Method for calculating near-ground received radiation quantity

Abstract

The invention provides a near-ground received radiation quantity calculation method, and belongs to the technical field of solar energy resource evaluation, and the method comprises the steps: S1, obtaining the historical data of astronomical parameters of a to-be-calculated region, the astronomical parameters comprise a radiation period, a solar constant, geographic latitude, a sun-earth distance, solar declination, sunrise and sunset hour angles, total ground radiation quantity, sunshine duration, half-day sunshine duration and astronomy difference; s2, dividing the historical data of the astronomical parameters into twenty-four groups according to solar terms; s3, based on grouping, 24 ground total radiation quantity calculation equations are constructed respectively; the historical data of the astronomical parameters are divided into twenty-four groups according to the solar term days over the years, the time range is refined through the ground total radiation quantity calculation formula of each group, the linear regression relation between the ground total radiation quantity and the sunshine percentage is accurately fitted, and the deviation between the measured data of the meteorological station and the formula calculation result is remarkably reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solar resource assessment, and particularly relates to a method for calculating near-surface received radiation. BACKGROUND

[0002] The total solar radiation is the most important energy source on the earth's surface, an important factor in climate formation and change, and a necessary resource for production and construction. Accurately calculating the total solar radiation data of each region is the first step for the development and utilization of solar energy resources.

[0003] At present, the calculation method is mainly based on the principles of climatology: according to the measured data of the meteorological station in the region, an empirical formula of the total solar radiation of each month is established. A typical method is the relationship between the sunshine percentage and the total solar radiation proposed by Angstrom, which is calculated with the data from January to December to obtain the empirical coefficients of the model.

[0004] However, due to the influence of many factors, there are differences in the total radiation of each region. Among them, the astronomical (solar constant, distance between the earth and the sun, solar declination, hour angle, etc.), geographical (latitude, longitude), and geometric (solar elevation angle) factors mainly affect the solar radiation reaching the top of the atmosphere; and when the radiation passes through the atmosphere, the physical (atmospheric water content, ozone content), and meteorological (sunshine percentage) factors also affect the total solar radiation. The actual meteorological conditions change randomly every month, and the parameters fluctuate greatly at the beginning, middle and end of the month, and many factors are easily affected by each other. These problems lead to large deviations between the results obtained by the traditional climatological calculation method and the measured values.

[0005] Therefore, how to improve the calculation accuracy of the total solar radiation has become one of the important problems to be solved in the process of solar resource assessment. SUMMARY

[0006] To solve the above problems of the prior art, the application provides a method for calculating the near-surface received radiation, which aims to determine the range of different parameters in the climatological calculation formula by combining meteorological data with natural rhythm calendars, fit the empirical formula of climatological calculation respectively, and then calculate the annual total solar radiation, so as to improve the accuracy of the calculation results.

[0007] To achieve the above purpose, the application provides the following technical scheme:

[0008] A method for calculating the near-surface received radiation, comprising the following steps:

[0009] Step S1: obtaining the historical data of astronomical parameters of the region to be calculated, the astronomical parameters including radiation period, solar constant, geographical latitude, distance between the earth and the sun, solar declination, sunrise and sunset hour angle, total radiation on the ground, sunshine duration, half-day sunshine hours, and atmospheric refraction;

[0010] Step S2: Divide the historical data of the astronomical parameters into twenty-four groups according to the solar terms;

[0011] Step S3: Based on the grouping, construct twenty-four equations for calculating total ground radiation.

[0012] Furthermore, the specific process of step S2 is as follows: the historical data of the astronomical parameters are divided into twenty-four groups according to the solar terms of each year. The first group is from the day after the Great Cold of the previous year to the Beginning of Spring of the current year; the second group is from the day after the Beginning of Spring to Rain Water; the third group is from the day after Rain Water to Awakening of Insects; the fourth group is from the day after Awakening of Insects to the Spring Equinox; the fifth group is from the day after the Spring Equinox to Pure Brightness; the sixth group is from the day after Pure Brightness to Grain Rain; the seventh group is from the day after Grain Rain to the Beginning of Summer; the eighth group is from the day after the Beginning of Summer to Grain Buds; the ninth group is from the day after Grain Buds to Grain in Ear; the tenth group is from the day after Grain in Ear to the Summer Solstice; and the tenth group is from the day after the Summer Solstice to Minor Heat. Group 11; Group 12 is from the day after Lesser Heat to Greater Heat; Group 13 is from the day after Greater Heat to the Beginning of Autumn; Group 14 is from the day after the Beginning of Autumn to the End of Heat; Group 15 is from the day after the End of Heat to White Dew; Group 16 is from the day after White Dew to the Autumnal Equinox; Group 17 is from the day after the Autumnal Equinox to Cold Dew; Group 18 is from the day after Cold Dew to Frost's Descent; Group 19 is from the day after Frost's Descent to the Beginning of Winter; Group 20 is from the day after Lesser Snow to Lesser Snow; Group 21 is from the day after Lesser Snow to Greater Snow; Group 22 is from the day after Greater Snow to the Winter Solstice; Group 23 is from the day after the Winter Solstice to Lesser Cold; Group 24 is from the day after Lesser Cold to Greater Cold.

[0013] Furthermore, step S3 includes:

[0014] Step S31: Calculate the total solar astronomical radiation and sunshine percentage for each group;

[0015] Step S32: Based on the total solar astronomical radiation and sunshine percentage, combined with the total ground radiation in the astronomical parameters, the least squares method is used to obtain the calculation equation for the total ground radiation through regression fitting.

[0016] Furthermore, step S31 includes:

[0017] Step S311: Calculate the total solar astronomical radiation. The calculation formula is as follows:

[0018]

[0019] Where Q0 represents the total solar astronomical radiation, in MJ / (m²). 2 ·d); T is the period (24×60×60s); I0 is the solar constant, taken as 13.67×10 -4 [MJ / (m2·s)]; δ is the solar declination, which is positive north of the celestial equator and negative south of it, in radians (rad); ω0 is the sunrise and sunset angle, which is positive west of true solar noon and negative east of it, in radians (rad). The latitude is expressed in radians (rad).

[0020] Step S312: Calculate the sunshine percentage, the formula is as follows:

[0021] S = T0 / T A (2)

[0022] Where S is the percentage of sunshine, T0 is the duration of sunshine, and T A For the duration of the photo.

[0023] Furthermore, in step S32, the equation for calculating the total ground radiation is:

[0024] Q = Q0(a + bS) (3)

[0025] Where Q is the total ground radiation, in MJ / (m²) 2 ·d); a and b are empirical coefficients, obtained by regression fitting using the least squares method.

[0026] Furthermore, in step S311: the square of the relative distance between the Sun and Earth is calculated using equation (4):

[0027]

[0028] Where ρ is the relative distance between the Earth and the Sun, and J is the day sequence within the year.

[0029] Furthermore, in step S311: the solar declination is calculated using equation (5):

[0030] δ=0.006894-0.399512cosX+0.006799cos2X+0.000896sin2X (5)

[0031] -0.002689cos3X + 0.001516sin3X

[0032] Where X is calculated by equation (6):

[0033] X = 2π(J-1) / 365 (6)

[0034] Where J represents the date sequence within the year.

[0035] Furthermore, in step S311: the sunrise and sunset time angles are calculated using equation (7):

[0036]

[0037] Where δ is the solar declination, which is positive north of the celestial equator and negative south of it, and is in radians (rad). ω0 is the sunrise and sunset angle, which is positive west of true solar noon and negative east of it, and is in radians (rad). The latitude is expressed in radians (rad).

[0038] Furthermore, in step S312, the sunshine duration is read from the acquired astronomical parameters, and the sunshine duration is calculated using equation (8):

[0039] T A =2×T B (8)

[0040] Among them, T B The number of hours of sunshine per half-day is calculated using formula (9):

[0041]

[0042] Where γ is the atmospheric difference; φ is the local latitude; and δ is the solar declination.

[0043] Furthermore, the method for calculating near-ground received radiation also includes:

[0044] Step S4: Obtain real-time data of astronomical parameters for the area to be calculated and predict the total ground radiation.

[0045] Compared with the prior art, the present invention has at least the following beneficial effects:

[0046] 1. This invention fully considers the influence of solar term changes, and the calculated empirical formula can more accurately describe the linear regression relationship between total solar radiation and sunshine percentage, thereby assessing the abundance of solar energy resources in a region and providing reliable data support for the rational development and utilization of solar energy in the future.

[0047] 2. This invention divides the historical data of the astronomical parameters into twenty-four groups according to the solar terms of each year. The calculation formula for the total ground radiation of each group refines the time range, accurately fits the linear regression relationship between the total ground radiation and the sunshine percentage, and significantly reduces the deviation between the meteorological station's measurement data and the formula calculation results. Attached Figure Description

[0048] Figure 1 This is a schematic diagram illustrating a method for calculating near-ground received radiation according to an embodiment of the present invention. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0051] To better understand the purpose, process, and function of this invention, the following detailed description of a method for calculating near-ground received radiation is provided in conjunction with the accompanying drawings.

[0052] Example 1

[0053] like Figure 1 As shown, the present invention provides the following technical solution:

[0054] A method for calculating near-ground received radiation includes the following steps:

[0055] Step S1: Select the region to be studied for solar energy resources, and combine the historical measured data of all radiation and meteorological stations within the geographical range to obtain historical data of astronomical parameters of the region to be calculated. The astronomical parameters include radiation period, solar constant, geographical latitude, Earth-Sun distance, solar declination, sunrise and sunset angles, total ground radiation, sunshine duration, half-day sunshine hours, and atmospheric eclipse difference.

[0056] Step S2: Divide the historical data of the astronomical parameters into twenty-four groups according to the solar terms. The solar terms can reflect natural laws such as seasons, phenological phenomena, and climate change. Thinking about and selecting the division criteria from this perspective can improve the accuracy of climatological calculation equations.

[0057] Step S3: Based on the grouping, construct twenty-four equations for calculating total ground radiation.

[0058] Furthermore, the specific process of step S2 is as follows: the historical data of the astronomical parameters are divided into twenty-four groups according to the solar terms of each year. The first group is from the day after the Great Cold of the previous year to the Beginning of Spring of the current year; the second group is from the day after the Beginning of Spring to Rain Water; the third group is from the day after Rain Water to Awakening of Insects; the fourth group is from the day after Awakening of Insects to the Spring Equinox; the fifth group is from the day after the Spring Equinox to Pure Brightness; the sixth group is from the day after Pure Brightness to Grain Rain; the seventh group is from the day after Grain Rain to the Beginning of Summer; the eighth group is from the day after the Beginning of Summer to Grain Buds; the ninth group is from the day after Grain Buds to Grain in Ear; the tenth group is from the day after Grain in Ear to the Summer Solstice; and the tenth group is from the day after the Summer Solstice to Minor Heat. Group 11; Group 12 is from the day after Lesser Heat to Greater Heat; Group 13 is from the day after Greater Heat to the Beginning of Autumn; Group 14 is from the day after the Beginning of Autumn to the End of Heat; Group 15 is from the day after the End of Heat to White Dew; Group 16 is from the day after White Dew to the Autumnal Equinox; Group 17 is from the day after the Autumnal Equinox to Cold Dew; Group 18 is from the day after Cold Dew to Frost's Descent; Group 19 is from the day after Frost's Descent to the Beginning of Winter; Group 20 is from the day after Lesser Snow to Lesser Snow; Group 21 is from the day after Lesser Snow to Greater Snow; Group 22 is from the day after Greater Snow to the Winter Solstice; Group 23 is from the day after the Winter Solstice to Lesser Cold; Group 24 is from the day after Lesser Cold to Greater Cold.

[0059] By analyzing annual solar radiation variations using the 24 solar terms as nodes, the impact of fluctuations in natural meteorological factors is reduced.

[0060] Furthermore, step S3 includes:

[0061] Step S31: Calculate the total solar astronomical radiation and sunshine percentage for each group;

[0062] Step S32: Based on the total solar astronomical radiation and sunshine percentage, combined with the total ground radiation in the astronomical parameters, the least squares method is used to select the sunshine percentage as the independent variable and the clear sky index as the dependent variable. The equation for calculating the total ground radiation is obtained through regression fitting, where the clear sky index = Q / Q0, Q is the total ground radiation, and Q0 is the total solar astronomical radiation.

[0063] Furthermore, step S31 includes:

[0064] Step S311: Based on astronomical parameters, using Lambert's theorem, Earth-Sun distance, and solar declination formula, process the relevant meteorological and radiation data to calculate the total solar astronomical radiation. The calculation formula is as follows:

[0065]

[0066] Where Q0 represents the total solar astronomical radiation, in MJ / (m²). 2 ·d); T is the period (24×60×60s); I0 is the solar constant, taken as 13.67×10 -4[MJ / (m2·s)]; δ is the solar declination, which is positive north of the celestial equator and negative south of it, in radians (rad); ω0 is the sunrise and sunset angle, which is positive west of true solar noon and negative east of it, in radians (rad). The latitude is expressed in radians (rad).

[0067] Step S312: Calculate the sunshine percentage, the formula is as follows:

[0068] S = T0 / T A (2)

[0069] Where S is the percentage of sunshine, T0 is the duration of sunshine, and T A For the duration of the photo.

[0070] Furthermore, in step S32, the equation for calculating the total ground radiation is:

[0071] Q = Q0(a + bS) (3)

[0072] Where Q is the total ground radiation, in MJ / (m²) 2 ·d); a and b are empirical coefficients, obtained by regression fitting using the least squares method.

[0073] Furthermore, in step S311: the square of the relative distance between the Sun and Earth is calculated using equation (4):

[0074]

[0075] Where ρ is the relative distance between the Earth and the Sun, and J is the day sequence within the year.

[0076] Furthermore, in step S311: the solar declination is calculated using equation (5):

[0077]

[0078] Where X is calculated by equation (6):

[0079] X = 2π(J-1) / 365 (6)

[0080] Where J represents the date sequence within the year, 1 represents the start date of the year (January 1st), and 365 represents the end date of the year (December 31st). In leap years, 366 is used.

[0081] Furthermore, in step S311: the sunrise and sunset time angles are calculated using equation (7):

[0082]

[0083] Where δ is the solar declination, which is positive north of the celestial equator and negative south of it, and is in radians (rad). ω0 is the sunrise and sunset angle, which is positive west of true solar noon and negative east of it, and is in radians (rad). The latitude is expressed in radians (rad).

[0084] Furthermore, in step S312, the sunshine duration is read from the acquired astronomical parameters, and the sunshine duration is calculated using equation (8):

[0085] T A =2×T B (8)

[0086] Among them, T B The number of hours of sunshine per half-day is calculated using formula (9):

[0087]

[0088] Where γ is the atmospheric difference; φ is the local latitude; and δ is the solar declination.

[0089] Furthermore, the method for calculating near-ground received radiation also includes:

[0090] Step S4: Obtain real-time data of astronomical parameters for the area to be calculated and predict the total ground radiation.

[0091] Example 2

[0092] The difference from Example 1 is that in this example, the equation for calculating the total ground radiation is compared with the traditional formula for each month, and the error of the fitting result is analyzed.

[0093] The relative deviation and average relative deviation between the climatologically calculated value Q of total solar radiation at ground level and the measured value Q' of total solar radiation can be expressed as:

[0094] ε ri =(Q-Q') / Q×100% (10)

[0095]

[0096] In the formula: n is the number of data points; i is the i-th data point.

[0097] By using historical radiation data and meteorological data from different regions, a climatological equation for total surface radiation is fitted. The deviation between the fitted radiation result and the measured value is calculated to verify the applicability and accuracy of the empirical climatological formula, thereby calculating the abundance of solar energy resources in the region.

[0098] To verify the accuracy of this method, basic data from a certain region in western China (84°75′E, 45°5′N) were selected as a case study for specific calculations and analysis.

[0099] Based on the measured values ​​of total ground radiation and sunshine percentage for each month of each year in this region, and using historical data from 2002 to 2021 as a basis, the formula for calculating total solar radiation is derived.

[0100] After statistical analysis and programming processing, the linear fitting results of the clear sky index (clear sky index = Q / Q0) for the 24 solar terms of the year with respect to the sunshine percentage S are shown in Table 1. For comparison, the formula for calculating the clear sky index (clear sky index = Q / Q0) for December with respect to the sunshine percentage S is shown in Table 2.

[0101] Taking 2022 as an example, the relative deviation between the values ​​calculated by the two methods and the actual values ​​measured by the meteorological stations was calculated.

[0102] Overall, throughout the year, the average relative deviation between the predicted values ​​of the 24 solar terms and the actual values ​​measured by the meteorological station was 1.91%, while the monthly deviation was 2.60%. In comparison, the deviation value of the new method is significantly reduced.

[0103] Table 1. Coefficients in the climatological calculation formulas for the Twenty-Four Solar Terms

[0104]

[0105]

[0106] Table 2. Coefficients in the monthly climatological calculation formulas

[0107]

[0108] Based on the above analysis and comparison, we can conclude that by fully considering the influence of seasonal changes, the empirical formula calculated can more accurately describe the linear regression relationship between total solar radiation and sunshine percentage, thereby assessing the abundance of solar energy resources in a region and providing reliable data support for the rational development and utilization of solar energy in the future.

[0109] Compared with the traditional formula based on months, the climatological calculation formulas for the 24 solar terms have refined the time range, accurately fitted the linear regression relationship between total solar radiation and sunshine percentage, and significantly reduced the deviation between the measured values ​​of meteorological stations and the calculation results of the formulas.

[0110] Therefore, this invention adopts the above-mentioned method, considers the laws of natural meteorological changes, combines the data of the twenty-four solar terms, clarifies the range of each parameter in the climatological calculation formula, calculates the empirical formulas respectively, calculates the regional near-surface received radiation, and then estimates the annual total solar radiation, which can improve the accuracy of the calculation. This invention optimizes the traditional method, significantly reduces the fluctuation of the original data, and reduces the deviation of the calculation results.

[0111] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A method for calculating near-ground received radiation, characterized in that, The method comprises the following steps: Step S1: obtaining historical data of astronomical parameters of a region to be calculated, the astronomical parameters comprising a radiation period, a solar constant, a geographical latitude, a distance between the sun and the earth, a solar declination, a sunrise and sunset hour angle, a total ground radiation, a sunshine duration, a half-day sunshine duration, and an air mass difference; Step S2: dividing the historical data of the astronomical parameters into twenty-four groups according to solstices; Step S3: respectively constructing twenty-four total ground radiation calculation equations based on the grouping.

2. The near surface received radiation calculation method of claim 1, wherein: The specific process of the step S2 is that the historical data of the astronomical parameters is divided into twenty-four groups according to solstice days of years, the day after the Great Cold of the previous year to the Beginning of Spring of the current year is the first group; the day after the Beginning of Spring to the Rain Water is the second group; the day after the Rain Water to the Waking of Insects is the third group; the day after the Waking of Insects to the Summer Solstice is the fourth group; the day after the Summer Solstice to the Clear and Bright is the fifth group; the day after the Clear and Bright to the Grain Rain is the sixth group; the day after the Grain Rain to the Beginning of Summer is the seventh group; the day after the Beginning of Summer to the First Fruiting is the eighth group; the day after the First Fruiting to the Grain in Ear is the ninth group; the day after the Grain in Ear to the Summer Solstice is the tenth group; the day after the Summer Solstice to the Small Heat is the eleventh group; the day after the Small Heat to the Great Heat is the twelfth group; the day after the Great Heat to the Beginning of Autumn is the thirteenth group; the day after the Beginning of Autumn to the End of Heat is the fourteenth group; the day after the End of Heat to the White Dew is the fifteenth group; the day after the White Dew to the Autumnal Equinox is the sixteenth group; the day after the Autumnal Equinox to the Cold Dew is the seventeenth group; the day after the Cold Dew to the First Frost is the eighteenth group; the day after the First Frost to the Beginning of Winter is the nineteenth group; the day after the Beginning of Winter to the Small Snow is the twentieth group; the day after the Small Snow to the Large Snow is the twenty-first group; the day after the Large Snow to the Winter Solstice is the twenty-second group; the day after the Winter Solstice to the Small Cold is the twenty-third group; and the day after the Small Cold to the Great Cold is the twenty-fourth group.

3. The near surface received radiation calculation method of claim 1, wherein: The step S3 comprises: Step S31: calculating a total amount of solar astronomical radiation and a sunshine percentage of each group; Step S32: obtaining a total ground radiation calculation equation by regression fitting through the least square method, according to the total amount of solar astronomical radiation and the sunshine percentage, and in combination with the total ground radiation in the astronomical parameters.

4. The method of calculating the amount of radiation received at the surface of the earth as claimed in claim 3, wherein: The step S31 comprises: Step S311: calculating the total amount of solar astronomical radiation, and the calculation formula is: Where Q0 is the total solar astronomical radiation, in MJ / (m²) 2 ·d); T is the period (24×60×60s); I0 is the solar constant, taken as 13.67×10 -4 [MJ / (m2·s)]; δ is the solar declination, which is positive north of the celestial equator and negative south of it, in radians (rad); ω0 is the sunrise and sunset angle, which is positive west of true solar noon and negative east of it, in radians (rad). The latitude is expressed in radians (rad). Step S312: calculating the sunshine percentage, and the calculation formula is: S = To / T A (2) Wherein S is the percentage of sunshine, T0 is the sunshine duration, T A is the available sunshine duration.

5. The method of calculating the amount of radiation received at the surface of the earth as recited in claim 3, wherein: In the step S32, the total ground radiation calculation equation is: Q=Q0(a+bS) (3) where Q is the total ground radiation in MJ / (m 2 d); a, b are empirical coefficients obtained by regression fitting with the least squares method.

6. The method of calculating the amount of radiation received at the surface of the earth as recited in claim 4, wherein: In the step S311: the square of the relative distance between the sun and the earth is calculated through formula (4): wherein, ρ is the relative distance between the sun and the earth, and J is a day sequence in a year.

7. The near surface received radiation calculation method of claim 4, wherein: In the step S311: the solar declination is calculated through formula (5): wherein, X is calculated through formula (6): X=2π(J-1) / 365 (6) wherein, J is a day sequence in a year.

8. The method of calculating the amount of radiation received at the surface of the earth as recited in claim 4, wherein: In the step S311: the sunrise and sunset hour angle is calculated through formula (7): Wherein, δ is the solar declination, positive in the north of the celestial equator and negative in the south, unit is radian (rad); ω0 is the sunrise and sunset hour angle, positive from the true solar time noon to the west and negative to the east, unit is radian (rad); is the geographic latitude, unit is radian (rad).

9. The method of calculating the amount of radiation received at the surface of the earth as recited in claim 4, wherein: In the step S312: the sunshine duration is read from the obtained astronomical parameters, and the sunshine duration is calculated through formula (8): T A = 2 x T B (8) where T B is the number of hours of daylight, calculated by equation (9): wherein, γ is the air mass difference; φ is the local latitude; and δ is the solar declination.

10. The method of calculating the amount of radiation received at the surface of the earth as recited in claim 1, wherein: The method for calculating the near-ground surface received radiation further comprises: Step S4: obtaining real-time data of astronomical parameters of a region to be calculated, and predicting the total ground radiation.

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