Water supply pipeline leakage detecting and positioning method based on one-dimensional flexible sensor array system

Abstract

The invention provides a water supply pipeline leakage detecting and positioning method based on a one-dimensional flexible sensor array system. The system comprises a package carrier tape, a flexible piezoelectric film vibration detection sensor, a signal amplification module, a signal multiplexer, a wireless transmission module and a terminal intelligent analysis module. The sensor obtains vibration signals of all positions of the surface of the pipeline. The vibration signals are sequentially selected by the signal multiplexer and then sent to the signal amplification module for signal amplification, and the amplified vibration signals are sent to the terminal intelligent analysis module through the wireless transmission module. The terminal intelligent analysis module analyzes and processes data of the vibration detection sensor. And performing water supply pipeline leakage detection and positioning based on an SVM method and a CBF method. The method can be applied to detection and positioning of urban water supply pipeline leakage, and provides powerful theoretical support and application guidance for improving the urban water supply pipe network management capability in China.

Description

Technical Field

[0001] The invention relates to a pipeline detection method, in particular to a water supply pipeline leakage detection and positioning method based on a one-dimensional flexible sensor array system. Background Art

[0002] The urban water supply system is one of the important infrastructures for the survival and development of the city. However, due to the long-term underground burial of water supply pipelines, pressure operation and pipe quality, the pipelines are prone to corrosion, aging, blockage, deformation, cracking and other problems. In addition to factors such as ground subsidence and human damage, leakage accidents such as pipeline leakage and pipe bursting frequently occur, and there has been a lack of effective solutions for a long time. According to statistics from the Ministry of Housing and Urban-Rural Development, more than 8 billion cubic meters of water resources were lost from the urban water supply system in 2017, which is equivalent to the total water consumption of 100 million people in one year. In addition to causing a large amount of waste of water resources, pipeline leakage may also cause external pollution of water supply, affect the health of urban residents, and cause water supply interruption in urban communities and production suspension of enterprises. In order to save water resources, ensure the normal progress of people's lives and production activities, and promote the construction and development of smart cities, it is urgent to fundamentally solve the leakage problem of urban water supply systems. Effective leakage detection is the first link in solving the leakage problem of urban water supply pipe networks. In order to reduce the resource, economic losses and social harm caused by leakage, a pipeline leakage detection method with higher leakage detection capability and positioning accuracy is proposed, which is of great significance to shorten the average duration of leakage and reduce the total leakage water volume. Summary of the invention

[0003] In order to solve the problems in the prior art, the present invention proposes a water supply pipeline leakage detection and positioning method based on a one-dimensional flexible sensor array system.

[0004] The technical solution adopted by the present invention is as follows:

[0005] On the one hand, the present invention provides a one-dimensional flexible sensor array system for water supply pipeline leakage detection and stereo positioning, comprising:

[0006] S1: Construct a one-dimensional flexible sensor array system consisting of a wrapping carrier, a flexible piezoelectric film vibration detection sensor, a signal multiplexer, a signal amplification module, a wireless transmission module and a terminal intelligent analysis module, arrange multiple flexible piezoelectric film vibration detection sensors in a one-dimensional linear and equidistant manner and fix them in the wrapping carrier, and evenly wrap the wrapping carrier around the target pipeline in a spiral wrapping form;

[0007] S2: Detecting vibrations at different positions on the surface of the target pipeline by the sensor and outputting a first vibration signal;

[0008] S3: The first vibration signals of each sensor are selected in sequence by a multiplexer, and the selected first vibration signals are amplified by a signal amplification module and converted into second vibration signals, and the second vibration signals are transmitted to the terminal intelligent analysis module through a wireless transmission module;

[0009] S4: The terminal intelligent analysis module performs signal denoising and signal feature extraction on the second vibration signal corresponding to each sensor, and uses a beamforming method based on maximum power output to locate the pipeline leakage point.

[0010] On the other hand, the present invention also proposes a one-dimensional flexible sensor array system for implementing the above-mentioned water supply pipeline leakage detection and positioning method, comprising: a wrapping carrier, a flexible piezoelectric film vibration detection sensor, a signal multiplexer, a signal amplification module, a wireless transmission module and a terminal intelligent analysis module;

[0011] The wrapping carrier tape is evenly wound around the target pipe in a spiral wrapping form; and is used to convert the vibration at the location into a first vibration signal output;

[0012] The signal multiplexer is used to select the first vibration signal of each sensor in turn, so that each first vibration signal is transmitted serially to the signal amplification module;

[0013] The signal amplification module is used to amplify the first vibration signal of each sensor and output it, and the amplified signal is the second vibration signal;

[0014] The wireless transmission module is used to send the second vibration signal corresponding to each sensor to the terminal intelligent analysis module;

[0015] The terminal intelligent analysis module is used to detect and locate pipeline leaks based on the output signal of the signal multiplexer and adopt a beam forming method based on maximum power output.

[0016] Compared with the prior art, the beneficial effects of this application are as follows:

[0017] 1. The present invention utilizes the flexibility of the flexible piezoelectric film vibration detection sensor to make the sensor better attached to the pipeline surface, thereby improving the detection performance of the sensor;

[0018] 2. The present invention combines signal denoising and signal feature extraction to process vibration leakage signals, and has higher leakage detection capability;

[0019] 3. The present invention combines sensor array signal comparison and adopts a beamforming method based on maximum power output to locate pipeline leakage through the difference in actual sensor array receiving signals caused by the leakage source, thereby achieving more accurate leakage point detection and positioning. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic diagram of a one-dimensional flexible sensor array of the present invention;

[0021] Figure 2 is a schematic diagram of the flexible vibration sensor of the present invention;

[0022] Figure 3 is a schematic diagram of the distribution of the one-dimensional flexible sensor array of the present invention in a pipeline;

[0023] Figure 4 is the decomposition result of the voltage signal output by the sensor in the present invention;

[0024] Figure 5 is the judgment result of leakage detection of the one-dimensional flexible sensor array of the present invention;

[0025] Figure 6 This is the pipeline leakage positioning result of the one-dimensional flexible sensor array of the present invention. DETAILED DESCRIPTION

[0026] The present invention proposes a method for leak detection and stereo positioning of a city water supply pipeline based on a one-dimensional flexible sensor array. The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0027] In order to save water resources, ensure the normal life and production activities of the people, and promote the construction and development of smart cities, it is urgent to fundamentally solve the leakage problem of urban water supply systems.

[0028] The present invention conducts research from the perspectives of improving the sensing capability, detection reliability, positioning accuracy and engineering deployment of flexible sensors for pipeline leakage detection, and uses the outstanding advantages and characteristics of flexible piezoelectric materials in pipeline leakage detection and positioning to establish new theories and methods for urban water supply pipeline leakage detection and positioning based on flexible sensors, improve the detection capability of small leakage conditions such as hidden leakage and seepage, and realize three-dimensional high-precision positioning of pipeline leakage, providing new ideas for pipeline leakage detection research. At the same time, the distributed network deployment of flexible sensors is realized by combining self-power supply, Internet of Things and cloud services, and a smart pipeline system is constructed.

[0029] To achieve the above objectives, the present invention proposes a water supply pipeline leakage detection and positioning method based on a one-dimensional flexible sensor array system. The one-dimensional flexible sensor array system includes: a wrapping carrier, a flexible piezoelectric film vibration detection sensor array, a signal amplification module, a signal multiplexer, a wireless transmission module, and a terminal intelligent analysis module.

[0030] The method comprises: fixing the flexible piezoelectric film vibration detection sensor array on the package carrier at equal intervals according to the accuracy requirements of the target pipeline detection and positioning, acquiring the pipeline vibration signal to realize the leakage detection and positioning of the urban water supply pipeline; the signal amplification module amplifies the pipeline vibration signal and transmits it to the signal multiplexer; the signal multiplexer selects the amplified output signal of each sensor for further data transmission; the wireless communication module transmits the output data of the signal multiplexer to the terminal intelligent analysis module; the terminal intelligent analysis module analyzes and processes the data of the vibration detection sensor to detect and locate the leakage of the urban water supply pipeline.

[0031] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] A one-dimensional flexible sensor array system, comprising: a wrapping carrier, a flexible piezoelectric film vibration detection sensor, a signal amplification module, a signal multiplexer, a wireless transmission module, and a terminal intelligent analysis module, characterized in that:

[0033] The wrapping carrier uses polycarbonate (PC) as the carrier material, which has high strength and elastic coefficient, high impact strength, good fatigue resistance, good dimensional stability, and no obvious creep. It also has excellent insulation performance and can maintain its high performance in a humid environment to protect the flexible piezoelectric film vibration detection sensor. The wrapping carrier uses two layers of polycarbonate as the protective material to wrap the flexible piezoelectric film vibration detection sensor array and its signal transmission line in it to isolate various influences such as soil cover, high humidity environment, and corrosion that may exist in the pipeline operation environment;

[0034] The flexible piezoelectric film vibration detection sensor includes a sensitive layer, an aluminum film layer located on both sides of the sensitive layer, electrodes located on both sides of the aluminum film layer, and a soft packaging layer for sensor packaging. In this embodiment, polyvinylidene fluoride (PVDF) is used as the sensitive layer to sense the vibration of the pipeline surface and convert it into an electrical signal; the aluminum film layer is wrapped on both sides of the polyvinylidene fluoride to conduct the electrical signal to the electrode, and also plays a role in protecting the sensitive layer; the electrode is a copper foil attached to both sides of the aluminum film and outputs the first vibration signal through a wire; and the last soft packaging layer is a polyimide film.

[0035] In this embodiment, the size of the sensor is 3mm*2mm, the thickness of the sensitive layer is 50um, the thickness of the aluminum film layer is 10um, which is the same size as the sensitive layer, the thickness of the electrode is 60um, and the thickness of the soft packaging layer is 50um.

[0036] A plurality of flexible piezoelectric film vibration detection sensors are arranged in a one-dimensional manner with equal spacing to form a flexible piezoelectric film vibration detection sensor array. The flexible piezoelectric film vibration detection sensor array is fixed in the package carrier at equal spacing according to the accuracy requirements of the target pipeline detection and positioning, and is used to obtain the vibration signal of the pipeline to realize the leakage detection and positioning of the urban water supply pipeline;

[0037] The signal multiplexer is used for signal selection of the flexible piezoelectric film vibration detection sensor array and transmits the output data to the signal amplification module;

[0038] The signal amplification module is used to amplify the first vibration signal of each sensor, the amplified signal is the second vibration signal, and the transimpedance amplifier is selected according to the detection principle of the flexible piezoelectric film vibration sensor;

[0039] The wireless communication module receives the second vibration signal and transmits it to the terminal intelligent analysis module;

[0040] The terminal intelligent analysis module is used to analyze and process the signals transmitted by the wireless communication module to detect and locate urban water supply pipeline leaks.

[0041] The target pipeline detection and positioning accuracy requirements are fixed on the package carrier at equal intervals. In this example, the 9 groups of flexible sensors are distributed on the package carrier at a spacing of 1000mm to form a one-dimensional flexible piezoelectric film vibration detection sensor array up to 10m, and the electrical connection is achieved with wires for the sensor signal to be output to the signal amplification module for processing. The one-dimensional flexible sensor array system is wrapped around the pipeline in a spiral wrapping form with a winding density of 0.2 turns / m to facilitate the subsequent three-dimensional positioning of pipeline leakage.

[0042] A method for detecting and locating water supply pipeline leakage based on the one-dimensional flexible sensor array system comprises the following steps:

[0043] S1. After the one-dimensional flexible sensor array system is installed, the vibration detection sensor array fixed in the package carrier is attached to the pipeline surface and can output electric charge in response to the vibration generated on the pipeline surface. The electric charge that changes with the vibration is the first vibration signal collected.

[0044] S2. The multiplexer selects each vibration detection sensor in turn, so that the first vibration signal of each sensor is output in series, and the sampling duration of each sensor is 1s; the selected first vibration signal is input into the signal amplification module, and after signal amplification, it is converted into a second vibration signal and transmitted to the multiplexer for further processing; the second vibration signal of each sensor is transmitted to the intelligent analysis module in the terminal through the wireless transmission module for signal analysis and processing;

[0045] S3. The terminal intelligent analysis module processes the vibration leakage signal according to the second vibration signal leakage corresponding to each sensor transmitted by the wireless transmission module, combining the signal denoising and signal feature extraction methods, and determines the pipeline leakage in combination with the pipeline leakage detection model. If there is a leakage, the conventional beamforming (CBF) method based on maximum power output is used to locate the pipeline leakage point.

[0046] Specifically, the vibration signal collected by the flexible sensor not only contains the vibration signal of the leaking part of the pipeline, but is also affected by noise such as the external environment or the natural frequency of the pipeline during the transmission process.

[0047] Therefore, the present invention first performs signal denoising: based on the second vibration signal transmitted by the wireless transmission module, the variational mode decomposition method (VMD) is used to perform multi-scale adaptive decomposition of the non-stationary, nonlinear original observed vibration signal, extract the effective intrinsic mode function and perform multi-resolution analysis and reconstruction, thereby achieving signal denoising and obtaining the third vibration signal. The variational mode decomposition method is a non-stationary signal adaptive decomposition estimation method, which essentially decomposes the original complex signal into multiple inherent modes with limited frequency bandwidth, and obtains these modes through a constrained energy function. The present invention uses the VMD method to non-recursively and perform variational mode decomposition to process the original signal to achieve denoising of the leakage signal.

[0048] Then the signal feature extraction is carried out: based on the third vibration signal, the leakage signal characteristic parameters are extracted, and with the help of principal component analysis feature extraction method, the Pearson correlation coefficient between the signal characteristic parameters is calculated. The PCA method is used to select the signal characteristic parameters with a higher correlation coefficient to reduce the dimension and generate a two-dimensional feature quantity, which is convenient for the subsequent classification processing of the model.

[0049] Specifically, the present invention improves the effect of practical application by selecting appropriate characteristic parameters of the signal in time domain, frequency domain and time-frequency domain. The selected leakage signal characteristic parameters are as follows: maximum value, minimum value, average value, median, peak-to-peak value, rectified average value, variance, standard deviation, root mean square, root mean square value, root amplitude, kurtosis, waveform factor, peak factor, pulse factor, margin factor, approximate entropy of the original signal, maximum value, average value, minimum value of the power spectrum, and root mean square of the six modes after VMD decomposition.

[0050] Finally, pipeline leakage is identified and located: based on the signal feature extraction results, a detection model is established using machine learning algorithms such as support vector machines, and support vector data description methods are used to perform single-class anomaly detection of leakage signals.

[0051] The flexible sensor array of the present invention is used to obtain vibration signals, and the pipeline leakage point is located using a beam forming method based on maximum power output. The location method of the algorithm is as follows:

[0052] (1) The vibration signal generated by the pipeline leakage source propagates along the pipeline surface. The signal received by the sensor array is defined as x m (t). Signal characteristics of sensors at different positions x m With x n The power cross spectrum matrix C(f) (CrossSpectrum Matrix) is defined as:

[0053]

[0054] Where X m With X n is the sensor signal characteristic x m With x n The frequency domain signal characteristics obtained by fast Fourier transform, f is the real-time frequency.

[0055] (2) In order to obtain the beamformer output, a leakage source plane is defined at any position as the expansion of the pipeline surface. Each sensor position is focused to different positions on the leakage source plane by mapping. One of the sensors is defined as the reference sensor. The results obtained from all the focused positions are combined into a vector, i.e., the vibration power steering vector h at each point on the scanning plane. l (r m ,f):

[0056]

[0057] where g l (.) is the Green's function based on the free field, M is the normalization matrix, r m is the position of the mth sensor; r 0l is the distance between the reference sensor (defined as the most central sensor in this embodiment) and its corresponding focus position, r ml is the distance between the mth sensor and its corresponding focus position, c is the signal propagation speed, e is jω is the basis of the frequency domain signal, and the superscript H represents the conjugate transpose.

[0058] (3) Finally, the vibration power steering vector h can be used l (r m ,f) and the power cross-spectral matrix C(f) to obtain the beamformer output matrix P CBF (w):

[0059] P CBF (w) = h l (f)H C(f)h l (f)

[0060] Each element in the beamformer output matrix is ​​the power of sensors at different positions, and the sensor position with the largest power is the location of the leakage point.

[0061] The present invention can not only provide a new idea for pipeline leakage detection and positioning, greatly improve the operating stability and intelligence level of the existing urban water supply system, and contribute to the construction of smart cities, but also provide useful reference for research on vibration signal acquisition and analysis based on flexible materials, layout optimization of sensor arrays, and engineering applications. It has important academic value and broad practical application prospects.

[0062] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. For ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A water supply pipeline leakage detection and positioning method based on a one-dimensional flexible sensor array system, characterized in that: The method comprises: S1: Construct a one-dimensional flexible sensor array system consisting of a wrapping carrier, a flexible piezoelectric film vibration detection sensor, a signal multiplexer, a signal amplification module, a wireless transmission module and a terminal intelligent analysis module, arrange multiple flexible piezoelectric film vibration detection sensors in a one-dimensional linear and equidistant manner and fix them in the wrapping carrier, and evenly wrap the wrapping carrier around the target pipeline in a spiral wrapping form; S2: Detecting vibrations at different positions on the surface of the target pipeline by the sensor and outputting a first vibration signal; S3: The first vibration signals of each sensor are selected in sequence by a multiplexer, and the selected first vibration signals are amplified by a signal amplification module and converted into second vibration signals, and the second vibration signals are transmitted to the terminal intelligent analysis module through a wireless transmission module; S4: The terminal intelligent analysis module performs signal denoising and signal feature extraction on the second vibration signal corresponding to each sensor, and uses a beamforming method based on maximum power output to locate the pipeline leakage point.

2. The water supply pipeline leakage detection and positioning method according to claim 1, characterized in that: The signal denoising is achieved by using a variational mode decomposition method; the signal feature extraction is specifically to extract the leakage signal characteristic parameters of the second vibration signal, calculate the Pearson correlation coefficient between the signal characteristic parameters, and use the PCA method to select signal features with higher correlation coefficients and reduce them into two-dimensional characteristic parameters.

3. The water supply pipeline leakage detection and positioning method according to claim 2, characterized in that: The leakage signal characteristic parameters are: the maximum value, minimum value, average value, median, peak-to-peak value, rectified average value, variance, standard deviation, root mean square, root mean square value, root amplitude, kurtosis, waveform factor, peak factor, pulse factor, margin factor, approximate entropy, power spectrum maximum value, power spectrum average value, power spectrum minimum value, and the root mean square of each mode obtained by variational mode decomposition.

4. The water supply pipeline leakage detection and positioning method according to claim 1, characterized in that: The method of using the beamforming method based on maximum power output to locate the pipeline leakage point is specifically as follows: 1) Calculate the signal characteristics x of sensors at different positions by the following formula: m With x n The power cross-spectral matrix C(f) is: Where X m With X n is the sensor signal characteristic x m With x n The frequency domain signal characteristics obtained by fast Fourier transform, f is the real-time frequency; 2) Define a leakage source plane at any position as the expansion of the pipeline surface, focus each sensor position to different positions of the leakage source plane through mapping, define one of the sensors as the reference sensor, and scan the vibration power steering vector h at each point on the leakage source plane. l (r m ,f), its expression is as follows: where g l (.) is the Green's function based on the free field, M is the normalization matrix, r m is the position of the mth sensor; r 0l is the distance between the reference sensor and its corresponding focus position, r ml is the distance between the mth sensor and its corresponding focus position, c is the signal propagation speed, e is jω is the basis of the frequency domain signal, and the superscript H represents the conjugate transpose; 3) Based on the vibration power steering vector h l (r m ,f) and the power cross-spectral matrix C(f) to obtain the beamformer output matrix P CBF (w), which is expressed as follows: P CBF (w)=h l (f) H C(f)h l (f) The beamformer output matrix P CBF Each element in (w) is the power of sensors at different positions, and the sensor position with the largest power is the location of the leak.

5. The water supply pipeline leakage detection and positioning method according to claim 1, characterized in that: The sensor includes a sensitive layer, an aluminum film layer located on both sides of the sensitive layer, electrodes located on both sides of the aluminum film layer, and a packaging layer for sensor packaging; the sensitive layer is polyvinylidene fluoride, which is used to sense the vibration of the pipeline surface and convert it into an electrical signal; the electrodes are connected to the signal amplification module through wires; the aluminum film layer is used to conduct electrical signals and protect the sensitive layer; the packaging layer is a polyimide film.

6. The water supply pipeline leakage detection and positioning method according to claim 5, characterized in that: The thickness of the sensitive layer is 50um, the thickness of the aluminum film layer is 10um, the thickness of the electrode is 60um, and the thickness of the packaging layer is 50um; the sensitive layer and the aluminum film layer have the same size.

7. The water supply pipeline leakage detection and positioning method according to claim 1, characterized in that: The wrapping carrier tape is made of two layers of polycarbonate, and the sensor is wrapped between the two layers of polycarbonate.

8. The water supply pipeline leakage detection and positioning method according to claim 1, characterized in that: The signal amplification module adopts a transimpedance amplifier.

9. A one-dimensional flexible sensor array system for implementing the water supply pipeline leakage detection and positioning method according to claim 1, characterized in that: The system comprises: a package carrier, a flexible piezoelectric film vibration detection sensor, a signal multiplexer, a signal amplification module, a wireless transmission module and a terminal intelligent analysis module; The wrapping carrier tape is evenly wound around the target pipe in a spiral wrapping form; and is used to convert the vibration at the location into a first vibration signal output; The signal multiplexer is used to select the first vibration signal of each sensor in turn, so that each first vibration signal is transmitted serially to the signal amplification module; The signal amplification module is used to amplify the first vibration signal of each sensor and output it, and the amplified signal is the second vibration signal; The wireless transmission module is used to send the second vibration signal corresponding to each sensor to the terminal intelligent analysis module; The terminal intelligent analysis module is used to detect and locate pipeline leaks based on the output signal of the signal multiplexer and adopt a beam forming method based on maximum power output.

Images