Transformer internal partial discharge detection acoustic imaging positioning device based on optical fiber microphone

Abstract

The invention discloses an acoustic imaging positioning device for partial discharge detection in a transformer based on an optical fiber microphone. The acoustic imaging positioning device comprises a signal acquisition module, data processing equipment and a spherical optical fiber microphone array arranged in the transformer, the signal acquisition module outputs light source excitation to each microphone channel in the optical fiber microphone array, so that the optical fiber microphone array acquires sound wave signals generated by partial discharge; the optical fiber microphone array converts the acquired sound wave signal into an optical interference signal and outputs the optical interference signal to the signal acquisition module; the signal acquisition module converts the optical interference signals into multi-channel digital signals and outputs the multi-channel digital signals to the data processing equipment; the data processing equipment performs beam forming calculation on the multiple paths of digital signals, reconstructs spatial distribution of the partial discharge source, and generates an acoustic imaging graph of the partial discharge source in combination with three-dimensional space coordinates in the transformer; according to the invention, high-precision and high-stability transformer internal partial discharge detection can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of power equipment detection, and in particular to an acoustic imaging and positioning device for detecting partial discharge inside a transformer based on an optical fiber microphone. Background Art

[0002] Transformers, as key equipment in power systems, are widely used in power transmission and distribution. Their stable operation is crucial to ensuring power supply. However, with long-term operation, transformers may experience partial discharge (PD), which is typically caused by localized defects or contamination in the insulation material. If this phenomenon is not detected promptly, it can lead to further degradation of the equipment's insulation performance, ultimately causing more serious failures such as electrical fires, power outages, or equipment damage. Therefore, real-time monitoring and early diagnosis of PD within transformers are key to preventing failures and improving transformer operation safety.

[0003] Traditional partial discharge detection methods mainly include electrical methods, chemical methods and ultrasonic methods, but these methods often face certain challenges in practical applications. For example, electrical detection relies on the analysis of current or voltage fluctuations, is easily interfered by external electromagnetic noise, and can only provide quantitative data of discharge, making it difficult to achieve accurate spatial positioning. Although chemical and ultrasonic methods can provide certain partial discharge information, their scope of application is relatively limited, and it is difficult to achieve long-term, stable online monitoring in complex power environments. For example, in the relevant technology, the patent application document with publication number CN114440809A proposes to collect the acoustic signal of the transformer through the vibration of a silicon microphone, but the silicon microphone and MEMS sensor used in this solution will be subject to certain limitations in environments with high voltage and strong electromagnetic interference, resulting in unstable signal acquisition. The patent application document with authorization publication number CN209264875U proposes to install vibration sensors and microphones on the outside of the transformer to collect fault signals inside the transformer. Although they are adsorbed on the surface of the transformer by magnets, the external structure of the transformer is usually complex and the surface is irregular, which may affect the stability of the sensor and the signal collection quality, especially in some specific transformer types or designs, the surface may be uneven, or the equipment may be large in size, and special adjustments and adaptations may be required during the installation process; and installing the sensor on the outside of the transformer means relying on the transformer casing to transmit sound and vibration signals, which may cause signal attenuation, especially when the transformer casing is thicker or the material density is higher, the signal transmission efficiency will be reduced, thereby affecting the diagnostic accuracy; furthermore, the external structure of the transformer may cause the tiny fault signals generated internally to be attenuated or distorted during the transmission process, resulting in the inability to accurately capture small-scale fault signals such as partial discharge. Patent application publication number CN114527427A proposes using a small spherical microphone array to localize sound sources. However, when the microphone array is placed inside a transformer, signal acquisition becomes unstable due to the transformer's complex internal structure, certain space limitations, and stronger electromagnetic interference and higher ambient temperature inside than outside. Summary of the Invention

[0004] The technical problem to be solved by the present invention is how to achieve high-precision and high-stability partial discharge detection inside a transformer.

[0005] The present invention solves the above technical problems through the following technical means:

[0006] A fiber-optic microphone-based acoustic imaging and positioning device for partial discharge detection inside a transformer is proposed. The device includes a signal acquisition module, a data processing device, and a fiber-optic microphone array arranged inside the transformer. The fiber-optic microphone array is composed of multiple fiber-optic microphones evenly distributed in a spherical geometric structure.

[0007] The signal acquisition module outputs light source excitation to each microphone channel in the fiber optic microphone array, so that the fiber optic microphone array collects the acoustic wave signal generated by the partial discharge;

[0008] The fiber optic microphone array converts the collected sound wave signal into an optical interference signal and outputs it to the signal acquisition module;

[0009] The signal acquisition module converts the optical interference signal into a multi-channel digital signal and outputs it to the data processing equipment;

[0010] The data processing equipment performs beamforming calculations on multiple digital signals to reconstruct the spatial distribution of the partial discharge source and, combined with the three-dimensional spatial coordinates inside the transformer, generates an acoustic imaging diagram of the partial discharge source.

[0011] Furthermore, the radius of the fiber optic microphone array and the density of the fiber optic microphone distribution are designed according to the internal space size of the transformer.

[0012] Furthermore, the frequency response range of the optical fiber microphone is 20kHz-200kHz.

[0013] Furthermore, the optical fiber microphone is encapsulated in a protective shell, and the protective shell is fixed to the spherical bracket.

[0014] Furthermore, the optical fiber microphone is an optical fiber FP microphone, a microphone based on a miniature optical fiber sensor, or a fiber Bragg grating microphone.

[0015] Furthermore, the signal acquisition module includes a laser, a splitter is arranged on the laser light path output by the laser, a circulator is arranged on the output light path of the splitter, one output port of the circulator outputs laser to the fiber optic microphone array, and the other output port outputs the reflected light of the fiber optic microphone array to a photodetector, and the output of the photodetector is connected to the data processing equipment after passing through a multi-channel acquisition card.

[0016] Furthermore, the data processing device includes:

[0017] The signal processing module is used to perform denoising and filtering on multiple digital signals to obtain processed digital signals;

[0018] The time-frequency analysis module is used to perform time-domain analysis and frequency-domain analysis on the processed digital signal to obtain the effective signal of partial discharge characteristics;

[0019] an amplification module, used to amplify the effective signal of the partial discharge characteristic and adjust the signal gain;

[0020] The acoustic imaging module is used to perform beamforming calculations on effective signals of partial discharge characteristics, reconstruct the spatial distribution of the partial discharge source, and generate an acoustic imaging map of the partial discharge source based on the three-dimensional spatial coordinates inside the transformer.

[0021] Furthermore, the acoustic imaging module specifically includes:

[0022] The compensation unit is used to calculate the propagation delay τ of the reflected light of each fiber optic microphone in the fiber optic microphone array according to the target direction (θ0, φ0) k , and perform time shift compensation on the reflected light of each fiber optic microphone so that the reflected light signal is phase-aligned in the frequency domain;

[0023] A weighted summing unit, configured to perform weighted summing on the reflected light signals of all the optical fiber microphones and output a beam signal;

[0024] A weight optimization unit is used to optimize the weight according to the interference environment, minimize the output power and ensure that the gain in the target direction is 1;

[0025] The imaging unit is used to traverse all directions of the three-dimensional space inside the transformer, repeat the signal preprocessing and beamforming steps, calculate the output power in each direction, and generate an acoustic imaging map of the local discharge source.

[0026] Furthermore, the data processing device further includes:

[0027] The data analysis module is used to diagnose the acoustic imaging images, determine the type and hazard level of partial discharge, and trigger a fault warning signal.

[0028] In addition, the present invention also proposes a method for detecting partial discharge inside a transformer by acoustic imaging and positioning based on a fiber optic microphone. The above-mentioned device for detecting partial discharge inside a transformer by acoustic imaging and positioning based on a fiber optic microphone performs acoustic imaging and positioning, including:

[0029] According to the internal space size of the transformer, the radius of the spherical fiber optic microphone array and the density of the fiber optic microphone distribution are designed;

[0030] Based on the characteristic curve of the fiber optic microphone and the detection requirements of partial discharge inside the transformer, the optimal sensitivity range of each fiber optic microphone in the fiber optic microphone array is determined;

[0031] According to the radius of the fiber optic microphone array, the wavelength of the laser output by the signal acquisition module is adjusted to stimulate the fiber optic microphone array to collect the sound pressure signal generated by the partial discharge and convert the collected sound pressure signal into an optical interference signal before outputting it to the signal acquisition module;

[0032] The optical interference signal is converted into a multi-channel digital signal using a signal acquisition module;

[0033] Data processing equipment is used to perform beamforming calculations on multiple digital signals to reconstruct the spatial distribution of the partial discharge source. Combined with the three-dimensional spatial coordinates inside the transformer, an acoustic imaging diagram of the partial discharge source is generated.

[0034] The advantages of the present invention are:

[0035] The present invention adopts fiber optic microphone array technology, which can effectively overcome the electromagnetic interference problems of traditional electrical and ultrasonic methods and has strong anti-electromagnetic interference capabilities, making the present invention particularly suitable for partial discharge detection in complex power environments, ensuring the accuracy and reliability of signal acquisition; through the design based on a spherical fiber optic microphone array, it can collect acoustic signals inside the transformer in all directions and from multiple angles, and combine with acoustic imaging technology to reconstruct the spatial distribution of the discharge source, thereby achieving more accurate discharge source location of the local discharge source inside the transformer and positioning of multiple sound sources.

[0036] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 1 is a schematic structural diagram of an acoustic imaging and positioning device for detecting partial discharge inside a transformer based on a fiber optic microphone, proposed in one embodiment of the present invention;

[0038] Figure 2 is a schematic diagram of a distributed spherical array of fiber optic microphones in one embodiment of the present invention;

[0039] Figure 3 1 is a schematic diagram of the working process of an acoustic imaging and positioning device for detecting partial discharge inside a transformer based on a fiber optic microphone in one embodiment of the present invention;

[0040] Figure 4 1 is a schematic diagram of acoustic imaging results of partial discharge inside a transformer according to one embodiment of the present invention;

[0041] Figure 5 The figure is a flow chart of an acoustic imaging and positioning method for detecting partial discharge inside a transformer based on a fiber optic microphone, proposed in one embodiment of the present invention. DETAILED DESCRIPTION

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0043] like Figure 1 As shown, one embodiment of the present invention provides an acoustic imaging and positioning device for detecting partial discharge inside a transformer based on a fiber optic microphone. The device includes a signal acquisition module, a data processing device, and a fiber optic microphone array arranged inside the transformer. The fiber optic microphone array is composed of multiple fiber optic microphones evenly distributed in a spherical geometric structure.

[0044] The signal acquisition module outputs light source excitation to each microphone channel in the fiber optic microphone array, so that the fiber optic microphone array collects the acoustic wave signal generated by the partial discharge;

[0045] The fiber optic microphone array converts the collected sound wave signal into an optical interference signal and outputs it to the signal acquisition module;

[0046] The signal acquisition module converts the optical interference signal into a multi-channel digital signal and outputs it to the data processing equipment;

[0047] The data processing equipment performs beamforming calculations on multiple digital signals to reconstruct the spatial distribution of the partial discharge source and, combined with the three-dimensional spatial coordinates inside the transformer, generates an acoustic imaging diagram of the partial discharge source.

[0048] It should be noted that the fiber optic microphone array can work stably for a long time without being subject to electromagnetic interference. It is particularly suitable for the complex and high-temperature electrical environment inside the transformer. It can sensitively detect the acoustic wave signals inside the transformer, has high sensitivity and anti-interference ability, and can ensure the accuracy and reliability of signal acquisition under different operating conditions. Furthermore, through the design based on the spherical fiber optic microphone array, it can collect acoustic signals inside the transformer in an all-round and multi-angle manner, and combine with acoustic imaging technology to reconstruct the spatial distribution of the discharge source. It can accurately locate the position and distribution of the discharge source through the propagation characteristics of the sound wave, and achieve more accurate discharge source location of the local discharge source inside the transformer and positioning of multiple sound sources, thereby providing important support for the detection of local discharge and fault warning inside the transformer.

[0049] It should be noted that the embodiments of the present invention differ from the traditional method of placing microphones outside the transformer to collect internal fault signals, which makes it impossible to accurately capture small-scale fault signals such as partial discharge. Instead, a fiber optic microphone array is placed inside the transformer. However, placing a fiber optic microphone array inside the transformer faces multiple technical difficulties, including space limitations within the transformer, the impact of mechanical vibration on signal acquisition, accurate positioning of fault signals and noise interference, the complexity of equipment maintenance and replacement, and sealing requirements such as waterproof and oil-proof. These challenges require the adoption of appropriate signal processing technology, high-temperature resistance, and anti-interference design to ensure the stability and long-term reliable operation of the fiber optic microphone in harsh environments.

[0050] Specifically:

[0051] (1) Space limitations and layout complexity: Transformers typically have a complex internal structure, including windings, cores, oil tanks, and other components. Finding appropriate space between these components to arrange the spherical microphone array is a challenge, especially when the space inside the equipment is limited. Arranging multiple fiber optic microphones ensures coverage of all possible discharge sources.

[0052] (2) Temperature and durability issues: Although fiber optic microphones have good high temperature resistance, as the temperature continues to rise, it may have a certain impact on the stability of its internal components, such as UV curing glue. Therefore, bonded fiber optic microphones should be used to build fiber optic microphone arrays to avoid equipment failure at high temperatures.

[0053] (3) Electromagnetic interference: Although fiber optic microphones have strong anti-electromagnetic interference capabilities, the strong electromagnetic field inside the transformer may still affect the signal of the microphone array, especially when it is close to electrical components. During design, it is necessary to ensure that the anti-interference performance of the microphone is strong enough to avoid electromagnetic fields interfering with the accurate acquisition of signals. Therefore, non-metallic high-reflective film materials or coating methods are used to improve the sensitivity of fiber optic microphones (such as silicon, etc.), and metal film materials are avoided to reduce the negative impact of electromagnetic interference on microphone performance.

[0054] (4) Mechanical vibration and noise: The vibration and noise generated by the transformer during operation may interfere with the signal acquisition of the microphone array. To ensure accurate partial discharge signal capture, the microphone array needs to be designed to effectively filter out these mechanical noises, such as using bandpass filtering to filter out mechanical vibrations.

[0055] (5) Signal processing and positioning accuracy: Spherical microphone arrays can provide three-dimensional sound source positioning. However, due to the physical aperture size of the array, the low-frequency signals collected inside the transformer will have low resolution. Its signal processing and beamforming algorithms may face resolution issues at low frequencies. To ensure accurate fault location, efficient algorithms need to be adopted and computing power needs to be increased to process high-precision positioning of low-frequency signals. For example, compressed sensing theory or deep learning frameworks are used to improve the sparse expression capabilities of low-frequency signals.

[0056] As a further preferred technical solution, in order to address the issues of space limitation and layout complexity, the radius of the fiber optic microphone array and the density of the fiber optic microphone distribution in this embodiment are designed according to the internal space size of the transformer.

[0057] Specifically, the spherical fiber optic microphone array is designed to meet the needs of 20kHz to 80kHz high-frequency partial discharge monitoring. The method of collaborative optimization of acoustic characteristics and mechanical constraints is adopted: first, based on the highest frequency wavelength constraint λ min =c / f max =1430 / 80k≈17.9mm and spatial sampling theorem, λ min is the wavelength, c is the speed of sound, f max The frequency of the sound signal is determined, and the array radius R is determined to be 0.15m; the sensor distribution uses the adaptive golden spiral algorithm and the genetic algorithm to optimize the energy uniformity function to achieve 0.8° spacing deviation control to ensure λ min / 2=8.95mm sampling density.

[0058] It should be noted that the fiber optic microphone array can adjust the number and density of microphones according to the different working environment requirements inside the transformer. By accurately calculating the geometric position of the microphone arrangement and combining it with acoustic imaging technology, the spatial resolution and positioning accuracy of the partial discharge source can be further improved. By optimizing the design and configuration of the fiber optic microphone array, such as Figure 2 As shown, the sensitivity of partial discharge detection can be effectively improved and the safe operation of the transformer can be ensured.

[0059] In this embodiment, when deploying the fiber optic microphone array within the transformer, the key placement locations must be determined based on the distribution of the partial discharge source, the complex internal structure and spatial constraints of the transformer, and the comprehensiveness of signal acquisition. A spherical array arrangement evenly covers every corner of the transformer, collecting signals from multiple directions, ensuring comprehensiveness and accuracy while avoiding blind spots. By optimizing the spatial distribution of the microphone array, the accuracy of localizing the partial discharge source can be improved, while ensuring the stability of signal acquisition. Furthermore, the density and number of placement points must be tailored to the size and structure of the transformer to achieve efficient signal acquisition and accurate fault diagnosis.

[0060] As a further preferred technical solution, the frequency response range of the fiber optic microphone is 20kHz-200kHz to cover the frequency band of partial discharge ultrasonic signals.

[0061] As a further preferred technical solution, in order to address the temperature and durability issues associated with placing the fiber optic microphone inside the transformer, the fiber optic microphone in this embodiment is encapsulated in a protective housing, which is fixed to a spherical bracket.

[0062] In this embodiment, the optical fiber microphone is encapsulated in a protective housing that is resistant to high temperatures and electromagnetic interference, so as to prevent the high temperature environment inside the transformer from affecting the stability of the optical fiber microphone array.

[0063] As a further preferred technical solution, the optical fiber microphone adopts an optical fiber FP microphone or a microphone based on a miniature optical fiber sensor or a fiber Bragg grating microphone.

[0064] Preferably, the fiber optic microphone array in this embodiment is composed of fiber optic FP microphones. Fiber optic FP microphones have high sensitivity and a wide range of applications, and can accurately capture weak sound wave signals.

[0065] It should be noted that those skilled in the art may use fiber optic microphones with other structures according to actual conditions, and this embodiment does not specifically limit the type of fiber optic microphone.

[0066] As a further preferred technical solution, Figure 3 As shown, the signal acquisition module includes a laser, a splitter is arranged on the laser light path output by the laser, a circulator is arranged on the output light path of the splitter, one output port of the circulator outputs laser to the fiber optic microphone array, and the other output port outputs the reflected light of the fiber optic microphone array to a photodetector, and the output of the photodetector is connected to the data processing equipment after passing through a multi-channel acquisition card.

[0067] Specifically, this embodiment uses a laser to output a light signal with a stable wavelength as the system's excitation source, ensuring that the optical transmission signal of the fiber optic microphone array is stable and reliable. Under laser excitation, the fiber optic microphone is used to collect the sound signal generated by the partial discharge inside the transformer and convert it into optical interference information, achieving highly sensitive acoustic signal detection.

[0068] The optical splitter is used to evenly distribute the laser signal emitted by the laser to multiple fiber optic microphones, ensuring that each fiber optic microphone can receive sufficient optical signal excitation for high-quality sound wave conversion, thereby ensuring the consistency and stability of the signals in each channel;

[0069] The circulator is used to ensure unidirectional signal transmission. Through reasonable optical path design, it prevents the reflected light signal of the fiber optic microphone from interfering with the performance of the laser or other components, thus avoiding affecting the system performance and further improving the signal transmission efficiency of the system.

[0070] Photoelectric detector (PD): The sound wave signal captured by the fiber optic microphone array is transmitted to the photoelectric converter, which converts the sound wave signal transmitted by the optical fiber into an electrical signal to ensure efficient capture and conversion of the sound signal. The photoelectric converter has the advantages of high signal-to-noise ratio and low distortion, which can ensure that the weak sound wave signal is effectively converted into a stable electrical signal for subsequent processing.

[0071] The acquisition card is used to collect signals from multiple photoelectric detectors at the same time, ensuring the synchronous collection of data from multiple sensors, and performing data conversion and preprocessing at high speed. The multi-channel acquisition card synchronously collects the electrical signals output by the photoelectric detectors and digitizes the signals to ensure the real-time and accuracy of high-frequency sampling.

[0072] In this embodiment, the data acquisition system uses high-sampling-rate digitizers, capable of accurately acquiring and transmitting signals at high frequencies. This high-sampling-rate data acquisition ensures signal accuracy at every sampling point, preventing data loss or distortion due to insufficient sampling accuracy, and providing reliable raw data for subsequent acoustic imaging and analysis.

[0073] In this embodiment, the data acquisition system has real-time data processing capabilities, enabling it to simultaneously collect signals and rapidly transmit them to a back-end signal processing module. Upon receiving the data, the signal processing module performs preliminary processing steps such as denoising and filtering to provide a clean signal source for subsequent acoustic imaging and spatial positioning.

[0074] Specifically, in this embodiment, the acoustic signals collected by the spherical fiber optic microphone array are converted into electrical signals via a photoelectric converter and transmitted to a computer or PC for processing via a data acquisition system. This step ensures that the acoustic signals can be accurately converted into electrical signals and provides high-quality data support for subsequent signal processing.

[0075] Furthermore, this embodiment uses low-loss optical fiber transmission technology to minimize signal loss when transmitting the acoustic wave signal from the optical fiber microphone to the optoelectronic converter, and can transmit the signal over long distances to meet the monitoring needs of large transformers.

[0076] As a further preferred technical solution, the data processing device includes:

[0077] The signal processing module is used to perform denoising and filtering on multiple digital signals to obtain processed digital signals;

[0078] The time-frequency analysis module is used to perform time-domain analysis and frequency-domain analysis on the processed digital signal to obtain the effective signal of partial discharge characteristics;

[0079] an amplification module, used to amplify the effective signal of the partial discharge characteristic and adjust the signal gain;

[0080] The acoustic imaging module is used to perform beamforming calculations on effective signals of partial discharge characteristics, reconstruct the spatial distribution of the partial discharge source, and generate an acoustic imaging map of the partial discharge source based on the three-dimensional spatial coordinates inside the transformer.

[0081] In this embodiment, after the data acquisition system receives the electrical signal from the fiber optic microphone array, the signal is immediately transmitted to the signal processing module. The integrity and accuracy of the signal are maintained during the transmission process to ensure that the signal quality is not lost during subsequent processing.

[0082] The signal processing module filters the collected electrical signals through a bandpass filter. The bandpass filter sets a specific frequency range, filters out noise signals with frequencies outside the range, and retains the most valuable frequency bands in the partial discharge signal.

[0083] To further reduce environmental noise, power system noise, and electromagnetic interference, the system incorporates a noise suppression algorithm. This algorithm analyzes the signal in both the time and frequency domains to precisely remove irrelevant noise components. The denoised and filtered signal is further amplified to ensure that no important information is lost during transmission. Automatic gain control (AGC) technology is used to adjust the signal gain, ensuring stable signal strength under varying power conditions, preventing information loss due to weak signals or distortion due to strong signals. After denoising and gain adjustment, signal quality is significantly improved. The signal-to-noise ratio (SNR) is significantly enhanced, ensuring signal accuracy and spatial positioning precision during subsequent acoustic imaging. The signal processing module also optimizes time and frequency domain analysis to eliminate most external interference, providing high-quality raw signals for subsequent localization and imaging of partial discharge sources.

[0084] As a further preferred technical solution, the acoustic imaging module specifically includes:

[0085] The compensation unit is used to calculate the propagation delay τ of the reflected light of each fiber optic microphone in the fiber optic microphone array according to the target direction (θ0, φ0) k , and perform time shift compensation on the reflected light of each fiber optic microphone so that the reflected light signal is phase-aligned in the frequency domain;

[0086] A weighted summing unit, configured to perform weighted summing on the reflected light signals of all the optical fiber microphones and output a beam signal;

[0087] A weight optimization unit, which uses the MVDR (minimum variance distortionless response) method to optimize the weights according to the interference environment, minimize the output power and ensure that the gain in the target direction is 1;

[0088] The imaging unit is used to traverse all directions of the three-dimensional space inside the transformer, repeat the signal preprocessing and beamforming steps, calculate the output power in each direction, and generate an acoustic imaging map of the local discharge source.

[0089] It should be noted that this embodiment first determines the geometric parameters of the spherical array (such as the sphere radius, the number of array elements, and the array element distribution), and accurately calibrates the positions of the array elements, which are expressed in a spherical coordinate system (r, θ, φ), where θ is the pitch angle and φ is the azimuth angle. The time domain signals x of all array elements are synchronously collected. k (t) (where k = 1, 2, ..., K). The key to this step is to accurately record parameters such as the array bandwidth and sampling frequency to ensure high-quality signal acquisition. To ensure signal synchronization, time shift compensation is performed on the signal of each array element to ensure phase alignment in the frequency domain.

[0090] Furthermore, this embodiment improves the angular resolution by increasing the number of array elements or adopting a super-resolution algorithm (such as MUSIC, compressed sensing), thereby avoiding the grating lobe problem and ensuring that the array element spacing matches the wavelength to avoid spatial aliasing.

[0091] It's important to note that compared to traditional planar or one-dimensional arrays, this method, using a spherical array, can capture sound source information in three dimensions, avoiding the limitation of two-dimensional arrays in being unable to locate sound sources behind them. By utilizing the existing spherical array configuration, high-frequency sound source localization can be achieved more efficiently and accurately. While improving low-frequency resolution, this method is applicable to a wider range of applications, particularly within environments where high-frequency imaging is required.

[0092] It should be noted that in this embodiment, a signal processing module is used on the computer or PC side to process the transmitted electrical signal in real time, including steps such as denoising, signal amplification, and filtering to improve signal quality and ensure that the partial discharge signal can be accurately analyzed. The processing module is based on digital signal processing (DSP) technology, which can effectively remove external interference and improve the signal-to-noise ratio of the signal. Acoustic imaging technology is used to analyze the processed electrical signal, and the acoustic wave signal is reconstructed based on algorithms such as beamforming to accurately calculate the location and distribution characteristics of the partial discharge source inside the transformer. This technology synthesizes the signals collected by multiple microphones through information such as time delay and phase difference to construct a spatial imaging map of the partial discharge source. Based on the reconstructed spatial distribution map of the partial discharge source, the partial discharge activity inside the transformer is monitored in real time. The display module dynamically displays the changes in the discharge source, helping operation and maintenance personnel to promptly discover potential fault locations and provide real-time feedback and alarm functions so that timely maintenance or preventive measures can be taken.

[0093] It should be noted that by performing time delay analysis on the signals received by different microphones, the system can estimate the time difference of sound wave propagation, thereby determining the position of the sound source relative to the microphone array. By calculating the time delay and phase difference, the acoustic imaging module can construct a three-dimensional spatial position map of the local discharge source, such as Figure 4The imaging results show that the system can accurately capture the spatial location of point sound sources, and its sound field energy distribution is clearly presented in the visualization image. The red area in the image represents the location with the strongest energy in the sound field, showing the specific location of the point sound source, while the color gradient around the periphery indicates the gradual attenuation of the sound field energy. This demonstrates that the present invention can accurately locate the location of acoustic signal sources such as partial discharge in complex acoustic environments and provide intuitive imaging results.

[0094] In addition, if Figure 5 As shown, another embodiment of the present invention provides a method for detecting partial discharge in a transformer by acoustic imaging and positioning based on a fiber optic microphone. Acoustic imaging and positioning are performed using the above-mentioned device for detecting partial discharge in a transformer by acoustic imaging and positioning based on a fiber optic microphone. The method includes the following steps:

[0095] S10. Design the radius of the spherical fiber optic microphone array and the density of the fiber optic microphone distribution according to the internal space size of the transformer;

[0096] S20. Determine the optimal sensitivity range of each fiber optic microphone in the fiber optic microphone array based on the characteristic curve of the fiber optic microphone and the detection requirements of partial discharge inside the transformer;

[0097] S30, adjusting the laser wavelength output by the signal acquisition module according to the radius of the fiber optic microphone array to stimulate the fiber optic microphone array to collect the sound pressure signal generated by the partial discharge, and converting the collected sound pressure signal into an optical interference signal and outputting it to the signal acquisition module;

[0098] S40, converting the optical interference signal into a multi-channel digital signal using a signal acquisition module;

[0099] S50. Perform beamforming calculations on the multi-channel digital signals using a data processing device to reconstruct the spatial distribution of the partial discharge source, and generate an acoustic imaging diagram of the partial discharge source in combination with the three-dimensional spatial coordinates inside the transformer.

[0100] Furthermore, the method of this embodiment can detect changes in partial discharge inside the transformer in real time online for a long time, continuously monitor the location of the discharge source inside the transformer and changes in its intensity, and can dynamically adjust the monitoring strategy based on the detection results, providing real-time feedback and alarm functions.

[0101] It should be noted that the logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, apparatus, or device (such as a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device), or in conjunction with such instruction execution system, apparatus, or device. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transmit a program for use by an instruction execution system, apparatus, or device, or in conjunction with such instruction execution system, apparatus, or device. More specific examples (non-exhaustive list) of computer-readable media include the following: an electrical connection portion having one or more wires (electronic device), a portable computer disk cartridge (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and programmable read-only memory (EPROM or flash memory), fiber optic devices, and portable compact disk read-only memory (CDROM). Furthermore, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing it in another suitable manner if necessary, and then storing it in a computer memory.

[0102] It should be understood that various parts of the present invention can be implemented using hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0103] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0104] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0105] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. An acoustic imaging and positioning device for detecting partial discharge inside a transformer based on a fiber optic microphone, characterized in that: The invention comprises a signal acquisition module, a data processing device and a fiber optic microphone array arranged inside the transformer, wherein the fiber optic microphone array is composed of a plurality of fiber optic microphones evenly distributed in a spherical geometric structure; The signal acquisition module outputs light source excitation to each microphone channel in the fiber optic microphone array, so that the fiber optic microphone array collects the acoustic wave signal generated by the partial discharge; The fiber optic microphone array converts the collected sound wave signal into an optical interference signal and outputs it to the signal acquisition module; The signal acquisition module converts the optical interference signal into a multi-channel digital signal and outputs it to the data processing equipment; The data processing equipment performs beamforming calculations on multiple digital signals to reconstruct the spatial distribution of the partial discharge source and, combined with the three-dimensional spatial coordinates inside the transformer, generates an acoustic imaging diagram of the partial discharge source.

2. The acoustic imaging and positioning device for detecting partial discharge inside a transformer based on an optical fiber microphone according to claim 1, characterized in that: The radius of the fiber optic microphone array and the density of the fiber optic microphone distribution are designed according to the internal space size of the transformer.

3. The acoustic imaging and positioning device for detecting partial discharge inside a transformer based on an optical fiber microphone according to claim 1, characterized in that: The frequency response range of the fiber optic microphone is 20kHz-200kHz.

4. The acoustic imaging and positioning device for detecting partial discharge inside a transformer based on an optical fiber microphone according to claim 1, characterized in that: The optical fiber microphone is encapsulated in a protective shell, and the protective shell is fixed to the spherical bracket.

5. The acoustic imaging and positioning device for detecting partial discharge inside a transformer based on an optical fiber microphone according to claim 1, characterized in that: The optical fiber microphone is an optical fiber FP microphone, a microphone based on a miniature optical fiber sensor, or an optical fiber Bragg grating microphone.

6. The acoustic imaging and positioning device for detecting partial discharge inside a transformer based on an optical fiber microphone according to claim 1, characterized in that: The signal acquisition module includes a laser, a beam splitter is arranged on the laser light path output by the laser, and a circulator is arranged on the output light path of the beam splitter. One output port of the circulator outputs laser to the fiber optic microphone array, and the other output port outputs the reflected light of the fiber optic microphone array to a photodetector. The output of the photodetector is connected to the data processing equipment after passing through a multi-channel acquisition card.

7. The acoustic imaging and positioning device for detecting partial discharge inside a transformer based on an optical fiber microphone according to claim 1, characterized in that: The data processing device comprises: The signal processing module is used to perform denoising and filtering on multiple digital signals to obtain processed digital signals; The time-frequency analysis module is used to perform time-domain analysis and frequency-domain analysis on the processed digital signal to obtain the effective signal of partial discharge characteristics; an amplification module, used to amplify the effective signal of the partial discharge characteristic and adjust the signal gain; The acoustic imaging module is used to perform beamforming calculations on effective signals of partial discharge characteristics, reconstruct the spatial distribution of the partial discharge source, and generate an acoustic imaging map of the partial discharge source based on the three-dimensional spatial coordinates inside the transformer.

8. The acoustic imaging and positioning device for detecting partial discharge inside a transformer based on an optical fiber microphone according to claim 7, characterized in that: The acoustic imaging module specifically includes: The compensation unit is used to calculate the propagation delay τ of the reflected light of each fiber optic microphone in the fiber optic microphone array according to the target direction (θ0, φ0) k , and perform time shift compensation on the reflected light of each fiber optic microphone so that the reflected light signal is phase-aligned in the frequency domain; A weighted summing unit, configured to perform weighted summing on the reflected light signals of all the optical fiber microphones and output a beam signal; A weight optimization unit is used to optimize the weight according to the interference environment, minimize the output power and ensure that the gain in the target direction is 1; The imaging unit is used to traverse all directions of the three-dimensional space inside the transformer, repeat the signal preprocessing and beamforming steps, calculate the output power in each direction, and generate an acoustic imaging map of the local discharge source.

9. The acoustic imaging and positioning device for detecting partial discharge inside a transformer based on an optical fiber microphone according to claim 7, characterized in that: The data processing device further includes: The data analysis module is used to diagnose the acoustic imaging images, determine the type and hazard level of partial discharge, and trigger a fault warning signal.

10. A method for detecting partial discharge in a transformer by acoustic imaging and positioning based on a fiber optic microphone, characterized in that: The method of performing acoustic imaging positioning using the transformer internal partial discharge detection acoustic imaging positioning device based on an optical fiber microphone as claimed in any one of claims 1 to 9 comprises: According to the internal space size of the transformer, the radius of the spherical fiber optic microphone array and the density of the fiber optic microphone distribution are designed; Based on the characteristic curve of the fiber optic microphone and the detection requirements of partial discharge inside the transformer, the optimal sensitivity range of each fiber optic microphone in the fiber optic microphone array is determined; According to the radius of the fiber optic microphone array, the wavelength of the laser output by the signal acquisition module is adjusted to stimulate the fiber optic microphone array to collect the sound pressure signal generated by the partial discharge and convert the collected sound pressure signal into an optical interference signal before outputting it to the signal acquisition module; The optical interference signal is converted into a multi-channel digital signal using a signal acquisition module; Data processing equipment is used to perform beamforming calculations on multiple digital signals to reconstruct the spatial distribution of the partial discharge source. Combined with the three-dimensional spatial coordinates inside the transformer, an acoustic imaging diagram of the partial discharge source is generated.

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