OPGW optical cable state early warning system based on OTDR and BOTDR

Abstract

The invention relates to the field of electric power, in particular to an OPGW optical cable state early warning system based on an OTDR and a BOTDR, and the system comprises a BOTDR measurement module which is used for determining the physical parameter data of each sampling point of an OPGW optical cable fiber core according to the collected Brillouin frequency shift data of each sampling point of the OPGW optical cable fiber core; the OTDR measurement module is used for measuring sampling point signal loss data of each sampling point of the OPGW optical cable fiber core through an OTDR; and the early warning module is used for acquiring the physical parameter data and the sampling point signal loss data of each sampling point of the OPGW optical cable fiber core from the BOTDR measurement module and the OTDR measurement module, and performing early warning prompt according to the physical parameter data and the sampling point signal loss data of each sampling point of the OPGW optical cable fiber core. According to the invention, an OTDR measurement and BOTDR measurement fusion technology is adopted, early warning is carried out according to sampling point signal loss data of each sampling point of the OPGW optical cable fiber core and physical parameter data of each sampling point, and timely discovery and early warning of faults of the power communication OPGW optical cable fiber core are realized.

Description

Technical Field

[0001] The invention relates to the technical field of electric power, and in particular to an OPGW optical cable state early warning system based on OTDR and BOTDR. Background Art

[0002] Optical Power Grounded Waveguide (OPGW) is a new type of ground wire for high-voltage power transmission system communication lines. It has the dual functions of traditional overhead ground wire and communication optical cable. OPGW is more reliable, stable and strong because it is wrapped with metal wires. Compared with other optical cables, it can shorten the construction period and save construction costs because the overhead ground wire and optical cable are combined into one. As an important part of the power communication system, the aging of OPGW optical cable has an important impact on the operation efficiency of the power grid and threatens the safety and stability of the power communication system.

[0003] Optical Time Domain Reflectometer (OTDR) mainly works on the principle of Rayleigh scattering and Fresnel reflection, and obtains the relationship between distance and loss in the optical fiber link by detecting the power of the reflected backscattered light. The basic principle of Brillouin Optical Time Domain Reflectometer (BOTDR) is to obtain the axial strain of the optical fiber by using the linear relationship between the frequency shift change of the naturally distributed Brillouin scattered light in the optical fiber and the axial strain of the optical fiber.

[0004] The present invention mainly realizes early warning of the health status of power OPGW optical cables based on Rayleigh OTDR and BOTDR, realizes timely discovery of power communication OPGW optical cable core faults, and real-time control of the health status of the optical cable core. Summary of the invention

[0005] The embodiment of the present invention provides an OPGW optical cable status early warning system based on Rayleigh OTDR and BOTDR, which is used for early warning of the health status of the power OPGW optical cable.

[0006] The present invention provides an optical fiber composite overhead ground wire OPGW cable state early warning system based on Rayleigh optical time domain reflectometer OTDR and Brillouin optical time domain reflectometer BOTDR, comprising:

[0007] The BOTDR measurement module is used to determine the physical parameter data of each sampling point of the OPGW optical cable core according to the collected Brillouin frequency shift data of each sampling point of the OPGW optical cable core;

[0008] OTDR measurement module, used to measure the sampling point signal loss data of each sampling point of the OPGW optical cable core through OTDR;

[0009] The early warning module is used to obtain the physical parameter data and the signal loss data of each sampling point of the OPGW optical cable core from the BOTDR measurement module and the OTDR measurement module, and to issue early warning prompts based on the physical parameter data and the signal loss data of each sampling point of the OPGW optical cable core.

[0010] Optionally, the providing of early warning prompts according to the physical parameter data of each sampling point of the OPGW optical cable core and the signal loss data of the sampling point includes:

[0011] According to the pre-fitted linear equation of the sampling point distance and the sampling point signal loss, the loss difference between the sampling point signal loss data of each sampling point in the OPGW optical cable core and the corresponding sampling point signal loss in the linear equation is determined. If the loss difference is not within the preset loss threshold range, an early warning prompt is given according to the physical parameter data of each sampling point in the OPGW optical cable core.

[0012] Optionally, the OTDR measurement module is further used to obtain a straight line equation of the distance between each sampling point and the signal loss of the sampling point by using a least squares method.

[0013] Optionally, when the loss difference is not within a preset loss threshold range, an early warning prompt is given according to the physical parameter data of each sampling point of the OPGW optical cable core, including:

[0014] When the loss difference is not within the preset loss threshold range, an early warning prompt is given according to the physical parameter data of each sampling point of the OPGW optical cable core and a preset graded early warning strategy.

[0015] Optionally, the physical parameter data includes strain data and sag measurement data, and the graded warning strategy includes:

[0016] When the current strain data is greater than the preset strain threshold and the OPGW optical cable is not covered with ice, the sag difference between the sag measurement data and the sag status data at each sampling point is determined; when the sag difference does not show an increasing trend over time, it indicates that the OPGW optical cable core is in good health; when the sag difference shows an increasing trend over time, it indicates that the OPGW optical cable core is aging faster; when the sag difference exceeds the preset maximum sag threshold, it indicates that the OPGW optical cable core is at risk of breakage.

[0017] Optionally, the physical parameter data includes strain data and ice thickness data, and the graded warning strategy includes:

[0018] When the current strain data is greater than the preset strain threshold and the OPGW optical cable is covered with ice, the ice thickness data of the sampling point is determined; when the ice thickness data exceeds the preset maximum thickness threshold, it is indicated that the OPGW optical cable core is at risk of breakage; when the sag difference does not exceed the preset maximum sag threshold, the ice thickness data and strain change curve are determined according to the duration of ice coverage; if the change curve changes smoothly with the duration, it indicates that the OPGW optical cable core is in good health; if the change curve is step-shaped within the duration, it indicates that the OPGW optical cable core is aging faster.

[0019] Optionally, the BOTDR measurement module is further used to collect the current value of the Brillouin frequency shift of each sampling point of the OPGW optical cable core, and determine the physical parameter data of each sampling point of the OPGW optical cable core according to the current value of the Brillouin frequency shift.

[0020] Optionally, the BOTDR measurement module includes a Brillouin frequency shift measurement unit, a core strain detection unit, a sag detection unit and an ice detection unit.

[0021] Optionally, the Brillouin frequency shift measurement unit is used to collect the current value of the Brillouin frequency shift of each sampling point;

[0022] The core strain detection unit is used to determine the change value of the Brillouin frequency shift of each sampling point according to the current value of the Brillouin frequency shift of each sampling point collected by the Brillouin frequency shift measurement unit and the initial value of the Brillouin frequency shift of each sampling point; determine the stress change value of each sampling point according to the change value of the Brillouin frequency shift of each sampling point and the temperature change value of each sampling point; determine the current stress value of each sampling point according to the stress change value of each sampling point and the initial value of the stress of each sampling point;

[0023] The sag detection unit is used to determine the sag measurement data of the fiber core at each sampling point according to the current stress value of each sampling point determined by the fiber core strain detection unit and the relationship between the preset sag of the OPGW optical cable fiber core and the stress under the operating state; each sag measurement data corresponds to a stress value; the stress value includes a stress history value and a stress current value;

[0024] The ice coating detection unit is used to measure the ice weight load of the OPGW optical cable through a fiber grating sensor, and determine the ice coating thickness data according to the ice weight load of the OPGW optical cable.

[0025] The present invention realizes the collection of Brillouin frequency shift data of each sampling point of the OPGW optical cable core by a BOTDR measurement module, determines the physical parameter data of each sampling point of the OPGW optical cable core, measures the sampling point signal loss data of each sampling point of the OPGW optical cable core by an OTDR measurement module, and then obtains the physical parameter data and sampling point signal loss data of each sampling point of the OPGW optical cable core from the BOTDR measurement module and the OTDR measurement module by an early warning module, and performs early warning prompts according to the physical parameter data and sampling point signal loss data of each sampling point of the OPGW optical cable core, adopts the fusion technology of OTDR measurement and BOTDR measurement, performs early warning according to the sampling point signal loss data of each sampling point of the OPGW optical cable core and in combination with the physical parameter data of each sampling point, realizes timely discovery and early warning of power communication OPGW optical cable core faults, and real-time control of the health status of the optical cable core, and effectively prevents the occurrence of power communication OPGW optical cable faults.

[0026] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0028] Figure 1 A block diagram of an OPGW optical cable status early warning system based on OTDR and BOTDR provided in an embodiment of the present invention;

[0029] Figure 2 A schematic diagram of a Brillouin frequency shift measurement unit provided by an embodiment of the present invention;

[0030] Figure 3 A schematic diagram of a pole tower for installing an OPGW optical cable provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0032] In the subsequent description, the suffixes such as "module", "component" or "unit" used to represent elements are used only to facilitate the description of the present invention and have no specific meanings. Therefore, "module", "component" or "unit" can be used in a mixed manner. Expressions such as "first" and "second" are only used to distinguish technical terms.

[0033] like Figure 1 As shown, the OPGW optical cable status early warning system based on OTDR and BOTDR provided in the embodiment of the present invention includes:

[0034] The BOTDR measurement module 10 is used to determine the physical parameter data of each sampling point of the OPGW optical cable core according to the collected Brillouin frequency shift data of each sampling point of the OPGW optical cable core;

[0035] An OTDR measurement module 20, used for measuring the sampling point signal loss data of each sampling point of the OPGW optical cable core by OTDR;

[0036] The early warning module 30 is used to obtain the physical parameter data and the signal loss data of each sampling point of the OPGW optical cable core from the BOTDR measurement module and the OTDR measurement module, and to issue an early warning prompt based on the physical parameter data and the signal loss data of each sampling point of the OPGW optical cable core.

[0037] OPGW carries the core business of power grid production and operation and maintenance departments. Among various mature OPGW products, OPGW can be divided into two types: aluminum tube type and steel tube type based on the optical fiber unit structure. OPGW is exposed to the field for a long time and will continue to be subjected to mechanical tension, lightning strikes and electrical flashovers, environmental changes, etc., resulting in icing and other conditions, causing aging, deformation, strand breakage, wear and corrosion of the power OPGW optical cable core, leading to power communication failures. The early warning system of the embodiment of the present invention comprises a BOTDR measurement module, an OTDR measurement module and an early warning module. The BOTDR measurement module is used to collect Brillouin frequency shift data of each sampling point of the OPGW optical cable core, determine the physical parameter data of each sampling point of the OPGW optical cable core, measure the sampling point signal loss data of each sampling point of the OPGW optical cable core by the OTDR measurement module, and then obtain the physical parameter data and sampling point signal loss data of each sampling point of the OPGW optical cable core from the BOTDR measurement module and the OTDR measurement module by the early warning module, and make early warning prompts according to the physical parameter data and sampling point signal loss data of each sampling point of the OPGW optical cable core, adopt the fusion technology of OTDR measurement and BOTDR measurement, make early warning according to the sampling point signal loss data of each sampling point of the OPGW optical cable core and the physical parameter data of each sampling point, realize timely discovery and early warning of power communication OPGW optical cable core faults, and real-time control of the health status of the optical cable core, effectively prevent the occurrence of power communication OPGW optical cable faults.

[0038] The optical fiber composite overhead ground wire OPGW cable status warning system based on Rayleigh optical time domain reflectometer OTDR and Brillouin optical time domain reflectometer BOTDR provided in the embodiment of the present invention can be specifically implemented in a module manner, such as Figure 2 As shown, in some embodiments, the OPGW optical cable status warning system based on OTDR and BOTDR includes a laser, an electro-optical modulator, a polarization scrambler, an erbium-doped fiber amplifier, a circulator, an optical attenuator, a balanced detector, a BOTDR measurement module, an OTDR measurement module, and an early warning module. The BOTDR measurement module and the OTDR measurement module are arranged at the receiving end. Among them:

[0039] 1. BOTDR measurement module

[0040] The BOTDR measurement module includes a Brillouin frequency shift measurement unit, a fiber core strain detection unit, a sag detection unit, and an ice detection unit. Among them:

[0041] Brillouin frequency shift measurement unit: used to collect the current value of the Brillouin frequency shift of each sampling point.

[0042] In some embodiments, the Brillouin frequency shift measurement module obtains the Brillouin frequency shift of the OPGW optical cable core by detecting the frequency difference between the scattered light and the incident light based on the principle of spontaneous Brillouin scattering. The Brillouin frequency shift measurement unit is used to collect the current value of the Brillouin frequency shift of each sampling point of the OPGW optical cable core through BOTDR.

[0043] In detail, the light emitted by the laser is split into two beams through optical coupler 1. The uplink light is modulated into a pulse pump light after passing through electro-optic modulator 1 controlled by a pulse modulator, enters the polarization scrambler, and then passes through the erbium-doped fiber amplifier. It enters port 1 and exits port 2 of the circulator and enters the optical fiber to be tested. The downlink light is modulated into a reference light after passing through electro-optic modulator 2 controlled by a microwave generator. It passes through an optical attenuator and is mixed with the pump light from the filter in optical coupler 2, and then enters a balanced detector. Finally, the signal obtained at the receiving end is filtered and detected. By continuously changing the frequency of the incident pulse light emitted by the transmitting end, the Brillouin frequency shift measurement unit can detect the frequency difference between the scattered light and the incident light, and obtain the Brillouin frequency shift of each sampling point on the fiber core.

[0044] Fiber core strain detection unit: used to determine the change value of the Brillouin frequency shift of each sampling point according to the current value of the Brillouin frequency shift of each sampling point collected by the Brillouin frequency shift measurement unit and the initial value of the Brillouin frequency shift of each sampling point; determine the stress change value of each sampling point according to the change value of the Brillouin frequency shift of each sampling point and the temperature change value of each sampling point; determine the current stress value of each sampling point according to the stress change value of each sampling point and the initial value of the stress of each sampling point.

[0045] In a specific implementation, most of the light waves propagating in the optical fiber propagate forward, but due to the inhomogeneous structure of the non-crystalline material of the optical fiber in the microscopic space, a small part of the light will be scattered. The light scattering in the optical fiber includes Brillouin scattering caused by acoustic phonons.

[0046] Backscattered light offset V in the fiber core B It can be expressed as:

[0047]

[0048] Where V a represents the speed of the sound wave in the fiber core, λ 0 represents the wavelength of the incident light and n represents the refractive index.

[0049] At temperature T 0 The initial relationship between the lower Brillouin frequency shift and strain is:

[0050]

[0051] Where ε represents the core strain, k represents Poisson's ratio, E represents Young's modulus, and ρ represents the medium density.

[0052] The tensile strain of the fiber core is very small, at the micro-strain level, so the above equation is Taylor expanded at ε = 0, ignoring the second-order and above terms, and the definite relationship between the Brillouin frequency shift and the strain at temperature T is:

[0053] V B (ε,T)=V B (0,T)=[1+Δε(Δn ε +Δk ε +ΔE ε +Δρ ε )] (3),

[0054] Normally, the temperature coefficient of the refractive index, Poisson's ratio, Young's modulus, and medium density of a single-mode fiber core is a constant, and the proportional relationship between the Brillouin frequency shift and temperature can be obtained from the above formula.

[0055] Therefore, the change in Brillouin frequency shift is approximately proportional to the change in fiber temperature and strain, which can generally be expressed as:

[0056] ΔV B =C V,T ΔT+C V,ε Δε (4),

[0057] Where ΔV B is the change in Brillouin frequency shift caused by temperature and strain, C V,T represents the Brillouin frequency shift temperature coefficient, C V,ε represents the Brillouin frequency shift strain coefficient, ΔT represents the temperature change, and Δε represents the strain change. The Brillouin frequency shift temperature coefficient and the Brillouin frequency shift strain coefficient are determined by four physical quantities: refractive index, Poisson's ratio, Young's modulus, and medium density. For a 1550nm wavelength pump light, according to the empirical data measured in the experiment, the single-mode quartz fiber core C V,T About 1.12MHz / ℃, C V,ε About 0.0482MHz / uε.

[0058] The transmitting end of the Brillouin frequency shift measurement unit emits pulse light through a laser, and the receiving end can locate the received signal using the following formula:

[0059]

[0060] In the formula, Z represents the distance from any point on the fiber core to the incident end, and c represents the speed of light in vacuum, which is 3×10 8m / s, t represents the time interval from when the pulse light is emitted from the transmitting end to when the signal is received, and n represents the refractive index of the fiber core. By continuously changing the frequency of the incident pulse light emitted from the transmitting end, the fiber core strain detection unit can detect the frequency difference between the scattered light and the incident light, and obtain the Brillouin frequency shift of each sampling point on the fiber core.

[0061] In some implementations, the fiber core strain detection unit is further used to determine the strain failure time of the sampling point based on the preset correspondence between the external stress and the fiber core break time and the stress average value of the sampling point.

[0062] In a specific implementation, a static fatigue test is performed on the OPGW optical cable core in advance to obtain the corresponding relationship between different strains and strain failure time at different times of the OPGW optical cable core. The strain failure time is the core break time minus the sampling time.

[0063] Static fatigue testing is performed as follows:

[0064] At each temperature, the applied stress σ f A static fatigue test is performed on an OPGW optical cable core sample with a length of l, and the time t from the start of the experiment to the breakage of the core is recorded. f According to the optical fiber microcrack propagation theory, the relationship between the applied stress and the optical fiber break time is as follows:

[0065] lgt f (σ a )≈lgt f (1)-nlgσ a (6)

[0066] Among them, a series of logarithmic values ​​of applied stress and a series of logarithmic values ​​of strain failure time corresponding to them are fitted with a straight line, and the slope of the straight line is -n; t f (1) is the intercept of the fitting line on the vertical axis, that is, the strain failure time value corresponding to the applied stress of 1.

[0067] In some embodiments, the relationship between strain and optical fiber break time is determined based on a calculation relationship between stress and strain.

[0068] For long-distance OPGW, the conversion relationship between stress and strain ε of the OPGW fiber core is as follows:

[0069] σ a =E 0 (1+cε)ε (7),

[0070] In the formula, E 0 It represents Young's modulus, with a value range of 70.3GPa-73.8GPa. For axial strain, the nonlinear term c ranges from 3 to 3.3.

[0071] Sag detection unit: used to determine the sag measurement data of the fiber core at each sampling point according to the current stress value of each sampling point determined by the fiber core strain detection unit and the relationship between the preset OPGW optical cable core sag and the stress under the operating state; each sag measurement data corresponds to a stress value; the stress value includes a stress history value and a stress current value.

[0072] In the specific implementation, OPGW optical cables are installed on power towers and work in complex external environments for a long time. The lines are always under stress and within the range of elastic deformation. With the increase of operating years and changes in the external environment, the stress of the OPGW optical cable core is affected, which in turn affects the OPGW optical cable sag. Excessive sag can easily cause accidents.

[0073] The OPGW optical cable suspended between two towers A and B with a height difference of is in a balanced state under the action of its own weight and external load. Figure 3 The shape between the two towers A and B shown in the figure shows a certain sag f. After long-term operation, the elastic modulus of the line has become a constant. When the load and temperature remain unchanged, the relationship between the sag of the OPGW optical cable core and the stress under the operating state is as follows:

[0074]

[0075] ε=σ / E (9),

[0076]

[0077] Where Δh represents the height difference of the OPGW cable suspension point, in m; g represents the OPGW cable core load, in Pa·m -1 ; σ represents the stress of OPGW optical cable in operation, unit: Pa·m -1 ; L represents the span, unit is m; β represents the height difference angle of the OPGW optical cable hanging point; ε represents the conductor stress, E represents the pressure of the environment where the OPGW optical cable is located; f represents the sag measurement data.

[0078] In the specific implementation, in order to ensure the safety and reliability of OPGW optical cables during construction and operation, the current length of the OPGW optical cable core can be determined through the law of changes in OPGW optical cable stress with meteorological conditions, that is, the state equation of the optical cable, and the sag state data can be calculated through the current length of the OPGW optical cable core.

[0079] In some embodiments, the state equation of the OPGW optical cable is as follows:

[0080]

[0081] Where, l represents the current length of the OPGW optical cable core; g represents the load of the OPGW optical cable core under current meteorological conditions, g 0 represents the OPGW optical cable core load under reference meteorological conditions, T represents the temperature under current meteorological conditions, and T 0 represents the temperature under reference meteorological conditions, ε represents the OPGW optical cable core stress under current meteorological conditions, and ε 0 It represents the stress of OPGW optical cable core under reference meteorological conditions; τ represents the thermal expansion coefficient of OPGW optical cable core, and λ represents the elasticity of OPGW optical cable core.

[0082] Furthermore, the current length of the fiber core minus the initial length of the fiber core=the sag state data of the fiber core, and the initial length of the fiber core is a known quantity.

[0083] Ice detection unit: used to measure the ice load of OPGW optical cable through fiber grating sensor, and determine the ice thickness data according to the ice load of OPGW optical cable.

[0084] Ice often forms on the surface of OPGW due to the influence of environment, conductor temperature, wind speed and direction, etc. Under certain ice thickness conditions, the sag of OPGW may be greater than the sag of conductor, which may easily lead to short circuit and grounding accidents under the influence of external forces such as wind.

[0085] In some embodiments, a fiber grating sensor is installed on each tower, and the vertical load of each tower is measured by the sensor, so as to determine the thickness of ice on the surface of the OPGW according to the vertical load.

[0086] The vertical load transmitted to the tower by the OPGW optical cable is:

[0087] G=gSl v (12)

[0088] l v = l v1 +l v2 (13) g=g 1 +g 2 +g 3 (14)

[0089] Where g represents the vertical load of OPGW optical cable, N / m.mm 2 ; l v Indicates the vertical span of the tower; l v1 l v2 Respectively represent the vertical span components on both sides of the tower; S represents the cross-sectional area of ​​OPGW optical cable, mm 2 .

[0090] Among them, in the case of no ice and no wind, the weight of OPGW optical cable is1 for:

[0091]

[0092] In the formula, m 0 Indicates the quality of OPGW optical cable per kilometer.

[0093] In the case of icing, the ice weight produced by the ice weight is g 2 :

[0094]

[0095] Where b is the ice thickness, mm; d is the OPGW cable diameter, mm.

[0096] In the case of icing, affected by wind pressure, the icing wind pressure ratio is g 3 :

[0097]

[0098] Where a is the wind speed unevenness coefficient, which is between 0.7 and 1. Specifically, when the wind speed is below 20 m / s, it is 1; between 20 and 30 m / s, it is 0.85; between 30 and 35 m / s, it is 0.75; and above 35 m / s, it is 0.7. C is the wind body shape coefficient, which is usually 1.2.

[0099] In the specific implementation, the axial force and axial angle are measured by the fiber grating sensor, and the ice weight load of the OPGW optical cable can be calculated, and then the ice thickness data can be calculated.

[0100] 2. OTDR measurement module

[0101] The light source couples the test light into the test optical fiber, and the test light is transmitted forward along the optical fiber. Due to the uneven texture of the optical fiber material and the impurities mixed into the raw materials for optical fiber manufacturing, the refractive index distribution at each position of the optical fiber is different, and scattering occurs in the optical fiber. Part of the scattered light will propagate in a direction 180 degrees from the original incident light direction. Based on this principle, in some embodiments, the OTDR measurement module is used to measure the sampling point signal loss data of each sampling point of the OPGW optical cable core through OTDR. Optionally, it is also used to fit the linear equation of the distance between each sampling point and the signal loss of the sampling point using the least squares method.

[0102] The least square method is to use mathematical analysis to fit a straight line from a set of OTDR signal measurement sample data that satisfies the relationship y=a+bx, minimize the total deviation, calculate the corresponding a and b at this time, and use the slope of the obtained straight line equation to know the sampling point signal loss slope of the OPGW optical cable core. x represents the sampling point distance, and y represents the sampling point signal loss value. In detail,

[0103] The relationship between the sampling point signal loss and the sampling distance of the OTDR signal measurement sample data is:

[0104] y = a + bx (18),

[0105] For a set of OTDR signal measurement sample data (x i ,y i ), x=x i When the OTDR signal measures the sample data y i and the point a+bx on the fitting line i The difference d i As follows:

[0106]

[0107] Ideally, the OTDR signal measurement sample data are all on the straight line represented by y = a + bx, so d in the above formulas is equal to zero, that is, d 1 =d 2 =…=d n = 0. In actual situations, it is impossible for all OTDR signal measurement sample data to fall on the above straight line. The least square method can be used to obtain is the minimum value, find the corresponding a and b.

[0108] Right now:

[0109]

[0110] The first-order partial derivatives of D with respect to a and b are:

[0111]

[0112] The second-order partial derivatives of D with respect to a and b are:

[0113]

[0114] To find the minimum value, set it to zero:

[0115]

[0116] Substitute the following average values ​​into the above 2 equations:

[0117]

[0118] but:

[0119] Solve for the values ​​of a and b, and substitute the values ​​of a and b into y=a+bx to obtain the linear equation of the sampling point distance and the sampling point signal loss.

[0120] Whether the fiber core is normal is determined based on whether the difference between the sampling point signal loss data corresponding to the distance measured by the OTDR signal and the sample sampling point signal loss value of the corresponding point on the fitted sampling point signal loss straight line equation is within a preset threshold range. The threshold can be set according to the actual application process.

[0121] 3. Early Warning Module

[0122] The early warning module is used to obtain the physical parameter data and the signal loss data of each sampling point of the OPGW optical cable core from the BOTDR measurement module and the OTDR measurement module, and to issue early warning prompts based on the physical parameter data and the signal loss data of each sampling point of the OPGW optical cable core.

[0123] At present, the signal loss data curve of the sampling points measured by OTDR usually has errors. Because of the measurement error of OTDR itself, the error of event blind zone, etc., the measurement curve is not smooth and steps appear, which leads to false alarms in the status warning of OPGW optical cable core. The embodiment of the present invention adopts OTDR measurement and BOTDR measurement fusion technology, and issues warnings based on the signal loss data of each sampling point of the OPGW optical cable core and the physical parameter data of each sampling point, so as to effectively avoid false alarms.

[0124] In some embodiments, in order to further avoid false alarms, the sampling point signal loss data and the straight line equation of each sampling point can be obtained by pre-fitting, and the errors and other problems existing in the OTDR measurement process can be eliminated according to the straight line equation. That is, the early warning prompt is given according to the physical parameter data and the sampling point signal loss data of each sampling point of the OPGW optical cable core, including:

[0125] According to the pre-fitted linear equation of the sampling point distance and the sampling point signal loss, the difference between the sampling point signal loss data of each sampling point in the OPGW optical cable core and the sampling point signal loss of the corresponding sampling point in the linear equation is determined. When the difference is not within the preset loss threshold range, an early warning prompt is given according to the physical parameter data of each sampling point in the OPGW optical cable core.

[0126] In some embodiments, a hierarchical early warning strategy can be adopted according to the physical parameter data of each sampling point of the OPGW optical cable core to ensure timely discovery of power communication OPGW optical cable core faults and real-time control of the health status of the optical cable core, so as to effectively prevent the occurrence of power communication OPGW optical cable faults. The physical parameter data may include strain data, sag measurement data and ice data. In some embodiments, a hierarchical early warning strategy is set according to the strain data combined with the sag measurement data and ice data.

[0127] When the strain data, sag measurement data and ice cover data are all within the preset normal range, no warning will be given.

[0128] The hierarchical warning strategy includes one or more of the following:

[0129] When the strain data is not greater than a preset strain threshold, the strain failure time of the sampling point is determined according to the strain data, and the strain failure time of the sampling point is prompted;

[0130] When the strain data is greater than the preset strain threshold and the OPGW optical cable is not covered with ice, the sag difference between the sag measurement data and the sag status data at the sampling point is determined; when the sag difference does not show an increasing trend over time, it indicates that the OPGW optical cable core is in good health; when the sag difference shows an increasing trend over time, it indicates that the OPGW optical cable core is aging faster; when the sag difference exceeds the preset maximum sag threshold, it indicates that the OPGW optical cable core is at risk of breaking and needs to be manually processed as soon as possible;

[0131] When the strain data is greater than the preset strain threshold and the OPGW optical cable is covered with ice, the ice thickness data of the sampling point is determined; when the ice thickness data exceeds the preset maximum thickness threshold, it indicates that the OPGW optical cable core is at risk of breakage and needs to be melted as soon as possible; when the sag difference does not exceed the preset maximum sag threshold, the ice thickness data, ice time and strain change curve are determined; if the change curve changes smoothly with the ice time, it indicates that the OPGW optical cable core is in good health; if the change curve is step-shaped during the ice time, it indicates that the OPGW optical cable core is aging faster.

[0132] The embodiment of the present invention adopts the fusion technology of OTDR measurement and BOTDR measurement, and performs early warning according to the signal loss data of each sampling point of the OPGW optical cable core and the physical parameter data of each sampling point, so as to realize timely discovery and early warning of power communication OPGW optical cable core faults, and real-time control of the health status of the optical cable core, and effectively prevent the occurrence of power communication OPGW optical cable faults.

[0133] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0134] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0135] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. An optical fiber composite overhead ground wire OPGW cable status early warning system based on Rayleigh optical time domain reflectometer OTDR and Brillouin optical time domain reflectometer BOTDR, characterized in that: The OPGW optical cable status early warning system based on OTDR and BOTDR includes: The BOTDR measurement module is used to determine the physical parameter data of each sampling point of the OPGW optical cable core according to the collected Brillouin frequency shift data of each sampling point of the OPGW optical cable core; An OTDR measurement module is used to measure the sampling point signal loss data of each sampling point of the OPGW optical cable core through OTDR; The early warning module is used to obtain the physical parameter data and the signal loss data of each sampling point of the OPGW optical cable core from the BOTDR measurement module and the OTDR measurement module, and to issue early warning prompts based on the physical parameter data and the signal loss data of each sampling point of the OPGW optical cable core.

2. The OPGW optical cable status early warning system based on OTDR and BOTDR according to claim 1, characterized in that: The method of providing early warning prompts based on the physical parameter data of each sampling point of the OPGW optical cable core and the signal loss data of the sampling point includes: According to the pre-fitted linear equation of the sampling point distance and the sampling point signal loss, the loss difference between the sampling point signal loss data of each sampling point in the OPGW optical cable core and the corresponding sampling point signal loss in the linear equation is determined. If the loss difference is not within the preset loss threshold range, an early warning prompt is given according to the physical parameter data of each sampling point in the OPGW optical cable core.

3. The OPGW optical cable status early warning system based on OTDR and BOTDR according to claim 2 is characterized in that: The OTDR measurement module is also used to obtain the linear equation of the distance between each sampling point and the signal loss of the sampling point by using the least square method.

4. The OPGW optical cable status early warning system based on OTDR and BOTDR according to claim 2 is characterized in that: When the loss difference is not within the preset loss threshold range, an early warning is given according to the physical parameter data of each sampling point of the OPGW optical cable core, including: When the loss difference is not within the preset loss threshold range, an early warning prompt is given according to the physical parameter data of each sampling point of the OPGW optical cable core and a preset graded early warning strategy.

5. The OPGW optical cable status early warning system based on OTDR and BOTDR according to claim 4 is characterized in that: The physical parameter data includes strain data and sag measurement data, and the hierarchical warning strategy includes: When the current strain data is greater than the preset strain threshold and the OPGW optical cable is not covered with ice, the sag difference between the sag measurement data and the sag status data at each sampling point is determined; when the sag difference does not show an increasing trend over time, it indicates that the OPGW optical cable core is in good health; when the sag difference shows an increasing trend over time, it indicates that the OPGW optical cable core is aging faster; when the sag difference exceeds the preset maximum sag threshold, it indicates that the OPGW optical cable core is at risk of breakage.

6. The OPGW optical cable status early warning system based on OTDR and BOTDR according to claim 5, characterized in that: The physical parameter data includes strain data and ice thickness data, and the graded warning strategy includes: When the current strain data is greater than the preset strain threshold and the OPGW optical cable is covered with ice, the ice thickness data of the sampling point is determined; when the ice thickness data exceeds the preset maximum thickness threshold, it is indicated that the OPGW optical cable core is at risk of breakage; when the sag difference does not exceed the preset maximum sag threshold, the ice thickness data and strain change curve are determined according to the duration of ice coverage; if the change curve changes smoothly with the duration, it indicates that the OPGW optical cable core is in good health; if the change curve is step-shaped within the duration, it indicates that the OPGW optical cable core is aging faster.

7. The OPGW optical cable status early warning system based on OTDR and BOTDR according to any one of claims 1 to 6, characterized in that: The BOTDR measurement module is also used to collect the current value of the Brillouin frequency shift of each sampling point of the OPGW optical cable core, and determine the physical parameter data of each sampling point of the OPGW optical cable core according to the current value of the Brillouin frequency shift.

8. The OPGW optical cable status early warning system based on OTDR and BOTDR according to claim 7, characterized in that: The BOTDR measurement module includes a Brillouin frequency shift measurement unit, a fiber core strain detection unit, a sag detection unit and an ice detection unit.

9. The OPGW optical cable status early warning system based on OTDR and BOTDR according to claim 8, characterized in that: The Brillouin frequency shift measurement unit is used to collect the current value of the Brillouin frequency shift of each sampling point; The core strain detection unit is used to determine the change value of the Brillouin frequency shift of each sampling point according to the current value of the Brillouin frequency shift of each sampling point collected by the Brillouin frequency shift measurement unit and the initial value of the Brillouin frequency shift of each sampling point; determine the stress change value of each sampling point according to the change value of the Brillouin frequency shift of each sampling point and the temperature change value of each sampling point; determine the current stress value of each sampling point according to the stress change value of each sampling point and the initial value of the stress of each sampling point; The sag detection unit is used to determine the sag measurement data of the fiber core at each sampling point according to the current stress value of each sampling point determined by the fiber core strain detection unit and the relationship between the preset sag of the OPGW optical cable fiber core and the stress under the operating state; each sag measurement data corresponds to a stress value; The stress value includes the stress history value and the stress current value; The ice coating detection unit is used to measure the ice weight load of the OPGW optical cable through a fiber grating sensor, and determine the ice coating thickness data according to the ice weight load of the OPGW optical cable.

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