: S4121, calculating a first phase difference between the reference upstream flight time and all other first upstream flight times; The calculation formula of the first phase difference between each first upstream flight time and the reference upstream flight time is as follows: ; in, Indicates a first phase difference between a first upstream flight time corresponding to an initial acquisition cycle and a reference upstream flight time; represents a reference upstream flight time corresponding to the first time period; Indicates The first upstream flight time corresponding to the initial acquisition cycle.

[0035] S4122, if the first phase difference is less than or equal to a preset phase difference threshold, taking the initial acquisition period corresponding to the first phase difference as the first target acquisition period; Among them, the phase difference threshold of this embodiment takes 0.1 as an example; by screening the initial acquisition cycle in step S4122, the first target acquisition cycle set (including all first target acquisition cycles) in the first time period can be quickly determined when all influencing factors remain relatively consistent. This helps to eliminate data deviations caused by various unstable interference factors, thereby providing a stable and reliable data basis for the accurate calculation of subsequent time deviations.

[0036] It should be noted that the method for determining the several second target acquisition cycles corresponding to the second time period in S410 is similar to steps S411-S412 and will not be repeated here. Generally speaking, in order to ensure the rigor of the data, the number of the first / second target acquisition cycles needs to be maintained at 3 or more. If the number of the first / second target acquisition cycles finally determined in step S410 is less than 3 (i.e., does not meet the minimum requirement), the corresponding first / second time period is extended separately to collect more first ultrasonic signal data (second ultrasonic signal data) in S100 (S300). Each time an initial acquisition cycle is added, it is determined through step S410 whether the newly added initial acquisition cycle can be used as the target acquisition cycle, and this is repeated until the number of the corresponding first / second target acquisition cycles meets the minimum requirement.

[0037] In addition, in order to ensure the accuracy of the judgment of whether the time deviation is a fixed value in the subsequent step S600, the reference upstream flight time selected in the first time period shall not be the same as the reference upstream flight time selected in the second time period (if the reference upstream flight time selected in the second time period is the same as the reference upstream flight time in the first time period, the first upstream flight time corresponding to the next initial collection period is selected as the reference upstream flight time corresponding to the second time period, and so on, until the above-mentioned limiting conditions are met); for ease of understanding, the first target collection period and the second target collection period of this embodiment are shown in Table 3 and Table 4 respectively: Table 3 The first target acquisition cycle set table ( )

[0038] Table 4 Second target acquisition cycle set table ( )

[0039] S400, obtaining a first offset curve according to the first ultrasonic signal data, and obtaining a second offset curve according to the second ultrasonic signal data; Specifically, S400 includes: S420, calculating a plurality of first time differences corresponding to each first target acquisition cycle according to the first upstream flight time and the first downstream flight time, and calculating a plurality of second time differences corresponding to each second target acquisition cycle according to the second upstream flight time and the second downstream flight time; The first time difference refers to the difference between the first upstream flight time and the first downstream flight time corresponding to a first target acquisition cycle, and the second time difference refers to the difference between the second upstream flight time and the second downstream flight time corresponding to a second target acquisition cycle; specifically, the calculation formulas for the first time difference and the second time difference are as follows: ; ; in, Indicates A first time difference corresponding to a first target acquisition cycle; Indicates A first upstream flight time corresponding to a first target acquisition cycle; Indicates A first downstream flight time corresponding to a first target acquisition cycle; Indicates the total number of first target acquisition cycles; Indicates A second time difference corresponding to a second target acquisition period; Indicates a second upstream flight time corresponding to a second target acquisition cycle; Indicates a second downstream flight time corresponding to a second target acquisition cycle; Indicates the total number of second target acquisition cycles.

[0040] S430, obtaining a first offset curve corresponding to the first time period according to all the first time differences, and obtaining a second offset curve corresponding to the second time period according to all the second time differences; Among them, refer to Figure 3 The first offset curve and the second offset curve are used to reflect the continuous change of the difference between the upstream flight time and the downstream flight time in the corresponding time period. Specifically, the first offset curve is used to reflect the continuous change of the difference between each group of the first upstream flight time and the first downstream flight time (i.e., the first time difference) in the first time period; the second offset curve is used to reflect the continuous change of the difference between each group of the second upstream flight time and the second downstream flight time (i.e., the second time difference) in the second time period; specifically, the first / second offset curve of this embodiment is calculated based on the least squares method of linear fitting, and the calculation formula of the first offset curve is as follows: ; ; ; ; in, Both are first offset curves The coefficient of Represents the first offset curve Previous continuous time point The corresponding first time difference; Indicates the first time period The discrete time points corresponding to the first time differences; Indicates the total number of first target acquisition cycles; represents the total number of initial collection cycles included in the first time period; Indicates The first target acquisition cycle corresponds to the first Initial collection cycle; Indicates the first time period Total duration of The calculation formula of the second offset curve is as follows: ; ; ; ; in, Both are second offset curves The coefficient of Represents the second offset curve Previous continuous time point The corresponding second time difference; Indicates the second time period A discrete time point corresponding to a second time difference; represents the total number of acquisition cycles for the second target; represents the total number of initial collection cycles included in the second time period, ; Indicates The second target acquisition cycle corresponds to the first Initial collection cycle; Indicates the second time period The total duration of .

[0041] S500, obtaining an initial zero bias function according to the first offset curve and the second offset curve; Among them, the initial zero bias function is used to calculate the approximate zero bias value of the gas meter in the first time period and the second time period. The initial zero bias function is specifically used to calculate the approximate zero bias value of the gas meter corresponding to each initial acquisition cycle in the first time period (second time period) according to the first time difference (second time difference); specifically, the initial zero bias function is as follows: ; in, represents the initial zero bias function; represents the first offset curve; represents the second offset curve.

[0042] S600, judging whether the time deviation caused by the zero bias problem of the gas meter is a fixed value according to the approximate zero bias value; Among them, refer to Figure 4 , the time deviation is used to reflect the zero bias problem of the gas meter; specifically, S600 includes: S610, calculating an average zero bias of the initial zero bias function in the first time period or the second time period; Among them, the average zero bias is the first time period or the second time period Internal initial bias function The average value of all the approximate zero bias values ​​in the above sequence is given by: ; in, represents the initial bias function In the interval The average zero bias in .

[0043] S620, calculating the sum of the square errors between the approximate zero bias values ​​corresponding to all initial acquisition cycles in the first time period or the second time period and the average zero bias; The initial acquisition period in the first time period is the same as the initial acquisition period in the second time period. Therefore, in this embodiment, one of the above two (all initial acquisition periods in the first / second time period) is selected to complete the calculation of the sum of variances; the sum of variances is used to reflect the initial zero bias function The actual fluctuation of the approximate zero bias value on in the first time period or the second time period; Specifically, if the approximate zero bias value in the first time period is used to calculate the sum of variances (in this case, s is taken as 0 in the calculation of the average zero bias), the calculation formula for the sum of variances is as follows: ; If the approximate zero bias value in the second time period is used to calculate the sum of variances (in this case, s is taken as 1 in the calculation of the average zero bias), the formula for calculating the sum of variances is as follows: ; in, Indicates that in the first time period and the The approximate zero bias value corresponding to the initial acquisition cycle; Indicates that in the second time period and The approximate zero bias value corresponding to the initial acquisition cycle; represents the total number of initial collection cycles included in the first time period; represents the total number of initial collection cycles included in the second time period; represents the sum of the square errors between the approximate zero bias value corresponding to each initial acquisition cycle and the average zero bias in the first time period; represents the sum of the squares of the approximate zero bias value corresponding to each initial acquisition cycle and the average zero bias in the second time period. In this embodiment, , Any one of them is taken as the final sum of variances; represents the mean bias.

[0044] S630, if the variance sum is less than or equal to the preset variance sum threshold, it is determined that the time deviation corresponding to the gas meter is a fixed value; Among them, for high-precision gas meters, the values ​​of variance and threshold are generally between 0.01-0.05; for ordinary gas meters, the values ​​of variance and threshold are generally between 0.05-0.1; the variance and threshold of this embodiment take 0.05 as an example.

[0045] S640: If the sum of the variances is greater than the sum of the variances threshold, it is determined that the time deviation corresponding to the gas meter is not a fixed value.

[0046] S700, when the time deviation is a fixed value, obtaining a zero offset value for correction based on the first offset curve and the second offset curve; Among them, once the time deviation is determined as a fixed value, it means that during the entire flow measurement process, the upstream flight time and the downstream flight time of the ultrasonic signal in the same group of the gas meter always maintain a constant deviation, and this deviation is not affected by factors such as gas flow, environmental factors and measurement time within a certain range; for example, due to the manufacturing tolerance of the sensor in the gas meter A, the propagation time difference of the ultrasonic signal (the difference between the upstream flight time and the downstream flight time) is always fixedly 5 microseconds more during each measurement. At this time, the zero bias compensation of the gas meter A can be achieved by using the fixed value of 5 microseconds as the correction zero bias value; the correction zero bias value is used to improve the zero bias problem of the gas meter. In this embodiment, taking the first time period as an example, the calculation formula of the correction zero bias value is as follows: ; in, Indicates that the first offset curve The approximate zero bias value corresponding to ; Indicates that the second offset curve The approximate zero bias value corresponding to ; Indicates the zero bias value for correction; represents the total number of initial acquisition cycles in the first time period. In this embodiment, all the above correction zero bias calculation formulas are Can also be replaced by .

[0047] S800, correcting the difference between each set of upstream flight time and downstream flight time according to the correction zero bias value to obtain a correction result; Wherein, step S800 is executed once when each set of upstream flight time and downstream flight time sent by the flow sensor is obtained, and the correction result is the accurate flow value obtained after correction.

[0048] It should be noted that the S700 Positive and negative, when When it is a positive number, it means that there is a fixed positive deviation between the upstream flight time and the downstream flight time of the ultrasonic signal measured in the flow channel to be measured, which causes the actual flow value to be smaller than the flow detection value. This is because in the process of calculating the flow based on the ultrasonic flight time, a longer flight time difference (such as the difference between the upstream flight time and the downstream flight time in the time difference method) will make the calculated flow velocity smaller, and then make the flow detection value larger. Therefore, at this time, it is necessary to subtract the correction zero bias value from the measured flight time difference to obtain a more accurate actual flow. Conversely, when the correction zero bias value is a negative number, the measured ultrasonic signal flight time is shorter than the actual flight time, and the actual flow value is larger than the flow detection value. At this time, it is necessary to add the absolute value of the correction zero bias value to the measured flight time difference to correct the flow detection value; Specifically, the calculation formula for the accurate flow value (i.e., the calibration result) in S800 is as follows: ; in, Indicates the exact flow value; Indicates the length of the flow channel to be measured; It represents the upstream flight time of the ultrasonic signal measured by the flow sensor in the flow channel to be measured; It represents the downstream flight time of the ultrasonic signal measured by the flow sensor in the flow channel to be measured; Indicates the zero bias value for correction; Indicates the inclination angle between the ultrasonic signal transmission path and the flow channel to be measured, which is a preset value; Indicates the cross-sectional area of ​​the flow channel to be measured, which is a preset value.

[0049] It should be noted that, when the time deviation is a fixed value, if the first transducer and the second transducer are not installed in parallel, the preset value in the above S800 accurate flow value calculation formula However, since the change in the tilt angle is a fixed value for the same ultrasonic gas meter, the offset error caused by the difference between the upstream flight time and the downstream flight time of the ultrasonic signal in the above situation is also a fixed value that can be calculated by steps S100-S800. Therefore, the present application does not need to Situations where changes may occur are discussed individually.

[0050] S900, when the time deviation is not a fixed value, constructing a velocity-pressure field coupling function, and obtaining a correction result according to the velocity-pressure field coupling function; The velocity-pressure field coupling function is used to solve the velocity field and pressure field that can affect each other during fluid flow through step-by-step iteration. Specifically, S900 includes: S910, when the time deviation is not a fixed value, determining design variables and design parameters related to the gas flow in the flow channel to be measured; Among them, the design variable is the gas flow rate in the flow channel to be measured that has the greatest impact on the gas flow rate (when the gas demand is large, the gas flow rate in the flow channel to be measured is significantly accelerated); the design parameters include the gas temperature, gas pressure, gas density, and gas viscosity (i.e., the dynamic viscosity in the physical properties of the gas) in the flow channel to be measured; the gas density and gas viscosity in this embodiment can be directly obtained by looking up the gas composition and the corresponding temperature based on the density and viscosity data table / simple interpolation formula of the preset specific gas components at different temperatures. The details can be seen in the existing gas property database / manual, which will not be repeated here.

[0051] It should be noted that the design parameters are usually parameters that change indirectly due to the change in the gas flow rate in the flow channel to be metered or can directly affect the gas flow rate to a certain extent; the reasons for selecting the design parameters in this implementation are as follows: In the actual fluid flow process, different gas components have different densities and dynamic viscosities. Changes in density and dynamic viscosity will cause the gas to present different flow characteristics, because they will affect the resistance and energy loss of the gas flow, and then affect the velocity distribution, and ultimately affect the time deviation; at the same time, the two factors of temperature and pressure will also affect the gas density and gas viscosity. For example, in the flow channel to be metered, changes in temperature or pressure may cause uneven gas flow rate. This uneven flow state will indirectly change the gas density and gas viscosity, thereby causing time deviation; When studying the influence of these design parameters on the accuracy of flow calculation, it is found that when one of the design parameters changes alone (that is, only this one variable changes, and the other parameters remain the same as the standard values ​​under the standard experimental environment), the influence on the overall flow calculation accuracy is not significant. However, in actual situations, all design parameters often have a certain deviation from the corresponding standard values. At this time, these design parameters will greatly increase the complexity of flow calculation under the influence of each other, and the influence on the overall flow calculation accuracy will also become significant, which may cause large errors in the measurement results. Therefore, the design parameters of this embodiment include the above-mentioned change factors to include the influence of these change factors in the calculation process of the correction zero bias.

[0052] S920, constructing a velocity-pressure field coupling function based on the design parameters and the design variables; Among them, the velocity-pressure field coupling function is as follows: ; in, Indicates gas viscosity; The velocity vector representing the gas transmission in the flow channel to be measured, i.e. the gas flow velocity with directional attributes; represents the gradient operator, which is a vector differential operator. That is the Laplace operator; Represents the pressure gradient, which is the driving force generated by the pressure difference of the fluid microelement and determines the direction of the fluid acceleration; the viscosity term Represents the momentum diffusion caused by internal friction of the fluid.

[0053] It should be specially noted that, since the method for correcting the flow conditions in the metering channel in the present application is only applicable to horizontally laid channels, in this case, the pressure changes and flow rate changes in the metering channel are mainly caused by the pressure of the gas source and the flow demand of the gas-using equipment, and are not driven by volume forces such as gravity. Therefore, when applying the NS equation for solution, the influence of volume forces on the solution results can be ignored.

[0054] S930, determining the boundary conditions and initial conditions of the velocity-pressure field coupling function; The boundary conditions include the gas flow rate at the inlet and outlet of the flow channel to be measured (i.e., the design variable), the gas pressure measured by the pressure sensors at the inlet and outlet of the flow channel to be measured, and the gas temperature measured by the temperature sensor in the flow channel to be measured; the initial conditions include the gas flow rate, gas pressure, and gas temperature at the initial moment; It should be particularly noted that the gas flow rate at the inlet (outlet) of the flow channel to be metered can be directly obtained through the outlet (inlet) flow rate of upstream equipment such as compressors and gas storage tanks (such as downstream equipment such as gas furnaces and gas turbines); in this embodiment, the gas flow rate at the initial moment is 0, the gas pressure at the initial moment is the gas pressure measured by the pressure sensor at the inlet of the flow channel to be metered, and the gas temperature at the initial moment is the gas temperature measured by the temperature sensor in the flow channel to be metered.

[0055] S940, obtaining a correction result according to all boundary conditions, initial conditions and velocity-pressure field coupling function; The correction result is the accurate flow value recalculated by taking into account various design parameters. Specifically, in S940, all boundary conditions and initial conditions are first substituted into the velocity-pressure field coupling function to solve, and the velocity field and pressure field of the gas in the flow channel to be metered are obtained. The specific solution method can be achieved by the following method: ① Finite difference method: Divide the gas flow channel in the flow channel to be metered into grids, discretize the partial differential equations in the NS equations at the grid points, and obtain a set of algebraic equations. Then, these algebraic equations are solved by numerical methods (iterative solution, such as Gauss-Seidel iteration, Jacobi iteration, etc.), and the velocity and pressure values ​​at each grid point are obtained, thereby obtaining the velocity field and pressure field in the flow channel to be metered; ② Finite volume method: Divide the gas flow channel in the flow channel to be metered into a series of control volumes, integrate the NS equations on the control volumes, and obtain the algebraic equations about the physical quantities at the center of the control volume (that is, convert the partial differential equations into algebraic equations with control volumes as units). Then, according to the boundary conditions and initial conditions, the integrated algebraic equations are iteratively solved to obtain the average velocity and pressure in each control volume, and then the velocity field and pressure field in the flow channel are obtained; ③ Finite element method: Discretize the gas flow channel in the flow channel to be measured into several units, express the physical quantity in the unit as a function of the node value through the interpolation function, and then solve the NS equation by variation to obtain the algebraic equation about the node value. The subsequent processing steps of the algebraic equation are the same as the above-mentioned finite volume method; The above calculation methods are all existing technologies and will not be described in detail here.

[0056] It should be noted that, through steps S910-S940, when the time deviation is not a fixed value, the present application can comprehensively consider the design variables, design parameters, boundary conditions and initial conditions by constructing a velocity-pressure field coupling function, so that the gas meter can meet the measurement requirements under complex working conditions such as different temperatures, pressures, changes in gas composition and internal structure changes (such as transducer installation problems). By considering the interaction of multiple physical factors, accurate correction of the gas flow is achieved, effectively ensuring high-precision measurement of the gas meter in various actual usage scenarios.

[0057] Based on the same inventive concept mentioned above, an embodiment of the present application also discloses an intelligent terminal, which includes a memory and a processor, wherein the memory stores at least one instruction, at least one program, code set or instruction set, and the at least one instruction, at least one program, code set or instruction set is loaded and executed by the processor to implement a method for calibrating the metering flow channel in a NB remote ultrasonic gas meter as provided in the above method embodiment.

[0058] Based on the same inventive concept mentioned above, an embodiment of the present application also discloses a computer-readable storage medium, which stores at least one instruction, at least one program, code set or instruction set. The at least one instruction, at least one program, code set or instruction set can be loaded and executed by a processor to implement a method for calibrating the metering flow channel in a NB remote ultrasonic gas meter provided in the above method embodiment.

[0059] It should be understood that the "several" mentioned in this article refers to two or more. "And / or" describes the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0060] Those skilled in the art will appreciate that all or part of the steps to implement the above embodiments may be accomplished by hardware or by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium. The storage medium mentioned above may include, for example, various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0061] The above description is only an optional embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for calibrating a metering flow channel in a NB remote ultrasonic gas meter, applied to an ultrasonic gas meter, wherein the ultrasonic gas meter comprises a flow sensor for detecting and obtaining ultrasonic signal data of an ultrasonic wave in a flow channel to be measured, wherein each ultrasonic signal data comprises a set of upstream flight time and downstream flight time, and is characterized in that: include: Under zero flow conditions, obtaining a plurality of first ultrasonic signal data within a preset first time period; Preliminarily determine whether the gas meter has a zero bias problem based on the first ultrasonic signal data; When the gas meter has a zero bias problem, obtaining a plurality of second ultrasonic signal data within a preset second time period; Obtaining a first offset curve according to the first ultrasonic signal data, and obtaining a second offset curve according to the second ultrasonic signal data, wherein the first offset curve and the second offset curve are used to reflect the continuous change of the difference between the upstream flight time and the downstream flight time in a corresponding time period; Obtaining an initial zero bias function according to the first offset curve and the second offset curve, wherein the initial zero bias function is used to calculate an approximate zero bias value of the gas meter in the first time period and the second time period; Determine whether the time deviation of the gas meter caused by the zero bias problem is a fixed value according to the approximate zero bias value; When the time deviation is a fixed value, obtaining a zero offset value for correction based on the first offset curve and the second offset curve; The difference between each group of upstream flight time and downstream flight time is corrected according to the correction zero bias value to obtain a correction result.

2. The method for calibrating the internal metering flow channel of the NB remote ultrasonic gas meter according to claim 1 is characterized in that: The first time period is composed of a plurality of initial acquisition cycles, each initial acquisition cycle in the first time period corresponds to a first ultrasonic signal data, and each first ultrasonic signal data specifically includes a set of first upstream flight time and first downstream flight time; the preliminary determination of whether the gas meter has a zero bias problem based on the first ultrasonic signal data includes: Calculating an average phase difference between each group of the first upstream flight time and the first downstream flight time; If the average phase difference value is zero, it is determined that the gas meter does not have a zero bias problem; If the average phase difference value exceeds the preset value fluctuation range, it is determined that the gas meter has an abnormal fault, and an alarm is triggered; If the average phase difference value is within the numerical fluctuation range, it is determined that the gas meter has a zero bias problem.

3. The method for calibrating the metering flow channel in the NB remote ultrasonic gas meter according to claim 2 is characterized in that: The second time period is composed of a plurality of initial acquisition cycles, each initial acquisition cycle in the second time period corresponds to a second ultrasonic signal data, and each second ultrasonic signal data specifically includes a set of second upstream flight time and second downstream flight time; the first offset curve is obtained according to the first ultrasonic signal data, and the second offset curve is obtained according to the second ultrasonic signal data, including: Determine a plurality of first target acquisition cycles corresponding to the first time period according to all of the first upstream flight times, and determine a plurality of second target acquisition cycles corresponding to the second time period according to all of the second upstream flight times; A plurality of first time differences corresponding to each first target acquisition cycle are calculated based on the first upstream flight time and the first downstream flight time, and a plurality of second time differences corresponding to each second target acquisition cycle are calculated based on the second upstream flight time and the second downstream flight time, wherein the first time difference represents the difference between a certain group of the first upstream flight time and the first downstream flight time within the first time period; and the second time difference represents the difference between a certain group of the second upstream flight time and the second downstream flight time within the second time period; A first offset curve corresponding to the first time period is obtained based on all the first time differences, and a second offset curve corresponding to the second time period is obtained based on all the second time differences, wherein the first offset curve is specifically used to reflect the continuous change of the first time difference within the first time period, and the second offset curve is specifically used to reflect the continuous change of the second time difference within the second time period.

4. The method for calibrating the metering flow channel in the NB remote ultrasonic gas meter according to claim 3 is characterized in that: The initial zero bias function is used to obtain an approximate zero bias value corresponding to each of the initial acquisition cycles according to the first time difference and the second time difference, and the approximate zero bias value is used to represent the actual bias value of the gas meter in the initial acquisition cycle; the calculation formula of the initial zero bias function is as follows: ； in, represents the initial zero bias function; represents the first offset curve; represents the second offset curve; The determining, according to the approximate zero offset value, whether the time offset caused by the zero offset problem of the gas meter is a fixed value comprises: Calculating an average zero bias of the initial zero bias function in the first time period or the second time period, the average zero bias being an average of all consecutive approximate zero bias values ​​on the initial zero bias function in the first time period or the second time period; Calculate the sum of the square errors between the approximate zero bias values ​​corresponding to all the initial acquisition cycles in the first time period or the second time period and the average zero bias; If the sum of the variances is less than or equal to a preset sum of the variances threshold, it is determined that the time deviation corresponding to the gas meter is a fixed value; If the sum of the variances is greater than the sum of the variances threshold, it is determined that the time deviation corresponding to the gas meter is not a fixed value.

5. The method for calibrating the metering flow channel in the NB remote ultrasonic gas meter according to claim 3 is characterized in that: The step of determining a plurality of first target acquisition cycles corresponding to the first time period according to all the first upstream flight times comprises: determining a reference upstream flight time corresponding to the first time period from among all the first upstream flight times; Calculate a first phase difference between the reference upstream flight time and all other first upstream flight times; If the first phase difference is less than or equal to a preset phase difference threshold, the initial acquisition period corresponding to the first phase difference is used as the first target acquisition period.

6. An intelligent terminal, characterized in that: It includes a memory and a processor, wherein the memory stores at least one instruction, at least one program, code set or instruction set, and the at least one instruction, at least one program, code set or instruction set is loaded and executed by the processor to implement a method for calibrating a metering flow channel in a NB remote ultrasonic gas meter as described in any one of claims 1 to 5.

7. A NB remote ultrasonic gas meter internal metering flow channel calibration system, characterized in that: include: A temperature sensor is used to measure the temperature of the gas in the flow channel to be metered; A pressure sensor is used to measure the gas pressure in the flow channel to be measured; The intelligent terminal as described in claim 6 is communicatively connected to the flow sensor, the temperature sensor and the pressure sensor, and is used to calibrate the ultrasonic gas meter according to the gas temperature, the gas pressure, the upstream flight time and the downstream flight time to obtain a calibration result.

8. A computer-readable storage medium, characterized in that: The readable storage medium stores at least one instruction, at least one program, code set or instruction set, and the at least one instruction, at least one program, code set or instruction set is loaded and executed by the processor to implement a method for calibrating a metering flow channel in a NB remote ultrasonic gas meter as described in any one of claims 1 to 5.

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