Mooring system initial design method based on catenary equation

Abstract

The invention relates to the technical field of offshore mooring systems, and discloses a mooring system initial design method based on a catenary equation, which comprises the following steps: determining basic parameters of a mooring system according to a multi-component catenary equation; based on the basic parameters and the central symmetry problem of the floating foundation, mooring parameters, the horizontal offset of the floating platform under different wind wave flow incidence angles, the load borne by the floating wind turbine generator and the value of the horizontal force borne by the top end of a mooring chain are determined; according to the mooring parameters, the horizontal force borne by the top end of the mooring chain and the load borne by the floating type wind turbine generator, horizontal force balance checking is conducted; the maximum offset of the floating platform is verified, if the maximum offset of the floating platform is equal to the allowable maximum offset of the floating platform, the horizontal length of a mooring chain is compared, and if the maximum offset of the floating platform is not equal to the allowable maximum offset of the floating platform, iterative optimization is carried out; and determining parameters for designing the mooring system according to the mooring parameters in the corresponding states when the horizontal length of the mooring chain is maximum so as to establish the mooring system.

Description

Technical Field

[0001] The invention relates to the technical field of offshore mooring systems, and in particular to an initial design method for a mooring system based on a catenary equation. Background Art

[0002] Floating wind turbines are positioned at sea for a long time. Whether they can be successfully positioned and safely produced depends on their mooring system, which depends on the level of mooring design. Compared with the three-stage and catenary types, the weighted mooring system not only improves the performance of the mooring system, but also greatly reduces costs and increases economic benefits, providing an important cost-cutting and efficiency-enhancing option for the innovative design of future mooring systems. However, the design of the weighted mooring system faces many challenges: the complexity of the design prerequisites, the diversity of design parameters, and the stringent requirements of the specifications for various indicators of the mooring system. Especially in the deep-sea environment, the various design parameters form an intricate mutual constraint relationship, which adds great difficulty to the design work.

[0003] In view of this, the core task of the designer is to determine the structural parameters such as the length of each segment of the mooring chain, the top pre-tension and the horizontal radiation distance of the mooring based on the established design basis, aiming to ensure that the mooring system meets the specifications and standards while optimizing its system performance, that is, while improving the horizontal recovery characteristics of the mooring chain, effectively controlling the overall steel usage and mooring load, thereby achieving dual optimization of technology and economy.

[0004] Although various mature commercial software can accurately calculate the configuration and force of the mooring chain, they can only calculate and verify the existing mooring schemes, and cannot automatically derive reasonable values ​​of various parameters. Therefore, how to provide a mooring system that can automatically derive reasonable values ​​of various parameters is a technical problem that needs to be urgently solved by technical personnel in this field. Summary of the invention

[0005] To achieve the purpose of the present invention, the present application provides an initial design method for a mooring system based on a catenary equation, comprising:

[0006] Step S1: determining basic parameters of the mooring system according to the multi-component catenary equation;

[0007] Step S2: Based on the basic parameters and the central symmetry problem of the floating foundation, determine the mooring parameters and the horizontal offset of the floating platform under different wind and wave inflow incident angles, the load on the floating wind turbine and the horizontal force on the top of the mooring chain;

[0008] Step S3: performing a horizontal force balance check according to the mooring parameters, the horizontal force on the top of the mooring chain and the load on the floating wind turbine, and verifying the maximum offset of the floating platform if the horizontal force at the maximum offset of the floating platform is satisfied, and re-performing iterative optimization if it is not satisfied;

[0009] Step S4: verifying the maximum offset of the floating platform. If the maximum offset of the floating platform is equal to the maximum offset allowed by the floating platform, comparing whether the maximum horizontal lengths of the mooring chains that can be achieved under different wind and wave inflow incident angles are equal. If they are not equal, re-performing iterative optimization.

[0010] Step S5: Determine the parameters of the mooring system according to the mooring parameters under various states corresponding to the maximum horizontal length of the mooring chain, so as to establish the mooring system.

[0011] In some specific embodiments, the basic parameters include: environmental load, material properties of the mooring chain, height of the fairlead hole from the water surface, water depth, maximum offset of the floating platform, angle between two mooring chains at the same end, and length of the upper mooring chain.

[0012] In some specific embodiments, the mooring chain in step S2 includes: anchor chain-weight-anchor chain.

[0013] In some specific embodiments, the wind and wave inflow incident angle ranges from 0° to 60°.

[0014] In some specific embodiments, step S2 includes: obtaining mooring parameters under different states by the assumption method and the Newton iteration method, and performing a horizontal force balance check on the horizontal force exerted on the mooring chain and the load exerted on the floating wind turbine. If the balance is satisfied, proceed to the next step; if not, perform iterative optimization again.

[0015] In some specific embodiments, step S3 also includes: after the iterative optimization conditions are met, determining the maximum horizontal offset of the floating platform and the mooring parameters when the floating platform has the maximum offset, and performing a horizontal force balance check on the horizontal force exerted on the mooring chain and the load exerted on the floating wind turbine. If the conditions are met, the next step of verification is performed; if not, the iterative optimization is performed again.

[0016] In some specific embodiments, in step S4, the horizontal length of the mooring chain is the maximum horizontal length that the mooring chain can reach under different wind and wave inflow incident angles.

[0017] In some specific embodiments, in step S4, comparing the horizontal length of the mooring chain is used to ensure that the mooring chain remains tangent to the seabed at the anchor point under any incident angle of wind and wave flow, so that the anchor is only subjected to horizontal force.

[0018] In some specific embodiments, the multi-component catenary equation includes:

[0019]

[0020] T i =T i+1 +w i h i

[0021]

[0022] Among them, θ i is the inclination angle of the top of each mooring line, w i is the wet weight per unit length of each mooring line, l i is the unstretched length of each mooring line, l di is the stretched length of each mooring line, T0 is the horizontal external force on the top of the mooring line, T i is the tension at the top of each mooring line, EA i is the axial stiffness of each mooring line, S is the horizontal distance, S i is the horizontal distance corresponding to each section of the mooring line, h is the water depth, h i is the vertical height corresponding to each section of the mooring line, and i is the label of each section of the mooring line.

[0023] Beneficial effects of the above technical solution:

[0024] (1) The initial design method of the mooring system established by the present invention combines the catenary equation, the hypothesis method and the Newton iteration method, and can quickly design a mooring system solution that is feasible and has excellent performance.

[0025] (2) The present invention can realize the autonomous selection of mooring system parameters, effectively reduce the design difficulty, and save the calculation time for subsequent optimization of the mooring system.

[0026] (3) The present invention is suitable for the detailed design of the mooring system of deep-sea floating wind turbines, thereby improving the efficiency of the mooring system design work. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 A flow chart of an initial design method of a mooring system based on a catenary equation of the present invention;

[0029] Figure 2It is the static diagram of the multi-component mooring line of the present invention;

[0030] Figure 3 It is a static diagram of a multi-component mooring line with concentrated gravity of the present invention;

[0031] Figure 4 This is a schematic diagram of the initial design of an example 3×1 mooring system of the present invention;

[0032] Figure 5 This is a schematic diagram of the initial design of an example 3×2 mooring system (angle 30°) of the present invention;

[0033] Figure 6 This is a schematic diagram of the initial design of an example 3×2 mooring system (angle 60°) of the present invention;

[0034] Figure 7 This is an initial design configuration diagram of an exemplary mooring system of the present invention;

[0035] Figure 8 This is a comparison chart of platform offset data of an example 3×1 mooring system of the present invention;

[0036] Fig. 9 This is a comparison chart of platform offset data for an example 3×2 mooring system (angle 30°) of the present invention;

[0037] Fig.10 This is a comparison chart of platform offset data for an example 3×2 mooring system (angle 60°) of the present invention. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0039] Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar symbols throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0040] Embodiment 1

[0041] An embodiment of the present invention provides an initial design method for a mooring system based on a catenary equation, referring to Figure 1 As shown, including:

[0042] Step S1: determining basic parameters of the mooring system according to the multi-component catenary equation;

[0043] Step S2: Based on the basic parameters and the central symmetry problem of the floating foundation, determine the mooring parameters and the horizontal offset of the floating platform under different wind and wave inflow incident angles, the load on the floating wind turbine and the horizontal force on the top of the mooring chain;

[0044] Step S3: performing a horizontal force balance check according to the mooring parameters, the horizontal force on the top of the mooring chain and the load on the floating wind turbine, and verifying the maximum offset of the floating platform if the horizontal force at the maximum offset of the floating platform is satisfied, and re-performing iterative optimization if it is not satisfied;

[0045] Step S4: verifying the maximum offset of the floating platform. If the maximum offset of the floating platform is equal to the maximum offset allowed by the floating platform, comparing whether the maximum horizontal lengths of the mooring chains that can be achieved under different wind and wave inflow incident angles are equal. If they are not equal, re-performing iterative optimization.

[0046] Step S5: Determine the parameters of the mooring system according to the mooring parameters under various states corresponding to the maximum horizontal length of the mooring chain, so as to establish the mooring system.

[0047] In a specific embodiment of the present invention, the basic parameters include: environmental load, material properties of the mooring chain, height of the fairlead hole from the water surface, water depth, maximum offset of the floating platform, angle between two mooring chains at the same end, and length of the upper mooring chain.

[0048] In a specific embodiment of the present invention, the mooring chain in step S2 includes: anchor chain-weight-anchor chain.

[0049] In a specific embodiment of the present invention, the range of the wind and wave flow incident angle is 0°-60°.

[0050] In a specific embodiment of the present invention, step S2 includes: obtaining mooring parameters under different states by the assumption method and the Newton iteration method, and performing a horizontal force balance check on the horizontal force exerted on the mooring chain and the load exerted on the floating wind turbine. If the balance is satisfied, proceed to the next step; if not, perform iterative optimization again.

[0051] In a specific embodiment of the present invention, step S3 also includes: after the iterative optimization conditions are met, determining the maximum horizontal offset of the floating platform and the mooring parameters when the floating platform has the maximum offset, and performing a horizontal force balance check on the horizontal force exerted on the mooring chain and the load exerted on the floating wind turbine. If the conditions are met, the next step of verification is performed; if not, the iterative optimization is performed again.

[0052] In a specific embodiment of the present invention, in step S4, the horizontal length of the mooring chain is the maximum horizontal length that the mooring chain can reach under different wind and wave inflow incident angles.

[0053] In a specific embodiment of the present invention, in step S4, comparing the horizontal length of the mooring chain is used to ensure that the mooring chain remains tangent to the seabed at the anchor point under any incident angle of wind and wave flow, so that the anchor is only subjected to horizontal force.

[0054] In a specific embodiment of the present invention, the multi-component catenary equation includes:

[0055]

[0056] T i =T i+1 +w i h i

[0057]

[0058] Among them, θ i is the inclination angle of the top of each mooring line, w i is the wet weight per unit length of each mooring line, l i is the unstretched length of each mooring line, l di is the stretched length of each mooring line, T0 is the horizontal external force on the top of the mooring line, T i is the tension at the top of each mooring line, EA i is the axial stiffness of each mooring line, S is the horizontal distance, S i is the horizontal distance corresponding to each section of the mooring line, h is the water depth, h i is the vertical height corresponding to each section of the mooring line, and i is the label of each section of the mooring line.

[0059] The initial design method of the mooring system established by the present invention combines the catenary equation, the hypothesis method and the Newton iteration method, and can quickly design a feasible and high-performance mooring system solution. The present invention can also realize the autonomy of the mooring system parameter value, effectively reduce the design difficulty, and save the calculation time for subsequent optimization of the mooring system. The present invention is suitable for the detailed design of the mooring system of deep-sea floating wind turbines, and improves the efficiency of the mooring system design work.

[0060] Embodiment 2

[0061] A mooring system initial design method based on a catenary equation in this embodiment includes the following steps:

[0062] Step 1: Consider the multi-component catenary equation formula of elasticity, as follows:

[0063]

[0064] T i =T i+1 +w i hi (3)

[0065]

[0066] In the first step, θ i is the inclination angle of the top of each mooring line, w i is the wet weight per unit length of each mooring line, l i is the unstretched length of each mooring line, l di is the stretched length of each mooring line, T0 is the horizontal external force on the top of the mooring line, T i is the tension at the top of each mooring line, EA i is the axial stiffness of each mooring line, S is the horizontal distance, S i is the horizontal distance corresponding to each section of the mooring line, h is the water depth, h i is the vertical height corresponding to each mooring line, i is the number of each mooring line, and the static diagram of the multi-component mooring line considering elasticity is as follows: Figure 2 shown.

[0067] Step 2: Multi-component catenary equation considering elasticity when carrying concentrated weights. Due to the effect of gravity W, the angles of θ2 and θ3 are different. There is the following relationship between T2 and T3 and W:

[0068] T2sinθ2=T3sinθ3+W (10)

[0069] Formulas (1) to (9) are still applicable here, but W is used to replace the product of w2l2, and S2, h2 and l2 are zero. The static diagram of the elastic multi-component mooring line with concentrated gravity is as follows: Figure 3 shown.

[0070] Step 3: Input and assume: First, input the basic parameters initially. Considering the central symmetry problem of the floating foundation, it is only necessary to input the incident angle of the wind and wave flow of 0°-60°, and then assume the horizontal offset of the floating platform and the horizontal force on the top of the mooring chain under different wind and wave flow incident angles.

[0071] In the third step, the mooring chain adopts three components (anchor chain-weight-anchor chain). The basic parameters include environmental load, material properties of mooring chain, height of cable guide hole from water surface, water depth, maximum allowable offset of floating platform, angle between two mooring chains at the same end (limited to 3×2 mooring system) and length of upper mooring chain.

[0072] Step 4: Horizontal force verification and iteration: According to the third step, the mooring parameters under different states are obtained. The horizontal force on the mooring chain and the load on the floating wind turbine are checked for horizontal force balance. If satisfied, proceed to the next step. If not satisfied, re-iterate optimization. After the iterative optimization meets the conditions, the next assumption is made. The maximum horizontal offset of the floating platform is assumed, and the mooring parameters when the platform has the maximum offset are obtained. The horizontal force on the mooring chain and the load on the floating wind turbine are checked for horizontal force balance. If satisfied, proceed to the next step for verification. If not satisfied, re-iterate optimization.

[0073] Step 5: Offset verification and iteration: After the horizontal force verification when the platform's maximum offset is met, the maximum offset of the platform is verified. If it is equal to the maximum offset allowed by the platform, the next step is to compare the horizontal length of the mooring chain (that is, the maximum horizontal length that the mooring chain can reach under different wind and wave inflow angles). If they are not equal, iterative optimization is performed again.

[0074] Step 6: Compare and output: The purpose of comparing the horizontal length of the mooring chain is to ensure that the mooring chain remains tangent to the seabed at the anchor point under any incident angle of wind and wave flow, that is, the anchor is only subjected to horizontal force and not upward pulling force. Finally, the mooring parameters under various states corresponding to the maximum horizontal length of the mooring chain are output.

[0075] The initial design method of the present invention is further described below with reference to a specific example:

[0076] Input and assumptions: First, the basic parameters are initially input. The mooring chain adopts three components (anchor chain-weight block-anchor chain). The mooring system mainly adopts 3×1 mooring system, 3×2 mooring system (angle 30°) and 3×2 mooring system (angle 60°). Considering the central symmetry problem of the floating foundation, it is only necessary to input the incident angle of wind and wave flow of 0°-60°, and then assume the horizontal offset of the floating platform under different wind and wave flow incident angles and the value of the horizontal force on the top of the mooring chain.

[0077] The extreme working conditions are shown in Table 1.

[0078] Table 1 Extreme working conditions

[0079]

[0080] The basic parameters of the initial design are shown in Table 2.

[0081] Table 2 Basic parameters of initial design

[0082]

[0083] Furthermore, horizontal force verification and iteration: According to formulas (1) to (10), the assumption method and Newton iteration method are combined to obtain the mooring parameters under different states. The horizontal force acting on the mooring chain and the load acting on the floating wind turbine are checked for horizontal force balance. If the balance is satisfied, the next step is performed. If not, the iterative optimization is performed again.

[0084] After the iterative optimization meets the conditions, the next step is to make the assumption that the floating platform has a maximum horizontal offset, and then obtain the mooring parameters when the platform has a maximum offset. The horizontal force on the mooring chain and the load on the floating wind turbine are checked for horizontal force balance. If the conditions are met, the next step is to be verified. If not, the iterative optimization is repeated.

[0085] Furthermore, the offset is verified and iterated: after the horizontal force is checked when the platform's maximum offset is met, the maximum offset of the platform is verified. If it is equal to the maximum offset allowed by the platform, the next step is to compare the horizontal length of the mooring chain (that is, the maximum horizontal length that the mooring chain can reach under different wind and wave inflow angles). If they are not equal, iterative optimization is performed again.

[0086] Furthermore, the comparison and output are as follows: The comparison of the horizontal length of the mooring chain is to ensure that the mooring chain remains tangent to the seabed at the anchor point under any incident angle of wind and wave flow, that is, the anchor is only subjected to horizontal force and not upward pulling force. Finally, the mooring parameters under various states corresponding to the maximum horizontal length of the mooring chain are output.

[0087] The initial design results of the 3×1 mooring system, the initial design results of the 3×2 mooring system (angle 30°), and the initial design results of the 3×2 mooring system (angle 60°) are shown in Tables 3 to 5.

[0088] Table 3 3×1 mooring system initial design result parameters

[0089]

[0090] Table 4 Parameters of initial design results of 3×2 mooring system (angle 30°)

[0091]

[0092]

[0093] Table 5 Initial design result parameters of 3×2 mooring system (angle 60°)

[0094]

[0095] The initial design results of the 3×1 mooring system, the initial design results of the 3×2 mooring system (angle 30°) and the initial design results of the 3×2 mooring system (angle 60°) are shown in the figure below. Figures 4 to 6 shown.

[0096] The configuration diagrams of the three types of mooring systems output by the initial design are as follows: Figure 7 shown.

[0097] Figures 8 to 10 They respectively represent the comparison between the initial design results of different types of mooring systems and the results obtained by OpenFAST software. From the comparison curves, it can be seen that the error in the calculation results between the method of the present invention and the OpenFAST software is small, indicating that the method of the present invention can be used for specific mooring design.

[0098] The present invention is suitable for the detailed scheme design of the mooring system of the deep-sea floating wind turbine generator set, and improves the efficiency of the mooring system design work.

[0099] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

[0100] Each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referenced to each other. The embodiments of the present invention are described with reference to the flowcharts and / or block diagrams of the methods, terminal devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing terminal device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing terminal device generate instructions for implementing the functions in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 These computer program instructions can also be stored in a computer-readable memory that can guide a computer or other programmable data processing terminal device to work in a specific way, so that the instructions stored in the computer-readable memory produce a product including an instruction device, which implements the functions specified in the process. Figure 1 A process or multiple processes and / or boxes Figure 1These computer program instructions can also be loaded onto a computer or other programmable data processing terminal device, so that a series of operation steps are executed on the computer or other programmable terminal device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable terminal device provide for implementing the process in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps of the functions specified in one or more boxes. Although the preferred embodiments of the embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the attached claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention. Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or terminal device including a series of elements includes not only those elements, but also other elements that are not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0101] The method and device provided by the present invention are introduced in detail above. Specific examples are used in this article to illustrate the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

[0102] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", "one specific embodiment" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for initial design of a mooring system based on a catenary equation, characterized in that: include: Step S1: determining basic parameters of the mooring system according to a multi-component catenary equation; Step S2: Based on the basic parameters and the central symmetry problem of the floating foundation, determine the mooring parameters and the horizontal offset of the floating platform under different wind and wave inflow incident angles, the load on the floating wind turbine and the horizontal force on the top of the mooring chain; Step S3: performing a horizontal force balance check according to the mooring parameters, the horizontal force on the top of the mooring chain and the load on the floating wind turbine, and verifying the maximum offset of the floating platform if the horizontal force at the maximum offset of the floating platform is satisfied, and re-performing iterative optimization if it is not satisfied; Step S4: verifying the maximum offset of the floating platform. If the maximum offset of the floating platform is equal to the maximum offset allowed by the floating platform, comparing whether the maximum horizontal lengths of the mooring chains that can be achieved under different wind and wave inflow incident angles are equal. If they are not equal, re-performing iterative optimization. Step S5: Determine the parameters of the mooring system according to the mooring parameters under various states corresponding to the maximum horizontal length of the mooring chain, so as to establish the mooring system.

2. The initial design method of a mooring system based on a catenary equation according to claim 1, characterized in that: The basic parameters include: environmental load, material properties of the mooring chain, height of the fairlead hole from the water surface, water depth, maximum offset of the floating platform, angle between two mooring chains at the same end, and length of the upper mooring chain.

3. The initial design method of a mooring system based on a catenary equation according to claim 1, characterized in that: In step S2, the mooring chain includes three components: anchor chain-weight-anchor chain.

4. The initial design method of a mooring system based on a catenary equation according to claim 1, characterized in that: In step S2, the wind and wave inflow incident angle ranges from 0° to 60°.

5. The initial design method of a mooring system based on a catenary equation according to claim 1, characterized in that: Step S2 includes: determining the mooring parameters under different states by the hypothesis method and the Newton iteration method, and performing a horizontal force balance check on the horizontal force on the mooring chain and the load on the floating wind turbine. If the balance is satisfied, proceed to the next step; if not, perform iterative optimization again.

6. The initial design method of a mooring system based on a catenary equation according to claim 5, characterized in that: Step S3 also includes: after the iterative optimization conditions are met, determining the maximum horizontal offset of the floating platform and the mooring parameters when the floating platform has the maximum offset, and performing a horizontal force balance check on the horizontal force on the mooring chain and the load on the floating wind turbine. If the conditions are met, the next step of verification is performed; if not, the iterative optimization is performed again.

7. The initial design method of a mooring system based on a catenary equation according to claim 1, characterized in that: In step S4, the horizontal length of the mooring chain is the maximum horizontal length that can be achieved by the comparison mooring chain under different wind and wave inflow incident angles.

8. The initial design method of a mooring system based on a catenary equation according to claim 1, characterized in that: In step S4, the comparison of the horizontal length of the mooring chain is used to ensure that the mooring chain remains tangent to the seabed at the anchor point under any incident angle of wind and wave flow, so that the anchor is only subjected to horizontal force.

9. The initial design method of a mooring system based on a catenary equation according to claim 1, characterized in that: The multi-component catenary equation includes: T i =T i+1 +w i h i Among them, θ i is the inclination angle of the top of each mooring line, w i is the wet weight per unit length of each mooring line, l i is the unstretched length of each mooring line, l di is the stretched length of each mooring line, T0 is the horizontal external force on the top of the mooring line, T i is the tension at the top of each mooring line, EA i is the axial stiffness of each mooring line, S is the horizontal distance, S i is the horizontal distance corresponding to each section of the mooring line, h is the water depth, h i is the vertical height corresponding to each section of the mooring line, and i is the label of each section of the mooring line.

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