A deep - water cable and its laying method

Abstract

The present invention relates to a deep-water cable and a laying method thereof. The deep-water cable mainly includes, from the inside to the outside, a conductor, a conductor shielding layer, an insulating layer, an insulation shielding layer, a water-blocking layer, a sealing tight sleeve layer, a sheath layer, an armor layer, and an anti-corrosion layer. A fiber optic sensing unit is provided inside the armor layer. The deep-water cable of the present invention reflects the change of the internal pressure field of the deep-water cable through the fiber optic sensing unit inside the cable, and monitors the location where a fault occurs, providing a basis for quickly eliminating the fault. In the laying method of the deep-water cable of the present invention, as the depth of the underwater monitor and the remotely operated underwater vehicle increases with the sinking of the cable, the clamping device grasps the cable with greater force, and the underwater monitor and the remotely operated underwater vehicle further closely adhere to the side of the cable, enabling accurate acquisition of monitoring data and precise remote control of the cable laying and sinking, making the cable laying process more accurate.

Description

Technical Field

[0001] The present invention relates to the field of wire and cable, and particularly to a deep - water cable and a laying method thereof. Background Art

[0002] The application of underwater cables is becoming more and more extensive, and there is a wide market demand in the fields of transformation of rivers, lakes and reservoir dams, construction of offshore wind power generation, trans - ocean power supply and transmission, etc.

[0003] Underwater cables also face many technical difficulties. For shallow - water scenarios, direct - burial cable laying is generally adopted. The construction difficulty is not great, and the requirements for additional functions of the cable are not high. However, deep - water cable laying puts forward more and higher requirements for the additional functions of the cable, such as higher moisture - proof, pressure - resistant, corrosion - resistant, etc. Statistical data shows that 95% of submarine cable damages are caused by human activities such as fishing and shipping, mainly external damages caused by fishing gear, ship anchors, etc. At the same time, marine geological activities will also bring uncertainties to the operation of submarine cables. Therefore, problems such as how to protect deep - water cables from damage caused by super - large self - weight, bad terrain, underwater animals, artificial offshore operations, etc., how to effectively monitor and manage underwater cables, and quickly and accurately locate faulty cables need to be solved. Also, during the cable - laying process, one end of the cable is usually fixed on the shore, and the cable - laying ship slowly sails towards the open sea, sinking the cable to the seabed while using an excavator that has sunk to the seabed for laying. During this period, underwater monitoring and remote control of the cable are required. However, as the cable sinks deeper, the underwater pressure becomes greater, and underwater monitoring and remote - control equipment may break away from the cable due to the huge underwater pressure, resulting in incorrect monitoring data, inability to accurately locate, and remote - control the cable to sink to the accurate position. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a deep - water cable that can timely monitor the location where a fault occurs and provide a basis for quickly eliminating the fault. The present invention also provides a deep - water cable laying method that can effectively monitor the cable and make the cable sink to the accurate position.

[0005] To achieve the above - mentioned purpose, the present invention can be realized through the following technical solutions:

[0006] A deep - water cable, from the inside to the outside, includes a conductor, a conductor shielding layer, an insulating layer, an insulating shielding layer, a water - blocking layer, a sealing tight - fitting layer, a sheath layer, an armor layer, and an anti - corrosion layer. An optical fiber sensing unit is arranged inside the armor layer.

[0007] Further, the conductor includes a central conductor and N layers of arc - shaped conductors tightly stranded around the central conductor.

[0008] Furthermore, the armor layer includes a first armor layer and a second armor layer from the inside to the outside, the first armor layer includes a plurality of first metal wires, the optical fiber sensing unit replaces one of the first metal wires, and is wound along the sheath layer together with the other first metal wires.

[0009] Furthermore, the second armor layer includes a plurality of second metal wires, and a winding direction of the second metal wires is opposite to a winding direction of the first metal wires.

[0010] Furthermore, the gaps between adjacent first metal wires and the gaps between adjacent second metal wires are sprayed with foam glue after winding is completed.

[0011] Furthermore, the conductor shielding layer and the insulating shielding layer are both semiconductor wrappings; the insulating layer is cross-linked polyethylene extrusion; the water-blocking layer is filled with water-blocking powder; the sealing tight sleeve layer is a metal tube; the sheath layer is a weather-resistant polyethylene sheath; and the anti-corrosion layer is composed of a combination of polypropylene and asphalt.

[0012] A method for laying a deepwater cable comprises the following steps:

[0013] One end of the cable is fixed on the shore, and the cable laying vessel carries the cable laying device and lays the cable along the designed route;

[0014] Underwater monitors and underwater remote control vehicles are used to continuously monitor and adjust, control the forward speed, direction and cable laying speed of the cable-laying vessel, so as to avoid uneven places and rocks and avoid damaging the cable; clamping devices are provided between the underwater monitors and the underwater remote control vehicles and the cables, and the clamping devices have greater force in grabbing the cable as the depth of the cable sinks.

[0015] Furthermore, a sheath with grooves is installed on the surface of the cable, and the clamping device includes a first clamping part, a second clamping part and a control device, and the first clamping part and the second clamping part grab and clamp the grooves of the sheath of the cable, and a PLC and a motor are arranged inside the control device, and the signal output end of the PLC is connected to the input end of the motor, and the output shaft of the motor is transmission-connected to the first clamping part, and a pressure sensor is arranged at the bottom of the control device, and the signal output end of the pressure sensor is connected to the signal input end of the PLC, and the control device is fixedly connected to the bottom of the underwater monitor or the underwater remote-controlled vehicle.

[0016] Furthermore, the second clamping portion is a gripper, and the second clamping portion is connected to the bottom of the control device through a steel rope.

[0017] Further, before cable laying, use the GPS positioning system to determine the plane coordinate position, use the dual-frequency digital sonar system to survey the deep-water geomorphology of the routing area, and use the shallow layer profile system to identify the distribution and scope of the shallow geological structure in the routing area;

[0018] Before the cable laying ship performs construction operations, obstacle clearing operations should be carried out within a certain distance on both sides of the cable route to ensure that there are no objects affecting the cable laying ship's burying operations at the bottom of the deep-water area within the operation range of the cable laying ship.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The deep-water cable of the present invention has the additional functions of being resistant to high pressure and deep-water erosion, seawater corrosion, having high mechanical strength, and preventing damage by deep-water animals, enabling the cable to adapt to long-term use in deep-water cable laying. The fiber optic sensing unit pre-installed with the cable can, according to the characteristics of the environment, real-time monitor important physical quantities such as the operating temperature and strain information at distribution points along the cable, and accurately locate, providing a basis for quickly troubleshooting.

[0021] For the laying method of the deep-water cable of the present invention, as the depth of the underwater monitor and the underwater remotely operated vehicle increases with the sinking of the cable, the clamping device grabs the cable with greater force, and the underwater monitor and the underwater remotely operated vehicle further closely adhere to the side of the cable, enabling accurate acquisition of monitoring data and precise remote control of the cable laying and sinking, making the cable laying process more accurate. Description of the Drawings

[0022] Figure 1 is a schematic structural diagram of the deep-water cable of the present invention;

[0023] Figure 2 is Figure 1 an enlarged schematic diagram of part A of

[0024] Figure 3 is a schematic diagram of the deep-water cable laying process of the present invention;

[0025] Figure 4 is a schematic diagram of the clamping device of the present invention;

[0026] Figure 5 is a schematic diagram of the cable sheath of the present invention;

[0027] In the figure: 1. Conductor; 2. Conductor shielding layer; 3. Insulation layer; 4. Insulation shielding layer; 5. Water-blocking layer; 6. Sealing tight sleeve layer; 7. Sheath layer; 8. Armor layer; 9. Fiber optic sensing unit; 10. Anticorrosion layer; 11. Sheath; 111. Groove; 12. Cable; 13. Cable laying vessel; 14. Cable paying-out device; 15. Rope paying-out device; 16. Clamping device; 161. Control device; 162. Pressure sensor; 163. First clamping part; 164. Second clamping part; 17. Steel wire rope; 18. Underwater monitor / remotely operated underwater vehicle. Detailed implementation manner

[0028] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation manners. Terms such as "upper", "inner", "middle", "left", "right", and "one" cited in this specification are only for the convenience of narration and are not used to limit the scope of implementation of the present invention. The change or adjustment of their relative relationship, without substantial change in the technical content, should also be regarded as the scope of implementation of the present invention.

[0029] Deep-water cables are usually used in deep-water areas such as the seabed, and play an important role in the development of offshore energy such as communication and power generation. Once a deep-water cable fails and stops operating, it will cause very large economic losses. Statistical data shows that 95% of deep-water cable damages are caused by human activities such as fishing and shipping, mainly external damages caused by fishing gear, ship anchors, etc. At the same time, marine geological activities will also bring uncertainties to the operation of submarine cables. Therefore, it is very necessary to monitor the operation status of submarine cables in real time. When a deep-water cable is damaged to different degrees, the temperature field and electric field inside the cable will both change. When the armor layer of the submarine cable is damaged but not penetrated, the temperature field and electric field inside the submarine cable do not change significantly compared with the normal situation, indicating that the submarine cable can still operate normally for a period of time when the armor layer is not damaged. If the damage reaches the filling layer, the temperature field and electric field strength inside the deep-water cable also hardly change, but because the rigidity of the filling layer is not enough to withstand the deep-water pressure, the deep-water cable will have a short-circuit fault in a very short time. The most serious is that the damage reaches the insulation layer. The insulation layer not only has much lower rigidity than the armor layer, but more seriously, the electric field strength inside the submarine cable will increase sharply, causing the cable insulation layer to be punctured due to the high electric field strength.

[0030] To solve this problem, the present invention designs a kind of as Figure 1The deep - water cable 12 shown includes, from the inside to the outside, a conductor 1, a conductor 1 shielding layer, an insulating layer 3, an insulating shielding layer 4, a water - blocking layer 5, a sealing jacket layer 6, a sheath layer 7, an armor layer 8, and an anti - corrosion layer 10. A fiber optic sensing unit 9 is arranged inside the armor layer 8. The change of the internal pressure field of the deep - water cable 12 is reflected by the fiber optic sensing unit 9 inside the cable 12, and the location where the fault occurs is monitored, providing a basis for quickly eliminating the fault.

[0031] The conductor 1 includes a central conductor and N layers of arc - shaped conductors tightly stranded around the central conductor. The conductor stranded by several unit conductors is softer and has better bending performance than a single - strand conductor of the same diameter size, and can adapt to the harsh deep - water terrain environment. At the same time, the tightly stranded conductor 1 also has a water - blocking function, preventing deep water from radially infiltrating and diffusing to corrode the conductor 1.

[0032] The armor layer 8 includes a first armor layer and a second armor layer from the inside to the outside. The double - layer armor layer makes the mechanical strength of the cable stronger. As Figure 2 shown, among them, the first armor layer includes several first metal wires. The fiber optic sensing unit 9 replaces one of the first metal wires and is wound along the sheath layer 7 together with the other first metal wires. Because the armor layer 8 has the strongest mechanical strength, when the armor layer 8 is not damaged, the cable 12 can still operate normally for a period of time. When the external force damage exceeds the armor layer 8 and enters the inner structural layer, the rigidity of the inner structural layer is not enough to withstand the deep - water pressure, and the deep - water cable 12 will have a short - circuit fault in a very short time. Therefore, setting the fiber optic sensing unit 9 in the armor layer 8 can timely sense important physical quantities such as pressure, bending, strain, current, magnetic field, voltage, humidity, temperature, etc. at the cable - along - line distribution points inside the cable when the armor layer 8 is penetrated by external force, and accurately locate the fault, providing a basis for quickly eliminating the fault. At the same time, there is no need to reserve an additional position for the fiber optic sensing unit 9, saving the space inside the cable and making the shape of the cable 12 more regular. The fiber optic sensing unit is a fiber optic sensor, which consists of a light source, an incident optical fiber, an outgoing optical fiber, an optical modulator, an optical detector, and a demodulator. Its basic principle is to send the light of the light source into the modulation area through the incident optical fiber. The light interacts with the external measured parameters in the modulation area, causing the optical properties (such as intensity, wavelength, frequency, phase, polarization state, etc.) of the light to change and become the modulated signal light, and then sending it into the optical detector and demodulator through the outgoing optical fiber to obtain the measured parameters.

[0033] The second armor layer includes several second metal wires. The winding direction of the second metal wires is opposite to that of the first metal wires, eliminating stress and increasing the mechanical strength of the armor layer 8.

[0034] Foaming glue is sprayed between the gaps of adjacent first metal wires and between the gaps of adjacent second metal wires after winding is completed. The foaming glue can fill the gaps between adjacent metal wires. After the foaming glue cures, it can increase the strength of the armor layer 8. At the same time, the foaming glue has a waterproof function to prevent deep water from seeping radially into the cable interior. Flame-retardant foaming glue is preferably selected to prevent the foaming glue from catching fire when the temperature inside the cable is too high.

[0035] Specifically, both the conductor shielding layer 2 and the insulation shielding layer 4 are semi-conductor wrapped to evenly distribute the electric field and improve the service life of the insulating material. The insulation layer 3 is cross-linked polyethylene extruded, with good insulation performance. The water-blocking layer 5 is filled with water-blocking powder. The water absorption of the water-blocking powder is dozens to thousands of times its own weight, with high water absorption strength and expansion rate. After absorbing water, it can quickly expand to form a gel-like substance, blocking the water seepage channel, blocking the longitudinal diffusion of water in the cable, terminating the further diffusion and extension of water and moisture, and minimizing the length of the dampened cable. The tightly-sealed jacket layer 6 is a metal tube to prevent high-pressure deep water from surging in and diffusing radially. The sheath layer 7 is a weather-resistant polyethylene sheath to prevent the hard armor layer 8 from scratching the interior of the cable.

[0036] The anti-corrosion layer 10 is composed of polypropylene and asphalt, with good anti-corrosion performance to prevent deep water from corroding the cable.

[0037] As Figure 3 shown, a laying method for a deep-water cable includes the following steps:

[0038] One end of the cable 12 is fixed on the shore, and the cable-laying ship 13 carrying the cable-releasing device 14 releases the cable while moving forward along the designed route.

[0039] An underwater monitor and an underwater remote control vehicle 18 are used for continuous monitoring and adjustment to control the forward speed, direction, and cable-laying speed of the cable-laying ship 13 to avoid uneven places and rocks to prevent damage to the cable 12. Clamping devices 16 are provided between the underwater monitor 18 and the cable 12, and between the underwater remote control vehicle 18 and the cable 12. The deeper the cable 12 sinks, the greater the force of the clamping device 16 to grasp the cable 12. The illustrated underwater monitor / underwater remote control vehicle 18 is only a schematic diagram, and 18 can be an underwater monitor or an underwater remote control vehicle.

[0040] Specifically, as Figure 3As shown in Figure 5, a sheath 11 with a groove 111 is installed on the surface of the cable 12. The sheath 11 plays a role in strengthening the strength of the cable 12. The groove 111 serves as a guide rail so that the clamping device 16 can move along the length direction of the cable 12. The clamping device 16 includes a first clamping part 163, a second clamping part 164 and a control device 161. The first clamping part 163 and the second clamping part 164 grab and clamp the groove 111 of the sheath 11 of the cable 12. The control device 161 is provided with a PLC and a motor inside. The signal output end of the PLC is connected to the input end of the motor. The output end of the motor is connected to a transmission assembly. The motor is matched with the first clamping part 163 through the transmission assembly. A pressure sensor 162 is provided at the bottom of the control device 161. The signal output end of the pressure sensor 162 is connected to the signal input end of the PLC. The control device 161 is fixedly connected to the bottom of the underwater monitor or underwater remote control vehicle 18. The second clamping part 164 is a gripper, and the second clamping part 164 is connected to the bottom of the control device 161 through the steel rope 17. The second clamping part 164 is not connected to the motor transmission because if the motor does not work, the clamping part connected to the motor transmission will also stop working, and the underwater monitor 18 / underwater remote control vehicle 18 will have the risk of being separated from the cable 12, so the second clamping part 164 is set to mechanical clamping to prevent both clamping parts from failing, thereby reducing the risk of the underwater monitor 18 / underwater remote control vehicle 18 being separated from the cable 12. As the cable 12 sinks further, the underwater pressure increases, the pressure sensor 162 senses the underwater pressure and converts the pressure signal into an available output electrical signal and sends it to the PLC, the PLC controls the motor to increase the output power, so that the gripping force of the first clamping part 163 increases, then the underwater monitor and the underwater remote control vehicle 18 can be tightly attached to the cable 12, avoiding separation from the cable 12 due to the huge underwater pressure, so that the monitoring data is more accurate, and the remote control positioning during the laying process of the cable 12 is more accurate.

[0041] Before laying the cable, use the GPS positioning system to determine the plane coordinate position, use the dual-frequency digital sonar system to investigate the deep-water topography of the routing area, and use the shallow stratum profile system to find out the distribution and range of the shallow geological structure in the routing area; before the cable-laying vessel 13 starts construction, obstacle clearance operations should be carried out within a certain distance on both sides of the cable route to ensure that there are no objects at the bottom of the deep-water area within the operating range of the cable-laying vessel 13 that may affect the burying operation of the cable-laying vessel 13.

[0042] Laying method of deep - water cable of the present invention. As the underwater monitor 18 and the underwater remote - controlled vehicle 18 sink deeper with the cable 12, the greater the force of the clamping device 16 to grasp the cable 12. The underwater monitor 18 and the underwater remote - controlled vehicle 18 are further closely attached to the side of the cable 12, can accurately obtain monitoring data, and precisely remotely control the cable 12 to lay and sink, making the cable - laying process more accurate. Monitoring the catenary of the cable 12 during the laying operation is crucial for reducing the stress and strain on the cable 12 by matching the ship speed and the cable release rate and combining with adjusting different seabed depths. In addition, unrecorded hazards or objects in the cable - laying path can be seen in advance, and decisions to slow down the running speed or adjust the designed cable - laying corridor path can be made in real - time, thus saving considerable and expensive rework and potential damage to the cable.

[0043] The embodiments of the present invention are not limited thereto. According to the above content of the present invention, using the ordinary technical knowledge and customary means in the art, without departing from the above - mentioned basic technical idea of the present invention, the present invention can also be modified, replaced or combined in many other forms, all of which fall within the scope of the protection of the present invention's rights.

Claims

1. Method for laying deep - water cable, characterized in that: It includes the following steps: One end of the cable is fixed on the shore, and the cable laying ship carrying the cable laying device moves forward along the designed route while laying the cable; An underwater monitor or an underwater remote control vehicle is used for continuous monitoring and adjustment to control the forward speed, direction of the cable laying ship and the speed of laying the cable, so as to avoid uneven places and rocks to prevent damage to the cable; Clamping devices are arranged between both the underwater monitor and the underwater remote control vehicle and the cable. The deeper the cable sinks, the greater the force of the clamping device to grasp the cable; A sheathed cable with grooves is installed on the surface of the cable. The clamping device includes a first clamping part, a second clamping part and a control device. The first clamping part and the second clamping part grasp and clamp the grooves of the cable sheath. A PLC and a motor are arranged inside the control device. The signal output end of the PLC is connected to the input end of the motor. The output shaft of the motor is in transmission connection with the first clamping part. A pressure sensor is arranged at the bottom of the control device. The signal output end of the pressure sensor is connected to the signal input end of the PLC. The control device is fixedly connected to the bottom of the underwater monitor or the underwater remote control vehicle; When the cable sinks deeper, the underwater pressure is greater. The pressure sensor senses the underwater pressure and converts the pressure signal into an available output electrical signal and sends it to the PLC. The PLC controls the motor to increase the output power to increase the grasping force of the first clamping part.

2. The laying method of the deep-water cable according to claim 1, characterized in that: The second clamping part is a gripper, and the second clamping part is connected to the bottom of the control device through a steel wire rope.

3. The laying method of the deep-water cable according to claim 2, wherein: Before laying the cable, use the GPS positioning system to determine the plane coordinate position, use the dual-frequency digital sonar system to survey the deep-water landform of the routing area, and use the shallow layer profile system to find out the distribution and scope of the shallow geological structure of the routing area; Before the cable laying ship constructs, obstacle clearing operations should be carried out within a certain distance on both sides of the cable route to ensure that there are no objects affecting the cable laying ship's burying operation at the bottom of the deep-water area within the operation range of the cable laying ship.

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