Floating offshore wind power semi-tension composite cable and construction method

Abstract

The application relates to the technical field of offshore wind power mooring construction, and proposes a floating offshore wind power semi-tension composite cable and a construction method. The floating offshore wind power semi-tension composite cable comprises a mooring cable body, a tension adjusting assembly and a controller. The mooring cable body comprises a polyester cable, an upper anchor chain and a lower anchor chain. The upper anchor chain and the lower anchor chain are respectively connected to the two ends of the polyester cable. The tension adjusting assembly comprises a tension sensor and a tension hydraulic cylinder. The tension sensor is implanted in the polyester cable. The tension hydraulic cylinder is installed at the upper anchor chain. The tension sensor is used for monitoring the tension of the mooring cable in real time and feeding back to the controller. The controller is used for driving the piston rod of the tension hydraulic cylinder to extend or retract according to the feedback tension data, so as to adjust the tension of the mooring cable. The application has the effects of relieving the tension mutation of the mooring cable under complex marine environment, reducing the cross winding and load concentration of the cable body.

Description

Technical Field

[0001] This application relates to the technical field of offshore wind power mooring construction, and in particular to a floating offshore wind power semi-tensioned composite cable and construction method. Background Technology

[0002] In floating offshore wind power systems, the semi-tensioned mooring system is the core component for achieving a reliable connection between the wind turbine platform and the seabed anchoring system. Its core function is to balance the displacement of the wind turbine platform and transmit dynamic loads in complex marine environments such as waves and ocean currents, ensuring that the wind turbine platform maintains a stable working posture.

[0003] Traditional semi-tensioned mooring systems typically use synthetic fiber ropes combined with anchor chains to form a composite cable. By connecting both ends of the mooring cable to the wind turbine platform and the suction anchor on the seabed, and pre-tensioning the mooring cable to apply a certain prestress, the prestress keeps the mooring cable in a near-tensioned state, thereby effectively controlling the movement of the wind turbine platform and reducing mooring tension, ensuring the stable positioning of the wind turbine platform.

[0004] Due to the complex marine environment caused by waves and currents, mooring cables in semi-tensioned mooring systems are prone to sudden tension changes, leading to cable entanglement and concentrated loads. This not only increases the risk of fatigue damage to the mooring cables but also necessitates a larger safety clearance during construction and installation. Furthermore, the horizontal cable length needs to be extended to improve attitude stability, resulting in an excessively large sea area occupied by the mooring cables during actual construction. This indirectly forces an increase in the spacing between wind turbines in wind farm cluster layouts, limiting installed capacity and increasing the construction cost per unit of power generation. Therefore, there is room for improvement. Summary of the Invention

[0005] To mitigate the sudden tension changes of mooring cables in complex marine environments, reduce cable cross-entanglement and load concentration, and lower the risk of fatigue damage to mooring cables, this application provides a floating offshore wind power semi-tensioned composite cable and its construction method.

[0006] This application provides a floating offshore wind power semi-tensioned composite cable and its construction method, which adopts the following technical solution: A floating offshore wind power semi-tensioned composite cable includes a mooring cable body, a tension adjustment component, and a controller; The mooring cable body includes a polyester cable, an upper anchor chain, and a lower anchor chain; the upper anchor chain and the lower anchor chain are respectively connected to both ends of the polyester cable; the upper anchor chain is used to connect to the wind turbine platform; the lower anchor chain is used to connect to the suction anchor. The tension adjustment assembly includes a tension sensor and a tensioning hydraulic cylinder; The tension sensor is embedded in the polyester cable; the tensioning hydraulic cylinder is installed at the upper anchor chain. The upper anchor chain includes a first connecting section and a second connecting section; the two ends of the first connecting section are respectively connected to the polyester cable and one end of the tensioning hydraulic cylinder; the second connecting section is connected to the other end of the tensioning hydraulic cylinder; The tension sensor and the tensioning hydraulic cylinder are both electrically connected to the controller. The tension sensor is used to monitor the tension of the mooring cable in real time and feed it back to the controller. The controller is used to drive the piston rod of the tensioning hydraulic cylinder to extend and retract according to the tension data fed back by the tension sensor, so as to adjust the tension of the mooring cable.

[0007] By adopting the above technical solution, when waves and ocean currents cause sudden changes in the mooring cable tension, tension sensors embedded in the polyester cable capture tension fluctuation data in real time and transmit it to the controller. After judging according to the preset tension threshold, the controller drives the piston rod of the tensioning hydraulic cylinder installed at the upper anchor chain to extend and retract, thereby adjusting the effective length of the upper anchor chain and adjusting the tension of the mooring cable to the preset range in real time. This helps to compensate for the tension fluctuations of the mooring cable, alleviate the amplitude of sudden changes in the tension of the mooring cable, avoid the phenomenon of mooring cable cross-entanglement and load concentration caused by sudden increase or decrease in tension, and reduce the risk of fatigue damage to the mooring cable. At the same time, the tension adjustment component forms an active adjustment mechanism for the mooring cable, which helps to improve the attitude stability of the mooring cable. Compared with the mooring cables of the traditional semi-tensioned mooring system, there is no need to reserve a large safety distance in the sea area and extend the horizontal laying length of the mooring cable, reducing the overall sea area occupied by the mooring cable. This is conducive to reducing the spacing between wind turbines in the wind farm cluster layout and increasing the installed density of wind turbines.

[0008] Preferably, a buoyancy cylinder is connected at the connection between the polyester cable and the lower anchor chain, and the buoyancy cylinder is hollow inside.

[0009] By adopting the above technical solution, a buoyancy cylinder is installed at the connection between the polyester cable and the lower anchor chain. The buoyancy of the buoyancy cylinder offsets the self-weight of the mooring cable body, thereby optimizing the vertical attitude of the mooring cable, reducing the area occupied in the sea, and making it easier for the cable to maintain a semi-tensioned state. This, in turn, helps to reduce the adjustment load of the tensioning hydraulic cylinder and reduce its extension and retraction frequency. At the same time, it can avoid friction and wear between the polyester cable and the seabed sediment, and extend the overall service life of the mooring chain.

[0010] Preferably, the outer periphery of the buoyancy cylinder is coated with an anti-bioadhesion coating.

[0011] By adopting the above technical solution, and by applying an anti-biofouling coating to the outer periphery of the buoyancy cylinder, it is possible to effectively inhibit the attachment and growth of marine organisms on the surface of the buoyancy cylinder, thereby avoiding a decrease in the actual buoyancy of the buoyancy cylinder due to biofouling; at the same time, it reduces the corrosion and damage to the buoyancy cylinder structure caused by biofouling, extends the service life of the buoyancy cylinder, and reduces the frequency and cost of maintenance.

[0012] Preferably, a number of counterweights are attached to a section of the first connecting segment near the polyester cable.

[0013] By adopting the above technical solution, a counterweight is attached to the area near the polyester cable in the first connecting section. The counterweight improves the overall stability of the upper anchor chain, which helps to suppress the irregular swaying of the mooring cable under the disturbance of waves and ocean currents. At the same time, the counterweight makes the force at the connection between the upper anchor chain and the polyester cable more stable, reduces stress concentration at the connection point, and improves the reliability of the connection.

[0014] Preferably, the polyester cable includes a core layer, the core layer is surrounded by a polyurethane sandproof layer, the polyurethane sandproof layer is surrounded by a polyester fiber braided layer, and the polyester fiber braided layer is coated with a modified polyvinyl chloride coating.

[0015] By adopting the above technical solution, the polyurethane anti-sand layer is combined with the polyester fiber braided layer to effectively prevent small sand particles from entering the core layer, thus avoiding the sand particles from abrading the core layer fibers and causing a decrease in tensile strength. By applying a modified polyvinyl chloride coating to the outer periphery of the polyester fiber braided layer, the corrosion resistance and UV aging resistance of the polyester cable can be enhanced.

[0016] A floating offshore wind power construction method, using the aforementioned semi-tensioned composite cable, includes the following steps: S1: Suction Anchor Construction: The suction anchor with the lower anchor chain is installed in place using a pump skid. S2: Polyester cable connection construction: Connect and fix the polyester cable to the end of the lower anchor chain on the suction anchor; S3: Wind turbine platform in place: Move the wind turbine platform with upper anchor chain into place; S4: Mooring cable reconnection: Connect the first connecting section of the upper anchor chain to the polyester cable; S5: Adjust the wind turbine platform to the working draft and pre-tension the mooring cables.

[0017] By adopting the above technical solution, and installing the lower anchor chain, polyester cable, and upper cable in sections, the difficulty of laying the mooring cable body is reduced, and the inconvenience caused by laying the entire cable at once is avoided. By pre-installing the lower anchor chain and upper anchor chain on the suction anchor and the wind turbine platform respectively, there is no need to carry out the connection construction between the lower anchor chain and the suction anchor, or between the upper anchor chain and the wind turbine platform. This further reduces the difficulty of laying the mooring cable and improves the overall laying efficiency of the mooring cable.

[0018] Preferably, in step S5, the anchor chain is tensioned by a tensioning hydraulic cylinder to pre-tension the mooring cable.

[0019] By adopting the above technical solution, pre-tensioning can be achieved using a tensioning hydraulic cylinder during the mooring cable reconnection stage, eliminating the need for additional dedicated tensioning equipment, simplifying the construction process, and reducing construction costs.

[0020] Preferably, in step S1, before the suction anchor is installed, a buoy is attached to the end of the lower anchor chain away from the suction anchor.

[0021] By adopting the above technical solution, buoys are attached to the lower anchor chain before the suction anchor is installed. The underwater position of the lower anchor chain can be marked by the buoys, which facilitates the precise connection between the polyester cable and the lower anchor chain. This avoids difficulties in connection construction caused by the lower anchor chain sinking to the seabed and being buried by silt or shifting its position, and improves connection efficiency.

[0022] In summary, this application includes at least one of the following beneficial technical effects: 1. When waves and ocean currents cause sudden changes in the mooring cable tension, the tension sensor inside the polyester rope can capture tension fluctuation data in real time and transmit it to the controller. The controller then drives the piston rod of the tensioning hydraulic cylinder to extend and retract, thereby adjusting the tension of the mooring cable to a preset range in real time. This alleviates the amplitude of sudden changes in mooring cable tension, avoids cable entanglement and load concentration, reduces the risk of fatigue damage to the mooring cable, and reduces the overall sea area occupied by the mooring cable. This is beneficial for reducing the spacing between wind turbines in the wind farm cluster layout and increasing the installed capacity density.

[0023] 2. By installing a buoyancy cylinder at the connection between the polyester rope and the lower anchor chain, the buoyancy of the buoyancy cylinder can offset the self-weight of the mooring cable body, optimize the vertical attitude of the mooring cable, reduce the area occupied in the sea, make it easier for the cable to maintain a semi-tensioned shape, and at the same time avoid friction and wear between the polyester rope of the mooring cable and the seabed sediment, thus extending the overall service life of the mooring chain.

[0024] 3. The counterweights tied to the upper anchor chain improve the overall stability of the upper anchor chain, suppress the irregular swaying of the mooring cable under the disturbance of waves and ocean currents, make the stress at the connection between the upper anchor chain and the polyester cable more stable, reduce stress concentration at the connection between the upper anchor chain and the polyester cable, and improve the reliability of the connection. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the installation of the wind turbine platform and the semi-tensioned mooring system used in this application.

[0026] Figure 2 This is a partial schematic diagram used in this application to illustrate the suction anchor and mooring cable.

[0027] Figure 3 This is a schematic diagram used in this application to illustrate a partial connection between the suction anchor and the mooring cable.

[0028] Figure 4 yes Figure 2 Enlarged schematic diagram of part A in the middle.

[0029] Explanation of reference numerals in the attached figures: 1. Mooring cable; 11. Polyester rope; 111. Core layer; 112. Polyurethane sandproof layer; 113. Polyester fiber braided layer; 12. Upper anchor chain; 120. Counterweight; 121. First connecting section; 122. Second connecting section; 13. Lower anchor chain; 2. Wind turbine platform; 3. Suction anchor; 4. Tensioning hydraulic cylinder; 14. H-type connector; 141. Connecting pin; 142. Rope guide wheel; 5. Buoyancy cylinder. Detailed Implementation

[0030] The following is in conjunction with the appendix Figure 1-4 This application will be described in further detail.

[0031] This application discloses a floating offshore wind power semi-tensioned composite cable and its construction method.

[0032] A floating offshore wind power semi-tensioned composite cable, referring to Figure 1 and Figure 2 The system includes a mooring cable 1 body, a tension adjustment component, and a controller. The two ends of the mooring cable 1 body are used to connect to the wind turbine platform 2 and the suction anchor 3, respectively. The tension adjustment component is installed on the mooring cable 1 body and electrically connected to the controller. The tension adjustment component is used to monitor the tension data of the mooring cable 1 in real time and feed it back to the controller. The controller is used to control the tension adjustment component to adjust the tension of the mooring cable 1 body according to the feedback tension data.

[0033] Reference Figure 2 and Figure 3 Specifically, the mooring cable 1 body includes a polyester cable 11, an upper anchor chain 12, and a lower anchor chain 13. The polyester cable 11 includes a core layer 111, which is surrounded by a polyurethane sandproof layer 112. This layer effectively blocks tiny sand particles from entering the core layer 111, preventing sand particles from abrading the core fibers and causing a decrease in tensile strength. The polyurethane sandproof layer 112 is bonded and fixed to the core layer 111 with an epoxy resin-based adhesive to improve the bonding strength between the core layer 111 and the polyurethane sandproof layer 112. The polyurethane sandproof layer 112 is also wrapped with a polyester fiber braided layer 113, which further enhances the protection of the core layer 111. The polyester fiber braided layer 113 is coated with a modified polyvinyl chloride coating with a thickness of 3 to 5 mm. Specifically, the modified polyvinyl chloride coating contains 1.2% nano-silver-loaded cuprous oxide antibacterial agent and 2% ultraviolet absorber to improve the overall corrosion resistance and UV aging resistance of the polyester cable 11, which helps to extend the service life of the polyester cable 11.

[0034] Reference Figure 1 and Figure 4The upper anchor chain 12 and the lower anchor chain 13 are respectively connected to the two ends of the polyester cable 11. The upper anchor chain 12 is used to connect the wind turbine platform 2, and the lower anchor chain 13 is used to connect the suction anchor 3.

[0035] Reference Figure 1 and Figure 4 Both ends of the polyester cable 11 are connected to the upper anchor chain 12 and the lower anchor chain 13 respectively via H-shaped connectors 14. Specifically, both ends of the H-shaped connector 14 are formed with connecting grooves, and each connecting groove is equipped with two connecting pins 141. The connecting pins 141 pass through the connecting grooves, and the ends of the connecting pins 141 are fixed and limited by lock nuts to prevent the connecting pins 141 from disengaging from the connecting grooves.

[0036] Reference Figure 1 and Figure 4 The polyester cable 11 has sleeve rings formed at both ends. The sleeve rings at the ends of the polyester cable 11 are fitted onto the connecting pin 141 at one end of the H-shaped connector 14. The connecting pin 141 is rotatably connected to the sleeve rings of the polyester cable 11. The cable guide wheel 142 has an annular limiting groove on its outer circumference. The sleeve rings at the ends of the polyester cable 11 are embedded in the annular limiting groove. The cable guide wheel 142 effectively reduces the friction between the polyester cable 11 and the H-shaped connector 14.

[0037] The chain links at the ends of the upper anchor chain 12 and the lower anchor chain 13 are sleeved on the connecting pins 141 at the other end of the corresponding H-type connectors 14, so that the polyester cable 11 is stably connected to the upper anchor chain 12 and the lower anchor chain 13 by means of the H-type connectors 14.

[0038] Reference Figure 1 and Figure 2 The tension adjustment assembly includes a tension sensor and a tensioning hydraulic cylinder 4. The tension sensor is embedded in the polyester cable 11, and specifically adopts a fiber optic grating sensor. The tensioning hydraulic cylinder 4 is installed at the upper anchor chain 12.

[0039] The upper anchor chain 12 includes a first connecting section 121 and a second connecting section 122; the tensioning hydraulic cylinder 4 is located between the first connecting section 121 and the second connecting section 122, with its two ends connected to the first connecting section 121 and the second connecting section 122 respectively. The end of the first connecting section 121 away from the tensioning hydraulic cylinder 4 is connected to the polyester cable 11 via an H-type connector 14, and the end of the second connecting section 122 away from the tensioning hydraulic cylinder 4 is used to connect to the wind turbine platform 2.

[0040] The tension sensor and tensioning hydraulic cylinder 4 are both electrically connected to the controller. When the tension sensor detects a change in the tension of the mooring cable 1, it feeds the data back to the controller. The controller, based on the feedback data and a preset tension threshold, determines whether to extend or retract the piston rod of the tensioning hydraulic cylinder 4 to adjust the effective length of the upper anchor chain 12, thereby achieving adaptive adjustment of the tension of the mooring cable 1. In actual operation, the controller can be connected to the wind turbine control system for real-time monitoring and adjustment.

[0041] Reference Figure 1 and Figure 2 Several counterweights 120 are attached to the first connecting section 121 near the polyester cable 11. The counterweights 120 improve the overall stability of the upper anchor chain 12, which helps to suppress the irregular swaying of the mooring cable 1 under the disturbance of waves and ocean currents. At the same time, it makes the force at the connection between the upper anchor chain 12 and the polyester cable 11 more stable, reduces the stress concentration at the connection between the upper anchor chain 12 and the polyester cable 11, and improves the connection reliability between the upper anchor chain 12 and the polyester cable.

[0042] Reference Figure 2 and Figure 4 A buoyancy cylinder 5 is installed at the connection between the polyester cable 11 and the lower anchor chain 13. The buoyancy cylinder 5 is a hollow polyester buoy, and its bottom end is connected to the H-shaped connector 14 at the connection between the polyester cable 11 and the lower anchor chain 13 via a cable. The buoyancy of the buoyancy cylinder 5 counteracts the weight of the mooring cable 1, thereby optimizing the vertical attitude of the mooring cable 1, reducing the area occupied in the sea, and making it easier for the cable to maintain a semi-tensioned state. At the same time, it can avoid friction and wear between the polyester cable 11 of the mooring cable 1 and the seabed sediment, thus extending the overall service life of the mooring chain.

[0043] The outer periphery of the buoyancy cylinder 5 is coated with an anti-biofouling coating. Specifically, the anti-biofouling coating can be an organic coating containing copper ions or a silicone coating. The coating effectively inhibits the attachment and growth of marine organisms on the surface of the buoyancy cylinder 5, preventing the actual buoyancy of the buoyancy cylinder 5 from decreasing due to biofouling. At the same time, it reduces the corrosion and damage to the structure of the buoyancy cylinder 5 caused by biofouling, extends the service life of the buoyancy cylinder 5, and reduces the frequency and cost of maintenance.

[0044] A floating offshore wind power construction method, employing the aforementioned floating offshore wind power semi-tensioned composite cable, with reference to... Figures 1 to 4 This includes the following steps: S1: Installation of suction anchor 3: The suction anchor 3 with the lower anchor chain 13 is installed into place using a pump skid; the specific steps are as follows: S1.1: Clear the sea and remove obstacles in the construction area of ​​suction anchor 3; S1.2: The lower anchor chain 13 is fixed to the lug plate on the outer periphery of the suction anchor 3 by a shackle at the end; S1.3: A buoy is attached to the end of the lower anchor chain 13 that is furthest from the suction anchor 3; S1.4: Transport and positioning of suction anchor 3: The crane ship and the transport ship carrying suction anchor 3 are berthed and positioned. S1.5: Lifting of suction anchor 3: The crane vessel lifts the suction anchor 3 with the lower anchor chain 13 from the transport vessel and installs the pump skid; before lifting, the end of the lower anchor chain 13 away from the suction anchor 3 is hooked onto the crane vessel's hook; S1.6: Installation of suction anchor 3: The crane vessel lowers the suction anchor 3 into the water and uses a pump skid to sink the suction anchor 3 to the design depth; S1.7: Recovery pump skid; S1.8: Lower anchor chain 13 bent and wet storage; S1.9: Repeat steps S1.1 to S1.8 until the installation of the remaining suction anchors 3 is completed.

[0045] S2: Polyester cable 11 connection construction: Connect and fix the polyester cable 11 to the tail end of the lower anchor chain 13 on the suction anchor 3; the specific steps are as follows. S2.1: Clear the sea and remove obstacles in the construction area of ​​mooring cable 1; S2.2: Laying the vessel into position: S2.3: Salvage anchor chain 13 to the laying vessel and remove the buoy at the stern of anchor chain 13; S2.4: Connect and fix the lower anchor chain 13 to the polyester cable 11 at the end closest to it using an H-type connector 14; S2.5: Installation of buoyancy cylinder 5: Connect buoyancy cylinder 5 to H-type connector 14 at the end of lower anchor chain 13 and polyester cable 11 via cable. S2.6: Attach a buoy to the end of the polyester cable 11 away from the lower anchor chain 13; S2.7: Polyester cable 11 bends and wet storage.

[0046] S2.8: Repeat steps S2.1 to S2.7 until the installation of the remaining polyester cables 11 is completed.

[0047] S3: Wind turbine platform 2 in place: Move the wind turbine platform 2 with the upper anchor chain 12 into place; the specific steps are as follows: S3.1: Connect the tail end of the second connecting section 122 of the upper anchor chain 12 to the corresponding connection point of the wind turbine platform 2 using a shackle; S3.2: The wind turbine platform 2 to be constructed shall be towed to the installation area by tugboat; S3.3: Temporarily limit the wind turbine platform 2 using three tugboats.

[0048] S4: Reconnect mooring cable 1; the specific steps are as follows: S4.1: Retrieve vessel salvage of polyester cable 11; S4.2: Connect the end of the polyester cable 11 to the first connecting section 121 of the upper anchor chain 12 using an H-type connector 14; S4.3: Repeat steps S4.1 to S4.2 until the remaining mooring cables 1 are reconnected.

[0049] S5: Adjust the wind turbine platform 2 to the working draft; tension the anchor chain 12 by tensioning the hydraulic cylinder 4 to pre-tension the mooring cable 1.

[0050] This application, through the cooperation of the mooring cable 1 body, tension adjustment component, and controller, effectively mitigates sudden tension changes in the mooring cable 1 under complex marine environments. The tension adjustment component monitors the tension in real time and feeds it back to the controller, which controls the action of the tensioning hydraulic cylinder 4 to adjust the tension of the mooring cable 1 in a timely manner, compensate for tension changes in the mooring cable 1, avoid cross-entanglement and load concentration in the mooring cable 1 body, and reduce the risk of fatigue damage to the mooring cable 1.

[0051] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A floating offshore wind power semi-tensioned composite cable, characterized in that: Includes the mooring cable (1) body, tension adjustment assembly and controller; The mooring cable (1) body includes a polyester cable (11), an upper anchor chain (12) and a lower anchor chain (13); the upper anchor chain (12) and the lower anchor chain (13) are respectively connected to the two ends of the polyester cable (11); the upper anchor chain (12) is used to connect the wind turbine platform (2); the lower anchor chain (13) is used to connect the suction anchor (3). The tension adjustment assembly includes a tension sensor and a tensioning hydraulic cylinder (4); The tension sensor is embedded in the polyester cable (11); the tensioning hydraulic cylinder (4) is installed at the upper anchor chain (12); The upper anchor chain (12) includes a first connecting section (121) and a second connecting section (122); the first connecting section (121) is connected at both ends to the polyester cable (11) and one end of the tensioning hydraulic cylinder (4); the second connecting section (122) is connected to the other end of the tensioning hydraulic cylinder (4); The tension sensor and the tensioning hydraulic cylinder (4) are both electrically connected to the controller. The tension sensor is used to monitor the tension of the mooring cable (1) in real time and feed it back to the controller. The controller is used to drive the piston rod of the tensioning hydraulic cylinder (4) to extend and retract according to the tension data fed back by the tension sensor, so as to adjust the tension of the mooring cable (1).

2. The floating offshore wind power semi-tensioned composite cable according to claim 1, characterized in that: A buoyancy cylinder (5) is connected at the connection between the polyester cable (11) and the lower anchor chain (13), and the buoyancy cylinder (5) is hollow inside.

3. A floating offshore wind power semi-tensioned composite cable according to claim 2, characterized in that: The outer periphery of the buoyancy cylinder (5) is coated with an anti-bioadhesion coating.

4. A floating offshore wind power semi-tensioned composite cable according to claim 1, characterized in that: Several counterweights (120) are attached to a section of the first connecting segment (121) near the polyester cable (11).

5. A floating offshore wind power semi-tensioned composite cable according to claim 1, characterized in that: The polyester cable (11) includes a core layer (111), the core layer (111) is wrapped with a polyurethane sandproof layer (112) on its outer periphery, the polyurethane sandproof layer (112) is also wrapped with a polyester fiber braided layer (113) on its outer periphery, and the polyester fiber braided layer (113) is coated with a modified polyvinyl chloride coating.

6. A floating offshore wind power construction method, employing a semi-tensioned composite cable as described in any one of claims 1 to 5, characterized in that: Includes the following steps: S1: Construction of suction anchor (3): The suction anchor (3) with the lower anchor chain (13) is installed in place by pump skid; S2: Polyester cable (11) connection construction: Connect and fix the polyester cable (11) to the tail end of the lower anchor chain (13) on the suction anchor (3); S3: Wind turbine platform (2) in place: Move the wind turbine platform (2) with the upper anchor chain (12) into place. S4: Mooring cable (1) reconnection: Connect the first connecting section (121) of the upper anchor chain (12) to the polyester cable (11); S5: Adjust the wind turbine platform (2) to the working draft and pre-tension the mooring cable (1).

7. A floating offshore wind power construction method according to claim 6, characterized in that: In step S5, the anchor chain (12) is tensioned by the tensioning hydraulic cylinder (4) to pre-tension the mooring cable (1).

8. A floating offshore wind power construction method according to claim 7, characterized in that: In step S1, before the suction anchor (3) is installed, a buoy is attached to the end of the lower anchor chain (13) away from the suction anchor (3).

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