CN102768545A - Method for determining optimum tracking angles of photovoltaic tracking systems under standard equatorial coordinate system - Google Patents

Abstract

The invention provides a method suitable for determining optimum tracking angles of photovoltaic tracking systems of various structures. The method solves the optimum tracking angles of single or double axis photovoltaic tracking systems of inclination axes in a vector method. By means of the method, the optimum tracking angles of gradients of the installation ground or gradients caused by installation errors of the single or double axis photovoltaic tracking systems can be rectified, and the optimum tracking angles of inclination toward the due south of installation direction of the single or double axis photovoltaic tracking system caused by limitation of the surrounding environment or installation errors can be rectified. The method has the advantages of being capable of automatically rectifying tracking errors caused by ground gradient, system direction, construction inaccuracy and the like and enabling the tracking system to be high in efficiency and stability and low in cost.

Description

Definite method of photovoltaic tracking system optimal tracking angle under the accurate equatorial coordinate system

Technical field

The present invention relates to a kind of best solar tracking angle and confirm method, be particularly useful for that photovoltaic tracking system changes and its optimal tracking angle of dynamic calculation with solar azimuth under the accurate equatorial coordinate system.

Background technology

Human society gets into 21 century, and the energy resource consumption that global economic growth causes has reached unprecedented degree.Conventional fossil energy is not only had too many difficulties to cope with satisfying on the human social development, and has brought bigger threat because of fossil fuel consumes the global warming and the deterioration of the ecological environment that cause excessively to the mankind.In order to tackle the fossil energy serious problems of shortage gradually; Must progressively adapt energy consumption structure; Develop energetically with sun power is the regenerative resource of representative; Walk the road of sustainable development in the energy supply field, only in this way could guarantee the lasting progress of politics, prosperity of economy development and civilization of human society.

Along with the appearance successively of various countries' subsidy policy, photovoltaic generation has got into the unprecedented fast-developing phase.But how improving photovoltaic efficiency, reducing cost of electricity-generating still is a long-range problem.Photovoltaic tracking system is the effective means that addresses this problem; But the photovoltaic tracking system ubiquity track algorithm of present stage is too simple, out of true, non-science; Or sensor receives such environmental effects such as dust, sunshine; It is low to cause following the tracks of efficient, makes system's long-term work under up-set condition, thereby has increased design, installation, the maintenance cost of system.Therefore, efficiently, reasonably track algorithm has important effect to raising tracker stability, raising system effectiveness, reduction system cost.

Summary of the invention

The objective of the invention is the deficiency to prior art, a kind of definite method that is applicable to photovoltaic tracking system optimal tracking angle under the accurate equatorial coordinate system is provided, adopted a kind of efficient, rational track algorithm.

According to technical scheme provided by the invention; Definite method of photovoltaic tracking system optimal tracking angle is under the said accurate equatorial coordinate system: under accurate equatorial coordinate system; To what on surface level, install, towards the optimal tracking angle η of the bi-axial tilt axle tracing system in due south _s=η, v _s=v; Wherein the v angle is that sunray and this light are at y ₀o ₀z ₀Angle between the projection on plane, place, angle η is this projection and z ₀The angle of axle;

To what on surface level, install, the β angle single-axis tilt axle tracing system that inclines towards the due south has:

$v_s={\mathrm{tam}}^{-1}\left(\frac{\tan \left(v\right)}{\cos (\mathrm{\η}-\mathrm{\β})}\right)---\left(7\right)$

Have azimuth angle deviation Δ γ if system installs, Δ γ is by east for negative, and is to the west for just; Or the gradient that the face of land is installed is Δ β, and Δ β is exposed to the north to negative on the Northern Hemisphere towards Nan Weizheng, and the Southern Hemisphere is opposite; Then system's optimal tracking angle is suc as formula (9) and formula (10);

If system exists Δ γ or Δ β, then

$v_s={\tan }^{-1}\left(\frac{A-B}{C+D+E}\right)---\left(9\right)$

η _s=β=η-Δβ （10）

To the bi-axial tilt axle tracing system, in the formula (9):

A=sin(ν)·cos(Δγ)

B=cos(ν)·cos(Δγ)·sin(η)

C=sin(ν)·sin(Δγ)·sin(η)

D=cos(ν)·cos(Δγ)·sin ²(η)

E=cos(ν)·cos(Δγ)·cos(η)

To the single-axis tilt axle tracing system, in the formula (9):

A=sin(ν)·cos(Δγ)

B=cos(ν)·cos(Δγ)·sin(η)

C=sin(ν)·sin(Δγ)·sin(β+Δβ)

D=cos(ν)·cos(Δγ)·sin(η)·sin(β+Δβ)

E=cos(ν)·cos(Δγ)·cos(β+Δβ)。

Advantage of the present invention is: can realize high-level efficiency, high stable, the low cost of tracker from NMO correction ground inclination, system towards the error that, construction out of true etc. causes.

Description of drawings

Fig. 1 is a sloping shaft photovoltaic tracking system synoptic diagram.

Fig. 2 is sun related angle figure.

Fig. 3 is an accurate equatorial coordinate system.

Fig. 4 is sunray and System planes normal vector synoptic diagram.

Fig. 5 is the contrast of 36.72 ° of N/101.75 ° of E area revised tracking angles of horizontal tracker and angle ν: wherein Fig. 5 (a) is day in the Spring Equinox, and Fig. 5 (b) is the summer solstice, and Fig. 5 (c) is day in the Autumnal Equinox, and Fig. 5 (d) is the winter solstice.

Embodiment

The present invention relates under accurate equatorial coordinate system, the vector method of the optimal tracking angle of the single, double axle of sloping shaft photovoltaic tracking system is found the solution.

Fig. 1 is the synoptic diagram of sloping shaft photovoltaic tracking, and the sloping shaft photovoltaic tracking system should comprise usually: solar panel, photovoltaic tracking support, photovoltaic tracking controller, motor, reduction gear, gearing etc.Photovoltaic tracking system is through specific algorithm controls motor, and motor rotates around turning axle through the support that reduction gear, actuator drives are equipped with solar panel.The angle of turning axle and surface level is defined as β, the angle of turning axle rotation, and promptly the tracking angle of photovoltaic tracking system is defined as ν _s

The present invention carries out the calculating under the accurate equatorial coordinate to the optimal tracking angle to sloping shaft photovoltaic tracking system shown in Figure 1 on the basis of the PSA of position of sun algorithm.

As shown in Figure 2, the statement of position of sun has dual mode.

(1) equatorial system of coordinates: (x, y, z).In the coordinate system, (ω confirms that δ) wherein δ is the angle of sunray and earth equatorial plane, and promptly declination is relevant with revolution of earth, and ω is the hour angle of the relative sun of earth rotation, and is relevant with earth rotation by coordinate in the position of the sun under the line.

(2) horizontal system of coordinates: (x ₀, y ₀, z ₀).In the horizontal system of coordinates, (γ confirms that α) wherein γ is the position angle, is the sun angle of deviation in due south, plane relatively by coordinate in the position of the sun; α is an elevation angle, is the angle between the sun and the ground level.θ among Fig. 2 _zBe zenith angle, zenith angle and elevation angle be complementary angle each other,

Be angle of latitude, L is a longitude angle.

The another kind of form of presentation of the horizontal system of coordinates is as shown in Figure 3, the equatorial system of coordinates that promptly is as the criterion system.In accurate equatorial coordinate system, position of sun is by (ν η) uniquely confirms.Wherein the ν angle is that sunray and this light are at y ₀o ₀z ₀Angle between the projection on plane, place, angle η is this projection and z ₀The angle of axle.ν; η is by solar hour angle ω; Declination δ, and latitude and longitude L confirm.

The PSA algorithm is input with the Julian date, has the correction of different year.At first, obtain the expression formula of accurate equatorial coordinate, suc as formula (1) and formula (2) through sunny hour angle ω and the declination δ of PSA algorithm computation.

ν=arcsin(cosδ*sinω) （1）

Position of sun and system towards vector representation.

Like Fig. 2 and shown in Figure 3, the accurate equatorial coordinate (x of system ₀, y ₀, z ₀) in, position availability vector formula (3) expression of the sun:

$\stackrel{\→}{V_P}=\begin{array}{}\end{array}\left[\begin{array}{c}-\sin \left(v\right)\\ -\cos \left(\mathrm{\υ}\right)\·\sin \left(\mathrm{\η}\right)\\ \cos \left(\mathrm{\υ}\right)\·\cos \left(\mathrm{\η}\right)\end{array}\right]---\left(3\right)$

In accurate equatorial coordinate system, the normal vector of System planes is shown in vector mode (4):

$\stackrel{\→}{V_{\mathrm{PS}}}=\begin{array}{}\end{array}\left[\begin{array}{c}-\sin \left(v_s\right)\\ -\cos \left({\mathrm{\υ}}_s\right)\·\sin \left({\mathrm{\η}}_s\right)\\ \cos \left({\mathrm{\υ}}_s\right)\·\cos \left({\mathrm{\η}}_s\right)\end{array}\right]---\left(4\right)$

In formula (4), angle subscript " s " expression system under each coordinate system and the corresponding angle of the sun.

2. the optimal tracking angle under the accurate equatorial coordinate system is found the solution.

As shown in Figure 4, the angle between sunray and the System planes normal line vector is θ, desires to make System planes to receive irradiation as much as possible, according to lambert's cosine law, should make angle theta as much as possible little, promptly should make the cosine value of angle theta big as much as possible.

Aligning equatorial coordinate system (x0, y0 z0) have:

$\frac{\∂\cos \left(\mathrm{\θ}\right)}{{\∂\mathrm{\η}}_s}=\frac{\∂(\stackrel{\→}{V_P}\·\stackrel{\→}{V_{\mathrm{PS}}})}{{\∂\mathrm{\η}}_s}=0---\left(5\right)$

$\frac{\∂\cos \left(\mathrm{\θ}\right)}{{\∂v}_s}=\frac{\∂(\stackrel{\→}{V_P}\·\stackrel{\→}{V_{\mathrm{PS}}})}{{\∂v}_s}=0---\left(6\right)$

Separate formula (5), formula (6), can obtain the optimal tracking angle η of the bi-axial tilt axle tracing system under the accurate equatorial system of coordinates _s=η, ν _s=ν.The β angle single-axis tilt axle tracing system that inclines is had:

$v_s={\tan }^{-1}\left(\frac{\tan \left(v\right)}{\cos (\mathrm{\η}-\mathrm{\β})}\right)---\left(7\right)$

Have azimuth angle deviation Δ γ if system installs, Δ γ is by east for negative, and is to the west for just, or the gradient that the face of land is installed is Δ β, and Δ β is exposed to the north to bearing on the Northern Hemisphere towards Nan Weizheng, and the Southern Hemisphere is opposite.Then the normal direction vector of unit length of System planes is suc as formula shown in (8).The optimal tracking angle is suc as formula (9) and (10).

If system exists Δ γ or Δ β, then this moment, the System planes normal vector was:

$\stackrel{\→}{V_{\mathrm{PS}}}=\left[\begin{array}{c}-\sin \left(v_s\right)\·\cos \left(\mathrm{\Δ\γ}\right)-\cos \left(v_s\right)\·\sin (\mathrm{\Δ\β}+{\mathrm{\η}}_s)\·\sin \left(\mathrm{\Δ\γ}\right)\\ -\sin \left(v_s\right)\·\sin \left(\mathrm{\Δ\γ}\right)-\cos \left({\mathrm{\υ}}_s\right)\·\sin (\mathrm{\Δ\β}+{\mathrm{\η}}_s)\·\cos \left(\mathrm{\Δ\γ}\right)\\ \cos \left({\mathrm{\υ}}_s\right)\·\cos (\mathrm{\Δ\β}+{\mathrm{\η}}_s)\end{array}\right]---\left(8\right)$

Separate formula (5), formula (6), can obtain:

$v_s={\tan }^{-1}\left(\frac{A-B}{C+D+E}\right)---\left(9\right)$

η _s=β=η-Δβ （10）

In double-axis tracking system formula (9):

A=sin(ν)·cos(Δγ)

B=cos(ν)·cos(Δγ)·sin(η)

C=sin(ν)·sin(Δγ)·sin(η)

D=cos(ν)·cos(Δγ)·sin ²(η)

E=cos(ν)·cos(Δγ)·cos(η)

In single-shaft tracking system formula (9):

A=sin(ν)·cos(Δγ)

B=cos(ν)·cos(Δγ)·sin(η)

C=sin(ν)·sin(Δγ)·sin(β+Δβ)

D=cos(ν)·cos(Δγ)·sin(η)·sin(β+Δβ)

E=cos(ν)·cos(Δγ)·cos(β+Δβ)。

As seen from the above analysis:

I. to what on surface level, install, towards the double-axis tracking system in due south, the optimal tracking angle is respectively:

ν _s=ν；η _s=η。

Ii. on surface level, installing, the single-shaft tracking system towards the due south, the optimal tracking angle is:

ν _s=arctan (tan ν/cos (η-β)), wherein β is single-shaft tracking system system inclination angle.

Iii. to because construction error, or there is gradient Δ β in the system itself that reason such as geographic position causes, and towards the photovoltaic tracking system of relative polarization south Δ γ, wherein Δ γ is the azimuth angle error that reason such as construction and installation causes, and Δ γ is by east for negative, and is to the west for just; The gradient that Δ β causes for the ground out-of-flatness, Δ β is exposed to the north to negative on the Northern Hemisphere towards Nan Weizheng, and the Southern Hemisphere is opposite.η then _s=β+Δ β;

$v_s={\tan }^{-1}\left(\frac{A-B}{C+D+E}\right).$

With transverse axis tracker β=0 (belong to the inclination angle be 0 single-shaft tracking system) is example; Fig. 5 (a) (b) (c) is 36.72 ° of north latitude (d); 101.75 ° of areas of east longitude, horizontal tracker are respectively in Δ γ=0 ° and the optimal tracking angle when Δ β=0 °, Δ γ=0 ° and Δ β=10 °, Δ γ=10 ° and Δ β=0 ° and Δ γ=10 ° and Δ β=10 ° and the time dependent trend of difference at ν angle.We can see from figure, and 10 ° deviation can be brought 2 ° ~ 3 ° tracking error to tracker on the position angle.Because it is higher to analyze the place latitude, the summer solstice, this difference was minimum, and on average about-2 °, the winter solstice, this difference was maximum, when maximum up to more than 20 °.

Claims (1)

1. definite method of photovoltaic tracking system optimal tracking angle under the accurate equatorial coordinate system is characterized in that: under accurate equatorial coordinate system, to what on surface level, install, towards the optimal tracking angle η of the bi-axial tilt axle tracing system in due south _s=η, ν _s=ν; Wherein the ν angle is that sunray and this light are at y ₀o ₀z ₀Angle between the projection on plane, place, angle η is this projection and z ₀The angle of axle;

To what on surface level, install, the β angle single-axis tilt axle tracing system that inclines towards the due south has:

$\left(7\right),v_s={\tan }^{-1}\left(\frac{\tan \left(v\right)}{\cos (\mathrm{\η}-\mathrm{\β})}\right)$

Have azimuth angle deviation Δ γ if system installs, Δ γ is by east for negative, and is to the west for just; Or the gradient that the face of land is installed is Δ β, and Δ β is exposed to the north to negative on the Northern Hemisphere towards Nan Weizheng, and the Southern Hemisphere is opposite; Then system's optimal tracking angle is suc as formula (9) and formula (10);

If system exists Δ γ or Δ β, then

$v_s={\tan }^{-1}\left(\frac{A-B}{C+D+E}\right)---\left(9\right)$

η _s=β=η-Δβ （10）

To the bi-axial tilt axle tracing system, in the formula (9):

A=sin(ν)·cos(Δγ)

B=cos(ν)·cos(Δγ)·sin(η)

C=sin(ν)·sin(Δγ)·sin(η)

D=cos(ν)·cos(Δγ)·sin ²(η)

E=cos(ν)·cos(Δγ)·cos(η)

To the single-axis tilt axle tracing system, in the formula (9):

A=sin(ν)·cos(Δγ)

B=cos(ν)·cos(Δγ)·sin(η)

C=sin(ν)·sin(Δγ)·sin(β+Δβ)

D=cos(ν)·cos(Δγ)·sin(η)·sin(β+Δβ)

E=cos(ν)·cos(Δγ)·cos(β+Δβ)。

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