ABNORMAL DETECTION PROGRAM, ABNORMAL DETECTION DEVICE, AND ABNORMAL DETECTION METHOD

Abstract

To easily detect a power transmission facility.SOLUTION: The present invention relates to an abnormality detection program for causing a computer to execute processing of acquiring rear Rayleigh scattering light from an optical fiber composite overhead earth wire of a power transmission facility, generating vibration information about a frequency region including the unique vibration number of the optical fiber composite overhead earth wire, and detecting an abnormality in the power transmission facility on the basis of the generated vibration information.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an abnormality detection program, an abnormality detection device, and an abnormality detection method. [Background technology]

[0002] Power transmission equipment such as power lines, steel towers, and overhead ground wires deteriorate due to natural disasters and aging, which can disrupt the stable supply of electricity. To prevent this, it is desirable to monitor the power transmission equipment and, if an abnormality is detected, to carry out appropriate maintenance.

[0003] There are two methods for monitoring power transmission facilities: manual monitoring, and monitoring using drones or helicopters. Manual monitoring requires workers to climb steel towers, which is dangerous. Also, monitoring using drones or helicopters is expensive because the area to be monitored is large.

[0004] On the other hand, it is also possible to install vibration sensors in power transmission facilities and monitor the vibrations measured by the vibration sensors to see if there are any abnormalities in the power transmission facilities. However, the area in which vibration sensors can detect vibrations is very narrow, so a huge number of vibration sensors would be required to monitor an area of, for example, several hundred kilometers. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. WO2020 / 044655 [Patent Document 2] Japanese Patent Application Publication No. 2018-141663 Summary of the Invention [Problem to be solved by the invention]

[0006] According to one aspect, an object is to easily detect abnormalities in power transmission equipment. [Means for solving the problem]

[0007] According to one aspect, an abnormality detection program is provided for causing a computer to execute a process of acquiring backward Rayleigh scattered light from an optical fiber composite overhead ground wire provided in a power transmission facility, generating vibration information for a frequency range including the natural frequency of the optical fiber composite overhead ground wire based on the backward Rayleigh scattered light, and detecting an abnormality in the power transmission facility based on the generated vibration information. [Effects of the Invention]

[0008] According to one aspect, abnormalities in power transmission equipment can be easily detected. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a power transmission facility. [Figure 2] FIG. 2(a) is a cross-sectional view of the OPGW taken along a plane perpendicular to the direction in which the OPGW extends, and FIG. 2(b) is a schematic diagram of the transmission line near the tower. [Figure 3] FIG. 3 is a schematic diagram of the system according to this embodiment. [Figure 4] FIG. 4(a) is a graph showing the frequency characteristics at a certain point of the OPGW, and FIG. 4(b) is a schematic diagram of the frequency characteristics of the OPGW 5 acquired by the DAS used as the abnormality detection device. [Figure 5] FIG. 5(a) is a diagram showing the relationship between the vibration intensity and frequency of the OPGW5 at multiple measurement points on the N-th span, and FIG. 5(b) is a diagram showing the relationship between the vibration intensity and frequency at multiple measurement points on the N+1-th span. [Figure 6] FIG. 6(a) is a schematic diagram showing the overall configuration of the abnormality detection device, and FIG. 6(b) is a block diagram for explaining the hardware configuration of the arithmetic device. [Figure 7] FIG. 7 is a diagram for explaining the principle of vibration measurement. [Figure 8] FIG. 8 is a schematic diagram of vibration information generated by the generation unit. [Figure 9] FIG. 9(a) is a schematic diagram of another example of vibration information generated by the generating unit, and FIG. 9(b) is a schematic diagram of vibration information for span N+1 generated by the generating unit. [Figure 10] FIG. 10 is a schematic diagram of vibration information generated by the generation unit. [Figure 11] FIG. 11(a) is a schematic diagram of another example of vibration information generated by the generating unit, and FIG. 11(b) is a schematic diagram of vibration information when there is an abnormality in the power transmission facility. [Figure 12] FIG. 12 is a flowchart of the abnormality identification method according to this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Prior to describing the present embodiment, the matters considered by the inventors of the present invention will be described.

[0011] 1 is a schematic diagram of a power transmission facility 1. This power transmission facility 1 includes a steel tower 2, a power transmission line 3, a vibration sensor 4, an OPGW (Optical fiber composite overhead Ground Wire) 5, and a substation 6.

[0012] The power transmission line 3 is an electric wire that transmits AC current transformed in a substation 6. The OPGW 5 is a wire with an optical fiber housed in the center of an overhead ground wire. The steel tower 2 is a tower that supports the power transmission line 3 and the OPGW 5. Below, the space between multiple steel towers 2 is called a span. The vibration sensor 4 is a sensor that measures the natural vibration of the OPGW 5.

[0013] Fig. 2(a) is a cross-sectional view of the OPGW 5 taken along a cross section perpendicular to the extension direction of the OPGW 5. As shown in Fig. 2(a), the OPGW 5 is supported on the tower 2 by cleats 2a.

[0014] Fig. 2(b) is a schematic diagram of the power transmission line 3 near the steel tower 2. As shown in Fig. 2(b), the power transmission line 3 is supported on the steel tower 2 via a clamp 2b and an insulator 2c.

[0015] The natural frequency of the OPGW 5 changes depending on the tension of the OPGW 5. Therefore, if the bolts, cleats 2a, clamps 2b, etc. of the tower 2 loosen, the tension of the OPGW 5 changes, and the natural frequency of the OPGW 5 also changes. By detecting this change in the natural frequency with the vibration sensor 4 (see Figure 1), it can be determined whether or not there is an abnormality in the power transmission equipment 1.

[0016] However, in order to capture changes in the natural vibration with high accuracy, it is necessary to install vibration sensors 4 at intervals of 10 m on an OPGW 5 having a length of, for example, about 100 km, and therefore an extremely large number of vibration sensors 4 are required.

[0017] Moreover, since it is difficult to externally supply power to the vibration sensor 4, an extra component such as a power generation system or battery for power supply is required. Furthermore, the power transmission facility 1 is located in a mountainous area outside the service area of ​​the public line network, so a wireless communication function is also required for data collection.

[0018] These vibration sensors, power generation systems, communication devices, and other electronic devices are used outdoors, so they must be highly reliable and maintenance-free. Power transmission equipment has a service life of several decades, which is longer than that of electronic devices, resulting in high maintenance costs.

[0019] (Present embodiment) Fig. 3 is a schematic diagram of the system according to this embodiment. In Fig. 3, the same elements as in Fig. 1 are given the same reference numerals, and their description will be omitted below.

[0020] This system is a system for detecting an abnormality in a power transmission facility 1, and includes an abnormality detection device 100.

[0021] In this example, a distributed acoustic sensing (DAS) optical fiber vibration measurement system is used as the abnormality detection device 100. The DAS is a system that calculates vibrations caused by the expansion and contraction of the optical fiber based on the time it takes for the backscattered Rayleigh light to return after pulsed light is incident on the optical fiber of the OPGW 5, as well as the phase difference and intensity of the backscattered Rayleigh light.

[0022] 4(a) is a graph showing the frequency characteristics at a certain point of the OPGW 5. The horizontal axis of the graph represents the frequency of the OPGW 5, and the vertical axis represents the vibration intensity in arbitrary units.

[0023] As shown in Figure 4(a), the fundamental wave and its overtones appear as natural frequencies in the frequency characteristics of the OPGW 5. On the other hand, the DAS can obtain the frequency characteristics at all points on the OPGW 5, rather than just the frequency characteristics at one point on the OPGW 5.

[0024] FIG. 4(b) is a schematic diagram of the frequency characteristics of the OPGW 5 acquired by the DAS used as the anomaly detection device 100. In this diagram, the horizontal axis represents the length of the OPGW 5, and the vertical axis represents the frequency. In this frequency characteristic, the intensity of vibration is represented by shades of gray, with the lighter the color, the greater the intensity of vibration. Additionally, multiple substantially white linear regions extending horizontally represent the natural frequencies of the OPGW 5 stretched across each span. As shown in FIG. 4(b), it can be seen that the natural frequencies differ depending on the span.

[0025] The natural frequency ν of the OPGW 5 can be expressed by the following equation (1).

[0026]

number

[0027] Fig. 5(a) is a diagram showing the relationship between vibration intensity and frequency of the OPGW 5 at multiple measurement points on the Nth span, and Fig. 5(b) is a diagram showing the relationship between vibration intensity and frequency at multiple measurement points on the N+1th span.

[0028] As shown in Figures 5(a) and 5(b), the vibration intensity varies depending on the measurement point even within the same span.

[0029] Fig. 6(a) is a schematic diagram showing the overall configuration of the abnormality detection device 100. As illustrated in Fig. 6(a), the abnormality detection device 100 includes a measuring device 10, a computing device 20, etc. The measuring device 10 includes a laser 11, an optical circulator 12, a detector 13, etc. The computing device 20 includes an acquiring unit 22, a generating unit 23, a detecting unit 24, and a storage unit 25.

[0030] FIG. 6(b) is a block diagram illustrating the hardware configuration of the arithmetic device 20. As illustrated in FIG. 6(b), the arithmetic device 20 includes a central processing unit (CPU) 101, a random access memory (RAM) 102, a storage device 103, an interface 104, and the like. These devices are connected via a bus or the like. The CPU 101 is a central processing unit. The CPU 101 includes one or more cores. The RAM 102 is a volatile memory that temporarily stores programs executed by the CPU 101, data processed by the CPU 101, and the like. The storage device 103 is a non-volatile storage device. The storage device 103 may be, for example, a read-only memory (ROM), a solid-state drive (SSD) such as a flash memory, or a hard disk driven by a hard disk drive. When the CPU 101 executes an anomaly detection program stored in the storage device 103, the arithmetic device 20 is provided with an acquisition unit 22, a generation unit 23, a detection unit 24, and a storage unit 25. Each part of the arithmetic device 20 may be hardware such as a dedicated circuit.

[0031] The laser 11 is a light source such as a semiconductor laser, and emits laser light within a predetermined wavelength range to the optical fiber 30 of the OPGW 5. In this embodiment, the laser 11 emits optical pulses (laser pulses) at predetermined time intervals. The optical circulator 12 guides the optical pulses emitted by the laser 11 to the optical fiber 30 whose vibration is to be measured, and guides the backscattered light returning from the optical fiber 30 to the detector 13.

[0032] The optical pulse incident on the optical fiber 30 propagates through the optical fiber 30. The optical pulse propagates through the optical fiber 30 while gradually attenuating, generating forward scattered light traveling in the propagation direction and backscattered light (return light) traveling in the return direction. The backscattered light re-enters the optical circulator 12. The backscattered light incident on the optical circulator 12 is output to the detector 13. The detector 13 is, for example, a receiver for obtaining the phase difference with the locally emitted light.

[0033] FIG. 7 is a diagram for explaining the principle of vibration measurement. As illustrated in FIG. 7, a laser pulse is incident as incident light into the optical fiber 30. Among the backscattered light, coherent returning light, which is Rayleigh scattered light having the same frequency as the incident light, returns to the optical circulator 12 with its phase shifted due to vibration. The acquisition unit 22 acquires this coherent returning light. Based on the detection result of the detector 13, the generation unit 23 generates time-series data of the phase difference caused by expansion and contraction of the optical fiber 30 at each sampling position (hereinafter referred to as time-series phase data). The phase difference caused by expansion and contraction of the optical fiber 30 is, for example, a phase difference caused by a change over time, a phase difference caused by a change in location, or the phase difference between the phase of the incident light and the backscattered light.

[0034] The memory unit 25 stores the time-series phase data at each sampling position created by the acquisition unit 22. The sampling positions are points or sections defined at predetermined intervals in the extension direction of the optical fiber 30. For example, the sampling positions are points defined every 1.25 m in the extension direction of the optical fiber 30, or sections defined every 1.25 m and having a length of 1.25 m or less. Each phase difference in the time-series phase data may be obtained from the phase difference detected at each point, or may be obtained from the sum or average of the phase differences detected in each section. Note that if the next laser pulse is generated before the return light scattered at the end of the optical fiber 30 returns, the return light will be mixed in and accurate measurement will not be possible; therefore, the minimum period of the laser pulse is determined by the length of the optical fiber to be measured.

[0035] Vibration measurement can be performed using the time-series phase data at each sampling position. For example, from the time-series phase data, vibration data can be calculated that indicates the displacement per unit time of each sampling position on the optical fiber 30. This method is known as self-interference. The physical quantity measured differs depending on whether the light to be interfered is localized light or backscattered light. The former is a phase difference corresponding to strain, while the latter is a phase difference relative to the strain rate obtained by taking the time difference. By acquiring the phase difference at the laser pulse period, it can be converted into time-series strain vibration data corresponding to the optical fiber position. Based on this time-series strain vibration data, the generation unit 23 generates vibration information for the frequency domain including the natural frequency of the OPGW 5 as follows.

[0036] Fig. 8 is a schematic diagram of vibration information generated by the generating unit 23. In the example of Fig. 8, the generating unit 23 generates, as vibration information, the time fluctuation of the intensity of the natural frequency of the OPGW 5 for each of a plurality of spans.

[0037] Anomalies may occur in the power transmission equipment 1 due to loosening of bolts on the steel tower 2, falling off of clamp 2b, deformation of the concrete foundation of the steel tower 2, etc. When any of these anomalies occurs, the vibration intensity of the natural frequency of the OPGW 5 also changes. Therefore, the detection unit 24 detects an abnormality in the power transmission equipment 1 based on vibration information such as that shown in FIG.

[0038] As an example, the detection unit 24 identifies a span among multiple spans whose time variation trend in the intensity of the natural frequency differs from that of the other spans, and identifies the identified span as having an abnormality. In the example of Fig. 8, the vibration intensity of span N increases significantly at time t, while the vibration intensity of the other spans at the same time t tends to decrease. The detection unit 24 identifies span N as having an abnormality when the time variation in the vibration intensity of span N at a certain time increases while the time variation in the vibration intensity of all other spans at the same time decreases. Alternatively, the detection unit 24 may identify span N as having an abnormality when the time variation in the vibration intensity of span N at a certain time decreases while the time variation in the vibration intensity of all other spans at the same time increases.

[0039] Furthermore, if the difference between the absolute value of the time change in vibration intensity of span N at a certain time and the absolute value of the time change in vibration intensity of span i at the same time exceeds a threshold value for all i other than N, the detection unit 24 may determine that there is an abnormality in span N.

[0040] In any of the above cases, the vibration intensity may be the maximum value, average value, or median value within the span, or may be the vibration intensity at a representative point within the span.

[0041] 9(a) is a schematic diagram of another example of vibration information generated by the generation unit 23. In this example, the generation unit 23 generates, as vibration information, the time fluctuation of the intensity of the natural frequency of the OPGW 5 at multiple points included in a certain span. In addition, the generation unit 23 generates such vibration information for each of multiple spans.

[0042] The example in Fig. 9(a) illustrates the time variation of the intensity of the natural frequency at multiple points in span N. Note that span N in this example is an example of the first span.

[0043] In this case, the detection unit 24 determines that there is an abnormality in span N if the multiple points included in span N include a point whose time variation trend differs from the time variation trend of the other points included in span N. In this example, the time variation at "point 2" at time t rises sharply, whereas the time variation at the other points at the same time t is gradual. Therefore, the time variation trend at "point 2" differs from the time variation at the other points. Therefore, the detection unit 24 determines that there is an abnormality in span N.

[0044] Fig. 9(b) is a schematic diagram of vibration information for span N+1 generated by the generation unit 23. In the example of Fig. 9(b), the trends of time change at all points included in span N+1 are similar. Therefore, the detection unit 24 determines that there is no abnormality in span N+1 and that it is normal.

[0045] Fig. 10 is a schematic diagram of vibration information generated by the generation unit 23. In the example of Fig. 10, the generation unit 23 generates, as vibration information, the time fluctuation of the natural frequency of the OPGW 5 for each of a plurality of spans.

[0046] The detection unit 24 then identifies a span among the multiple spans whose time variation trend of the natural frequency differs from that of the other spans, and determines that the identified span has an abnormality. In the example of Figure 10, the vibration intensity of span N increases significantly at the time indicated by the arrow, while the vibration intensity of the other spans at the same time tends to decrease. Therefore, the detection unit 24 determines that span N has an abnormality. The vibration frequency at this time may be the maximum, average, or median value within the span, or the vibration frequency at a representative point within the span.

[0047] Fig. 11(a) is a schematic diagram of another example of vibration information generated by the generation unit 23. In this example, the generation unit 23 generates, as vibration information, information indicating the relationship between the length of the OPGW 5 and its natural frequency. Note that Fig. 11(a) is vibration information when the power transmission facility 1 is normal.

[0048] On the other hand, Fig. 11(b) is a schematic diagram of vibration information when there is an abnormality in the power transmission equipment 1. In this case, a natural frequency that does not appear in normal times (Fig. 11(a)) appears in the vibration information. Therefore, the detection unit 24 determines that there is an abnormality in the power transmission equipment 1 when a natural frequency that does not appear when the power transmission equipment 1 is normal appears in the vibration information.

[0049] Next, the abnormality identification method according to this embodiment will be described with reference to the flowchart of FIG.

[0050] First, the acquisition unit 22 acquires location information indicating the location of each of the multiple steel towers 2 (step S11). As an example, the acquisition unit 22 acquires the location information from a storage device external to the anomaly detection device 100. Note that the location information may be stored in advance in the storage unit 25, and the acquisition unit 22 may acquire the location information from the storage unit 25.

[0051] Next, the acquisition unit 22 acquires the coherent light, which is Rayleigh scattered light, emitted from the optical fiber 30 (step S12).

[0052] Next, the detection unit 24 estimates the positions of each of the multiple steel towers 2 and spans (step S13). For example, the detection unit 24 estimates that the steel tower 2 is located at a position where the linear natural frequency is discontinuous, as shown in FIG. 4(b). Furthermore, the detection unit 24 estimates that the intervals between the positions of the steel towers 2 identified in this manner are spans. Then, the detection unit 24 assigns identifiers 1, 2, ..., N, N+1, ... to each of the steel towers 2 based on the position information acquired in step S11. For example, the length of the optical fiber 30 and the position of each steel tower 2 are stored in the position information, and the detection unit 24 assigns an identifier to each steel tower 2 by comparing this with the length of the optical fiber 30 where the natural frequency is discontinuous in FIG. 4(b). Thereafter, the detection unit 24 estimates the position of each span based on the identified position of each steel tower 2. For example, the detection unit 24 estimates that the optical fiber 30 located between the Nth steel tower and the N+1th steel tower is the span N.

[0053] Next, the generation unit 23 acquires any one of the vibration information shown in Fig. 8 to Fig. 11 based on the acquired coherent light (step S14). The span used in the vibration information is the one estimated in step S13.

[0054] Thereafter, the detection unit 24 detects an abnormality in the power transmission facility 1 based on the vibration information (step S15). For example, the detection unit 24 detects an abnormality using any of the methods described with reference to FIGS.

[0055] According to the present embodiment described above, the detection unit 24 detects an abnormality by acquiring scattered light emitted from the optical fiber 30 and using vibration information generated based on the scattered light. Therefore, an abnormality in the power transmission facility 1 can be detected without providing a large number of vibration sensors 4 in the power transmission facility 1 as shown in FIG. 1 , and an abnormality in the power transmission facility 1 can be easily detected. [Explanation of symbols]

[0056] 1...power transmission equipment, 2...steel tower, 2a...cleat, 2b...clamp, 2c...insulator, 3...power transmission line, 4...vibration sensor, 6...substation, 10...measuring device, 11...laser, 12...optical circulator, 13...detector, 20...computing device, 22...acquisition unit, 23...generation unit, 24...detection unit, 25...memory unit, 30...optical fiber, 100...abnormality detection device, 103...memory device, 104...interface.

Claims

1. The backscattered Rayleigh light is acquired from an optical fiber composite overhead ground wire installed in a power transmission facility having multiple steel towers. generating vibration information indicating a time variation in intensity of a natural frequency of the optical fiber composite overhead ground wire for each of a plurality of spans of the plurality of steel towers based on the backward Rayleigh scattered light; identifying a span among the plurality of spans whose tendency of the time fluctuation is different from the tendency of the time fluctuation of other spans, and determining that an abnormality exists in the identified span, thereby detecting an abnormality in the power transmission facility. An anomaly detection program that causes a computer to execute a process.

2. A power transmission system comprising: a power transmission system including a plurality of steel towers; a power transmission system including a power transmission system; a power transmission system including a power transmission system; generating vibration information indicating a time variation in intensity of a natural frequency of the optical fiber composite overhead ground wire at a plurality of points included in each of a plurality of spans of the plurality of steel towers based on the backward Rayleigh scattered light; when the plurality of points included in a first span among the plurality of spans includes a point whose time variation trend is different from the time variation trend of other points included in the first span, the abnormality of the power transmission facility is detected by identifying that the first span has an abnormality; An anomaly detection program that causes a computer to execute a process.

3. A power transmission system comprising: a power transmission system including a plurality of steel towers; a power transmission system including a power transmission system; a power transmission system including a power transmission system; generating vibration information indicating a time variation in frequency of the natural frequency of the optical fiber composite overhead ground wire for each of the plurality of spans of the plurality of steel towers based on the backward Rayleigh scattered light; identifying a span among the plurality of spans whose tendency of the time fluctuation is different from the tendency of the time fluctuation of other spans, and determining that an abnormality exists in the identified span, thereby detecting an abnormality in the power transmission facility. An anomaly detection program that causes a computer to execute a process.

4. An acquisition unit that acquires backward Rayleigh scattered light from an optical fiber composite overhead ground wire provided in a power transmission facility having a plurality of steel towers; a generator that generates vibration information indicating a time variation in intensity of a natural frequency of the optical fiber composite overhead ground wire for each of a plurality of spans of the plurality of steel towers based on the backward Rayleigh scattered light; a detection unit that identifies a span among the plurality of spans, the span having a tendency of the time variation different from the time variation of other spans, and detects an abnormality in the power transmission equipment by identifying the identified span as having an abnormality; An abnormality detection device comprising:

5. An acquisition unit that acquires backward Rayleigh scattered light from an optical fiber composite overhead ground wire provided in a power transmission facility having a plurality of steel towers; a generator that generates, based on the backward Rayleigh scattered light, vibration information indicating time fluctuations in intensity of natural frequencies of the optical fiber composite overhead ground wire at a plurality of points included in each of a plurality of spans of the plurality of steel towers; a detection unit that detects an abnormality in the power transmission facility by identifying an abnormality in a first span when the plurality of points included in a first span among the plurality of spans includes a point whose time variation trend differs from the time variation trend of other points included in the first span; An abnormality detection device comprising:

6. An acquisition unit that acquires backward Rayleigh scattered light from an optical fiber composite overhead ground wire provided in a power transmission facility having a plurality of steel towers; a generator that generates vibration information indicating a time variation in frequency of the natural frequency of the optical fiber composite overhead ground wire for each of the plurality of spans of the plurality of steel towers based on the backward Rayleigh scattered light; a detection unit that identifies a span among the plurality of spans, the span having a tendency of the time variation different from the time variation of other spans, and detects an abnormality in the power transmission equipment by identifying the identified span as having an abnormality; An abnormality detection device comprising:

7. The computer The backscattered Rayleigh light is acquired from an optical fiber composite overhead ground wire installed in a power transmission facility having multiple steel towers. generating vibration information indicating a time variation in frequency of the natural frequency of the optical fiber composite overhead ground wire for each of the plurality of spans of the plurality of steel towers based on the backward Rayleigh scattered light; identifying a span among the plurality of spans whose tendency of the time fluctuation is different from the tendency of the time fluctuation of other spans, and determining that an abnormality exists in the identified span, thereby detecting an abnormality in the power transmission facility.

2. An anomaly detection method comprising:

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