CN113639961A - OPGW (optical fiber composite overhead ground wire) optical cable lightning stroke positioning monitoring method, system, device, equipment and medium - Google Patents
OPGW (optical fiber composite overhead ground wire) optical cable lightning stroke positioning monitoring method, system, device, equipment and medium Download PDFInfo
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Abstract
The invention provides a method, a system, a device, equipment and a medium for positioning and monitoring lightning stroke of an OPGW (optical fiber composite overhead ground wire) optical cable, wherein the method comprises the following steps: acquiring central wavelengths of array gratings on distributed optical fibers in an OPGW optical cable at different moments before and after a lightning stroke event occurs; calculating temperature coefficients at different grating positions in the array grating according to the variable quantities of the central wavelength at different moments; calculating the temperature rise rate of different grating positions on the OPGW optical cable according to the temperature coefficient; and positioning the lightning stroke event occurrence position according to the temperature rise rates of different grating positions on the OPGW optical cable. The method carries out full-time global lightning strike positioning monitoring on the operation of the OPGW optical cable, and provides a solution for the hidden trouble of the operation of the OPGW optical cable caused by lightning strike. The method for detecting the state of the OPGW optical cable can detect the fault, the sub-health state and the health state of the OPGW optical cable.
Description
Technical Field
The invention relates to the technical field of wireless communication, in particular to a method, a system, a device, equipment and a medium for positioning and monitoring OPGW (optical fiber composite overhead ground wire) optical cable lightning stroke.
Background
The distributed optical fiber has the advantages of long detection distance, high sensitivity, high environmental adaptability, strong anti-electromagnetic interference capability and the like, and is widely applied to monitoring scenes such as fire alarm, perimeter security protection, object deformation and the like.
Meanwhile, the optical fiber composite overhead ground wire integrates an optical fiber communication function and a power transmission line lightning protection function, and is an important development direction of special electric power optical cables. With the construction of optical fiber communication networks of power systems, optical fiber composite overhead ground wires are beginning to be adopted on a large scale. Due to the functional definition of the OPGW optical cable, the strong tensile resistance and the conductor property are both considered, the OPGW optical cable runs in a complex natural environment for a long time, once lightning strike occurs, the instantaneous high temperature can cause the OPGW optical cable to be locally carbonized, and strand breakage and even whole cable breakage occur. The lightning stroke phenomenon is random, after the lightning stroke, the concealment is strong, and the long running distance of the OPGW optical cable is an important influence factor of the positioning hidden trouble. Therefore, research on positioning the OPGW optical cable lightning strike points by using the distributed optical fiber technology has instructive significance for solving the potential safety hazards of the OPGW optical cable.
At present, an OPGW optical cable is positioned by lightning strike, and no effective technical means exists. The location after a lightning strike is typically determined by transmission line inspection (telescope or drone).
Disclosure of Invention
Aiming at the problem that once the optical fiber composite overhead ground wire (OPGW optical cable for short) is struck by lightning in the operation process, huge hidden danger is caused, the invention provides a lightning strike positioning and monitoring method, a system, a device, equipment and a medium for the OPGW optical cable.
In order to achieve the purpose, the invention adopts the following technical scheme:
an OPGW optical cable lightning stroke positioning and monitoring method comprises the following steps:
acquiring central wavelengths of array gratings on distributed optical fibers in an OPGW optical cable at different moments before and after a lightning stroke event occurs;
calculating temperature coefficients at different grating positions in the array grating according to the variable quantities of the central wavelength at different moments; calculating the temperature rise rate of different grating positions on the OPGW optical cable according to the temperature coefficient;
and positioning the lightning stroke event occurrence position according to the temperature rise rates of different grating positions on the OPGW optical cable.
As a further improvement of the invention, the distributed optical fiber is arranged in the tubular structure, the excess length of the optical fiber of the tubular structure is controlled to form a sensing composite unit, and the distributed optical fiber is twisted with other optical units of the OPGW optical cable and metal single wires and is laid with the OPGW optical cable in a whole line.
As a further improvement of the present invention, before acquiring the central wavelengths of the array grating lightning strike events on the distributed optical fiber in the OPGW optical cable at different times before and after occurrence, the method further includes:
calibrating the relative position of the array grating of the distributed optical fiber in the OPGW optical cable, and matching the gratings at different positions in the array grating with the actual position of the OPGW optical cable; and then collecting the central wavelength of each grating at different moments before and after the occurrence of each lightning stroke event in real time.
As a further improvement of the present invention, the calculating the temperature coefficients at different grating positions in the array grating according to the variation of the center wavelength at different times includes:
calibrating the initial wavelength of OPGW optical cable, t1Time as reference position of wavelength of each grating, using λ1、λ2......λnRepresents;
real-time acquisition of t2Wavelength of time of day by λt1,λt2.......λtnIndicates that t is1To t2The wavelength change rate at that time is:
mapping the collected wavelength variation to the variation of temperature to obtain the temperature coefficient KTThe specific method comprises the following steps:
KT＝η·Kλ
wherein eta is the wavelength variation and the temperature variation conversion coefficient.
As a further improvement of the present invention, the temperature rise rate at different grating positions on the OPGW optical cable is calculated by using the temperature coefficient, and specifically:
and calculating the temperature rise rate of each grating position by adopting a temperature rise rate model, wherein the temperature rise rate model is as follows:
wherein, VTFor the demodulated temperature rise rate, F is a temperature rise model function, Q is the lightning stroke discharge amount, t is the lightning stroke discharge time, etarFor the efficiency of lightning temperature conduction, KTIs the temperature coefficient; Δ t is the time for which the temperature rises to the maximum value at room temperature.
As a further improvement of the invention, the method also comprises the following steps:
obtaining the optical signal return time corresponding to the grating at the lightning stroke event occurrence position by utilizing a time division multiplexing mechanism;
and calculating the distance of the lightning stroke event occurrence position according to the optical signal return time.
As a further improvement of the present invention, the distance of the occurrence position of the lightning stroke event is calculated by using the optical signal return time, and the specific method is as follows:
obtaining the grating distance according to the relational expression of the optical signal return time and the grating position, wherein the relational expression is as follows:
τi＝2neffLi/c
wherein, tauiFor the return time of the optical signal, LiIs the distance of the ith grating from the circulator, neffIs a grating fiber core havingThe change in effective refractive index, c is the speed of light;
the grating distance is the distance of the position where the lightning stroke event occurs.
An OPGW optical cable lightning stroke positioning monitoring system, comprising:
the acquisition module is used for acquiring the central wavelengths of the array grating lightning stroke events on the distributed optical fiber in the OPGW optical cable at different moments before and after the occurrence of the array grating lightning stroke events;
the calculation module is used for calculating temperature coefficients at different grating positions in the array grating according to the variable quantities of the central wavelength at different moments; calculating the temperature rise rate of different grating positions on the OPGW optical cable according to the temperature coefficient;
and the positioning module is used for positioning the lightning stroke event occurrence position according to the temperature rise rates of different grating positions on the OPGW optical cable.
An OPGW optical cable lightning stroke positioning and monitoring device comprises:
the sensing unit at least comprises a distributed optical fiber, and the distributed optical fiber collects the central wavelength of reflected light;
the fiber grating demodulator is used for acquiring the central wavelengths at different moments and demodulating the central wavelengths;
and the upper computer comprises the OPGW optical cable lightning stroke positioning monitoring system and outputs OPGW optical cable lightning stroke positioning monitoring information.
An OPGW optical cable lightning stroke positioning and monitoring device comprises:
the sensing unit at least comprises a distributed optical fiber, and the distributed optical fiber collects the central wavelength of reflected light;
the fiber grating demodulator is used for demodulating the acquired wavelength;
and the upper computer analyzes and processes the demodulated signals and outputs OPGW (optical fiber composite overhead ground wire) optical cable lightning stroke positioning monitoring information.
An electronic device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, the processor implementing the steps of the OPGW optical cable lightning strike location monitoring method when executing the computer program.
A computer readable storage medium storing a computer program which, when executed by a processor, implements the steps of the OPGW optical cable lightning strike location monitoring method.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a lightning stroke positioning and monitoring method based on a distributed optical fiber OPGW (optical fiber composite overhead ground wire) optical cable aiming at the problems of potential safety hazards caused by lightning stroke of the OPGW optical cable in a complex environment and the limitation of the existing lightning stroke positioning technology. The state detection method of the OPGW optical cable can detect the fault, the sub-health state and the health state of the OPGW optical cable; the method can detect the OPGW optical cable in a transport OPGW and an OPGW optical cable in a test room.
Drawings
FIG. 1 is a schematic flow chart of a OPGW optical cable lightning stroke positioning monitoring method of the invention;
fig. 2 is a schematic structural diagram of an OPGW optical cable of a sensing unit combined with a distributed optical fiber according to an embodiment of the present invention;
FIG. 3 is a frame diagram of an OPGW optical cable lightning strike location system;
FIG. 4 is a schematic demodulation diagram of OPGW optical cable positioning based on distributed optical fiber sensing;
FIG. 5 is a schematic diagram of a distributed optical fiber lightning strike location principle;
FIG. 6 is a schematic view of a distributed optical fiber lightning strike location process;
FIG. 7 is a schematic diagram of an exemplary lightning strike discharge model;
FIG. 8 is a schematic structural view of an OPGW optical cable lightning strike positioning and monitoring system of the present invention;
fig. 9 is a schematic structural diagram of an electronic device according to the present invention.
Wherein, 10 is an OPGW optical cable, 11 is a double-core sensing unit, 12 is an aluminum clad steel wire, and 13 is a mixed light unit; 21 is an optical fiber jumper, and 22 is an optical fiber grating demodulator; 23 is a network cable, 24 is an upper computer, 25 is a laser, 26 is a circulator, 27 is a narrow-wide filter, 28 is a photoelectric detector, 29 is a high-speed data acquisition device, 30 is a pulse modulation module, 31 is an EDFA, 32 is a pulse signal generator, 33 is an FPGA, and 34 is a delay module and a starting acquisition device.
Detailed Description
The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.
The following detailed description is exemplary in nature and is intended to provide further details of the invention. Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention.
The noun explains:
(1) the OPGW Optical cable is an Optical Fiber Composite Overhead Ground Wire (OPGW Optical cable), Optical fibers are placed in the Ground Wire of an Overhead high-voltage power transmission line to form an Optical Fiber communication network on the power transmission line, and the structural form has the double functions of Ground Wire and communication and is generally called as an OPGW Optical cable.
(2) Distributed optical fiber: the grating inscribed in the optical fiber is used as a sensing unit, and the optical fiber is used as a carrier for information transmission, so that the optical fiber has double functions of sensing and signal transmission. The grating and the optical fiber are arranged at intervals to form an array grating structure.
Aiming at the problems of potential safety hazards caused by lightning strike of an optical fiber composite overhead ground wire (OPGW optical cable for short) in a complex environment and the limitation of the existing lightning strike positioning technology, the invention provides a distributed optical fiber OPGW optical cable lightning strike positioning and monitoring method, which is used for carrying out full-time global lightning strike positioning and monitoring on the operation of the OPGW optical cable and provides a solution for the hidden operation danger of the OPGW optical cable caused by the lightning strike.
As shown in fig. 1, a first object of the present invention is to provide an OPGW optical cable lightning strike location monitoring method, including the following steps:
acquiring central wavelengths of array gratings on distributed optical fibers in an OPGW optical cable at different moments before and after a lightning stroke event occurs;
calculating temperature coefficients at different grating positions in the array grating according to the variable quantities of the central wavelength at different moments; calculating the temperature rise rate of different grating positions on the OPGW optical cable according to the temperature coefficient;
and positioning the lightning stroke event occurrence position according to the temperature rise rates of different grating positions on the OPGW optical cable.
The method is based on a distributed optical fiber OPGW optical cable lightning stroke positioning monitoring method, the temperature rate is obtained through the change of the central wavelength before and after the occurrence of the lightning stroke event, whether the lightning stroke event occurs is judged according to the temperature rate, and positioning is carried out according to the position of a grating at the position where the temperature rate changes. However, the method can only be located at a specific grating, and cannot obtain the distance of occurrence of a specific lightning stroke event.
The method for acquiring the real-time signal on the distributed optical fiber in the OPGW optical cable specifically comprises the following steps:
calibrating the relative position of an array grating of distributed optical fibers in the OPGW optical cable so as to match the actual positions of the grating and the OPGW optical cable; and then collecting the central wavelength of the reflected light of each grating in real time.
As a preferred embodiment, the distributed optical fiber is placed in a tubular structure, the excess length of the optical fiber of the tubular structure is controlled to form a sensing composite unit, and the distributed optical fiber is twisted with other optical units of the OPGW optical cable and metal single wires and is laid with the OPGW optical cable in a full-line mode.
As a preferred embodiment, further comprising:
obtaining the optical signal return time corresponding to the grating at the lightning stroke event occurrence position by utilizing a time division multiplexing mechanism;
and calculating the distance of the lightning stroke event occurrence position according to the optical signal return time.
The method comprises the following steps of calculating the distance of the lightning stroke event occurrence position according to the optical signal return time, and specifically comprises the following steps:
and obtaining the grating distance according to the relational expression between the optical signal return time and the grating position, wherein the grating distance is the distance of the lightning stroke event occurrence position.
The step is combined with the grating position for positioning, and the distance of the specific lightning stroke event occurrence position can be calculated.
The invention provides a distributed optical fiber OPGW (optical fiber composite overhead ground wire) optical cable lightning stroke positioning and monitoring method, which comprises the following steps of:
(1) the distributed optical fiber is arranged in the OPGW optical cable in the same structure mode of the communication optical cable to form an independent optical sensing unit as a distributed sensing physical device;
and (3) independently forming a sensing unit by utilizing distributed optical fiber sensing and using the sensing unit and the OPGW optical cable as a twisting unit together to establish a lightning stroke temperature positioning model for realizing the real-time positioning of a lightning stroke point.
(2) Calibrating the relative position of the sensing grating in the OPGW optical cable, and matching the actual positions of the grating and the OPGW optical cable in a metric scale;
(3) a double-unit sensing mechanism is adopted to carry out a wavelength drift verification mode of lightning stroke point positions;
as a preferred embodiment, the OPGW optical cable has two sensing units, where a first sensing unit is the distributed optical fiber, a second sensing unit is a communication optical fiber, and the two sensing units are laid out in a full line on the OPGW optical cable.
(4) Establishing a temperature positioning model about lightning stroke OPGW optical cable heat conduction;
(5) and the lightning stroke positioning mechanism of the OPGW optical cable with double parameters is set, so that the lightning stroke positioning of the OPGW optical cable is realized.
The invention utilizes the distributed optical fiber sensing technology as a distributed sensing mode, forms a sensing unit and an OPGW optical cable together as a twisting unit independently, and establishes a lightning stroke temperature positioning model, thereby realizing the real-time positioning of lightning stroke points.
Specifically, as an OPGW optical cable with a sensing function, a stainless steel material is made into a tubular structure, a distributed optical fiber is placed in the tubular structure, the excess length of the optical fiber in the tube is controlled to form a sensing composite unit, and the sensing composite unit is twisted with other optical units and metal single wires.
Furthermore, in order to ensure that the distributed optical fibers in the distributed optical fiber sensing unit in the OPGW optical cable are not influenced by stress, the sensing unit reserves a proper extra length. Therefore, the OPGW optical cable is combined with the distributed optical fiber sensing unit, which means that full-line laying of monitoring of the OPGW optical cable line is achieved at the physical sensor level. In the lightning stroke monitoring of the OPGW optical cable, a wavelength demodulation based on distributed optical fiber, a time division multiplexing based distributed optical fiber and a lightning stroke temperature model matching mechanism are adopted. The principle is that firstly, the OPGW optical cable integrated into the optical fiber sensing unit realizes physical position matching in the distributed optical fiber sensing principle on the premise of not changing the attribute of the OPGW optical cable, and the occurrence of a lightning stroke event is positioned algorithmically through an OPGW optical cable lightning stroke wavelength demodulation model.
Preferably, the step (1) is based on a distributed optical fiber sensing unit OPGW optical cable, wherein a core of the dual-core sensing unit 11 is a distributed optical fiber, and a core of the sensing unit is a common communication optical fiber, and the ribbon is structured. The structure of the distributed optical fiber cable is strengthened, and the influence of stress on the distributed optical fiber is eliminated.
The change of the external temperature can cause the temperature change of the grating material, the grating period of the fiber grating and the effective refractive index of the fiber core can change due to the thermo-optic effect and the thermal expansion effect, and the central wavelength of the reflected light of the fiber grating can also change accordingly. Assuming that the fiber grating is only affected by temperature change, the period of the grating changes due to thermal expansion effect, and the change amount is expressed as:
ΔΛ＝α·Λ·ΔT (1)
in the formula:
delta lambda is the change amount of the distributed fiber grating;
alpha is the thermal expansion coefficient of the grating, and is a material intrinsic parameter only related to the material per se, namely a constant;
Δ T is the amount of change in the outside temperature.
The effective refractive index of the grating is also changed due to the thermo-optic effect, and the change quantity is as follows:
Δneff＝neff·ξ·ΔT (2)
in the formula:
neffis the change of the effective refractive index of the grating fiber core;
xi is the coefficient of thermal expansion of the grating, and the parameter is also the intrinsic parameter of the material and is a constant;
Δ T is the amount of change in the outside temperature.
Substitution of formula 2 into formula 1 can result:
in the formula ofBAnd a and xi are all intrinsic parameters of the fiber grating, namely constants.
Let KT＝(a+ξ)λBI.e. the temperature coefficient is substituted for formula 3
ΔλB＝KTΔT (4)
The coefficient of the change of the central wavelength of the reflected light of the array grating and the change of the outside temperature is K according to the formula 4TWhen the central wavelength of the reflected light is detected to change by using a distributed optical fiber temperature demodulation system, the linear relation of (A) is determined by a temperature coefficient KTThe variation of the external temperature can be obtained, and the actual temperature value can be calculated according to the calibrated initial temperature.
Further, in the step (4), the time of lightning stroke is usually 50-100 microseconds, the lightning stroke discharge amount is strong in randomness, and the data shows that the natural lightning stroke discharge amount is generally lower than 200C (coulomb), the method is applied in the range, and the temperature rise model is as follows:
wherein, VTFor the demodulated temperature rise rate, F is a temperature rise model function, and the lightning stroke discharge quantity Q, the lightning stroke discharge time t and the lightning stroke temperature conduction efficiency etarWavelength and temperature coefficient KTIt is related. And delta t is the time length of the temperature rising to the maximum value at normal temperature, the process is the qualitative analysis of the lightning stroke event, and for the lightning stroke positioning analysis, the real OPGW optical cable lightning stroke positioning is realized by combining the physical positioning.
Specifically, as shown in fig. 5, after a lightning strike occurs, if the lightning strike strikes the grating i of the sensing fiber in the OPGW optical cable, the temperature at the grating i changes, and the temperature of other gratings does not change or changes very little, so the position of the grating where the temperature change (or the change is the largest) is considered to be the position of the lightning strike, and the position can be determined according to τi＝2neffLiAnd/c calculating the specific position.
Further, the distributed optical fiber is applied to OPGW optical cable lightning stroke positioning monitoring, and optical signal return time corresponding to the optical grating at the position where the lightning stroke event occurs is obtained by utilizing a time division multiplexing mechanism; and calculating the distance of the lightning stroke event occurrence position according to the optical signal return time.
The method comprises the following steps of calculating the distance of the lightning stroke event occurrence position according to the optical signal return time, and specifically comprises the following steps:
obtaining the grating distance according to the relational expression of the optical signal return time and the grating position, and satisfying the following formula:
τi＝2neffLi/c
wherein, according to the return time tau of the optical signaliThe location of the event can be determined, as in the OTDR system, LiThe distance between the ith grating and the circulator, and c is the speed of light.
The grating distance is the distance of the position where the lightning stroke event occurs.
Therefore, the invention is based on the distributed optical fiber OPGW optical cable lightning stroke positioning method, firstly, a mathematical model related to a lightning stroke event is established through an OPGW optical cable lightning stroke test, the mathematical model is the OPGW optical cable lightning stroke qualitative analysis, and secondly, the positioning of the physical lightning stroke is realized by adopting a time division multiplexing mechanism and combining the judgment condition of the qualitative analysis.
Examples
The distributed optical fiber sensing device is based on a plurality of tests, in the embodiment, the distributed optical fiber adopts a single tube penetrating structure, the extra length is ensured, and the sensing optical fiber is in a normal sensing state to a certain extent. In the embodiment, the main parameters of the composite distributed optical fiber are as follows:
| OPGW optical cable model | OPGW fiber optic cable-30B 1-113[ 136; 56.6] |
| Single weight (kg/km) | 802 |
| Excess length (%) | 0.6 |
| Rated breaking force RTS (kN) | 136 |
| Diameter (mm) | 15 |
Fig. 2 is a schematic structural diagram of an OPGW optical cable combined with a distributed optical fiber sensing unit, and a main structure of the OPGW optical cable is consistent with that of a conventional OPGW optical cable, so that mechanical, electrical and environmental properties of the OPGW optical cable are guaranteed. Meanwhile, the OPGW optical cable has the functions of communication and lightning protection, and the sensing is used as a third function basis for the application of the OPGW optical cable.
Accordingly, the second object of the present invention is to provide an OPGW optical cable lightning strike location monitoring device, including:
the sensing unit at least comprises a distributed optical fiber, and the distributed optical fiber collects the central wavelength of reflected light;
the fiber grating demodulator is used for demodulating the acquired wavelength;
and the upper computer analyzes and processes the demodulated signals and outputs OPGW (optical fiber composite overhead ground wire) optical cable lightning stroke positioning monitoring information.
In the embodiment, fig. 3 is a system diagram of an OPGW optical cable lightning stroke positioning method, and the whole system is composed of three parts, namely, an OPGW optical cable 10, a grating array demodulator 22 and an upper computer 24. The grating pitch of the distributed optical fiber used for the lightning strike positioning test is 10cm, and the high-density grating distribution type can fully cover and respond to the position of a lightning strike point.
Further, the grating array demodulator 22 is used as a demodulation device for the signal of the distributed optical fiber, and realizes the demodulation process from the optical signal to the electrical signal, and finally to the digital signal. The digital signals are finally uploaded to the upper computer 24 through a network to be analyzed and processed according to a specific mechanism, and positioning information is output to achieve the OPGW optical cable lightning stroke positioning application function.
The grating array demodulator 22 is a commonly used demodulation device, and is connected to the sensing optical cable of the OPGW optical cable 10 through an optical fiber jumper 21, and the other end of the grating array demodulator 22 is connected to an upper computer 24 through a network cable 23.
As shown in fig. 3, the internal structure of the grating array demodulator 22 is:
the laser 25 is connected with the pulse modulation module 30, the pulse modulation module 30 is connected with the EDFA 31, the circulator 26 is connected with the EDFA 31, and the circulator 26 is connected with the OPGW optical cable 10; for transmitting laser light;
the FPGA 33 is connected with the pulse signal generator 32, and the pulse signal generator 32 is connected with the pulse modulation module 30 to provide pulse signals;
the FPGA 33 is connected with a high-speed data acquisition unit (ADC)29, the high-speed data acquisition unit 29 is connected with a photoelectric detector 28, the photoelectric detector 28 is connected with a narrow-wide filter 27, and the narrow-wide filter 27 is connected with a circulator 26 and used for acquiring grating signals.
In the examples, the figuresAnd 4, a demodulation light path diagram applied to OPGW (optical fiber composite overhead ground wire) cable lightning stroke positioning, wherein a laser emits light with a fixed wavelength through an OPGW optical cable distributed optical fiber, once a lightning stroke hits the OPGW optical cable, the temperature is raised instantly, heat conduction can be generated, and central wavelength drift occurs. Delta lambdaB＝KTΔ T, wherein Δ λBOffset of center wavelength, KTThe Δ T is the variation of the ambient temperature, which is a known correlation coefficient of wavelength and temperature variation.
In an embodiment, the data sampling time interval is 100 milliseconds in order to balance the demodulation speed and the response wavelength variation data. Data are uploaded under the control of the FPGA, and the USB3.0 is adopted as an interface. The lightning stroke monitoring real-time data transmission speed is guaranteed.
In the embodiment, the steps shown in fig. 6 are specifically used for realizing the OPGW optical cable lightning stroke positioning,
step S1: the operation initialization wavelength calibration of the OPGW optical cable is carried out, t1The time instant being the reference position of the wavelength of each grating1、λ2......λnRepresents;
step S2: real-time acquisition of t2λ is used as the wavelength of timet1,λt2.......λtnAnd (4) showing. Then t1To t2The wavelength change rate at that time is:
step S31: mapping the collected wavelength variation to the variation of temperature, that is, obtaining the temperature coefficient K according to the relationship between the wavelength variation and the variation of temperatureTThe formula is as follows:
KT＝η·Kλ
wherein eta is the wavelength variation and the temperature variation conversion coefficient.
In the embodiment, the OPGW optical cable is struck by lightning, the temperature rising rate model is divided into two stages, one stage is an instantaneous temperature rising stage, the instantaneous temperature rising rate is 11.1-11.5 and the deviation is 0.4 through a plurality of tests by taking 140C (coulomb) electric charge lightning stroke as an example; the second is a cooling process after instantaneous temperature rise, and the process is closely related to the environment and not used as a main judgment condition of lightning stroke, but can be used as an auxiliary condition of the OPGW optical cable suffering from the lightning stroke.
Step S4: in the embodiment, distributed optical fiber sensing application and OPGW (optical fiber composite overhead ground wire) optical cable lightning stroke positioning monitoring are provided, and the following relation is satisfied by utilizing a time division multiplexing mechanism:
τi＝2neffLi/c
wherein, according to the return time tau of the optical signaliThe location of the event can be determined, as in the OTDR system. L isiThe distance of the ith weak grating from the circulator C1. Therefore, on the basis of the distance of the known OPGW optical cable, the physical position of the OPGW optical cable with temperature rise change is easy to judge, and meanwhile, the temperature rise rate model is matched to further confirm the occurrence of a lightning stroke event.
According to the invention, related data and a large amount of data statistics are consulted to show that the parameters provided by the OPGW optical cable protection level 3(200C) cover 99% of the lightning of the cloud to the ground in the nature, and the parameters provided by the protection level 1(100C) cover 95% of the lightning of the cloud to the ground in the nature. The method provided by the invention can realize accurate positioning of OPGW optical cable lightning stroke.
Fig. 7 shows the temperature rise and gradual recovery of the normal curve of two lightning strikes at 140C in the example, and the results show that the consistency of the two lightning strikes is good, and the method is suitable for the location monitoring of the lightning strikes.
As shown in fig. 8, another object of the present invention is to provide an OPGW optical cable lightning strike location monitoring system, including:
the acquisition module is used for acquiring the central wavelengths of the array grating lightning stroke events on the distributed optical fiber in the OPGW optical cable at different moments before and after the occurrence of the array grating lightning stroke events;
the calculation module is used for calculating temperature coefficients at different grating positions in the array grating according to the variable quantities of the central wavelength at different moments; calculating the temperature rise rate of different grating positions on the OPGW optical cable according to the temperature coefficient;
and the positioning module is used for positioning the lightning stroke event occurrence position according to the temperature rise rates of different grating positions on the OPGW optical cable.
Also comprises
The distance calculation module is used for obtaining the optical signal return time corresponding to the grating at the lightning stroke event occurrence position by utilizing a time division multiplexing mechanism; and calculating the distance of the lightning stroke event occurrence position according to the optical signal return time.
A fourth object of the present invention is to provide an electronic device, as shown in fig. 9, comprising a memory, a processor and a computer program stored in the memory and executable on the processor, the processor implementing the steps of the OPGW optical cable lightning strike location monitoring method when executing the computer program.
The OPGW optical cable lightning stroke positioning and monitoring method comprises the following steps:
acquiring central wavelengths of array gratings on distributed optical fibers in an OPGW optical cable at different moments before and after a lightning stroke event occurs;
calculating temperature coefficients at different grating positions in the array grating according to the variable quantities of the central wavelength at different moments; calculating the temperature rise rate of different grating positions on the OPGW optical cable according to the temperature coefficient;
and positioning the lightning stroke event occurrence position according to the temperature rise rates of different grating positions on the OPGW optical cable.
Further comprising:
obtaining the optical signal return time corresponding to the grating at the lightning stroke event occurrence position by utilizing a time division multiplexing mechanism;
and calculating the distance of the lightning stroke event occurrence position according to the optical signal return time.
A fifth object of the present invention is to provide a computer readable storage medium, which stores a computer program, which when executed by a processor, implements the steps of the OPGW optical cable lightning strike location monitoring method.
Acquiring central wavelengths of array gratings on distributed optical fibers in an OPGW optical cable at different moments before and after a lightning stroke event occurs;
calculating temperature coefficients at different grating positions in the array grating according to the variable quantities of the central wavelength at different moments; calculating the temperature rise rate of different grating positions on the OPGW optical cable according to the temperature coefficient;
and positioning the lightning stroke event occurrence position according to the temperature rise rates of different grating positions on the OPGW optical cable.
Further comprising:
obtaining the optical signal return time corresponding to the grating at the lightning stroke event occurrence position by utilizing a time division multiplexing mechanism;
and calculating the distance of the lightning stroke event occurrence position according to the optical signal return time.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.
Claims (11)
1. An OPGW optical cable lightning stroke positioning and monitoring method is characterized by comprising the following steps:
acquiring central wavelengths of array gratings on distributed optical fibers in an OPGW optical cable at different moments before and after a lightning stroke event occurs;
calculating temperature coefficients at different grating positions in the array grating according to the variable quantities of the central wavelength at different moments; calculating the temperature rise rate of different grating positions on the OPGW optical cable according to the temperature coefficient;
and positioning the lightning stroke event occurrence position according to the temperature rise rates of different grating positions on the OPGW optical cable.
2. The method of claim 1,
the distributed optical fiber is arranged in the tubular structure, the excess length of the optical fiber of the tubular structure is controlled, a sensing composite unit is formed, and the distributed optical fiber is twisted with other optical units of the OPGW optical cable and the metal single wire and is laid with the OPGW optical cable in a whole line.
3. The method of claim 1,
before the obtaining of the central wavelengths of the array grating lightning stroke events on the distributed optical fiber in the OPGW optical cable at different moments before and after the occurrence of the array grating lightning stroke events, the method further comprises the following steps:
calibrating the relative position of the array grating of the distributed optical fiber in the OPGW optical cable, and matching the gratings at different positions in the array grating with the actual position of the OPGW optical cable; and then collecting the central wavelength of each grating at different moments before and after the occurrence of each lightning stroke event in real time.
4. The method of claim 1,
the temperature coefficients at different grating positions in the array grating are calculated according to the variation of the central wavelength at different moments, and the method specifically comprises the following steps:
calibrating the initial wavelength of OPGW optical cable, t1Time as reference position of wavelength of each grating, using λ1、λ2......λnRepresents;
real-time acquisition of t2Wavelength of time of day by λt1,λt2.......λtnIndicates that t is1To t2The wavelength change rate at that time is:
mapping the collected wavelength variation to the variation of temperature to obtain the temperature coefficient KTThe specific method comprises the following steps:
KT＝η·Kλ
wherein eta is the wavelength variation and the temperature variation conversion coefficient.
5. The method of claim 1,
the temperature rise rate of different grating positions on the OPGW optical cable is calculated by the temperature coefficient, and the method specifically comprises the following steps:
and calculating the temperature rise rate of each grating position by adopting a temperature rise rate model, wherein the temperature rise rate model is as follows:
wherein, VTFor the demodulated temperature rise rate, F is a temperature rise model function, Q is the lightning stroke discharge amount, t is the lightning stroke discharge time, etarFor the efficiency of lightning temperature conduction, KTIs the temperature coefficient; Δ t is the time for which the temperature rises to the maximum value at room temperature.
6. The method of claim 1,
further comprising:
obtaining the optical signal return time corresponding to the grating at the lightning stroke event occurrence position by utilizing a time division multiplexing mechanism;
and calculating the distance of the lightning stroke event occurrence position according to the optical signal return time.
7. The method of claim 6,
the method comprises the following steps of calculating the distance of the lightning stroke event occurrence position according to the optical signal return time, and specifically comprises the following steps:
obtaining the grating distance according to the relational expression of the optical signal return time and the grating position, wherein the relational expression is as follows:
τi＝2neffLi/c
wherein, tauiFor the return time of the optical signal, LiIs the distance of the ith grating from the circulator, neffThe change quantity of the effective refractive index of the grating fiber core is shown, and c is the light speed;
the grating distance is the distance of the position where the lightning stroke event occurs.
8. The utility model provides an OPGW optical cable thunderbolt location monitoring system which characterized in that includes:
the acquisition module is used for acquiring the central wavelengths of the array grating lightning stroke events on the distributed optical fiber in the OPGW optical cable at different moments before and after the occurrence of the array grating lightning stroke events;
the calculation module is used for calculating temperature coefficients at different grating positions in the array grating according to the variable quantities of the central wavelength at different moments; calculating the temperature rise rate of different grating positions on the OPGW optical cable according to the temperature coefficient;
and the positioning module is used for positioning the lightning stroke event occurrence position according to the temperature rise rates of different grating positions on the OPGW optical cable.
9. The utility model provides an OPGW optical cable thunderbolt location monitoring devices which characterized in that includes:
the sensing unit at least comprises a distributed optical fiber, and the distributed optical fiber collects the central wavelength of reflected light;
the fiber grating demodulator is used for acquiring the central wavelengths at different moments and demodulating the central wavelengths;
and an upper computer, the upper computer comprising the OPGW optical cable lightning strike location monitoring system of claim 8 and outputting OPGW optical cable lightning strike location monitoring information.
10. An electronic device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, the processor implementing the steps of the OPGW optical cable lightning strike location monitoring method of any of claims 1-7 when executing the computer program.
11. A computer readable storage medium storing a computer program which when executed by a processor implements the steps of the OPGW optical cable lightning strike location monitoring method of any of claims 1-7.
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| CN202110951421.2A CN113639961B (en) | 2021-08-18 | OPGW optical cable lightning stroke positioning monitoring method, system, device, equipment and medium |
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| CN202110951421.2A CN113639961B (en) | 2021-08-18 | OPGW optical cable lightning stroke positioning monitoring method, system, device, equipment and medium |
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