Anti-seismic and anti-power-frequency-interference system and method for vortex shedding flowmeter

Abstract

The invention discloses an anti-seismic and anti-power-frequency-interference system and method for a vortex shedding flowmeter, and relates to the technical field of flow measurement, the system comprises a signal receiving module, a vibration monitoring module, a frequency identification module, a temperature and pressure measurement module and an interference signal processing module, interference signals in a flow-free state can be accurately processed, whether actual flow exists or not can be accurately judged by measuring the temperature and pressure of fluid in a pipeline and combining the temperature and pressure with vibration and frequency characteristic information, wrong measurement data generated due to the interference signals in the flow-free state are avoided, and the measurement accuracy is improved. According to the method and the system, the measurement problem caused by misjudgment can be reduced, meanwhile, information about the equipment operation state and the pipeline environment is provided for different types of interference signals through comprehensive analysis and judgment of the system, potential equipment faults and abnormal working conditions can be found in time, and a powerful data basis is provided for maintenance and management of the equipment.

Description

Technical Field

[0001] The invention relates to the technical field of flow measurement, in particular to a system and method for resisting earthquake and power frequency interference of a vortex flowmeter. Background Art

[0002] As an important flow measurement device, vortex flowmeter is widely used in many industrial fields such as petroleum, chemical industry, electric power, metallurgy, water supply and drainage, etc. It detects the vortex frequency generated when the fluid flows through the vortex generator in the pipeline, and measures the flow of the fluid based on the Karman vortex principle. It has the advantages of simple structure, high reliability and wide application range. In the industrial production process, accurate flow measurement is crucial to controlling process, material balance, energy metering and trade settlement. Therefore, the stable and accurate operation of vortex flowmeter is one of the key factors to ensure industrial production efficiency and economic benefits. However, in the actual industrial environment, vortex flowmeter is often under complex working conditions and is affected by many factors.

[0003] The existing anti-interference technology, on the one hand, is often relatively simple in filtering out interference signals, and mostly adopts traditional filtering methods without fully considering the characteristics of different interference signals. It is impossible to filter out interference signals generated by different interference sources based on their unique frequency, amplitude, phase and other characteristics. As a result, in practical applications, interference signals still have a significant impact on measurement results, resulting in reduced measurement accuracy.

[0004] On the other hand, existing technologies perform poorly in processing interference signals under no-flow conditions. When there is actually no fluid flowing in the pipeline, interference signals will still be generated, and existing technologies cannot accurately identify and process this situation, which can easily lead to misjudgment and affect subsequent metering operations and industrial process control.

[0005] In summary, the existing vortex flowmeter anti-interference technology is difficult to meet the growing needs of high-precision measurement and stable operation under complex working conditions in industrial sites. A more intelligent, accurate and targeted anti-interference system and method is needed, which can accurately identify and filter out interference signals according to the characteristics of the interference signals and the actual fluid state in the pipeline, so as to improve the measurement accuracy and reliability of the vortex flowmeter. Summary of the invention

[0006] The purpose of the present invention is to make up for the shortcomings of the prior art and to provide a system and method for the earthquake resistance and power frequency interference resistance of a vortex flowmeter. The system and method can use a vibration sensor to monitor whether the pipeline has vibration and the frequency characteristics of the vortex output signal, filter out vibration and power frequency interference, and measure the temperature and pressure of the fluid in the pipeline to determine whether there is an interference signal. The method of monitoring pipeline vibration and analyzing the flowmeter frequency signal can solve the interference signal, and at the same time, cooperate with the temperature and pressure measurement of the fluid in the pipeline to solve the interference problem when there is no flow.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: On the one hand, a system for vortex flowmeter to resist earthquake and power frequency interference, the system comprises: a signal receiving module, a vibration monitoring module, a frequency identification module, a temperature and pressure measurement module and an interference signal processing module;

[0008] The signal receiving module receives the frequency signal output by the vortex flowmeter in real time, and transmits it to the frequency identification module and the interference signal processing module;

[0009] The vibration monitoring module uses a vibration sensor to monitor the pipeline vibration in real time and transmit the vibration parameters to the interference signal processing module;

[0010] The frequency identification module uses a spectrum analysis algorithm to perform real-time analysis on the received frequency signal, identify the frequency components in the signal, determine the characteristic frequency of the interference signal, and transmit the identification result to the interference signal processing module;

[0011] The temperature and pressure measurement module uses a temperature sensor and a pressure sensor to measure the temperature and pressure of the fluid in the pipeline in real time, and transmits the measurement data to the interference signal processing module;

[0012] The interference signal processing module makes a comprehensive judgment based on the received vibration parameters, frequency identification results and temperature and pressure measurement data, and satisfies the following conditions: when the vibration parameters exceed the normal range, the frequency identification results show the existence of interference signal characteristic frequency, and the temperature and pressure measurement data show that there is no flow in the pipeline, the signal is judged to be an interference signal, filtered out, and an accurate flow measurement signal is output, and the filtered signal y(n) and the historical data y are calculated. hist The mean square error of (n) Where N is the data length, and the correlation coefficient with the instrument data is calculated at the same time Where x(n) is the instrument data, and are the means of x(n) and y(n), respectively. When MSE>τ MSE and |ρ xy |<τ ρ When one of the above conditions is met, the interference judgment process is restarted, τMSE and τ ρ are the mean square error threshold and correlation coefficient threshold, respectively, |ρ xy | is the absolute value of the correlation coefficient.

[0013] Furthermore, the working principle of the vortex flowmeter in the signal receiving module is:

[0014] Fluid flow and vortex formation: When the fluid flows into the measuring pipe of the vortex flowmeter, a columnar object is arranged in the measuring pipe perpendicular to the flow direction of the fluid, which is a vortex generator. When the fluid meets the vortex generator placed in the pipe, the vortex generator is hindered from flowing due to the viscosity of the fluid, thereby forming a boundary layer separation phenomenon. On both sides of the downstream of the vortex generator, vortices with opposite rotation directions are alternately generated, and the vortices are arranged into a regular vortex array, namely, the Karman vortex street;

[0015] Relationship between vortex frequency and flow velocity: The formation frequency of the Karman vortex street is related to the flow velocity of the fluid, that is, the frequency of vortices alternately falling off from both sides of the vortex generator. According to fluid mechanics, the relationship between the vortex street frequency f and the fluid flow velocity v and the width d of the flow surface of the vortex generator is: Where St is the Strouhal number, which remains constant within the Reynolds number range. The Reynolds number Re is a dimensionless number that measures the flow state of the fluid. Where ρ is the fluid density, μ is the fluid dynamic viscosity, and when the Reynolds number Re is in the standard range, the Strouhal number St is considered a constant;

[0016] Vortex detection and signal conversion: There is a piezoelectric element inside the vortex generator. When vortices are generated alternately, periodically changing pressure pulsations are generated around the vortex generator. The pressure pulsations act on the piezoelectric element. According to the piezoelectric effect, the piezoelectric element will generate an electric charge proportional to the pressure change. The charge generated by the piezoelectric element is amplified by a charge amplifier connected to it, and the weak charge signal is converted into a measurable voltage signal. The frequency of the voltage signal is the same as the vortex street frequency, which reflects the frequency of vortex shedding in the fluid, and the flow state of the fluid, that is, the vortex street frequency, is converted into an electrical signal.

[0017] Furthermore, the electrical signal output by the piezoelectric element in the vortex flowmeter is weak and contains interference components, the circuit signal is filtered to remove high-frequency and low-frequency noise, and the useful signal with the vortex frequency is retained, the amplifier circuit further amplifies the filtered signal, and the shaping circuit converts the amplified signal into a standard pulse signal, whose frequency is consistent with the vortex frequency;

[0018] The processed pulse signal is received by the signal receiving module as the output signal of the vortex flowmeter, and the signal receiving module transmits the received signal to the frequency identification module and the interference signal processing module for subsequent flow calculation and interference analysis.

[0019] Furthermore, the specific steps of the frequency identification module are:

[0020] Signal input: The frequency identification module receives the frequency signal output by the vortex flowmeter from the signal receiving module. The frequency signal is a time domain signal, i.e., a voltage and current waveform that changes with time, reflecting the vortex shedding frequency and interference information generated by the fluid flow detected by the vortex flowmeter;

[0021] Pre-processing: Before the signal is input into the spectrum analysis algorithm, the input signal is pre-processed, including sampling and quantizing the signal to convert the continuous analog signal into a discrete digital signal. The sampling process samples the input signal at equal intervals to ensure that the information of the original signal can be fully retained. The quantization process converts the continuous amplitude obtained by sampling into a discrete digital amplitude.

[0022] Spectrum analysis: The pre-processed discrete signal is input into the spectrum analysis algorithm to extract the frequency component information in the signal.

[0023] Furthermore, the frequency identification module inputs the discrete digital amplitude after pre-processing into the spectrum analysis algorithm for quantization. The quantized signal is represented as x(n), where n=0, 1, 2, ..., N-1, and N is the number of sampling points. The quantized discrete signal sequence x(n) is used as input to the FFT algorithm of the spectrum analysis algorithm, and a bit reversal operation is performed on the input sequence x(n), that is, the element positions of the input sequence are rearranged according to the bit reversal principle. For the binary representation of n, its bit order is reversed to obtain a new index m, the positions of x(n) and x(m) are exchanged, and the bit-reversed sequence is iteratively calculated according to the butterfly structure, and finally the input time domain discrete sequence x(n) is converted into a frequency domain sequence X(k). When s=N, that is, after the last iteration, the obtained X(k) contains the amplitude and phase information of the original signal at different frequency components. Each X(k) element corresponds to a frequency component, and its frequency f k By k = kΔf calculation, where the frequency resolution f s is the sampling frequency, k is the index of the frequency domain sequence, k = 0, 1, 2, …, N-1.

[0024] Furthermore, the FFT algorithm iteratively calculates the bit-reversed sequence according to the butterfly structure. The FFT calculation process is divided into multiple stages, each stage contains multiple groups of butterfly operations, and the sequence x is divided into several groups, each group contains s elements. For the elements in each group, it is further divided into two subgroups, each group contains m elements. For s=2 to N, that is, each stage where s is shifted left by one bit each time calculates m=s>>1, where m represents half of the number of elements in each butterfly operation group. For traversing different butterfly operation groups i=0 to N-1, each group of the entire sequence is traversed with s as the step size:

[0025] For elements j = 0 to m-1, calculate the rotation factor t = W(s, j)*x[i+j+m], where is the rotation factor weight;

[0026] Update x[i+j+m]=x[i+j]-t;

[0027] Update x[i+j]=x[i+j]+t.

[0028] On the other hand, a method for vortex flowmeter to resist earthquake and power frequency interference, the specific steps of the method are:

[0029] S100, using a signal receiving module to receive in real time a frequency signal output by a vortex flowmeter;

[0030] S200, acquire multi-source data, including pipeline vibration, digital signal spectrum analysis, fluid temperature and pressure;

[0031] S300, when any one of the vibration interference condition, the frequency interference condition and the no-flow condition is met, the interference signal processing module determines that the current signal is an interference signal;

[0032] S400, using an interference signal processing module to filter the determined interference signal, and output a pure flow signal after filtering;

[0033] S500, compare and analyze the filtered flow signal with historical measurement data and instrument data in the same pipeline system.

[0034] Furthermore, the result verification process of S500 is as follows:

[0035] Compare and analyze the filtered flow signal with historical measurement data and instrument data in the same pipeline system, and calculate the mean square error between the filtered signal and the historical data, as well as the correlation coefficient with the instrument data;

[0036] Abnormal processing: When the mean square error is greater than the set threshold and the correlation coefficient is less than the set threshold, it indicates that there is still a problem with the filtered signal. Restart the interference judgment process, adjust the filtering parameters, and judge and filter the interference signal again;

[0037] Output result: When the verification result does not meet any of the conditions, the filtered flow signal is output as the final measurement result.

[0038] Compared with the prior art, the system and method for vortex flowmeter anti-seismic and anti-power frequency interference have the following beneficial effects:

[0039] 1. In terms of signal processing, the present invention not only takes into account pipeline vibration monitoring and frequency feature identification, but also combines temperature and pressure measurement modules, which can comprehensively analyze the measurement environment and signal characteristics, making the judgment of interference signals more accurate, avoiding misjudgment caused by misjudgment of a single factor, and effectively filtering out various interferences to ensure the accuracy of flow measurement, especially in complex industrial environments, which can significantly reduce measurement errors caused by interference and improve the overall stability and reliability of the measurement system.

[0040] 2. The present invention can accurately process interference signals in a no-flow state. By measuring the temperature and pressure of the fluid in the pipeline and combining it with the vibration and frequency characteristic information, it can accurately determine whether there is actual flow, avoiding erroneous measurement data due to interference signals when there is no flow. This helps to reduce metering problems caused by misjudgment. At the same time, for different types of interference signals, through systematic comprehensive analysis and judgment, it provides information about the equipment operating status and pipeline environment, which helps to timely discover potential equipment failures and abnormal operating conditions, and provide a strong data basis for equipment maintenance and management.

[0041] Other advantages, objectives and features of the present invention will be set forth in part in the following description and, in part, will be apparent to those skilled in the art based on an examination of the following or may be taught from the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0043] Figure 1 It is an operation step diagram of a system for vortex flowmeter to resist earthquake and power frequency interference;

[0044] Figure 2 The present invention is a flow chart of a method for making a vortex flowmeter resistant to earthquakes and power frequency interference. DETAILED DESCRIPTION

[0045] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation mode, structure, characteristics and effects of the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments.

[0046] Embodiment 1

[0047] like Figure 1 As shown, this embodiment describes in detail the operation process of a system for vortex flowmeter anti-seismic and anti-power frequency interference. The system integrates a signal receiving module, a vibration monitoring module, a frequency identification module, a temperature and pressure measurement module and an interference signal processing module. Through the coordinated work of each module, the output signal of the vortex flowmeter is processed, the interference signal is effectively filtered out, and high-precision flow measurement is achieved. This embodiment deeply analyzes the working principle, operation process and mutual cooperation mechanism of each module.

[0048] The signal receiving module is responsible for receiving the frequency signal output by the vortex flowmeter. The vortex flowmeter works based on the Karman vortex principle. When the fluid flows into the measuring pipe and encounters the vortex generator, the boundary layer separation phenomenon is formed on both sides of the vortex generator due to the viscosity of the fluid, and then vortices with opposite rotation directions are alternately generated on both sides of the downstream. These vortices are arranged into a Karman vortex street. According to fluid mechanics, the relationship between the vortex frequency f and the fluid flow velocity v and the width d of the frontal surface of the vortex generator is: Where St is the Strouhal number. Within a certain range of Reynolds numbers, St remains constant, while the Reynolds number Here ρ is the fluid density, μ is the fluid dynamic viscosity, when the Reynolds number Re is in the standard range, St can be regarded as a constant, so that by measuring the vortex frequency f, the fluid flow velocity v can be calculated, and then the flow data can be obtained, and a piezoelectric element is installed inside the vortex generator. When the vortex is generated alternately, a periodically changing pressure pulsation will be generated around it. The pressure pulsation acts on the piezoelectric element. According to the piezoelectric effect, the piezoelectric element generates a charge proportional to the pressure change. These charges are amplified by the charge amplifier connected to it and converted into a measurable voltage signal. Since the electrical signal is weak and contains interference components, it first passes through a filtering circuit to remove high-frequency and low-frequency noise, retaining the useful signal related to the vortex frequency, and then further amplified by the amplifier circuit, and finally converted into a standard pulse signal through a shaping circuit. This pulse signal is the output signal of the vortex flowmeter, which is received by the signal receiving module. The signal receiving module transmits the received signal to the frequency identification module and the interference signal processing module to provide a data basis for subsequent flow calculation and interference analysis.

[0049] The vibration monitoring module uses a vibration sensor to monitor the vibration of the pipeline in real time. The vibration sensor is based on the principle of vibration change. When the pipeline vibrates, the vibration sensor converts the vibration signal into an electrical signal, and obtains relevant parameters such as vibration amplitude and frequency through the built-in signal conditioning circuit. These vibration parameters will be transmitted to the interference signal processing module in real time to determine whether the pipeline vibration interferes with the measurement of the vortex flowmeter. In actual operation, the vibration monitoring module continuously collects vibration data to provide dynamic information support for the judgment of interference signals.

[0050] The frequency identification module performs spectrum analysis on the received frequency signal, identifies the frequency components therein, and determines whether there is a characteristic frequency of the interference signal. The module receives the frequency signal from the signal receiving module, which is a time domain signal that reflects the vortex shedding frequency and possible interference information generated by the fluid flow detected by the vortex flowmeter. Before performing spectrum analysis, the input signal needs to be pre-processed, including sampling and quantization. The sampling process samples the input continuous analog signal at equal intervals according to a certain sampling frequency to ensure that the information of the original signal can be fully retained. The quantization process converts the continuous amplitude obtained by sampling into a discrete digital amplitude. The quantized signal is represented as x(n), where n=0,1,2,…,N-1, and N is the number of sampling points. The pre-processed discrete signal x(n) is input into the spectrum analysis algorithm. In the FFT algorithm of the spectrum analysis algorithm, the input sequence x(n) is first bit-reversed. For the binary representation of n, its bit order is reversed to obtain a new index m, and then the positions of x(n) and x(m) are exchanged. The FFT calculation process is divided into multiple stages, each stage contains multiple groups of butterfly operations, and the sequence x is divided into multiple groups, each group contains s elements. For the elements in each group, they are further divided into two subgroups, each group contains m elements. In the calculation process, for each stage from s=2 to N (each time s is shifted left by one bit), m=s>>1 is calculated, and m represents half of the number of elements in each butterfly operation group. For traversing different butterfly operation groups, from i=0 to N-1, each group of the entire sequence is traversed with a step size of s. For the elements in the group from j=0 to m-1, the rotation factor t=W(s,j)*x[i+j+m] is calculated, where is the rotation factor weight, and then update x[i+j+m]=x[i+j]-t and x[i+j]=x[i+j]+t. After multiple iterations of butterfly operations, the input time domain discrete sequence x(n) is finally converted into the frequency domain sequence X(k). When s=N, that is, after the last iteration, the obtained X(k) contains the amplitude and phase information of the original signal at different frequency components. Each X(k) element corresponds to a frequency component, and its frequency f k By k= kΔf calculation, where the frequency resolution f s is the sampling frequency, k is the index of the frequency domain sequence, k = 0, 1, 2, ..., N-1. By analyzing the frequency domain sequence X(k), we can clearly see the distribution of different frequency components in the signal, so as to determine whether there is a characteristic frequency of the interference signal, and transmit the identification result to the interference signal processing module.

[0051] The temperature and pressure measurement module uses temperature sensors and pressure sensors to measure the temperature and pressure of the fluid in the pipeline in real time. When the temperature changes, the resistance value of the thermistor changes. By measuring the change in resistance value, the temperature of the fluid can be obtained; the pressure sensor is used to measure pressure. When the pressure in the pipeline acts on the elastic element, the elastic element deforms, and the strain gauge attached to its surface is strained, resulting in a change in resistance value. The pressure value is obtained by measuring the change in resistance value of the strain gauge. The measured temperature and pressure data will be transmitted to the interference signal processing module in real time to determine whether there is actual flow in the pipeline and assist in the judgment of interference signals.

[0052] The interference signal processing module receives the vibration parameters from the vibration monitoring module, the frequency identification results of the frequency identification module, and the temperature and pressure data of the temperature and pressure measurement module. The module makes a comprehensive judgment based on these data. When the vibration parameters exceed the normal range, the frequency identification results show that there is a characteristic frequency of the interference signal, and the temperature and pressure measurement data indicate that there is no flow in the pipeline, the signal is judged to be an interference signal. In the judgment process, a normal range is pre-set for the vibration parameters. When the vibration parameters transmitted by the vibration monitoring module exceed the range, it indicates that the pipeline vibration may affect the flow measurement. For the frequency identification results, the identified frequency components are compared with the pre-stored interference signal characteristic frequency library. If a matching frequency is found and its amplitude exceeds a certain threshold, it is considered that there is frequency interference. The temperature and pressure measurement data are used to determine whether there is actual flow in the pipeline. If it is determined to be an interference signal, the interference signal processing module will filter it out. After filtering out the interference signal, an accurate flow measurement signal is output. At the same time, in order to verify the quality of the filtered signal, the module will calculate the filtered signal y(n) and the historical data y hist The mean square error of (n) Where N is the data length, and the correlation coefficient with the instrument data is also calculated Where x(n) is the instrument data, and are the means of x(n) and y(n), respectively. When MSE>τ MSE and |ρ xy |<τ ρWhen one of the above conditions is met, it indicates that there is still a problem with the filtered signal, and it is necessary to restart the interference judgment process, adjust the filtering parameters, and judge and filter the interference signal again. Here, τ MSE and τ ρ are the mean square error threshold and correlation coefficient threshold, respectively, |ρ xy | is the absolute value of the correlation coefficient, which is used to measure the accuracy and reliability of the filtered signal. In this embodiment, the modules of the system work closely together. The signal receiving module accurately obtains the output signal of the vortex flowmeter, the vibration monitoring module monitors the pipeline vibration in real time, the frequency identification module deeply analyzes the signal frequency components, the temperature and pressure measurement module provides fluid state information, and the interference signal processing module comprehensively judges and processes the interference signal. At the same time, the accuracy of the output signal is ensured through the verification mechanism. During the entire operation process, the various modules jointly realize the anti-seismic and anti-power frequency interference functions of the vortex flowmeter in a complex industrial environment, which effectively improves the accuracy and reliability of flow measurement.

[0053] This embodiment shows in detail the working process of a vortex flowmeter anti-seismic and anti-power frequency interference system. By deeply explaining the working principle and operation process of each module, effective filtering of interference signals is achieved, thereby ensuring the accuracy of flow measurement. Furthermore, Figure 2 As shown, based on a vortex flowmeter anti-seismic and anti-power frequency interference system, the specific application steps of the vortex flowmeter anti-seismic and anti-power frequency interference method are as follows:

[0054] First, the signal receiving and collecting stage (S100) is entered. The signal receiving module continuously monitors the frequency signal output by the vortex flowmeter. The vortex flowmeter works on the principle of Karman vortex street. When the fluid flows through the vortex generator, alternating vortices are generated. The pressure change of the vortex causes the piezoelectric element to generate charges. After amplification, filtering and shaping, the frequency signal is output. The signal receiving module samples the signal at the sampling frequency, converts the analog signal into a digital signal, and then transmits these signals to the frequency identification module and the interference signal processing module to provide a data basis for subsequent analysis.

[0055] Then, the multi-source data acquisition stage (S200) is entered. The vibration sensor of the vibration monitoring module closely monitors the pipeline vibration. The vibration sensor converts the pipeline vibration into an electrical signal, and obtains parameters such as vibration amplitude and frequency through internal circuit processing, and transmits these vibration parameters to the interference signal processing module in real time; after the frequency recognition module receives the digital signal from the signal receiving module, it first quantizes the signal, and then uses the spectrum analysis algorithm to convert the time domain signal into a frequency domain signal. By analyzing the frequency domain signal, the frequency component in the signal is identified, and compared with the pre-stored interference signal characteristic frequency to determine whether there is an interference signal characteristic frequency, and finally the identification result is sent to the interference signal processing module; the temperature sensor and pressure sensor of the temperature and pressure measurement module start working, respectively measuring the temperature and pressure of the fluid in the pipeline, and transmitting the measurement data to the interference signal processing module.

[0056] Subsequently, the interference signal judgment stage (S300) is entered. The interference signal processing module comprehensively analyzes the vibration parameters from the vibration monitoring module, the frequency recognition results of the frequency recognition module, and the temperature and pressure data of the temperature and pressure measurement module, compares the vibration parameters with the normal range, determines whether the vibration is abnormal, checks whether there is an interference signal characteristic frequency in the frequency recognition results, and determines whether there is flow in the pipeline based on the temperature and pressure data. When one of the three conditions is met, the vibration parameter exceeds the normal range, the interference signal characteristic frequency exists, and there is no flow in the pipeline, the current signal is determined to be an interference signal.

[0057] Next, the interference signal filtering stage (S400) is entered. Once an interference signal is determined, the interference signal processing module inputs the signal containing interference into a filter for processing, thereby removing the interference signal and obtaining a relatively pure flow signal.

[0058] Finally, the result verification and output stage (S500) is entered. The interference signal processing module compares and analyzes the filtered flow signal with the historical measurement data and the instrument data in the same pipeline system to evaluate the signal quality. If the evaluation result shows that the signal quality meets the standard, the filtered flow signal is output as the final measurement result for use in flow monitoring, control and metering in industrial production. If the evaluation finds that there is a problem with the signal, such as a large difference from the historical data or an abnormal correlation with other instrument data, the interference judgment process is restarted, the filtering strategy is adjusted, and the interference signal is judged and filtered again until the output flow signal meets the requirements.

[0059] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A vortex flowmeter anti-seismic and anti-power frequency interference system, characterized in that: The system consists of: signal receiving module, vibration monitoring module, frequency identification module, temperature and pressure measurement module and interference signal processing module; The signal receiving module receives the frequency signal output by the vortex flowmeter in real time, and transmits it to the frequency identification module and the interference signal processing module; The vibration monitoring module uses a vibration sensor to monitor the pipeline vibration in real time and transmit the vibration parameters to the interference signal processing module; The frequency identification module uses a spectrum analysis algorithm to perform real-time analysis on the received frequency signal, identify the frequency components in the signal, determine the characteristic frequency of the interference signal, and transmit the identification result to the interference signal processing module; The temperature and pressure measurement module uses a temperature sensor and a pressure sensor to measure the temperature and pressure of the fluid in the pipeline in real time, and transmits the measurement data to the interference signal processing module; The interference signal processing module makes a comprehensive judgment based on the received vibration parameters, frequency identification results and temperature and pressure measurement data. If the vibration parameters are out of range, the frequency identification results show that there is a characteristic frequency of the interference signal, and the temperature and pressure measurement data show that there is no flow in the pipeline, then the signal is determined to be an interference signal, filtered out, and an accurate flow measurement signal is output, and the filtered signal y(n) and the historical data y are calculated. hist The mean square error of (n) Where N is the data length, and the correlation coefficient with the instrument data is calculated at the same time Where x(n) is the instrument data, and are the means of x(n) and y(n), respectively. When MSE>τ MSE and |ρ xy |<τ ρ When one of the above conditions is met, the interference judgment process is restarted, τ MSE and τ ρ are the mean square error threshold and correlation coefficient threshold, respectively, |ρ xy | is the absolute value of the correlation coefficient.

2. The system for vortex flowmeter to resist earthquake and power frequency interference according to claim 1 is characterized in that: The working principle of the vortex flowmeter in the signal receiving module is: Fluid flow and vortex formation: When the fluid flows into the measuring pipe of the vortex flowmeter, a columnar object is arranged in the measuring pipe perpendicular to the flow direction of the fluid, which is a vortex generator. When the fluid meets the vortex generator placed in the pipe, the vortex generator is hindered from flowing due to the viscosity of the fluid, thereby forming a boundary layer separation phenomenon. On both sides of the downstream of the vortex generator, vortices with opposite rotation directions are alternately generated, and the vortices are arranged into a regular vortex array, namely, the Karman vortex street; Relationship between vortex frequency and flow velocity: The formation frequency of the Karman vortex street is related to the flow velocity of the fluid, that is, the frequency of vortices alternately falling off from both sides of the vortex generator. According to fluid mechanics, the relationship between the vortex street frequency f and the fluid flow velocity v and the width d of the flow surface of the vortex generator is: Where St is the Strouhal number, which remains constant within the Reynolds number range. The Reynolds number Re is a dimensionless number that measures the flow state of the fluid. Where ρ is the fluid density, μ is the fluid dynamic viscosity, and when the Reynolds number Re is in the standard range, the Strouhal number St is considered a constant; Vortex detection and signal conversion: There is a piezoelectric element inside the vortex generator. When vortices are generated alternately, periodically changing pressure pulsations are generated around the vortex generator. The pressure pulsations act on the piezoelectric element. According to the piezoelectric effect, the piezoelectric element will generate an electric charge proportional to the pressure change. The charge generated by the piezoelectric element is amplified by a charge amplifier connected to it, and the weak charge signal is converted into a measurable voltage signal. The frequency of the voltage signal is the same as the vortex street frequency, which reflects the frequency of vortex shedding in the fluid, and the flow state of the fluid, that is, the vortex street frequency, is converted into an electrical signal.

3. The system for vortex flowmeter to resist earthquake and power frequency interference according to claim 2, characterized in that: The electrical signal output by the piezoelectric element in the vortex flowmeter is weak and contains interference components. The circuit signal is filtered to remove high-frequency and low-frequency noise, and the useful signal with the vortex frequency is retained. The amplifier circuit further amplifies the filtered signal, and the shaping circuit converts the amplified signal into a standard pulse signal, whose frequency is consistent with the vortex frequency. The processed pulse signal is received by the signal receiving module as the output signal of the vortex flowmeter, and the signal receiving module transmits the received signal to the frequency identification module and the interference signal processing module for subsequent flow calculation and interference analysis.

4. The system for vortex flowmeter to resist earthquake and power frequency interference according to claim 1, characterized in that: The specific steps of the frequency identification module are: Signal input: The frequency identification module receives the frequency signal output by the vortex flowmeter from the signal receiving module. The frequency signal is a time domain signal, i.e., a voltage and current waveform that changes with time, reflecting the vortex shedding frequency and interference information generated by the fluid flow detected by the vortex flowmeter; Pre-processing: Before inputting the signal into the spectrum analysis algorithm, the input signal is pre-processed, including sampling and quantizing the signal to convert the continuous analog signal into a discrete digital signal. The sampling process samples the input signal at equal intervals to ensure that the information of the original signal can be fully retained. The quantization process converts the continuous amplitude obtained by sampling into a discrete digital amplitude. Spectrum analysis: The pre-processed discrete signal is input into the spectrum analysis algorithm to extract the frequency component information in the signal.

5. The system for vortex flowmeter to resist earthquake and power frequency interference according to claim 4, characterized in that: The frequency identification module inputs the discrete digital amplitude after pre-processing into the spectrum analysis algorithm for quantization. The quantized signal is represented as x(n), where n=0, 1, 2, ..., N-1, and N is the number of sampling points. The quantized discrete signal sequence x(n) is used as input to the FFT algorithm of the spectrum analysis algorithm, and a bit reversal operation is performed on the input sequence x(n), that is, the element positions of the input sequence are rearranged according to the bit reversal principle. For the binary representation of n, its bit order is reversed to obtain a new index m, the positions of x(n) and x(m) are exchanged, and the bit-reversed sequence is iteratively calculated according to the butterfly structure, and finally the input time domain discrete sequence x(n) is converted into a frequency domain sequence X(k). When s=N, that is, after the last iteration, the obtained X(k) contains the amplitude and phase information of the original signal on different frequency components. Each X(k) element corresponds to a frequency component, and its frequency f k By k = kΔf calculation, where the frequency resolution f s is the sampling frequency, k is the index of the frequency domain sequence, k = 0, 1, 2, …, N-1.

6. The system for vortex flowmeter to resist earthquake and power frequency interference according to claim 5, characterized in that: The FFT algorithm iteratively calculates the bit-reversed sequence according to the butterfly structure. The FFT calculation process is divided into multiple stages, each stage contains multiple groups of butterfly operations, and the sequence x is divided into several groups, each group contains s elements. For the elements in each group, it is further divided into two subgroups, each group contains m elements. For s=2 to N, that is, each stage where s is shifted left by one bit calculates m=s>>1, where m represents half of the number of elements in each butterfly operation group. For traversing different butterfly operation groups i=0 to N-1, each group of the entire sequence is traversed with s as the step size: For elements j = 0 to m-1, calculate the rotation factor t = W(s, j) * x[i+j+m], where is the rotation factor weight; Update x[i+j+m]=x[i+j]-t; Update x[i+j]=x[i+j]+t.

7. A method for vortex flowmeter to resist earthquake and power frequency interference, applicable to the system for vortex flowmeter to resist earthquake and power frequency interference as claimed in any one of claims 1 to 6, characterized in that: The specific steps of this method are: S100, using a signal receiving module to receive in real time a frequency signal output by a vortex flowmeter; S200, acquire multi-source data, including pipeline vibration, digital signal spectrum analysis, fluid temperature and pressure; S300, when any one of the vibration interference condition, the frequency interference condition and the no-flow condition is met, the interference signal processing module determines that the current signal is an interference signal; S400, using an interference signal processing module to filter the determined interference signal, and output a pure flow signal after filtering; S500, compare and analyze the filtered flow signal with historical measurement data and instrument data in the same pipeline system.

8. The method for vortex flowmeter to resist earthquake and power frequency interference according to claim 7, characterized in that: The result verification process of S500 is as follows: Compare and analyze the filtered flow signal with historical measurement data and instrument data in the same pipeline system, and calculate the mean square error between the filtered signal and the historical data, as well as the correlation coefficient with the instrument data; Abnormal processing: When the mean square error is greater than the set threshold and the correlation coefficient is less than the set threshold, it indicates that there is still a problem with the filtered signal. Restart the interference judgment process, adjust the filtering parameters, and judge and filter the interference signal again; Output result: When the verification result does not meet any of the conditions, the filtered flow signal is output as the final measurement result.

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