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

Abstract

The application provides a water supply pipeline leakage detection and positioning method based on a one-dimensional flexible sensor array system. The system comprises a wrapping 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 acquires vibration signals at various positions on the pipeline surface. The vibration signals are sequentially selected by the signal multiplexer and then sent to the signal amplification module for signal amplification. 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 the data of the vibration detection sensor and performs water supply pipeline leakage detection and positioning based on the SVM method and the CBF method. The application can be applied to the detection and positioning of urban water supply pipeline leakage and provides strong theoretical support and application guidance for improving the management ability of urban water supply pipeline networks in China.

Description

Technical Field

[0001] The present 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] Urban water supply systems are crucial infrastructure for the survival and development of cities. However, due to the long-standing underground location of water supply pipelines, their operation under pressure, and the quality of the pipes, they are prone to corrosion, aging, blockage, deformation, and cracking. Coupled with factors such as land subsidence and vandalism, leaks and bursts frequently occur, and effective solutions have long been lacking. According to statistics from the Ministry of Housing and Urban-Rural Development, over 8 billion cubic meters of water were lost from urban water supply systems in 2017, equivalent to the annual water consumption of 100 million people. Pipeline leaks not only waste significant water resources, but can also contaminate the water supply, impacting the health of urban residents, and causing water supply disruptions in urban communities and production halts in businesses. To conserve water resources, ensure the normal operation of people's lives and production, and promote the development of smart cities, there is an urgent need to fundamentally address the leakage issues in urban water supply systems. Effective leak detection is a key component in addressing leaks in urban water supply 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 shortening the average duration of leakage and reducing the total amount of leaked water. 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 in the present invention is as follows:

[0005] In one aspect, the present invention provides a one-dimensional flexible sensor array system for water supply pipeline leak 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. Multiple flexible piezoelectric film vibration detection sensors are fixed to the wrapping carrier in a one-dimensional linear and evenly spaced arrangement. The wrapping carrier is then evenly wrapped around the target pipeline in a spiral.

[0007] S2: Detecting vibrations at different locations on the surface of the target pipe using the sensor and outputting a first vibration signal;

[0008] S3: The first vibration signals of each sensor are sequentially selected by a multiplexer, 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 via 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 sequentially select the first vibration signal of each sensor, 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 beamforming method based on maximum power output.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1. The present invention utilizes the flexibility of the flexible piezoelectric film vibration detection sensor to better adhere the sensor to the pipe surface, thereby improving the sensor's detection performance;

[0018] 2. This invention combines signal denoising and signal feature extraction to process vibration leakage signals, resulting in higher leakage detection capabilities;

[0019] 3. The present invention combines sensor array signal comparison with a beamforming method based on maximum power output to locate pipeline leaks through the actual sensor array received signal differences caused by the leak source, enabling more accurate leak point detection and location. 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 Schematic diagram of the distribution of the one-dimensional flexible sensor array in a pipeline according to the present invention;

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

[0024] Figure 5 is the discrimination 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 three-dimensional positioning of urban water supply pipelines based on a one-dimensional flexible sensor array. The present invention is further described below with reference to 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] This paper investigates the use of flexible sensors to improve the sensing capabilities, reliability, and accuracy of pipeline leak detection, as well as to enable their engineering deployment. Leveraging the outstanding advantages and properties of flexible piezoelectric materials in pipeline leak detection and location, this paper establishes a new theory and method for leak detection and location in urban water supply pipelines based on flexible sensors. This method enhances the ability to detect subtle leaks, such as hidden leaks and seepage, and achieves high-precision, three-dimensional positioning of pipeline leaks, providing new insights into pipeline leak detection research. Furthermore, the paper combines self-powered systems, the Internet of Things, and cloud services to achieve distributed networked deployment of flexible sensors, thus building a smart pipeline system.

[0029] To achieve the above objectives, the present invention proposes a water supply pipeline leak detection and location method based on a one-dimensional flexible sensor array system. The one-dimensional flexible sensor array system comprises: 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 includes: fixing a flexible piezoelectric film vibration detection sensor array on the package carrier at equal intervals according to the accuracy requirements of target pipeline detection and positioning, obtaining pipeline vibration signals to realize urban water supply pipeline leakage detection and positioning; the signal amplification module amplifies the pipeline vibration signal and transmits it to a 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 a terminal intelligent analysis module; the terminal intelligent analysis module analyzes and processes the data of the vibration detection sensor to detect and locate urban water supply pipeline leakage.

[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 includes: 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 is made of polycarbonate (PC), which has high strength and elastic modulus, high impact strength, good fatigue resistance, good dimensional stability, and low creep. It also has excellent insulation properties and can maintain its high performance in humid environments to protect the flexible piezoelectric film vibration detection sensor. The wrapping carrier uses two layers of polycarbonate as a protective material to wrap the flexible piezoelectric film vibration detection sensor array and its signal transmission line, thereby isolating it from various influences such as soil cover, high humidity, and corrosion that may exist in the pipeline operating environment.

[0034] The flexible piezoelectric film vibration detection sensor includes a sensitive layer, aluminum film layers located on both sides of the sensitive layer, electrodes located on both sides of the aluminum film layer, and a soft packaging layer for encapsulating the sensor. In this embodiment, the sensitive layer is made of polyvinylidene fluoride (PVDF), which senses vibrations on the pipe surface and converts them into electrical signals. The aluminum film layers are wrapped around both sides of the PVDF, transmitting the electrical signals to the electrodes and also protecting the sensitive layer. The electrodes are copper foil attached to both sides of the aluminum film, which transmit the first vibration signal via wires. Finally, the 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] Multiple flexible piezoelectric film vibration detection sensors are arranged in a one-dimensional array with equal spacing, forming a flexible piezoelectric film vibration detection sensor array. The flexible piezoelectric film vibration detection sensor array is fixed to the package carrier at equal spacings according to the accuracy requirements for target pipeline detection and positioning, and is used to obtain pipeline vibration signals to achieve urban water supply pipeline leak detection and positioning;

[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, and the amplified signal is the second vibration signal. 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 leaks in urban water supply pipelines.

[0041] To ensure accurate detection and positioning of the target pipeline, the sensors are fixed to the carrier tape at equal intervals. In this example, nine sets of flexible sensors are distributed on the carrier tape at 1000 mm intervals to form a 10-meter-long one-dimensional flexible piezoelectric film vibration detection sensor array. Electrical connections are made using wires to transmit sensor signals to a signal amplification module for processing. The one-dimensional flexible sensor array system is spirally wrapped around the pipeline at a density of 0.2 turns / m to facilitate the subsequent three-dimensional localization of pipeline leaks.

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

[0043] S1. After installing the one-dimensional flexible sensor array system, the vibration detection sensor array fixed in the package carrier is attached to the pipeline surface and can output an electric charge in response to the vibration generated on the pipeline surface. The 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 serially output, and the sampling duration of each sensor is 1s; the first vibration signal after selection is input into the signal amplification module, and the signal is amplified and 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 via a wireless transmission module for signal analysis and processing;

[0045] S3. The terminal intelligent analysis module processes the vibration leakage signal based on the second vibration signal leakage corresponding to each sensor transmitted by the wireless transmission module, combining signal denoising and signal feature extraction methods, and determines pipeline leakage in combination with the pipeline leakage detection model. If a leakage exists, 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 and estimation method, and its essence is to decompose the original complex signal into multiple inherent modes with limited frequency bandwidth, and obtain these modes through a constrained energy function. The present invention uses the VMD method to process the original signal non-recursively and by variational mode decomposition to achieve leakage signal denoising.

[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 the 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 the time domain, frequency domain and time-frequency domain. The selected leakage signal characteristic parameters are as follows: 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, form factor, peak factor, pulse factor, margin factor, approximate entropy of the original signal, the maximum value, average value, minimum value of the power spectrum, and the 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 the support vector data description method is 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 a beamforming method based on maximum power output is used to locate pipeline leaks. The specific positioning method of the algorithm is as follows:

[0052] (1) The vibration signal generated by the pipeline leakage source propagates along the pipeline surface, and 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 Frequency domain signal characteristics obtained by fast Fourier transform, where 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, namely, 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 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 l (r m ,f) and the power cross spectrum matrix C(f) to obtain the beamformer output matrix P CBF (w):

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

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

[0061] This invention not only provides a new idea for pipeline leak detection and positioning, greatly improves the operational stability and intelligence level of existing urban water supply systems, and contributes to the construction of smart cities, but also provides a 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-described embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. Persons skilled in the art will readily appreciate that variations and modifications may be made without departing from the scope of the present invention, all of which fall within the scope of protection 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. Multiple flexible piezoelectric film vibration detection sensors are fixed to the wrapping carrier in a one-dimensional linear and evenly spaced arrangement. The wrapping carrier is then evenly wrapped around the target pipeline in a spiral. S2: Detecting vibrations at different locations on the surface of the target pipe using the sensor and outputting a first vibration signal; S3: The first vibration signals of each sensor are sequentially selected by a multiplexer, 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 via 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 based on the one-dimensional flexible sensor array system according to claim 1 is 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 each signal characteristic parameter, and use the PCA method to select signal features with a higher correlation coefficient and reduce the dimension to two-dimensional feature parameters.

3. The water supply pipeline leakage detection and positioning method based on the one-dimensional flexible sensor array system according to claim 2 is characterized in that: The characteristic parameters of the leakage signal 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, form 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 modal decomposition.

4. The water supply pipeline leakage detection and positioning method based on a one-dimensional flexible sensor array system according to claim 1 is characterized in that: The pipeline leak point is located using the beamforming method based on maximum power output, specifically: 1) Calculate the signal characteristics x of different position sensors 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 Frequency domain signal characteristics obtained by fast Fourier transform, where 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 on 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 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 spectrum matrix C(f) to obtain the beamformer output matrix P CBF (w), which is expressed as follows: P CBF (w)=h l (r m ,f) H C(f)h l (r m ,f) Beamformer output matrix P CBF Each element in (w) is the power of the sensor at different positions, and the sensor position with the largest power is the location of the leak point.

5. The water supply pipeline leakage detection and positioning method based on a one-dimensional flexible sensor array system according to claim 1 is characterized in that: The sensor includes a sensitive layer, aluminum film layers located on both sides of the sensitive layer, electrodes located on both sides of the aluminum film layer, and an encapsulation layer for sensor encapsulation; the sensitive layer is polyvinylidene fluoride, used to sense vibrations on the pipe surface and convert them into electrical signals; the electrodes are connected to a signal amplification module via wires; the aluminum film layer is used to conduct electrical signals and protect the sensitive layer; and the encapsulation layer is a polyimide film.

6. The water supply pipeline leakage detection and positioning method based on a one-dimensional flexible sensor array system according to claim 5 is characterized in that: The thickness of the sensitive layer is 50 μm, the thickness of the aluminum thin film layer is 10 μm, the thickness of the electrode is 60 μm, and the thickness of the packaging layer is 50 μm; the sensitive layer and the aluminum thin film layer have the same size.

7. The water supply pipeline leakage detection and positioning method based on a one-dimensional flexible sensor array system according to claim 1 is 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 based on a one-dimensional flexible sensor array system according to claim 1 is 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 based on a one-dimensional flexible sensor array system according to claim 1, characterized in that: The system includes: 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 sequentially select the first vibration signal of each sensor, 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 beamforming method based on maximum power output.

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