A calculation method of an electromagnetic interference resistant gas ultrasonic flowmeter

Abstract

The application discloses a kind of calculation methods of gas ultrasonic flowmeter of anti-electromagnetic interference, it is related to ultrasonic flow measurement technical field, to solve the problem that existing technology is difficult to realize accurate measurement under complex interference;The method comprises;S1, reference sound velocity confirmation: selecting the group data of gas ultrasonic flowmeter recent test, satisfy, wherein, for measurement frequency, for the shortest time of sound velocity variation rate <0.1% under normal data in field, and the average value is obtained after interference filtering to the group data, the average value is taken as reference sound velocity C 0， And the deviation of C0 and actual sound velocity is less than, it is the smaller value in the maximum deviation of field non-interference data and the minimum value of interference data, the application has the advantages of accurate measurement under complex interference environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ultrasonic flow metering, in particular to a calculation method of an electromagnetic interference resistant gas ultrasonic flow meter. BACKGROUND

[0002] In the field of flow metering, ultrasonic flow meters achieve flow calculation through the propagation characteristics of ultrasonic waves in fluids and are widely used in flow metering scenarios of fluids such as gas and water.

[0003] However, in actual application, the flow metering technology of existing ultrasonic flow meters has the problem that the reference sound velocity used as the basis for flow calculation is mainly obtained by relying on the "self-gain wave finding" scheme, but this scheme is prone to errors in calculating the reference sound velocity in an electromagnetic interference and same-frequency noise interference environment, resulting in a loss of accurate basis for flow data derived based on the sound velocity, and the interference filtering logic used in the existing technology can only filter the "wrong wave phenomenon" caused by hardware failure or hardware characteristic fluctuations, but cannot effectively identify and filter non-hardware interference signals (such as short electromagnetic pulses and environmental noise coupling signals) with a duration of 5 μs, thereby causing flow calculation errors and greatly reducing the metering accuracy of metering equipment in a complex interference environment. In view of this, we propose a calculation method of an electromagnetic interference resistant gas ultrasonic flow meter. SUMMARY

[0004] The purpose of the present application is to provide a calculation method of an electromagnetic interference resistant gas ultrasonic flow meter, which aims to solve the problem that the prior art cannot accurately meter in a complex interference environment.

[0005] To solve the above technical problems, the present application provides the following technical scheme: a calculation method of an electromagnetic interference resistant gas ultrasonic flow meter, which comprises:

[0006] S1: reference sound velocity confirmation: selecting a group of data recently tested by the gas ultrasonic flow meter, satisfying wherein, is the measurement frequency, is the shortest time under which the sound velocity changes at a rate of <0.1% under normal data in the field, and the average value of the group of data after interference filtering is taken as the reference sound velocity C 0， and the deviation of C0 from the actual sound velocity is less than , is the smaller one of the maximum deviation of the data in the field without interference and the minimum value of the interference data; S2: effective data acquisition: assuming that the sound velocity in the current measurement period is C

[0007] ​​0， And both upward and downward × φ is a constant, where, Let φ be the average axial velocity of the fluid, and φ be the angle between the sound channel and the horizontal, satisfying the following conditions: + φ、 - × φ, where L is the length of the ultrasonic wave propagation path. For downstream flight time, Define the time of flight against the current. 2C 0 ， when Data is considered valid when the value is 0.

[0008] S3: Confidence analysis provides the correct flow rate: analyzes the most recently measured flow rate. Group data, if the number of valid data points is greater than ,Right now < , Based on the average number of valid data points determined under severe electromagnetic interference or co-frequency noise interference environments, valid data are extracted and combined with... Output flow, of which, The average axial velocity of the fluid. For the flow area of ​​the channel, if the number of valid data If the deviation is small, the corresponding flow rate is output; otherwise, the current flow rate remains unchanged.

[0009] Preferably, in S1 above, select The basis is: During the corresponding time interval, the composition, temperature, and pressure of the fluid medium are assumed to remain unchanged, which is consistent with the principle that the speed of sound is constant when the composition, temperature, and pressure of the medium remain unchanged.

[0010] Preferably, in S2 above, for Partial differential equations are obtained ,right Partial differential equations are obtained , total deviation change amount satisfies .

[0011] Preferably, in the above S2, because , and deviation is extremely small, and ultrasonic measurement is based on the principle of the first wave, which only makes the measurement time smaller under normal circumstances, and cannot be larger, excluding larger and smaller by the same order of magnitude or larger and smaller by the same order of magnitude interference cases.

[0012] Preferably, in the above S2, by relationship to verify the validity of the data.

[0013] Preferably, in the above S1, when selecting the latest test group data, the measurement time stamp continuity of the group data needs to be additionally verified, and if there is disconnected data with a time stamp interval greater than , the disconnected data is removed and the group data is reselected.

[0014] Preferably, after reselecting the group data, there is still disconnected data and it cannot satisfy , the measurement frequency is temporarily adjusted to 1 , 1 / 2, until 1 , and the adjusted 1 needs to ensure that the sound velocity change rate under normal data on site is still less than 0.1%.

[0015] Preferably, in the above S1, after the group data is filtered for interference and the average value is taken, the data is filtered for interference using the Rayleigh criterion.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] 1. This invention selects data within the shortest time frame with a sound velocity change rate of <0.1%, controls the deviation between the reference sound velocity and the actual sound velocity, filters out interference from the data to determine the reference sound velocity, then determines the valid data, and combines the number of valid data and deviation analysis to output the flow rate, thereby reducing measurement inaccuracies and fluctuations caused by electromagnetic interference and co-frequency noise interference, and improving measurement accuracy.

[0018] 2. This invention verifies the continuity of timestamps when selecting data, removes disconnected data with intervals exceeding twice the measurement frequency, and reselects data. If the data is still disconnected and does not meet the data selection conditions, the measurement frequency is temporarily adjusted to ensure that the data selection conditions are met and the rate of change of sound velocity is still <0.1%, thus ensuring uninterrupted measurement.

[0019] 3. By clarifying the relationship between the changes in flight time with and against the current and the total deviation, this invention quantifies the transmission effect of time measurement error on the total deviation, making it easier to control the measurement deviation based on this quantified relationship, improving the controllability of measurement accuracy, and reducing the impact of interference on data deviation. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0021] Example 1

[0022] A calculation method for an electromagnetic interference-resistant ultrasonic gas flow meter, the method comprising the following steps;

[0023] S1: Reference sound velocity confirmation: Select the most recently tested gas ultrasonic flow meter. Group data, satisfy ,in, To measure frequency, The shortest time for the rate of change of sound speed to be <0.1% under normal on-site data, and the... After filtering out interference from the data sets, the average value is taken, and this average value is used as the reference sound speed C. 0， And the deviation between C0 and the actual speed of sound is less than , It is the smaller of the maximum deviation of the interference-free data and the minimum value of the interference data.

[0024] S2: Effective Data Acquisition: Let the speed of sound in the current measurement period be C. 0， And both upward and downward × φ is a constant, where, Let φ be the average axial velocity of the fluid, and φ be the angle between the sound channel and the horizontal, satisfying the following conditions: + φ, - × φ, wherein L is the ultrasonic wave propagation path length, is the forward flow time, is the reverse flow time, defined as 2C 0 ， When 0, the data is determined to be valid data;

[0025] S3: the confidence analysis gives the correct flow: analyze the latest measured group data, if the number of valid data is greater than , that is < , Based on the average value of the number of valid data in the environment of serious electromagnetic interference or same frequency noise interference, the valid data is extracted under this condition, combined with Output flow, wherein is the axial average velocity of the fluid, is the flow area of the flow passage, if the number of valid data is , analyze the number of valid data output recently, and output the corresponding flow if the deviation is small, otherwise keep the current flow unchanged.

[0026] Wherein, in the above S1, the basis for selecting group data is that: the fluid medium composition, temperature and pressure are considered unchanged within the time interval corresponding to the group data, which conforms to the principle that the sound speed is fixed when the medium composition, temperature and pressure are unchanged.

[0027] Wherein, in the above S2, the total differential is obtained by partial differentiation, and the total differential is obtained by partial differentiation, and the total differential change satisfies .

[0028] Wherein, in the above S1, because ​​ , With deviation is very small, and the ultrasonic metering is based on the principle of the first wave, which only makes the measurement time smaller under normal circumstances, but cannot be larger, excluding larger and smaller by the same order of magnitude or larger and smaller by the same order of magnitude interference cases.

[0029] Among them, in the above S2, by relationship to verify the validity of the data.

[0030] Among them, in the above S1, when selecting the latest test group data, the continuity of the measurement time stamp of the group data needs to be checked additionally, if there is a disconnected data with a time stamp interval greater than , the disconnected data is removed and the group data is selected again.

[0031] Among them, after reselecting , there are still disconnected data and it cannot meet , the measurement frequency is temporarily adjusted to 1 , 1 / 2, until 1 , and the adjusted 1 needs to ensure that the sound velocity change rate under normal data on site is still <0.1%.

[0032] Among them, in the above step S1, after removing the interference of the group data, the average value is taken, and the data is filtered by using the Laplace criterion.

[0033] In this embodiment, through the synergistic effect of multiple steps, the electromagnetic interference and the same frequency noise interference are effectively suppressed, and the accuracy and stability of fluid flow measurement are significantly improved.

[0034] In the reference sound velocity confirmation link, by selecting the time constraint , and The shortest time for the rate of change of sound velocity < 0.1% and the medium parameters (composition, temperature, pressure) are approximately constant The group data is combined with the interference filtering and the average value is taken as the reference sound velocity At the same time, the data timestamp continuity is checked, and the measurement frequency is adjusted when the connection is broken, which ensures The deviation from the actual sound velocity is less than The smaller value of the maximum deviation of the non-interference data and the minimum value of the interference data lays a precise foundation for subsequent data validity judgment;

[0035] In the effective data acquisition link, the judgment index is constructed based on the relationship between the sound velocity and the axial average speed of the fluid, and the total deviation change control and data checking relationship derived by partial differential (dV / dt The effective data with a deviation of 0 is accurately screened out 0, and the first wave principle of ultrasonic measurement is used to exclude specific interference conditions, further reducing the influence of interference data on the measurement results;

[0036] In the confidence analysis link, by setting a threshold based on the average accuracy of interference environment data The number of effective data is judged, and only when the effective data is sufficient, the flow formula is combined The output flow, when the effective data is insufficient, the flow output mode is decided according to the deviation of the historical effective data, avoiding the flow calculation error caused by invalid data in the interference environment.

[0037] Overall, the embodiment can continuously output accurate and reliable fluid flow data in the presence of serious electromagnetic interference or same frequency noise interference, ensuring the stability and accuracy of the flow measurement in the ultrasonic flowmeter calculation process.

[0038] The embodiments of the present application are disclosed, but not limited to, the ordinary skilled in the art can easily understand the spirit of the present application and make different inferences and changes according to the above embodiments, as long as they do not deviate from the spirit of the present application, they are within the protection scope of the present application.

Claims

1. A method of calculating an electromagnetic interference immune gas ultrasonic flow meter, characterized by, The method comprises the following steps: S1: reference sound velocity confirmation: select the latest test of the gas ultrasonic flowmeter group data, satisfy wherein, is the measurement frequency, is the shortest time under the sound velocity change rate <0.1% of the normal data on site, and the average value of the group data after interference filtering is taken, the data is filtered by the Raydah criterion, and the average value is taken as the reference sound velocity C 0， and the deviation of C0 from the actual sound velocity is less than , is the smaller value of the maximum deviation of the on-site non-interference data and the minimum value of the interference data; S2: valid data acquisition: let the sound velocity in the current measurement period be C 0， and the uplink and downlink φ is a constant value, wherein, is the fluid axial average velocity, φ is the angle between the sound channel and the horizontal, and satisfies φ, φ, wherein L is the ultrasonic wave propagation path length, is the downstream flight time, is the upstream flight time, defined as 2C 0 ， when 0 is determined as valid data;​​​​ S3: Confidence analysis gives correct flow: analyze the latest measured group data, if the number of valid data is greater than , that is < , based on the average value of the number of valid data in the environment of serious electromagnetic interference or same frequency noise interference, the valid data is extracted, combined with output flow, wherein, is the axial average velocity of the fluid, is the flow area of the flow passage, if the number of valid data is , analyze the number of valid data output recently, the deviation is small, output the corresponding flow, otherwise keep the current flow unchanged.

2. The method of claim 1, wherein, In the above S1, selecting The basis of the group data is that the In the time interval corresponding to the group data, the fluid medium composition, temperature and pressure are considered to be constant, which conforms to the principle that the sound speed is fixed when the medium composition, temperature and pressure are constant.

3. The method of claim 1, wherein, In the above S2, the total deviation change amount satisfies Partial differentiation gives , the total deviation change amount satisfies Partial differentiation gives , the total deviation change amount satisfies .

4. The method of claim 1, wherein, In the above S1, because , and deviation is very small, and ultrasonic measurement is based on the principle of the first wave, which under normal circumstances only makes the measurement time smaller but cannot be larger, excluding larger and smaller by the same order of magnitude or larger and smaller by the same order of magnitude interference.

5. The method of claim 1, wherein, In the above S2, the data validity is verified by the relationship.

6. The method of claim 1, wherein, In the above S1, the most recently tested group data is selected . When selecting the group data, the continuity of the measurement time stamps of the group data is additionally checked. If there is disconnected data with a time stamp interval greater than , the disconnected data is removed and the group data is reselected. ​ 7. The method of claim 6, wherein the method further comprises: reselect There are still disconnected data and cannot meet , the measurement frequency is temporarily adjusted to 1 , 1 / 2, until the adjusted 1 , and the adjusted 1 Need to ensure that the sound velocity change rate under normal data is still <0.1%.

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