Weak-coupling few-mode photonic crystal fiber transformer substation temperature monitoring method, system, equipment and medium
By constructing a weakly coupled few-mode photonic crystal fiber model and performing beam decomposition and polarization processing, the problems of signal attenuation and insufficient model guidance in substation temperature monitoring were solved, and high-precision and reliable temperature measurement was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-17
- Publication Date
- 2026-03-20
AI Technical Summary
Existing substation temperature monitoring methods suffer from limitations in monitoring accuracy and reliability due to signal attenuation, signal quality degradation after long-distance transmission, and a lack of calibration mechanisms and optimized sensor models, resulting in easy drift of measured values under complex electromagnetic environments and temperature fluctuations.
A theoretical model of the optical fiber was constructed using a weakly coupled few-mode photonic crystal fiber. The laser beam was generated and decomposed into a signal beam and a reference beam through optimization iteration using the controlled variable method. Polarization processing and calibration were performed, and the resonant wavelength offset was extracted to determine the true temperature.
It improves the accuracy and reliability of temperature monitoring, overcomes the signal attenuation problem, ensures accurate extraction of resonant wavelength offset in complex background noise, and realizes stable and accurate monitoring of substation equipment temperature.
Smart Images
Figure CN121706321A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of temperature monitoring technology, and in particular to a method, system, equipment and medium for temperature monitoring in weakly coupled few-mode photonic crystal fiber substations. Background Technology
[0002] With the continuous improvement of the intelligence level of power systems, health management and fault prediction of substation equipment have become key aspects of modern power systems. Temperature, as one of the important parameters of equipment status, plays a crucial role in the operational monitoring of substation equipment. Changes in temperature are often precursors to equipment failures; excessively high temperatures can lead to aging of insulation materials, damage to electrical components, and even major accidents such as fires. Therefore, timely and accurate monitoring of substation equipment temperature is essential for ensuring the stability and safety of the power system.
[0003] However, in existing technologies, whether it is a distributed temperature sensor or a sensor based on fiber Raman scattering, the monitoring methods are limited by the characteristics of the fiber itself and the system architecture, resulting in two major drawbacks: First, the monitoring accuracy and reliability are limited by signal attenuation. After long-distance transmission, the signal quality deteriorates, making it difficult to accurately extract the key feature signals used for temperature inversion. Second, the lack of calibration mechanisms and optimized sensing models makes the monitoring system less adaptable to the complex electromagnetic environment and temperature fluctuations in substations, and the measured values are prone to drift, making it difficult to guarantee long-term stability. Summary of the Invention
[0004] In view of the aforementioned existing problems, the present invention is proposed.
[0005] Therefore, this invention provides a method, system, equipment, and medium for temperature monitoring in weakly coupled few-mode photonic crystal fiber substations, which solves the problems that the monitoring accuracy and reliability of existing monitoring methods are limited by signal attenuation, signal quality deteriorates after long-distance transmission, and there is a lack of calibration mechanisms and optimized sensing models for guidance.
[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:
[0007] In a first aspect, the present invention provides a method for temperature monitoring in a weakly coupled few-mode photonic crystal fiber substation, comprising: constructing a fiber optic theoretical model; using a controlled variable method to change the refractive index and spatial position of the device under test, evaluating the performance indicators of the fiber optic theoretical model, and obtaining a production fiber optic model; generating a laser beam, the laser beam reaching an optical coupler through a single-mode fiber; decomposing the laser beam into a signal beam and a reference beam through the optical coupler; performing polarization processing on the signal beam to obtain linearly polarized light, and acquiring the intensity of the reference beam; coupling the linearly polarized light to the production fiber optic model, and acquiring the spectrum of the linearly polarized light output by the production fiber optic model; calibrating the spectrum of the linearly polarized light based on the intensity of the reference beam, extracting the resonance wavelength offset from the calibrated spectrum, and determining the true temperature of the device under test based on the resonance wavelength offset.
[0008] As a preferred embodiment of the weakly coupled few-mode photonic crystal fiber substation temperature monitoring method of the present invention, the step of constructing the fiber theoretical model includes: establishing a geometric model based on a preset photonic crystal fiber cross-sectional topology, and assigning corresponding material properties to different regions of the geometric model; performing optimization iteration processing on the geometric model to obtain the fiber theoretical model; the optimization iteration processing step includes: setting one or more geometric parameters to be optimized and the value range of the geometric parameters; calculating whether the geometric model satisfies the plasmonic resonance condition based on the geometric parameters, wherein the plasmonic resonance condition is expressed as: the real part of the effective refractive index of the conduction mode is equal to the real part of the effective refractive index of the surface plasmon mode; when the plasmonic resonance condition is satisfied, the fiber theoretical model is obtained; when the plasmonic resonance condition is not satisfied, the value range of the geometric parameters is changed, and the plasmonic resonance condition is calculated again.
[0009] The beneficial effects of this preferred technical solution are as follows: by establishing a geometric model and assigning material properties by pre-setting the cross-sectional topology of the photonic crystal fiber, the geometric model can fit the actual fiber structure. Then, the geometric model is optimized and iterated, the geometric parameters and range to be optimized are set, and the plasma resonance condition of the effective refractive index of the conduction mode and the surface plasmon mode is used for judgment. If it is not satisfied, the parameter range is adjusted and the calculation is repeated. This ensures that the obtained fiber theoretical model meets the plasma resonance requirements.
[0010] As a preferred embodiment of the weakly coupled few-mode photonic crystal fiber substation temperature monitoring method of the present invention, the step of obtaining the production fiber model includes: calculating the loss spectrum of the fiber theoretical model by changing the geometric parameters to obtain preferred parameters; based on the preferred parameters, changing the refractive index of the device under test and calculating the performance index of the fiber theoretical model; based on the preferred parameters, changing the spatial position of the device under test and evaluating the impact on the performance index to obtain an evaluation result; when the evaluation result meets the preset stability, obtaining the production fiber model based on the preferred parameters.
[0011] The beneficial effects of this preferred technical solution are as follows: by changing the geometric parameters to calculate the loss spectrum of the optical fiber theoretical model, the preferred parameters are obtained, making the loss characteristics of the model more in line with actual needs; then, based on the preferred parameters, the performance index of the device under test is calculated by changing the refractive index of the device under test, which can verify the performance of the optical fiber theoretical model when the refractive index of the device under test changes; next, the impact of changing the spatial position of the device under test on the performance index can be evaluated, and the impact of spatial position changes can be known in advance; finally, the production optical fiber model is obtained after the evaluation results meet the stability requirements. In actual use, the performance of the produced optical fiber model can remain stable regardless of changes in the refractive index of the device under test or changes in spatial position, which is suitable for the actual scenario of substation temperature monitoring.
[0012] As a preferred embodiment of the weakly coupled few-mode photonic crystal fiber substation temperature monitoring method of the present invention, the step of polarizing the signal beam includes: guiding the signal beam into a polarizer; filtering and polarizing the unpolarized signal beam through the polarizer to obtain linearly polarized light.
[0013] The beneficial effects of this preferred technical solution are as follows: By filtering and polarizing the signal beam with a polarizer to obtain linearly polarized light, the influence of polarization mode dispersion in weakly coupled few-mode photonic crystal fibers can be reduced, making signal transmission more stable. At the same time, the state of linearly polarized light is consistent, which can accurately capture the changes in optical signals caused by temperature changes during temperature monitoring, thereby improving the accuracy and reliability of temperature monitoring in substations.
[0014] As a preferred embodiment of the weakly coupled few-mode photonic crystal fiber substation temperature monitoring method of the present invention, the step of extracting the resonance wavelength offset includes: obtaining the spectral intensity through the spectrum of the linearly polarized light, calculating the ratio of the spectral intensity to the intensity of the reference beam as the calibrated spectral intensity, and generating a calibrated spectrum through the calibrated spectral intensity; identifying the characteristic loss peak caused by the surface plasmon resonance effect excited by the production fiber model in the calibrated spectrum, and determining the center wavelength corresponding to the characteristic loss peak as the measurement resonance wavelength; preset the reference resonance wavelength, and calculate the difference between the measurement resonance wavelength and the reference resonance wavelength to obtain the resonance wavelength offset.
[0015] The beneficial effects of this preferred technical solution are as follows: The spectrum is calibrated using the ratio of the spectral intensity of linearly polarized light to the intensity of the reference beam, which can offset the influence caused by fluctuations in the light source or changes in fiber loss, thus improving the accuracy of characteristic loss peak identification; the measurement resonant wavelength is determined by the characteristic loss peak of the surface plasmon resonance effect, which has obvious characteristics and makes it easier to determine the corresponding center wavelength; the resonant wavelength offset is obtained by calculating the difference between the measured resonant wavelength and the reference resonant wavelength, and the resonant wavelength offset can directly correspond to temperature changes, thereby improving the accuracy of substation temperature monitoring.
[0016] As a preferred embodiment of the weakly coupled few-mode photonic crystal fiber substation temperature monitoring method of the present invention, the step of determining the true temperature of the device under test based on the resonant wavelength offset includes: dividing the resonant wavelength offset by the preset temperature sensitivity coefficient of the production fiber model to obtain the temperature change of the device under test; calculating the sum of the temperature change and the preset reference temperature to obtain the true temperature of the device under test.
[0017] The advantages of this preferred technical solution are as follows: By directly correlating the measured resonant wavelength offset with the preset temperature sensitivity coefficient of the production fiber model, a simple and physically clear linear conversion relationship is established, avoiding complex iterative calculations or empirical fitting, and improving the real-time performance and reliability of temperature calculation; using a preset reference temperature as a benchmark, combined with the calculated temperature change, it can not only accurately reflect the absolute temperature value of the device under test, but also eliminate system zero drift and cumulative errors in long-term monitoring. This calculation directly based on physical parameters ensures the accuracy of the measurement results and is suitable for achieving stable and accurate online monitoring of equipment temperature in the complex environment of substations.
[0018] Secondly, the present invention provides a weakly coupled few-mode photonic crystal fiber optic substation temperature monitoring system, comprising:
[0019] Light source module: used to generate laser beams;
[0020] Beam splitter module: used to decompose the received laser beam into a signal beam and a reference beam;
[0021] Polarization processing and beam acquisition module: used to polarize the signal beam to obtain linearly polarized light, and to acquire the intensity of the reference beam;
[0022] Sensing module: used to receive the linearly polarized light and convert the temperature change of the device under test into a resonant wavelength offset output;
[0023] Signal acquisition and processing module: used to acquire the spectrum of the linearly polarized light and calculate the spectral intensity, process the spectral intensity and the intensity of the reference beam to calculate the resonant wavelength offset, and determine the true temperature of the device under test based on the resonant wavelength offset.
[0024] As a preferred embodiment of the weakly coupled few-mode photonic crystal fiber substation temperature monitoring system of the present invention, the sensing module includes a substrate; the substrate has an analyte channel, a pre-coated hole, and an air hole respectively opened inside; the substrate is made of silicon dioxide, the inner surface of the pre-coated hole is coated with a metal layer, and the air holes are arranged in a periodic pattern.
[0025] The beneficial effects of this preferred technical solution are as follows: the substrate is made of silicon dioxide, which not only has good optical transmittance and chemical stability, but also can adapt to the harsh environment of high temperature and high pressure in substations; the metal layer coated on the inner surface of the pre-coated holes can excite surface plasmon resonance, ensuring the sensitivity response of the sensing area to changes in the refractive index of the surrounding medium; the analyte channel provides a specific flow and contact path for the medium surrounding the device under test, ensuring the efficiency and directness of temperature transfer. The arrangement of air holes constitutes a specific waveguide structure of the photonic crystal fiber, which, in synergy with the pre-coated holes, can modulate the optical field mode and promote its coupling with the surface plasmon of the metal layer, thereby enhancing the surface plasmon resonance effect and improving the sensitivity and signal-to-noise ratio of the sensing module.
[0026] Thirdly, the present invention provides an electronic device, comprising:
[0027] Memory and processor;
[0028] The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, they implement the steps of the weakly coupled few-mode photonic crystal fiber substation temperature monitoring method.
[0029] Fourthly, the present invention provides a computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the steps of the weakly coupled few-mode photonic crystal fiber substation temperature monitoring method.
[0030] Compared with existing technologies, the beneficial effects of this invention are as follows: Through a dual-beam design and calibration mechanism, the signal attenuation problem is overcome, improving monitoring accuracy and long-term reliability. By decomposing the laser beam into a signal beam and a reference beam, and using the intensity of the reference beam to calibrate the spectrum of linearly polarized light, it is possible to compensate for general signal attenuation caused by factors such as laser source power fluctuations and connector losses. This ensures accurate extraction of the true resonant wavelength offset from complex background noise, solving the problem of measurement inaccuracies caused by signal quality degradation after long-distance transmission.
[0031] By constructing a theoretical model of optical fiber and optimizing it iteratively using the controlled variable method, the model was ensured to meet the plasma resonance condition and its performance was evaluated. This resulted in a production optical fiber model specifically designed for substation temperature monitoring. This process ensures that the final sensing module has a pre-defined and optimized temperature sensitivity coefficient, guaranteeing the accuracy and reliability of the monitoring method from the outset and overcoming the limitations of existing technologies that lack targeted model guidance. Attached Figure Description
[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0033] Figure 1 This is a schematic diagram of the overall process of a weakly coupled few-mode photonic crystal fiber substation temperature monitoring method according to an embodiment of the present invention.
[0034] Figure 2 This is a cross-sectional schematic diagram of the sensing module in a weakly coupled few-mode photonic crystal fiber substation temperature monitoring system according to an embodiment of the present invention.
[0035] Figure 3 This is a schematic diagram showing the relationship between the aperture value of the analyte channel and the characteristic loss value caused by surface plasmon resonance in a weakly coupled few-mode photonic crystal fiber substation temperature monitoring method according to an embodiment of the present invention.
[0036] Figure 4 This is a schematic diagram showing the relationship between the hole spacing value between adjacent air holes and the characteristic loss value caused by surface plasmon resonance in the weakly coupled few-mode photonic crystal fiber substation temperature monitoring method according to an embodiment of the present invention. Detailed Implementation
[0037] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.
[0038] Example 1, referring to Figure 1 As an embodiment of the present invention, a method for temperature monitoring in a weakly coupled few-mode photonic crystal fiber substation is provided, comprising steps S100~S500:
[0039] S100. Construct a theoretical model of optical fiber, and use the controlled variable method to change the refractive index and spatial position of the device under test respectively to evaluate the performance index of the optical fiber theoretical model and obtain the production optical fiber model.
[0040] S200 generates a laser beam, which travels through a single-mode fiber to the optical coupler.
[0041] S300: The laser beam is decomposed into a signal beam and a reference beam through an optical coupler. The signal beam is polarized to obtain linearly polarized light, and the intensity of the reference beam is collected.
[0042] S400: Couple linearly polarized light to the production fiber model and collect the spectrum of the linearly polarized light output by the production fiber model.
[0043] S500 calibrates the spectrum of linearly polarized light based on the intensity of the reference beam, extracts the resonant wavelength offset from the calibrated spectrum, and determines the true temperature of the device under test based on the resonant wavelength offset.
[0044] It should be noted that substations have numerous electrical devices and operate in complex environments. Traditional temperature monitoring methods suffer from problems such as cumbersome wiring and susceptibility to electromagnetic interference. The sensing performance of weakly coupled few-mode photonic crystal fibers is closely related to temperature; however, in practical applications, changes in the refractive index and spatial position of the device under test can affect its performance indicators. Simultaneously, during laser beam transmission, the stability of the reference beam intensity and the calibration accuracy of the signal beam spectrum directly impact the accuracy of temperature measurement. Improper calibration can easily lead to significant errors. Therefore, achieving accurate temperature monitoring of substation equipment presents numerous challenges.
[0045] Therefore, to address the limitations of traditional methods, the numerous factors affecting sensor performance, and insufficient spectral calibration accuracy in substation temperature monitoring, this paper proposes a method through steps S100-S500. This method constructs and optimizes a production fiber model, generates and decomposes a laser beam, completes the coupling and spectral acquisition of linearly polarized light, and then calibrates the spectrum of the linearly polarized light based on the reference beam intensity to extract the resonant wavelength shift. Ultimately, this method accurately determines the true temperature of the device under test, overcoming the shortcomings of traditional monitoring methods and improving the accuracy, anti-interference capability, and spatial adaptability of substation temperature monitoring.
[0046] Example 2, refer to Figures 1-4 As an embodiment of the present invention, based on the above embodiment, a method for monitoring temperature in a weakly coupled few-mode photonic crystal fiber substation is provided.
[0047] In this embodiment of the application, the step of constructing the optical fiber theoretical model in step S100 includes A1~A2:
[0048] A1. Establish a geometric model based on the preset cross-sectional topology of the photonic crystal fiber, and assign corresponding material properties to different regions of the geometric model.
[0049] First, in the finite element analysis software, a two-dimensional cross-sectional geometric model is created according to a preset topology. In this embodiment, the geometric model is constructed using COMSOL. The preset topology includes, but is not limited to, a substrate 1 as a background material and analyte channels 2, preset holes 3, and air holes 4 opened within the substrate 1. Next, corresponding material properties are assigned to different regions of the geometric model. For example, the material property of the substrate 1 is set to silicon dioxide, the material property of the analyte channel 2 is initialized to the test medium (including but not limited to oil, temperature-sensitive materials, etc.), the material property of the inner surface of the pre-coated hole 3 is set to a metal layer, and the material property of the air hole 4 is set to air.
[0050] A2. Perform optimization iteration on the geometric model to obtain the optical fiber theoretical model;
[0051] Using the geometric model established and assigned material properties in step A1 as the input object, the optical performance of the geometric model is made to meet the design requirements through iterative calculation, thereby constructing the optical fiber theoretical model. The specific optimization and iteration process is a cyclical process.
[0052] The optimization iterative processing steps include A2.1 to A2.3:
[0053] A2.1. Set one or more geometric parameters to be optimized and the range of values for the geometric parameters;
[0054] Based on the geometric model established in step A1, one or more geometric parameters that have a significant impact on optical performance are selected from the geometric model as optimization variables. In this embodiment, the optimization variables include, but are not limited to, the diameter d1 of the analyte channel 2 and the hole spacing p between adjacent air holes 4. Subsequently, a value range is set for each selected geometric parameter. For example, the value range of the diameter d1 of the analyte channel 2 is set to 7.2 μm to 8.0 μm, and the value range of the hole spacing p between adjacent air holes 4 is set to 13.0 μm to 13.5 μm.
[0055] A2.2 Calculate whether the geometric model satisfies the plasma resonance condition based on the geometric parameters. The plasma resonance condition is expressed as: the real part of the effective refractive index of the conduction mode is equal to the real part of the effective refractive index of the surface plasma mode.
[0056] The specific geometric parameters set in step A2.1 are assigned to the geometric model established in step A1, thereby obtaining a simulated structure with defined parameters. Subsequently, numerical simulation is performed using the finite element method to calculate the optical characteristics of the simulated structure in two key aspects: first, the effective real part of the refractive index of the linearly polarized light propagating in the optical fiber, i.e., the signal beam; second, the effective real part of the refractive index of the surface plasmon mode excited by the metal layer coated on the inner surface of the pre-coated hole 3. After the calculation, it is determined whether the plasmon resonance condition is met, i.e., whether the difference between the effective real part of the refractive index of the propagation mode and the effective real part of the refractive index of the surface plasmon mode is within the preset calculation tolerance range. In this embodiment, the set calculation tolerance range is 1×10⁻⁶. -4 Then output a boolean result: true means that the plasma resonance condition is met, and false means that the plasma resonance condition is not met.
[0057] A2.3 When the plasma resonance condition is met, the optical fiber theoretical model is obtained. When the plasma resonance condition is not met, the range of values for the geometric parameters is changed, and the geometric model is recalculated to see if the plasma resonance condition is met.
[0058] If the judgment result received from step A2.2 is true, it indicates that the current set of geometric parameters is a feasible solution that enables the geometric model to meet the plasma resonance condition. At this time, the geometric model under the current parameters is determined as the fiber optic theoretical model, and the current optimization iteration ends. If the judgment result received from step A2.2 is false, it means that no feasible solution has been found within the currently set range of values, and the range of values must be adjusted. In this embodiment, step A2.1 sets the initial value range of the hole spacing p between adjacent air holes 4 to 13.0 μm to 13.5 μm. This range is insufficient to satisfy the plasma resonance condition for the geometric model. Therefore, the operation of "changing the value range of geometric parameters" is performed. Based on the calculation results, the value range of the hole spacing p between adjacent air holes 4 is adjusted to an interval that is more likely to contain feasible solutions, for example, modified to 13.8 μm to 14.2 μm. Then, the calculation is performed again, i.e., jumping back to step A2.2, to regenerate candidate parameter values with the new value range of the hole spacing p between adjacent air holes 4, update the geometric model, and perform simulation to determine whether the new model satisfies the plasma resonance condition. This iterative loop will continue until step A2.2 returns a true result, and the final optical fiber theoretical model is output.
[0059] In an optional implementation, the construction of the optical fiber theoretical model in step S100 can also employ a multiphysics coupling simulation method. This method, based on optical modal simulation, further introduces a thermodynamic field for coupling analysis: First, temperature boundary conditions are added to the geometric model established in step A1 in the finite element software to simulate the temperature distribution under the substation environment; then, the structural thermal expansion and material refractive index changes caused by temperature changes (such as the thermo-optical effect of the silica matrix) are calculated, and these physical quantity changes are fed back to the optical model to iteratively update the geometric parameters and material properties; finally, an optical fiber theoretical model that has been pre-compensated for temperature effects and can more accurately predict the optical response (relationship between resonant wavelength and temperature) under actual working conditions is obtained.
[0060] In this embodiment of the application, the step of obtaining the production optical fiber model in step S100 includes B1 to B4:
[0061] B1. Optimal parameters are obtained by calculating the loss spectrum of the optical fiber theoretical model by changing the geometric parameters;
[0062] Within the feasible solution range of geometric parameters satisfying the plasmon resonance condition, the geometric parameters were fine-tuned, and the loss spectrum corresponding to each set of parameters was calculated using the finite element method. By analyzing the depth and width of the characteristic loss peaks caused by the surface plasmon resonance effect in the loss spectrum, the response intensity and sharpness of the fiber theoretical model under different parameters were evaluated. Finally, the set of geometric parameters with the highest loss was determined as the preferred parameters.
[0063] In this embodiment, as Figure 3 As shown, with the increase of the diameter d1 of the analyte channel 2, the peak loss of the characteristic loss peak caused by the surface plasmon resonance effect gradually decreases. This is because the increase of the diameter d1 of the analyte channel 2 changes the energy distribution of the optical field, making it easier for evanescent waves to leak into the metal layer of the pre-coated hole 3 adjacent to the analyte channel 2, thereby reducing the intensity of the surface plasmon resonance. Furthermore... Figure 2 The data also shows that the resonance wavelength blue-shifts as the diameter d1 of the analyte channel 2 decreases. Therefore, within the range of 7.2 μm to 8.0 μm for the diameter d1 of the analyte channel 2 obtained in step A2.2, setting the diameter d1 to 8.0 μm helps to reduce the peak loss of the characteristic loss peak. Figure 4 As shown, the variation in the spacing p between adjacent air holes 4 affects the resonant wavelength. When the spacing p = 14.0 μm, the peak loss of the characteristic loss peak caused by the surface plasmon resonance effect is minimized. This indicates that the coupling efficiency between the surface plasmon mode and the conduction mode is the highest. Therefore, p = 14.0 μm is considered the optimal value for optimizing the coupling efficiency. In summary, the determined preferred parameters are the combination of the diameter d1 = 8.0 μm of the analyte channel 2 and the spacing p = 14.0 μm between adjacent air holes 4.
[0064] B2. Based on the optimized parameters, change the refractive index of the device under test and calculate the performance index of the optical fiber theoretical model;
[0065] The preferred parameters obtained in step B1 are fixed as the final structural parameters of the optical fiber theoretical model. Next, the refractive index of the device under test is simulated within a certain range in a simulation environment, for example, the refractive index change caused by temperature variation, and the resonant wavelength shift corresponding to each refractive index point is calculated. In this embodiment, the performance indicators include, but are not limited to, the temperature sensitivity coefficient, which is characterized by calculating the resonant wavelength shift caused by a unit refractive index change and further converting it to the shift caused by a unit temperature change.
[0066] B3. Based on the optimized parameters, change the spatial position of the device under test, evaluate the impact on performance indicators, and obtain the evaluation results.
[0067] Keeping the optimal parameters of the fiber optic theoretical model unchanged, fine-tune the spatial position of the device under test (DUT) relative to the fiber optic theoretical model in the simulation environment, for example, by making a small offset along the axial or radial direction of the fiber optic theoretical model. For each different spatial position, repeat the process in step B2 to calculate the performance index, namely the temperature sensitivity coefficient. By comparing the values of the performance index at different positions, evaluate its fluctuation range. If the fluctuation range is very small, for example, the sensitivity change rate is less than 5%, it indicates that the fiber optic theoretical model is not sensitive to the installation position, and the evaluation result is stable; otherwise, it indicates that the design is too sensitive to the position, and the evaluation result is poor.
[0068] B4. When the evaluation results meet the preset stability, the production fiber model is obtained based on the optimized parameters.
[0069] The evaluation results obtained in step B3 are used to determine whether the optical fiber theoretical model possesses the stability required for practical application. If the evaluation result is stable, the optical fiber theoretical model design is considered robust and reliable. In this case, the optical fiber theoretical model based on this set of optimized parameters is determined as the final production optical fiber model, which can be used to guide actual optical fiber drawing and system integration. If the evaluation result is unsatisfactory, it is necessary to return to step B1 and recalculate by changing the geometric parameters.
[0070] In an optional implementation, the production fiber model obtained in step S100 can also be obtained using a multi-objective collaborative optimization method. This method does not take the peak loss of the characteristic loss peak as a single objective when determining the optimal parameters, but comprehensively considers multiple key performance indicators, such as the resonant peak width, crosstalk suppression ratio, and sensitivity to manufacturing errors. It assigns weights to each indicator and establishes a comprehensive evaluation function. Then, through a multi-objective optimization algorithm, such as the non-dominated sorting genetic algorithm II, it searches in the parameter feasible solution space and finally selects the Pareto optimal solution parameter combination that achieves the best balance among multiple performance indicators, thereby obtaining a production fiber model with stronger robustness and better overall performance.
[0071] In this embodiment of the application, the step of polarizing the signal beam in step S300 includes guiding the signal beam into a polarizer, filtering and polarizing the unpolarized signal beam through the polarizer to obtain linearly polarized light.
[0072] The signal beam transmitted through a single-mode fiber is coupled to the incident end face of the polarizer. The polarizer uses its internal birefringence or selective absorption characteristics to filter the unpolarized signal beam: it attenuates or reflects polarization components that are not aligned with the transmission axis of the polarizer, and only allows polarization components aligned with the transmission axis to pass through. This completes the polarization conversion from unpolarized light to single-direction polarized light. Finally, the signal beam emitted from the polarizer is linearly polarized light with a high degree of polarization and a definite polarization direction.
[0073] In this embodiment of the application, the step of extracting the resonant wavelength shift in step S500 includes C1~C3:
[0074] C1. Obtain the spectral intensity from the spectrum of linearly polarized light, calculate the ratio of the spectral intensity to the intensity of the reference beam as the calibrated spectral intensity, and generate the calibrated spectrum from the calibrated spectral intensity.
[0075] First, the spectrum of linearly polarized light is analyzed using a spectrometer to obtain the raw spectral intensity values at each wavelength. Since the spectrum characterizes the distribution of light intensity with wavelength, subsequent processing needs to be performed independently for each specific wavelength. Then, the spectral intensity value corresponding to each wavelength is compared with the intensity value of the reference beam to eliminate common-mode noise introduced by laser source power fluctuations and random losses in the transmission link. The resulting ratio is the calibrated spectral intensity corresponding to that wavelength. Finally, each wavelength is re-associated with its corresponding calibrated spectral intensity value to generate a complete calibrated spectrum.
[0076] C2. Identify the characteristic loss peak caused by the surface plasmon resonance effect excited by the production fiber model in the calibrated spectrum, and determine the center wavelength corresponding to the characteristic loss peak as the measurement resonance wavelength.
[0077] The characteristic loss peak appears as a distinct valley in the spectrum, a typical feature of surface plasmon resonance. A peak detection algorithm is used to scan and analyze the calibrated spectral curve to identify this characteristic loss peak. For example, a Gaussian fitting algorithm is used to approximate the contour of the valley as a Gaussian distribution curve. The optimal Gaussian function parameters are then fitted using the least squares method, and the wavelength position corresponding to the extreme point of this Gaussian function is calculated. This wavelength position is the center wavelength of the characteristic loss peak.
[0078] Alternatively, a local extremum search algorithm can be used to directly search for local minima in the calibrated spectral data sequence. By comparing the intensity values of adjacent data points, the bottom of the depression can be located, and the wavelength corresponding to the bottom of the depression can be determined as the center wavelength of the characteristic loss peak.
[0079] C3. Preset the reference resonant wavelength and calculate the difference between the measured resonant wavelength and the reference resonant wavelength to obtain the resonant wavelength offset.
[0080] A reference resonant wavelength needs to be preset. In this embodiment, the reference resonant wavelength refers to the measurement resonant wavelength obtained by performing step C2 at room temperature (25°C). Subsequently, the measurement resonant wavelength determined in step C2 of the current measurement cycle is subtracted from the reference resonant wavelength, and the resulting difference is the resonant wavelength offset.
[0081] In an optional implementation, the resonant wavelength offset extracted in step S500 can also be obtained by cross-correlation analysis. This method performs cross-correlation calculation between the spectrum of the linearly polarized light obtained by the current measurement and the pre-stored reference spectrum. By calculating the correlation coefficient of the two spectral signals under different wavelength offsets and finding the global maximum value point of the correlation coefficient, the wavelength offset that makes the two spectra match the most is directly determined. This offset is the resonant wavelength offset.
[0082] In this embodiment of the application, the step of determining the true temperature of the device under test based on the resonant wavelength offset in step S500 includes D1~D2:
[0083] D1. Divide the resonant wavelength offset by the temperature sensitivity coefficient preset in the production fiber model to obtain the temperature change of the device under test.
[0084] Divide the resonant wavelength offset by the temperature sensitivity coefficient preset in the production fiber model obtained through simulation optimization in step S100. This temperature sensitivity coefficient has been determined in the model optimization stage of step B2. Its physical meaning is the amount of resonant wavelength change caused by a unit temperature change. The temperature change from the reference temperature state to the current measurement state can be directly calculated through division.
[0085] D2. Calculate the sum of the temperature change and the preset reference temperature to obtain the true temperature of the device under test.
[0086] The temperature change is algebraically summed with a preset reference temperature. In this embodiment, the preset reference temperature is 25°C, which corresponds to the reference resonant wavelength measured in step C3. Through summation, the true temperature of the device under test is finally obtained.
[0087] In an optional implementation, the determination of the true temperature of the device under test based on the resonant wavelength offset in step S500 can also be achieved using a polynomial regression temperature calculation method. First, a high-order mathematical relationship between the resonant wavelength offset and the temperature change is established through experimental calibration: the corresponding resonant wavelength offset is measured at multiple known temperature points, such as 0℃, 25℃, 50℃, 75℃, and 100℃, to obtain a set of calibration data; then, the least squares method is used to perform second-order polynomial fitting on these data points to obtain the fitting curve of the resonant wavelength offset and the temperature change and its polynomial coefficients; during actual measurement, the resonant wavelength offset obtained in step C3 is substituted into the polynomial equation to calculate the temperature change of the device under test, and then added to the preset reference temperature to obtain the true temperature.
[0088] In summary, the dual-beam design and calibration mechanism overcomes the signal attenuation problem, improving monitoring accuracy and long-term reliability. By decomposing the laser beam into a signal beam and a reference beam, and using the intensity of the reference beam to calibrate the spectrum of linearly polarized light, it is possible to compensate for general signal attenuation caused by factors such as laser source power fluctuations and connector losses. This ensures accurate extraction of the true resonant wavelength offset from complex background noise, solving the problem of measurement inaccuracies caused by signal quality degradation after long-distance transmission. Furthermore, by constructing a fiber optic theoretical model and using the controlled variable method to optimize and iterate the model, ensuring that it meets the plasma resonance condition and conducting performance evaluation, a production fiber optic model specifically for substation temperature monitoring is obtained. This process enables the final sensing module to have a preset, optimal temperature sensitivity coefficient, guaranteeing the accuracy and reliability of the monitoring method from the source and overcoming the limitations of existing technologies that lack targeted model guidance.
[0089] Example 3 illustrates a schematic scheme for a temperature monitoring method in a weakly coupled few-mode photonic crystal fiber optic substation. It should be noted that the technical solution of this weakly coupled few-mode photonic crystal fiber optic substation temperature monitoring system belongs to the same concept as the aforementioned weakly coupled few-mode photonic crystal fiber optic substation temperature monitoring method. Details not described in detail in this embodiment can be found in the description of the aforementioned weakly coupled few-mode photonic crystal fiber optic substation temperature monitoring method.
[0090] This embodiment also provides a weakly coupled few-mode photonic crystal fiber optic substation temperature monitoring system, including:
[0091] Light source module: used to generate laser beams;
[0092] Beam splitter module: used to decompose the received laser beam into a signal beam and a reference beam;
[0093] Polarization processing and beam acquisition module: used to polarize the signal beam to obtain linearly polarized light, and to acquire the intensity of the reference beam;
[0094] Sensing module: used to receive linearly polarized light and convert the temperature change of the device under test into a resonant wavelength offset output;
[0095] Signal acquisition and processing module: used to acquire the spectrum of linearly polarized light and calculate the spectral intensity. By processing the spectral intensity and the intensity of the reference beam, the resonant wavelength offset is calculated, and the true temperature of the device under test is determined based on the resonant wavelength offset.
[0096] In this embodiment, the sensing module includes a substrate 1; the substrate 1 has an analyte channel 2, a pre-coated hole 3, and an air hole 4 respectively; the substrate 1 is made of silicon dioxide, the inner surface of the pre-coated hole 3 is coated with a metal layer, and the air holes 4 are arranged in a periodic pattern.
[0097] The sensing module, which is the physical embodiment of the fiber optic model, is the core sensitive unit of the entire monitoring system. The main body of the sensing module is a substrate 1 made of silicon dioxide. Silicon dioxide not only has optical transmittance and thermal stability, but can also withstand the high temperature and electromagnetic interference in the substation environment.
[0098] The analyte channel 2 serves as the flow and filling channel for the analyte medium, directly contacting the insulating medium of the device under test. In this embodiment, an immersion method can be used, immersing the analyte channel 2 of the sensing module into the device's oil tank, ensuring full contact between the analyte channel 2 and the oil in the tank. Temperature changes cause a change in refractive index through the thermo-optical effect of the oil, thereby monitoring the device temperature. Alternatively, a filling method can be used, filling the analyte channel 2 with a temperature-sensitive material. Temperature changes will cause a change in the refractive index of the temperature-sensitive material, thereby monitoring the room temperature.
[0099] The metal layer coated on the inner surface of the pre-coated hole 3 is a key structure for exciting the surface plasmon resonance effect. When light energy of a specific wavelength is coupled to this point, it will excite an oscillating electron cloud, i.e., a surface plasmon wave, at the metal-medium interface. In this embodiment, silver is selected as the metal coating on the inner surface of the pre-coated hole 3. Compared with other metals, silver can produce a sharper and stronger surface plasmon resonance effect in the visible and near-infrared bands. This means that when the refractive index changes slightly due to temperature, the resonance wavelength will produce a larger shift, i.e., higher wavelength sensitivity, thereby improving the accuracy of temperature measurement.
[0100] The periodic arrangement of the air holes 4 constitutes the waveguide structure unique to photonic crystal fibers. In this embodiment, a hexagonal lattice arrangement is used. This regular periodic structure can generate a photonic bandgap effect, thereby strictly confining the transmitted linearly polarized light to the fiber core region and greatly reducing transmission loss. More importantly, this structure can modulate the energy distribution of the light field, causing it to extend more outward from the fiber core, thus overlapping with the metal layer of the pre-coated holes 3, providing crucial phase-matching conditions for exciting surface plasmon resonance.
[0101] This embodiment also provides an electronic device suitable for temperature monitoring in weakly coupled few-mode photonic crystal fiber substations, comprising: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the temperature monitoring method for weakly coupled few-mode photonic crystal fiber substations as proposed in the above embodiment.
[0102] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements the method for monitoring temperature in a weakly coupled few-mode photonic crystal fiber substation as proposed in the above embodiments.
[0103] The storage medium proposed in this embodiment belongs to the same inventive concept as the method for realizing weakly coupled few-mode photonic crystal fiber substation temperature monitoring proposed in the above embodiments. Technical details not described in detail in this embodiment can be found in the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.
[0104] Based on the above description of the implementation methods, those skilled in the art can clearly understand that the present invention can be implemented using software and necessary general-purpose hardware, and of course, it can also be implemented using hardware. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as a computer floppy disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk, or optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of the various embodiments of the present invention.
[0105] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.
Claims
1. A method for temperature monitoring in a weakly coupled few-mode photonic crystal fiber substation, characterized in that, include: A theoretical model of optical fiber was constructed. The refractive index and spatial position of the device under test were changed by controlling the variable method to evaluate the performance index of the optical fiber theoretical model and obtain the production optical fiber model. A laser beam is generated, and the laser beam reaches an optical coupler through a single-mode optical fiber; The laser beam is decomposed into a signal beam and a reference beam by the optical coupler. The signal beam is polarized to obtain linearly polarized light, and the intensity of the reference beam is collected. The linearly polarized light is coupled to the production fiber model, and the spectrum of the linearly polarized light output by the production fiber model is collected. The spectrum of the linearly polarized light is calibrated based on the intensity of the reference beam, and the resonant wavelength offset is extracted from the calibrated spectrum. The true temperature of the device under test is determined based on the resonant wavelength offset.
2. The method for temperature monitoring in a weakly coupled few-mode photonic crystal fiber substation as described in claim 1, characterized in that, The steps for constructing a theoretical model of optical fiber include: A geometric model is established based on a preset photonic crystal fiber cross-sectional topology, and corresponding material properties are assigned to different regions of the geometric model. The geometric model is subjected to optimization iteration to obtain the optical fiber theoretical model; The steps for optimizing the iterative process include: Define one or more geometric parameters to be optimized and their value ranges; Calculate whether the geometric model satisfies the plasma resonance condition based on the geometric parameters. The plasma resonance condition is expressed as: the real part of the effective refractive index of the conduction mode is equal to the real part of the effective refractive index of the surface plasmon mode. When the plasma resonance condition is met, the optical fiber theoretical model is obtained. When the plasma resonance condition is not met, the range of values for the geometric parameters is changed, and the geometric model is recalculated to determine whether the plasma resonance condition is met.
3. The method for temperature monitoring in a weakly coupled few-mode photonic crystal fiber substation as described in claim 2, characterized in that, The steps to obtain the production fiber model include: The optimal parameters are obtained by calculating the loss spectrum of the optical fiber theoretical model by changing the geometric parameters. Based on the preferred parameters, the refractive index of the device under test is changed, and the performance index of the optical fiber theoretical model is calculated. Based on the preferred parameters, the spatial position of the device under test is changed, and the impact on the performance indicators is evaluated to obtain the evaluation results. When the evaluation results meet the preset stability, the production fiber model is obtained based on the preferred parameters.
4. The method for temperature monitoring in a weakly coupled few-mode photonic crystal fiber substation as described in claim 3, characterized in that, The steps for polarizing the signal beam include: Guide the signal beam into the polarizer; The polarizer filters and converts the polarization of the unpolarized signal beam to obtain linearly polarized light.
5. The method for temperature monitoring in a weakly coupled few-mode photonic crystal fiber substation as described in claim 4, characterized in that, The steps for extracting the resonant wavelength shift include: The spectral intensity is obtained by measuring the spectrum of the linearly polarized light, and the ratio of the spectral intensity to the intensity of the reference beam is calculated as the calibrated spectral intensity. The calibrated spectrum is then generated using the calibrated spectral intensity. In the calibrated spectrum, the characteristic loss peak caused by the surface plasmon resonance effect excited by the production fiber model is identified, and the center wavelength corresponding to the characteristic loss peak is determined as the measurement resonance wavelength. A reference resonant wavelength is preset, and the difference between the measured resonant wavelength and the reference resonant wavelength is calculated to obtain the resonant wavelength offset.
6. The method for temperature monitoring in a weakly coupled few-mode photonic crystal fiber substation as described in claim 5, characterized in that, The steps for determining the true temperature of the device under test based on the resonant wavelength offset include: Divide the resonant wavelength offset by the temperature sensitivity coefficient preset in the production fiber model to obtain the temperature change of the device under test. The sum of the temperature change and the preset reference temperature is calculated to obtain the true temperature of the device under test.
7. A weakly coupled few-mode photonic crystal fiber substation temperature monitoring system, employing the method described in any one of claims 1-6, characterized in that, include: Light source module: used to generate laser beams; Beam splitter module: used to decompose the received laser beam into a signal beam and a reference beam; Polarization processing and beam acquisition module: used to polarize the signal beam to obtain linearly polarized light, and to acquire the intensity of the reference beam; Sensing module: used to receive the linearly polarized light and convert the temperature change of the device under test into a resonant wavelength offset output; Signal acquisition and processing module: used to acquire the spectrum of the linearly polarized light and calculate the spectral intensity, process the spectral intensity and the intensity of the reference beam to calculate the resonant wavelength offset, and determine the true temperature of the device under test based on the resonant wavelength offset.
8. The method for temperature monitoring in a weakly coupled few-mode photonic crystal fiber substation as described in claim 7, characterized in that, The sensing module includes: Matrix (1); The substrate (1) has an analytical channel (2), a pre-coating hole (3) and an air hole (4) respectively. The substrate (1) is made of silicon dioxide, the inner surface of the pre-coated holes (3) is coated with a metal layer, and the air holes (4) are arranged in a periodic pattern.
9. An electronic device, comprising: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, they implement the steps of the weakly coupled few-mode photonic crystal fiber substation temperature monitoring method according to any one of claims 1 to 7.
10. A computer-readable storage medium storing computer-executable instructions that, when executed by a processor, implement the steps of the weakly coupled few-mode photonic crystal fiber substation temperature monitoring method according to any one of claims 1 to 7.