Cable connection method, mobile body, and connection body

Abstract

In this cable connection method, the conductors of a first cable and a second cable which are connected in series to an offshore wind power generation facility and transmit power are detached from the offshore wind power generation facility, the removed conductor end sections are waterproofed and stored in a mobile body for each of the first cable and the second cable, the mobile body is suspended from the offshore wind power generation facility by a wire rope and stopped in the sea, and the mobile body stopped in the sea is pulled up to a work ship. The mobile body pulled up by the work ship is disassembled, the conductor end section of the first cable and the conductor end section of the second cable stored in the mobile body are connected to each other, a connection body having a sealed protective body for storing the connected conductor end sections is assembled, and the connection body is lowered to the sea floor.

Description

Cable connection method, mobile body and connection body

[0001] The present invention relates to a cable connection method, a moving body, and a connecting body.

[0002] Patent Literature 1 (PTL 1) discloses a connection system for offshore wind farms. This connection system is used in a series-connected wind farm and includes an I-pipe for connecting and disconnecting array cables connecting floating wind power plants that make up the wind farm. Two array cables for connecting adjacent wind power plants are connected at their tops in this I-pipe. When the I-pipe is attached to the wind power plant, the two array cables are connected to cables connected to the wind power plant's switchgear. Furthermore, when the I-pipe is to be maintained at the wind power plant, it is detached from the wind power plant and floats on the sea, disconnecting the array cables from the cables connected to the wind power plant's switchgear. Because the two array cables are connected to a connection box inside the floating I-pipe, power can still be supplied from the offshore wind farm via the I-pipe, even if the wind power plant is detached from the array cables for maintenance.

[0003] Patent No. 6715850

[0004] In the system disclosed in Patent Document 1, the I-pipe is connected to the wind power generation facility with a portion exposed above sea level. Therefore, it is subjected to loads due to the effects of wind, swells, waves, wind and rain, ocean currents, and the like. Furthermore, when detached from the wind power generation facility, it floats on the sea, but because it is not moored by mooring lines, it moves due to the effects of wind, swells, waves, ocean currents, and the like, which could damage the array cable. Furthermore, when the I-pipe floats on the sea, marine organisms may attach to it or come into contact with it.

[0005] The present invention has been made in consideration of the above, and aims to reduce the load on the cable, maintain the series connection, and continue power transmission even if a wind power generation facility is removed from the series-connected cable.

[0006] In order to solve the above-mentioned problems and achieve the object, a cable connection method according to the present invention includes the steps of: removing, from an offshore wind power generation facility, conductors of a first cable and a second cable that are connected in series to the offshore wind power generation facility to transmit power; providing a first protection part that has a waterproofing part that waterproofs a conductor end of the removed first cable and protects the conductor end; fixing the first protection part to a retaining part that fastens the first cable to the offshore wind power generation facility, assembling a mobile body; providing a second protection part that has a waterproofing part that waterproofs a conductor end of the removed second cable and protects the conductor end; and fixing the second protection part to a retaining part that fastens the second cable to the offshore wind power generation facility. a step of assembling a mobile body by suspending the mobile body from the offshore wind power facility with a wire rope and anchoring it in the sea; a step of lifting the mobile body anchored in the sea onto a work vessel; a step of dismantling the mobile body that has been anchored on the work vessel; a step of connecting the conductor end of the first cable and the conductor end of the second cable that were stored in the mobile body; a step of assembling a connecting body having an enclosed protective body that houses the connected conductor end; a step of fixing the protective body to the retaining portion of the first cable and the protective body to the retaining portion of the second cable using a connector; and a step of lowering the connecting body to the seabed.

[0007] In one aspect of the cable connection method of the present invention, the first cable and the second cable may include optical cables, and in the mobile body, the ends of the optical cables may be waterproofed and stored in the first protective section and the second protective section, and in the connection body, the optical cable of the first cable and the optical cable of the second cable may be connected and stored in the protective section.

[0008] In the cable connection method according to one aspect of the present invention, the first cable and the second cable may each have a plurality of core wires.

[0009] In the cable connection method according to one aspect of the present invention, the step of waterproofing the conductor end may be configured to waterproof the conductor end for each of the plurality of core wires.

[0010] In a cable connection method according to one aspect of the present invention, the offshore wind power generation facility may have a riser pipe through which the first cable is passed from underwater into a hollow portion thereof, and a riser pipe through which the second cable is passed from underwater into a hollow portion thereof, and the moving body may be able to pass through the riser pipe.

[0011] In one aspect of the cable connection method of the present invention, the step of hoisting the moving body onto a work vessel may involve reconnecting the moving body, which is suspended by a wire rope of the offshore wind power generation facility and stopped in the sea, to the wire rope of the work vessel, and hoisting the moving body onto the work vessel using the wire rope of the work vessel.

[0012] In the cable connection method according to one aspect of the present invention, the protection section may be configured so that seawater can enter inside the protection section when in the sea.

[0013] In one aspect of the cable connection method of the present invention, the distance between the protective body and the retaining portion of the first cable and the distance between the protective body and the retaining portion of the second cable may be adjusted using the connecting device.

[0014] In a cable connection method according to one aspect of the present invention, the connector may be a stud bolt, and the distance between the protective body and the retaining portion of the first cable and the distance between the protective body and the retaining portion of the second cable may be individually adjusted by the stud bolt.

[0015] In a cable connection method according to one aspect of the present invention, the conductor end housed in the protective body may be fixed inside the protective body, and the part that fixes the conductor end may be non-magnetic.

[0016] In a cable connection method according to one aspect of the present invention, the conductor ends of the first cable and the second cable may be stored inside the protective body through holes provided in the protective body, and the holes through which the first cable and the second cable are passed may be waterproofed.

[0017] A mobile body according to one aspect of the present invention comprises a waterproofing section that waterproofs the conductor end of a cable that is connected in series to an offshore wind power generation facility to transmit electricity, a protective section that protects the conductor end and is fixed to a retaining section that fastens it to the offshore wind power generation facility, and a sling to which a rope that suspends the protective section is tied.

[0018] In the moving body according to one aspect of the present invention, the protection section may be configured to be in the sea and to allow seawater to flow in.

[0019] A connector according to one embodiment of the present invention comprises a connection part that connects the conductor ends of a first cable and a second cable that are connected in series to an offshore wind power generation facility to transmit electric power, an enclosed protective body that houses the connection part, a retaining part that secures the protective body and the first cable to the offshore wind power generation facility, and a coupling that secures the protective body and the retaining part that secures the second cable to the offshore wind power generation facility.

[0020] In one embodiment of the connection body of the present invention, the coupling device may be configured to adjust the distance between the protective body and the retaining portion of the first cable and the distance between the protective body and the retaining portion of the second cable.

[0021] In the connector according to one aspect of the present invention, the two retaining portions may be integrally fixed to the protective body.

[0022] In the connector according to one aspect of the present invention, the two retaining portions may be configured to be fixed to the protective body individually and independently.

[0023] In the connection body according to one aspect of the present invention, the protective body may have a position adjusting and fixing portion that adjusts and fixes the positions of the first and second cables within a sealed interior.

[0024] According to the present invention, even if a wind power generation facility is disconnected from a series-connected cable, the load on the cable can be reduced, the series connection can be maintained, and power transmission can be continued.

[0025] FIG. 1 is a schematic diagram of a series-connected wind farm. FIG. 2 is an external view of an offshore platform. FIG. 3A is a cross-sectional view of an array cable. FIG. 3B is a cross-sectional view of an array cable. FIG. 4 is a schematic diagram of the vicinity of the tower of the offshore platform. FIG. 5 is a side view of a floating body. FIG. 6 is a schematic diagram of the interior of a junction box. FIG. 7A is a view showing an open power cable junction box. FIG. 7B is a side view of a direct equipment connection terminal housed in the power cable junction box. FIG. 8 is a diagram showing the structure of a direct equipment connection terminal. FIG. 9A is a half-side cross-sectional view of a detent section. FIG. 9B is a half-side cross-sectional view of another example of a detent section. FIG. 9C is a half-side cross-sectional view of a detent section when the array cable is the array cable shown in FIG. 3B. FIG. 9D is a half-side cross-sectional view of yet another example of a detent section when the array cable is the array cable shown in FIG. 3B. FIG. 10 is a flowchart showing the process of hoisting an array cable onto a work vessel. FIG. 11 is a schematic diagram showing the inside of the junction box before the array cable is removed. FIG. 12 is a schematic diagram showing the state after the power lines and optical cables have been removed. FIG. 13 is a schematic diagram showing the state after waterproofing of the power lines and optical cables has been performed. FIG. 14 is a schematic diagram of a half cross section of the waterproofing treatment section. FIG. 15 is a schematic diagram showing the state after the retention section has been lifted. FIG. 16 is a schematic diagram showing the state after the movable termination has been assembled. FIG. 17A is a half cross section of the movable termination. FIG. 17B is a half cross section of another example of the movable termination. FIG. 17C is a half cross section of yet another example of the movable termination. FIG. 18 is a schematic diagram showing the suspended movable termination. FIG. 19 is a schematic diagram showing the operation of removing the bend stiffener. FIG. 20 is a schematic diagram showing the mobile termination being lowered. FIG. 21 is a schematic diagram showing the mobile termination moved into the sea. Fig. 22 is a schematic diagram showing the wire rope of the work vessel connected to the movable termination. Fig. 23 is a schematic diagram showing the movable termination being pulled to the work vessel. Fig. 24 is a schematic diagram showing the operation of hoisting the movable termination onto the work vessel. Fig. 25 is a schematic diagram showing the movable termination hoisted onto the work vessel.FIG. 26 is a flowchart showing the process flow for connecting array cables in series. FIG. 27 is a schematic diagram showing a mobile termination hoisted onto a work vessel. FIG. 28 is a schematic diagram showing the state in which the protective tube has been removed from the fastening section. FIG. 29 is a schematic diagram showing the state in which the waterproof section has been dismantled and the waterproof tube has been removed. FIG. 30 is a diagram showing the configuration of an energized termination. FIG. 31A is a plan view of a bottom plate. FIG. 31B is a plan view of another example of a bottom plate. FIG. 32 is a schematic diagram showing the assembly process for an energized termination. FIG. 33 is a schematic diagram showing the state in which power lines and optical cables have been connected. FIG. 34 is a schematic diagram showing a fixed device direct connection terminal, power lines, and optical cables. FIG. 35 is a schematic diagram showing a waterproofing treatment section. FIG. 36 is a schematic diagram showing the state in which the bottom plate and fastening section are connected with stud bolts. FIG. 37 is a schematic diagram showing the state in which a protective body is attached to the bottom plate. FIG. 38 is a schematic diagram showing a state in which a lid is attached to a protective body. FIG. 39 is a flowchart showing the process flow for lowering a live termination to the seabed. FIG. 40 is a schematic diagram showing the process for lowering a live termination to the seabed. FIG. 41 is a schematic diagram showing the process for lowering a live termination to the seabed. FIG. 42 is a schematic diagram showing the process for lowering a live termination to the seabed. FIG. 43 is a flowchart showing the process flow for connecting an array cable to an offshore platform after its maintenance is completed. FIG. 44 is a diagram showing a modified example of the clamp portion of the movable termination. FIG. 45A is a diagram showing a modified example of attaching a stud bolt. FIG. 45B is a diagram showing a modified example of attaching a stud bolt. FIG. 46A is a diagram showing an example in which a connector includes a perforated angle. FIG. 46B is a diagram showing an example in which a connector includes a perforated angle.

[0026] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to the embodiments described below. In addition, in the description of the drawings, the same or corresponding elements are appropriately designated by the same reference numerals. Furthermore, it should be noted that the drawings are schematic, and the dimensional relationships between the elements may differ from the actual ones. There may also be parts in which the dimensional relationships and ratios between the elements differ from one another.

[0027] 1 is a schematic diagram of a series-connected wind farm WF that generates wind power offshore. The wind farm WF according to this embodiment is a wind farm in which a plurality of offshore platforms 1 equipped with generators are connected in series by array cables 2. Electric power generated on the offshore platforms 1, which are an example of an offshore wind power generation facility, is transmitted to a substation via the array cables 2 that transmit the power.

[0028] FIG. 2 is an external view of the offshore platform 1. The offshore platform 1 is a tension-moored platform known as a TLP (Tension Leg Platform). The offshore platform 1 includes a float 11, a tower 12, a nacelle 13, a rotor 14, blades 14a, a tendon 15, and a foundation 16. The offshore platform 1 is moored by connecting the semi-submerged float 11 and the foundation 16 installed on the seabed via the tendon 15, utilizing tension generated by buoyancy. The nacelle 13 is provided on top of the tower 12 attached to the float 11. A yaw drive device is provided at the joint between the nacelle 13 and the tower 12, rotating the nacelle 13 around the central axis of the tower 12 in accordance with the wind direction. The nacelle 13 supports a main shaft (not shown), to which a rotor 14 having blades 14a is attached. A generator (not shown) is housed within the nacelle 13, and the main shaft of the rotor 14 is connected to the rotating shaft of the generator via a gearbox. Also installed within the nacelle 13 are power equipment for supplying the power generated by the generator to the array cable 2, a wind direction and anemometer, and a computer device for communicating with a land-based monitoring device that monitors the offshore platform 1.

[0029] 3A is a cross-sectional view perpendicular to the longitudinal direction of the array cable 2. The array cable 2 mainly comprises a power line unit 210 and a covering 227 surrounding the power line unit 210. The power line unit 210 is a three-core power cable formed by twisting together three power lines 203. The power line unit 210 may comprise a plurality of power lines 203 (cores), such as two or four or more, or may have a single-core configuration consisting of a single power line 203. The power line 203 comprises, from the center, a conductor 207, an inner semiconductive layer 209 disposed on the outer periphery of the conductor 207, an insulating layer 211 disposed on the outer periphery of the inner semiconductive layer 209, an outer semiconductive layer 213 disposed on the outer periphery of the insulating layer 211, a metal sheath 215 disposed on the outer periphery of the outer semiconductive layer 213, and an inner sheath 217 disposed on the outer periphery of the metal sheath 215.

[0030] The covering 227 includes a pressure tape 221, an iron wire armor 223 made of iron wire, and an outer sheath 225. The configurations of the power line 203 and the covering 227 are not limited to the example shown in the figure, and some of the components shown may be omitted, or other components may be added. For example, the power line 203 may be configured such that at least the conductor 207 is covered with an insulator (including the inner semiconductive layer 209, the insulating layer 211, and the outer semiconductive layer 213).

[0031] A spacer member 229 is disposed in the gap formed between the power line unit 210 and the covering 227. The spacer member 229 is a member formed, for example, by extrusion molding a resin. The spacer member 229 may be disposed in one location as shown in FIG. 3A , but this is not limited to the example shown in FIG. 3A . The spacer member 229 may be disposed in three locations, one between each of the three power lines 203. The portions of the gap formed between the power line unit 210 and the covering 227 where the spacer member 229 is not disposed may be left empty without any other member disposed therein. For example, an intervening member made of polypropylene string may be disposed to fill the gap. An optical cable 205 having an optical fiber is disposed in the gap formed by the spacer member 229. The optical cable 205 is waterproofed by, for example, a stainless steel metal tube. The optical cable 205 and the metal tube may be stored in the gap between the spacer member 229 and the power line unit 210, or the gap between the pressure tape 221 and the power line unit 210 may be filled with a filler made of resin fibers such as polyethylene, and the optical cable 205 and the metal tube may be stored in the filler.

[0032] The array cable connecting the offshore platforms 1 in series may be an array cable 2' shown in FIG. 3B. The array cable 2' comprises a power line unit 210 and a covering 227A surrounding the power line unit 210. FIG. 3B is a cross-sectional view perpendicular to the longitudinal direction of the array cable 2'. The array cable 2' does not comprise a spacer member 229, but comprises an iron wire armor 223a, a filler 231, a seat 232, and a seat 233. The array cable 2' differs from the array cable 2 in that the covering 227A comprises a pressure tape 221, a seat 232, an iron wire armor 223, a seat 233, an iron wire armor 223a, and an outer sheath 225. The filler 231 is made of, for example, a polypropylene string and fills the gap between the power line unit 210 and the pressure tape 221. In the array cable 2', an optical cable 205 is disposed within the filler 231. The seat 232 is made of, for example, a plastic string and covers the outer periphery of the pressure tape 221. An iron wire armor 223 is arranged on the outer periphery of the seat 232, and a seat 233 is provided on the outer periphery of the iron wire armor 223. The seat 233 is made of, for example, a plastic string. An iron wire armor 223a made of iron wire is arranged on the outer periphery of the seat 233. In other words, the array cable 2' has a double iron wire armor with the seat 233 sandwiched between them. The outer periphery of the iron wire armor 223a is covered with an outer sheath 225.

[0033] 4 is a schematic plan view of the vicinity of the tower 12 of the offshore platform 1. A winch 20, multiple pulleys 21, and connection boxes 30A and 30B are installed near the tower 12 provided on the floating body 11. The connection boxes 30A and 30B are rooms that house direct equipment connection terminals, which are an example of a connection part that connects the array cable 2 to a power cable connected to the power equipment in the nacelle 13. The winch 20 is an electric winch that winds and lets out the wire rope 22. The wire rope 22 is fed onto the connection boxes 30A and 30B via the pulleys 21. Note that since the connection boxes 30A and 30B have the same configuration, they will be referred to as the connection box 30 unless there is a need to distinguish them in the following description.

[0034] 5 is a schematic diagram of the float 11 as seen from the side. Riser pipes 17 are provided below the connection boxes 30A and 30B. The riser pipes 17 are hollow pipes arranged vertically along the float 11, and protect the array cables 2 that pass through their hollow portions. The bend stiffeners 18 limit the bending of the array cables 2, and are attached to the lower ends of the riser pipes 17. The array cables 2 pass through the bend stiffeners 18 and the hollow portions of the riser pipes 17, and their ends are fixed inside the connection boxes 30A and 30B.

[0035] 6 is a schematic diagram of the inside of the junction box 30. The junction box 30 includes a power cable junction box 31, an optical cable junction box 36, a door 33A, a ceiling door 33B, and an adapter 35. Inside the junction box 30, a retaining portion 4 is provided at the end of the array cable 2. The retaining portion 4 is a component for fixing the end of the array cable 2 inside the junction box 30. Beyond the retaining portion 4, the covering 227 and spacer member 229 of the array cable 2 are removed, exposing the optical cable 205 and the power line 203.

[0036] The door 33A is a door for workers to enter and exit the inside of the junction box 30 and is provided on the side of the junction box 30. The ceiling door 33B is provided on the ceiling of the junction box 30 and opens and closes an opening provided in the ceiling. The optical cable junction box 36 connects the optical cable 205 to an optical cable connected to a computer device in the nacelle 13 using a connector. The adapter 35 is a member shaped like a hollow cylinder with a flange cut in half. The adapter 35 is arranged around the upper end of the riser pipe 17. The adapter 35 is installed between the retaining portion 4 and the floor of the junction box 30 to support the retaining portion 4 at its upper end, and the array cable 2 is passed through the hollow portion.

[0037] The power cable junction box 31 is a box that houses direct equipment connection terminals that connect the power lines 203 to the section cables 131 that are connected to the power equipment inside the nacelle 13. Fig. 7A is a diagram showing the power cable junction box 31 in an open state, and Fig. 7B is a side view of the direct equipment connection terminals housed in the power cable junction box 31. A direct equipment connection terminal 5A is provided at the end of the power line 203, and a direct equipment connection terminal 5B is provided at the end of the section cable 131 that is connected to the power equipment inside the nacelle 13. The direct equipment connection terminals 5A and 5B are housed in the power cable junction box 31 in a connected state and are supported inside the power cable junction box 31 by a bracket 34. A cable cleat 32A supports three section cables 131, and a cable cleat 32B supports three power lines 203.

[0038] FIG. 8 illustrates the structure of the device direct connection terminals 5A and 5B. Insulating stress cones 57 are provided at the ends of the power line 203 and the section cable 131. Conductive terminals 53 are attached to the conductors 207 of the power line 203 and the section cable 131. The stress cones 57 and terminals 53 are covered with insulating layers 54, inner semiconductive layers 56, and outer semiconductive layers 55. A conductive connection bolt 52 electrically connects the terminal 53 of the device direct connection terminal 5A to the terminal 53 of the device direct connection terminal 5B. An insulating plug 59 seals the end of the connection bolt 52 and is covered with a protective cap 58. The connector body 51 is made of an insulating material and seals the connection bolt 52.

[0039] 9A is a half-side cross-sectional view of the retaining portion 4. The retaining portion 4 bends and holds the iron wire armor 223 provided on the array cable 2, and clamps the array cable 2 to enable attachment, fixation, and removal to the offshore platform 1. The retaining portion 4 includes a wedge 41, a stopper 42, a clamp portion 43, and an eyebolt 44. The retaining portion 4 clamps the array cable 2 while bending and holding the iron wire armor 223 with the wedge 41, the stopper 42, and the clamp portion 43. Note that the retaining portion 4 shown in FIG. 9A is an example, and the structure of the retaining portion 4 is not limited to that shown in FIG. 9A .

[0040] The clamp portion 43 has a ring shape and is made of metal. The hole in the clamp portion 43 through which the array cable 2 is passed is formed so that its diameter decreases from top to bottom. The bent iron wire armor 223 is fixed by being sandwiched between the inner surface of the hole and the wedge 41. The clamp portion 43 is split in half and has multiple holes on its outer periphery through which bolts pass. When attaching the detention portion 4 to the offshore platform 1, the clamp portion 43 is placed on the adapter 35 and fixed to a flange at the upper end of the adapter 35 with multiple bolts. When removing the detention portion 4 from the offshore platform 1, the multiple bolts are removed from the flange, thereby removing the detention portion 4 from the adapter 35. The clamp portion 43 is also an example of an attachment / fixing portion for fixing a movable termination 7 and an energized termination 8 (described later) to the array cable 2 with bolts. The protective tube of the movable termination 7 and the energized termination 8, which will be described later, are attached and fixed to the upper surface of the clamp 43. The clamp 43 may be fastened to one half with a bolt extending from one half to the other. Alternatively, the clamp 43 may have a two-layer structure, with the two layers stacked so that the halves are oriented in a cross direction and fastened together with bolts at the top and bottom, thereby reliably clamping the array cable 2.

[0041] Eye bolts 44, which are an example of a hoisting device, are provided on the outer periphery of the clamp 43, and a wire rope is tied to them when lifting the fastening part 4. Hereinafter, the eye bolts will be described as an example of a hoisting device. Because the distance from the center of the fastening part 4 to the left and right ends of the two eye bolts 44 is shorter than the inner diameter of the riser pipe 17, the fastening part 4 can be passed inside the riser pipe 17 when the adapter 35 is removed.

[0042] A plurality of wedges 41 are fixed to the iron wire armor 223 of the power line 203. The wedges 41 have a circular ring shape when viewed from above, and a semicircular shape at the top in cross section, with the width narrowing toward the bottom. Like the clamps 43, the wedges 41 may also be split into two halves, with one half fastened to the other by a bolt extending from one half to the other. The multiple wedges 41 engage with the clamps 43 and support the power line 203 to prevent it from descending. The iron wire armor 223 is sandwiched and fixed between the semicircular and wedge-shaped portions of the wedges 41 and the stoppers 42 and clamps 43, thereby clamping the iron wire armor 223 and holding the array cable 2.

[0043] The stopper 42 is fixed to the clamp portion 43 with multiple bolts, and holds down the power lines 203 to secure them to the retention portion 4. The hole in the stopper 42 through which the array cable 2 is passed is formed so that its diameter increases from top to bottom, corresponding to the semicircular portion of the wedge 41. The bent iron wire armor 223 is sandwiched and fixed between the inner circumferential surface of this hole and the wedge 41, thereby clamping the array cable 2. Note that the stopper 42 may also have a two-layer structure, with the two layers stacked so that the halves are oriented in an intersecting direction and fixed with bolts at the top and bottom, thereby reliably clamping the array cable 2.

[0044] 9B is a half-sectional view of a retaining portion 4A, which is another example of a retaining portion. The retaining portion 4A has a configuration in which the stopper 42 and the clamp portion 43 of the retaining portion 4 are replaced with a stopper 42A and a clamp portion 43A, respectively, and the wedge 41 is eliminated. In the retaining portion 4A, the bent iron wire armor 223 is sandwiched and fixed between the upper surface of the clamp portion 43A and the lower surface of the stopper 42A. The holes in the stopper 42A and the clamp portion 43A through which the array cable 2 is passed may have a constant diameter from top to bottom. When such a retaining portion 4A is used, attaching the retaining portion 4A to the array cable 2 is relatively easy.

[0045] 9C is a half-side cross-sectional view of the retaining portion 4 when the array cable is the array cable 2′ shown in FIG. 3B. In this case, both the iron wire armor 223 and the iron wire armor 223a are sandwiched and fixed between the semicircular and wedge-shaped portions of the wedge 41 and the stopper 42 and clamp portion 43, thereby clamping the iron wire armor 223 and the iron wire armor 223a and holding the array cable 2′.

[0046] FIG. 9D is a half-sectional view of a retaining portion 4B, which is another example of a retaining portion for the array cable 2′ shown in FIG. 3B . The retaining portion 4B has a configuration in which the stopper 42 and the clamp portion 43 in the retaining portion 4 are replaced with stopper 42B and clamp portion 43B, respectively, and a stopper 42C is further added. The hole in clamp portion 43B through which the array cable 2′ is passed is formed so that its diameter decreases from top to bottom. The holes in stopper 42B and stopper 42C through which the array cable 2′ is passed may have a constant diameter from top to bottom. With the retaining portion 4B, the iron wire armor 223a is sandwiched and fixed between the semicircular and wedge-shaped portions of the wedge 41 and the stopper 42B and clamp portion 43B. The iron wire armor 223 is also sandwiched and fixed between the upper surface of stopper 42B and the lower surface of stopper 42C. This allows the iron wire armor 223 and the iron wire armor 223a to be clamped and the array cable 2' to be held.

[0047] Next, we will explain a method for maintaining power transmission from the wind farm WF during maintenance of the offshore platform 1. When performing maintenance on the offshore platform 1, the array cable 2 is removed from the offshore platform 1, but if the array cable 2 that was connected to the offshore platform 1 under maintenance remains disconnected, power generated by other operating offshore platforms 1 cannot be sent to the substation.

[0048] Therefore, in this embodiment, the array cables 2 connected to the offshore platform 1 undergoing maintenance are removed, and the removed array cables 2 are connected together to maintain the series connection of the array cables 2, and power generated by other operating offshore platforms 1 is sent to the substation. Also, in this embodiment, the series-connected array cables 2 are disconnected from the offshore platform 1 for which maintenance has been completed, and the disconnected array cables 2 are connected in series to the offshore platform 1 for which maintenance has been completed. Below, a method of disconnecting the array cables 2 from the offshore platform 1 and connecting them in series, and a method of disconnecting the series-connected array cables 2 and connecting them in series to the offshore platform 1 for which maintenance has been completed will be described.

[0049] 10 is a flowchart showing the process of removing the array cable 2 from the offshore platform 1 and hoisting the removed array cable 2 onto a work vessel for series connection. Fig. 11 is a schematic diagram showing the interior of the connection box 30A before the array cable 2 is removed. Before the array cable 2 is removed from the offshore platform 1, the end of the array cable 2 is held in place within the connection box 30A by the holding portions 4, the power lines 203 are connected to the section cables 131 in the power cable connection box 31, and the optical cables 205 are connected to the optical cable connection box 36.

[0050] First, the worker removes the power line 203 from the power cable junction box 31 and the optical cable 205 from the optical cable junction box 36 (step S1). Fig. 12 is a schematic diagram showing the state after the power line 203 and the optical cable 205 have been removed. The worker removes the device direct connection terminal 5A from the device direct connection terminal 5B inside the power cable junction box 31, exposing the stress cone 57 and the terminal 53 attached to the tip of the power line 203. The worker also removes the optical cable 205 from the optical cable junction box 36.

[0051] Next, the worker waterproofs the ends of the power line 203 and the optical cable 205 (step S2). FIG. 13 is a schematic diagram showing the state after waterproofing the ends of the power line 203 and the optical cable 205. Specifically, the worker inserts the stress cone 57 and the terminal 53 into the waterproof pipe 61, and inserts the end of the optical cable 205 into the waterproof pipe 63. The waterproof pipes 61 and 63 are hollow cylindrical with one end closed and are made of, for example, metal. The waterproof pipes 61 and 63 are an example of a waterproof section according to the present invention. The waterproof pipes 61 and 63 may be covered with a sheath made of synthetic resin. The worker waterproofs the opening of the waterproof pipe 61 into which the stress cone 57 and the terminal 53 are inserted to form a waterproof treatment section 62 so as to prevent seawater from entering the inside of the waterproof pipe 61, and waterproofs the opening of the waterproof pipe 63 into which the end of the optical cable 205 is inserted to form a waterproof treatment section 64 so as to prevent seawater from entering the inside of the waterproof pipe 63.

[0052] FIG. 14 is a schematic diagram of one side cross section of the waterproofing treatment section 62. The adhesive watertight sheet 629 is an adhesive watertight sheet that is wrapped around the power line 203. The self-fusing tape 624 is a self-fusing tape that is wrapped around the power line 203 to fill in any gaps between the adhesive watertight sheet 629 and the power line 203. The aluminum tape 623 is an aluminum foil tape with an adhesive applied to one side that is wrapped around the end of the adhesive watertight sheet 629 and the self-fusing tape 624. The heat-shrinkable tube 622 is a tube that shrinks when heated. The heat-shrinkable tube 622 is placed over the end of the waterproof pipe 61, the adhesive watertight sheet 629, the self-fusing tape 624, the aluminum tape 623, and the power line 203. The heated heat-shrinkable tube 622 shrinks and adheres tightly to the end of the waterproof pipe 61, the adhesive watertight sheet 629, the aluminum tape 623, and the power line 203. The heat-shrinkable tube 622 may have an inner adhesive layer made of an adhesive or an inner adhesive layer made of a pressure-sensitive adhesive. The adhesive watertight sheet 627 is an adhesive watertight sheet that is wrapped around the end of the heat-shrinkable tube 622. The insulating tape 626 is an insulating tape made by laminating a black polyethylene film and a self-adhesive adhesive material primarily made of butyl rubber. The insulating tape 626 is wrapped around the adhesive watertight sheet 627 and the end of the heat-shrinkable tube 622. The PVC tape 625 is an insulating tape made by bonding a polyethylene base material with an adhesive layer primarily made of butyl rubber. The PVC tape 625 is wrapped around the insulating tape 626. The adhesive watertight sheet 621 is an adhesive watertight sheet that is wrapped around the end of the heat-shrinkable tubing 622 and the power line 203. The insulating tape 620 is an insulating tape formed by laminating a black polyethylene film and a self-adhesive adhesive material whose main component is butyl rubber. The insulating tape 620 is wrapped around the adhesive watertight sheet 621, the end of the heat-shrinkable tubing 622, and the end of the power line 203. The PVC tape 628 is an insulating tape made by bonding an adhesive layer whose main component is butyl rubber to a polyethylene base material, and is wrapped around the insulating tape 620. The waterproofing treatment portion 64 is formed in the same manner as the waterproofing treatment portion 62.

[0053] Next, the worker lifts up the fastening portion 4 and removes the adapter 35 (step S3). Figure 15 is a schematic diagram showing the state after the adapter 35 has been removed and the fastening portion 4 has been lifted up. The worker attaches a hoisting scale 23, which is an example of a hoisting device for suspending the fastening portion by the wire rope, to the wire rope 22 inside the connection box 30A, and connects the hoisting scale 23 to an eyebolt 44, also an example of a hoisting device, with the hoisting rope 24. The worker also removes the bolts that secure the fastening portion 4 to the adapter 35, removes the adapter 35 from the fastening portion 4, and drives the winch 20 to lift up the fastening portion 4.

[0054] Next, the worker assembles the mobile termination 7, which is an example of a cable mover for moving the end of the power line 203 to the work boat (step S4). FIG. 16 is a schematic diagram showing the assembled state of the mobile termination 7. First, before assembling the mobile termination 7, a temporary cradle 25, which is split in half, is placed between the fastening portion 4 and the riser pipe 17, and the lifting balance 23 is lowered to place the fastening portion 4 on the temporary cradle 25. The temporary cradle 25 on which the fastening portion 4 is placed is formed so that the lower sides of the bolt-through holes in the clamp portion 43 are exposed. Note that the temporary cradle 25 may be configured, for example, by arranging two metal beams to sandwich the riser pipe 17 between them, so that when the fastening portion 4 is placed, the lower sides of the bolt-through holes in the clamp portion 43 are exposed between the two beams. This structure allows the bolts to be tightened with nuts below the bolt-through holes in the clamp portion 43 to secure the protective pipe 71, which will be described later.

[0055] FIG. 17A is a half-side cross-sectional view of the mobile termination 7. The mobile termination 7 includes a fastening portion 4, a protection tube 71, a cover 72, an eyebolt 73 as an example of a suspending device, a flange 74, and a binder 75. The protection tube 71, which is an example of a protection portion that protects the power lines 203 and optical cables 205 exposed from the array cable 2, is a hollow cylinder with open ends in the longitudinal direction and is made of metal. The protection tube 71 is designed to sink under its own weight when cast into the sea. To enable the protection tube 71 to sink under its own weight, for example, the weight of the assembled mobile termination 7 may be made heavier than the weight of seawater with the same volume as the mobile termination 7. Alternatively, to enable the protection tube 71 to sink under its own weight, for example, the protection tube 71 may be provided with a plurality of holes penetrating from the inside to the outside, allowing seawater to flow into the protection tube 71 when cast into the sea and discharging the seawater when pulled out of the sea. The protective pipe 71 has a flange 74 formed on one end and an open end. A metal lid 72 is attached to the open end of the protective pipe 71 with bolts to close it. An eyebolt 73 is provided at the end of the protective pipe 71 where the lid 72 is attached, and the wire rope 22 is tied to the eyebolt 73. The protective pipe 71 may be made of resin. Protective parts that can replace the protective pipe 71 include, for example, a cylindrical metal mesh or a circular arrangement of multiple stud bolts that surround the waterproof pipes 61, 63, and the power line 203. Alternatively, columnar members or the like may be fastened to the retaining portion 4 and the lid 72 with bolts or the like to surround the waterproof pipes 61, 63, and the power line 203 and hold them inside. In this case, the columnar members do not necessarily have to be arranged in a circular shape.

[0056] 17B is a half-side cross-sectional view of movable termination 7A, another example of a movable termination. Mobile termination 7A has a configuration in which protective tube 71A replaces protective tube 71 in mobile termination 7. Protective tube 71A is provided with slits 71Aa through which seawater flows in. Slits 71Aa extend in the longitudinal direction of protective tube 71A, and multiple slits 71Aa are formed on the outer circumferential surface of protective tube 71A.

[0057] The waterproof section may also be integrated with a portion of the protective section. Figure 17C is a half-sectional view of a mobile termination 7B, another example of a mobile termination. The mobile termination 7B has a configuration in which the protective tube 71 in the mobile termination 7 is replaced with a protective tube 71B. However, when using the mobile termination 7B, the waterproof tube 61 and waterproof processing section 62 are not provided on the power line 203, and the waterproof tube 63 and waterproof processing section 64 are not provided on the optical cable 205. The protective tube 71B includes a waterproof / protective section 71Ba, a waterproof processing section 71Bb, and a lower section 71Bc. The waterproof / protective section 71Ba is sealed, and the waterproof section and a portion of the protective section are integrated. The waterproof processing section 71Bb is the portion through which the power line 203 and optical cable 205 are passed and is waterproofed. In the waterproof processing section 71Bb, the portion through which the power line 203 and optical cable 205 are passed is cylindrical. The lower portion 71Bc is provided with slits 71Bca through which seawater flows in. The slits 71Bca extend in the longitudinal direction of the lower portion 71Bc, and a plurality of slits 71Bca are formed on the outer circumferential surface of the lower portion 71Bc.

[0058] Each of the protective parts holds the power lines 203 and optical cables 205, the ends of which are waterproofed, inside, while the parts other than the waterproof part sink into the sea under their own weight as seawater flows in. In addition, by bundling the power lines 203 and optical cables 205 with bundling tools 75, they can be easily held inside even if the structure of the protective part is simplified.

[0059] When assembling the movable termination 7 of FIG. 17A , the waterproof pipe 61, the waterproofing portion 62, the waterproof pipe 63, and the waterproofing portion 64 are inserted into the protective pipe 71, and the flange 74 is secured to the retaining portion 4 with bolts. When inserting the waterproof pipes 61, 63 and the waterproofing portions 62, 64 into the protective pipe 71, the three power lines 203 are bundled together with a binding device 75 such as tape or a metal band and restrained to fit the inner diameter of the protective pipe 71. The lid 72 is attached to the protective pipe 71 with bolts to close the end of the protective pipe 71. The protective pipe 71, which includes the waterproof pipes 61, 63, is an example of a protective portion according to the present invention. The protective pipe 71 may be divided into two parts, one with the flange 74 and the other with the eyebolt 73, and the part with the flange 74 and the part with the eyebolt 73 may be connected when assembling the movable termination 7. Furthermore, the movable termination 7 may have an eyebolt 73 attached to the lid 72. Since the weight of the assembled movable termination 7 is heavier than the weight of seawater with the same volume as the movable termination 7, the movable termination 7 will sink under its own weight when dropped into the sea.

[0060] Next, the worker reconnects the wire rope 22 from the hoisting balance 23 to the eyebolt 73, suspends the movable termination 7, and removes the temporary support base 25 (step S5). Figure 18 is a schematic diagram showing the suspended movable termination 7. Here, the outer diameter of the movable termination 7 and the outer diameter of the retaining portion 4 are smaller than the inner diameter of the riser pipe 17, so the movable termination 7 can be lowered onto the riser pipe 17.

[0061] Next, the worker removes the bend stiffener 18 from the offshore platform 1 (step S6). Fig. 19 is a schematic diagram showing the bend stiffener 18 removed from the offshore platform 1. In step S6, the diver DV removes the bend stiffener 18 from the floating body 11 in the sea. The bend stiffener 18 removed from the floating body 11 is lowered to a position where it does not interfere with the mobile termination 7 being lowered.

[0062] Next, the worker drives the winch 20 to lower the movable termination 7 (step S7). Figure 20 is a schematic diagram showing the movable termination 7 being lowered. Here, the outer diameters of the movable termination 7 and the retention portion 4 are smaller than the inner diameter of the riser pipe 17, so the movable termination 7 descends inside the riser pipe 17 due to its own weight. The lowered movable termination 7 emerges from the lower end of the riser pipe 17 and moves into the sea. Figure 21 is a schematic diagram showing the movable termination 7 after it has moved into the sea.

[0063] Next, the diver DV connects the wire rope 27, which is wound onto the winch 26 of the work vessel SH, to the mobile termination 7 in the sea (step S8). Figure 22 is a schematic diagram showing the wire rope 27 connected to the eyebolt 73 of the mobile termination 7. After connecting the wire rope 27 to the mobile termination 7 with the mobile termination 7 located between the sea surface and the seabed, the diver DV detaches the wire rope 22 from the mobile termination 7. Because the mobile termination 7 does not reach the seabed by operating the winch 26, the water pressure resistance of the mobile termination 7 may be less than the water pressure of the seabed where the array cable 2 is laid.

[0064] Next, the worker drives the winch 26 to pull the mobile termination 7 toward the work vessel (step S9). FIG. 23 is a schematic diagram showing the mobile termination 7 pulled toward the work vessel SH. Next, the worker connects the wire rope 28 of a crawler crane (not shown) equipped on the work vessel SH to the mobile termination 7 and pulls the mobile termination 7 toward the work vessel SH (step S10). FIG. 24 is a schematic diagram showing the operation of pulling the mobile termination 7 toward the work vessel SH with the wire rope 28. Using a crawler crane reduces the load on the mobile termination 7 compared to pulling the mobile termination 7 toward the work vessel SH using only the winch 26. The mobile termination 7 is pulled toward the work vessel SH by the crawler crane and winch 26, as shown in FIG. 25.

[0065] In addition, the retaining portion 4 of the connection box 30B and the array cable 2 retained in the connection box 30B are removed and the movable termination 7 is assembled using the same process as described above, and then lowered into the sea from the riser pipe 17 and pulled up to the work vessel SH.

[0066] Next, the process of connecting the array cables 2 hoisted onto the work vessel SH in series will be described. FIG. 26 is a flowchart showing the process of connecting the array cables 2 in series. FIG. 27 is a schematic diagram of a mobile termination 7 assembled in a junction box 30A and hoisted onto the work vessel SH, and a mobile termination 7 assembled in a junction box 30B and hoisted onto the work vessel SH. In the following description, for convenience of explanation, the array cable 2 secured to the detent 4 taken out of the junction box 30A will be referred to as the array cable 2A, and the array cable 2 secured to the detent 4 taken out of the junction box 30B will be referred to as the array cable 2B. The array cables 2A and 2B hoisted onto the work vessel SH are held on the work vessel SH.

[0067] First, the worker removes the protective pipe 71 provided on the mobile termination 7 from the fastening part 4 and dismantles the mobile termination 7 (step S21). Figure 28 is a schematic diagram showing the state after the protective pipe 71 has been removed from the fastening part 4. Next, the worker dismantles the waterproofing treatment parts 62, 64 and removes the waterproof pipes 61, 63 from the power line 203 (step S22). Figure 29 is a schematic diagram showing the state after the waterproofing treatment parts 62, 64 have been dismantled and the waterproof pipes 61, 63 have been removed from the power line 203.

[0068] Next, the worker assembles the energized termination 8, which is an example of a connector that connects the array cables 2A and 2B in series. Figure 30 is a diagram showing the internal configuration of the energized termination 8. The energized termination 8 includes a bottom plate 81, a protective body 82, a cover 83, a base 84, a connector cleat 85, a cable cleat 86, a stud bolt 87, an optical cable connection box 88, a lower metal fitting 89, and a retaining portion 4.

[0069] The bottom plate 81 has a disk shape and is made of, for example, stainless steel. FIG. 31A shows a plan view of the bottom plate 81. The bottom plate 81 is provided with a through-hole 811, screw holes 812A and 812B, cable holes 813A and 813B, and optical cable holes 814A and 814B. The multiple through-holes 811 are holes through which bolts for fixing the protective body 82 to the bottom plate 81 are passed. The through-holes 811 are formed on the outer periphery of the bottom plate 81. The cable holes 813A and 813B are holes through which the power lines 203 are passed. The three cable holes 813A are arranged in a triangular shape, and the three power lines 203 of the array cable 2A are passed through them. The three cable holes 813B are arranged in a triangular shape, and the three power lines 203 of the array cable 2B are passed through them. The optical cable holes 814A and 814B are holes through which the optical cable 205 is passed through. The optical cable 205 of the array cable 2A is passed through the optical cable hole 814A, and the optical cable 205 of the array cable 2B is passed through the optical cable hole 814B.

[0070] The plurality of screw holes 812A and the plurality of screw holes 812B are threaded and are holes into which one ends of stud bolts 87, which are an example of a connector, are attached. Hereinafter, the stud bolts are described as an example of a connector that adjusts the distance between the bottom plate 81 and the clamp portion 43 of the fastening portion 4 and connects and fastens the bottom plate 81 to the clamp portion 43 of the fastening portion 4. The screw holes 812A are provided at equal intervals to surround the three cable holes 813A, and the screw holes 812B are provided at equal intervals to surround the three cable holes 813B. The screw holes 812A are fitted with stud bolts 87 that connect the fastening portions 4 to which the array cable 2A is fixed, and the screw holes 812B are fitted with stud bolts 87 that connect the fastening portions 4 to which the array cable 2B is fixed.

[0071] Here, the two fastening portions 4 may be fixed together by an integrated part (not shown), and the distance between the two fastening portions 4 and the bottom plate 81 may be adjusted collectively by a connector. This allows the two fastening portions 4 to be firmly held to the bottom plate 81, more reliably protecting the power wires 203 from which the iron wire armor 223 has been stripped. Alternatively, the distance between the two fastening portions 4 and the bottom plate 81 may be independently adjusted by a connector. This allows the distance between the bottom plate 81 and each fastening portion 4 to be adjusted and fixed so that the degree of deflection of each power wire 203 exposed in the sea after the iron wire armor 223 has been stripped is appropriate for each of the two array cables 2A, 2B.

[0072] The lower metal fitting 89 is a metal fitting through which the power line 203 and the optical cable 205 are passed, and is fixed to the bottom plate 81. The portion of the lower metal fitting 89 through which the power line 203 and the optical cable 205 are passed is cylindrical. The portion of the lower metal fitting 89 through which the power line 203 is passed has an inner diameter that is larger than the outer diameter of the power line 203. Note that the portion of the lower metal fitting 89 through which the power line 203 is passed may have an inner diameter through which the stress cone 57 passes, or may have an inner diameter through which the terminal 53 passes if the terminal 53 is attached to the end of the power line 203. The lower metal fitting 89 is formed, for example, from stainless steel.

[0073] The protective body 82 has a hollow cylindrical shape and is made of, for example, stainless steel. The protective body 82 has a flange 821 formed on one end and an open end. A metal cover 83 is attached to the open end of the protective body 82 with bolts to close it. The cover 83 is equipped with an eyebolt 83A to which a wire rope is connected. The connector cleat 85 is a plate-shaped member that supports the device direct connection terminals 5A and 5B provided at the ends of the power lines 203. The connector cleat 85 is preferably an insulator to suppress heat generation due to induction of current flowing through the power lines 203. The cable cleat 86 is a plate-shaped member that supports the power lines 203 housed within the protective body 82. The cable cleat 86 is preferably an insulator to suppress heat generation due to induction of current flowing through the power lines 203. The optical cable junction box 88 connects the optical cable 205 of the array cable 2A to the optical cable 205 of the array cable 2B. The optical cable connection box 88 is housed in the protective body 82 and fixed to the stand 84. The bottom plate 81, the protective body 82, and the lid 83 are an example of the protective body according to the present invention.

[0074] The base 84 is a base to which the connector cleat 85 and the cable cleat 86 are fixed. The base 84 has multiple holes through which bolts are passed. The connector cleat 85 and the cable cleat 86 are fixed to the base 84 by bolts passed through the holes. One end of a stud bolt 87 is attached to the screw holes 812A and 812B of the bottom plate 81, and the other end is attached to the clamp portion 43 of the retaining portion 4, connecting the bottom plate 81 and the retaining portion 4. The stud bolt 87 adjusts the distance between the bottom plate 81 and the retaining portion 4, thereby reducing flexure of the power line 203 between the bottom plate 81 and the retaining portion 4. The base 84 is made of, for example, stainless steel. The multiple holes formed in the base 84 allow for precise adjustment of the attachment positions of the connector cleat 85 and the cable cleat 86. The base 84 may be fixed to the inner surface of the protective body 82 with a scaffolding jack, for example, to reduce movement within the protective body 82.

[0075] The conductive termination 8 may be provided with a mechanism that can adjust the ratio between the length of the portion of the power line 203 that is located outside the protective body 82 and the length of the portion that is housed in the protective body 82. By providing such a mechanism, the bending of the power line 203 can be further suppressed.

[0076] As a modification of the energized termination 8, the connector cleat 85 may have a mechanism that allows individual adjustment of the fixing position of the device direct connection terminal 5A or 5B of each power line 203. Furthermore, the cable cleat 86 may have a mechanism that allows individual adjustment of the fixing position of each power line 203. By providing such a mechanism, it is possible to further suppress bending of the power lines 203.

[0077] The above-described mount 84 and connector cleat 85 constitute a position adjusting and fixing part that can adjust and fix the positions of the direct device connection terminals 5A, 5B while the direct device connection terminals 5A, 5B are connected inside the protective body 82. Note that this position adjusting and fixing part inside the protective body 82 does not necessarily require the structure that adjusts and fixes the spacing between the bottom plate 81 and the fastening part 4 with the connector outside the protective body 82, and may be provided separately from this. In other words, as long as the bottom plate 81 and the fastening part 4 are fixed at a predetermined spacing outside the protective body that does not cause excessive bending of the power lines 203, the connector may only fix the spacing without adjusting the spacing, and the positions of the direct device connection terminals 5A, 5B may be adjusted and fixed only inside the protective body 82.

[0078] The bottom plate 81 may be replaced with a bottom plate 81A, which is another example. FIG. 31B shows a plan view of the bottom plate 81A, which is another example. In the bottom plate 81A, the three cable holes 813A are aligned in a straight line. The three cable holes 813B are also aligned in a straight line. If the three cable holes 813A and the three cable holes 813B are aligned in a straight line, the three power lines 203 are also aligned in a straight line within the protective body 82. This makes it easier to offset the power lines 203, for example, vertically offset from the straight line, making it easier to assemble the electrical termination 8. This also reduces the likelihood of the power lines 203 becoming bent and contacting the edges of the cable holes 813A or 813B.

[0079] 32 to 38 are schematic diagrams showing the steps for assembling the energized termination 8. When assembling the energized termination 8, the worker first passes the power line 203 and the optical cable 205 through the lower metal fitting 89 and the bottom plate 81, as shown in FIG. 32 (step S23).

[0080] Next, the worker connects the power lines 203 of the array cable 2A to the power lines 203 of the array cable 2B, and connects the optical cables 205 of the array cable 2A to the optical cables 205 of the array cable 2B (step S24). Figure 33 is a schematic diagram showing the state after the power lines 203 and the optical cables 205 have been connected. Specifically, the worker assembles the direct device connection terminals 5A and 5B, each including a stress cone 57 and a terminal 53, and connects the direct device connection terminals 5A and 5B using an insulating bushing. The direct device connection terminals 5A and 5B are an example of a connection part in a connector. The worker then secures the insulating bushing to the connector cleat 85 and secures the power lines 203 to the cable cleat 86. The optical cables 205 of the array cable 2A and the optical cables 205 of the array cable 2B are connected using an optical cable connection box 88.

[0081] Next, the worker fixes the direct device connection terminals 5A and 5B, the power line 203, and the optical cable junction box 88 to the frame 84 (step S25). Fig. 34 is a schematic diagram showing the fixed direct device connection terminals 5A and 5B, the power line 203, and the optical cable junction box 88. Specifically, the worker fixes the connector cleat 85 to the frame 84, and fixes the cable cleat 86 to which the power line 203 is fixed to the frame 84. The worker also fixes the optical cable junction box 88 to the frame 84. The worker fixes the frame 84 to which the connector cleat 85, the cable cleat 86, and the optical cable junction box 88 are fixed to the bottom plate 81.

[0082] Next, the worker waterproofs the fastening portion 4 side of the lower fitting 89 (step S26). FIG. 35 is a schematic diagram showing the waterproofing portion formed by waterproofing. To prevent seawater from entering the platform 84 from the fastening portion 4 side, the worker waterproofs the opening of the lower fitting 89 on the fastening portion 4 side to form a waterproofing portion 90. The waterproofing portion 90 is formed using heat-shrink tubing and multiple tapes, similar to the waterproofing portions 62 and 64. Because the conductive termination 8 is placed on the seabed, the waterproofing portion 90 preferably has higher waterproofing performance than the waterproofing portions 62 and 64 and can withstand the water pressure of the seabed. The waterproofing performance (water pressure resistance) of the waterproofing portion 90 can be improved, for example, by increasing the length of the heat-shrink tubing 622 that tightly covers the waterproof pipe 61 and the inner sheath 217. By using such a waterproofing treatment 90 in the energized termination 8, the waterproofing performance is higher than that of the waterproofing treatments 62, 64 of the mobile termination 7, which remains at a higher position than the seabed, and the electrified termination 8 can withstand the water pressure at the seabed. The heat shrinkable tube used in the waterproofing treatment 90 is preferably one with a metal layer. Aluminum foil or aluminum tape may also be used in the waterproofing treatment 90 to improve waterproofing performance.

[0083] Next, the worker connects the bottom plate 81 and the fastening portion 4 with the stud bolts 87 and adjusts the distance between the bottom plate 81 and the fastening portion 4 (step S27). FIG. 36 is a schematic diagram showing the bottom plate 81 and the fastening portion 4 connected with the stud bolts 87. The bottom plate 81 has a screw hole 812A corresponding to the fastening portion 4 fixed to the array cable 2A, and a screw hole 812B corresponding to the fastening portion 4 fixed to the array cable 2B. The bottom plate 81 and the fastening portion 4 are fixed with the stud bolts 87 as a connector, with the distance between the bottom plate 81 and the fastening portion 4 adjusted. In the fastening portion 4, the stud bolts 87 are passed through holes in the clamp portion 43 through which the bolts pass. The stud bolts 87 and the fastening portion 4 are fixed with nuts that clamp both ends of the holes. The distance between the bottom plate 81 and the retaining portion 4 to which the array cable 2A is fixed and the distance between the bottom plate 81 and the retaining portion 4 to which the array cable 2B is fixed can be adjusted separately.

[0084] The screw holes 812A and 812B are holes that do not penetrate to the side opposite to the side where the stud bolt 87 is attached. If the screw holes 812A and 812B penetrate to the side opposite to the side where the stud bolt 87 is attached, it is preferable to apply a waterproofing treatment when the stud bolt 87 is attached.

[0085] The connector that adjusts and secures the distance between the bottom plate 81 and the fastening portion 4 is not limited to the stud bolt 87, but may be, for example, a perforated angle having a plurality of bolt holes. When using a perforated angle as a connector, the perforated angle may be fixed to the bottom plate 81, and the distance between the bottom plate 81 and the fastening portion 4 may be adjusted to an appropriate distance, and then the perforated angle and the fastening portion 4 may be fixed with bolts. Furthermore, the connector may be fixed via, for example, one or more spacers, thereby adjusting and securing the distance between the bottom plate 81 and the fastening portion 4. The use of a perforated angle as a connector will be described in detail later.

[0086] In this way, the distance between the bottom plate 81 and the fastening portion 4 is adjusted and fixed with the stud bolt 87. Here, the power line 203 and the optical cable 205 are exposed between the bottom plate 81 and the fastening portion 4, and the deflection of the portion of the power line 203 that comes into contact with seawater when the conductive termination 8 is submerged can be maintained in a constant state.

[0087] Next, the worker attaches the protective body 82 to the bottom plate 81 (step S28). Figure 37 is a schematic diagram showing the state in which the protective body 82 is attached to the bottom plate 81. Here, the worker passes a bolt through the flange 821 of the protective body 82 and the through-hole 811 of the bottom plate 81 to fix the protective body 82 to the bottom plate 81.

[0088] Next, the worker attaches the lid 83 to the protective body 82 to close the protective body 82 (step S29). Figure 38 is a schematic diagram showing the state in which the lid 83 is attached to the protective body 82. By attaching the lid 83 to the protective body 82, the inside of the protective body 82 is sealed and seawater cannot enter. Furthermore, six power lines 203 and two optical cables 205 are housed together inside the protective body 82. Note that, although the power lines 203 are passed through one by one in the bottom plate 81, through holes may be provided so that three or six power lines can be passed through at a time.

[0089] Next, the worker lowers the assembled energized termination 8 to the seabed. Figure 39 is a flowchart showing the process of lowering the energized termination 8 to the seabed. Figures 40 to 42 are schematic diagrams showing the process of lowering the energized termination 8 to the seabed.

[0090] First, a worker connects the wire rope 27 extending from the winch 26 of the work vessel SH to the eyebolt 83A of the energized termination 8 (step S41). Figure 40 is a schematic diagram showing the state in which the wire rope 27 is connected to the energized termination 8. The worker also connects the wire rope 28 of the crawler crane to the mobile termination 7, and uses the winch 26 and crawler crane to throw and lower the energized termination 8 into the sea (step S42). Figure 41 is a schematic diagram showing the state in which the energized termination 8 is thrown into the sea.

[0091] When the energized termination 8 that has been thrown into the sea reaches the seabed, the diver DV removes the wire ropes 27 and 28 (step S43). Since the array cables 2A and 2B are connected in series in the energized termination 8, even if the offshore platform 1 is removed from the wind farm for maintenance, the power generated by the wind farm can be sent to the substation.

[0092] Next, we will explain the process of connecting the array cables 2A, 2B to the offshore platform 1 after maintenance has been completed. When connecting the array cables 2A, 2B to the offshore platform 1 after maintenance has been completed, the energized termination 8 is pulled up to the work vessel SH and disassembled, and the mobile termination 7 is assembled on the work vessel SH. Next, the assembled mobile termination 7 is pulled up to the connection boxes 30A, 30B, and the mobile termination 7 is disassembled inside the connection boxes 30A, 30B. The power line 203 is connected to the section cable 131, and the optical cable 205 is connected to the optical cable connection box 36.

[0093] 43 is a flowchart showing the process flow for connecting array cables 2A, 2B to an offshore platform 1 for which maintenance has been completed. First, a diver DV connects wire ropes 27, 28 to an energized termination 8 on the seabed (step S51). Next, a worker uses a winch 26 and a crawler crane to pull the energized termination 8 to the work vessel SH (step S52). The worker then hoists the energized termination 8 that has been pulled to the work vessel SH onto the work vessel SH (step S53).

[0094] Next, the worker disassembles the energized termination 8 on the work vessel (step S54).The worker then assembles the mobile termination 7 in the same manner as described above (step S55).The worker connects the wire ropes 27 and 28 to the mobile termination 7 and uses the winch 26 and crawler crane to throw the mobile termination 7 into the sea (step S56).Next, the diver DV connects the wire rope 22 of the offshore platform 1 that has completed maintenance to the mobile termination 7 and removes the wire ropes 27 and 28 (step S57).

[0095] Next, the worker uses winch 20 to pull mobile termination 7 into junction boxes 30A, 30B (step S58). The worker disassembles mobile termination 7 inside junction boxes 30A, 30B (step S59). The worker then assembles device direct connection terminals 5A, 5B at the ends of power lines 203, connects power lines 203 to section cables 131, and connects optical cables 205 to optical cable junction boxes 36 (step S60).

[0096] As described above, according to this embodiment, the dead-end portion 4 is part of the movable termination 7, and the dead-end portion 4 is part of the energized termination 8, which facilitates the assembly of the movable termination 7 and the energized termination 8. Furthermore, the dead-end portion 4 that supports the array cable 2 in the connection box 30 can be shared by both the movable termination 7 and the energized termination 8, thereby reducing costs. Furthermore, the lengths of the power wire 203 and the optical cable 205 exposed beyond the dead-end portion 4 are not changed, so the movable termination 7 and the energized termination 8 can be assembled without changing the distance from the dead-end portion 4 to the tip of the power wire 203 and the distance from the dead-end portion 4 to the tip of the optical cable 205. Furthermore, the energized termination 8 connects the array cable 2A and the array cable 2B in parallel, which reduces the overall length of the energized termination 8.

[0097] Furthermore, in the energized termination 8, because three sets of direct device connection terminals 5A, 5B are stored in the protective body 82, the volume of the protective body 82 can be reduced and the water pressure resistance can be increased compared to a structure in which each set of direct device connection terminals 5A, 5B is stored in a waterproof container. Furthermore, because the three sets of direct device connection terminals 5A, 5B are stored together in the protective body 82, it is easy to ensure working space for connecting the direct device connection terminals 5A, 5B, and it is possible to reliably waterproof the terminals after checking the connection between the connectors, and to check the electrical connection. Furthermore, because the energized termination 8 is submerged in the seabed, it is possible to reduce damage from waves and ocean currents, weight increase due to marine loss, and contact with marine organisms.

[0098] [Modifications] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and can be implemented in various other forms. For example, the above-described embodiments may be modified as follows to implement the present invention. The above-described embodiments and the following modifications may be combined with each other. The present invention also includes configurations in which the components of the above-described embodiments and modifications are appropriately combined. Furthermore, further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the present invention are not limited to the above-described embodiments and modifications, and various modifications are possible.

[0099] In the present invention, the ends of the three power lines 203 are individually housed in the waterproof pipes 61, but it is also possible to have a structure in which all three are housed together in one waterproof pipe 61. Also, in the above-described embodiment, the device direct connection terminal 5A is disassembled and the stress cone 57 and terminal 53 are housed in the waterproof pipe 61, but the device direct connection terminal 5A may also be housed in the waterproof pipe 61 without being disassembled.

[0100] In the present invention, a bend stiffener 18 may be attached to the moving termination 7. If the bend stiffener 18 can be attached to the moving termination 7, bending of the array cable 2 near the moving termination 7 can be suppressed while the moving termination 7 is moving.

[0101] Since the power line 203 transmits electricity when the offshore platform 1 is in operation, it is preferable that the components of the energized termination 8 are made of a non-magnetic material to suppress heat generation due to induction. Note that the components of the energized termination 8 may be made of copper, aluminum, or titanium.

[0102] In the above-described embodiment, the array cable 2A and the array cable 2B are connected in parallel at the conductive termination 8, but in the present invention, the array cable 2A and the array cable 2B may also be directly connected.

[0103] 44 is a plan view of a clamp 43A, which is a modified example of the clamp 43 of the movable termination 7. The clamp 43A has a through hole 443 through which the array cable 2 passes, and multiple bolt holes 441 and 442. The bolt hole 441 is a hole through which a bolt is passed to fasten the adapter 35 and the clamp 43A. The bolt hole 442 is a hole through which a bolt is passed to fasten the flange 74 and the clamp 43A. The distance from the center of the clamp 43A to the center of the bolt hole 442 is shorter than the distance from the center of the clamp 43A to the center of the bolt hole 441. When assembling the movable termination 7, if the retaining unit 4 includes the clamp 43A, the flange 74 and the clamp 43A are fastened together with a bolt passed through the bolt hole 442, and the bolt fastening the adapter 35 and the clamp 43A is removed. In this structure, the flange 74 can be attached to the retaining portion 4 without suspending the retaining portion 4, while the retaining portion 4 is supported by the adapter 35. The clamp portion 43A may have a half-split structure.

[0104] In the above-described embodiment, the stud bolt 87 is attached to the fastening portion 4, but the method of attaching the stud bolt 87 to the fastening portion 4 is not limited to the method of the embodiment. Figures 45A and 45B are views showing an example of a modified method of attaching the stud bolt 87 to the fastening portion 4. As shown in Figure 45A, the end of the clamp portion 43 may be sandwiched between plate-like members 45A and 45B, and the stud bolt 87 may be attached to the fastening portion 4 by attaching the stud bolt 87 to the plate-like members 45A and 45B. Alternatively, as shown in Figure 45B, the stud bolt 87 may be attached to the fastening portion 4 by fixing the plate-like member 45A to the end of the clamp portion 43 with a bolt 46, and attaching the stud bolt 87 to the plate-like member 45A.

[0105] In the above-described embodiment, the retaining portion 4 is not disassembled and becomes part of the movable termination 7 and the energized termination 8, but if the distance from the bottom plate 81 to the retaining portion 4 does not match when assembling the energized termination 8, the retaining portion 4 may be reassembled in the connection box 30A, 30B or the work boat SH.

[0106] In the embodiment described above, the wedge 41 is fixed to the iron wire armor 223, but it may also be fixed to the outer sheath 225.

[0107] In the present invention, the structure of the waterproofing treatment portion 62 is not limited to the structure of the embodiment, and other structures may be used. For example, the waterproofing treatment portion 62 may be configured to include an aluminum water-blocking shrinkable tube inside the heat-shrinkable tube 622. Furthermore, the waterproofing treatment portion 62 may be configured to include an epoxy glass tape inside the heat-shrinkable tube 622.

[0108] In the conductive termination 8, the power line 203 of the array cable 2A and the power line 203 of the array cable 2B are connected by the device direct connection terminals 5A and 5B, but they may be connected by a connector other than the device direct connection terminals.

[0109] In FIG. 13 , a waterproof pipe 61 is provided for each power line 203, and the end of each power line 203 is individually inserted into the waterproof pipe 61. However, as shown in FIG. 17C , the ends of multiple power lines 203 may be bundled and inserted into a single waterproof container made of hollow metal with one longitudinal end closed and the other end open, and the open end of the waterproof container may be waterproofed. This waterproof container is an example of a waterproof section according to the present invention. Furthermore, when the ends of multiple power lines 203 are bundled and inserted into a single waterproof container, the open side through which the power lines 203 are inserted may be provided with the structure of the lower metal fitting 89 described above, and the lower metal fitting 89 may be waterproofed. In this modified example, the waterproof container may be fixed to the fastening section 4 with a stud bolt. In this manner, the waterproof section functions as a protective section, and the conductor ends can be waterproofed and housed in the protective section.

[0110] 46A and 46B show an example in which the connector of the electrical termination includes a slotted angle bracket with multiple bolt holes, as described above. FIG. 46A is a side view, and FIG. 46B is a bottom view. In the example shown in FIGS. 46A and 46A, the clamp 43A shown in FIG. 44 is used as the clamp. Furthermore, instead of the stud bolt 87 used as the connector in the electrical termination 8 shown in FIG. 30, the electrical termination 8A shown in FIGS. 46A and 46B uses a connector 87A. The connector 87A includes a slotted angle bracket 87Aa, a mounting bracket 87Ab, and a mounting jig 87Ac. The mounting bracket 87Ab is a bracket for attaching the slotted angle bracket 87Aa to the bottom plate 81 and is fixed to the slotted angle bracket 87Aa and the bottom plate 81 with bolts or the like. The attachment jig 87Ac is a jig for connecting the perforated angle 87Aa and the clamp portion 43A, and is fixed to the perforated angle 87Aa and the bottom plate 81 by using the bolt holes 441 of the clamp portion 43A.

[0111] REFERENCE SIGNS LIST 1 Offshore platform 2 Array cable 4 Retaining portion 5A, 5B Equipment direct connection terminal 7 Mobile termination 8 Power-carrying termination 30A, 30B Junction box 203 Power line 205 Optical cable WF Wind farm

Claims

1. The steps of removing, from an offshore wind power facility, the conductors of a first cable and a second cable which are connected in series to the offshore wind power facility to transmit electric power; providing a first protection part which has a waterproofing part for waterproofing the conductor end of the removed first cable and protects the conductor end, assembling the first protection part by fixing the first protection part to a retaining part which fastens the first cable to the offshore wind power facility, assembling the mobile body by providing a second protection part which has a waterproofing part for waterproofing the conductor end of the removed second cable and protects the conductor end, assembling the mobile body by fixing the second protection part to a retaining part which fastens the second cable to the offshore wind power facility; suspending the mobile body from the offshore wind power facility with a wire rope to anchor it in the sea; hoisting the mobile body anchored in the sea onto a work boat; dismantling the mobile body which has been raised onto the work boat; connecting the conductor end of the first cable and the conductor end of the second cable which were stored in the mobile body; A cable connection method comprising the steps of: assembling a connection body having a sealed protective body that houses the connected conductor ends; fixing the protective body to the retaining portion of the first cable and the protective body to the retaining portion of the second cable using a connector; and lowering the connection body to the seabed.

2. The cable connection method described in claim 1, wherein the first cable and the second cable include optical cables, and in the moving body, ends of the optical cables are waterproofed and stored in the first and second protective parts, and in the connecting body, the optical cable of the first cable and the optical cable of the second cable are connected and stored in the protective part.

3. The cable connection method according to claim 1, wherein the first cable and the second cable each have a plurality of core wires.

4. The cable connection method according to claim 3, wherein in the step of waterproofing the conductor end, the conductor end is waterproofed for each of the plurality of core wires.

5. The cable connection method described in claim 1, wherein the offshore wind power facility has a riser pipe through which the first cable is passed from the sea in a hollow portion thereof, and a riser pipe through which the second cable is passed from the sea in a hollow portion thereof, and the moving body is capable of passing through the riser pipe.

6. A cable connection method as described in claim 1, wherein in the step of hoisting the moving body onto a work boat, the moving body suspended by a wire rope of the offshore wind power facility and stopped in the sea is reconnected to the wire rope of the work boat, and the moving body is hoisted onto the work boat by the wire rope of the work boat.

7. The cable connection method according to claim 1, wherein seawater enters the inside of the first protection section and the second protection section when in the sea.

8. A cable connecting method as set forth in claim 1, wherein the distance between said protective body and the retaining portion of said first cable and the distance between said protective body and the retaining portion of said second cable are adjusted by said connecting tool.

9. A cable connection method as described in claim 1, wherein the connector is a stud bolt, and the distance between the protective body and the retaining portion of the first cable and the distance between the protective body and the retaining portion of the second cable are individually adjusted by the stud bolt.

10. A cable connection method as described in claim 1, wherein the conductor end housed in the protective body is fixed inside the protective body, and a part for fixing the conductor end is made of a non-magnetic material.

11. A cable connection method as described in claim 3, wherein the conductor ends of the first cable and the second cable are stored inside the protective body through holes provided in the protective body, and the holes through which the first cable and the second cable pass are waterproofed.

12. A mobile body comprising: a waterproofing section that waterproofs the conductor end of a cable that is connected in series to an offshore wind power generation facility to transmit electric power; a protection section that protects the conductor end and is fixed to a retaining section that fastens it to the offshore wind power generation facility; and a hoisting device to which a rope that suspends the protection section is tied.

13. The moving body according to claim 12, wherein the protective section is configured so that seawater can flow into the protective section when in the sea.

14. A connection comprising: a connection part that connects the conductor ends of a first cable and a second cable that are connected in series to an offshore wind power generation facility to transmit electric power; a sealed protective body that houses the connection part; a retaining part that secures the protective body and the first cable to the offshore wind power generation facility, and a coupling device that secures the protective body and the retaining part that secures the second cable to the offshore wind power generation facility.

15. The connection body according to claim 14, wherein the coupling adjusts the distance between the protection body and the retaining portion of the first cable and the distance between the protection body and the retaining portion of the second cable.

16. The connection body according to claim 14, in which the two retaining portions are fixed to the protective body as a single unit.

17. The connection body according to claim 14, wherein the two retaining portions are fixed to the protective body individually and independently.

18. The connection body according to claim 14, wherein the protective body has a position adjustment and fixing part for adjusting and fixing the positions of the first and second cables within a sealed interior.

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