GIS (Geographic Information System) metal particle distributed detection system and method and electronic equipment

Abstract

The invention provides a GIS (Geographic Information System) metal particle distributed detection system and method and electronic equipment. The system comprises a light source, a first optical fiber coupler, a second optical fiber coupler, a third optical fiber coupler, a circulator, a reference optical fiber, a sensing optical fiber, a light reflector, a photoelectric detector, a mechanical sound wave generator and a controller. Wherein the input end of the first optical fiber coupler is connected with the light source, and the output end is connected with the first port of the circulator and the reference optical fiber; a second port of the circulator is connected with multiple paths of sensing optical fibers through a second optical fiber coupler, the tail end of each sensing optical fiber is connected with an optical reflector, and a third port and a reference optical fiber are connected with the input end of a third optical fiber coupler; the photoelectric detector is connected with the output end of the third optical fiber coupler; the controller is connected with the photoelectric detector and the mechanical sound wave generator, and GIS metal particle detection is completed based on the interfered light. According to the invention, multiplexing of sensing components can be realized, so that distributed detection of metal particles in GIS equipment is realized.

Description

Technical Field

[0001] The present application relates to the technical field of power equipment, and in particular to a GIS metal particle distributed detection system, method and electronic equipment. Background Art

[0002] Gas-insulated metal-enclosed switchgear (GIS) is a core component of power systems, and its reliable operation is crucial to their stability. Metal particles within GIS can experience vibration and partial discharge under the operating voltage. Traditional methods use pulsed current and ultra-high frequency methods to detect partial discharge defects. However, because electrical detection methods struggle to accurately capture effective information in short-term experiments, acoustic detection methods based on piezoelectric ceramic (PTZ) sensors have been proposed. However, PTZ sensors suffer from poor sensitivity and multiplexing performance.

[0003] In recent years, thanks to the rapid development of optoelectronic theory and devices, fiber optic acoustic emission sensing technology has become a potential solution to replace PZT. Among them, interference fiber optic sensing technology has attracted particular attention. For example, in 2019, Ma Guoming and others from North China Electric Power University proposed a fiber optic acoustic emission sensor based on the Michelson interference structure, which can achieve high-sensitivity detection of metal particle discharge defects inside GIS. In 2023, the research team optimized the sensing optical fiber structure and further improved the detection sensitivity of the fiber optic interference sensing system. In 2021, Jiang Jun and others from Nanjing University of Aeronautics and Astronautics designed a fiber optic acoustic emission sensor based on the Sagnac interference structure for partial discharge defect detection of GIS outlet casings. The experimental conclusions show that the fiber optic sensor has good consistency with the high-frequency current sensor. In 2023, Chen Weigen and others from Chongqing University proposed a built-in GIS partial discharge acoustic emission detection technology based on the Michelson interference structure, which can achieve 15.3pC free metal particle defect discharge detection.

[0004] However, during the research process, the inventors discovered the following problems: the currently developed optical fiber sensors can only perform single-point sensing and cannot achieve distributed detection through multiplexing. Summary of the Invention

[0005] The embodiments of the present application provide a GIS metal particle distributed detection system, method and electronic equipment to solve the problem of distributed detection.

[0006] In one possible implementation,

[0007] In a first aspect, an embodiment of the present application provides a GIS metal particle distributed detection system, comprising: a light source, a first fiber optic coupler, a second fiber optic coupler, a third fiber optic coupler, a circulator, a reference fiber, a sensing fiber, a light reflector, a photodetector, a mechanical acoustic wave generator, and a controller;

[0008] The input end of the first fiber coupler is connected to the light source, and the output end is connected to the first port of the circulator and the reference optical fiber, respectively, for splitting the light emitted by the light source into two beams, and inputting them into the reference optical fiber and the circulator, respectively;

[0009] The second port of the circulator is connected to a multi-channel sensing optical fiber via the second optical fiber coupler, and the end of each sensing optical fiber is connected to a light reflector. The third port of the circulator and the other end of the reference optical fiber are connected to the input end of the third optical fiber coupler, so as to transmit the light emitted by the light source to each sensing optical fiber and transmit the light reflected by each sensing optical fiber to the third optical fiber coupler.

[0010] The photodetector is connected to the output end of the third optical fiber coupler and is used to receive the light after interference occurs in the third optical fiber coupler;

[0011] The controller is connected to the photoelectric detector and the mechanical sound wave generator respectively, and is used to control the mechanical sound wave generator to generate sound waves that cause the phase of the light transmitted in each sensing optical fiber to change, and complete GIS metal particle detection based on the interfered light.

[0012] In a second aspect, an embodiment of the present application provides a GIS metal particle distributed detection method based on the GIS metal particle distributed detection system described in the first aspect above, comprising:

[0013] obtaining an interference output signal from an output end of the third optical fiber coupler;

[0014] Analyzing the interference output signal to determine the phase demodulation result corresponding to each sensing optical fiber;

[0015] The phase demodulation results corresponding to each sensing fiber are compared to determine the distribution of GIS metal particles.

[0016] In a third aspect, an embodiment of the present application provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method described in the second aspect above when executing the computer program.

[0017] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method described in the second aspect above are implemented.

[0018] The present invention provides a distributed metal particle detection system, method, and electronic device for GIS equipment. The system is constructed using a light source, a first fiber optic coupler, a second fiber optic coupler, a third fiber optic coupler, a circulator, a reference fiber, a sensing fiber, a light reflector, a photodetector, a mechanical acoustic wave generator, and a controller. The system utilizes optical sensing technology to accurately detect metal particles within GIS equipment. The light source, as the system's light source, provides a stable optical signal. The input end of the first fiber optic coupler is connected to the light source and distributes the optical signal emitted by the light source into two different paths: a reference path and a sensing path. One sensing path is transmitted to the first port of the circulator. The second port of the circulator is connected to multiple sensing fibers via a second fiber optic coupler. These sensing fibers are placed at key locations within the GIS equipment to detect the presence of metal particles. Each sensing fiber is connected to a light reflector at the end of the circulator to reflect the optical signal and send it back to the circulator. The circulator then transmits the optical signal to the input end of the third fiber optic coupler, where the optical signals from the sensing and reference fibers are combined for subsequent interference analysis. A photodetector is connected to the output end of the third fiber optic coupler to detect the combined optical signal and convert it into an electrical signal. In addition, a mechanical sound wave generator is used to generate sound waves during the detection process. These sound waves can interact with metal particles, thereby changing the characteristics of the optical signal, so that the photodetector can detect the presence of metal particles. By analyzing the light after interference, the controller can determine the position and concentration of the metal particles, thereby realizing distributed detection of GIS metal particles. In the implementation of this application, the sensing optical fiber is arranged at different detection positions of the GIS equipment. The reflected light frequency of each sensing light will be different. When it is transmitted to the third optical fiber coupler through the second optical fiber coupler and the circulator, the sensing components can be reused, thereby realizing distributed detection of metal particles inside the GIS equipment. Through one light source and multiple sensing optical fibers, multiple locations in the GIS equipment can be monitored simultaneously, greatly improving the detection efficiency and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0020] Figure 1This is a schematic diagram of the basic structure of fiber optic acoustic emission sensing based on Michelson interference;

[0021] Figure 2 This is a schematic structural diagram of a GIS metal particle distributed detection system provided in one embodiment of the present application;

[0022] Figure 3 This is a schematic diagram of the structure of a detection experimental platform of a GIS metal particle distributed detection system provided in one embodiment of the present application;

[0023] Figure 4 This is a physical picture of the detection experimental platform of the GIS metal particle distributed detection system provided in one embodiment of the present application;

[0024] Figure 5 It is the signal demodulation result synchronously detected by the optical fiber sensing unit corresponding to the detection experimental platform of the GIS metal particle distributed detection system provided in one embodiment of the present application;

[0025] Figure 6 This is a flowchart of the implementation of the GIS metal particle distributed detection method provided in one embodiment of the present application;

[0026] Figure 7 It is a structural diagram of an electronic device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0027] In the following description, specific details such as specific system structures and techniques are provided for purposes of illustration rather than limitation to facilitate a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid obscuring the description of the present application with unnecessary detail.

[0028] In the description and claims of the embodiments of the present application and the accompanying drawings, the terms "first," "second," and the like are used to distinguish similar objects and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate for the purposes of describing the embodiments of the present application. In addition, the terms "including," "having," and any variations thereof are intended to cover non-exclusive inclusions.

[0029] Unless otherwise specified, the term "plurality" means two or more. The character " / " indicates an "or" relationship between the preceding and following objects. For example, A / B means: A or B. The term "and / or" describes an associative relationship between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or, A and B.

[0030] The terms used in this application are only used to describe the embodiments and are not used to limit the claims. As used in the description of the embodiments and claims, unless the context clearly indicates, the singular forms "a", "an" and "the" are intended to also include the plural forms. Similarly, the term "and / or" as used in this application refers to any and all possible combinations of one or more associated listings. In addition, when used in this application, the term "comprise" and its variations "comprises" and / or comprising refer to the presence of stated features, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or groups thereof. In the absence of further restrictions, the elements defined by the statement "comprising a ..." do not exclude the presence of other identical elements in the process, method or device comprising the elements.

[0031] In this application, each embodiment may focus on the differences from other embodiments, and similar parts between the embodiments can be referenced to each other. For methods, products, etc. disclosed in the embodiments, if they correspond to the method part disclosed in the embodiments, then the relevant parts can be referenced to the description of the method part.

[0032] Long-term operational experience shows that GIS insulation failures occur frequently. According to statistics, GIS insulation failures account for 35.7% and 45.0% of discharge failures in 500kV and 1000kV substation equipment, respectively. Among the many GIS insulation failures, insulation surface flashover failures caused by metal particle defects introduced during assembly and operation account for as much as 43%. Therefore, strengthening GIS metal particle defect detection is a key priority in power grid operation and maintenance.

[0033] When detecting metal particle defects using partial discharge detection methods such as the pulse current method and the ultra-high frequency method, electrical detection methods often find it difficult to accurately capture effective information in short-term experiments because the partial discharge characteristics of metal particles in GIS are highly random and intermittent and are susceptible to electromagnetic interference.

[0034] Acoustic detection methods based on piezoelectric ceramic (PTZ) sensors are often used on-site. They can detect the acoustic vibration signals caused by particle vibrations and capture the ultrasonic waves generated by discharges for defect identification. However, these methods present the following challenges: 1) Existing PZT sensors are not very sensitive. For microscale metal particles, the signals they generate are very small, making it difficult to achieve high-sensitivity detection using PZT. 2) PZT sensors have poor multiplexing performance and exhibit significant propagation attenuation of acoustic vibration signals. Large-scale GIS equipment often requires multi-point simultaneous detection, which PZT sensors struggle to meet.

[0035] When using interferometric fiber optic sensing technology to detect metal particle discharge defects within GIS, the basin-shaped insulation within the GIS significantly attenuates the propagation of acoustic signals. Consequently, multiple sensors must be deployed for simultaneous detection at multiple points during a single experiment. The inability to reuse fiber optic sensors inevitably increases operational and maintenance costs, hindering the application and development of fiber optic sensing technology.

[0036] The present invention proposes a multiplexing method of fiber optic acoustic emission sensors based on optical swept frequency interferometry based on the Michelson interference structure. A set of detection and demodulation systems can be used to separate and demodulate multi-channel sensing signals, thereby forming a distributed fiber optic sensing system for GIS metal particle defect detection.

[0037] To facilitate understanding of the detection process of this application, the fiber optic acoustic emission sensing technology based on Michelson interferometry is first introduced.

[0038] Fiber optic acoustic emission sensing based on Michelson interference uses mechanical sound waves to cause phase changes in the light transmitted in the optical fiber to achieve signal perception. The basic structure of the sensing system is as follows: Figure 1 shown.

[0039] The laser light is divided into sensing light and reference light after passing through the fiber coupler. One beam enters the sensing fiber and the other enters the reference fiber. The two beams of light are reflected by the end fiber reflector and return to the original path, and interfere with each other at the fiber coupler. Assume that the light fields of the two beams of light that interfere in the system are E s and E r , then

[0040] E s (t) = E s0 expj[2πf0(t+τ s )] (1)

[0041] E r (t) = E r0 expj[2πf0(t+τ r )] (2)

[0042] Where: t is time, f0 is the laser output frequency, E s0 is the amplitude of the sensing light field, τ s is the time it takes for light to travel back and forth in the sensing fiber, E r0 is the reference light field amplitude, τ r is the round-trip transmission time of light in the reference fiber.

[0043] After the two beams of light interfere, the interference light intensity I can be expressed as:

[0044]

[0045] Where: c is the speed of light in vacuum, n is the refractive index of the optical fiber, and ε0 is the dielectric constant of vacuum.

[0046] Known sensor light intensity amplitude I s0 and the reference light intensity amplitude I r0 They can be expressed as:

[0047]

[0048] Substituting formulas (4) and (5) into (3), we can obtain:

[0049]

[0050] Where: τ is the time difference between the two beams of light, and:

[0051]

[0052] Where: l is the optical path difference between the interferometer sensing fiber and the reference fiber.

[0053] When the metal particles beat or discharge, the acoustic signal generated acts on the sensing fiber, changing the size of the sensing fiber, thereby changing the initial optical path difference l between the sensing fiber and the reference fiber, and then introducing the phase change of the interference light. Therefore, formula (6) can be expressed as:

[0054]

[0055] Where: is the initial phase, we have:

[0056]

[0057] Therefore, the effect of the external sound signal can be reflected by demodulating the phase change of the interference light.

[0058] like Figure 1 The frequency of the laser output light increases linearly at a certain speed starting from f0. Assuming that the reference fiber length is very short, the transmission time of light in the reference fiber, i.e., τ r Can be ignored. Then the laser light field E returned by the reference fiber to the coupler is r It can be expressed as:

[0059] E r (t) = E r0 exp[j(2πf0t+πγt 2 )] (10)

[0060] Where: γ is the laser sweep rate.

[0061] It is known that there is a certain optical path difference between the sensing fiber and the reference fiber. The laser light field E returned from the sensing fiber to the coupler is s It can be expressed as:

[0062] E s (t) = E s0 exp[j(2πf0(t-τ+πγ(t-τ) 2 )] (11)

[0063] According to the above derivation, when affected by external sound signals, the intensity I of the two interfering light beams can be expressed as

[0064]

[0065] Where: For a constant phase, we have:

[0066]

[0067] Comparing formulas (8) and (12), it can be seen that the optical frequency sweep method can introduce a high-frequency component into the phase of the interference light signal. The frequency of this component is related to the initial length difference l between the sensing fiber and the reference fiber. Therefore, if there are multiple sensing fibers, and the optical path difference with the reference fiber is different, the interference light signal should be the superposition of multiple frequency components.

[0068] In order to make the purpose, technical solutions and advantages of this application clearer, specific embodiments will be described below with reference to the accompanying drawings.

[0069] Figure 2 This is a schematic diagram of the structure of the GIS metal particle distributed detection system provided by an embodiment of the present application. Figure 1 As shown, it includes: a light source, a first fiber optic coupler, a second fiber optic coupler, a third fiber optic coupler, a circulator, a reference fiber, a sensing fiber, a light reflector, a photodetector, a mechanical acoustic wave generator and a controller.

[0070] The input end of the first fiber coupler is connected to the light source, and the output end is connected to the first port of the circulator and the reference fiber respectively, so as to split the light emitted by the light source into two beams and input them into the reference fiber and the circulator respectively.

[0071] The second port of the circulator is connected to the multi-channel sensing fiber through the second fiber coupler. The end of each sensing fiber is connected to a light reflector. The third port of the circulator and the other end of the reference fiber are connected to the input end of the third fiber coupler, which is used to transmit the light emitted by the light source to each sensing fiber and transmit the light reflected by each sensing fiber to the third fiber coupler. Figure 2In the figure, four optical fibers are shown as an example. In other embodiments, the number of optical fibers can be adjusted according to the detection position, for example, five, six or more.

[0072] The photoelectric detector is connected to the output end of the third optical fiber coupler and is used for receiving the light after interference occurs in the third optical fiber coupler.

[0073] The controller is connected to the photoelectric detector and the mechanical acoustic wave generator respectively, and is used to control the mechanical acoustic wave generator to generate acoustic waves that cause the phase of the light transmitted in each sensing optical fiber to change, and complete the GIS metal particle detection based on the light after interference.

[0074] The light source is the light source part of the system and is responsible for providing stable light signals.

[0075] A circulator is an optical device with three ports for controlling the transmission direction of optical signals. In this embodiment, the transmission direction of the circulator is: the signal input to the first port is output through the second port, and the signal input to the second port is output through the third port.

[0076] The first fiber coupler splits the light emitted by the light source into two beams: one for reference and the other for sensing. The second port of the circulator is connected to multiple sensing fibers via a second fiber coupler. The third port of the circulator and the other end of the reference fiber are connected to the input of a third fiber coupler. The circulator then transmits the light emitted by the light source to each sensing fiber. Each sensing fiber is connected to a light reflector at the end to reflect the light. This allows the light reflected from each sensing fiber to be transmitted to the third fiber coupler.

[0077] The output end of the third fiber coupler is connected to a photodetector, which receives the light after interference from the third fiber coupler. By analyzing the interference light, information about the GIS metal particles can be obtained.

[0078] The controller's primary function is to control the mechanical acoustic wave generator to produce acoustic waves that cause phase shifts in the light transmitted through each sensing fiber. This allows the controller to demodulate the interfering light collected by the photodetectors and detect metal particles in the GIS.

[0079] In this embodiment, a distributed GIS metal particle detection system is constructed using a light source, a first fiber optic coupler, a second fiber optic coupler, a third fiber optic coupler, a circulator, a reference fiber, a sensing fiber, a light reflector, a photodetector, a mechanical acoustic wave generator, and a controller. This system utilizes optical sensing technology to accurately detect metal particles within GIS equipment. The light source, as the light source component of the system, is responsible for providing a stable optical signal. The input end of the first fiber optic coupler is connected to the light source and distributes the optical signal emitted by the light source into two different paths: a reference path and a sensing path. One sensing path is transmitted to the first port of the circulator. The second port of the circulator is connected to multiple sensing fibers via a second fiber optic coupler. These sensing fibers are placed at key locations in the GIS equipment to detect the presence of metal particles. Each sensing fiber is connected to a light reflector at the end of the circulator to reflect the optical signal and send it back to the circulator. The circulator then transmits the optical signal to the input end of the third fiber optic coupler, where the optical signals from the sensing and reference fibers are combined for subsequent interference analysis. A photodetector is connected to the output end of the third fiber optic coupler to detect the combined optical signal and convert it into an electrical signal. In addition, a mechanical sound wave generator is used to generate sound waves during the detection process. These sound waves can interact with metal particles, thereby changing the characteristics of the optical signal, so that the photodetector can detect the presence of metal particles. By analyzing the light after interference, the controller can determine the position and concentration of the metal particles, thereby realizing distributed detection of GIS metal particles. In the implementation of this application, each sensing optical fiber is arranged at a different detection position of the GIS device, and the reflected light frequency of each sensing light will be different. When it is transmitted to the third optical fiber coupler through the second optical fiber coupler and the circulator, the sensing components can be reused, thereby realizing distributed detection of metal particles inside the GIS device. Through one light source and multiple sensing optical fibers, multiple locations in the GIS device can be monitored simultaneously, greatly improving the detection efficiency and accuracy.

[0080] Based on the aforementioned embodiment, the sensing fibers are placed at different detection locations on the GIS equipment to cover key areas and monitor their status in real time. However, in actual applications, the inventors have discovered a potential problem: when two or more detection locations are very close to each other, the frequencies of the light reflected from these locations may become identical or extremely similar, making the reflected signals difficult to distinguish, thereby affecting the accuracy and reliability of the monitoring data.

[0081] In a possible implementation, the lengths of the sensing optical fibers are different from each other.

[0082] To address the aforementioned issues, the inventors proposed a solution: adjusting the lengths of the various sensing fibers to make them distinct. This length difference results in slightly different frequencies in the optical signals reflected from each sensing fiber. This ensures the independence and identifiability of each signal, even when the detection locations are close, thereby achieving frequency division multiplexing of the sensor device. This method effectively separates and identifies the reflected signals from each detection location, ensuring the accuracy and efficiency of the monitoring system.

[0083] In other possible implementations, the independence of each signal can be ensured by other possible implementations. Optionally, frequency modulation technology can be introduced into the sensing fiber or light sources with different wavelengths can be used to further enhance the signal differentiation.

[0084] Other possible implementations include introducing frequency modulation technology into the sensing fiber, using light sources of different wavelengths, and adjusting the fiber length to provide a more flexible and reliable solution. These comprehensive measures ensure that the sensing fiber system can operate stably in complex GIS equipment environments.

[0085] As can be seen from the above embodiments, by setting different sensing fiber lengths, the reflected signals of each sensing fiber can be separated. On this basis, increasing the frequency difference between the corresponding signals of each sensing fiber can achieve multi-path separation through bandpass filtering.

[0086] In a possible implementation, the length difference between the sensing optical fibers is determined according to the sweep rate of the light source, the frequency of the mechanical acoustic wave generator, the speed of light in a vacuum, and the refractive index of the sensing optical fibers.

[0087] Among them, by determining the length difference between each sensing optical fiber through multiple parameters, it can be ensured that there is an appropriate length difference between the sensing optical fibers, so as to generate an interference effect when receiving the acoustic wave signal, thereby achieving accurate measurement of the acoustic wave signal.

[0088] In one possible implementation, the length difference between the sensing fibers is calculated as follows:

[0089]

[0090] Where, Δl i is the length difference between the sensing fibers; is the phase change amplitude of the interference light caused by the signal to be measured, f u is the frequency of the external acoustic signal; c is the speed of light in a vacuum; γ is the frequency sweep rate of the light source; and n is the refractive index of the sensing fiber.

[0091] In the actual implementation process, in order to ensure the flexibility and adaptability of the system, Adjust according to actual detection needs. The following explains the principle of determining the length difference between each sensing fiber:

[0092] like Figure 2 As shown, the laser output light passes through the first coupler (i.e. Figure 2 After the middle coupler 1), it is split into two, one enters the reference optical path, and the other enters the sensing optical path. In the sensing optical path, the laser passes through the fiber circulator and then passes through the second fiber coupler (i.e. Figure 2 The middle coupler 2) is divided into n paths, and a reflector is connected to the end of each sensing optical fiber. The reflected light will return along the original optical path and enter the third optical fiber coupler (i.e. Figure 2 Interference occurs after the middle coupler 3). At this time, the AC component of the interference light intensity I can be expressed as:

[0093]

[0094] Where: I s0i is the intensity amplitude of the sensing light passing through the i-th sensing optical fiber, τ i is the time difference between the i-th sensing light and the reference light, is the constant phase corresponding to the interference of the i-th sensing light, is the optical phase change caused by the external signal acting on the i-th sensing fiber, and M(t) is the noise term, which is caused by the interference of various sensing lights at the third fiber coupler. This noise term contains signals with multiple frequency components, and its maximum frequency depends on the difference in the round-trip transmission time of the laser in each sensing fiber. By setting an appropriate sensing fiber length, this noise term can be kept in the low frequency band.

[0095] It can be seen from formula (14) that by setting different sensing fiber lengths, τ i If there is a difference, the interference signal frequency after each sensor fiber is different. Therefore, the signal after photoelectric conversion can be separated into multiple signals by bandpass filtering to obtain the target signal U corresponding to each sensor fiber. i (i=1~n), thereby realizing frequency division multiplexing of sensor devices. i It can be expressed as:

[0096]

[0097] Where: U io is the amplitude of the AC component after photoelectric conversion, f i is the carrier frequency, we have:

[0098] f i =γτ i =γΔli n / c (16)

[0099] Where: l i is the length difference between the i-th sensing optical fiber and the reference optical fiber.

[0100] Based on the above theoretical results, Figure 2 a distributed system with multiplexing of four optical fiber sensing units is designed in the shown embodiment, that is, 4 optical fiber sensing units are connected into Figure 2 the topology, denoted as sensors 1# to 4# respectively. As can be seen from the foregoing analysis, the key to separating and demodulating the four sensing signals lies in: 1) the frequency bands of the target signals U i (i = 1 to 4) of each sensor do not overlap; 2) the noise signals M caused by the interference of the optical signals in each sensing optical path at the third optical fiber coupler (i.e., Figure 2 coupler 3 in it) have frequencies less than the target signals U i (i = 1 to 4) corresponding to each sensor.

[0101] As can be seen from formula (12), the target signals U i (i = 1 to 4) corresponding to each sensor can be regarded as carrier signals with a carrier frequency of f i The optical phase change caused by the external acoustic vibration signal can be regarded as phase modulation of this signal. According to Carson's bandwidth rule, the effective bandwidth EBD of this carrier signal (i.e., the target signal U i ) corresponding to each sensor) can be expressed as:

[0102]

[0103] Where: f u is the frequency of the external acoustic vibration signal. is the amplitude of the interference optical phase change that can be caused by the measured signal. According to the vibration intensity of the metal particles inside the GIS and relevant literature records, take

[0104] In a specific embodiment, when f u = 80 kHz, then EBD = 480 kHz can be determined. Therefore, in order to avoid mutual crosstalk between multiple signals, in this distributed sensing system, the carrier frequency difference between each path should be higher than the effective bandwidth of 480 kHz. And the minimum carrier frequency should be higher than 0.5EBD = 240 kHz. Assuming f1 < f2 < f3 < f4, then:

[0105]

[0106] In addition, for the noise M(t), its maximum frequency is f4 - f1. In order to ensure that the noise term does not overlap with each target signal, there should be:

[0107] (f4-f1)+480kHz≤f1 (20)

[0108] Considering the constraints of formulas (19) and (20), in a 4-channel multiplexed sensing system, the minimum carrier frequencies should be selected as f1 = 0.96 MHz, f2 = 1.44 MHz, f3 = 1.92 MHz, and f4 = 2.4 MHz.

[0109] In the above specific embodiment, the external acoustic vibration signal frequency f u =80kHz, the laser sweep rate is set to γ = 1.249 × 10 13 Hz / s, and the speed of light c = 3×10 8 m / s, n = 1.46. From formula (16), we can get the fiber length differences between each sensing optical path and the reference optical path should be l1 = 15.79m, l2 = 23.69m, l3 = 31.59m, l4 = 39.48m respectively.

[0110] The above embodiments mainly introduce the main components of the system. In the process of completing GIS metal particle detection based on the GIS metal particle distributed detection system, it is also crucial to analyze and process the light parameters received by the photoelectric detector.

[0111] In a possible implementation, the controller includes: a demodulation device for demodulating and analyzing the light collection results after interference to complete GIS metal particle detection.

[0112] In this embodiment, the demodulation device in the controller demodulates the light collection results after interference to achieve in-depth analysis, so as to accurately complete the detection of GIS metal particles.

[0113] In a possible implementation, the controller is further configured to be connected to the light source and to control light parameters of light emitted by the light source.

[0114] In this embodiment, a controller is connected to a light source and can effectively control the light parameters of the light emitted by the light source, such as wavelength, intensity, and pulse frequency. This control capability allows the controller to adjust the light parameters according to detection requirements to optimize the detection process and improve detection accuracy and efficiency. For example, the controller can adjust the wavelength of the light to achieve the optimal interference effect, or adjust the light intensity to ensure sufficient signal quality, depending on the different detection environments and metal particle characteristics. In this way, the controller can flexibly adapt to various detection scenarios and ensure the reliability and consistency of detection results.

[0115] In order to verify the detection effect of the GIS metal particle distributed detection system provided in the embodiment of the present application, Figure 3As shown in the figure, a detection experimental platform was built based on 126kV GIS. Figure 4 shown.

[0116] The GIS experimental platform consists of a high-voltage bushing and four test chambers, each separated by a basin insulator. A power-frequency power supply applies voltage to the central guide rod within the chamber through the bushing. Before the experiment, a 10 mm thick metal wire was placed on the surface of one of the basin insulators to simulate a discharge defect. Furthermore, each chamber was filled with 0.5 MPa SF6. Four fiber optic sensing units from a distributed fiber optic sensing system were fixed to the outer walls of each of the four test chambers to simultaneously detect metal particle defects in the GIS.

[0117] The experimental results of the four sensing optical fibers corresponding to the sensing units are as follows: Figure 5 As shown in the figure, when the applied voltage increases to 35kV, the signal demodulation results of the four optical fiber sensing units synchronously detected in one power frequency cycle are as follows: Figure 5 As shown in the figures.

[0118] The following are method embodiments of the present application. For details not fully described therein, please refer to the corresponding system embodiments described above.

[0119] Figure 6 FIG. 1 is a flow chart of a GIS metal particle distributed detection method provided in an embodiment of the present application. Figure 6 As shown, the method includes:

[0120] S601: Acquire an interference output signal from an output end of a third optical fiber coupler.

[0121] S602: Analyze the interference output signal to determine the phase demodulation result corresponding to each sensing optical fiber.

[0122] S603 , comparing the phase demodulation results corresponding to the sensing optical fibers to determine the distribution of the GIS metal particles.

[0123] In the embodiment of the present application, the execution subject of the method is the controller in the GIS metal particle distributed detection system of the aforementioned embodiment.

[0124] The controller is connected to the output of the third fiber coupler to obtain an interference output signal from the output of the third fiber coupler. The interference pattern generated by the fiber coupler after coupling the optical signal contains the phase information of the light wave transmitted in the sensing fiber.

[0125] Then, the controller analyzes the interference output signal to determine the phase demodulation result corresponding to each sensing fiber, with the aim of extracting the phase change information of each sensing fiber from the interference pattern.

[0126] Finally, by analyzing the pattern and amplitude of the phase changes, the location and distribution characteristics of the metal particles can be inferred.

[0127] In one possible implementation, the demodulation results corresponding to each sensing fiber are compared to determine the distribution of metal particles in the GIS, including:

[0128] Compare the demodulation results corresponding to each sensing fiber to determine the distribution information of the background noise and the pulse sound signal exceeding the background noise;

[0129] When the amplitude of the pulse sound signal exceeding the background noise exceeds a set value or the proportion exceeds a set ratio, it is determined that GIS metal particles exist in the detection area of the corresponding sensing optical fiber.

[0130] Among them, determining the distribution information of background noise and pulse sound signals exceeding the background noise is aimed at distinguishing normal background noise from abnormal signals.

[0131] In a possible implementation, if the amplitude of the pulse sound signal exceeding the background noise exceeds a set value, it is considered that metal particles may exist in the area.

[0132] In another possible implementation, if the proportion of pulsed acoustic signals exceeding background noise exceeds a set ratio, the area is considered likely to contain metal particles. Because sampling errors can cause outliers during detection, this method based on the excess ratio helps avoid false detections.

[0133] In a possible implementation, before comparing the phase demodulation results corresponding to the respective sensing optical fibers, the method further includes: obtaining the phase demodulation results corresponding to the respective sensing optical fibers within a power frequency cycle.

[0134] In this embodiment, on the one hand, the analyzed data is collected on the same time scale, thereby improving the accuracy and reliability of the detection. On the other hand, by collecting data over a complete power frequency cycle, a more comprehensive understanding of the dynamic changes in the signal can be obtained, thereby more accurately identifying and locating the presence of metal particles.

[0135] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0136] Figure 7 Schematic diagram of the structure of an electronic device provided by an embodiment of the present application. Figure 7As shown, the electronic device 7 of this embodiment includes: a processor 70, a memory 71, and a computer program 72 stored in the memory 71 and executable on the processor 70. When the processor 70 executes the computer program 72, the steps in each of the above-mentioned GIS metal particle distributed detection method embodiments are implemented, such as Figure 6 The steps shown.

[0137] Exemplarily, the computer program 72 may be divided into one or more modules / units, which are stored in the memory 71 and executed by the processor 70 to implement the present application. The one or more modules / units may be a series of computer program instruction segments capable of performing specific functions, and the instruction segments are used to describe the execution process of the computer program 72 in the electronic device 7.

[0138] The electronic device 7 may be a computing device such as a desktop computer, a notebook, a PDA, or a cloud server. The electronic device 7 may include, but is not limited to, a processor 70 and a memory 71. Those skilled in the art will understand that Figure 7 It is only an example of the electronic device 7 and does not constitute a limitation of the electronic device 7. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the electronic device may also include input and output devices, network access devices, buses, etc.

[0139] The processor 70 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor.

[0140] The memory 71 may be an internal storage unit of the electronic device 7, such as a hard disk or memory of the electronic device 7. The memory 71 may also be an external storage device of the electronic device 7, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the electronic device 7. Furthermore, the memory 71 may include both an internal storage unit of the electronic device 7 and an external storage device. The memory 71 is used to store the computer program and other programs and data required by the electronic device. The memory 71 may also be used to temporarily store data that has been output or is about to be output.

[0141] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0142] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0143] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed in this application can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0144] In the embodiments provided in the present application, it should be understood that the disclosed devices / electronic devices and methods can be implemented in other ways. For example, the device / electronic device embodiments described above are merely schematic. For example, the division of the modules or units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0145] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0146] In addition, the functional units in the various embodiments of the present application may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0147] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present application implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by the processor, it can implement the steps of the above-mentioned various GIS metal particle distributed detection method embodiments. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device that can carry the computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium, etc.

[0148] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A GIS metal particle distributed detection system, characterized in that: include: A light source, a first fiber optic coupler, a second fiber optic coupler, a third fiber optic coupler, a circulator, a reference fiber, a sensing fiber, a light reflector, a photodetector, a mechanical acoustic wave generator, and a controller; The input end of the first fiber coupler is connected to the light source, and the output end is connected to the first port of the circulator and the reference optical fiber, respectively, for splitting the light emitted by the light source into two beams, and inputting them into the reference optical fiber and the circulator, respectively; The second port of the circulator is connected to a multi-channel sensing optical fiber via the second optical fiber coupler, and the end of each sensing optical fiber is connected to a light reflector. The third port of the circulator and the other end of the reference optical fiber are connected to the input end of the third optical fiber coupler, so as to transmit the light emitted by the light source to each sensing optical fiber and transmit the light reflected by each sensing optical fiber to the third optical fiber coupler. The photodetector is connected to the output end of the third optical fiber coupler and is used to receive the light after interference occurs in the third optical fiber coupler; The controller is connected to the photoelectric detector and the mechanical sound wave generator respectively, and is used to control the mechanical sound wave generator to generate sound waves that cause the phase of the light transmitted in each sensing optical fiber to change, and complete GIS metal particle detection based on the interfered light.

2. The GIS metal particle distributed detection system according to claim 1, characterized in that: The lengths of the sensing fibers are different from each other.

3. The GIS metal particle distributed detection system according to claim 1, characterized in that: The length difference between the sensing optical fibers is determined according to the sweep rate of the light source, the frequency of the mechanical acoustic wave generator, the speed of light in a vacuum, and the refractive index of the sensing optical fibers.

4. The GIS metal particle distributed detection system according to claim 3, characterized in that: The length difference between the sensing fibers is calculated as follows: Where, Δl i is the length difference between the sensing fibers; is the phase change amplitude of the interference light caused by the signal to be measured, f u is the frequency of the external acoustic signal; c is the speed of light in a vacuum; γ is the frequency sweep rate of the light source; and n is the refractive index of the sensing fiber.

5. The GIS metal particle distributed detection system according to claim 1, characterized in that: The controller includes a demodulation device for demodulating and analyzing the light collection results after interference to complete GIS metal particle detection.

6. The GIS metal particle distributed detection system according to claim 1, characterized in that: The controller is also used to connect with the light source and to control the light parameters of the light emitted by the light source.

7. A GIS metal particle distributed detection method based on the GIS metal particle distributed detection system according to any one of claims 1 to 6, characterized in that: include: obtaining an interference output signal from an output end of the third optical fiber coupler; Analyzing the interference output signal to determine the phase demodulation result corresponding to each sensing optical fiber; The phase demodulation results corresponding to each sensing fiber are compared to determine the distribution of GIS metal particles.

8. The GIS metal particle distributed detection method according to claim 7, characterized in that: The comparison of the demodulation results corresponding to the respective sensing optical fibers to determine the distribution of the GIS metal particles includes: Comparing the demodulation results corresponding to the respective sensing optical fibers to determine the distribution information of the background noise and the pulse sound signal exceeding the background noise; When the amplitude of the pulse sound signal exceeding the background noise exceeds a set value or the proportion exceeds a set ratio, it is determined that GIS metal particles exist in the detection area of the corresponding sensing optical fiber.

9. The GIS metal particle distributed detection method according to claim 7, characterized in that: Before comparing the phase demodulation results corresponding to the respective sensing optical fibers, the method further includes: Obtain the phase demodulation results corresponding to each sensing optical fiber within a power frequency cycle.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and capable of running on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 7 to 9 are implemented.

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