JP7474937B1 - Lightning monitoring system and lightning monitoring method - Google Patents

Abstract

The lightning monitoring system acquires the time change in vibration intensity for each frequency of an optical fiber at measurement points set along an optical fiber installed along a power transmission line using a distributed acoustic sensing (DAS), acquires the location and time of the lightning strike from an LLS (lightning location location system), extracts as lightning detection spans those spans having measurement points where the time change in vibration intensity for each frequency during at least any specified period before and after the time of the strike includes the time change in vibration intensity caused by a lightning strike, identifies among the lightning detection spans those spans that are within a specified distance from the location of the strike as neighboring spans, and generates information indicating that a direct lightning strike has occurred on a neighboring span if the time change in vibration intensity for each frequency during at least any specified period before and after the time of the strike includes the time change in vibration intensity caused by a direct lightning strike on the neighboring span.

Description

The present invention relates to a lightning monitoring system and a lightning monitoring method.

Patent Document 1 describes a fault detection and location system that locates the location of a fault that occurs in an overhead power transmission line having an OPGW (optical fiber composite overhead ground wire). When a fault detector installed on a steel tower supporting the overhead power transmission line detects an fault, the fault detection and location system applies mechanical shock or vibration to the OPGW using a shock/vibration application device, and detects changes in the state of the light propagating through the optical fiber. The fault detection and location system locates the position of the lightning strike by detecting changes over time in the polarization state of the light propagating through the optical fiber combined with the OPGW due to the lightning current.

Patent document 2 describes an anomaly detection device that generates vibration information for a frequency range including the natural frequency of the OPGW using an optical fiber vibration measurement system (DAS: Distributed Acoustic Sensing) that calculates vibrations caused by the expansion and contraction of the optical fiber based on the time from when pulsed light is incident on the optical fiber of the OPGW until the backward Rayleigh scattered light returns, and the phase difference and intensity of the backward Rayleigh scattered light, and detects abnormalities in the power transmission equipment based on the generated vibration information.

Japanese Patent Application Laid-Open No. 10-177055 JP 2023-50257 A

"Investigation into the feasibility of measuring lightning impact on CFRP composite materials using optical fiber sensors", Yoshiaki Akimatsu, Kazuo Kageyama, Hideaki Murayama, Kanazawa Institute of Technology, Materials Systems Research Institute, [online], Internet <URL: https://www.jstage.jst.go.jp/article/zairyosystem/34/0/34_51/_article/-char/ja/>, retrieved on October 20, 2023

Direct lightning strikes on power transmission and transformation equipment such as power lines, transmission towers, and substations can lead directly to accidents and breakdowns. Therefore, when maintaining power transmission equipment, it is necessary to monitor lightning strikes on power transmission equipment in real time, quickly understand the impact of a direct lightning strike, and, if necessary, take immediate action to restore power.

The fault detection and location locating system described in Patent Document 1 locates the location of a lightning strike by detecting the time change in the polarization state of the light propagating through the optical fiber of the OPGW due to the lightning current. However, in order to implement this system, it is necessary to install fault detection devices and shock/vibration application devices on each tower, which is very costly.

Patent Document 2 describes the detection of abnormalities in power transmission equipment based on vibration information generated using an optical fiber vibration measurement system (DAS). However, the document does not describe the presence or absence of a direct lightning strike on the power transmission equipment or a mechanism for detecting the effects of a direct lightning strike.

The Lightning Location System (LLS) is a system for acquiring information such as the date and time of lightning strikes, their location (latitude and longitude), the magnitude of the lightning current, and the amount of charge in real time. However, the accuracy of the LLS in locating the lightning strike is only a few hundred meters, so it is not always possible to pinpoint the location of the lightning strike with high accuracy.

The present invention has been made in consideration of this background, and aims to provide a lightning monitoring system and a lightning monitoring method that are capable of quickly and appropriately providing information regarding the effects of lightning strikes on power transmission equipment.

One of the means for solving the above problem is a lightning monitoring system comprising an optical analysis unit and an information processing device, which acquires the time change of vibration intensity for each frequency of an optical fiber at measurement points set along an optical fiber attached along a power transmission line using a Distributed Acoustic Sensing (DAS), acquires information indicating the location of the lightning strike and the time of the strike from a communicatively connected Lightning Location System (LLS), extracts as a lightning detection span a span having the measurement point where the time change of vibration intensity for each frequency during at least any specified period before or after the time of the strike includes the aspect of the time change of vibration intensity caused by the lightning strike, identifies, of the extracted lightning detection spans, spans that are within a specified distance from the location of the strike as nearby spans, and generates information indicating the identified nearby spans.

Other problems and solutions disclosed in this application will be made clear in the description of the embodiment and the drawings.

According to the present invention, it is possible to provide information regarding the impact of lightning strikes on power transmission equipment promptly and appropriately.

FIG. 1 is a diagram showing a schematic configuration of a lightning monitoring system. FIG. 2 is a diagram illustrating a mechanism for measuring a vibration state by a DAS. FIG. 2 is a diagram illustrating an example of a positional relationship between a lightning strike point and power transmission equipment. 1 is a diagram showing an example of a change in vibration intensity over time for each frequency of an optical fiber. FIG. 1 is a diagram showing the main configuration of a lightning monitoring device. FIG. 2 is a diagram showing main functions of the lightning monitoring device. 13 is a flowchart illustrating a lightning strike monitoring process. 13 is an example of a lightning strike information display screen.

The present invention will be described below with reference to the accompanying drawings according to one embodiment of the present invention. At least the following points will become clear from the description of this specification and the accompanying drawings. In the following description, the letter "S" before a reference symbol indicates a processing step.

Figure 1 shows a schematic configuration of a lightning monitoring system 1 described as one embodiment of the present invention. The lightning monitoring system 1 includes a lightning monitoring device 100 provided in a substation 6 or the like, and a lightning location system (hereinafter referred to as "LLS300").

The lightning monitoring device 100 is configured using an information processing device (computer). The lightning monitoring device 100 is communicatively connected to the LLS 300 via a communication network (not shown). The communication network may be, for example, a LAN (Local Area Network), a WAN (Wide Area Network), the Internet, a PLC (Power Line Communication), a public communication network, a dedicated line, etc.

The lightning monitoring device 100 uses the optical fiber 4a of the OPGW4 (OPTICAL fiber composite overhead ground wire) installed on the power transmission line 3 as a vibration detection sensor, and acquires the vibration state at each measurement point by a technique (distributed multipoint vibration measurement method (hereinafter referred to as "DAS" (Distributed Acoustic Sensing)) that measures the vibration state (vibration intensity, vibration frequency) based on the expansion and contraction of the optical fiber 4a at each of multiple measurement positions (hereinafter referred to as "measurement points") set along the optical fiber 4a. In DAS, the vibration state at each measurement point is acquired, for example, using the principle of C-OTDR (Coherent detection Optical Time Domain Reflectometer).

Figure 2 is a diagram explaining the mechanism by which the lightning monitoring device 100 measures the vibration state of each measurement point using the DAS. As shown in the figure, the lightning monitoring device 100 inputs a light pulse (laser pulse, hereinafter also referred to as "incident light") from the end face of the optical fiber 4a, and measures the change speed (≒ stretch frequency) of the phase difference of the backscattered light of the light pulse at each measurement point. The phase difference is estimated from the intensity change due to the interference between the backscattered lights. Then, the lightning monitoring device 100 determines the vibration frequency (for example, vibration frequency in the range of up to 10 kHz) of the longitudinal wave and transverse wave of the optical fiber 4a at each measurement point based on the measured change speed. The lightning monitoring device 100 also determines the vibration intensity (spectral intensity, vibration amplitude) at each measurement point based on the phase difference for each vibration frequency. The lightning monitoring device 100 also determines the position of each measurement point (distance from the end face) based on the elapsed time from the time when the incident light is input to the end face to the time when the return light is received.

The above measurement points are set, for example, at predetermined intervals d (m) along the optical fiber that are shorter than the span of the transmission tower 2 (0 (m), d (m), ..., N (m), N + d (m), N + 2 d (m)). For example, as shown in Figure 1, if the predetermined interval d is 5 (m) and measurement points are set over a maximum range of 70 (km) of the transmission line 3, approximately 14,000 measurement points are set along the optical fiber. The lightning monitoring device 100 acquires information about the shock and vibration caused by lightning at each measurement point based on the vibration state of each measurement point.

Returning to FIG. 1, LLS300 acquires information (hereinafter referred to as "lightning information") relating to lightning strikes that occur in areas where power transmission facilities (transmission tower 2, transmission line 3, substation 6, etc.) are located, and provides (transmits) the acquired lightning strike information to lightning monitoring device 100 quickly (in real time). LLS300 captures the electromagnetic field generated by lightning strikes and acquires lightning strike information, for example, by the time difference of arrival method. Lightning strike information includes information indicating the date and time of the lightning strike and its location (latitude, longitude). The location accuracy (location error) of the lightning strike location of LLS300 is on the order of several hundred meters.

Figure 3A shows an example of the positional relationship between the point where a lightning strike occurs and power transmission equipment when lightning strikes an area around the power transmission equipment. The figure shows that lightning struck at point a near a power transmission tower 2 whose identifier (hereafter referred to as "tower ID") is "19" to "23." When a lightning strike occurs, vibrations (sounds) caused by the lightning strike (thunderclaps) occur in the OPGW 4 in the span of the power transmission tower 2 located around the point where the lightning strike occurred.

Figure 3B is an example of the change over time in vibration intensity for each frequency of optical fiber 4a measured at specific measurement points on each of the spans shown in Figure 3A, with span identifiers (hereafter referred to as "span IDs") of "20_21", "21_22", "22_23", and "23_24". In each graph, time flows from top to bottom on the page. The shades of color in the figure represent the vibration intensity (arbitrary units) for each frequency (the lighter the color, the greater the vibration intensity).

The vibrations (sounds) that accompany a lightning strike begin a little before the strike and continue for a while after it occurs. Therefore, in each graph shown in the figure, vibrations caused by lightning strikes are observed for at least a certain period (often about a few minutes) before or after the time when lightning struck point a.

As shown in the figure, strong vibration intensity (vibration intensity equal to or greater than a preset threshold) is observed at the same frequency (frequency centered around 8.25 Hz) during at least a specified period before or after the lightning strike in the graphs for adjacent spans with span IDs "21_22" and "22_23" located close to point a. It has been found that when thunder has a sound pressure equal to or greater than a specified level, vibrations in the same frequency band are observed not just across one span but across multiple spans. It can therefore be determined that these vibrations are caused by the same lightning strike.

On the other hand, it is known that when a span is directly struck by lightning, multiple strong vibrations (vibration intensity greater than or equal to a preset threshold) are observed across multiple frequency bands during at least a specific period before or after the lightning strike, but no such vibrations are observed in these graphs. Therefore, it can be determined that no direct lightning strikes occurred on these spans.

In addition, strong vibrations are observed across a wide frequency range (5 to 7.5 Hz) in the graph for span ID "23_24". However, no such vibrations are observed in the 8 to 9 Hz frequency band where strong vibrations are observed in the graphs for span IDs "21_22" and "22_23". Therefore, it can be determined that the strong vibrations observed in the graph for span ID "23_24" are due to a lightning strike different from the lightning strike that occurred at point a.

From the above perspective, the lightning monitoring device 100 provides information about lightning strikes that have occurred in the vicinity of a span and information about direct lightning strikes that have occurred on the span (the power transmission equipment of the span) based on the time-dependent changes in the vibration state of the optical fiber 4a at each frequency obtained at the measurement points of each span.

Figure 4A is a diagram showing the main configuration of the lightning monitoring device 100. As shown in the figure, the lightning monitoring device 100 comprises a processor 101, a main memory device 102 (memory), an auxiliary memory device 103 (external memory device), an input device 104, an output device 105, a communication device 106, and an optical analysis unit 107. These are communicatively connected via a bus, a communication cable, or the like. Note that the lightning monitoring device 100 may be realized in whole or in part using virtual information processing resources, such as a virtual server provided by a cloud system.

The processor 101 is configured using, for example, a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a GPU (Graphics Processing Unit), an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), an AI (Artificial Intelligence) chip, etc.

The main memory device 102 is a memory device used by the processor 101 when executing a program, and may be, for example, a ROM (Read Only Memory), a RAM (Random Access Memory), or a non-volatile memory (NVRAM (Non Volatile RAM)).

The auxiliary storage device 103 is a device that stores programs and data, and can be configured, for example, with an SSD (Solid State Drive), a hard disk drive, an optical storage device (CD (Compact Disc), DVD (Digital Versatile Disc), etc.). Programs and data can be read into the auxiliary storage device 103 from other information processing devices equipped with non-transient recording media or non-transient storage devices via a recording medium reading device or communication device 106. The programs and data stored (kept) in the auxiliary storage device 103 are read into the main storage device 102 at any time.

The input device 104 is an interface that accepts input of information from outside, such as a keyboard, a mouse, a touch panel, a voice input device, etc.

The output device 105 is an interface that outputs various information such as the progress of processing and the results of processing to the outside. The output device 105 is, for example, a display device (liquid crystal display, LCD (Liquid Crystal Display) etc.) that visualizes the various information described above, a device that converts the various information described above into audio (audio output device (speaker etc.)), or a device that converts the various information described above into text (printing device etc.). For example, the information processing device 10 may be configured to input and output information between it and other devices via the communication device 106.

The input device 104 and the output device 105 constitute a user interface that realizes interactive processing with the user (accepting information, providing information, etc.).

The communication device 106 is a device that realizes communication with other devices via a communication network (such as a LAN (Local Area Network), a WAN (Wide Area Network), the Internet, a public communication network, a dedicated line, etc.). The communication device 106 is a wired or wireless communication interface that realizes communication with other devices via a communication medium, such as a NIC (Network Interface Card), a wireless communication module, a USB module (USB: Universal Serial Bus), etc.

The optical analysis unit 107 is a device that measures the vibration state of the measurement point using a DAS, and includes a vibration measurement device using a C-OTDR and a signal processing circuit. The optical analysis unit 107 includes a CW (continuous wave) laser light source that generates an optical pulse (laser light) to be input to the end face of the optical fiber 4a, an optical pulse generator, an optical amplifier, optical equipment (optical detector, optical interferometer), a signal processing circuit (phase calculation circuit, etc.), etc. The optical analysis unit 107 and the optical fiber 4a are connected, for example, by optically connecting the output part of the laser light source of the optical analysis unit 107 to the connection port (socket) of the core wire of the OPGW installed in the substation. Therefore, the connection does not cause any impact on the power system, such as a power outage.

The lightning monitoring device 100 may be equipped with, for example, an operating system, a file system, a DBMS (DataBase Management System) (relational database, NoSQL, etc.), a KVS (Key-Value Store), etc.

The various functions of the lightning monitoring device 100 are realized by the processor 101 reading and executing a program stored in the main memory device 102, or by the hardware (FPGA, ASIC, AI chip, etc.) that constitutes the lightning monitoring device 100. The lightning monitoring device 100 stores various information (data), for example, as a database table or a file managed by a file system.

Figure 4B is a block diagram explaining the main functions of the lightning monitoring device 100. As shown in the figure, the lightning monitoring device 100 has the functions of a memory unit 110, a vibration state measurement unit 120, a lightning information acquisition unit 125, a lightning detection span extraction unit 130, a nearby span identification unit 132, a direct lightning hit presence/absence determination unit 135, an equipment abnormality presence/absence determination unit 140, a response information generation unit 145, and a lightning information presentation unit 150.

Of the above functions, the memory unit 110 stores the vibration state for each measurement point 111, lightning information 112, lightning detection span 113, nearby span 114, direct lightning strike determination result 115, equipment abnormality determination result 116, response information 117, and power transmission equipment information 118.

The vibration state measurement unit 120 uses the DAS to measure the time change (time series data) of the vibration state (vibration intensity, vibration frequency) at each measurement point on each span, and manages the measurement results as the vibration state for each measurement point 111. The vibration state for each measurement point 111 includes, for example, the information shown in each graph in Figure 3B.

The lightning information acquisition unit 125 receives lightning information from the LLS 300 and manages the received lightning information as lightning information 112. The lightning information 112 includes information indicating at least the location (latitude, longitude) of the lightning strike and the date and time of the lightning strike. The lightning information 112 includes, for example, the information displayed in FIG. 3A.

The lightning detection span extraction unit 130 extracts spans (hereinafter referred to as "lightning detection spans") that include a vibration state caused by a lightning strike based on the vibration state for each measurement point 111, and manages the span IDs of the extracted spans as lightning detection spans 113. For example, the lightning detection span extraction unit 130 extracts spans having measurement points that include a pattern of the time change in vibration intensity caused by a lightning strike in the time change in vibration intensity for each frequency in at least any predetermined period before and after the time of the lightning strike as lightning detection spans. The pattern of the time change in vibration intensity caused by the lightning strike is, for example, that vibrations of a magnitude equal to or greater than a preset threshold value are observed at the same frequency (same frequency range) for at least any predetermined period before and after the time of the lightning strike (a predetermined period taking into account the time it takes for the sound waves caused by the lightning strike to reach the power transmission equipment) for the measurement points of each of the adjacent spans.

The nearby span identification unit 132 determines whether or not there is a span (hereinafter referred to as a "neighboring span") that exists near the lightning strike location indicated by the lightning strike information 112 among the lightning strike detection spans, and if so, manages the span ID of the span as a nearby span 114. The nearby span identification unit 132 obtains information indicating the location of each span from, for example, the power transmission equipment information 118, and identifies spans that exist within a specified distance (e.g., 1.5 km) from the lightning strike location as nearby spans. The power transmission equipment information 118 includes information on the power transmission equipment associated with the tower ID and the span ID (such as the location of the power transmission tower 2, and information on the power transmission equipment installed in the power transmission tower 2 and its surroundings).

The direct lightning hit determination unit 135 determines whether or not a direct lightning hit has occurred on the power transmission equipment of the nearby span based on the vibration state of the nearby span, and if a direct lightning hit has occurred, manages information indicating this as the direct lightning hit determination result 115. For example, the direct lightning hit determination unit 135 determines that a direct lightning hit has occurred on a nearby span when the change in vibration intensity for each frequency during at least any predetermined period before or after the occurrence time of the measurement point on the nearby span includes a change in vibration intensity due to a direct lightning hit on the nearby span. The change in vibration intensity due to a direct lightning hit on the nearby span is, for example, observed across multiple frequency bands with a magnitude equal to or greater than a preset threshold during at least any predetermined period before or after the occurrence time of the lightning strike.

When the direct lightning hit determination unit 135 determines that the power transmission equipment in the nearby span has been hit by a direct lightning hit, the equipment abnormality determination unit 140 determines whether or not an abnormality (such as a broken wire or partial deformation) has occurred in the power transmission equipment, and manages the determination result in the equipment abnormality determination result 116. The equipment abnormality determination unit 140 determines whether or not an abnormality has occurred in the power transmission equipment in the nearby span by, for example, comparing the natural frequency of the optical fiber 4a grasped from the vibration intensity for each frequency after the time of the lightning strike at the measurement point in the nearby span with the natural frequency of the optical fiber 4a grasped from the vibration intensity for each frequency in the nearby span in normal times (before the occurrence of a direct lightning hit) that has been stored in advance. For example, the equipment abnormality determination unit 140 determines that an abnormality has occurred in the power transmission equipment in the nearby span when a natural frequency different from the natural frequency in normal times is observed a predetermined number or more.

The correspondence information generating unit 145 generates information indicating nearby spans that have been hit by direct lightning (span IDs of nearby spans) and information indicating the action that should be taken by the power transmission equipment manager (maintenance personnel, etc.) for the nearby spans (power transmission equipment for the nearby spans) (hereinafter referred to as "response information"), and manages the generated response information as response information 117. The response information generating unit 145 acquires information necessary for generating the response information from power transmission equipment information 118. The response information generating unit 145 manages the response information in the power transmission equipment information 118, for example, in association with span IDs, and generates the response information by comparing the span IDs of nearby spans that have been hit by direct lightning with the power transmission equipment information 118.

The lightning information presentation unit 150 presents the contents of the corresponding information 117 to the administrator (e.g., displays it on a display device). The lightning information presentation unit 150, for example, generates a screen (e.g., the lightning information presentation screen 600 described later) that describes the contents of the corresponding information 117 and presents it to the administrator.

Figure 5 is a flowchart explaining the processing performed by the lightning monitoring device 100 (hereinafter referred to as "lightning monitoring processing S500"). Below, the lightning monitoring processing S500 will be explained with reference to the same figure.

In the following explanation, it is assumed that the LLS300 generates lightning information immediately when a lightning strike occurs and transmits the generated lightning information to the lightning monitoring device 100 (it may also be possible for the lightning monitoring device 100 to access the LLS300, and for the lightning monitoring device 100 to read (acquire, receive) the lightning information from the LLS300). In addition, it is assumed that the vibration state measurement unit 120 of the lightning monitoring device 100 measures the time change in the vibration state (vibration intensity, vibration frequency) of each measurement point on each span in real time using the DAS, and manages the latest vibration state of each measurement point as the vibration state for each measurement point 111.

As shown in the figure, the lightning information acquisition unit 125 waits in real time to receive lightning information from the LLS 300 (S511: No). When the lightning information acquisition unit 125 receives lightning information from the LLS 300 (S511: Yes), it manages the received lightning information as lightning information 112.

In S512, the lightning detection span extraction unit 130 extracts a lightning detection span based on the vibration state for each measurement point 111, and manages information indicating the extracted span as the lightning detection span 113.

In S513, the nearby span identification unit 132 determines whether or not a nearby span exists for the location of the lightning strike indicated by the lightning strike information 112 received in S511. If it is determined that a nearby span exists (S513: Yes), the nearby span identification unit 132 manages the information indicating the nearby span as the nearby span 114, and then the process proceeds to S514. On the other hand, if the nearby span identification unit 132 determines that a nearby span does not exist (S513: No), the process returns to S511.

In S514, the direct lightning hit determination unit 135 determines whether or not a direct lightning hit has occurred on the nearby span (the transmission equipment) based on the vibration state of the nearby span identified in S513 (the vibration state obtained from the vibration state per measurement point 111 for the identified nearby span). If the direct lightning hit determination unit 135 determines that a direct lightning hit has occurred on the nearby span (S514: Yes), processing proceeds to S515. On the other hand, if the direct lightning hit determination unit 135 determines that a direct lightning hit has not occurred on the nearby span (S514: No), processing returns to S511.

In S515, the equipment abnormality determination unit 140 determines whether or not an abnormality has occurred in the power transmission equipment in the nearby span identified in S513. If the equipment abnormality determination unit 140 determines that an abnormality has occurred in the power transmission equipment in the nearby span identified in S513 (S515: Yes), information indicating the result of the determination is managed in the equipment abnormality determination result 116, and then processing proceeds to S516. On the other hand, if the equipment abnormality determination unit 140 determines that no abnormality has occurred in the power transmission equipment in the nearby span identified in S513 (S515: No), processing proceeds to S517.

In S516, the correspondence information generation unit 145 generates correspondence information for the nearby span in which it has been determined that an abnormality has occurred, and manages the generated correspondence information as correspondence information 117.

In S517, the lightning strike information presentation unit 150 presents to the administrator the contents of the lightning strike information 112, information (span ID, etc.) regarding the nearby span determined to have been a direct lightning strike in S514, the contents of the corresponding information 117, etc.

Figure 6 is an example of a screen (hereinafter referred to as the "lightning strike information presentation screen 600") that the lightning strike information presentation unit 150 presents to the administrator.

As shown in the figure, the exemplary lightning strike information presentation screen 600 has a display field 611 for lightning strike information, a display field 612 for direct lightning strike information, and a display field 613 for corresponding information.

Of these, the lightning information display field 611 displays the contents of the lightning information acquired (received) by the lightning information acquisition unit 125 from the LLS 300 in S511 of Figure 5, for example, in the manner shown in Figure 3A.

The direct lightning hit information display field 612 displays information (span ID) indicating nearby spans that the direct lightning hit determination unit 135 determined to have been hit by direct lightning in S514 of Fig. 5. By referring to the contents of the direct lightning hit information display field 612, the administrator can easily identify nearby spans that may be affected by lightning.

Response information is displayed in the response information display field 613. By referring to the contents of the response information display field 613, the manager can quickly confirm the response that should be taken for the nearby span that was directly struck by lightning, and can take the necessary response efficiently.

As described above, the lightning monitoring system 1 of this embodiment can quickly provide the manager with information indicating the impact of a direct lightning strike on the power transmission equipment and the response to be taken for power transmission equipment in a nearby span that is determined to have been hit by direct lightning, based on the lightning strike information obtained from the LLS 300 and the information obtained using the DAS. The information provided by the lightning monitoring system 1 allows the manager to quickly and appropriately grasp the impact of a lightning strike on the power transmission equipment, and efficiently perform patrols, inspections, and maintenance work on the power transmission equipment.

In addition, the lightning monitoring system 1 of this embodiment can be easily implemented by utilizing the mechanism of an optical fiber vibration measurement system (DAS) without installing any special equipment on the transmission tower 2, etc.

The above embodiment is intended to facilitate understanding of the present invention, and is not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit of the present invention, and equivalents thereof are also included in the present invention.

For example, the location of a lightning strike can be estimated from the difference in the time when vibrations caused by thunder were observed for each span, thereby improving the accuracy of estimating the location of a lightning strike.

For example, the lightning strike information presentation unit 150 may receive a span (span ID) specification from an administrator, and present to the administrator the contents of the vibration state for each measurement point 111 corresponding to the received span (for example, in the manner shown in Figure 3B).

For example, the extraction of lightning detection spans by the lightning detection span extraction unit 130 and the determination of whether or not a direct lightning strike has occurred on a power transmission facility in a nearby span by the direct lightning strike determination unit 135 may be performed using a machine learning model that has been trained to output a determination result of whether or not a direct lightning strike has occurred on the lightning detection span or the nearby span when feature quantities extracted by performing image recognition processing on the graph (image) shown in Figure 3B are input as explanatory variables.

For example, the lightning monitoring device 100 may acquire information regarding the lightning strike force from the vibration state acquired by the DAS, and present (for example, display on the lightning strike information presentation screen 600) the acquired information and information regarding the reliability of the information (consistency with the charge amount and current value acquired from the LLS 300) (for information on acquiring lightning strike force, see, for example, Non-Patent Document 1, "Investigation into the feasibility of measuring lightning impact on CFRP composite materials using optical fiber sensors", Akimatsu Yoshiaki, Kageyama Kazuo, Murayama Hideaki, Materials Systems Research Institute, Kanazawa Institute of Technology).

1 Lightning monitoring system 2 Power transmission tower 3 Power line 4 OPGW
4a Optical fiber 100 Lightning monitoring device 107 Optical analysis unit 110 Memory unit 111 Vibration state at each measurement point 112 Lightning information 113 Lightning detection span 114 Nearby span 115 Direct lightning presence/absence determination result 116 Equipment abnormality presence/absence determination result 117 Correspondence information 118 Power transmission equipment information 120 Vibration state measurement unit 125 Lightning information acquisition unit 130 Lightning detection span extraction unit 132 Nearby span identification unit 135 Direct lightning presence/absence determination unit 140 Equipment abnormality presence/absence determination unit 145 Correspondence information generation unit 150 Lightning information presentation unit S500 Lightning monitoring process 600 Lightning information presentation screen

Claims (11)

The optical analysis unit and the information processing device are included.
Obtaining a time change in vibration intensity for each frequency of an optical fiber at measurement points set along the optical fiber installed along the power transmission line by a distributed acoustic sensing (DAS);
Acquire information indicating the location of a lightning strike and the time of the lightning strike from a lightning location system (LLS) that is communicably connected;
extracting, as a lightning detection span, a span having the measurement point in which the time change of the vibration intensity for each frequency during at least any predetermined period before or after the occurrence time includes a mode of time change of the vibration intensity caused by the lightning strike;
Among the extracted lightning strike detection spans, a span that exists within a predetermined distance from the occurrence position is identified as a nearby span, and information indicating the identified nearby span is generated.
Lightning monitoring system. The lightning monitoring system according to claim 1,
extracting the lightning detection span based on the fact that vibrations of a magnitude equal to or greater than a preset threshold value are observed at the same frequency during at least any predetermined period before or after the occurrence time for each of the measurement points of a plurality of adjacent spans;
Lightning monitoring system. The lightning monitoring system according to claim 1,
generating information indicating that a direct lightning strike has occurred on the nearby span when a time change in vibration intensity for each frequency during at least any predetermined period before or after the occurrence time of the measurement point on the nearby span includes a time change in vibration intensity resulting from a direct lightning strike on the nearby span;
Lightning monitoring system. The lightning monitoring system according to claim 3,
The presence or absence of a direct lightning strike in the nearby span is determined based on the fact that a plurality of vibrations having a magnitude equal to or greater than a preset threshold value are observed across a plurality of frequency bands during at least a predetermined period before or after the occurrence of a lightning strike.
Lightning monitoring system. The lightning monitoring system according to claim 3,
determining whether or not an abnormality has occurred in the power transmission equipment in the neighboring span by comparing a natural frequency of the optical fiber grasped from the vibration intensity for each frequency after the occurrence time of the measurement point in the neighboring span with a natural frequency of the optical fiber grasped from the vibration intensity for each frequency in the neighboring span under normal conditions that has been stored in advance, and generating information indicating the result of the determination;
Lightning monitoring system. The lightning monitoring system according to claim 1,
outputting information indicating the nearby span via a user interface;
Lightning monitoring system. The lightning monitoring system according to claim 3,
outputting information indicating that a direct lightning strike has occurred in the nearby span via a user interface;
Lightning monitoring system. The lightning monitoring system according to claim 5,
when it is determined that an abnormality has occurred in the power transmission equipment in the nearby span, outputting information indicating that an abnormality has occurred via a user interface;
Lightning monitoring system. The lightning monitoring system according to claim 3,
Store information indicating the action to be taken in the event of a direct lightning strike for each span,
outputting, via a user interface, information indicating a response to be taken for the nearby span determined to have been hit by direct lightning;
Lightning monitoring system. In a lightning monitoring system including an optical analysis unit and an information processing device,
The information processing device,
acquiring, by a distributed acoustic sensing (DAS), a time change in vibration intensity for each frequency of an optical fiber at measurement points set along the optical fiber installed along the power transmission line;
acquiring information indicating a location of a lightning strike and a time of the lightning strike from a lightning location system (LLS) communicably connected;
extracting, as a lightning strike detection span, a span having the measurement point in which the time change of the vibration intensity for each frequency during at least any predetermined period before or after the occurrence time includes a time change of the vibration intensity caused by the lightning strike; and
a step of identifying, from among the extracted lightning detection spans, spans that are within a predetermined distance from the occurrence position as nearby spans, and generating information indicating the identified nearby spans. A lightning monitoring method according to claim 10, comprising:
A lightning monitoring method, further comprising the step of: generating information indicating that a direct lightning strike has occurred on the nearby span when the time change in vibration intensity for each frequency during at least any specified period before or after the time of occurrence of the measurement point on the nearby span includes a pattern of time change in vibration intensity caused by a direct lightning strike on the nearby span.

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