A device for locating vibration events on power transmission lines

Abstract

This invention discloses a device for locating vibration events on power transmission lines. The device includes a pulsed laser module, an optical pulse amplifier, an optical fiber circulator, an optical fiber polarizer, a sensing optical fiber, a photodetector, a data acquisition card, and a data processing and control unit. It utilizes the optical fiber inherent in the power transmission line or a separately laid optical fiber as the sensing fiber. While the optical pulse propagates in the sensing fiber, it generates a Rayleigh scattering signal. Vibration events on the power transmission line disturb the polarization state and phase of the Rayleigh scattering signal, resulting in a significant difference in noise convergence in the obtained optical time-domain reflectometry curve before and after the location of the induced vibration on the sensing fiber. Therefore, the location is determined by identifying the convergence start point. This device is suitable for locating external vibration sources on quasi-static power transmission lines and has advantages such as long monitoring coverage distance, high positioning accuracy, and low false alarm rate.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power sensing, and particularly relates to a power transmission line vibration event positioning device. BACKGROUND

[0002] With the rapid development of municipal construction in China, illegal construction, barbaric construction and the like will continue to pose a great threat to power transmission lines. Therefore, real-time or quasi-real-time online monitoring and intelligent operation and maintenance of power transmission lines are important issues for the power industry. The power industry itself has abundant fiber resources, and fiber optic ground wires, phase lines and self-supporting cables are widely used in power transmission, distribution and use environments. Therefore, using optical fibers as a sensing medium has natural advantages in developing optical fiber sensors. Moreover, optical fibers have the characteristics of being passive, anti-electromagnetic interference, corrosion-resistant, high-temperature-resistant, light in weight and easy to lay, and are widely used in power equipment and facility sensing applications. At present, external damage accounts for a large proportion of factors in power transmission line faults, but the fault source is usually found after the occurrence of the line fault, and it is impossible to achieve pre-accident warning and prevention. In particular, after the accident, it is difficult to locate the fault point, and it is impossible to quickly locate the fault and quickly restore the power supply of the line. At present, the conductive characteristics of the power transmission line are often used for positioning, such as the direct current impulse method, which uses a ball gap discharge to generate a pulse voltage. The voltage generates a multi-spectrum discharge current, sound, light and magnetic field at the insulation damage site, and then the discharge signals are detected on site to accurately locate the fault point. However, this method is easily disturbed by the environment of the power transmission line, and the actual operation process is relatively complex.

[0003] With the continuous development of optical fiber sensing technology, power transmission and operation gradually use optical fiber sensors to monitor the body and environmental parameters of the transmission line, such as voltage, current, temperature, partial discharge, humidity, vibration, etc. Among them, the optical fiber sensor for monitoring the external damage of the transmission line is currently rapidly popularized and applied. The granted invention patent "Optical fiber vibration sensor and application thereof in transmission line wind vibration monitoring system" (application number: CN201310542441.X, application date: 2013-11-05) proposes a kind of optical fiber composite overhead transmission line vibration sensor based on optical fiber grating sensing technology, that is, using optical fiber grating in series in optical fiber composite overhead line, using spectrum demodulation method to obtain line vibration information. This method is a kind of multi-point or quasi-distributed sensing method, but the optical fiber grating is arranged at special nodes, such as optical fiber joint box, and the monitoring coverage is very limited. The invention patent "Transmission line vibration online monitoring system" (application number: CN202010376693.X, application date: 2020-05-07) sets up a vibration sensor on the transmission line, and transmits the vibration data through the wireless communication module to realize the monitoring of the line vibration. This method needs to power the sensor and network, and to realize full-line high-density monitoring coverage, the number of sensing nodes must be increased, and the network and data communication face difficulties. In view of the above shortcomings, the present application is based on the distributed optical fiber sensing technology architecture, based on the disturbance influence of vibration event on the polarization and phase of optical signal in optical fiber, and a new transmission line vibration event positioning device is proposed. SUMMARY

[0004] In view of the shortcomings of the prior art, the present application proposes a transmission line vibration event positioning device, which modulates the phase and polarization state of Rayleigh signal in the sensing optical fiber according to the vibration event, so that the convergence characteristics of the optical time domain reflection curve change sharply before and after the vibration position, and then the vibration event positioning is realized by judging the convergence starting position.

[0005] The application discloses a transmission line vibration event positioning device, characterized in that the device comprises a pulse laser module, an optical pulse amplifier, an optical fiber circulator, an optical fiber polarizer, a sensing optical fiber, a photoelectric detector, a data acquisition card, a data processing and controller.

[0006] The data processing and controller controls the data acquisition card, so that the data acquisition card outputs an electric pulse signal.

[0007] The electric pulse signal is connected to the pulse laser module to drive the pulse laser module to output an optical pulse.

[0008] The light pulse accesses the optical pulse amplifier, the peak power of the output light pulse is raised by the optical pulse amplifier, and the light pulse enters from the 1 port of the optical fiber circulator, is output from the 2 port of the optical fiber circulator, and then accesses the sensing optical fiber through the optical fiber polarizer;

[0009] The light pulse transmits in the sensing optical fiber, and a back Rayleigh scattering signal is generated; the back Rayleigh scattering signal is input from the 2 port of the optical fiber circulator through the optical fiber polarizer, and is output from the 3 port of the optical fiber circulator to the photodetector;

[0010] The photodetector converts the back Rayleigh scattering signal into a voltage signal; the voltage signal is collected by the data acquisition card and converted into an optical time domain reflection signal voltage data with time and voltage amplitude information;

[0011] The data acquisition card has a data accumulation function, the data processing and controller sets the accumulation times, the data acquisition card collects the optical time domain reflection signal voltage data of the corresponding continuous measurement period according to the accumulation times set by the data processing and controller, and performs addition operation on the collected optical time domain reflection signal voltage data, and transmits the optical time domain reflection signal voltage data obtained after the addition operation to the data processing and controller, and then starts the next data acquisition, accumulation and data transmission;

[0012] The data processing and controller processes the optical time domain reflection signal voltage data by using a vibration event discrimination and positioning algorithm, and then locates the vibration event.

[0013] Preferably, the vibration event discrimination and positioning algorithm comprises the following steps:

[0014] 1) performing average operation on the optical time domain reflection signal voltage data transmitted by the data acquisition card to obtain the optical time domain reflection signal voltage data after average operation;

[0015] 2) selecting a 20-length subarray data at the end of the optical time domain reflection voltage array data after average operation, which avoids the position of the Rayleigh scattering peak of the optical fiber;

[0016] 3) calculating the mean value, maximum value and minimum value of the subarray data; taking the absolute value of the difference between the maximum value and the mean value, and taking the absolute value of the difference between the minimum value and the mean value, and taking the larger one as a reference value; dividing the reference value by the mean value, and taking the result as a discrimination value; if the discrimination value is less than a predetermined threshold value, it is determined that there is a vibration event in the power transmission line, otherwise, it is determined that there is no vibration event in the power transmission line;

[0017] 4) if it is determined that the power transmission line has a vibration event, recording the ordinal number of the first element of the sub-array data in the average operation of the optical time domain reflection voltage array data as a calibration ordinal number, dividing the array element corresponding to the ordinal number before the calibration ordinal number by the array element corresponding to the calibration ordinal number to obtain a positioning reference value;

[0018] If the positioning reference value is not in the positioning value range, then the calibration ordinal number is reduced by 1 as a new calibration ordinal number, and the array element corresponding to the ordinal number before the new calibration ordinal number is divided by the array element corresponding to the new calibration ordinal number to obtain a new positioning reference value;

[0019] If the positioning reference value is in the positioning value range, then the calibration ordinal number at this time is determined as the position calibration ordinal number, and the position corresponding to the position calibration ordinal number corresponds to the position of the vibration event;

[0020] 5) calculating the sensing optical fiber distance position corresponding to the vibration event position according to the position calibration ordinal number.

[0021] Preferably, the pulsed laser module selects a pulsed light laser directly driven by a pulsed current.

[0022] Preferably, the pulsed laser module selects a combination module of a continuous light laser and a light pulse modulator.

[0023] Preferably, the spectral line width of the laser output by the pulsed laser module is less than 10 MHz.

[0024] Preferably, the pulse width and period of the electric pulse are set in the data processing and controller, and the data acquisition card outputs an electric pulse signal.

[0025] Preferably, the maximum data accumulation number of the data acquisition card is not less than 1024 times.

[0026] Preferably, the predetermined threshold value is 0.005.

[0027] Preferably, the positioning value range is less than 0.97 or greater than 1.03.

[0028] Preferably, the optical fiber distance position corresponding to the vibration position is obtained by dividing the position calibration ordinal number by the sampling rate of the data acquisition card, multiplying the propagation speed of the light pulse in the sensing optical fiber, and dividing by 2.

[0029] Compared with the prior art, the present application has the following advantages:

[0030] 1. The present application directly uses an optical fiber as a sensing medium, has the advantages of being passive, anti-electromagnetic interference, corrosion-resistant, high-temperature-resistant, and easy to lay, and can overcome the disadvantages of traditional electronic sensors and wireless sensors, such as power supply difficulties, complex networking, many sensing nodes, and difficult node arrangement;

[0031] 2、The application adopts the way of modulating the phase and polarization state of Rayleigh scattering signal in the optical fiber by external vibration event to quickly reduce the fading noise in the optical time domain reflection curve, and uses the average way to suppress the influence of phase and polarization state randomness, thereby effectively improving the discrimination accuracy and positioning precision of vibration event on the transmission line, and having the advantages of long monitoring coverage distance, high positioning precision, low false alarm rate, etc. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 It is a structure schematic diagram of a transmission line vibration event positioning device of the embodiment;

[0033] Figure 2 It is a voltage data schematic diagram of the optical time domain reflection signal;

[0034] Figure 3 It is a voltage data schematic diagram of the optical time domain reflection signal after averaging;

[0035] Figure 4 It is a subarray selection schematic diagram for avoiding the Rayleigh scattering peak position of the optical fiber;

[0036] Figure 5 It is a sequence number selection schematic diagram;

[0037] Figure 6 It is a vibration positioning schematic diagram based on the position sequence number.

[0038] Numerals in the figure represent:

[0039] 101-pulse laser module; 102-optical pulse amplifier; 103-optical fiber circulator; 104-optical fiber polarizer; 105-sensing optical fiber; 106-optoelectronic detector; 107-data acquisition card; 108-data processing and controller. DETAILED DESCRIPTION

[0040] The above and other technical features and advantages of the present application will be made more apparent by the following detailed description of the application, given in connection with the attached drawings.

[0041] The embodiment provides a transmission line vibration event positioning device, as shown in Figure 1 The device includes a pulse laser module 101, an optical pulse amplifier 102, an optical fiber circulator 103, an optical fiber polarizer 104, a sensing optical fiber 105, an optoelectronic detector 106, a data acquisition card 107, and a data processing and controller 108.

[0042] The data processing and controller 108 controls the data acquisition card 107 to output an electric pulse signal; the electric pulse signal accesses the pulse laser module 101 to drive the pulse laser module 101 to output a light pulse; the pulse laser module 101 selects a pulse light laser directly driven by a pulse current, and the laser spectral line width is 3 MHz.

[0043] The light pulse accesses the light pulse amplifier 102, the light pulse amplifier 102 enhances the peak power of the output light pulse, enters the 1 port of the optical fiber ring 103, and then is output from the 2 port of the optical fiber ring 103, and then accesses the sensing optical fiber 105 through the optical fiber polarizer 104.

[0044] The light pulse transmits in the sensing optical fiber 105, and at the same time generates a backscattering Rayleigh scattering signal; the backscattering Rayleigh scattering signal is input through the optical fiber polarizer 104 and the 2 port of the optical fiber ring 103, and is output from the 3 port of the optical fiber ring 103 to the photodetector 106; the photodetector 106 selects an avalanche photodetector.

[0045] The photodetector 106 converts the backscattering Rayleigh scattering signal into a voltage signal; the voltage signal is collected by the data acquisition card 107 and converted into an optical time domain reflection signal voltage data with time and voltage amplitude information, as shown in Figure 2 The data acquisition card 107 has a data accumulation function, and the maximum accumulation number is 65536 times, the data processing and controller 108 sets the accumulation number, the data acquisition card 107 collects the optical time domain reflection signal voltage data of the corresponding continuous measurement period according to the accumulation number set by the data processing and controller 108, and performs addition operation, transmits the optical time domain reflection signal voltage data obtained after the addition operation to the data processing and controller 108, and then performs next data collection, accumulation and data transmission.

[0046] The data processing and controller 108 processes the optical time domain reflection signal voltage data by using a vibration event discrimination and positioning algorithm, and then locates the vibration event;

[0047] The vibration event discrimination and positioning algorithm includes the following steps:

[0048] 1) The optical time domain reflection signal voltage data transmitted by the data acquisition card 107 is subjected to average operation to obtain an average optical time domain reflection signal voltage array data, as shown in Figure 3

[0049] 2) In the average optical time domain reflection voltage array data, a 20-length subarray data avoiding the position of the optical fiber Rayleigh scattering peak at the end is selected, as shown in​Figure 4 as shown;

[0050] 3) Calculate the mean, maximum and minimum of the sub-array data; take the absolute value of the difference between the maximum and minimum and the mean, respectively, and take the larger one as the reference value; then divide the reference value by the mean to obtain the discrimination value; if the discrimination value is less than a predetermined threshold value, which is set to 0.005, it is determined that there is a vibration event on the power transmission line, otherwise, it is determined that there is no vibration event on the power transmission line;

[0051] 4) If it is determined that there is a vibration event on the power transmission line, record the ordinal number of the first element of the sub-array data in the average operation of the optical time domain reflection voltage array data as the calibration ordinal number, as shown in Figure 5 The positioning reference value is obtained by dividing the array element corresponding to the ordinal number before the calibration ordinal number by the array element corresponding to the calibration ordinal number;

[0052] If the positioning reference value is not within the positioning value range, which is set to be less than 0.97 and greater than 1.03, the calibration ordinal number is reduced by 1 to obtain a new calibration ordinal number, and the new positioning reference value is obtained by dividing the array element corresponding to the new calibration ordinal number by the array element corresponding to the new calibration ordinal number;

[0053] If the positioning reference value falls within the positioning value range, it is determined that the calibration ordinal number at this time is the position calibration ordinal number, corresponding to the position of the vibration event;

[0054] Using the above method, the array data in Figure 3 is calculated to obtain the position calibration ordinal number 5000, and the positioning reference value at this time is 0.96, which meets the requirement of the positioning value range, so it can be determined that the position of the position calibration ordinal number is the position of the vibration event.

[0055] 5) According to the determined position calibration ordinal number, the distance position of the sensing optical fiber corresponding to the position of the vibration event is calculated. As shown in Figure 6 The distance position of the sensing optical fiber corresponding to the position of the vibration event is the position calibration ordinal number 5000 divided by the sampling rate 100 Msps of the data acquisition card 7, multiplied by the propagation speed 2×10 8 m / s of the optical pulse in the sensing optical fiber, and then divided by 2, to obtain the sensing optical fiber distance position corresponding to the position of the vibration event at 5 km.

[0056] This invention discloses a transmission line vibration event location device that utilizes the optical fiber integrated into the transmission line or a separately laid optical fiber as the sensing fiber. As the optical pulse propagates in the sensing fiber, a Rayleigh scattering signal is generated. Vibration events on the transmission line disturb the polarization state and phase of the Rayleigh scattering signal, resulting in a significant difference in noise convergence in the obtained optical time-domain reflectometry curve before and after the location of the induced vibration on the sensing fiber. The location is then determined by identifying the convergence start point. This location device is suitable for locating external vibration sources on quasi-static transmission lines and has advantages such as long monitoring coverage distance, high location accuracy, and low false alarm rate.

[0057] The above description is merely a preferred embodiment of the present invention and is illustrative rather than restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

Claims

1. A power line vibration event location device, characterized by, The device comprises a pulse laser module (101), an optical pulse amplifier (102), an optical fiber circulator (103), an optical fiber polarizer (104), a sensing optical fiber (105), a photodetector (106), a data acquisition card (107), and a data processing and controller (108). The data processing and controller (108) controls the data acquisition card (107) to output an electric pulse signal. The electric pulse signal is connected to the pulse laser module (101) to drive the pulse laser module (101) to output an optical pulse. The optical pulse is connected to the optical pulse amplifier (102) to increase the peak power of the output optical pulse, and then enters the 1 port of the optical fiber circulator (103) and is output from the 2 port of the optical fiber circulator (103), and then enters the sensing optical fiber (105) through the optical fiber polarizer (104). The optical pulse is transmitted in the sensing optical fiber (105) to generate a back Rayleigh scattering signal, which is input from the 2 port of the optical fiber circulator (103) through the optical fiber polarizer (104) and output from the 3 port of the optical fiber circulator (103) to the photodetector (106). The photodetector (106) converts the back Rayleigh scattering signal into a voltage signal, which is collected by the data acquisition card (107) and converted into an optical time domain reflectometry voltage data with time and voltage amplitude information. The data acquisition card (107) has a data accumulation function, and the data processing and controller (108) sets the number of accumulations. The data acquisition card (107) collects the optical time domain reflectometry voltage data of the corresponding continuous measurement period according to the number of accumulations set by the data processing and controller (108), and performs addition operation on the collected optical time domain reflectometry voltage data. The optical time domain reflectometry voltage data obtained after the addition operation is transmitted to the data processing and controller (108), and then the next data collection, accumulation and data transmission are performed. The data processing and controller (108) processes the optical time domain reflectometry voltage data by using a vibration event discrimination and positioning algorithm, and then locates the vibration event. The vibration event discrimination and positioning algorithm comprises the following steps: 1) performing average operation on the multiple groups of optical time domain reflectometry voltage data transmitted by the data acquisition card (107) to obtain an array data of the optical time domain reflectometry voltage data after the average operation; 2) selecting a 20-length subarray data from the end of the optical time domain reflectometry voltage array data after the average operation, which avoids the position of the Rayleigh scattering peak of the optical fiber. 3) calculating the mean value, maximum value and minimum value of the sub-array data, taking the absolute value of the difference between the maximum value and the mean value and the difference between the minimum value and the mean value, and taking the larger one as the reference value; dividing the reference value by the mean value to obtain the discrimination value; if the discrimination value is less than a predetermined threshold value, it is determined that the power transmission line has a vibration event, otherwise, it is determined that the power transmission line does not have a vibration event; 4) if it is determined that the power transmission line has a vibration event, recording the ordinal number of the first element of the sub-array data in the average operation of the optical time domain reflection voltage array data as the calibration ordinal number, dividing the array element corresponding to the ordinal number before the calibration ordinal number by the array element corresponding to the calibration ordinal number to obtain the positioning reference value; if the positioning reference value is not in the positioning value range, reducing 1 from the calibration ordinal number as a new calibration ordinal number, dividing the array element corresponding to the ordinal number before the new calibration ordinal number by the array element corresponding to the new calibration ordinal number to obtain a new positioning reference value; if the positioning reference value is in the positioning value range, it is determined that the calibration ordinal number at this time is the position calibration ordinal number, and the position corresponding to the position calibration ordinal number is the position of the vibration event; 5) calculating the sensing optical fiber distance position corresponding to the vibration event position according to the position calibration ordinal number.

2. A power line vibration event location device according to claim 1, characterised in that, The pulse laser module (101) selects a pulse light laser directly driven by a pulse current.

3. A power line vibration event locator according to claim 1, wherein, The pulse laser module (101) selects a combination module of a continuous light laser and a light pulse modulator.

4. A power line vibration event locator according to claim 1, wherein, The laser spectral line width output by the pulse laser module (101) is less than 10 MHz.

5. A power line vibration event locator according to claim 1, wherein, The pulse width and period of the electric pulse are set in the data processing and controller (108), and the data acquisition card (107) outputs an electric pulse signal.

6. A power line vibration event locator according to claim 1, wherein, The maximum data accumulation number of the data acquisition card (107) is not less than 1024 times.

7. A power line vibration event locator device according to claim 1, wherein, The predetermined threshold value is 0.

005.

8. A power line vibration event locator device according to claim 1, wherein, The positioning value range is less than 0.97 or greater than 1.

03.

9. A power line vibration event locator apparatus according to claim 1, wherein, The optical fiber distance position corresponding to the vibration event position is obtained by dividing the position calibration ordinal number by the sampling rate of the data acquisition card (107), multiplying the propagation speed of the light pulse in the sensing optical fiber, and then dividing by 2.

Images