CN114459679A - Method for measuring on-line dynamic response time of sensor - Google Patents
Method for measuring on-line dynamic response time of sensor Download PDFInfo
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Abstract
The invention relates to the technical field of performance test of sensors, and particularly discloses a method for measuring the online dynamic response time of a sensor, which comprises a test device, wherein the test device consists of a signal isolator, a signal regulating device, a data acquisition device and a data acquisition upper computer, a signal with noise of an on-site process medium is transmitted to the sensor to be detected, the sensor converts a mechanical signal into a 4-20mA current signal and sends the 4-20mA current signal into a DCS cabinet, a voltage signal corresponding to the 4-20mA current conversion is led into the data acquisition device after passing through the signal isolator and the signal regulating device from a sampling resistance terminal of the DCS cabinet through a lead, the signal regulating device comprises a high-pass filter and an anti-aliasing filter, the data acquisition device comprises a data acquisition card and an auxiliary power supply device, and the invention does not need to use a pressure, a differential pressure transmitter and a magnetic levitation sub liquid level meter from a process pipeline, And (4) disassembling the process container, namely realizing in-situ measurement.
Description
Technical Field
The invention relates to the technical field of performance test of sensors, in particular to a method for measuring the online dynamic response time of a sensor.
Background
The pressure and differential pressure transmitter is the most widely used instrument in industry, and is commonly used for measuring pressure, differential pressure, flow and liquid level in the process, and the magnetic float level gauge is used for measuring the liquid level of an important container of a nuclear power plant. Response time is an important performance indicator for pressure, differential pressure transmitters and magnetic float level gauges. The management guide RG1.118 issued by the united states nuclear authority specifies that security system response time measurements should be taken periodically to verify the total response time of all links of the system from sensor to actuator operation.
The 1E-level pressure, differential pressure transmitter and the magnetic float level meter are mainly used for measuring key parameters of a nuclear power plant process system and participating in important functions of nuclear power plant control and shutdown special protection, but after the meters are used for a period of time, the response time of the meters can be degraded, so that the response time of a reactor protection system and the response time of special safety facilities exceed the limit values.
The traditional instrument response time test is generally completed in a laboratory by adopting a step method, a pressure and differential pressure transmitter applies input pressure to the transmitter through a pressure step signal generating device, and the response time of the transmitter is determined by measuring the time delay from the initial position of an output signal of the transmitter to a certain fixed point. The magnetic float level meter measures the time difference between the trigger signal and the measured meter to determine the response time of the level meter, which causes inconvenience for the test and measurement.
Disclosure of Invention
The present invention is directed to a method for measuring the on-line dynamic response time of a sensor, so as to solve the problems mentioned in the background art.
In order to achieve the purpose, the invention provides the following technical scheme: a method for measuring the on-line dynamic response time of a sensor comprises a testing device, wherein the testing device consists of a signal isolator, a signal regulating device, a data acquisition device and a data acquisition upper computer, a signal with noise of an on-site process medium is transmitted to the sensor to be detected, the sensor converts a mechanical signal into a 4-20mA current signal and sends the 4-20mA current signal into a DCS cabinet, a voltage signal corresponding to the 4-20mA current conversion is led into the data acquisition device through a lead from a sampling resistance terminal of the DCS cabinet after passing through the signal isolator and the signal regulating device, the signal regulating device comprises a high-pass filter and an anti-aliasing filter, the data acquisition device comprises a data acquisition card and an auxiliary power supply device, and the data acquisition device sends acquired signal data into a data acquisition upper computer for analysis and processing in a USB communication mode;
the mechanism model which is obtained by comparing a large number of data experiments and is suitable for the pressure and differential pressure transmitter and the magnetic float level meter by the testing device is as follows:
wherein, ω isnThe natural frequency or undamped natural oscillation frequency of the system is obtained, and xi is the damping coefficient of the system;
the specific test method comprises the following steps:
s1, reading a noise signal;
s2, preprocessing segmented and filtered data;
s3, judging signal quality: if the signal quality is poor, returning to the step S2, processing the data again, and if the signal quality is good, being used for response time analysis;
s4, selecting a discrete Fourier transform method to obtain signal power spectral density analysis;
s5, judging a fitting curve: for the collected sensor signals, due to the influence of noise and other factors, the collected sensor signals cannot be completely matched with theoretical values, at the moment, a model is required to be established, system output is obtained according to different signal input modes and a transfer function, parameters are optimized by fitting a function through a least-square method, then fitting curve judgment is carried out, and if the fitting effect is not good, the step S4 is repeated to select again;
s6, if the fitting effect is good and the fitting effect accords with a second-order model, judging the response time;
s7, judging the system response time by the definition method: after the fitting function is obtained, the system response time, namely T, is obtained by using a system definition method2And T is2＝4/ξωn；
And S8, finally outputting the response time of the meter.
Preferably, step S4 specifically includes (1) the direct method: taking N observation data of a random sequence x (N) as an energy-limited sequence, directly calculating discrete Fourier transform of x (N) to obtain X (k), then taking the square of the amplitude value of the X (k), and dividing the square by N to be used as an estimation of a real power spectrum of the sequence x (N); (2) an indirect method: the autocorrelation function R (n) is estimated by the sequence x (n), then Fourier transform is carried out on R (n), and the power spectrum estimation of x (n) is obtained.
Preferably, the DCS cabinet is connected with a pressure and differential pressure transmitter or a magnetic float level meter, and when an object lacking signal fluctuation is measured using the magnetic float level meter, the measured signal fluctuation is caused from the outside, wherein the current-pressure converter is driven by a white noise signal generator during operation, and noise can be superimposed to the gas pressure of the gas storage tank by means of a 4-20mA current signal to generate a random pressure noise signal.
Preferably, the test device collects the test signal through the data collection device, when the test signal, especially the field noise signal, is interfered by external noise, the noise signal is weak, the signal amplification is needed, then before A/D conversion, high-frequency electrical noise is removed through sequential low-pass filtering, meanwhile, before signal analysis, amplitude spectrum analysis is carried out on the noise signal section by section, stability and linearity characteristics are checked, and for the interfered signal, section processing can be carried out, and abnormal signals are deleted.
Compared with the prior art, the invention has the beneficial effects that: the in-situ measurement can be realized without disassembling the pressure and differential pressure transmitter and the magnetic float level meter from the process pipeline and the process container; the pressure and differential pressure transmitter and the magnetic float level meter can be measured on line in real time when the nuclear power plant normally operates, and the normal use of the pressure and differential pressure transmitter and the magnetic float level meter is not influenced; the response time measured by the method also comprises the response time of the pressure and differential pressure transmitter instrument pressure leading pipe, and can be used for the nuclear power plant operating personnel to judge the performance degradation conditions of the pressure and differential pressure transmitter on line in real time;
drawings
FIG. 1 is a schematic diagram of the overall structure of a sensor response time testing device according to the present invention;
FIG. 2 is a schematic diagram of the noise introduction system of the present invention;
FIG. 3 is a schematic view of a noise introducing apparatus of the present invention;
FIG. 4 is a schematic diagram of the power spectral density fit of the present invention;
FIG. 5 is a block diagram of the structure of the online dynamic response time testing method of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1-5, the present invention provides a technical solution: a method for measuring the on-line dynamic response time of a sensor comprises a testing device, wherein the testing device consists of a signal isolator, a signal regulating device, a data acquisition device and a data acquisition upper computer, a signal with noise of an on-site process medium is transmitted to the sensor to be detected, the sensor converts a mechanical signal into a 4-20mA current signal and sends the 4-20mA current signal into a DCS cabinet, a voltage signal corresponding to the 4-20mA current conversion is led into the data acquisition device through a lead from a sampling resistance terminal of the DCS cabinet after passing through the signal isolator and the signal regulating device, the signal regulating device comprises a high-pass filter and an anti-aliasing filter, the data acquisition device comprises a data acquisition card and an auxiliary power supply device, and the data acquisition device sends acquired signal data into a data acquisition upper computer for analysis and processing in a USB communication mode;
the mechanism model which is obtained by comparing a large number of data experiments and is suitable for the pressure and differential pressure transmitter and the magnetic float level meter by the testing device is as follows:
wherein, ω isnThe natural frequency or undamped natural oscillation frequency of the system is obtained, and xi is the damping coefficient of the system;
the specific test method comprises the following steps:
s1, reading a noise signal;
s2, preprocessing segmented and filtered data;
s3, judging signal quality: if the signal quality is poor, returning to the step S2, processing the data again, and if the signal quality is good, being used for response time analysis;
s4, selecting a discrete Fourier transform method to obtain signal power spectral density analysis;
s5, judging a fitting curve: for the collected sensor signals, due to the influence of noise and other factors, the collected sensor signals cannot be completely matched with theoretical values, at the moment, a model is required to be established, system output is obtained according to different signal input modes and a transfer function, parameters are optimized by fitting a function through a least-square method, then fitting curve judgment is carried out, and if the fitting effect is not good, the step S4 is repeated to select again;
s6, if the fitting effect is good and the fitting effect accords with a second-order model, judging the response time;
s7, judging the system response time by the definition method: after the fitting function is obtained, the system response time, namely T, is obtained by using a system definition method2And T is2＝4/ξωn；
And S8, finally outputting the response time of the meter.
Further, step S4 specifically includes (1) the direct method: taking N observation data of a random sequence x (N) as an energy-limited sequence, directly calculating discrete Fourier transform of x (N) to obtain X (k), then taking the square of the amplitude value of the X (k), and dividing the square by N to be used as an estimation of a real power spectrum of the sequence x (N); (2) an indirect method: the autocorrelation function R (n) is estimated by the sequence x (n), then Fourier transform is carried out on R (n), and the power spectrum estimation of x (n) is obtained.
Further, the DCS cabinet is connected with a pressure and differential pressure transmitter or a magnetic float level meter, and when an object lacking signal fluctuation is measured using the magnetic float level meter, the measured signal fluctuation is caused from the outside, wherein the current-pressure converter is driven by a white noise signal generator during operation, and noise can be superimposed into the gas pressure of the gas storage tank by means of a 4-20mA current signal to generate a random pressure noise signal.
Furthermore, the test device collects test signals through the data acquisition device, when the test signals, particularly field noise signals, are interfered by external noise, the noise signals are weak, the signals need to be amplified, then high-frequency electrical noise is removed through low-pass filtering in sequence before A/D conversion, meanwhile, amplitude spectrum analysis is carried out on the noise signals section by section before signal analysis, stability and linear characteristic inspection is carried out, and segmented processing can be carried out on the interfered signals, and abnormal signals are deleted.
Example 1: the specific measurement steps for the pressure and differential pressure transmitter response time test are as follows:
s11, connecting the positive and negative terminals of the signal acquisition device to a standard resistor in the measurement loop;
s12, continuously acquiring pressure and differential pressure transmitter output signals through a signal acquisition device;
s13, storing the collected signals as a csv format data file;
and S14, calling a frequency domain method calculation program, and automatically calculating the response time of the measured pressure and the differential pressure transmitter.
Example 2: the response time test of the magnetic float liquid level meter comprises the following measurement steps:
s21, connecting an instrument gas source to a gas source input port of the signal generator;
s22, connecting the noise output port of the signal generator to the bottom of the container where the magnetic float level meter is located;
s23, turning on a power supply of the signal generator, and observing that gas is separated out from the bottom of the container;
s24, connecting the positive and negative terminals of the signal acquisition device to a standard resistor in the measurement loop;
s25, continuously acquiring output signals of the magnetic float through a signal acquisition device;
s26, storing the collected signals as a csv format data file;
and S27, calling a frequency domain method calculation program, and automatically calculating the response time of the measured pressure and the differential pressure transmitter.
Wherein, unit pressure transmitter response time is as follows:
the response time test of the pressure transmitter is carried out by adopting a slope method on the spot, and a large amount of laboratory data show that: the ramp method is close to the response time of the instrument measured by the traditional step method.
Shown in FIG. 3: the nozzle shutter is controlled to move up and down as shown in the figure by applying a 4-20mA current signal after electromagnetic conversion, and the pressure change is adjusted by the change of the opening degree, wherein the larger the current is, the smaller the distance between the plate and the nozzle is, namely, a pressure fluctuation signal is superposed on the inherent pressure.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (4)
1. A method for measuring the on-line dynamic response time of a sensor is characterized by comprising the following steps: the device comprises a testing device, wherein the testing device consists of a signal isolator, a signal adjusting device, a data acquisition device and a data acquisition upper computer, a signal with noise of a field process medium is transmitted to a sensor to be detected, the sensor converts a mechanical signal into a 4-20mA current signal and sends the 4-20mA current signal into a DCS cabinet, a voltage signal corresponding to the 4-20mA current conversion is led into the data acquisition device from a sampling resistor terminal of the DCS cabinet through a lead after passing through the signal isolator and the signal adjusting device, the signal adjusting device comprises a high-pass filter and an anti-aliasing filter, the data acquisition device comprises a data acquisition card and an auxiliary power supply device, and the data acquisition device sends acquired signal data into the data acquisition upper computer for analysis and processing in a USB communication mode;
the mechanism model which is obtained by comparing a large number of data experiments and is suitable for the pressure and differential pressure transmitter and the magnetic float level meter by the testing device is as follows:
wherein, ω isnThe natural frequency or undamped natural oscillation frequency of the system is set, ξ is the damping coefficient of the system, s is a Laplace operator, and K is a scale factor;
the specific test method comprises the following steps:
s1, reading a noise signal;
s2, preprocessing segmented and filtered data;
s3, judging signal quality: if the signal quality is poor, returning to the step S2, processing the data again, and if the signal quality is good, being used for response time analysis;
s4, selecting a discrete Fourier transform method to obtain signal power spectral density analysis;
s5, judging a fitting curve: for the collected sensor signals, due to the influence of noise and other factors, the collected sensor signals cannot be completely matched with theoretical values, at the moment, a model is required to be established, system output is obtained according to different signal input modes and a transfer function, parameters are optimized by fitting the function through a least-square method, then fitting curve judgment is carried out, and if the fitting effect is poor, the step S4 is repeated to select again;
s6, if the fitting effect is good and the fitting effect accords with a second-order model, judging the response time;
s7, judging the system response time by the definition method: after the fitting function is obtained, the system response time, namely T, is obtained by using a system definition method2And T is2＝4/ξωn；
And S8, finally outputting the response time of the meter.
2. The method for measuring the on-line dynamic response time of the sensor according to claim 1, wherein the method comprises the following steps: step S4 specifically includes (1) the direct method: taking N observation data of a random sequence x (N) as an energy-limited sequence, directly calculating discrete Fourier transform of x (N) to obtain X (k), then taking the square of the amplitude value of the X (k), and dividing the square by N to be used as an estimation of a real power spectrum of the sequence x (N); (2) an indirect method: the autocorrelation function R (n) of the sequence x (n) is estimated by using a multi-signal classification method, and then discrete Fourier transform is carried out on R (n) to obtain the power spectrum estimation of x (n).
3. The method for measuring the on-line dynamic response time of the sensor according to claim 1, wherein the method comprises the following steps: the DCS cabinet is connected with a pressure and differential pressure transmitter or a magnetic float level meter, when the magnetic float level meter is used for measuring an object lacking signal fluctuation, the measured signal fluctuation is caused from the outside, wherein the current-pressure converter is driven by a white noise signal generator during working, noise can be superposed into the gas pressure of the gas storage tank in a 4-20mA current signal mode, and random pressure noise signals are generated.
4. The method for measuring the on-line dynamic response time of the sensor according to claim 1, wherein the method comprises the following steps: the testing device collects testing signals through the data collecting device, when the testing signals, particularly field noise signals, are interfered by external noise, the noise signals are weak, the signals need to be amplified, then high-frequency electrical noise is removed through low-pass filtering in sequence before A/D conversion, meanwhile, amplitude spectrum analysis is carried out on the noise signals section by section before signal analysis, stability and linear characteristics are checked, and segmented processing can be carried out on the interfered signals, and abnormal signals are deleted.
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Citations (4)
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| WO2017178878A1 (en) * | 2016-04-13 | 2017-10-19 | Universitat Politecnica De Catalunya | A full time-domain method for analyzing two or more signals for assessing them as electromagnetic interference (emi) |
| CN108362436A (en) * | 2018-05-22 | 2018-08-03 | 三门核电有限公司 | A kind of Pressure and Difference Pressure Transmitter Response Time Test System and method |
| CN110657864A (en) * | 2019-10-08 | 2020-01-07 | 三门核电有限公司 | Sensor response time measuring method |
| US20200400485A1 (en) * | 2019-06-24 | 2020-12-24 | Analysis And Measurement Services Corporation | Methods and Apparatus for Calibration and Response Time Testing of Level Sensors |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017178878A1 (en) * | 2016-04-13 | 2017-10-19 | Universitat Politecnica De Catalunya | A full time-domain method for analyzing two or more signals for assessing them as electromagnetic interference (emi) |
| CN108362436A (en) * | 2018-05-22 | 2018-08-03 | 三门核电有限公司 | A kind of Pressure and Difference Pressure Transmitter Response Time Test System and method |
| US20200400485A1 (en) * | 2019-06-24 | 2020-12-24 | Analysis And Measurement Services Corporation | Methods and Apparatus for Calibration and Response Time Testing of Level Sensors |
| CN110657864A (en) * | 2019-10-08 | 2020-01-07 | 三门核电有限公司 | Sensor response time measuring method |
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