Apparatus for Detecting Abnormalities in a Joint Portion of a Submarine Distribution Power Cable

Abstract

The present invention relates to a device for detecting abnormalities in the connection parts of submarine power distribution cables. By applying the technology of existing optical fibers and distributed acoustic sensing systems (DAS), it can detect abnormalities in the connection parts of 22.9kV submarine power distribution cables and, in particular, quickly and accurately identify abnormalities caused by seawater intrusion in the connection parts. The submarine power distribution cable connection part abnormality detection device according to the present invention comprises: a first and second submarine power distribution cables (1, 2) and a connection sleeve (3) that surrounds and protects the connection end of the first and second submarine power distribution cables; first and second water-expanding rings (20-1, 20-2) each installed on both sides in the longitudinal direction inside the connection sleeve, which expand due to moisture penetrating from the outside to block further moisture penetration and simultaneously pressurize the optical fiber; a distributed acoustic detection system (DAS) (30) connected to the optical fiber to detect deformation signals generated in the optical fiber by location; and a controller (40) that determines whether there is an abnormality in the connection part due to moisture penetration based on the deformation signal of the optical fiber caused by the expansion of the first and second water-expanding rings. Additionally, it includes first and second pressurizing wedges (50-1, 50-2) that pressurize the optical fiber while moving due to the expansion or movement of the first and second water-expanding rings.

Description

Technology Field

[0001] The present invention relates to an abnormality detection device for a 22.9kV class submarine power distribution cable, and more specifically, to an abnormality detection device for a submarine power distribution cable connection part that detects moisture infiltration and structural deformation occurring at the connection part of the submarine power distribution cable using optical fibers and a distributed acoustic sensing (DAS). Background Technology

[0002] Solar power generation is a technology that converts light energy into electrical energy using the photoelectric effect, and it is becoming widely adopted as an eco-friendly energy source. As solar power systems require a large surface area to install numerous solar modules, large-scale floating solar power systems utilizing idle water surfaces are being developed and deployed.

[0003] Large-scale floating solar power generation systems utilize 22.9kV submarine power distribution cables. These submarine power distribution cables are a core infrastructure required to connect onshore distribution systems with offshore facilities or to supply power to island regions, and thus require stable operation over a long period.

[0004] Submarine power distribution cables generally consist of a conductor, an insulation layer, a shielding layer, and an outer sheath, and include cable joints at regular intervals. These joints are structures designed to connect manufactured cables on-site and are sections where insulation restoration, shielding continuity, and waterproofing are performed. However, because the structure of the joints is more complex than that of the cable body and its reliability depends on the quality of construction, they are known as vulnerable sections where deterioration is highly likely to occur intensively during long-term operation.

[0005] Particularly in underwater environments, currents, seabed subsidence, impacts from ship anchors, and micro-bending and repetitive loading caused by external forces can occur. This leads to the concentration of mechanical stress at the connection points, posing a risk of insulation degradation, partial discharge, water tree formation, and insulation breakdown. Furthermore, while seawater intrusion or micro-leakage can cause electrical abnormalities within the connection points, it is difficult to visually detect external abnormalities when the equipment is buried or installed on the seabed.

[0006] Conventionally, periodic inspection methods such as insulation resistance measurement, withstand voltage testing, or partial discharge testing after a power outage have been used to check for abnormalities in submarine power cables. However, these methods have limitations, such as requiring the interruption of power supply or making it difficult to detect the early stages of localized deterioration at connection points in real time. Additionally, due to the characteristics of submarine sections, inspection and maintenance work is costly and time-consuming.

[0007] Therefore, there is a continuously increasing need for anomaly detection technology that can detect abnormalities occurring at the connection points of 22.9kV submarine power distribution cables in real-time or near-real-time during operation, and enable early response before an accident occurs.

[0008] As patent documents that confirm the background technology of the present invention, Korean Registered Patent No. 10-1091043 and Korean Published Patent No. 10-2026-0023685 confirm the connection part of a submarine cable, and Korean Published Patent No. 10-2015-0021669 and Korean Registered Patent No. 10-2693702 confirm the monitoring of a submarine cable.

[0009] Registered Patent No. 10-2693702 includes a DAS device that identifies the fault location of a submarine cable by detecting changes in the vibration of light wavelengths through the process of transmitting and receiving light through a fiber optic cable. However, it merely identifies the location where the fault has occurred in the submarine cable and cannot quickly confirm whether this location is a connection point. Of course, if the location of the connection point is confirmed first, it is possible to determine an abnormality in the connection point by comparing the location confirmed as the fault with the location of the connection point, but there is a problem in that this process is involved.

[0010] Furthermore, it only confirms the location of the submarine cable failure and cannot identify failures caused by seawater intrusion.

[0011] Furthermore, optical fibers can only identify the location of abnormalities in submarine power distribution cables and cannot prevent seawater from infiltrating at the connection points. Prior art literature

[0012] Republic of Korea Registered Patent No. 10-1091043 Republic of Korea Published Patent No. 10-2026-0023685 Republic of Korea Published Patent No. 10-2015-0021669 Republic of Korea Registered Patent No. 10-2693702 The problem to be solved

[0013] The present invention aims to solve the aforementioned problems by applying the technology of existing optical fibers and distributed acoustic sensing systems (DAS) to detect abnormalities in the connection parts of 22.9kV submarine power distribution cables, and in particular, to quickly and accurately identify abnormalities caused by seawater intrusion in the connection parts. means of solving the problem

[0014] The submarine power distribution cable connection part abnormality detection device according to the present invention comprises: an optical fiber installed along a connection sleeve that surrounds and protects the connection ends of the first and second submarine power distribution cables; first and second water-expanding rings each installed on both sides in the longitudinal direction inside the connection sleeve, which expand due to moisture penetrating from the outside to block further moisture penetration and simultaneously pressurize the optical fiber; a distributed acoustic detection system (DAS) connected to the optical fiber to detect deformation signals generated in the optical fiber by location; and a controller that determines whether there is an abnormality in the connection part due to moisture penetration based on the deformation signals of the optical fiber resulting from the expansion of the first and second water-expanding rings.

[0015] The present invention is characterized by comprising: first and second fixed guide surfaces formed on each side in the longitudinal direction of a connector connecting the first and second submarine power distribution cables, with the diameter decreasing towards the ends; and first and second pressing wedges movably installed on the first and second fixed guide surfaces, which press the optical fibers while moving along the first and second fixed guide surfaces due to the expansion or movement of the first and second water-expanding rings. Effects of the invention

[0016] The submarine power distribution cable connection part abnormality detection device according to the present invention has the following effects.

[0017] By using optical fibers and a Distributed Acoustic Sensing (DAS) system, structural deformation of 22.9kV submarine power distribution cables is detected, and abnormalities caused by moisture intrusion are also detected, thereby preventing power loss due to abnormalities in the connection parts. Furthermore, moisture intrusion inside the connection parts can be detected at an early stage, and the detection signal can be amplified through the expansion of a water-expanding ring, thus improving the reliability of the abnormality detection results in the connection parts. In particular, by utilizing the characteristics of the water-expanding ring, additional seawater intrusion can be prevented or delayed, thereby protecting the connection parts. Additionally, since abnormalities caused by seawater intrusion can be identified, the reliability as a detection device is improved, and ultimately, power loss is reduced by repairing the connection parts of the submarine power distribution cables before they break.

[0018] In addition, safe maintenance is possible by classifying abnormalities in the connection part into two stages (alarm when the water-expanding ring expands, and severe stage when the pressure wedge moves) through two-stage detection using a water-expanding ring and a pressure wedge. Brief explanation of the drawing

[0019] FIG. 1 is an installation state diagram of a submarine power distribution cable connection part abnormality detection device according to the present invention. FIG. 2 is an exploded perspective view of a submarine power distribution cable connection part abnormality detection device according to the present invention. FIG. 3 is another example of a first and second water-expanding ring applied to a submarine power distribution cable connection part abnormality detection device according to the present invention. FIG. 4 is another example of a first and second water-expanding ring applied to a submarine power distribution cable connection part abnormality detection device according to the present invention. Specific details for implementing the invention

[0020] In the following description of the present invention, specific descriptions of related known functions or configurations will be omitted if it is determined that such descriptions would unnecessarily obscure the essence of the invention. Furthermore, the terms described below are defined in consideration of their functions within the present invention, and these definitions may vary depending on the intentions or practices of the user or operator. Therefore, such definitions should be based on the content throughout this specification.

[0021] As shown in FIG. 1, the submarine power distribution cable connection part abnormality detection device according to the present invention comprises a first and second submarine power distribution cable (hereinafter abbreviated as 'first and second cables') (1, 2) and an optical fiber (10) installed along a connection sleeve (3) of a connection part that connects the connection ends of the first and second cables (1, 2); first and second water-expanding rings (20-1, 20-2) installed inside the connection sleeve (3) and along the installation path of the optical fiber (10), which expand due to water penetrating into the interior of the connection sleeve (3) from the outside; a distributed acoustic sensing (DAS) (30) connected to the optical fiber (10) and detecting deformation signals generated in the optical fiber (10) by location; and a controller (40) that detects abnormalities in the connection part based on deformation signals generated in the optical fiber (10). Additionally, first and second pressure wedges (50-1, 50-2) may be included.

[0022] The first and second cables (1,2) are, for example, connected at one end to a floating solar cell (100) and a floating substation (200), and at the other end electrically connected through a connector (4) as a connection end and protected through a connection sleeve (3), and are not limited to being connected through various known connection structures as shown in the drawing (including a protective tube that wraps the first and second cables (1,2) and the optical fiber (10), etc.).

[0023] The optical fiber (10) is formed as a single continuous structure and is continuously connected from the first cable (1) through the inside of the connection sleeve (3) to the second cable (2) without cutting.

[0024] It is preferable that the optical fiber (10) be placed in an annular space formed between the inner surface of the connection sleeve (3) and the outer surface of the connector (4), and in particular, be continuously placed along the section between the first water expansion ring (20-1) and the second water expansion ring (20-2), and be in contact with the first water expansion ring (20-1) and the second water expansion ring (20-2) so that when the first water expansion ring (20-1) and the second water expansion ring (20-2) expand, the optical fiber is compressed by the first water expansion ring (20-1) and the second water expansion ring (20-2).

[0025] The optical fiber (10) can be fixed to a fixed support formed inside the connection sleeve (3), and can also be inserted into the first and second wiring grooves (21-1, 21-2) formed in the first water expansion ring (20-1) and the second water expansion ring (20-2).

[0026] The DAS (30) includes, for example, a light source unit that generates laser light and injects it into the optical fiber (10) in the form of pulses, a receiver unit that receives a scattered signal generated inside the optical fiber (10) in a backscattering manner, an interference analysis unit that analyzes the scattered signal according to the time-of-flight and calculates a phase shift at each position along the length of the optical fiber (10), and a strain calculation unit that converts the phase shift into a strain change to quantify the mechanical deformation occurring at a specific position on the optical fiber (10).

[0027] The controller (40) analyzes the deformation signal received from the DAS (30) to determine whether there is an abnormality in the connection part, and although it can be included in the DAS (30), it is separated as an independent component for the sake of understanding and performs the following functions.

[0028] The optical fiber (10) length coordinates corresponding to the connection sleeve (3) section can be stored in advance, and only the signals occurring in that section can be selectively analyzed (at this time, deformation outside the connection sleeve (3) section is determined by the DAS (30)). That is, if the position of the connection sleeve (3) is stored in advance using the lengths of the first and second cables (1,2), an abnormality in the connection part is quickly determined.

[0029] The first and second water-expanding rings (20-1, 20-2) expand to apply a gradual compressive force to the optical fiber (10), and a signal is generated in which the strain in the optical fiber (10) gradually increases, which is determined to be an abnormality caused by moisture penetration.

[0030] In addition, when the first and second pressure wedges (50-1, 50-2) are applied, the first and second pressure wedges (50-1, 50-2) move and compress the optical fiber (10), and based on the deformation occurring in the optical fiber (10), the level of moisture penetration is determined to be severe.

[0031] Since seawater will gradually infiltrate, the deformation signal generated by the expansion of the first and second water expansion rings (20-1, 20-2) has a gradual increase over time, and the deformation signal caused by external mechanical impact has a rapid change, so the controller (40) can distinguish the cause of the abnormality based on the time change rate and location of occurrence of the signal.

[0032] While the first and second cables (1,2) receive tensile or compressive force mainly along the wiring direction (axial direction) underwater and do not receive compressive force (radial compressive force) directed inward from the periphery, the optical fiber (10) at the connection part receives radial compressive force through the first and second water-expanding rings (20-1, 20-2) and the first and second pressure wedges (50-1, 50-2), so an abnormality at the connection part can be distinguished from an abnormality at other places.

[0033] The controller (40) can be configured to determine the moisture penetration status more precisely through comparison with a pre-established database.

[0034] Specifically, an expansion experiment is performed on the first and second water-expanding rings (20-1, 20-2) while varying the amount of water penetration in stages, and the strain value, the rate of change of strain, and the deformation pattern over time detected in the optical fiber (10) corresponding to each amount of penetration are measured and stored in a database.

[0035] The above database may include absolute strain values ​​according to moisture penetration amount, strain increase curves over time, patterns of rapid deformation change at the critical expansion point, and deformation distribution characteristics by location in the connection sleeve section.

[0036] When a deformation signal is detected through the optical fiber (10) at the site, the controller (40) compares and analyzes the magnitude, rate of change, and temporal pattern of the deformation signal with reference data stored in the database.

[0037] The controller (40) extracts the most similar reference data through pattern similarity, error range, or correlation coefficient analysis, and estimates the degree of expansion and moisture penetration of the corresponding water expansion ring.

[0038] This allows for the quantitative determination of the progression stage and risk level of moisture that has penetrated into the connection part, going beyond simply determining the presence or absence of abnormalities.

[0039] The first and second water-expanding rings (20-1, 20-2) have the same configuration and are applied symmetrically with respect to the connector (4). Their positions are at both ends in the longitudinal direction of the connection sleeve (3) (where there is a high possibility of moisture penetration). They are ring structures provided with holes through which the first and second cables (1, 2) pass, and preferably include first and second wiring grooves (21-1, 21-2) into which the optical fiber (10) is inserted and wired.

[0040] The first and second wiring grooves (21-1, 21-2) are groove structures that are open to the outside at the edges of the first and second water expansion rings (20-1, 20-2), and of course, a structure of a hole that is open only to the left and right with respect to FIG. 1 and has a closed perimeter is also possible.

[0041] The first and second wiring grooves (21-1, 21-2) may also have a structure larger than a semicircle, and in this case, sensitivity can be amplified by compressing a large portion of the circumference of the optical fiber (10) while preventing the optical fiber (10) from slipping out.

[0042] The first and second water-expanding rings (20-1, 20-2) of such a structure are inserted into the interior of the connection sleeve (3) and are isolated from the outside, that is, are not in contact with seawater. When seawater flows in due to damage to the connection sleeve (3), they expand, and through this expansion, the optical fiber (10) is compressed.

[0043] The first and second pressure wedges (50-1, 50-2) are installed on the inside (to the connector (4) side) of the first and second water-expanding rings (20-1, 20-2), and move when the first and second water-expanding rings (20-1, 20-2) are pushed inward due to the expansion of the first and second water-expanding rings (20-1, 20-2) or due to the water pressure of seawater, and the direction of movement is toward the inner surface of the connection sleeve (3) that is orthogonal to the axial direction, i.e., toward the optical fiber (10).

[0044] Therefore, under normal circumstances, the first and second pressure wedges (50-1, 50-2) do not compress the optical fiber (10), but compress the optical fiber (10) as they move when seawater infiltrates.

[0045] An inclined guide section must be included for the movement of the first and second pressure wedges (50-1, 50-2), and for example, first and second fixed guide surfaces (51-1, 51-2) are formed on both sides in the longitudinal direction of the connector (4) to support the first and second pressure wedges (50-1, 50-2) so as to be movable.

[0046] The first and second pressure wedges (50-1, 50-2) can be, for example, in a form where three or more wedge pieces are arranged in a ring shape and connected by a rubber ring.

[0047] The method for detecting abnormalities in the connection portion of a submarine power distribution cable according to the present invention is as follows.

[0048] 1. Normal state.

[0049] In normal conditions, the first and second cables (1, 2) are electrically connected by a connector (4), and the connector (4) is protected from the outside by a connection sleeve (3).

[0050] At this time, the first and second water-expanding rings (20-1, 20-2) are not in contact with moisture and no expansion occurs, and the first and second pressure wedges (50-1, 50-2) maintain their initial positions.

[0051] Accordingly, the optical fiber (10) maintains a reference state in which no tension or compression is applied in the internal annular space of the connection sleeve (3).

[0052] The DAS (30) injects a laser pulse along the optical fiber (10) and receives a backscattered signal to set a reference strain value at the position of the optical fiber (10) corresponding to the connection sleeve (3) section.

[0053] The controller (40) determines the normal state when the deformation signal of the connection sleeve (3) section is within a preset reference range.

[0054] 2. Connection defects (moisture penetration).

[0055] In the event that seawater penetrates into the connection sleeve (3) along the surface of the first and second cables (1,2) or penetrates into the connection sleeve (3) due to damage to the connection sleeve (3),

[0056] a. Expansion action of the first and second water-expanding rings (20-1, 20-2)

[0057] When the penetrated moisture comes into contact with the first and second water-expanding rings (20-1, 20-2), the first and second water-expanding rings (20-1, 20-2) absorb the moisture and expand.

[0058] The first and second water-expansion rings (20-1, 20-2) apply pressure to the optical fiber (10) through their expansion force.

[0059] At this time, gradual compressive deformation occurs in the optical fiber (10), and the DAS (30) detects a signal in which the strain gradually increases.

[0060] Based on this, the controller (40) determines that an abnormality has occurred in the connection part of the first and second cables (1,2), and in particular, determines that the abnormality is caused by the intrusion of seawater.

[0061] b. Movement of the first and second pressure wedges (50-1, 50-2).

[0062] In a state where the first and second pressure wedges (50-1, 50-2) are moving (where the first and second pressure wedges (50-1, 50-2) are pushed by the expansion of the first and second water-expanding rings (20-1, 20-2), or where the first and second pressure wedges (50-1, 50-2) are pushed inward by the infiltration of seawater), the first and second pressure wedges (50-1, 50-2) move along the first and second fixed guide surfaces (51-1, 51-2), that is, move toward the optical fiber (10) and compress the optical fiber (10).

[0063] As a result, an increase in strain or a sudden change in amplitude occurs in the optical fiber (10), and the DAS (30) detects a sudden deformation signal at that location, and the controller (40) determines that the first and second pressure wedges (50-1, 50-2) have moved, that is, that is, that a significant amount of seawater has penetrated into the connection part, and determines that the connection part abnormality has worsened.

[0064] Meanwhile, the controller (40) can store optical fiber length coordinates corresponding to the location where the connection sleeve (3) is installed in advance, and when the DAS (30) detects a deformation signal at a specific location in the optical fiber length direction, the controller (40) compares the location coordinates with the stored connection sleeve location coordinates, and if the detected deformation location is within a preset tolerance range with the stored connection sleeve location, it determines that this is an abnormality that occurred in the connection part, whereas if deformation occurs at a location outside the tolerance range, it determines that it is an external impact or an abnormality in another section.

[0065] FIG. 3 is an example in which the connection relationship between the first and second water expansion rings (20-1, 20-2) and the optical fiber (10) is different so that the location of the connection part can be accurately determined.

[0066] The first and second water-expanding rings (20-1, 20-2) have first and second coil-shaped wiring grooves (22-1, 22-2) formed on their periphery with a constant pitch and a constant depth (semicircle or more than a semicircle), and the optical fiber (10) is wound in the first and second wiring grooves (22-1, 22-2) in a coil shape.

[0067] According to this structure, when the first and second water-expansion rings (20-1, 20-2) expand in the radial direction, an increase in the length of the optical fiber (10) occurs simultaneously. Therefore, a deformation value different from when the optical fiber (10) is arranged in a straight line in the general section (the section other than the connection part) occurs, and a deformation value larger than the number of windings of the optical fiber (10) occurs (sensitivity amplification), so an abnormality in the connection part can not be confused with other sections.

[0068] FIG. 4 illustrates a configuration for intensively expanding the first and second water-expanding rings (20-1, 20-2) toward the optical fiber (10), and a first and second cover (23-1, 23-2) is installed on the outer diameter side of the first and second water-expanding rings (20-1, 20-2) to induce expansion.

[0069] The first and second covers (23-1, 23-2) are formed of a material having a lower expansion (tensile) coefficient than the first and second water-expanding rings (20-1, 20-2), such as steel or a high-rigidity metal, and are installed to wrap around most of the circumference of the water-expanding rings.

[0070] However, the cover is not formed or an opening is formed in the first and second wiring grooves (21-1, 21-2) where the optical fiber (10) is inserted and arranged, so that the wiring groove area is configured to be relatively less constrained.

[0071] Accordingly, when the first and second water-expanding rings (20-1, 20-2) expand in volume due to moisture penetration, radial deformation is restricted in the area constrained by the cover, and expansion deformation is concentrated in the direction of the wiring groove, where there is relatively less constraint.

[0072] As a result, the optical fiber (10) receives a larger circumferential tensile strain due to radial expansion concentrated in the direction of the first and second wiring grooves (21-1, 21-2), and the strain sensitivity is amplified accordingly.

[0073] Additionally, a separate inner cover may be further formed on the inner surface of the first and second water-expanding rings (20-1, 20-2), and the inner cover may be configured to prevent compression or damage to the cables by limiting the transmission of expansion deformation in the direction of the first and second cables (1, 2). Explanation of the symbols

[0074] 1,2 : 1st and 2nd submarine power distribution cables, 3: Connection sleeve, 4: Connector 10: Optical fiber, 20-1,20-2: 1st,2nd water expansion ring 21-1,21-2 : 1st and 2nd wiring grooves, 30: Distributed Acoustic Sensing System (DAS), 40: Controller, 50-1, 50-2: 1st, 2nd pressure type wedge 51-1,51-2 : 1st and 2nd fixed guide surfaces,

Claims

Claim 1 An optical fiber installed along a connection sleeve that encloses and protects the connection ends of the first and second submarine power distribution cables; first and second water-expanding rings, each installed on both longitudinal sides inside the connection sleeve and expanding due to moisture penetrating from the outside; first and second fixed guide surfaces, each formed on both longitudinal sides of a connector connecting the first and second submarine power distribution cables and having a slanted shape with a diameter decreasing towards the ends; first and second pressure wedges, disposed between the first and second water-expanding rings and the connector and movably installed on the first and second fixed guide surfaces, which pressurize the optical fiber while moving along the first and second fixed guide surfaces due to the expansion of the first and second water-expanding rings; and a distributed acoustic sensing system (DAS) connected to the optical fiber to detect deformation signals generated in the optical fiber at specific locations. A submarine power distribution cable connection part abnormality detection device characterized by including a controller that receives a deformation signal of an optical fiber from the above distributed acoustic sensing system (DAS) and determines whether there is an abnormality in the connection part due to the expansion of the first and second water-expanding rings. Claim 2 delete Claim 3 A submarine power distribution cable connection part abnormality detection device according to claim 1, wherein the first and second water-expanding rings include first and second wiring grooves formed in a coil shape on the outer surface, and the optical fiber is wound in a coil shape through the first and second wiring grooves. Claim 4 A submarine power distribution cable connection part abnormality detection device according to claim 1, wherein a first and second cover are further coupled to the outer surface of each of the first and second water-expanding rings, and the first and second covers are formed of a material having a smaller expansion coefficient than the first and second water-expanding rings and are configured to surround the area of ​​the outer surface of the first and second water-expanding rings excluding the wiring groove area where an optical fiber is inserted and disposed, and when the first and second water-expanding rings expand due to moisture absorption, radial expansion is restricted in the area constrained by the first and second covers, and expansion deformation is concentrated in the direction of the wiring groove area.

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