Optical fiber current transformer system with embedded optical tags and fault section identification method

Abstract

The application provides an optical fiber current mutual inductance system containing embedded optical tags and a fault section identification method, the system comprising an optical link, a modulation box and a sensing ring connected in sequence along the optical link; an array of embedded optical tags is fused to a plurality of key physical nodes in the optical link, an optical time domain reflection unit controls an optical source to inject an optical signal into the optical link, and collects reflection spectra of each optical tag, and the collected reflection spectra are preprocessed; according to the reflection spectra of each optical tag, multi-stage fault state discrimination and response are performed label by label in the order of the optical path topology, and a fault section identification result is output. Through low-loss optical tags at key physical nodes such as the input end of the sensing ring and the output end of the modulation box, and through a specific wavelength coding scheme and a fast identification and positioning algorithm, accurate positioning of the fault section is realized, thereby significantly improving the fault positioning efficiency, reducing misjudgment and reducing costs.

Description

Technical Field

[0001] This invention relates to the fields of intelligent operation and maintenance of power systems and fiber optic sensing technology, and particularly to a fiber optic current transformer system with embedded optical tags and a fault section identification method. Background Technology

[0002] Fiber Optic Current Transformers (FOCTs), with their significant advantages such as small size, simple insulation structure, and lack of magnetic saturation, have become core equipment for current measurement in modern smart substations. Based on the Faraday magneto-optical effect, they can achieve high-precision current monitoring in high-voltage and ultra-high-voltage power systems, providing key technical support for the safe operation of the system. However, in practical applications, FOCTs are often deployed in an outdoor, multi-component, discrete manner: the optical sensing head (including the sensing ring) is installed near the outdoor circuit breaker or disconnector, while the electronic processing unit is placed in the control room, with the two connected by tens to hundreds of meters of optical fiber. While this deployment meets the requirements for electrical insulation and spatial layout, it also brings new challenges, especially in fault location.

[0003] Because key components such as sensing rings, insulators, and modulation boxes are physically independent and exposed to complex outdoor environments for extended periods, factors such as temperature cycling, mechanical vibration, and seal aging can easily lead to increased optical path loss or a deterioration in the system's signal-to-noise ratio, thereby affecting measurement accuracy and even causing system failure. Therefore, quickly and accurately locating faulty sections is crucial for ensuring the stable operation of the power system.

[0004] Especially in outdoor FOCT systems with multiple components deployed discretely, the independent nature of each component makes fault location particularly complex. When system performance degrades or a failure occurs, maintenance personnel often find it difficult to quickly determine which specific component or section the problem originates from. For example, cracks in the adhesive joint of the reflector within the sensing ring, seal failure of the insulator's light transmission rod, or performance degradation of the optical components at the modulation box's output port can all lead to increased overall optical path loss. However, traditional monitoring methods cannot accurately pinpoint the source of the fault.

[0005] Currently, on-site maintenance mainly relies on manual troubleshooting using an Optical Time-Domain Reflectometer (OTDR). However, this method has several limitations: First, OTDR testing requires interrupting current measurement, affecting continuous system operation; second, the testing process is time-consuming, especially in long-distance optical cables, where fault location accuracy is limited by instrument resolution and operator skill; third, OTDRs are not sensitive to subtle localized loss changes, making it difficult to detect early signs of degradation. These problems severely restrict fault handling efficiency, increase maintenance costs, and pose a potential threat to power system reliability.

[0006] Therefore, there is an urgent need for a method that can quickly and accurately locate faulty sections of outdoor optical paths without interrupting measurements. Summary of the Invention

[0007] Based on this, the present invention provides an optical fiber current transformer system with embedded optical tags and a fault section identification method to achieve online monitoring of the optical path status and millisecond-level fault location in the optical fiber current transformer system.

[0008] In a first aspect, embodiments of the present invention provide an optical fiber current transformer system with an embedded optical tag, comprising:

[0009] Optical link, and modulation box and sensing ring connected in sequence along the optical link;

[0010] An embedded optical tag array includes multiple optical tags with preset reflectivity. The multiple optical tags are respectively fused to multiple key physical nodes in the optical link. The key physical nodes include at least the output end of the modulation box and the input end of the sensing ring.

[0011] An optical temporal reflectance unit, connected to the optical link, includes a light source; the optical temporal reflectance unit is configured to control the light source to inject optical signals into the optical link, and to collect the reflection spectra of each optical tag, preprocess the collected reflection spectra, and perform multi-level fault state discrimination and response for each optical tag according to the optical path topology order, and output the fault section identification result;

[0012] The characteristic reflection wavelength of each of the optical tags is located within the frequency sweep range of the light source and is different from the operating wavelength of the optical fiber current inductance system.

[0013] Optionally, the optical time-domain reflectometry unit is an optical time-domain reflectometer, which is only connected to the optical link when detecting optical link failure; or,

[0014] The optical time-domain reflectometry unit is a built-in signal acquisition and processing unit of the optical fiber current transformer system. The signal acquisition and processing unit is also configured to enable the optical fiber current transformer system to measure the current in the external substation.

[0015] Optionally, it also includes an insulator light transmission rod, which is disposed in the optical link, and the key physical node further includes the input end and the output end of the insulator light transmission rod.

[0016] Optionally, the reflectivity of the optical tag ranges from 0.1% to 1%.

[0017] Optionally, the surface of the optical tag is coated with a low-refractive-index material.

[0018] Optionally, the optical tag includes a miniature fiber Bragg grating or a Fabry-Perot interferometer microcavity.

[0019] Based on the same inventive concept, embodiments of the present invention also provide a method for identifying fault sections in an optical fiber current transformer system, which is implemented using the optical fiber current transformer system with embedded optical tags provided in the first aspect, including:

[0020] Step S1: At multiple key physical nodes of the optical link, multiple optical tags are fused together. The reference peak intensity, reference center wavelength and reference spectral half width of each optical tag are collected under standard operating conditions to establish a reference spectral database.

[0021] Step S2: The optical temporal reflectance unit controls the light source to inject optical signals into the optical link, and collects the reflection spectrum of each optical tag and preprocesses the collected reflection spectrum;

[0022] Step S3: The optical temporal reflectance unit performs multi-level state discrimination and response tag by tag according to the optical path topology order and the reflection spectrum of each optical tag, and outputs the fault segment identification result; the multi-level state discrimination and response includes:

[0023] Fault location criteria: When the real-time peak intensity of the first optical tag is lower than the noise threshold and the output power of the light source is within the standard threshold range, the fault is determined to be located in the optical path between the light source and the i-th optical tag; where 1 < i < n, and i and n are both integers.

[0024] When the real-time peak intensity of the i-th optical tag is lower than the noise level, and the real-time peak intensity of the (i-1)-th optical tag upstream of its optical path is greater than a preset percentage of its reference value, the fault is determined to be located in the optical fiber segment between the (i-1)-th optical tag and the i-th optical tag.

[0025] When the real-time peak intensity of the nth optical tag is lower than the noise level, and the real-time peak intensity of the (i-1)th optical tag upstream of its optical path is less than a preset percentage of its reference value, the fault is determined to be located in the optical fiber segment between the (n-1)th optical tag and the nth optical tag; 1 < i < i-1 < n-1 < n, where i and n are integers;

[0026] Degradation warning criterion: When the real-time peak intensity of the i-th optical tag is lower than its baseline value minus a preset threshold for N consecutive times, a degradation warning is issued;

[0027] Environmental anomaly criterion: When the real-time center wavelength offset of the i-th optical tag exceeds the preset threshold, it is determined that there is an abnormality in temperature or stress.

[0028] Spectral distortion warning: When the real-time spectral half-width of the i-th optical tag is greater than twice its reference spectral half-width, it is determined to be local interference or fiber damage, and the spectral distortion of the i-th optical tag is output.

[0029] Optionally, in step S2, the step of controlling the optical temporal reflectance unit to collect the reflectance spectrum of each optical tag includes:

[0030] In the first sampling period, the light source is controlled to sweep the frequency and collect the full-link reflection spectrum for routine inspection;

[0031] When the fault criteria are met, the system automatically switches to the second sampling period and controls the light source to sweep the frequency and collect the full-link reflection spectrum, thereby achieving a high-speed response after the fault is triggered.

[0032] Wherein, the first sampling period is longer than the second sampling period.

[0033] Optionally, step S2, the step of preprocessing the acquired reflectance spectrum, includes:

[0034] Sliding window mean filtering suppresses high-frequency photoelectric noise;

[0035] Perform a quadratic polynomial fit and subtract the background, then perform baseline correction;

[0036] The reflection peak is located within the preset fluctuation range of the characteristic wavelength of each optical tag, and the real-time peak intensity, real-time center wavelength and real-time spectral half width are extracted.

[0037] Calculate the average power in the peakless region across the entire band and calibrate the noise floor in real time.

[0038] Optionally, it also includes a robustness enhancement mechanism, wherein the robustness enhancement mechanism comprises at least one of the following:

[0039] When the total optical power of the system drops by more than 10% within a preset time, dynamic reference scaling compensation is automatically executed.

[0040] When a single optical tag triggers the fault criterion and its adjacent tags show spectral distortion, it is determined to be electromagnetic / vibration interference, and no alarm is triggered but manual verification is notified;

[0041] When the same criterion result is obtained M times consecutively, an increasing weight is assigned. The final decision is output only when the cumulative weight exceeds a preset threshold; M≥3, where M is an integer.

[0042] The system detects the reflection intensity of the light tag in real time. If the reflection intensity exceeds the preset range, the tag is marked as abnormal.

[0043] In summary, the fiber optic current transformer system with embedded optical tags provided in this embodiment of the invention includes an optical link and a modulation box and a sensing ring connected sequentially along the optical link; the embedded optical tag array includes multiple optical tags with preset reflectivities, and the multiple optical tags are respectively fused to multiple key physical nodes in the optical link, the key physical nodes including at least the output end of the modulation box and the input end of the sensing ring; the optical time-domain reflectometry unit is connected to the optical link and includes a light source; the optical time-domain reflectometry unit is configured to control the light source to inject optical signals into the optical link and collect the reflection spectrum of each optical tag, and preprocess the collected reflection spectrum; according to the optical path topology, multi-level fault state discrimination and response are performed tag by tag according to the reflection spectrum of each optical tag, and the fault segment identification result is output; wherein, the characteristic reflection wavelength of each optical tag is located within the frequency sweep range of the light source and is different from the operating wavelength of the fiber optic current transformer system. This invention utilizes low-loss optical tags at key physical nodes such as the sensor loop input and modulation box output, along with a specific wavelength coding scheme and a fast identification and positioning algorithm, to achieve accurate location of faulty sections. This significantly improves fault location efficiency, reduces misjudgments, and lowers costs, providing an efficient and reliable solution for power system operation and maintenance. It has significant application value and promising prospects for widespread adoption. Attached Figure Description

[0044] Figure 1 A schematic diagram of the structure of an optical fiber current transformer system with an embedded optical tag provided in an embodiment of the present invention;

[0045] Figure 2 A schematic diagram of another fiber optic current transformer system with an embedded optical tag provided in an embodiment of the present invention;

[0046] Figure 3 A flowchart illustrating a method for identifying fault sections in an optical fiber current transformer system provided in an embodiment of the present invention;

[0047] Figure 4 This is a schematic diagram of the optical link and optical tag of an optical fiber current transformer system provided in an embodiment of the present invention.

[0048] The following are explanations of the reference numerals in the attached figures:

[0049] 10. Modulation box; 20. Sensing ring; 31. Optical tag; 41. Light source; 11. Polarizer; 42. Coupler; 12. PZT phase modulator; 13. Polarization-maintaining delay fiber ring; 21. Current sensing fiber ring; 22. Conductor. Detailed Implementation

[0050] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the invention and not all structures. Various modifications and variations can be made to the present invention without departing from its spirit or scope, which will be apparent to those skilled in the art. Therefore, the present invention is intended to cover modifications and variations falling within the scope of the corresponding claims (the claimed technical solutions) and their equivalents. It should be noted that the embodiments provided in the present invention can be combined with each other without contradiction.

[0051] Figure 1 This is a schematic diagram of the structure of an optical fiber current transformer system with an embedded optical tag provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of another fiber optic current transformer system with embedded optical tags provided in an embodiment of the present invention, with reference to... Figure 1 and Figure 2 This invention provides an optical fiber current transformer system with embedded optical tags. The system includes an optical link and a modulation box 10 and a sensing ring 20 connected sequentially along the optical link. The embedded optical tag array 30 includes multiple optical tags 31 with preset reflectivities, which are respectively fused to multiple key physical nodes in the optical link. The key physical nodes include at least the output of the modulation box 10 and the input of the sensing ring 20. An optical time-domain reflectometry (OTDR) unit 40 is connected to the optical link and includes a light source 41. The ODR unit 40 is configured to control the light source 41 to inject optical signals into the optical link, collect the reflection spectra of each optical tag 31, preprocess the collected reflection spectra, perform multi-level fault state discrimination and response based on the reflection spectra of each optical tag 31, and output the fault segment identification result. The characteristic reflection wavelength of each optical tag 31 is located within the frequency sweep range of the light source 41 and is different from the operating wavelength of the optical fiber current transformer system.

[0052] In response to the above problems, combined with Figure 1 and Figure 2This invention proposes a fiber optic current transformer (FOCT) system with embedded optical tags and a fault segment identification method. This system embeds specific optical tags 31 at key physical nodes of the outdoor optical link and combines them with efficient monitoring and identification algorithms to achieve online monitoring of the optical path status and precise location of fault segments. This solves the problem of fault location within the FOCT system, improves operation and maintenance efficiency, and ensures the stable operation of the power system. This system and identification method not only effectively overcome the shortcomings of traditional OTDR manual segmentation troubleshooting schemes but also provide a completely new solution for power system operation and maintenance. From a practical application perspective, this invention has significant value and meaning: on the one hand, it can significantly improve the speed and accuracy of fault location, reducing power outage time and economic losses; on the other hand, by introducing IoT and sensor technologies, this method can be deeply integrated with other smart grid technologies, promoting the development of the power system towards greater intelligence and automation. The FOCT system with embedded optical tags and the fault segment identification method provided by this invention not only provide technical support for the operation and maintenance of FOCT but also lay the foundation for the digital transformation of the entire power industry.

[0053] Compared with existing research results, this invention has significant innovations in fault location methods. First, by introducing embedded optical tag technology into the optical link of the fiber optic current transformer system, optical tags are integrated at key physical nodes such as the input end of the sensing ring 20 and the output end of the modulation box 10, forming an array of optical tags with specific wavelength codes. The reflected signal of each optical tag 31 can be independently identified, thereby achieving rapid location of the faulty section.

[0054] The integration location of the optical tag 31 directly determines the accuracy and effectiveness of fault location in the fiber optic current transformer system. Therefore, deploying the optical tag 31 at key physical nodes such as the input end of the sensing ring 20 and the output end of the modulation box 10 is of significant practical importance. Specifically, the input end of the sensing ring 20 serves as the first station for the optical signal entering the outdoor unit, and changes in the signal of its optical tag 31 can effectively reflect the state of the fiber optic link before that node; while the output end of the modulation box 10 can be used to monitor the performance of the modulator and its subsequent optical paths. Furthermore, the fiber optic current transformer system also includes an insulator light transmission rod (…). Figure 1 and Figure 2(Not shown in the diagram) The invention can also place optical tags at the input and output ends of the insulator's optical transmission rod within the optical link, further refining the fault location range. This multi-node deployment strategy significantly improves location accuracy, especially in long-distance optical cables. For example, when the reflected signal of a certain optical tag disappears, the specific segment where the fault occurred can be quickly located by analyzing the signal states of its adjacent optical tags. It is worth noting that the contribution of optical tags at different locations to fault location varies; therefore, in actual deployment, optimization design based on system architecture and operating environment is necessary to achieve full coverage monitoring of the entire outdoor optical link.

[0055] Secondly, the present invention employs low-loss integration technology to control the reflectivity of the optical tag 31 between 0.1% and 1%, thereby avoiding significant interference to the main measurement optical path and ensuring the reliability of the monitoring signal.

[0056] For example, the optical tag 31 can be a miniature fiber grating (FBG), a Fabry-Perot interferometer microcavity, or other microreflectors. Specifically, in fiber optic current transformers, the selection of the optical tag 31 needs to comprehensively consider its size, reflection characteristics, and impact on the main optical path. For example, miniature fiber gratings (FBGs) are the preferred type of optical tag in this invention due to their compact structure, high wavelength selectivity, and ease of integration. In addition, other microreflectors such as Fabry-Perot interferometer microcavities are also considered because they have higher reflectivity and narrower bandwidth, making them suitable for scenarios with high signal strength requirements. However, the advantage of FBGs is that they can achieve precise reflection of specific wavelengths by adjusting the grating period while maintaining low insertion loss, thereby minimizing interference with the main measurement optical path. In contrast, although Fabry-Perot interferometer microcavities have excellent reflection performance, their manufacturing process is complex and costly, limiting their application in large-scale deployments.

[0057] The key optical characteristics of the optical tag 31 include reflection wavelength, reflectivity, and bandwidth. The determination of these parameters requires comprehensive consideration of the system's operating environment and measurement requirements. Firstly, the selection of the reflection wavelength should avoid overlap with the operating wavelength of the fiber optic current inductance system (such as 1310nm or 1550nm) to prevent interference with the main measurement signal. For example, each optical tag is assigned an independent characteristic wavelength to achieve efficient differentiation and accurate identification of the reflected signal. In practical applications, the center reflection wavelength of each optical tag 31 (…) , , The optical tags (…) need to be isolated from each other within the frequency sweep range of the monitoring light source and completely separated from the operating wavelength of the current transformer system (such as 1310nm or 1550nm) to avoid signal interference. The wavelength encoding scheme also needs to consider the scalability of the number of optical tags to adapt to fiber optic current transformer systems of different sizes. For example, in large substations, multiple sensing rings and insulators may need to be deployed, so the encoding scheme needs to support a sufficient number of independent wavelength channels. Secondly, the control of the reflectivity of the optical tag 31 is crucial. Excessive reflectivity may lead to increased signal attenuation in the main optical path, while excessively low reflectivity will affect the detection sensitivity of the reflected signal. Studies have shown that controlling the reflectivity of the optical tag 31 between 0.1% and 1% can minimize the impact on the main optical path while ensuring signal quality. Furthermore, the bandwidth of the optical tag 31 needs to be sufficiently narrow to reduce spectral cross-interference, while also possessing a certain degree of temperature stability to adapt to extreme conditions that may occur in outdoor environments. Through the above design, the optical tag 31 can provide reliable signal support for fault location without significantly affecting system performance.

[0058] Therefore, in practical design, the advantages and disadvantages of different types of optical tags can be weighed according to the needs of specific application scenarios to ensure that the optical tags can meet the accuracy requirements of fault location without significantly affecting system performance.

[0059] In one embodiment of the present invention, reference is made to... Figure 2 The optical path system of a fiber optic current transformer (FOCT) includes key components such as a light source 41, a polarizer 11, a PZT phase modulator 12, a polarization-maintaining delay fiber ring 13, and a current-sensing fiber ring 21. These components together constitute a complex but precise optical link. However, due to the influence of factors such as temperature changes and mechanical vibrations in outdoor environments, the optical components in the fiber optic section are easily damaged or aged, leading to a decrease in measurement performance or even failure. Therefore, ensuring the long-term stable operation of the FOCT in complex environments has become one of the key research focuses.

[0060] The fiber optic current transformer (FOCT) provided in this embodiment of the invention achieves current measurement based on the Faraday magneto-optical effect. Its core principle is that when polarized light propagates in a medium, the polarization plane rotates due to the influence of an external magnetic field, and the rotation angle is proportional to the magnetic field strength. Specifically, refer to... Figure 3 When the light signal emitted by the light source 41 is split by the coupler 42, a portion enters the single-mode fiber 46 and polarizer 11 to form linearly polarized light. This linearly polarized light is modulated by the PZT phase modulator 12 and transmitted to the current sensing fiber ring 21 via the polarization-maintaining delay fiber 13. When the linearly polarized light passes through the current sensing fiber ring 21 wound around the primary conductor 22, due to the magnetic field generated by the conductor 22, the deflection angle of the polarized light is linearly related to the magnitude of the current. This relationship is determined by the Wilder constant (V), i.e. ,in, For Faraday rotation angle, The magnetic field strength, This represents the path of light propagation.

[0061] In this embodiment of the invention, the optical tag 31 is embedded in the optical fiber of the optical link. To achieve low-loss integration of the optical tag 31, the invention also employs advanced fusion splicing technology and precision alignment techniques to ensure that the connection between the optical tag 31 and the optical fiber has high mechanical strength and low insertion loss. Specifically, during the fusion splicing process between the optical tag and the optical fiber, by controlling the discharge parameters of the fusion splicer and the alignment accuracy of the optical fiber, optical signal scattering and attenuation caused by poor splicing can be effectively reduced. Experimental results show that the optimized fusion splicing process can control the insertion loss below 0.1 dB, meeting the requirements of practical applications.

[0062] It should be noted that the low-loss integration method of optical tags in fiber optic segments constitutes one of the core technologies of this invention, and its uniqueness and innovation are reflected in several aspects. First, this invention achieves precise monitoring of the optical path status by fusing microfiber gratings (FBGs) or Fabry-Perot interferometer microcavities, which have low reflectivity, at key physical nodes of the fiber optic current transformer. This integration method not only requires the optical tags themselves to have extremely low insertion loss, but also to ensure that they do not significantly interfere with the main measurement optical path. Specifically, the reflectivity of the optical tags is controlled between 0.1% and 1% to avoid signal distortion or increased noise due to excessive reflection. In addition, the fusion splicing process of the optical tags adopts advanced fiber optic docking technology, and by optimizing the splicing parameters and fiber alignment accuracy, the additional loss in the integration process is further reduced.

[0063] Furthermore, to prevent irreversible damage to fiber optic transmission performance during integration, this invention also introduces a protective coating technology. By depositing a low-refractive-index material coating on the surface of the optical tag, optical signal leakage and loss are further reduced. It is worth noting that the above-mentioned techniques are not only applicable to FBG optical tags but can also be extended to other types of microreflectors, thus providing technical support for diverse application scenarios. Through the aforementioned low-loss integration technology, the optical tag can provide reliable fault location without significantly affecting system performance.

[0064] In one embodiment of this application, reference is made to Figure 1The optical time domain reflector unit 40 is an optical time domain reflectometer (OTDR), which is only connected to the optical link when detecting optical link faults. That is, when the fiber optic current transformer system measures the current of an external substation (power system), the optical time domain reflector unit 40 is disconnected from the fiber optic current transformer system. When it is necessary to detect faults in the fiber optic current transformer system, the optical time domain reflectometer (OTDR) is connected to the optical link of the fiber optic current transformer system. The light source 41 is an independent optical signal source inside the optical time domain reflectometer (OTDR).

[0065] In one embodiment of this application, the optical time domain reflectance unit 40 is a signal acquisition and processing unit 50 built into the optical fiber current transformer system. The signal acquisition and processing unit 50 is also configured to realize the current measurement of the external substation (power system) by the optical fiber current transformer system.

[0066] Furthermore, based on the same inventive concept, this invention also designs an efficient and rapid identification and location algorithm. This method can monitor the optical path loss status online and automatically locate the faulty section without interrupting current measurement, thus overcoming the shortcomings of traditional OTDR methods that rely on manual operation and are inefficient. Overall, this invention not only improves the accuracy and efficiency of fault location but also provides a new solution for the intelligent operation and maintenance of fiber optic current transformers, possessing significant application value and promising prospects for widespread adoption.

[0067] Specifically, the fault section identification method for an optical fiber current transformer system provided in this embodiment of the invention is executed using an optical fiber current transformer system with embedded optical tags provided in the above embodiment. Figure 3 This is a flowchart illustrating a method for identifying fault sections in an optical fiber current transformer system according to an embodiment of the present invention. Figure 4 This is a schematic diagram of the optical link and optical tag of an optical fiber current transformer system provided in an embodiment of the present invention, combined with... Figures 1-4 The fault section identification method for an optical fiber current transformer system provided by the present invention includes:

[0068] Step S1: At multiple key physical nodes of the optical link, multiple optical tags are fused together. The reference peak intensity, reference center wavelength and reference spectral half width of each optical tag are collected under standard operating conditions to establish a reference spectral database.

[0069] Specifically, refer to Figure 4 On multiple key physical nodes of the optical link of the fiber optic current transformer system, n optical tags are embedded sequentially and numbered FBG1~FBGn along the optical path. The reflectivity of a single tag is strictly controlled between 0.1% and 1% to avoid affecting the measurement accuracy of the main optical path. The center reflection wavelength of each optical tag is carefully designed to avoid interference with signals from other optical tags.

[0070] The optical temporal reflectance unit controls the light source to inject optical signals into the optical link and collects the reflection spectra of each tag under standard operating conditions (25℃, no stress, rated optical power), extracting and storing three core reference parameters: reference peak intensity. (Unit: dBm) Quasi-center wavelength (Unit: nm) and reference spectrum full width at half maximum (FWHM) (Unit: nm)

[0071] The collected reference data is written into a non-volatile memory to form a reference database with one-to-one correspondence between tag topology and spectral parameters, and the physical installation location of the tag is recorded synchronously.

[0072] Step S2: The optical temporal reflectance unit controls the light source to inject optical signals into the optical link, and collects the reflection spectrum of each optical tag and preprocesses the collected reflection spectrum.

[0073] Specifically, in combination Figure 2 and Figure 3 As shown, taking the optical time-domain reflectometry unit 40 as an example, which is the built-in signal acquisition and processing unit of the fiber optic current inductance system, the signal acquisition and processing unit integrates a low-power broadband monitoring light source to inject monitoring signals into the main optical path. When the monitoring light propagates along the optical path, the weak reflection signals generated by each optical tag are received by the built-in spectral analysis module of the signal acquisition and processing unit and preprocessed.

[0074] Step S3: The optical temporal reflectance unit performs multi-level state discrimination and response for each optical tag according to the optical path topology order and the reflection spectrum of each optical tag, and outputs the fault section identification result.

[0075] The multi-level state discrimination and response includes fault location criteria, degradation early warning criteria, environmental anomaly criteria, and spectral distortion early warning. The optical temporal reflectance unit performs real-time analysis of the reflectance spectrum, enabling rapid determination of the state of each optical tag. Specifically, refer to Table 1:

[0076] When determining fault location criteria, the first and nth optical tags use boundary-specific criteria, while the ith optical tag uses general criteria. , where i and n are both integers.

[0077] Table 1

[0078]

[0079] Specifically, referring to Table 1, for the first optical tag ( When the optical temporal reflectance unit determines the first optical tag ( Real-time peak intensity () ) lower than noise level ( When the output power of the light source is within the standard threshold range, that is... Furthermore, the light source output power is normal, indicating that the fault is located between the light source and the i-th optical tag. The optical path between ( ).

[0080] For the i-th optical tag ( When the optical temporal reflectance unit determines the real-time peak intensity of the i-th optical tag ( ) lower than noise level ( ), and the (i-1)th optical tag upstream of its optical path ( Real-time peak intensity () When the percentage is greater than the preset percentage of its baseline value, that is and Where 0 < A < 1, as an example, The fault is determined to be located in the fiber optic segment between the (i-1)th optical tag and the ith optical tag.

[0081] For the nth optical tag, when the optical temporal reflectance unit determines the nth optical tag ( Real-time peak intensity () ) lower than noise level ( ), and the (n-1)th optical tag upstream of its optical path ( Real-time peak intensity () The percentage less than its baseline value (e.g.) When, that is and The fault was determined to be located in the fiber optic segment between the (n-1)th optical tag and the nth optical tag. , where i and n are both integers.

[0082] In the degradation early warning criterion: when the optical temporal reflectance unit judges the i-th optical tag ( Real-time peak intensity () ) N consecutive times lower than its benchmark value ( Subtract the preset threshold ( When a problem occurs, a deterioration warning is issued. This enables early identification of potential hazards and supports the effectiveness of condition-based maintenance. For example, Three consecutive samples satisfy: ,like .

[0083] While issuing a degradation warning, the degradation rate can also be calculated simultaneously and the monitoring mode can be switched to enhanced monitoring (e.g., with a sampling period of T / 2).

[0084] Deterioration rate ,unit: .in, The time interval between the two measurements.

[0085] When determining environmental anomalies: when the optical temporal reflectance unit judges the real-time center wavelength offset of the i-th optical tag ( Exceeding the preset threshold ( When, that is The presence of temperature or stress anomalies indicates that multiple tags are shifting in the same direction, manifesting as overall temperature drift; single tag shifting manifests as localized stress / micro-bending. Locating the tag's physical location, the optical tag is upgraded to a distributed sensing node. For example, , This is the default value.

[0086] In spectral distortion early warning: when the optical temporal reflectance unit determines the real-time spectral half-width (FWHM) of the i-th optical tag (… ) is greater than its reference spectral half-width (FWHM) When it is twice the size of ), that is If the signal is determined to be local interference or fiber damage, the spectral distortion of the i-th optical tag is output and marked as suspected local interference / fiber damage.

[0087] As an example, when the analysis results show a significant decrease in the reflection peak intensity of the optical tag located at the input end of the insulator's optical transmission rod, while the signals of other optical tags remain normal, it can be accurately determined that the fault occurs in the fiber optic segment between the input end of the insulator's optical transmission rod and the preceding optical tag. To further verify the accuracy of the location results, maintenance personnel conducted a local inspection of the suspected faulty segment and found that the fiber optic connector was loose, leading to increased optical path loss. After re-fixing, the system measurement signal returned to normal, and the fault was completely eliminated. The fault segment identification method for fiber optic current transformer systems provided by this invention has been fully verified in practical applications for its efficiency and accuracy, providing important technical support for the operation and maintenance of fiber optic current transformers.

[0088] The real-time spectral acquisition includes a regular inspection mode and a fault-triggered mode. In the regular inspection mode, sampling is performed in the first sampling period; in the fault-triggered mode, sampling is performed in the second sampling period. The first sampling period is longer than the second sampling period.

[0089] Specifically, in step S2, the step of controlling the optical temporal reflectance unit 40 to collect the reflectance spectrum of each optical tag 31 includes:

[0090] Using the first sampling period, control the light source to sweep the frequency 41 times to collect the full-link reflectance spectrum for routine inspection. If using a periodic... Broadband light source frequency sweep acquisition of full-link reflection spectrum.

[0091] When the fault criteria are met, the system automatically switches to the second sampling period, controlling the light source 41 to sweep and collect the full-link reflectance spectrum, achieving a high-speed response after fault triggering. For example, when the fault criteria are met, the system operates on a periodic basis. It automatically switches to high-speed sampling mode to achieve millisecond-level response.

[0092] In step S2, the preprocessing step of the acquired reflectance spectrum after sampling includes:

[0093] Sliding window mean filtering, such as a window length of 5 points, can suppress high-frequency noise in photoelectric applications.

[0094] The background is fitted using a quadratic polynomial and subtracted, and then baseline correction is performed.

[0095] In the preset characteristic wavelengths of each optical tag (such as...) Locate the reflection peak within the fluctuation range and extract the real-time peak intensity. ), real-time center wavelength ( ) and real-time spectral half-width (FWHM) ).

[0096] Calculate the average power in the peakless region across the entire band and calibrate the noise floor in real time.

[0097] For example, define the noise floor (Power in the peakless region) ,in, This represents the noise standard deviation.

[0098] Based on the above embodiments, the fault section identification method for fiber optic current transformer systems provided by the present invention further includes a robustness enhancement mechanism, wherein the robustness enhancement mechanism includes at least one of the following:

[0099] Dynamic threshold compensation (anti-light source aging): When the total optical power of the system decreases by more than a certain amount within a preset time... At that time, dynamic baseline scaling compensation is automatically performed.

[0100] Specifically, if the total optical power of the reflection spectrum collected by the optical temporal reflectance unit 40 from each optical tag 31 within 1 hour ( If the decrease is greater than 10%, automatic baseline scaling and dynamic threshold compensation will be performed. The dynamic threshold compensation formula is as follows:

[0101] .

[0102] in, This represents the total optical power after dynamic threshold compensation. The reference peak intensity of the optical tag. The total optical power before dynamic threshold compensation; This represents the baseline peak total intensity of the optical tag.

[0103] This invention avoids false alarms caused by light source attenuation and chronic aging of optical fibers by automatically performing dynamic reference scaling compensation.

[0104] Spatial consistency verification (anti-local interference): When a single optical tag triggers the fault criterion and adjacent tags show spectral distortion, it is determined to be electromagnetic / vibration interference, and no alarm is triggered but manual review is notified.

[0105] Specifically, when a single optical tag triggers the fault criterion, and adjacent optical tags do not exhibit spectral distortion ( The result was determined to be electromagnetic / vibration interference. No alarm was issued at this time, and the case was transferred to manual review.

[0106] Time-series confidence weighting (anti-transient noise): When the same criterion result is obtained M times in a row, an increasing weight is assigned. The final decision is output only when the cumulative weight exceeds a preset threshold. M is an integer. Specifically, three consecutive identical criterion results are assigned increasing weights: The final decision is only output when the weight is greater than or equal to 1.3, thus reducing the error rate caused by instantaneous interference.

[0107] Reflectivity constraint verification: The reflection intensity of the optical tag 31 is detected in real time. If it exceeds the preset reflectivity range, it is marked as an abnormal tag. Specifically, the reflection intensity of the optical tag is detected in real time, and if it exceeds... The range is marked as optical tag abnormal, ruling out non-optical path faults.

[0108] Finally, the optical time-domain reflectometry unit 40 outputs the judgment result. Specifically, the judgment result (timestamp, tag ID, physical location, criterion type, key parameters, confidence level) can be encapsulated into a standard message and uploaded to the power master station via RS485 / Ethernet / IEC61850 protocol. When an alarm is triggered, the original spectral segment of 10 seconds before and after the event is automatically saved, supporting fault tracing and review. Real-time updates to reference parameters and sampling mode switching are synchronously recorded to ensure data traceability.

[0109] The fault section identification method for fiber optic current transformer systems provided by this invention integrates FOCT optical path topology, FBG three-parameter spectral characteristics, and an adaptive robust mechanism, perfectly matching the engineering requirements of low loss, passive operation, and high reliability for outdoor units. Compared with existing technologies, it has at least the following advantages:

[0110] 1) Precise segment-level mapping based on tag space sequence number enables fault location rather than overall alarm.

[0111] 2) A three-parameter coupled criterion of peak intensity, wavelength shift, and spectral linewidth covers all scenarios of fracture, degradation, stress, and temperature drift.

[0112] 3) Dynamic benchmark update + spatial-temporal dual verification, adapting to complex working conditions such as outdoor temperature fluctuations, vibration, and light source attenuation.

[0113] Tests showed that this fault section identification method was effective at different temperature ranges. Under scenarios of strong vibration and 15% light source attenuation: false alarm rate <0.3%, fault location accuracy >99.2%, response time <10 ms, meeting the reliability requirements of power system relay protection level.

[0114] In summary, the fiber optic current transformer system with embedded optical tags and the fault section identification method provided by this invention solve the problem of difficult fault location in outdoor multi-component discrete deployment. Based on the above embodiments, the core content of this method includes optical tag design, low-loss integration method, wavelength coding scheme, and fast identification and location algorithm. In the design of the optical tag, miniature fiber gratings (FBGs) or other microreflectors are mainly selected as core components. Their reflection wavelength and reflectivity are precisely designed to minimize interference to the main measurement optical path while providing reliable reflection signals for fault diagnosis. In terms of the integration method, optical tags are fused at key physical nodes such as the sensor loop input and modulation box output to achieve precise monitoring of each component in the fiber optic link. In addition, by optimizing the fusion splicing process, the impact of the integration process on the fiber optic transmission performance is effectively reduced, thereby ensuring the stability and reliability of the system.

[0115] The wavelength coding scheme further enhances the system's practicality. By assigning an independent characteristic wavelength to each optical tag, mutual interference between signals is avoided, making reflectance spectral analysis more accurate and efficient. Combined with a rapid identification and location algorithm, the system can monitor changes in the reflectance spectrum in real time and determine the specific location of the fault based on preset logical rules. This optical tag-based solution not only achieves rapid fault location but also enables online monitoring without interrupting current measurement, significantly improving maintenance efficiency. Therefore, this invention provides an innovative fault location solution for outdoor units of fiber optic current transformers, possessing significant theoretical and practical value.

[0116] Compared to traditional OTDR manual segmentation troubleshooting methods, the method proposed in this invention demonstrates significant advantages in fault location efficiency, accuracy, and economy. Firstly, regarding fault location efficiency, this method, through embedded optical tags and automated monitoring algorithms, can locate the faulty segment in a very short time, while traditional methods rely on manual operation, which is time-consuming and easily affected by human factors. Secondly, regarding accuracy, this method utilizes optical tags of specific wavelengths to achieve precise monitoring of each component in the fiber optic link, avoiding misjudgments caused by signal attenuation or noise interference in traditional methods, thus significantly improving the accuracy of fault location.

[0117] Furthermore, from a cost and feasibility perspective, the high degree of automation and low operation and maintenance costs of this method make it more economical throughout its entire lifecycle. Especially in large-scale deployment scenarios, this method can significantly reduce labor costs and operation and maintenance time, providing strong support for the efficient operation of power systems.

[0118] In summary, the fiber optic current transformer system with embedded optical tags and the fault section identification method provided by the embodiments of the present invention have shown broad prospects in practical applications. In the future, with the further advancement of smart grid construction, this method is expected to be widely used in the field of power system operation and maintenance, making significant contributions to improving the safety and reliability of power grid operation.

[0119] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A fiber optic current inductor system with an embedded optical tag, characterized in that, include Optical link, and modulation box and sensing ring connected in sequence along the optical link; An embedded optical tag array includes multiple optical tags with preset reflectivity. The multiple optical tags are respectively fused to multiple key physical nodes in the optical link. The key physical nodes include at least the output end of the modulation box and the input end of the sensing ring. An optical temporal reflectance unit, connected to the optical link, includes a light source; the optical temporal reflectance unit is configured to control the light source to inject optical signals into the optical link, and to collect the reflection spectra of each optical tag, and to preprocess the collected reflection spectra; According to the optical path topology, multi-level fault status discrimination and response are performed tag by tag based on the reflection spectrum of each optical tag, and the fault segment identification result is output. The characteristic reflection wavelength of each of the optical tags is located within the frequency sweep range of the light source and is different from the operating wavelength of the optical fiber current inductance system.

2. The fiber optic current inductance system according to claim 1, characterized in that, The optical time-domain reflectometry unit is an optical time-domain reflectometer, which is only connected to the optical link when detecting a fault in the optical link; or... The optical time-domain reflectometry unit is a built-in signal acquisition and processing unit of the optical fiber current transformer system. The signal acquisition and processing unit is also configured to enable the optical fiber current transformer system to measure the current in the external substation.

3. The fiber optic current inductance system according to claim 1, characterized in that, It also includes an insulator light transmission rod, which is set in the optical link. The key physical node also includes the input end and the output end of the insulator light transmission rod.

4. The fiber optic current inductance system according to claim 1, characterized in that, The reflectivity of the optical tag ranges from 0.1% to 1%.

5. The fiber optic current inductance system according to claim 1, characterized in that, The surface of the optical tag is coated with a low-refractive-index material.

6. The fiber optic current inductance system according to claim 1, characterized in that, The optical tag includes a miniature fiber optic grating or a Fabry-Perot interferometer microcavity.

7. A method for identifying fault sections in an optical fiber current transformer system, implemented using an optical fiber current transformer system with embedded optical tags as described in any one of claims 1-6, characterized in that... include: Step S1: At multiple key physical nodes of the optical link, multiple optical tags are fused together. The reference peak intensity, reference center wavelength and reference spectral half width of each optical tag are collected under standard operating conditions to establish a reference spectral database. Step S2: The optical temporal reflectance unit controls the light source to inject optical signals into the optical link, and collects the reflection spectrum of each optical tag and preprocesses the collected reflection spectrum; Step S3: The optical temporal reflectance unit performs multi-level state discrimination and response for each optical tag according to the optical path topology order and the reflection spectrum of each optical tag, and outputs the fault section identification result. The multi-level state discrimination and response includes: Fault location criteria: When the real-time peak intensity of the first optical tag is lower than the noise threshold and the output power of the light source is within the standard threshold range, the fault is determined to be located in the optical path between the light source and the i-th optical tag; where 1 < i < n, and i and n are both integers. When the real-time peak intensity of the i-th optical tag is lower than the noise level, and the real-time peak intensity of the (i-1)-th optical tag upstream of its optical path is greater than a preset percentage of its reference value, the fault is determined to be located in the optical fiber segment between the (i-1)-th optical tag and the i-th optical tag. When the real-time peak intensity of the nth optical tag is lower than the noise level, and the real-time peak intensity of the (i-1)th optical tag upstream of its optical path is less than a preset percentage of its reference value, the fault is determined to be located in the optical fiber segment between the (n-1)th optical tag and the nth optical tag; 1 < i < i-1 < n-1 < n, where i and n are integers. Degradation warning criterion: When the real-time peak intensity of the i-th optical tag is lower than its baseline value minus a preset threshold for N consecutive times, a degradation warning is issued; Environmental anomaly criterion: When the real-time center wavelength offset of the i-th optical tag exceeds the preset threshold, it is determined that there is an abnormality in temperature or stress. Spectral distortion warning: When the real-time spectral half-width of the i-th optical tag is greater than twice its reference spectral half-width, it is determined to be local interference or fiber damage, and the spectral distortion of the i-th optical tag is output.

8. The method according to claim 7, characterized in that, In step S2, the step of controlling the optical temporal reflectance unit to collect the reflectance spectrum of each optical tag includes: Using the first sampling period, control the light source to sweep the frequency and collect the full-link reflection spectrum for routine inspection; When the fault criteria are met, the system automatically switches to the second sampling period and controls the light source to sweep the frequency and collect the full-link reflection spectrum, thereby achieving a high-speed response after the fault is triggered. Wherein, the first sampling period is longer than the second sampling period.

9. The method according to claim 7, characterized in that, In step S2, the preprocessing step of the acquired reflectance spectrum includes: Sliding window mean filtering suppresses high-frequency photoelectric noise; Perform a quadratic polynomial fit and subtract the background, then perform baseline correction; The reflection peak is located within the preset fluctuation range of the characteristic wavelength of each optical tag, and the real-time peak intensity, real-time center wavelength and real-time spectral half width are extracted. Calculate the average power in the peakless region across the entire band and calibrate the noise floor in real time.

10. The method according to claim 7, characterized in that, It also includes robustness enhancement mechanisms, which include at least one of the following: When the total optical power of the system drops by more than 10% within a preset time, dynamic reference scaling compensation is automatically executed. When a single optical tag triggers the fault criterion and its adjacent tags show spectral distortion, it is determined to be electromagnetic / vibration interference, and no alarm is triggered but manual verification is notified; When the same criterion result is obtained M times consecutively, an increasing weight is assigned. The final decision is output only when the cumulative weight exceeds a preset threshold. M≥3, where M is an integer; The system detects the reflection intensity of the light tag in real time. If the reflection intensity exceeds the preset range, the tag is marked as abnormal.

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