Power generation efficiency optimization method for floating type photovoltaic power generation system

Abstract

The invention discloses a power generation efficiency optimization method for a floating photovoltaic power generation system. The method comprises the following steps: analyzing the motion response of a floating body in a marine environment, and determining the boundary condition of the floating body swinging under the action of waves; based on hydrodynamic analysis software AQWA, a hydrodynamic analysis model of the floating body is built, and the pitching angle of the floating body is verified; in combination with an inclined surface irradiance calculation model, an improved particle swarm algorithm is adopted for optimization, and the initial inclination angle of the photovoltaic panel when the photovoltaic panel receives solar radiation energy to the maximum extent is solved; in combination with different wave conditions of a certain sea area, simulation software is used for performing dynamic simulation on the floating body and the assembly, the influence of different environmental conditions on the power generation efficiency is analyzed, and the effectiveness of the scheme is verified. According to the method, the optimal initial angle is determined by optimizing the initial mounting inclination angle of the assembly, fully considering the movement condition of the floating body under the action of waves and combining the influence of different wave conditions, the radiation quantity received by the assembly is maximized, and the defects in the aspects of laying design, dynamic adaptability and power generation efficiency in the prior art are overcome.

Description

(I) Technical Field:

[0001] This invention relates to the field of photovoltaic power generation technology, and in particular to a method for optimizing the power generation efficiency of a floating photovoltaic power generation system. (II) Background Technology:

[0002] In recent years, the layout of photovoltaic power generation projects has gradually shifted from Northwest my country to Central and East China, and the development model has expanded from plains to mountainous areas and from land to water. Among these, offshore floating photovoltaic power stations use bases and floating platforms to float photovoltaic modules on the sea surface to generate electricity. This not only saves valuable land resources but also utilizes the cooling effect of water to lower the module temperature, thereby improving power generation efficiency. However, the marine environment is complex and changeable. Especially under the action of waves, the floating platform will continuously sway. Even if the ambient irradiance remains constant, the movement of the waves will still cause random fluctuations in the distribution of sunlight on the photovoltaic modules, thus affecting the power generation efficiency of the photovoltaic modules. This dynamic environment causes the solar angle of the photovoltaic panels to constantly change, making it impossible to install them at the optimal angle as on land.

[0003] Current research on offshore floating photovoltaic (PV) power generation systems mainly focuses on the following aspects: first, energy integration and economic benefits, optimizing marine space utilization, stabilizing energy supply, and reducing costs by combining with other marine renewable energy sources; second, system stability and durability, deeply analyzing the fatigue effects of waves, wind, and current on floating structures, and studying the stability of rigid structures and flexible connection designs to address the long-term durability challenges under wave conditions exacerbated by climate change. However, research on the electrical aspects of offshore floating PV power generation systems lacks in-depth analysis of the impact of factors such as waves on the irradiance of PV modules in actual marine operating environments. Furthermore, no simulation tools or methods specifically designed for the power generation efficiency of offshore floating PV power generation systems have been developed, resulting in insufficient performance optimization.

[0004] To address this issue and achieve higher solar radiation utilization and power generation efficiency, this paper proposes a method for optimizing the power generation efficiency of floating photovoltaic power generation systems based on improvements to existing technologies, providing an effective solution for the design of photovoltaic systems in complex marine environments. (III) Summary of the Invention:

[0005] The purpose of this invention is to provide a method for optimizing the power generation efficiency of a floating photovoltaic power generation system. This method overcomes the shortcomings of existing technologies by optimizing the initial installation tilt angle of the photovoltaic modules and comprehensively considering the dynamic motion characteristics and wave conditions of the floating body. It ensures that the photovoltaic modules can receive solar radiation to the maximum extent in different environments and is a simple and easy-to-implement optimization method.

[0006] The technical solution of this invention: a method for optimizing the power generation efficiency of a floating photovoltaic power generation system, comprising the following steps:

[0007] (1) Analyze the wave conditions and the structure of the floating body to determine the motion response of the floating body in the marine environment and the boundary conditions for the oscillation of the floating body under the action of waves;

[0008] In step (1), the wave conditions include the wave height H and period T, and the floating structure includes the length, width, height and mass of the floating body.

[0009] In step (1), determining the motion response of the floating body in the marine environment means that, under the combined action of wind, waves, and water flow loads, the floating body will exhibit a motion mode with six degrees of freedom under the action of waves, and the motion equations are solved as shown in equation (1):

[0010]

[0011] In the formula, M s For structural mass, M a The additional mass is ω, the wave angular frequency is B, the damping is C (frequency-dependent), the hydrostatic stiffness is C, and the wave force is F. It is the acceleration of the object. ρ is the velocity of the object, and x is the displacement of the object;

[0012] The motion response of the floating body in the time domain can be calculated by converting formula (1) into:

[0013]

[0014] In the formula, k(t-τ) is the memory function, F(t) is the dynamic force exerted by the wave on the floating body, and T(t) is the instantaneous impact load on the floating body;

[0015] The additional mass M a The memory function k(t) can be calculated by the following formula:

[0016]

[0017] The range of oscillation angles of the floating body under extreme sea conditions is taken as the boundary condition for the pitching motion of the floating body. Combined with the effect of wind load, the limit value of the tilt angle of the component can be determined by the formula in Appendix A.2 of T / CPIA0017—2019 "Design Specification for Floating Photovoltaic Power Generation System", as shown in Equation (5). The initial installation tilt angle range of the component is determined based on the motion of the floating body. The initial installation tilt angle range is obtained by subtracting the maximum value of the floating body motion from the limit value of the tilt angle of the component.

[0018] W = KW k Scosβ (5)

[0019] In the formula, W is the design value of wind load; S is the actual area of ​​the component; W k β is the standard value of wind load; K is the matrix correction coefficient; β is the limit value of component tilt angle.

[0020] Ocean waves are classified into regular waves and irregular waves. Under the influence of regular waves, the angular oscillation of a floating body in the waves can be considered as simple harmonic motion. Therefore, the angular change of a photovoltaic module under the action of regular waves can be expressed by equation (6):

[0021]

[0022] In the formula, α0 is the initial tilt angle of the photovoltaic module, ε is the amplitude of the change of the floating body under the action of waves, φ is the initial phase of the wave, and T is the wave period.

[0023] For random or irregular waves composed of different wave heights, periods, and propagation directions, the wave can be considered as a superposition of many simple harmonic cosine waves with random amplitudes, random frequencies, and random initial phases, in the following form:

[0024]

[0025] In the formula, A i The wave amplitude is derived from the wave spectrum S(ω); φ i The initial phase of the wave; N is the total number of discrete frequency components; Δω i =ω i —ω i-1 .

[0026] In summary, the angle change of a photovoltaic module under the action of an irregular wave can be represented by equation (9):

[0027]

[0028] In the formula, φ j H represents the phase after wave superposition. a (ω i ) is the amplitude of the frequency response function, which is determined by formula (10).

[0029]

[0030] In step (1), the boundary condition for the swaying of the floating body under the action of waves specifically refers to the maximum value of the pitch angle of the floating body under the combined action of external loads. The amplitude of the pitch motion of the floating body can be obtained by integrating formula (1), as shown in formula (11).

[0031]

[0032] In the formula, ρ is the density of water, taken as 1025 kg / m³.3 g is the acceleration due to gravity, taken as 9.8 N / kg; H is the wave height; L is the distance from the point of action of the wave to the center of rotation. A is the effective force-bearing area, i.e., the area below the water surface.

[0033] (2) Build a hydrodynamic analysis model of the floating body and verify the motion response range of the floating body in step (1);

[0034] Step (2) is specifically based on the hydrodynamic analysis software AQWA. By building a finite element model, the motion response range of the floating body in step (1) is verified to accurately evaluate the dynamic characteristics of the floating body under wave conditions and verify the accuracy of the calculation results of formulas (1) to (4). The specific process includes the following:

[0035] 2-1) Building a finite element model: Using the hydrodynamic analysis software AQWA, a finite element model of the floating body is constructed based on the geometric characteristics, material parameters and hydrodynamic characteristics of the floating body structure to simulate the dynamic response of the floating body under wave action.

[0036] 2-2) Verify the pitch angle of the floating body: Using a hydrodynamic analysis model, the dynamic behavior of the floating body in the pitch direction is simulated by changing the wave height, period and direction of the waves. The pitch angle change curve of the floating body is extracted based on the simulation results, and the angle change of the floating body is used as the key input parameter for component tilt angle optimization.

[0037] 2-3) Data acquisition: Based on the simulation results and calculation results of the floating body motion in step 2-2), the accuracy of the calculation results of formulas (1) to (4) is verified by comparing the simulation results with the calculation results. If the error between the calculation results and the simulation results is within 1%, it can be proven that the calculation results are accurate and meet the requirements. The calculation data of the floating body pitching motion is used as the data affecting the change of tilt angle when calculating the irradiance in step (3).

[0038] (3) Taking the maximum amount of radiation received by the component as the optimization objective, combined with the tilted surface irradiance calculation model, the improved particle swarm algorithm is used as the optimization method to solve the initial tilt angle of the photovoltaic panel when maximizing the solar radiation energy received.

[0039] The calculation model for the irradiance of the inclined surface in step (3) is as follows:

[0040] The solar radiation energy received by a fixed-tilt photovoltaic module includes three parts: direct radiation energy, diffuse radiation energy, and reflected radiation energy.

[0041]

[0042] In the formula, G is the total radiant energy; G b For direct radiation energy; G d For scattered radiation energy; G gTo reflect radiation energy;

[0043] The angle of incidence of sunlight θ is given by equation (13):

[0044]

[0045] Where α is the angle between the surface of the photovoltaic cell and the horizontal plane. γ is the local geographic latitude angle, n is the azimuth angle of the inclined plane, δ is the hour angle, and δ is the declination angle.

[0046] 1) Direct radiation energy

[0047] G b =ξ0I sc P m (14)

[0048] In the formula, G b ξ0 is the direct radiation energy received by the horizontal surface; I is the Earth's orbital eccentricity correction factor; sc The solar constant represents the amount of solar radiation received per unit area per unit time at the upper boundary of the Earth's atmosphere perpendicular to sunlight. In engineering calculations, it is typically taken as 1367 W / m². 2 P is the atmospheric transparency coefficient; m is the atmospheric optical quality.

[0049] The calculation methods for the Earth orbit eccentricity correction coefficient ξ0 and the atmospheric optical mass m are shown in formulas (15) and (16), respectively.

[0050]

[0051]

[0052] 2) Scattered radiation energy

[0053] Theoretically, it is difficult to accurately calculate the solar scattered radiation energy on the Earth's surface. Generally, empirical calculation formulas based on actual measurements are used (17):

[0054]

[0055] Where h is the solar altitude angle;

[0056] The method for calculating the solar altitude angle h is shown in formula (18).

[0057]

[0058] 3) Reflected radiation energy

[0059] After solar radiation reaches the ground, the horizontal reflected irradiance G g Horizontal direct irradiance G b and horizontal scattered irradiance Gd The sum of the values ​​and the influence of the reflection coefficient q are considered, therefore, the reflected radiation energy G can be calculated according to equation (19). g :

[0060] G g =q(G b +G d (19)

[0061] In the formula, q represents the ground reflectivity.

[0062] From the above formula, we can see that the radiant energy G received by the fixed-tilt photovoltaic panel within time R is... R Equation (20) represents:

[0063]

[0064] The optimization method in step (3) refers to: based on the particle swarm optimization algorithm, introducing an improved strategy to eliminate the randomness of the algorithm, and adopting a strategy of dynamically adjusting the inertia weight. By dynamically adjusting the inertia weight value with the number of iterations, the algorithm can enhance the global search capability in the early stage and strengthen the local development capability in the later stage, thereby further improving the convergence accuracy and global search capability. The specific process of solving the initial tilt angle of the photovoltaic panel when maximizing the solar radiation energy received by the photovoltaic panel in step (3) using the improved particle swarm optimization algorithm is as follows:

[0065] 1) Define the problem and objective function

[0066] In a marine environment, the floating body is significantly affected by water depth and wave loads. When designing the initial tilt angle, the photovoltaic modules with different tilt angles will affect the change in the maximum received radiation. The wave height H and period T are the main factors affecting the tilt angle of the floating body. Therefore, the optimization objective comprehensively considers the initial tilt angle α0 of the module, the wave height H, and the period T. The influence of wave height and period on the pitch angle can be calculated by equation (11). The specific objective function is shown in (21).

[0067]

[0068] In the formula, G(t) is the amount of radiation received by the photovoltaic module with a tilt angle of α at time t; the initial tilt angle that maximizes the amount of radiation received by the module is taken as the optimization objective, that is:

[0069] maxG=f(α0)(22)

[0070] 2) Design constraints

[0071] Since the initial tilt angle α0 of the module is directly related to the power generation efficiency of the entire system, this invention aims to maximize the initial tilt angle of the module while meeting the constraints, thereby improving power generation efficiency. The specific design constraints are as follows:

[0072] 2-1) Based on the local wind load, the limit value β of the component tilt angle is determined by formula (5);

[0073] 2-2) Determine the buoy's position at extreme low wave height H based on formula (11) min Swing angle ε min and extreme high wave high H max Swing angle ε under environmental conditions max ;

[0074] 2-3) The initial angle range of the component is determined by the limit value of the component tilt angle and the maximum and minimum values ​​of the floating body's pitch motion. The minimum component tilt angle α corresponds to the maximum value of the floating body's pitch motion. min The component tilt angle α corresponds to the minimum pitch motion of the floating body. max ;

[0075] 2-4) During operation, the total angle of the components and the float shall not exceed the limit value β;

[0076] From constraints 2-1) to 2-4), an optimization model with the maximum radiation received by the component as the objective can be obtained, as shown in equation (23):

[0077]

[0078] 3) Specific process of improving the particle swarm optimization algorithm

[0079] Using different initial tilt angles as design variables, the initial tilt angle is continuously adjusted during the optimization process to seek the maximum radiation received by the component. The specific process is as follows:

[0080] 3-1) Determine the mass M of the buoy based on step (1). s Size, wave height H, and period T;

[0081] 3-2) After verifying the boundary conditions of the floating body's motion response in step (2), determine the minimum value of the objective function f(α) based on the minimum tilt angle. min ;

[0082] 3-3) Initialize the parameters, including the tilt angle α, the maximum number of iterations Y1 and the termination condition, and calculate the irradiance at the current tilt angle according to formula (12);

[0083] 3-4) Generate new design schemes based on different tilt angles within the component tilt angle range, and calculate the new objective function f(α);

[0084] 3-5) If f(α)>f(α) min Enter the iterative loop, and update α during the loop. i and the irradiance f(α) received i); Otherwise, reinitialize the tilt angle and iterate again;

[0085] 3 - 6) If α min < α i < α max , and f(α i ) > f(α), let α = α i ; If f(α i ) < f(α), keep α i = α; If α i is not within the range, then update α i again;

[0086] 3 - 7) If the maximum number of iterations Y1 is reached, output the optimal solution α i , and the tilt angle optimization ends; Otherwise, continue to loop and iterate until the initial tilt angle α0 that maximizes the irradiance within the tilt angle range is found.

[0087] (4) Combine the different wave conditions of the specific sea area, the initial tilt angle of the floating photovoltaic module obtained in step (3), and the surface irradiance of the tilt angle to calculate the total irradiance received by the offshore floating photovoltaic module.

[0088] The specific step (4) refers to calculating the total irradiance received by the module within a certain time according to the wave conditions of the target ocean, including the wave height H and period T of the waves, and the optimized tilt angle α0 in step (3), in combination with formula (20).

[0089] The beneficial effects of the technical solution provided by the present invention are:

[0090] 1. The present invention considers the design requirements of the module tilt angle for the floating body structure in the marine environment, proposes a design process for the optimal initial tilt angle of the module, fully considers the movement of the floating body under the action of waves, and determines the optimal initial angle in combination with the influence of different wave conditions to optimize the power generation efficiency.

[0091] 2. The present invention considers the influence of waves on the movement of the module, and establishes a mathematical model for the tilt angle change of the photovoltaic module under the action of waves. Through derivation, the tilt angle change law of the photovoltaic module under the action of different types of waves is analyzed, and the corresponding radiation energy calculation formula is given.

[0092] 3. This invention aims to maximize the overall solar radiation received across multiple scenarios. Based on potential flow theory and hydrodynamic equations, it calculates the motion response parameters of the floating body under external environments through time-domain analysis. By optimizing the initial installation tilt angle of the photovoltaic modules and comprehensively considering the dynamic motion characteristics of the floating body and wave conditions, it ensures that the photovoltaic modules can receive solar radiation to the maximum extent under different environments. This method uses hydrodynamic analysis technology to construct a dynamic model of the floating body, evaluate the impact of the floating body's motion on the system, and verify the design scheme in conjunction with optimization algorithms, ultimately determining the optimal installation angle that meets the design requirements. (iv) Description of the attached drawings:

[0093] Figure 1 This is a schematic diagram of the overall process of a method for optimizing the power generation efficiency of a floating photovoltaic power generation system according to the present invention.

[0094] Figure 2 This is a schematic diagram of the six-degree-of-freedom motion of the floating body in a method for optimizing the power generation efficiency of a floating photovoltaic power generation system according to the present invention.

[0095] Figure 3 This is a flowchart illustrating the steps of solving the improved particle swarm optimization algorithm in a method for optimizing the power generation efficiency of a floating photovoltaic power generation system, as described in this invention.

[0096] Figure 4 This is a schematic diagram comparing the calculation results and simulation results of the floating body motion response in the power generation efficiency optimization method of a floating photovoltaic power generation system involved in this invention.

[0097] Figure 5 shows the irradiance range of the tilted photovoltaic panel in the power generation efficiency optimization method of the floating photovoltaic power generation system involved in the present invention (wherein, 5-1 is the irradiance range under extreme condition 1, and 5-2 is the irradiance range under extreme condition 2).

[0098] Figure 6 This is a schematic diagram illustrating the change in the tilt angle of photovoltaic modules under the action of ocean waves in a method for optimizing the power generation efficiency of a floating photovoltaic power generation system according to the present invention.

[0099] Figure 7 This is a schematic diagram of the solution results under different wave heights in the same period in the power generation efficiency optimization method of a floating photovoltaic power generation system involved in this invention.

[0100] Figure 8 This is a schematic diagram of the solution results under different period conditions at the same wave height in the power generation efficiency optimization method of a floating photovoltaic power generation system involved in this invention.

[0101] Figure 9 This is a schematic diagram showing the irradiance variation of a typical day during the four seasons in the project location of the floating photovoltaic power generation system, which is part of the power generation efficiency optimization method of the floating photovoltaic power generation system involved in this invention.

[0102] Figure 10 This is a schematic diagram comparing the power generation efficiency before and after optimization in a floating photovoltaic power generation system power generation efficiency optimization method according to the present invention. (V) Specific Implementation Methods:

[0103] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below.

[0104] Example:

[0105] A method for optimizing the power generation efficiency of a floating photovoltaic power generation system, see [link to relevant documentation]. Figure 1 The method includes the following steps:

[0106] 101: Analyze wave conditions and floating body structure to determine the motion response of the floating body in the marine environment and the boundary conditions for the oscillation of the floating body under wave action;

[0107] 102: Construct a hydrodynamic analysis model of the floating body and verify the motion response range of the floating body in step (1);

[0108] 103: Taking the maximum amount of radiation received by the component as the optimization objective, and combining the tilted surface irradiance calculation model, the improved particle swarm optimization algorithm is used as the optimization method to solve the initial tilt angle of the photovoltaic panel when maximizing the solar radiation energy received.

[0109] 104: Combine the different wave conditions of the specific sea area, the initial tilt angle of the floating photovoltaic module obtained in step (3), and the irradiance of the tilt angle surface to calculate the total irradiance received by the floating photovoltaic module at sea.

[0110] In summary, the embodiments of the present invention optimize the power generation efficiency of floating photovoltaic systems through the above steps 101-104 and known external environmental parameters, and solve the shortcomings of existing technologies in terms of installation design, dynamic adaptability and power generation efficiency.

[0111] The following section provides a further explanation of the scheme in Example 1, using specific calculation formulas and examples. See the description below for details:

[0112] 201: Analyze wave conditions and floating body structure to determine the motion response of the floating body in the marine environment and the boundary conditions for the oscillation of the floating body under wave action;

[0113] Under the combined influence of wind, waves, and current loads, a floating body will exhibit six degrees of freedom of motion under the action of waves, such as... Figure 2 As shown, the solution to the equation of motion is shown in equation (1):

[0114]

[0115] In the formula, M s For structural mass, Ma The additional mass is ω, the wave angular frequency is B, the damping is C (frequency-dependent), the hydrostatic stiffness is C, and the wave force is F. It is the acceleration of the object. is the velocity of the object, and x is the displacement of the object.

[0116] The motion response of the floating body in the time domain can be calculated using formula (1) as follows:

[0117]

[0118] In the formula, k(t-τ) is the memory function, F(t) is the dynamic force exerted by the wave on the floating body, and T(t) is the instantaneous impact load on the floating body.

[0119] Additional mass M a The memory function k(t) can be calculated by the following formula:

[0120]

[0121] The range of oscillation angles of the floating body under extreme sea conditions serves as the boundary condition for the pitching motion of the floating body. Based on the motion of the floating body, the initial installation tilt angle of the components is determined. Combined with the effect of wind load, the limit value of the component tilt angle can be determined by formula (5) in Appendix A.2 of T / CPIA0017—2019 "Design Code for Floating Photovoltaic Power Generation Systems". Based on the motion of the floating body, the range of the initial installation tilt angle of the components is determined. The range of the initial installation tilt angle is obtained by subtracting the maximum value of the floating body motion from the limit value of the component tilt angle.

[0122] W = KW k Scosβ (5)

[0123] In the formula, W is the design value of wind load; S is the actual area of ​​the component; W k β is the standard value of wind load; K is the matrix correction coefficient; β is the limit value of component tilt angle.

[0124] Ocean waves are classified into regular waves and irregular waves. Under the influence of regular waves, the angular oscillation of a floating body in the waves can be considered as simple harmonic motion. Therefore, the angular change of a photovoltaic module under the action of regular waves can be expressed by equation (6):

[0125]

[0126] In the formula, α0 is the initial tilt angle of the photovoltaic module, ε is the amplitude of the change of the floating body under the action of waves, and φ is the initial phase of the waves.

[0127] For random or irregular waves composed of different wave heights, periods, and propagation directions, the wave can be considered as a superposition of many simple harmonic cosine waves with random amplitudes, random frequencies, and random initial phases, in the following form:

[0128]

[0129] In the formula, A i The wave amplitude is derived from the wave spectrum S(ω); φ i The initial phase of the wave; N is the total number of discrete frequency components; Δω i =ω i -ω i-1 .

[0130] In summary, the angle change of a photovoltaic module under the action of an irregular wave can be represented by equation (9).

[0131]

[0132] In the formula, φ j H represents the phase after wave superposition. a (ω i ) represents the amplitude of the frequency response function.

[0133]

[0134] The boundary condition for the oscillation of a floating body under the action of waves specifically refers to the maximum value of the pitch angle of the floating body under the combined action of external loads. The amplitude of the pitch motion of the floating body can be obtained by integrating formula (1), as shown in formula (11).

[0135]

[0136] In the formula, ρ is the density of water, taken as 1025 kg / m³. 3 g is the gravitational acceleration, taken as 9.8 N / kg; H is the wave height; L is the distance from the point of action of the wave to the center of rotation; A is the effective force-bearing area, i.e. the area below the water surface.

[0137] 202: Construct a hydrodynamic analysis model of the floating body and verify the motion response range of the floating body in step (1);

[0138] Step (2) is specifically based on the hydrodynamic analysis software AQWA. By building a finite element model, the motion response range of the floating body in step (1) is verified to accurately evaluate the dynamic characteristics of the floating body under wave conditions and verify the accuracy of the calculation results of formulas (1) to (4). The specific process includes the following:

[0139] 2-1) Building a finite element model: Using the hydrodynamic analysis software AQWA, a finite element model of the floating body is built based on the geometric characteristics, material parameters and hydrodynamic characteristics of the floating body structure to simulate the dynamic response of the floating body under wave action.

[0140] 2-2) Verify the pitch angle of the floating body: Using a hydrodynamic analysis model, the dynamic behavior of the floating body in the pitch direction is simulated by changing the wave height, period and direction of the waves. The pitch angle change curve of the floating body is extracted based on the simulation results, and the angle change of the floating body is used as the key input parameter for component tilt angle optimization.

[0141] 2-3) Data acquisition: Based on the simulation results and calculation results of the floating body motion in step 2-2), the accuracy of the calculation results of formulas (1) to (4) is verified by comparing the simulation results with the calculation results. If the error between the calculation results and the simulation results is within 1%, it can be proven that the calculation results are accurate. The specific data can be directly exported by the software. The calculation data of the floating body pitching motion is used as the data affecting the change of tilt angle when calculating the irradiance in step (3).

[0142] 203: Taking the maximum amount of radiation received by the component as the optimization objective, and combining the tilted surface irradiance calculation model, the improved particle swarm optimization algorithm is used as the optimization method to solve the initial tilt angle of the photovoltaic panel when maximizing the solar radiation energy received.

[0143] The specific model for calculating irradiance on inclined surfaces is as follows:

[0144] The solar radiation energy received by a fixed-tilt photovoltaic module includes three parts: direct radiation energy, diffuse radiation energy, and reflected radiation energy.

[0145]

[0146] In the formula, G is the total radiant energy; G b For direct radiation energy; G d For scattered radiation energy; G g To reflect radiation energy;

[0147] The angle of incidence of sunlight θ is given by equation (13):

[0148]

[0149] Where α is the angle between the surface of the photovoltaic cell and the horizontal plane. γ is the local geographic latitude angle, n is the azimuth angle of the inclined plane, δ is the hour angle, and δ is the declination angle.

[0150] 1) Direct radiation energy

[0151] G b =ξ0I sc P m (14)

[0152] In the formula, G b ξ0 is the direct radiation energy received by the horizontal surface; I is the Earth's orbital eccentricity correction factor; sc The solar constant represents the amount of solar radiation received per unit area per unit time at the upper boundary of the Earth's atmosphere perpendicular to sunlight. In engineering calculations, it is typically taken as 1367 W / m². 2 P is the atmospheric transparency coefficient; m is the atmospheric optical quality.

[0153] The calculation methods for the Earth orbit eccentricity correction coefficient ξ0 and the atmospheric optical mass m are shown in formulas (15) and (16), respectively.

[0154]

[0155] 2) Scattered radiation energy

[0156] Theoretically, it is difficult to accurately calculate the solar scattered radiation energy on the Earth's surface. Generally, empirical calculation formulas based on actual measurements are used (17):

[0157]

[0158] Where h is the solar altitude angle;

[0159] The method for calculating the solar altitude angle h is shown in formula (18).

[0160]

[0161] 3) Reflected radiation energy

[0162] After solar radiation reaches the ground, the horizontal reflected irradiance G g Horizontal direct irradiance G b and horizontal scattered irradiance G d The sum of the values ​​and the influence of the reflection coefficient q are considered, therefore, the reflected radiation energy G can be calculated according to equation (19). g :

[0163] G g =q(G b +G d (19) In the formula, q is the ground reflectivity. According to the reflectivity table of different environmental surfaces, the ground reflectivity is taken as 0.2 and the ocean reflectivity is taken as 0.1.

[0164] From the above formula, we can see that the radiant energy G received by the fixed-tilt photovoltaic panel within time R is... R Equation (20) represents:

[0165]

[0166] The optimization method in step (3) refers to: based on the particle swarm optimization algorithm, introducing an improved strategy to eliminate the randomness of the algorithm, and adopting a strategy of dynamically adjusting the inertia weight. By dynamically adjusting the inertia weight value with the number of iterations, the algorithm can enhance its global search capability in the early stage and strengthen its local exploration capability in the later stage, thereby further improving the convergence accuracy and global search capability. The tilt angle optimization process of the improved particle swarm optimization algorithm is as follows:

[0167] 1) Define the problem and objective function

[0168] In a marine environment, the floating body is significantly affected by water depth and wave loads. When designing the initial tilt angle, the photovoltaic modules with different tilt angles will affect the change in the maximum received radiation. The wave height H and period T are the main factors affecting the tilt angle of the floating body. Therefore, the optimization objective comprehensively considers the initial tilt angle α0 of the module, the wave height H, and the period T. The influence of wave height and period on the pitch angle can be calculated by equation (11). The specific objective function is shown in (21).

[0169]

[0170] In the formula, G(t) is the amount of radiation received by the photovoltaic module with a tilt angle of α at time t;

[0171] The initial tilt angle that maximizes the radiation received by the component is taken as the optimization objective, that is:

[0172] maxG=f(α0)(22)

[0173] 2) Design constraints

[0174] Since the initial tilt angle α0 of the module is directly related to the power generation efficiency of the entire system, this invention aims to maximize the initial tilt angle of the module while meeting the constraints, thereby improving power generation efficiency. The specific design constraints are as follows:

[0175] 2-1) Based on the local wind load, the limit value β of the component tilt angle is determined by formula (5);

[0176] 2-2) Determine the buoy's position at extreme low wave height H based on formula (11) min Swing angle ε min and extreme high wave high H max Swing angle ε under environmental conditions max ;

[0177] 2-3) The initial angle range of the component is determined by the limit value of the component tilt angle and the maximum and minimum values ​​of the floating body's pitch motion. The minimum component tilt angle α corresponds to the maximum value of the floating body's pitch motion. min The component tilt angle α corresponds to the minimum pitch motion of the floating body. max ;

[0178] 2 - 4) During the operation, the total angle of the component and the floating body does not exceed the limit value β;

[0179] From the constraint conditions 2 - 1) to 2 - 4), an optimization model with the maximum radiation dose received by the component as the objective can be obtained, as shown in Equation (23):

[0180]

[0181] 3) The specific process of the improved particle swarm optimization algorithm

[0182] Taking different initial inclination angles as design variables, continuously adjust the initial inclination angle during the optimization process to seek the maximum radiation dose received by the component, as Figure 3 shown. The specific process is as follows:

[0183] 3 - 1) Determine the mass M s , dimensions of the floating body, as well as the wave height H and period T of the wave;

[0184] 3 - 2) After verifying the boundary conditions of the floating body motion response in step (2), determine the minimum value f(α) of the objective function based on the minimum inclination angle min ;

[0185] 3 - 3) Initialize the parameters, including the inclination angle α, the maximum number of iterations Y1, and the termination condition, and calculate the irradiance received by the current inclination angle according to Equation (12);

[0186] 3 - 4) Generate new design schemes based on different inclination angles within the inclination angle range of the component, and calculate the new objective function f(α);

[0187] 3 - 5) If f(α) > f(α) min , enter the iterative loop, and update α i and the received irradiance f(α i ) during the loop; otherwise, re - initialize the inclination angle and iterate again;

[0188] 3 - 6) If α min < α i < α max , and f(α i ) > f(α), let α = α i ; if f(α i ) < f(α), keep α i = α; if α i is not within the range, then update α i again;

[0189] 3 - 7) If the maximum number of iterations Y1 is reached, output the optimal solution α iIf the tilt angle optimization ends, the iteration continues until an initial tilt angle α0 that maximizes irradiance within the tilt angle range is found.

[0190] 204: Combine the different wave conditions of the specific sea area, the initial tilt angle of the floating photovoltaic module obtained in step (3), and the irradiance of the tilt angle surface to calculate the total irradiance of the floating photovoltaic module at sea.

[0191] The step (4) specifically refers to calculating the total irradiance received by the component within a certain time period based on the wave conditions of the target ocean, including the wave height H, period T, and the tilt angle α0 optimized in step (3), combined with formula (20).

[0192] Practical application examples of this invention:

[0193] A. Environmental parameters

[0194] Considering the natural operating environment conditions of the project site and the selected floating structure, all key data are derived from on-site measurements and environmental monitoring results in the project sea area, thereby ensuring the scientific nature and engineering adaptability of the technical solution. Specific parameters are shown in Table 1 and Table 2.

[0195] Table 1. Floating Body Structure and Environmental Parameters

[0196]

[0197] Table 2 Wave parameters

[0198]

[0199] Based on the extreme conditions of the design waves and formulas (1)-(4), the maximum pitch angle range of the floating body is determined to be -10° to 10°, which is the boundary condition of the floating body motion. According to formula (5), the limit tilt angle of the component is calculated to be 18°. The calculation results of the floating body pitch response are compared with the simulation results. Figure 4 As shown, during the operating time, both exhibit high consistency, displaying the same periodic fluctuations with consistent frequencies and similar amplitudes. Overall, the calculation model can effectively describe the dynamic characteristics of the system, verifying its feasibility and effectiveness. The irradiance ranges for extreme conditions 1 and 2 are shown in Figure 5.

[0200] The impact of wave conditions on power generation efficiency

[0201] The design of photovoltaic module tilt angle needs to take into account the impact of wave environment, while also considering factors such as module tilt angle and radiation. Ensuring system stability and power generation efficiency is crucial, and the changes in module tilt angle under wave influence are important considerations. Figure 6 As shown.

[0202] The numerical analysis of the pitch response of the floating body is solved based on its structure. The results are as follows: (See table below) Figure 7 As shown, it can be concluded that as the wave height increases, the range of the buoy's pitch angle also increases, from a maximum of 1.231° at a wave height of 0.5m to 3.9° at a wave height of 1.5m.

[0203] The solution to the floating body motion under different period conditions with the same wave height of 1m is as follows: Figure 8 As shown, with the increase of the period, the angle change of the floating body gradually decreases, and the amplitude also gradually decreases. It decreases from 4.8° in a 3s period to 2.4° in a 6s period.

[0204] Taking the initial installation tilt angle of the photovoltaic panel as 5° as an example, the radiation and power generation under different wave conditions within one hour at noon are calculated, as shown in Table 3.

[0205] Table 3 Comparison of power generation efficiency under different wave conditions

[0206]

[0207]

[0208] Comparison of power generation efficiency before and after optimization C

[0209] The typical daily radiation levels in the project's sea area during the four seasons are as follows: Figure 9 As shown, the meteorological data comes from MeteoNorm 8.0 station. Irradiance is high and stable in spring and summer, resulting in higher power generation efficiency; irradiance is low in autumn and winter, limiting power generation. Before optimization, the modules were laid flat on the floating body, and their tilt angle changed entirely with the movement of the floating body. Considering the wave conditions in the project area, the average wave period is less than 5 seconds, the average significant wave height is less than 0.5 meters, and the maximum pitch angle of the floating body under normal operating conditions is 4.8°. After optimization, the initial tilt angle of the modules is 12°, leaving a safety margin while meeting the requirement that the maximum tilt angle of the modules under normal operating conditions does not exceed 18°.

[0210] By comparing the two design schemes before and after optimization, the typical daily power generation of the modules in all four seasons is obtained as follows: Figure 10 As shown, the optimized design significantly improves power generation efficiency, especially under conditions of large wave height (1m), where the power generation efficiency remains at a high level. The overall power generation efficiency is 13% to 16% higher than before optimization, verifying the adaptability of the design in complex marine environments.

[0211] Unless otherwise specified, the model numbers of the various devices in this embodiment of the invention are not limited, and any device that can perform the above functions is acceptable.

[0212] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of a preferred embodiment, and the sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0213] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for optimizing the power generation efficiency of a floating photovoltaic power generation system, characterized in that... It includes the following steps: (1) Analyze the wave conditions and the structure of the floating body to determine the motion response of the floating body in the marine environment and the boundary conditions for the oscillation of the floating body under the action of waves; (2) Build a hydrodynamic analysis model of the floating body and verify the motion response range of the floating body in step (1); (3) Taking the maximum amount of radiation received by the component as the optimization objective, combined with the tilted surface irradiance calculation model, the improved particle swarm algorithm is used as the optimization method to solve the initial tilt angle of the photovoltaic panel when maximizing the solar radiation energy received. (4) Calculate the total irradiance of the floating photovoltaic module at sea by combining the different wave conditions of the specific sea area, the initial tilt angle of the floating photovoltaic module obtained in step (3), and the irradiance of the tilt angle surface.

2. The method for optimizing the power generation efficiency of a floating photovoltaic power generation system according to claim 1, characterized in that... The wave conditions in step (1) refer to the wave height H and period T, and the floating structure includes the length, width, height and mass of the floating body.

3. The method for optimizing the power generation efficiency of a floating photovoltaic power generation system according to claim 1, characterized in that... In step (1), determining the motion response of the floating body in the marine environment means that, under the combined action of wind, waves, and water flow loads, the floating body will exhibit a motion mode with six degrees of freedom under the action of waves, and the motion equations are solved as shown in equation (1): In the formula, M s For structural mass, M a The additional mass is ω, the wave angular frequency is B, the damping is C (frequency-dependent), the hydrostatic stiffness is C, and the wave force is F. It is the acceleration of the object. ρ is the velocity of the object, and x is the displacement of the object; The motion response of the floating body in the time domain can be calculated by converting formula (1) into: In the formula, k(t-τ) is the memory function, F(t) is the dynamic force exerted by the wave on the floating body, and T(t) is the instantaneous impact load on the floating body.

4. The method for optimizing the power generation efficiency of a floating photovoltaic power generation system according to claim 3, characterized in that... The additional mass M a The memory function k(t) can be calculated by the following formula: The range of angles in which the floating body swings under extreme sea conditions is taken as the boundary condition for the pitching motion of the floating body. Combined with the effect of wind load, the limit value of the component tilt angle can be determined by equation (5). Based on the motion of the floating body, the initial installation tilt angle range of the component is determined, that is: the limit value of the component tilt angle minus the maximum value of the floating body motion. W=KW k Scosβ (5) In the formula, W is the design value of wind load; S is the actual area of ​​the component; W k β is the standard value of wind load; K is the matrix correction coefficient; β is the limit value of component tilt angle. In a marine environment, the influence of regular wave pairs on a floating body means that the angular oscillation of the floating body in the waves is a simple harmonic motion. Therefore, the angular change of the photovoltaic module under the action of regular waves can be expressed by equation (6): In the formula, α0 is the initial tilt angle of the photovoltaic module, ε is the amplitude of the change of the floating body under the action of waves; φ is the initial phase of the wave; and T is the wave period. For random or irregular waves composed of different wave heights, periods, and propagation directions, the wave is considered as a superposition of at least two simple harmonic cosine waves with random amplitudes, different and random frequencies, and random initial phases. Its form is as follows: In the formula, A i The wave amplitude is derived from the wave spectrum S(ω); φ i The initial phase of the wave; N is the total number of discrete frequency components; Δω i =ω i -ω i-1 ; In summary, the angle change of a photovoltaic module under the action of an irregular wave can be represented by equation (9): In the formula, φ j H represents the phase after wave superposition. a (ω i ) is the amplitude of the frequency response function, which is determined by formula (10).

5. The method for optimizing the power generation efficiency of a floating photovoltaic power generation system according to claim 4, characterized in that... In step (1), the boundary condition for the swaying of the floating body under the action of waves specifically refers to the maximum value of the pitch angle of the floating body under the combined action of external loads. The amplitude of the pitch motion of the floating body can be obtained by integrating formula (1), as shown in formula (11). In the formula, ρ is the density of water, taken as 1025 kg / m³. 3 g is the gravitational acceleration, taken as 9.8 N / kg; H is the wave height; L is the distance from the point of action of the wave to the center of rotation; A is the effective force-bearing area, i.e. the area below the water surface.

6. The method for optimizing the power generation efficiency of a floating photovoltaic power generation system according to claim 2, characterized in that... Step (2) is specifically based on the hydrodynamic analysis software AQWA. By building a finite element model, the motion response range of the floating body in step (1) is verified to accurately evaluate the dynamic characteristics of the floating body under wave conditions and verify the accuracy of the calculation results of formulas (1) to (4). The specific process includes the following: 2-1) Building a finite element model: Using the hydrodynamic analysis software AQWA, a finite element model of the floating body is constructed based on the geometric characteristics, material parameters and hydrodynamic characteristics of the floating body structure to simulate the dynamic response of the floating body under wave action. 2-2) Verify the pitch angle of the floating body: Using a hydrodynamic analysis model, the dynamic behavior of the floating body in the pitch direction is simulated by changing the wave height, period and direction of the waves. The pitch angle change curve of the floating body is extracted based on the simulation results, and the angle change of the floating body is used as the key input parameter for component tilt angle optimization. 2-3) Data acquisition: Based on the simulation results and calculation results of the floating body motion in step 2-2), the accuracy of the calculation results of formulas (1) to (4) is verified by comparing the simulation results with the calculation results. If the error between the calculation results and the simulation results is within 1%, it can be proven that the calculation results are accurate and meet the requirements. The calculation data of the floating body pitching motion is used as the data affecting the change of tilt angle when calculating the irradiance in step (3).

7. The method for optimizing the power generation efficiency of a floating photovoltaic power generation system according to claim 6, characterized in that... The calculation model for the irradiance of the inclined surface in step (3) is as follows: The solar radiation energy received by a fixed-tilt photovoltaic module includes three parts: direct radiation energy, diffuse radiation energy, and reflected radiation energy. In the formula, G is the total radiant energy; G b For direct radiation energy; G d For scattered radiation energy; G g To reflect radiation energy; The angle of incidence of sunlight θ is given by equation (13): Where α is the angle between the surface of the photovoltaic cell and the horizontal plane. γ is the local geographic latitude angle, n is the azimuth angle of the inclined plane, δ is the hour angle, and δ is the declination angle. 1) Direct radiation energy G b =ξ0I sc P m (14) In the formula, G b ξ0 is the direct radiation energy received by the horizontal surface; I is the Earth's orbital eccentricity correction factor; sc The solar constant represents the amount of solar radiation received per unit area per unit time at the upper boundary of the Earth's atmosphere perpendicular to sunlight. In engineering calculations, it is typically taken as 1367 W / m². 2 P is the atmospheric transparency coefficient; m is the atmospheric optical quality. The calculation methods for the Earth orbit eccentricity correction coefficient ξ0 and the atmospheric optical mass m are shown in formulas (15) and (16), respectively. 2) Scattered radiation energy Theoretically, it is difficult to accurately calculate the solar scattered radiation energy on the Earth's surface. Generally, empirical calculation formulas based on actual measurements are used (17): Wherein, h is the solar altitude angle, and the calculation method is shown in equation (18); 3) Reflected radiation energy After solar radiation reaches the ground, the horizontal reflected irradiance G g Horizontal direct irradiance G b and horizontal scattered irradiance G d The sum of the values ​​and the influence of the reflection coefficient q are considered, therefore, the reflected radiation energy G can be calculated according to equation (19). g : G g =q(G b +G d ) (19) In the formula, q is the ground reflectivity; From the above formula, we can see that the radiant energy G received by the fixed-tilt photovoltaic panel within time R is... R Equation (20) represents:

8. The method for optimizing the power generation efficiency of a floating photovoltaic power generation system according to claim 11, characterized in that... The optimization method in step (3) is to use an improved particle swarm optimization algorithm to solve for the initial tilt angle of the photovoltaic panel when maximizing the solar radiation energy received. The specific process is as follows: 1) Define the problem and objective function The optimization objective comprehensively considers the initial tilt angle α0 of the component, the wave height H, and the period T. The influence of wave height and period on the pitch angle can be calculated by equation (11), and the specific objective function is shown in (21): In the formula, G(t) is the amount of radiation received by the photovoltaic module with a tilt angle of α at time t; the initial tilt angle that maximizes the amount of radiation received by the module is taken as the optimization objective, that is: maxG=f(α0)(22) 2) Design constraints Since the initial tilt angle α0 of the components is directly related to the power generation efficiency of the entire system, the specific design constraints are as follows: 2-1) Based on the local wind load, the limit value β of the component tilt angle is determined by formula (5); 2-2) Determine the buoy's position at extreme low wave height H based on formula (11) min Swing angle ε min and extreme high wave high H max Swing angle ε under environmental conditions max ; 2-3) The initial angle range of the component is determined by the limit value of the component tilt angle and the maximum and minimum values ​​of the floating body's pitch motion. The minimum component tilt angle α corresponds to the maximum value of the floating body's pitch motion. min The component tilt angle α corresponds to the minimum pitch motion of the floating body. max ; 2-4) During operation, the total angle of the components and the float shall not exceed the limit value β; From constraints 2-1) to 2-4), an optimization model with the maximum radiation received by the component as the objective can be obtained, as shown in equation (23): 3) The specific process of improving the particle swarm optimization algorithm Using different initial tilt angles as design variables, the initial tilt angle is continuously adjusted during the optimization process to seek the maximum radiation received by the component. The specific process is as follows: 3-1) Determine the mass M of the buoy based on step (1). s Size, wave height H, and period T; 3-2) After verifying the boundary conditions of the floating body's motion response in step (2), determine the minimum value of the objective function f(α) based on the minimum tilt angle. min ; 3-3) Initialize the parameters, including the tilt angle α, the maximum number of iterations Y1 and the termination condition, and calculate the irradiance at the current tilt angle according to formula (12); 3-4) Generate new design schemes based on different tilt angles within the component tilt angle range, and calculate the new objective function f(α); 3-5) If f(α)>f(α) min Enter the iterative loop, and update α during the loop. i and the irradiance f(α) received i ); Otherwise, reinitialize the tilt angle and iterate again; 3 - 6) If α min < α i < α max , and f(α i ) > f(α), let α = α i ; if f(α i ) < f(α), keep α i = α; if α i is not within the range, then update α i again; 3-7) If the maximum number of iterations Y1 is reached, output the optimal solution α. i If the tilt angle optimization ends, the iteration continues until an initial tilt angle α0 that maximizes irradiance within the tilt angle range is found.

9. The method for optimizing the power generation efficiency of a floating photovoltaic power generation system according to claim 1, characterized in that... The step (4) specifically refers to calculating the total irradiance received by the component within a certain time period based on the wave conditions of the target ocean, namely: wave height H, period T, and the tilt angle α0 optimized in step (3), combined with formula (20).

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