A heliostat scheduling control method for a multi-tower single-unit solar thermal mirror field

Abstract

The present invention relates to the field of solar thermal mirror field control and discloses a heliostat scheduling control method for a multi-tower, single-machine solar thermal mirror field. The method comprises dividing the multi-tower, single-machine mirror field into a plurality of mirror field subgroups; dividing the mirror field into target absorbers according to the maximum projection radius; calculating the maximum projected power of each mirror field subgroup on the target absorber and on a designated panel of the target absorber based on the projected power of each heliostat on the target absorber; generating a linear programming constraint matrix, determining binary search parameters using a binary search method to obtain a final constraint vector; and running a linear programming operation based on the linear programming constraint matrix and the final constraint vector to determine the power allocation ratio of the target absorber in each mirror field subgroup, and allocating heliostats within the subgroup according to the power allocation ratio. The method disclosed in the present invention maximizes the solar thermal efficiency of the entire field while meeting the power requirements of each absorber panel. The algorithm is simple and can quickly implement energy flow scheduling for the multi-tower, single-machine mirror field.

Description

Technical Field

[0001] The present invention relates to the field of photothermal mirror field control, and in particular to a heliostat scheduling control method for a multi-tower single-machine photothermal mirror field. Background Art

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

[0003] To overcome these limitations, multi-tower, single-unit technology (particularly three-tower, single-unit) has become a research hotspot. This technology integrates multiple heat-absorbing towers to share a single generator set and heat storage system, creating an innovative "physically separate towers, coupled systems" architecture. This significantly reduces the investment cost per unit of power, including the molten salt circulation system, steam generation equipment, and powerhouse infrastructure. Heliostats in the center of the multi-tower system can flexibly serve any of the heat-absorbing towers, improving the overall optical efficiency of the field while reducing the number of heliostats and the floor space required.

[0004] While multiple towers per unit offer significant advantages, the shared use of heliostats also raises the bar for control systems. If scheduling is based solely on heliostat optical efficiency, over- or under-projection from shared heliostats can lead to receiver overheating or salt freezing. Effectively scheduling heliostats and striking a balance between maximum efficiency and safe operation presents a thorny challenge. Summary of the Invention

[0005] To address the above technical problems, the present invention provides a heliostat scheduling and control method for a multi-tower, single-machine solar thermal mirror field. This method maximizes the solar thermal efficiency of the entire field while meeting the power requirements of each absorber panel. The algorithm is simple and can quickly implement energy flow scheduling for the multi-tower, single-machine mirror field.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A heliostat scheduling control method for a multi-tower, single-machine solar thermal mirror field comprises the following steps:

[0008] Step 1: Divide the multi-tower single-machine mirror field into several mirror field subgroups according to the angles corresponding to the absorber faceplates;

[0009] Step 2, dividing the target absorber into the mirror field according to the maximum projection radius;

[0010] Step 3, calculate the projected power of each heliostat on the target absorber;

[0011] Step 4, calculating the maximum projected power of each heliostat subgroup on the target absorber and on a designated panel of the target absorber based on the projected power of each heliostat on the target absorber;

[0012] Step 5: Generate a linear programming constraint matrix based on the calculated maximum projection power, set an initial constraint vector, use a binary search method to determine the binary search parameters, and obtain the final constraint vector;

[0013] Step 6: Based on the linear programming constraint matrix and the final constraint vector, run linear programming to determine the power allocation ratio of the target receiver in each mirror field subgroup, and allocate heliostats within the subgroup according to the power allocation ratio.

[0014] In the above scheme, in step 1, the multi-tower single-machine mirror field contains three sub-mirror fields. For each sub-mirror field, heliostats are arranged in a circular pattern around the absorber in that sub-mirror field, and adjacent rows of heliostats are staggered, with adjacent sub-mirror fields overlapping. Each absorber has 12 panels, corresponding to 12 angular intervals, dividing the entire mirror field into 36 sub-groups.

[0015] In the above scheme, in step 2, take each heat absorber as the center of the circle and use the radius Draw a circle and set the target point of the heliostat within the circle to the heat sink. Each heliostat has a maximum of 3 target heat sinks. It is larger than the radius of each mirror field and smaller than the maximum focusing distance of the heliostat.

[0016] In the above scheme, in step 3, the projected power of each heliostat on the target receiver is calculated as follows:

[0017] ;

[0018] in, is the number of heliostats at the target receiver The projected power on is the direct normal radiation from the sun, is the number of heliostats at the target receiver Area is the reflection area of ​​the heliostat.

[0019] In the above scheme, in step 4, the mth mirror field subgroup On target heat sink Maximum projected power on The calculation formula is as follows:

[0020] ;

[0021] in, is the number of heliostats in the mth mirror field subgroup, , is the number of heliostats at the target receiver Projected power on

[0022] The mth mirror field subgroup On target heat sink Panel Maximum projected power on The calculation formula is as follows:

[0023] ;

[0024] in, is the number of heliostats at the target receiver Panel The maximum projected power on the panel is when the i-th heliostat does not project onto the panel On time, .

[0025] In the above scheme, in step 5, the mth mirror field subgroup On target heat sink The projected power ratio on , its mathematical expression is:

[0026] ;

[0027] in, Indicates the mth mirror field subgroup On target heat sink The upper limit of the projection power ratio on the target point; R is the projection power coefficient of each subgroup-target point pair;

[0028] The mth mirror field subgroup The total projected power ratio cannot exceed , its mathematical expression is:

[0029] ;

[0030] in, Indicates the mth mirror field subgroup Upper limit of total projected power ratio;

[0031] Thus, the generated linear programming constraint matrix is ​​as follows:

[0032] .

[0033] In the above scheme, in step 5, the initial constraint vector is set as follows:

[0034] ;

[0035] in, represents the maximum allowable power of the kth panel, Indicates the maximum heat absorption power of the absorber.

[0036] In the above solution, in step 5, the final constraint vector obtained is as follows:

[0037] ;

[0038] in, Indicates the maximum heat absorption power of the absorber, Indicates the mth mirror field subgroup On target heat sink The upper limit of the projected power ratio, Indicates the mth mirror field subgroup The upper limit of the total projected power ratio.

[0039] In the above scheme, in step 6, the method for allocating heliostats within the subgroup according to the power allocation ratio is as follows:

[0040] For the mth mirror field subgroup , the heliostat output power distribution follows the following process:

[0041] (1) Single round allocation: The i-th heliostat is at the target receiver Projected power on Sort by power from largest to smallest and take the one that ranks first , and its corresponding target heat sink is , and add this power to At the same time, the i-th heliostat is marked as used, and its projected power on other target absorbers is set to 0;

[0042] (2) Cycle and termination: Repeat the above single round allocation steps. When a target heat sink The accumulated power reaches its required power When the All heliostats, place them in The projected power on is reset to 0, and it no longer participates in the power allocation of the target heat sink. It gives priority to ensuring the power allocation results of the target that has met the demand, and continues to allocate to other target heat sinks that have not met the demand until the allocation of each target is completed as needed.

[0043] In the above scheme, the target heat absorber Required power The calculation formula is as follows:

[0044] ;

[0045] in, is the mth mirror field subgroup On target heat sink The maximum projected power on is the mth mirror field subgroup S m Projected power coefficient at the target receiver Tn.

[0046] Through the above technical solution, the heliostat scheduling control method for a multi-tower single-machine solar thermal mirror field provided by the present invention has the following beneficial effects:

[0047] The present invention divides the subgroup-target absorber of the multi-tower one machine mirror field; uses a linear programming algorithm suitable for multi-tower one machine and introduces and Constraints, as well as the adjustment methods of these two parameters; under the conditions of meeting safe operation, the thermal collection efficiency of the entire solar thermal system can be maximized. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for describing the embodiments or the prior art.

[0049] Figure 1 This is a flow chart of a heliostat scheduling control method for a multi-tower, single-machine solar thermal mirror field disclosed in an embodiment of the present invention;

[0050] Figure 2 This is a schematic diagram of the layout of the three towers and one machine mirror field;

[0051] Figure 3 A schematic diagram showing how the mirror field is grouped according to the absorber panels;

[0052] Figure 4 Schematic diagram of the division of the target heat 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.

[0053] In the figure, 1. Sub-mirror field; 2. Receiver; 3. Generator set and heat storage system. DETAILED DESCRIPTION

[0054] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0055] The present invention provides a heliostat scheduling control method for a multi-tower single-machine solar thermal mirror field, such as Figure 1 As shown, the following steps are included:

[0056] Step 1: Divide the multi-tower single-machine mirror field into several mirror field subgroups according to the angles corresponding to the absorber faceplates.

[0057] This embodiment takes three towers and one machine as an example. In the northern hemisphere, the typical layout of the three towers and one machine mirror field is as follows: Figure 2 As shown, the mirror field contains three sub-mirror fields 1 of the same size. The three sub-mirror fields 1 share a set of generator sets and heat storage systems 3. Two of them are located on the north side and one on the south side, arranged in an inverted triangular shape. For each sub-mirror field, heliostats are arranged in a circular pattern around the heat absorber 2 (T1, T2, T3) in the sub-mirror field. Adjacent rows of heliostats are staggered to reduce shading losses. Adjacent sub-mirror fields overlap. Figure 3 As shown, each absorber has 12 panels, corresponding to 12 angle intervals, dividing the entire mirror field into 36 subgroups S1-S 36 .

[0058] Step 2: Divide the target heat absorber 2 into the mirror field according to the maximum projection radius.

[0059] like Figure 4 As shown, with each heat absorber 2 as the center, using the radius Draw a circle and set the target point of the heliostat within the circle to the heat sink. Each heliostat has a maximum of 3 target heat sinks. It is larger than the radius of each mirror field and smaller than the maximum focusing distance of the heliostat. The typical value is 1200~1600m.

[0060] Each heliostat has only one target point on each heat absorber. The specific positioning of the target point is determined based on the energy flow distribution. The specific optimization and adjustment method of the target point position is not within the scope of protection of the present invention.

[0061] The target point sets are divided according to the heat absorber, and the target points located on the same heat absorber are classified into one target point set.

[0062] Step 3: Calculate the projected power of each heliostat on the target receiver.

[0063] The projected power of each heliostat on the target receiver is calculated as follows:

[0064] ;

[0065] in, For the i Heliostats at the target receiver The projected power on is the direct normal solar radiation (real-time measurement value), is the number of heliostats at the target receiver Area is the reflection area of ​​the heliostat.

[0066] Step 4: Calculate the maximum projected power of each heliostat subgroup on the target absorber and on a designated panel of the target absorber based on the projected power of each heliostat on the target absorber.

[0067] In this embodiment, the basic unit to be adjusted by the linear programming is the subgroup-target absorber pair, which represents the pairing of the mirror field subgroup and the absorber. For a scenario where the mirror field is divided into 36 subgroups and has 3 absorbers, there are a total of 108 pairing combinations.

[0068] The mth mirror field subgroup On target heat sink Maximum projected power on The calculation formula is as follows:

[0069] ;

[0070] in, For the m The number of heliostats in each field subgroup, , For the i Heliostats at the target receiver When the heliostat in the subgroup does not have a target point on the absorber n, the projected power p is set to 0.

[0071] No. m mirror field subgroup On target heat sink Panel Maximum projected power on The calculation formula is as follows:

[0072] ;

[0073] in, For the i Heliostats at the target receiver Panel The maximum projected power on i The heliostats do not project onto the panel On time, .

[0074] Step 5: Generate a linear programming constraint matrix based on the calculated maximum projection power, set an initial constraint vector, and use a binary search method to determine the binary search parameters to obtain the final constraint vector.

[0075] The power allocation ratio (R) of each {subgroup-target sink} is optimized by linear programming (LP), and the parameters are adjusted using binary search.

[0076] Goal: Maximize total power, i.e. ,in:

[0077] R: w-dimensional column vector, the unknown variable to be solved, representing the power coefficient of each subgroup-target absorber pair (between 0 and 1).

[0078] O: w-dimensional row vector containing the maximum power of each subgroup-target point pair at full power.

[0079] The key point is to solve R. In linear programming, by solving the constraint equation Determine the vector R. M is the constraint coefficient matrix, defining the linear relationships between the decision variables. A matrix of size [g, w] contains the coefficients for each variable in the constraint, where w is the number of {subgroups - target sinks} and the size of g depends on the constraints, as described in detail below. B is the right-hand side constant vector of the constraints, a g-dimensional column vector.

[0080] Constraints ( ):

[0081] (1) Receiver panel power limit: The power projected onto each panel shall not exceed its upper limit.

[0082] (2) Subgroup-target point upper limit: each R element ≤ β (β is the binary search parameter).

[0083] (3) Upper limit of total power of subgroups: the sum of R of each subgroup ≤ α (α is the binary search parameter).

[0084] (4) Total power limit: total power ≤ expected power T.

[0085] Constraint (1) The total power of each surface does not exceed its upper limit

[0086] The size of the M matrix corresponding to constraint (1) is [k, w], where the rows represent the power delivered by the {heliostat group-target receiver} pair corresponding to each panel, and the number w=n*m, where n is the number of heliostat groups (36 in this example) and m is the number of target receivers (3 in this example); the columns are the power delivered by each subgroup-target point on all k panels (36 in this example).

[0087] The constraint constant vector on the right side of the equation is a k-dimensional column vector, which represents the power limit delivered to the panel. It is an inherent property of the absorber and is determined during design;

[0088] ;

[0089] Constraint (2) Each {subgroup-target heat sink} output upper limit

[0090] Every element of R ≤ β (β is the binary search parameter).

[0091] The maximum available fraction for each {subgroup - target sink} is 100%, and this 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 constrained to be within β, which is between 0 and 1. The search strategy is defined as follows. This will create the next section 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 first m mirror field subgroup On target heat sink The projected power ratio on , its mathematical expression is:

[0092] ;

[0093] in, Indicates the m mirror field subgroup On target heat sink R is the projected power coefficient of each subgroup-target point pair; the right-hand matrix is ​​a [w,w] matrix, where w is the number of {subgroup-target heat sinks} (108 in the example).

[0094] Constraint (3) Upper limit of total power output of subgroup

[0095] The sum of R in each subgroup is ≤ α (α is the binary search parameter).

[0096] In addition to the constraints on each subgroup's target point pairs, each subgroup is physically constrained to be between 0% and 100% of the total power across all target points. These subgroups are then additionally constrained to be less than α, another parameter that is binary searched between 0 and 1, as described in the next section. The matrix M generates identity matrices stacked side by side, one for each target point. B consists entirely of the α values. The total projected power ratio cannot exceed , its mathematical expression is:

[0097] ;

[0098] in, Indicates the mth mirror field subgroup The upper limit of the total projected power ratio; the matrix on the right is a [m,w] matrix, where m is the number of subgroups (36 in the example), and w is the number of {subgroups - target heat sinks} (108 in the example).

[0099] Constraint (4) Total power limit

[0100] Total power ≤ expected power T

[0101] ;

[0102] The right side is a vector of [1,w], where w is the number of {subgroup-target heat sinks} (108 in this example).

[0103] Thus, the generated linear programming constraint matrix is ​​as follows:

[0104] .

[0105] The initial constraint vector is set as follows:

[0106] ;

[0107] in, represents the maximum allowable power of the kth panel, Indicates the maximum heat absorption power of the absorber.

[0108] Binary search to determine and

[0109] In the above integrated M matrix, there are two undetermined constraint parameters and , use binary search to determine these two parameters:

[0110] β value calculation:

[0111] The default value is 1, which adjusts the maximum power ratio for each aiming point. Starting from the last aiming point, a binary search is performed sequentially to find the minimum β that does not limit the total power.

[0112] Calculation of α value:

[0113] The default value is 1, and a binary search is performed in sequence to adjust the maximum power ratio of each subgroup to find the minimum α that does not limit the total power.

[0114] Linear programming to determine R

[0115] In making sure and Finally, a linear programming is run to determine R, the power coefficient of each subgroup-target sink pair.

[0116] The final constraint vector obtained is as follows:

[0117] ;

[0118] in, Indicates the maximum heat absorption power of the absorber, Indicates the mth mirror field subgroup On target heat sink The upper limit of the projected power ratio, Indicates the mth mirror field subgroup The upper limit of the total projected power ratio.

[0119] Step 6: Based on the linear programming constraint matrix and the final constraint vector, run linear programming to determine the power allocation ratio of the target receiver in each mirror field subgroup, and allocate heliostats within the subgroup according to the power allocation ratio.

[0120] The specific method is as follows:

[0121] For the mth mirror field subgroup , the heliostat output power distribution follows the following process:

[0122] (1) Single round allocation: The i-th heliostat is at the target receiver Projected power on Sort by power from largest to smallest and take the one that ranks first , and its corresponding target heat sink is , and add this power to At the same time, the i-th heliostat is marked as used, and its projected power on other target absorbers is set to 0;

[0123] (2) Cycle and termination: Repeat the above single round allocation steps. When a target heat sink The accumulated power reaches its required power When the All heliostats, place them in The projected power on is reset to 0, and it no longer participates in the power allocation of the target heat sink. It gives priority to ensuring the power allocation results of the target that has met the demand, and continues to allocate to other target heat sinks that have not met the demand until the allocation of each target is completed as needed.

[0124] Specifically, the target heat sink Required power The calculation formula is as follows:

[0125] ;

[0126] in, is the mth mirror field subgroup On target heat sink The maximum projected power on is the mth mirror field subgroup S m Projected power coefficient at the target receiver Tn.

[0127] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily 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 is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A heliostat scheduling control method for a multi-tower, single-unit solar thermal mirror field, characterized in that: The steps include: Step 1: Divide the multi-tower single-machine mirror field into several mirror field subgroups according to the angles corresponding to the absorber faceplates; Step 2, dividing the target absorber into the mirror field according to the maximum projection radius; Step 3, calculate the projected power of each heliostat on the target absorber; Step 4, based on the projected power of each heliostat on the target absorber, calculate the maximum projected power of each mirror field subgroup on the target absorber and on the designated panel of the target absorber; Step 5: Generate a linear programming constraint matrix based on the calculated maximum projection power, set an initial constraint vector, use a binary search method to determine the binary search parameters, and obtain the final constraint vector; Step 6: Based on the linear programming constraint matrix and the final constraint vector, run a linear programming to determine the power allocation ratio of the target receiver in each mirror field subgroup, and allocate the heliostats within the subgroup according to the power allocation ratio; In step 2, take each heat absorber as the center of the circle and use the radius Draw a circle and set the target point of the heliostat within the circle to the heat sink. Each heliostat has a maximum of 3 target heat sinks. Greater than the radius of each mirror field and less than the maximum focusing distance of the heliostat; In step 5, the mth mirror field subgroup On target heat sink The projected power ratio on , its mathematical expression is: ； in, Indicates the mth mirror field subgroup On target heat sink The upper limit of the projection power ratio on the target point; R is the projection power coefficient corresponding to each subgroup-target point; The mth mirror field subgroup The total projected power ratio cannot exceed , its mathematical expression is: ； in, Indicates the mth mirror field subgroup Upper limit of total projected power ratio; Thus, the generated linear programming constraint matrix is ​​as follows: ； In step 6, the method for allocating heliostats within the subgroup according to the power allocation ratio is as follows: For the mth mirror field subgroup , the heliostat output power distribution follows the following process: (1) Single round allocation: The i-th heliostat is at the target receiver Projected power on Sort by power from largest to smallest and take the one that ranks first , and its corresponding target heat sink is , which corresponds to the target heat sink At the same time, the i-th heliostat is marked as used, and its projected power on other target absorbers is set to 0; (2) Cycle and termination: Repeat the above single round allocation steps. When a target heat sink The power reaches its required power When the heat sink is not All heliostats, place them in The projected power on is reset to 0, and it no longer participates in the power allocation of the target heat sink. It gives priority to ensuring the power allocation results of the target that has met the demand, and continues to allocate to other target heat sinks that have not met the demand until the allocation of each target is completed as needed.

2. The heliostat scheduling control method for a multi-tower, single-unit solar thermal mirror field according to claim 1, characterized in that: In step 1, the multi-tower, single-machine mirror field contains three sub-mirror fields. For each sub-mirror field, heliostats are arranged in a circular pattern around the receiver in that sub-mirror field, and adjacent rows of heliostats are staggered, with adjacent sub-mirror fields overlapping. Each receiver has 12 panels, corresponding to 12 angle intervals, dividing the entire mirror field into 36 sub-groups.

3. The heliostat scheduling control method for a multi-tower, single-unit solar thermal mirror field according to claim 1, characterized in that: In step 3, the projected power of each heliostat on the target receiver is calculated as follows: ； in, is the number of heliostats at the target receiver The projected power on is the direct normal radiation from the sun, is the number of heliostats at the target receiver Area is the reflection area of ​​the heliostat.

4. The heliostat scheduling control method for a multi-tower, single-unit solar thermal mirror field according to claim 1, characterized in that: In step 4, the mth mirror field subgroup On target heat sink Maximum projected power on The calculation formula is as follows: ； in, is the number of heliostats in the mth mirror field subgroup, , is the number of heliostats at the target receiver Projected power on The mth mirror field subgroup On target heat sink Panel Maximum projected power on The calculation formula is as follows: ； in, is the number of heliostats at the target receiver Panel The maximum projected power on the panel is when the i-th heliostat does not project onto the panel On time, .

5. The heliostat scheduling control method for a multi-tower, single-unit solar thermal mirror field according to claim 1, characterized in that: In step 5, the initial constraint vector is set as follows: ； in, represents the maximum allowable power of the kth panel, Indicates the maximum heat absorption power of the absorber.

6. The heliostat scheduling control method for a multi-tower, single-unit solar thermal mirror field according to claim 1, characterized in that: In step 5, the final constraint vector is as follows: ； in, Indicates the maximum heat absorption power of the absorber, Indicates the mth mirror field subgroup On target heat sink The upper limit of the projected power ratio, Indicates the mth mirror field subgroup The upper limit of the total projected power ratio.

7. The heliostat scheduling control method for a multi-tower, single-unit solar thermal mirror field according to claim 1, characterized in that: Target heat sink Required power The calculation formula is as follows: ； in, is the mth mirror field subgroup On target heat sink The maximum projected power on is the mth mirror field subgroup On target heat sink The projected power coefficient.

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