A method, system and medium for improving the communication quality of acoustic emission signals
By combining typical acoustic emission signals with leak defect signals and performing frequency domain processing, the problem of poor communication quality of acoustic emission signals in nuclear reactor equipment is solved, and the accuracy of leakage and defect diagnosis is improved.
Patent Information
- Application Number
- CN202211122421.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-09-15
- Publication Date
- 2024-12-31
- Estimated Expiration
- 2042-09-15
AI Technical Summary
The quality of the acoustic emission signal communication of key equipment of nuclear reactors is poor, resulting in problems such as misjudgment and misjudgment in leaks and defect monitoring.
By combining the cyclic prefix of the preset typical acoustic emission signal with the acoustic emission leakage defect signal, transforming it into a frequency domain signal, and migrating to a higher frequency band, the coefficients allocated in real time are weighted and combined, and then demodulated and inverse transformation is performed. The estimated noise parameters are corrected to improve signal quality.
It effectively improves the communication quality of acoustic transmitting signals, reduces noise interference, improves the accuracy of diagnosis of leakage and defects of nuclear reactor equipment, and reduces the risk of misdiagnosis and misdiagnosis.
Smart Images
Figure CN115459790B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a method, a system and a medium for improving the communication quality of acoustic emission signals. Background Art
[0002] Key equipment in nuclear reactors, such as main pipelines and surge tubes, steam generators, valves, etc., work in harsh environments of high temperature, high pressure and high radiation for a long time. Real-time status monitoring of these key equipment is crucial to maintaining the safety of nuclear reactors. Among them, leakage and defect monitoring of the sealing performance of these key equipment is one of the most important monitoring directions.
[0003] At present, acoustic emission sensors are arranged on the surface of these key equipment for monitoring. Acoustic emission is the phenomenon that when a material is deformed or fractured by external or internal forces, it releases energy in the form of stress waves. When a leak or defect occurs, a continuous and non-overlapping acoustic emission pulse signal will be generated on the surface of the equipment to characterize it. The signal is a small signal of medium and high frequency, and its magnitude is comparable to the background noise. However, through the experience of on-site monitoring of nuclear power plants, it is found that the acoustic emission signal is mixed with various noises caused by vibration, hydraulics, friction, interference, etc. during transmission, which has a great impact on the quality of signal communication transmission. There is a situation where the background noise or other various noises are increased in time and misdiagnosed as leaks or defects. There is also a risk of excessive noise covering the signal or cracks appearing in the early stage of leakage but the signal is small, resulting in missed diagnosis.
[0004] In summary, the inventors have found that the above technology has at least the following technical problems:
[0005] The communication quality and transmission condition of acoustic emission signals for monitoring leakage and defects of key nuclear reactor equipment is poor, and the acoustic emission signals for monitoring leakage and defects of key nuclear reactor equipment cannot be accurately diagnosed, resulting in missed judgments and misjudgments. Summary of the invention
[0006] In order to solve the technical problem in the prior art that the acoustic emission signal cannot be accurately diagnosed due to poor communication quality transmission of the acoustic emission signal, the embodiments of the present invention provide a method, system and medium for improving the communication quality of the acoustic emission signal.
[0007] The embodiment of the present invention is achieved through the following technical solutions:
[0008] In a first aspect, an embodiment of the present invention provides a method for improving the communication quality of an acoustic emission signal, comprising:
[0009] Combining a preset cyclic prefix of a typical acoustic emission signal with an acoustic emission leakage defect signal to obtain a combined signal;
[0010] transforming the combined signal into a frequency domain signal;
[0011] Migrating the frequency domain signal to a higher frequency band, and performing weighted combination by coefficients allocated according to the real-time state of transmission to obtain a combined frequency domain signal and a receiving end signal;
[0012] According to the inverse transformation of weighted distribution, the combined frequency domain signal after the demodulation of the receiving end signal is fused into the original frequency band of the signal, and the time domain signal is obtained after processing;
[0013] The cyclic prefix part of the time domain signal is compared and calculated with the known cyclic prefix of a typical acoustic emission signal to obtain a noise estimation parameter;
[0014] The remaining part of the time domain signal after removing the cyclic prefix is subjected to noise correction and compensation according to the noise estimation parameter to obtain an acoustic emission signal with improved quality.
[0015] Furthermore, the noise estimation parameters include the noise sequence, the overall noise mean and the overall noise variance.
[0016] Furthermore, it also includes:
[0017] The overall noise variance is compared with the threshold of the overall noise variance, and the overall noise mean is compared with the threshold of the overall noise mean. If the number of times the overall noise variance exceeds the threshold of the overall noise variance or the number of times the overall noise mean exceeds the threshold of the overall noise mean reaches or exceeds the specified number of times, then
[0018] Re-adjusting the coefficients allocated for the transmission real-time state and returning to obtain the combined frequency domain signal and the receiving end signal, so that the number of times the overall noise variance exceeds the threshold of the overall noise variance or the number of times the overall noise mean exceeds the threshold of the overall noise mean is less than a specified number;
[0019] The method also includes: performing noise trend analysis on the noise sequence and effective determination analysis on the acoustic emission signal, and generating a threshold value of the overall noise variance and a threshold value of the overall noise mean.
[0020] Further, transforming the combined signal into a frequency domain signal comprises:
[0021] According to formulas (1) and (2), the combined signal is transformed into a frequency domain signal A(f);
[0022]
[0023] ω=2πf (2)
[0024] Where ω is the signal angular frequency, f is the signal frequency, and a(t) is the combined time domain signal.
[0025] Furthermore, the frequency domain signal is migrated to a spectrum of a higher frequency band, and a combined frequency domain signal is obtained by weighted combination of coefficients allocated by the transmission real-time state; including:
[0026] The frequency domain signal A(f) is subjected to spectrum migration in the medium and high frequency bands to obtain the frequency domain signal A(f-nf0), where f0 satisfies f0>mf x , generally the coefficient m>1.3, n is a positive integer greater than 0;
[0027] Assume that the real-time state weight coefficients of the channel are k0k1k2...k n , then the combined frequency domain signal X(f) is expressed as
[0028] X(f)=k0A(f)+k1A(f-f0)+k2A(f-2f0)+...+k n A(f-nf0) (3)
[0029] Assume that the transmission noise signal is expressed in frequency domain as N(f), and the receiving end signal Y(f) is expressed as
[0030] Y(f)=X(f)+N(f) (4).
[0031] Further, according to the inverse transformation of weighted allocation, the combined frequency domain signal after the demodulation of the receiving end signal is fused into the original frequency band of the signal, and the time domain signal is obtained after processing; including:
[0032] According to formulas (5) and (6), the combined frequency domain signal after demodulation of the receiving end signal is converted into a time domain signal;
[0033]
[0034] ω=2πf (6)
[0035] Among them, ω is the signal angular frequency and f is the signal frequency.
[0036] Further, the cyclic prefix part of the time domain signal is compared and calculated with the known typical acoustic emission signal cyclic prefix to obtain the noise estimation parameter; including:
[0037] The cyclic prefix part r'(t) of the time domain signal is compared with the known typical acoustic emission signal cyclic prefix r(t) to obtain the noise sequence N(t); the noise sequence N(t) is expressed as
[0038] N(t)=r'(t)-r(t) (7)
[0039] Perform statistical operations on the noise sequence N(t) and divide it into time segments to obtain the overall noise mean of each segment, μ1...μ n , and their variances are σ12 ... n 2 ; Take the statistical average to get the overall noise mean μ and the overall noise variance σ 2 .
[0040] Further, according to the noise estimation parameter, the remaining part of the time domain signal after removing the cyclic prefix is subjected to noise correction and compensation to obtain an acoustic emission signal with improved quality; including:
[0041] According to the noise estimation parameter, the remaining part s'(t) of the time domain signal z(t) after removing the cyclic prefix is subjected to noise correction and compensation to obtain an acoustic emission signal with improved quality;
[0042] The acoustic emission signal S0(t) after quality improvement is expressed as:
[0043] s0(t)=s'(t)-μ (8).
[0044] In a second aspect, an embodiment of the present invention provides a system for improving the communication quality of an acoustic emission signal, comprising:
[0045] A combined signal unit, used for combining a preset cyclic prefix of a typical acoustic emission signal with an acoustic emission leakage defect signal to obtain a combined signal;
[0046] A frequency domain signal conversion unit, used for converting the combined signal into a frequency domain signal;
[0047] A frequency domain signal processing unit, used to migrate the frequency domain signal to a higher frequency band, and obtain a combined frequency domain signal and a receiving end signal by weighted combination of coefficients allocated by the transmission real-time state;
[0048] A time domain signal unit is used to fuse the combined frequency domain signal after receiving end signal demodulation into the original frequency band of the signal according to the inverse transformation of weighted distribution, and obtain the time domain signal after processing;
[0049] A noise estimation parameter calculation unit, used for comparing and calculating the cyclic prefix part of the time domain signal with the known typical acoustic emission signal cyclic prefix to obtain the noise estimation parameter; and
[0050] The acoustic emission signal correction unit is used to perform noise correction and compensation on the remaining part of the time domain signal after removing the cyclic prefix according to the noise estimation parameter to obtain an acoustic emission signal with improved quality.
[0051] In a third aspect, an embodiment of the present invention provides a storage medium, wherein the computer-readable storage medium stores instructions, and when the instructions are executed on a computer, the method for improving the communication quality of acoustic emission signals is executed.
[0052] Compared with the prior art, the embodiments of the present invention have the following advantages and beneficial effects:
[0053] A method, system and medium for improving the communication quality of an acoustic emission signal according to an embodiment of the present invention, comprising: combining a cyclic prefix of a preset typical acoustic emission signal with an acoustic emission leakage defect signal to obtain a combined signal; transforming the combined signal into a frequency domain signal; migrating the frequency domain signal to a higher frequency band, and performing weighted combination by transmitting coefficients allocated by a real-time state to obtain a combined frequency domain signal and a receiving end signal; fusing the combined frequency domain signal demodulated by the receiving end signal into the original frequency band of the signal according to an inverse transformation of the weighted allocation, and obtaining a time domain signal after processing; comparing and calculating the cyclic prefix part of the time domain signal with the known cyclic prefix of a typical acoustic emission signal to obtain a noise estimation parameter; performing noise correction and compensation on the remaining part of the time domain signal after removing the cyclic prefix according to the noise estimation parameter to obtain an acoustic emission signal with improved quality, thereby solving the technical problem in the prior art that the acoustic emission signal cannot be accurately diagnosed due to poor communication quality transmission of the acoustic emission signal. BRIEF DESCRIPTION OF THE DRAWINGS
[0054] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.
[0055] Figure 1 A flow chart of a method for improving the communication quality of acoustic emission signals.
[0056] Figure 2 Schematic diagram of the system structure for improving the communication quality of acoustic emission signals.
[0057] Figure 3 Schematic diagram of the process of the present invention for example.
[0058] Figure 4 Schematic diagram of the cyclic prefix of a typical acoustic emission signal.
[0059] Figure 5 Flowchart of the feedback strategy approach.
[0060] Figure 6 This is the flow chart of the nuclear reactor main pipe and surge tube LBB leakage monitoring system. DETAILED DESCRIPTION
[0061] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.
[0062] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is apparent to one of ordinary skill in the art that these specific details are not necessarily employed to practice the present invention. In other embodiments, in order to avoid obscuring the present invention, well-known structures, circuits, materials, or methods are not specifically described.
[0063] Throughout the specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment," "an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily all refer to the same embodiment or example. In addition, particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. In addition, it will be appreciated by those of ordinary skill in the art that the figures provided herein are for illustrative purposes and that the figures are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0064] In the description of the present invention, the directions or positional relationships indicated by terms such as “front”, “rear”, “left”, “right”, “up”, “down”, “vertical”, “horizontal”, “high”, “low”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the scope of protection of the present invention.
[0065] Example
[0066] In order to solve the technical problem that the acoustic emission signal cannot be accurately diagnosed due to the poor communication quality transmission condition of the acoustic emission signal in the prior art, in the first aspect, an embodiment of the present invention provides a method for improving the communication quality of the acoustic emission signal, referring to Figure 1 As shown, including:
[0067] S1. Combining the cyclic prefix of the preset typical acoustic emission signal with the acoustic emission leakage defect signal to obtain a combined signal;
[0068] Cyclic prefix reference of a typical acoustic emission signal Figure 4 shown.
[0069] S2. transforming the combined signal into a frequency domain signal;
[0070] S3. Migrating the frequency domain signal to a higher frequency band, performing weighted combination by transmitting coefficients allocated in real-time state to obtain a combined frequency domain signal and a receiving end signal;
[0071] S4. According to the inverse transform of the weighted distribution, the combined frequency domain signal after the demodulation of the receiving end signal is fused into the original frequency band of the signal, and the time domain signal is obtained after processing;
[0072] S5. Compare and calculate the cyclic prefix part of the time domain signal with the known typical acoustic emission signal cyclic prefix to obtain the noise estimation parameter;
[0073] S6. Perform noise correction and compensation on the remaining part of the time domain signal after removing the cyclic prefix according to the noise estimation parameter to obtain an acoustic emission signal with improved quality.
[0074] The execution subject of the method of the embodiment of the present invention may be a server, a client, etc., or a system. Specifically, the method of the embodiment of the present invention may be performed by Figure 3 The system shown is implemented.
[0075] Thus, the embodiment of the present invention obtains a combined signal by combining a cyclic prefix of a preset typical acoustic emission signal with an acoustic emission leakage defect signal; transforming the combined signal into a frequency domain signal; migrating the frequency domain signal to a higher frequency band, and performing weighted combination by transmitting coefficients allocated by a real-time state to obtain a combined frequency domain signal and a receiving end signal; fusing the combined frequency domain signal demodulated by the receiving end signal into the original frequency band of the signal according to an inverse transform of the weighted allocation, and obtaining a time domain signal after processing; comparing and calculating the cyclic prefix part of the time domain signal with the known cyclic prefix of the typical acoustic emission signal to obtain a noise estimation parameter; performing noise correction and compensation on the remaining part of the time domain signal after removing the cyclic prefix according to the noise estimation parameter to obtain an acoustic emission signal with improved quality, thereby solving the technical problem in the prior art that the acoustic emission signal cannot be accurately diagnosed due to poor communication quality transmission of the acoustic emission signal.
[0076] Furthermore, the noise estimation parameters include the noise sequence, the overall noise mean and the overall noise variance.
[0077] Furthermore, it also includes:
[0078] The overall noise variance is compared with the threshold of the overall noise variance, and the overall noise mean is compared with the threshold of the overall noise mean. If the number of times the overall noise variance exceeds the threshold of the overall noise variance or the number of times the overall noise mean exceeds the threshold of the overall noise mean reaches or exceeds the specified number of times, then
[0079] Re-adjusting the coefficients allocated for the transmission real-time state and returning to obtain the combined frequency domain signal and the receiving end signal, so that the number of times the overall noise variance exceeds the threshold of the overall noise variance or the number of times the overall noise mean exceeds the threshold of the overall noise mean is less than a specified number;
[0080] The method also includes: performing noise trend analysis on the noise sequence and effective determination analysis on the acoustic emission signal, and generating a threshold value of the overall noise variance and a threshold value of the overall noise mean.
[0081] The above steps are used to evaluate the transmission environment and optimize the strategy. Among them, the noise sequence refers to the sequence after the known acoustic emission signal cyclic prefix is added with the transmission noise. The validity judgment of the acoustic emission signal mainly refers to the difference with the effective value, variance, peak-to-peak value, number of oscillations, etc. of the known acoustic emission signal. If the noise sequence can still pass this judgment, it means that the noise impact is not large enough to maintain the status quo. On the contrary, if it cannot be identified, it is necessary to optimize the transmission strategy and adjust the ratio coefficient of the frequency band transmission. The threshold can be set to a certain multiple of the noise mean and variance through statistical averaging over a period of time.
[0082] Further, transforming the combined signal into a frequency domain signal comprises:
[0083] According to formulas (1) and (2), the combined signal is transformed into a frequency domain signal A(f);
[0084]
[0085] ω=2πf (2)
[0086] Where ω is the signal angular frequency, f is the signal frequency, and a(t) is the combined time domain signal.
[0087] Furthermore, the frequency domain signal is migrated to a spectrum of a higher frequency band, and a combined frequency domain signal is obtained by weighted combination of coefficients allocated by the transmission real-time state; including:
[0088] The frequency domain signal A(f) is subjected to spectrum migration in the medium and high frequency bands to obtain the frequency domain signal A(f-nf0), where f0 satisfies f0>mf x , generally the coefficient m>1.3, n is a positive integer greater than 0;
[0089] Assume that the real-time state weight coefficients of the channel are k0k1k2...k n , then the combined frequency domain signal X(f) is expressed as
[0090] X(f)=k0A(f)+k1A(f-f0)+k2A(f-2f0)+...+k n A(f-nf0) (3)
[0091] Assume that the transmission noise signal is expressed in frequency domain as N(f), and the receiving end signal Y(f) is expressed as
[0092] Y(f)=X(f)+N(f) (4).
[0093] Further, according to the inverse transformation of weighted allocation, the combined frequency domain signal after the demodulation of the receiving end signal is fused into the original frequency band of the signal, and the time domain signal is obtained after processing; including:
[0094] According to formulas (5) and (6), the combined frequency domain signal after demodulation of the receiving end signal is converted into a time domain signal;
[0095]
[0096] ω=2πf (6)
[0097] Among them, ω is the signal angular frequency and f is the signal frequency.
[0098] Further, the cyclic prefix part of the time domain signal is compared and calculated with the known typical acoustic emission signal cyclic prefix to obtain the noise estimation parameter; including:
[0099] The cyclic prefix part r'(t) of the time domain signal is compared with the known typical acoustic emission signal cyclic prefix r(t) to obtain the noise sequence N(t); the noise sequence N(t) is expressed as
[0100] N(t)=r'(t)-r(t) (7)
[0101] Perform statistical operations on the noise sequence N(t) and divide it into time segments to obtain the overall noise mean of each segment, μ1...μ n , and their variances are σ1 2 ... n 2 ; Take the statistical average to get the overall noise mean μ and the overall noise variance σ 2 .
[0102] Further, according to the noise estimation parameter, the remaining part of the time domain signal after removing the cyclic prefix is subjected to noise correction and compensation to obtain an acoustic emission signal with improved quality; including:
[0103] According to the noise estimation parameter, the remaining part s'(t) of the time domain signal z(t) after removing the cyclic prefix is subjected to noise correction and compensation to obtain an acoustic emission signal with improved quality;
[0104] The acoustic emission signal S0(t) after quality improvement is expressed as:
[0105] s0(t)=s'(t)-μ (8).
[0106] Exemplary, reference Figure 6 As shown, the method of the embodiment of the present invention is applied to a nuclear reactor. The online monitoring system for the primary loop main pipeline and the surge tube LBB leakage of the nuclear reactor is implemented to adaptively improve the signal communication quality. 31 acoustic emission sensors are installed at various positions of the primary loop main pipeline and the surge tube to monitor the acoustic emission signals. Figure 3 The signal processing shown improves the signal communication quality and accuracy, and is ultimately identified by the software system through algorithms and output to the alarm system.
[0107] The specific method includes the following steps:
[0108] Step 1: Obtain acoustic emission leakage defect signals by installing acoustic emission sensors in main pipelines, surge pipes, important valves and other locations.
[0109] Step 2: The acoustic emission signal s(t) is collected through the front-end digital processing module, and the preset typical acoustic emission signal r(t) is combined with the collected signal in the form of a cyclic prefix to obtain the signal a(t), and the frequency domain signal A(f) of the signal is obtained through Fourier transform or FFT.
[0110] Step 3: Perform spectrum migration of the frequency domain signal A(f) to the medium and high frequency bands, and perform weighted combination by the coefficients allocated by the real-time state transmission to obtain the combined frequency domain signal X(f). This signal is transmitted to the receiving end through the multi-band signal cable to obtain the signal Y(f).
[0111] Step 4: The receiving end signal Y(f) demodulates the combined spectrum signal, and fuses the signal into the original frequency band according to the inverse transform of weighted allocation to obtain the signal Z(f). After the signal is bandpass filtered, it is processed by inverse Fourier transform or IFFT to obtain the time domain signal z(t).
[0112] Step 5: Take out the cyclic prefix part r'(t) of the signal z(t), compare it with the known typical acoustic emission signal cyclic prefix r(t), and get the real-time noise sequence n(t), the overall noise mean μ, and the overall noise variance σ 2 .
[0113] Step 6: Combined with the result of noise calculation, the remaining part s'(t) after removing the cyclic prefix of the signal z(t) is subjected to noise correction and compensation to obtain the final acoustic emission signal s0(t) for system fault diagnosis.
[0114] Step 7: Analyze and evaluate the transmission environment of the noise signal, optimize the strategy, feed back the adjusted correction coefficient to the front-end digital processing module, and repeat steps 3-7 until the system stops running.
[0115] In step 2, since the leakage and defect acoustic emission signal s(t) is a steady-state signal, once leakage and cracks occur, the signal will continue to emit stress wave signals. Therefore, only 500ms of the 1s data can be collected to obtain the required information.
[0116] In step 2, the preset acoustic emission signal r(t) is a typical standard acoustic emission signal of a known sequence, such as Figure 4 As shown in the figure, it is a continuous stress wave pulse signal, which gradually decays. After reaching the receiving end through the transmission channel, the noise can be calculated by transformation.
[0117] In this embodiment, 500ms is divided into three sections, and three typical effective acoustic emission signals are set respectively. The frequency bands are respectively located at 50kHz~200kHz, 250kHz~400kHz, and 450kHz~600kHz. The noise sequences of these three frequency bands are estimated at the receiving end, and finally the accuracy of calculating noise is improved.
[0118] In step 2, the Fourier transform formula for converting the time domain signal into the frequency domain signal is:
[0119]
[0120] ω=2πf
[0121] In step 3, the frequency domain signal A(f) is subjected to spectrum migration in the medium and high frequency bands. In this embodiment, the spectrum is shifted to the right by f0=200kHz and 2f0=400kHz, and the expressions are A(f-f0) and A(f-2f0). The effective bandwidth of the acoustic emission stress wave signal in this embodiment is 150kHz. In order to ensure that the migrated spectrum does not overlap with the original signal spectrum, f0>mf x , where the coefficient m>1.3.
[0122] In step 3, we can also directly Directly perform Fourier transform to obtain the spectrum A(f-f0), and so on.
[0123] In step 3, assume that the real-time state weighting coefficients of the channel are k0k1k2, and the initial state k0=k1=k2=1, then the combined frequency domain signal X(f) is expressed as
[0124] X(f)=k0A(f)+k1A(f-f0)+k2A(f-2f0)
[0125] Assume that the transmission noise signal is expressed in the frequency domain as N(f), and the signal Y(f) at the receiving end can be expressed as
[0126] Y(f)=X(f)+N(f)
[0127] In step 4, the inverse Fourier transform formula for converting the frequency domain signal into the time domain signal is:
[0128]
[0129] ω=2πf
[0130] In step 5, the noise sequence N(t) is expressed as
[0131] N(t)=r'(t)-r(t)
[0132] Performing statistical operations on the obtained noise sequence and based on the results of the aforementioned time segmentation, we can obtain the mean of the noise in each segment as μ1μ2μ3 and the variance as σ1 2 σ2 2 σ3 2 . By taking a statistical average, we can get the overall noise mean μ and the overall noise variance σ 2 .
[0133] In step 6, the acoustic emission signal finally used for system fault diagnosis can be expressed as
[0134] s0(t)=s'(t)-μ
[0135] In step 7, the flow chart of transmission environment assessment and strategy optimization is as follows: Figure 5 As shown, the noise sequence obtained by the cyclic prefix is stored in the noise database, and the noise trend analysis is performed. At the same time, the noise sequence also performs effective judgment on the acoustic emission signal to analyze whether the noise can be identified by the algorithm after affecting the acoustic emission. The results of the two-side processing are stored in the computer to guide the setting of the noise threshold.
[0136] In this embodiment, the overall mean and variance of the noise are initially set to the mean μ0 and variance σ0 of the overall noise sequence calculated for the first five acquisitions. 2 , and gradually set it to a more appropriate threshold in the early stage of operation.
[0137] For example, the overall mean and variance of the noise are compared with the set threshold value, and the specified number of times is set to 5. If the specified number of times is not reached, the original strategy remains unchanged and the threshold comparison continues. If it exceeds the threshold value 5 times, the coefficients will be redistributed.
[0138] The coefficients are reallocated based on the estimated mean and variance of each frequency band in the reference noise sequence, and the weight coefficients with the best mean and variance are appropriately increased by 10%, while the weight coefficients with poor mean and variance, i.e., poor transmission frequency band environment, are reduced by 10%, and the coefficients are recorded and fed back to the front-end digital processing equipment.
[0139] Therefore, the embodiment of the present invention improves the signal communication quality by adding a cyclic prefix of a typical acoustic emission signal in the time domain to the acoustic emission signal for monitoring leakage defects of key nuclear reactor equipment to reduce the influence of noise, and by multi-band transmission of weighted coefficient spectrum migration to effectively utilize the characteristics of high frequency and low noise. The acoustic emission signal obtained by the method of the present invention has a higher signal-to-noise ratio and precision, and therefore, the accuracy of monitoring and fault diagnosis is higher.
[0140] The embodiment of the present invention can evaluate the signal transmission environment by estimating the calculated noise, and obtain the corresponding optimization strategy through analysis, which is fed back to the front-end signal processing module, and the module can optimize the weighted coefficient of the real-time state of the channel. The feedback strategy of the present invention can make the above method for improving the signal communication quality applicable to complex and changing transmission environments, and the practicality and reliability are greatly improved.
[0141] In a second aspect, an embodiment of the present invention provides a system for improving the communication quality of acoustic emission signals, referring to Figure 2 As shown, including:
[0142] A combined signal unit, used for combining a preset cyclic prefix of a typical acoustic emission signal with an acoustic emission leakage defect signal to obtain a combined signal;
[0143] A frequency domain signal conversion unit, used for converting the combined signal into a frequency domain signal;
[0144] A frequency domain signal processing unit, used to migrate the frequency domain signal to a higher frequency band, and obtain a combined frequency domain signal and a receiving end signal by weighted combination of coefficients allocated by the transmission real-time state;
[0145] A time domain signal unit is used to fuse the combined frequency domain signal after receiving end signal demodulation into the original frequency band of the signal according to the inverse transformation of weighted distribution, and obtain the time domain signal after processing;
[0146] A noise estimation parameter calculation unit, used for comparing and calculating the cyclic prefix part of the time domain signal with the known typical acoustic emission signal cyclic prefix to obtain the noise estimation parameter; and
[0147] The acoustic emission signal correction unit is used to perform noise correction and compensation on the remaining part of the time domain signal after removing the cyclic prefix according to the noise estimation parameter to obtain an acoustic emission signal with improved quality.
[0148] In a third aspect, an embodiment of the present invention provides a storage medium, wherein the computer-readable storage medium stores instructions, and when the instructions are executed on a computer, the method for improving the communication quality of acoustic emission signals is executed.
[0149] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.
Claims
1. A method for improving the communication quality of acoustic emission signals, characterized in that: include: The cyclic prefix of the preset typical acoustic emission signal is combined with the acoustic emission leakage defect signal to obtain a combined signal; transforming the combined signal into a frequency domain signal; Migrating the frequency domain signal to a higher frequency band, and performing weighted combination by coefficients allocated according to the real-time state of transmission to obtain a combined frequency domain signal and a receiving end signal; According to the inverse transformation of weighted distribution, the combined frequency domain signal after the demodulation of the receiving end signal is fused into the original frequency band of the signal, and the time domain signal is obtained after processing; The cyclic prefix part of the time domain signal is compared and calculated with the known cyclic prefix of a typical acoustic emission signal to obtain a noise estimation parameter; The remaining part of the time domain signal after removing the cyclic prefix is subjected to noise correction and compensation according to the noise estimation parameter to obtain an acoustic emission signal with improved quality; The step of transforming the combined signal into a frequency domain signal comprises: According to formulas (1) and (2), the combined signal is transformed into a frequency domain signal A(f); ω=2πf (2) Where ω is the signal angular frequency, f is the signal frequency, and a(t) is the combined time domain signal; The frequency domain signal is migrated to a higher frequency band of the spectrum, and a combined frequency domain signal is obtained by weighted combination of coefficients allocated by the transmission real-time state; including: The frequency domain signal A(f) is subjected to spectrum migration in the medium and high frequency bands to obtain the frequency domain signal A(f-nf0), where f0 satisfies f0>mf x , coefficient m>1.3, n is a positive integer greater than 0; Assume that the real-time state weight coefficients of the channel are k0k1k2...k n , then the combined frequency domain signal X(f) is expressed as X(f)=k0A(f)+k1A(f-f0)+k2A(f-2f0)+...+k n A(f-nf0) (3) Assume that the transmission noise signal is expressed in the frequency domain as N(f), and the receiving end signal Y(f) is expressed as Y(f)=X(f)+N(f) (4); Among them, according to the inverse transformation of weighted allocation, the combined frequency domain signal after the demodulation of the receiving end signal is fused into the original frequency band of the signal, and the time domain signal is obtained after processing; including: According to formulas (5) and (6), the combined frequency domain signal after demodulation of the receiving end signal is converted into a time domain signal; ω=2πf (6) Where, ω is the signal angular frequency, and f is the signal frequency; The cyclic prefix part of the time domain signal is compared and calculated with the known typical acoustic emission signal cyclic prefix to obtain the noise estimation parameter; including: The cyclic prefix part r'(t) of the time domain signal is compared with the known typical acoustic emission signal cyclic prefix r(t) to obtain the noise sequence N(t); the noise sequence N(t) is expressed as N(t)=r'(t)-r(t) (7) Perform statistical operations on the noise sequence N(t) and divide it into time segments to obtain the overall noise mean of each segment, μ1...μ n , and their variances are σ1 2 ... n 2 ; Take the statistical average to get the overall noise mean μ and the overall noise variance σ 2 ; The method comprises: performing noise correction and compensation on the remaining part of the time domain signal after removing the cyclic prefix according to the noise estimation parameter to obtain an acoustic emission signal with improved quality; comprising: According to the noise estimation parameter, the remaining part s'(t) of the time domain signal z(t) after removing the cyclic prefix is subjected to noise correction and compensation to obtain an acoustic emission signal with improved quality; The acoustic emission signal S0(t) after quality improvement is expressed as: s0(t)=s'(t)-μ (8).
2. The method for improving the communication quality of acoustic emission signals according to claim 1, characterized in that: The noise estimation parameters include the noise sequence, the overall noise mean and the overall noise variance.
3. The method for improving the communication quality of acoustic emission signals according to claim 2, characterized in that: Also includes: The overall noise variance is compared with the threshold of the overall noise variance, and the overall noise mean is compared with the threshold of the overall noise mean. If the number of times the overall noise variance exceeds the threshold of the overall noise variance or the number of times the overall noise mean exceeds the threshold of the overall noise mean reaches or exceeds the specified number of times, then Re-adjusting the coefficients allocated for the transmission real-time state and returning to obtain the combined frequency domain signal and the receiving end signal, so that the number of times the overall noise variance exceeds the threshold of the overall noise variance or the number of times the overall noise mean exceeds the threshold of the overall noise mean is less than a specified number; The method also includes: performing noise trend analysis on the noise sequence and effective determination analysis on the acoustic emission signal, and generating a threshold value of the overall noise variance and a threshold value of the overall noise mean.
4. A system for improving the communication quality of acoustic emission signals, characterized in that: include: A combined signal unit, used for combining a preset cyclic prefix of a typical acoustic emission signal with an acoustic emission leakage defect signal to obtain a combined signal; A frequency domain signal conversion unit, used for converting the combined signal into a frequency domain signal; A frequency domain signal processing unit, used to migrate the frequency domain signal to a higher frequency band, and obtain a combined frequency domain signal and a receiving end signal by weighted combination of coefficients allocated by the transmission real-time state; A time domain signal unit is used to fuse the combined frequency domain signal after receiving end signal demodulation into the original frequency band of the signal according to the inverse transformation of weighted distribution, and obtain the time domain signal after processing; A noise estimation parameter calculation unit is used to compare and calculate the cyclic prefix part of the time domain signal with the known typical acoustic emission signal cyclic prefix to obtain the noise estimation parameter; as well as An acoustic emission signal correction unit, used to perform noise correction and compensation on the remaining part of the time domain signal after removing the cyclic prefix according to the noise estimation parameter, so as to obtain an acoustic emission signal with improved quality; The step of transforming the combined signal into a frequency domain signal comprises: According to formulas (1) and (2), the combined signal is transformed into a frequency domain signal A(f); ω=2πf (2) Where ω is the signal angular frequency, f is the signal frequency, and a(t) is the combined time domain signal; The frequency domain signal is migrated to a higher frequency band of the spectrum, and a combined frequency domain signal is obtained by weighted combination of coefficients allocated by the transmission real-time state; including: The frequency domain signal A(f) is subjected to spectrum migration in the medium and high frequency bands to obtain the frequency domain signal A(f-nf0), where f0 satisfies f0>mf x , coefficient m>1.3, n is a positive integer greater than 0; Assume that the real-time state weight coefficients of the channel are k0k1k2...k n , then the combined frequency domain signal X(f) is expressed as X(f)=k0A(f)+k1A(f-f0)+k2A(f-2f0)+...+k n A(f-nf0) (3) Assume that the transmission noise signal is expressed in frequency domain as N(f), and the receiving end signal Y(f) is expressed as Y(f)=X(f)+N(f) (4); Among them, according to the inverse transformation of weighted allocation, the combined frequency domain signal after the demodulation of the receiving end signal is fused into the original frequency band of the signal, and the time domain signal is obtained after processing; including: According to formulas (5) and (6), the combined frequency domain signal after demodulation of the receiving end signal is converted into a time domain signal; ω=2πf (6) Where, ω is the signal angular frequency, and f is the signal frequency; The cyclic prefix part of the time domain signal is compared and calculated with the known cyclic prefix of the typical acoustic emission signal to obtain the noise estimation parameter; including: The cyclic prefix part r'(t) of the time domain signal is compared with the known typical acoustic emission signal cyclic prefix r(t) to obtain the noise sequence N(t); the noise sequence N(t) is expressed as N(t)=r'(t)-r(t) (7) Perform statistical operations on the noise sequence N(t) and divide it into time segments to obtain the overall noise mean of each segment, μ1...μ n , and their variances are σ1 2 ... n 2 ; Take the statistical average to get the overall noise mean μ and the overall noise variance σ 2 ; The method comprises: performing noise correction and compensation on the remaining part of the time domain signal after removing the cyclic prefix according to the noise estimation parameter to obtain an acoustic emission signal with improved quality; comprising: According to the noise estimation parameter, the remaining part s'(t) of the time domain signal z(t) after removing the cyclic prefix is subjected to noise correction and compensation to obtain an acoustic emission signal with improved quality; The acoustic emission signal S0(t) after quality improvement is expressed as: s0(t)=s'(t)-μ (8).
5. A storage medium, characterized in that: The storage medium stores instructions, and when the instructions are executed on a computer, the method for improving the communication quality of acoustic emission signals according to any one of claims 1 to 3 is executed.