Power tower geological disaster monitoring and analyzing method based on deformation detection

Abstract

The invention discloses a power tower geological disaster monitoring analysis method based on deformation detection, and belongs to the technical field of power transmission tower deformation monitoring, and the method comprises the steps: 1, building a tower line model; 2, running the tower line model through terminal software; 3, sending the data information of the terminal software to a monitoring center through a monitoring device; and step 4, analyzing the data information through a monitoring center. By arranging an FBG stress sensor, an FBG demodulation unit, a stress state monitoring device (CMD) and a monitoring center, the stress information of a key point is acquired in real time by using the FBG stress sensor, the demodulation unit demodulates an optical sensing signal, and then the CMD processes data and uploads the data through an optical fiber / local area network. Finally, expert software of a monitoring center is used for overall analysis of the iron tower, and when the external load of the iron tower is too large, early warning is performed in advance to guarantee safe operation of the line.

Description

Technical Field

[0001] The invention belongs to the technical field of deformation monitoring of transmission iron towers, and in particular relates to a method for monitoring and analyzing geological disasters of power towers based on deformation detection. Background Art

[0002] With the development of industrial automation in my country, the demand for electric energy continues to increase, bringing great challenges to the operation of the power grid. Transmission lines are not only extremely critical facilities of the power grid system, but also the main arteries for the safe and reliable operation of the power grid. Among them, transmission towers play an important supporting role for the conductors and ground wires. The safety of the towers is the basis for the reliable operation of the power grid. However, with the increase in the scale of the power grid and the increase in the voltage level of the lines, the operating conditions of the power grid will become more complicated. Transmission towers often operate under harsh conditions such as icing, wind loads, and conductor dancing, which can easily cause tower body tilting, tower base sinking, tower material deformation and other faults. Tower failure is a typical "invisible fault". During normal manual inspections of transmission lines, it is often not discovered in time. When the tower failure is discovered, the transmission line is already in a dangerous state, which seriously threatens the reliable operation of the line. In addition, transmission lines inevitably pass through special areas such as coal mining areas, soft soil areas, hillsides, and riverbeds. Affected by the terrain, line structure and natural disasters, overhead line towers in many places have experienced tower tilting, deformation, and even tower collapse. When a tower fails, it often destroys the force balance of the ground wire, causing problems such as the insulator string and the ground wire clamp to move apart, insufficient electrical safety distance, and then causing accidents such as tripping and power outages; when the problem expands, it is very easy to cause the tower to collapse and the line to break. Therefore, how to analyze the safe operation status of the transmission line tower has become an urgent problem to be solved. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a method for monitoring and analyzing geological disasters of power towers based on deformation detection, thereby solving the problems in the above-mentioned background technology.

[0004] The object of the present invention is achieved in this way: a method for monitoring and analyzing geological disasters of power towers based on deformation detection, which includes: step one, establishing a tower line model; step two, running the tower line model through terminal software; step three, sending the data information of the terminal software to a monitoring center through a monitoring device; step four, analyzing the data information through the monitoring center.

[0005] The tower line model includes:

[0006] Load calculation of ice-covered transmission line towers. The calculation formula for ice load is:

[0007] q=0.6α2γb

[0008] Where: q is the ice load acting on the unit area of ​​the tower member, in N / m 2 ; b is the ice thickness, in mm; a2 is the height increment coefficient of the ice thickness; γ is the ice weight, the ice weight includes frost and takes 9kN / m 3 , Mixed frost 6kN / m 3 and rime take 3kN / m 3 ;

[0009] The wind load calculation per unit area of ​​the tower and insulator high-rise structure is as follows:

[0010] P=β c μ s μ z μ r w o

[0011] Where: P is the wind load per unit area of ​​the tall structure, in N / m 2 ; w0 is the basic wind pressure, in N / m 2 ;μ r is the recurrence period adjustment coefficient, and the recurrence period adjustment coefficient includes 1.1 for tall structures and 1.2 for important structures; μ z is the wind pressure height variation coefficient; μ s β is the wind load body shape coefficient, and the wind load body shape coefficient includes steel and is 1.3, and other steel towers are 1.3 (1 + η); c is the tower wind load adjustment factor; η is the tower leeward load reduction factor;

[0012] The calculation formula for ice load on ground wire is:

[0013]

[0014] Where: D is the calculated outer diameter of the ground wire, in mm; b is the ice thickness, in mm; g is the local gravitational acceleration.

[0015] The terminal software adopts the transplanted UC / OS-III operating system of the STM32F407 kernel, and the operating system includes a main program, a temperature compensation program, a data storage program, an LED and a watchdog program, an interrupt program, an Ethernet communication program and a 485 communication program;

[0016] The operating system is used to collect wavelength sensing information of the fiber Bragg grating demodulation unit to realize the screening and preliminary filtering preprocessing of the original data; calibrate the initial wavelength of the on-site FBG stress sensor according to the initial temperature of the reference grating, and perform temperature compensation on the strain measurement; calculate the tower stress information of the corresponding monitoring point according to the wavelength change of the sensor; collect the ambient temperature and humidity, wind speed and direction data on the site; back up important data in real time and store them in a data storage device; and communicate data with the background monitoring center to upload data and receive instructions.

[0017] The monitoring device includes a stress sensor, a mediation unit, a CMD hardware unit and an anti-interference module; the stress sensor adopts an FBG stress sensor for real-time collection of tower stress information; the mediation unit is used for mediation of wavelength sensing signals; the CMD hardware unit is used for processing and forwarding field data;

[0018] The working process of the stress sensor includes:

[0019] When subjected to external stress, the grating period and effective refractive index change due to the photoelastic effect and waveguide effect. Considering the photoelastic effect and waveguide effect, ignoring the lateral stress, and considering the wavelength change caused by the axial stress;

[0020] The linear relationship between axial strain and temperature and the wavelength change caused by them is expressed as follows:

[0021] dλ B =2Λdn eff +2n eff dΛ

[0022]

[0023] The effects of temperature and strain on the FBG stress sensor are linearly superimposed and independent of each other. When the temperature of the FBG stress sensor does not change and only the effect of axial stress is considered, within the linear range,

[0024]

[0025] Where: Δε is the axial strain; ignoring the effect of lateral deformation on the refractive index, the refractive index change of the FBG stress sensor under axial deformation is:

[0026]

[0027] Where: p 11 and p 12 is the elastic-optic constant; γ is the Poisson’s ratio;

[0028] Let P ε =n eff2 / 2[p 12 -γ(p 11 +p 12 )]have to:

[0029]

[0030] After the material of the FBG stress sensor is determined, its sensing characteristic coefficient for strain is a constant, which is used to ensure that the FBG stress sensor has a good linear output;

[0031] After the broadband light of the stress sensor is modulated by external parameters, the light with a central wavelength satisfying the following formula is reflected back:

[0032] λ B =2n eff Λ

[0033] In the formula, λ B is the center wavelength of the reflected light, n eff is the effective refractive index of the fiber core, and Λ is the grating period.

[0034] The mediation unit includes combining the fiber grating sensor network with time division multiplexing, wavelength division multiplexing and space division multiplexing to overcome the shortcomings of the exclusivity of single-point light source, demodulation and data processing equipment; allocating the available wavelength range of the light source into independent wavelength intervals, each sensing grating occupies different frequency band resources, and when the external physical quantity changes, the reflection peak of the sensing grating changes in the respective wavelength intervals, wherein the number of available sensors depends on the dynamic range of the physical quantity to be measured and the total bandwidth of the broadband light source, and this process is used to improve the utilization rate of the broadband light source; the space division multiplexing network selects the optical path selection switch through the control circuit, each sensing grating has a separate transmission path, and only one channel is selected at any time. In the multiplexing network, each sensor is independent of each other and does not interfere with each other, and is used to realize distributed stress measurement in a larger range of spatial fields.

[0035] The CMD hardware unit includes a clock module, a 100M Ethernet module, an EEPROM module, an AD sampling module, an RS485 module, an SD card data storage module and a power module; the clock module is powered by a button battery to ensure that the clock accurately keeps time for a long time; the Ethernet module is used for real-time forwarding of data; the EEPROM module is used to store basic information; the AD sampling module is used to monitor the power supply voltage; the controller collects data through the RS485 interface, and uses an SD card based on the file system to store data for historical data query; the entire CMD hardware unit is powered by a battery plus a solar panel.

[0036] The monitoring center includes a microcontroller, a clock circuit, a watchdog reset circuit and a communication unit, which are used for data acquisition and data processing conversion; the communication unit adopts a GPRS communication mode, and the microcontroller sends AT commands to it through a serial port to perform corresponding operations, or directly configures it through supporting software; the working process includes the microcontroller controlling the conduction of the power MOS tube Q2 by changing the high and low levels of the I / O port PG5; when PG5 is at a high level, the transistor Q1 is turned on, and then drives Q2 to be turned on; when PG5 is at a low level, the transistor Q1 is turned off, causing Q2 to be turned off, and the power supply of the communication unit is cut off at this time; after the communication unit is powered on, by reading the high and low levels of the PG1 port, it is determined whether the GPRS module has been online. If PG1 is at a high level, the GPRS module is online, and if PG1 is continuously at a low level, the restart mechanism is entered; after the GPRS module is online, the microcontroller performs data communication through the serial port. The FBG stress sensor collects the stress information of the key poles of the tower in real time, and then the CMD uploads the data to the monitoring center using optical fiber / local area network. The expert software of the monitoring center analyzes the operating status of the tower based on the monitoring data, line structure, tower model, etc.

[0037] The beneficial effects of the present invention are as follows: through the fiber Bragg grating stress sensor (FBG stress sensor for short), fiber Bragg grating demodulation unit, stress state monitoring device (CMD), monitoring center and other parts. The FBG stress sensor collects stress information of key points in real time, the demodulation unit demodulates the optical sensor signal, and then the CMD processes the data and uploads it through the optical fiber / local area network, and finally the expert software of the monitoring center is used to perform an overall analysis of the iron tower, and an early warning is given when the external load of the iron tower is too large to ensure the safe operation of the line. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic diagram of the demodulation principle of the FBG stress sensor matched grating of the present invention;

[0039] Figure 2 It is a CMD hardware unit framework diagram of the present invention;

[0040] Figure 3 It is a working principle diagram of the FBG stress sensor of the present invention;

[0041] Figure 4 is a wavelength division multiplexing network diagram of a mediation unit of the present invention;

[0042] Figure 5 It is a network diagram of the mediation unit space division multiplexing of the present invention;

[0043] Figure 6 is a hardware diagram of a CMD hardware unit of the present invention;

[0044] Figure 7It is a diagram of the internal structure of a microcontroller of the present invention;

[0045] Figure 8 It is a clock circuit diagram of the present invention;

[0046] Fig. 9 It is a block diagram of the system software composition of the present invention;

[0047] Fig.10 It is the main program flow chart of the present invention. DETAILED DESCRIPTION

[0048] The present invention is further described in detail below in conjunction with the accompanying drawings. It should be pointed out that it is only for the purpose of more clearly describing and explaining the present invention.

[0049] like Figure 1-10 As shown, this embodiment discloses a method for monitoring and analyzing geological disasters of power towers based on deformation detection, which includes:

[0050] Step 1: Establish the tower line model; the main material of the transmission tower angle steel is Q345 steel, and the diagonal material and auxiliary material are Q235 steel. Considering that the transmission tower structure has strong geometric nonlinearity in actual work, the tower rods are simulated by BEAM188 beam units; due to the large distance between the two suspension points of the transmission line, the rigidity of the ground wire material has negligible influence on its geometric shape when suspended in the air, so the ground wires are simulated by LINK10 rod units; the insulator string is slender, and the overall bending moment is very small, so the rod element LINK8 used in many actual projects is selected for simulation. After completing the modeling of the main components of the tower line system, it is necessary to combine the various parts to construct the overall finite element model. The beam units of the tower modeling are rigidly connected; the ground wire rod units are connected by a dumpling chain, which belongs to the characteristics of the suspension cable structure; the insulator string is composed of suspension insulators in series, and the tower crossarm, conductor and insulator string are all connected by a dumpling chain. The external loads borne by the tower-line system of a power transmission line are closely related to the engineering operation environment of the line. In actual operation, the tower-line system bears loads of various natures. The deadweight loads of the iron tower and the ground wire are permanent loads, the wind load and the ice load are variable loads, and the loosening of the tower base (goaf, earthquake, mudslide, etc.) and the line break load are accidental loads. The present invention takes into account the load modes such as wind load, ice load and loosening of the tower base borne by the tower-line system.

[0051] The tower line model includes:

[0052] Load calculation of ice-covered transmission line towers. The calculation formula for ice load is:

[0053] q=0.6α2γb

[0054] Where: q is the ice load acting on the unit area of ​​the tower member, in N / m 2; b is the ice thickness, in mm; a2 is the height increment coefficient of the ice thickness; γ is the ice weight, the ice weight includes frost and takes 9kN / m 3 , Mixed frost 6kN / m 3 and rime take 3kN / m 3 ;

[0055] The wind load calculation per unit area of ​​the tower and insulator high-rise structure is as follows:

[0056] P=β c μ s μ z μ r w o

[0057] Where: P is the wind load per unit area of ​​the tall structure, in N / m 2 ; w0 is the basic wind pressure, in N / m 2 ;μ r is the recurrence period adjustment coefficient, and the recurrence period adjustment coefficient includes 1.1 for tall structures and 1.2 for important structures; μ z is the wind pressure height variation coefficient; μ s β is the wind load body shape coefficient, and the wind load body shape coefficient includes steel and is 1.3, and other steel towers are 1.3 (1 + η); c is the tower wind load adjustment factor; η is the tower leeward load reduction factor;

[0058] The calculation formula for ice load on ground wire is:

[0059]

[0060] Where: D is the calculated outer diameter of the ground wire, in mm; b is the ice thickness, in mm; g is the local gravitational acceleration.

[0061] When the transmission line is operating normally, the anchor bolts on the tower legs connect the tower base main material with the foundation concrete. The rigid connection between the tower and the foundation is achieved through the friction and extrusion between the anchor bolts, tower base plate and foundation concrete.

[0062] Step 2, run the tower line model through the terminal software; the terminal software is the front end of the tower stress monitoring system and the core part of the monitoring system. It mainly includes three parts: FBG stress sensor, demodulation unit and CMD. The FBG stress sensor is responsible for the real-time acquisition of the tower stress information, the demodulation unit is responsible for the demodulation of the FBG wavelength sensing signal, and the CMD realizes the processing and forwarding of the field data. Their long-term stable operation is used to ensure the reliable operation of the entire system. The terminal software adopts the transplanted UC / OS-III operating system of the STM32F407 kernel. The operating system includes a main program, a temperature compensation program, a data storage program, an LED and a watchdog program, an interrupt program, an Ethernet communication program and a 485 communication program. The range of the FBG stress sensor is an important parameter in the design process of the stress sensor. Only by determining the measurement range of the sensor can the structure and performance of the sensor be better optimized. The range of the stress sensor depends on the range of the stress strain of the elastic element material, which is essentially caused by the stress strain conduction of the transmission tower. During the normal operation of the transmission line, the most basic requirement is that the tower poles are not damaged. The range adjustment of the stress sensor according to the allowable stress of the tower material can save the tedious calculation process and leave a large enough margin. The transmission tower designed for the operating line load is made of Q345 steel as the main angle steel, and Q235 steel as the diagonal and auxiliary materials. The elastic modulus of the tower is 2.01x10 11 Pa. It is known that the allowable stress of Q345 steel is 345MPa, and the allowable stress of Q235 steel is 235MPa, so the range of the selected stress sensor is 360MPa. Under the maximum stress, the strain is 1.79×10 -3 The strain range of fiber Bragg grating is generally ±1000με~±2000με, which can cover the strain range of tower materials.

[0063] The operating system is used to collect wavelength sensing information of the fiber grating demodulation unit to achieve screening and preliminary filtering preprocessing of raw data; calibrate the initial wavelength of the on-site FBG stress sensor according to the initial temperature of the reference grating, and perform temperature compensation on the strain measurement; calculate the tower stress information of the corresponding monitoring point according to the wavelength change of the sensor; collect the ambient temperature and humidity, wind speed and direction data of the site; back up important data in real time and store it in a data storage device; communicate data with the background monitoring center to upload data and receive instructions. Since the fiber grating sensor is sensitive to both strain and temperature, temperature compensation is required when measuring strain parameters. The cross-sensitivity problem of strain and temperature can be solved by referring to the fiber grating method, the dual parameter matrix method, the dual wavelength stacking method, etc. The present invention adopts the method of referring to the fiber grating for temperature compensation to eliminate the error caused by temperature drift.

[0064] Since the effects of temperature and strain on the wavelength change of FBG are a linear superposition of the two, the reference fiber Bragg grating method is the simplest and most effective way to solve the problem of strain-temperature cross-sensitivity. By using a fiber Bragg grating that is only affected by temperature as a reference, and since the reference fiber is only affected by temperature alone, temperature compensation for strain can be achieved by subtracting the wavelengths of the two.

[0065] Step 3: Send the data information of the terminal software to the monitoring center through the monitoring device; the monitoring device includes a stress sensor, a mediation unit, a CMD hardware unit and an anti-interference module; the stress sensor adopts an FBG stress sensor for real-time collection of tower stress information; the mediation unit is used for mediation of wavelength sensing signals; the CMD hardware unit is used for processing and forwarding field data;

[0066] The working process of the stress sensor includes:

[0067] When subjected to external stress, the grating period and effective refractive index change due to the photoelastic effect and waveguide effect. Considering the photoelastic effect and waveguide effect, ignoring the lateral stress, and considering the wavelength change caused by the axial stress;

[0068] The linear relationship between axial strain and temperature and the wavelength change caused by them is expressed as follows:

[0069] dλ B =2Λdn eff +2n efd dΛ

[0070]

[0071] The effects of temperature and strain on the FBG stress sensor are linearly superimposed and independent of each other. When the temperature of the FBG stress sensor does not change and only the effect of axial stress is considered, within the linear range,

[0072]

[0073] Where: Δε is the axial strain; ignoring the effect of lateral deformation on the refractive index, the refractive index change of the FBG stress sensor under axial deformation is:

[0074]

[0075] Where: p 11 and p 12 is the elastic-optic constant; γ is the Poisson’s ratio;

[0076] Let P ε =n eff 2 / 2[p 12 -γ(p11 +p 12 )]have to:

[0077]

[0078] After the material of the FBG stress sensor is determined, its sensing characteristic coefficient for strain is a constant, which is used to ensure that the FBG stress sensor has a good linear output;

[0079] After the broadband light of the stress sensor is modulated by external parameters, the light with a central wavelength satisfying the following formula is reflected back:

[0080] λ B =2n eff Λ

[0081] In the formula, λ B is the center wavelength of the reflected light, n eff is the effective refractive index of the fiber core, and Λ is the grating period.

[0082] The mediation unit includes combining the fiber grating sensor network with time division multiplexing, wavelength division multiplexing and space division multiplexing to overcome the shortcomings of the exclusivity of single-point light source, demodulation and data processing equipment; allocating the available wavelength range of the light source into independent wavelength intervals, each sensing grating occupies different frequency band resources, and when the external physical quantity changes, the reflection peak of the sensing grating changes in the respective wavelength intervals, wherein the number of available sensors depends on the dynamic range of the physical quantity to be measured and the total bandwidth of the broadband light source, and this process is used to improve the utilization rate of the broadband light source; the space division multiplexing network selects the optical path selection switch through the control circuit, each sensing grating has a separate transmission path, and only one channel is selected at any time. In the multiplexing network, each sensor is independent of each other and does not interfere with each other, and is used to realize distributed stress measurement in a larger range of spatial fields.

[0083] The CMD hardware unit includes a clock module, a 100M Ethernet module, an EEPROM module, an AD sampling module, an RS485 module, an SD card data storage module and a power module; the clock module is powered by a button battery to ensure that the clock accurately keeps time for a long time; the Ethernet module is used for real-time forwarding of data; the EEPROM module is used to store basic information; the AD sampling module is used to monitor the power supply voltage; the controller collects data through the RS485 interface, and uses an SD card based on the file system to store data for historical data query; the entire CMD hardware unit is powered by a battery plus a solar panel.

[0084] Step 4, analyzing the data information through the monitoring center; the monitoring center includes a microcontroller, a clock circuit, a watchdog reset circuit and a communication unit for data acquisition and data processing conversion; the communication unit adopts GPRS communication mode, and the microcontroller sends AT commands to it through the serial port to perform corresponding operations, or directly configures it through supporting software; the working process includes the microcontroller controlling the conduction of the power MOS tube Q2 by changing the high and low levels of the I / O port PG5; when PG5 is at a high level, the transistor Q1 is turned on, and then drives Q2 to be turned on; when PG5 is at a low level, the transistor Q1 is turned off, causing Q2 to be turned off, and the power supply of the communication unit is cut off at this time; after the communication unit is powered on, by reading the high and low levels of the PG1 port, it is determined whether the GPRS module is online. If PG1 is at a high level, the GPRS module is online. If PG1 is continuously at a low level, the restart mechanism is entered; after the GPRS module is online, the microcontroller performs data communication through the serial port. The FBG stress sensor collects the stress information of the key poles of the tower in real time, and then the CMD uploads the data to the monitoring center using optical fiber / local area network. The expert software of the monitoring center analyzes the operating status of the tower based on the monitoring data, line structure, tower model, etc.

[0085] The above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for monitoring and analyzing geological disasters of power towers based on deformation detection, characterized in that: include: Step 1: Establish a tower line model; Step 2: running the tower line model through terminal software; Step 3: Sending the data information of the terminal software to the monitoring center through the monitoring device; Step 4: Analyze the data information through the monitoring center.

2. The method for monitoring and analyzing geological disasters of power towers based on deformation detection according to claim 1 is characterized in that: The tower line model includes: Load calculation of ice-covered transmission line towers. The calculation formula for ice load is: q=0.6α2γb Where: q is the ice load acting on the unit area of ​​the tower member, in N / m 2 ; b is the ice thickness, in mm; a2 is the height increment coefficient of ice thickness; γ is the ice coverage weight, the ice coverage weight includes frost and takes 9kN / m 3 , Mixed frost 6kN / m 3 and rime take 3kN / m 3 ; The wind load calculation per unit area of ​​the tower and insulator high-rise structure is as follows: P=β c m s m z m r w o Where: P is the wind load per unit area of ​​the tall structure, in N / m 2 ; w0 is the basic wind pressure, in N / m 2 ;μ r is the recurrence period adjustment coefficient, and the recurrence period adjustment coefficient includes 1.1 for tall structures and 1.2 for important structures; μ z is the wind pressure height variation coefficient; μ s β is the wind load body shape coefficient, and the wind load body shape coefficient includes steel and is 1.3, and other steel towers are 1.3 (1 + η); c is the tower wind load adjustment factor; η is the tower leeward load reduction factor; The calculation formula for ice load on ground wire is: Where: D is the calculated outer diameter of the ground wire, in mm; b is the ice thickness, in mm; g is the local gravitational acceleration.

3. The method for monitoring and analyzing geological disasters of power towers based on deformation detection according to claim 1 is characterized in that: The terminal software adopts the transplanted UC / OS-III operating system of the STM32F407 kernel, and the operating system includes a main program, a temperature compensation program, a data storage program, an LED and a watchdog program, an interrupt program, an Ethernet communication program and a 485 communication program; The operating system is used to collect wavelength sensing information of the fiber Bragg grating demodulation unit, realize the screening and preliminary filtering preprocessing of the original data; calibrate the initial wavelength of the on-site FBG stress sensor according to the initial temperature of the reference grating, and perform temperature compensation on the strain measurement; calculate the tower stress information of the corresponding monitoring point according to the wavelength change of the sensor; collect the environmental temperature and humidity, wind speed and direction data on the site; Back up important data in real time and store it in data storage; Communicate data with the background monitoring center to upload data and receive instructions.

4. The method for monitoring and analyzing geological disasters of power towers based on deformation detection according to claim 1 is characterized in that: The monitoring device includes a stress sensor, a mediation unit, a CMD hardware unit and an anti-interference module; the stress sensor adopts an FBG stress sensor for real-time collection of tower stress information; the mediation unit is used for mediation of wavelength sensing signals; The CMD hardware unit is used for processing and forwarding field data; The working process of the stress sensor includes: When subjected to external stress, the grating period and effective refractive index change due to the photoelastic effect and waveguide effect. Considering the photoelastic effect and waveguide effect, ignoring the lateral stress, and considering the wavelength change caused by the axial stress; The linear relationship between axial strain and temperature and the wavelength change caused by them is expressed as follows: dλ B =2Λdn eff +2n eff dΛ The effects of temperature and strain on the FBG stress sensor are linearly superimposed and independent of each other. When the temperature of the FBG stress sensor does not change and only the effect of axial stress is considered, within the linear range, Where: Δ ε is the axial strain; ignoring the effect of lateral deformation on the refractive index, the refractive index change of the FBG stress sensor under axial deformation is: Where: p 11 and p 12 is the elastic-optical constant; γ is Poisson's ratio; Let P ε =n eff 2 / 2[p 12 -γ(p 11 +p 12 )]have to: After the material of the FBG stress sensor is determined, its sensing characteristic coefficient for strain is a constant, which is used to ensure that the FBG stress sensor has a good linear output; After the broadband light of the stress sensor is modulated by external parameters, the light with a central wavelength satisfying the following formula is reflected back: l B =2n eff L In the formula, λ B is the center wavelength of the reflected light, n eff is the effective refractive index of the fiber core, and Λ is the grating period.

5. The method for monitoring and analyzing geological disasters of power towers based on deformation detection according to claim 4 is characterized in that: The mediation unit includes combining the fiber grating sensor network with time division multiplexing, wavelength division multiplexing and space division multiplexing to overcome the shortcomings of the exclusivity of single-point light source, demodulation and data processing equipment; allocating the available wavelength range of the light source into independent wavelength intervals, each sensing grating occupies different frequency band resources, and when the external physical quantity changes, the reflection peak of the sensing grating changes in the respective wavelength intervals, wherein the number of available sensors depends on the dynamic range of the physical quantity to be measured and the total bandwidth of the broadband light source, and this process is used to improve the utilization rate of the broadband light source; the space division multiplexing network selects the optical path selection switch through the control circuit, each sensing grating has a separate transmission path, and only one channel is selected at any time. In the multiplexing network, each sensor is independent of each other and does not interfere with each other, and is used to realize distributed stress measurement in a larger range of spatial fields.

6. The method for monitoring and analyzing geological disasters of power towers based on deformation detection according to claim 4 is characterized in that: The CMD hardware unit includes a clock module, a 100M Ethernet module, an EEPROM module, an AD sampling module, an RS485 module, an SD card data storage module and a power module; the clock module is powered by a button battery to ensure that the clock accurately keeps time for a long time; the Ethernet module is used for real-time forwarding of data; the EEPROM module is used to store basic information; the AD sampling module is used to monitor the power supply voltage; the controller collects data through the RS485 interface, and uses an SD card based on the file system to store data for historical data query; the entire CMD hardware unit is powered by a battery plus a solar panel.

7. The method for monitoring and analyzing geological disasters of power towers based on deformation detection according to claim 1 is characterized in that: The monitoring center includes a microcontroller, a clock circuit, a watchdog reset circuit and a communication unit, which are used for data acquisition and data processing conversion; the communication unit adopts a GPRS communication mode, and the microcontroller sends AT commands to it through a serial port to perform corresponding operations, or directly configures it through supporting software; the working process includes the microcontroller controlling the conduction of the power MOS tube Q2 by changing the high and low levels of the I / O port PG5; when PG5 is at a high level, the transistor Q1 is turned on, and then drives Q2 to be turned on; when PG5 is at a low level, the transistor Q1 is turned off, causing Q2 to be turned off, and the power supply of the communication unit is cut off at this time; after the communication unit is powered on, by reading the high and low levels of the PG1 port, it is determined whether the GPRS module has been online. If PG1 is at a high level, the GPRS module is online, and if PG1 is continuously at a low level, the restart mechanism is entered; after the GPRS module is online, the microcontroller performs data communication through the serial port.

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