阅读说明：本技术 基于光纤光栅的光缆接头盒湿度监测方法及系统 (Optical cable joint box humidity monitoring method and system based on fiber bragg grating ) 是由 李任新 朱一峰 陈保豪 田霖 张承亮 陆国生 于 2021-07-19 设计创作，主要内容包括：本发明公开了基于光纤光栅的光缆接头盒湿度监测方法及系统,一种电力光缆保护方法,所述方法包括在规划的局域内,选定一根待保护电力光缆,并在电力光缆上等距离安装若干个光缆接头盒；在每个光缆接头盒中均安装一个传感器,局域内的若干个传感器共同形成实时监测组网；若干个传感器所形成的监测组网通过光纤与实时分析装置通讯连接,实时分析装置将各个传感器实时监测的信号转化后,传输给远程终端；远程终端实时显示传感器在光缆接头盒内监测的数据信息,该方法从根本上解决了因光缆接头盒长期使用后,密封不良,导致雨水或潮气进入电力光缆接头盒内部,造成光纤断裂或者光纤损耗进一步增大,从而严重威胁光缆线路的运行安全的问题。(The invention discloses a fiber grating-based optical cable joint box humidity monitoring method and a fiber grating-based optical cable joint box humidity monitoring system, and a power optical cable protection method comprises the steps of selecting an optical power cable to be protected in a planned local area, and installing a plurality of optical cable joint boxes on the optical power cable at equal distances; a sensor is arranged in each optical cable joint box, and a plurality of sensors in a local area form a real-time monitoring networking together; the monitoring network formed by a plurality of sensors is in communication connection with the real-time analysis device through optical fibers, and the real-time analysis device converts signals monitored by the sensors in real time and transmits the converted signals to the remote terminal; the method fundamentally solves the problem that after the optical cable joint box is used for a long time, due to poor sealing, rainwater or moisture enters the power optical cable joint box, so that optical fibers are broken or the loss of the optical fibers is further increased, and the operation safety of an optical cable line is seriously threatened.)

1. The optical cable joint box humidity monitoring method based on the fiber bragg grating is characterized by comprising the following steps of:

selecting an electric power optical cable to be protected in a planned local area, and mounting a plurality of optical cable joint boxes on the electric power optical cable at equal distances;

a sensor is arranged in each optical cable joint box, and a plurality of sensors in a local area form a real-time monitoring networking together;

the monitoring network formed by the sensors is in communication connection with a real-time analysis device through optical fibers, and the real-time analysis device converts signals monitored by the sensors in real time and transmits the converted signals to a remote terminal;

and the remote terminal displays the data information monitored by the sensor in the optical cable joint box in real time through built-in software.

2. The fiber grating-based optical cable joint box humidity monitoring method according to claim 1, wherein the optical cable joint box comprises a joint (101) and a joint (102) fixedly connected above the joint (101) and having a matched size, the joint (103) is fixedly connected to the bottom end of the joint (101), the joint (104) is fixedly installed inside the joint (101), one joint (105) penetrates through the joint (101) and the joint (102), the joint (105) passes through the inside of the joint (104), the joint (106) and the joint (107) are respectively opened at the edge between the joint (101) and the joint (102), the joint (106) and the joint (107) are communicated, a joint (108) is arranged between the joint (101) and the joint (102), and a plurality of groups of sensors form a communication connection structure through one optical fiber core in the joint (105).

3. The fiber grating-based humidity monitoring method for cable closures according to claim 1, wherein a sensor is installed in each cable closure, and after the step of forming a real-time monitoring network by a plurality of sensors in a local area, the method further comprises:

in the optical cable joint box, the change of temperature and humidity can promote the Bragg reflection wavelength of the FBGAnddrift occurs and the variation is respectivelyAndso as to calculate the temperature and humidity change values and compensate the temperature cross sensitivity of the humidity measurement.

4. The moisture monitoring method for the fiber grating-based optical cable joint box according to claim 3, wherein the sensor is a fiber grating sensor, the fiber grating sensor comprises a T-shaped structure (201), a layer (202) is coated on the outer portion of the T-shaped structure (201), a layer (203) is arranged on the inner portion of the T-shaped structure (201), a layer (204) sensitive to temperature and moisture and a layer (205) sensitive to temperature only are arranged in the layer (203), the coating layer of the layer (204) is the layer (202), the layer (202) is a modified polyimide moisture sensitive film, and the layer (204) and the layer (205) are connected in series.

5. The fiber grating-based fiber optic cable closure humidity monitoring method of claim 3, wherein the variation is utilizedAndthe formula for calculating the temperature and humidity change values is as follows:

according to the coupled mode theory, FBG reflects the wavelength（=1, 2) satisfies the following formula:

（1）

in the formula (I), the compound is shown in the specification,is the effective refractive index of the FBG;（=1, 2) FBGThe grating period of (a); the first term on the right hand side of the equation is the amount of change from relative humidityInduced elasto-optic effect and temperature variationThe result of the combined action of the induced thermo-optic effects; the second term isAnd FBG axial strain due to thermal expansion.

6. The fiber grating-based fiber optic cable closure humidity monitoring method of claim 5, wherein the moisture-sensitive coating layer and the optical fiber are constrained to each other,inducing axial strain of the FBG1The difference between the axial strain and the constrained strain in the free state can be obtained from the elastic theory:

（2）

（3）

in the formula、、The wet expansion coefficient, Poisson's ratio and elastic modulus of the humidity sensitive film are respectively;、the diameters of the cross sections of the humidity-sensitive film and the optical fiber cladding are respectively; considering the elasto-optic effect, thermo-optic effect, and thermal expansion effect, the relative variation of the reflected wavelength of the FBG1 can be expressed as:

(4)

in the formula、Respectively, the effective elasto-optic coefficient and the thermo-optic coefficient of the optical fiber;the linear expansion coefficients of the humidity-sensitive film and the optical fiber are respectively;、temperature and relative humidity sensitivity coefficients of the FBG1, respectively;

for FBG2, the reason is that，Therefore:

(5)

solving the formulas (4) and (5) to obtain the variation value of the relative humidityAnd temperature variation value。

7. A system for use in the fiber grating based fiber optic cable closure humidity monitoring method of any one of claims 1-6, comprising:

the sensors (3) are arranged and used for monitoring humidity data in the optical cable joint box in real time and transmitting the humidity data by using optical signals;

the analysis device (4) is in communication connection with the sensors (3), collects optical signals transmitted by each sensor (3), and converts the optical signals into humidity signals;

and the industrial control host (5) is used for processing the humidity signal acquired by the analysis device (4) in real time.

8. The fiber grating-based optical cable splice closure humidity monitoring system of claim 7, wherein said sensor (3) is a fiber grating humidity sensor, said analyzing device (4) is a fiber grating network analyzer, and said industrial host (5) is a monitoring computer.

Technical Field

The invention relates to a method for protecting an electric power optical cable, in particular to a method and a system for monitoring the humidity of an optical cable joint box based on fiber bragg gratings.

Background

In the operation process of the power optical cable, the communication loss of the power optical cable is increased frequently, the communication quality of a circuit is influenced, and the normal service life of the power optical cable is seriously threatened. According to inspection, the main reason is that the existing power cable joint box has poor sealing, so that rainwater or moisture enters the interior of the power cable joint box, and once the optical fibers meet water or moisture, hydrogen loss can be generated, so that the damage to the optical fibers is increased. Furthermore, if the optical fiber is soaked in water for a long time, the surface of the optical fiber is damaged to generate cracks, so that the optical fiber is broken or the loss of the optical fiber is further increased, and the operation safety of the optical cable line is seriously threatened.

Therefore, the method and the system for monitoring the humidity of the optical cable joint box based on the fiber bragg grating are provided by the technical personnel in the field.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a fiber grating-based optical cable joint box humidity monitoring method and system, which solve the problems that the existing power optical cable joint box has poor sealing, rainwater or moisture enters the interior of the power optical cable joint box, and once the optical fiber meets water or moisture, hydrogen loss is generated, so that the damage to the optical fiber is increased. Furthermore, if the optical fiber is soaked in water for a long time, the surface of the optical fiber is damaged to generate cracks, so that the optical fiber is broken or the loss of the optical fiber is further increased, and the operation safety of the optical cable line is seriously threatened.

In order to achieve the purpose, the invention is realized by the following technical scheme:

in a first aspect, the invention provides a fiber grating-based optical cable splice closure humidity monitoring method, which comprises the following steps:

selecting an electric power optical cable to be protected in a planned local area, and mounting a plurality of optical cable joint boxes on the electric power optical cable at equal distances;

a sensor is arranged in each optical cable joint box, and a plurality of sensors in a local area form a real-time monitoring networking together;

the monitoring network formed by the sensors is in communication connection with a real-time analysis device through optical fibers, and the real-time analysis device converts signals monitored by the sensors in real time and transmits the converted signals to a remote terminal;

and the remote terminal displays the data information monitored by the sensor in the optical cable joint box in real time through built-in software.

Furthermore, the optical cable joint box comprises a plurality of groups of optical fiber cores, the optical fiber cores are fixedly connected to the upper part of the optical cable joint box, the optical fiber cores are matched in size, the bottom end of the optical cable joint box is fixedly connected with the bottom end of the optical cable joint box, one optical fiber core penetrates through the inner part of the optical cable joint box, the edges between the optical cable joint box and the optical fiber core are respectively provided with a junction, the junction is communicated with the junction, and a plurality of groups of sensors form a communication connection structure through the optical fiber cores.

Further, a sensor is installed in each optical cable joint box, and after the step of forming real-time monitoring networking by a plurality of sensors in a local area, the method further comprises the following steps:

in the optical cable joint box, the change of temperature and humidity can promote the Bragg reflection wavelength of the FBGAnddrift occurs and the variation is respectivelyAndso as to calculate the temperature and humidity change values and compensate the temperature cross sensitivity of the humidity measurement.

Furthermore, the sensor is a fiber grating sensor, the fiber grating sensor comprises a T-shaped structure, the outer part of the fiber grating sensor is coated with a layer, the inner part of the fiber grating sensor is provided with a layer, the layer is used for being sensitive to temperature and humidity and only sensitive to temperature, and the coating layer is a modified polyimide humidity sensitive film which is connected in series.

Further, using the variationAndthe formula for calculating the temperature and humidity change values is as follows:

according to the coupled mode theory, FBG reflects the wavelengthSatisfies the following formula:

（1）

in the formula (I), the compound is shown in the specification,is the effective refractive index of the FBG;as FBGThe grating period of (a); the first term on the right hand side of the equation is the amount of change from relative humidityInduced elasto-optic effect and temperature variationThe result of the combined action of the induced thermo-optic effects; the second term isAnd FBG axial strain due to thermal expansion.

Further, since the moisture-sensitive coating layer and the optical fiber are constrained to each other,inducing axial strain of the FBG1The difference between the axial strain and the constrained strain in the free state can be obtained from the elastic theory:

（2）

（3）

in the formula、、The wet expansion coefficient, Poisson's ratio and elastic modulus of the humidity sensitive film are respectively;、the diameters of the cross sections of the humidity-sensitive film and the optical fiber cladding are respectively; considering the elasto-optic effect, thermo-optic effect, and thermal expansion effect, the relative variation of the reflected wavelength of the FBG1 can be expressed as:

(4)

in the formula、Respectively, the effective elasto-optic coefficient and the thermo-optic coefficient of the optical fiber;the linear expansion coefficients of the humidity-sensitive film and the optical fiber are respectively;、temperature and relative humidity sensitivity coefficients of the FBG1, respectively;

for FBG2, the reason is that，Therefore:

(5)

solving the equations (4) andequation (5), the change value of the relative humidity can be obtainedAnd temperature variation value。

In a second aspect, the present invention provides a system for the fiber grating-based optical cable closure humidity monitoring method, including:

the sensors are arranged and used for monitoring humidity data in the optical cable joint box in real time and transmitting the humidity data by using optical signals;

the analysis device is in communication connection with the sensors, collects optical signals transmitted by the sensors and converts the optical signals into humidity signals;

and the industrial control host is used for processing the humidity signal acquired by the analysis device in real time.

Furthermore, the sensor is a fiber grating humidity sensor, the analysis device is a fiber grating network analyzer, and the industrial control host is a monitoring computer.

Advantageous effects

The invention provides a fiber grating-based optical cable joint box humidity monitoring method and system. Compared with the prior art, the method has the following beneficial effects:

the method for monitoring the humidity of the optical cable joint box based on the fiber bragg grating fundamentally solves the problem that the operation safety of an optical cable line is seriously threatened due to the fact that the optical cable joint box is badly sealed after being used for a long time, rainwater or moisture enters the interior of the power optical cable joint box and the optical fiber is broken or the loss of the optical fiber is further increased due to the fact that the optical cable joint box is badly sealed after the optical cable joint box is used for a long time.

Correspondingly, the optical cable joint box humidity monitoring system based on the fiber bragg grating also has the technical effects.

Drawings

FIG. 1 is a block flow diagram of a monitoring method of the present invention;

FIG. 2 is a schematic view of the construction of the cable closure of the present invention;

FIG. 3 is a schematic diagram of the sensor of the present invention;

FIG. 4 is a schematic diagram of a monitoring system according to the present invention;

FIG. 5 is a diagram of a device status display interface of the present invention;

FIG. 6 is a diagram of a sensor temperature status display interface in accordance with the present invention;

FIG. 7 is a diagram of a sensor real-time data tracking interface according to the present invention;

FIG. 8 is a diagram of a history query interface in accordance with the present invention;

FIG. 9 is a diagram of an equipment management function interface of the present invention;

FIG. 10 is a diagram of a sensor management function interface according to the present invention;

FIG. 11 is a diagram of a user management function interface in accordance with the present invention.

In the figure: 101. a box body; 102. a box cover; 103. fixing a bracket; 104. an optical unit splice tray; 105. an optical cable; 106. injecting ant-proof glue into the hole; 107. an ant-proof glue groove; 108. a gasket; 201. a carrier; 202. a PI coating layer; 203. a cladding layer; 204. fiber bragg grating FBG 1; 205. a fiber bragg grating FBG 2.

Detailed Description

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 only a part of the embodiments of the present invention, and not all of the embodiments. 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.

Referring to fig. 1, an embodiment of the present invention provides a technical solution: the optical cable joint box humidity monitoring method based on the fiber bragg grating comprises the following steps:

s1, selecting an electric power optical cable to be protected in the planned local area, and mounting a plurality of optical cable joint boxes on the electric power optical cable at equal distances;

s2, installing a sensor in each optical cable joint box, wherein a plurality of sensors in a local area form a real-time monitoring networking together;

s3, in the optical cable joint box, the change of temperature and humidity can promote the Bragg reflection wavelength of the FBGAnddrift occurs and the variation is respectivelyAndso as to calculate the temperature and humidity change values and compensate the temperature cross sensitivity of the humidity measurement;

using the amount of variationAndthe formula for calculating the temperature and humidity change values is as follows:

according to the coupled mode theory, FBG reflects the wavelength =1, 2 satisfies the following formula:

（1）

in the formula (I), the compound is shown in the specification,is the effective refractive index of the FBG; =1, 2 is FBGThe grating period of (a); the first term on the right hand side of the equation is the amount of change from relative humidityInduced elasto-optic effect and temperature variationThe result of the combined action of the induced thermo-optic effects; the second term isAnd FBG axial strain due to thermal expansion.

Further, since the moisture-sensitive coating layer and the optical fiber are constrained to each other,inducing axial strain of the FBG1The difference between the axial strain and the constrained strain in the free state can be obtained from the elastic theory:

（2）

（3）

in the formula、、The wet expansion coefficient, Poisson's ratio and elastic modulus of the humidity sensitive film are respectively;、the diameters of the cross sections of the humidity-sensitive film and the optical fiber cladding are respectively; considering the elasto-optic effect, thermo-optic effect, and thermal expansion effect, the relative variation of the reflected wavelength of the FBG1 can be expressed as:

（4）

in the formula、Respectively, the effective elasto-optic coefficient and the thermo-optic coefficient of the optical fiber;the linear expansion coefficients of the humidity-sensitive film and the optical fiber are respectively;、temperature and relative humidity sensitivity coefficients of the FBG1, respectively;

for FBG2, the reason is that，Therefore:

（5）

solving the formulas (4) and (5) to obtain the variation value of the relative humidityAnd temperature variation value。

S4, a monitoring network formed by a plurality of sensors is in communication connection with a real-time analysis device through optical fibers, and the real-time analysis device converts signals monitored by the sensors in real time and transmits the converted signals to a remote terminal;

and S5, displaying the data information monitored by the sensor in the optical cable joint box in real time by the remote terminal through built-in software.

Referring to fig. 2, the optical cable joint box includes a 101 and a 102 fixedly connected above the 101 and having a size adapted to the size, a 103 is fixedly connected to a bottom end of the 101, a 104 is fixedly installed inside the 101, a 105 and a 105 pass through the 104 inside the 101 and the 102, 106 and 107 are respectively opened at an edge between the 101 and the 102, the 106 and the 107 are communicated, 108 is provided between the 101 and the 102, and a plurality of groups of sensors form a communication connection structure through an optical fiber core in the 105.

Referring to fig. 3, the sensor is a fiber grating sensor, the fiber grating sensor includes a T-shaped structure 201, a layer 202 is coated on the outside of the 201, a layer 203 is disposed on the inside of the 201, a layer 202 is disposed in the layer 203 for sensing temperature and humidity 204 and a layer 205 and 204 only sensing temperature, the coating layers 202 and 202 are modified polyimide moisture sensitive films, and the layers 204 and 205 are connected in series.

Referring to fig. 4, an embodiment of the present invention further provides a system, where the system is used in the method for monitoring humidity of an optical cable splice closure based on fiber bragg grating, and the method includes:

the sensors 3 are arranged and used for monitoring humidity data in the optical cable joint box in real time and transmitting the humidity data by using optical signals;

the analysis device 4 is in communication connection with the plurality of sensors 3, collects optical signals transmitted by each sensor 3 and converts the optical signals into humidity signals;

and the industrial control host 5 is used for processing the humidity signal acquired by the analysis device 4 in real time.

The sensor 3 is a fiber grating humidity sensor, the analysis device 4 is a fiber grating network analyzer, and the industrial control host 5 is a monitoring computer.

In addition, the system also relates to a software part, the software is internally installed in the industrial control host 5, a functional interface of the software refers to fig. 5-11, and after the system is used together with the software, the soft solution function comprises:

1. the equipment state display mainly comprises the equipment number, the online number, the temperature sensor number and the humidity sensor number;

2. displaying the temperature and humidity state of the sensor, wherein the temperature and humidity state mainly comprises a channel number, a real-time wavelength and a physical value;

3. the sensor tracks data in real time, and real-time temperature and humidity changes can be visually checked;

4. historical record query, which can query the historical temperature and humidity value of the sensor;

5. the equipment management function can increase equipment at any time along with the rise of the traffic;

6. a sensor management function, which can configure a new sensor at any time along with the increase of the traffic;

7. the user management function can assign different authorities to the operating users.

Through above-mentioned software function, can let the user more quick and effectual come the inside condition of real-time supervision optical cable splice box through the sensor, acquire data information in real time to in time solve, avoid causing loss and harm.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.