Scheduling control method for heliostats of multi-tower one-machine photo-thermal mirror field

Abstract

The invention relates to the field of photo-thermal mirror field control, and discloses a heliostat scheduling control method for a multi-tower one-machine photo-thermal mirror field, which comprises the following steps of: dividing the multi-tower one-machine photo-thermal mirror field into a plurality of mirror field subgroups; dividing a target heat absorber for the mirror field according to the maximum projection radius; according to the projection power of each heliostat on the target heat absorber, calculating the maximum projection power of each heliostat field subgroup on the target heat absorber and a specified panel of the target heat absorber; generating a linear programming constraint matrix, and determining binary search parameters by using a binary search method to obtain a final constraint vector; and according to the linear programming constraint matrix and the final constraint vector, linear programming is operated to determine the power distribution proportion of the target heat absorber in each mirror field subgroup, and heliostats are distributed in the subgroups according to the power distribution proportion. According to the method, on the premise that the power requirement of each heat absorber panel is met, the photo-thermal efficiency of the whole field is maximized, the algorithm is simple, and energy flow scheduling of the multi-tower one-machine mirror field can be rapidly achieved.

Description

Technical Field

[0001] The present invention relates to the field of solar thermal mirror field control, and particularly to a method for scheduling and controlling heliostats in a multi-tower one-machine solar thermal mirror field. Background Art

[0002] As the core technical route in the field of solar thermal power generation, tower-type solar thermal power generation has become an important support for building a new power system with its high concentration ratio, large-capacity energy storage, and flexible peak shaving capabilities. However, the large-scale development of a single-tower mirror field faces multiple technical bottlenecks: when the distance between mirror towers exceeds 1.2 km, the optical efficiency of heliostats at the edge of the mirror field decreases significantly, and at the same time, the pointing accuracy is affected by factors such as atmospheric disturbance and mechanical error, further restricting the system performance.

[0003] To break through the above limitations, the multi-tower one-machine technology (especially the three-tower one-machine) has become a research hotspot. This technology integrates multiple solar receivers to share a set of generator sets and energy storage systems, forming an innovative architecture of "physically separate towers and system coupling", significantly reducing the investment costs of infrastructure such as molten salt circulation systems, steam generation devices, and workshops per unit power. The heliostats in the middle area of multiple towers can flexibly serve any solar receiver, improving the overall optical efficiency of the mirror field, while reducing the number of heliostats and the floor area.

[0004] Although the multi-tower one-machine has obvious advantages, the sharing of heliostats also raises higher requirements for the control system. If the optical efficiency of the heliostat is simply used as the scheduling basis, it may cause overheating or freezing of the salt in the solar receiver due to excessive or insufficient projection of the shared heliostats. How to effectively schedule the heliostats and achieve a balance between maximizing efficiency and safe operation has become a rather difficult problem. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a method for scheduling and controlling heliostats in a multi-tower one-machine solar thermal mirror field, which maximizes the overall solar thermal efficiency under the premise of meeting the power demand of each solar receiver panel. The algorithm is simple and can quickly realize the energy flow scheduling of the multi-tower one-machine mirror field.

[0006] To achieve the above object, the technical solution of the present invention is as follows: A method for scheduling and controlling heliostats in a multi-tower one-machine solar thermal mirror field, comprising the following steps: Step 1, dividing the multi-tower one-machine mirror field into several mirror field sub-groups according to the angles corresponding to the solar receiver panels; Step 2, dividing the target solar receiver for the mirror field according to the maximum projection radius; Step 3, calculating the projection power of each heliostat on the target solar receiver; Step 4: Calculate the maximum projection power of each mirror field subgroup on the target receiver and on the specified panel of the target receiver according to the projection power of each heliostat on the target receiver. Step 5: Generate a linear programming constraint matrix based on the calculated maximum projection power. By setting the initial constraint vector and using the binary search method to determine the binary search parameter, obtain the final constraint vector. Step 6: According to the linear programming constraint matrix and the final constraint vector, run the linear programming to determine the power distribution ratio of the target receiver in each mirror field subgroup, and distribute the heliostats within the subgroup according to the power distribution ratio.

[0007] In the above solution, in Step 1, the multi-tower one-machine mirror field contains three sub-mirror fields. For each sub-mirror field, the heliostats are arranged in a circular pattern around the receiver in that sub-mirror field, and the heliostats in adjacent rows are staggered, and adjacent sub-mirror fields overlap; each receiver has 12 panels, corresponding to 12 angular intervals, and the entire mirror field is divided into 36 sub-groups.

[0008] In the above solution, in Step 2, with each receiver as the center, draw a circle using the radius and set the target point of the heliostats inside the circle to that receiver. Each heliostat has at most 3 target receivers; among them, is greater than the radius of each mirror field and less than the farthest focusing distance of the heliostat.

[0009] In the above solution, in Step 3, the projection power of each heliostat on the target receiver is calculated as follows: ; Among them, is the projection power of the i-th heliostat on the target receiver , is the direct normal solar radiation, is the efficiency of the i-th heliostat on the target receiver and Area is the reflection area of the heliostat.

[0010] In the above solution, in Step 4, the formula for calculating the maximum projection power of the m-th mirror field subgroup on the target receiver is as follows: ; ; Among them, is the number of heliostats in the m-th mirror field subgroup, , is the projection power of the i-th heliostat on the target receiver ; The m-th mirror field subgroup on the target receiver on the panel the maximum projection power The calculation formula is as follows: ; Wherein, is the maximum projection power of the i-th heliostat on the target receiver on the panel When the i-th heliostat does not project onto the panel , .

[0011] In the above solution, in step 5, the projection power ratio of the m-th mirror field subgroup on the target receiver shall not exceed , and its mathematical expression is: ; Wherein, represents the upper limit of the projection power ratio of the m-th mirror field subgroup on the target receiver ; R is the projection power coefficient of each subgroup-target point pair; The total projection power ratio of the m-th mirror field subgroup shall not exceed , and its mathematical expression is: ; Wherein, represents the upper limit of the total projection power ratio of the m-th mirror field subgroup ; Thus, the generated linear programming constraint matrix is as follows: .

[0012] In the above solution, in step 5, the set initial constraint vector is as follows: ; Wherein, represents the maximum allowable power of the k-th panel, represents the maximum heat absorption power of the receiver.

[0013] In the above solution, in step 5, the obtained final constraint vector is as follows: ; Wherein, represents the maximum heat absorption power of the receiver, represents the upper limit of the projection power ratio of the m-th mirror field subgroup on the target receiver , Indicates the m-th mirror field subgroup Upper limit of the total projection power ratio

[0014] In the above solution, in step 6, the method for allocating heliostats within the subgroup according to the power distribution ratio is as follows: For the m-th mirror field subgroup , the output power distribution of the heliostats follows the following process: (1) Single-round allocation: The projection power of the i-th heliostat on the target receiver is sorted from largest to smallest, and the power ranked first is taken. Its corresponding target receiver is , and this power is accumulated to ; at the same time, mark that the i-th heliostat has been used, and set its projection power on other target receivers to 0; (2) Loop and termination: Repeat the above single-round allocation step. When the accumulated power of a certain target receiver reaches its required power , for all heliostats that have not been accumulated to this , reset their projection powers on to 0, and no longer participate in the power allocation of this target receiver. Give priority to ensuring the power allocation results of the targets that have met the requirements, and continue to perform allocation for other unmet target receivers until the allocation is completed according to the needs of each target. (3) In the above solution, the calculation formula for the required power

[0015] of the target receiver is as follows: ; ; Among them, is the maximum projection power of the m-th mirror field subgroup on the target receiver , and is the projection power coefficient of the m-th mirror field subgroup S m on the target receiver Tn.

[0016] Through the above technical solution, a method for scheduling and controlling heliostats in a multi-tower and one-machine solar thermal mirror field provided by the present invention has the following beneficial effects: The present invention divides the subgroup-target receiver of the multi-tower and one-machine mirror field; through a linear programming algorithm applicable to multi-tower and one-machine, and introduces and constraints in the linear programming algorithm, as well as adjustment methods for these two parameters; under the condition of ensuring safe operation, the maximum heat collection efficiency of the entire solar thermal system can be achieved. Description of the drawings

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art.

[0018] Figure 1 Schematic flow chart of the scheduling control method for heliostats in a multi-tower-one-machine solar thermal mirror field disclosed in the embodiments of the present invention; Figure 2 Schematic diagram of the mirror field layout for three towers and one machine; Figure 3 Schematic diagram of grouping the mirror field according to the absorber panel; Figure 4 Schematic diagram of dividing the target absorber; (a) is the mirror field area with the target point T1, (b) is the mirror field area with the target point T2, and (c) is the mirror field area with the target point T3.

[0019] In the figure, 1 is the sub-mirror field; 2 is the absorber; 3 is the generator set and the energy storage system. Specific implementation manners

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention.

[0021] The present invention provides a scheduling control method for heliostats in a multi-tower-one-machine solar thermal mirror field, as Figure 1 shown, including the following steps: Step 1, divide the multi-tower-one-machine mirror field into several mirror field subgroups according to the angles corresponding to the absorber panels.

[0022] In this embodiment, taking three towers and one machine as an example, in the northern hemisphere, the typical layout of the three-tower-one-machine mirror field is as Figure 2 shown. The mirror field contains three sub-mirror fields 1 of the same scale. The three sub-mirror fields 1 share a set of generator sets and energy storage systems 3. Two of them are on the north side and one is on the south side, arranged in an inverted product shape. For each sub-mirror field, the heliostats are arranged in a circle around the absorber 2 (T1, T2, T3) in the sub-mirror field, and the heliostats in adjacent rows are staggered to reduce the occlusion loss, and adjacent sub-mirror fields overlap. As Figure 3 shown, each absorber has 12 panels, corresponding to 12 angular intervals, and the entire mirror field is divided into 36 subgroups S1-S 36 .

[0023] Step 2, divide the target absorber 2 for the mirror field according to the maximum projection radius.

[0024] As Figure 4 shown, with each absorber 2 as the center, using the radius Draw a circle and set the target point of the heliostat inside the circle as the receiver. Each heliostat has at most 3 target receivers. Among them, It is greater than the radius of each mirror field and less than the farthest focusing distance of the heliostat, with a typical value of 1200 - 1600 m.

[0025] Each heliostat has only one target point on each receiver. The specific positioning of the target point is determined according to the energy flux distribution, and the specific optimization and adjustment method of the target point position are not within the protection scope of the present invention.

[0026] Divide the target point set according to the receivers. The target points located on the same receiver are classified into one target point set.

[0027] Step 3: Calculate the projection power of each heliostat on the target receiver.

[0028] The projection power of each heliostat on the target receiver is calculated as follows: ; Among them, is the projection power of the i rd heliostat on the target receiver , is the direct normal solar radiation (a real-time measurement value), is the efficiency of the i-th heliostat on the target receiver , and Area is the reflection area of the heliostat.

[0029] Step 4: Calculate the maximum projection power of each mirror field subgroup on the target receiver and on the specified panel of the target receiver according to the projection power of each heliostat on the target receiver.

[0030] In this embodiment, the basic unit to be adjusted by linear programming is the subgroup - target receiver pair, which represents the pairing of the mirror field subgroup and the receiver. For a scenario where the mirror field is divided into 36 subgroups and there are 3 receivers, there are a total of 108 pairing combinations.

[0031] The m-th mirror field subgroup on the target receiver The maximum projection power is calculated as follows: ; Among them, is the number of heliostats in the m th mirror field subgroup, , is the i th heliostat on the target receiver The projection power on it; when the heliostat in the subgroup does not have a target point on the absorber n, the projection power p is set to 0.

[0032] The m th mirror field subgroup on the target absorber panel maximum projection power is calculated as follows: ; where is the i th heliostat's maximum projection power on the target absorber panel ; when the i th heliostat does not project onto the panel , .

[0033] Step 5: Generate a linear programming constraint matrix based on the calculated maximum projection power. By setting an initial constraint vector and using the binary search method to determine the binary search parameters, the final constraint vector is obtained.

[0034] Optimize the power distribution ratio (R) of each {subgroup - target absorber} through linear programming (LP), and use binary search to adjust the parameters.

[0035] Objective: Maximize the total power, that is , where: R: A w-dimensional column vector, the unknown variable to be solved, representing the power coefficient (between 0 and 1) of each subgroup - target absorber pair.

[0036] O: A w-dimensional row vector, containing the maximum power of each subgroup - target point pair at full power.

[0037] The key lies in the solution of R. In linear programming, the vector R is determined by solving the constraint equation . Where M is the constraint coefficient matrix, which defines the linear relationship between decision variables, a matrix of size [g, w], containing the coefficients of each variable in the constraint conditions, where w is the number of {subgroup - target absorber}, and the size of g depends on the constraint conditions, which will be described in detail below. B is the constraint right - hand side constant vector, a g-dimensional column vector.

[0038] Constraint conditions ( ): (1) Absorber face screen power limit: The power projected onto each face screen does not exceed its upper limit.

[0039] (2) Subgroup - Target Point Upper Limit: Each R element ≤ β (β is the binary search parameter).

[0040] (3) Subgroup Total Power Upper Limit: The sum of R for each subgroup ≤ α (α is the binary search parameter).

[0041] (4) Total Power Limit: Total power ≤ Desired power T.

[0042] Constraint (1) The total power of each face does not exceed its upper limit The size of the M matrix corresponding to Constraint (1) is [k, w], where the rows represent the power delivered by each {Heliostat Subgroup - Target Receiver} pair corresponding to each panel, and the number w = n * m, n is the number of heliostat subgroups (example is 36), m is the number of target receivers (example is 3); the columns represent the power of each subgroup - target point on all k panels (example is 36).

[0043] The constraint constant vector on the right - hand side is a k - dimensional column vector, representing the power limit delivered to the panel, which is an inherent property of the receiver and is determined during the design; ; Constraint (2) Output Upper Limit of Each {Subgroup - Target Receiver} Each R element ≤ β (β is the binary search parameter).

[0044] The maximum available fraction of each {Subgroup - Target Receiver} is 100%. This item must be added to constrain each element of R to be less than or equal to 1. As part of the binary search, each target point will be limited within β, where β is between 0 and 1. The search strategy is defined as follows. This will create the next part in M and B. In M, it is just an identity matrix spanning the width of the matrix. In B, it is a list of β values, the m th mirror field subgroup The proportion of the projected power on the target receiver cannot exceed , and its mathematical expression is: ; Among them, represents the upper limit of the proportion of the projected power of the m th mirror field subgroup on the target receiver ; R is the projection power coefficient for each subgroup - target point pair; the right - hand side matrix is a [w, w] matrix, and w is the number of {Subgroup - Target Receiver} (example is 108).

[0045] Constraint (3) Subgroup Total Power Output Upper Limit The sum of R for each subgroup ≤ α (α is the binary search parameter).

[0046] In addition to the limitation on each subgroup's target point pair, each subgroup is physically limited between 0% and 100% of the total power of all target points. Then, these subgroups are additionally limited to be less than α, which is another parameter for binary search between 0 and 1, as described in the next section. Matrix M generates unit matrices stacked side by side, one for each target point. B consists entirely of α values. The m-th mirror field subgroup The total projected power ratio cannot exceed , and its mathematical expression is: ; where represents the upper limit of the total projected power ratio of the m-th mirror field subgroup ; the right matrix is a matrix of [m, w], where m is the number of subgroups (example is 36), and w is the number of {subgroup - target absorber} (example is 108).

[0047] Constraint (4) Total power limit Total power ≤ desired power T ; where the right side is a vector of [1, w], and w is the number of {subgroup - target absorber} (example is 108).

[0048] Thus, the generated linear programming constraint matrix is as follows: .

[0049] The set initial constraint vector is as follows: ; where represents the maximum allowable power of the k-th panel, represents the maximum heat absorption power of the absorber.

[0050] Binary search determines and

[0051] In the above integrated M matrix, there are two undetermined constraint parameters and , and binary search is used to determine these two parameters: β value calculation: The default value is 1. To adjust the maximum power ratio for each aiming point, starting from the last aiming point, binary search is performed sequentially to find the minimum β that does not limit the total power.

[0052] α value calculation: The default value is 1. Perform binary search in sequence, adjust the maximum power ratio of each subgroup, and find the minimum α that does not limit the total power.

[0053] Linear programming determines R After determining and run linear programming to determine R, that is, the power coefficient of each subgroup - target receiver pair.

[0054] The final constraint vector obtained is as follows: ; Among them, represents the maximum heat absorption power of the receiver, represents the m - th mirror field subgroup at the target receiver the upper limit of the projection power ratio, represents the m - th mirror field subgroup the upper limit of the total projection power ratio.

[0055] Step 6: According to the linear programming constraint matrix and the final constraint vector, run linear programming to determine the power distribution ratio of the target receivers in each mirror field subgroup, and distribute the heliostats within the subgroup according to the power distribution ratio.

[0056] The specific method is as follows: For the m - th mirror field subgroup , the power output distribution of the heliostats follows the following process: (1) Single - round distribution: Sort the projection power of the i - th heliostat in on the target receiver from large to small, take the power ranked first, and its corresponding target receiver is , add this power to ; at the same time, mark that the i - th heliostat has been used, and set its projection power on other target receivers to 0; (2) Loop and termination: Repeat the above single - round distribution step. When the accumulated power of a certain target receiver reaches its required power , for all the heliostats that have not been accumulated to this , reset their projection power on to 0, and they will no longer participate in the power distribution of this target receiver. Give priority to ensuring the power distribution results of the target receivers that have met the requirements, and continue to perform distribution for other unmet target receivers until the distribution for each target is completed as required.

[0057] Specifically, the required power of the target receiver The calculation formula is as follows: ; Wherein, is the maximum projection power of the m-th mirror field subgroup on the target receiver , and is the projection power coefficient of the m-th mirror field subgroup S m on the target receiver Tn.

[0058] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can 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 is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A scheduling control method for heliostats in a multi-tower one-machine solar thermal mirror field, characterized in that It includes the following steps: Step 1: Divide the multi-tower one-machine mirror field into several mirror field subgroups according to the angles corresponding to the heat absorber surface screens; Step 2: Divide the target heat absorber for the mirror field according to the maximum projection radius; Step 3: Calculate the projection power of each heliostat on the target heat absorber; Step 4: According to the projection power of each heliostat on the target heat absorber, calculate the maximum projection power of each mirror field subgroup on the target heat absorber and on the specified panel of the target heat absorber; Step 5: Generate a linear programming constraint matrix according to the calculated maximum projection power. By setting the initial constraint vector and using the binary search method to determine the binary search parameter, obtain the final constraint vector; Step 6: According to the linear programming constraint matrix and the final constraint vector, run the linear programming to determine the power distribution ratio of the target heat absorber in each mirror field subgroup, and distribute the heliostats within the subgroup according to the power distribution ratio.

2. The scheduling control method of heliostats for a multi-tower one-machine solar thermal mirror field according to claim 1, wherein In Step 1, there are three sub-mirror fields in the multi-tower one-machine mirror field. For each sub-mirror field, the heliostats are arranged in a circular pattern around the heat absorber in the sub-mirror field, and the heliostats in adjacent rows are staggered, and there is an overlap between adjacent sub-mirror fields; each heat absorber has 12 panels corresponding to 12 angular intervals, and the entire mirror field is divided into 36 subgroups.

3. The scheduling control method for heliostats in a multi-tower one-machine solar thermal mirror field according to claim 1, wherein, In Step 2, with each receiver as the center, using a radius draw a circle, and set the target points of the heliostats within the circle to this receiver. Each heliostat has at most 3 target receivers. Among them, is greater than the radius of each mirror field and less than the farthest focusing distance of the heliostat.

4. The scheduling control method for heliostats of a multi-tower one-machine solar thermal mirror field according to claim 1, characterized in that In Step 3, the projection power of each heliostat on the target heat absorber is calculated as follows: ； Among them, is the projection power of the i-th heliostat on the target receiver , is the direct normal solar irradiance is the efficiency of the i-th heliostat on the target receiver , and Area is the reflective area of the heliostat.

5. The scheduling control method of the heliostat in a multi-tower one-machine solar thermal mirror field according to claim 1, characterized in that In step 4, the m-th mirror field subgroup at the target receiver the maximum projection power is calculated as follows: ； Among them, is the number of heliostats in the m-th mirror field subgroup, , is the projection power of the i-th heliostat on the target receiver ; The m-th mirror field subgroup On the target receiver Panel The maximum projection power The calculation formula is as follows: ； Among them, is the maximum projection power of the i-th heliostat on the target receiver panel When the i-th heliostat does not project onto the panel then .

6. The scheduling control method of the heliostat for a multi-tower one-machine solar thermal mirror field according to claim 1, wherein In step 5, the m-th mirror field subgroup on the target receiver the projection power ratio cannot exceed , and its mathematical expression is: ； Among them, represents the m-th mirror field subgroup at the target receiver upper limit of the projection power ratio; R is the projection power coefficient for each subgroup-target point pair; The m-th mirror field subgroup The total projection power ratio cannot exceed , and its mathematical expression is: ； Among them, represents the m-th mirror field subgroup upper limit of the total projection power ratio; Thus, the generated linear programming constraint matrix is as follows: 。 7. The scheduling control method for heliostats of a multi-tower one-machine solar thermal mirror field according to claim 1, wherein, In Step 5, the set initial constraint vector is as follows: ； Among them, represents the maximum allowable power of the k-th panel, represents the maximum heat absorption power of the heat absorber.

8. A heliostat scheduling control method for a multi-tower one-machine solar thermal mirror field according to claim 1, characterized in that In Step 5, the obtained final constraint vector is as follows: ； Among them, represents the maximum heat absorption power of the heat absorber, represents the m-th mirror field subgroup at the target heat absorber upper limit of the projection power ratio, represents the m-th mirror field subgroup upper limit of the total projection power ratio.

9. The scheduling control method for heliostats in a multi-tower one-machine solar thermal mirror field according to claim 1, wherein In Step 6, the method for distributing the heliostats within the subgroup according to the power distribution ratio is as follows: For the m-th mirror field subgroup , the heliostat output power distribution follows the following process: (1)Single-wheel allocation: The projection power of the i-th heliostat in onto the target receiver is sorted from largest to smallest, and the power ranked first is taken , and its corresponding target receiver is , and this power is accumulated into ; At the same time, mark that the i-th heliostat has been used, and set its projection power on other target receivers to 0; (2) Loop and termination: Repeat the above single-round allocation step. When the cumulative power of a certain target receiver reaches its required power at this time, for all heliostats that have not been accumulated to this , reset their projected power on to 0, and no longer participate in the power allocation of this target receiver. Give priority to ensuring the power allocation result of the target that has met the requirements, and continue to perform allocation for other target receivers that have not been met until the allocation for each target is completed according to the demand.

10. The method for scheduling and controlling heliostats in a multi-tower one-machine solar thermal mirror field according to claim 9, wherein Target absorber required power The calculation formula is as follows: ； Among them, is the m-th mirror field subgroup on the target receiver the maximum projection power, is the projection power coefficient of the m-th mirror field subgroup S m on the target receiver Tn.

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