A method for controlling the mirror field of a multi-tower multiplex heliostat.

Abstract

This invention provides a mirror field and control method for a multi-tower multiplexed heliostat. The mirror field of the multi-tower multiplexed heliostat includes multiple tower-type receivers, an exclusive heliostat array corresponding to each tower-type receiver, and a shared heliostat array disposed between adjacent tower-type receivers. The tower-type receivers absorb the heat energy reflected by the heliostats. The exclusive heliostat arrays are arranged around the corresponding tower-type receivers to reflect heat energy back to them. The shared heliostat arrays reflect heat energy back to one or more predetermined tower-type receivers. The mirror field and control method of the multi-tower multiplexed heliostat provided by this invention fill the technological gap of lacking multi-tower multiplexing and optimized scheduling of heliostats when multiple concentrating solar thermal systems are used in parallel. By using a shared heliostat array, it achieves a faster start-up speed than concentrating solar thermal systems without multiplexed heliostats, extends the heat collection time of the concentrating solar thermal system, and can collect more energy.

Description

Technical Field

[0001] This invention relates to the field of tower solar thermal power generation technology, and in particular to a mirror field and control method for multi-tower reused heliostats. Background Technology

[0002] Solar thermal power generation, as a clean and renewable energy source, can achieve stable power output when combined with thermal storage, and can be used as base power or peak-shaving power, leading to its increasing applications.

[0003] Solar thermal power generation technologies mainly include: tower solar thermal power generation technology; trough solar thermal power generation technology; dish solar thermal power generation technology; and linear Fresnel solar thermal power generation technology. Among them, tower solar thermal power generation technology has received widespread attention due to its advantages such as high photothermal conversion efficiency and low heat loss. Tower solar thermal power generation technology focuses sunlight onto an absorber located at the top of the collector tower through a heliostat field (mirror field), heating the heat transfer medium in the absorber to generate heat energy. This heat energy is then generated through a heat exchange system to produce high-temperature steam, which drives a turbine to generate electricity. The concentrating efficiency of the mirror field plays a crucial role in this process.

[0004] In existing technologies, due to limitations in the efficiency of the heliostat field, it is difficult for a single concentrating solar thermal power plant with a single steam turbine to achieve the same capacity as a thermal power unit. However, by using multiple concentrating solar thermal power systems in parallel, more energy can be collected, allowing for the use of larger generator sets. Currently, due to atmospheric attenuation, the heliostat field area of ​​a single-tower solar thermal power generation system has reached its limit, making it impossible to obtain sufficient heliostat-reflected radiation energy for large generator sets. This results in tower solar thermal power generation systems being limited to using inefficient, small generator sets. Summary of the Invention

[0005] This invention provides mirror field control for multi-tower reusable heliostats to achieve mirror field control when multiple concentrating solar collectors are used in parallel. By adjusting the orientation of each heliostat relative to the receiver, more energy can be collected than when the same number of concentrating solar collectors are used individually.

[0006] The present invention provides a mirror field of a multi-tower multiplex heliostat, the mirror field of which includes multiple tower-type receivers, an exclusive heliostat array corresponding to each tower receiver, and a shared heliostat array disposed between adjacent tower receivers.

[0007] The tower-type heat absorber is used to absorb the heat energy reflected by the heliostat;

[0008] The exclusive heliostat array is arranged around the corresponding tower receiver to reflect heat energy to the corresponding tower receiver.

[0009] The shared heliostat array is used to reflect thermal energy toward one or more predetermined tower-type receivers.

[0010] Furthermore, the mirror field of the multi-tower multiplex heliostat includes a first tower receiver, a first dedicated heliostat array corresponding to the first tower receiver, a second tower receiver, a second dedicated heliostat array corresponding to the second tower receiver, and a first shared heliostat array shared by the first tower receiver and the second tower receiver.

[0011] The first tower receiver and the second tower receiver are arranged adjacent to each other; the first exclusive heliostat array and the second exclusive heliostat array are respectively arranged around the first tower receiver and the second tower receiver; the first shared heliostat array is arranged between the first tower receiver and the second tower receiver, and is respectively arranged around the first tower receiver and the second tower receiver.

[0012] Furthermore, the mirror field of the multi-tower multiplex heliostat includes a first tower receiver, a first exclusive heliostat array exclusively occupied by the first tower receiver, a second exclusive heliostat array exclusively occupied by the second tower receiver, a third tower receiver, a third exclusive heliostat array exclusively occupied by the third tower receiver, and a fourth shared heliostat array.

[0013] The first, second, and third tower receivers are arranged in a triangular configuration; the first, second, and third exclusive heliostat arrays are respectively arranged around the first, second, and third tower receivers; the fourth shared heliostat array is a Y-shaped heliostat array, which includes a shared portion between the first and second tower receivers, a shared portion between the second and third tower receivers, and a shared portion between the first and third tower receivers.

[0014] Furthermore, the mirror field of the multi-tower multiplex heliostat includes a first tower receiver, a first exclusive heliostat array exclusively occupied by the first tower receiver, a second tower receiver, a second exclusive heliostat array exclusively occupied by the second tower receiver, a third tower receiver, a third exclusive heliostat array exclusively occupied by the third tower receiver, a fourth tower receiver, a fourth exclusive heliostat array exclusively occupied by the fourth tower receiver, and a first shared heliostat array, a second shared heliostat array, and a third shared heliostat array.

[0015] The second, third, and fourth tower receivers are arranged in a triangular configuration, with the first tower receiver positioned within the triangle. A first, second, third, and fourth exclusive heliostat array are respectively arranged around the first, second, third, and fourth tower receivers. A first shared heliostat array is positioned between the first and second tower receivers, and is arranged around both of them. A second shared heliostat array is positioned between the first and third tower receivers, and is arranged around both of them. A third shared heliostat array is positioned between the first and fourth tower receivers, and is arranged around both of them.

[0016] A method for controlling the mirror field of a multi-tower multiplexed heliostat is also provided, the method comprising the following steps:

[0017] Step 1: Simulate and calculate the efficiency of each heliostat when it is pointing at the corresponding reusable receiver at the current moment;

[0018] Step 2: Based on the simulation calculation of the most efficient reusable receiver that each heliostat points to at the current moment, determine the relationship between the heliostat and the receiver.

[0019] Step 3: Simulate and calculate the energy that each receiver can currently receive when the heliostat is pointing to the receiver with the highest efficiency;

[0020] Step 4: Based on the energy that each receiver can currently receive, activate the corresponding receiver.

[0021] Step 5: Repeat steps 1-4 according to the sun's position.

[0022] Furthermore, in step 1, the efficiency η of the heliostat when it is pointed at any reusable receiver at the current moment is:

[0023] η=ρf cos f at f int

[0024] ρ is the specular reflectance, f cos It is the cosine efficiency of the heliostat, f at It is the atmospheric attenuation rate, f int It is the cut-off efficiency of the heat absorber;

[0025] The cosine efficiency of the heliostat is:

[0026] f cos =cosθ zcosβ+sinθ z sinβcos(γ s -γ)

[0027] θ z β is the solar zenith angle, β is the tilt angle of the illuminated surface, and γ is the solar zenith angle. s It is the solar azimuth angle, and γ is the azimuth angle of the normal of the illuminated surface relative to the horizontal plane;

[0028] Atmospheric attenuation rate f at for:

[0029]

[0030] Where, d hr It is the distance from the heliostat to the receiver;

[0031] The heat absorber cutoff efficiency is:

[0032] Where l is the length of the absorber cross-section, h is the width of the absorber cross-section, and σ tot It is an overflow factor.

[0033] Furthermore, in step 3, the energy E that the heat absorber can currently receive is:

[0034]

[0035] Where DNI is the current solar normal direct irradiance, m is the number of heliostats associated with the receiver to be calculated, A is the area of ​​each heliostat, and η is the efficiency of the receiver corresponding to the heliostat.

[0036] Furthermore, in step 1, the cosine efficiency of the heliostat... z for:

[0037] cosθ z =cosδcosφcosω+sinδsinφ

[0038] Where δ is the declination angle, φ is the local latitude, ω is the solar hour angle, and the declination angle is:

[0039]

[0040] n is the date sequence number, referring to the nth day of the year;

[0041] The solar hour angle is:

[0042] ω = 0.25° (AST-720)

[0043] AST is solar time, represented as:

[0044] AST = LST + ET - 4(SL - LL)

[0045] LST is the local standard time, ET is the correction value, SL is the longitude of the standard time measurement point, and LL is the local longitude; the correction value is expressed as:

[0046] ET=9.87sin(2B)-7.53cos(B)-1.5sin(B)

[0047] Where B = 360°(n-81) / 364;

[0048] The solar azimuth angle is:

[0049]

[0050] The tilt angle of the light-receiving surface is:

[0051]

[0052] The azimuth angle of the normal of the light-receiving surface relative to the horizontal plane is:

[0053]

[0054] Where x, y, and z are the positions of different receivers relative to a certain heliostat.

[0055] Furthermore, the feature is that, in step 2, the heliostat includes an exclusive heliostat and a shared heliostat;

[0056] An exclusive heliostat can only be associated with receivers that have an exclusive relationship with it, and only the efficiency of the receiver corresponding to it is calculated; a shared heliostat can be associated with receivers that have a shared relationship with it, and the efficiency of each receiver corresponding to it needs to be calculated separately.

[0057] Furthermore, in step 4, activating the corresponding receiver based on the energy that each receiver can currently receive also includes the following steps:

[0058] Determine whether the minimum start-up energy requirement is met based on the energy that the heat absorber can receive.

[0059] If the requirements are met, the receiver starts and issues a pointing command to the heliostats with which it is associated, so that the heliostats point to the receiver with the highest efficiency.

[0060] If the requirements are not met, the receiver and its corresponding dedicated heliostat are put into standby mode, and the shared heliostats with the associated relationship are pointed to the most efficient receiver among the receivers that are already started and have the shared relationship. If no receiver is in the started state, it is calculated whether it can be started when all the heliostats associated with the unstarted receivers are pointed to any receiver. If the start-up requirements are met, the receiver is started and the heliostats are reassigned. If it still cannot be started, both the receiver and the heliostat are put into standby mode.

[0061] The beneficial effects achieved by this invention are:

[0062] The mirror field and control strategy of the multi-tower reusable heliostat provided by this invention fills the technical gap of reusing and optimizing the scheduling of multiple receivers without heliostats when multiple concentrating solar thermal systems are used in parallel.

[0063] The mirror field and control strategy of the multi-tower reusable heliostat provided by this invention achieves a faster start-up speed than a concentrating solar thermal system without reusable heliostats, extends the heat collection time of the concentrating solar thermal system, and can collect more energy.

[0064] The mirror field and control strategy of the multi-tower multiplexed heliostat provided by this invention improves the cosine efficiency of the multiplexed heliostat, achieving a higher heat collection efficiency than the concentrating and heat collection system without multiplexed heliostats, and can provide more energy with the same number of heliostats. Attached Figure Description

[0065] Figure 1 This is a schematic plan view of a solar concentrating and heat collection system of a double-tower multiplex heliostat according to an embodiment of the present invention;

[0066] Figure 2 This is a schematic plan view of a three-tower reusable heliostat concentrating and heat collection system according to an embodiment of the present invention;

[0067] Figure 3 This is a schematic plan view of a solar concentrating and heat collection system with three or more reusable heliostats according to an embodiment of the present invention;

[0068] Figure 4 This is a schematic flowchart of a method for controlling the mirror field of a multi-tower multiplexed heliostat according to an embodiment of the present invention.

[0069] 101-First tower receiver, 102-Second tower receiver, 103-Third tower receiver, 104-Fourth tower receiver, 201-First exclusive heliostat array, 202-Second exclusive heliostat array, 203-Third exclusive heliostat array, 204-Fourth exclusive heliostat array, 301-First shared heliostat array, 302-Second shared heliostat array, 303-Third shared heliostat array and 304-Fourth shared heliostat array. Detailed Implementation

[0070] The technical solution of the present invention will be described in more detail below with reference to the accompanying drawings. The present invention includes, but is not limited to, the following embodiments.

[0071] This invention proposes a mirror field for a multi-tower multiplexed heliostat, which includes multiple tower receivers and a heliostat array matched with the tower receivers. The heliostat array includes an exclusive heliostat array corresponding to each tower receiver and a shared heliostat array disposed between adjacent tower receivers.

[0072] This mirror field can collect more energy than an equivalent number of concentrating solar collectors would collect if used alone, by adjusting the orientation of each heliostat to the receiver.

[0073] The core principle is that the efficiency of a heliostat in reflecting sunlight to a specific receiver varies with the sun's daily trajectory. With multiple receivers, the efficiency of the heliostat in reflecting sunlight to different receivers differs, and the efficiency varies with the sun's trajectory. By calculating and ensuring that the heliostat reflects sunlight to the receiver with the highest efficiency in real time, the efficiency of multiple concentrating solar collectors used in parallel can be maximized, exceeding the efficiency of the same number of concentrating solar collectors used individually.

[0074] Example 1

[0075] As attached Figure 1 As shown, in this embodiment, the mirror field of the multi-tower multiplexed heliostat includes a first tower receiver 101, a first exclusive heliostat array 201 corresponding to the first tower receiver 101, a second tower receiver 102, a second exclusive heliostat array 202 corresponding to the second tower receiver 102, and a first shared heliostat array 301 shared by the first tower receiver 101 and the second tower receiver 102.

[0076] The first tower receiver 101 and the second tower receiver 102 are arranged adjacent to each other; the first exclusive heliostat array 201 and the second exclusive heliostat array 202 are respectively arranged around the first tower receiver 101 and the second tower receiver 102; the first shared heliostat array 301 is located between the first tower receiver 101 and the second tower receiver 102, and is respectively arranged around the first tower receiver 101 and the second tower receiver 102.

[0077] During the startup phase, the energy provided by the first dedicated heliostat array 201 plus the first shared heliostat array 301 and the second dedicated heliostat array 202 plus the first shared heliostat array 301 is first calculated based on the current DNI to determine whether it meets the requirement for simultaneous startup of the first tower receiver 101 and the second tower receiver 102. Specifically, the efficient portion of the shared heliostat array, consisting of a plurality of heliostats whose distance from a receiver with a shared relationship is less than that from other receivers with shared relationships, is the efficient portion for that receiver.

[0078] If only the high-efficiency portion of the first exclusive heliostat array 201 and the first shared heliostat array 301 provides enough energy to meet the startup requirements, only the first tower receiver 101 will be activated, and both the first exclusive heliostat array 201 and the first shared heliostat array 301 will be used by the first tower receiver 101.

[0079] If only the high-efficiency portion of the second exclusive heliostat array 202 and the first shared heliostat array 301 provides enough energy to meet the startup requirements, only the second tower receiver 102 will be activated, and both the second exclusive heliostat array 202 and the first shared heliostat array 301 will be used by the second tower receiver 102.

[0080] If the energy provided by the first exclusive heliostat array 201 plus the high-efficiency section of the first shared heliostat array 301 and the second exclusive heliostat array 202 plus the high-efficiency section of the first shared heliostat array 301 both meet the startup requirements, the first tower receiver 101 and the second tower receiver 102 are activated. The first shared heliostat array 301 allocates the energy provided by the heliostats to the first tower receiver 101 and the second tower receiver 102 respectively according to the principle of maximum efficiency and the energy ratio provided by the first exclusive heliostat array 201 and the second exclusive heliostat array 202.

[0081] During operation, if the first tower receiver 101 operates alone, the first exclusive heliostat array 201 and the first shared heliostat array 301 are both used by the first tower receiver 101.

[0082] If the second tower receiver 102 operates alone, the second exclusive heliostat array 202 and the first shared heliostat array 301 are both used by the second tower receiver 102.

[0083] If the first tower receiver 101 and the second tower receiver 102 operate simultaneously, the heliostats in the first shared heliostat array 301 calculate the energy values ​​that can be provided to the first tower receiver 101 and the second tower receiver 102 respectively, and automatically select the receiver to collect heat based on the higher energy value.

[0084] Example 2

[0085] As attached Figure 2As shown, in this embodiment, the mirror field of the multi-tower multiplexed heliostat includes a first tower receiver 101, a first exclusive heliostat array 201 exclusively occupied by the first tower receiver 101, a second tower receiver 102, a second exclusive heliostat array 202 exclusively occupied by the second tower receiver 102, a third tower receiver 103, a third exclusive heliostat array 203 exclusively occupied by the third tower receiver 103, and a fourth shared heliostat array 304.

[0086] The first tower receiver 101, the second tower receiver 102, and the third tower receiver 103 are arranged in an equilateral triangle. The first exclusive heliostat array 201, the second exclusive heliostat array 202, and the third exclusive heliostat array 203 are respectively arranged around the first tower receiver 101, the second tower receiver 102, and the third tower receiver 103. The fourth shared heliostat array 304 is a heliostat array with a Y-shaped regional distribution, which is composed of the shared part between the first tower receiver 101 and the second tower receiver 102, the shared part between the second tower receiver 102 and the third tower receiver 103, and the shared part between the first tower receiver 101 and the third tower receiver 103.

[0087] During the startup phase, the energy values ​​provided by the first exclusive heliostat array 201 plus the fourth shared heliostat array 304 (high-efficiency section), the second exclusive heliostat array 202 plus the fourth shared heliostat array 304 (high-efficiency section), and the third exclusive heliostat array 203 plus the fourth shared heliostat array 304 (high-efficiency section) are first assessed to determine if they meet the requirement for simultaneous startup of the first tower receiver 101, the second tower receiver 102, and the third tower receiver 103.

[0088] If only the high-efficiency portion of the first exclusive heliostat array 201 and the fourth shared heliostat array 304 provides enough energy to meet the startup requirements, the first tower receiver 101 is activated. Both the first exclusive heliostat array 201 and the fourth shared heliostat array 304 are used by the first tower receiver 101.

[0089] If only the high-efficiency portion of the second exclusive heliostat array 202 and the fourth shared heliostat array 304 provides enough energy to meet the startup requirements, the second tower receiver 102 is activated, and both the second exclusive heliostat array 202 and the fourth shared heliostat array 304 are used by the second exclusive heliostat array 202.

[0090] If only the high-efficiency portion of the third exclusive heliostat array 203 and the fourth shared heliostat array 304 provides enough energy to meet the startup requirements, the third tower receiver 103 is activated. Both the third exclusive heliostat array 203 and the fourth shared heliostat array 304 are used by the third tower receiver 103.

[0091] If the energy provided by the first exclusive heliostat array 201 plus the high-efficiency portion of the fourth shared heliostat array 304 and the second exclusive heliostat array 202 plus the high-efficiency portion of the fourth shared heliostat array 304 meets the startup requirements, the first tower receiver 101 and the second tower receiver 102 are activated. The fourth shared heliostat array 304 allocates the heliostats according to the energy provided by the fourth shared heliostat array based on the principle of maximum efficiency, so that the first tower receiver 101 and the second tower receiver 102 can use them respectively.

[0092] If the energy provided by the first exclusive heliostat array 201 plus the high-efficiency section of the fourth shared heliostat array 304 and the third exclusive heliostat array 203 plus the high-efficiency section of the fourth shared heliostat array 304 meets the startup requirements, the first tower receiver 101 and the third tower receiver 103 are activated. The fourth shared heliostat array 304 allocates the energy provided by the heliostats to the first tower receiver 101 and the third tower receiver 103 respectively according to the principle of maximum efficiency and the proportion of energy provided by the first exclusive heliostat array 201 and the third exclusive heliostat array 203.

[0093] If the energy provided by the second exclusive heliostat array 202 plus the high-efficiency section of the fourth shared heliostat array 304 and the third exclusive heliostat array 203 plus the high-efficiency section of the fourth shared heliostat array 304 meets the startup requirements, the second tower receiver 102 and the third tower receiver 103 are activated. The fourth shared heliostat array 304 allocates the energy provided by the heliostats to the second tower receiver 102 and the third tower receiver 103 respectively according to the principle of maximum efficiency and the proportion of energy provided by the second exclusive heliostat array 202 and the third exclusive heliostat array 203.

[0094] If the energy provided by the first exclusive heliostat array 201 plus the high-efficiency section of the fourth shared heliostat array 304, the second exclusive heliostat array 202 plus the high-efficiency section of the fourth shared heliostat array 304, and the third exclusive heliostat array 203 plus the high-efficiency section of the fourth shared heliostat array 304 all meet the startup requirements, the first tower receiver 101, the second tower receiver 102, and the third tower receiver 103 are activated. The fourth shared heliostat array 304 allocates the energy provided by the heliostats to the first tower receiver 101, the second tower receiver 102, and the third tower receiver 103 according to the principle of maximum efficiency and the proportion of energy provided by the first exclusive heliostat array 201, the second exclusive heliostat array 202, and the third exclusive heliostat array 203.

[0095] During operation, if the first tower receiver 101 operates alone, the first exclusive heliostat array 201 and the fourth shared heliostat array 304 are used by the first tower receiver 101.

[0096] If the second tower receiver 102 operates alone, the second exclusive heliostat array 202 and the fourth shared heliostat array 304 are used by the second tower receiver 102.

[0097] If the third tower receiver 103 operates alone, the third exclusive heliostat array 203 and the fourth shared heliostat array 304 are used by the third tower receiver 103.

[0098] If the first tower receiver 101 and the second tower receiver 102 operate simultaneously, the heliostats in the fourth shared heliostat array 304 calculate the energy values ​​that can be provided to the first tower receiver 101 and the second tower receiver 102 respectively, and select the receiver to collect heat based on the higher energy value.

[0099] If the first tower receiver 101 and the third tower receiver 103 operate simultaneously, the heliostats in the fourth shared heliostat array 304 calculate the energy values ​​that can be provided to the first tower receiver 101 and the third tower receiver 103 respectively, and select the receiver to collect heat based on the higher energy value.

[0100] If the second tower receiver 102 and the third tower receiver 103 operate simultaneously, the heliostats in the fourth shared heliostat array 304 calculate the energy values ​​that can be provided to the second tower receiver 102 and the third tower receiver 103 respectively, and automatically select the receiver to collect heat based on the higher energy value.

[0101] If the first tower receiver 101, the second tower receiver 102, and the third tower receiver 103 operate simultaneously, the heliostats in the fourth shared heliostat array 304 calculate the energy values ​​that can be provided to the first tower receiver 101, the second tower receiver 102, and the third tower receiver 103, and automatically select the receiver to collect heat based on the highest energy value.

[0102] Example 3

[0103] As attached Figure 3 As shown, in this embodiment, the mirror field of the multi-tower multiplexed heliostat includes a first tower receiver 101, a first exclusive heliostat array 201 exclusively occupied by the first tower receiver 101, a second tower receiver 102, a second exclusive heliostat array 202 exclusively occupied by the second tower receiver 102, a third tower receiver 103, a third exclusive heliostat array 203 exclusively occupied by the third tower receiver 103, a fourth tower receiver 104, a fourth exclusive heliostat array 204 exclusively occupied by the fourth tower receiver 104, and a first shared heliostat array 301, a second shared heliostat array 302, and a third shared heliostat array 303.

[0104] The second tower receiver 102, the third tower receiver 103, and the fourth tower receiver 104 are arranged in an equilateral triangle, with the first tower receiver 101 located at the center of the triangle. The first exclusive heliostat array 201, the second exclusive heliostat array 202, the third exclusive heliostat array 203, and the fourth exclusive heliostat array 204 are respectively arranged around the first tower receiver 101, the second tower receiver 102, the third tower receiver 103, and the fourth tower receiver 104. The first shared heliostat array 301 is located between the first tower receiver 101 and... The second tower receiver 102 is positioned between the first tower receiver 101 and the second tower receiver 102, and is respectively arranged around the first tower receiver 101 and the second tower receiver 102; the second common heliostat array 302 is positioned between the first tower receiver 101 and the third tower receiver 103, and is respectively arranged around the first tower receiver 101 and the third tower receiver 103; the third common heliostat array 303 is positioned between the first tower receiver 101 and the fourth tower receiver 104, and is respectively arranged around the first tower receiver 101 and the fourth tower receiver 104.

[0105] During the startup phase, the energy provided by the first exclusive heliostat array 201 plus the high-efficiency part of the first shared heliostat array 301, the high-efficiency part of the second shared heliostat array 302, and the high-efficiency part of the third shared heliostat array 303 is first calculated based on DNI to determine whether it meets the startup requirements of the first tower receiver 101.

[0106] If the energy provided by the first exclusive heliostat array 201 plus the high-efficiency section of the first shared heliostat array 301, the high-efficiency section of the second shared heliostat array 302, and the high-efficiency section of the third shared heliostat array 303 meets the startup requirements, the first tower receiver 101 is activated. The first exclusive heliostat array 201, the first shared heliostat array 301, the second shared heliostat array 302, and the third shared heliostat array 303 are all used by the first tower receiver 101.

[0107] Furthermore, based on DNI calculations, it is determined whether the energy values ​​provided by the second exclusive heliostat array 202 plus the high-efficiency portion of the first shared heliostat array 301, the third exclusive heliostat array 203 plus the high-efficiency portion of the second shared heliostat array 302, and the fourth exclusive heliostat array 204 plus the high-efficiency portion of the third shared heliostat array 303 meet the requirement of simultaneous startup of the second tower receiver 102, the third tower receiver 103, and the fourth tower receiver 104.

[0108] If the energy provided by the second exclusive heliostat array 202 meets the startup requirements, the second tower receiver 102 is activated. The first shared heliostat array 301 allocates the energy provided by the heliostats to the first tower receiver 101 and the second tower receiver 102 respectively according to the principle of maximum efficiency and the energy ratio provided by the first exclusive heliostat array 201 and the second exclusive heliostat array 202.

[0109] If the energy provided by the third exclusive heliostat array 203 meets the startup requirements, the third tower receiver 103 is activated. The second shared heliostat array 302 allocates the energy provided by the heliostats to the first tower receiver 101 and the third tower receiver 103 respectively according to the principle of maximum efficiency and the energy ratio provided by the first exclusive heliostat array 201 and the third exclusive heliostat array 203.

[0110] If the energy provided by the fourth exclusive heliostat array 204 meets the startup requirements, the fourth tower receiver 104 is activated. The third shared heliostat array 303 allocates the energy provided by the heliostats to the first tower receiver 101 and the fourth tower receiver 104 respectively according to the principle of maximum efficiency and the energy ratio provided by the first exclusive heliostat array 201 and the fourth exclusive heliostat array 204.

[0111] During operation, if the first tower receiver 101 operates alone, the first exclusive heliostat array 201, the first shared heliostat array 301, the second shared heliostat array 302, and the third shared heliostat array 303 are used by the first tower receiver 101.

[0112] Furthermore, if the second tower receiver 102 operates simultaneously, the heliostats in the first shared heliostat array 301 calculate the energy values ​​that can be provided to the first tower receiver 101 and the second tower receiver 102 respectively, and automatically select the receiver to collect heat based on the higher energy value.

[0113] If the third tower receiver 103 is operating simultaneously, the heliostats in the second shared heliostat array 302 calculate the energy values ​​that can be provided to the first tower receiver 101 and the third tower receiver 103 respectively, and select the receiver to collect heat based on the higher energy value.

[0114] If the fourth tower receiver 104 is operating simultaneously, the heliostats in the third shared heliostat array 303 calculate the energy values ​​that can be provided to the first tower receiver 101 and the fourth tower receiver 104 respectively, and select the receiver to collect heat based on the higher energy value.

[0115] Example 4

[0116] This embodiment provides a mirror field control method for multi-tower reusable heliostats to meet the mirror field control system requirements when multiple concentrating solar thermal systems are used in parallel. By adjusting the orientation of each heliostat relative to the receiver, more energy can be collected than when the same number of concentrating solar thermal systems are used individually.

[0117] The core principle is that the efficiency of a heliostat in reflecting sunlight to a specific receiver varies with the sun's daily trajectory. With multiple receivers, the efficiency of the heliostat in reflecting sunlight to different receivers differs, and the efficiency varies with the sun's trajectory. By calculating and ensuring that the heliostat reflects sunlight to the receiver with the highest efficiency in real time, the efficiency of multiple concentrating solar collectors used in parallel can be maximized, exceeding the efficiency of the same number of concentrating solar collectors used individually.

[0118] As attached Figure 4 As shown, the mirror field control method includes the following steps:

[0119] Step 1: Simulate and calculate the efficiency of each heliostat when it is pointing at the corresponding reusable receiver at the current moment;

[0120] In a heliostat field, heliostats include dedicated heliostats and shared heliostats. For dedicated heliostats, only the efficiency of the corresponding receiver is calculated. For shared heliostats, the efficiency of each receiver is calculated separately. The efficiency of each heliostat when pointing towards its corresponding receiver needs to be calculated individually. The efficiency calculation method is as follows:

[0121] η=ρf cos f at f int #(1-1)

[0122] In equation (1-1), ρ is the specular reflectance, with an annual average of 0.85, and f cos It is the cosine efficiency of the heliostat, f at It is the atmospheric attenuation rate, f int It is the cutoff efficiency of the heat absorber.

[0123] The coordinates of the relative positions of each heliostat to different receivers affect the heliostat's cosine efficiency f. cos The distance between the heliostat and the receiver affects the receiver's cutoff efficiency f. int and atmospheric attenuation rate f at .

[0124] Among them, the cosine efficiency f of the heliostat cos for:

[0125] f cos =cosθ z cosβ+sinθ z sinβcos(γs -γ)#(1-2a)

[0126] In equation (1-2a), θ z β is the solar zenith angle, β is the tilt angle of the illuminated surface, and γ is the solar zenith angle. s γ is the solar azimuth angle, and γ is the azimuth angle of the normal of the illuminated surface relative to the horizontal plane.

[0127] cosθ z =cosδcosφcosω+sinδsinφ#(1-2b)

[0128] In equation (1-2b), δ is the declination angle, φ is the local latitude, and ω is the solar hour angle.

[0129]

[0130] In equation (1-2c), n is the date number, referring to the nth day of the year, and n=1 represents January 1st.

[0131] ω=0.25°(AST-720)#(1-2d)

[0132] In equation (1-2d), AST is solar time.

[0133] AST = LST + ET - 4(SL - LL) # (1 - 2e)

[0134] In equation (1-2e), LST is the local standard time in minutes; ET is the correction value in minutes; SL is the longitude of the standard time measurement point; and LL is the local longitude.

[0135] ET=9.87sin(2B)-7.53cos(B)-1.5sin(B)#(1-2f)

[0136] In equation (1-2f), B = 360°(n-81) / 364, where n is the date number, referring to the nth day of the year, and n = 1 represents January 1st.

[0137]

[0138] Atmospheric attenuation rate f at for:

[0139]

[0140] In equation (1-3), d hr It is the distance from the heliostat to the receiver.

[0141] Heat absorber cutoff efficiency f int for:

[0142]

[0143] In equation (1-4a), l is the length of the receiver cross-section, h is the width of the receiver cross-section, and σ tot It is an overflow factor.

[0144]

[0145] In equation (1-4b), d hr It is the distance from the heliostat to the receiver, σ sun The solar divergence angle is 9.6 mrad, σ bq The splicing angle error of the sub-mirrors is 0.98, σ ast The astigmatism error is 0.996, σ track The heliostat tracking error is 0.02 mrad.

[0146]

[0147] In equations (1-5), (1-6), and (1-7), x, y, and z are the positions of different receivers relative to a certain heliostat.

[0148] By substituting different values ​​(x, y, z) into the different positions of different receivers relative to a certain heliostat, the efficiency η of a certain heliostat for different receivers can be obtained.

[0149] Step 2: Based on the simulation calculation of the most efficient reusable receiver that each heliostat points to at the current moment, determine the relationship between the heliostat and the receiver.

[0150] Among them, an exclusive heliostat can only be associated with the receivers it has an exclusive relationship with, while a shared heliostat is associated with the most efficient receiver among the receivers it shares with.

[0151] Step 3: Simulate and calculate the energy that each receiver can currently receive when the heliostat is pointing to the receiver with the highest efficiency;

[0152]

[0153] In Equation (2-1), DNI is the current solar normal direct irradiance (W / ㎡), m is the number of heliostats associated with the receiver to be calculated, A is the area of ​​each heliostat (㎡), and η is the efficiency of the receiver corresponding to the heliostat.

[0154] Step 4: Based on the energy that each receiver can currently receive, activate the corresponding receiver.

[0155] Specifically, the minimum start-up energy requirement is determined based on the energy that the receiver can receive.

[0156] If the requirements are met, the receiver starts and issues a pointing command to the associated heliostats so that the heliostats point to the receiver with the highest efficiency.

[0157] If the requirements are not met, the receiver and its corresponding dedicated heliostat will be put into standby mode, and the shared heliostats with the associated relationship will be pointed to the most efficient receiver among the receivers that are already started and have the shared relationship. If no receiver is currently started, it will be calculated whether it can be started when all the heliostats associated with the unstarted receivers are pointed to any receiver. If the start-up requirements are met, the receiver will be started and the heliostats will be reassigned. If it still cannot be started, both the receiver and the heliostat will be put into standby mode.

[0158] Taking the mirror field layout in Embodiment 1 as an example, when the energy provided by the first exclusive heliostat array 201 and the second exclusive heliostat array 202 has met the start-up requirements of the first tower receiver 101 and the second tower receiver 102 respectively, the first tower receiver 101 and the second tower receiver 102 are started, and each heliostat in the first shared heliostat array 301 points to the receiver with the highest efficiency.

[0159] If the energy provided by the first exclusive heliostat array 201 and the second exclusive heliostat array 202 alone is insufficient to meet the startup requirements of the first tower receiver 101 and the second tower receiver 102, then the energy of each heliostat parameter in the first shared heliostat array 301 is provided to the receiver with the highest efficiency. It is then determined whether the first tower receiver 101 and the second tower receiver 102 meet the requirement of simultaneous startup under the action of the first shared heliostat array 301. If the requirement is met, then the first tower receiver 101 and the second tower receiver 102 are started, and each heliostat in the first shared heliostat array 301 points to the receiver with the highest efficiency.

[0160] If the first tower receiver 101 and the second tower receiver 102 still cannot meet the requirement of simultaneous start-up under the action of the first shared heliostat array 301, then consider providing the energy generated by all the heliostats in the first shared heliostat array 301 to the receiver in the first tower receiver 101 or the second tower receiver 102 that can generate more energy. If the start-up conditions under this condition are met, then the corresponding receiver is started, so that the first shared heliostat array 301 is all pointing at that receiver, while the other receiver and the corresponding exclusive heliostat array are on standby; if it still cannot be started, then the two receivers and all the heliostat arrays are on standby.

[0161] Step 5: Repeat steps 1-4 according to the sun's position.

[0162] The mirror field control strategy for multi-tower reusable heliostats provided by this invention fills the technological gap in the reuse and optimized scheduling of multiple receivers without heliostats when multiple concentrating solar thermal systems are used in parallel. It also achieves a faster start-up speed and extends the heat collection time of concentrating solar thermal systems compared to those without reusable heliostats, allowing for the collection of more energy.

[0163] The mirror field control strategy for multi-tower multiplexed heliostats provided by this invention also improves the cosine efficiency of the multiplexed heliostats, achieving a higher heat collection efficiency than a concentrating solar thermal system without multiplexed heliostats, and can provide more energy with the same number of heliostats.

[0164] The invention is not limited to the specific embodiments described above. Those skilled in the art can implement the invention using other specific embodiments based on the disclosed content of the embodiments and accompanying drawings. Therefore, any design that adopts the design structure and concept of the invention and makes some simple changes or modifications falls within the protection scope of the invention.

Claims

1. A mirror field of a multi-tower multiplexed heliostat, characterized in that, The mirror field of the multi-tower multiplexing heliostat comprises a plurality of tower heat absorbers, an exclusive heliostat array corresponding to each tower heat absorber, and a shared heliostat array arranged between adjacent tower heat absorbers; The tower heat absorber is used for absorbing heat energy reflected by the heliostat; The exclusive heliostat array is arranged around the corresponding tower heat absorber, and is used for reflecting heat energy to the corresponding tower heat absorber; The shared heliostat array is used for reflecting heat energy to one or more predetermined tower heat absorbers; The mirror field of the multi-tower multiplexing heliostat comprises a first tower heat absorber (101), a first exclusive heliostat array (201) exclusive to the first tower heat absorber (101), a second exclusive heliostat array (202) exclusive to a second tower heat absorber (102), a third tower heat absorber (103), a third exclusive heliostat array (203) exclusive to the third tower heat absorber (103), and a fourth shared heliostat array (304); The first tower heat absorber (101), the second tower heat absorber (102) and the third tower heat absorber (103) are distributed in a triangular shape; the first exclusive heliostat array (201), the second exclusive heliostat array (202) and the third exclusive heliostat array (203) are arranged around the first tower heat absorber (101), the second tower heat absorber (102) and the third tower heat absorber (103) respectively; the fourth shared heliostat array (304) is a Y-shaped area distributed heliostat array, comprising a shared part between the first tower heat absorber (101) and the second tower heat absorber (102), a shared part between the second tower heat absorber (102) and the third tower heat absorber (103), and a shared part between the first tower heat absorber (101) and the third tower heat absorber (103).

2. A mirror field of a multi-tower, multiplexed heliostat, characterized in that, The mirror field of the multi-tower multiplexing heliostat comprises a first tower heat absorber (101), a first exclusive heliostat array (201) exclusive to the first tower heat absorber (101), a second tower heat absorber (102), a second exclusive heliostat array (202) exclusive to the second tower heat absorber (102), a third tower heat absorber (103), a third exclusive heliostat array (203) exclusive to the third tower heat absorber (103), a fourth tower heat absorber (104), a fourth exclusive heliostat array (204) exclusive to the fourth tower heat absorber (104), and a first shared heliostat array (301), a second shared heliostat array (302) and a third shared heliostat array (303); The first tower heat absorber (101), the second tower heat absorber (102) and the third tower heat absorber (103) are distributed in a triangular shape; the first exclusive heliostat array (201), the second exclusive heliostat array (202) and the third exclusive heliostat array (203) are arranged around the first tower heat absorber (101), the second tower heat absorber (102) and the third tower heat absorber (103) respectively; the fourth shared heliostat array (304) is a Y-shaped area distributed heliostat array, comprising a shared part between the first tower heat absorber (101) and the second tower heat absorber (102), a shared part between the second tower heat absorber (102) and the third tower heat absorber (103), and a shared part between the first tower heat absorber (101) and the third tower heat absorber (103). The second tower heat absorber (102), the third tower heat absorber (103) and the fourth tower heat absorber (104) are in a triangular distribution, and the first tower heat absorber (101) is arranged in the triangle; the first exclusive heliostat array (201), the second exclusive heliostat array (202), the third exclusive heliostat array (203) and the fourth exclusive heliostat array (204) are respectively arranged outside the first tower heat absorber (101), the second tower heat absorber (102), the third tower heat absorber (103) and the fourth tower heat absorber (104); the first shared heliostat array (301) is arranged between the first tower heat absorber (101) and the second tower heat absorber (102), and is arranged outside the first tower heat absorber (101) and the second tower heat absorber (102) respectively; the second shared heliostat array (302) is arranged between the first tower heat absorber (101) and the third tower heat absorber (103), and is arranged outside the first tower heat absorber (101) and the third tower heat absorber (103) respectively; the third shared heliostat array (303) is arranged between the first tower heat absorber (101) and the fourth tower heat absorber (104), and is arranged outside the first tower heat absorber (101) and the fourth tower heat absorber (104) respectively.

3. A method for controlling the mirror field of a multi-tower concentrator heliostat according to any of claims 1-2, characterized in that, The control method comprises the following steps: Step 1, simulate the efficiency of each heliostat at the current time when the heliostat points to the corresponding reusable heat absorber; Step 2, determine the association between the heliostat and the heat absorber according to the highest efficiency of the heat absorber pointed to by each heliostat at the current time obtained by simulation; Step 3, simulate the current receivable energy of each heat absorber when the heliostat points to the heat absorber with the highest efficiency; Step 4, start the corresponding heat absorber according to the current receivable energy of each heat absorber; Step 5, repeat steps 1-4 according to the position of the sun.

4. The mirror field control method of a multi-tower concentrator heliostat according to claim 3, wherein, In step 1, the efficiency η of the heliostat at the current time when the heliostat points to any reusable heat absorber is: η = p f cos f at f int p is the specular reflectivity, f cos is the heliostat cosine efficiency, f at is the atmospheric attenuation rate, f int is the absorber intercept efficiency; Wherein, the cosine efficiency of the heliostat is: f cos = cos θ z cos β + sin θ z sin β cos (γ s - γ) θ z is the solar zenith angle, β is the tilt angle of the light receiving surface, γ s is the solar azimuth angle, and γ is the azimuth angle of the normal of the light receiving surface relative to the horizontal plane. Atmospheric attenuation rate f at is: where d hr is the distance from the heliostat to the receiver; The truncation efficiency of the heat absorber is: where l is the length of the cross section of the heat sink, h is the width of the cross section of the heat sink, σ tot is the spill factor.

5. The mirror field control method of a multi-tower concentrator heliostat according to claim 4, wherein, In step 3, the current receivable energy E of the heat absorber is: Wherein, DNI is the current solar normal direct irradiance, m is the number of heliostats associated with the heat absorber to be calculated, A is the area of each heliostat, and η is the efficiency of the heliostat corresponding to the current heat absorber.

6. The mirror field control method of a multi-tower concentrator heliostat according to claim 4, wherein, In step 1, the cosine efficiency of the heliostat cos θ z is: cos θ z = cos δ cos φ cos ω + sin δ sin φ Wherein, δ is the declination angle, φ is the local latitude, and ω is the solar hour angle, and the declination angle is: n is the date sequence number, indicating the nth day of the year; The solar hour angle is: ω = 0.25° (AST-720) AST is the solar time, expressed as: AST = LST + ET-4 (SL-LL) LST is the local standard time, ET is the correction value, SL is the longitude of the standard time measurement point, and LL is the local longitude; the correction value is expressed as: ET = 9.87 sin (2B)-7.53 cos (B)-1.5 sin (B) Wherein, B = 360° (n-81) / 364; The solar azimuth angle is: The inclination angle of the light receiving surface is: The azimuth angle of the normal of the light receiving surface relative to the horizontal plane is: Wherein, x, y, z are the positions of different heat receivers relative to a certain heliostat.

7. The mirror field control method of a multi-tower concentrator heliostat according to claim 6, wherein, In step 2, the heliostat includes an exclusive heliostat and a shared heliostat; The exclusive heliostat can only be associated with the heat receiver having an exclusive relationship, and only calculates the efficiency of the fixed corresponding heat receiver; the shared heliostat can be associated with the heat receiver having a shared relationship, and needs to calculate the efficiency of each corresponding heat receiver respectively.

8. The mirror field control method of a multi-tower concentrator heliostat according to claim 7, wherein, In step 4, according to the energy that each heat receiver can receive at present, starting the corresponding heat receiver includes the following steps: According to the energy that the heat receiver can receive, it is judged whether the minimum starting energy requirement is met; If the requirement is met, the heat receiver is started, and the pointing command is issued to the heliostat having the associated relationship to make the heliostat point to the heat receiver with the highest efficiency; If the requirement is not met, the heat receiver and the corresponding exclusive heliostat are on standby, and the shared heliostat having the associated relationship is pointed to the heat receiver with the highest efficiency among the heat receivers that have been started and have the shared relationship; if there is no heat receiver in the starting state, it is calculated whether all the heliostats associated with the heat receivers that have not been started can be started when they are all pointed to an arbitrary heat receiver, if the starting requirement is met, the heat receiver is started, and the heliostat is re-associated, if it still cannot be started, the heat receiver and the heliostat are on standby.

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