Marine cable fixing support method

Abstract

The present invention relates to a method for fixing and supporting a marine cable, and more specifically, when a marine cable is installed and fixed within various pre-set marine structures, if only a hang-off assembly is installed to fix the cable, there is a problem in that the waiting time of the lifting vessel positioning the cable in the structure is prolonged and the manpower and costs increase accordingly. Therefore, the invention relates to a method for fixing and supporting a marine cable that has the effect of shortening the waiting time of the lifting vessel, reducing manpower and costs, and increasing work efficiency compared to the existing installation method, by additionally providing a cable holding clamp in a form embedded inside the hang-off assembly before the hang-off assembly, thereby enabling the cable to be securely supported and fixed within the structure for a pre-set time through the cable holding clamp, and then proceeding to the step of installing the hang-off assembly.

Description

Technology Field

[0001] The present invention relates to a support method that enables easy and stable support and fixation of a cable within a structure while reducing costs and time and increasing efficiency, through an installation method of a hang-off assembly in which a cable holding clamp is secured internally when installing and fixing a marine cable within a pre-set structure at sea. Background Technology

[0002] The anchoring of submarine cables inside conventional offshore wind turbines was achieved solely by hang-off assemblies.

[0003] The assembly of the hang-off takes about 2 hours. According to the work sequence, the assembly of the hang-off must be carried out while the submarine cable lifting vessel has pulled the submarine cable above the water surface, and during this time, the submarine cable lifting vessel must remain in the lifted state for the duration of the operation.

[0004] There are multiple offshore wind turbines, and due to the nature of submarine cables requiring continuity in installation, massive time, manpower, and costs are consumed as massive cable lifting vessels must remain on standby for the entire duration of the hang-off assembly process; furthermore, operations are inevitably delayed if sea weather conditions are poor. (In other words, since the submarine cable could only be secured and moved on to the next stage after all assembly processes of the hang-off assembly were completed, having separate equipment capable of holding the cable for a short period would allow the remaining work to proceed by transferring the cable to smaller boats after the lifting vessel has departed, once the cable is temporarily secured.)

[0005] Accordingly, there is an urgent need to develop a device capable of supporting and securing such submarine cables for a short period or for a set duration, without the waiting time of the lifting vessel or the installation of the hang-off assembly, or before the installation of the hang-off assembly. Prior art literature

[0006] Republic of Korea Registered Patent Publication No. 10-1467113 (Registered Nov. 24, 2014) The problem to be solved

[0007] The present invention has been devised to solve the aforementioned problems. The objective of the present invention is to provide a method for safely and efficiently fixing and installing a marine cable inside an offshore tower or offshore wind power structure, wherein the cable, which is vertically erected on a base plate inside the offshore structure, is fixed in position using a cable holding clamp, thereby reducing the waiting time of the lifting vessel that is vertically suspending and fixing the cable. Furthermore, in this state, a hang-off assembly is installed on the exterior of the cable holding clamp in a manner that encloses and wraps the cable holding clamp, thereby ensuring that the cable is securely and stably fixed.

[0008] The cable holding clamp is manufactured from MC nylon material suitable for marine environments to ensure lightweight, insulation, and corrosion resistance, and its inner periphery forms an anti-slip section to enable secure fixation and support of the cable. By integrally installing this cable holding clamp within the hang-off assembly to form a single configuration,

[0009] The present invention provides a marine cable fixing and support method that resolves the long waiting times, increased manpower, and higher costs associated with using only conventional hang-off assemblies by supporting and fixing the cable through a cable holding clamp.

[0010] Other objects and advantages of the present invention will be described below and will be known from the embodiments of the present invention. Additionally, the objects and advantages of the present invention may be realized by means and combinations set forth in the claims. means of solving the problem

[0011] The present invention has been devised to solve the above-mentioned problems, and

[0012] Step (S100) of placing a cable (C) upright in the center of a base plate (10) inside an offshore tower or offshore wind structure, which is the object to be installed, via a submarine cable lifting vessel;

[0013] A step (S200) in which a cable holding clamp (20) is assembled and mounted on the outer circumference of a cable (C) on the upper part of a base plate (10) within the object to be installed, through a worker or work machine within the object to be installed, thereby fixing and supporting the cable (C);

[0014] A step (S300) of installing a hang-off assembly (30) in which a cable (C) is fixedly supported by being fixedly installed at the lower end of the base plate (10), while wrapping the cable holding clamp (20) so as to be installed on the upper part of the base plate (10) within the object to be installed through a worker or work machine within the object to be installed;

[0015] Step (S400) in which, through a worker or work machine within the object to be installed, the outer sheath is removed from the cable exposed above the hang-off assembly (30) and the wire sheath is spread out and arranged at preset intervals on the upper surface of the hang-off assembly (30), wherein the ends of the wire sheath are cut to align with the outer line of the top of the hang-off assembly (30);

[0016] A step (S500) in which an upper flange portion (37) is correspondingly assembled on the upper part of the wire outer casing through a worker or work machine within the object to be installed;

[0017] Step (S600) of injecting resin into the hang-off assembly (30) to a preset depth inside through the wires vertically exposed in the center of the upper flange portion (37) via a resin injection device within the object to be installed;

[0018] A step (S700) in which a grounding line is installed on the hang-off assembly (30) and the upper flange portion (37) through a worker or work machine within the object to be installed;

[0019] It is characterized by being composed of. Effects of the invention

[0020] As described above, the present invention has the effect of supporting and fixing a submarine cable for a preset time prior to the waiting time of the lifting vessel and the installation of the hang-off assembly, thereby increasing work efficiency and stability and reducing operating costs.

[0021] In addition, the present invention has an efficient structure in which a cable holding clamp is secured internally within a hang-off assembly, which has the effect of stably gripping the cable and preventing displacement during installation.

[0022] In addition, the present invention uses MC nylon material for the cable holding clamp, thereby providing the effects of corrosion prevention in marine environments, lightweighting, insulation, and corrosion resistance. Brief explanation of the drawing

[0023] FIGS. 1 and FIGS. 2 are flowcharts of an embodiment illustrating a fixed support method according to the present invention. FIGS. 3 to 5 are drawings of an embodiment showing the assembly of a cable holding clamp and a hang-off assembly according to the present invention. FIG. 6 is a conceptual diagram of an embodiment showing the tightening (fastening) sequence of a joint bolt according to the present invention. FIGS. 7 to 9 are drawings of an embodiment showing a cable holding clamp according to the present invention. FIGS. 10 and FIGS. 11 are drawings of an embodiment showing a cable holding clamp according to the present invention fixed to a cable. FIG. 12 is a drawing of an embodiment showing a hang-off assembly according to the present invention. FIG. 13 is a drawing of an embodiment showing a submarine cable fixing force test conducted by KOMERI (Korea Marine Equipment Research Institute) to ensure the fixing force of the cable holding clamp according to the present invention. FIGS. 14 to 17 are test results of passing the accredited test of FIG. 13. Specific details for implementing the invention

[0024] Before describing various embodiments of the present invention in detail, it will be understood that the application is not limited to the details of the configuration and arrangement of components described in the following detailed description or illustrated in the drawings. The present invention may be embodied and practiced in other embodiments and may be carried out in various ways. Furthermore, it will be understood that the expressions and terms used herein regarding device or element orientations (e.g., "front," "back," "up," "down," "top," "bottom," "left," "right," "lateral") are used merely to simplify the description of the present invention and do not indicate or imply that the related device or element must simply have a specific orientation. Additionally, terms such as "first" and "second" are used in this and the appended claims for illustrative purposes and are not intended to indicate or imply relative importance or intent.

[0026] The present invention has the following features to achieve the above objective.

[0027] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, and should be interpreted in a meaning and concept consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0028] Therefore, it should be understood that the embodiments described in this specification and the configurations illustrated in the drawings are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention, and that various equivalents and modifications that can replace them may exist at the time of filing this application.

[0031] Hereinafter, a method for fixing and supporting a marine cable according to a preferred embodiment of the present invention will be described in detail with reference to FIGS. 1 to 17.

[0033] The method for fixing and supporting a marine cable according to the present invention is used when installing a cable (submarine cable, etc., C) within a marine tower or offshore wind power structure, which is the object of installation. By temporarily supporting and fixing the cable using a cable holding clamp (20) before installing the hang-off assembly (30), the working time and operating costs of the lifting vessel and marine crane can be reduced, and the cable (C) can be stably held without the need for separate cable (C) fixing work or the installation of a fixing device, while preventing the cable (C) from moving out of position within the object of installation.

[0034] 1. A step (S100) in which a cable (C) is positioned upright in the center of a base plate (10) inside an offshore tower or offshore wind structure, which is the object to be installed, via a submarine cable lifting vessel:

[0035] This is the step of inserting the cable (C) into the hole in the center of the base plate (10) inside the object to be installed using the marine crane of the lifting vessel, and positioning it vertically to create an upright position.

[0038] 2. A step (S200) in which a cable holding clamp (20) is assembled and mounted on the outer circumference of the cable (C) on the upper part of the base plate (10) within the object to be installed, through a worker or work machine within the object to be installed, thereby fixing and supporting the cable (C):

[0039] In step S100, if the cable (C) is maintained in a state of being vertically suspended in the center of the offshore structure through a marine crane installed on the offshore lifting vessel, the cable (C) is supported and fixed to the upper surface of the base plate (10) prior to the hang-off assembly (30) through the cable holding clamp (20) of the present invention.

[0040] Due to the support and fixing step of the cable (C) through such a cable holding clamp (20), the lifting vessel had to be kept at sea for a long time until the cable (C) was completely fixed to the structure using only one hang-off assembly (30). This involved various risks of exposure to weather or surrounding environment, as well as the consumption of enormous amounts of time, manpower, and costs, but the present invention makes it possible to reduce this.

[0041] The above cable holding clamp (20) is a fixing device that wraps around the outer circumference of the cable (C) on the upper surface of the base plate (10) and fixes its position while the cable (C) is suspended and positioned in a state where it is vertically penetrating the center of the base plate (10) within the installation target by the marine crane of the submarine cable lifting vessel.

[0042] To explain the configuration of the cable holding clamp (20) in more detail, the cable holding clamp (20) is composed of a first clamp (21), a second clamp (22), and a fastener (23).

[0043] The first clamp (21) is a clamp having a semicircular cross-section or a 'C'-shaped cross-section to correspond to and wrap around the outer circumference of the cable (C).

[0044] The second clamp (22) has the same shape as the first clamp (21) described above and is positioned opposite the first clamp (21) to wrap around the outer circumference of the cable (C). It is a clamp positioned opposite the first clamp (21) to wrap around the cable (C) while maintaining a distance between the two ends so that they do not come into contact. That is, the first and second clamps (21, 22) have the same shape, but when wrapping around the outer circumference of the cable (C), the ends of the first and second clamps (21, 22) are spaced apart so that they do not come into contact with each other. This is intended to allow the distance between the ends of the first and second clamps (21, 22) to narrow or widen depending on the size (thickness) of the cable (C).

[0045] The above-mentioned plurality of fasteners (23) are fixing means for connecting the left and right spacing spaces (24) of the first and second clamps (21, 22) to each other, and are in the form of long bolts with screw threads formed on their outer circumferences, and have a shape in which nuts are tightened at each end.

[0046] In the present invention, three such fasteners (23) are formed on each side of the first and second clamps (21, 22) (of course, the number of fasteners (23) can be varied depending on the user). In order to securely fix the cable (C) using the cable holding clamp (20), the fasteners are tightened step by step using a torque wrench in the order of the left fastener and right fastener located in the middle of the first and second clamps (21, 22), the right fastener and left fastener located at the top of the first and second clamps (21, 22), and the right fastener and left fastener located at the bottom of the first and second clamps (21, 22). At this time, the tightening operation is performed repeatedly until a clicking sound is continuously produced from the torque wrench, and the torque sequencer, which is the torque adjustment range of the torque wrench, is set to 220~260 Nm. (Based on 7 tons for a maximum cable (C) length of 50M, and 21 tons with a safety factor of 3 times.)

[0047] The calculation formula of the above-mentioned torque sequencer will be explained below with reference.

[0048] The above fastener (23) consists of a bolt, a nut, a flat washer, and a spring washer.

[0049] (1) Bolt used M16 × 2.09, strength 10.9 (actual strength).

[0050] At strength 10.9, yield load: 14.4 ton (141,300 N), breaking load: 16 ton (157,000 N).

[0051] (2) Coefficient of friction (μ) = 0.5 (when internal irregular structure)

[0052] (3) It is a structure that is supported by frictional force for the purpose of preventing cable slippage.

[0053] F마찰력 = μ × F 축력

[0054] F 축력 = F 마찰력 / μ = 3,500kgf / 0.5 = 7,000kgf

[0055] (Based on 21 tons, there are 6 bolts, so 21 tons / 6 = 3.5 tons (per bolt))

[0056] 7,000 × 9.8 = 68,600N

[0057] 4) Tightening torque T = k × F × d (Steel bolt k=0.2)

[0058] (Torque coefficient) × (Bolt axial force (N)) × Bolt nominal diameter (m) =

[0059] 0.2 ×68,600N × 0.016m = 219.5Nm

[0060] Therefore, at 21 tons, the tightening torque is 219.5 Nm

[0061] If you apply the above formula,

[0062] The tightening torque is 261.3 Nm at 25 tons.

[0063] The tightening torque is 313.6 Nm at 30 tons

[0064] The tightening torque is 418.1 Nm at 40 tons.

[0065] In conclusion, the appropriate tightening torque is 219.5 ~ 261.3 Nm (21 ton ~ 25 ton),

[0066] It is approximately 220 to 262 N.m.

[0068] In addition, the cable holding clamp (20) in the present invention has a groove (25) formed in a transverse direction perpendicular to the vertically erected cable (C) on the inner circumference that contacts the cable (C), and the groove (25) is formed continuously in a downward direction like screw threads to form an anti-slip portion (26), thereby preventing slippage by engaging with the outer sheath of the cable (C) and reducing the cable holding clamp (20) and damage to the cable (C) through the load distribution effect of the cable (C). The protruding portion between the grooves (25) in the anti-slip portion (26) forms a flat portion (27) that makes surface contact with the outer circumference of the cable (C), and has a trapezoidal shape of a projection (28) that gradually narrows toward the cable (C).

[0069] In addition, the cable holding clamp (20) is made of MC (Mono Cast) Nylon material to provide corrosion prevention, lightweighting, insulation, and corrosion resistance in a marine environment.

[0070] This MC Nylon has excellent tensile strength (81 MPa) and tensile modulus (3.2 GPa), and is about one-third lighter than metal, with excellent wear resistance, salt water resistance, and insulation properties, so it does not rust and is environmentally friendly due to its high recyclability.

[0071] With a lightweight and non-corrosive structure, corrosion and rust do not occur even under conditions of exposure to salt and moisture in the marine environment, and the weight is reduced by about 40~80% compared to aluminum (Al 2.7g / cm³) and SCM440 (7.8g / cm³), thereby reducing the operating load of marine cranes, improving work efficiency, and reducing maintenance costs.

[0072] The aforementioned tensile strength of 81 MPa is similar to that of general structural aluminum (approx. 90 MPa), ensuring sufficient structural rigidity when gripping the cable (C) and minimizing deformation caused by cable (C) load, vibration, and waves (sea shaking).

[0073] In addition, since the cable holding clamp (20) is formed of MC (Mono Cast) nylon material, it has a high elastic recovery force with a tensile elongation of 35% and can be restored without cracking when subjected to impact load or repeated fastening, so it has the effect of maintaining stability even with vibration and changes in cable (C) tension when installing a marine tower.

[0074] item MC Nylon Aluminum (AL) / Special Steel (SCM440) note weight About 1 / 3 to 1 / 6 High weight increases risk during offshore operations Easy to install and handle Corrosion resistance Excellent (non-metallic) Corrosion may occur at sea, requiring regular maintenance. No corrosion or painting required insulating Excellent electrical insulation Conductive presence, insulation supplement required Improvement of electrical safety eco-friendliness Recyclable Surface treatment (plating / painting) required, environmental burden No marine pollution-causing factors unit price Cheap High material and processing costs

[0077] 3. A step (S300) in which a cable (C) is fixedly supported by a hang-off assembly (30) having its lower part fixedly installed on the base plate (10), while wrapping the cable holding clamp (20) so as to be installed on the upper part of the base plate (10) within the object to be installed through a worker or work machine within the object to be installed:

[0078] In the step of installing a hanging assembly (30) to more securely fix and support the cable (C) while the cable (C) is supported and fixed within the structure by a cable holding clamp (20) through the aforementioned S200, the cable holding clamp (20) is fixed by wrapping around the outer circumference of the cable (C) on the upper surface of the base plate (10) to prevent the cable (C) from slipping downward, whereas in the step of S300, the hanging assembly (30) has the cable holding clamp (20) mounted internally and its bottom surface fixed to the upper surface of the base plate (10) to more securely support and prevent the cable (C) from slipping downward.

[0079] The above-described hang-off assembly (30) is installed by wrapping around the outside of the cable holding clamp (20) so that the aforementioned cable holding clamp (20) is embedded therein, and its lower part is fixedly installed on the base plate (10), thereby being a fixing device that fixes the position of the cable (C) while keeping it float.

[0080] In the case of such a hang-off assembly (30), it consists of a first lower flange (31), a second lower flange (35), and a joint bolt (36).

[0081] The first lower flange (31) is a part that surrounds the cable (C) while forming an insertion space (A) inside into which the first clamp (21), which is half of the cable holding clamp (20), is inserted, and is composed of a body part (32) and upper and lower flanges (33, 34) located on the upper and lower sides of the body part (32).

[0082] The second lower flange (35) has the same shape as the first lower flange (31) and surrounds the cable (C) while forming an insertion space (A) inside into which the second clamp (22), which is the remaining half of the cable holding clamp (20), is inserted. By being combined with the first lower flange (31), it has a cylindrical shape with plate-shaped flanges formed on the left and right sides. The assembled first and second lower flanges (31, 35) must have their upper and lower ends closed so that the cable holding clamp (30), which is mounted in the internal insertion space (A), does not fall out downwards (the lower part of the cable holding clamp (20) is placed on the upper surface of the lower flange (34)), while having a shape in which only a central hole is drilled in the upper and lower center so that the cable (C) can vertically penetrate the center of the first and second lower flanges (31, 35).

[0083] According to an embodiment of the user, the hang-off assembly (30) may be further provided with a fixing hole (41) and a fixing means (42) that fix the cable holding clamp (20) and the hang-off assembly (30) by penetrating the outer circumference of the first lower flange (31) or the second lower flange (35) or the first and second lower flanges to the outer circumference of the internal cable holding clamp (20), and being fastened to a corresponding groove (40) formed on the outer circumference of the cable holding clamp (20), more specifically on the outer circumference of the first clamp (21) or the second clamp (22) or the first and second clamps (21, 22).

[0084] Additionally, an inwardly recessed keyway (43) is formed at the lower outer circumference of either the first clamp (21) or the second clamp (22), or at each of the first clamp (21) and the second clamp (22). When the first and second clamps (21, 22) are mounted within the hang-off assembly (30), a key (44) welded to the inner lower portions of the first lower flange (31) and the second lower flange (35) constituting the hang-off assembly (30) corresponds to and is joined, thereby enabling the support of the load of the cable (C). More specifically, the presence of such a key (44) and keyway (43) enables a rapid and accurate connection between the cable holding clamp (20) and the hang-off assembly (30) in a marine cable work environment where shaking due to waves is severe.

[0085] The joint bolt (36) is a plurality of fixing bolts (fixing means) that connect and fix the body portions (32) of the first and second lower flanges to each other, and connect and fix the second lower flange (35) and the base plate (10).

[0088] 4. A step (S400) in which, through a worker or work machine within the object to be installed, the outer sheath is removed from the cable (C) exposed above the hang-off assembly (30) and the wire sheath is spread out and arranged at preset intervals on the upper surface of the hang-off assembly (30), wherein the ends of the wire sheath are cut to align with the outer line of the top of the hang-off assembly (30);

[0089] 5. Step (S500) in which an upper flange portion (37) is correspondingly assembled on the upper part of the above wire outer casing:

[0090] The outer serving layer of the cable (C) is removed from the upper surface of the upper flange (33) to expose the wire sheath (C1) to the outside. The wire sheath (C1) is spread out at a preset interval on the upper surface of the upper flange (33), cut to match the end of the upper flange (33), and then the upper flange portion (37) is fixed to the upper flange (33) with a joint bolt (36) on the upper surface of the wire sheath (C1).

[0091] These upper flange portions (37) are composed of a first upper flange (38) and a second upper flange (39) in the shape of a semicircle plate that are opposite each other and form a circular plate, and the connection direction is rotated 90 degrees so as not to be the same as the installation direction of the first lower flange (31) and the second lower flange (35), and they are assembled to be opposite each other on the upper flange (33). (That is, if the first lower flange (31) and the second lower flange (35) are connected to each other in the front and rear directions, the first upper flange (38) and the second upper flange (39) are connected to each other in the left and right directions rather than in the front and rear directions.)

[0092] In addition, regarding the multiple joint bolts (36) used for connecting and fixing the second lower flange (35, more specifically the lower flange (34)) and the base plate (10), and connecting and fixing the upper flange (33) and the upper flange part (37), the multiple joint bolts (36) are arranged and fixed in a circular pattern, and the joint bolts (36) are tightened and fixed in the order of upper, lower, right, and left in a cross (+) shape centered on the center of the hang-off assembly, and the cross-shaped tightening is performed multiple times while moving clockwise by a preset angle, and the torque sequencer, which is the torque adjustment range of the torque wrench tightening the joint bolts (36), is 220~260 Nm, and the tightening operation is performed repeatedly at least three times until a continuous clicking sound is heard from the torque wrench.

[0093] (Numbers 1 through 12 in the drawing represent the locations where the joint bolts (36) are installed and indicate the tightening sequence. As shown in the example below, after tightening number 1, the opposite diagonal number 2 is tightened, and numbers 3 and 4, which form a cross shape, are tightened sequentially to perform the cross-shaped tightening operation. Afterwards, numbers 5, 6, 7, and 8 need to be tightened. The cross shape of numbers 1, 2, 3, and 4 is rotated clockwise by a preset angle to form the positions of numbers 5, 6, 7, and 8.)

[0096] 6. A step (S600) of injecting resin into the hang-off assembly (30) to a preset depth inside through the wires vertically exposed in the center of the upper flange portion (37) via a resin injection device within the object to be installed:

[0097] This is a step in which resin is injected through the optical fiber (C2) to a preset depth (preset depth inside the hang-off assembly (30)) through a separate rain injection part at the center of the upper flange part (37) where the optical fiber (C2) is exposed to the outside.

[0100] 7. A step (S700) in which a grounding line is installed on the hang-off assembly (30) (first and second lower flanges (31, 35)) and the upper flange portion (37) through a worker or work machine within the object to be installed:

[0101] It is a grounding line connected to the aforementioned hang-off assembly (30) (first and second lower flanges (31, 35)) and the upper flange section (37).

[0104] 8. A step (S800) in which an AI automatic monitoring sensor is installed on the hang-off assembly (30) through a worker or work machine within the object to be installed, so as to be able to check the assembly status and installation status of the hang-off assembly (30):

[0105] The device is pre-installed at a preset location within an object in which the aforementioned hang-off assembly (30) or the hang-off assembly (30) and cable holder clamp (20) are installed, and allows for various checks to be made via a display from a control room on land or outside, such as whether the joint bolt (36) in the hang-off assembly (30) has loosened or if corrosion has occurred, or if there are any problems in supporting and fixing the cable. Depending on the user's embodiment, a camera and various sensors may be the target.

[0109] As described above, although the present invention has been explained by limited embodiments and drawings, the present invention is not limited thereto and it is obvious that various modifications and changes are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs. Explanation of the symbols

[0110] 10: Base plate 20: Cable holding clamp 21: 1st clamp 22: 2nd clamp 23: Fastener 24: Separation distance 25: Home 26: Anti-slip part 27: Flat part 28: Protrusion 30: Hang-off assembly 31: First lower flange 32: Body part 33: Top flange 34: Bottom flange 35: Second bottom flange 36: Joint bolt 37: Upper flange 38: 1st upper flange 39: 2nd lower flange 40: Corresponding groove 41: Fixing hole 42: Fixing means 43: Keyway 44: Key C : Cable C1: Steel wire sheath C2: Optical fiber

Claims

Claim 1 A step (S100) in which a cable (C) is positioned upright in the center of a base plate (10) inside an offshore tower or offshore wind structure, which is the installation target, via a submarine cable lifting vessel; a step (S200) in which a cable holding clamp (20) is assembled and mounted on the outer circumference of the cable (C) on the upper part of the base plate (10) inside the installation target via a worker or work machine inside the installation target, thereby fixing and supporting the cable (C); a step (S300) in which a hang-off assembly (30) is installed on the upper part of the base plate (10) inside the installation target via a worker or work machine inside the installation target, with the lower part fixedly installed on the base plate (10) so as to wrap around the cable holding clamp (20) so as to be installed inside, thereby fixing and supporting the cable (C); and a step (S300) in which the outer sheath is removed from the cable exposed above the hang-off assembly (30) via a worker or work machine inside the installation target, and the steel wire sheath is spread out and arranged at preset intervals on the upper surface of the hang-off assembly (30). A step (S400) in which the end of the wire sheath is cut to align with the outer line of the top of the hang-off assembly (30); a step (S500) in which an upper flange portion (37) is correspondingly assembled on the upper part of the wire sheath through a worker or work machine within the object to be installed; a step (S600) in which resin is injected through a resin injection device within the object to be installed, through the wires vertically exposed in the center of the upper flange portion (37), to a preset depth inside the hang-off assembly (30); a step (S700) in which a grounding line is constructed on the hang-off assembly (30) and the upper flange portion (37) through a worker or work machine within the object to be installed; and an AI automatic monitoring sensor is installed on the hang-off assembly (30) to allow verification via a display from a control room on land or outside, etc., whether the joint bolt (36) in the hang-off assembly (30) has loosened, whether corrosion has occurred, or whether there are any problems in supporting and fixing the cable. Step (S800);It is composed of, and in step S200, the cable holding clamp (20) comprises: a first clamp (21) having a semicircular cross-section to correspond to and wrap around the outer circumference of the cable (C); a second clamp (22) having the same shape as the first clamp (21), facing the first clamp (21) to wrap around the outer circumference of the cable (C), and positioned facing the first clamp (21) to wrap around the cable (C) while maintaining a state where both sides do not come into contact and are spaced apart; and a plurality of fasteners (23) connecting the left and right spaced-away spaces (24) of the first and second clamps (21, 22) to each other.It is configured such that the distance between the first and second clamps (21, 22) on both sides can be adjusted to narrow or widen, thereby wrapping around and fixing the outer circumference of the cable (C) according to the thickness of the cable (C), and in step S200, in order for the cable holding clamp (20) to be securely fixed to the cable (C), the fasteners are tightened step by step with a torque wrench according to the order of the left and right fasteners located in the middle of the first and second clamps (21, 22), the right and left fasteners located at the top of the first and second clamps (21, 22), and the right and left fasteners located at the bottom of the first and second clamps (21, 22), and the tightening operation is performed repeatedly until a continuous clicking sound is heard from the torque wrench, and the torque sequencer, which is the torque adjustment range of the torque wrench, is 220~260 Nm, and the cable holding clamp (20) contacts the cable (C). On the inner circumference, a groove (25) is formed in a transverse direction perpendicular to the vertically erected cable (C), and a plurality of grooves (25) are formed continuously in a downward direction like screw threads to form an anti-slip portion (26), thereby interlocking with the outer sheath of the cable (C) to suppress slippage and, through the load distribution effect of the cable (C), prevent the cable holding clamp (20) from changing and reduce damage to the cable (C). The protruding portion between the grooves (25) in the anti-slip portion (26) forms a flat portion (27) that makes surface contact with the outer circumference of the cable (C) and has a trapezoidal shape of a projection (28) that gradually narrows toward the cable (C). The cable holding clamp (20) is made of MC (Mono Cast) nylon material, providing effects such as corrosion prevention in a marine environment, lightweighting, insulation, and corrosion resistance. The hang-off assembly (30) is half of the cable holding clamp (20). A first lower flange (31) that surrounds a cable (C) while forming an insertion space (A) into which a first clamp (21) is inserted, and is composed of a body part (32) and upper and lower flanges (33, 34) located on the upper and lower sides of the body part (32);A second lower flange (35) that surrounds the cable (C) while having the same shape as the first lower flange (31) and forming an insertion space (A) inside into which the second clamp (22), which is the remaining half of the cable holding clamp (20), is inserted; a plurality of joint bolts (36) that connect and fix the body portions (32) of the first and second lower flanges to each other and connect and fix the second lower flange (35) and the base plate (10); and an upper flange portion (37) in which the wire sheath (C1), which is exposed to the outside by removing the outer serving layer of the cable (C) from the upper flange (33), is spread out at a preset interval on the upper surface of the upper flange (33), cut to match the end of the upper flange (33), and then fixed to the upper flange (33) with joint bolts (36) on the upper surface of the wire sheath (C1). A method for fixing and supporting a marine cable, characterized in that, in the case of a plurality of joint bolts (36) used for connecting and fixing the second lower flange (35) and the base plate (10) and connecting and fixing the upper flange (33) and the upper flange part (37), the plurality of joint bolts (36) are arranged and fixed in a circular manner, and are tightened and fixed in the order of upper, lower, right, and left joint bolts (36) in a cross shape centered on the center of the hang-off assembly, and the cross-shaped tightening is performed multiple times while moving clockwise by a preset angle, and the torque sequencer, which is the torque adjustment range of the torque wrench tightening the joint bolts (36), is 220~260 Nm, and the tightening operation is performed repeatedly at least three times until a continuous clicking sound is produced from the torque wrench. Claim 2 A method for fixing and supporting a marine cable according to claim 1, wherein a key groove (43) that is recessed inward is formed at the lower outer circumference of the first clamp (21) or the second clamp (22), and when the first and second clamps (21, 22) are installed inside the hang-off assembly (30), a key (44) formed on the inner bottom surface of the hang-off assembly (30) corresponds to and is fastened, so that the cable holding clamp (20) and the hang-off assembly (30) can be quickly and accurately connected to each other, thereby enabling the cable (C) to support the load. Claim 3 A method for fixing and supporting a marine cable according to claim 1, wherein in step S300, the hang-off assembly (30) penetrates from the outer circumference of the hang-off assembly (30) to the corresponding groove (40) on the outer circumference of the inner cable holding clamp (20), and further comprises a fixing hole (41) and a fixing means (42) for fixing the cable holding clamp (20) and the hang-off assembly (30). Claim 4 A method for fixing and supporting a marine cable according to claim 1, wherein the upper flange portion (37) is composed of a first upper flange (38) and a second upper flange (39) that are opposite each other and form a disc, and is assembled on the upper flange (33) facing each other by rotating the connection direction 90 degrees so as not to be the same as the installation direction of the first lower flange (31) and the second lower flange (35). 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