JP7615957B2 - Power transmission line monitoring system, power transmission line monitoring method, and power transmission line monitoring program - Google Patents

Description

This disclosure relates to a power transmission line monitoring system, a power transmission line monitoring method, and a power transmission line monitoring program.

Trees, buildings, etc. may be present on the ground surface in the area where the overhead power lines are located. The distance (separation) that the ground surface shape, including such objects, must be kept away from the overhead power lines is specified. The separation between the overhead power lines and the ground surface shape is sometimes measured, for example, using a laser measuring device mounted on a helicopter (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 6-313715

The shape of the ground surface may change over time, but the purpose of this disclosure is to provide a technology that can accurately measure the distance between an overhead power transmission line and the shape of the ground surface while reflecting the changes that occur in the shape of the ground surface, and that can reduce the time and costs required for measurement even in such a case.

According to one aspect of the present disclosure,
an initial value data acquisition unit that acquires three-dimensional data of a ground surface shape in an area where the overhead power transmission line is arranged, the data being measured using an aircraft, as initial value data;
a displacement amount data acquisition unit that acquires and analyzes observation data regarding the earth's surface shape periodically transmitted from a satellite, extracts a displacement amount of the earth's surface shape over time, and sets the displacement amount data;
An installation information storage unit that stores installation information of the overhead power transmission line;
a distance detection processing unit that calculates a distance between the overhead power transmission line and the ground surface shape using the initial value data, the displacement amount data, and the installation information;
A power transmission line monitoring system is provided, comprising:

According to another aspect of the present disclosure,
An initial value data acquisition step of acquiring three-dimensional data of the ground surface shape of the area where the overhead power transmission line is arranged, which is actually measured using an aircraft, as initial value data;
a displacement amount data acquisition step of acquiring and analyzing observation data regarding the earth's surface shape periodically transmitted from a satellite, and extracting a displacement amount over time of the earth's surface shape to obtain displacement amount data;
An installation information storage procedure for storing installation information of the overhead power transmission line;
a distance detection process step of calculating a distance between the overhead power transmission line and the ground surface shape using the initial value data, the displacement amount data, and the installation information;
A method for monitoring a power transmission line is provided, comprising:

According to yet another aspect of the present disclosure,
On the computer,
an initial value data acquisition step of acquiring three-dimensional data of the ground surface shape of the area where the overhead power transmission line is arranged, which is actually measured using an aircraft, as initial value data;
a displacement amount data acquisition step of acquiring and analyzing observation data regarding the earth's surface shape periodically transmitted from a satellite, and extracting a displacement amount over time of the earth's surface shape to obtain displacement amount data;
An installation information storage step of storing installation information of the overhead power transmission line;
a distance detection processing step of calculating a distance between the overhead power transmission line and the ground surface shape using the initial value data, the displacement amount data, and the installation information;
A power line monitoring program is provided that causes the power line monitoring program to execute the following:

According to the present disclosure, it is possible to accurately measure the distance between an overhead power line and the ground surface shape while reflecting the displacement that occurs in the ground surface shape, and even in this case, it is possible to reduce the time and cost required for measurement.

1 is an explanatory diagram illustrating a schematic configuration example of a power transmission line monitoring system according to an embodiment of the present invention; 1 is a flowchart showing an example of a procedure of a power transmission line monitoring method according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing a specific example of an SAR image processed by the power transmission line monitoring method according to the embodiment of the present invention. FIG. 1 is an explanatory diagram (part 1) showing a specific example of three-dimensional coordinate space data processed by a power transmission line monitoring method according to an embodiment of the present invention. FIG. 2 is an explanatory diagram (part 2) showing a specific example of three-dimensional coordinate space data processed by the power transmission line monitoring method according to one embodiment of the present invention. 1 is an explanatory diagram showing a specific example of a resolution conversion process in a power transmission line monitoring method according to an embodiment of the present invention; FIG. 3 is an explanatory diagram (part 3) showing a specific example of three-dimensional coordinate space data processed by the power transmission line monitoring method according to one embodiment of the present invention. FIG. 4 is an explanatory diagram (part 4) showing a specific example of three-dimensional coordinate space data processed by the power transmission line monitoring method according to one embodiment of the present invention. FIG. 2 is an explanatory diagram showing a specific example of a power line sag calculation in the power transmission line monitoring method according to an embodiment of the present invention.

<Insights gained by the inventors>
First, the findings of the inventors of the present application will be described.

While it is necessary to ensure a certain distance between overhead power lines and the ground surface shape around them, this can change over time due to factors such as the growth of trees that make up the ground surface shape and the effects of disasters. For this reason, it is necessary to periodically measure the distance between the overhead power lines and the ground surface shape to determine whether there are any abnormalities.

As disclosed in Patent Document 1, for example, the measurement of the distance between an overhead power transmission line and the ground surface shape can be performed with high accuracy by measuring the ground surface shape using a laser measuring device mounted on a helicopter. However, if the distance is measured periodically, there is a risk that the measurement costs will be excessive due to helicopter usage fees and maintenance costs for the laser measuring device. Also, in bad weather, it may not be possible to fly the helicopter, making it impossible to perform measurements when needed.

On the other hand, in recent years, a technology has been known that uses radio waves from satellites to observe the earth's surface, such as interferometric SAR (Synthetic Aperture Radar), and images the strength of the waves reflected from the earth's surface, making it possible to determine the state of the earth's surface. However, SAR images obtained by interferometric SAR can only measure the amount of displacement of the state of the earth's surface. In other words, although SAR images are suitable for extracting the amount of displacement of the state of the earth's surface by using the difference between multiple images, it is difficult to accurately determine, for example, the absolute value of the height of a tree using SAR images alone, so they are not used to grasp the shape of the earth's surface around overhead power lines.

As described above, existing technologies are not suitable for periodic measurement of the distance between overhead power lines and the ground surface. After extensive research into this point, the inventors of the present application came up with the idea that by focusing on the advantages of multiple technologies that were originally used for different purposes and making them usable, it might be possible to perform periodic measurement of the distance accurately and at low cost, without being dependent on weather conditions, etc.

The distance between an overhead transmission line and the ground surface shape is also affected by the sag of the overhead transmission line. However, the manner in which the sag of the overhead transmission line occurs (how much it sags) can vary depending on the magnitude of the current, weather conditions, etc., and it is difficult to accurately grasp this using laser measuring instruments, SAR images, etc. After extensive research into this point, the inventors of the present application came up with the idea that accurately grasping the sag of the overhead transmission line is extremely useful for appropriately measuring the distance between the overhead transmission line and the ground surface shape.

This disclosure is based on the above novel idea discovered by the inventors of the present application.

<One embodiment of the present disclosure>
(1) Configuration of Power Transmission Line Monitoring System Next, a configuration example of a power transmission line monitoring system will be described.
FIG. 1 is an explanatory diagram that illustrates a schematic configuration example of a power transmission line monitoring system according to this embodiment.

(Overall composition)
The power transmission line monitoring system of this embodiment is configured to periodically measure the distance between an overhead power transmission line 2 supported by a steel tower 1 and a ground surface shape 5 including trees 3, buildings 4, etc. present in the surrounding area in order to monitor whether there is any abnormality in the distance between them.

To this end, the power transmission line monitoring system includes at least a server device 10 having computer functions, and a temperature sensor unit 20 attached to the overhead power transmission line 2. The server device 10 and the temperature sensor unit 20 are communicatively connected via a communication line network 23. Therefore, the server device 10 may be installed in a location remote from the overhead power transmission line 2. Details of the temperature sensor unit 20 will be described later.

(Server device)
The server device 10 is communicably connected to a ground station 32 that receives observation data from an artificial satellite 31. The observation data from the artificial satellite 31 is exemplified by an SAR image of the ground surface shape 5 around the overhead power transmission line 2. In other words, the server device 10 is capable of receiving a service of providing an SAR image of the ground surface shape 5 around the overhead power transmission line 2.

The server device 10 also has hardware resources such as a storage device 11 that stores various information and a CPU (Central Processing Unit) (not shown). The CPU executes a pre-installed program, so that the server device 10 functions as an initial value data acquisition unit 12, a displacement amount data acquisition unit 12, an installation information storage unit 13, a wire slack calculation unit 14, a separation detection processing unit 15, and a matching processing unit 16.

The initial value data acquisition unit 12 has a function of acquiring three-dimensional data measured using a laser measuring device mounted on an aircraft such as a helicopter or drone for the ground surface shape 5 around the overhead power transmission line 2 (i.e., the ground surface shape 5 of the area in which the overhead power transmission line 2 is located) as initial value data for the ground surface shape 5. The measurement of the three-dimensional data using the aircraft may be performed using known technology. Furthermore, the measurement results may be acquired via the communication network 23 or using a computer-readable recording medium, and the method is not particularly limited. The initial value data is stored and held in the storage device 11 as necessary and organized into a database.

When SAR images, which are observation data from an artificial satellite 31, are periodically sent via a ground station 32, the displacement amount data acquisition unit 12 acquires and analyzes the SAR images, extracts the amount of displacement over time of the ground surface shape 5 around the overhead power transmission line 2, and converts it into displacement amount data. SAR images are sent from the ground station 32, for example, once every few days. The sent SAR images and the displacement amount data extracted based on them are stored and held in the storage device 11 as necessary and organized into a database.

The installation information storage unit 13 is a function that uses a specified area of the storage device 11 to store the installation information of the overhead transmission line 2 in a database. The installation information of the overhead transmission line 2 is information that specifies the location where the overhead transmission line 2 is installed. Specifically, examples of information about the tower 1 that supports the overhead transmission line 2 include the latitude, longitude, height above ground, span length, and position and length of the cross arm where the tower 1 is installed. However, as long as the installation location of the overhead transmission line 2 can be specified, the information is not limited to these and may include other information. The installation information may be input to the server device 10 by a known method, such as using an information input unit or a communication unit (not shown).

The electric wire sag calculation unit 14 is a function that calculates the sag of the overhead transmission line 2 using the temperature measurement data obtained by the temperature sensor unit 20. The method for calculating the sag of the overhead transmission line 2 is not particularly limited, but a specific example will be described later.

The distance detection processing unit 15 is a function that calculates the distance between the overhead transmission line 2 and the surrounding ground surface shape 5 using the initial value data acquired by the initial value data acquisition unit 12, the displacement amount data extracted by the displacement amount data acquisition unit 12, and the installation information held by the installation information holding unit 13, and judges whether or not there is an abnormality in the calculated distance. When calculating the distance, the distance detection processing unit 15 may take into account the sag of the overhead transmission line 2 calculated by the electric wire sag calculation unit 14.

The alignment processing unit 16 is a function that performs processing to align the initial value data acquired by the initial value data acquisition unit 12 with the SAR image that is the basis of the displacement amount data extracted by the displacement amount data acquisition unit 12. The processing performed by the alignment processing unit 16 includes various processing for aligning the initial value data with the SAR image, and one specific example is a resolution conversion process that aligns the resolution of the initial value data with the resolution of the SAR image. Details of alignment processing such as resolution conversion processing will be described later.

(program)
As described above, the functions of the above-described units 12 to 16 are realized by the CPU executing a predetermined program. The predetermined program that causes a computer to execute these functions corresponds to an example of a power transmission line monitoring program according to the present disclosure.

In this case, if the power line monitoring program can be installed in a computer (e.g., server device 10), it may be provided by being stored in a recording medium readable by the computer (e.g., a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc.), or it may be provided from outside via a network such as the Internet or a dedicated line.

(Temperature sensor part)
The temperature sensor unit 20 measures the temperature of the overhead transmission line 2. To this end, the temperature sensor unit 20 is configured to include a sensor main body unit 21 that is attached to each of the multiple overhead transmission lines 2 supported by the tower 1, and an aggregation terminal unit 22 that performs short-range wireless communication with each sensor main body unit 21. The sensor main body unit 21 is configured to obtain a detection signal regarding the temperature of the overhead transmission line 2, for example, by using a thermocouple directly attached to the overhead transmission line 2. The aggregation terminal unit 22 is configured to receive the detection signal from each sensor main body unit 21, convert it into temperature measurement data representing the temperature value of the overhead transmission line 2, and output the temperature measurement data onto the communication line network 23.

The temperature sensor unit 20 configured in this manner is arranged, for example, at each interval between steel towers 1, measures the temperature of the overhead power transmission line 2 between the steel towers 1 at a frequency of every predetermined time (for example, every few seconds to a few minutes), and outputs the measurement results, that is, the temperature measurement data, onto the communication line network 23. The output temperature measurement data is stored and held in a cloud server on the communication line network 23 as necessary, and then transmitted to the server device 10 in response to a request from the server device 10. However, the arrangement interval, measurement frequency, handling on the communication line network 23, etc. are not limited to a specific embodiment. For example, details of temperature measurement using sensors can be realized using publicly known technology (for example, see JP 2018-201276 A).

(2) Procedure of Power Transmission Line Monitoring Method Next, a procedure for monitoring a power transmission line using the power transmission line monitoring system configured as described above, that is, a procedure of the power transmission line monitoring method according to this embodiment will be described.

Figure 2 is a flow diagram showing an example of the procedure of the power line monitoring method according to this embodiment. Figure 3 is an explanatory diagram showing a specific example of an SAR image processed by the power line monitoring method according to this embodiment. Figures 4, 5, 7, and 8 are explanatory diagrams showing a specific example of three-dimensional coordinate space data processed by the power line monitoring method according to this embodiment. Figure 6 is an explanatory diagram showing a specific example of resolution conversion processing in the power line monitoring method according to this embodiment. Figure 9 is an explanatory diagram showing a specific example of power line sag calculation in the power line monitoring method according to this embodiment.

As shown in FIG. 2, when the power transmission line monitoring system is operated, first, pre-processing required for operation is performed (step 101, hereinafter, step is abbreviated as "S"). The pre-processing includes at least a process of registering initial value data (see (a) in the figure), a process of registering a SAR reference image (see (b) in the figure), and a process of registering installation information (see (c) in the figure).

In the initial value data registration process, the initial value data acquisition unit 12 of the server device 10 receives the results of laser measurements taken using an aircraft such as a helicopter or drone on the ground surface shape 5 around the overhead power line 2 to be monitored, and processes these as three-dimensional data in a specified coordinate space to create initial value data for the ground surface shape 5. The initial value data is then registered in a database in a specified area of the storage device 11 while being associated with the acquisition date and time of the initial value data.

In the process of registering the SAR reference image, the displacement data acquisition unit 12 of the server device 10 acquires SAR images of the ground surface shape 5 around the overhead power transmission line 2 to be monitored, which are periodically sent from the artificial satellite 31 via the ground station 32, and among the acquired SAR images, the SAR image acquired at the timing closest to the acquisition date and time of the initial value data (including the same timing) is set as the SAR reference image. Then, the SAR reference image is registered in a database in a specified area in the storage device 11.

In the installation information registration process, when information such as the latitude, longitude, height above ground, span length, and cross arm position/length at which the steel tower 1 supporting the overhead power transmission line 2 is installed is input to the server device 10 as the installation information of the overhead power transmission line 2, the installation information storage unit 13 of the server device 10 registers the input installation information in a database in a specified area of the storage device 11.

After carrying out the above pre-processing, the power transmission line monitoring system enters an operating state. While the power transmission line monitoring system is operating, SAR images are periodically sent from the artificial satellite 31 via the ground station 32, and the sent SAR images are stored and held in a specified area of the storage device 11 in association with the acquisition date and time. In addition, the temperature of the overhead power line 2 to be monitored is measured by the temperature sensor unit 20, and the measurement result, that is, the temperature measurement data, is stored and held in a cloud server on the communication line network 23.

When the power transmission line monitoring system is in an operational state, it becomes possible to monitor the power transmission line using the power transmission line monitoring system. In the power transmission line monitoring system, the power transmission line monitoring is performed, for example, at a preset periodic timing or at a timing when a change in the ground surface shape 5 is expected due to the occurrence of a disaster or the like.

When monitoring a power transmission line, in the power transmission line monitoring system, the displacement amount data acquisition unit 12 of the server device 10 reads and acquires the SAR image acquired at the timing closest to the date and time of power transmission line monitoring (including the same timing) from the storage device 11 as the latest SAR image (S102).

When the latest SAR image is acquired, as shown in FIG. 2, the displacement amount data acquisition unit 12 reads and acquires the SAR reference image registered in preprocessing from the storage device 11. Then, image analysis is performed on the latest SAR image and the SAR reference image, and the difference between them is calculated as the amount of displacement over time of the earth's surface shape 5. In other words, the displacement amount data acquisition unit 12 calculates the amount of displacement over time of the earth's surface shape 5 based on the latest SAR image and the SAR reference image, and the calculation result is used as displacement amount data for the earth's surface shape 5 (S103).

After calculating the displacement amount data, the server device 10 has the distance detection processing unit 15 read out the installation information stored in the installation information storage unit 13, thereby obtaining information (position, height, etc.) about the tower 1 supporting the overhead power transmission line 2 to be monitored. Furthermore, the distance detection processing unit 15 cuts out a SAR image of the surrounding area including the tower 1, and obtains displacement amount data about the ground surface shape 5 of the surrounding area (S104).

Specifically, as shown in FIG. 3, the displacement amount data acquisition unit 12 converts area image data in which brightness varies depending on the magnitude of the difference (displacement amount) into displacement amount data, and focuses on the surrounding area including the steel tower 1 supporting the overhead transmission line 2 to be monitored, and performs image cropping for that surrounding area.

Then, as shown in FIG. 2, the distance detection processing unit 15 uses the tower 1 supporting the overhead power transmission line 2 to be monitored as a reference and performs coordinate conversion of the ground surface shape 5 of the surrounding area including the tower 1 into a predetermined three-dimensional coordinate space (S105).

Specifically, as shown in FIG. 4, for example, the distance detection processing unit 15 assumes a three-dimensional coordinate space in which the position of the ground (foundation) on which the reference tower 1 is installed is the zero point, the height direction of the tower 1 is the z-axis direction, the line direction along which the overhead power line 2 supported by the tower 1 extends is the y-axis direction, and the direction perpendicular to the y-axis and z-axis is the x-axis direction. Then, in that three-dimensional coordinate space, coordinate conversion is performed on the displacement amount data and installation information so that the support position of the overhead power line 2 by the tower 1 and the magnitude of the displacement amount (z value) of the ground surface shape 5 at each point on the xy plane are reflected (see the gray bar plots in the figure).

Next, as shown in FIG. 2, the distance detection processing unit 15 reads out and acquires the initial value data registered in the preprocessing from the storage device 11. Then, the initial value data is reflected in the three-dimensional coordinate space, thereby synthesizing the initial value data and the displacement amount data. As a result, the distance detection processing unit 15 creates a three-dimensional measurement image that reflects the absolute values of the height direction of the ground surface shape 5 in the area surrounding the steel tower 1 (S106).

Specifically, as shown in FIG. 5, for example, the distance detection processing unit 15 performs coordinate transformation on the initial value data so that the magnitude (z value) of the initial value data of the ground surface shape 5 at each point on the xy plane is reflected in the three-dimensional coordinate space reflecting the displacement amount data, and thus creates a three-dimensional measurement image.

As described above, the distance detection processing unit 15 creates a three-dimensional measurement image using the initial value data, the displacement amount data, and the installation information. This three-dimensional measurement image is used to calculate the distance between the overhead transmission line 2 and the surrounding ground surface shape 5.

When creating such a three-dimensional measuring image, the initial value data and the SAR image on which the displacement amount data is based are not necessarily suitable for processing in the same three-dimensional coordinate space. For example, this is because they generally have different resolutions. Therefore, in the server device 10, after the initial value data and the SAR image are acquired and before the three-dimensional measuring image is created, the alignment processing unit 16 performs processing to align at least one of the initial value data and the SAR image. The processing performed by the alignment processing unit 16 can include various processing including resolution conversion processing.

Here, the resolution conversion process performed by the alignment processing unit 16 will be described with a specific example.
As shown in Fig. 6, the initial value data and the displacement amount data obtained from the SAR image have different resolutions (data resolution). In addition, since the displacement amount data is subjected to coordinate conversion, it is not arranged in a manner that matches the y-axis direction (railway direction) and x-axis direction (perpendicular direction) of the three-dimensional coordinate space. Therefore, in order to create a three-dimensional measurement image, it is necessary to group the displacement amount data according to which initial value data it corresponds to.
The matching processing unit 16 performs grouping, for example, by the following method. Specifically, when performing grouping, the displacement amount data is divided into meshes, and the initial value data belonging to each region is extracted and labeled (assigned a number label). As a result, the initial value data is assigned the same number label as the displacement amount data that is close in distance on the x and y coordinates, and the data is grouped according to the number label. In other words, by grouping using the number label, it becomes clear which initial value data corresponds to which displacement amount data.
After grouping, the displacement amount data with the same label number is added to the initial value data to create a three-dimensional measuring image. In other words, even if the resolution (data resolution) of the initial value data and the displacement amount data is different, the difference in resolution between the initial value data and the displacement amount data can be eliminated by adding data with the same numbers while utilizing the grouping result.
Although the resolution conversion process using grouping by labeling is given here as an example, the resolution conversion process performed by the alignment processing unit 16 is not limited to this, and may be performed using other methods. Furthermore, the alignment processing unit 16 may perform processes other than the resolution conversion process as long as they are processes for aligning the initial value data with the SAR image (or the displacement amount data obtained from the SAR image) in order to create a three-dimensional measuring image.

After performing such an alignment process that includes a resolution conversion process, the initial value data and the displacement data obtained from the SAR image become suitable for processing in the same three-dimensional coordinate space, making it possible to easily and smoothly create a three-dimensional measurement image.

After creating the three-dimensional measuring image, the distance detection processing unit 15 uses the three-dimensional measuring image to calculate the distance between the overhead power transmission line 2 and the surrounding ground surface shape 5 .
However, the overhead transmission line 2 is disposed between the steel towers 1. Therefore, sagging (slackness) occurs in the overhead transmission line 2, and the manner in which it occurs (how it sags) is not always constant but can vary depending on the magnitude of the current and meteorological conditions (weather, temperature, wind conditions, etc.).
The sag of the overhead transmission line 2 has a large effect on the calculation result of the distance from the ground surface shape 5, so it is desirable to grasp it in advance when calculating the distance.
However, for that purpose, it is not necessarily realistic to comprehensively detect the weather conditions at the installation location of the overhead transmission line 2 or to identify the correspondence between the change in the weather conditions and the fluctuation of the sag generation mode. In addition, although it is conceivable to adopt the sag (fixed value) calculated under predetermined conditions, this does not reflect the fluctuation of the sag generation mode, and it cannot be said that the sag of the overhead transmission line 2 can be grasped with high accuracy.

The sag of the overhead transmission line 2 is thought to be greatly affected by the expansion and contraction of the overhead transmission line 2 in the line direction. One of the factors that causes the overhead transmission line 2 to expand and contract is temperature change of the overhead transmission line 2. The temperature of the overhead transmission line 2 can change due to various factors, including changes in the magnitude of the current and weather conditions. In other words, it can be thought that the major factor that changes the occurrence mode of the sag of the overhead transmission line 2 is temperature change of the overhead transmission line 2.

In this embodiment, as shown in FIG. 2, when calculating the distance between the overhead transmission line 2 and the ground surface shape 5, the electric wire sag calculation unit 14 accesses a cloud server on the communication line network 23. Then, from the cloud server, the electric wire sag calculation unit 14 obtains temperature measurement data detected by the temperature sensor unit 20 for the overhead transmission line 2 to be monitored (S107). At this time, the electric wire sag calculation unit 14 may obtain only the temperature measurement data (i.e., the latest temperature measurement data) that is the detection result at the timing closest to the calculation date and time of the distance (including the same timing), or may obtain all temperature measurement data detected during a predetermined period (for example, from the previous calculation of the distance to the current calculation of the distance).

Then, when the temperature measurement data is acquired, the electric wire sag calculation unit 14 extracts one of the temperature measurement data to be used for calculating the sag of the overhead transmission line 2 from the acquired temperature measurement data (S108). For example, if only the latest temperature measurement data is acquired, that temperature measurement data is extracted. If all temperature measurement data obtained during a specified period is acquired, for example, the latest temperature measurement data may be extracted from the data. By extracting the latest temperature measurement data in this way, the temperature of the overhead transmission line 2 at the time of calculating the sag can be reflected in the calculation result of the sag. Also, if all temperature measurement data obtained during a specified period is acquired, for example, the highest temperature measurement data may be extracted from the data. By extracting the highest temperature measurement data within the specified period in this way, the sag of the overhead transmission line 2 can be calculated assuming the worst-case condition in which the overhead transmission line 2 is most likely to sag.

When any one of the temperature measurement data is extracted, the electric wire sag calculation unit 14 uses the extracted temperature measurement data to calculate the sag of the overhead transmission line 2 (S109). The sag calculation is performed, for example, in the following procedure.

When calculating the sag of the conductor from the temperature measurement data, the conductor tension is calculated first. For example, the actual conductor length in the reference state (maximum usable tension _T0 at wind speed 40 m/s and conductor temperature _t0 (=15°C)) is defined as _L0 . If the conductor tension when the conductor temperature reaches _t1 is defined as _T1 and the actual conductor length is defined as _L1 , the conductor temperature _t1 and the conductor tension _T1 are expressed by the following relational expression. The conductor tension _T1 is calculated from this relational expression.

After the calculation of the wire tension _T1 , the wire sag is calculated. For example, as shown in Fig. 9, the wire sag d is calculated by the three-point angle method from the wire at an arbitrary point D in the figure, the elevation angles of points A, B, and D shown in the figure, the horizontal angle between A'B' and A'D', and the relationship between the span length S and the height difference h of the support. The relational expression between the wire tension _T1 and the wire sag d is as follows:

After calculating the conductor sag, the conductor sag calculation unit 14 uses the calculated conductor sag value to calculate the conductor catenary curve, which represents the occurrence of sag in the overhead transmission line 2, as shown in FIG. 2. The conductor sag calculation unit 14 then reflects the conductor catenary curve in the three-dimensional measurement image created for the distance calculation (S110). There are no particular limitations on the method for calculating the conductor catenary curve and drawing it in the three-dimensional measurement image, and any known method may be used.

As a result, the three-dimensional measurement image depicts the manner in which sagging occurs in the overhead transmission line 2 supported by the tower 1, as shown in, for example, Figure 7.

When multiple overhead transmission lines 2 are supported on the tower 1, the wire sag calculation unit 14 performs the above process for each of the overhead transmission lines 2. However, this is not necessarily limited to this, and it is also possible to select at least one of the multiple overhead transmission lines 2 (e.g., an overhead transmission line 2 located close to the ground surface) and perform the process only for the selected overhead transmission line 2.

Then, as shown in FIG. 2, the distance detection processing unit 15 calculates the distance between the overhead power transmission line 2 and the surrounding ground surface shape 5 in the three-dimensional measurement image reflecting the power transmission line catenary curve. Then, the distance detection processing unit 15 determines whether or not there is an abnormality in the calculated distance (S111).

As shown in Figure 8, for example, the calculation of the separation can be performed by determining the shortest distance between the top of the ground surface shape 5 in the height direction and the overhead power transmission line 2 for each point on the xy plane in the three-dimensional measurement image, and extracting the closest (smallest) shortest distance among each point (see arrows in the figure). In other words, the value of the smallest shortest distance is the calculated result of the separation between the overhead power transmission line 2 and the ground surface shape 5.

The presence or absence of an abnormality in the calculation result of the separation can be determined by comparing the calculation result with a preset tolerance. Specifically, for example, if the calculation result of the separation is equal to or greater than the tolerance, the separation detection processing unit 15 determines that there is no abnormality in the separation between the overhead transmission line 2 and the ground surface shape 5. On the other hand, if the calculation result of the separation is less than the tolerance, the separation detection processing unit 15 determines that the separation between the overhead transmission line 2 and the ground surface shape 5 has not been secured and that an abnormality has occurred in the separation.

When the distance detection processing unit 15 determines that an abnormality has occurred in the distance, the server device 10 outputs an alarm to that effect through the display output unit of the server device 10 or a terminal device or the like that is communicably connected to the server device 10. This allows the user of the server device 10 or the terminal device or the like to know that an abnormality has occurred in the distance between the overhead power transmission line 2 and the ground surface shape 5.

(3) Effects of the Present Embodiment According to the present embodiment, one or more of the following effects can be obtained.

(a) According to this embodiment, the separation between the overhead power transmission line 2 and the ground surface shape 5 is calculated using initial value data obtained by actually measuring the ground surface shape 5 using an aircraft, displacement amount data on the ground surface shape 5 obtained by analyzing SAR images periodically sent from the artificial satellite 31, and installation information of the overhead power transmission line 2, and the result is set as the measurement result of the separation. In this way, by using the displacement amount data, it is possible to reflect the displacement occurring in the ground surface shape 5 in the isolation measurement without performing an actual measurement using an aircraft for each isolation measurement. Furthermore, since not only the displacement amount data but also the initial value data obtained by actual measurement are used, the ground surface shape 5 can be measured with high accuracy, and the result of the isolation measurement becomes highly reliable.
In other words, according to this embodiment, even if the distance between the overhead transmission line 2 and the ground surface shape 5 is measured periodically to monitor whether there is any abnormality in the distance, the measurement can be performed accurately while reflecting any displacements occurring in the ground surface shape 5, and the time and cost required for the measurement can be reduced without being dependent on the weather, etc.

(b) According to this embodiment, the amount of displacement of the ground surface shape 5 is calculated based on the SAR reference image acquired closest to the time when the initial value data is acquired and the latest SAR image acquired closest to the date and time when the power line is monitored (i.e., the date and time when the separation calculation is performed), and this is used as the displacement amount data. Therefore, the measurement result of the separation between the overhead power line 2 and the ground surface shape 5 reliably reflects the amount of displacement of the ground surface shape 5 between the time when the initial value data is acquired and the date and time when the power line is monitored. This makes the results of the isolation measurement very reliable.

(c) According to this embodiment, the sag of the overhead transmission line 2 is calculated using the temperature measurement data obtained by the temperature sensor unit 20, and the calculated sag of the overhead transmission line 2 is taken into account to calculate the distance between the overhead transmission line 2 and the ground surface shape 5. Therefore, even if the sag occurrence mode (degree of sagging) of the overhead transmission line 2 varies depending on the magnitude of the current, weather conditions, etc., it is possible to accurately grasp the sag of the overhead transmission line 2 while reflecting the variation. In other words, according to this embodiment, the distance between the overhead transmission line 2 and the ground surface shape 5 can be accurately measured while reflecting the variation in the sag occurrence mode of the overhead transmission line 2, and as a result, the results of the isolation measurement are highly reliable.

(d) As described in this embodiment, when calculating the sag of the overhead transmission line 2, if the latest temperature measurement data obtained closest to the time of the isolated measurement is used, the temperature of the overhead transmission line 2 at the time of calculating the sag can be reflected in the calculation result of the sag. In other words, the temperature measurement data is reflected in real time, which is suitable for knowing the current results of the isolated measurement.

(e) As described in this embodiment, when calculating the sag of the overhead transmission line 2, if the highest temperature measurement data among the temperature measurement data obtained in a specified period is used, the sag of the overhead transmission line 2 can be calculated assuming the worst-case conditions in which the overhead transmission line 2 would be the most sag. In other words, the temperature measurement data in the so-called worst case is reflected, which is suitable for knowing the results of the isolation measurement taking into account the degree of risk.

(f) As described in this embodiment, by performing a process to align the initial value data and the SAR image on which the displacement amount data is based, the initial value data and the SAR image become suitable for processing in the same three-dimensional coordinate space, and as a result, it becomes possible to easily and smoothly create a three-dimensional measurement image.

<Modifications, etc.>
Although one embodiment of the present disclosure has been specifically described above, the present disclosure is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit and scope of the present disclosure.

For example, in the above embodiment, the observation data periodically transmitted from the satellite is SAR images, but the present invention is not limited to this. The observation data may be replaced with something other than SAR images as long as it can identify the amount of displacement of the earth's surface shape 5 over time without requiring actual measurements using an aircraft.

In the above embodiment, the sag of the overhead transmission line 2 is calculated using temperature measurement data when measuring the distance between the overhead transmission line 2 and the ground surface shape 5, but this is not limited to the above. For example, the distance between the overhead transmission line 2 and the ground surface shape 5 may be calculated using a sag (fixed value) calculated under predetermined conditions, and even in this case, the distance can be measured with high accuracy while reflecting the displacement occurring in the ground surface shape 5. However, as described in the above embodiment, if the sag of the overhead transmission line 2 is calculated using temperature measurement data, the results of the separation measurement become very reliable as described above, which is very useful in that respect.

In addition, in the above embodiment, the case where the sag of the overhead transmission line 2 is calculated by first calculating the conductor tension and then calculating the conductor sag is given as an example, but this is not limited to this. In other words, the calculation of the sag of the overhead transmission line 2 is not limited to a specific calculation method.

<Preferred aspects of the present disclosure>
Preferred aspects of the present disclosure will be described below.

(Appendix 1)
According to one aspect of the present disclosure,
an initial value data acquisition unit that acquires three-dimensional data of a ground surface shape in an area where the overhead power transmission line is arranged, the data being measured using an aircraft, as initial value data;
a displacement amount data acquisition unit that acquires and analyzes observation data regarding the earth's surface shape periodically transmitted from a satellite, extracts a displacement amount of the earth's surface shape over time, and sets the displacement amount data;
An installation information storage unit that stores installation information of the overhead power transmission line;
a distance detection processing unit that calculates a distance between the overhead power transmission line and the ground surface shape using the initial value data, the displacement amount data, and the installation information;
A power transmission line monitoring system is provided, comprising:

(Appendix 2)
Preferably,
The power transmission line monitoring system described in Appendix 1 is provided, in which the displacement amount data acquisition unit acquires, as the displacement amount data, the amount of displacement between the ground surface shape identified by the observation data acquired at the timing closest to the data acquisition by the initial value data acquisition unit and the ground surface shape identified by the observation data acquired at the timing closest to the separation calculation by the separation detection processing unit.

(Appendix 3)
Preferably,
A temperature sensor unit for measuring a temperature of the overhead transmission line;
a wire sag calculation unit that calculates a sag of the overhead transmission line using temperature measurement data obtained by the temperature sensor unit,
The power transmission line monitoring system according to claim 1 or 2, wherein the separation detection processing unit calculates a separation between the overhead power transmission line and the ground surface shape by taking into account the sag of the overhead power transmission line calculated by the power line sag calculation unit.

(Appendix 4)
Preferably,
The power line sag calculation unit calculates a sag of the overhead transmission line by using the temperature measurement data obtained at a timing closest to the time when the separation detection processing unit calculates the separation.

(Appendix 5)
Preferably,
The power line sag calculation unit calculates the sag of the overhead transmission conductor using the highest temperature among the temperature measurement data obtained during a predetermined period up to the time of the separation detection processing unit's separation calculation.

(Appendix 6)
Preferably,
The power transmission line monitoring system according to any one of Supplementary Notes 1 to 5 further includes a matching processing unit that performs a process of matching the initial value data and the observation data on which the displacement amount data is based.

(Appendix 7)
According to another aspect of the present disclosure,
An initial value data acquisition step of acquiring three-dimensional data of the ground surface shape of the area where the overhead power transmission line is arranged, which is actually measured using an aircraft, as initial value data;
a displacement amount data acquisition step of acquiring and analyzing observation data regarding the earth's surface shape periodically transmitted from a satellite, and extracting a displacement amount over time of the earth's surface shape to obtain displacement amount data;
An installation information storage procedure for storing installation information of the overhead power transmission line;
a distance detection process step of calculating a distance between the overhead power transmission line and the ground surface shape using the initial value data, the displacement amount data, and the installation information;
A method for monitoring a power transmission line is provided, comprising:

(Appendix 8)
According to yet another aspect of the present disclosure,
On the computer,
an initial value data acquisition step of acquiring three-dimensional data of the ground surface shape of the area where the overhead power transmission line is arranged, which is actually measured using an aircraft, as initial value data;
a displacement amount data acquisition step of acquiring and analyzing observation data regarding the earth's surface shape periodically transmitted from a satellite, and extracting a displacement amount over time of the earth's surface shape to obtain displacement amount data;
An installation information storage step of storing installation information of the overhead power transmission line;
a distance detection processing step of calculating a distance between the overhead power transmission line and the ground surface shape using the initial value data, the displacement amount data, and the installation information;
A power line monitoring program is provided that causes the power line monitoring program to execute the following:

Reference Signs List 1: Steel tower 2: Overhead power transmission line 3: Tree 4: Building 5: Ground surface shape 10: Server device 11: Storage device 12: Initial value data acquisition unit 13: Displacement amount data acquisition unit 14: Installation information storage unit 15: Power line sag calculation unit 16: Distance detection processing unit 17: Matching processing unit 20: Temperature sensor unit 21: Sensor main body unit 22: Aggregation terminal unit 31: Artificial satellite 32: Ground station

Claims (8)

an initial value data acquisition unit that acquires three-dimensional data of a ground surface shape in an area where the overhead power transmission line is arranged, the data being measured using an aircraft, as initial value data;
a displacement amount data acquisition unit that acquires and analyzes observation data regarding the earth's surface shape periodically transmitted from a satellite, extracts a displacement amount of the earth's surface shape over time, and sets the displacement amount data;
An installation information storage unit that stores installation information of the overhead power transmission line;
a distance detection processing unit that calculates a distance between the overhead power transmission line and the ground surface shape using the initial value data, the displacement amount data, and the installation information;
A power transmission line monitoring system comprising: 2. The power transmission line monitoring system according to claim 1, wherein the displacement amount data acquisition unit sets as the displacement amount data a displacement amount between the ground surface shape identified by the observation data acquired at the timing closest to the data acquisition time of the initial value data acquisition unit and the ground surface shape identified by the observation data acquired at the timing closest to the separation calculation time of the separation detection processing unit. A temperature sensor unit for measuring a temperature of the overhead transmission line;
a wire sag calculation unit that calculates a sag of the overhead transmission line using temperature measurement data obtained by the temperature sensor unit,
The power transmission line monitoring system according to claim 1 or 2, wherein the separation detection processing unit calculates the separation between the overhead power transmission line and the ground surface shape by taking into account the sag of the overhead power transmission line calculated by the power line sag calculation unit. The power transmission line monitoring system according to claim 3 , wherein the power line sag calculation unit calculates the sag of the overhead transmission line by using the temperature measurement data obtained at a timing closest to the time when the separation detection processing unit calculates the separation. The power transmission line monitoring system according to claim 3 , wherein the power line sag calculation unit calculates the sag of the overhead power transmission line by using the highest temperature measurement data among the temperature measurement data obtained during a predetermined period until the separation detection processing unit calculates the separation. The power transmission line monitoring system according to claim 1 , further comprising a matching processing unit that performs a process of matching the initial value data and the observation data on which the displacement amount data is based. An initial value data acquisition step of acquiring three-dimensional data of the ground surface shape of the area where the overhead power transmission line is arranged, which data is actually measured using an aircraft, as initial value data;
a displacement amount data acquisition step of acquiring and analyzing observation data regarding the earth's surface shape periodically transmitted from a satellite, and extracting a displacement amount over time of the earth's surface shape to obtain displacement amount data;
A setup information storage step for storing setup information of the overhead power transmission line;
a distance detection process step of calculating a distance between the overhead power transmission line and the ground surface shape using the initial value data, the displacement amount data, and the installation information;
A power transmission line monitoring method comprising: On the computer,
an initial value data acquisition step of acquiring three-dimensional data of the ground surface shape of the area where the overhead power transmission line is arranged, which data is actually measured using an aircraft, as initial value data;
a displacement amount data acquisition step of acquiring and analyzing observation data regarding the earth's surface shape periodically transmitted from a satellite, and extracting a displacement amount over time of the earth's surface shape to obtain displacement amount data;
An installation information storage step of storing installation information of the overhead power transmission line;
a distance detection processing step of calculating a distance between the overhead power transmission line and the ground surface shape using the initial value data, the displacement amount data, and the installation information;
A power line monitoring program that executes the above.

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