Failure identification system, failure identification method, and program

Abstract

To provide a fault identification system, a fault identification method, and a program capable of improving identification accuracy of a fault position in a submarine cable.SOLUTION: According to an aspect of the embodiments, a path selection apparatus includes an acquisition unit configured to acquire temperature data of a submarine cable, a correction unit configured to correct a parameter of the submarine cable by using the temperature data and position information of a position where the temperature data is detected, and an identification unit configured to identify a fault position of the submarine cable by using the corrected parameter.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a fault identification system, a fault identification method, and a program. [Background technology]

[0002] Currently, cables for various purposes such as communications and power supply are installed all over the world, and technologies are being developed to perform maintenance work on such cables accurately or more efficiently.

[0003] For example, Patent Document 1 discloses a detection device that detects the location of a ground fault in a power cable. This detection device detects the location of a ground fault based on the step-like distribution characteristic of the temperature rise, which is indicated by the difference between the temperature distribution after the ground fault occurs and the temperature distribution before the ground fault occurs. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-176788 Summary of the Invention [Problem to be solved by the invention]

[0005] When a fault (such as a ground fault) occurs in a cable in a submarine cable communication system, the accuracy of locating the fault using current fault detection methods is limited to a distance of several tens to 100 km. Therefore, in order to actually locate the fault, it is necessary to reel in the cable using a ship. This work not only takes a long time but also incurs a correspondingly high cost.

[0006] One of the objectives that the embodiments of the present disclosure aim to achieve is to provide a fault location system, a fault location method, and a program that can improve the accuracy of identifying a fault location in a submarine cable. It should be noted that this objective is only one of multiple objectives that the embodiments disclosed herein aim to achieve. Other objectives or problems and novel features will become apparent from the description of this specification or the accompanying drawings. [Means for solving the problem]

[0007] A fault identification system according to one aspect includes: an acquisition means for acquiring temperature data of the submarine cable; a correction means for correcting parameters of the submarine cable by using the temperature data and location information of a location where the temperature data is detected; and a location determination means for determining a fault location in the submarine cable using the corrected parameters.

[0008] A fault identification method according to one aspect includes the steps of: Acquire temperature data from undersea cables, correcting parameters of the submarine cable by using the temperature data and location information of a location where the temperature data was detected; using the corrected parameters to identify the location of the fault in the submarine cable; It is a computer-implemented method.

[0009] In one aspect, the program Acquire temperature data from undersea cables, correcting parameters of the submarine cable by using the temperature data and location information of a location where the temperature data was detected; using the corrected parameters to identify the location of the fault in the submarine cable; This is what causes a computer to execute the above. [Effects of the Invention]

[0010] The present disclosure makes it possible to provide a fault location system, a fault location method, and a program that can improve the accuracy of identifying a fault location in a submarine cable. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a block diagram illustrating an example of a fault identification system according to the present disclosure. [Figure 2] 1 is a flowchart illustrating an example of a representative process of the fault identification system. [Figure 3] 1 is a schematic diagram illustrating an example of a submarine cable communication system according to the present disclosure. [Figure 4] FIG. 2 is a block diagram showing an example of a repeater and a branching device. [Figure 5] FIG. 1 is a block diagram illustrating an example of a PFE. [Figure 6] FIG. 2 is a block diagram illustrating an example of an NMS. [Figure 7] 10 is a flowchart illustrating an example of a representative process of an NMS. [Figure 8] FIG. 2 is a block diagram illustrating an example of a hardware configuration of an information processing device in which processing of the system or device is executed. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the following descriptions and drawings in the embodiments have been omitted or simplified as appropriate for clarity of explanation. Furthermore, in this disclosure, unless otherwise specified, when multiple items are defined as "at least one of multiple items," the definition may mean any one item, or any multiple items including all items.

[0013] Each drawing referenced in the embodiments is merely an example for describing one or more embodiments. Each drawing may not relate to only one particular embodiment, but may also relate to one or more other embodiments. As will be understood by those skilled in the art, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings to create, for example, an embodiment not explicitly shown or described. Not all features or steps shown in any one drawing are necessarily required to describe an exemplary embodiment, and some features or steps may be omitted. The order of steps described in any drawing may be changed as appropriate.

[0014] The "submarine cable" described in the following embodiments is a cable at least part of which is laid on the seabed. Submarine cables are used for any purpose, such as communications, power supply, etc.

[0015] Embodiment 1 [Configuration Description] 1 is a block diagram showing an example of a fault identification system according to the present disclosure. The fault identification system 10 includes an acquisition unit 102, a correction unit 104, and an identification unit 106. Each unit of the fault identification system 10 will be described below.

[0016] The acquiring unit 102 acquires temperature data of the submarine cable that is the target of fault identification. The acquiring unit 102 may acquire temperature data at one or more positions in the submarine cable, for example, data detected by a temperature sensor installed at a predetermined position, or data detected using fiber sensing technology.

[0017] Fiber sensing can be achieved using, for example, fiber Bragg gratings (FBG) and band pass filters on fiber ends (BOF). In FBG, optical fiber constituting a submarine cable is processed to provide multiple diffraction gratings at specific locations on the optical fiber. When light from a light source is incident on the multiple diffraction gratings, the wavelength of the reflected light (hereinafter also referred to as return light) from the diffraction gratings is measured, thereby enabling detection of the temperature at the location where the diffraction gratings are located. In BOF, a dielectric multilayer film is formed at the end of the optical fiber constituting the submarine cable. When light from a light source is incident on the dielectric multilayer film, the reflectance spectrum changes depending on the temperature of the dielectric multilayer film. Therefore, the temperature at the location where the dielectric multilayer film is located can be detected by detecting the reflectance of the return light.

[0018] The acquiring unit 102 may be, for example, an interface that receives, via a wired or wireless connection, temperature data detected by a temperature sensor installed at one or more positions on the submarine cable. When the acquiring unit 102 receives the temperature data via a wired connection, the temperature data may be transmitted from the temperature sensor via an optical fiber that constitutes the submarine cable. As another example, the acquiring unit 102 may include an optical sensor that acquires return light from a diffraction grating or a dielectric multilayer film (hereinafter, both of which are collectively referred to as a sensing element) using fiber sensing technology. The optical sensor acquires temperature data information at one or more positions by acquiring return light from the sensing element installed at that position.

[0019] The correction unit 104 corrects the parameters of the submarine cable by using the temperature data acquired by the acquisition unit 102 and the location information of the location where the temperature data was detected. For example, the temperature sensor may transmit its own location information along with the detected temperature data, and the acquisition unit 102 may acquire that location information. As another example, the location information of the sensing element used for fiber sensing may be stored in a memory unit of the fault identification system 10. The correction unit 104 can use the location information acquired or stored in this manner.

[0020] The submarine cable parameters corrected by the correction unit 104 are parameters required for calculations when the identification unit 106 identifies the location of a fault. The parameters vary depending on temperature, such as the resistivity of the submarine cable. However, the types of parameters to be corrected are not limited to this. Furthermore, the number of parameters to be corrected is not limited to one, and multiple types may be used.

[0021] The identifying unit 106 identifies the location of a fault in the submarine cable using the parameters corrected by the correcting unit 104. For example, assume that the fault identification system 10 is made up of a land-based monitoring device connected to the submarine cable, and that the monitoring device monitors a ground fault in the submarine cable as a fault. A ground fault is a fault in which the power supply line associated with the optical fiber is disconnected, rather than the optical fiber. However, the fault that occurs is not limited to a ground fault.

[0022] In this case, the length from the monitoring device to the earth fault is L [m], the voltage value of the cable is V [V], and the cross-sectional area of ​​the cable is S [m 2 ], the resistivity of the cable is ρ [Ωm], and the current value is I [A]. L is the length value that uniquely identifies the fault location to be identified. The voltage value V and the current value I can be acquired by the acquisition unit 102 by measuring the submarine cable. Furthermore, the cross-sectional area S is a parameter that is predetermined for the optical fiber.

[0023] The voltage value V varies depending on the location of the fault. Therefore, the fault identification system 10 may detect the occurrence of a fault, for example, when the fluctuation value of the voltage value V becomes equal to or greater than a predetermined threshold. The current value I is also assumed to be a substantially constant value. After detecting the occurrence of a fault, the correction unit 104 corrects the resistivity ρ, which is a parameter, as described above.

[0024] For example, the resistivity ρ0 at a reference temperature (e.g., 0 degrees Celsius) may be set as the reference resistivity. When the difference between the detected temperature data at one or more positions and the reference temperature is T, the correction unit 104 calculates the resistivity ρ corrected by the temperature data based on the following formula. ρ=ρ0(1+α*T) (1) Here, α is a coefficient related to temperature changes that depend on the material that makes up the optical fiber. The resistivity ρ depends on the resistivity ρ0, which is determined depending on the type of optical fiber, and the temperature difference T, which is affected by the seawater temperature. While the material of the optical fiber is assumed to be constant, the seawater temperature is assumed to fluctuate. Therefore, the resistivity ρ is thought to take on different values ​​depending on the time of the fault.

[0025] The correction unit 104 may identify the coefficient α corresponding to either the detected temperature or the temperature calculated based on the temperature data by referring to a table in which temperatures and coefficients α are associated. The correction unit 104 calculates the resistivity ρ using the identified coefficient α. Alternatively, the correction unit 104 may identify the ρ corresponding to either the detected temperature or the temperature calculated based on the temperature data by referring to a table in which temperatures and ρ are associated. Here, the "temperature calculated based on temperature data" refers to the estimated temperature at the fault location calculated based on the temperature data. For example, when temperature data is detected at multiple points on the submarine cable, the correction unit 104 may calculate the estimated temperature by any interpolation method using the temperature data. Alternatively, the correction unit 104 may calculate the estimated temperature by applying a predetermined function to the temperature data detected at a certain point. The correction unit 104 outputs the resistivity ρ corrected as described above to the identification unit 106.

[0026] Using Ohm's law, the voltage value V, resistance value R [Ω], and current value I in the optical fiber in the section from the monitoring device to the ground fault have the following relationship: V=RI (2) Here, the resistance value R is expressed as follows using the length to the fault location L, the cross-sectional area S, and the current value I. R=(ρ*L) / S (3) Therefore, the specification unit 106 can use the above parameters to calculate the length L as follows, by using the formulas (2) and (3). L = (V * S) / (ρ * I) (4)

[0027] The correcting unit 104 may correct the resistance value R instead of the resistivity ρ. In this way, the specifying unit 106 can also calculate the length L.

[0028] It should be noted that the submarine cable may be made of other types of fiber than optical fiber. Even in such cases, the respective components of the fault identification system 10 can perform the same processing.

[0029] [Flow description] 2 is a flowchart showing an example of a typical process of the fault identification system 10. This flowchart explains the process of the fault identification system 10. Note that the details of each process are as described above, and therefore will not be explained again as appropriate.

[0030] First, the acquisition unit 102 acquires temperature data of the submarine cable (step S12). The correction unit 104 corrects the parameters of the submarine cable by using the acquired temperature data and location information of the location where the temperature data was detected (step S14). The identification unit 106 uses the corrected parameters to identify the fault location in the submarine cable (step S16).

[0031] [Effect description] As described above, the fault location system 10 locates a fault using parameters corrected based on the temperature data of the submarine cable. Therefore, even if the temperature of the submarine cable changes, the fault location system 10 can correct the parameters accordingly, thereby improving the accuracy of locating a fault in the submarine cable.

[0032] The fault identification system 10 may be configured as a single computer device (information processing device), or as a distributed system having multiple computer devices. In a distributed system, the processing executed by the fault identification system 10 can be shared and executed by multiple computer devices. In other words, the fault identification system 10 may be realized by distributing the acquisition unit 102, the correction unit 104, and the identification unit 106 across two or more computer devices, and enabling the two or more computer devices to communicate with each other.

[0033] In the second embodiment described below, a specific example of the fault identification system 10 described in the first embodiment will be disclosed. However, the specific example of the fault identification system 10 described in the first embodiment is not limited to the one described below. The configuration and processing described below are merely examples, and are not limited to these.

[0034] Embodiment 2 (2A) [Configuration Description] 3 is a schematic diagram showing an example of a submarine cable communication system (hereinafter also simply referred to as a communication system) according to the present disclosure. The submarine cable communication system S is connected by a submarine cable 20 (hereinafter also simply referred to as a cable) for transmitting an optical signal (hereinafter also simply referred to as a signal). The cable 20 is laid or buried on the seabed, and is provided with repeaters 40 and branching units 50 as necessary, and each repeater 40 and branching unit 50 is equipped with a temperature sensor 30. A power feed equipment (PFE) 60 and a network monitoring system (NMS) 70 are provided at the end of the cable 20 on land.

[0035] 3, a cable 20A is provided between the PFE 60A and NMS 70A and the PFE 60B and NMS 70B. The cable 20A is provided, in order, with a repeater 40A, a branching device 50, a repeater 40B, and a repeater 40C. At the branching device 50, the cable 20A is connected to one end of a cable 20B. The other end of the cable 20B is provided with an NMS 70C, and the cable 20B is provided with a repeater 40D. Furthermore, the NMS 70C is connected to the PFE 60C and the NMS 70D via the cable 20C. The NMS 70A, the NMS 70B, and the NMS 70D are provided corresponding to the PFE 60A, the PFE 60B, and the PFE 60C, respectively. Although not shown, a PFE may also be provided corresponding to the NMS 70C.

[0036] The cable 20 has an optical fiber at its center for transmitting signals. A water-resistant layer, copper pipe, and other structures are provided to surround the optical fiber, and the structure is protected from seawater by a cover such as an insulating layer. The cable 20 may be designed to have different structures for deep water and shallow water. Examples of the cover that covers the cable 20 include, but are not limited to, double armored, single armored, light weight screen, and light weight.

[0037] The temperature sensor 30 measures the seawater temperature around the temperature sensor 30. The temperature sensor 30 then outputs the measured temperature data and its own identification information to the repeater 40 or branching device 50 to which the temperature sensor 30 is attached. Here, the temperature sensor 30 may be covered with a cover made of the same material as the cover that covers the cable 20 where the temperature sensor 30 is installed. This makes it possible to consider that the temperature measured by the temperature sensor 30 is approximately equal to the temperature inside the cable 20 where the temperature sensor 30 is installed. The temperature sensor 30 may be, for example, provided integrally with the repeater 40 or branching device 50, or may be provided as a separate device near the repeater 40 or branching device 50. Also, although FIG. 3 shows multiple temperature sensors 30 provided on the cable 20, only one temperature sensor 30 may be provided on the cable 20.

[0038] The repeater 40 is a device that repeats signals transmitted through optical fibers in the cable 20. The repeater 40 is equipped with an amplifier that amplifies signals that have been attenuated by long-distance transmission. The repeaters 40 are installed, for example, at intervals of several tens of kilometers to 100 kilometers. The repeater 40 may further include a fault point monitoring device. The branching device 50 is a device that branches the cable 20 underwater, and has the function of switching power supply paths and the function of branching or adding multiplexed optical signals.

[0039] 3, cables 20A and 20B are installed in deep water. Because cables 20A and 20B are long distances, repeaters 40 and branching devices 50 are installed to ensure communication quality. On the other hand, cable 20C is installed in shallow water, so neither repeater 40 nor branching device 50 is installed.

[0040] The repeater 40 and the branching device 50 also have the function of receiving temperature data and identification information from the temperature sensor 30 and transmitting them to the PFE 60. Fig. 4 is a block diagram showing an example of a device (hereinafter also referred to as a transfer device) that has the function of receiving and transmitting temperature data from the temperature sensor 30, as an example of the repeater 40 and the branching device 50. The transfer device 55 includes a receiving unit 552, a control unit 554, a transmitting unit 556, and a storage unit 558.

[0041] The receiving unit 552 is an interface that receives temperature data transmitted from the temperature sensor 30 attached to the transfer device 55. The receiving unit 552 can also receive a temperature data request transmitted from the PFE 60.

[0042] The control unit 554 stores the temperature data received by the receiving unit 552 in the storage unit 558. Furthermore, when the receiving unit 552 receives a temperature data request, the control unit 554 transmits the temperature data and identification information of the temperature sensor 30 stored in the storage unit 558 to the PFE 60 via the transmitting unit 556 in response to the request.

[0043] The transmitter 556 is an interface that transmits the temperature data and identification information in the form of an optical signal to the PFE 60. The memory 558 stores the temperature data received by the receiver 552 as well as a computer program executed by the controller 554. The receiver 552 and transmitter 556 transmit and receive data to and from the PFE 60 via the optical fiber of the cable 20.

[0044] The PFE 60 is a device installed on land and is also called a landing station. The PFE 60 supplies power to the amplifiers in the repeater 40 via the copper pipe (power supply cable) of the cable 20. The PFE 60 may supply power using, for example, a DC constant current method.

[0045] The PFE 60 also has the function of receiving temperature data from each repeater 40 and branching device 50 and transmitting it to the NMS 70 corresponding to the PFE 60. Figure 5 is a block diagram showing an example of the PFE 60, specializing in this function of the PFE 60. The PFE 60 includes a receiving unit 602, a converting unit 604, a reading unit 606, a transmitting unit 608, a measuring unit 610, and a storage unit 612.

[0046] The receiving unit 602 is an interface that receives the temperature data and identification information of the temperature sensor 30 transmitted from each repeater 40 and branching device 50. The receiving unit 602 can also receive a temperature data request transmitted from the NMS 70.

[0047] The conversion unit 604 converts into electrical signals the temperature data and identification information in the form of optical signals received by the receiving unit 602. The reading unit 606 reads out the temperature data and identification information from the electrical signals converted by the conversion unit 604.

[0048] The transmitting unit 608 transmits the temperature data and identification information read by the reading unit 606 to the NMS 70 together with data measured by the measuring unit 610 (described later). The transmitting unit 608 also transfers the temperature data request transmitted from the NMS 70 to each repeater 40 and branching device 50 present in the cable 20 connected to the PFE 60.

[0049] The measurement unit 610 measures the voltage value V and the current value I in the cable 20 connected to the PFE 60. For example, the measurement unit 610 detects the occurrence of a ground fault when the fluctuation value of the voltage value V becomes equal to or greater than a predetermined threshold. At this time, the measurement unit 610 outputs information on the measured current value I and voltage value V to the NMS 70 via the transmission unit 608.

[0050] The storage unit 612 stores various data received by the receiving unit 602, as well as temperature data and identification information read by the reading unit 606. The storage unit 612 also stores computer programs executed by the various units of the PFE 60.

[0051] 6 is a block diagram showing an example of the NMS 70. The NMS 70 includes a receiving unit 702, a correcting unit 704, a calculating unit 706, an identifying unit 708, an output unit 710, a transmitting unit 712, and a storage unit 714. The NMS 70 is an example of the fault identification system 10. Each element of the NMS 70 will be described below.

[0052] The receiving unit 702 receives the temperature data and identification information of each temperature sensor 30 transmitted from the PFE 60. In addition, the receiving unit 702 receives information on the current value I and voltage value V of the cable 20 when the measuring unit 610 detects the occurrence of a ground fault.

[0053] The correction unit 704 corrects the resistivity ρ of copper, which is the material of the cable 20, by using the received temperature data. The calculation formula used by the correction unit 704 is (1), and the resistivity ρ0 at the reference temperature is the one stored in the storage unit 714. The correction unit 704 outputs the corrected resistivity ρ to the calculation unit 706.

[0054] The correction unit 704, for example, refers to the received identification information of the temperature sensors 30 and map information (coordinate information) in which the position information of each temperature sensor 30 is shown in association with the identification information of the temperature sensor 30. Using the result of this reference, the correction unit 704 determines the temperature at each position on the map where the temperature sensor 30 is installed, based on the received temperature data of each temperature sensor 30. The correction unit 704 may calculate the temperature distribution between adjacent temperature sensors 30 on the cable 20, based on the temperature at the position of each temperature sensor 30 on the map. The correction unit 704 corrects the resistivity ρ using the calculated temperature distribution.

[0055] As an example, the temperature measured by the temperature sensor 30A is T A and the temperature measured by the temperature sensor 30B adjacent to the temperature sensor 30A is T B In this case, the correction unit 704 calculates the temperature distribution in the section AB between the positions of the temperature sensors 30A and 30B as the temperature T A and T B For example, the correction unit 704 may calculate the temperature in the section AB using the following formula: A +T B Alternatively, the correction unit 704 may calculate that the temperature at one end of the section AB is T A , the temperature at the other end is T B , the temperature during that time is T A and T BThe temperature of the section AB excluding the end may be expressed as, for example, T A and T B Alternatively, the correction unit 704 may take into consideration the depth of the seabed in the section AB and the like, and calculate T A and T B A function connecting the temperature distributions may be determined. The temperature distributions in the sections between other adjacent temperature sensors can be calculated in a similar manner. The correction unit 704 corrects the resistivity ρ using the calculated temperature distribution. The resistivity ρ can be expressed as a function of position, for example.

[0056] Furthermore, when there is only one temperature sensor 30 from which temperature data is to be acquired, the correction unit 704 may calculate the temperature distribution of the cable 20 in which the temperature sensor 30 is installed, using the temperature data of the temperature sensor 30. The correction unit 704 can calculate the temperature distribution based on, for example, information about the depth of the seabed in the section where the cable 20 is laid or buried.

[0057] The calculation unit 706 calculates the length L from the PFE 60 to the fault position using the resistivity ρ output by the correction unit 704, the current value I, the voltage value V, and information on the cross-sectional area S of the cable 20 stored in the memory unit 714. The calculation unit 706 uses the formula (4) to calculate the length L. The correction unit 704 outputs the calculated length L to the identification unit 708.

[0058] The identification unit 708 identifies the location (e.g., latitude and longitude) on the cable 20 where the fault has occurred by referring to the length L and map information of the cable 20 stored in the memory unit 714. The identification unit 708 outputs the identified location to a display unit connected to the NMS 70 via the output unit 710.

[0059] The output unit 710 is an interface that displays information on a display unit connected to the NMS 70. The output unit 710 may output not only the location of the fault identified by the identification unit 708 but also the temperature distribution of the cable 20 calculated by the correction unit 704 to the display unit. The output unit 710 may also output information such as the location of the fault to the user as audio.

[0060] The transmitting unit 712 transmits a temperature data request to the PFE 60 when the measuring unit 610 detects the occurrence of a ground fault.

[0061] The memory unit 714 stores, as appropriate, information on the resistivity ρ0 of the cable 20, the resistivity ρ corrected by the correction unit 704, the cross-sectional area S of the cable 20, and the length L calculated by the calculation unit 706, in addition to the various data received by the receiving unit 702. The memory unit 714 also stores, as appropriate, information such as the depth of the seabed in the section where the cable 20 is laid or buried, map information in which the position information of each temperature sensor 30 is associated with the identification information of the temperature sensor 30, and map information of the cable 20. The memory unit 714 also stores computer programs executed by each unit of the NMS 70.

[0062] [Flow description] 7 is a flowchart showing an example of a typical process of the NMS 70. This flowchart explains the process of the NMS 70. Note that the details of each process are as described above, and therefore will not be explained again as appropriate.

[0063] First, the receiving unit 702 receives temperature data and the like from each temperature sensor 30 (step S22). The correcting unit 704 corrects the resistivity ρ of the cable by using the acquired temperature data and position information from each temperature sensor 30 (step S24). The calculating unit 706 calculates the length L from the PFE 60 to the fault location by using the resistivity ρ and the like output by the correcting unit 704 (step S26). The identifying unit 708 identifies the location of the fault by referring to the length L and map information of the cable 20 stored in the memory unit 714 (step S28). The output unit 710 causes the display unit to display the location of the fault (step S30).

[0064] [Effect description] When a ground fault occurs in a submarine cable communication system, the current accuracy of locating the fault is only a few tens to 100 kilometers, meaning that on-site fault recovery work takes a certain number of days and costs money. Specifically, the estimated location of the cable fault is used as the starting point, and the cable is reeled in until the actual fault point is found. Since the cable length that can be reeled in per day is approximately 10 km, this takes several to 10 days within the above error range. Furthermore, high vessel usage fees are incurred in proportion to the time required, making the total cost of recovery very high. Given these circumstances, improvements were needed to shorten the time and reduce the costs required for fault recovery.

[0065] One possible way to improve this is to calculate the parameters of the submarine cable taking into account seawater temperature data, and then estimate the location of the fault based on that. The water temperature of the deep sea where the submarine cable is installed is said to be almost constant (about 2 to 4 degrees Celsius). However, strictly speaking, Water temperature varies depending on the location, even at the same depth. The deeper the depth, the colder the water temperature There is a temperature difference between winter and summer For these reasons, there may be a discrepancy between the estimated temperature and the actual temperature. Therefore, even if submarine cable parameters are calculated using pre-estimated temperature data and then the fault location is estimated using those parameters, there is a possibility that the difference between the estimated location and the actual fault location will be large. For example, if the total cable length is 10,000 km, the current value is 1 A, the power supply cable is made of copper wire, and formula (4) is used to calculate the length L, a discrepancy of 1°C between the estimated seawater temperature and the actual seawater temperature will result in an error of approximately 40 km.

[0066] However, in the submarine cable communication system S according to the second embodiment, the NMS 70 calculates the parameters of the submarine cable using temperature data actually measured by the temperature sensor 30, and identifies the fault location based on the calculated parameters. Therefore, compared to using temperature data estimated in advance, data closer to the actual seawater temperature can be used when identifying the fault location. This improves the accuracy of estimating the fault location. This makes it possible to shorten the time required to actually find the fault location on-site, thereby shortening the time required for fault recovery and reducing costs.

[0067] Furthermore, the correction unit 704 may use temperatures measured by temperature sensors located at different locations to calculate the temperature of the submarine cable between those temperature sensors. The correction unit 704 corrects the parameter resistivity ρ using the calculated temperature. This allows the temperature of the submarine cable between the temperature sensors to be calculated as a value closer to the actual temperature, allowing the NMS 70 to calculate a more accurate value for the resistivity ρ. Therefore, the NMS 70 can improve the accuracy of estimating the location of a fault.

[0068] Furthermore, temperature data detected by a temperature sensor may be used to identify the location of a fault, which allows the NMS 70 to improve the accuracy of estimating the location of a fault compared to when temperature data estimated indirectly is used.

[0069] Here, the temperature sensor may be provided in at least one of the repeater 40 and the branching device 50. This makes it possible to achieve the above-mentioned effects without making large-scale changes to the configuration of existing submarine cable communication systems.

[0070] Furthermore, the temperature sensor 30 may be covered with a cover made of the same material as the cover that covers the cable 20 where the temperature sensor 30 is installed. This makes it possible to consider that the temperature measured by the temperature sensor 30 is approximately equal to the temperature inside the cable 20 installed around the temperature sensor 30. This allows the NMS 70 to calculate a more accurate value for the resistivity ρ. This allows the NMS 70 to improve the accuracy of estimating the location of the fault.

[0071] Like the fault identification system 10, the NMS 70 may be configured as a single computer device, or may be configured as a distributed system having a plurality of computer devices.

[0072] Below, we will explain examples of variations of the submarine cable communication system S shown in (2A). Below, we will omit the points already explained in (2A) as appropriate and focus on the unique features of each variation. In addition, the contents described in the following variations can be used in combination as appropriate.

[0073] (2B) The cable 20 is often buried in sand on the seabed and not exposed to seawater, but may be laid on top of sand and exposed to seawater for construction or other reasons. Here, even if the seawater temperature is the same, the temperature inside the cable 20 may differ when the cable 20 is buried in sand compared to when it is laid on top of sand. Specifically, it is thought that the temperature inside the cable 20 will be higher when the cable 20 is buried in sand than when it is laid on top of sand. Therefore, it is more preferable that the correction unit 704 calculates the temperature distribution of the cable 20 taking into account such conditions of the cable 20.

[0074] The memory unit 714 stores map information indicating which sections of the cable 20 are buried in the sand and which sections are laid on top of the sand. The correction unit 704 may use the map information and temperature data at each position on the map where the temperature sensors 30 are installed to calculate the temperature distribution between adjacent temperature sensors. For example, the correction unit 704 may perform a correction by adding a predetermined value to the temperatures measured in the sections buried in the sand, and then correct the resistivity ρ using the corrected temperature data and temperature data measured in the sections laid on top of the sand. Conversely, the correction unit 704 may perform a correction by subtracting a predetermined value from the temperatures measured in the sections laid on top of the sand, and then correct the resistivity ρ using the corrected temperature data and temperature data measured in the sections buried in the sand.

[0075] In addition, if there is only one temperature sensor 30 from which temperature data is to be obtained, the correction unit 704 may calculate the temperature distribution of the cable 20 in which the temperature sensor 30 is installed using the above-mentioned map information indicating the burial or laying of the cable 20.

[0076] In this way, the correction unit 704 may correct the resistivity ρ by further using information on the exposed state of the cable 20. This allows the NMS 70 to calculate a more accurate value for the resistivity ρ, thereby improving the accuracy of estimating the fault location.

[0077] (2C) In (2A), an example has been described in which multiple temperature sensors 30 transmit temperature data to the PFE 60 via the repeater 40 or branching device 50 to which each temperature sensor 30 is attached. However, instead of each temperature sensor 30 transmitting temperature data individually, multiple temperature sensors 30 may form an ad hoc network. In this case, some of the temperature sensors 30 (one or more temperature sensors 30) that form the ad hoc network collectively transmit the temperature data measured by each temperature sensor 30 and its identification information to the repeater 40 or branching device 50. The repeater 40 or branching device 50 transmits the received information to the PFE 60 as shown in (2A).

[0078] There may be cases where one or more temperature sensors 30 are unable to transmit temperature data to the repeater 40 or branching device 50, or where the repeater 40 or branching device 50 is unable to transmit temperature data to the PFE 60. Even in such cases, by configuring the temperature sensors 30 as an ad hoc network, it becomes possible for other temperature sensors 30 to transmit the data to the PFE 60. As a result, even if a failure occurs in a device that configures the submarine cable communication system S, it is possible to calculate an accurate value for the resistivity ρ, and to maintain improved accuracy in estimating the location of the failure.

[0079] (2D) In (2A), an example has been described in which the NMS 70 acquires temperature data using the temperature sensor 30. However, the NMS 70 may acquire temperature data using fiber sensing instead of the temperature sensor 30.

[0080] For example, in Figure 3, cable 20C is installed in shallow waters, so neither repeater 40 nor branching device 50 is installed. This makes it difficult to install a temperature sensor 30 on cable 20C. Even in such a case, the NMS 70D can acquire temperature data for cable 20C by using fiber sensing, as will be described below.

[0081] First, when the measurement unit 610 of the PFE 60C detects the occurrence of a ground fault, the transmission unit 712 of the NMS 70D transmits a temperature data request to the PFE 60C. This process is as shown in (2A).

[0082] The processing of each unit of the PFE 60C will be described below. The receiving unit 602 receives the temperature data request sent from the NMS 70D. In response to the temperature data request, the transmitting unit 608 sends an optical signal for temperature measurement to the optical fiber of the cable 20C.

[0083] The sensing element shown in the first embodiment is formed at a predetermined position on the cable 20C. The receiving unit 602 receives return light from the sensing element in response to the transmitted optical signal. The measuring unit 610 analyzes the return light and detects the wavelength or reflectance of the return light to obtain the temperature at the location where the sensing element is installed.

[0084] The sensing element may be provided at one location on the cable 20C, or at multiple locations. That is, the location where the temperature is measured on the cable 20C may be one location or multiple locations. The measurement unit 610 outputs the measured temperature data together with information about the location where the temperature data was measured to the NMS 70 via the transmission unit 608. The information about the location where the temperature data was measured is location information where one or more sensing elements are provided, and is stored in the storage unit 612.

[0085] The receiving unit 702 of the NMS 70D receives the temperature data and the position information from the PFE 60C. The correcting unit 704 corrects the resistivity ρ of the cable by using the acquired information. Details of this process are as shown in (2A). Thereafter, the calculating unit 706, the identifying unit 708, and the output unit 710 also perform the same process as shown in (2A).

[0086] In this way, the NMS 70 can acquire temperature data by using fiber sensing. Therefore, even if the conditions on the seabed are not suitable for installing a temperature sensor 30, the NMS 70 can acquire temperature data that is close to the actual temperature of the cable 20. Therefore, the NMS 70 can calculate a more accurate value for the resistivity ρ, thereby improving the accuracy of estimating the location of the fault.

[0087] The NMS 70 can also use fiber sensing to acquire temperature data for a cable 20A or the like that is provided with a repeater 40 or a branching device 50. For example, one or more sensing elements may be installed in a shallow water section of the cable 20A where neither a repeater 40 nor a branching device 50 is installed. As described above, the PFE 60A acquires temperature data at locations where one or more sensing elements are installed by using fiber sensing. Then, the NMS 70A corrects the resistivity ρ and identifies the location of the fault, as described above, by using the temperature data measured by the temperature sensor 30 and the position information of the temperature sensor 30, and the temperature data measured using fiber sensing and the position information of the sensing element.

[0088] (2E) The material of the power supply cable provided in the cable 20 may be silver, nichrome, or the like, in addition to copper.

[0089] In the above-described embodiments, the present disclosure has been described as a hardware configuration, but the present disclosure is not limited to this. The present disclosure can also be realized by causing a processor in a computer to execute a computer program to perform the processing of the devices constituting the fault identification system 10, the forwarding device 55, the PFE 60, or the NMS 70 described in the above-described embodiments.

[0090] 8 is a block diagram showing an example of the hardware configuration of an information processing device (i.e., a computer) that executes the processing of the system or device described in each embodiment. Referring to FIG. 8, an information processing device 90 includes a signal processing circuit 91, a processor 92, and a memory 93.

[0091] The signal processing circuit 91 is a circuit for processing signals in accordance with the control of the processor 92. The signal processing circuit 91 may include a communication circuit for receiving signals from a transmitting device.

[0092] The processor 92 is connected to the memory 93, and performs the processing of the system described in the above embodiment by reading and executing a computer program from the memory 93. As an example of the processor 92, one of a CPU (Central Processing Unit), an MPU (Micro Processing Unit), an FPGA (Field-Programmable Gate Array), a DSP (Digital Signal Processor), and an ASIC (Application Specific Integrated Circuit) may be used, or a plurality of these may be used in parallel.

[0093] The memory 93 is configured with a volatile memory, a nonvolatile memory, or a combination thereof. The memory 93 is not limited to one, and multiple memories may be provided. The volatile memory may be, for example, a RAM (Random Access Memory) such as a DRAM (Dynamic Random Access Memory) or an SRAM (Static Random Access Memory). The nonvolatile memory may be, for example, a ROM (Read Only Memory) such as a PROM (Programmable Random Only Memory) or an EPROM (Erasable Programmable Read Only Memory), a flash memory, or an SSD (Solid State Drive).

[0094] The memory 93 is used to store one or more instructions. Here, the one or more instructions are stored as programs in the memory 93. The processor 92 can perform the processes described in the above embodiments by reading and executing these programs from the memory 93.

[0095] The memory 93 may include memory built into the processor 92 in addition to memory provided outside the processor 92. The memory 93 may also include storage located away from the processors constituting the processor 92. In this case, the processor 92 can access the memory 93 via an I / O (Input / Output) interface.

[0096] As described above, one or more processors included in each device in the above-described embodiments execute one or more programs including instructions for causing a computer to execute the algorithms described using the drawings. Execution of the programs enables the information processing described in each embodiment to be realized.

[0097] The program includes instructions or software code that, when loaded into a computer, causes the computer to perform one or more functions described in the embodiments. The program may be stored in a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, computer-readable media or tangible storage media include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disk (DVD), Blu-ray disc or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage devices. The program may also be transmitted on a transitory computer-readable medium or communication medium. By way of example and not limitation, transitory computer-readable media or communication media include electrical, optical, acoustic, or other forms of propagated signals. The transitory computer-readable medium or communication medium may provide the program to the computer via a wired communication path, such as electrical wires and optical fibers, or via a wireless communication path.

[0098] A part or all of the above-described embodiments can be described as, but not limited to, the following supplementary notes. (Appendix 1) an acquisition means for acquiring temperature data of the submarine cable; a correction means for correcting parameters of the submarine cable by using the temperature data and location information of a location where the temperature data is detected; and a fault location determination means for determining a fault location in the submarine cable using the corrected parameters. Fault Identification System. (Appendix 2) the acquiring means acquires a first temperature which is a temperature at a first position on the submarine cable and a second temperature which is a temperature at a second position on the submarine cable; the correction means corrects the parameter by calculating the temperature of the submarine cable between the first position and the second position using the first temperature and the second temperature. 1. A fault isolation system as described in Appendix 1. (Appendix 3) the correction means further uses information on the exposure state of the submarine cable to correct the parameters. 3. A fault identification system according to claim 1 or 2. (Appendix 4) Further comprising a temperature sensor provided at one or more positions on the submarine cable; the acquiring means acquires the temperature data detected by the one or more temperature sensors. A fault identification system according to any one of appendices 1 to 3. (Appendix 5) The submarine cable may further include at least one of a relay device that relays data communicated through the submarine cable and a branching device that branches the submarine cable, The one or more temperature sensors are provided in at least one of the relay device and the branching device. 10. A fault isolation system as described in Appendix 4. (Appendix 6) The submarine cable may further include at least one of a relay device that relays data communicated through the submarine cable and a branching device that branches the submarine cable, a plurality of the temperature sensors forming an ad hoc network; the acquiring means acquires the temperature data detected by the plurality of temperature sensors from the ad hoc network via at least one of the relay device and the branching device. 10. A fault isolation system as described in Appendix 4. (Appendix 7) the plurality of temperature sensors are covered with covers made of the same material as a cover covering the submarine cable at the locations where the temperature sensors are installed; A fault identification system according to any one of appendixes 4 to 6. (Appendix 8) a transmitting means for transmitting a measurement optical signal to the optical fiber of the submarine cable; a receiving means for receiving a return light of the measurement optical signal from the optical fiber, the acquiring means acquires the temperature data by analyzing the returned light. A fault identification system according to any one of appendices 1 to 3. (Appendix 9) Acquire temperature data from undersea cables, correcting parameters of the submarine cable by using the temperature data and location information of a location where the temperature data was detected; using the corrected parameters to identify the location of the fault in the submarine cable; A computer-implemented fault isolation method. (Appendix 10) Acquire temperature data from undersea cables, correcting parameters of the submarine cable by using the temperature data and location information of a location where the temperature data was detected; using the corrected parameters to identify the location of the fault in the submarine cable; A program that makes a computer do something.

[0099] Some or all of the elements (e.g., configurations and functions) described in Supplementary Notes 2 to 8 that are dependent on Supplementary Note 1 may also be dependent on Supplementary Notes 9 and 10 in the same dependency relationship as Supplementary Notes 2 to 8. Some or all of the elements described in any Supplementary Note may be applied to various hardware, software, recording means for recording software, systems, and methods.

[0100] Although the present disclosure has been described above with reference to the embodiments, the present disclosure is not limited to the above-described embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present disclosure within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate. [Explanation of symbols]

[0101] 10. Fault Identification System 102 Acquisition section 104 Correction section 106 Specification section S Submarine cable communication system 20 Cable 30 Temperature Sensor 40 Repeater 50 Branching device 55 Teleporter 552 receiving unit 554 control unit 556 transmitting unit 558 Storage section 60 Power Feed Equipment (PFE) 602 receiving unit 604 converting unit 606 reading unit 608 transmitting unit 610 measuring unit 610 storage unit 70 Network Monitoring System (NMS) 702 receiving unit 704 correction unit 706 calculation unit 708 Identification unit 710 Output unit 712 Transmission unit 714 Storage section

Claims

1. an acquisition means for acquiring temperature data of the submarine cable; a correction means for correcting parameters of the submarine cable by using the temperature data and location information of a location where the temperature data is detected; and a fault location determination means for determining a fault location in the submarine cable using the corrected parameters. Fault Identification System.

2. the acquiring means acquires a first temperature which is a temperature at a first position of the submarine cable and a second temperature which is a temperature at a second position of the submarine cable; the correction means corrects the parameter by calculating a temperature of the submarine cable between the first position and the second position using the first temperature and the second temperature. The fault isolation system according to claim 1 .

3. the correction means further uses information on the exposure state of the submarine cable to correct the parameters.

3. The fault identification system according to claim 1 or 2.

4. a temperature sensor provided at one or more positions on the submarine cable; the acquiring means acquires the temperature data detected by the one or more temperature sensors.

3. The fault identification system according to claim 1 or 2.

5. The submarine cable may further include at least one of a relay device that relays data communicated through the submarine cable and a branching device that branches the submarine cable, the one or more temperature sensors are provided in at least one of the relay device and the branching device; The fault identification system according to claim 4 .

6. The submarine cable may further include at least one of a relay device that relays data communicated through the submarine cable and a branching device that branches the submarine cable, a plurality of the temperature sensors forming an ad hoc network; the acquiring means acquires the temperature data detected by the plurality of temperature sensors from the ad hoc network via at least one of the relay device and the branching device. The fault identification system according to claim 4 .

7. the plurality of temperature sensors are covered with covers made of the same material as a cover covering the submarine cable at the locations where the temperature sensors are installed; The fault identification system according to claim 4 .

8. a transmitting means for transmitting a measurement optical signal to the optical fiber of the submarine cable; a receiving means for receiving a return light of the measurement optical signal from the optical fiber, the acquiring means acquires the temperature data by analyzing the returned light.

3. The fault identification system according to claim 1 or 2.

9. Acquire temperature data from undersea cables, correcting parameters of the submarine cable by using the temperature data and location information of a location where the temperature data was detected; using the corrected parameters to identify the location of the fault in the submarine cable; A computer-implemented fault isolation method.

10. Acquire temperature data from undersea cables, correcting parameters of the submarine cable by using the temperature data and location information of a location where the temperature data was detected; using the corrected parameters to identify the location of the fault in the submarine cable; A program that makes a computer do something.

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