A method for checking the safety of a floating flexible thin-film photovoltaic platform at sea

Abstract

The application discloses a kind of checking methods for the safety of offshore floating flexible thin film photovoltaic platform, offshore floating flexible thin film photovoltaic platform includes double floater, thin film and multiple mooring connectors, checking method includes floater structure checking: establishing coupled dynamic equation group, solving equation group obtains floater elastic deformation modal coefficient, according to floater elastic deformation modal coefficient calculation and judge floater safety.The present application realizes the accurate quantification of the design stress at any position of the floater tube wall, providing a reliable design basis for the optimization of the floater's pipe diameter, wall thickness and material structure parameters, effectively avoiding the structural yield failure under extreme sea conditions.

Description

Technical Field

[0001] This invention relates to the field of power, and more particularly to a method for verifying the safety of offshore floating flexible thin-film photovoltaic platforms. Background Technology

[0002] With advancements in photovoltaic (PV) power generation technology and declining costs, the PV power generation industry has continued to expand, reaching a cumulative installed capacity of approximately 1.2 TW worldwide by the end of 2022. However, large-scale PV power plants require approximately 0.016 square kilometers of land per megawatt, which will significantly negatively impact the economic viability of PV projects in densely populated areas and countries with multi-purpose land use. Furthermore, deploying PV power plants in remote areas far from populated regions incurs substantial costs for long-distance power transmission infrastructure.

[0003] Therefore, with the tightening of onshore photovoltaic space resources and my country's restrictions on the development of freshwater floating photovoltaic systems, offshore areas have become an important strategic space for photovoltaic development. Floating photovoltaic systems, as a novel photovoltaic power generation technology, have solved some of the problems and challenges of onshore photovoltaic systems. Considering the relatively significant wave and current conditions in open seas, traditional floating photovoltaic pontoon structures are no longer suitable, and new types of offshore photovoltaic support structures are gaining attention. Typical examples include rigid floating photovoltaic support structures and flexible thin-film photovoltaic support structures. Among them, offshore floating flexible thin-film photovoltaic platforms have advantages such as low structural weight and mooring stress, low wind resistance, convenient transportation, easy installation, and low cost. However, current methods for verifying the safety of offshore floating flexible thin-film photovoltaic platforms are not yet perfect.

[0004] Therefore, those skilled in the art are dedicated to developing a verification method for the safety of offshore floating flexible thin-film photovoltaic platforms. Summary of the Invention

[0005] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is: 1) Existing technologies lack effective methods for deriving deformation and calculating internal force distribution for flexible twin-buoy structures for marine photovoltaic systems, making it difficult to accurately verify their strength and load-bearing capacity.

[0006] 2) The large-scale flexible deformation of the membrane under the action of wind and waves makes it difficult to calculate the tension distribution; in addition, when inputting extreme wave examples, high and steep waves that do not conform to physical reality are often generated, which can easily lead to a serious overestimation of the local tension of the membrane in the calculation.

[0007] 3) Thin-film photovoltaic platforms have large windward and current-receiving areas, and the load fluctuates drastically under dynamic conditions. Conventional static assessments cannot accurately reflect the fatigue and breakage risks of the mooring system.

[0008] 4) Floating thin-film photovoltaic platforms generally have low freeboard, making them highly susceptible to wave impact caused by waves exceeding the effective freeboard. This can increase the platform's load and even lead to the risk of equipment flooding and damage. Existing technologies make it difficult to quantitatively analyze the instantaneous water inflow.

[0009] To achieve the above objectives, this invention provides a method for verifying the safety of a floating flexible thin-film photovoltaic platform at sea. The floating flexible thin-film photovoltaic platform includes two float rings, a thin film, and multiple mooring connectors. The two float rings include an inner float ring and an outer float ring, both of which are annular and concentric. The inner float ring and the outer float ring are rigidly connected, and the edge of the thin film is rigidly connected to the inner float ring. The verification method includes verification of the float ring structure. The structural physical parameters and marine environmental load parameters of a floating flexible thin-film photovoltaic platform are obtained. A coupled dynamic equation set is established based on existing structural dynamics theory and hydroelasticity theory. Solving this coupled dynamic equation set yields the elastic deformation modal coefficients of the float, including the modal coefficients of the float's vertical deformation. , In-plane elastic deformation mode coefficients of the float , , in The modal order is... The criteria for judging the structure of the float ring are as follows: ≤ It was determined at that time that the safety requirements of the float structure were met. > It was determined at that time that the safety requirements of the float structure were not met, among which Stress design for float rings, This represents the yield stress of the float material.

[0010] Furthermore, The

[0011] in, It is a constant normal stress caused by the pretension of the mooring system. for The load factor, It is the normal stress caused by environmental loads. for The load factor.

[0012] Furthermore, the aforementioned , in, This represents the total normal stress at a point on the wall of the float ring.

[0013] Furthermore, the aforementioned , in, Let be the normal stress at a point on the float ring tube wall caused by the out-of-plane bending moment. The normal stress at a point on the float ring tube wall caused by the in-plane bending moment. Let be the moment of inertia of the cross section of the float. Point in the centroid coordinate system of the cross section radial coordinates in Point in the centroid coordinate system of the cross section Vertical coordinates in The out-of-plane bending moment of the floating ring, Let be the in-plane bending moment of the floating ring.

[0014] Furthermore,

[0015] in, The elastic modulus of the float ring, Let be the moment of inertia of the float's cross section. is the distance from the centroid of the float cross section to the center of the circle, and is the equivalent radius of the float.

[0016] Furthermore, the verification method also includes thin film structure verification: The structural physical parameters and marine environmental load parameters of a floating flexible thin-film photovoltaic platform are obtained. A coupled dynamic equation set is established based on existing structural dynamics theory and hydroelasticity theory. Solving this coupled dynamic equation set yields the elastic deformation modal coefficients of the thin film, including the modal coefficients of in-plane deformation. , , , The nth eigenvalue of the mth order of the first type of in-plane deformation of the thin film The nth eigenvalue of the mth order of the second type of in-plane deformation of the thin film , The criteria for judging the performance of thin film structures are as follows: A value ≤1 indicates that the safety requirements for the thin film structure are met. A value greater than 1 indicates that the safety requirements for thin film structures are not met. ,in For the design tension of the thin film, This represents the allowable tension of the thin film material.

[0017] Furthermore, , in, Pre-tension is applied to the thin film. Its load factor, This is the maximum tension calculated after applying an external load. Its load factor.

[0018] Furthermore,

[0019] in, For the pretension of the film, The maximum tension at a point on the film. ,in, The maximum principal stress at a point on the thin film. The thickness of the film. The calculation formula is:

[0020] in, This represents the total radial normal stress of the thin film. This represents the circumferential normal stress of the thin film. For the shear stress of the thin film, ,in, The radial normal stress is caused by the in-plane deformation of the thin film. The radial normal stress is caused by the out-of-plane deformation of the thin film. ,in, The circumferential normal stress is caused by the in-plane deformation of the thin film. The circumferential normal stress is caused by the out-of-plane deformation of the thin film. ,in, This refers to the shear stress caused by the in-plane deformation of the thin film.

[0021] in The elastic modulus of the film. Poisson's ratio, Where is the thin film radius. , , , There are four structural characteristic functions. For the pretension of the film, The radial gradient of the thin film,

[0022] in, For normalized thin film radial coordinates, Let be the radial coordinate of a point on the thin film. In order to obtain The m-th order Bessel function when the value is given. In order to obtain The m-th order Bessel function when the value is given. This represents the nth eigenvalue of the mth order of the first type of in-plane deformation of the thin film, extracted based on time-domain potential flow calculations. The value is the nth eigenvalue of the mth order of the second type of in-plane deformation of the thin film, which is extracted based on the time-domain potential flow calculation. m and n are the modal cutoff numbers.

[0023] Furthermore, the verification methods also include mooring verification: The structural physical parameters and marine environmental load parameters of a floating flexible thin-film photovoltaic platform were obtained. A coupled dynamic equation set was established based on existing structural dynamics and hydroelasticity theories. Solving this equation set yielded load variation curves at each mooring node. The unstable segments in the initial stage of the calculation were removed to obtain the average tension of the mooring cable under stress. With dynamic tension Combined with the average environmental safety factor Safety factor of dynamic environment Comprehensive calculation of mooring design loads:

[0024] Calculate mooring utilization rate:

[0025] like If the value is less than 1, then the cable meets the strength requirement; otherwise, it does not.

[0026] Furthermore, the verification method also includes wave verification: The structural physical parameters and marine environmental load parameters of a floating flexible thin-film photovoltaic platform were obtained. A coupled dynamic equation set was established based on existing structural dynamics theory and hydroelasticity theory. This coupled dynamic equation set was then solved. Throughout the calculation process, the instantaneous wave surface at the edge of the dual floating rings was monitored to determine wave-climbing phenomena and calculate the wave magnitude. The criteria for determining the upward trend are defined as follows:

[0027] in, Represents the wavefront elevation function. This indicates the vertical displacement of the float. This represents the preset effective freeboard height. When the above conditions are met, it is considered that wave-on occurs. The local wave-on amount is calculated using the following formula:

[0028] in, The horizontal velocity of the wave surface, , Indicates the start and end times of the upward wave. The overtopping head is the instantaneous wave height above the top of the wave barrier. = , Integrate and sum the local upwelling amounts within each interval to obtain the total upwelling amount over the entire calculation time. If the total upwelling amount is less than the product of the drainage pump power and the entire calculation time, it is determined that the upwelling check is satisfied.

[0029] Technical effect

[0030] 1) A method for calculating the in-plane and out-of-plane stresses and verifying the safety of a floating ring based on a combination of modal decomposition and curved beam theory is proposed. The floating ring, rigidly connected internally and externally, is equivalent to a curved beam. Using the displacement modal coefficients obtained from overall hydrodynamic calculations, the out-of-plane bending moments (based on Euler-Bernoulli beam theory) and in-plane bending moments (based on the assumption of inextensibility) are solved separately. The total normal stress at each point on the annular cross-section is discretized and calculated to determine the structural utilization rate. This method achieves precise quantification of the design stress at any location on the floating ring wall, providing a reliable design basis for optimizing structural parameters such as the floating ring's diameter, wall thickness, and material, effectively avoiding structural yielding failure under extreme sea conditions.

[0031] 2) A method for evaluating the principal stress of flexible thin films is proposed, which integrates characteristic function expansion and superposition with wave steepness limit correction. Based on the Love theory governing equations of isotropic circular thin plates and the method of separation of variables, the in-plane and out-of-plane deformation modes of the thin film are extracted, and the maximum principal stress is derived using the large deflection bending formula. Simultaneously, a wave breaking limit constraint is introduced into the calculation process to automatically eliminate distorted wave surface motions exceeding this limit (wave steepness > 1 / 7), avoiding tension errors. This effectively eliminates the problem of overestimation of film stress caused by wave distortion, obtaining a film design tension and safe utilization rate that more closely reflects actual engineering conditions, and reducing redundant costs in thin film material selection while ensuring safety boundaries.

[0032] 3) A comprehensive verification method for mooring design tension based on load variation curves and dynamic correction using multiple environmental safety factors is proposed. Load variation curves of mooring nodes are extracted from the overall hydrodynamic calculation results. After removing the initial unstable segment, the force is separated into average tension and dynamic tension. These are then substituted into different environmental safety factors corresponding to the specifications for load superposition. Finally, the mooring utilization rate is obtained by comparing the load with the breaking load. This method comprehensively and conservatively covers the instantaneous peak force of mooring cables under extreme sea conditions, providing quantitative indicators for the layout scheme, alignment design, and cable breaking tensile strength selection of flexible photovoltaic platform mooring systems, ensuring the platform's safe positioning.

[0033] 4) A method for assessing the instantaneous inrush volume of water accumulated on a platform is proposed, based on dam-break theory and real-time monitoring of relative motion. Throughout the calculation process, the relative height difference between the vertical displacement of the float edge nodes and the instantaneous wave height is dynamically monitored. When the wave surface exceeds the effective freeboard, it is determined to trigger inrush. The total inrush volume is then calculated by integrating the wave surface flow rate in the time domain using the overrush head formula from dam-break theory. This method can accurately predict the total amount of water entering the platform under specific sea states and effective freeboard heights. A direct safety comparison with the platform's configured drainage pump capacity provides intuitive data support for the freeboard design and drainage system selection of photovoltaic platforms, preventing capsizing and sinking due to water accumulation.

[0034] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0035] Figure 1 This is a model diagram of a preferred embodiment of the present invention: a floating flexible thin-film photovoltaic platform. Figure 2 This is a preferred embodiment of the float cross-section discrete unit of the present invention; Figure 3 This is a cloud diagram showing the stress calculation results of the float design according to a preferred embodiment of the present invention; Figure 4 This is a cloud map showing the calculation results of the maximum principal stress of the thin film according to a preferred embodiment of the present invention. Detailed Implementation

[0036] The following description, with reference to the accompanying drawings, illustrates several preferred embodiments of the present invention to make its technical content clearer and easier to understand. The present invention can be embodied in many different forms, and the scope of protection of the present invention is not limited to the embodiments mentioned herein.

[0037] In the accompanying drawings, components with the same structure are indicated by the same numerical designation, and components with similar structures or functions are indicated by similar numerical designations. The dimensions and thicknesses of each component shown in the drawings are arbitrary, and the present invention does not limit the dimensions and thicknesses of each component. To make the illustrations clearer, the thickness of some components has been appropriately exaggerated in the drawings.

[0038] This invention provides a method for verifying the safety of a floating flexible thin-film photovoltaic platform at sea. The floating flexible thin-film photovoltaic platform includes two float rings, a thin film, and multiple mooring connectors. The two float rings include an inner float ring and an outer float ring, both of which are annular and concentric, and the inner float ring is rigidly connected to the outer float ring. The edge of the thin film is rigidly connected to the inner float ring. The mooring connectors are fixedly connected to the two float rings, and mooring cables are connected to the mooring connectors.

[0039] For structural deformation, the inner and outer floating rings and the edge of the membrane are rigidly connected, meaning that the displacement at each radius is completely consistent (including in-plane and out-of-plane).

[0040] Based on existing mature theories, the mathematical model of offshore floating flexible thin-film photovoltaic platforms can be proposed based on the modal superposition method. Its deformation can be decomposed into in-plane and out-of-plane parts, and structurally, it is divided into a floating ring and a thin film.

[0041] Double float structure: Since the inner and outer floats are rigidly connected, it can be regarded as a curved beam with different stiffness inside and outside the plane based on the parallel axis shift theorem.

[0042] 1. Float structure verification

[0043] The structure of either float in a double float configuration can be verified using the following method.

[0044] The structural physical parameters and marine environmental load parameters of a floating flexible thin-film photovoltaic platform are obtained. A coupled dynamic equation set is established based on existing structural dynamics theory and hydroelasticity theory. Solving this coupled dynamic equation set yields the elastic deformation modal coefficients of the float, including the modal coefficients of the float's vertical deformation. , In-plane elastic deformation mode coefficients of the float , Float bow roll coefficient Float heave coefficient The above-mentioned methods for establishing and solving the coupled dynamic equations are existing and mature techniques. For details, please refer to the article (Yifan Zhang et al., 'A frequency-domain hydroelastic analysis of a membrane-based offshore floating photovoltaic platform in regular waves', Journal of Fluids and Structures 127 (2024)104125).

[0045] The following content is an analysis and verification standard for the float structure.

[0046] Radial deformation of the float (1) According to the condition that the central axis of the Euler beam is inextensible, (2) The circumferential deformation of the float is obtained according to formula (2). (3) Vertical deformation of the float (4) Out-of-plane bending moment of the float Modal representation (5) in, The elastic modulus of the float ring, Let be the moment of inertia of the float's cross section. is the distance from the centroid of the float cross section to the center of the circle, and is the equivalent radius of the float. The formula for out-of-plane bending moment removes the rigid modes at m=0,1 and does not consider the contribution of torsion to the out-of-plane bending moment.

[0047] In-plane bending moment of the float Modal representation (6) Among them, due to the symmetry of the cross section, therefore This also refers to the in-plane bending stiffness of the float. is the distance from the centroid of the float cross section to the center of the circle, and is the equivalent radius of the float.

[0048] like Figure 2As shown, the cross-section of a single float is a circular ring. Since the wall thickness of the float is much smaller than its diameter, the effect of the wall thickness is ignored, and the stress is assumed to be uniformly distributed along the wall thickness. The circular cross-section of the float is discretized into several arc-shaped elements, and the magnitude of the normal stress at the center of each element is calculated for structural verification. The stress includes the normal stress generated by out-of-plane bending moments and in-plane bending moments, but does not account for other stress components generated by deformation modes such as tension and torsion.

[0049] The out-of-plane bending moment of the float is obtained by integrating the moment caused by the normal stress in the cross section. Considering the inextensibility condition and neglecting the curvature change caused by torsion, we have: (7) in Let be the normal stress at a point on the cross section, and let be the normal stress caused by the out-of-plane bending moment. Normal stress caused by in-plane bending moment The sum of Let the changes in out-of-plane and in-plane curvature before and after deformation be represented, respectively. The normal stress caused by the out-of-plane bending moment at a point on the float ring wall can then be calculated as follows: (8) in, Let be the moment of inertia of the float's cross section. Point in the centroid coordinate system of the cross section The vertical coordinates in the coordinate system are as follows: Figure 1 The diagram is constructed at the centroid of the cross section.

[0050] Similarly, for the in-plane bending moment of the float ring, we have: (9) Normal stress at a point on the float ring wall caused by in-plane bending moment (10) in, Let be the moment of inertia of the float's cross section. Point in the centroid coordinate system of the cross section The radial coordinates in the diagram. The total normal stress at a point on the float ring wall. (11) The float is discretized into several segments along the axial direction. The out-of-plane bending moment and in-plane bending moment on each segment are calculated. Then, the cross-section of each segment is divided according to... Figure 1 (Right) The discretization is divided into several arc segments. The normal stress at the center of each arc segment is calculated as the float stress at this position.

[0051] According to the float design stress given in DNVGL-RP-0584 (4.2) Calculation formula (12) in, It can be considered as a constant normal stress caused by the pretension of the mooring system, and its load factor is... The possible value is 1.0. This can be considered as normal stress caused by environmental loads; here, we take... Its load factor A possible value is 1.35. The maximum value used during the entire calculation process should be used for verification. (Appendix) Figure 3 for The resulting cloud map.

[0052] The design stress of the float should be less than the yield stress of the float material. ,Right now (13) ≤ It was determined at that time that the safety requirements of the float structure were met. > It was determined at that time that the safety requirements of the float structure were not met.

[0053] 2. Thin film structure verification

[0054] The structural physical parameters and marine environmental load parameters of a floating flexible thin-film photovoltaic platform are obtained. A coupled dynamic equation set is established based on existing structural dynamics theory and hydroelasticity theory. Solving this coupled dynamic equation set yields the elastic deformation modal coefficients of the thin film, including the modal coefficients of in-plane deformation. , , , The nth eigenvalue of the mth order of the first type of in-plane deformation of the thin film The nth eigenvalue of the mth order of the second type of in-plane deformation of the thin film m and n are the modal cutoff numbers.

[0055] The following content is the analysis and verification standards for thin film structure verification.

[0056] radial deformation of thin film and circumferential deformation (15) in (16) in In order to obtain The m-th order Bessel function when the value is given. In order to obtain The m-th order Bessel function when the value is given. For the normalized radial coordinates of the thin film, For modal truncation, These are four different radial modal characteristic functions.

[0057] Vertical deformation of the thin film (17) in The nth modal coefficient of the mth order in the out-of-plane deformation of the thin film. It is the m-th order n-th eigenvalue of the out-of-plane deformation.

[0058] Radial normal stress caused by in-plane deformation of the thin film Circumferential normal stress and shear stress (18) in The elastic modulus of the film. Poisson's ratio, This is the shear modulus of the thin film.

[0059] Formula (15) is the general differential relationship for calculating the in-plane stress of a thin film. Based on this, the modal superposition method is further introduced to decompose the displacement field into a linear combination of modes of each order, and the radial deformation of the thin film is then incorporated. and circumferential deformation Then, the stress can be represented by modal functions. (19) in, , (20) (twenty one) in Where is the thin film radius. For the normalized radial coordinates of the thin film, Let be the radial coordinate of a point on the thin film. , , , These are four structural characteristic functions, with specific expressions as shown above.

[0060] Radial normal stress caused by out-of-plane deformation of the thin film Circumferential normal stress and shear stress The formula is derived from the large deflection bending formula of a circular plate, and is referenced in Timoshenko's "Theory of Plates and Shells" (pp. 426-427).

[0061] (twenty two)

[0062] in, For the pre-tension of the film, h Let be the thickness of the thin film. The radial gradient of the thin film can be represented by a mode function. (twenty three) In the above equation, the three rigid modes corresponding to (m=0, n=1) and (m=1, n=1) are omitted. Furthermore, due to shear stress... Compared to radial normal stress and circumferential normal stress It is a high-order small quantity, so it can be ignored.

[0063] Total radial normal stress of the thin film Circumferential normal stress and shear stress It can be represented as (twenty four) Out-of-plane shear stress is ignored here.

[0064] Maximum principal stress at a point on the thin film Calculation formula (25) Appendix Figure 4 for The resulting cloud map.

[0065] Since the film thickness is small compared to the radius, it is uniformly distributed across the thickness. This is based on the calculated maximum principal stress. The maximum tension at a certain point on the film is obtained. : (26) in This refers to the thickness of the thin film. Similar to the float ring, the design tension of the thin film... It can be represented as (27) Among them, load factor According to Table 5-1, the load factor is 1.0. According to Table 5-1, take 1.35. The pre-tension preloaded on the thin film is taken here. , The maximum tension calculated after applying an external load is taken here. When verifying the entire film, it is discretized into several surface elements, and the design tension at the center of each surface element is calculated. The maximum value of the film's design tension throughout the entire time period should not exceed the allowable tension of the film material. ,Right now (28) Define thin film utilization rate (29) If this value is less than or equal to 1, the structural safety requirements are met. It is important to note that wave instances generated using wave spectrum and linear potential flow theory under extreme sea conditions may produce unrealistically steep waves exceeding the wave breaking limit (wave steepness = 1 / 7). Since flexible membranes deform primarily along the wave surface, and considering that the tension generated by the out-of-plane motion of the membrane is mainly related to its radial gradient, unrealistically steep waves may lead to an overestimation of the tension caused by the out-of-plane motion. Waves with a steepness exceeding a specific threshold can be removed from the program. Replace all parts with .

[0066] 3. Mooring verification

[0067] The structural physical parameters and marine environmental load parameters of a floating flexible thin-film photovoltaic platform were obtained. A coupled dynamic equation set was established based on existing structural dynamics and hydroelasticity theories. Solving this equation set yielded load variation curves at each mooring node. The unstable segments in the initial stage of the calculation were removed to obtain the average tension of the mooring cable under stress. With dynamic tension Based on the relevant standard DNVGL-RP-0584, the average tension of the mooring cable under stress is determined. With dynamic tension And taking into account the average environmental safety factor Safety factor of dynamic environment Comprehensive calculation of mooring design loads: (30) Referring to Section 6.2 of DNVGL-RP-0584, it is recommended that... Take 1.30, Take 1.75.

[0068] Based on the mooring design tension calculated above, and the mooring breaking load... The mooring utilization rate is obtained by taking the ratio. (31) If the ratio is less than 1 (or less than the limit corresponding to the safety factor), then the cable meets the strength requirements; otherwise, it does not.

[0069] 4. Verification by Shanglang

[0070] The structural physical parameters and marine environmental load parameters of the offshore floating flexible thin-film photovoltaic platform were obtained. A coupled dynamic equation system was established based on existing structural dynamics and hydroelasticity theories. This system was then solved. Throughout the calculation process, the instantaneous wave surface at the edge of the dual-buoy rings was monitored to determine wave-climbing phenomena and calculate the wave volume. Specifically, for each moment and each edge position, a wave-climbing event was considered to have occurred when the instantaneous wave height exceeded the designed effective freeboard height; the wave-climbing process was considered to have ended when the instantaneous wave height was below the effective freeboard height. The total wave volume for the entire simulation period was obtained by integrating the wave surface flow rate over time during the wave-climbing process.

[0071] The criteria for determining the upward trend are defined as follows: (32) in, Represents the wavefront elevation function. This indicates the vertical displacement of the float. This represents the preset effective freeboard height, which is the height of the wave-breaking structure at the edge of the platform above the still water surface of the float. When the condition of equation (32) is met, it is considered that a wave has occurred. According to the dam-break theory, the local wave volume can be calculated using the following formula: (33) in, The horizontal velocity of the wave surface, The overtopping head is the instantaneous wave height above the effective freeboard. = , It can be approximated as , , Indicates the start and end times of the upward wave. This is the acceleration due to gravity.

[0072] In summary, by using equation (32) to determine the wave occurrence interval and by using equation (33) to integrate and sum the wave amount in each interval, the total wave amount in the entire calculation time can be obtained. This amount is then compared with the power of the drainage pump configured on the membrane to analyze the safety of the water accumulation wave. If the total wave amount is less than the product of the drainage pump power and the entire calculation time, it is determined that the wave check is satisfied.

[0073] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for verifying the safety of offshore floating flexible thin-film photovoltaic platforms, characterized in that, The offshore floating flexible thin-film photovoltaic platform includes dual float rings, a thin film, and multiple mooring connectors. The dual float rings include an inner float ring and an outer float ring, both of which are annular and concentric. The inner float ring and the outer float ring are rigidly connected, and the edge of the thin film is rigidly connected to the inner float ring. The verification method includes float ring structure verification. The structural physical parameters and marine environmental load parameters of a floating flexible thin-film photovoltaic platform are obtained. A coupled dynamic equation set is established based on existing structural dynamics theory and hydroelasticity theory. Solving this coupled dynamic equation set yields the elastic deformation modal coefficients of the float, including the modal coefficients of the float's vertical deformation. , In-plane elastic deformation mode coefficients of the float , , in The modal order is... The criteria for judging the structure of the float ring are as follows: ≤ It was determined at that time that the safety requirements of the float structure were met. > It was determined at that time that the safety requirements of the float structure were not met, among which Stress design for float rings, This represents the yield stress of the float material.

2. The method for verifying the safety of offshore floating flexible thin-film photovoltaic platforms as described in claim 1. The in, It is a constant normal stress caused by the pretension of the mooring system. for The load factor, It is the normal stress caused by environmental loads. for The load factor.

3. The method for verifying the safety of offshore floating flexible thin-film photovoltaic platforms as described in claim 2, wherein... , in, This represents the total normal stress at a point on the wall of the float ring.

4. The method for verifying the safety of offshore floating flexible thin-film photovoltaic platforms as described in claim 3, wherein... , in, Let be the normal stress at a point on the float ring tube wall caused by the out-of-plane bending moment. The normal stress at a point on the float ring tube wall caused by the in-plane bending moment. Let be the moment of inertia of the cross section of the float. Point in the centroid coordinate system of the cross section radial coordinates in Point in the centroid coordinate system of the cross section Vertical coordinates in For the out-of-plane bending moment of the floating ring, Let be the in-plane bending moment of the floating ring.

5. The safety verification method for offshore floating flexible thin-film photovoltaic platforms as described in claim 4, in, The elastic modulus of the float ring, Let be the moment of inertia of the float's cross section. is the distance from the centroid of the float cross section to the center of the circle, and is the equivalent radius of the float.

6. The verification method for the safety of offshore floating flexible thin-film photovoltaic platforms as described in claim 1, wherein the verification method further includes thin-film structure verification: The structural physical parameters and marine environmental load parameters of a floating flexible thin-film photovoltaic platform are obtained. A coupled dynamic equation set is established based on existing structural dynamics theory and hydroelasticity theory. Solving this coupled dynamic equation set yields the elastic deformation modal coefficients of the thin film, including the modal coefficients of in-plane deformation. , , , The nth eigenvalue of the mth order of the first type of in-plane deformation of the thin film The nth eigenvalue of the mth order of the second type of in-plane deformation of the thin film , The criteria for judging the thin film structure are as follows: A value ≤1 indicates that the safety requirements for the thin film structure are met. A value greater than 1 indicates that the safety requirements for thin film structures are not met. ,in For the design tension of the thin film, This represents the allowable tension of the thin film material.

7. The safety verification method for offshore floating flexible thin-film photovoltaic platforms as described in claim 6, ， in, Pre-tension is applied to the thin film. Its load factor, This is the maximum tension calculated after applying an external load. Its load factor.

8. The method for verifying the safety of offshore floating flexible thin-film photovoltaic platforms as described in claim 7. in, For the pre-tension of the film, The maximum tension at a point on the film. ,in, The maximum principal stress at a point on the thin film. The thickness of the film. The calculation formula is: in, This represents the total radial normal stress of the thin film. This represents the circumferential normal stress of the thin film. For the shear stress of the thin film, ,in, The radial normal stress is caused by the in-plane deformation of the thin film. The radial normal stress is caused by the out-of-plane deformation of the thin film. ,in, The circumferential normal stress is caused by the in-plane deformation of the thin film. The circumferential normal stress is caused by the out-of-plane deformation of the thin film. ,in, This refers to the shear stress caused by the in-plane deformation of the thin film. in The elastic modulus of the film. Poisson's ratio, Where is the thin film radius. , , , There are four structural characteristic functions. For the pre-tension of the film, The radial gradient of the thin film, in, For normalized thin film radial coordinates, Let be the radial coordinate of a point on the thin film. In order to obtain The m-th order Bessel function when the value is given. In order to obtain The m-th order Bessel function when the value is given. This represents the nth eigenvalue of the mth order of the first type of in-plane deformation of the thin film, extracted based on time-domain potential flow calculations. The value is the nth eigenvalue of the mth order of the second type of in-plane deformation of the thin film, which is extracted based on the time-domain potential flow calculation. m and n are the modal cutoff numbers.

9. The verification method for the safety of offshore floating flexible thin-film photovoltaic platforms as described in claim 1, wherein the verification method further includes mooring verification: The structural physical parameters and marine environmental load parameters of a floating flexible thin-film photovoltaic platform were obtained. A coupled dynamic equation set was established based on existing structural dynamics and hydroelasticity theories. Solving this equation set yielded load variation curves at each mooring node. The unstable segments in the initial stage of the calculation were removed to obtain the average tension of the mooring cable under stress. With dynamic tension Combined with the average environmental safety factor Safety factor of dynamic environment Comprehensive calculation of mooring design loads: Calculate mooring utilization rate: like If the value is less than 1, then the cable meets the strength requirement; otherwise, it does not.

10. The safety verification method for offshore floating flexible thin-film photovoltaic platforms as described in claim 1, wherein the verification method further includes wave-side verification: The structural physical parameters and marine environmental load parameters of a floating flexible thin-film photovoltaic platform were obtained. A coupled dynamic equation set was established based on existing structural dynamics theory and hydroelasticity theory. This coupled dynamic equation set was then solved. Throughout the calculation process, the instantaneous wave surface at the edge of the dual floating rings was monitored to determine wave-climbing phenomena and calculate the wave magnitude. The criteria for determining the upward trend are defined as follows: in, Represents the wavefront elevation function. This indicates the vertical displacement of the float. This represents the preset effective freeboard height. When the above conditions are met, it is considered that wave-on occurs. The local wave-on amount is calculated using the following formula: in, The horizontal velocity of the wave surface, , Indicates the start and end times of the upward wave. The overtopping head is the instantaneous wave height above the top of the wave barrier. = , Integrate and sum the local upwelling amounts within each interval to obtain the total upwelling amount over the entire calculation time. If the total upwelling amount is less than the product of the drainage pump power and the entire calculation time, it is determined that the upwelling check is satisfied.

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