A solar conversion cosine effect loss calculation and output thermal power optimization method

Abstract

This invention discloses a method for calculating cosine effect loss and optimizing output thermal power in solar energy conversion. First, geographical and temporal parameters are obtained to establish a geometric model of the heliostat field. Based on the solar altitude angle, a cosine loss algorithm model is constructed, deriving a formula for calculating cosine efficiency with local latitude, solar declination angle, and solar hour angle as variables, thus achieving dynamic and accurate calculation of cosine loss. On this basis, an objective function is established to maximize the annual average output thermal power per unit mirror area. Considering constraints such as the heliostat's operating status, absorber tower location, installation height and dimensions, center distance, annular radius, and staggered layout, the optimal mirror field layout parameters and operating strategy are solved through year-round time-domain simulation. This invention accurately quantifies cosine loss through analytical algorithms and combines multi-constraint optimization to improve the annual output thermal power of the heliostat field, reduce shading and cosine loss, and provide support for the efficient operation of tower-type solar thermal power generation systems.

Description

Technical Field

[0001] This invention relates to the field of tower solar thermal power generation, specifically to a method for calculating solar energy conversion cosine effect loss and optimizing output thermal power. Background Technology

[0002] Solar energy, as a core source of clean energy, directly impacts the scale of energy utilization through its conversion efficiency. However, in solar thermal and photovoltaic power generation systems, an angle exists between the incident sunlight and the normal direction of the collector / power generation equipment surface. The effective receiving area decreases sharply as the incident angle increases; this phenomenon is known as the "cosine effect." Existing heliostat field optimization methods often focus on instantaneous peak power, neglecting the dynamic impact of the sun's annual motion on cosine losses. This results in insufficient power output during low solar altitude angle periods such as the spring and autumn equinoxes, leading to poor annual power output stability. While existing technologies partially alleviate this problem through single-axis or dual-axis tracking systems, these systems are costly, complex to maintain, and cannot completely eliminate the losses.

[0003] In the field of tower solar thermal power generation, heliostats are a core component, and their performance directly affects the power generation efficiency and stability of the entire system. The rational setting of heliostat layout parameters plays a decisive role in the energy flow distribution of the collectors and the system's thermal power output. However, traditional heliostat design methods mainly rely on empirical trial and error. Designers constantly try to adjust layout parameters based on past experience, a process that is not only time-consuming and resource-intensive but also difficult to comprehensively consider various complex factors. Due to the lack of scientific and systematic optimization methods, traditional methods are prone to efficiency losses, preventing heliostats from reaching their maximum performance. Furthermore, empirical trial and error methods often only yield locally optimal solutions, failing to achieve optimal heliostat layout from a global perspective. Therefore, developing a method for accurately calculating cosine effect losses has become a key requirement for overcoming the bottleneck in solar energy conversion efficiency. Summary of the Invention

[0004] To address the aforementioned issues and improve the overall performance of tower solar thermal power generation systems, this invention proposes an innovative method that combines output thermal power optimization with solar angle. This method aims to accurately determine the optimal layout parameters of heliostat fields at various solar angles, providing an efficient reference for heliostat field design and propelling tower solar thermal power generation technology to a new level.

[0005] The technical solution adopted in this invention is: a method for calculating the cosine effect loss of solar energy conversion, comprising the following steps: Step S1: Obtain the geographical and temporal parameters of the solar energy conversion system, including the local latitude. The time parameters include the solar declination angle. and solar hour angle ; Step S2: Establish a geometric relationship model of the heliostat field. The geometric relationship model is used to characterize the relative spatial positions between the following elements: heliostat, incident light reflected by the heliostat, reflected light directed towards the solar collector after reflection by the heliostat, and solar collector; wherein, the angle between the incident light and the reflected light is equal to the angle between the normal of the heliostat and each light ray. Step S3: Establish the cosine loss algorithm model: in, For cosine loss, Solar altitude angle; Step S4: Calculate the solar altitude angle using the parameters obtained in step S1; Step S5: Based on the parameters obtained in the above steps, the cosine efficiency formula is calculated as follows: in, The latitude is the local latitude, with North latitude as the positive value. The solar declination angle; It is the solar hour angle.

[0006] A method for optimizing the output thermal power of solar energy conversion using the cosine effect includes the following steps: Step S1: Using the cosine loss calculation method described in claim 1, obtain the cosine efficiency of each heliostat at any time. ; Step S2: Establish an objective function that maximizes the annual average output heat power per unit mirror area: in, This represents the average annual output heat power per unit mirror area. For the first The optical efficiency of a mirror Indicates the first The size of the solar altitude angle, This is the correlation coefficient of normal direct radiation irradiance.

[0007] Step S3: Set the constraint set, including: Heliostat operating status constraints; Absorption tower location constraints; Heliostat installation height and dimensional constraints; Constraints on the center distance of heliostats and the radius of the annulus; Constraints on the number of heliostats and staggered layout.

[0008] Step S4: Optimize and design the installation height and dimensions between heliostats.

[0009] Step S5: Perform time-domain simulations for different dates throughout the year, iterating through each date k, dynamically determining the working status of each heliostat, and solving for the objective function while satisfying the constraints described in Step S3 and the design optimization described in Step S4. Maximize the mirror field layout parameters and operating strategy.

[0010] Step S6: Configure the heliostat field according to the parameters optimized in step S5, and control the angle of each heliostat according to the optimized operation strategy.

[0011] Preferably, in step S3 of a method for optimizing the output thermal power of a solar energy conversion cosine effect, the working state constraint adopts a 0-1 programming constraint.

[0012] Preferably, in a method for optimizing the output thermal power of solar energy conversion cosine effect, the heliostats on the same ring have the same installation height, the mirror height and installation height on different rings increase arithmetically with the ring radius, and the mirror width on all rings remains consistent; wherein, the installation height of the heliostats installed on the n rings... The dimensions of the heliostat and the heliostat respectively satisfy the following: , in express Installation height of the heliostat on the ring This represents the coefficient for increasing the installation height of the heliostat; the installation height of the heliostats between each ring increases sequentially in an arithmetic sequence; Indicates the width of the mirror. Indicates the height of the mirror surface.

[0013] Preferably, in a method for optimizing the output thermal power of solar energy conversion cosine effect, the center distance constraint between each heliostat base satisfies: in This indicates the distance between the centers of the two heliostat bases. This indicates the width of the mirror surface, which depends on the heliostat with a longer mirror surface.

[0014] Preferably, in a method for optimizing the output thermal power of solar energy conversion using the cosine effect, the radius constraint of the layout ring is such that the first layout ring is positioned 100 meters from the absorption tower, as specifically described below: in, Indicates the radius of the open space surrounding the absorption tower. express The radius of the first circular ring is such that half of the heliostat's area is inside the first circular ring. The width considered in the calculation of the radius of each circular ring is the width of the heliostat located on its own circular ring.

[0015] Preferably, in a method for optimizing the output thermal power of solar energy conversion cosine effect, the spatial coordinates of each heliostat in the heliostat field are determined based on the layout annular radius constraint, the heliostat number constraint, and the staggered layout constraint.

[0016] Preferably, in a method for optimizing the output thermal power of solar energy conversion cosine effect, the height of the heliostats between adjacent rings increases sequentially using an arithmetic sequence, while the width of the heliostats remains constant.

[0017] Preferably, the formula for calculating the solar altitude angle in step S4 of the method for calculating the cosine effect loss of solar energy conversion is: in, The solar altitude angle, The latitude is the local latitude, with North latitude as the positive value. The solar declination angle; It is the solar hour angle.

[0018] A tower-type solar thermal power generation heliostat field uses the above method to calculate cosine loss and optimize output thermal power.

[0019] The beneficial effects of this invention are mainly reflected in the following aspects: This invention patent constructs a cosine loss algorithm model based on solar altitude angle, local latitude, solar declination angle, and time angle, accurately quantifies the energy loss caused by the angular reflection relationship of heliostats, and derives a cosine efficiency formula that can be calculated in real time. This effectively solves the calculation error caused by neglecting spatiotemporal dynamic parameters and geometric relationships in traditional methods, improves the accuracy of heliostat field layout optimization and tracking strategy control, significantly reduces the cosine loss in the solar energy conversion process, and provides key theoretical support for improving the overall concentration efficiency of solar thermal power generation systems.

[0020] In terms of thermal power optimization, an optimization method with output thermal power as the objective function was established, and comprehensive and reasonable constraints were set to effectively solve the problem of maximizing the output thermal power of heliostat fields while meeting rated power requirements. This method fully considers various factors such as changes in solar altitude angle, heliostat operating status, and absorber tower location, and precisely optimizes parameters such as heliostat installation height, dimensions, base center distance, and layout ring radius. The installation height and dimensions of the heliostats are rationally designed, with smaller heights and dimensions closer to the absorber tower to reduce shading losses. Parameters are determined based on various constraints to ensure the maintenance and cleaning needs of the heliostats and to rationally plan the layout. This technology can significantly improve the overall performance of heliostat fields, increase the output thermal power per unit area, and reduce energy loss, providing strong support for the efficient and stable operation of tower-type solar thermal power generation systems, and has extremely high practical value and economic benefits. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the geometric relationship model of the heliostat field of the present invention; Figure 2 This is a schematic diagram of the cosine loss calculation logic of the present invention; Figure 3 This is a schematic diagram of the output thermal power optimization logic of the present invention. Detailed Implementation

[0022] This invention proposes a method for calculating cosine effect loss in solar energy conversion and optimizing output thermal power. For the first time, it establishes a direct functional mapping relationship between cosine loss and the real-time changing solar altitude angle. By introducing astronomical parameters such as solar declination and solar hour angle, a precise mathematical bridge is constructed from "solar position" to "specular reflection efficiency." This analytical algorithm no longer relies on fixed empirical coefficients but can dynamically capture changes in the incident angle of light at different times and geographical locations, thus theoretically achieving "instantaneous and accurate calculation" of cosine loss, laying a solid mathematical foundation for subsequent energy flux density distribution simulation.

[0023] like Figure 1-3 As shown, this invention provides a method for calculating the cosine effect loss of solar energy conversion, including the following steps: Step S1: Obtain the geographical and temporal parameters of the solar energy conversion system, including the local latitude. The time parameters include the solar declination angle. and solar hour angle ; Step S2: Establish a geometric relationship model of the heliostat field. The geometric relationship model is used to characterize the relative spatial positions between the following elements: heliostat, incident light reflected by the heliostat, reflected light directed towards the solar collector after reflection by the heliostat, and solar collector; wherein, the angle between the incident light and the reflected light is equal to the angle between the normal of the heliostat and each light ray. Step S3: Establish the cosine loss algorithm model: in, For cosine loss, Solar altitude angle; Step S4: Calculate the solar altitude angle using the parameters obtained in step S1; Step S5: Based on the parameters obtained in the above steps, the cosine efficiency formula is calculated as follows: in, The latitude is the local latitude, with North latitude as the positive value. The solar declination angle; It is the solar hour angle.

[0024] like Figure 1-3 As shown, this invention provides a method for optimizing the output thermal power of solar energy conversion using the cosine effect, comprising the following steps: Step S1: Using the cosine loss calculation method described in claim 1, obtain the cosine efficiency of each heliostat at any time. ; Step S2: Establish an objective function that maximizes the annual average output heat power per unit mirror area: in, This represents the average annual output heat power per unit mirror area. For the first The optical efficiency of a mirror Indicates the first The size of the solar altitude angle, This is the correlation coefficient of normal direct radiation irradiance.

[0025] Step S3: Set the constraint set, including: Heliostat operating status constraints; Absorption tower location constraints; Heliostat installation height and dimensional constraints; Constraints on the center distance of heliostats and the radius of the annulus; Constraints on the number of heliostats and staggered layout.

[0026] Step S4: Optimize and design the installation height and dimensions between heliostats.

[0027] Step S5: Perform time-domain simulations for different dates throughout the year, iterating through each date k, dynamically determining the working status of each heliostat, and solving for the objective function while satisfying the constraints described in Step S3 and the design optimization described in Step S4. Maximize the mirror field layout parameters and operating strategy.

[0028] Step S6: Configure the heliostat field according to the parameters optimized in step S5, and control the angle of each heliostat according to the optimized operation strategy.

[0029] in, Figure 1 To construct a geometric model of the heliostat field, including the heliostat, incident rays, reflected rays, and solar collectors; Figure 2 This outlines the overall process for calculating cosine efficiency loss. Figure 3 The optimization logic for the overall output heat power of the cosine effect optimization method in solar energy conversion is as follows: The workflow of a specific implementation is as follows: 1. Cosine Loss Algorithm Model (1) in, For cosine loss, The solar altitude angle, Figure 1 The middle angle 2 is the solar altitude angle.

[0030] The derivation process is as follows: Depend on Figure 1 It can be known that the reflection height The range can be represented as: (2) in, This indicates the distance between the center of the heliostat and the center of the solar collector. This represents the cosine loss angle, which is the solar altitude angle.

[0031] The horizontal distance between the heliostat and the absorption tower can be expressed using trigonometric functions from the above diagram as follows: (3) in, This indicates the horizontal distance between the heliostat and the absorption tower.

[0032] Formula for calculating solar altitude angle (4) in, The solar altitude angle, The latitude is the local latitude, with North latitude as the positive value. The solar declination angle; It is the solar hour angle.

[0033] The cosine efficiency is calculated as follows: (5) By solving the system of equations (1) (5) Solving for the cosine efficiency formula yields: (6) in, The latitude is the local latitude, with North latitude as the positive value. The solar declination angle; It is the solar hour angle.

[0034] 2. Output thermal power optimization The heliostat field needs to maximize its output heat power while meeting the rated power requirements. Furthermore, the size of each heliostat can vary, and the installation height of some heliostats may also differ. Therefore, the following output heat power is used as an example. Establish an optimization method for the objective function: (7) By performing the above calculations, the output heat power per unit area can be solved under decentralized conditions. The parameters used in this method are as follows: This represents the average annual output heat power per unit mirror area. For the first The optical efficiency of a mirror Indicates the first The solar altitude angle varies slightly depending on the number of days in the same time period, as the sun continuously travels between the Tropic of Cancer and the Tropic of Capricorn. e represents the average daily heat output per unit mirror area. This is the correlation coefficient of normal direct radiation irradiance.

[0035] Constraints: (1) Constraints on the working state of the heliostat: Planning constraints Because the sun's motion is directional, there are situations where some heliostats do not operate, which is consistent with... planning.

[0036] (8) Using the above By planning and determining whether the heliostats are operational, it is possible to determine which heliostats are working and which are not operating at a given moment.

[0037] (2) Location constraints of the absorption tower By combining the calculation formula (9), the location coordinates of the absorption tower can be obtained.

[0038] (9) in, Indicates in The coordinates of the absorption tower are the coordinates of the heat collector receiving the heat power at the coordinates that satisfy this condition.

[0039] (3) Constraints on the installation height of heliostats The installation height of heliostats falls within a certain range. Analyzing the installation height requirements, we can simplify it as follows: (10) in, The installation height of the heliostat is given, and according to the assumptions of the method, the installation height of the heliostat is the same on each ring, but the installation height of the heliostat differs on different rings.

[0040] (4) Heliostat size constraints The height of the heliostat mirror must not exceed its width, and to ensure that the mirror does not touch the ground during rotation, the specific constraints are as follows: (11) in, Indicates the width of the mirror. This indicates the mirror height, and according to the method's assumptions, the heliostats on each ring have the same size, while the sizes of the heliostats on different rings differ.

[0041] (5) Constraint on the center distance between the two heliostat bases To meet the requirements for heliostat maintenance and cleaning, the distance between the centers of the two heliostats needs to be constrained accordingly: (12) in, This represents the distance between the centers of the two heliostat bases. According to the method assumptions, the mirror width considered for the distance between the centers of the two heliostat bases should be the width of the longer heliostat to prevent inconvenience caused by choosing a shorter width.

[0042] (6) Constraints on the radius of the circular ring Let the first layout ring start from Starting from the boundary line, no heliostats shall be constructed within 100 meters of the absorption tower, as detailed below: (13) in, Indicates the radius of the open space surrounding the absorption tower. express The radius of the first circular ring is such that half of the heliostat's area is inside the first circular ring. The width considered in the calculation of the radius of each circular ring is the width of the heliostat located on its own circular ring.

[0043] (7) Constraint on the number of heliostats The specific details regarding the number of heliostats are as follows: (14) in, express The number of heliostats on the ring. This indicates the minimum total number of heliostats required. MW stands for megawatts, and DNI stands for direct normal irradiance.

[0044] (8) Constraints on the staggered positions of heliostats The heliostats on the ring are staggered to minimize unnecessary shading losses. The coordinates of the heliostats are set to... The specific description is as follows: (15) in, Indicates in The coordinates of each heliostat on the ring can be solved by combining formulas (13), (14), and (15).

[0045] Heliostat parameter design (1) Heliostat installation height During the mirror reflection process, if the heliostat near the absorption tower is installed too high, the light reflected by the rear heliostat will be easily blocked, resulting in shadow loss. Therefore, the installation height of the heliostat can be reasonably designed, that is, the closer it is to the absorption tower, the smaller the installation height of the heliostat. The installation height of each heliostat has a functional relationship, as shown in formula (16): (16) express Installation height of the heliostat on the ring This represents the coefficient for increasing the installation height of the heliostat; the installation height of the heliostats between each ring increases sequentially in an arithmetic sequence.

[0046] (2) Different sizes of heliostats To avoid the heliostats near the absorption tower being too large and causing shadows to the heliostats behind them, the size of the heliostats can be reasonably designed. That is, the closer to the absorption tower, the smaller the size of the heliostat. The size of each heliostat has a functional relationship, as shown in formula (17): (17) According to the model's assumptions, all mirrors have the same width; Representing the width of the heliostat and the corresponding Height of the heliostat on the ring The coefficient representing the increase in heliostat height is such that the height of the heliostat increases sequentially between each ring in an arithmetic progression, while the width remains constant. Therefore, the dimensions of the heliostat follow an arithmetic progression. The above formula can be simplified as follows: (18) in, The height is indicated as being in The cumulative height of the heliostats on the circular ring. This represents the height growth rate on different rings.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. All modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for calculating the cosine effect loss in solar energy conversion, characterized in that, Includes the following steps: Step S1: Obtain the geographical and temporal parameters of the solar energy conversion system, including the local latitude. The time parameters include the solar declination angle. and solar hour angle ; Step S2: Establish a geometric relationship model of the heliostat field. The geometric relationship model is used to characterize the relative spatial positions between the following elements: heliostat, incident light reflected by the heliostat, reflected light directed towards the solar collector after reflection by the heliostat, and solar collector; wherein, the angle between the incident light and the reflected light is equal to the angle between the normal of the heliostat and each light ray. Step S3: Establish the cosine loss algorithm model: in, For cosine loss, Solar altitude angle; Step S4: Calculate the solar altitude angle using the parameters obtained in step S1; Step S5: Based on the parameters obtained in the above steps, the cosine efficiency formula is calculated as follows: in, The latitude is the local latitude, with North latitude as the positive value. The solar declination angle; It is the solar hour angle.

2. A method for optimizing the output thermal power of solar energy conversion using the cosine effect, characterized in that, Includes the following steps: Step S1: Using the cosine loss calculation method described in claim 1, obtain the cosine efficiency of each heliostat at any time. ; Step S2: Establish an objective function that maximizes the annual average output heat power per unit mirror area: in, This represents the average annual output heat power per unit mirror area. For the first The optical efficiency of a mirror Indicates the first The size of the solar altitude angle, This is the correlation coefficient of normal direct radiation irradiance. Step S3: Set the constraint set, including: Heliostat operating status constraints; Absorption tower location constraints; Heliostat installation height and dimensional constraints; Constraints on the center distance of heliostats and the radius of the annulus; Constraints on the number of heliostats and staggered layout. Step S4: Optimize and design the installation height and dimensions between heliostats. Step S5: Perform time-domain simulations for different dates throughout the year, iterating through each date k, dynamically determining the working status of each heliostat, and solving for the objective function while satisfying the constraints described in Step S3 and the design optimization described in Step S4. Maximize the mirror field layout parameters and operating strategy. Step S6: Configure the heliostat field according to the parameters optimized in step S5, and control the angle of each heliostat according to the optimized operation strategy.

3. The method for optimizing the output thermal power of solar energy conversion using the cosine effect according to claim 2, characterized in that, In step S3, the working state constraints adopt 0-1 programming constraints.

4. The method for optimizing the output thermal power of solar energy conversion using the cosine effect according to claim 2, characterized in that, Heliostats on the same ring have the same installation height. The mirror height and installation height on different rings increase arithmetically with increasing ring radius, and the mirror width remains constant on all rings. The installation height of the heliostat installed on ring n is... The dimensions of the heliostat and the heliostat respectively satisfy the following: ， in express Installation height of the heliostat on the ring This represents the coefficient for increasing the installation height of the heliostat; the installation height of the heliostats between each ring increases sequentially in an arithmetic sequence; Indicates the width of the mirror. Indicates the height of the mirror surface.

5. The method for optimizing the output thermal power of solar energy conversion using the cosine effect according to claim 2, characterized in that, The center-to-center distance constraint between each heliostat base satisfies: in This indicates the distance between the centers of the two heliostat bases. This indicates the width of the mirror surface, which depends on the heliostat with a longer mirror surface.

6. The method for optimizing the output thermal power of solar energy conversion using the cosine effect according to claim 2, characterized in that, The radius constraint of the layout rings is that the first layout ring is set at a distance of 100 meters from the absorption tower, as specifically described below: in, Indicates the radius of the open space surrounding the absorption tower. express The radius of the first circular ring is such that half of the heliostat's area is inside the first circular ring. The width considered in the calculation of the radius of each circular ring is the width of the heliostat located on its own circular ring.

7. A method for optimizing the output thermal power of solar energy conversion using the cosine effect according to any one of claims 2 or 6, characterized in that, Based on the layout annular radius constraint, the number of heliostats constraint, and the staggered layout constraint, the spatial coordinates of each heliostat in the heliostat field are determined.

8. The method for calculating cosine effect loss in solar energy conversion and optimizing output thermal power according to claim 2, characterized in that, The height of the heliostats between adjacent rings increases sequentially in an arithmetic sequence, while the width of the heliostats remains constant.

9. The method for calculating the cosine effect loss of solar energy conversion according to claim 1, characterized in that, The formula for calculating the solar altitude angle in step S4 is as follows: in, The solar altitude angle, The latitude is the local latitude, with North latitude as the positive value. The solar declination angle; It is the solar hour angle.

10. A tower-type solar thermal power generation heliostat field, characterized in that, The method described in any one of claims 1-9 is used to calculate cosine loss and optimize output thermal power.

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