Partial discharge detection system and method based on acoustic imaging

Abstract

The invention relates to the technical field of partial discharge detection, in particular to a partial discharge detection system and method based on acoustic imaging. The partial discharge detection system comprises a laser excitation module, a distributed acoustic emission sensor array and a core control module. The laser excitation module emits a laser signal to the sensor array; the sensor arrays are installed on the single face of a tested device at equal intervals and collect partial discharge acoustic emission signals after receiving laser signals. The core control module constructs a time difference positioning constraint of the position of the partial discharge acoustic emission source, calculates a spatial response power function value corresponding to each spatial grid point coordinate in the tested equipment, and obtains a coordinate corresponding to a spatial response power function peak value as a candidate position coordinate; and verifying whether the coordinates of the candidate position conform to the time difference positioning constraint, and if so, taking the candidate position as the position of the partial discharge acoustic emission source. According to the invention, accurate detection of partial discharge is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of partial discharge detection, and in particular to a partial discharge detection system and method based on acoustic imaging. Background Art

[0002] Partial discharge (PD) is a discharge phenomenon caused by insulation breakdown due to concentrated electric fields within or on a localized area of ​​an insulator. This phenomenon can directly indicate whether insulation faults exist in substation electrical equipment and is an important assessment method for determining insulation condition. Localizing PD has always been a hot topic, especially for distribution substations, which are widely dispersed and difficult to monitor on-site. Because of the widespread distribution of equipment, the difficulty of on-site monitoring, and the complex and highly integrated structure, locating PD sources poses greater challenges than for other types of equipment.

[0003] Currently, most methods for detecting partial discharges include optical detection, ultra-high frequency (UHF) positioning, and ultrasonic positioning. Optical detection relies on capturing the optical signals generated by partial discharge for positioning. However, the internal structure of distribution substation equipment is complex, and optical signals are easily blocked by equipment components. Insufficient penetration limits the detection range. Furthermore, severe stray light interference in the environment further reduces the discernibility of optical signals, making accurate positioning difficult. Ultra-high frequency (UHF) positioning utilizes ultra-high frequency (UHF) electromagnetic wave signals generated by partial discharge. However, in the complex electromagnetic environment of a substation, high-frequency signals attenuate rapidly and are prone to reflection, scattering, and diffraction, making their propagation paths difficult to predict. Furthermore, electromagnetic interference generated by the numerous electrical devices within the station, mixed with the partial discharge signals, greatly increases the difficulty of signal identification and processing, making it impossible to guarantee positioning accuracy.

[0004] While ultrasonic positioning can overcome the shortcomings of optical detection and ultra-high frequency positioning methods in terms of signal propagation and interference resistance, it also has significant drawbacks. This method relies on the propagation characteristics of ultrasound. When a local discharge occurs, it stimulates ultrasonic waves to propagate in all directions. Multiple sensors mounted on the surface of the device sequentially receive the ultrasonic signal. Because the propagation speed of sound waves in a medium is relatively constant, there is a time difference between the time different sensors receive the signal. A hyperbolic positioning equation is constructed for each sensor, and the location of the local discharge acoustic emission source is determined by solving the equations. Solving this equation system typically involves iterative methods, such as least squares and maximum likelihood estimation, which require repeated iterations until convergence conditions are met. This complex calculation places extremely high demands on hardware performance and algorithms. Furthermore, ultrasonic positioning imposes stringent requirements on sensor layout during installation. To ensure the accuracy of time difference measurements and the effectiveness of the positioning algorithm, the sensors must be arranged in a specific geometric configuration. For example, the spacing between sensors must be precisely controlled to within a certain ratio of the acoustic wavelength to avoid phase ambiguity and positioning errors caused by improper spacing. In actual distribution substations, equipment is complex and space is limited. Achieving this precise, regular array layout requires time-consuming on-site surveys. Furthermore, due to the uneven dielectric and complex structure of substation equipment, ultrasonic waves undergo refraction, reflection, and scattering during propagation, resulting in a significant amount of interference in the received signal. This makes ultrasonic positioning extremely difficult to implement in practice and hinders its widespread and effective adoption. Summary of the Invention

[0005] To this end, the technical problem to be solved by the present invention is to overcome the defects of the ultrasonic positioning method, such as the complex inversion process and extremely high requirements for hardware equipment and algorithms, which lead to low positioning efficiency and high implementation costs, and difficulty in adapting to the complex structure of distribution substations and the need for rapid response to positioning needs.

[0006] To solve the above technical problems, the present invention provides a partial discharge detection system based on acoustic imaging, comprising: A laser excitation module, used for transmitting laser signals to a distributed acoustic emission sensor array through an optical fiber; The distributed acoustic emission sensor array is installed on any side of the device under test and connected to the laser excitation module via optical fiber. After receiving the laser signal, it collects the acoustic emission signal generated by the partial discharge acoustic emission source and records the timestamp of the acoustic emission signal to each distributed acoustic emission sensor. The core control module is in communication with the distributed acoustic emission sensor array and the laser excitation module, and is used to drive the laser excitation module to emit laser signals, and receive the acoustic emission signals generated by the partial discharge acoustic emission source collected by the distributed acoustic emission sensor array, and the timestamp of the acoustic emission signals to each distributed acoustic emission sensor; Based on the time stamp of the acoustic emission signal to each distributed acoustic emission sensor and the hyperbola positioning equation of each distributed acoustic emission sensor, the time difference positioning constraint of the partial discharge acoustic emission source position is constructed; Calculate the spatial response power function value corresponding to the coordinates of each spatial grid point in the device under test, and obtain the coordinates corresponding to the peak of the spatial response power function as the candidate position coordinates; Verify whether the candidate position coordinates meet the time difference positioning constraints. If so, the candidate position is used as the location of the partial discharge acoustic emission source.

[0007] Preferably, the process of obtaining the hyperbolic positioning equation of each distributed acoustic emission sensor includes: Selecting any distributed acoustic emission sensor in the distributed acoustic emission sensor array as a reference distributed acoustic emission sensor; Based on the difference between the timestamp of the acoustic emission signal to the current distributed acoustic emission sensor and the timestamp to the reference distributed acoustic emission sensor, the propagation velocity of the acoustic emission signal emitted by the partial discharge sound source in the corresponding medium, the position of the current distributed acoustic emission sensor, the position of the reference distributed acoustic emission sensor, and the position of the partial discharge acoustic emission source, the hyperbola positioning equation of the current distributed acoustic emission sensor is constructed.

[0008] Preferably, the hyperbolic positioning equation of each distributed acoustic emission sensor is: , in, is the x-axis coordinate of the PD AE source, is the y-axis coordinate of the partial discharge acoustic emission source, is the z-axis coordinate of the PD AE source, For the The x-axis coordinate of a distributed acoustic emission sensor, For the The y-axis coordinate of a distributed acoustic emission sensor, For the The z-axis coordinate of a distributed acoustic emission sensor, For acoustic emission signal to The distance difference between the distributed acoustic emission sensor and the reference distributed acoustic emission sensor, , , is the propagation speed of the acoustic emission signal emitted by the partial discharge sound source in the corresponding medium, For acoustic emission signal to The difference between the timestamp of the distributed acoustic emission sensor and the timestamp of the reference distributed acoustic emission sensor, For acoustic emission signal to timestamps of distributed acoustic emission sensors, is the timestamp of the acoustic emission signal to the reference distributed acoustic emission sensor, is the x-axis coordinate of the reference distributed acoustic emission sensor, is the y-axis coordinate of the reference distributed acoustic emission sensor, is the z-axis coordinate of the reference distributed acoustic emission sensor, is the index of distributed acoustic emission sensor, , is the total number of distributed acoustic emission sensors in the distributed acoustic emission sensor array.

[0009] Preferably, the time difference positioning constraint of the partial discharge acoustic emission source position is: , in, express The transposed matrix of , is the x-axis coordinate of the PD AE source, is the y-axis coordinate of the partial discharge acoustic emission source, is the z-axis coordinate of the PD AE source, , is the distance from the PD AE source to the reference distributed AE sensor, is the x-axis coordinate of the reference distributed acoustic emission sensor, is the y-axis coordinate of the reference distributed acoustic emission sensor, is the z-axis coordinate of the reference distributed acoustic emission sensor, is the transpose, is the coefficient matrix, Middle Behavior , is a vector, Middle The elements are , For acoustic emission signal to The distance difference between the distributed acoustic emission sensor and the reference distributed acoustic emission sensor, is the propagation speed of the acoustic emission signal emitted by the partial discharge sound source in the corresponding medium, For acoustic emission signal to The difference between the timestamp of the distributed acoustic emission sensor and the timestamp of the reference distributed acoustic emission sensor, For acoustic emission signal to timestamps of distributed acoustic emission sensors, is the timestamp of the acoustic emission signal to the reference distributed acoustic emission sensor, , is the total number of distributed acoustic emission sensors in the distributed acoustic emission sensor array.

[0010] Preferably, the calculating of the spatial response power function value corresponding to the coordinates of each spatial grid point in the device under test includes: Discretize the internal space of the device under test into multiple grid points and obtain the coordinates of each space grid point; Performing frequency domain transformation on the received acoustic emission signal of the partial discharge acoustic emission source to obtain a frequency domain signal corresponding to each distributed acoustic emission sensor; Based on the frequency domain signal corresponding to each distributed acoustic emission sensor, the position of the distributed acoustic emission sensor, and the position of the partial discharge acoustic emission source to be measured, a spatial response power function is constructed; The coordinates of each spatial grid point in the device under test are sequentially used as the position to be measured of the partial discharge acoustic emission source, and the spatial response power function value corresponding to the coordinates of each spatial grid point in the device under test is calculated.

[0011] Preferably, the spatial response power function is constructed based on the frequency domain signal corresponding to each distributed acoustic emission sensor, the position of the distributed acoustic emission sensor, and the position to be measured of the partial discharge acoustic emission source: , in, is the spatial response power function, is the total number of distributed acoustic emission sensors in the distributed acoustic emission sensor array, For the The frequency domain signal corresponding to the distributed acoustic emission sensor is For the The complex conjugate of the frequency domain signal corresponding to each distributed acoustic emission sensor, is the modulus of the complex number, is the imaginary unit, is a natural constant, is the signal frequency, The location of the partial discharge acoustic emission source to be measured To A distributed acoustic emission sensor and The time difference of the distributed acoustic emission sensors, , is the x-axis coordinate of the position to be measured of the partial discharge acoustic emission source, is the y-axis coordinate of the position to be measured of the partial discharge acoustic emission source, is the z-axis coordinate of the position to be measured of the partial discharge acoustic emission source, For the The x-axis coordinate of a distributed acoustic emission sensor, For the The y-axis coordinate of a distributed acoustic emission sensor, For the The z-axis coordinate of a distributed acoustic emission sensor, is the propagation speed of the acoustic emission signal emitted by the partial discharge sound source in the corresponding medium, For the The x-axis coordinate of a distributed acoustic emission sensor, For the The y-axis coordinate of a distributed acoustic emission sensor, For the The z-axis coordinate of a distributed acoustic emission sensor, Indicates the A distributed acoustic emission sensor, , Indicates the A distributed acoustic emission sensor, .

[0012] Preferably, the distributed acoustic emission sensor array is any one of a rectangular array, a circular array, and a spiral planar array.

[0013] Preferably, the distributed acoustic emission sensor is any one of a distributed grating emitter sensor and a distributed optical fiber acoustic emission sensor.

[0014] Preferably, the distributed acoustic emission sensor array is mounted on any side of the device under test by gluing.

[0015] The present invention further provides a partial discharge detection method based on acoustic imaging, which is applied to the above-mentioned partial discharge detection system based on acoustic imaging, comprising: Using a laser excitation module, a laser signal is emitted to a distributed acoustic emission sensor array; Using a distributed acoustic emission sensor array installed on any side of the device under test, after receiving the laser signal, it collects the acoustic emission signal generated by the partial discharge acoustic emission source and records the time stamp of the acoustic emission signal to each distributed acoustic emission sensor; The core control module constructs the time difference positioning constraint of the PD AE source position based on the timestamp of the AE signal to each distributed AE sensor and the hyperbolic positioning equation of each distributed AE sensor; Calculate the spatial response power function value corresponding to the coordinates of each spatial grid point in the device under test, and obtain the coordinates corresponding to the peak of the spatial response power function as the candidate position coordinates; Verify whether the candidate position coordinates meet the time difference positioning constraints. If so, the candidate position is used as the location of the partial discharge acoustic emission source.

[0016] The above technical solution of the present invention has the following beneficial effects compared with the prior art: The present invention discloses a local discharge detection system and method based on acoustic imaging. The distributed acoustic emission sensor array of the present invention can be installed on any side of the device under test, without the need for strict geometric configuration and precise spacing control, and can adapt to different complex environments. A laser excitation module transmits a laser signal to the distributed acoustic emission sensor array to achieve synchronous triggering of each sensor, ensure the accuracy of timestamp recording, and avoid the complex inversion problem caused by clock synchronization errors in traditional ultrasonic positioning. Considering that the spatial response power function will be subject to mirror artifact interference when a distributed acoustic emission sensor array is deployed on a single surface, power peaks of equal intensity are generated at symmetrical positions of the sound source, causing the positioning result to deviate from the true position. Therefore, the present invention introduces a time difference positioning constraint for the location of the local discharge acoustic emission source. Through the sound speed prior and the sensor geometric relationship, the nonlinear hyperbolic positioning problem is converted into a linear constraint. The location of the local discharge acoustic emission source is determined by calculating the spatial response power function value corresponding to the coordinates of each spatial grid point in the device under test and judging whether the peak position meets the time difference positioning constraint. After initially locating the candidate location using the spatial response power function, constraints are substituted to verify whether they comply with the physical laws of sound wave propagation, thereby eliminating mirror artifacts. Without the need for a complex iterative inversion process, accurate localization of the local discharge source can be achieved, quickly responding to the positioning needs of the distribution substation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the installation position of the distributed acoustic emission sensor array.

[0018] Figure 2 It is a schematic diagram of the distributed acoustic emission sensor array when it is a rectangular array.

[0019] Figure 3 It is a flow chart of a partial discharge detection method based on acoustic imaging according to the present invention.

[0020] Explanation of the accompanying figures in the specification: 1. Partial discharge area; 2. Distributed acoustic emission sensor array; 3. Partial discharge detection area; 4. Distributed acoustic emission sensor. DETAILED DESCRIPTION

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0022] This embodiment 1 provides a partial discharge detection system based on acoustic imaging, including: A laser excitation module, used for transmitting laser signals to the distributed acoustic emission sensor array 2 through an optical fiber; like Figure 1 As shown, Figure 1 This is a schematic diagram of the installation position of the distributed acoustic emission sensor array.

[0023] The distributed acoustic emission sensor array 2 is installed on any side of the device under test and connected to the laser excitation module via optical fiber. After receiving the laser signal, it collects the acoustic emission signal generated by the partial discharge acoustic emission source and records the timestamp of the acoustic emission signal to each distributed acoustic emission sensor 4; In this embodiment, the laser excitation module guides the laser signal to the distributed acoustic emission sensor 4 through an optical fiber, thereby preventing the partial discharge detection system from being affected by the complex environment inside the device under test and simplifying the installation difficulty of the partial discharge detection system.

[0024] In this embodiment, specifically, the distributed acoustic emission sensor array 2 is any one of a rectangular array, a circular array, and a spiral planar array.

[0025] like Figure 2 As shown, Figure 2 It is a schematic diagram of the distributed acoustic emission sensor array when it is a rectangular array.

[0026] In this embodiment, specifically, when the distributed acoustic emission sensor array 2 is a rectangular array, the spacing between two adjacent sensors in the same row is equal, and the spacing between two adjacent sensors in the same column is equal; When the distributed acoustic emission sensor array 2 is a circular array, the arc lengths between two adjacent sensors within the same radius are equal; When the distributed acoustic emission sensor array 2 is a spiral planar array, the radial spacing of adjacent sensors along the spiral radial direction is kept consistent according to the spiral law, and the tangential direction is based on the spiral curvature to ensure that the spatial spacing of adjacent sensors in the tangential direction is relatively balanced; In this embodiment, specifically, the distributed acoustic emission sensor 4 is any one of a distributed grating emitter sensor and a distributed optical fiber acoustic emission sensor.

[0027] In this embodiment, specifically, the distributed acoustic emission sensor array 2 is mounted on any side of the device under test by gluing.

[0028] The core control module is in communication with the distributed acoustic emission sensor array 2 and the laser excitation module, and includes a computer for driving the laser excitation module to emit laser signals, and receiving acoustic emission signals generated by the partial discharge acoustic emission source collected by the distributed acoustic emission sensor array 2, and the timestamp of the acoustic emission signals to each distributed acoustic emission sensor 4; Based on the timestamp of the acoustic emission signal to each distributed acoustic emission sensor 4 and the hyperbola positioning equation of each distributed acoustic emission sensor 4, a time difference positioning constraint of the partial discharge acoustic emission source position is constructed; In this embodiment, specifically, the process of obtaining the hyperbolic positioning equation of each distributed acoustic emission sensor 4 includes: Selecting any distributed acoustic emission sensor 4 in the distributed acoustic emission sensor array 2 as a reference distributed acoustic emission sensor; Based on the difference between the timestamp of the acoustic emission signal to the current distributed acoustic emission sensor 4 and the timestamp to the reference distributed acoustic emission sensor, the propagation speed of the acoustic emission signal emitted by the partial discharge sound source in the corresponding medium, the position of the current distributed acoustic emission sensor 4, the position of the reference distributed acoustic emission sensor, and the position of the partial discharge acoustic emission source, a hyperbola positioning equation of the current distributed acoustic emission sensor 4 is constructed.

[0029] The hyperbolic positioning equation of each distributed acoustic emission sensor 4 is: , in, is the x-axis coordinate of the PD AE source, is the y-axis coordinate of the partial discharge acoustic emission source, is the z-axis coordinate of the PD AE source, For the The x-axis coordinate of the distributed acoustic emission sensor 4, For the The y-axis coordinate of the distributed acoustic emission sensor 4, For the The z-axis coordinate of the distributed acoustic emission sensor 4, For acoustic emission signal to The distance difference between the distributed acoustic emission sensor 4 and the reference distributed acoustic emission sensor, , , is the propagation speed of the acoustic emission signal emitted by the partial discharge sound source in the corresponding medium, For acoustic emission signal to The difference between the timestamp of the distributed acoustic emission sensor 4 and the timestamp of the reference distributed acoustic emission sensor, For acoustic emission signal to timestamps of 4 distributed acoustic emission sensors, is the timestamp of the acoustic emission signal to the reference distributed acoustic emission sensor, is the x-axis coordinate of the reference distributed acoustic emission sensor, is the y-axis coordinate of the reference distributed acoustic emission sensor, is the z-axis coordinate of the reference distributed acoustic emission sensor, Index for distributed acoustic emission sensor 4, , is the total number of distributed acoustic emission sensors 4 in the distributed acoustic emission sensor array 2.

[0030] By squaring and expanding the hyperbolic positioning equation of each distributed acoustic emission sensor 4, we can obtain ,in, , is the distance from the partial discharge acoustic emission source to the reference distributed acoustic emission sensor.

[0031] In this embodiment, preferably, the time difference positioning constraint of the partial discharge acoustic emission source position is: , in, express The transposed matrix of , is the x-axis coordinate of the PD AE source, is the y-axis coordinate of the partial discharge acoustic emission source, is the z-axis coordinate of the PD AE source, , is the distance from the PD AE source to the reference distributed AE sensor, is the x-axis coordinate of the reference distributed acoustic emission sensor, is the y-axis coordinate of the reference distributed acoustic emission sensor, is the z-axis coordinate of the reference distributed acoustic emission sensor, is the transpose, is the coefficient matrix, Middle Behavior , is a vector, Middle The elements are , For acoustic emission signal to The distance difference between the distributed acoustic emission sensor 4 and the reference distributed acoustic emission sensor, is the propagation speed of the acoustic emission signal emitted by the partial discharge sound source in the corresponding medium, For acoustic emission signal to The difference between the timestamp of the distributed acoustic emission sensor 4 and the timestamp of the reference distributed acoustic emission sensor, For acoustic emission signal to timestamps of 4 distributed acoustic emission sensors, is the timestamp of the acoustic emission signal to the reference distributed acoustic emission sensor, Index of distributed acoustic emission sensor 4.

[0032] Calculate the spatial response power function value corresponding to the coordinates of each spatial grid point in the device under test, and obtain the coordinates corresponding to the peak of the spatial response power function as the candidate position coordinates; In this embodiment, specifically, calculating the spatial response power function value corresponding to the coordinates of each spatial grid point in the device under test includes: Discretize the internal space of the device under test into multiple grid points and obtain the coordinates of each space grid point; Performing frequency domain transformation on the received acoustic emission signal of the partial discharge acoustic emission source to obtain a frequency domain signal corresponding to each distributed acoustic emission sensor 4; Based on the frequency domain signal corresponding to each distributed acoustic emission sensor 4 and the position of the distributed acoustic emission sensor 4 and the position to be measured of the partial discharge acoustic emission source, a spatial response power function is constructed; The coordinates of each spatial grid point in the device under test are taken as the position to be measured of the partial discharge acoustic emission source in turn, and the spatial response power function value corresponding to the coordinates of each spatial grid point in the device under test is calculated.

[0033] In this embodiment, specifically, the spatial response power function is constructed based on the frequency domain signal corresponding to each distributed acoustic emission sensor 4, the position of the distributed acoustic emission sensor 4, and the position to be measured of the partial discharge acoustic emission source: , in, is the spatial response power function, is the total number of distributed acoustic emission sensors 4 in the distributed acoustic emission sensor array 2, For the The frequency domain signal corresponding to 4 distributed acoustic emission sensors, For the The complex conjugate of the frequency domain signal corresponding to the distributed acoustic emission sensor 4, is the modulus of the complex number, is the imaginary unit, is a natural constant, is the signal frequency, The location of the partial discharge acoustic emission source to be measured To A distributed acoustic emission sensor 4 and the The time difference of 4 distributed acoustic emission sensors, , is the x-axis coordinate of the position to be measured of the partial discharge acoustic emission source, is the y-axis coordinate of the position to be measured of the partial discharge acoustic emission source, is the z-axis coordinate of the position to be measured of the partial discharge acoustic emission source, For the The x-axis coordinate of the distributed acoustic emission sensor 4, For the The y-axis coordinate of the distributed acoustic emission sensor 4, For the The z-axis coordinate of the distributed acoustic emission sensor 4, is the propagation speed of the acoustic emission signal emitted by the partial discharge sound source in the corresponding medium, For the The x-axis coordinate of the distributed acoustic emission sensor 4, For the The y-axis coordinate of the distributed acoustic emission sensor 4, For the The z-axis coordinate of the distributed acoustic emission sensor 4, Indicates the 4 distributed acoustic emission sensors, , Indicates the 4 distributed acoustic emission sensors, .

[0034] Verify whether the candidate position coordinates meet the time difference positioning constraints. If so, the candidate position is used as the location of the partial discharge acoustic emission source.

[0035] Traditional ultrasound positioning method solves linear equations When directly calculating the location of the PD AE source, it is necessary to calculate , strictly requires that each sensor is non-collinear / non-coplanar to avoid matrix singularity, relying on accurate time difference and ideal matrix invertibility. When the distributed acoustic emission sensor array 4 is on the same horizontal plane, it may cause the coefficient matrix The column vectors of are linearly related, so that Close to singularity, which is manifested by the condition number of the matrix being extremely large or the eigenvalues ​​being close to zero. This situation will cause the matrix inversion to be extremely sensitive to measurement noise, which will make the solution of the linear equation system unstable, resulting in Either there is no solution, or there are infinitely many solutions.

[0036] Therefore, the present invention introduces a Steered Response Power-Phase Transform (SRP-PHAT). Even if the distributed acoustic emission sensors 4 are randomly distributed, the SRP-PHAT can still form a peak at the location of the PD acoustic emission source, while noise and incoherent signals cancel each other out during the accumulation process. However, if the SRP-PHAT is directly applied to PD detection, due to the symmetry of sound wave propagation, mirror artifacts will be generated at locations symmetrical to the PD acoustic emission source with respect to the sensor array plane. The false peaks formed by these artifacts have energy intensities similar to the true peaks and can easily be misidentified as the location of the PD acoustic emission source. In other words, the candidate location coordinates may be the location of the PD acoustic emission source or a location symmetrical to the PD acoustic emission source with respect to the sensor array plane, resulting in significant errors in the localization of the PD acoustic emission source, seriously affecting the reliability and accuracy of the positioning results.

[0037] To address these shortcomings, the present invention introduces a time-of-day localization constraint for the location of PD acoustic emission sources. By leveraging sound velocity priors and sensor geometry, the nonlinear hyperbolic localization problem is converted into a linear constraint. The PD acoustic emission source location is determined by calculating the spatial response power function corresponding to the coordinates of each spatial grid point within the device under test and determining whether the peak position meets the time-of-day localization constraint. After initially locating candidate locations using the spatial response power function, the constraint conditions are substituted to verify compliance with the physical laws of sound wave propagation, thereby eliminating image artifacts. Accurate PD source location is achieved by simply substituting the corresponding position of the obtained spatial response power peak and verifying whether the time-of-day localization constraint is met. This eliminates the need for complex iterative inversion processes.

[0038] The present invention proposes a partial discharge detection system based on acoustic imaging that can not only detect the partial discharge source inside an oil-immersed transformer, but also detect other partial discharge sources and locate the sound source, thus having broad application prospects and potential application value.

[0039] When detecting partial discharge sources within an oil-immersed transformer, the distributed acoustic emission sensor array of four is simply affixed to any side of the transformer's internal casing. Theoretically, this invention only requires a single-sided 4x4 distributed acoustic emission sensor array to achieve three-dimensional positioning accuracy. The geometric distribution of the distributed acoustic emission sensors is not strictly required, and the single-sided array can reconstruct the three-dimensional sound field by scanning every grid point across the entire space.

[0040] The present invention arranges 16 distributed acoustic emission sensors 4 in a 4x4 array on the same plane as the device under test, with each pair of sensors forming a "unit surface." When a partial discharge generates an acoustic emission signal, the time difference between the signal reaching the two sensors on the unit surface, combined with the propagation velocity, defines a hyperboloid centered on the two sensors. The source of the partial discharge acoustic emission is therefore located on this hyperboloid. Pairing the 16 sensors creates 120 sets of hyperboloids, which are intersecting and constrained in three-dimensional space. Their unique intersection is the 3D location of the partial discharge acoustic emission source. Because the sensor array is located on a fixed height plane, the present invention achieves efficient 3D positioning using 2D coordinates through coordinated positioning of the hyperboloids constructed from multiple "unit surfaces."

[0041] refer to Figure 3 The second embodiment provides a partial discharge detection method based on acoustic imaging, which is applied to the above-mentioned partial discharge detection system based on acoustic imaging, including: Step S1: using a laser excitation module to emit a laser signal to the distributed acoustic emission sensor array 2; Step S2: After receiving the laser signal, the distributed acoustic emission sensor array 2 installed on any side of the device under test collects the acoustic emission signal generated by the partial discharge acoustic emission source and records the timestamp of the acoustic emission signal to each distributed acoustic emission sensor 4; Step S3: The core control module constructs a time difference positioning constraint for the position of the partial discharge acoustic emission source based on the timestamp of the acoustic emission signal to each distributed acoustic emission sensor 4 and the hyperbola positioning equation of each distributed acoustic emission sensor 4; Step S4: Calculate the spatial response power function value corresponding to the coordinates of each spatial grid point in the device under test, and obtain the coordinates corresponding to the peak value of the spatial response power function as the candidate position coordinates; Step S5: Verify whether the candidate position coordinates meet the time difference positioning constraint. If so, use the candidate position as the location of the partial discharge acoustic emission source.

[0042] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0043] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0044] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0045] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0046] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A partial discharge detection system based on acoustic imaging, characterized in that: include: A laser excitation module, used for transmitting laser signals to a distributed acoustic emission sensor array through an optical fiber; The distributed acoustic emission sensor array is installed on any side of the device under test and connected to the laser excitation module via optical fiber. After receiving the laser signal, it collects the acoustic emission signal generated by the partial discharge acoustic emission source and records the timestamp of the acoustic emission signal to each distributed acoustic emission sensor. The core control module is in communication with the distributed acoustic emission sensor array and the laser excitation module, and is used to drive the laser excitation module to emit laser signals, and receive the acoustic emission signals generated by the partial discharge acoustic emission source collected by the distributed acoustic emission sensor array, and the timestamp of the acoustic emission signals to each distributed acoustic emission sensor; Based on the time stamp of the acoustic emission signal to each distributed acoustic emission sensor and the hyperbola positioning equation of each distributed acoustic emission sensor, the time difference positioning constraint of the partial discharge acoustic emission source position is constructed; Calculate the spatial response power function value corresponding to the coordinates of each spatial grid point in the device under test, and obtain the coordinates corresponding to the peak of the spatial response power function as the candidate position coordinates; Verify whether the candidate position coordinates meet the time difference positioning constraints. If so, the candidate position is used as the location of the partial discharge acoustic emission source.

2. The partial discharge detection system based on acoustic imaging according to claim 1, characterized in that: The process of obtaining the hyperbolic positioning equation of each distributed acoustic emission sensor includes: Selecting any distributed acoustic emission sensor in the distributed acoustic emission sensor array as a reference distributed acoustic emission sensor; Based on the difference between the timestamp of the acoustic emission signal to the current distributed acoustic emission sensor and the timestamp to the reference distributed acoustic emission sensor, the propagation velocity of the acoustic emission signal emitted by the partial discharge sound source in the corresponding medium, the position of the current distributed acoustic emission sensor, the position of the reference distributed acoustic emission sensor, and the position of the partial discharge acoustic emission source, the hyperbola positioning equation of the current distributed acoustic emission sensor is constructed.

3. The partial discharge detection system based on acoustic imaging according to claim 2, characterized in that: The hyperbolic positioning equation of each distributed acoustic emission sensor is: ， in, is the x-axis coordinate of the PD AE source, is the y-axis coordinate of the partial discharge acoustic emission source, is the z-axis coordinate of the PD AE source, For the The x-axis coordinate of a distributed acoustic emission sensor, For the The y-axis coordinate of a distributed acoustic emission sensor, For the The z-axis coordinate of a distributed acoustic emission sensor, For acoustic emission signal to The distance difference between the distributed acoustic emission sensor and the reference distributed acoustic emission sensor, , , is the propagation speed of the acoustic emission signal emitted by the partial discharge sound source in the corresponding medium, For acoustic emission signal to The difference between the timestamp of the distributed acoustic emission sensor and the timestamp of the reference distributed acoustic emission sensor, For acoustic emission signal to timestamps of distributed acoustic emission sensors, is the timestamp of the acoustic emission signal to the reference distributed acoustic emission sensor, is the x-axis coordinate of the reference distributed acoustic emission sensor, is the y-axis coordinate of the reference distributed acoustic emission sensor, is the z-axis coordinate of the reference distributed acoustic emission sensor, is the index of distributed acoustic emission sensor, , is the total number of distributed acoustic emission sensors in the distributed acoustic emission sensor array.

4. The partial discharge detection system based on acoustic imaging according to claim 2, characterized in that: The time difference positioning constraint of the partial discharge acoustic emission source is: ， in, express The transposed matrix of , is the x-axis coordinate of the PD AE source, is the y-axis coordinate of the partial discharge acoustic emission source, is the z-axis coordinate of the PD AE source, , is the distance from the PD AE source to the reference distributed AE sensor, is the x-axis coordinate of the reference distributed acoustic emission sensor, is the y-axis coordinate of the reference distributed acoustic emission sensor, is the z-axis coordinate of the reference distributed acoustic emission sensor, is the transpose, is the coefficient matrix, Middle Behavior , is a vector, Middle The elements are , For acoustic emission signal to The distance difference between the distributed acoustic emission sensor and the reference distributed acoustic emission sensor, is the propagation speed of the acoustic emission signal emitted by the partial discharge sound source in the corresponding medium, For acoustic emission signal to The difference between the timestamp of the distributed acoustic emission sensor and the timestamp of the reference distributed acoustic emission sensor, For acoustic emission signal to timestamps of distributed acoustic emission sensors, is the timestamp of the acoustic emission signal to the reference distributed acoustic emission sensor, , is the total number of distributed acoustic emission sensors in the distributed acoustic emission sensor array.

5. The partial discharge detection system based on acoustic imaging according to claim 1, characterized in that: Calculating the spatial response power function value corresponding to the coordinates of each spatial grid point in the device under test includes: Discretize the internal space of the device under test into multiple grid points and obtain the coordinates of each space grid point; Performing frequency domain transformation on the received acoustic emission signal of the partial discharge acoustic emission source to obtain a frequency domain signal corresponding to each distributed acoustic emission sensor; Based on the frequency domain signal corresponding to each distributed acoustic emission sensor, the position of the distributed acoustic emission sensor, and the position of the partial discharge acoustic emission source to be measured, a spatial response power function is constructed; The coordinates of each spatial grid point in the device under test are sequentially used as the position to be measured of the partial discharge acoustic emission source, and the spatial response power function value corresponding to the coordinates of each spatial grid point in the device under test is calculated.

6. The partial discharge detection system based on acoustic imaging according to claim 5, characterized in that: The spatial response power function is constructed based on the frequency domain signal corresponding to each distributed acoustic emission sensor, the position of the distributed acoustic emission sensor, and the position to be measured of the partial discharge acoustic emission source: ， in, is the spatial response power function, is the total number of distributed acoustic emission sensors in the distributed acoustic emission sensor array, For the The frequency domain signal corresponding to the distributed acoustic emission sensor is For the The complex conjugate of the frequency domain signal corresponding to each distributed acoustic emission sensor, is the modulus of the complex number, is the imaginary unit, is a natural constant, is the signal frequency, The location of the partial discharge acoustic emission source to be measured To A distributed acoustic emission sensor and The time difference of the distributed acoustic emission sensors, , is the x-axis coordinate of the position to be measured of the partial discharge acoustic emission source, is the y-axis coordinate of the position to be measured of the partial discharge acoustic emission source, is the z-axis coordinate of the position to be measured of the partial discharge acoustic emission source, For the The x-axis coordinate of a distributed acoustic emission sensor, For the The y-axis coordinate of a distributed acoustic emission sensor, For the The z-axis coordinate of a distributed acoustic emission sensor, is the propagation speed of the acoustic emission signal emitted by the partial discharge sound source in the corresponding medium, For the The x-axis coordinate of a distributed acoustic emission sensor, For the The y-axis coordinate of a distributed acoustic emission sensor, For the The z-axis coordinate of a distributed acoustic emission sensor, Indicates the A distributed acoustic emission sensor, , Indicates the A distributed acoustic emission sensor, .

7. The partial discharge detection system based on acoustic imaging according to claim 1, characterized in that: The distributed acoustic emission sensor array is any one of a rectangular array, a circular array and a spiral planar array.

8. The partial discharge detection system based on acoustic imaging according to claim 1, characterized in that: The distributed acoustic emission sensor is any one of a distributed grating emitter sensor and a distributed optical fiber acoustic emission sensor.

9. The partial discharge detection system based on acoustic imaging according to claim 1, characterized in that: The distributed acoustic emission sensor array is installed on any side of the device under test by adhesive bonding.

10. A partial discharge detection method based on acoustic imaging, characterized in that: A partial discharge detection system based on acoustic imaging as claimed in any one of claims 1 to 9, comprising: Using a laser excitation module, a laser signal is emitted to a distributed acoustic emission sensor array; Using a distributed acoustic emission sensor array installed on any side of the device under test, after receiving the laser signal, it collects the acoustic emission signal generated by the partial discharge acoustic emission source and records the time stamp of the acoustic emission signal to each distributed acoustic emission sensor; The core control module constructs the time difference positioning constraint of the PD AE source position based on the timestamp of the AE signal to each distributed AE sensor and the hyperbolic positioning equation of each distributed AE sensor; Calculate the spatial response power function value corresponding to the coordinates of each spatial grid point in the device under test, and obtain the coordinates corresponding to the peak of the spatial response power function as the candidate position coordinates; Verify whether the candidate position coordinates meet the time difference positioning constraints. If so, the candidate position is used as the location of the partial discharge acoustic emission source.

Images