CN101551064A - Water supply pipe leakage detection locating signal processing method - Google Patents

Abstract

The invention discloses a signal processing method for detecting and locating leakage of a water supply pipeline. This method first judges whether the burst interference exists on the collected information, and if the burst interference exists, then remove the burst interference processing, if the burst interference does not exist or after the burst interference is removed, the signal is subjected to noise suppression processing; the whole denoising After the preprocessing process is completed, it is judged whether the leak exists according to the processed signal. The function of identifying the difference between the real leak and the fixed interference sound source is also added during the judgment. If the leak does not exist, the detection result is directly given. If it exists, it is also necessary to locate the leak point, and give the final detection result and the location of the leak point. The beneficial technical effects of the present invention are: when performing leakage detection on water supply pipelines, through denoising processing such as removal of burst interference and noise suppression in the acquisition signal, the quality of the signal is improved, thereby improving pipeline leakage detection in complex noise environments The accuracy and accuracy of leak point location; only by identifying whether the collected signal contains a real leak sound signal, and then locating the leak point has practical value.

Description

The signal processing method of water supply line Leak testtion location

Technical field

The present invention relates to the fault diagnosis technology field of fluid-transporting tubing, relate in particular to the signal processing method of a kind of water supply line Leak testtion location.

Background technique

When leaking appears in water supply line, high pressure water in the water pipe is when pipe leakage outwards sprays, because the outer soil of Cavitation Noise, turbulence noise, ejaculation water and pipe friction and water slug pipe etc. is buried the interaction between medium underground, will cause sound vibration at the pipe leakage place, as shown in Figure 1.By picking up this acoustic signal, and carry out corresponding signal and handle, extract detection information, just can judge that whether leakage takes place and locate leakage point at pipeline or ground.Picking up and leaking that the chatter signal cause detects is the main difference of water supply line and other fluid line detecting methods.In addition, also there are bigger difference in water supply line and long oil pipeline road and gas pipeline on space distribution, formation and operating conditions: the one, and water supply line space distribution complexity, major-minor and more secondary pipeline are formed the topological pipe network system of a complexity, and branch is many, node is many; The 2nd, major-minor and more secondary pipeline water supply load difference, therefore, pipeline condition in a pipe network system (pressure of supply water, pipe material, caliber, pipe thickness, pipeline enclosure interface shape and piping laying condition etc. in mouthful pipe) is complicated and changeable, and major-minor and more secondary pipeline condition difference are bigger; The 3rd, the leakage form is varied, comprises that aperture, crackle and pipe joint break etc.; The 4th, the environment of burying underground of water supply line mainly concentrates on production and biotope, and the interference noise source is many, and circumstance complication is changeable.Therefore, Leak testtion and the localization method that is generally used for oil transportation or gas pipeline used on water supply line than difficult.

At present, the water supply line leakage detection method is divided into based on the Leak testtion of non-sound signal with based on the leakage detection method of acoustic signal.Leakage detection method based on non-sound signal mainly contains: though minimum discharge method at night is simple, cost is low, efficient is low, poor sensitivity, and poor reliability, and can not locate leak source; The flow equilibrium method requires high to accuracy of instruments such as flowmeters, be not suitable for the multiple-limb pipeline, and can not locate; State observation and modelling are very responsive to disturbance, so wrong report, rate of failing to report height and can not be located; Method costs such as GPR, gas tracking, thermograph are higher.Based on the leakage detection method of acoustic signal is to leak the acoustic signal time domain or frequency domain character leaks identification by extracting, and has based on the localization method that leaks acoustic signal: the related positioning method that time delay is estimated, based on the localization method of degradation of energy characteristic positioning method (Chinese patent 96121000.1) and and modal analysis theoretical based on guided wave etc.Based on leaking the acoustic signal detection related positioning method in the research of water supply line Leak testtion with the most extensive in using.

In Leak testtion and position fixing process, when water supply line leakage acoustic signal is picked up, the environmental conditions complexity, the uncertain non-stationary of all kinds disturbs and may take place at any time, as the vibration of boring ground in traffic noises such as car horn, motor, the mechanical execution and impact, the sound of machine run, the voice noise of people's speech etc., the existence that non-stationary disturbs can directly cause detecting and the inefficacy of localization method; In addition, the backflow noise that also has lateral place in domestic noise, the pipe, noise in irregular pipeline section and pipe wall material sudden change place reflection generation, the influence of the multiple stationary noises such as water noise that excite in valve, elbow, so the leakage observation signal signal to noise ratio of actual reception is extremely low, thereby influences detection sensitivity and good location accuracy.Therefore, be necessary to carry out denoising, identification of leaking then and location, thereby sensitivity, degree of accuracy and the locating accuracy of raising Leak testtion.On the other hand, generally adopt at present based on the Leak testtion and the location of leaking the acoustic signal correlation analysis, be actually that a step finishes.If in the signal of gathering the crosscorrelation composition is arranged, and relevant composition is not from leaking sound source, manage the non-leakage noise that send external and internal fixation positions but derive from other, then can being mistaken for leakage, and being positioned as leakage point.So identification is leaked, should be the prerequisite of location leakage point.

Summary of the invention

The invention discloses the signal processing method of a kind of water supply line Leak testtion location, this method is carried out the denoising pretreatment to the information of gathering and is improved signal quality, leaks identification and leakage positioning then.

Wherein, the signal of gathering is at first judged whether to exist bursty interference before the denoising pretreatment, carry out the denoising pretreatment then, described denoising pretreatment comprises removes bursty interference and suppresses stationary noise.

Described removal bursty interference noise step is:

1) will gather the N segment signal that signal is divided into equal length, guaranteeing to have at least does not have the bursty interference noise in the segment signal;

2) calculate each segment signal wavelet coefficient x in the N segment signal _WcModulus maximum ρ _i, (i=1,2 ..., N);

3) ask minimum according to the maximum of each segment signal wavelet coefficient mould, obtain the threshold value η=min (ρ of denoising _i), (i=1,2 ..., N);

4) non-linear denoising operation, $x_{\mathrm{wc}}=\left\{\begin{array}{cc}{x}_{\mathrm{wc}}& \mathrm{if}\left|x_{\mathrm{wc}}\right|\≤\mathrm{\η}\\ 0& \mathrm{otherwise}\end{array}\right.;$

5) wavelet coefficient after the non-linear denoising is reconstructed, obtains to gather stably signal.

Described inhibition stationary noise signal adopts the stationary noise inhibition method of error albefaction criterion-linear prediction-adaptive cancellation, select the suitable l step, with the prediction the signal relevant with useful signal as the reference signal, the original mixed signal passes through the adaptive cancellation device as input, from mixed signal, deduct the useful signal composition, suppressed noise.

Describedly be to gathering the step that signal leaks identification:

Gather the relevant peaks of signal by two-way and judge that two paths of signals has or not coherence,, then do not have leakage if relevant peaks does not exist; If peak value is obvious, need then to judge that this relevant peaks is to be gathered that relevant leakage noise in the signal causes or caused by pipe external and internal fixation sound source noise by two-way, if the approximate entropy of the self correlation function of signal is less than a certain threshold value (this threshold value is derived from the different of the approximate entropy of correlation function according to leakage noise and steady noise and determines), judge that relevant peaks is to be caused by pipe external and internal fixation sound source, otherwise, judge that this relevant peaks is to be caused by leakage noise, leak existence.

Describedly be to gathering the step that signal carries out leakage positioning:

Estimating the relative time that leakage noise propagates into two end sensors postpones

Utilize the length l in path and the information of velocity of propagation v of knowing again, according to ranging formula: $l_1,l_2=\frac{l\±v\·\hat{D}}{2},$ Estimate to obtain the position of leakage point, l ₁, l ₂Be respectively leak source and arrive the diffusion path length of two end sensors.

Useful technique effect of the present invention is: by to the removal of gathering bursty interference in the signal with to denoisings such as Noise Suppression, improve quality of signals, identification of leaking then and location, thus the degree of accuracy and the leak source locating accuracy of water supply line leakage identification under the complicated noise improved.

Description of drawings

Fig. 1 is the signal processing method flow process of water supply line Leak testtion location;

Embodiment

With two Check points as an example, specific implementation method of the present invention is described in detail below.At first introduce detection and location device of the present invention, it is made up of four parts: piezoelectric acceleration sensor is used to pick up the leakage acoustic signal at doubtful leak source two ends, and is converted into electrical signal; The embedded data acquisition unit amplifies/signal conditions such as filtering the simulated leakage signal that picks up, and converts digital signal and storage to by A/D; USB/ is wired, the WLAN communication interface, is used for gathering and to convert to the main frame that is transferred to of digital signal; A plurality of probe leakage signals that main frame will collect are handled, and propose leakage information and also locate the leak position, provide and show final Leak testtion and positioning result.What next introduce is exactly concrete application of the present invention:

At first, there are the doubtful leak source two ends of the water supply line of leak source to place sensor respectively in suspection to pick up the leakage acoustic signal.Sensor can place on the fire hydrant that exposes on ground, the exposed tube wall, on down-hole fire hydrant or the pipe joint, can select according to piping laying environment different under the actual detected condition, and standard is to the most effective position of leakage information collection.

The leakage signal that sensor is picked up by data acquisition unit amplify, signal condition such as filtering, to improve the signal to noise ratio of gathering signal, carry out the A/D conversion and be stored in the storage unit of collector.The collection signal of storage is transferred to main frame and is carried out signal processing by communication interface such as USB interface, wire/wireless lan interfaces, and whether extract leakage information and diagnosis has and leak and provide the leak source position.

To Signal Processing is key point of the present invention.In the gatherer process of signal, owing to have noise interference miscellaneous in the testing environment, comprise that mainly bursty interference is (as car horn, traffic noises such as motor, bore the vibration and the impact on ground in the mechanical execution, the sound of machine run, the voice noises of people speech etc.) and generally noise (also can be described as stationary noise, as domestic noise, the backflow noise at pipe branch pipe place, noise in irregular pipeline section and pipe wall material sudden change place reflection generation, at valve, the water noise that the elbow excites etc.) two big classes, the actual acquisition Signal-to-Noise is low, influence detects effect, so must carry out denoising to the information that collects.The generation of bursty interference is unpredictable, and extraction and diagnosis to follow-up leakage information have material impact, therefore the leakage signal to gathering at first needs to judge to have or not bursty interference to exist: if bursty interference does not exist the treatment phase of directly entering follow-up noise suppression; If but the bursty interference existence then needs to carry out the removal of bursty interference.The bursty interference removal method that the present invention program adopts is:

1) will gather the N segment signal that signal is divided into equal length, guaranteeing to have at least does not have the bursty interference noise in the segment signal;

2) calculate each segment signal wavelet coefficient x in the N segment signal _WcModulus maximum ρ _i, (i=1,2 ..., N);

3) ask minimum according to the maximum of each segment signal wavelet coefficient mould, obtain the threshold value η=min (ρ of denoising _i), (i=1,2 ..., N);

4) non-linear denoising operation, $x_{\mathrm{wc}}=\left\{\begin{array}{cc}{x}_{\mathrm{wc}}& \mathrm{if}\left|x_{\mathrm{wc}}\right|\≤\mathrm{\η}\\ 0& \mathrm{otherwise}\end{array}\right.;$

5) wavelet coefficient after the non-linear denoising is reconstructed, obtains to gather stably signal.

To removing after the bursty interference or disturbing non-existent nearly stationary signal to implement noise suppression and handle, what adopt is the noise suppressing method of error albefaction criterion-linear prediction-adaptive cancellation (EWC-LP-ANC): utilize useful signal correlation time greater than the noise characteristics of correlation time, (choose according to error albefaction criterion, retardation l is greater than the correlation length cl of noise to select suitable l step delay _nAnd less than the correlation length cl of useful signal _s), can carry out linear prediction and can not predict noise to signal, with the signal relevant that dope as a reference with useful signal, the original mixed signal as input by the adaptive cancellation device, extract the useful signal composition from mixed signal, reach the purpose that suppresses noise.This method strengthens the signal to noise ratio of signal by suppressing noise, is convenient to effectively extract the leakage information that is submerged in the noise, and accurately locatees.The multiple that the signal to noise ratio of utilizing this method of EWC-LP-ANC will gather signal improves is: $\frac{{\mathrm{\ρ}}_{\mathrm{out}}\left(z\right)}{{\mathrm{\ρ}}_{\mathrm{pri}}\left(z\right)}=1+\frac{1}{{\mathrm{\ρ}}_{\mathrm{pri}}\left(z\right)}>1.$ ρ _Out(z) for suppressing the signal to noise ratio of front signal, ρ _Pri(z) be the Signal-to-Noise after suppressing.

After removing bursty interference and suppressing noise, identification and location that the high quality Information Monitoring that pretreatment is obtained is leaked.At first be the identification of leaking: the relevant peaks of gathering signal by two-way judges that two paths of signals has or not coherence, if relevant peaks does not exist, does not then have leakage; If peak value is obvious, need then to judge that this relevant peaks is to be gathered that relevant leakage noise in the signal causes or caused by the non-leakage sound source of pipe external and internal fixation noise by two-way.If the approximate entropy of the self correlation function of signal is less than a certain threshold value (this threshold value is derived from the different of the approximate entropy of correlation function according to leakage noise and steady noise and determines), judge that relevant peaks is to be caused by pipe external and internal fixation sound source, otherwise, judge that this relevant peaks is to be caused by leakage noise, leak existence.

When confirming that leakage exists, need to determine the particular location of leakage.The concrete method that adopts is: the relevant information of gathering signal by doubtful leak source two ends positions.Estimating the relative time that leakage noise propagates into two end sensors postpones

Utilize the length l in path and the information of velocity of propagation v of knowing again, according to ranging formula: $l_1,l_2=\frac{l\±v\·\hat{D}}{2},$ Estimate to obtain the position of leakage point.l ₁, l ₂Be respectively leak source and arrive the diffusion path length of two end sensors.The relative time that signal is gathered at two ends postpones

Generally adopt broad sense crosscorrelation delay time estimation method, but need statistics such as known input signal power spectrum, noise power spectrum to construct prefilter as priori, in actual Leak testtion engineering practice, these parameters often are difficult to accurately know.Therefore determine that the particular location that leaks adopts novel adaptive time delay estimation.Utilize sef-adapting filter to make automatic adjustment of filter parameter reach the optimum state by self adaption actual acquisition signal characteristic, without any need for priori statistical knowledge about signal and noise, directly extract the similarity of two signals by filter parameter, when sef-adapting filter enters stable state, weight vector is carried out peak value detect, the peak value position is time delay and estimates

For the signal processing of a plurality of Check points, in fact be exactly the information processing of two Check points and the extension of leaking identification and location.Do not give unnecessary details at this.

Claims (6)

1. A signal processing method for water supply pipeline leak detection and location, characterized in that: the collected information is denoised and preprocessed to improve signal quality, and then leak identification and leak location are performed. 2. The signal processing method for detecting and locating water supply pipeline leaks according to claim 1, characterized in that: before the denoising preprocessing of the collected signal, it is first judged whether there is a sudden interference, and then the denoising preprocessing is carried out. The denoising preprocessing includes removing burst interference and suppressing noise. 3. The signal processing method for detecting and locating water supply pipeline leaks according to claim 2, characterized in that: the step of removing sudden interference noise is as follows: 1) Divide the collected signal into N segments of equal length to ensure that there is no burst interference noise in at least one segment of the signal; 2) Calculating the modulus maxima ρ _i , (i=1, 2, ..., N) of the wavelet coefficient x _wc of each segment signal in the N segment signals; 3) seek the minimum according to the maximum value of the wavelet coefficient modulus of each section signal, and obtain the denoising threshold η=min(ρ _i ), (i=1, 2, ..., N); 4) nonlinear denoising operation, $x_{\mathrm{wc}}=\left\{\begin{array}{ccc}{x}_{\mathrm{wc}}& \mathrm{if}& \left|x_{\mathrm{wc}}\right|\≤\mathrm{\η}\\ 0& & \mathrm{otherwise}\end{array}\right.;$ 5) Reconstruct the wavelet coefficients after nonlinear denoising to obtain a stable acquisition signal. 4. The signal processing method for leak detection and location of water supply pipeline according to claim 2, characterized in that: suppressing the stationary noise signal adopts the stationary noise suppression method of error whitening criterion-linear prediction-adaptive cancellation, selects an appropriate step, and predicts The signal related to the useful signal is used as a reference signal, and the original mixed signal is passed through an adaptive canceller as an input, and the useful signal component is subtracted from the mixed signal to suppress noise. 5. The signal processing method for detecting and locating water supply pipeline leakage according to claim 1, characterized in that: the step of identifying the leakage of the collected signal is as follows: Use the correlation peaks of the two acquisition signals to determine whether the two signals are correlated. If the correlation peak does not exist, there is no leakage; if the peak is obvious, it needs to be judged that the correlation peak is caused by the correlation leakage noise in the two acquisition signals. If the approximate entropy of the autocorrelation function of the signal is less than a certain threshold (the threshold is determined according to the difference between the leakage noise and the fixed noise from the approximate entropy of the correlation function), it is judged that the correlation peak is It is caused by fixed sound sources inside and outside the pipe, otherwise, it is judged that the correlation peak is caused by leakage noise, and the leakage exists. 6. The signal processing method for detecting and locating water supply pipeline leakage according to claim 1, characterized in that: the step of locating the collected signal for leakage is: Estimate the relative time delay for the leakage noise to propagate to the sensors at both ends

Then use the information of the known path length l and propagation velocity v, according to the positioning formula: $l_1,l_2=\frac{l\±v\·\widehat{\mathrm{D.}}}{2},$ Estimate the location of the leak point, l ₁ , l ₂ are the propagation path lengths from the leak point to the sensors at both ends, respectively.

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