CN105972836B - A kind of quick focus adjustment method of solar energy dish-style concentrator mirror unit installation - Google Patents

Abstract

The invention discloses a fast focusing method for installing a mirror unit of a solar dish concentrator. The implementation steps are as follows: 1) establishing a database of one-to-one correspondence between the space pose error of each mirror unit and the feature of the focused spot; 2) concentrating When the device is tracking the sun, the image acquisition system obtains the image of the focused spot that the mirror unit to be adjusted focuses on the receiving target on the focal plane, and processes it to obtain the characteristics of the focused spot. 3) Compare the focus spot features in step 2) with the database of the same mirror unit number established in step 1), and obtain the corresponding mirror unit space pose error that matches the focus spot features, and get the spherical hinge bolt of the mirror unit Adjust the length to adjust the mirror unit quantitatively. The mirror unit of the present invention is simple to adjust the focus, and can eliminate the rotation error of the mirror unit in one step, and can effectively meet the high-efficiency and low-cost focus adjustment requirements of the solar concentrating system in my country at the present stage.

Description

A fast focusing method for installation of solar dish concentrator mirror unit

technical field

The invention relates to the field of solar thermal power generation, in particular to a fast focusing method for installing a mirror unit of a solar dish concentrator.

Background technique

Dish/Stirling solar thermal power generation system (DS-CSP) has the characteristics of high photoelectric conversion efficiency, flexible layout and high degree of modularization, and is one of the important equipment for the efficient development of solar energy resources. The concentrator of DS-CSP is composed of several mirror units spliced to form a parabolic surface, which is used to realize the directional transmission and efficient concentration of solar light energy. In essence, the concentrator is a set of precision optical devices, but limited by the precision of the fabrication and installation of the concentrator grid structure, the focusing process during the installation of the mirror unit is necessary. In addition, the concentrator works in a high-sunshine outdoor environment and is subject to harsh weather such as wind, sand, rain, and high temperature difference all year round. During the service period of the solar thermal power station (generally 20 to 25 years), the damage of the reflector or the concentration efficiency The reduction is inevitable, and at this time, the efficient and high-precision replacement of some local mirror surfaces will become particularly important. Therefore, it is particularly urgent to provide an efficient and accurate fast focusing method for installing or replacing the damaged mirror unit of the condenser, which has important engineering practical significance.

The currently used concentrator reflector mirror focusing methods mainly include:

(1) The concentrator is working in the solar tracking state. The operator 1 adjusts the connecting bolts on the back of the concentrator, and the receiving target is placed at the focal plane position, and the operator 2 observes the deviation of the light spot received by the receiving target. , and inform operator 1 to make corresponding adjustments. It is obvious that at least two people are required to work together in this mirror installation method, and the focusing process is qualitatively adjusted based on experience or the shift of the light spot, and the focusing efficiency is very low.

(2) In prior art 1 (CN 104062743 A), an automatic focusing system and a focusing method thereof for adjusting solar concentrating mirrors are disclosed, the method mainly judges the inclination angle by observing the image color of the reflecting mirror Approximate orientation, calculate the ratio of each color on the disc, and compare it with the pre-stored experience database to inform the operator to make corresponding adjustments. The core part of it is to establish an experience database, but this patent does not disclose the specific content and establishment method of the database, resulting in poor implementability of the technology, and the technology is also based on qualitative guidance and adjustment, and cannot accurately inform the operator of the mirror surface. The adjustment amount and adjustment sequence of the units, and the overall adjustment efficiency need to be further improved.

Contents of the invention

In order to solve the above-mentioned technical problems, the present invention provides a solar dish concentrator mirror unit installation system that obtains the spatial pose of the mirror unit by comparing the focused spot database, and quickly and accurately quantitatively provides the adjustment amount of the ball hinge bolt of the mirror unit. Fast focusing method.

In order to solve the problems of the technologies described above, the technical solution adopted in the present invention is:

A method for quickly adjusting the focus of solar dish concentrator mirror unit installation, comprising the following steps:

1) According to the division of fan-shaped mirror units of the designed dish concentrator, the mirror units are numbered, and a database of one-to-one correspondence between the spatial pose error of each mirror unit and the characteristic parameters of the focal spot is established;

2) When the concentrator is tracking the position of the sun in real time, install a square receiving target with a Lambertian effect on the focal plane of the concentrator, set the serial number of the mirror unit to be adjusted, and obtain the target to be adjusted through the image acquisition system. The focus mirror unit condenses the focus spot image on the plane receiving target separately, and processes it at the data processing terminal to obtain the characteristic parameters of the focus spot; when the focus spot characteristics meet the installation requirements, fix the ball hinge bolt of the mirror unit , the mirror unit is installed; otherwise, proceed to the next step;

3) Compare the characteristic parameters of the focus spot obtained in step 2) with the database of the same mirror unit number established in step 1), and obtain the spatial pose error of the mirror unit corresponding to the match of the focus spot characteristics, and obtain the spherical hinge supported by the mirror unit Adjust the length of the bolt to adjust the mirror unit quantitatively.

In the fast focusing method that the above-mentioned solar dish concentrator mirror unit is installed, the specific steps of database establishment in step 1) are as follows:

1.1) When the mirror unit is in the design pose, establish a coordinate system O-xyz at a fixed point on the parabolic surface of the concentrator, and the z-axis points to the focal point F of the parabolic surface; divide the optical grid for the mirror unit, and obtain the center points of each grid position vector and inner normal unit vector;

1.2) Calculate the spherical hinge center position vector of the spherical hinge bolt supported and adjusted by the mirror element;

1.3) The pose error is equivalently introduced through the combination of the overall translation motion of the mirror unit and the rotation motion around the spherical joint, and the position vector and inner normal unit vector of each grid center point under the corresponding pose error working condition are calculated;

1.4) Divide the square plane receiving target located at the focal plane into a rectangular grid, and discretize the incident light cone of the sun, and use the ray tracing method to calculate the focusing spot of the mirror unit on the plane receiving target under the condition of pose error energy flow density distribution;

1.5) Extract the characteristic boundary points of the focused spot through the local concentration ratio threshold, and use the least squares method to perform ellipse fitting on the boundary points. Focus on the characteristic parameters of the spot, and calculate the adjustment length of the spherical hinge bolt under the pose error, form a one-to-one data element corresponding to the focus spot feature, the mirror unit pose error, and the spherical hinge bolt adjustment, and calculate several kinds of mirror units The data elements in the pose situation, so as to establish a clustered spot feature database of pose errors;

1.6) The database is sorted according to the x-axis coordinates of the center of the ellipse from small to large, which is convenient for fast matching of focal spot features.

In the fast focusing method that the above-mentioned solar dish type concentrator mirror unit is installed, the specific steps of obtaining the characteristic parameters of the focused spot in step 2) are as follows:

2.1) The center of the square plane receiving target coincides with the focus F of the parabolic surface, and the two right-angled sides of the square are respectively translated to the x-axis and y-axis of the coordinate system O-xyz; the coordinate system Fx _F y _F is established at the center of the receiving target, Each axis of the coordinate system is parallel to each axis of the coordinate system O-xyz, and the spatial pose relationship between the image acquisition system and the plane receiving target is calibrated;

2.2) Collect the focused spot image of the mirror unit to be focused on the plane receiving target, and calculate the characteristic parameters of the focused spot image by the characteristic parameter calculation method of the focused spot in step 1.5);

In the fast focusing method that above-mentioned solar dish type concentrator mirror unit is installed, the specific steps of step 1.1) are as follows:

The mirror unit is divided into K parts with equal length along the radial direction, and M parts with equal angles along the circumferential direction, and the position vector and normal vector are calculated with the center point of the grid cell, then the number of the mirror unit is the grid of km grid center point The formulas for the coordinates of and the inner normal unit vector are as follows:

In the formula, R1 is the radius of the inner circle _of the mirror element; is the radial size of the grid micro _- element; R2 is the radial length of the mirror element; is the circumferential angle of the grid cells; θ is the circumferential angle of the mirror unit; e _z =[0,0,1] is the unit direction vector of the z-axis; the unified spatial equation of the mirror surface is F ₁ ( x, y, z)=zf ₁ (x, y)=0, the coordinate system O-xyz is established on the vertex of the mirror surface, and the z-axis points to the focus position. When it is a parabolic surface, f is the focal length; the function Rot(e,β) is a rotation function matrix, which is used to realize the function of rotating an angle β of any vector around any unit vector e=[e _x ,e _y ,e _z ], specifically:

In the formula, C=cosβ; S=sinβ.

sign is a symbolic variable, z _pkm is a point The z-axis component of the coordinate.

In the above-mentioned fast focusing method for installing the mirror unit of the solar dish concentrator, the position vectors of the centers A to C of the spherical joints in step 1.2) are calculated according to the following formula:

In the formula, the position vectors of the projection points a~c of the center of the spherical joint on the mirror surface are:

a=[R ₂ -δ ₂ ,0,f ₁ (R ₂ -δ ₂ ,0)]·Rot(e _z ,θ-β ₁ );

b=[R ₂ -δ ₂ ,0,f ₁ (R ₂ -δ ₂ ,0)]·Rot(e _z ,β ₁ );

The unit normal vector of the plane abc

In the formula: δ ₁ and δ ₂ are the distance between the support projection point and the edge of the mirror unit; β ₁ is the angle between the projection point and the origin and the edge of the mirror unit; n is the number of spherical hinge supports of the mirror unit; δ ₃ is the plane The distance between abc and the plane ABC.

In the fast focusing method that the above-mentioned solar dish type concentrator mirror unit is installed, the calculation steps and method of step 1.3) are as follows:

1.3.1) The mirror unit performs a number of rotations around the axis and translational movements sequentially from the design position, where the rotation axis is formed by any two centers of spherical joints; the angular range of the mirror unit’s rotation is The range of each axial component of the overall translation motion is -δ～δ, and the motion parameters of rotation and translation are combined to obtain the pose error vector T _error =[R _i ,M ₁ ] of the mirror unit, where R _i is the rotation motion Vector, the subscript i=1~6 are respectively ABC, ACB, BAC, BCA, CAB, CBA a total of 6 rotation motion sequences, The overall translation motion vector is M _i =[x _i , y _i , z _i ];

1.3.2) Calculate the position vector and inner normal unit vector of each grid center point under the pose error vector; the steps are as follows:

(1) Rotate the first spherical joint center E around the axis GP according to the rotation sequence At this time, the center point of the grid km in the mirror unit Movement to the point Then rotate the center G of the second spherical joint around the axis EP by an angle At this time, the center point of the grid km in the mirror unit Movement to the point Then rotate the center P of the third spherical joint around the axis EG At this time, the center point of the grid km in the mirror unit Movement to the point Then the whole mirror unit is translated according to the vector M _i =[ _xi ,y _i , _zi ]; E∈[A,B,C], G∈[A,B,C]; P∈[A,B ,C]; E≠G≠p;

The center point of the grid km within the mirror cell Movement to the point position, the corresponding position vectors of the motion phase are:

where the unit vector unit vector unit vector vector vector Vectors E, G, P are the position vectors of the first spherical joint center, the second spherical joint center and the third spherical joint center of the corresponding rotation sequence;

Introducing the pose error, the normal vector of the mirror unit grid microelement km is given by rotate to Calculated by the following formula:

In the formula, the total rotation matrix of the mirror unit pose

The calculation method of step 1.5) in the fast focusing method that the above-mentioned solar dish type concentrator mirror unit is installed is as follows:

1.5.1) Extract the position in the focused spot where the local concentration ratio is close to or equal to the threshold C _t as the boundary point; the search method for the boundary point is: combined with the grid divided by the planar receiving target, first extract column by column from top to bottom, etc. The upper boundary point and coordinates of the value line; and then extract the lower boundary point and coordinates of the contour line column by column from bottom to top. Finds when searching column by column that satisfies 2 neighboring grids of , and then according to Select the center point of the corresponding grid with the smallest difference as the boundary point, and its coordinates are marked as C _i ( _xi , y _i ); where, I(w, v) is the grid number w, v in the plane receiving target The energy flux density value is calculated by step 1.4); W ₀ is the solar direct radiation intensity value; the function min(a, b) is the smallest number among a and b;

1.5.2) Use the least squares method to perform ellipse fitting on the boundary points, and obtain the characteristic vector T _flux of the focused spot as:

T _flux =[d,φ ₁ ,φ ₂ ,a,b]=[x ₀ ,y ₀ ,φ ₂ ,a,b]

In the formula, the coordinate system Fx _F y _F is established at the focal point F of the focal plane. This coordinate system is parallel to the coordinate system O-xyz. The quantitative description parameters of the ellipse shape include the geometric center point O ₁ coordinates (x ₀ , y ₀ ), The dimension a of the semi-major axis of the ellipse and its angle φ ₂ with the coordinate x _F axis, and the dimension b of the semi-minor axis;

1.5.3) Calculate the screw adjustment lengths d _A ~ d _C of the spherical joint centers A ~ C that contribute to the rotation error of the mirror unit:

In the formula, the vector

1.5.4) Form the data elements uniquely corresponding to the focus spot feature, the mirror unit pose error and the adjustment amount of the spherical hinge bolt, and calculate the data elements of several kinds of mirror unit pose conditions, so as to establish the gathered spot feature database of the pose error .

In the fast focusing method that above-mentioned solar dish type concentrator mirror unit is installed, the characteristic parameter of the focus spot image in step 2.2) is calculated by the method of step 1.5.1) and step 1.5.2), adopts during calculation The direct solar radiation intensity value W ₀ is the measured value at the time of collection of the focused light spot of the mirror unit to be focused.

In the above-mentioned fast focusing method for the installation of the mirror unit of the solar dish concentrator, the method for obtaining the focused spot image of the individual concentrating light of the mirror unit to be focused in step 2) is: by moving the focused spot image of the mirror unit to be focused Go to the outside of the plane receiving target and collect the spot image 1 on the surface of the receiving target at this time, then preliminarily install the mirror unit to be adjusted, adjust the gathered light spot to the receiving target area, and the image acquisition system collects the spot image on the receiving target surface at this time For the spot image 2, subtract the gray value of the spot image 2 from the gray value of the spot image 1 to obtain the focused spot image of the mirror unit to be focused separately;

Or first install the mirror unit to be focused, and adjust the gathered light spot to the receiving target area, the image acquisition system collects the light spot image 1 on the surface of the receiving target at this time, and then block the mirror unit to be focused, and Collect the spot image 2 on the surface of the receiving target at this time, and subtract the gray value of the spot image 2 from the gray value of the spot image 1 to obtain the focused spot image of the single focused light of the mirror unit to be focused.

In the above-mentioned quick focusing method for installing the mirror unit of the solar dish concentrator, the position vectors of the centers A to C of the spherical joints in step 1.2) are obtained directly from the design drawings.

Compared with prior art, the beneficial effect of the present invention is:

1. The present invention directly matches and compares the actual focal spot features of the mirror unit with the database by establishing a database of one-to-one correspondence between the spatial pose error of the mirror unit and its gathered spot features, and then inverts the spatial pose of the mirror unit, and converts the mirror unit The bolt adjustment amount of the unit is fed back to the operator, and corresponding adjustments can be made to eliminate the rotation error of the mirror unit in one step. Coke is quick and easy.

2. The present invention extracts the boundary points of the focus spot by introducing the local concentration ratio threshold C _t , and carries out ellipse fitting of the boundary points; eliminates the influence of the solar irradiance intensity value on the focus spot features, and combines the pre-established database with In connection with the actual gathered spot features (different solar irradiance values), in the actual focusing process of the mirror unit, it is only necessary to monitor the direct solar irradiance value at the time when the focused spot of the mirror unit to be adjusted is collected; corresponding adjustments.

3. The present invention has real-time quantitative guidance for the focusing of the mirror unit, and can provide quantitative adjustment guidance. The method has the advantages of high efficiency and high precision, and the present invention can also be applied to other surface-shaped concentrator mirrors During adjustment of the unit. The present invention establishes a one-to-one correspondence between the focus spot features and the pose error, and can separate the focus spot of a single mirror unit from the focus spot of the concentrator, and does not need to block or only need to be adjusted for other mirror units. It is one of the main innovations of the present invention to perform short-term shading processing on the focused mirror unit itself, which can effectively meet the requirements of high-efficiency and low-cost precise installation of solar concentrating systems.

Description of drawings

Figure 1 is a schematic structural diagram of a dish/Stirling solar thermal power generation system.

FIG. 2 is a structural schematic diagram of installation and focusing of the mirror unit in FIG. 1 .

FIG. 3 is a flow chart of the method for quickly adjusting the focus of the mirror unit of the present invention.

Fig. 4 is a flow chart of the establishment of the database in Fig. 3 of the present invention.

FIG. 5 is a flow chart of obtaining individual focusing spot characteristics of the mirror unit to be adjusted in FIG. 3 according to the present invention.

Figure 6 shows the structural parameters and optical grid division of the mirror unit.

Fig. 7 is an elliptical geometric representation of the focused light spot of the mirror unit.

detailed description

The present invention will be further described in detail below in conjunction with the accompanying drawings.

Firstly, for a clearer understanding of the position of the mirror unit in the concentrator and its fixing method. As shown in FIG. 1 , the structural diagram of the dish/Stirling solar thermal power generation system, the mirror unit 2 is installed on the truss structure 1 of the concentrator. The specific fixing structure of the mirror unit 2 is shown in Figure 2. The ball end of the ball stud 3 is connected with the mirror unit 2 using a spherical hinge structure, and the other end of the ball stud 3 passes through the through hole of the truss structure 1, and is connected by a The spherical washers and nuts are fixed on the truss structure 1, and the mirror unit is generally fixed by 3 or 4 spherical joint supports. The focusing process of the mirror unit 2 is a process of adjusting the supporting length of the ball stud 3 .

As shown in Figure 3, the operation steps of the present invention are as follows:

1) According to the division of the fan-shaped mirror units of the designed dish concentrator, the mirror units are numbered, and a database of one-to-one correspondence between the spatial pose error of each mirror unit and the characteristic parameters of the focal spot is established.

As shown in Figure 4, the establishment method of the database, the specific steps are as follows:

1.1) When the mirror unit is in the design pose, the mirror unit is divided into optical grids, and the position vector and internal normal unit vector of each grid center point are obtained. As shown in Fig. 6, a global coordinate system O-xyz is established at the apex of the concentrator mirror surface, where the z-axis points to the focus position. The mirror unit is divided into K parts with equal length along the radial direction, and divided into M parts with equal angles along the circumferential direction, and the position vector and normal vector are calculated with the center point of the grid cell, then the number of the mirror unit is the grid of km grid center point The coordinates and inner normal unit vector of are shown in formula (1) and formula (2):

In the formula, R1 is the radius of the inner circle _of the mirror element; is the radial size of the grid micro _- element; R2 is the radial length of the mirror element; is the circumferential angle of the grid cells; θ is the circumferential angle of the mirror unit; e _z =[0,0,1] is the unit direction vector of the z-axis; the unified spatial equation of the mirror surface is F ₁ ( x, y, z)=zf ₁ (x, y)=0, the coordinate system O-xyz is established on the vertex of the mirror surface, and the z-axis points to the focus position. When it is a parabolic surface, f is the focal length; the function Rot(e,β) is a rotation function matrix, which is used to realize the function of rotating an angle β of any vector around any unit vector e=[e _x ,e _y ,e _z ], specifically:

In the formula, C=cosβ; S=sinβ.

sign is a symbolic variable, z _pkm is a point The z-axis component of the coordinate.

1.2) In the case of the design pose, calculate the center position vector of the spherical hinge bolts supported and adjusted by the mirror element. The calculation formula of the position vector of the spherical joint center A~C is as follows

In the formula, the position vectors of the projection points a~c of the center of the spherical joint on the mirror surface are:

a=[R ₂ -δ ₂ ,0,f ₁ (R ₂ -δ ₂ ,0)]·Rot(e _z ,θ-β ₁ );

b=[R ₂ -δ ₂ ,0,f ₁ (R ₂ -δ ₂ ,0)]·Rot(e _z ,β ₁ );

The unit normal vector of the plane abc

In the formula: δ ₁ and δ ₂ are the distances between the support projection point and the edge of the mirror unit; β ₁ is the angle between the projection point and the origin and the edge of the mirror unit; n is the number of spherical hinge supports of the mirror unit, and n=3 is Three-spherical joint support, n=4 is four-spherical joint support; δ ₃ is the distance between plane abc and plane ABC. The position vectors of the centers A~C of the spherical joint can also be obtained in other ways, such as directly obtained from the design drawings.

1.3) The pose error is equivalently introduced through the combination of the overall translation motion of the mirror unit and the rotation motion around the spherical joint, and the position vector and inner normal unit vector of each grid center point corresponding to the pose error condition are calculated. Specific steps are as follows:

1.3.1) The mirror unit performs several rotations around the axis and translational movements sequentially from the ideal position, wherein the rotation axis is formed by any two centers of spherical joints. The angular range of the rotation motion of the mirror unit is (unit rad), the range of each axial component of the overall translation motion is -δ～δ (unit mm), and the rigid body motion parameters of rotation and translation are combined to obtain the pose error vector T _error of the mirror unit =[R _i , M ₁ ], where R _i is the rotational motion vector, and the subscripts i=1～6 are the rotational motion sequences of ABC, ACB, BAC, BCA, CAB, and CBA, for example, when i=1 The overall translation motion vector is M ₁ =[x ₁ ,y ₁ ,z ₁ ].

1.3.2) Calculate the position vector and inner normal unit vector of each grid center point under the pose error vector; the steps are as follows:

Taking A-B-C rotation movement + translation movement as an example, the steps are as follows:

(1) The mirror unit is located in the design pose, and the rotation angle of the center A of the spherical hinge around the axis CB (Regulations: the z-axis coordinate component of the center of the spherical joint increases to a positive angle, and the corresponding rotation axis direction is a positive direction), move to the A ₁ position;

(2) Rotation angle of spherical hinge center B around axis A ₁ C Move to B1 position _;

(3) The rotation angle of the spherical hinge center C around the axis B ₁ A ₁ Move to _C1 position;

(4) Translate the entire mirror unit according to the vector M ₁ =[x ₁ , y ₁ , z ₁ ].

The center point of the grid km within the mirror cell Movement to the point position, the corresponding position vectors of the motion phase are:

where the unit vector unit vector unit vector vector vector

Introducing the pose error, the normal vector of the mirror unit grid microelement km is given by rotate to Calculated by the following formula:

In the formula, the total rotation matrix of the mirror unit pose

Similarly, the position vector and inner normal unit vector of each grid center point of other rotation sequence working conditions can be obtained according to the above method.

1.4) Carry out grid division on the square plane receiving target located at the focal plane position, as shown in Figure 7, the plane receiving target is a square with the focus F as the center, its side length is L, and the grid is divided into W×V parts, And W=V, the starting number of the grid is at the upper right corner. The incident light from the sun is discretized, and the ray tracing method is used to calculate the energy flux density distribution of the focused spot of the mirror unit on the plane receiving target under the condition of pose error. The calculation of the focused energy flow distribution in this part is a well-known and mature calculation method, and will not be described in detail here.

1.5) Extract the characteristic boundary points of the focused spot through the local concentration ratio threshold, and use the least squares method to perform ellipse fitting on the boundary points, using the coordinates of the center point of the plane ellipse geometry, the angle between the pose and the size of the long and short semi-axes, etc. Five parameters are used to characterize the characteristics of the focus spot, and the adjustment amount of the spherical hinge bolt for the pose error is calculated to form unique corresponding data elements such as the focus spot feature, the mirror unit pose error, and the adjustment amount of the spherical hinge bolt, and a number of data elements are calculated. The data elements of the pose situation of each mirror unit are used to establish a clustered spot feature database of pose errors. Among them, the calculation method of the focus spot feature and the error distance of the spherical hinge bolt, the specific steps are as follows:

1.5.1) Extract the position in the focused spot where the local concentration ratio is close to or equal to the threshold C _t as the boundary point (take the center point of the corresponding grid). The search method of the boundary point is: combined with the grid divided by the planar receiving target, first extract the upper boundary point and coordinates of the contour line from top to bottom; then extract the lower boundary point and coordinates of the contour line from bottom to top. coordinate. Finds when searching column by column that satisfies 2 neighboring grids of , and then according to Select the center point of the corresponding grid with the smallest difference as the boundary point, and its coordinates are marked as C _i ( _xi , y _i ). Among them, I(w, v) is the energy flux density value of the grid number w, v in the plane receiving target, which is calculated by step 1.4); W ₀ is the value of the direct solar radiation intensity; the function min(a, b) To take the smallest number of a and b.

1.5.2) Use the least squares method to fit the ellipse to the boundary points. The geometric representation of the ellipse is shown in Figure 7. The characteristic vector T _flux of the focused spot is obtained as:

T _flux =[d,φ ₁ ,φ ₂ ,a,b]=[x ₀ ,y ₀ ,φ ₂ ,a,b]

In the formula, the coordinate system Fx _F y _F is established at the focal point F of the focal plane, which is parallel to the coordinate system O-xyz, and the quantitative description parameters of the ellipse shape include the geometric center point O ₁ coordinate (x ₀ , y ₀ )( It can also be determined jointly by the distance d and the included angle φ ₁ ), the dimension a of the semi-major axis of the ellipse and its included angle φ ₂ with the coordinate x _F axis, and the dimension b of the semi-minor axis. The unit of angle φ ₁ and φ ₂ is rad, and the unit of characterizing length is mm.

1.5.3) The error of the spherical hinge bolt that contributes to the rotation error of the mirror unit can be completely eliminated by adjusting the length of the screw, while the error caused by translational motion can only be corrected by the overall translation of the mirror unit, which is generally difficult to deal with. Calculate the screw adjustment lengths d _A ~ d _C of the spherical joint centers A ~ C that contribute to the rotation error of the mirror unit:

In the formula, the vector

1.5.4) Form the one-to-one corresponding data elements of the focus spot feature, the mirror unit pose error, and the spherical hinge bolt adjustment amount, and calculate the data elements of several kinds of mirror unit pose conditions, and establish the gather spot feature of the pose error database.

1.6) Sort the database according to the x-axis coordinates of the center of the ellipse from small to large, so as to quickly match the subsequent features of the focused spot.

2) When the concentrator is tracking the position of the sun in real time, install a square receiving target with a Lambertian effect on the focal plane of the concentrator, set the serial number of the mirror unit to be adjusted, and obtain the target to be adjusted through the image acquisition system. The focal mirror unit separately condenses the focused spot image on the plane receiving target, and processes it at the data processing terminal to obtain the characteristic parameters of the focused spot. When the feature of the focused spot meets the installation requirements, fix the ball hinge bolts of the mirror unit, and the mirror unit is installed. Otherwise, proceed to the next step.

The steps to obtain the characteristic parameters of the focus spot of the mirror unit to be focused are as follows:

2.1) Establish a coordinate system at the center position of the planar receiving target (that is, the focus of the light collector), and calibrate the spatial pose relationship between the image acquisition system and the planar receiving target.

2.2) Collect the focused spot image of the mirror unit to be focused on the plane receiving target, and use the same concentration ratio threshold, feature extraction and ellipse fitting method as in step 1.5) to obtain the characteristic parameters of the focused spot image.

The method of obtaining the focused spot image of the single condensed light of the mirror unit to be focused is as follows: firstly, by moving the focused spot image of the mirror unit to the outside of the plane receiving target and collecting the spot image 1 on the surface of the receiving target at this time, and then the mirror unit to be focused The unit is initially installed, and the gathered light spot is adjusted to the receiving target area, and the image acquisition system collects the light spot image 2 on the surface of the receiving target at this time; the gray value of the light spot image 1 is subtracted from the gray value of the light spot image 2. Obtaining the focused spot image of the single condensed light of the mirror unit to be focused, this method does not need to block other mirror units.

The following method can also be used to obtain the focused spot image of the single condensed light of the mirror unit to be focused: first, the mirror unit to be focused is initially installed, and the gathered spot is adjusted to the receiving target area, and the image acquisition system collects at this time The spot image 1 of the receiving target surface; then block the mirror unit to be focused, and collect the spot image 2 of the receiving target surface at this time; subtract the gray value of the spot image 2 from the gray value of the spot image 1 to obtain A focused spot image of the individually focused light of the mirror unit to be focused can be obtained. This method only needs to occlude the mirror unit to be focused, and the entire operation is also efficient and convenient.

3) Compare the characteristic parameters of the focus spot obtained in step 2) with the database of the same mirror unit number established in step 1), and obtain the space pose error of the corresponding mirror unit whose features of the focus spot match, and obtain the ball supported by the mirror unit Adjust the length of the hinge bolt to adjust the mirror unit quantitatively.

Since the present invention provides a one-to-one correspondence between the focus spot feature and the mirror unit pose error, only one quantitative adjustment is required to achieve accurate focus adjustment of the mirror unit, but considering the manufacturing error of the actual mirror unit, it may be necessary Steps 2 and 3 are performed multiple times until the spatial pose of the mirror unit meets the distribution requirements of the focus spot.

The fast focusing method for installation of the mirror unit of the solar dish concentrator of the present invention, by establishing a one-to-one correspondence database of the space pose error of the mirror unit and its gathered spot features, directly compares the actual focus spot features of the mirror unit with the database Match and compare, and then invert the spatial pose of the mirror unit, and feed back the bolt adjustment amount of the mirror unit to the operator, and make corresponding adjustments, which can eliminate the rotation error of the mirror unit in one step. The whole focusing process is direct. Focusing on concentrating performance, it can effectively adapt to the engineering application requirements of high-efficiency, low-cost and precise installation of solar concentrating systems in my country at this stage.

Claims (10)

1. A quick focusing method that solar dish type concentrator mirror unit is installed, comprises the steps: 1) According to the division of fan-shaped mirror units of the designed dish concentrator, the mirror units are numbered, and a database of one-to-one correspondence between the spatial pose error of each mirror unit and the characteristic parameters of the focal spot is established; 2) When the concentrator is tracking the position of the sun in real time, install a square receiving target with a Lambertian effect on the focal plane of the concentrator, set the serial number of the mirror unit to be adjusted, and obtain the target to be adjusted through the image acquisition system. The focus mirror unit condenses the focus spot image on the plane receiving target separately, and processes it at the data processing terminal to obtain the characteristic parameters of the focus spot; when the focus spot characteristics meet the installation requirements, fix the ball hinge bolt of the mirror unit , the mirror unit is installed; otherwise, proceed to the next step; 3) Compare the characteristic parameters of the focus spot obtained in step 2) with the database of the same mirror unit number established in step 1), and obtain the spatial pose error of the mirror unit corresponding to the match of the focus spot characteristics, and obtain the spherical hinge supported by the mirror unit Adjust the length of the bolt to adjust the mirror unit quantitatively. 2. the fast focusing method that solar dish type concentrator mirror unit according to claim 1 is installed, the concrete steps that database is set up in step 1) are as follows: 1.1) When the mirror unit is in the design pose, establish a coordinate system O-xyz at a fixed point on the parabolic surface of the concentrator, and the z-axis points to the focal point F of the parabolic surface; divide the optical grid for the mirror unit, and obtain the center points of each grid position vector and inner normal unit vector; 1.2) Calculate the spherical hinge center position vector of the spherical hinge bolt supported and adjusted by the mirror element; 1.3) The pose error is equivalently introduced through the combination of the overall translation motion of the mirror unit and the rotation motion around the spherical joint, and the position vector and inner normal unit vector of each grid center point under the corresponding pose error working condition are calculated; 1.4) Divide the square plane receiving target located at the focal plane into a rectangular grid, and discretize the incident light cone of the sun, and use the ray tracing method to calculate the focus spot energy of the mirror unit on the plane receiving target under the condition of pose error flow density distribution; 1.5) Extract the characteristic boundary points of the focused spot through the local concentration ratio threshold, and use the least squares method to perform ellipse fitting on the boundary points. Focus on the characteristic parameters of the spot, and calculate the adjustment length of the spherical hinge bolt under the pose error, form a one-to-one data element corresponding to the focus spot feature, the mirror unit pose error, and the spherical hinge bolt adjustment, and calculate several kinds of mirror units The data elements in the pose situation, so as to establish a clustered spot feature database of pose errors; 1.6) The database is sorted according to the x-axis coordinates of the center of the ellipse from small to large, which is convenient for fast matching of focal spot features. 3. the fast focusing method that solar dish type concentrator mirror unit according to claim 1 is installed, step 2) in the concrete steps of obtaining focus spot feature parameter as follows: 2.1) The center of the square plane receiving target coincides with the focus F of the parabolic surface, and the two right-angled sides of the square are respectively translated to the x-axis and y-axis of the coordinate system O-xyz; the coordinate system Fx _F y _F is established at the center of the receiving target, Each axis of the coordinate system is parallel to each axis of the coordinate system O-xyz, and the spatial pose relationship between the image acquisition system and the plane receiving target is calibrated; 2.2) Collect the focused spot image of the mirror unit to be focused on the plane receiving target, and calculate the characteristic parameters of the focused spot image by the characteristic parameter calculation method of the focused spot in step 1.5). 4. the fast focusing method that solar dish type concentrator mirror unit according to claim 2 is installed, the concrete steps of step 1.1) are as follows: The mirror unit is divided into K parts with equal length along the radial direction, and M parts with equal angles along the circumferential direction, and the position vector and normal vector are calculated with the center point of the grid cell, then the number of the mirror unit is the grid of km grid center point The coordinates and inner normal unit vector formulas of are as follows: In the formula, R1 is the radius of the inner circle _of the mirror element; is the radial size of the grid micro _- element; R2 is the radial length of the mirror element; is the circumferential angle of the grid cells; θ is the circumferential angle of the mirror unit; e _z =[0,0,1] is the unit direction vector of the z-axis; the unified spatial equation of the mirror surface is F ₁ ( x, y, z)=zf ₁ (x, y)=0, the coordinate system O-xyz is established on the vertex of the mirror surface, and the z-axis points to the focus position. When it is a parabolic surface, f is the focal length; the function Rot(e,β) is a rotation function matrix, which is used to realize the function of rotating an angle β of any vector around any unit vector e=[e _x ,e _y ,e _z ], specifically: In the formula, C=cosβ; S=sinβ; sign is a symbolic variable, z _pkm is a point The z-axis component of the coordinate. 5. the fast focusing method that the mirror unit of solar dish type concentrator according to claim 4 is installed, the position vector of the spherical hinge center A～C in the step 1.2) is calculated by the following formula: In the formula, the position vectors of the projection points a~c of the center of the spherical joint on the mirror surface are: a=[R ₂ -δ ₂ ,0,f ₁ (R ₂ -δ ₂ ,0)]·Rot(e _z ,θ-β ₁ ); b=[R ₂ -δ ₂ ,0,f ₁ (R ₂ -δ ₂ ,0)]·Rot(e _z ,β ₁ ); The unit normal vector of the plane abc In the formula: δ ₁ and δ ₂ are the distance between the support projection point and the edge of the mirror unit; β ₁ is the angle between the projection point and the origin and the edge of the mirror unit; n is the number of spherical hinge supports of the mirror unit; δ ₃ is the plane The distance between abc and the plane ABC. 6. the fast focusing method that solar dish type concentrator mirror unit according to claim 5 is installed, step 1.3) computing steps and method are as follows: 1.3.1) The mirror unit performs a number of rotations around the axis and translational movements sequentially from the design position, where the rotation axis is formed by any two centers of spherical joints; the angular range of the mirror unit’s rotation is The range of each axial component of the overall translation motion is -δ～δ, and the motion parameters of rotation and translation are combined to obtain the pose error vector T _error =[R _i ,M ₁ ] of the mirror unit, where R _i is the rotation motion Vector, the subscript i=1~6 are respectively ABC, ACB, BAC, BCA, CAB, CBA a total of 6 rotation motion sequences, The overall translation motion vector is M _i =[x _i , y _i , z _i ]; 1.3.2) Calculate the position vector and inner normal unit vector of each grid center point under the pose error vector; the steps are as follows: (1) Rotate the first spherical joint center E around the axis GP according to the rotation sequence At this time, the center point of the grid km in the mirror unit Movement to the point Then rotate the center G of the second spherical joint around the axis EP by an angle At this time, the center point of the grid km in the mirror unit Movement to the point Then rotate the center P of the third spherical joint around the axis EG At this time, the center point of the grid km in the mirror unit Movement to the point Then the whole mirror unit is translated according to the vector M _i =[ _xi ,y _i , _zi ]; E∈[A,B,C], G∈[A,B,C]; P∈[A,B ,C]; E≠G≠p; The center point of the grid km within the mirror cell Movement to the point position, the corresponding position vectors of the motion phase are: where the unit vector unit vector unit vector vector vector Vectors E, G, P are the position vectors of the first spherical joint center, the second spherical joint center and the third spherical joint center of the corresponding rotation sequence; Introducing the pose error, the normal vector of the mirror unit grid microelement km is given by rotate to Calculated by the following formula: In the formula, the total rotation matrix of the mirror unit pose 7. the fast focusing method that solar dish type concentrator mirror unit according to claim 6 is installed, step 1.5) calculation method is as follows: 1.5.1) Extract the position in the focused spot where the local concentration ratio is close to or equal to the threshold C _t as the boundary point; the search method for the boundary point is: combined with the grid divided by the planar receiving target, first extract column by column from top to bottom, etc. The upper boundary point and coordinates of the value line; then extract the lower boundary point and coordinates of the contour line from bottom to top column by column; when searching column by column, find the 2 neighboring grids of , and then according to Select the center point of the corresponding grid with the smallest difference as the boundary point, and its coordinates are marked as C _i ( _xi , y _i ); where, I(w, v) is the grid number w, v in the plane receiving target The energy flux density value is calculated by step 1.4); W ₀ is the solar direct radiation intensity value; the function min(a, b) is to take the smallest number among a and b; 1.5.2) Use the least squares method to perform ellipse fitting on the boundary points, and obtain the characteristic vector T _flux of the focused spot as: T _flux =[d,φ ₁ ,φ ₂ ,a,b]=[x ₀ ,y ₀ ,φ ₂ ,a,b] In the formula, the coordinate system Fx _F y _F is established at the focal point F of the focal plane. This coordinate system is parallel to the coordinate system O-xyz. The quantitative description parameters of the ellipse shape include the geometric center point O ₁ coordinates (x ₀ , y ₀ ), The dimension a of the semi-major axis of the ellipse and its angle φ ₂ with the coordinate x _F axis, and the dimension b of the semi-minor axis; 1.5.3) Calculate the screw adjustment lengths d _A ~ d _C of the spherical joint centers A ~ C that contribute to the rotation error of the mirror unit: In the formula, the vector 1.5.4) Form the data elements uniquely corresponding to the focus spot feature, the mirror unit pose error and the adjustment amount of the spherical hinge bolt, and calculate the data elements of several kinds of mirror unit pose conditions, so as to establish the gathered spot feature database of the pose error . 8. the fast focusing method that the solar dish type concentrator mirror unit according to claim 7 is installed, step 2.2) in the feature parameter of the focus spot image by step 1.5.1) and the method for step 1.5.2) to carry out Calculation, the direct solar radiation intensity value W0 used in the calculation is the actual measured value _at the time of collection of the focused light spot of the mirror unit to be focused. 9. the fast focusing method that the solar dish type concentrator mirror unit according to claim 5 is installed, step 2) the obtaining method of the focused spot image of the independent focus of the mirror unit to be adjusted is: by The focusing spot of the focusing mirror unit moves to the outside of the plane receiving target and collects the spot image 1 on the surface of the receiving target at this time, and then preliminarily installs the mirror unit to be adjusted, adjusts the gathered spot to the receiving target area, and the image acquisition system collects Receive the spot image 2 on the target surface at this time, and subtract the gray value of the spot image 2 from the gray value of the spot image 1 to obtain the focused spot image of the single focusing mirror unit to be focused; Or first install the mirror unit to be focused, and adjust the gathered light spot to the receiving target area, the image acquisition system collects the light spot image 1 on the surface of the receiving target at this time, and then block the mirror unit to be focused, and Collect the spot image 2 on the surface of the receiving target at this time, and subtract the gray value of the spot image 2 from the gray value of the spot image 1 to obtain the focused spot image of the single focused light of the mirror unit to be focused. 10. The fast focusing method for solar dish concentrator mirror unit installation according to claim 2, the position vectors of the centers A to C of the spherical joints in step 1.2) are directly obtained from the design drawings.