CN113340350A - Grating vector sensor, and device and method for monitoring ice-coated sag state of overhead line - Google Patents
Grating vector sensor, and device and method for monitoring ice-coated sag state of overhead line Download PDFInfo
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Abstract
The invention discloses a grating vector sensor, an ice-coated sag state monitoring device of an overhead line and a method thereof, wherein the grating vector sensor comprises a sensing part, a plurality of groups of fiber gratings and single-mode fibers; the sensing piece is a cylindrical body with a hollow center, and a plurality of groups of fiber gratings are adhered to a stressed deformation area of the sensing piece; two ends of the sensing piece are respectively provided with a connecting piece; each group of fiber bragg gratings is parallel to the axial direction of the sensing piece and is wound on the sensing piece in a quasi-distributed mode; and the fiber bragg grating is adhered to the inner side of the sensing column, and the grating vector sensor transmits, decomposes and monitors the tension of the ice-coated ground wire on line. The grating vector sensor deeply fuses the specific engineering environment of the ground wire hardware fitting, realizes the functions of on-line monitoring and real-time transmission, improves the accuracy of a data model by combining an artificial intelligence algorithm, and forms a set of complete technical scheme for monitoring the icing arc icing state.
Description
Technical Field
The invention belongs to the field of overhead line monitoring, and relates to a grating vector sensor for monitoring tension changes of a ground wire in ice coating and sag states in a strain section, in particular to a grating vector sensor, and an overhead line ice coating sag state monitoring device and method.
Background
In an overhead line, a strain tower is required to bear not only the gravity load of a ground wire and hardware, but also an additional load from the line direction, which is mainly caused by external conditions. In the 2008 frozen snow disaster, the strain tower is damaged due to the strong external load, thereby causing the collapse accident of the whole line. Therefore, it is necessary to install sensors at the tension towers, which are closely concerned about the changes of the external load, and the main monitoring targets are icing and sag.
3.1 icing monitoring related technology
The ice coating of the overhead transmission line is used as a disaster which has great harm and seriously threatens the safe and stable operation of the transmission line. The damage mainly comprises overload accidents, uneven icing or ice shedding, galloping caused by icing on a ground wire, insulator ice flashing accidents and the like. The overload accident refers to mechanical and electrical accidents caused by the increase of mass and wind pressure area after the ground wire is coated with ice, and the accidents can cause hardware damage, broken strands of the ground wire, damage and collapse of a tower and the like. Uneven icing or deicing can generate tension difference, thereby causing diameter shrinkage and breakage of the ground wire, damage of an insulator, torsion and deformation of a cross arm of a tower and easily causing flashover. The ice coating is one of the power for generating the waving, the waving is easily generated after the ice coating of the ground wire, and the waving has long duration of large-amplitude swinging, thereby easily causing more harm. Insulator ice flash accident: if a lot of pollutants are mixed in the damage of ice coating, insulator flashover is easily generated, and the insulation state of the electric environment is damaged.
Mechanism of ice accretion generation: generally considered as a physical process of solidification by releasing latent heat from liquid supercooled water droplets. The heat exchange and transfer of water and ice are closely related, thereby affecting the amount of ice and the thickness of the ice.
Study of ice coating model of transmission line: it solves the quantitative analysis under meteorological parameters. At present, the mature ones are: a predictive model and an actual simulation line device built by EA company effectively solve the formation of icing conditions and various parameters. MRI model and modified GOODWIN, etc.: the growth process of the ice and the formation of ice freezes under the influence of humidity and temperature are estimated.
Deicing and anti-icing technology of the power transmission line: thermal deicing, mechanical deicing, natural passive deicing, and the like.
1. Thermal deicing: the large current of the ground wire is utilized to generate heat for deicing; currently considered to be the most efficient method.
2. Mechanical deicing: various manual mechanical and electric mechanical devices are directly used for deicing in modes of impact, explosion, bending and the like;
3. and (3) natural passive deicing: the device for preventing ice coating is provided with a snow-resisting ring, a balance weight, a wind umbrella and the like. In particular, methods of applying hydrophobic coatings are of interest. None of these methods guarantees reliable deicing but does not require external additional energy.
The current online monitoring method comprises the following steps:
1. image and video methods: and the video device arranged on the tower collects real-time images of the icing line and then obtains the on-site icing condition through analysis. And identifying the icing degree by using the image difference.
2. And (3) weighing method: the force sensor is used for replacing a ball head hanging ring which is sourced from for a long time, and an angle sensor and a tension sensor are used for measuring the inclination angle, the wind deflection and the icing load of the suspension insulator string respectively. And (4) combining meteorological data such as wind speed and wind direction, performing static analysis on the suspension point in the vertical direction, and calculating the vertical load increased by ice coating in the vertical span so as to obtain the ice coating thickness.
3. Dip angle sag method: and obtaining real-time monitoring data by the change of the torsional reference datum plane after the icing of the ground wire occurs.
3.2 sag State monitoring brief introduction
The main reasons for the sag change of the ground lead wire are load change and temperature change of the ground lead wire, and the following hazards are mainly caused:
sag is too small, and the annual stress increases, has increased the mechanical load of leading ground wire self gold utensil insulator, harms the life that shortens easily, and the vibration probability increases, and the unbalanced tension grow between shaft tower and the adjacent strain insulator section leads to the shaft tower slope easily.
The sag is too large, the change of the sag of the ground wire is caused due to the influence of wind power, the phenomenon of whipping is generated, and the extension of the ground wire is obviously increased at high temperature, so that the safety distance to the ground is not enough.
The measuring method of the sag mainly comprises the following steps: midpoint height, angle, equal length. The online monitoring method is divided into the following points according to different principles:
1. sag measurement based on angle sensor (monitoring tension and dip)
2. Sag monitoring technology based on ground lead wire temperature (real-time measurement of ground lead wire temperature, calculation of horizontal stress by using ground lead wire state equation, and calculation according to the relationship between horizontal stress and sag)
3. Sag online monitoring based on ultrasonic (measuring distance by ultrasonic, monitoring sag height of any point of ground wire and distance of tower reference)
4. Sag Observation based on images and video (real-time observation by adding equipment and devices)
And (3) conducting ground wire sag monitoring based on fiber bragg grating: the strain value of the line is monitored through the optical fiber sensor, and then the sag height and the suspension point height are obtained according to the relation between the strain and the grating wavelength, so that the real-time sag value is obtained. The optical fiber sensor is used as a passive device, and has good anti-electromagnetic interference characteristic.
3.3 fiber Grating sensor introduction
At present, a plurality of sensors for monitoring ice coating exist, the problems of nonlinearity, zero drift, unresponsiveness of creep characteristics and the like are difficult to solve by the most applied electronic tension sensor, the precision and the sensitivity of the angle sensor are easily interfered by the external electromagnetic environment, a plurality of monitoring data are invalid, and the signal transmission of the sensors is also difficult to solve.
In the field of overhead line monitoring, the fiber grating sensor has natural advantages, including excellent electromagnetic interference resistance, small size, light weight, high and low temperature resistance, corrosion resistance and the like. The invention is based on the fiber bragg grating sensing technology, monitors the tension change of the ground wire in the ice coating process by utilizing the characteristic that the fiber bragg grating is sensitive to stress, and monitors the ice coating by comprehensively considering the inclination angle, the wind deflection angle and the microclimate environment (temperature, humidity, wind speed, wind direction, rainfall and the like) of the tower by utilizing the existing angle sensor, tension sensor, microclimate station and the like.
The fiber grating is a section of fiber with a periodically changing core refractive index, and has selectivity on wavelength transmission and reflection. In sensing application, the refractive index distribution period of the fiber core is changed by temperature, pressure, stress and the like, so that the corresponding central wavelength is changed, and specific values of the temperature, the pressure, the stress and the like can be calculated according to the corresponding relation between the wavelength central variation and an external event.
The fiber grating sensor has important application value in the power industry. For example, stress monitoring of composite insulators. Researchers stick the fiber bragg grating on the surface of the composite insulator, and evaluate the running states of the fiber composite insulator such as icing, temperature rise, pollution creepage, brittle failure/decay failure and the like by measuring temperature or strain. The research surface is as follows: the temperature coefficient of the fiber grating is related to the packaging material and process, and the stress data shows that the axial stress of the core rod is not uniform.
The fiber bragg grating strain sensor is arranged at a key position of the stress of the cross arm and used for monitoring the stress strain of the cross arm. The research surface shows that the main stress of the cross arm is concentrated at the top end of the suspension insulator string, the fiber grating sensor is installed at the top end of the cross arm, the stress is taken as a monitoring object, and the correlation coefficient of the central wavelength and the strain reaches more than 0.999.
The fiber grating strain monitoring scheme can be applied to an electric power tunnel, sensors can be appointed to be installed at weak positions of the electric power tunnel and comprise easily-deformed sensitive regions such as unfavorable geological structures, faults and cracks, one demodulator is provided with a plurality of channels, each channel can be connected with a plurality of sensors to form a quasi-distributed network, and a fiber grating monitoring system can acquire data such as displacement and temperature of stress strain and cracks.
Chinese patent 202010550692.2 discloses "icing real-time monitoring system based on fiber bragg grating", this patent technique belongs to the fiber bragg grating sensor field, including the triangle-shaped cantilever beam, fiber bragg grating FBG1, fiber bragg grating FBG2, the thimble, U type link plate, glue silk, interior glue silk, this triangle-shaped cantilever beam both ends are equipped with the circular port, link thimble and U type link plate respectively, be used for fixing on the overhead line, there is the trapezoidal hole in the centre, fiber bragg grating FBG1 pastes the outside at the triangle-shaped cantilever beam, fiber bragg grating FBG2 pastes the inboard at the triangle-shaped cantilever beam, when overhead transmission line is with when icing, make triangle-shaped the cantilever beam produces stress.
Two gratings are pasted on the inner side and the outer side of the triangular cantilever beam, the wavelength offset of the fiber grating is determined by temperature and deformation, the temperature coefficients of the FBG1 and the FBG2 on the inner side and the outer side are the same, the voltage change coefficients are just opposite, the wavelength change amounts of the FBG1 and the FBG2 on the inner side and the outer side are subtracted to obtain composite change amounts, the influence of the temperature on the wavelength offset of the fiber grating is eliminated, and the influence of strain on the wavelength offset of the fiber grating is improved by one time.
However, the triangular cantilever beam of the above patent is used as a stress induction end, the end with a large diameter is connected with the embedded ring, the end with a small diameter is connected with the U-shaped hanging plate, and the fiber grating and the triangular cantilever beam are fixed in a sticking way. On one hand, the triangular cantilever beam is used as a connecting hardware fitting for a tower and a cable, the requirement on safety factors of tensile strength and fatigue resistance is high, the stress structure of the hardware fitting is damaged by a method of forming a trapezoidal groove in the center, the cross sectional area is reduced, the tensile force in unit area is increased, and safety accidents are likely to occur; on the other hand, the performance of the adhered multi-polymer material cannot be suitable for the harsh environment of the optical fiber sensor of the overhead transmission line, the sensor is easy to fall off after the adhesive is aged, and the optical fiber sensor is extremely difficult to maintain after being installed on the overhead transmission line, so that the existing patent technical engineering is not strong in reliability, cannot meet the monitoring requirement of the overhead transmission line, and is poor in implementation safety; in addition, the sensing technology can only realize unidirectional stress measurement, the stress condition of the connection part of the overhead ground wire and the tower is very complex, the universality and the accuracy are difficult to ensure through mechanical calculation in the prior art, and the ice coating information under the action of waving, wind pendulum and the like is difficult to obtain through the sensing technology.
Disclosure of Invention
The invention aims to solve the problems that the monitoring variable of the existing sensor is single, the stress in multiple directions cannot be judged, the engineering applicability is poor and the like, and provides a grating vector sensor, an overhead line icing sag state monitoring device and a method.
In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:
a grating vector sensor, comprising:
the sensing piece is a cylindrical body with a hollow center, and a plurality of groups of fiber gratings are adhered to a stressed deformation area of the sensing piece; two ends of the sensing piece are respectively provided with a connecting piece;
each group of fiber gratings is parallel to the axial direction of the sensing piece and is wound on the sensing piece in a quasi-distributed manner;
and the single-mode optical fiber penetrates through the base after being wound on a plurality of groups of optical fiber gratings on the sensing piece, and is output from the tail cable terminal to be connected with the joint box.
The device for monitoring the icing sag state of the overhead line adopts the grating vector sensor, a fixing hole at the upper end of the grating vector sensor is connected with a cross arm of a tower through a connecting hardware fitting, and a fixing hole at the lower end of the grating vector sensor is connected with an insulator string through a connecting hardware fitting; the single mode fiber penetrates out of the tail cable terminal and is connected with the joint box.
A method for monitoring the icing sag state of an overhead line comprises the following steps:
step 1: fixing two ends of the sensor through the ground lead wire, and applying tension F1 by a tensile machine to ensure that the ground lead wire is in a straightening state and is used for simulating the self gravity load of the ground lead wire and collecting the variation of the central wavelength;
step 2: the tensile machine applies a vertically downward tension F2 to bend and sag the ground wire to generate a sag h1 and a sag h2, and the inclination angle of the ground wire in the horizontal direction is changed into theta 1 and theta 2 to simulate the ice coating load of the ground wire and the sag change caused by ice coating and collect the variation of the central wavelength of the grating vector sensor and the inclination angle sensor;
and step 3: after the sensor is calibrated, the central wavelength is converted into the corresponding tension and inclination angle for calculating the icing thickness and the sag size.
Compared with the prior art, the invention has the following beneficial effects:
the sensors related to the invention are all fiber bragg grating sensors, and comprise vector sensors, inclination sensors, strain sensors and microclimate stations, so that the electromagnetic interference resistance is strong, and monitoring variables are obviously increased; the sensors and the strain insulator string are reasonably arranged and deeply combined; a plurality of fiber gratings are arranged in the vector sensor, a demodulation system simultaneously collects all central wavelength variation quantities, and the tension of the ground wire is calculated through components of the tension (lateral force, normal tension, axial tension and torsional force); and correcting the data by adopting an artificial intelligence algorithm.
Drawings
In order to more clearly explain the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
Fig. 1 is a schematic structural diagram of a grating vector sensor according to the present invention.
FIG. 2 is a schematic cross-sectional view of a sensor according to the present invention.
Fig. 3 is a schematic view of the installation of the sensor of the present invention on a strain-resistant mast tower of an overhead transmission line.
Fig. 4 is a schematic diagram of the connection between the grating vector sensor and the power fitting according to the present invention.
FIG. 5 is a schematic diagram of the sensor testing and calibration according to the present invention.
FIG. 6 is an algorithm flow chart of the monitoring method of the present invention.
Wherein: the method comprises the following steps of 1-installing a fixing piece, 2-a base, 3-a sensing piece, 4-a groove, 5-a tail cable terminal, 6-a fixing hole, 7-a fiber grating, 8-a single-mode fiber, 9-a socket hanging plate, 10-a connecting hardware fitting, 11-a ground wire, 12-a demodulation unit, 13-a tower cross arm, 14-a joint box, 15-an insulator string, 16-a strain clamp and 17-an OPGW optical cable.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. are used for indicating the orientation or positional relationship based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship which is usually arranged when the product of the present invention is used, the description is merely for convenience and simplicity, and the indication or suggestion that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, cannot be understood as limiting the present invention. Furthermore, the terms "first," "second," and the like are used merely to distinguish one description from another, and are not to be construed as indicating or implying relative importance.
Furthermore, the term "horizontal", if present, does not mean that the component is required to be absolutely horizontal, but may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.
In the description of the embodiments of the present invention, it should be further noted that unless otherwise explicitly stated or limited, the terms "disposed," "mounted," "connected," and "connected" should be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
The invention is described in further detail below with reference to the accompanying drawings:
referring to fig. 1, an embodiment of the present invention discloses a grating vector sensor, including: the optical fiber grating installation device comprises an installation fixing piece 1, a base 2, a sensing piece 3, a groove 4, a tail cable terminal 5, a fixing hole 6, an optical fiber grating 7 and a single-mode optical fiber 8. The main body part of the sensor is directly processed by adopting a numerical control processing method, and the material can be made of stainless steel, carbon steel, quenched and tempered steel, alloy steel, spring steel and the like. According to the schematic diagram of the sensor, the cylindrical installation fixing piece 1 is arranged on the cylindrical base 2, the diameter of the installation fixing piece 1 is smaller than that of the base 2, the sensing piece 3 is a hollow sensitive cylinder formed by forming a groove 4 in the surface, the fiber bragg grating 7 is adhered to a stress deformation area of the hollow sensitive cylinder and is parallel to the axial direction of the cylinder, the fiber bragg grating is wound on the sensing piece 3 in a quasi-distributed mode, the tail cable terminal 5 is fixed on the base 2, and the single-mode optical fiber 8 is led out through one end of the tail cable terminal 5.
The sensor of the invention selects the discrete sensing columns which are grooved in the circumferential direction in sequence and parallel to the axial direction or vertical to the base 2 to be directly processed in a numerical control way on the sensing piece 3, and can be made into a three-column sensor, a four-column sensor and a five-column sensor till an n-column sensor according to different grooving quantities. In the sensor, the mounting and fixing piece 1 is a stress and transmission end and is used for sensing the tension change of the ice-coated ground wire 11, the tension action can be transmitted to each discrete sensing column of the sensing piece 3 through the handle 1 and the base 2, when the type and direction of external stress change, the strain area of each surface of the sensing column also changes correspondingly, and the external three-dimensional stress condition can be restored by monitoring the central wavelength variation of all fiber gratings adhered to the surface of the sensing piece 3 of the sensor.
As shown in fig. 2, the sensor of the present invention has a plurality of sensitive surfaces, and in the case of a three-pillar sensor, the center of the sensing element 3 is hollowed out, and there are A, B, C pillars, and there are 9 surfaces, which are named as a1, a2, A3, B1, B2, B3, C1, C2, and C3, respectively. Characterized in that B and C are symmetrical about the handle, a1, B1, C1 are outwardly directed surfaces, while a2, A3, B2, B3, C2, C3 are inwardly directed surfaces.
As shown in fig. 3, the sensor of the present invention is installed on a strain-resistant type pole tower, and the tension change of the ground wire 11 is transmitted to the surface of each discrete sensing column of the sensing member 3 through the strain clamp 16, the socket plate 9, the insulator string 15 and the link fitting 10 in sequence, so as to cause deformation and change the center wavelength of the fiber grating. An optical fiber tilt angle sensor is arranged in the connecting fitting 10, a joint box 14 is arranged on the tower cross arm 13, and all optical signals are transmitted to the demodulation unit 12 through an OPGW optical cable 17.
As shown in fig. 3, the vector is located between the tower cross arm 13 and the insulator string 15, the connection fitting 10 between the vector sensor and the tower cross arm 13 includes a U-shaped ring, a hanging point fitting, a hanging plate, an extension ring, an adjusting plate, etc., and the connection fitting 10 between the vector sensor and the insulator string 15 includes a ball head hanging ring, a socket head hanging plate, etc. The vector sensor may also be located between the insulator string 15 and the strain clamp 16, instead of various link fittings, including PD-type link plates, ZS-type link plates, P-type link plates, and the like. Fig. 4 shows a connection mode of the installation fixing piece 1 and the hardware fitting of the sensor, and the vector sensor is provided with a packaging protection shell which is respectively fixed with the GD type hanging point hardware fitting and the yoke plate.
In the monitoring process, the sensing column surface is welded with the fiber bragg grating, and the icing state of the ground wire 11 is monitored by monitoring the central wavelength variation of all the fiber bragg gratings at different positions. The central wavelength of the fiber grating varies differently at different positions at the same time during the entire ice coating process, because the sensing element 3 decomposes the conductor-wire tension into a plurality of tension components. According to the coordinate system in fig. 3, the sensing element 3 can decompose the ground wire tension F into a normal tension Fx, a lateral tension Fy, an axial tension Fz and a torsion force Mz, wherein the normal tension Fx is parallel to the base 2 and the paper surface, the lateral tension Fy is perpendicular to the normal tension Fx, and the axial tension Fz is perpendicular to the normal tension Fx and the lateral tension Fy. In the specific implementation process of the invention, the fiber bragg grating is welded on a specific position, and the stress change of the surface is monitored.
The principle and the working process of the invention are as follows:
the following brief analysis was performed in conjunction with the change in the center wavelength of the fiber grating and the change in tension during the ice coating process:
a. when ice coating occurs, the conductive ground wire 11 is eccentrically stressed to generate torsion along the Z direction, when the sensor is subjected to the torsion force Mz of the conductive ground wire, the outward surfaces such as a1, B1 and C1 shown in fig. 2 are deformed, while the surfaces in other directions such as a2 and A3 are deformed to be far lower than a1 or not deformed, and the gratings at a1, B1 and C1 sense the deformation and transmit the deformation to the demodulation unit 12.
b. When icing occurs, the load of the grounding wire per se can be obviously increased, and the sensor can be subjected to obvious axial tension Fz. The inwardly facing surfaces shown in fig. 2, e.g., a2, A3, B2, B3, C2, C3, are sensitive to the axial tension Fz, and the fiber gratings at these locations sense these deformations and transmit them to the demodulation unit 12.
c. In practical situations, the change of the tension of the ground wire caused by ice coating is not the same as the axial tension Fz of the vector sensor, but deviates from a certain angle, and the magnitude and direction of the axial tension Fz are corrected by analyzing the changes of the lateral force Fy and the normal tension Fx. When the ground wire swings in the direction vertical to the paper surface, the sensor is subjected to lateral force Fy, the corresponding position can deform, and the fiber bragg grating can sense the deformation; when the ground wire swings in the up-and-down direction, the sensor is subjected to a normal force Fx, the corresponding position is deformed, and the fiber bragg grating can also sense the deformation. And finally, calculating the magnitude and direction of the external resultant force by using an interpolation method, namely the tension of the ground wire.
d. Icing can cause the ground lead to sag larger. The inclination angle sensor located in the link fitting 10 senses a change in the angle, thereby calculating the horizontal stress of the ground wire.
In the former 5 steps, the device monitors the icing load and the sag change by monitoring the eccentric torsion force, the tension of the ground wire, the inclination angle and the like.
As shown in fig. 5, fig. 5 is a schematic view of testing and calibrating a grating vector sensor according to the present invention, and an embodiment of the present invention further discloses a method for monitoring an icing sag state of an overhead line, including the following steps:
step 1: the tension machine applies tension F1, the ground lead wire is in a straightening state and is used for simulating the self gravity load of the ground lead wire, the sensor is connected with the demodulator and is used for collecting the variation of the central wavelength, and the variation of the wavelength has a good linear relation with the tension;
step 2: the tensile machine applies a vertically downward tension F2, the ground wire bends and droops to generate sag h1 and sag h2, meanwhile, the inclination angles of the ground wire and the horizontal direction can also change, namely theta 1 and theta 2, and the sag h is used for simulating the ice-coated load of the ground wire and the sag change caused by ice coating;
and step 3: after the sensor is calibrated, the central wavelength is converted into the corresponding tension and inclination angle, and the corresponding formula is substituted to calculate the icing thickness and the sag size.
In the previous embodiment, the central wavelengths of the fiber gratings at different positions vary differently at the same time. The autonomous design algorithm maps the central wavelength variation acquired by the demodulator and the tension characteristic in the icing process. As shown in fig. 6, in the schematic diagram of the fiber grating vector sensor algorithm, the change of the tension of the ground wire in a certain state during the ice coating process causes the change of the central wavelength of each fiber grating in different degrees, the demodulator is used for detecting the wavelength, the number of the fiber gratings is less than or equal to the number of the channels of the demodulator, and the algorithm calculates the data to obtain N outputs. And in the N outputs, finding out the output data corresponding to the state, taking the output data as a correct result, taking the output data as an incorrect result, increasing the connection weight of the correct result, and repeating the training to ensure that the algorithm can make the correct result when meeting the condition again. And repeating the process of simulating the ice coating, wherein the process comprises various states (vertical load, horizontal load, lead wire and ground wire tension, ice coating thickness, ice shedding jump and the like) until the algorithm accurately judges and identifies each state.
The specific method for identifying the state comprises the following steps:
step 1: normalizing the sample data to determine effective input data of a target to be trained;
step 2: setting parameters such as maximum training times, learning precision, initial weight, threshold value and the like;
and step 3: calculating the output of the hidden layer and the output layer;
and 4, step 4: calculating an error;
and 5: and if the prediction error of the network model is larger than the learning error, updating the weight and the threshold, repeating the training until the prediction error is smaller than the learning error, and finishing the learning.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (12)
1. A grating vector sensor, comprising:
the sensing piece (3) is a cylindrical body with a hollow center, and a plurality of groups of fiber gratings (7) are adhered to a stressed deformation area of the cylindrical body; two ends of the sensing piece (3) are respectively provided with a connecting piece;
the fiber bragg gratings (7) of each group are parallel to the axial direction of the sensing piece (3), and are wound on the sensing piece (3) in a quasi-distributed manner;
single mode fiber (8), single mode fiber (8) pass base (2) after winding a plurality of groups fiber grating (7) on perception piece (3), are located out the fine, connect splice box (14) by tail cable terminal (5).
2. The grating vector sensor according to claim 1, wherein the connecting member and the sensing member (3) are made of stainless steel, carbon steel, hardened and tempered steel, alloy steel or spring steel.
3. The grating vector sensor according to claim 1, wherein the connecting member comprises a mounting fixing member (1) and a base (2), the mounting fixing member (1) is provided with a fixing hole (6), and the end part of the mounting fixing member is connected with the sensing member (3).
4. The grating vector sensor of claim 3, wherein the installation fixture (1) and the base (2) are both cylindrical, and the diameter of the bottom surface of the installation fixture (1) is smaller than that of the bottom surface of the base (2).
5. The grating vector sensor according to claim 3 or 4, wherein a pigtail cable terminal (5) is mounted on the base (2), and the single-mode optical fiber (8) is threaded through by the pigtail cable terminal (5) on the base (2) on one side.
6. The grating vector sensor according to claim 5, wherein the single mode fiber (8) is connected to the connection box (14) at the end that passes through the pigtail cable terminal (5), and is connected to the demodulation unit (12) through the OPGW optical cable (17).
7. The grating vector sensor according to claim 1, wherein the side surface of the sensing member (3) is sequentially provided with a plurality of grooves (4) in the circumferential direction, a sensing column is arranged between two adjacent grooves, and the fiber grating (7) is adhered to a stressed deformation area of the sensing column.
8. An overhead line icing sag state monitoring device is characterized in that a grating vector sensor according to any one of claims 3-7 is adopted, a fixing hole (6) at the upper end of the grating vector sensor is connected with a cross arm (13) of a tower through a connecting hardware fitting (10), and a fixing hole (6) at the lower end of the grating vector sensor is connected with an insulator string (16) through the connecting hardware fitting (10); the single-mode optical fiber (8) penetrates out of the tail cable terminal (5) and is connected with the joint box (14).
9. The overhead line icing sag state monitoring device according to claim 8, wherein a grating vector sensor is arranged between the tower cross arm (13) and the insulator string (15).
10. The overhead line icing sag state monitoring device according to claim 8, wherein a grating vector sensor is arranged between the insulator string (15) and the strain clamp (16).
11. The overhead line icing sag state monitoring device according to claim 8, wherein an optical fiber tilt angle sensor is arranged in the connecting hardware fitting (10), and a joint box (14) is arranged on the tower cross arm (13) and connected through a single-mode optical fiber (8).
12. A method for monitoring ice-coating sag conditions of an overhead line using the apparatus of any one of claims 8 to 11, comprising the steps of:
step 1: fixing two ends of the sensor through the ground lead wire, and applying tension F1 by a tensile machine to ensure that the ground lead wire is in a straightening state and is used for simulating the self gravity load of the ground lead wire and collecting the variation of the central wavelength;
step 2: the tensile machine applies a vertically downward tension F2 to bend and sag the ground wire to generate a sag h1 and a sag h2, and the inclination angle of the ground wire in the horizontal direction is changed into theta 1 and theta 2 to simulate the ice coating load of the ground wire and the sag change caused by ice coating and collect the variation of the central wavelength of the grating vector sensor and the inclination angle sensor;
and step 3: after the sensor is calibrated, the central wavelength is converted into the corresponding tension and inclination angle for calculating the icing thickness and the sag size.
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