Target point dynamic adjustment method for photo-thermal mirror field of multiple heat absorption towers

Abstract

The invention discloses a target point dynamic adjustment method for a photo-thermal mirror field of multiple heat absorption towers, and the method comprises the following steps: taking the center of the photo-thermal mirror field as an original point, and obtaining the center elevation position coordinates of a heat absorber on each heat absorption tower; calculating X, Y and Z coordinates of a target point of each heliostat on each heat absorber; calculating the power of a corresponding target point of each heliostat on each heat absorber at a certain moment based on a light trace tracking method, and establishing a 0-1 integer linear programming model by taking the maximized power of a photo-thermal mirror field as a target function; and solving the 0-1 integer linear programming model by using an implicit enumeration algorithm to obtain a target heat absorber pointed by each heliostat at the moment, thereby realizing dynamic adjustment of the target point of the photo-thermal mirror field. According to the method disclosed by the invention, the energy flux density on the heat absorption panel can be uniformly distributed, the light abandoning phenomenon can be reduced to the maximum extent, and the mirror field can reach the maximum power.

Description

Technical Field

[0001] The present invention relates to the field of photothermal power station control, and in particular to a method for dynamically adjusting target points of a photothermal mirror field with multiple heat absorption towers. Background Art

[0002] Tower-type CSP is an increasingly popular way of generating electricity, and is also one of the new clean energy storage methods. Tower-type CSP not only has the advantage of low power generation cost, but also can generate electricity continuously for 24 hours compared with photovoltaic power generation. CSP is also used in winter heating, oil extraction and other fields.

[0003] The principle of tower solar thermal power generation is to first arrange a large number of heliostats in different geometric shapes around the absorber, reflect a large amount of low-density solar energy onto the absorber to turn it into high-density solar energy, and then convert it into working fluid thermal energy and finally utilize the thermal energy, such as converting thermal energy into electrical energy.

[0004] Most of the tower-type CSP power plants currently under construction are single towers, that is, they only have one heat absorbing tower. However, in actual operation, it is found that there is always a phenomenon of "abandoned light" in summer or at noon. The phenomenon of abandoned light usually refers to the fact that only some heliostats participate in the actual work to reach the rated power of the heat absorber. The energy corresponding to the remaining heliostats that do not participate in the work is called abandoned light, which makes the tower-type CSP mirror field unable to fully output. With the large-scale development of CSP power stations, the scale of the mirror field is showing an increasingly larger trend. The maximum distance between the heliostat and the heat absorbing tower exceeds 1,500 meters, and the heliostat will have astigmatism. In response to this, some experts and scholars have proposed dual towers or multiple towers, so that all heliostats can be fully utilized to participate in the actual work, solve the phenomenon of abandoned light and avoid the occurrence of astigmatism.

[0005] Currently, the target point setting for multiple heat absorption towers is only based on operation and maintenance experience, and is often set according to the principle of proximity. The target point is mapped to the heat absorber to which the heliostat is closest. However, this often leads to local overheating of the heat absorber, making it impossible to maximize the utilization of the heliostats, thereby failing to achieve the maximum efficiency of the system. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a method for dynamically adjusting the target points of a multi-heat absorption tower thermal mirror field, so as to maximize the utilization of heliostats, avoid local overheating, and achieve the purpose of maximum system efficiency.

[0007] To achieve the above object, the technical solution of the present invention is as follows:

[0008] A method for dynamically adjusting target points of a multi-heat absorbing tower photothermal mirror field comprises the following steps:

[0009] Step 1: Taking the center of the photothermal mirror field as the origin, obtain the center elevation position coordinates of the heat absorber on each heat absorption tower;

[0010] Step 2, based on the center elevation position coordinates of each heat absorber, calculate the X coordinate and Y coordinate of the target point of each heliostat on each heat absorber;

[0011] Step 3, based on the center elevation position coordinates of each heat absorber and based on the energy maximization principle, determine the Z coordinate of the target point of each heliostat on each heat absorber;

[0012] Step 4: Calculate the power of each heliostat at the corresponding target point on each absorber at a certain moment based on the ray tracing method, and establish a 0-1 integer linear programming model with maximizing the power of the photothermal mirror field as the objective function;

[0013] Step 5, using an implicit enumeration algorithm to solve the 0-1 integer linear programming model, obtain the target absorber that each heliostat is pointing to at that moment, thereby realizing dynamic adjustment of the target point of the photothermal mirror field.

[0014] In the above scheme, step 1 is as follows: Assume that there are J heat absorption towers in the photothermal mirror field, each heat absorption tower has a heat absorber on the top, and the shape of heat absorber j is positive N j Prism, j = 1, 2, ... J, side length L j , high is S j ; The center elevation position coordinates of the heat absorber j are

[0015] In the above scheme, step 2 is as follows: Assume that there are M heliostats in the solar thermal mirror field. For heliostat i, i = 1, 2, ... M, first calculate the radius length R of the circumscribed circle of the absorber j. j :

[0016]

[0017] Based on the principle of the closest distance, the X coordinate of the target point of heliostat i on the receiver j is obtained and Y coordinate

[0018]

[0019] Among them, the heliostat and the absorber are projected onto the XY plane, β ij It represents the angle between heliostat i and absorber j in the horizontal direction, and its calculation formula is as follows:

[0020]

[0021] in, and are the X and Y coordinates of heliostat i respectively.

[0022] In the above scheme, step 3 is as follows:

[0023] The horizontal distance between heliostat i and receiver j is r ij , the center elevation of the heat absorber j is The target point of heliostat i on the absorber j is the line A between the center of the spot and the heliostat ij The angle with the horizontal direction is θ, and the line between the lower edge of the spot and the heliostat is A ′ ij , connection A ij With line A ′ ij The angle between them is θ ′ , from the lower edge of the spot to the line A ij The distance between According to the relationship between the sides of the right triangle, the following equation is established:

[0024]

[0025] in,

[0026]

[0027] in, and are the X and Y coordinates of heliostat i respectively;

[0028] Using stochastic gradient descent to find an approximate solution to a nonlinear equation Finally, the spot radius of heliostat i in the vertical direction is obtained

[0029] Based on the principle of energy maximization, the spot radius The larger the beam spot, the more the target point should be at the center of the absorber. The smaller the value, the target points should be randomly distributed on the absorber panel, so the Z coordinate of the target point of heliostat i on absorber j is determined as follows:

[0030]

[0031] Among them, sgn(x) is the sign function. When x>0, sgn(x)=1, otherwise sgn(x)=-1, and rand(0,1) is the random number function, which generates a random number between 0 and 1.

[0032] In the above scheme, step 4 is as follows: Based on the ray tracing method, the power p of the heliostat i at the corresponding target point on the absorber j at time T is calculated. ij , let b ijIs whether heliostat i uses the corresponding target point on absorber j. If b ij = 0, indicating that heliostat i does not use the corresponding target point on absorber j; if b ij =1, indicating that heliostat i uses the corresponding target point on absorber j; the 0-1 integer linear programming model is established as follows:

[0033]

[0034] Where M is the total number of heliostats.

[0035] In the above scheme, step 5 is as follows: Use the implicit enumeration algorithm to solve the 0-1 integer linear programming model and obtain the optimal solution (x 1j ,x 2j ,…,x Mj ), that is, the target receiver that each heliostat points to at time T.

[0036] Through the above technical solution, the method for dynamically adjusting the target point of a multi-heat absorption tower photothermal mirror field provided by the present invention has the following beneficial effects:

[0037] The present invention proposes for the first time a dynamic adjustment method for multiple heat absorption tower target points for tower-type solar thermal power generation; the multiple heat absorption tower target points set by the present invention can not only make the energy flow density on the heat absorption panel uniform in tower-type solar thermal power generation, but also minimize the phenomenon of abandoned light and enable the mirror field to achieve maximum power.

[0038] The present invention adopts 0-1 integer linear programming, which has the characteristics of simple calculation and fast response, and is particularly suitable for the control of tower-type solar thermal mirror fields, so that the heliostat can give feedback in a very short time (the optimal solution can be obtained within a few seconds, and it only takes 1 to 2 minutes for the final response of the heliostat to be completed), and can achieve the global optimum at every moment. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0040] Figure 1 A schematic flow chart of a method for dynamically adjusting target points in a multi-heat absorbing tower photothermal mirror field disclosed in an embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of a multi-heat absorption tower photothermal mirror field;

[0042] Figure 3 is a three-dimensional diagram of a heat absorber;

[0043] Figure 4 It is a schematic diagram of the projection of the heliostat and the absorber on the XY plane;

[0044] Figure 5 This is a three-dimensional schematic diagram of the heliostat and the absorber.

[0045] In the figure, E, heat absorption tower; F, absorber; G, heliostat. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0047] The present invention provides a method for dynamically adjusting the target point of a multi-heat absorbing tower photothermal mirror field, such as Figure 1 As shown, the following steps are included:

[0048] Step 1: Taking the center of the photothermal mirror field as the origin, obtain the center elevation position coordinates of the absorbers on each heat absorption tower.

[0049] like Figure 2 As shown, the multiple towers are generally distributed symmetrically around the center of the site. Assume that there are J heat absorption towers E in the photothermal mirror field, and J is usually 4, 6, 8, etc.; there is a heat absorber F on the top of each heat absorption tower E, such as Figure 3 As shown, the shape of the heat absorber j is positive N j Prism, j = 1, 2, ... J, side length L j , high is S j ; The center elevation position coordinates of the heat absorber j are

[0050] This embodiment takes four heat absorption towers E as an example. is the horizontal distance from the absorber j (j=1,2,3,4) to the center of the site.

[0051] Step 2: Based on the coordinates of the center elevation position of each heat absorber, the X coordinate and Y coordinate of the target point of each heliostat on each heat absorber are calculated.

[0052] Assume that there are M heliostats G in the solar thermal mirror field, such as Figure 4 As shown, for heliostat i, i = 1, 2, ... M, first calculate the radius length R of the circumscribed circle of the absorber j j :

[0053]

[0054] Project the heliostat and the absorber onto the XY plane, and the coordinates of the center position of the absorber j are The plane coordinates of heliostat i are Based on the principle of the closest distance, the X coordinate of the target point of heliostat i on the receiver j is obtained and Y coordinate

[0055]

[0056] Among them, the heliostat and the absorber are projected onto the XY plane, β ij It represents the angle between heliostat i and absorber j in the horizontal direction, and its calculation formula is as follows:

[0057]

[0058] Step 3: Based on the center elevation position coordinates of each heat absorber and based on the energy maximization principle, determine the Z coordinate of the target point of each heliostat on each heat absorber.

[0059] like Figure 5 As shown, the horizontal distance between heliostat i and receiver j is r ij , the center elevation of the heat absorber j is The target point of heliostat i on the absorber j is the line A between the center of the spot and the heliostat ij The angle with the horizontal direction is θ, and the line between the lower edge of the spot and the heliostat is A ′ ij , connection A ij With line A ′ ij The angle between them is θ ′ , from the lower edge of the spot to the line A ij The distance between According to the relationship between the sides of the right triangle, the following equation is established:

[0060]

[0061] in,

[0062]

[0063] in, and are the X and Y coordinates of heliostat i respectively;

[0064] Using stochastic gradient descent to find an approximate solution to a nonlinear equation Finally, the spot radius of heliostat i in the vertical direction is obtained

[0065] Based on the principle of energy maximization, the spot radius The larger the beam spot, the more the target point should be at the center of the absorber. The smaller the value, the target points should be randomly distributed on the absorber panel, so the Z coordinate of the target point of heliostat i on absorber j is determined as follows:

[0066]

[0067] Among them, sgn(x) is the sign function. When x>0, sgn(x)=1, otherwise sgn(x)=-1, and rand(0,1) is the random number function, which generates a random number between 0 and 1.

[0068] Combining steps 2 and 3, there are 4 possible valid target points for heliostat i: Where j=1,2,3,4.

[0069] Step 4: Calculate the power of each heliostat at the corresponding target point on each absorber at a certain moment based on the ray tracing method, and establish a 0-1 integer linear programming model with maximizing the power of the photothermal mirror field as the objective function;

[0070] Based on the ray tracing method (the most common method for calculating power in the field of tower thermal mirror field simulation), the power p of the heliostat i corresponding to the target point on the receiver j at time T is calculated. ij , let b ij Is whether heliostat i uses the corresponding target point on absorber j. If b ij = 0, indicating that heliostat i does not use the corresponding target point on absorber j; if b ij =1, indicating that heliostat i uses the corresponding target point on absorber j; the 0-1 integer linear programming model is established as follows:

[0071]

[0072] Where M is the total number of heliostats.

[0073] Step 5, using an implicit enumeration algorithm to solve the 0-1 integer linear programming model, obtain the target absorber that each heliostat is pointing to at that moment, thereby realizing dynamic adjustment of the target point of the photothermal mirror field.

[0074] The implicit enumeration algorithm is used to solve the 0-1 integer linear programming model and the optimal solution (x 1j ,x 2j ,…,x Mj ), that is, the target receiver that each heliostat points to at time T. Implicit enumeration algorithm is the most common and efficient algorithm for solving 0-1 integer linear programming models. It performs pruning by comparing branches and upper and lower bounds. It does not need to list all solutions for calculation, which greatly reduces the amount of calculation.

[0075] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for dynamically adjusting target points of a multi-heat absorption tower thermal mirror field, characterized in that: The steps include: Step 1: Taking the center of the photothermal mirror field as the origin, obtain the center elevation position coordinates of the heat absorber on each heat absorption tower; Step 2, based on the center elevation position coordinates of each heat absorber, calculate the X coordinate and Y coordinate of the target point of each heliostat on each heat absorber; Step 3, based on the center elevation position coordinates of each heat absorber and based on the energy maximization principle, determine the Z coordinate of the target point of each heliostat on each heat absorber; Step 4: Calculate the power of each heliostat at the corresponding target point on each absorber at a certain moment based on the ray tracing method, and establish a 0-1 integer linear programming model with maximizing the power of the photothermal mirror field as the objective function; Step 5, using an implicit enumeration algorithm to solve the 0-1 integer linear programming model, obtain the target absorber that each heliostat is pointing to at that moment, thereby realizing dynamic adjustment of the target point of the photothermal mirror field.

2. The method for dynamically adjusting the target point of a multi-heat absorption tower thermal mirror field according to claim 1 is characterized in that: Step 1 is as follows: Assume that there are J heat absorbing towers in the photothermal mirror field, each of which has a heat absorber on top, and the shape of heat absorber j is positive N j Prism, j = 1, 2, ... J, side length L j , high is S j ; The center elevation position coordinates of the heat absorber j are 3. The method for dynamically adjusting the target point of a multi-heat absorption tower thermal mirror field according to claim 2 is characterized in that: Step 2 is as follows: Assume that there are M heliostats in the solar thermal mirror field. For heliostat i, i = 1, 2, ... M, first calculate the radius length R of the circumscribed circle of the absorber j: j : Based on the principle of the closest distance, the X coordinate of the target point of heliostat i on the receiver j is obtained and Y coordinate Among them, the heliostat and the absorber are projected onto the XY plane, β ij It represents the angle between heliostat i and absorber j in the horizontal direction, and its calculation formula is as follows: in, and are the X and Y coordinates of heliostat i respectively.

4. The method for dynamically adjusting the target point of a multi-heat absorption tower thermal mirror field according to claim 2 is characterized in that: Step 3 is as follows: The horizontal distance between heliostat i and receiver j is r ij , the center elevation of the heat absorber j is The target point of heliostat i on the absorber j is the line A between the center of the spot and the heliostat ij The angle with the horizontal direction is θ, and the line between the lower edge of the spot and the heliostat is A ′ ij , connection A ij With line A ′ ij The angle between them is θ ′ , from the lower edge of the spot to the line A ij The distance between According to the relationship between the sides of the right triangle, the following equation is established: in, in, and are the X and Y coordinates of heliostat i respectively; Using stochastic gradient descent to find an approximate solution to a nonlinear equation Finally, the spot radius of heliostat i in the vertical direction is obtained Based on the principle of energy maximization, the spot radius The larger the beam spot, the more the target point should be at the center of the absorber. The smaller the value, the target points should be randomly distributed on the absorber panel, so the Z coordinate of the target point of heliostat i on absorber j is determined as follows: Among them, sgn(x) is the sign function. When x>0, sgn(x)=1, otherwise sgn(x)=-1, and rand(0,1) is the random number function, which generates a random number between 0 and 1.

5. The method for dynamically adjusting target points of a multi-heat absorption tower thermal mirror field according to claim 2 is characterized in that: Step 4 is as follows: Based on the ray tracing method, calculate the power p of the heliostat i at the corresponding target point on the absorber j at time T ij , let b ij Is whether heliostat i uses the corresponding target point on absorber j, if b ij = 0, indicating that heliostat i does not use the corresponding target point on absorber j; if b ij =1, indicating that heliostat i uses the corresponding target point on absorber j; the 0-1 integer linear programming model is established as follows: Where M is the total number of heliostats.

6. The method for dynamically adjusting the target point of a multi-heat absorption tower thermal mirror field according to claim 5 is characterized in that: Step 5 is as follows: Use the implicit enumeration algorithm to solve the 0-1 integer linear programming model and obtain the optimal solution (x 1j ,x 2j ,…,x Mj ), that is, the target receiver that each heliostat points to at time T.

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