Cables and cable water ingress detection devices

Abstract

To provide a cable that can accurately determine replacement timing by detecting water infiltrating into a water-shielding layer.SOLUTION: A cable in which a water-shielding layer 20f is formed on an outer peripheral side of a conductor 20a to which electric power is transmitted comprises: a heat generation part 21 which is provided inside the water-shielding layer 20f, and generates heat by water infiltrating into the water-shielding layer 20f; and an optical fiber sensor 23 which has an optical fiber 23b extending along an extension direction of the conductor 20a inside the water-shielding layer 20f, and is capable of detecting heat emitted from the heat generation part 21.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a cable installed in a place where water exists such as in the sea or on the seabed, and a water immersion detection device for the cable.

Background Art

[0002] As a conventional cable, for example, one used for transmitting electric power generated in an offshore wind power generation facility and laid in a place where water exists such as in the sea or on the seabed is known (see, for example, Patent Document 1).

[0003] A cable laid in a place where water exists forms a water blocking layer outside the conductor and the insulating layer to suppress deterioration of the insulating layer and achieve a long service life.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a cable having a water blocking layer, the water blocking layer may deteriorate and break, and water may penetrate into the insulating layer, resulting in insulation breakdown. Therefore, a cable having a water blocking layer needs to be replaced with a new cable before insulation breakdown occurs. However, in a cable having a water blocking layer, the degree of deterioration of the water blocking layer varies depending on the laying environment, and it is difficult to determine the replacement timing.

[0006] An object of the present invention is to provide a cable and a water immersion detection device for the cable that can accurately determine the replacement timing by detecting water that penetrates inside the water blocking layer.

Means for Solving the Problems

[0007] The cable according to the present invention is a cable in which a water-blocking layer is formed on the outer circumference of a conductor through which power is transmitted, and comprises a heating element provided inside the water-blocking layer and generating heat when water penetrates inside the water-blocking layer, and an optical fiber sensor having an optical fiber extending along the direction of extension of the conductor inside the water-blocking layer and capable of detecting the heat emitted from the heating element.

[0008] Furthermore, the cable according to the present invention includes a heat transfer section that extends in the circumferential direction of the conductor and transmits the heat emitted from the heat-generating section to the optical fiber sensor.

[0009] Furthermore, in the cable according to the present invention, the optical fiber sensors are arranged at multiple locations in the circumferential direction of the conductor.

[0010] Furthermore, the cable according to the present invention comprises an optical fiber sensor made of a thermally conductive material, a tubular member surrounding the outer circumference of the optical fiber, and a thermal conductive member housed inside the tubular member that transmits heat from the tubular member to the optical fiber.

[0011] Furthermore, the cable water intrusion detection device according to the present invention comprises the cable, a measuring unit that causes light to be incident on the optical fiber and receives scattered light scattered in the optical fiber, and a water intrusion determination unit that determines whether or not water has infiltrated the inside of the water-impermeable layer based on the results measured by the measuring unit. [Effects of the Invention]

[0012] According to the present invention, it is possible to reliably detect water intrusion into the waterproof layer, making it possible to accurately determine when to replace the cable and to efficiently manage cable maintenance. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a schematic diagram of a cable and a cable water ingress detection device according to one embodiment of the present invention. [Figure 2]FIG. 2 is a cross-sectional view of a cable according to an embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view of a power line according to an embodiment of the present invention. [Figure 4] FIG. 4 is a diagram for explaining a heat transfer part according to an embodiment of the present invention. [Figure 5] FIG. 5 is a cross-sectional view of an optical fiber sensor according to an embodiment of the present invention. [Figure 6] FIG. 6 is a cross-sectional view of a power line showing another arrangement of a heat generation part and a heat transfer part of the present invention.

Mode for Carrying Out the Invention

[0014] Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to the following embodiments, and includes all aspects included in the concept of the present disclosure and the scope of the claims, and can be variously modified within the scope of the present disclosure.

[0015] FIGS. 1 to 5 show an embodiment of the present invention. FIG. 1 is a schematic view of a cable and a cable immersion detection device, FIG. 2 is a cross-sectional view of the cable, FIG. 3 is a cross-sectional view of a power line, FIG. 4 is a diagram for explaining a heat transfer part, and FIG. 5 is a cross-sectional view of an optical fiber sensor.

[0016] The cable 10 and the cable immersion detection device 100 of the present embodiment are used, for example, as shown in FIG. 1, for transmitting the power generated in the floating offshore wind power generation facility 1 to a substation (not shown) on land.

[0017] The floating offshore wind power generation facility 1 is floating on the sea surface and is moored to the seabed by a chain (not shown).

[0018] The cable 10 has a submarine cable 10a laid along the seabed and a dynamic cable 10b connecting the floating offshore wind power generation facility 1 and the submarine cable 10a.

[0019] The submarine cable 10a is, for example, connected at one end to the substation equipment and at the other end to one end of the dynamic cable 10b via the connection part 10c.

[0020] One end of the dynamic cable 10b is connected to the other end of the submarine cable 10a via the connection part 10c, and the other end is connected to the floating offshore wind power generation facility 1. The dynamic cable 10b has a buoy 10d supported on the seabed by a wire and a weight (not shown) attached to an intermediate part in the extending direction, and is configured to change its posture in accordance with the behavior of the floating offshore wind power generation facility 1.

[0021] Also, as shown in FIG. 2, the cable 10 (submarine cable 10a and dynamic cable 10b) is provided on the central part side in the radial direction with three twisted power lines 20, two communication lines 30, and an interlayer 11 intervening therebetween. On the outer peripheral side of the three power lines 20, two communication lines 30, and the interlayer 11, a bedding layer 12, a wire armor 13, and an outer sheath 14 are formed in order from the inner peripheral side.

[0022] As shown in FIG. 3, the power line 20 has, in order from the central part side, a conductor 20a, an inner semiconductive layer 20b, an insulator 20c, an outer semiconductive layer 20d, a shielding layer 20e, a water-blocking layer 20f, and an anticorrosion layer 20g. Here, the water-blocking layer 20f is made of a metal such as stainless steel or aluminum.

[0023] Also, the power line 20 has a heat generating part 21 provided between the shielding layer 20e and the water-blocking layer 20f that absorbs water and generates heat, a heat transfer part 22 provided between the shielding layer 20e and the heat generating part 21 for transferring the heat generated from the heat generating part 21 in the circumferential direction of the power line 20, and a plurality of optical fiber sensors 23 disposed on the shielding layer 20e for detecting the heat transferred by the heat transfer part 22 in the circumferential direction of the power line 20 or the heat generated from the heat generating part 21.

[0024] The heat-generating section 21 consists of a strip-shaped member, for example, a base material made of fibers such as nonwoven fabric or resin, to which a substance such as quicklime that generates heat in reaction with moisture is applied. This strip is wound around the inside of the water-impermeable layer 20f without any gaps, extending along the entire length of the power line 20. Alternatively, the heat-generating section 21 may also be made of a strip-shaped material made of moisture-absorbing heat-generating fibers that generate heat when they absorb moisture.

[0025] The heat transfer section 22 is a strip-shaped member made of a metal with high thermal conductivity, such as a soft copper tape, and is wound around the entire length of the power line 20 in the circumferential direction. The heat transfer section 22 is wrapped so as to be in contact with all of the multiple optical fiber sensors 23, and as shown in Figure 4, it is configured to transfer the heat generated from the heat generating section 21 to the optical fiber sensors 23.

[0026] As shown in Figure 3, the multiple optical fiber sensors 23 are arranged circumferentially around the power line 20 together with the multiple wire shields 20e1 that constitute the shielding layer 20e. The multiple optical fiber sensors 23 are each spaced apart circumferentially around the power line 20. The appropriate number of optical fiber sensors 23 varies depending on the radial size of the power line 20, but it is preferable to have at least four or more.

[0027] As shown in Figure 5, each of the multiple optical fiber sensors 23 includes a thermally conductive tubular member 23a, an optical fiber 23b housed inside the tubular member 23a, and a thermal conductive member 23c housed inside the tubular member 23a for transferring heat from the tubular member 23a to the optical fiber 23b.

[0028] The tubular member 23a is made of a material with high thermal conductivity, such as stainless steel or copper.

[0029] Each of the multiple optical fibers 23b has a core, cladding, primary coating, and secondary coating, arranged from the radial center toward the outer periphery.

[0030] The heat conductive member 23c is a heat conductive grease composed of, for example, a grease made of modified silicone resin and metal particles such as copper, silver, or alumina that have high thermal conductivity.

[0031] Furthermore, the cable water ingress detection device 100 of this embodiment includes a measurement unit 40 that measures the intensity of scattered light and the time it takes for the scattered light to return to one end of each optical fiber 23b of a plurality of optical fiber sensors 23 of the power line 20 of the cable 10, and a water ingress determination unit 50 that determines whether or not water has penetrated inside the waterproof layer 20f based on the measurement results of the measurement unit 40.

[0032] The measurement unit 40 constitutes a DTS (Distributed Temperature Sensor) system by connecting the optical fiber 23b of the optical fiber sensor 23. The measurement unit 40 obtains temperature by injecting light such as laser light into one end of the optical fiber 23b and measuring the intensity of the scattered light (Raman scattered light) returning to the other end of the optical fiber 23b, and by measuring the time it takes for the scattered light to return, it obtains the location in the extending direction of the optical fiber sensor 23 where the acquired temperature is located. In this way, the measurement unit 40 can obtain the temperature distribution in the extending direction of the cable 10 using the optical fiber sensor 23.

[0033] The water ingress determination unit 50 consists of a computer or the like and determines whether or not water has infiltrated the inside of the waterproof layer 20f of the power line 20 based on the measured values ​​of the measurement unit 40. For example, the water ingress determination unit 50 determines that water ingress into the inside of the waterproof layer 20f has occurred in the cable 10 when the measurement unit 40 detects a temperature above a predetermined temperature. Alternatively, the water ingress determination unit 50 may, for example, continuously acquire the temperature distribution in the direction of extension of the cable 10 using the measurement unit 40, and determine that water ingress into the inside of the waterproof layer 20f has occurred in the cable 10 when the acquired temperature change exceeds a predetermined temperature. Furthermore, the water ingress determination unit 50 can acquire the position in the direction of extension of the cable 10 where water ingress into the waterproof layer 20f has occurred based on the temperature distribution in the direction of extension of the cable 10 acquired by the measurement unit 40.

[0034] In the cable 10 configured as described above, the dynamic cable 10b changes its orientation in accordance with the behavior of the floating offshore wind power generation facility 1. Therefore, if the dynamic cable 10b is damaged due to fatigue failure or other reasons caused by repeated changes in orientation of the dynamic cable 10b, seawater may penetrate inside the waterproof layer 20f. If seawater penetrates inside the waterproof layer 20f, the seawater will reach the heat-generating section 21 located inside the waterproof layer 20f, and heat will be generated from the part of the heat-generating section 21 that the seawater has reached. The heat generated from the part of the heat-generating section 21 that the seawater has reached will be transmitted through the heat transfer section 22 that extends in the circumferential direction of the power line 20 to the nearby optical fiber sensor 23, and then to the optical fiber 23b via the tubular member 23a and heat-conducting member 23c of the optical fiber sensor 23.

[0035] At this time, the water ingress detection device 100 measures the temperature transmitted through the optical fiber 23b in the measurement unit 40, and the water ingress determination unit 50 determines that water has entered the inside of the watertight layer 20f of the power line 20 based on the temperature measured by the measurement unit 40.

[0036] Thus, according to the cable of this embodiment, the cable 10 has a water-impermeable layer 20f formed on the outer circumference of a conductor 20a through which power is transmitted, and includes a heating element 21 provided inside the water-impermeable layer 20f and generating heat when water penetrates inside the water-impermeable layer 20f, and an optical fiber sensor 23 having an optical fiber 23b that extends along the direction of extension of the conductor 20a inside the water-impermeable layer 20f and capable of detecting the heat emitted from the heating element 21.

[0037] Furthermore, the cable water ingress detection device of this embodiment includes a cable 10, a measurement unit 40 that causes light to be incident on the optical fiber 23b and receives scattered light scattered in the optical fiber 23b, and a water ingress determination unit 50 that determines whether or not water has infiltrated the inside of the watertight layer 20f based on the results measured by the measurement unit 40.

[0038] This makes it possible to reliably detect the intrusion of seawater into the inside of the waterproof layer 20f, allowing for an accurate determination of when to replace the cable 10, and enabling efficient maintenance and management of the cable 10.

[0039] Furthermore, it is preferable that the conductor 20a is provided with a heat transfer section 22 that extends in the circumferential direction and transmits the heat emitted from the heat-generating section 21 to the optical fiber sensor 23.

[0040] This makes it possible to transmit to the optical fiber sensor 23 whether seawater penetrates the inside of the waterproof layer 20f from any position in the circumferential direction of the power line 20, thereby reducing the number of optical fiber sensors 23 that need to be installed.

[0041] Furthermore, it is preferable that the optical fiber sensors 23 are arranged at multiple locations in the circumferential direction of the conductor 20a.

[0042] This makes it possible to quickly detect the presence of seawater intrusion into the impermeable layer 20f, regardless of the location in the circumferential direction of the power line 20, enabling a rapid response.

[0043] Furthermore, it is preferable that the optical fiber sensor 23 is made of a thermally conductive material and includes a tubular member 23a surrounding the outer circumference of the optical fiber, and a thermal conductive member 23c housed inside the tubular member 23a that transfers heat from the tubular member 23a to the optical fiber 23b.

[0044] As a result, since the optical fiber 23b is housed in the tubular member 23a, damage to the optical fiber 23b can be suppressed. In addition, since the heat conductive member 23c is housed in the tubular member 23a together with the optical fiber 23b, the heat transmitted to the tubular member 23a can be reliably transferred to the optical fiber 23b.

[0045] In the above embodiment, we have shown a system for detecting seawater seeping inside the waterproof layer 20f of a submarine cable 10a laid on the seabed and a dynamic cable 10b installed in the sea, but the invention is not limited to this. As long as it detects water seeping inside the waterproof layer, the present invention can be applied, for example, to cables laid underground where groundwater exists.

[0046] Furthermore, although the above embodiment shows the heat-generating section 21 positioned between the shielding layer 20e and the water-blocking layer 20f, the invention is not limited to this configuration. The heat-generating section 21 may also be positioned between the outer semiconducting layer 20d and the shielding layer 20e, as shown in Figure 6. In this case, the heat transfer section 22 would be positioned between the heat-generating section 21 and the shielding layer 20e. [Explanation of symbols]

[0047] 10 Cables 20 Power lines 20a conductor 20f waterproof layer 21 Heat-generating part 22 Heat transfer section 23 Fiber Optic Sensor 23a Tubular member 23b Optical Fiber 23c heat conductive material 40 Measurement section 50 Flood detection section 100 Flood detection device

Claims

1. A cable in which a water-blocking layer is formed on the outer circumference of a conductor through which power is transmitted, A heating element is provided inside the waterproof layer and generates heat when water penetrates inside the waterproof layer, An optical fiber sensor having an optical fiber extending along the direction of extension of the conductor inside the water-impermeable layer, and capable of detecting heat emitted from the heat-generating part, The conductor comprises a heat transfer section that extends in the circumferential direction and transmits heat emitted from the heat-generating section to the optical fiber sensor, The optical fiber sensors are arranged at multiple locations in the circumferential direction of the conductor. The heat transfer section is a metal strip-shaped member wrapped around the conductor in the circumferential direction so as to be in contact with all of the multiple optical fiber sensors. cable.

2. The optical fiber sensor is made of a thermally conductive material and includes a tubular member surrounding the outer circumference of the optical fiber and a thermal conductive member housed inside the tubular member that transmits heat from the tubular member to the optical fiber. The cable according to claim 1.

3. A cable according to claim 1 or 2, A measuring unit that directs light into the optical fiber and receives scattered light scattered in the optical fiber, The system includes a water infiltration determination unit that determines whether or not water has penetrated inside the watertight layer based on the results measured by the measurement unit. Cable water ingress detection device.

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