Power transmission line state evaluation method and device, and optical fiber sensing system

Abstract

The invention relates to a power transmission line state evaluation method and device and an optical fiber sensing system. The method comprises the following steps: acquiring an optical signal to be measured of a sensing optical fiber in the optical fiber sensing system; the to-be-measured optical signal is an optical signal obtained under the action of a to-be-measured power transmission line after the optical fiber sensing system modulates and enhances a target optical signal and transmits the target optical signal to the sensing optical fiber; the target optical signal is an optical signal which minimizes the negative influence of a nonlinear effect on the sensing performance of the sensing optical fiber; performing photoelectric conversion processing on the to-be-detected optical signal to obtain state data of the to-be-detected power transmission line; and according to the state data and a preset state evaluation model, obtaining a state evaluation result of the to-be-tested power transmission line. The method can realize long-distance sensing and improve the accuracy of a state evaluation result of the power transmission line.

Description

Technical Field

[0001] The present application relates to the technical field of transmission line condition assessment, and particularly to a transmission line condition assessment method and device, and an optical fiber sensing system. Background Art

[0002] As an important part of the power system, transmission lines are responsible for safely and reliably transporting electric energy from power plants to the power grid, and their operating quality directly affects the integrity of the entire power system and is crucial for protection. Over time, transmission lines degrade due to the influence of the external environment and their own aging, forming defects. If not dealt with in time, they may evolve into faults, posing a serious threat to the safe operation of the power system.

[0003] In related technologies, the status of transmission lines is usually detected by using thermistors, temperature-sensitive cables, infrared monitoring, etc. However, the above conventional sensors have problems such as difficulty in long-distance layout, corrosion intolerance, and susceptibility to electromagnetic interference. The accuracy of the status assessment results of transmission lines obtained based on conventional sensors is relatively low. Summary of the Invention

[0004] Based on this, in view of the above technical problems, it is necessary to provide a transmission line condition assessment method and device, and an optical fiber sensing system that can achieve long-distance sensing and improve the accuracy of transmission line condition assessment results.

[0005] In a first aspect, the present application provides a transmission line condition assessment method, which is applied to an optical fiber sensing system. The method includes:

[0006] Obtain a measured optical signal of a sensing optical fiber in the optical fiber sensing system; the measured optical signal is an optical signal obtained after the optical fiber sensing system modulates and enhances a target optical signal, transmits it to the sensing optical fiber, and then under the action of a transmission line to be measured; the target optical signal is an optical signal that minimizes the negative impact of non-linear effects on the sensing performance of the sensing optical fiber;

[0007] Perform photoelectric conversion processing on the measured optical signal to obtain the status data of the transmission line to be measured;

[0008] According to the status data and a preset status assessment model, obtain a status assessment result of the transmission line to be measured.

[0009] In one of the embodiments, the method for determining the target optical signal includes:

[0010] Obtain multiple groups of candidate light source information, where the candidate light source information includes light source pulse waveform information and candidate peak power information;

[0011] Controlling the fiber optic sensing system to output candidate optical signals to the initial node of the sensing optical fiber according to each of the candidate light source information respectively;

[0012] Determining the non - linear index of the sensing optical fiber according to each of the candidate light source information and a preset wave coupling formula respectively;

[0013] Determining the target light source information from each of the candidate light source information according to the non - linear index corresponding to each candidate light source information;

[0014] Determining the candidate optical signal corresponding to the target light source information as the target optical signal.

[0015] In one embodiment, determining the non - linear index of the sensing optical fiber according to the candidate light source information and a preset wave coupling formula includes:

[0016] Determining the complex amplitude of the pump light at each node according to the candidate peak power information, the preset fiber loss coefficient, the preset Raman gain coefficient, the preset pump light loss coefficient, and the distance information between each preset node on the sensing optical fiber and the initial node;

[0017] Determining the complex amplitude of the Stokes light at each node on the sensing optical fiber according to the complex amplitude of the pump light at each node, the preset vacuum permittivity, the preset amplitude of the change in polarizability, and the preset proportionality constant;

[0018] Calculating the non - linear index at each node on the sensing optical fiber according to the complex amplitude of the pump light at each node, the complex amplitude of the Stokes light at each node, and a preset wave coupling equation.

[0019] In one embodiment, the determining the complex amplitude of the pump light at each node according to the candidate peak power information, the preset fiber loss coefficient, the preset Raman gain coefficient, the preset pump light loss coefficient, and the distance information between each preset node on the sensing optical fiber and the initial node includes:

[0020] Determining the power of the candidate optical signal at each node on the sensing optical fiber according to the candidate peak power information, the preset fiber loss coefficient, and the preset Raman gain coefficient;

[0021] Determining the power of the pump light at each node on the sensing optical fiber according to the power of the candidate optical signal at each node, the preset Raman gain coefficient, the preset pump light loss coefficient, and the distance information between each preset node and the initial node;

[0022] Determining the complex amplitude of the pump light at each node according to the power of the pump light at each node.

[0023] In a second aspect, the present application provides a fiber optic sensing system, and the system includes: a sensing optical fiber, a light source assembly, a modulation assembly, and a detection assembly;

[0024] Among them, the light source component is used to output a target optical signal; the modulation component is respectively connected to the light source component and the sensing optical fiber, and is used to modulate and enhance the target optical signal, and input the target optical signal after modulation and enhancement processing into the sensing optical fiber; the sensing optical fiber is used to output a measured optical signal based on the target optical signal under the action of the transmission line to be measured; the detection component is connected to the sensing optical fiber, and is used to obtain the measured optical signal in the sensing optical fiber, obtain the state data of the transmission line to be measured according to the measured optical signal, and obtain the state evaluation result of the transmission line to be measured according to the state data and a preset state evaluation model.

[0025] In one embodiment, the modulation component includes:

[0026] The first modulation unit is respectively connected to the light source component and the sensing optical fiber, and is used to receive the target optical signal, perform pulse modulation processing on the target optical signal, and perform enhancement processing on the target optical signal after the pulse modulation processing, and output a first target optical signal;

[0027] The second modulation unit is respectively connected to the light source component and the sensing optical fiber, and is used to receive the target optical signal, perform double-sideband modulation processing on the target optical signal, and output a second target optical signal;

[0028] Among them, the first target optical signal and the second target optical signal converge in the sensing optical fiber and are converted into a measured optical signal under the action of the transmission line to be measured.

[0029] In one embodiment, the first modulation unit includes:

[0030] The first modulation subunit is connected to the light source component, and is used to output an electrical pulse signal to perform pulse modulation on the target optical signal according to the electrical pulse signal;

[0031] The signal enhancement subunit is used to output a pump optical signal;

[0032] The first multiplexer is respectively connected to the first modulation subunit, the signal enhancement subunit and the sensing optical fiber, and is used to perform coupling processing on the pump optical signal and the target optical signal after pulse modulation, so that the pump optical signal performs enhancement processing on the target optical signal, generate a first target optical signal, and input the pump optical signal and the first target optical signal into the sensing optical fiber.

[0033] In one embodiment, the second modulation unit includes:

[0034] A second modulation subunit, connected to the light source component, for providing a radio frequency signal and performing double-sideband modulation on a target optical signal according to the radio frequency signal;

[0035] A filtering subunit, respectively connected to the second modulation subunit and the sensing optical fiber, for filtering and polarization processing the target optical signal that has undergone double-sideband modulation, generating a second target optical signal, and inputting the second target optical signal into the sensing optical fiber.

[0036] In one embodiment, the detection component includes:

[0037] A second multiplexer, connected to the sensing optical fiber, for receiving the optical signal to be measured and performing decoupling processing on the optical signal to be measured, extracting a target optical signal to be measured with the same wavelength as the target optical signal in the optical signal to be measured;

[0038] A photoelectric conversion unit, connected to the second multiplexer, for obtaining state data of the power transmission line to be measured according to the target optical signal to be measured;

[0039] An evaluation unit, connected to the photoelectric conversion unit, for obtaining a state evaluation result of the power transmission line to be measured according to the state data and a preset state evaluation model.

[0040] In a third aspect, the present application provides a power transmission line state evaluation device, applied to an optical fiber sensing system, the device includes:

[0041] An acquisition module, for acquiring an optical signal to be measured of a sensing optical fiber in the optical fiber sensing system; the optical signal to be measured is an optical signal obtained after the optical fiber sensing system modulates and enhances a target optical signal and transmits it to the sensing optical fiber and then under the action of the power transmission line to be measured; the target optical signal is an optical signal that minimizes the negative impact of non-linear effects on the sensing performance of the sensing optical fiber;

[0042] A conversion module, for performing photoelectric conversion processing on the optical signal to be measured to obtain state data of the power transmission line to be measured;

[0043] An evaluation module, for obtaining a state evaluation result of the power transmission line to be measured according to the state data and a preset state evaluation model.

[0044] The above-mentioned transmission line status evaluation method, optical fiber sensing system, and transmission line status evaluation device are applied to an optical fiber sensing system. The sensing optical fiber in the optical fiber sensing system is laid together with the transmission line to be measured. The optical fiber sensing system can generate a target optical signal that minimizes the negative impact of the nonlinear effect on the sensing performance of the sensing optical fiber, and performs modulation and enhancement processing on the target optical signal and then transmits it to the sensing optical fiber. The target optical signal after modulation and enhancement processing can achieve long-distance transmission in the sensing optical fiber. And under the influence of the transmission line to be measured, the target optical signal transmitted in the sensing optical fiber will change, generating a measured optical signal carrying information of the transmission line to be measured. The optical fiber sensing system can acquire the measured optical signal and perform optoelectronic conversion processing on the measured optical signal, analyze and obtain the status data of the transmission line to be measured, and then input the status data of the transmission line to be measured into a preset status evaluation model, and the accurate status evaluation result of the transmission line to be measured can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present application or in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0046] Figure 1 It is a schematic structural diagram of an optical fiber sensing system in an embodiment;

[0047] Figure 2 It is a schematic structural diagram of an optical fiber sensing system in another embodiment;

[0048] Figure 3 It is a schematic structural diagram of an optical fiber sensing system in still another embodiment;

[0049] Figure 4 It is a schematic flowchart of a transmission line status evaluation method in an embodiment;

[0050] Figure 5 It is a schematic flowchart of a method for determining a target optical signal in an embodiment;

[0051] Figure 6 It is a schematic flowchart of S503 in an embodiment;

[0052] Figure 7 It is a schematic flowchart of S601 in an embodiment;

[0053] Figure 8 It is a structural block diagram of a transmission line status evaluation device in an embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0054] To facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant drawings. Embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used in the specification of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0056] It can be understood that the terms "first", "second", etc. used in this application can be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element.

[0057] Spatial relationship terms such as "under", "below", "beneath", "underneath", "above", "over", etc. can be used herein to describe the relationship of one element or feature shown in the drawings with other elements or features. It should be understood that, in addition to the orientation shown in the drawings, spatial relationship terms also include different orientations of the device during use and operation. For example, if the device in the drawing is flipped, an element or feature described as "under other elements" or "beneath it" or "under it" will be oriented "above" other elements or features. Therefore, the exemplary terms "under" and "below" can include both the upper and lower orientations. In addition, the device can also include additional orientations (such as rotating 90 degrees or other orientations), and the spatial descriptive terms used herein are accordingly interpreted.

[0058] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intermediate element. In addition, "connection" in the following embodiments should be understood as "electrical connection", "communication connection", etc. if there is a transmission of electrical signals or data between the connected objects.

[0059] As used herein, the singular forms "a", "an" and "the" may also include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprise / include" or "have" etc. specify the presence of the stated features, wholes, steps, operations, components, parts or combinations thereof, but do not preclude the presence or addition of one or more other features, wholes, steps, operations, components, parts or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the related listed items.

[0060] In an exemplary embodiment, refer to Figure 1 , the present application provides an optical fiber sensing system, which includes a sensing optical fiber 1, a light source component 2, a modulation component 3, and a detection component 4.

[0061] The light source component 2 is used to output a target optical signal. The modulation component 3 is respectively connected to the light source component 2 and the sensing optical fiber 1, and is used to modulate and enhance the target optical signal, and input the target optical signal after modulation and enhancement processing into the sensing optical fiber 1; the sensing optical fiber 1 is used to output a to-be-detected optical signal based on the target optical signal under the action of the to-be-detected transmission line; the detection component 4 is connected to the sensing optical fiber 1, and is used to obtain the to-be-detected optical signal in the sensing optical fiber 1, obtain the state data of the to-be-detected transmission line according to the to-be-detected optical signal, and obtain the state evaluation result of the to-be-detected transmission line according to the state data and a preset state evaluation model.

[0062] It can be understood that the sensing optical fiber 1 in the optical fiber sensing system of the present application is laid together with the to-be-detected transmission line. Among them, the light source component 2 is used to output a target optical signal to the modulation component 3 that can minimize the negative impact of the nonlinear effect on the sensing performance of the sensing optical fiber 1. After receiving the target optical signal, the modulation component 3 can perform processing such as modulation, amplification, enhancement, and filtering on the target optical signal, so that the processed target optical signal can be transmitted more stably over a long distance in the sensing optical fiber 1. Under the influence of the to-be-detected transmission line, when the optical signal is transmitted in the sensing optical fiber 1, the characteristics of the optical signal will be changed. The detection component 4 can obtain the optical signal whose characteristics are changed, that is, the to-be-detected optical signal, and perform photoelectric conversion processing on the to-be-detected optical signal. By monitoring and obtaining characteristic quantities such as the phase, light intensity, polarization state, and frequency of the to-be-detected optical signal, the state data of the to-be-detected transmission line such as the temperature, strain, and real-time oscillation frequency of the to-be-detected transmission line is sensed, and then the analyzed state data is input into a preset state evaluation model to obtain the state evaluation result of the to-be-detected transmission line. Among them, the state evaluation model can include an R-CNN (Region-based Convolutional Neural Networks) model and an RNN (Recurrent Neural Network) model. The R-CNN model is used to extract the spatial features of the transmission line state data, and the RNN model is used to obtain the temporal changes of the spatial features of each region of the transmission line according to the spatial features of the transmission line state data, and predict the state of the transmission line according to the temporal changes of the spatial features of each region of the transmission line.

[0063] In the above optical fiber sensing system, the sensing optical fiber is laid together with the power transmission line to be measured. The optical fiber sensing system can generate a target optical signal that minimizes the negative impact of the nonlinear effect on the sensing performance of the sensing optical fiber, and modulates and enhances the target optical signal and then transmits it to the sensing optical fiber. The target optical signal after modulation and enhancement processing can be transmitted over a long distance in the sensing optical fiber. Under the influence of the power transmission line to be measured, the transmitted target optical signal in the sensing optical fiber will change, generating a measured optical signal carrying information about the power transmission line to be measured. The optical fiber sensing system can acquire the measured optical signal and perform optoelectronic conversion processing on the measured optical signal, analyze and obtain the state data of the power transmission line to be measured, and then input the state data of the power transmission line to be measured into a preset state evaluation model to obtain an accurate state evaluation result of the power transmission line to be measured.

[0064] In an exemplary embodiment, please refer to Figure 2 , the modulation component 3 includes a first modulation unit 31 and a second modulation unit 32. The light source component 2 may include a light source 21 and a coupler 22. The light source 21 can output a beam of target optical signal. After the target optical signal enters the coupler 22, it will be split into two identical target optical signals. One of the target optical signals enters the first modulation unit 31, and the other target optical signal enters the second modulation unit 32.

[0065] The first modulation unit 31 is respectively connected to the light source component 2 and the sensing optical fiber 1, and is used to receive the target optical signal, perform pulse modulation processing on the target optical signal, and perform enhancement processing on the target optical signal after pulse modulation processing, and output a first target optical signal.

[0066] The first modulation unit 31 may include: a first modulation subunit 311, a signal enhancement subunit 312, and a first multiplexer 313. The first modulation subunit 311 is connected to the light source component 1 and is used to output an electrical pulse signal to perform pulse modulation on the target optical signal according to the electrical pulse signal. The signal enhancement subunit 312 is used to output a pump optical signal. The first multiplexer 313 is respectively connected to the first modulation subunit 311, the signal enhancement subunit 312, and the sensing optical fiber 1, and is used to perform coupling processing on the pump optical signal and the pulse-modulated target optical signal, so that the pump optical signal enhances the target optical signal to generate a first target optical signal. The first target optical signal includes the pump optical signal and the modulated target optical signal, and inputs the first target optical signal into the sensing optical fiber 1.

[0067] Specifically, the first modulation subunit 311 may include a pulse signal generator, a pulse modulator, and an amplifier, and the signal enhancer subunit 312 may include a Raman pump laser. The pulse modulator is respectively connected to the pulse signal generator, the coupler, and the amplifier, and the amplifier is connected to the first multiplexer 313. The pulse signal generator can generate pulse signals with various frequencies, widths, and amplitudes to drive the pulse modulator. By adjusting the parameters of the pulse signal, precise control and optimization of the sensing system can be achieved. The pulse modulator can modulate the target optical signal into a pulsed optical signal under the action of the pulse signal output by the pulse signal generator. Then, the amplifier can amplify the modulated target optical signal. After the amplified target optical signal enters the first multiplexer, the first multiplexer can couple the target optical signal with the pump optical signal output by the Raman pump laser to generate a first target optical signal, which is then input into the sensing optical fiber 1. When the first target optical signal is transmitted in the sensing optical fiber 1, the pump optical signal can enhance and amplify the target optical signal to increase the transmission distance of the target optical signal.

[0068] The second modulation unit 32 is respectively connected to the light source assembly 2 and the sensing optical fiber 1, and is configured to receive the target optical signal, perform double-sideband modulation processing on the target optical signal, and output a second target optical signal.

[0069] The second modulation unit 32 includes a second modulation subunit 321 and a filtering subunit 322. The second modulation subunit 321 is connected to the light source assembly 1 and is configured to provide a radio frequency signal and perform double-sideband modulation on the target optical signal according to the radio frequency signal. The filtering subunit 322 is respectively connected to the second modulation subunit 321 and the sensing optical fiber 1, and is configured to filter and polarize the target optical signal that has undergone double-sideband modulation to generate a second target optical signal, and input the second target optical signal into the sensing optical fiber 1.

[0070] Exemplarily, the second modulation subunit 321 may include a double-sideband modulator and a radio frequency source. The filtering subunit 322 may include a filter, a polarization scrambler, and a vibration isolator. The double-sideband modulator is respectively connected to the radio frequency source, the coupler, and the filter. The polarization scrambler is respectively connected to the polarization scrambler and the vibration isolator. The vibration isolator is connected to the sensing optical fiber 1. The radio frequency source is used to provide a stable radio frequency signal for the double-sideband modulator or other components that require radio frequency signals. The double-sideband modulator is used to modulate the low-frequency signal onto the high-frequency carrier, so as to utilize the propagation characteristics of the high-frequency carrier to transmit the information signal to a farther distance. In the fiber optic sensing system of the present application, the double-sideband modulator helps to enhance the anti-interference ability and transmission distance of the target optical signal. The filter is used to remove the noise and clutter in the optical signal, and improve the purity and signal-to-noise ratio of the signal. The polarization scrambler is used to reduce the polarization-dependent gain and eliminate the polarization sensitivity. In optical fiber transmission, the change of the polarization state may affect the target optical signal. The polarization scrambler can randomize the polarization state of the target optical signal, which helps to reduce this influence and improve the stability of the system. The vibration isolator is used to reduce the influence of external vibration on the sensing system, which helps to ensure the stability and reliability of the system in a harsh environment.

[0071] After the two target optical signals enter the first modulation unit and the second modulation unit respectively, the first modulation unit and the second modulation unit respectively output the first target optical signal and the second target optical signal. The first target optical signal and the second target optical signal converge in the sensing optical fiber 1 and are converted into the optical signal to be measured under the action of the power transmission line to be measured.

[0072] In an exemplary embodiment, please continue to refer to Figure 2 , the detection component 4 includes a second multiplexer 41, a photoelectric conversion unit 42, and an evaluation unit 43.

[0073] The second multiplexer 41 is connected to the sensing optical fiber 1 and is used to receive the optical signal to be measured and perform decoupling processing on the optical signal to be measured to extract the target optical signal to be measured with the same wavelength as the target optical signal. The photoelectric conversion unit 42 is connected to the second multiplexer 41 and is used to obtain the state data of the power transmission line to be measured according to the target optical signal to be measured. The evaluation unit 43 is connected to the photoelectric conversion unit 42 and is used to obtain the state evaluation result of the power transmission line to be measured according to the state data and the preset state evaluation model.

[0074] In another example, please refer to Figure 3, the second multiplexer 41 and the first multiplexer 313 can be the same wavelength division multiplexer. The first modulation unit may further include a circulator 314, which is respectively connected to the amplifier, the first multiplexer 313, and the optoelectronic conversion unit, and is used to guide the transmission path of the optical signal in the system to ensure that the optical signal is transmitted in the optical fiber in a predetermined direction, avoiding signal interference and loss. In an exemplary embodiment, please refer to Figure 4 , this application provides a method for evaluating the state of a power transmission line, which is applied to an optical fiber sensing system. The method includes steps S401 to S403.

[0075] S401: Obtain the optical signal to be measured of the sensing optical fiber in the optical fiber sensing system.

[0076] Wherein, the optical signal to be measured is the optical signal obtained after the optical fiber sensing system modulates and enhances the target optical signal and transmits it to the sensing optical fiber, and then under the action of the power transmission line to be measured; the target optical signal is the optical signal that minimizes the negative impact of the nonlinear effect on the sensing performance of the sensing optical fiber.

[0077] It can be understood that the method for evaluating the state of the power transmission line in this application can be applied to an optical fiber sensing system such as Figure 2 or Figure 3 shown. First, the light source 21 can output a beam of target optical signal. After the target optical signal enters the coupler 22, it will be divided into two identical target optical signals. One of the target optical signals enters the pulse modulator, and after passing through the amplifier, circulator, and first multiplexer, a first target optical signal is generated and enters the sensing optical fiber. The other target optical signal enters the double-sideband modulator, and after passing through the filter, polarization scrambler, and vibration isolator, a second target optical signal is generated and enters the optical fiber to be measured. The first target optical signal and the second target optical signal converge in the sensing optical fiber and are jointly transmitted in the sensing optical fiber, and are converted into the optical signal to be measured under the action of the power transmission line to be measured. The detection component of the optical fiber sensing system can obtain the optical signal to be measured and perform decoupling processing on the optical signal to be measured to extract the part of the optical signal to be measured that carries the information of the power transmission line to be measured.

[0078] S402: Perform optoelectronic conversion processing on the optical signal to be measured to obtain the state data of the power transmission line to be measured.

[0079] After extracting the part of the optical signal to be measured that carries the information of the power transmission line to be measured, the optoelectronic conversion unit in the detection component can perform optoelectronic conversion processing on this part of the optical signal, and according to the characteristic quantities such as the phase, light intensity, polarization state, and frequency of this part of the optical signal, obtain the state data of the power transmission line to be measured, such as the temperature, strain, and real-time oscillation frequency of the power transmission line to be measured.

[0080] S403: Obtain the state evaluation result of the power transmission line to be measured according to the state data and the preset state evaluation model.

[0081] After that, the detection component can input the obtained status data into a pre-constructed status evaluation model, and obtain the status evaluation result of the transmission line to be measured through the analysis of the status evaluation model. Among them, the status evaluation model can include an R-CNN (Region-based Convolutional Neural Networks) model and an RNN (Recurrent Neural Network) model.

[0082] The above-mentioned transmission line status evaluation method is applied to an optical fiber sensing system. The sensing optical fiber in the optical fiber sensing system is laid together with the transmission line to be measured. The optical fiber sensing system can generate a target optical signal that minimizes the negative impact of the nonlinear effect on the sensing performance of the sensing optical fiber, and perform modulation and enhancement processing on the target optical signal and then transmit it to the sensing optical fiber. The target optical signal after modulation and enhancement processing can be transmitted over a long distance in the sensing optical fiber. And under the influence of the transmission line to be measured, the target optical signal transmitted therein will change, generating a to-be-measured optical signal carrying the information of the transmission line to be measured. The optical fiber sensing system can acquire the to-be-measured optical signal and perform optoelectronic conversion processing on the to-be-measured optical signal, analyze and obtain the status data of the transmission line to be measured, and then input the status data of the transmission line to be measured into a preset status evaluation model, and then the accurate status evaluation result of the transmission line to be measured can be obtained.

[0083] In an exemplary embodiment, the method for determining the target optical signal includes steps S501 to S505.

[0084] S501: Obtain multiple groups of candidate light source information, where the candidate light source information includes light source pulse waveform information and candidate peak power information.

[0085] In application, in order to minimize the negative impact of the nonlinear effect on the sensing performance of the sensing optical fiber 1, multiple groups of candidate light source information can be preset, and the optical fiber sensing system is controlled to output candidate optical signals to the sensing optical fiber respectively according to each group of candidate light source information, and the nonlinear indexes of the sensing optical fiber are respectively detected when different optical signals are output by the light source, and the optical signal corresponding to the smallest nonlinear index is determined as the target optical signal.

[0086] S502: Control the optical fiber sensing system to output candidate optical signals to the initial node of the sensing optical fiber respectively according to each group of candidate light source information.

[0087] It can be understood that the light source generates each initial optical signal according to each light source pulse waveform information and each candidate peak power information respectively. The initial optical signal is divided into two beams by a coupler and enters the first modulation unit and the second modulation unit respectively, converges at the initial node of the sensing optical fiber to form a candidate optical signal, and enters the sensing optical fiber.

[0088] S503: Determine the nonlinear index of the sensing optical fiber according to each candidate light source information and the preset wave coupling formula respectively.

[0089] When the candidate light source information of the initial optical signal output by the light source is determined, the wave coupling formula can be solved with the goal of minimizing the negative impact of the nonlinear effect in the sensing optical fiber on the sensing performance. The expression of the wave coupling formula can be as shown in formula (1):

[0090]

[0091] Among them, is the propagation distance of light in the optical fiber, is the propagation distance the complex amplitude of the pump light at, is the partial derivative symbol, c is the speed of light in vacuum, is the refractive index of the optical fiber, is at the propagation distance the time at, is the loss coefficient of the optical fiber, is the imaginary unit, is the nonlinear coefficient, is the propagation distance the complex amplitude of the Stokes light at, and are both coupling coefficients, is the difference symbol, is the material density of the optical fiber core, is the complex conjugate symbol, is the Brillouin frequency shift, is the Brillouin linewidth, is the effective area of the optical fiber.

[0092] S504: Determine the target light source information from each candidate light source information according to the nonlinear index corresponding to each candidate light source information.

[0093] Exemplarily, the wave coupling formula can be discretized in space and time, that is, the length of the sensing optical fiber is divided into small segments, or the propagation time of the candidate optical signal in the sensing optical fiber is divided into small segments. The original wave coupling formula is continuous, and the discretized wave coupling formula is the equation at each discrete point. For the discretized wave coupling formula, the SSFM split-step Fourier transform method can be used to relate the time domain and the frequency domain by Fourier transform, and the propagation process of the candidate optical signal in the sensing optical fiber is divided into a linear part and a nonlinear part for separate processing.

[0094] Specifically, using the selected numerical calculation method, according to the candidate light source information corresponding to the initial optical signal, iterative calculation is performed on the discretized wave coupling formula. In each step of the calculation, the values of the optical field at each discrete node are updated. During the simulation process, an objective function can be defined with the goal of minimizing the negative impact of the nonlinear effect on the sensing performance. Calculate the indexes related to the nonlinear effect, such as the nonlinear phase shift, self-phase modulation (SPM), cross-phase modulation (XPM), etc. These nonlinear indexes can reflect the degree of influence of the nonlinear effect on the optical field. For example, the sum of the nonlinear phase shifts or the intensity of the nonlinear effect at a certain key position can be used as the objective function, and the goal is to minimize the value of this function.

[0095] S505: Determine the candidate optical signal corresponding to the target light source information as the target optical signal.

[0096] In the application, a suitable optimization algorithm (such as the gradient descent method, genetic algorithm, particle swarm optimization algorithm, etc.) can also be selected to search for the target light source information from each candidate light source information, and determine the candidate optical signal corresponding to the target light source information as the target optical signal.

[0097] In an exemplary embodiment, determining the nonlinear index of the sensing optical fiber according to the candidate light source information and the preset wave coupling formula in step S503 includes steps S601 to S603.

[0098] S601: Determine the complex amplitude of the pump light at each node according to the candidate peak power information, the preset fiber loss coefficient, the preset Raman gain coefficient, the preset pump light loss coefficient, and the distance information between each preset node and the initial node on the sensing optical fiber.

[0099] In this embodiment, before calculating the nonlinear index according to the wave coupling formula, it is necessary to first determine the parameters and . Exemplarily, according to the candidate peak power information of the initial optical signal, the preset fiber loss coefficient , determine the complex amplitude of the pump light at each node based on the preset Raman gain coefficient, the preset pump light loss coefficient, and the distance information z between each preset node on the sensing optical fiber and the initial node.

[0100] S602: Determine the complex amplitude of the Stokes light at each node on the sensing optical fiber according to the complex amplitude of the pump light at each node, the preset vacuum permittivity, the preset amplitude change of the polarizability, and the preset proportionality constant.

[0101] After determining the complex amplitude of the pump light at each node on the sensing optical fiber, the complex amplitude of the Stokes light at each node on the sensing optical fiber can be further determined according to the preset vacuum permittivity, the preset amplitude change of the polarizability, and the preset proportionality constant.

[0102] S603: Calculate the nonlinear index at each node on the sensing optical fiber according to the complex amplitude of the pump light at each node, the complex amplitude of the Stokes light at each node, and the preset wave coupling equation.

[0103] In application, the propagation distance of the candidate optical signal between the initial node of the sensing optical fiber and the remaining nodes , the speed of light in vacuum c, the refractive index n of the sensing optical fiber, the time of the candidate signal light to the propagation distance z, the loss coefficient of the sensing optical fiber , the nonlinear coefficient , the coupling coefficient and , the material density of the core of the sensing optical fiber , the Brillouin frequency shift , the Brillouin linewidth , the effective area of the optical fiber , are all known parameters. After obtaining the complex amplitude of the pump light at each node and the complex amplitude of the Stokes light at each node , it can be substituted into the wave coupling formula to solve the nonlinear index at each node on the sensing optical fiber.

[0104] In an exemplary embodiment, step S601, determining the complex amplitude of the pump light at each node according to the candidate peak power information, the preset optical fiber loss coefficient, the preset Raman gain coefficient, the preset pump light loss coefficient, and the distance information between each preset node on the sensing optical fiber and the initial node, includes steps S701 to S703.

[0105] S701: Determine the power of the candidate optical signal at each node on the sensing optical fiber according to the candidate peak power information, the preset optical fiber loss coefficient, and the preset Raman gain coefficient.

[0106] The evolution equation of the pump light in the Raman pump laser can be shown as formula (2):

[0107]

[0108] Among them, is the pump light power at the propagation distance z; is the partial derivative symbol; is the propagation distance of light in the optical fiber; is the loss coefficient of the pump light; is the Raman gain coefficient; is the power of the candidate optical signal at the propagation distance z. When determining the complex amplitude of the pump light at each node on the sensing optical fiber, it is first necessary to determine the power of the candidate optical signal at each node on the sensing optical fiber. Specifically, the power of the candidate optical signal at each node on the sensing optical fiber can be calculated according to parameters such as the candidate peak power information of the candidate optical signal, the preset optical fiber loss coefficient, and the preset Raman gain coefficient.

[0109] S702: Determine the power of the pump light at each node on the sensing optical fiber according to the power of the candidate optical signal at each node, the preset Raman gain coefficient, the preset pump light loss coefficient, and the preset distance information between each node and the initial node.

[0110] After obtaining the power of the candidate optical signal at each node on the sensing optical fiber, the power of the pump light at the propagation distance z can be calculated and determined by substituting into the evolution equation of the pump light according to the power of the candidate optical signal at each node, the preset Raman gain coefficient, the preset pump light loss coefficient, and the preset distance information between each node and the initial node.

[0111] S703: Determine the complex amplitude of the pump light at each node according to the power of the pump light at each node.

[0112] Finally, the complex amplitude of the pump light at each node can be determined according to the power of the pump light at each node.

[0113] In an exemplary embodiment, the transmission line state evaluation of the present application further includes obtaining detailed indicators of all working conditions of the transmission line to be measured, and using the principal component analysis method to extract the main parameters from the detailed indicators of each working condition of the transmission line to be measured, obtaining a set of transmission line state evaluation parameters for the transmission line to be measured. Then, using the optical fiber sensing system of the present application, obtain the working conditions of the transmission line to be measured for a period of time and the parameter values of the main parameters corresponding to the working conditions of the transmission line to be measured in the set of transmission line state evaluation parameters. Then, use the obtained working conditions of the transmission line to be measured for the period of time and the parameter values of the main parameters corresponding to the working conditions of the transmission line to be measured in the set of transmission line state evaluation parameters to train the state evaluation model to be trained, and obtain a trained deep learning model as the state evaluation model of the transmission line to be measured.

[0114] Among them, the health monitoring of transmission lines is a necessary condition to ensure their operational integrity, mainly including eight units such as utility poles, conductors, hardware, foundations, insulators, grounding devices, and corridor environments, as well as ancillary facilities as comprehensive assessment indicators. A working condition evaluation parameter system is constructed from the detailed indicators of each unit, resulting in a total of 103 working condition quantities. Defects in the actual operation and maintenance of transmission lines all have corresponding characteristic quantities. To accurately evaluate their operating status, it is necessary to select the most representative status quantities and establish a comprehensive and reasonable transmission line status evaluation system. Drawing on the effectiveness of evaluation criteria and the accuracy of evaluation results, streamline and standardize the parameter system, and construct a transmission line status evaluation parameter set to ensure the comprehensiveness of evaluation parameters.

[0115] In this embodiment, the fiber optic sensing system is combined with the deep neural network model to achieve instantaneous evaluation of the transmission line status. First, use the fiber optic sensing system to collect transmission line status data, and then use the status evaluation model to analyze the data, extract key features, and evaluate the transmission line status. In application, data deep learning can be applied under natural environmental conditions, and data deep learning and model optimization are performed once a week. Finally, an event perception model and database adapted to the complex environment of the power transmission network are formed. This method can provide more accurate status evaluation, timely detect potential safety hazards, and provide decision-making support to facilitate maintenance and repair activities in the operation of transmission lines.

[0116] The transmission line status evaluation method of this application, based on the fiber optic sensing system, effectively improves the safety monitoring level of the transmission line to be measured through real-time monitoring and in-depth analysis. Using the fiber optic sensing system to collect the status data of the transmission line to be measured can achieve ultra-long-distance real-time monitoring and multi-parameter distributed perception of the transmission line to be measured. By monitoring characteristic quantities such as the phase, light intensity, polarization state, and frequency of the transmitted light, basic quantities such as the temperature, strain, and real-time oscillation frequency of the power line can be sensed, providing basic data for accurately evaluating the line status, improving the coverage and accuracy of monitoring, and enhancing the ability to identify potential risks of the transmission line.

[0117] In one example, this application utilized more than 2000 status evaluation data points of aerial power lines in a specific area for a case study. After data purification of the relevant 220 kV aerial power line data, a data set for training and verification was established, which included a total of 510 training instances and a total of 143 test samples, including the values of all status quantities of the overhead transmission line and their corresponding evaluation grades. Their distribution is shown in Table 1, where there are 243 samples in the normal state, 209 samples in the attention state, 41 samples in the abnormal state, and 17 samples in the severe state.

[0118] Table 1 Sample of Transmission Line Status Evaluation Training

[0119]

[0120] Then, the results of the state evaluation of 143 test sample data using the proposed method are compared with the actual results, and the results are shown in Table 2.

[0121] Table 2 Comparison of status assessment results and actual results

[0122]

[0123] As can be seen from the table, the overall evaluation compliance is 92.31%, and the evaluation results of each working condition show a large deviation. The main reason is that the distribution of samples in each category is uneven and the total number of samples is relatively small. The evaluation results of this method are basically consistent with the actual sample evaluation results. In the biased results, compared with the test sample results, only one state is deviated, and it is mainly biased in a more serious direction. Further analysis of these lines with biased evaluations shows that 5 lines deviate from normal to attention, 4 lines deviate from attention to abnormal, and 2 lines deviate from abnormal to severe. The operation history of these 11 lines is relatively long, and each unit has a long time from the last inspection, that is, the equivalent operation time is long, resulting in a low evaluation score. Since the data source for the current transmission line status evaluation is mainly based on the transmission line status evaluation guide, the influence of line operation time and inspection interval is not considered in this process. Therefore, the status score of the line with a long operation time or a long inspection interval is not different from that of other lines. From this result, it can be inferred that the present invention significantly enhances the solution to this problem and is superior to the traditional method in terms of evaluation performance.

[0124] It should be understood that although Figures 4 - 7 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figures 4 - 7 At least part of the steps may include multiple steps or multiple stages. These steps or stages are not necessarily performed at the same time, but can be performed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed in turn or alternately with other steps or at least part of the steps or stages in other steps.

[0125] In an exemplary embodiment, see Figure 8 The present application provides a transmission line status assessment device, which is applied to a fiber optic sensing system. The device includes: an acquisition module 801, a conversion module 802 and an assessment module 803.

[0126] The acquisition module 801 is configured to acquire an optical signal to be measured of a sensing optical fiber in an optical fiber sensing system; the optical signal to be measured is an optical signal obtained after the optical fiber sensing system modulates and enhances a target optical signal and then transmits it to the sensing optical fiber and under the action of a power transmission line to be measured; the target optical signal is an optical signal that minimizes the negative impact of the nonlinear effect on the sensing performance of the sensing optical fiber.

[0127] The conversion module 802 is configured to perform optoelectronic conversion processing on the optical signal to be measured to obtain status data of the power transmission line to be measured.

[0128] The evaluation module 803 is configured to obtain a status evaluation result of the power transmission line to be measured according to the status data and a preset status evaluation model.

[0129] For the specific limitations of the power transmission line status evaluation device, reference may be made to the limitations on the power transmission line status evaluation method in the foregoing text, which will not be elaborated herein. Each module in the above power transmission line status evaluation device can be implemented in whole or in part by software, hardware, and their combination. The above modules can be embedded in the processor in the computer device in the form of hardware or be independent of it, or can be stored in the memory in the computer device in the form of software, so as to facilitate the processor to call and execute the operations corresponding to the above modules. It should be noted that the division of modules in the embodiments of the present application is illustrative, only a logical function division, and there may be other division methods in actual implementation.

[0130] Those of ordinary skill in the art can understand that all or part of the processes of implementing the methods in the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it may include the processes of the embodiments of the above methods. Among them, any reference to a memory, storage, database, or other medium used in the embodiments provided in the present application may include at least one of non-volatile and volatile memories. The non-volatile memory may include a read-only memory (ROM), magnetic tape, floppy disk, flash memory, or optical memory, etc. The volatile memory may include a random access memory (RAM) or an external cache memory. By way of illustration and not limitation, RAM can be in various forms, such as a static random access memory (SRAM) or a dynamic random access memory (DRAM), etc.

[0131] In the description of this specification, the descriptions referring to terms such as "some embodiments", "other embodiments", "ideal embodiments", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

[0132] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0133] The above-described embodiments only represent several implementation manners of the present application. The descriptions are relatively specific and detailed, but should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A method for evaluating the state of a transmission line, characterized in that, Applied to an optical fiber sensing system, the method includes: Obtaining an optical signal to be measured of a sensing optical fiber in the optical fiber sensing system; the optical signal to be measured is an optical signal obtained after the optical fiber sensing system modulates and enhances a target optical signal, transmits it to the sensing optical fiber, and then under the action of a power transmission line to be measured; the target optical signal is an optical signal that minimizes the negative impact of the nonlinear effect on the sensing performance of the sensing optical fiber; Performing photoelectric conversion processing on the optical signal to be measured to obtain state data of the power transmission line to be measured; Obtaining a state evaluation result of the power transmission line to be measured according to the state data and a preset state evaluation model.

2. The method according to claim 1, wherein The method for determining the target optical signal includes: Obtaining multiple groups of candidate light source information, where the candidate light source information includes light source pulse waveform information and candidate peak power information; Controlling the optical fiber sensing system to output candidate optical signals to the initial node of the sensing optical fiber respectively according to each group of candidate light source information; Respectively determining the nonlinear index of the sensing optical fiber according to each group of candidate light source information and a preset wave coupling formula; Determining target light source information from each group of candidate light source information according to the nonlinear index corresponding to each group of candidate light source information; Determining the candidate optical signal corresponding to the target light source information as the target optical signal.

3. The method according to claim 2, wherein Determining the nonlinear index of the sensing optical fiber according to the candidate light source information and a preset wave coupling formula includes: Determining the complex amplitude of the pump light at each node according to the candidate peak power information, a preset fiber loss coefficient, a preset Raman gain coefficient, a preset pump light loss coefficient, and the distance information between each preset node and the initial node on the sensing optical fiber; Determining the complex amplitude of the Stokes light at each node on the sensing optical fiber according to the complex amplitude of the pump light at each node, a preset vacuum permittivity, a preset polarization rate change amplitude, and a preset proportionality constant; Calculating the nonlinear index at each node on the sensing optical fiber according to the complex amplitude of the pump light at each node, the complex amplitude of the Stokes light at each node, and a preset wave coupling equation.

4. The method according to claim 2, wherein Determining the complex amplitude of the pump light at each node according to the candidate peak power information, a preset fiber loss coefficient, a preset Raman gain coefficient, a preset pump light loss coefficient, and the distance information between each preset node and the initial node on the sensing optical fiber includes: Determining the power of the candidate optical signal at each node on the sensing optical fiber according to the candidate peak power information, a preset fiber loss coefficient, and a preset Raman gain coefficient; Determining the power of the pump light at each node on the sensing optical fiber according to the power of the candidate optical signal at each node, a preset Raman gain coefficient, a preset pump light loss coefficient, and the distance information between each preset node and the initial node; Determining the complex amplitude of the pump light at each node according to the power of the pump light at each node.

5. An optical fiber sensing system, characterized in that, The system includes: a sensing optical fiber, a light source assembly, a modulation assembly, and a detection assembly; Among them, the light source component is used to output a target optical signal; the modulation component is respectively connected to the light source component and the sensing optical fiber, and is used to modulate and enhance the target optical signal, and input the target optical signal after modulation and enhancement into the sensing optical fiber; the sensing optical fiber is used to output a measured optical signal based on the target optical signal under the action of the transmission line to be measured; the detection component is connected to the sensing optical fiber, and is used to obtain the measured optical signal in the sensing optical fiber, obtain the state data of the transmission line to be measured according to the measured optical signal, and obtain the state evaluation result of the transmission line to be measured according to the state data and a preset state evaluation model.

6. The fiber optic sensing system according to claim 5, wherein The modulation component includes: A first modulation unit, which is respectively connected to the light source component and the sensing optical fiber, and is used to receive the target optical signal, perform pulse modulation processing on the target optical signal, and perform enhancement processing on the target optical signal after the pulse modulation processing, and output a first target optical signal; A second modulation unit, which is respectively connected to the light source component and the sensing optical fiber, and is used to receive the target optical signal, perform double-sideband modulation processing on the target optical signal, and output a second target optical signal; Among them, the first target optical signal and the second target optical signal converge in the sensing optical fiber and are converted into a measured optical signal under the action of the transmission line to be measured.

7. The fiber optic sensing system according to claim 6, wherein The first modulation unit includes: A first modulation subunit, which is connected to the light source component, and is used to output an electrical pulse signal to perform pulse modulation on the target optical signal according to the electrical pulse signal; A signal enhancement subunit, which is used to output a pump optical signal; A first multiplexer, which is respectively connected to the first modulation subunit, the signal enhancement subunit and the sensing optical fiber, and is used to perform coupling processing on the pump optical signal and the target optical signal after pulse modulation, so that the pump optical signal performs enhancement processing on the target optical signal, generates a first target optical signal, and inputs the pump optical signal and the first target optical signal into the sensing optical fiber.

8. The fiber optic sensing system according to claim 6, wherein The second modulation unit includes: A second modulation subunit, which is connected to the light source component, and is used to provide a radio frequency signal and perform double-sideband modulation on the target optical signal according to the radio frequency signal; A filtering subunit, which is respectively connected to the second modulation subunit and the sensing optical fiber, and is used to perform filtering and polarization processing on the target optical signal after double-sideband modulation, generate a second target optical signal, and input the second target optical signal into the sensing optical fiber.

9. The fiber optic sensing system according to claim 5, characterized in that, The detection component includes: A second multiplexer, which is connected to the sensing optical fiber, and is used to receive the measured optical signal, perform decoupling processing on the measured optical signal, and extract a target measured optical signal with the same wavelength as the target optical signal in the measured optical signal; An optoelectronic conversion unit, which is connected to the second multiplexer, and is used to obtain the state data of the transmission line to be measured according to the target measured optical signal; An evaluation unit, which is connected to the optoelectronic conversion unit, and is used to obtain the state evaluation result of the transmission line to be measured according to the state data and a preset state evaluation model.

10. A transmission line status evaluation device, characterized in that Applied to an optical fiber sensing system, the device includes: An acquisition module, configured to acquire an optical signal to be measured of a sensing optical fiber in the optical fiber sensing system; the optical signal to be measured is an optical signal obtained after the optical fiber sensing system modulates and enhances a target optical signal, transmits the modulated and enhanced optical signal to the sensing optical fiber, and then under the action of a power transmission line to be measured; the target optical signal is an optical signal that minimizes the negative impact of non-linear effects on the sensing performance of the sensing optical fiber; A conversion module, configured to perform optoelectronic conversion processing on the optical signal to be measured to obtain status data of the power transmission line to be measured; An evaluation module, configured to obtain a status evaluation result of the power transmission line to be measured according to the status data and a preset status evaluation model.

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