Spectral analysis and elimination method and system for water vapor interference of laser sensor

Abstract

The invention provides a spectral analysis and elimination method and system for water vapor interference of a laser sensor, and the method comprises the steps: scanning a spectral interval containing a methane characteristic absorption peak, and obtaining an original light intensity signal curve A composed of N discrete wavelength points; m wavelength point data outside the methane characteristic absorption peak range in the original light intensity signal curve A are selected, and a reference signal curve B is generated through a linear regression algorithm; performing point-by-point difference proportion operation on the original light intensity signal curve A and the reference signal curve B to obtain an absorption intensity curve C; counting the number of wavelength points of which the absorption intensity values continuously exceed a preset threshold value T in the methane characteristic absorption peak range of the absorption intensity curve C; and when the number of the wavelength points continuously exceeding the threshold value T reaches a set number K, judging that methane gas exists. Under the environment that methane gas and water vapor are mixed together, the accuracy of the methane concentration result detected by the sensor can be effectively improved; and the false alarm rate of the sensor in a pure water vapor interference environment is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of gas detection, and particularly relates to a spectrum analysis and elimination method and system for water vapor interference of a laser sensor. BACKGROUND

[0002] Currently, laser detection mainly adopts tunable diode laser absorption spectroscopy (TDLAS) technology, which performs concentration inversion through a characteristic absorption peak near 1653 nm.

[0003] The laser sensor mainly detects whether toxic or flammable gas leaks, and the specific use and installation are basically at a position where gas is prone to leak. However, if the humidity at the detection site is high, water vapor interference cannot be avoided, which causes pollution and influence on the light path of the sensor, resulting in a decrease in the sensitivity of the sensor or false positives, false negatives, and the like in the case of only water vapor interference or the case of simultaneous mixing of flammable or toxic gas to be detected and water vapor interference. Water molecules have continuous absorption in the 1550-1750 nm waveband, and water vapor condensation causes light intensity attenuation.

[0004] Currently, there are two common solutions, one of which is to add a hydrophobic filter membrane, and the other of which is to set up a gas chamber heating device. However, adding a hydrophobic filter membrane causes the transmittance of the gas to be detected to decrease with increasing humidity, and when the water vapor concentration is too high, water droplets are easily condensed on the surface of the filter screen, so that the gas to be detected cannot enter the inside of the detection gas chamber. Adding a gas chamber heating device causes an increase in power consumption, which in turn shortens the service life of the sensor.

[0005] As described above, passive protection cannot solve the spectral overlap of water vapor and the gas to be detected, resulting in a large error in the detection result. SUMMARY

[0006] The present application aims to provide a spectrum analysis and elimination method and system for water vapor interference of a laser sensor to solve the problems raised in the background.

[0007] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0008] The spectrum analysis and elimination method for water vapor interference of a laser sensor comprises the following steps:

[0009] Scanning a spectral interval containing a methane characteristic absorption peak to obtain an original light intensity signal curve A composed of N discrete wavelength points;

[0010] Selecting M wavelength point data outside the range of the methane characteristic absorption peak in the original light intensity signal curve A, and generating a reference signal curve B through a linear regression algorithm;

[0011] The original light intensity signal curve A and the reference signal curve B are subjected to point-by-point difference proportional operation to obtain an absorption intensity curve C;

[0012] The number of wavelength points in the absorption intensity curve C whose absorption intensity values continuously exceed the preset threshold T in the methane characteristic absorption peak range is counted;

[0013] When the number of wavelength points continuously exceeding the threshold T reaches a set number K, it is determined that methane gas exists.

[0014] Optionally, the reference signal curve B is generated through a linear regression algorithm, and the linear regression algorithm is a least square method. The slope k and the intercept b of the reference signal curve B are calculated through the following formula:

[0015]

[0016] Where x is the wavelength point serial number, y is the corresponding light intensity value, and N≥20;

[0017] Then, the linear equation of the reference signal curve B can be obtained through the above formula and the known collected data:

[0018] y=kx+b.

[0019] Optionally, the original light intensity signal curve A and the reference signal curve B are subjected to point-by-point difference proportional operation to obtain the absorption intensity curve C, wherein

[0020] The absorption intensity value of the i-th wavelength point is C i :

[0021]

[0022] Optionally, in the step of counting the number of wavelength points in the absorption intensity curve C whose absorption intensity values continuously exceed the preset threshold T in the methane characteristic absorption peak range,

[0023] The preset threshold T is a dynamic adjustable parameter, which is set to an initial default value and then is adaptively adjusted according to the environmental humidity sensor data.

[0024] Optionally, the adaptive adjustment rule according to the environmental humidity sensor data is as follows:

[0025] When the environmental relative humidity is greater than or equal to 80%, the threshold T is increased by 10% to 20%;

[0026] When the environmental relative humidity is less than or equal to 30%, the threshold T is decreased by 5% to 10%.

[0027] Optionally, the method further comprises:

[0028] When the condition is met for the first time for the continuous K wavelength points, the concentration of the methane gas is calculated.

[0029] If the concentration of methane is greater than zero and the fluctuation range is less than or equal to 15% for P consecutive times, it is determined that the methane alarm is triggered.

[0030] Optionally, a tunable diode laser is used to scan a spectral interval containing a methane characteristic absorption peak to obtain an original light intensity signal curve A composed of N discrete wavelength points.

[0031] A laser sensor water vapor interference spectrum analysis and elimination system, comprising:

[0032] An original light intensity signal curve A generation module is configured to scan a spectral interval containing a methane characteristic absorption peak to obtain an original light intensity signal curve A composed of N discrete wavelength points.

[0033] A reference signal curve B generation module is configured to select M wavelength point data outside the methane characteristic absorption peak range in the original light intensity signal curve A and generate a reference signal curve B through a linear regression algorithm.

[0034] An operation module is configured to perform point-by-point difference ratio operation on the original light intensity signal curve A and the reference signal curve B to obtain an absorption intensity curve C.

[0035] A statistical module is configured to count the number of wavelength points whose absorption intensity values in the absorption intensity curve C continuously exceed a preset threshold T within the methane characteristic absorption peak range.

[0036] A judgment module is configured to determine that there is methane gas when the number of wavelength points continuously exceeding the threshold T reaches a set number K.

[0037] Optionally, the system further comprises an environmental compensation module with a built-in temperature and humidity sensor and a threshold self-adaptive adjustment algorithm, configured to perform:

[0038] When the environmental relative humidity is greater than or equal to 80%, the threshold T is adjusted upward by 10% to 20%.

[0039] When the environmental relative humidity is less than or equal to 30%, the threshold T is adjusted downward by 5% to 10%.

[0040] Optionally, the system further comprises a historical data comparison module configured to store a typical water vapor interference mode feature library, wherein the data of the typical water vapor interference mode feature library includes humidity values and threshold T corresponding to current humidity values, and the preset threshold T is adjusted according to the humidity value detected by the humidity sensor.

[0041] Compared with the prior art, the application provides a water vapor interference elimination method for methane detection and a methane detection system, the method comprising the following steps: scanning a spectral interval containing a methane characteristic absorption peak to obtain an original light intensity signal curve A composed of N discrete wavelength points; selecting M wavelength point data outside the methane characteristic absorption peak range in the original light intensity signal curve A, and generating a reference signal curve B through a linear regression algorithm; performing point-by-point difference ratio operation on the original light intensity signal curve A and the reference signal curve B to obtain an absorption intensity curve C; counting the number of wavelength points whose absorption intensity values in the methane characteristic absorption peak range continuously exceed a preset threshold T; and determining that methane gas exists when the number of wavelength points continuously exceeding the threshold T reaches a set number K. Through the above method, in an environment where methane gas and water vapor are mixed together, the accuracy of the sensor detection result of the methane concentration can be effectively improved, and the false positive rate of the sensor in a pure water vapor interference environment can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 It is an original signal and fitting curve comparison chart.

[0043] Figure 2 It is an absorption intensity curve generation schematic diagram.

[0044] Figure 3 It is a typical water vapor interference mode schematic diagram.

[0045] Figure 4 It is an effective point distribution law under different methane concentrations.

[0046] Figure 5 It is a flowchart of a water vapor interference elimination method for methane detection

[0047] Figure 6 It is a methane concentration data result chart measured by a sensor in an environment where methane gas and water vapor are mixed together.

[0048] Figure 7 It is a methane concentration data result chart measured by a sensor in a pure water vapor interference environment. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0050] Furthermore, elements in this invention are referred to as being "fixed to" or "set on" another element, which may be directly on the other element or may also include an intervening element. When an element is considered to be "connected" to another element, it may be directly connected to the other element or may also include an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementations.

[0051] It should be noted that the technical solution provided in this application is applicable to the handling of water vapor interference by any gas sensor, such as methane, hydrogen, acetylene, ethylene, ammonia, hydrogen sulfide, etc. This application takes methane as an example to elaborate on the technical solution of this application. The technical solution of this application is also applicable to the detection of other gases.

[0052] Specifically, taking methane as an example, in order to solve the problem of false alarms or missed alarms of household methane laser sensors under water vapor interference, and to ensure that the sensor can work normally under various water vapor interference conditions, the technical solution of this application is proposed as follows:

[0053] Please see Figure 1 - Figure 7 This invention provides a method for spectral analysis and elimination of water vapor interference in an alkyl laser sensor, comprising: steps S101-S105:

[0054] Step S101. Scan the spectral range containing the characteristic absorption peak of methane to obtain the original light intensity signal curve A composed of N discrete wavelength points.

[0055] In this embodiment, scanning the spectral range containing the characteristic absorption peak of methane can be achieved using a tunable diode laser, for example: laser: NELNLK1 B6EAAA (center wavelength 1653.7nm), detector: Hamamatsu G12180-010A (response bandwidth 10MHz); utilizing the characteristics and principles of methane absorption of specific spectra, data can be collected at the sensor receiver end, such as... Figure 1 The original light intensity signal curve A, as shown Figure 1 As shown, the waveform of the original light intensity signal curve A is actually obtained by plotting the voltage signal data corresponding to 100 scanning points at different wavelengths collected by the laser receiver. By controlling the laser's operating current and temperature, the methane absorption wavelength range is controlled between 40 and 60 scanning points.

[0056] The original light intensity signal curve A is the signal waveform after methane gas is present in the sensor's optical path and absorbs a specific wavelength. The higher the methane concentration, the greater the absorption intensity, and the more obvious the concave part of the original light intensity signal curve A is.

[0057] Step S102. Selecting M wavelength point data in the original light intensity signal curve A outside the range of the methane characteristic absorption peak, and generating a reference signal curve B by linear regression algorithm.

[0058] In this embodiment, the data actually collected by step S101 is fitted to obtain the reference signal curve B without methane absorption interference. As shown in Figure 1 , the reference signal curve B is composed of the data of the two end straight line parts of the original light intensity signal curve A, i.e. Figure 1 The data of less than 40 points and more than 60 points on the X-axis are obtained by fitting, which represents the signal waveform curve without methane gas absorption in the optical path.

[0059] In this embodiment, the data of the reference signal curve B without methane interference is obtained by fitting through step S102 after collecting the data of the original light intensity signal curve A each time. Therefore, two curve data, i.e. the original light intensity signal curve A and the reference signal curve B, are finally obtained by data collection in each detection process.

[0060] Step S103. Point-by-point difference ratio operation is performed on the original light intensity signal curve A and the reference signal curve B to obtain the absorption intensity curve C.

[0061] In this embodiment, the absorption intensity value of each data point on the Y-axis corresponding to the original light intensity signal curve A and the reference signal curve B in Figure 1 is calculated by the formula: to obtain the absorption intensity value of the i-th wavelength point as C i , and the absorption intensity curve C is generated, taking Figure 1 for example, in combination with each data point on the Y-axis corresponding to the original light intensity signal curve A and the reference signal curve B in Figure 1 , the absorption intensity curve as shown in Figure 2 is obtained.

[0062] Figure 2 The absorption intensity value of each point on the curve as shown in Figure 1 is The difference or ratio of the Y-axis corresponding to the original light intensity signal curve A and the reference signal curve B at each current scanning point in

[0063] is converted into the absorption intensity curve, and the purpose of the conversion is to more intuitively and conveniently perform subsequent data processing and related condition judgment. Figure 1 Figure 2 In this embodiment, the absorption intensity value of each data point on the original light intensity signal curve A in is one-to-one corresponding to the current scanning point in

[0064] . Figure 3As shown: in the X-axis 40 to 60 point interval (i.e. near the absorption peak) the number of data points collected relative to the number of discrete points below the fitting curve is less or very small, and all water vapor interference data substantially meet this regularity, such as Figure 4 As shown: in the X-axis 40 to 60 point interval (i.e. near the absorption peak) the number of data points collected relative to the number of discrete points below the fitting curve is less or very small, and all water vapor interference data substantially meet this regularity, such as

[0065] Step S104. Count the number of wavelength points whose absorption intensity values exceed the preset threshold T continuously in the range of the methane characteristic absorption peak in the absorption intensity curve C.

[0066] Using Figure 3 Figure 4 Based on the regularity of water vapor interference detection, in this embodiment, the water vapor interference situation analysis and exclusion determination is carried out by the following method, including steps S1041-S1042:

[0067] Step S1041. Determine whether it is interference or there is measurement gas by judging the number of points below the fitting curve.

[0068] Step S1042. Take Figure 2 For example, by comparing the absorption intensity values of the data points corresponding to the X-axis 40 to 60 points of the absorption intensity curve from 40 points to 60 points in turn with the absorption intensity threshold value (for example, 50) to determine whether the number of points below the fitting curve is valid and record the number of valid points at the same time.

[0069] Step S105. When the number of wavelength points whose absorption intensity values exceed the threshold T continuously reaches the set number K, it is determined that there is methane gas.

[0070] In this embodiment, the number of valid points is used as the basis for judgment, and when the number of valid points reaches or meets the set threshold of valid points (for example, 6), it is considered that there is methane gas and subsequent processing is carried out, otherwise it is determined to be water vapor interference.

[0071] In this embodiment, the difference ratio (absorption intensity) of the absorption intensity curve in the absorption wavelength range is positive and greater than a certain threshold (such as 50, which is a value given according to the test effect in actual test, and can be flexibly set, and the reason for introducing the threshold value to be a certain value instead of 0 is to exclude the error between the data curve A and the fitting curve B when there is no methane) indicates that the actual measured data point is below the fitting curve data, and the number of points greater than the threshold value exceeds the set number continuously, indicating that there is methane absorption, otherwise it is water vapor interference or no methane.

[0072] In this embodiment, refer to Figure 5As shown, first, the laser receiving end collects actual waveform curve A data; standard data curve B without methane absorption is fitted according to the collected curve A data; the two sets of data curves A and B are used to obtain absorption intensity waveform curve C through specific calculation, and the X-axis point position mark field PiontAddr=40; the absorption intensity value corresponding to the X-axis point position mark field PiontAddr point as shown is compared with a threshold value (such as 50): Figure 2

[0073] If greater than the threshold value 50, the effective point number count mark field Count is incremented by 1, and the X-axis point position mark field PiontAddr is incremented by 1;

[0074] If less than the threshold value 50, the effective point number count mark field Count is cleared, and counting from 0 is restarted, and the X-axis point position mark field PiontAddr is incremented by 1;

[0075] It is judged whether the X-axis point position mark field PiontAddr is greater than 60:

[0076] If less than 60, the absorption intensity value corresponding to the X-axis point position mark field PiontAddr point as shown is compared with a threshold value (such as 50): Figure 2

[0077] If greater than 60, the comparison task of the corresponding absorption intensity and the threshold value on the 40 to 60 point positions is completed, and the process ends;

[0078] It is judged whether the continuous effective point count Count is greater than 6:

[0079] If Count is greater than 6, it means that there is a target gas to be measured, and subsequent data processing and calculation are performed to obtain concentration effective data value, and the concentration effective value field MetCount is incremented by 1 (if it is incremented to 5, it is maintained and no longer incremented by 1);

[0080] If Count is less than 6, it means that there is no target gas to be measured, and subsequent processing and calculation are exited, and the concentration effective value field MetCount is cleared;

[0081] It is judged whether the concentration effective value field MetCount is greater than or equal to 5:

[0082] If MetCount is greater than or equal to 5, the measured concentration value is output and the program ends;

[0083] If MetCount is less than 5, the concentration output is zero and the program ends.

[0084] ​​In one specific implementation, in the step of generating the reference signal curve B using a linear regression algorithm, the linear regression algorithm is the least squares method, and the slope k and intercept b of the reference signal curve B are calculated using the following formulas:

[0085]

[0086] Where x is the wavelength point number, y is the corresponding light intensity value, and N≥20;

[0087] Using the above formula and the known acquired data, the linear formula for the reference signal curve B can be obtained:

[0088] y = kx + b.

[0089] In this embodiment, the least squares linear fitting algorithm is used: the least squares method is a mathematical optimization technique that finds the best function match for the data by minimizing the sum of squared errors. In linear fitting, the least squares method is used to find a straight line such that the sum of the squared perpendicular distances from all data points to that line is minimized. As described above, the original acquired waveform ( Figure 1 The data from the straight sections at both ends of the original light intensity signal curve A) are used to solve for the slope k and intercept b of the standard straight-line waveform (reference signal curve B) without methane interference using the least squares formula. This yields the straight-line formula and the data for each point on the line. The specific application formula is as follows:

[0090]

[0091] In the above formula, the amount of data N = 80 (below) Figure 1 (100 scan points minus 20 points in the middle range of 40-60);

[0092] x = down Figure 1 Current scan point values ​​(0-39, 60-99);

[0093] y = down Figure 1 The current scanning point value corresponds to the voltage value on the Y-axis;

[0094] Using the above formula and the known collected data, the linear formula for the reference signal curve B can be obtained: y = kx + b.

[0095] In this embodiment, combined with the appendix Figure 1 Appendix Figure 2 Explanation of the fitting calculation for the absorption intensity curve C:

[0096] Will Figure 1 and Figure 2 Each point on the curve is denoted by (X, Y), where X represents the x-coordinate and Y represents the y-coordinate. Then, we know that:

[0097] Each point data on the original light intensity signal curve A A(0, Y0), A(1, Y1), A(2, Y2)…A(97, Y97), A(98, Y98), A(99, Y99);

[0098] Each point data on the reference signal curve B B(0, Y0), B(1, Y1), B(2, Y2)…B(97, Y97), B(98, Y98), B(99, Y99);

[0099] Then each point data on the absorption intensity curve C is calculated by formula 1-A / B as follows:

[0100] C(0, Y0)=1-A(Y0) / B(Y0);

[0101] C(1, Y1)=1-A(Y1) / B(Y1);

[0102] C(2, Y2)=1-A(Y2) / B(Y2);

[0103] …

[0104] C(97, Y97)=1-A(Y97) / B(Y97);

[0105] C(98, Y98)=1-A(Y98) / B(Y98);

[0106] C(99, Y99)=1-A(Y99) / B(Y99);

[0107] The absorption intensity curve 0-99 scanning current point position corresponding data: C(Y0), C(Y1), C(Y2)…C(Y97), C(Y98), C(Y99) can be obtained;

[0108] Then:

[0109] C(Y0)=A(Y0) and B(Y0) at 0 point position difference ratio;

[0110] C(Y1)=A(Y1) and B(Y1) at 1 point position difference ratio;

[0111] C(Y2)=A(Y2) and B(Y2) at 2 point position difference ratio;

[0112] …

[0113] C(Y97)=A(Y97) and B(Y97) at 97 point position difference ratio;

[0114] C(Y98)=A(Y98) and B(Y98) at 98 point position difference ratio;

[0115] C(Y99) = A(Y99) - B(Y99) / B(Y99)

[0116] The data values C(Y0), C(Y1), C(Y2)…C(Y97), C(Y98), C(Y99) on the absorption intensity curve represent the difference between the actual data line and the standard methane-free data line at each scanning point, and the calculated data is represented on the coordinate graph, i.e. Figure 2 ;

[0117] Therefore, by Figure 1 and Figure 2 it can be known that the difference in the absorption wavelength range is larger, and the difference in the middle point of the absorption wavelength range is the largest. This difference value can be used as the absorption intensity of methane at this point. The absorption intensity near the absorption wavelength increases with the increase of the methane concentration.

[0118] In a specific embodiment, the step of counting the number of wavelength points whose absorption intensity values exceed the preset threshold T in the methane characteristic absorption peak range is performed. The preset threshold T is a dynamic adjustable parameter, which is initially set to a default value and then adjusted adaptively according to the environmental humidity sensor data.

[0119] In the embodiment, the adjustment of the above-mentioned preset threshold T as a dynamic adjustable parameter is specifically performed according to the adaptive adjustment rule based on the environmental humidity sensor data as follows:

[0120] When the environmental relative humidity is ≥80%, T is adjusted upwards by 10% to 20%;

[0121] When the environmental relative humidity is ≤30%, T is adjusted downwards by 5% to 10%.

[0122] It can be understood that the greater the humidity, the greater the preset threshold T, and the smaller the humidity, the smaller the preset threshold T. In this way, the influence of water vapor on the accuracy of the detection result can be better reduced.

[0123] In a specific embodiment, the method further comprises:

[0124] When the condition is met for the first time, the concentration of the methane gas is calculated;

[0125] If the methane concentration values obtained by calculating the concentration of the methane gas for P consecutive times are all greater than zero and the fluctuation range is ≤15%, the methane alarm is confirmed.

[0126] In this embodiment, in order to exclude false alarm conditions caused by water vapor and other causes with extremely small probability, a processing logic for multiple counting of the concentration effective value (calculated concentration value is not zero) is further added, and whether the measured concentration value is real and effective is judged according to whether the counting value exceeds the set threshold (for example, 5), and finally reported and output. When the concentration effective value is counted for 5 times, the counting value is kept and no longer counted, and the next effective concentration value is directly reported. If the counting is 3 or 4 times, if the concentration value is detected to be zero at this time, the counting is cleared, and the counting is restarted when the next effective concentration value appears. That is, the processing logic only counts and judges when the first effective concentration value appears. If the gas to be measured exists all the time, the concentration value after more than 5 times of counting is directly output, without affecting the real-time performance of the measurement data.

[0127] The laser sensor water vapor interference spectrum analysis and elimination method provided by the application can more accurately detect the concentration of methane in an environment where methane gas and water vapor are mixed together, can reduce the false alarm rate of the sensor in a pure water vapor interference environment, and can detect the concentration in a normal environment with a higher detection index or a lower false alarm rate.

[0128] In a second aspect, the embodiment provides a laser sensor water vapor interference spectrum analysis and elimination system, comprising:

[0129] An original light intensity signal curve A generation module is configured to scan a spectrum interval containing a methane characteristic absorption peak to obtain an original light intensity signal curve A composed of N discrete wavelength points;

[0130] A reference signal curve B generation module is configured to select M wavelength point data outside the methane characteristic absorption peak range in the original light intensity signal curve A and generate a reference signal curve B through a linear regression algorithm;

[0131] An operation module is configured to perform point-by-point difference ratio operation on the original light intensity signal curve A and the reference signal curve B to obtain an absorption intensity curve C;

[0132] A statistical module is configured to count the number of wavelength points whose absorption intensity values in the absorption intensity curve C continuously exceed a preset threshold T in the methane characteristic absorption peak range;

[0133] A judgment module is configured to determine that methane gas exists when the number of wavelength points whose absorption intensity values continuously exceed the threshold T reaches a set number K.

[0134] In a specific implementation, the system further comprises an environment compensation module with a built-in temperature and humidity sensor and a threshold self-adaptive adjustment algorithm, configured to perform:

[0135] When the relative humidity of the environment is ≥80%, T should be increased by 10% to 20%.

[0136] When the relative humidity is ≤30%, adjust temperature (T) by 5% to 10%.

[0137] By making the above adjustments, the threshold T in this application can be adaptively adjusted according to changes in ambient relative humidity, thereby reducing the false alarm rate of methane leak detection.

[0138] In one specific embodiment, it further includes: a historical data comparison module for storing a typical water vapor interference pattern feature library, wherein the data in the typical water vapor interference pattern feature library includes: humidity value and a threshold T corresponding to the current humidity value, and the preset threshold T is adjusted according to the humidity value detected by the humidity sensor.

[0139] In this embodiment, different humidity environments are simulated in the laboratory to record the fingerprint characteristics of water vapor interference; the current ambient humidity is obtained through a humidity sensor; the threshold T corresponding to the current ambient humidity is matched in the feature library of typical water vapor interference patterns, and the matched threshold T is used as the preset threshold T.

[0140] For example: Scenario: Steam is generated when boiling water in the kitchen. At this time, the humidity will rise sharply (e.g., the humidity increases by 60%). The light intensity signal fluctuates due to the interference of the steam. The interference features under 60% humidity are retrieved from the feature library. It is found that the current signal fluctuation matches the "high humidity water vapor interference" mode. The threshold is automatically increased from 50 to 65. At this time, the spectral analysis and elimination method of water vapor interference of laser sensor provided in this application (steps S101-S105) can be used to detect methane leaks under the condition of a preset threshold T of 65, thereby reducing the false alarm rate of methane leak detection.

[0141] It is evident that the solution proposed in this application can avoid misidentifying steam as methane leakage. Furthermore, compared to the fixed threshold solution, the technical solution proposed in this application reduces the false alarm rate for methane leakage detection.

[0142] Experimental example (see Figure 6 , Figure 7 )

[0143] Figure 6 The data shows the methane concentration measured by the sensor in an environment where methane gas and water vapor are mixed. There are a total of 3,527 continuous detection concentration data points, of which 3,507 are valid and 20 are invalid. Therefore, the percentage of valid measured concentrations is 99.4%.

[0144] Figure 7For the methane concentration data results of sensor measurement in the simple water vapor interference environment, the total number of continuously detected concentration data is 2404, the number of correctly recognized no-methane gas concentration data is 2404 (i.e., the correct concentration measurement value is all 0% LEL), the number of false concentration data is 0, and the water vapor interference exclusion rate is 100%.

[0145] According to an embodiment of the present application, a server is provided, comprising: a processor; a memory for storing processor-executable instructions; wherein the processor is configured to invoke the instructions stored in the memory to perform the management method of the credit system data.

[0146] According to an embodiment of the present application, a computer readable storage medium is provided, which stores computer program instructions, the computer program instructions are executed by a processor to implement the management method of the credit system data.

[0147] The present application can be a method, device, system and / or computer program product. The computer program product can include a computer readable storage medium having computer readable program instructions stored therein, the computer readable program instructions are used to execute various aspects of the present application.

[0148] It is apparent to those skilled in the art that the present application is not limited to the details of the foregoing exemplary embodiments, and can be realized in other particular forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all respects as illustrative and not restrictive, the scope of the present application being defined by the appended claims rather than the above description, and it is intended that all changes coming within the meaning and range of equivalency of the claims are embraced therein. Any reference signs in the claims should not be construed as limiting the claims to the figures in which the reference signs are used.

[0149] In addition, it should be understood that, although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that those skilled in the art can understand.

Claims

1. A method for spectral analysis and elimination of water vapor interference of a laser sensor, characterized in that, The method comprises the following steps: scanning a spectral interval containing a methane characteristic absorption peak to obtain an original light intensity signal curve A composed of N discrete wavelength points; selecting M wavelength point data outside the range of the methane characteristic absorption peak in the original light intensity signal curve A, and generating a reference signal curve B through a linear regression algorithm; performing point-by-point difference proportional operation on the original light intensity signal curve A and the reference signal curve B to obtain an absorption intensity curve C; counting the number of wavelength points whose absorption intensity values continuously exceed a preset threshold T within the range of the methane characteristic absorption peak; when the number of wavelength points continuously exceeding the threshold T reaches a set number K, it is determined that there is methane gas.

2. The method for laser sensor water vapor interference spectrum analysis and elimination according to claim 1, characterized in that, In the step of generating the reference signal curve B through a linear regression algorithm, the linear regression algorithm is a least square method, and the slope k and the intercept b of the reference signal curve B are calculated through the following formula: wherein x is the wavelength point number, y is the corresponding light intensity value, and N≥20; then the linear equation of the reference signal curve B can be obtained through the above formula and the known collected data: y=kx+b.

3. The method for laser sensor water vapor interference spectrum analysis and elimination according to claim 1, characterized in that, In the step of performing point-by-point difference proportional operation on the original light intensity signal curve A and the reference signal curve B to obtain the absorption intensity curve C, The absorption intensity value of the ith wavelength point is C i :

4. The method for laser sensor water vapor interference spectrum analysis and elimination according to claim 1, characterized in that, In the step of counting the number of wavelength points whose absorption intensity values continuously exceed the preset threshold T within the range of the methane characteristic absorption peak, the preset threshold T is a dynamic adjustable parameter, which is set to an initial default value and then adaptively adjusted according to the environmental humidity sensor data.

5. The method for laser sensor water vapor interference spectrum analysis and elimination according to claim 4, characterized in that, The adaptive adjustment rule according to the environmental humidity sensor data is as follows: when the environmental relative humidity is greater than or equal to 80%, the threshold T is increased by 10% to 20%; when the environmental relative humidity is less than or equal to 30%, the threshold T is decreased by 5% to 10%.

6. The method for laser sensor water vapor interference spectrum analysis and elimination according to claim 1, characterized in that, The method further comprises the following steps: when K consecutive wavelength points meet the condition for the first time, the concentration of the methane gas is calculated; if the methane concentration values obtained by calculating the concentration of the methane gas for P consecutive times are all greater than zero and the fluctuation range is less than or equal to 15%, it is determined that the methane alarm is confirmed.

7. The method for laser sensor water vapor interference spectrum analysis and elimination according to claim 1, characterized in that, A tunable diode laser is used to scan a spectral interval containing a methane characteristic absorption peak to obtain an original light intensity signal curve A composed of N discrete wavelength points.

8. A system for spectral analysis and elimination of water vapor interference in a laser sensor, characterized in that The method comprises the following steps: an original light intensity signal curve A generation module is configured to scan a spectral interval containing a methane characteristic absorption peak to obtain an original light intensity signal curve A composed of N discrete wavelength points; a reference signal curve B generation module is configured to select M wavelength point data outside the range of the methane characteristic absorption peak in the original light intensity signal curve A, and generate a reference signal curve B through a linear regression algorithm; an operation module is configured to perform point-by-point difference proportional operation on the original light intensity signal curve A and the reference signal curve B to obtain an absorption intensity curve C; a counting module is configured to count the number of wavelength points whose absorption intensity values continuously exceed a preset threshold T within the range of the methane characteristic absorption peak; a judgment module is configured to determine that there is methane gas when the number of wavelength points continuously exceeding the threshold T reaches a set number K.

9. The system for spectral analysis and elimination of water vapor interference with laser sensor according to claim 7, characterized in that, Further comprising: an environmental compensation module with a built-in temperature and humidity sensor and a threshold adaptive adjustment algorithm, configured to perform the following steps: when the environmental relative humidity is greater than or equal to 80%, the threshold T is increased by 10% to 20%. When the relative humidity of the environment is less than or equal to 30%, the T is adjusted by 5% to 10% downward.

10. The system for spectral analysis and elimination of water vapor interference with laser sensor according to claim 9, characterized in that, Also include: The historical data comparison module is used for storing a typical water vapor interference mode feature library, wherein the data of the typical water vapor interference mode feature library includes: a humidity value and a threshold T corresponding to a current humidity value, and the preset threshold T is adjusted according to the humidity value detected by the humidity sensor.

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