An online monitoring system for the state of an optical fiber composite overhead ground line

Abstract

The application provides an optical fiber composite overhead ground line state online monitoring system, which comprises an optical fiber sensing module, an information acquisition and storage module and an information calculation and processing module; the Rayleigh scattering signal and the Raman scattering signal of the optical fiber composite overhead ground line are measured through the optical fiber sensing module; the measured Rayleigh scattering signal and Raman scattering signal are collected and stored through the information acquisition and storage module; the Rayleigh scattering signal and the Raman scattering signal are demodulated and processed through the information calculation and processing module, the dancing frequency, the sag and the average temperature of the optical fiber composite overhead ground line are obtained respectively and based on this, the dancing state of the optical fiber composite overhead ground line and the icing state of the optical fiber composite overhead ground line are judged. Compared with the prior art, the technical scheme of the application can demodulate the temperature, the sag and the dancing frequency and other information by measuring the scattering signal of the optical fiber along the line, can intelligently identify the working state of the power transmission line in real time, and is convenient for subsequent timely warning based on the working state.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power system equipment state detection and optical fiber distributed sensing, and particularly relates to an optical fiber composite overhead ground wire state online monitoring system. BACKGROUND

[0002] The safety and stability of power lines are the foundation of guaranteeing power quality, and large-area icing of transmission lines caused by severe weather and uncontrollable galloping are important reasons for transmission line failure. Due to the characteristics of wide range across regions and great difficulty in repair of transmission lines, once serious cable icing and galloping events occur, long-time and large-area power outages will be caused. With the rapid expansion of the power grid in China, large-area icing accidents have occurred in various parts of the country in the past 50 years, especially from January to February 2008, a long-time and large-area snow and ice weather occurred in the southern power grid of China, causing 1252 110-500KV line towers to collapse and 13888 10-35KV lines to fail and stop operating, which has a serious impact on the local people's life and national economic development.

[0003] The existing icing detection methods for transmission lines include the following: manual inspection method, weighing method, image method, and simulated conductor method. Among them, the manual inspection method consumes a lot of manpower and material resources, has poor measurement accuracy, and due to the limitation of the walking speed of the artificial, the real-time performance is poor, and the manual inspection method has been faced with elimination; the weighing method: through angle sensors, tension sensors, load sensors, etc. to measure the sag, tension, and load of the conductor after icing, and compare the data with the data before icing to calculate the equivalent icing thickness. However, the sensors have nonlinear, creep, and zero drift characteristics, and in extreme environments and strong magnetic field interference, the data obtained is inaccurate; the image method: a camera is installed to take pictures of the transmission line, and the images before and after icing are compared, and the image segmentation method is used to obtain the image edge after icing to judge the icing condition. Disadvantages: the measurement accuracy is limited by the algorithm itself, the camera field of view is limited in terms of measurement breadth, and the working state of the camera in severe cold environments is poor; the simulated conductor method: a power cable identical to the real conductor is erected at the monitoring station near the area where icing events frequently occur, and the icing condition on the simulated conductor is measured to analogically infer the icing condition on the real conductor. Disadvantages: there is no current in the simulated conductor, which cannot simulate the real conductor conditions including thermal effects. The icing thickness, speed, shape, etc. are related to the airflow in the high altitude, which cannot be simulated, and this method needs to be measured in the same environment as the cable, and a lot of manpower is needed to measure the cable in remote areas. SUMMARY

[0004] The technical problem solved by the present application is to provide an optical fiber composite overhead ground line state online monitoring system, which can demodulate temperature, sag and dance frequency information by measuring the scattering signals of the optical fiber along the line, can intelligently identify the working state of the power transmission line in real time, facilitates subsequent timely warning based on the working state, and solves the problems of long time consumption and low precision of the existing measurement method.

[0005] To solve the above technical problems, the present application provides an optical fiber composite overhead ground line state online monitoring system, comprising: an optical fiber sensing module, an information acquisition and storage module, and an information calculation and processing module.

[0006] The optical fiber sensing module comprises a phase-sensitive optical time domain reflection module based on Rayleigh scattering and an optical time domain reflection module based on Raman scattering.

[0007] The information calculation and processing module comprises a data preprocessing module, a temperature demodulation module, a dance frequency demodulation module, a sag demodulation module, and a decision output module.

[0008] The phase-sensitive optical time domain reflection module is configured to measure the Rayleigh scattering signals of the optical fiber composite overhead ground line.

[0009] The optical time domain reflection module is configured to measure the Raman scattering signals of the optical fiber composite overhead ground line.

[0010] The information acquisition and storage module is configured to acquire and store the Rayleigh scattering signals and the Raman scattering signals.

[0011] The data preprocessing module is configured to perform noise reduction processing on the Rayleigh scattering signals and the Raman scattering signals.

[0012] The dance frequency demodulation module is configured to acquire and perform signal processing on the Rayleigh scattering signals to obtain the dance frequency of the optical fiber composite overhead ground line.

[0013] The sag demodulation module is configured to acquire and perform signal processing on the Rayleigh scattering signals to obtain the sag of the optical fiber composite overhead ground line.

[0014] The temperature demodulation module is configured to acquire and perform signal processing on the Raman scattering signals to obtain the average temperature of the optical fiber composite overhead ground line within a preset time.

[0015] The decision output module is configured to calculate the maximum sag change of the optical fiber composite overhead ground line according to the sag, calculate the first and second accumulated temperatures of the optical fiber composite overhead ground line according to the average temperature, output the dance state of the optical fiber composite overhead ground line according to the dance frequency and the maximum sag change, and output the icing state of the optical fiber composite overhead ground line according to the sag, the first accumulated temperature, and the second accumulated temperature.

[0016] The application provides an online monitoring system for the state of an optical fiber composite overhead ground wire, further comprising a warning module, a device communication module and a display module.

[0017] The warning module is configured to receive and issue a warning signal according to the galloping state of the optical fiber composite overhead ground wire and the icing state of the optical fiber composite overhead ground wire.

[0018] The display module is configured to receive and display the galloping state of the optical fiber composite overhead ground wire and the icing state of the optical fiber composite overhead ground wire.

[0019] The device communication module is configured to communicate the working states of the modules.

[0020] In a possible implementation, the optical fiber sensing module is connected to the information acquisition and storage module, the information acquisition and storage module is connected to the device communication module, the device communication module is connected to the information calculation and processing module, the information calculation and processing module is connected to the warning module, and the warning module is connected to the display module.

[0021] In a possible implementation, the optical fiber sensing module comprises a phase-sensitive optical time domain reflection module based on Rayleigh scattering and an optical time domain reflection module based on Raman scattering, and specifically comprises:

[0022] The phase-sensitive optical time domain reflection module based on Rayleigh scattering comprises an ultra-narrow linewidth laser, a pulse modulator, an erbium-doped fiber amplifier, a first circulator, a filter and a balanced detector.

[0023] The optical time domain reflection module based on Raman scattering comprises a laser source, a wavelength division multiplexer, an optical pulse amplifier, a second circulator and a photodetector.

[0024] In a possible implementation, the decision output module is configured to output the galloping state of the optical fiber composite overhead ground wire according to the galloping frequency and the maximum sag change amount, and specifically comprises:

[0025] The galloping frequency is compared with a preset galloping frequency threshold value, if the galloping frequency is not greater than the preset galloping frequency threshold value, the galloping state of the optical fiber composite overhead ground wire is output as normal.

[0026] If the galloping frequency is greater than the preset galloping frequency threshold value, the maximum sag change amount is compared with a preset maximum sag change amount threshold value, if the maximum sag change amount is not greater than the preset maximum sag change amount threshold value, the galloping state of the optical fiber composite overhead ground wire is output as normal.

[0027] If the maximum sag change amount is greater than a preset maximum sag change amount threshold, an optical fiber composite overhead ground wire dancing state abnormality is output.

[0028] In a possible implementation, the decision output module is configured to output an optical fiber composite overhead ground wire icing state according to the sag, the first accumulated temperature, and the second accumulated temperature, and specifically includes the following steps.

[0029] If the first accumulated temperature is not within a preset first accumulated temperature threshold range, it is determined that the optical fiber composite overhead ground wire does not have an icing initial sign.

[0030] If the sag is not greater than the first preset sag threshold, it is determined that the optical fiber composite overhead ground wire does not have an icing initial sign; if the sag is greater than the first preset sag threshold, it is determined that the optical fiber composite overhead ground wire has an icing initial sign.

[0031] If the second accumulated temperature is not within a preset second accumulated temperature threshold range, it is determined that the optical fiber composite overhead ground wire does not have an icing state.

[0032] If the sag is not greater than the second preset sag threshold, it is determined that the optical fiber composite overhead ground wire does not have an icing state; if the sag is greater than the first preset sag threshold, it is determined that the optical fiber composite overhead ground wire has an icing state.

[0033] In a possible implementation, the decision output module is configured to calculate a first accumulated temperature and a second accumulated temperature of the optical fiber composite overhead ground wire according to the average temperature, and specifically includes the following steps.

[0034] A plurality of first average temperatures collected within a first preset time are obtained, and it is determined whether the plurality of first average temperatures satisfy a first preset average temperature threshold range, respectively; if yes, a first average temperature is retained, and all retained first average temperatures are accumulated to obtain the first accumulated temperature.

[0035] A plurality of second average temperatures collected within a second preset time are obtained, and it is determined whether the plurality of second average temperatures satisfy a second preset average temperature threshold range, respectively; if yes, a second average temperature is retained, and all retained second average temperatures are accumulated to obtain the second accumulated temperature.

[0036] In a possible implementation, after the decision output module outputs the optical fiber composite overhead ground wire icing state according to the sag, the first accumulated temperature, and the second accumulated temperature, the decision output module further includes the following steps.

[0037] When the optical fiber composite overhead ground wire exists icing state, the equivalent icing thickness of the optical fiber composite overhead ground wire is calculated, wherein the equivalent icing thickness calculation formula is as follows:

[0038]

[0039] Wherein, d is the equivalent icing thickness, m o is the initial mass of the optical fiber composite overhead ground wire per unit length, f o is the vibration frequency of the optical fiber composite overhead ground wire when not icing, f ice is the vibration frequency of the optical fiber composite overhead ground wire when icing, p ice is the density of the ice layer 0.92 g / cm 3 , r o is the initial radius of the optical fiber composite overhead ground wire.

[0040] In a possible implementation, the decision output module is configured to calculate a maximum sag change of the optical fiber composite overhead ground wire according to the sag, and specifically includes:

[0041] The sag is input into a preset maximum sag change calculation formula to calculate and obtain the maximum sag change of the optical fiber composite overhead ground wire, wherein the preset maximum sag change calculation formula is as follows:

[0042]

[0043] In the formula, Delta h is the sag change, lambda is the wavelength of the probe light, l is the distance between two towers, is the phase of the optical fiber composite overhead ground wire after icing, is the original phase of the optical fiber composite overhead ground wire, and h0 is the sag of the optical fiber composite overhead ground wire.

[0044] In a possible implementation, the information acquisition and storage module includes a high-speed acquisition card and a solid state disk array.

[0045] Compared with the prior art, the optical fiber composite overhead ground wire state online monitoring system has the following beneficial effects:

[0046] The application provides an online monitoring system for the state of an optical fiber composite overhead ground wire, which comprises an optical fiber sensing module, an information acquisition and storage module and an information calculation and processing module; the Rayleigh scattering signal and the Raman scattering signal of the optical fiber composite overhead ground wire are measured through the optical fiber sensing module; the measured Rayleigh scattering signal and Raman scattering signal are collected and stored through the information acquisition and storage module; the Rayleigh scattering signal and Raman scattering signal are demodulated and processed through the information calculation and processing module, the dancing frequency, sag and average temperature of the optical fiber composite overhead ground wire are obtained respectively and based on this, the dancing state of the optical fiber composite overhead ground wire and the icing state of the optical fiber composite overhead ground wire are judged. Compared with the prior art, the technical scheme of the application adopts the distributed optical fiber sensing technology to monitor the state of the power transmission line, does not need to install additional sensors, can demodulate the temperature, sag and dancing frequency and other information through the measurement of the scattering signal of the optical fiber along the line, can intelligently identify the working state of the power transmission line in real time, is convenient for subsequent timely warning based on the working state, has the advantages of long detection distance, simple maintenance, high detection precision, no dead angle monitoring and the like, and can solve the problems of long time consumption, low precision and narrow coverage of the traditional measurement method. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 is a structural schematic diagram of one embodiment of the online monitoring system for the state of the optical fiber composite overhead ground wire provided by the application;

[0048] Figure 2 is still another structural schematic diagram of one embodiment of the online monitoring system for the state of the optical fiber composite overhead ground wire provided by the application;

[0049] Figure 3 is a module connection schematic diagram of still another embodiment of the online monitoring system for the state of the optical fiber composite overhead ground wire provided by the application. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0051] Embodiment 1

[0052] Reference is made to Figure 1 , Figure 1 is a structural schematic diagram of one embodiment of the online monitoring system for the state of the optical fiber composite overhead ground wire provided by the application, as Figure 1As shown, the system comprises a fiber sensing module 101, an information acquisition and storage module 102, and an information calculation and processing module 103, and specifically as follows:

[0053] In an embodiment, the fiber sensing module 101 comprises a phase-sensitive optical time domain reflection module Φ-OTDR based on Rayleigh scattering and an optical time domain reflection module R-OTDR based on Raman scattering.

[0054] In an embodiment, the phase-sensitive optical time domain reflection module is used to measure the Rayleigh scattering signal of the fiber composite overhead ground wire; the phase-sensitive optical time domain reflection module based on Rayleigh scattering comprises an ultra-narrow linewidth laser, a pulse modulator, an erbium-doped fiber amplifier, a first circulator, a filter, and a balanced detector; specifically, the ultra-narrow linewidth laser is used to emit continuous light, so that after the continuous light is modulated into pulsed light by the pulse modulator, the pulsed light is amplified based on the erbium-doped fiber amplifier, the probe optical fiber is injected through the first circulator, the returned Rayleigh scattering signal passes through the band-pass filter and enters the data acquisition card in the information acquisition and storage module 102 through the balanced detector, and is stored in the computer, waiting for the next step of processing.

[0055] In an embodiment, the optical time domain reflection module is used to measure the Raman scattering signal of the fiber composite overhead ground wire; the optical time domain reflection module based on Raman scattering comprises a laser source, a wavelength division multiplexer, an optical pulse amplifier, a second circulator, and a photodetector; specifically, after the continuous light emitted by the laser source is modulated into pulsed light by the pulse modulator, the pulsed light is amplified based on the optical pulse amplifier, the probe optical fiber is injected through the second circulator, Raman scattering occurs in the probe optical fiber, generating Stokes light and anti-Stokes light, which are filtered by the Raman filter and converted by the photodetector to generate Raman scattering signals, which enter the data acquisition card in the information acquisition and storage module 102, and are stored in the computer, waiting for the next step of processing.

[0056] In an embodiment, the information acquisition and storage module 102 is used to acquire and store the Rayleigh scattering signal and the Raman scattering signal.

[0057] In an embodiment, the information acquisition and storage module 102 comprises a high-speed acquisition card and a solid-state disk array; wherein the high-speed acquisition card is a 250MHz multi-channel high-speed acquisition card, which can realize edge trigger acquisition mode for optical pulse setting and can simultaneously perform high-speed acquisition of scattering traces of two fiber sensing lines. The solid-state disks form a redundant array of independent disks (RAID), which can realize high-speed reading and writing of large-capacity data and has high data security.

[0058] In an embodiment, the information calculation and processing module 103 comprises a data preprocessing module, a temperature demodulation module, a galloping frequency demodulation module, a sag demodulation module and a decision output module.

[0059] In an embodiment, the data preprocessing module is configured to perform noise reduction processing on the Rayleigh scattering signal and the Raman scattering signal. Specifically, the baseline noise of the sensing system in the case of no icing event and no galloping event of the power transmission line is collected, and an arithmetic mean of the baseline noise is calculated. The noise reduction of the original scattering trace can be achieved by subtracting the arithmetic mean from the original scattering trace.

[0060] For the trace segmentation processing, the length of the OPGW to be measured and the propagation speed of the optical pulse in the OPGW are calculated to set the optical pulse frequency, so that the noise segment between each scattering trace in the collected signal is as small as possible. Then, the length and period of the scattering trace are calculated to determine the cut-off point between the traces, and the wavelet transform method is applied to extract the envelope of the scattering trace. After extracting the envelope of the scattering trace, the starting point is selected to segment the trace.

[0061] The wavelet transform is defined as:

[0062]

[0063] wherein a is a scale parameter and b is a position parameter.

[0064] In an embodiment, the galloping frequency demodulation module is configured to acquire and perform signal processing on the Rayleigh scattering signal to obtain the galloping frequency of the OPGW.

[0065] Specifically, the galloping frequency demodulation module demodulates the galloping frequency of the OPGW by detecting the change of the backscattering Rayleigh scattering light power. When the OPGW gallops, it will deform, causing the optical fiber to follow the cable to produce a slight deformation, which will periodically change the length of the sensing optical fiber and the core refractive index. The distance between the strain peaks of the optical fiber can be demodulated to obtain the galloping frequency of the OPGW.

[0066] In an embodiment, the sag demodulation module is configured to acquire and perform demodulation processing on the Rayleigh scattering signal to obtain the sag of the OPGW.

[0067] In an embodiment, the temperature demodulation module is configured to acquire and perform signal processing on the Raman scattering signal to obtain the average temperature of the OPGW within a preset time,

[0068] Specifically, the temperature demodulation module obtains the temperature of the sensing optical fiber along the line by demodulating the Raman scattering signal. Since the Raman scattering light is only sensitive to temperature, and the Raman scattering is divided into Stokes and anti-Stokes scattering light, the anti-Stokes scattering light is sensitive to temperature, while the Stokes scattering light is less affected by temperature, and the intensity of the two scattering lights is proportional to the change in temperature. The temperature of the temperature measurement point can be obtained by measuring and calculating the intensity ratio of the Stokes and anti-Stokes light. The temperature calculation is according to the following formula:

[0069]

[0070] Where h is the Planck coefficient, c is the speed of light in vacuum, k is the Boltzmann constant, v is the Raman shift, and a is the temperature correlation coefficient. as is the anti-Stokes light intensity, and s is the Stokes light intensity.

[0071] Specifically, by obtaining the temperature of each temperature measurement point in the optical fiber composite overhead ground wire within a predetermined time, the average temperature T avg is obtained by calculating the average of the obtained temperature, where the predetermined time is within the past one hour.

[0072] In an embodiment, the decision output module comprehensively evaluates the working state of the optical fiber composite overhead ground wire according to the output data of the temperature demodulation module, the galloping frequency demodulation module, and the sag demodulation module, and judges three event states of abnormal galloping of the optical fiber composite overhead ground wire, conductor icing warning, and conductor icing and thickness calculation by setting different threshold values.

[0073] Specifically, the decision output module is configured to calculate the maximum sag change of the optical fiber composite overhead ground wire according to the sag.

[0074] Since the sensing optical fiber in the optical fiber composite overhead ground wire has a certain length of redundancy, when the optical fiber composite overhead ground wire icing causes the sag to increase, the redundant optical fiber length in the optical fiber composite overhead ground wire will be consumed first, further causing the optical fiber to produce axial strain, causing the optical fiber length and the core refractive index to change, and causing the light phase of the backscattering signal to change. Therefore, when the sag increases, it can be judged that the line icing occurs. The sag demodulation module can obtain the sag increment of the optical fiber composite overhead ground wire by demodulating the backscattering Rayleigh trace, which is used as a judgment basis for the occurrence of icing events.

[0075] The sag is input into a preset maximum sag change calculation formula to calculate and obtain the maximum sag change of the optical fiber composite overhead ground wire, where the preset maximum sag change calculation formula is as follows:

[0076]

[0077] In the formula, Δh is the change in sag, λ is the wavelength of the probe light, and l is the distance between the two towers. This refers to the phase after the fiber optic composite overhead ground wire is iced. h0 represents the original phase of the fiber optic composite overhead ground wire, and h0 represents the sag of the fiber optic composite overhead ground wire.

[0078] Specifically, the decision output module is used to calculate the first accumulated temperature and the second accumulated temperature of the optical fiber composite overhead ground wire based on the average temperature.

[0079] By acquiring multiple first average temperatures collected within a first preset time period, it is determined whether the multiple first average temperatures meet the first preset average temperature threshold range. If so, the first average temperature is retained, and all retained first average temperatures are accumulated to obtain the first accumulated temperature. By acquiring multiple second average temperatures collected within a second preset time period, it is determined whether the multiple second average temperatures meet the second preset average temperature threshold range. If so, the second average temperature is retained, and all retained second average temperatures are accumulated to obtain the second accumulated temperature.

[0080] As an example in this embodiment: Calculate the first accumulated temperature T on the fiber optic composite overhead ground line in the past 10 hours. sum1 The second accumulated temperature T on the fiber optic composite overhead ground line in the last 24 hours sum2 The method for calculating accumulated temperature is: T sum1 The first average temperature T over the past 10 hours avg Meets -5℃ <T avg The sum of the first average temperatures under conditions below 0℃; T sum2 The second-highest average temperature over the past 24 hours is -15℃. <T avg The sum of the second average temperatures under conditions of <-5℃.

[0081] Specifically, the decision output module is used to output the dancing state of the optical fiber composite overhead ground wire based on the dancing frequency and the maximum change in sag.

[0082] By comparing the waving frequency with a preset waving frequency threshold, if the waving frequency is not greater than the preset waving frequency threshold, the waving state of the fiber optic composite overhead ground wire is output as normal; if the waving frequency is greater than the preset waving frequency threshold, the maximum change in sag is compared with a preset maximum change in sag threshold. If the maximum change in sag is not greater than the preset maximum change in sag threshold, the waving state of the fiber optic composite overhead ground wire is output as normal; if the maximum change in sag is greater than the preset maximum change in sag threshold, the waving state of the fiber optic composite overhead ground wire is output as abnormal.

[0083] Preferably, the preset galloping frequency threshold is 1 Hz, and the preset sag maximum change threshold is 10 m.

[0084] As an example in this embodiment: if the current optical fiber composite overhead ground wire has a galloping frequency F g >1 Hz and a sag maximum change Ah>10 m, the optical fiber composite overhead ground wire is output as being in an abnormal galloping state.

[0085] Specifically, the decision output module is configured to output an icing state of the optical fiber composite overhead ground wire according to the sag, the first accumulated temperature, and the second accumulated temperature.

[0086] By judging whether the first accumulated temperature is within a preset first accumulated temperature threshold range, if not, the optical fiber composite overhead ground wire is output as not having an initial icing sign; when it is judged that the first accumulated temperature is within the preset first accumulated temperature threshold range, the sag is compared with a first preset sag threshold, if the sag is not greater than the first preset sag threshold, the optical fiber composite overhead ground wire is output as not having an initial icing sign, and if the sag is greater than the first preset sag threshold, the optical fiber composite overhead ground wire is output as having an initial icing sign.

[0087] Preferably, the preset first accumulated temperature threshold range is -50℃ sum1 <-20℃, and the first preset sag threshold is Hg>1 / 300l, where l is a horizontal distance between two line towers.

[0088] As an example in this embodiment: if the current optical fiber composite overhead ground wire has an accumulated temperature -50℃ sum1 <-20℃ and a sag Hg>1 / 300l in the last 10 hours, the optical fiber composite overhead ground wire is output as having an initial icing sign, and a conductor icing warning needs to be issued.

[0089] By judging whether the second accumulated temperature is within a preset second accumulated temperature threshold range, if not, the optical fiber composite overhead ground wire is output as not having an icing state; when it is judged that the second accumulated temperature is within the preset second accumulated temperature threshold range, the sag is compared with a second preset sag threshold, if the sag is not greater than the second preset sag threshold, the optical fiber composite overhead ground wire is output as not having an icing state, and if the sag is greater than the first preset sag threshold, the optical fiber composite overhead ground wire is output as having an icing state.

[0090] Preferably, the preset second accumulated temperature threshold range is -3600℃ sum2 <-240℃, and the second preset sag threshold is Hg>1 / 100l, where l is a horizontal distance between two line towers.

[0091] As an example in this embodiment: if the current optical fiber composite overhead ground wire has a heat accumulation -3600℃<T sum2 <-240℃, and sag Hg>1 / 100l; the output optical fiber composite overhead ground wire has an icing state.

[0092] In an embodiment, when the output optical fiber composite overhead ground wire has an icing state, the equivalent icing thickness of the optical fiber composite overhead ground wire is also calculated. Since the icing will affect the conductor galloping frequency, the icing thickness can be calculated through the galloping frequency, and the equivalent icing thickness calculation formula is as follows:

[0093]

[0094] Where d is the equivalent icing thickness, m o is the initial mass of the unit length of the optical fiber composite overhead ground wire, f o is the vibration frequency of the optical fiber composite overhead ground wire without icing, f ice is the vibration frequency of the optical fiber composite overhead ground wire with icing, p ice is the density of the ice layer 0.92g / cm 3 , r o is the initial radius of the optical fiber composite overhead ground wire.

[0095] In an embodiment, the online monitoring system for the state of the optical fiber composite overhead ground wire provided by the application further comprises a warning module 104, a device communication module 105 and a display module 106, as shown in Figure 2 . Figure 2 is another structural diagram of the online monitoring system for the state of the optical fiber composite overhead ground wire provided by the embodiment of the application.

[0096] In an embodiment, the warning module 104 is used to receive and issue a warning signal according to the galloping state of the optical fiber composite overhead ground wire and the icing state of the optical fiber composite overhead ground wire.

[0097] In an embodiment, the display module 106 is used to receive and display the galloping state of the optical fiber composite overhead ground wire and the icing state of the optical fiber composite overhead ground wire. Specifically, the display module 106 can display the event type and the event occurrence position, including icing warning, galloping warning, icing thickness measurement display, galloping amplitude and frequency display.

[0098] In an embodiment, the device communication module 105 is configured to communicate the working states among the modules. Specifically, the synchronization settings of the optical pulse modulator and the data acquisition card are communicated, and the data transmission among the fiber sensing module 101, the information acquisition and storage module 102, the information calculation and processing module 103, the early warning module 104, and the display module 106 is communicated by using a wireless signal transceiver.

[0099] In an embodiment, the fiber sensing module 101 is connected to the information acquisition and storage module 102, the information acquisition and storage module 102 is connected to the device communication module 105, the device communication module is connected to the information calculation and processing module 103, the information calculation and processing module 103 is connected to the early warning module 104, and the early warning module 104 is connected to the display module 106. Figure 3 Figure 3 is another connection diagram of the state online monitoring system of the fiber composite overhead ground wire provided by the embodiment of the present application.

[0100] In summary, the state online monitoring system of the fiber composite overhead ground wire provided by the present application uses the distributed fiber sensing technology to monitor the state of the power transmission line, and does not need to install additional sensors, but only needs to use the existing optical fiber resources in the fiber composite overhead ground wire, the fiber composite phase line, and the like. This method has the advantages of long detection distance, simple maintenance, high detection precision, and no dead angle monitoring, and the like. By measuring the scattering signals along the optical fiber, the information such as the temperature, the sag, and the vibration frequency can be demodulated, the working state of the power transmission line can be further intelligently identified in real time, and the fault alarm can be timely performed. The distributed fiber sensing can solve the problems of long time consumption, low precision, and narrow coverage of the traditional measurement method, and has a broad application prospect.

[0101] The above only describes the preferred embodiments of the present application, and it should be noted that, for those skilled in the art, without departing from the technical principles of the present application, a number of improvements and replacements can be made, and these improvements and replacements should also be considered as the protection scope of the present application.​

Claims

1. An online status monitoring system for fiber optic composite overhead ground wires, characterized in that, include: Fiber optic sensing module, information acquisition and storage module, and information calculation and processing module; The fiber optic sensing module includes a phase-sensitive optical time-domain reflectometry module based on Rayleigh scattering and an optical time-domain reflectometry module based on Raman scattering. The information calculation and processing module includes a data preprocessing module, a temperature demodulation module, a dancing frequency demodulation module, a sag demodulation module, and a decision output module; The phase-sensitive optical time-domain reflectometry module is used to measure the Rayleigh scattering signal of the fiber-optic composite overhead ground wire; The optical time-domain reflectometry module is used to measure the Raman scattering signal of the fiber-optic composite overhead ground wire; The information acquisition and storage module is used to acquire and store the Rayleigh scattering signal and the Raman scattering signal; The data preprocessing module is used to perform noise reduction processing on the Rayleigh scattering signal and the Raman scattering signal; The dancing frequency demodulation module is used to acquire and process the Rayleigh scattering signal to obtain the dancing frequency of the optical fiber composite overhead ground wire. The sag demodulation module is used to acquire and process the Rayleigh scattering signal to obtain the sag of the fiber optic composite overhead ground wire. The temperature demodulation module is used to acquire and process the Raman scattering signal to obtain the average temperature of the fiber optic composite overhead ground wire within a preset time. The decision output module is used to calculate the maximum change in sag of the fiber optic composite overhead ground wire based on the sag, calculate the first accumulated temperature and the second accumulated temperature of the fiber optic composite overhead ground wire based on the average temperature, output the galloping state of the fiber optic composite overhead ground wire based on the galloping frequency and the maximum change in sag, and output the icing state of the fiber optic composite overhead ground wire based on the sag, the first accumulated temperature and the second accumulated temperature. The step of outputting the galloping state of the fiber optic composite overhead ground wire based on the galloping frequency and the maximum change in sag specifically includes: The dancing frequency is compared with a preset dancing frequency threshold. If the dancing frequency is not greater than the preset dancing frequency threshold, the dancing state of the fiber optic composite overhead ground wire is normal. If the dancing frequency is greater than the preset dancing frequency threshold, then the maximum change in sag is compared with the preset maximum change in sag threshold. If the maximum change in sag is not greater than the preset maximum change in sag threshold, then the dancing state of the fiber optic composite overhead ground wire is normal. If the maximum change in sag is greater than the preset maximum change in sag threshold, the output fiber optic composite overhead ground wire galloping state is abnormal. The step of outputting the icing status of the fiber optic composite overhead ground wire based on the sag, the first accumulated temperature, and the second accumulated temperature specifically includes: Determine whether the first accumulated temperature is within the preset first accumulated temperature threshold range. If not, output that there are no initial signs of icing on the fiber optic composite overhead ground wire. When it is determined that the first accumulated temperature is within the preset first accumulated temperature threshold range, the sag is compared with the first preset sag threshold. If the sag is not greater than the first preset sag threshold, the output fiber composite overhead ground wire does not have the initial signs of icing. If the sag is greater than the first preset sag threshold, the output fiber composite overhead ground wire has the initial signs of icing. Determine whether the second accumulated temperature is within the preset second accumulated temperature threshold range. If not, output that the fiber optic composite overhead ground wire is not iced. When it is determined that the second accumulated temperature is within the preset second accumulated temperature threshold range, the sag is compared with the second preset sag threshold. If the sag is not greater than the second preset sag threshold, the output fiber composite overhead ground wire is not in an icing state. If the sag is greater than the first preset sag threshold, the output fiber composite overhead ground wire is in an icing state.

2. The online status monitoring system for fiber optic composite overhead ground wire as described in claim 1, characterized in that, Also includes: Early warning module, device communication module, and display module; The early warning module is used to receive and issue an early warning signal based on the galloping state and icing state of the optical fiber composite overhead ground wire. The display module is used to receive and display the galloping state of the optical fiber composite overhead ground wire and the icing state of the optical fiber composite overhead ground wire. The device communication module is used to communicate the working status between various modules.

3. The online status monitoring system for fiber optic composite overhead ground wire as described in claim 2, characterized in that, The fiber optic sensing module is connected to the information acquisition and storage module, the information acquisition and storage module is connected to the device communication module, the device communication module is connected to the information calculation and processing module, the information calculation and processing module is connected to the early warning module, and the early warning module is connected to the display module.

4. The online status monitoring system for fiber optic composite overhead ground wire as described in claim 1, characterized in that, The fiber optic sensing module includes a phase-sensitive optical time-domain reflectometry module based on Rayleigh scattering and an optical time-domain reflectometry module based on Raman scattering, specifically including: The Rayleigh scattering-based phase-sensitive optical time-domain reflectometry module includes an ultra-narrow linewidth laser, a pulse modulator, an erbium-doped fiber amplifier, a first circulator, a filter, and a balanced detector. The Raman scattering-based optical time-domain reflectometry module includes a laser source, a wavelength division multiplexer, an optical pulse amplifier, a second circulator, and a photodetector.

5. The online status monitoring system for fiber optic composite overhead ground wire as described in claim 1, characterized in that, The decision output module is used to calculate the first accumulated temperature and the second accumulated temperature of the optical fiber composite overhead ground wire based on the average temperature, specifically including: Multiple first average temperatures collected within a first preset time period are obtained. It is determined whether each of the multiple first average temperatures meets the first preset average temperature threshold range. If so, the first average temperature is retained. All retained first average temperatures are accumulated to obtain the first accumulated temperature. Multiple second average temperatures collected within a second preset time period are obtained. It is determined whether each of the multiple second average temperatures meets the second preset average temperature threshold range. If so, the second average temperature is retained. All retained second average temperatures are accumulated to obtain the second accumulated temperature.

6. The online status monitoring system for fiber optic composite overhead ground wire as described in claim 1, characterized in that, The decision output module, after outputting the icing status of the fiber optic composite overhead ground wire based on the sag, the first accumulated temperature, and the second accumulated temperature, further includes: When the output fiber-optic composite overhead ground wire is iced, the equivalent icing thickness of the fiber-optic composite overhead ground wire is calculated. The formula for calculating the equivalent icing thickness is as follows: Where d is the equivalent icing thickness, m o f is the initial mass per unit length of the fiber-optic composite overhead ground wire. o f is the vibration frequency of the fiber optic composite overhead ground wire when it is not covered with ice. ice ρ is the vibration frequency of the fiber optic composite overhead ground wire when it is covered with ice. ice The density of the ice layer is 0.92 g / cm³. 3 r o The initial radius of the fiber optic composite overhead ground wire.

7. The online status monitoring system for fiber optic composite overhead ground wire as described in claim 1, characterized in that, The decision output module is used to calculate the maximum change in sag of the fiber optic composite overhead ground wire based on the sag, specifically including: The sag is input into a preset formula for calculating the maximum sag change, and the maximum sag change of the fiber optic composite overhead ground wire is calculated and obtained. The preset formula for calculating the maximum sag change is as follows: In the formula, Δh is the change in sag, λ is the wavelength of the probe light, and l is the distance between the two towers. This refers to the phase after the fiber optic composite overhead ground wire is iced. h0 represents the original phase of the fiber optic composite overhead ground wire, and h0 represents the sag of the fiber optic composite overhead ground wire.

8. The online status monitoring system for fiber optic composite overhead ground wire as described in claim 1, characterized in that, The information acquisition and storage module includes a high-speed acquisition card and a solid-state disk array.

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