Leak detector anti-interference method based on estimated background value

Abstract

The invention relates to the technical field of digital signal processing, in particular to a leak detector anti-interference method based on an estimated background value, which comprises the following steps: acquiring a background separation algorithm of a leak detection signal during leak detection, performing derivation and filtering on the leak detection signal twice, and performing integration twice again to extract a background natural attenuation part signal; a linearization algorithm of the exponential signal: taking a natural logarithm ln from the exponential signal to linearize the exponential signal, and estimating a background value derivative algorithm; according to the method, the future derivative value is estimated through less calculation, the future derivative is estimated, the advanced derivative can be obtained, the system can respond more timely, convenience and rapidness are achieved, the background signal value can be taken out in time, the more accurate leakage detection signal value is obtained, the influence of other gas substances in the background on the leakage detection signal is reduced, and the leakage detection accuracy is improved. And along with the increase of the detection period, the precision of the estimated derivative is also increased, so that the precision of the leak detector during leak detection is improved.

Description

Technical Field

[0001] This invention relates to the field of digital signal processing technology, and more specifically to an anti-interference method for leak detectors based on estimated background values. Background Technology

[0002] Dynamically acquiring the system's background value during leak detection can reduce background interference and improve the detection limit. The conventional method is to continuously follow the system's minimum value, record the minimum value as the background value, and subtract it. The disadvantage of this method is that when the background decreases rapidly, the background signal may be greater than the rate of increase in the leak rate, and the overall leak rate will show a downward trend, making it impossible to detect small signals. To solve this problem, if the background value for the next time period can be estimated in advance, this problem can be avoided to a large extent.

[0003] For example, the system's background signal base value is 0.1 Pa·m³ / s and decreases at a rate of 0.01 Pa·m³ / s, while the leakage rate increases at a rate of 0.002 Pa·m³ / s. During the entire observation period, the observed leakage rate decreases at a rate of 0.008 Pa·m³ / s. Thus, the leakage rate signal is overwhelmed by the decreasing background signal. If the system could obtain the current background rate of decrease and estimate the background at the next moment, it could effectively identify the leakage rate signal. Taking the above data as an example, based on 0.1 Pa·m³ / s, we estimate the background signal at the next moment to be 0.09 Pa·m³ / s. At this point, if there is no leakage, the system displays a value of 0.09 Pa·m³ / s. However, if there is a leakage with an increasing rate of 0.002 Pa·m³ / s, the value at the next moment will be 0.092 Pa·m³ / s. Therefore, a leak detector anti-interference method based on the estimated background value is proposed. This demonstrates that estimating the background at the next moment is highly valuable for improving leak detection accuracy.

[0004] From the perspective of the time domain, the derivative is a kind of advance or prediction when taking the derivative over time. For example, the derivative of velocity is acceleration. Based on the sign and magnitude of acceleration, we can determine the increase or decrease of velocity and the magnitude of change. In engineering, we often use the derivative to better control the original function. However, in practical applications, there is often a lag in the sampling and differentiation of the original function, resulting in unsatisfactory control effect.

[0005] Leak detectors typically increase the leak rate linearly, while the background rate tends to decrease exponentially. The superposition of these two signals often makes them difficult to distinguish. Moreover, most algorithms perform well for relatively linear systems but often perform poorly for nonlinear systems. Summary of the Invention

[0006] In order to solve the technical problems existing in the prior art, the present invention provides a leak detector anti-interference method based on estimated background value.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a leak detector anti-interference method based on estimated background values, comprising the following steps:

[0008] S1: The original leak detection signal is differentiated twice and integrated twice to obtain the separated signal;

[0009] S2: Acquire the signals at three separate time points from the signal, and record them in chronological order along the time axis as pairs. , , ;

[0010] S3: Yes , , Taking the natural logarithm gives us , , ;

[0011] S4: Yes , , The derivative is obtained by taking the difference. and Then the derivative obtained and The difference is used to obtain the second derivative. ;

[0012] S5: and Summing yields the estimated value. , and The difference between the estimated and actual values ​​is calculated as e, and the integral of e is obtained. , and The difference is used to obtain the predicted derivative. ;

[0013] S6: Second derivative With the predicted derivative Summing yields the actual predicted derivative. And predict the signal value at the next moment. ;

[0014] S7: Will Then, perform exponentiation with the natural logarithm e as the base to obtain hat_ex2;

[0015] S8: Obtain the signal value at any future moment. , The real leak signal value is obtained after subtracting the background signal value.

[0016] Preferably, the specific calculation formula in step S3 is as follows:

[0017] ;

[0018] ;

[0019] .

[0020] Preferably, the specific calculation formula in step S4 is as follows:

[0021] First derivative: ;

[0022] ;

[0023] Second derivative: .

[0024] Preferably, the specific calculation formula in step S5 is as follows:

[0025] Forecast for: ;

[0026] The error e between the estimated value and the actual value is: ;

[0027] The error e between the estimated value and the actual value for each period before summing x is obtained. ;

[0028] Signal value prediction derivative for: .

[0029] Preferably, the specific calculation formula in step S6 is as follows:

[0030] Actual predicted derivative of the signal for:

[0031] signal value at the next moment for: .

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] This invention utilizes a small amount of raw data and estimates future derivative values ​​with minimal calculations. By predicting future derivatives, a more advanced derivative can be obtained, allowing the system to respond more promptly and efficiently. It also enables the timely extraction of background signal values, resulting in more accurate leak detection signal values. Furthermore, it reduces the influence of other gaseous substances in the background on the leak detection signal. As the detection cycle increases, the accuracy of the estimated derivative also increases, thereby improving the accuracy of the leak detector during leak detection. Attached Figure Description

[0034] Figure 1 This is a block diagram of the pre-estimation method module of the present invention;

[0035] Figure 2 This is a block diagram of the linearization algorithm module of the present invention;

[0036] Figure 3 This is a block diagram of the signal separation algorithm module of the present invention;

[0037] Figure 4 This is a block diagram of the input pre-estimation algorithm system of the present invention;

[0038] Figure 5 This is a comparison diagram of the original leak detection signal and the separated signal in the experimental example of this invention;

[0039] Figure 6 The experimental example of this invention separates the signal at three sampling times. , , Trend chart;

[0040] Figure 7 The experimental example of this invention separates the signal at three sampling times. , , Microscopic comparison diagram;

[0041] Figure 8 For the experimental example of the present invention, the signal separation And the trend chart of the algorithm's predicted value hat_ex2;

[0042] Figure 9 For the experimental example of the present invention, the signal is separated. Microscopic comparison of the algorithm's predicted value hat_ex2;

[0043] Figure 10 The original leak detection signal and comparison diagram are shown in the experimental example of this invention. Detailed Implementation

[0044] The present invention will be further described below with reference to the accompanying drawings and embodiments, which illustrate the above and other technical features and advantages of the present invention. However, the following embodiments are merely preferred embodiments of the present invention and are not exhaustive.

[0045] Example 1:

[0046] like Figure 1-10 As shown, the present invention provides an anti-interference method for leak detectors based on estimated background values, comprising the following steps:

[0047] S1: The original leak detection signal is differentiated twice and integrated twice to obtain the separated signal, such as... Figure 5 As shown, the original signal is a superimposed signal, and the separated signal only has the exponential part left;

[0048] S2: Acquire the signals at three separate time points from the signal, and denote them in chronological order as follows: , , ,like Figure 6 and Figure 7 As shown, the three signals only have a time lag;

[0049] S3: Yes , , Taking the natural logarithm gives us , , .

[0050] S4: Yes , , The derivative is obtained by taking the difference. and Then the derivative obtained and The difference is used to obtain the second derivative. ;

[0051] S5: and Summing yields the estimated value. , and The difference between the estimated and actual values ​​is calculated as e, and the integral of e is obtained. , and The difference is used to obtain the predicted derivative. ;

[0052] S6: Second derivative With the predicted derivative Summing yields the actual predicted derivative. And predict the signal value at the next moment. ;

[0053] S7: Will Then, perform exponentiation with the natural logarithm e as the base to obtain hat_ex2, as follows: Figure 8 and Figure 9 As shown, the estimated value hat_ex2 leads ex2 by one sampling period;

[0054] S8: Obtain the signal value at any future moment. , The real leak signal value is obtained after subtracting the background signal value, such as... Figure 10 As shown, after subtracting the background signal value from the original signal, the coverage effect caused by the natural attenuation in the early stage is weakened, and the characteristics of the leak detection signal itself are revealed.

[0055] In this embodiment, the specific calculation formula in step S3 is as follows:

[0056]

[0057]

[0058]

[0059] In this embodiment, the specific calculation formula in step S4 is as follows:

[0060] First derivative: ;

[0061] ;

[0062] Second derivative:

[0063] In this embodiment, the specific calculation formula in step S5 is as follows:

[0064] Forecast for: ;

[0065] The error e between the estimated value and the actual value is: ;

[0066] The error e between the estimated value and the actual value for each period before summing x is obtained. ;

[0067] Signal value prediction derivative for: .

[0068] In this embodiment, the specific calculation formula in step S6 is as follows:

[0069] Actual predicted derivative of signal value for:

[0070] signal value at the next moment for: .

[0071] Example 2:

[0072] When acquiring the leak detection signal from the leak detector, under natural conditions, the background signal decays rapidly in a natural exponential manner, while the actual leak rate rises gradually with a certain slope. In this embodiment, the initial background signal is approximately 10⁻⁵. After 30 seconds, it will be approximately 10⁻⁸. The initial leakage rate is approximately 2.0 * 10⁻⁷. The leakage rate change rate is approximately 10⁻⁷. .

[0073] The above are merely preferred embodiments of the present invention and are illustrative in nature, not restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

Claims

1. A leak detector anti-interference method based on estimated background values, characterized in that, Includes the following steps: S1: The original leak detection signal is differentiated twice and integrated twice to obtain the separated signal; S2: Acquire the signals at three separate time points from the signal, and record them in chronological order along the time axis as pairs. , , ; S3: Yes , , Taking the natural logarithm gives us , , ; S4: Yes , , The derivative is obtained by taking the difference. and Then the derivative obtained and The difference is used to obtain the second derivative. ; S5: and Summing yields the estimated value. , and The difference between the estimated and actual values ​​is calculated as e, and the integral of e is obtained. , and The difference is used to obtain the predicted derivative. ; S6: Second derivative With the predicted derivative Summing yields the actual predicted derivative. And predict the signal value at the next moment. ; S7: Will Then, perform exponentiation with the natural logarithm e as the base to obtain hat_ex2; S8: Obtain the signal value at any future moment. , The real leak signal value is obtained after subtracting the background signal value.

2. The anti-interference method for a leak detector based on estimated background values ​​as described in claim 1, characterized in that, The specific calculation formula in step S3 is as follows: ； ； 。 3. The anti-interference method for a leak detector based on estimated background values ​​as described in claim 1, characterized in that, The specific calculation formula in step S4 is as follows: First derivative: ; ； Second derivative: .

4. The anti-interference method for a leak detector based on estimated background values ​​as described in claim 1, characterized in that, The specific calculation formula in step S5 is as follows: Forecast for: ; The error e between the estimated value and the actual value is: ; The error e between the estimated value and the actual value for each period before summing x is obtained. ; Signal value prediction derivative for: .

5. The anti-interference method for a leak detector based on estimated background values ​​as described in claim 1, characterized in that, The specific calculation formula in step S6 is as follows: The actual predicted derivative of the signal is: ; signal value at the next moment for: .

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