A method and system for heliostat error correction in a tower solar thermal power generation system

Abstract

The present application discloses a method and system for correcting the errors of heliostats in a tower-type solar thermal power generation system, which relates to the technical field of solar thermal utilization. The method includes: obtaining a preset angle; controlling the to-be-corrected heliostat to rotate to the preset angle; collecting, by a drone, a target image of the solar collector tower at the position and direction where the heliostat is located; identifying the heat collection area of the solar collector tower in the target image, and determining whether the center of the heat collection area coincides with the center of the target image. If they do not coincide, controlling the heliostat to rotate and collecting the target image again. If the center of the heat collection area in the target image coincides with the center of the target image, recording the rotation angle of the heliostat to obtain a first rotation angle; correcting the preset angle according to the first rotation angle. The method of the present application does not need to rely on the light reflected by the heliostat, so there is no requirement for light, and it has a wide application range. Moreover, the drone can fly autonomously and does not need to install multiple cameras in advance, greatly reducing the complexity of the operation.

Description

Technical Field

[0001] The present application relates to the technical field of solar thermal utilization, and particularly to a method and system for correcting the error of heliostats in a tower-type solar thermal power generation system. Background Art

[0002] In a tower-type solar thermal power generation system, a heliostat is an important component. Heliostats are usually arranged around a collector tower. By reflecting sunlight onto the collector tower, the solar heat can be absorbed and stored, and then used for power generation. Since the direction of sunlight changes constantly, the heliostats also need to rotate continuously to accurately reflect sunlight onto the collector tower. In this process, a relatively high precision is required for the angle control of the heliostats.

[0003] Although the angle of each heliostat is estimated during the design process of a solar thermal power plant, the installation process of heliostats involves processes such as foundation excavation, bracket installation, and mirror installation. Each process will cause certain errors. After the accumulation of these errors, the actual attitude of the heliostat may deviate greatly from the designed attitude. If it is directly put into use without correction, a considerable part of solar thermal energy cannot be utilized. Therefore, error correction is carried out after the installation of the heliostats.

[0004] However, current technologies for correcting heliostat errors are all based on the light reflected by the heliostats. For example, CN102116604A and CN108413987A collect the spot images of sunlight reflected by heliostats, and CN108958229A collects the light reflected by heliostats to form an image. This technology requires pre-installing cameras. Since the number of heliostats is relatively large, multiple cameras need to be pre-installed or the position of the camera needs to be moved, which is very inconvenient to operate. Moreover, the technology using the light reflected by heliostats has relatively high requirements for the weather. It not only requires sunlight, but also the light intensity must reach a certain value, resulting in great limitations in the application of this technology. Summary of the Invention

[0005] Embodiments of the present application provide a method and system for correcting the error of heliostats in a tower-type solar thermal power generation system, so as to solve the problems of inconvenient operation and limited application of the prior art for error correction based on the light reflected by heliostats.

[0006] On the one hand, embodiments of the present application provide a method for correcting the error of heliostats in a tower-type solar thermal power generation system, including:

[0007] Obtaining design data, where the design data includes the preset angle of the heliostat;

[0008] Controlling the heliostat to be corrected to rotate to the preset angle;

[0009] A drone collects a target image of the solar tower at the position and direction where the heliostat is located. The drone stops on the mirror surface of the heliostat, and the orientation of the camera of the drone is the same as the orientation of the heliostat.

[0010] Identify the heat collection area of the solar tower in the target image, and determine whether the center of the heat collection area in the target image coincides with the center of the target image. If not, determine the direction and distance of the center of the heat collection area in the target image relative to the center of the target image.

[0011] Control the rotation of the heliostat according to the direction and distance, and collect the target image again. If the center of the heat collection area in the target image collected again coincides with the center of the target image collected again, record the angle of rotation of the heliostat starting from the preset angle to obtain the first rotation angle.

[0012] Correct the preset angle according to the first rotation angle.

[0013] On the other hand, an embodiment of the present application also provides a heliostat error correction system in a tower-type solar thermal power generation system, including:

[0014] A computer for obtaining design data, where the design data includes the preset angle of the heliostat.

[0015] A control mechanism for controlling the heliostat to be corrected to rotate to the preset angle.

[0016] A drone for collecting a target image of the solar tower at the position and direction where the heliostat is located. The drone stops on the mirror surface of the heliostat, and the orientation of the camera of the drone is the same as the orientation of the heliostat.

[0017] The computer identifies the heat collection area of the solar tower in the target image, and determines whether the center of the heat collection area in the target image coincides with the center of the target image. If not, determine the direction and distance of the center of the heat collection area in the target image relative to the center of the target image.

[0018] The control mechanism controls the rotation of the heliostat according to the direction and distance, and the drone collects the target image again. If the center of the heat collection area in the target image collected again coincides with the center of the target image collected again, the computer records the angle of rotation of the heliostat starting from the preset angle to obtain the first rotation angle; correct the preset angle according to the first rotation angle.

[0019] A method and system for correcting the error of a heliostat in a tower-type solar thermal power generation system in the present application have the following advantages:

[0020] Park the drone on the mirror surface of the heliostat to determine whether the mirror surface of the heliostat is facing the heat collection area of the heat collection tower. If it is facing correctly, it means that there is no error in the heliostat. Otherwise, adjust the angle of the heliostat and correct the estimated angle in the design process according to the rotated angle. The method of this application does not need to rely on the light reflected by the heliostat, so there is no requirement for light, and it has a wide range of applications. Moreover, the drone can fly autonomously without the need to pre-install multiple cameras, greatly reducing the complexity of the operation. Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 It is a flowchart of a method for correcting the error of a heliostat in a tower-type solar thermal power generation system provided by an embodiment of the present application.

[0023] Figure 2 It is a schematic diagram of a partial flight route planned by a drone provided by an embodiment of the present application.

[0024] Figure 3 It is a schematic diagram of the analysis process of the reference image captured by the drone provided by an embodiment of the present application.

[0025] Figure 4 It is a schematic diagram of an application scenario of a system for correcting the error of a heliostat in a tower-type solar thermal power generation system provided by an embodiment of the present application.

[0026] Explanation of the reference numerals in the drawings: 100, heliostat; 200, heat collection tower; 300, drone; 400, computer. Detailed Embodiments

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0028] Figure 1 It is a flowchart of a method for correcting the error of a heliostat in a tower-type solar thermal power generation system provided by an embodiment of the present application. An embodiment of the present application provides a method for correcting the error of a heliostat in a tower-type solar thermal power generation system, including the following steps:

[0029] S100, Obtain design data, where the design data includes the preset angles of the heliostat 100.

[0030] Exemplarily, during the design process of the solar thermal power plant, the angles of each heliostat 100 have been estimated in advance. These angles include the horizontal angle and the pitch angle. At these horizontal and pitch angles, the heliostat 100 will face the heat collection area on the heat collection tower 200, that is, the normal line of the center of the heliostat 100 passes through the center of the heat collection area. Therefore, during the calibration process after the installation of the heliostat 100 is completed, the preset angles including the horizontal angle and the pitch angle can be extracted from the design data.

[0031] S110, Control the to-be-calibrated heliostat 100 to rotate to the preset angle.

[0032] Exemplarily, in addition to the mirror surface, the heliostat 100 also includes a bracket for supporting the mirror surface. A control mechanism for driving the mirror surface to rotate in the horizontal and vertical directions is provided on the bracket. These control mechanisms usually adopt a combination of a stepper motor and a gear. The mirror surface of the heliostat 100 is at the initial angle after the installation is completed. This initial angle may be the same as the preset angle or may not be the same. However, regardless of whether they are the same or not, the initial angle and the preset angle will be compared first. If the two are the same, the current state of the heliostat 100 will be maintained. Otherwise, the stepper motor will be driven to rotate, and the mirror surface of the heliostat 100 will be driven by the gear to rotate to the preset angle.

[0033] S120, The drone 300 collects the target image of the heat collection tower 200 at the position and direction of the heliostat 100, where the drone 300 stops on the mirror surface of the heliostat 100, and the orientation of the camera of the drone 300 is the same as the orientation of the heliostat 100.

[0034] Exemplarily, the drone 300 preferably adopts a multi-rotor drone, and a rotatable camera is provided on its main body. The camera rotates to the required angle under the control of the main body and collects images.

[0035] Furthermore, an attitude sensor is provided on the drone 300. The attitude sensor can detect the real-time attitude angle of the drone, and this attitude angle also includes the horizontal angle and the pitch angle. When the drone 300 stops on the mirror surface of the heliostat 100, the drone 300 can collect the current real-time attitude angle and control the camera to rotate to an angle perpendicular to the plane where the main body of the drone 300 is located according to this real-time attitude angle. At this time, since the main body of the drone 300 and the mirror surface of the heliostat 100 are parallel, the camera will also be perpendicular to the mirror surface. If the mirror surface of the heliostat 100 faces the heat collection area, the position of the heat collection area in the target image will be located at the center of the target image at this time. By analyzing the target image, it can be determined whether there is an error in the heliostat 100.

[0036] Further, before the drone 300 lands on the mirror surface of the heliostat 100, it collects a global image of the solar thermal power plant above the central receiver tower 200. After analyzing the global image, it plans the calibration sequence for each heliostat 100. After determining the calibration sequence, the drone 300 lands on the mirror surface of each heliostat 100 in sequence according to the calibration sequence.

[0037] Specifically, as Figure 2 shown, in the solar thermal power plant, the central receiver tower 200 and a large number of heliostats 100 are arranged. The heat collection area is located at the top of the central receiver tower 200, and the heliostats 100 are arranged with the central receiver tower 200 as the center. Before the drone 300 collects the target image of the position where each heliostat 100 is located, it will first collect a global image containing all the heliostats 100 above the central receiver tower 200, identify the central receiver tower 200 and each heliostat 100 in the global image through the recognition model, and then plan the flight route.

[0038] In the embodiment of the present application, the above recognition model can be established based on a convolutional neural network. Before actual use, the recognition model needs to be trained and tested so that the recognition model can accurately identify the central receiver tower 200 and the heliostats 100 in the target image.

[0039] After identifying each heliostat 100, each subsequent heliostat 100 will be connected in series starting from a certain heliostat 100 according to a preset rule to form a flight route formed by connecting the positions of multiple heliostats 100. Specifically, since the longitude and latitude coordinates of each heliostat 100 have been determined during the design and there is almost no error in the longitude and latitude coordinates, the drone 300 can directly obtain the longitude and latitude coordinates of each heliostat 100 determined during the design stage, and then combine all the flight routes to determine the longitude and latitude coordinates of each point that needs to be stopped on the flight route. At this time, the flight route is transformed into a broken line formed by connecting multiple points of longitude and latitude coordinates in sequence. After determining the flight route, the drone 300 will collect the real-time position during the flight using the positioning module and determine whether the real-time position is the same as the longitude and latitude coordinates of the point to be traveled to. If they are the same, it means that the drone 300 has reached above the heliostat 100, and then the target image collection work can be started.

[0040] Further, after the drone 300 lands on the mirror surface of the heliostat 100, the camera of the drone 300 collects the edge image of the heliostat 100, and determines whether the drone 300 is located at the center of the mirror surface of the heliostat 100 according to the edge image. If not, the drone 300 adjusts its position until it is located at the center of the mirror surface of the heliostat 100.

[0041] Specifically, although the latitude and longitude coordinates of each point on the flight route have been determined in the above process, there is still a certain error in controlling the flight of the UAV 300 based solely on the latitude and longitude coordinates. When the UAV 300 flies and lands on a mirror surface, the camera of the UAV 300 will collect an image of the mirror edge at a set angle, and analyze the length of the mirror edge in the edge image. If the length is the same as or not much different from the preset length data, it means that the UAV 300 has landed in the center of the mirror surface, and then the target image can be collected.

[0042] If it is found through the analysis of the edge image that the UAV 300 is not in the center of the mirror surface, the UAV 300 needs to take off and land again. During this process, when the UAV 300 approaches the heliostat 100, the camera faces directly downward to collect the landing image, and analyzes the landing image to determine whether the center of the landing image coincides with the center of the heliostat 100 in the landing image. If they do not coincide, adjust the position of the UAV 300 until the center of the landing image coincides with the center of the heliostat 100 in the landing image, and then the UAV 300 descends and stops on the mirror surface of the heliostat 100.

[0043] Specifically, after collecting the landing image, the recognition model will be used to recognize the mirror surface in the landing image, and then determine the geometric center of the mirror surface in the landing image, and determine whether this geometric center coincides with the center of the landing image. If they coincide, it means that the UAV 300 is directly above the mirror surface of the heliostat 100 at this time, and the UAV 300 can descend vertically and stop at the center of the mirror surface.

[0044] Further, a suction cup is provided at the bottom of the UAV 300, and the suction cup is connected to a vacuum pump. When the UAV 300 stops on the mirror surface of the heliostat 100, the vacuum pump pumps out the air in the suction cup to make the UAV 300 stably stop on the mirror surface of the heliostat 100.

[0045] Specifically, since the heliostat 100 will be in an inclined state when facing the solar collector tower 200, it is necessary to use a suction cup to stably stop the UAV 300 on the mirror surface.

[0046] S130, identify the heat collection area of the solar collector tower 200 in the target image, and judge whether the center of the heat collection area in the target image coincides with the center of the target image. If they do not coincide, determine the direction and distance of the center of the heat collection area in the target image relative to the center of the target image.

[0047] Exemplarily, the recognition model can also be used for the recognition of the heat collection area. It should be understood that the recognition models mentioned above do not represent the same model. These models can be established based on the same neural network, but are trained and tested with their respective pre-prepared training samples and test samples respectively.

[0048] After the heat collection area is identified, the edge of the heat collection area can be determined in the target image, and the geometric center of the closed area surrounded by the edge is the center of the heat collection area in the target image. If this center coincides with or is at a very small distance from the center of the target image, it is considered that the mirror surface of the current heliostat 100 is facing the heat collection area directly, that is, there is no error in the angle of the heliostat 100. If the pixel distance between the two centers exceeds the set threshold, it indicates that there is a large error in the heliostat 100. At this time, the angle of the heliostat 100 needs to be adjusted. Before adjusting the angle, it is necessary to first determine the direction and angle of adjustment. The direction is the direction of the center of the heat collection area in the target image relative to the center of the target image, and the angle can be determined according to the distance between the two centers in the target image.

[0049] S140, control the rotation of the heliostat 100 according to the direction and distance, and collect the target image again. If the center of the heat collection area in the target image collected again coincides with the center of the target image collected again, record the angle of rotation of the heliostat 100 starting from the preset angle to obtain the first rotation angle.

[0050] Exemplarily, if the angle of the heliostat 100 is still not facing the heat collection area directly after adjustment, its angle can be adjusted again until the center of the heat collection area in the target image collected again coincides with the center of the target image collected again.

[0051] S150, correct the preset angle according to the first rotation angle.

[0052] Exemplarily, the corrected preset angle can be obtained by calculating the sum of the first rotation angle and the preset angle.

[0053] Furthermore, in order to ensure that the corrected preset angle can make the sunlight reflected by the heliostat 100 accurately irradiate on the heat collection area, after the first rotation angle is determined, the heliostat 100 rotates to the tracking angle in the automatic tracking mode. The unmanned aerial vehicle 300 collects a reference image at the position and direction of the heliostat 100, identifies the sun and the heat collection area in the reference image, and judges whether the centers of the sun and the heat collection area in the reference image are symmetric about the center of the reference image. If not, adjust the angle of the heliostat 100 until the centers of the sun and the heat collection area in the reference image are symmetric about the center of the reference image. Record the angle of rotation of the heliostat 100 starting from the tracking angle to obtain the second rotation angle, and correct the preset angle according to the first rotation angle and the second rotation angle.

[0054] Specifically, as Figure 3As shown in the figure, the outer rectangle represents the edge of the reference image, the inner rectangle represents the heat collection area, the circle represents the sun, and the cross in the center represents the center of the reference image. Theoretically, if the heliostat 100 reflects sunlight to the heat collection area, then the center of the sun and the center of the heat collection area in the reference image will be on the opposite sides of the center of the reference image respectively, and the distances from both of them to the reference image are the same. According to this principle, by analyzing the reference image, it can be determined whether the tracking angle can accurately reflect sunlight after the heliostat 100 enters the tracking mode at the corrected preset angle.

[0055] If it is found through the analysis of the reference image that the heliostat 100 still cannot accurately reflect sunlight, the angle of the heliostat 100 can be adjusted again until the sunlight is accurately reflected, that is, the centers of the sun and the heat collection area in the reference image are symmetric about the center of the reference image. The second rotation angle obtained at this time can be added to the first rotation angle, and the sum of this sum and the preset angle is the preset angle after secondary correction.

[0056] It should be understood that the sun is required during the secondary correction process. Therefore, the light intensity data can be collected in advance through a light sensor to determine whether there is a sun currently. If there is no sun, the secondary correction is not required.

[0057] The embodiment of the present application also provides a heliostat error correction system in a tower-type solar thermal power generation system, as Figure 4 shown. The system includes:

[0058] A computer 400, configured to obtain design data, where the design data includes the preset angle of the heliostat 100;

[0059] A control mechanism, configured to control the to-be-corrected heliostat 100 to rotate to the preset angle;

[0060] An unmanned aerial vehicle 300, configured to collect a target image of the heat collection tower 200 at the position and direction where the heliostat 100 is located. The unmanned aerial vehicle 300 stops on the mirror surface of the heliostat 100, and the orientation of the camera of the unmanned aerial vehicle 300 is the same as the orientation of the heliostat 100;

[0061] The computer 400 identifies the heat collection area of the heat collection tower 200 in the target image, determines whether the center of the heat collection area in the target image coincides with the center of the target image. If not, it determines the direction and distance of the center of the heat collection area in the target image relative to the center of the target image;

[0062] The control mechanism controls the rotation of the heliostat 100 according to the direction and distance. The UAV 300 collects the target image again. If the center of the heat collection area in the target image collected again coincides with the center of the target image collected again, the computer 400 records the angle at which the heliostat 100 starts to rotate from the preset angle to obtain the first rotation angle; the preset angle is corrected according to the first rotation angle.

[0063] Although the preferred embodiments of the present application have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0064] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these modifications and variations.

Claims

1. A method for correcting the error of heliostats in a tower-type solar thermal power generation system, characterized in that, Including: Obtain design data, where the design data includes the preset angle of the heliostat (100); Control the to-be-corrected heliostat (100) to rotate to the preset angle; Collect a target image of the solar tower (200) at the position and direction of the heliostat (100) by a drone (300), where the drone (300) stops on the mirror surface of the heliostat (100), and the orientation of the camera of the drone (300) is the same as the orientation of the heliostat (100); Identify the heat collection area of the solar tower (200) in the target image, and determine whether the center of the heat collection area in the target image coincides with the center of the target image. If not, determine the direction and distance of the center of the heat collection area in the target image relative to the center of the target image; Control the heliostat (100) to rotate according to the direction and distance, and collect the target image again. If the center of the heat collection area in the re-collected target image coincides with the center of the re-collected target image, record the angle by which the heliostat (100) rotates from the preset angle to obtain the first rotation angle; Correct the preset angle according to the first rotation angle; After determining the first rotation angle, the heliostat (100) rotates to the tracking angle in the automatic tracking mode. The drone (300) collects a reference image at the position and direction of the heliostat (100), identifies the sun and the heat collection area in the reference image, and determines whether the centers of the sun and the heat collection area in the reference image are symmetric about the center of the reference image. If not, adjust the angle of the heliostat (100) until the centers of the sun and the heat collection area in the reference image are symmetric about the center of the reference image, and record the angle by which the heliostat (100) rotates from the tracking angle to obtain the second rotation angle, and correct the preset angle according to the first rotation angle and the second rotation angle.

2. The method for correcting the error of a heliostat in a tower-type solar thermal power generation system according to claim 1, characterized in that, Before the drone (300) stops on the mirror surface of the heliostat (100), collect a global image of the solar power plant above the solar tower (200), analyze the global image to plan the correction sequence for each heliostat (100), and after determining the correction sequence, the drone (300) stops on the mirror surface of each heliostat (100) in sequence according to the correction sequence.

3. The method for correcting the error of a heliostat in a tower-type solar thermal power generation system according to claim 1, characterized in that After the drone (300) stops on the mirror surface of the heliostat (100), the camera of the drone (300) collects an edge image of the heliostat (100), and determines whether the drone (300) is located at the center of the mirror surface of the heliostat (100) according to the edge image. If not, the drone (300) adjusts its position until it is located at the center of the mirror surface of the heliostat (100).

4. A method for correcting the error of a heliostat in a tower-type solar thermal power generation system according to claim 3, characterized in that, When the drone (300) approaches the heliostat (100), the camera faces directly downward to collect landing images, and the landing images are analyzed to determine whether the center of the landing image coincides with the center of the heliostat (100) in the landing image. If not, the position of the drone (300) is adjusted until the center of the landing image coincides with the center of the heliostat (100) in the landing image. At this time, the drone (300) descends and stops on the mirror surface of the heliostat (100).

5. A method for correcting the error of heliostats in a tower-type solar thermal power generation system according to claim 1, characterized in that, A suction cup is provided at the bottom of the drone (300), and the suction cup is connected to a vacuum pump. When the drone (300) stops on the mirror surface of the heliostat (100), the vacuum pump extracts the air in the suction cup, so that the drone (300) stably stops on the mirror surface of the heliostat (100).

6. The method for correcting the error of a heliostat in a tower-type solar thermal power generation system according to claim 1, wherein, Take the sum value of the first rotation angle and the second rotation angle, and use the sum of the sum value and the preset angle as the corrected preset angle.

7. A system applying the method for correcting the heliostat error in the tower solar thermal power generation system according to any one of claims 1-6, characterized in that, Including: A computer (400) for obtaining design data, where the design data includes the preset angle of the heliostat (100); A control mechanism for controlling the to-be-corrected heliostat (100) to rotate to the preset angle; A drone (300) for collecting a target image of the solar tower (200) at the position and direction where the heliostat (100) is located, where the drone (300) stops on the mirror surface of the heliostat (100), and the orientation of the camera of the drone (300) is the same as the orientation of the heliostat (100); The computer (400) identifies the heat collection area of the solar tower (200) in the target image, and determines whether the center of the heat collection area in the target image coincides with the center of the target image. If not, it determines the direction and distance of the center of the heat collection area in the target image relative to the center of the target image; The control mechanism controls the heliostat (100) to rotate according to the direction and distance, and the drone (300) collects the target image again. If the center of the heat collection area in the target image collected again coincides with the center of the target image collected again, the computer (400) records the angle by which the heliostat (100) rotates starting from the preset angle to obtain the first rotation angle; corrects the preset angle according to the first rotation angle; after determining the first rotation angle, the heliostat (100) rotates to the tracking angle in the automatic tracking mode, and the drone (300) collects a reference image at the position and direction where the heliostat (100) is located, identifies the sun and the heat collection area in the reference image, and determines whether the centers of the sun and the heat collection area in the reference image are symmetric about the center of the reference image. If not, adjusts the angle of the heliostat (100) until the centers of the sun and the heat collection area in the reference image are symmetric about the center of the reference image, records the angle by which the heliostat (100) rotates starting from the tracking angle to obtain the second rotation angle, and corrects the preset angle according to the first rotation angle and the second rotation angle.

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