CN103226654B - A kind of solar energy thermal-power-generating heliostat field analogy method - Google Patents

Abstract

The invention discloses a kind of solar energy thermal-power-generating heliostat field analogy method, comprise following implementation step: the sunshine incident direction 1) calculating current location according to time and geography information; 2) on the sun, produce random point, calculate the actual incident direction at this random point place according to described sunshine incident direction; 3) according to described actual incident direction, sun shape is utilized to calculate outgoing emittance to each random point; 4) calculate described emergent radiation energy according to meteorology radiation patterns and enter the actual emanations energy behind ground through air; 5) direction of each bar reflection ray of monte carlo method sampling heliostat is used; 6) according to the direction of described actual emanations energy, reflection ray, micro-plane reflection model is utilized to calculate the light ray energy of every bar reflection ray; 7) according to the light ray energy of every bar reflection ray, calculate energy attenuation according to the path between heliostat to receiver, obtain final energy.

Description

A kind of solar energy thermal-power-generating heliostat field analogy method

Technical field

The present invention relates to computer graphics drafting, meteorology and geometrical optics field, particularly relate to a kind of solar energy thermal-power-generating heliostat field analogy method.

Background technology

Energy and environment problem is two outstanding problems of restriction world economy and social sustainable development.In China, oneself storage of the energy such as oil, rock gas, coal etc. of exploitation is all very limited, per capita energy's yield far below world average level, lack of energy and environment go from bad to worse become we must faced by reality.Sun power have reserves unlimited, exist general, utilize advantage that is clean, exploiting economy; effectively utilize sun power; the discharge capacity of the harmful gas such as the energy problem of China, the carbon dioxide of minimizing can not only be alleviated, and the energy of preserving the ecological environment, guaranteeing in process of economic development is supplied etc. continually and steadily all will have important and far-reaching meaning.

China also starts pilot study in solar energy thermal-power-generating technology etc., builds up domestic seat of honour tower type solar energy thermal power generation demonstration project, and successfully generate electricity by way of merging two or more grid systems in October, 2005 in Jiangning, Nanjing economic and technological development zone.The Ministry of Science and Technology and the Chinese Academy of Sciences and Municipal Commission of Science and Technology support the research studying the hot generation technology of large solar jointly.The Eleventh Five-Year Plan period will set up 1MW solar energy tower type thermal generation Demonstration Station in Beijing, and set up China's solar energy thermal-power-generating Experimental Base with this, current CAS Electrical Engineering Research Institute completes general layout design, Demonstration Station has started to go into operation construction at Yanqing County of Beijing, and in August, 2012, experiment generates electricity successfully.Along with research and the manufacture of power house, also extremely urgent to the demand of the simulation and analysis of solar electrical energy generation Jing Chang.

More early stage calculating simulation software such as HFLCAL, HELIOS, MIRVAL, DELSOL etc., they are by early stage numerical evaluation Software Evolution, and common feature calculates simply, is in the junior stage to the simulation of mirror field optics, precision is not high, and operational efficiency is lower, and user interface interaction is poor.Nearly ten years, no matter simulation system is obtained for and greatly develops in theory or in practice, the Enertracer of people's exploitations such as Blanco, Alarcon in 2000; 2003, the SolTrace that American National new forms of energy laboratory (NationalRenewableEnergyLaboratory) is developed; 2009, the DLR that German Aerospace Center (GermanAerospaceCenter) develops.They are all integrated with new optical theory, have adapted to the hardware structure of next generation computer, have done special processing and optimization to optical frames field.

Computer hardware fast development in recent years, GPU accelerates the speed of traditional calculations greatly as the core of parallel computation of new generation, along with continuous expansion and the upgrading evolution of solar energy thermal-power-generating mirror field scale, cause the simulated data information of magnanimity, and require more efficient and accurate result of calculation.Because existing simulation system does not effectively utilize GPU of new generation to accelerate, the computing time for large-scale Jing Chang is very long; And use simple Ray Tracing Algorithm thought, do not consider the impact of global illumination, accuracy and the result of implementation of calculating greatly differ from each other, and cause in simulation and there is very large error, and they are more and more difficult to the analog operation of competent New Times heat generating system.

Summary of the invention

For overcoming deficiency of the prior art, the invention provides a kind of solar energy heliostat field stimulation method that can process large-scale data and real time modelling and calculate.

A kind of solar energy thermal-power-generating heliostat field analogy method, comprises following implementation step:

1) the sunshine incident direction of current location is calculated according to time and geography information;

2) on the sun, produce random point, calculate the actual incident direction at this random point place according to described sunshine incident direction;

3) according to described actual incident direction, sun shape is utilized to calculate outgoing emittance to each random point;

4) calculate described emergent radiation energy according to meteorology radiation patterns and enter the actual emanations energy behind ground through air;

5) direction of each bar reflection ray of monte carlo method sampling heliostat is used;

6) according to the direction of described actual emanations energy, reflection ray, micro-plane reflection model is utilized to calculate the light ray energy of every bar reflection ray;

7) according to the light ray energy of every bar reflection ray, calculate energy attenuation according to the path between heliostat to receiver, obtain final energy.

In described step 2) in, the sun uses the random point described in monte carlo method generation.

Monte carlo method (MonteCarlomethod), also statistical simulation methods is claimed, the development of middle 1940s due to science and technology and the invention of robot calculator, and be suggested a kind of with Probability Statistics Theory be instruct the very important numerical computation method of a class, refer to the method using random number (or more common pseudo random number) to solve a lot of computational problem, such as: the people such as Jaroslav disclose a kind of this area application monte carlo method ( jaroslav.GlobalilluminationwithMonteCarloraytracing [C] //InACMSIGGRAPH2008.NewYork:ACMPress, 2008 (61): 1-25.).

The function expression of described sun shape is:

$\mathrm{\&phi;}\left(\mathrm{\&theta;}\right)=\{\begin{array}{cc}\frac{\cos \left(0.326\mathrm{\&theta;}\right)}{\cos \left(0.308\mathrm{\&theta;}\right)}& \mathrm{for}\{\mathrm{\&theta;}\&Element;R|0<\mathrm{\&theta;}<4.65\}\\ e^k{\mathrm{\&theta;}}^r& \mathrm{for}\{\mathrm{\&theta;}\&Element;R|4.65<\mathrm{\&theta;}<44\}\end{array}$

Wherein: γ=2.2ln (0.52x) x ^0.43-0.1

k=0.9ln(13.5x)x ^-0.3

In formula, φ (θ) represents emittance ratio, and x representative ring day area ratio, θ represents the angle of actual incident direction and sunshine incident direction.

Before step 7), judge, if meet following condition arbitrarily, then abandon the calculating of current reflective light:

A) current reflective light and receiver do not have intersection point;

B) current reflective light is obstructed;

C) corresponding with current reflective light incident ray is obstructed.

Micro-plane reflection model in described step 6) is Blinn model, and its specular reflectance is:

$R_s=\frac{\mathrm{FDG}}{\mathrm{\&pi;}(N\&CenterDot;V)(N\&CenterDot;L)}$

Wherein, wherein N is surperficial mean unit normal vector, and V is unit sight line vector, and L is incident ray vector of unit length, and F is Fresnel item, and D is micro-plane distribution function from the teeth outwards, and G is the decay factor because a micro-plane is formed another micro-blocking of plane.

When using monte carlo method to sample in described step 5), according to sunshine incident ray direction, use monte carlo method to launch many reflection rays, its directional spreding determines according to micro-plane reflection model.

The present invention has following advantage:

1, the present invention is by utilizing Monte Carlo ray trace, uses micro-plane reflection model, can the process of more accurate compute ray transmitting energy;

2, the present invention can adapt to new extensive heliostat field, is convenient to process magnanimity minute surface microfarad to data.

Accompanying drawing explanation

Fig. 1 is the schematic flow sheet of solar energy thermal-power-generating heliostat field analogy method of the present invention.

Fig. 2 is that the incident ray of the embodiment of the present invention produces schematic diagram;

Fig. 3 is that the reflection ray of the embodiment of the present invention calculates schematic diagram.

Embodiment

The present invention is based on CPU and the GPU in computing machine, realize solar energy thermal-power-generating heliostat field analogy method, the starting point of the sunray that the present invention the produces video camera (viewpoint) that to be the sun be not in reverse ray trace, according to information such as sun shape (SunShape) and ring days region (Circumsolar), simulation produces the sunray with energy; The process produced is subject to the impact of the factor such as weather, geographical environment.

As shown in Figure 1, solar energy thermal-power-generating heliostat field analogy method, comprises following implementation step:

1) the sunshine incident direction of current location is calculated according to time and geography information;

2) on the sun, monte carlo method produces random point, calculates the actual incident direction at this random point place according to sunshine incident direction;

As shown in Figure 2, in figure, a represents the sun, and b represents the random point (quantity of random point is set by the user) produced on the sun, true origin is that d represents heliostat field, c represents the incident direction of sunshine, and e represents actual incident direction, and the light distributed in conical area can be by represent, wherein, ε ₃with ε ₄for interval [0,1] upper equally distributed random number, represent the position angle in conical coordinates system, θ _srepresent the cone angle in conical coordinates system, its value is 4.65mrad.

Conical coordinates system is transformed into xyz coordinate system as follows:

In formula, represent the position angle in conical coordinates system, θ represents the cone angle in conical coordinates system.

3) according to actual incident direction, sun shape is utilized to calculate outgoing emittance to each random point;

The function expression of sun shape is:

$\mathrm{\&phi;}\left(\mathrm{\&theta;}\right)=\{\begin{array}{cc}\frac{\cos \left(0.326\mathrm{\&theta;}\right)}{\cos \left(0.308\mathrm{\&theta;}\right)}& \mathrm{for}\{\mathrm{\&theta;}\&Element;R|0<\mathrm{\&theta;}<4.65\}\\ e^k{\mathrm{\&theta;}}^r& \mathrm{for}\{\mathrm{\&theta;}\&Element;R|4.65<\mathrm{\&theta;}<44\}\end{array}$

Wherein: γ=2.2ln (0.52x) x ^0.43-0.1

k=0.9ln(13.5x)x ^-0.3

In formula, φ (θ) represents emittance ratio, and x representative ring day area ratio (each area obtains according to actual measurement on the same day), θ represents the angle of actual incident direction and sunshine incident direction.

4) calculate outgoing emittance according to meteorology radiation patterns and enter the actual emanations energy behind ground through air;

The portion of energy that the compute ray that is used for meteorology radiation patterns reduces in an atmosphere, under fine environment, by the sunshine beam energy injecting earth surface in universe is:

G _b=G _exτ _ατ _rτ _oτ _wτ _mix

Wherein, G _exfor the vertical unit area emittance of the outer space, provide G by Muneer _ex=1367W/m ².τ _α, τ _r, τ _o, τ _wand τ _mixmie scattering, Rayleigh scattering, ozone absorption rate, water vapor absorption rate and mixed gas absorptivity (such as carbon dioxide, oxygen etc.) respectively.These parameters are relevant with air themperature (DEG C), relative humidity (%) and air pressure (hPa).

5) direction of each bar reflection ray of monte carlo method sampling heliostat is used;

Micro-plane reflection model is Blinn model, and wherein Gaussian distribution is followed in mirror-reflection direction, as shown in Figure 3.Box-Muller method is used to simulate the random number r meeting Gaussian distribution in actual enforcement ₀, r ₁:

$r_0=\sqrt{-2\ln U_1}\cos \left(2\mathrm{\&pi;}{U}_2\right)=\sqrt{-2\ln s}\left(\frac{u}{\sqrt{s}}\right)=u\sqrt{\frac{-2\ln s}{s}}$

$r_1=\sqrt{-2\ln U_1}\sin \left(2\mathrm{\&pi;}{U}_2\right)=\sqrt{-2\ln s}\left(\frac{v}{\sqrt{s}}\right)=v\sqrt{\frac{-2\ln s}{s}}$

U ₁and U ₂represent [0,1] interval interior equally distributed random number, wherein u, v are respectively [-1,1] interval interior equally distributed random number, s ²=u ²+ v ².

6) according to the direction of described actual emanations energy, reflection ray, micro-plane reflection model is utilized to calculate the light ray energy of every bar reflection ray;

Suppose that incident light energy is E _i, emergent light energy is E _i* R _s.Wherein R _sfor Blinn microplane model specular reflectance:

$R_s=\frac{\mathrm{FDG}}{\mathrm{\&pi;}(N\&CenterDot;V)(N\&CenterDot;L)}$

Wherein, N is surperficial mean unit normal vector, and V is unit sight line vector, and L is incident ray vector of unit length, and F is Fresnel item, and D is micro-plane distribution function from the teeth outwards, and G is the decay factor because a micro-plane is formed another micro-blocking of plane.Suppose that the unit normal vector of each micro-plane is that the distribution function of gauss of distribution function as this plane slightly got by H, Blinn model:

$D=\mathrm{k\; exp}[-{\left(\frac{\mathrm{\&alpha;}}{m}\right)}^2]$

Wherein, k is a constant, and α is the angle between the normal vector H of micro-plane and the macroscopic method vector N on surface, and namely α=arccos (NH), m are micro-plane slope mean square deviation.When m value is less, show that surface is more smooth; When m value is larger, show that surface is more coarse.

The geometric attenuation factor of reflectance lightness is:

$G_m=\frac{2(N\&CenterDot;H)(N\&CenterDot;V)}{(H\&CenterDot;L)}$

$G_s=\frac{2(N\&CenterDot;H)(N\&CenterDot;L)}{(H\&CenterDot;V)}$

G=min(1,G _m,G _s)

In formula, N is surperficial mean unit normal vector, and V is unit sight line vector, and L is incident ray vector of unit length, and H is the unit normal vector of each micro-plane.

Fresnel item can be released according to Fresnel equation and simplify further:

$F=\frac{{(g-c)}^2}{2{(g+c)}^2}\{1+\frac{{[c{(g+c)}^2-1]}^2}{{[c{(g-c)}^2+1]}^2}\}$

Wherein c=LH, g ²=η ²+ c ²-1, η is relative index of refraction.

7) according to the light ray energy of every bar reflection ray, calculate energy attenuation according to the path between heliostat to receiver, obtain final energy.

Energy attenuation calculates according to the energy attenuation factor, and the wherein energy attenuation factor is:

${\mathrm{\&eta;}}_{\mathrm{atmosphere}}=\{\begin{array}{c}0.99321-0.0001176d_i+1.97*{10}^{-8}{d_i}^2,d_i\&le;1000m\\ \exp (-0.0001106d_i),d_i>1000m\end{array}$

Wherein, d _iit is the distance that light advances.

Claims (3)

1. a solar energy thermal-power-generating heliostat field analogy method, is characterized in that, comprises following implementation step:

1) the sunshine incident direction of current location is calculated according to time and geography information;

2) on the sun, use monte carlo method to produce random point, calculate the actual incident direction at this random point place according to described sunshine incident direction;

3) according to described actual incident direction, sun shape is utilized to calculate outgoing emittance to each random point;

4) calculate described emergent radiation energy according to meteorology radiation patterns and enter the actual emanations energy behind ground through air;

5) direction of each bar reflection ray of monte carlo method sampling heliostat is used;

Be specially: according to sunshine incident ray direction, use monte carlo method to launch many reflection rays, reflection direction distribution determines according to micro-plane reflection model, and follows Gaussian distribution, and uses Box-Muller method to simulate the random number r meeting Gaussian distribution ₀, r ₁:

$r_0=\sqrt{-2{\mathrm{lnU}}_1}cos\left(2{\mathrm{\&pi;U}}_2\right)=\sqrt{-2\ln s}\left(\frac{u}{\sqrt{s}}\right)=u\sqrt{\frac{-2\ln s}{s}}$

$r_1=\sqrt{-2{\mathrm{lnU}}_1}sin\left(2{\mathrm{\&pi;U}}_2\right)=\sqrt{-2\ln s}\left(\frac{v}{\sqrt{s}}\right)=v\sqrt{\frac{-2\ln s}{s}}$

U ₁and U ₂represent [0,1] interval interior equally distributed random number, wherein u, v are respectively [-1,1] interval interior equally distributed random number, s ²=u ²+ v ²;

6) according to the direction of described actual emanations energy, reflection ray, micro-plane reflection model is utilized to calculate the light ray energy of every bar reflection ray;

Suppose that incident light energy is E _i, energy of reflection light is E _i× R _s, wherein R _sfor Blinn microplane model specular reflectance:

$R_s=\frac{FDG}{\mathrm{\&pi;}(N\&CenterDot;V)(N\&CenterDot;L)}$

Wherein, N is surperficial mean unit normal vector, and V is unit sight line vector, and L is incident ray vector of unit length, and F is Fresnel item, and D is micro-plane distribution function from the teeth outwards, and G is the decay factor because a micro-plane is formed another micro-blocking of plane;

7) according to the light ray energy of every bar reflection ray, calculate energy attenuation according to the path between heliostat to receiver, obtain final energy.

2. solar energy thermal-power-generating heliostat field analogy method as claimed in claim 1, is characterized in that, in step 7) before, judge, if meet following condition arbitrarily, then abandon the calculating of current reflective light:

A) current reflective light and receiver do not have intersection point;

B) current reflective light is obstructed;

C) corresponding with current reflective light incident ray is obstructed.

3. solar energy thermal-power-generating heliostat field analogy method as claimed in claim 2, it is characterized in that, the function expression of described sun shape is:

$\mathrm{\&phi;}\left(\mathrm{\&theta;}\right)=\left\{\begin{array}{cc}\frac{\cos \left(0.326\mathrm{\&theta;}\right)}{\cos \left(0.308\mathrm{\&theta;}\right)}& for\{\mathrm{\&theta;}\&Element;R|0<\mathrm{\&theta;}<4.65\}\\ e^k{\mathrm{\&theta;}}^{\mathrm{\&gamma;}}& for\{\mathrm{\&theta;}\&Element;R|4.65<\mathrm{\&theta;}<44\}\end{array}\right.$

Wherein: γ=2.2ln (0.52x) x ^0.43-0.1

k＝0.9ln(13.5x)x ^-0.3

In formula, φ (θ) represents emittance ratio, x representative ring day area ratio, and θ represents the angle of actual incident direction and sunshine incident direction, and R is the set of all real numbers.