POTDR-based overhead open wire fault identification method and system, and storage medium

Abstract

The invention relates to the technical field of overhead open wire fault detection, in particular to an overhead open wire fault identification method and system based on POTDR and a storage medium. The method comprises the following steps: acquiring a first operation signal of an overhead open line in normal operation under a set environmental condition; for n overhead open lines with different fault types, obtaining n fault signals; establishing a database of fault signals and fault types; changing a set environment condition, and acquiring a second operation signal of the overhead open line which operates normally; acquiring a third operation signal of the overhead open line to be detected; and collecting environmental conditions of the to-be-detected overhead open line, obtaining a correction signal of the to-be-detected overhead open line, obtaining a final fault signal, and judging the fault type of the to-be-detected overhead open line by combining the fault signal and the fault type database. According to the invention, the fault identification of the overhead open wire is more accurate.

Description

Technical Field

[0001] The invention relates to the technical field of overhead line fault detection, and in particular to an overhead line fault identification method, system and storage medium based on POTDR. Background Art

[0002] Overhead lines refer to bare wire telecommunication lines installed on the ground, which are usually used to transmit telecommunication services such as telephone, telegraph, fax and data. As overhead lines are exposed to the external environment, they are easily affected by the environment and may fail. Common types of failures include:

[0003] Broken fiber failure: The optical fiber in the optical cable is broken somewhere, causing the optical signal to be unable to pass;

[0004] Microbend fault: The optical cable is slightly bent at a certain point, affecting the transmission quality of the optical signal;

[0005] Connector loss: The loss at the optical cable connector increases, which may be due to poor connector quality or external influences;

[0006] Fiber aging: Fiber materials age over time, resulting in decreased transmission performance;

[0007] Fiber contamination: The surface or interior of the fiber is contaminated, affecting the transmission of optical signals;

[0008] Fiber misalignment: The fiber is misaligned in the splice box, resulting in interruption of optical signal transmission or increased loss;

[0009] Poor fiber splicing: Problems occurred during the fiber splicing process, resulting in increased loss at the joint.

[0010] If an optical cable fails, it will affect the normal transmission of communications. Therefore, it is necessary to detect and identify the fault of the optical cable in order to carry out timely repair and maintenance. Fiber optic sensing technology is widely used in vibration measurement, structural health monitoring and other fields due to its advantages such as anti-electromagnetic interference, corrosion resistance and long transmission distance. Traditional fault location technology includes optical time domain reflectometer (OTDR) for optical fiber fault location, but OTDR has the following problems when locating faults:

[0011] 1. Difficult to locate quickly. For example, the OTDR finds that the fault point is 10.0 km away from the test point and 870 m away from the nearest joint box. However, it is very difficult to find the corresponding joint box first and then find the corresponding fault point 870 m away from the joint box, unless the damage to the optical cable at the fault point is very obvious.

[0012] 2. It is difficult to find the target optical cable among multiple optical cables.

[0013] The above problem can be easily solved by Polarization Time Domain Reflectometry (POTDR). When the optical fiber is deformed, the polarization state of the optical signal will change starting from the deformation position. The polarization direction of the Rayleigh scattered light at the scattering point is the same as that of the incident light. By detecting the polarization state of the backward Rayleigh scattered light and the delay time of the optical signal at the incident end of the optical fiber, the position information of the optical fiber deformation can be obtained.

[0014] However, in the process of using POTDR to detect optical fiber faults, since the optical fiber is exposed to the external environment, external factors such as wind and temperature affect the optical fiber, resulting in a certain deviation between the collected signal data and the actual data, resulting in inaccurate optical fiber fault detection results. Summary of the invention

[0015] In order to solve the above technical problems existing in the prior art, the present invention provides a method, system and storage medium for identifying overhead line faults based on POTDR.

[0016] To achieve the above object, the technical solution of the present invention is as follows:

[0017] In a first aspect, the present invention provides a method for identifying an overhead line fault based on POTDR, comprising:

[0018] Step 1: Under set environmental conditions, pulse light is emitted to the normally operating overhead wire to collect the light signal scattered back by the overhead wire. The light signal is converted into an electrical signal after polarization splitting and photoelectric conversion. The electrical signal is processed to obtain a first operation signal;

[0019] Step 2: Under set environmental conditions, pulse light is emitted to n overhead wires with different fault types, and light signals scattered back from the overhead wires are collected. The light signals are converted into electrical signals after polarization splitting and photoelectric conversion, and the electrical signals are processed to obtain n fault signals;

[0020] Step 3: Using the first operation signal and the fault signal, a database of fault signals and fault types is established;

[0021] Step 4: Change the set environmental conditions, send pulse light to the normally operating overhead wire, collect the light signal scattered back by the overhead wire, the light signal is converted into an electrical signal after polarization splitting and photoelectric conversion, and the electrical signal is processed to obtain a second operation signal;

[0022] Step 5: Send pulse light to the overhead wire to be detected, collect the light signal scattered back by the overhead wire, convert the light signal into an electrical signal after polarization beam splitting and photoelectric conversion, and obtain the third operation signal after signal processing;

[0023] Step 6: Collect the environmental conditions of the overhead wire to be detected, obtain a correction signal corresponding to the overhead wire to be detected based on the environmental conditions and the second operating signal, and use the correction signal and the third operating signal to obtain a final fault signal of the overhead wire to be detected. Based on the final fault signal, combined with the database of fault signals and fault types, determine the fault type of the overhead wire to be detected.

[0024] Furthermore, the set environmental conditions in step 1 are specifically: normal temperature, no wind, no rain, and light intensity between 30000-50000 lux.

[0025] Further, in step 1, the optical signal becomes an electrical signal after polarization beam splitting and photoelectric conversion, specifically: the optical signal passes through a polarization beam splitter, the polarization beam splitter decomposes the optical signal into an X light signal and a Y light signal whose X and Y vectors are orthogonal, the X light signal and the Y light signal are respectively transmitted to an X photoelectric converter and a Y photoelectric converter, the X photoelectric converter converts the X light signal into an X electrical signal, and the Y photoelectric converter converts the Y light signal into a Y electrical signal.

[0026] Furthermore, the fault types in step 2 include fiber breakage, connector loss, fiber loss, fiber misalignment, poor fiber fusion, fiber contamination, and fiber bending.

[0027] Furthermore, in step 3, the first operating signal and the fault signal are used to establish a database of fault signals and fault types, which specifically includes: comparing the fault signal obtained in step 2 with the first operating signal, eliminating fault signals whose differences between the fault signals and the first operating signal are not obvious, and using the remaining fault signals and the first operating signal to establish a database of fault signals and fault types.

[0028] The remaining fault signals and the first operating signal are taken as input quantities, and the fault type and the fault-free type corresponding to the fault signal are taken as output quantities. The vgg16 model is used for deep learning to obtain a database of fault signals and fault types.

[0029] Furthermore, the changing of the set environmental conditions in step 4 specifically includes: changing one or more of temperature, wind level, light intensity and weather, wherein weather refers to sunny, rainy or snowy days.

[0030] Furthermore, changing one or more of the temperature, wind level, and light intensity specifically includes:

[0031] The temperature is set to 7 intervals, namely:

[0032] -40℃~-20℃, -20℃~0℃, 0℃-15℃, 15℃-25℃, 25℃-35℃, 35℃-40℃, 40℃-45℃;

[0033] The wind level is divided into 13 levels from 0 to 12 according to the Beaufort wind scale;

[0034] The light intensity is set to 6 intervals, namely:

[0035] 0-2000lux, 2000-15000lux, 15000-30000lux, 30000-50000lux, 50000-75000lux, 75000-100000lux.

[0036] Furthermore, in step 6, a correction signal corresponding to the overhead wire to be detected is obtained according to the environmental conditions and the second operation signal, specifically:

[0037] Collect the ambient temperature, wind force level, light intensity and weather of the environment where the overhead wire to be tested is located;

[0038] Determine the temperature range of the ambient temperature and obtain a temperature operation signal according to the temperature range;

[0039] Obtain wind level operation signal according to wind force level;

[0040] Determine the light intensity range in which the light intensity is located, and obtain a light operation signal according to the light intensity range;

[0041] Get weather operation signals according to the weather;

[0042] but

[0043] Correction signal = A × temperature operation signal + B × wind level operation signal + C × light operation signal + D × weather operation signal - 3 × first operation signal

[0044] Among them, A, B, C, and D are weight coefficients.

[0045] Furthermore, the ambient temperature, wind level, light intensity and weather of the environment where the overhead wire to be tested is located are compared with the set environmental conditions.

[0046] When one of the ambient temperature, wind force level, light intensity and weather is different from the corresponding item in the set environmental conditions, the weight coefficient corresponding to the different item is 1;

[0047] When two or more of the ambient temperature, wind level, light intensity and weather are different from the corresponding items in the set environmental conditions, the initial values ​​of the weight coefficients corresponding to the different items are set as: ambient temperature 0.8, wind level 0.8, light intensity 0.5, weather 0.5; if different items include both ambient temperature and wind level, the weight coefficient corresponding to the ambient temperature is reduced by 0.1; if different items include both ambient temperature and light intensity, the weight coefficient corresponding to the ambient temperature is increased by 0.1; if different items include both light intensity and weather, the weight coefficient corresponding to the light intensity is reduced by 0.1.

[0048] Furthermore, a temperature operation signal is obtained according to the temperature interval, specifically: according to the temperature interval, after the temperature in the set environmental condition is changed to the temperature interval in step 4, the second operation signal obtained is the temperature operation signal.

[0049] Furthermore, in step 6, the correction signal and the third operating signal are used to obtain a final fault signal of the overhead wire to be detected, specifically: the correction signal is subtracted from the third operating signal to obtain the final fault signal.

[0050] In a second aspect, the present invention further provides an overhead open line fault identification system based on POTDR, which executes the above-mentioned overhead open line fault identification method based on POTDR, and the overhead open line fault identification system comprises: a laser, a circulator, a polarization beam splitter, an X-photoelectric converter, a Y-photoelectric converter, a signal collector, a signal processing system, an environmental information collection system and a processing center, wherein the laser emits pulse light, and the pulse light enters the circulator; the circulator is connected to the optical fiber to be tested; the other port of the circulator is connected to the polarization beam splitter; the polarization beam splitter decomposes the optical signal into an X-light signal and a Y-light signal whose X and Y vectors are orthogonal; the X-light signal and the Y-light signal are transmitted to the X-photoelectric converter and the Y-photoelectric converter respectively;

[0051] The X photoelectric converter and the Y photoelectric converter convert the optical signal into an electrical signal and transmit it to the signal collector. The signal collector demodulates the electrical signal to obtain polarization light parameters and sends them to the signal processing system. The signal processing system obtains an operation signal or a fault signal.

[0052] The environmental information collection system is used to collect the environmental information of the optical fiber to be tested;

[0053] The processing center obtains the fault information of the optical fiber to be tested according to the operation signal or the fault signal and the environmental information.

[0054] In a third aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the above-mentioned POTDR-based overhead line fault identification method is implemented.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] The POTDR-based overhead wire fault identification method provided by the present invention first measures the operating signal of the overhead wire in normal operation under specific environmental conditions, then measures the fault signals under different fault types, and establishes a relationship database between the fault signal and the fault type; then changes the environmental conditions to measure the influence of the environmental conditions on the operating signal; then collects the operating signal of the overhead wire to be detected, uses the operating signal influenced by the environment to correct the collected operating signal of the overhead wire, obtains the final fault signal after correction, and then judges the fault information of the overhead wire, including the fault type and the fault location, so that the fault identification of the overhead wire is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a logic diagram of the method of the present invention.

[0058] Figure 2 It is a system schematic diagram of the present invention.

[0059] Figure 3 This is a schematic diagram of the demodulation process performed by the signal collector in the present invention.

[0060] Description of reference numerals:

[0061] 111. laser, 112. circulator, 113. optical fiber to be tested, 114. polarization beam splitter, 115. X-photoelectric converter, 116. Y-photoelectric converter, 117. signal collector, 118. signal processing system;

[0062] 211. Multiplier, 212. Multiplier, 213. Low-pass filter, 214. Low-pass filter. DETAILED DESCRIPTION

[0063] The technical solution of the present invention will be clearly described below in conjunction with the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present invention, and all other embodiments obtained by ordinary technicians in the field without making creative work are within the protection scope of the present invention.

[0064] It should be noted that, unless otherwise specifically stated, the relative arrangements of components and steps, and numerical expressions set forth in these embodiments should not be construed as limiting the scope of the present invention.

[0065] The following description of the exemplary embodiments is merely illustrative and is not intended to limit the present invention and its application or use in any sense. Techniques, methods and devices known to ordinary technicians in the relevant field may not be discussed in detail here, but where applicable, these techniques, methods and devices should be considered as part of this specification.

[0066] The present invention provides a method for identifying overhead open line faults based on POTDR, such as Figure 1 As shown, including:

[0067] Step 1: Under set environmental conditions, pulse light is emitted to the normally operating overhead wire to collect the light signal scattered back by the overhead wire. The light signal is converted into an electrical signal after polarization splitting and photoelectric conversion. The electrical signal is processed to obtain a first operation signal;

[0068] The environmental conditions are set as follows: normal temperature, no wind, no rain, and light intensity between 30,000-50,000 lux.

[0069] The optical signal becomes an electrical signal after polarization beam splitting and photoelectric conversion. The specific process is as follows: the optical signal passes through the polarization beam splitter, which decomposes the optical signal into an X-light signal and a Y-light signal whose X and Y vectors are orthogonal. The X-light signal and the Y-light signal are respectively transmitted to the X-photoelectric converter and the Y-photoelectric converter. The X-photoelectric converter converts the X-light signal into an X-electrical signal, and the Y-photoelectric converter converts the Y-light signal into a Y-electrical signal.

[0070] Then, the mutually orthogonal X electrical signal and Y electrical signal are input into a bandpass filter to obtain an I component and a Q component, and then an IQ demodulator is used to obtain a first operating signal.

[0071] Step 2: Under set environmental conditions, pulse light is emitted to n overhead wires with different fault types, and light signals scattered back from the overhead wires are collected. The light signals are converted into electrical signals after polarization splitting and photoelectric conversion, and the electrical signals are processed to obtain n fault signals;

[0072] The fault types include fiber breakage, joint loss, fiber loss, fiber dislocation, poor fiber fusion, fiber contamination, and fiber bending. The number of overhead open wire samples of each fault type is preferably no less than 10.

[0073] Step 3, using the first operation signal and the fault signal, establish a database of fault signals and fault types; specifically comprising: comparing the fault signal obtained in step 2 with the first operation signal, eliminating fault signals whose difference from the first operation signal is not obvious, and using the remaining fault signals and the first operation signal to establish a database of fault signals and fault types. Eliminating fault signals whose difference is not obvious can avoid false detection leading to insufficient accuracy of the database.

[0074] The remaining fault signals and the first operating signal are taken as input quantities, and the fault type and the fault-free type corresponding to the fault signal are taken as output quantities. The vgg16 model is used for deep learning to obtain a database of fault signals and fault types.

[0075] Step 4: Change the set environmental conditions, send pulse light to the normally operating overhead wire, collect the light signal scattered back by the overhead wire, the light signal is converted into an electrical signal after polarization splitting and photoelectric conversion, and the electrical signal is processed to obtain a second operation signal;

[0076] Changing the set environmental conditions specifically includes: changing one or more of temperature, wind level, light intensity and weather, wherein weather refers to sunny, rainy or snowy days.

[0077] Temperature, wind level, light intensity, including:

[0078] The temperature is set to 7 intervals, namely:

[0079] -40℃~-20℃, -20℃~0℃, 0℃-15℃, 15℃-25℃, 25℃-35℃, 35℃-40℃, 40℃-45℃;

[0080] The wind level is divided into 13 levels from 0 to 12 according to the Beaufort wind scale;

[0081] The light intensity is set to 6 intervals, namely:

[0082] 0-2000lux, 2000-15000lux, 15000-30000lux, 30000-50000lux, 50000-75000lux, 75000-100000lux.

[0083] Change the temperature, wind level, light intensity and weather according to the above ranges or levels.

[0084] Step 5: Send pulse light to the overhead wire to be detected, collect the light signal scattered back by the overhead wire, and convert the light signal into an electrical signal after polarization splitting and photoelectric conversion. The electrical signal is processed to obtain the third operation signal.

[0085] Step 6: Collect the environmental conditions of the overhead wire to be detected, and obtain the correction signal corresponding to the overhead wire to be detected according to the environmental conditions and the second operation signal, specifically:

[0086] Collect the ambient temperature, wind force level, light intensity and weather of the environment where the overhead wire to be tested is located;

[0087] Determine the temperature range of the ambient temperature and obtain a temperature operation signal according to the temperature range; specifically: according to the temperature range, after changing the temperature in the set ambient condition to the temperature range in step 4, the second operation signal obtained is the temperature operation signal.

[0088] A wind level operation signal is obtained according to the wind force level; specifically: according to the wind force level, after changing the wind level in the set environmental conditions to the corresponding wind force level in step 4, the second operation signal obtained is the wind level operation signal.

[0089] Determine the illumination intensity range in which the illumination intensity is located, and obtain the illumination operation signal according to the illumination intensity range; specifically: according to the illumination intensity range, after changing the illumination intensity in the set environmental condition to the corresponding illumination intensity range in step 4, the second operation signal obtained is the illumination operation signal.

[0090] According to the weather, a weather operation signal is obtained; specifically, according to the weather, after the weather in the set environmental condition is changed to the corresponding weather in step 4, the second operation signal obtained is the weather operation signal. If it rains, the weather is rainy, if it snows, the weather is snowy, and other conditions are all classified as sunny.

[0091] but

[0092] Correction signal = A × temperature operation signal + B × wind level operation signal + C × light operation signal + D × weather operation signal - 3 × first operation signal

[0093] Among them, A, B, C, and D are weight coefficients.

[0094] The ambient temperature, wind level, light intensity and weather of the environment where the overhead wire to be tested is located are compared with the set environmental conditions.

[0095] When one of the ambient temperature, wind force level, light intensity and weather is different from the corresponding item in the set environmental conditions, the weight coefficient corresponding to the different item is 1;

[0096] When two or more of the ambient temperature, wind level, light intensity and weather are different from the corresponding items in the set environmental conditions, the initial values ​​of the weight coefficients corresponding to the different items are set as: ambient temperature 0.8, wind level 0.8, light intensity 0.5, weather 0.5; if different items include both ambient temperature and wind level, the weight coefficient corresponding to the ambient temperature is reduced by 0.1; if different items include both ambient temperature and light intensity, the weight coefficient corresponding to the ambient temperature is increased by 0.1; if different items include both light intensity and weather, the weight coefficient corresponding to the light intensity is reduced by 0.1.

[0097] The final fault signal of the overhead wire to be detected is obtained by using the correction signal and the third operating signal. Specifically, the final fault signal is obtained by subtracting the correction signal from the third operating signal.

[0098] Based on the final fault signal, combined with the fault signal and the database of fault types, the fault type of the overhead wire to be detected is determined.

[0099] The present invention also provides an overhead wire fault identification system based on POTDR, which executes the above-mentioned overhead wire fault identification method based on POTDR, such as Figure 2 As shown, the overhead open line fault identification system includes: a laser 111, a circulator 112, a polarization beam splitter 114, an X-photoelectric converter 115, a Y-photoelectric converter 116, a signal collector 117, a signal processing system 118, an environmental information collection system and a processing center. The laser 111 emits pulse light, and the pulse light enters the circulator 112; the circulator 112 is connected to the optical fiber 113 to be tested; the other port of the circulator 112 is connected to the polarization beam splitter 114; the polarization beam splitter 114 decomposes the optical signal into an X-light signal and a Y-light signal whose X and Y vectors are orthogonal; the X-light signal and the Y-light signal are transmitted to the X-photoelectric converter 115 and the Y-photoelectric converter 116 respectively;

[0100] The X photoelectric converter 115 and the Y photoelectric converter 116 convert the optical signal into an electrical signal and transmit it to the signal collector 117. The signal collector 117 demodulates the electrical signal to obtain polarization light parameters and sends them to the signal processing system 118. The signal processing system 118 obtains an operation signal or a fault signal. Figure 3 The schematic diagram of the demodulation process performed by the signal collector 117 is shown. IQ demodulation is to construct two orthogonal signals of the same frequency according to the carrier frequency of the intermediate frequency signal to simulate the local oscillator signal L I , L Q :

[0101]

[0102] Figure 3 The input IF in L I , LQ After multiplication by multipliers 211 and 212, high frequency components are filtered out through low pass filters 213 and 214, and two orthogonal components are output: I component and Q component. Then, after division and calculation of the inverse tangent, a correlation signal is obtained.

[0103] The environmental information collection system is used to collect the environmental information of the optical fiber to be tested;

[0104] The processing center obtains the fault information of the optical fiber to be tested according to the operation signal or the fault signal and the environmental information.

[0105] In addition, the present invention provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the above-mentioned POTDR-based overhead line fault identification method is implemented.

[0106] The above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, a person skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for identifying overhead line faults based on POTDR, characterized in that: include: Step 1: Under set environmental conditions, pulse light is emitted to the normally operating overhead wire to collect the light signal scattered back by the overhead wire. The light signal is converted into an electrical signal after polarization splitting and photoelectric conversion. The electrical signal is processed to obtain a first operation signal; Step 2: Under set environmental conditions, pulse light is emitted to n overhead wires with different fault types, and light signals scattered back from the overhead wires are collected. The light signals are converted into electrical signals after polarization splitting and photoelectric conversion, and the electrical signals are processed to obtain n fault signals; Step 3: Using the first operation signal and the fault signal, establish a database of fault signals and fault types; Step 4: Change the set environmental conditions, send pulse light to the normally operating overhead wire, collect the light signal scattered back by the overhead wire, the light signal is converted into an electrical signal after polarization splitting and photoelectric conversion, and the electrical signal is processed to obtain a second operation signal; Step 5: Send pulse light to the overhead wire to be detected, collect the light signal scattered back by the overhead wire, convert the light signal into an electrical signal after polarization beam splitting and photoelectric conversion, and obtain the third operation signal after signal processing; Step 6: Collect the environmental conditions of the overhead wire to be detected, obtain a correction signal corresponding to the overhead wire to be detected based on the environmental conditions and the second operating signal, and use the correction signal and the third operating signal to obtain a final fault signal of the overhead wire to be detected. Based on the final fault signal, combined with the database of fault signals and fault types, determine the fault type of the overhead wire to be detected.

2. The method for identifying overhead wire faults according to claim 1, characterized in that: The set environmental conditions in step 1 are specifically: normal temperature, no wind, no rain, and light intensity between 30000-50000 lux.

3. The method for identifying overhead wire faults according to claim 1, characterized in that: In step 1, the optical signal becomes an electrical signal after polarization beam splitting and photoelectric conversion. Specifically, the optical signal passes through a polarization beam splitter, which decomposes the optical signal into an X optical signal and a Y optical signal whose X and Y vectors are orthogonal. The X optical signal and the Y optical signal are respectively transmitted to an X photoelectric converter and a Y photoelectric converter. The X photoelectric converter converts the X optical signal into an X electrical signal, and the Y photoelectric converter converts the Y optical signal into a Y electrical signal.

4. The method for identifying overhead wire faults according to claim 1, characterized in that: The fault types in step 2 include fiber breakage, connector loss, fiber loss, fiber misalignment, poor fiber fusion, fiber contamination, and fiber bending.

5. The method for identifying overhead wire faults according to claim 1, characterized in that: The changing of the set environmental conditions in step 4 specifically includes: changing one or more of the temperature, wind level, light intensity and weather, wherein the weather refers to sunny, rainy or snowy days.

6. The overhead wire fault identification method according to claim 5, characterized in that: Change one or more of the temperature, wind level, and light intensity, including: The temperature is set to 7 intervals, namely: -40℃～-20℃，-20℃～0℃，0℃-15℃，15℃-25℃，25℃-35℃，35℃-40℃，40℃-45℃； The wind level is divided into 13 levels from 0 to 12 according to the Beaufort wind scale; The light intensity is set to 6 intervals, namely: 0-2000lux, 2000-15000lux, 15000-30000lux, 30000-50000lux, 50000-75000lux, 75000-100000lux.

7. The method for identifying overhead wire faults according to claim 6, characterized in that: In step 6, a correction signal corresponding to the overhead wire to be detected is obtained according to the environmental conditions and the second operation signal, specifically: Collect the ambient temperature, wind force level, light intensity and weather of the environment where the overhead wire to be tested is located; Determine the temperature range of the ambient temperature and obtain a temperature operation signal according to the temperature range; Obtain wind level operation signal according to wind force level; Determine the light intensity range in which the light intensity is located, and obtain a light operation signal according to the light intensity range; Get weather operation signals according to the weather; but Correction signal = A × temperature operation signal + B × wind level operation signal + C × light operation signal + D × weather operation signal - 3 × first operation signal Among them, A, B, C, and D are weight coefficients.

8. The method for identifying overhead wire faults according to claim 7, characterized in that: The ambient temperature, wind level, light intensity and weather of the environment where the overhead wire to be tested is located are compared with the set environmental conditions. When one of the ambient temperature, wind force level, light intensity and weather is different from the corresponding item in the set environmental conditions, the weight coefficient corresponding to the different item is 1; When two or more of the ambient temperature, wind level, light intensity and weather are different from the corresponding items in the set environmental conditions, the initial values ​​of the weight coefficients corresponding to the different items are set as: ambient temperature 0.8, wind level 0.8, light intensity 0.5, weather 0.5; if different items include both ambient temperature and wind level, the weight coefficient corresponding to the ambient temperature is reduced by 0.1; if different items include both ambient temperature and light intensity, the weight coefficient corresponding to the ambient temperature is increased by 0.1; if different items include both light intensity and weather, the weight coefficient corresponding to the light intensity is reduced by 0.

1.

9. The method for identifying overhead wire faults according to claim 7, characterized in that: The temperature operation signal is obtained according to the temperature interval, specifically: according to the temperature interval, after the temperature in the set environmental condition is changed to the temperature interval in step 4, the second operation signal obtained is the temperature operation signal.

10. The overhead wire fault identification method according to claim 1, characterized in that: In step 6, the correction signal and the third operating signal are used to obtain the final fault signal of the overhead wire to be detected. Specifically, the correction signal is subtracted from the third operating signal to obtain the final fault signal.

11. A POTDR-based overhead wire fault identification system, executing the POTDR-based overhead wire fault identification method according to any one of claims 1 to 10, characterized in that: The overhead open line fault identification system comprises: a laser, a circulator, a polarization beam splitter, an X-photoelectric converter, a Y-photoelectric converter, a signal collector, a signal processing system, an environmental information collection system and a processing center. The laser emits pulse light, and the pulse light enters the circulator; the circulator is connected to the optical fiber to be tested; the other port of the circulator is connected to the polarization beam splitter; the polarization beam splitter decomposes the optical signal into an X-light signal and a Y-light signal of which the X and Y vectors are orthogonal; the X-light signal and the Y-light signal are transmitted to the X-photoelectric converter and the Y-photoelectric converter respectively; The X photoelectric converter and the Y photoelectric converter convert the optical signal into an electrical signal and transmit it to the signal collector. The signal collector demodulates the electrical signal to obtain polarization light parameters and sends them to the signal processing system. The signal processing system obtains an operation signal or a fault signal. The environmental information collection system is used to collect the environmental information of the optical fiber to be tested; The processing center obtains the fault information of the optical fiber to be tested according to the operation signal or the fault signal and the environmental information.

12. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the POTDR-based overhead line fault identification method according to any one of claims 1 to 10 is implemented.

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