A control method and device of a photovoltaic tracking support and a photovoltaic tracking system

Abstract

This invention discloses a control method, device, and photovoltaic tracking system for a photovoltaic tracking bracket. Based on the current total solar radiation intensity and current clear sky radiation intensity, the current clear sky index is determined. When the current clear sky index is less than a preset index value, cloudy weather is determined. All cloud images collected at the current time and within a first preset time period prior to the current time are acquired, and the solar radiation intensity influence area including the sun's position is extracted. Based on the historical cloud coverage trend within the solar radiation intensity influence area, the future cloud coverage rate is predicted, obtaining the cloud change trend within the solar radiation intensity influence area. This leads to the determination of the future clear sky index corresponding to the future cloud coverage rate. The optimal tracking angle of the photovoltaic tracking bracket is determined based on the magnitude of the future clear sky index. This invention considers the cloud change trend within the solar radiation intensity influence area when determining the optimal tracking angle, thereby effectively avoiding the continuous rotation of the photovoltaic tracking bracket due to complex and changeable weather.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic power generation technology, and more specifically, to a control method, device, and photovoltaic tracking system for a photovoltaic tracking bracket. Background Technology

[0002] In photovoltaic (PV) tracking systems, PV modules are typically mounted on tracking brackets to improve power generation efficiency. These brackets allow the orientation of the PV modules to be adjusted according to sunlight conditions, reducing the angle between the modules and direct sunlight, maximizing irradiance, and thus improving power generation efficiency.

[0003] Currently, photovoltaic (PV) tracking systems primarily use astronomical algorithms to determine the tracking angle of the PV tracking bracket. This method is essentially a solar tracking control method based on calculating the angle of sunlight using astronomical information. However, this method does not consider the influence of weather, leading to significant errors in the determined tracking angle. To improve the accuracy of the tracking angle, some existing tracking algorithms have optimized the above-mentioned issues by incorporating current weather conditions when determining the tracking angle of the PV tracking bracket. Although the optimized tracking algorithms improve the accuracy of the tracking angle to some extent, weather is usually complex and changeable. Relying solely on current weather conditions for solar tracking will cause frequent fluctuations in the tracking angle, resulting in continuous rotation of the PV tracking bracket. This not only leads to a loss of power generation from the PV power plant but also affects the lifespan of the PV tracking bracket. Summary of the Invention

[0004] In view of this, the present invention discloses a control method, device and photovoltaic tracking system for a photovoltaic tracking bracket, which takes into account the weather change trend when determining the optimal tracking angle, mainly the state and change trend of clouds around the sun, thereby effectively avoiding the situation where the photovoltaic tracking bracket rotates continuously due to complex and changeable weather, thereby increasing the power generation of the photovoltaic power station and extending the service life of the photovoltaic tracking bracket.

[0005] A control method for a photovoltaic tracking bracket, applied to a controller of a photovoltaic tracking system, the control method comprising:

[0006] The current clear sky index is determined based on the current total solar radiation intensity incident on the horizontal plane and the current clear sky radiation intensity.

[0007] When the current clear sky index is less than the preset index value, acquire all cloud images collected at the current time and within the first preset time period before the current time.

[0008] Extract the region of solar radiation intensity influence containing the sun's position from each of the cloud images;

[0009] Based on each of the solar radiation intensity influence areas, determine the historical cloud coverage rate within the first preset time period prior to the current moment;

[0010] Predict the future cloud coverage rate for a second preset time period after the current moment based on the changing trends of the historical cloud coverage rates;

[0011] Based on the correlation between cloud coverage and clear sky index, the future clear sky index corresponding to the future cloud coverage is determined.

[0012] The optimal tracking angle of the photovoltaic tracking bracket is determined based on the magnitude of the future clear sky index.

[0013] Optionally, extracting the solar radiation intensity influence area containing the sun's position from each of the cloud images includes:

[0014] The target cloud image is obtained by cropping the edge distortion positions of each cloud image using an image processing library;

[0015] Determine the position of the sun on the target cloud image;

[0016] Using the sun's position as the center point, the area within a preset distance from the center point is extracted as the solar radiation intensity influence area.

[0017] Optionally, determining the sun's position on the target cloud image includes:

[0018] Obtain the current geographical location of the sun, which includes: zenith angle and azimuth angle;

[0019] The position of the sun is determined on the target cloud image based on the zenith angle and the azimuth angle.

[0020] Optionally, determining the historical cloud coverage rate within the first preset time period prior to the current moment based on each of the solar radiation intensity influence areas includes:

[0021] Cloud map features are extracted from each of the solar radiation intensity affected areas using a convolutional neural network, and the cloud coverage area in the solar radiation intensity affected areas is determined based on the cloud map features.

[0022] Based on each cloud coverage area and the corresponding solar radiation intensity affected area, the historical cloud coverage rate of the corresponding cloud image is determined.

[0023] Optionally, based on the correlation between cloud coverage and clear sky index, the future clear sky index corresponding to the future cloud coverage is determined, including:

[0024] Obtain all historical total solar radiation intensity and historical clear-sky radiation intensity within the first preset time period prior to the current moment;

[0025] Based on the historical total solar radiation intensity and the historical clear sky radiation intensity, determine the historical clear sky index within the first preset time period before the current moment to obtain the historical clear sky index sequence.

[0026] The historical clear sky index sequence and the historical cloud coverage sequence are linearly fitted to obtain the correlation between cloud coverage and clear sky index. The historical cloud coverage sequence includes each of the historical cloud coverage rates within the first preset time period before the current time.

[0027] Based on the correlation between cloud coverage and clear sky index, the future clear sky index corresponding to the future cloud coverage is determined.

[0028] Optionally, determining the optimal tracking angle of the photovoltaic tracking bracket based on the future clear sky index includes:

[0029] Determine whether the future clear sky index is less than the preset index value;

[0030] If so, compare the current clear sky index with the future clear sky index;

[0031] If the current clear sky index is not less than the future clear sky index, then the current solar radiation intensity corresponding to the current clear sky index is input into the tilt surface radiation calculation model to obtain the current irradiance value corresponding to each tilt angle of the tilt surface radiation calculation model.

[0032] The tilt angle corresponding to the largest current irradiance value among all the current irradiance values ​​is determined as the optimal tracking angle of the photovoltaic tracking bracket.

[0033] Optional, also includes:

[0034] If the current clear sky index is less than the future clear sky index, then based on the future clear sky index and the clear sky model at the corresponding time, the predicted solar radiation intensity for the second preset time period after the current time is obtained.

[0035] The predicted solar radiation intensity is input into the tilted surface radiation calculation model to obtain the predicted irradiance value corresponding to each tilt angle of the tilted surface radiation calculation model.

[0036] The tilt angle corresponding to the maximum predicted irradiance value among all the predicted irradiance values ​​is determined as the optimal tracking angle of the photovoltaic tracking bracket.

[0037] Optional, also includes:

[0038] If the future clear sky index is not less than the preset index value, then an astronomical algorithm is used to determine the optimal tracking angle of the photovoltaic tracking bracket.

[0039] A control device for a photovoltaic tracking bracket, used in a controller of a photovoltaic tracking system, the control device comprising:

[0040] The current clear sky index determination unit is used to determine the current clear sky index based on the current total solar radiation intensity and the current clear sky radiation intensity incident on the horizontal plane.

[0041] The cloud image acquisition unit is used to acquire all cloud images collected at the current time and within a first preset time period before the current time when the current clear sky index is less than a preset index value.

[0042] A region extraction unit is used to extract the region affected by solar radiation intensity containing the location of the sun from each of the cloud images;

[0043] The historical cloud coverage determination unit is used to determine the historical cloud coverage rate within the first preset time period before the current moment based on each of the solar radiation intensity influence areas.

[0044] The future cloud coverage determination unit is used to predict the future cloud coverage rate for a second preset time period after the current moment based on the changing trends of each of the historical cloud coverage rates.

[0045] The future clear sky index determination unit is used to determine the future clear sky index corresponding to the future cloud coverage rate based on the correlation between cloud coverage rate and clear sky index.

[0046] The tracking angle determination unit is used to determine the optimal tracking angle of the photovoltaic tracking bracket based on the magnitude of the future clear sky index.

[0047] Optionally, the region extraction unit includes:

[0048] The cropping subunit is used to crop the edge distortion positions of each cloud image using an image processing library to obtain the target cloud image;

[0049] A sun position determination subunit is used to determine the sun's position on the target cloud image;

[0050] The region extraction subunit is used to extract the region within a preset distance from the sun's position as the solar radiation intensity influence region.

[0051] Optionally, the solar position determination subunit is specifically used for:

[0052] Obtain the current geographical location of the sun, which includes: zenith angle and azimuth angle;

[0053] The position of the sun is determined on the target cloud image based on the zenith angle and the azimuth angle.

[0054] Optionally, the historical cloud coverage determination unit includes:

[0055] The cloud coverage area determination subunit is used to extract cloud map features from each of the solar radiation intensity influence areas using a convolutional neural network, and determine the cloud coverage area in the solar radiation intensity influence areas based on the cloud map features;

[0056] The historical cloud coverage determination subunit is used to determine the historical cloud coverage of the corresponding cloud image based on each cloud coverage area and the corresponding solar radiation intensity influence area.

[0057] Optionally, the future clear sky index determination unit includes:

[0058] The radiation intensity acquisition subunit is used to acquire all historical total solar radiation intensity and historical clear sky radiation intensity within the first preset time period before the current moment.

[0059] The clear sky index sequence determination subunit is used to determine each historical clear sky index within the first preset time period before the current moment based on each of the historical total solar radiation intensity and each of the historical clear sky radiation intensity, so as to obtain the historical clear sky index sequence.

[0060] A fitting subunit is used to linearly fit the historical clear sky index sequence and the historical cloud coverage sequence to obtain the correlation between the cloud coverage and the clear sky index. The historical cloud coverage sequence includes each of the historical cloud coverage rates within the first preset time period before the current moment.

[0061] The Future Clear Sky Index Determination Subunit is used to determine the Future Clear Sky Index corresponding to the future cloud coverage rate based on the correlation between the cloud coverage rate and the clear sky index.

[0062] Optionally, the tracking angle determination unit includes:

[0063] The judgment subunit is used to determine whether the future clear sky index is less than the preset index value;

[0064] The comparison subunit is used to compare the current clear sky index with the future clear sky index when the judgment subunit determines that it is true.

[0065] The current irradiance value determination subunit is used to input the current solar radiation intensity corresponding to the current clear sky index into the tilt surface radiation calculation model if the current clear sky index is not less than the future clear sky index, so as to obtain the current irradiance value corresponding to each tilt angle of the tilt surface radiation calculation model.

[0066] The first tracking angle determination subunit is used to determine the tilt angle corresponding to the largest current irradiance value among the various current irradiance values ​​as the optimal tracking angle of the photovoltaic tracking bracket.

[0067] Optionally, the tracking angle determination unit further includes:

[0068] The radiation intensity prediction subunit is used to obtain the predicted solar radiation intensity for the second preset time period after the current moment based on the future clear sky index and the clear sky model at the corresponding time if the current clear sky index is less than the future clear sky index.

[0069] The predicted irradiance value determination subunit is used to input the predicted solar radiation intensity into the tilted surface radiation calculation model to obtain the predicted irradiance value corresponding to each tilt angle of the tilted surface radiation calculation model.

[0070] The second tracking angle determination subunit is used to determine the tilt angle corresponding to the largest predicted irradiance value among the predicted irradiance values ​​as the optimal tracking angle of the photovoltaic tracking bracket.

[0071] Optionally, the tracking angle determination unit further includes:

[0072] The third tracking angle determination subunit is used to determine the optimal tracking angle of the photovoltaic tracking bracket using an astronomical algorithm when the judgment subunit determines that it is not.

[0073] A photovoltaic tracking system includes: a photovoltaic module, a photovoltaic tracker, a photovoltaic inverter, and a controller, wherein the controller includes the control device for the photovoltaic tracking bracket described above;

[0074] The controller is communicatively connected to the photovoltaic tracker and the photovoltaic inverter respectively. The photovoltaic tracker is mechanically connected to at least one of the photovoltaic modules, and at least one of the photovoltaic modules is connected to the DC side of the photovoltaic inverter.

[0075] As can be seen from the above technical solution, this invention discloses a control method, device, and photovoltaic tracking system for a photovoltaic tracking bracket. Based on the current total solar radiation intensity and current clear-sky radiation intensity incident on the horizontal plane, the current clear-sky index is determined to determine the current irradiance level. When the current clear-sky index is less than a preset index value, cloudy weather is determined. At this time, all cloud images collected within the current moment and a first preset time period prior to the current moment are acquired. Image recognition technology is used to extract the solar radiation intensity influence area containing the sun's position from each cloud image. Based on the historical cloud coverage change trend within the solar radiation intensity influence area, the future cloud coverage rate for a second preset time period after the current moment is predicted, obtaining the cloud change trend within the solar radiation intensity influence area. According to the correlation between cloud coverage rate and clear-sky index, the future clear-sky index corresponding to the future cloud coverage rate is determined. Therefore, the optimal tracking angle of the photovoltaic tracking bracket is determined based on the magnitude of the future clear-sky index. This invention considers the cloud change trend within the solar radiation intensity influence area when determining the optimal tracking angle, effectively avoiding the continuous rotation of the photovoltaic tracking bracket due to complex and changeable weather, thereby improving the power generation of the photovoltaic power station and extending the service life of the photovoltaic tracking bracket. Attached Figure Description

[0076] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the published drawings without creative effort.

[0077] Figure 1 This is a flowchart of a control method for a photovoltaic tracking bracket disclosed in an embodiment of the present invention;

[0078] Figure 2 This is a flowchart of a method for determining the area affected by solar radiation intensity, as disclosed in an embodiment of the present invention.

[0079] Figure 3 This is a flowchart of a method for determining the future clear sky index disclosed in an embodiment of the present invention;

[0080] Figure 4 This is a flowchart of a method for determining the optimal tracking angle of a photovoltaic tracking bracket based on a future clear sky index, as disclosed in an embodiment of the present invention.

[0081] Figure 5 This is a schematic diagram of the structure of a control device for a photovoltaic tracking bracket disclosed in an embodiment of the present invention. Detailed Implementation

[0082] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0083] This invention discloses a control method, device, and photovoltaic tracking system for a photovoltaic (PV) tracking bracket. Based on the current total solar radiation intensity and current clear-sky radiation intensity incident on the horizontal plane, a current clear-sky index is determined to establish the current irradiance level. When the current clear-sky index is less than a preset index value, cloudy weather is identified. At this point, all cloud images collected within the current moment and a first preset time period prior to the current moment are acquired. Image recognition technology is used to extract the solar radiation intensity influence area, including the sun's position, from each cloud image. Based on the historical cloud coverage trend within the solar radiation intensity influence area, the future cloud coverage rate for a second preset time period after the current moment is predicted, obtaining the cloud change trend within the solar radiation intensity influence area. Based on the correlation between cloud coverage rate and the clear-sky index, the future clear-sky index corresponding to the future cloud coverage rate is determined. Therefore, the optimal tracking angle of the PV tracking bracket is determined based on the magnitude of the future clear-sky index. This invention considers the cloud change trend within the solar radiation intensity influence area when determining the optimal tracking angle, effectively avoiding the continuous rotation of the PV tracking bracket due to complex and changeable weather, thereby increasing the power generation of the photovoltaic power station and extending the service life of the PV tracking bracket.

[0084] See Figure 1 The present invention discloses a flowchart of a control method for a photovoltaic tracking bracket. This method is applied to the controller of a photovoltaic tracking system, and the control method includes:

[0085] Step S101: Determine the current clear sky index based on the current total solar radiation intensity incident on the horizontal plane and the current clear sky radiation intensity;

[0086] In practical applications, the current total solar radiation intensity incident on the horizontal plane can be collected using an irradiance meter, and the current clear-sky radiation intensity at the corresponding moment can be calculated. The calculation process for the current clear-sky radiation intensity can be found in existing mature solutions, and will not be elaborated here.

[0087] The clear sky index, also known as the clear sky factor, is the ratio of the total solar radiation intensity incident on the horizontal plane to the clear sky radiation intensity, with a value between 0 and 1.

[0088] The formula for calculating the clear sky index k is as follows:

[0089] k=I m / I clear ;

[0090] In the formula, I m I represents the total solar radiation intensity incident on a horizontal plane. clear This indicates the intensity of radiation in clear sky.

[0091] In this embodiment, the current total solar radiation intensity refers to the total solar radiation intensity incident on the horizontal plane at the current moment, and the current clear sky radiation intensity refers to the clear sky radiation intensity at the current moment.

[0092] Step S102: When the current clear sky index is less than the preset index value, acquire all cloud images collected at the current time and within the first preset time period before the current time.

[0093] This embodiment determines the current weather condition based on the size of the clear sky index k.

[0094] Since the most direct influencing factor on the tracking angle is the direct sunlight ratio, which is the ratio of direct sunlight to diffused sunlight, when the direct sunlight ratio is greater than a certain value (e.g., 1), direct sunlight becomes the main component of the total horizontal solar radiation. In this case, the optimal tracking angle is the one calculated using astronomical algorithms, where the photovoltaic module's angle in the east-west direction is perpendicular to the sunlight. When the direct sunlight ratio > 1, the corresponding k value is approximately k > 0.5, where 0.5 is a preset exponent value. The preset exponent value includes, but is not limited to, 0.5, and is determined based on actual needs; this invention does not limit this value.

[0095] The higher the clear sky index k, the clearer the sky. When the clear sky index k is close to 1 or slightly greater than 1, it indicates that the weather is clear. When 0.5 < k < 1, it indicates that there are cirrus clouds or stratus clouds in the sky. In this case, although the clouds affect the direct sunlight, the optimal tracking angle is still the tracking angle calculated by astronomical algorithm.

[0096] If the current clear sky index is lower than the preset index value, such as k < 0.5, cumulus or nimbostratus clouds may be present in the sky. When cumulus or nimbostratus clouds block the sun, ground radiation attenuation is significant. Nimbostratus clouds are relatively stable, basically covering the entire sky, and the total horizontal radiation at the ground remains at a low level; however, cumulus clouds are affected by atmospheric wind fields and other meteorological conditions, and their changes and movement speeds are relatively fast. If the support control angle is adjusted only based on the current irradiance level, it may cause frequent angle fluctuations and power generation loss. Therefore, further judgment is needed in this situation.

[0097] In this embodiment, if the current clear sky index is less than the preset index value, then all cloud images collected by the all-sky camera within the current time and the first preset time period before the current time are obtained.

[0098] The value of the first preset time period is determined according to actual needs, and this invention does not limit it.

[0099] Assuming the first preset time period is 5 minutes, and the all-sky camera can capture cloud images at 30-second intervals, then a total of 10 cloud images will be captured within 5 minutes.

[0100] All-sky cameras are preferred over all-sky fisheye cameras, which are less expensive than all-sky imagers.

[0101] Step S103: Extract the solar radiation intensity influence area containing the sun's position from each of the cloud images;

[0102] Since direct solar radiation is mainly affected by clouds around the sun, the cloud cover in the part far from the sun contributes little to the change in direct solar radiation. Therefore, it is only necessary to extract the area of ​​solar radiation intensity influence containing the sun's position from each cloud image and predict the cloud change trend within the area of ​​solar radiation intensity influence to obtain a relatively accurate prediction result of direct solar radiation.

[0103] Step S104: Determine the historical cloud coverage rate within the first preset time period before the current moment based on each of the solar radiation intensity influence areas;

[0104] Cloud coverage rate, also known as the proportion of cloud-covered area, is specifically the ratio of the cloud-covered area to the area affected by solar radiation intensity.

[0105] Cloud coverage R ci The expression is as follows:

[0106] R ci = A ci / A;

[0107] In the formula, A represents the region affected by solar radiation intensity. ci Indicates the area covered by clouds.

[0108] In this embodiment, the historical cloud coverage rate refers to the cloud coverage rate corresponding to the cloud images collected within a first preset time period before the current moment.

[0109] Step S105: Based on the changing trends of the historical cloud coverage rates, predict the future cloud coverage rate for the second preset time period after the current moment;

[0110] Assuming the first preset time period is 5 minutes and the data acquisition interval can be 30 seconds, then a total of 10 cloud images will be acquired within 5 minutes. The historical cloud coverage rate corresponding to each image is as follows: R c1 R c2 R c3 R c4 R c5 R c6 Rc7 R c8 R c9 and R c10 .

[0111] Therefore, the historical cloud coverage sequence R from 5 minutes prior to the current moment c =[ R c1 R c2 R c3 R c4 R c5 R c6 R c7 R c8 R c9 R c10 . ]

[0112] Assuming clouds are rigid bodies, related studies have shown that this assumption can achieve ideal computational results in ultra-short-term forecasting (within 10 minutes). According to R... c By observing the changing trend, the future cloud coverage rate for the second preset time period after the current moment can be calculated, such as the future cloud coverage rate R for the next five minutes after the current moment. c11 .

[0113] Historical cloud coverage trends can be obtained through simple linear trend calculations or other fitting methods.

[0114] Step S106: Determine the future clear sky index corresponding to the future cloud coverage rate based on the correlation between cloud coverage rate and clear sky index;

[0115] The correlation between cloud coverage and clear sky index can be obtained through linear fitting.

[0116] Step S107: Determine the optimal tracking angle of the photovoltaic tracking bracket based on the magnitude of the future clear sky index.

[0117] The magnitude of the future clear sky index can determine whether the sky will be clear or contain cirrus or stratus clouds, thus determining the optimal tracking angle for the photovoltaic tracking bracket.

[0118] In summary, this invention discloses a control method for a photovoltaic tracking bracket. Based on the current total solar radiation intensity and the current clear sky radiation intensity incident on the horizontal plane, a current clear sky index is determined to establish the current irradiance level. When the current clear sky index is less than a preset index value, cloudy weather is identified. At this point, all cloud images collected within the current moment and a first preset time period prior to the current moment are acquired. Image recognition technology is used to extract the solar radiation intensity influence area containing the sun's position from each cloud image. Based on the historical cloud coverage trend within the solar radiation intensity influence area, the future cloud coverage rate for a second preset time period after the current moment is predicted, obtaining the cloud change trend within the solar radiation intensity influence area. Based on the correlation between cloud coverage rate and the clear sky index, the future clear sky index corresponding to the future cloud coverage rate is determined. Therefore, the optimal tracking angle of the photovoltaic tracking bracket is determined based on the magnitude of the future clear sky index. This invention considers the cloud change trend within the solar radiation intensity influence area when determining the optimal tracking angle, effectively avoiding the continuous rotation of the photovoltaic tracking bracket due to complex and changeable weather, thereby increasing the power generation of the photovoltaic power station and extending the service life of the photovoltaic tracking bracket.

[0119] To further optimize the above embodiments, see [link to relevant documentation]. Figure 2 The flowchart of a method for determining the area affected by solar radiation intensity disclosed in this embodiment of the invention, specifically step S103 includes:

[0120] Step S201: Use an image processing library to crop the edge distortion positions of each cloud image to obtain the target cloud image;

[0121] In practical applications, the OpenCV image processing library can be used to batch crop the edge distortion locations of multiple cloud images.

[0122] OpenCV is a cross-platform computer vision and machine learning software library released under the Apache 2.0 license (open source), which can run on Linux, Windows, Android, and Mac OS operating systems. It is lightweight and efficient—consisting of a series of C functions and a small number of C++ classes—while also providing interfaces for languages ​​such as Python, Ruby, and MATLAB, implementing many common algorithms in image processing and computer vision.

[0123] Step S202: Determine the position of the sun on the target cloud image;

[0124] Specifically, the current geographical location of the sun is obtained, including its zenith angle and azimuth angle; based on the current zenith angle and azimuth angle of the sun, the sun's position is determined on the target cloud image.

[0125] The zenith angle is the angle between the direction of incident light and the zenith direction.

[0126] Azimuth angle, also known as horizontal longitude (Az), is one of the methods for measuring the angular difference between objects on a plane. It is the horizontal angle between the north-pointing line at a given point and the target direction line in a clockwise direction.

[0127] Step S203: Using the sun's position as the center point, extract the area within a preset distance range from the center point as the solar radiation intensity influence area.

[0128] The preset distance range is adjusted appropriately based on the number of pixels in the cloud map, such as 30 pixels. This invention does not limit this range.

[0129] In summary, this invention obtains a relatively accurate target cloud image by using an image processing library to crop the edge distortion positions of the cloud image, thereby improving the reliability of the solar radiation intensity-affected area extracted from the target cloud image.

[0130] To further optimize the above embodiments, step S104 may specifically include:

[0131] Cloud map features are extracted from each solar radiation intensity affected area using a convolutional neural network, and the cloud coverage area in the solar radiation intensity affected area is determined based on the cloud map features.

[0132] Based on the cloud coverage area and the corresponding solar radiation intensity affected area, the historical cloud coverage rate of the corresponding cloud image is determined.

[0133] Specifically, the ratio of each cloud coverage area to the corresponding solar radiation intensity affected area is determined as the historical cloud coverage rate of the corresponding cloud image.

[0134] To further optimize the above embodiments, see [link to relevant documentation]. Figure 3 The flowchart of a method for determining the future clear sky index disclosed in this embodiment of the invention, specifically step S106, may include:

[0135] Step S301: Obtain all historical total solar radiation intensity and historical clear sky radiation intensity within the first preset time period before the current moment;

[0136] Step S302: Based on each of the historical total solar radiation intensity and each of the historical clear sky radiation intensity, determine each of the historical clear sky indices within the first preset time period before the current moment, and obtain the historical clear sky index sequence;

[0137] In practical applications, the historical clear sky index is obtained by quotienting the total historical solar radiation intensity for each historical period with the corresponding historical clear sky radiation intensity.

[0138] Assuming the first preset time period before the current moment is 5 minutes, and the time interval between collecting historical total solar radiation intensity and historical clear sky radiation intensity is 30 seconds, then a total of 10 sets of correspondences between historical total solar radiation intensity and historical clear sky radiation intensity were collected within 5 minutes. The historical clear sky index sequence for the 5 minutes before the current time is calculated as k. c =[k c1 k c2 k c3 k c4 k c5 k c6 k c7 k c8 k c9 k c10 ].

[0139] Step S303: Perform linear fitting on the historical clear sky index sequence and the historical cloud coverage sequence to obtain the correlation between the cloud coverage and the clear sky index;

[0140] The historical cloud coverage sequence includes: each of the historical cloud coverage rates within the first preset time period prior to the current moment.

[0141] Assuming the first preset time period before the current moment is 5 minutes, the historical cloud coverage sequence R for the 5 minutes before the current moment is... c =[ R c1 R c2 R c3 R c4 R c5 R c6 R c7 R c8 R c9 R c10 . ]

[0142] Let the historical clear sky index sequence be k. c Compared with historical cloud coverage sequence R c Perform linear fitting to obtain the correlation between cloud cover and clear sky index, such as the fitted relationship formula. Based on this fitted relationship, the future clear sky index corresponding to the future cloud coverage rate can be obtained. .

[0143] Step S304: Based on the correlation between cloud coverage and clear sky index, determine the future clear sky index corresponding to the future cloud coverage.

[0144] To further optimize the above embodiments, see [link to relevant documentation]. Figure 4The present invention discloses a flowchart of a method for determining the optimal tracking angle of a photovoltaic tracking bracket based on a future clear sky index. The method includes:

[0145] Step S401: Determine whether the future clear sky index is less than the preset index value. If so, proceed to step S402.

[0146] The power generation under low irradiance conditions is less sensitive to angle than that under high irradiance conditions. In other words, the change in power generation caused by angle changes under low irradiance is much smaller than the change in power generation caused by angle changes under high irradiance.

[0147] Assuming a preset index value of 0.5, if the future clear sky index... If the value is less than 0.5, the optimal tracking angle is determined based on the larger of the current clear sky index and the future clear sky index.

[0148] Step S402: Compare the current clear sky index with the future clear sky index;

[0149] Step S403: If the current clear sky index is not less than the future clear sky index, then input the current solar radiation intensity corresponding to the current clear sky index into the tilt surface radiation calculation model to obtain the current irradiance value corresponding to each tilt angle of the tilt surface radiation calculation model.

[0150] It should be noted that the current clear sky index corresponds to the solar radiation intensity incident on the horizontal plane. The tilted surface irradiance calculation model has tilt angle ranges set based on the rotation range of the photovoltaic tracking bracket, such as -45°~45° or -60°~60°. By inputting the current solar radiation intensity into the tilted surface irradiance calculation model, the current irradiance value corresponding to each tilt angle can be obtained.

[0151] Step S404: Determine the tilt angle corresponding to the largest current irradiance value among all the current irradiance values ​​as the optimal tracking angle of the photovoltaic tracking bracket.

[0152] In this embodiment, the tilt angle corresponding to the maximum current irradiance value is selected as the optimal tracking angle for the photovoltaic tracking bracket.

[0153] To further optimize the above embodiment, after step S402, the following may also be included:

[0154] Step S405: If the future clear sky index is less than the future clear sky index, then based on the future clear sky index and the clear sky model at the corresponding time, obtain the predicted solar radiation intensity for the second preset time period after the current time.

[0155] In this embodiment, the future clear sky index is multiplied by the clear sky model at the corresponding time to obtain the predicted solar radiation intensity for the second preset time period after the current time, such as the predicted solar radiation intensity for the next 5 minutes after the current time.

[0156] Step S406: Input the predicted solar radiation intensity into the tilted surface radiation calculation model to obtain the predicted irradiance value corresponding to each tilt angle of the tilted surface radiation calculation model.

[0157] In this embodiment, the predicted solar radiation intensity is the solar radiation intensity incident on the horizontal plane. The tilted surface radiation calculation model has a tilt angle range set based on the rotation range of the photovoltaic tracking bracket, such as -45°~45° or -60°~60°. By inputting the predicted solar radiation intensity into the tilted surface radiation calculation model, the predicted irradiance value corresponding to each tilt angle can be obtained.

[0158] Step S407: Determine the tilt angle corresponding to the maximum predicted irradiance value among all predicted irradiance values ​​as the optimal tracking angle for the photovoltaic tracking bracket.

[0159] To further optimize the above embodiments, when step S401 determines that it is not true, the method further includes:

[0160] Step S408: Use an astronomical algorithm to determine the optimal tracking angle of the photovoltaic tracking bracket.

[0161] When the future clear sky index is not less than the preset index value, such as the future clear sky index A value of ≥0.5 indicates that the influence of clouds on direct sunlight will decrease in the second preset time period after the current moment. If the optimal tracking angle corresponding to the current irradiance value is used, it will cause a loss of power generation and may also cause the photovoltaic tracking bracket to rotate frequently. Therefore, in this case, the optimal tracking angle of the photovoltaic tracking bracket will be determined by the angle corresponding to the moment with the highest clear sky index, and the astronomical algorithm will be executed at this time.

[0162] Corresponding to the above method embodiments, the present invention also discloses a control device for a photovoltaic tracking bracket.

[0163] See Figure 5 This invention discloses a schematic diagram of a control device for a photovoltaic tracking bracket. This device is used as a controller in a photovoltaic tracking system and includes...

[0164] The current clear sky index determination unit 501 is used to determine the current clear sky index based on the current total solar radiation intensity and the current clear sky radiation intensity incident on the horizontal plane.

[0165] In practical applications, the current total solar radiation intensity incident on the horizontal plane can be collected using an irradiance meter, and the current clear-sky radiation intensity at the corresponding moment can be calculated. The calculation process for the current clear-sky radiation intensity can be found in existing mature solutions, and will not be elaborated here.

[0166] The clear sky index, also known as the clear sky factor, is the ratio of the total solar radiation intensity incident on the horizontal plane to the clear sky radiation intensity, with a value between 0 and 1.

[0167] The formula for calculating the clear sky index k is as follows:

[0168] k=I m / I clear ;

[0169] In the formula, I m I represents the total solar radiation intensity incident on a horizontal plane. clear This indicates the intensity of radiation in clear sky.

[0170] In this embodiment, the current total solar radiation intensity refers to the total solar radiation intensity incident on the horizontal plane at the current moment, and the current clear sky radiation intensity refers to the clear sky radiation intensity at the current moment.

[0171] The cloud image acquisition unit 502 is used to acquire all cloud images collected at the current time and within a first preset time period before the current time when the current clear sky index is less than a preset index value.

[0172] This embodiment determines the current weather condition based on the size of the clear sky index k.

[0173] Region extraction unit 503 is used to extract the solar radiation intensity influence area containing the sun's position from each of the cloud images;

[0174] Since direct solar radiation is mainly affected by clouds around the sun, the cloud cover in the part far from the sun contributes little to the change in direct solar radiation. Therefore, it is only necessary to extract the area of ​​solar radiation intensity influence containing the sun's position from each cloud image and predict the cloud change trend within the area of ​​solar radiation intensity influence to obtain a relatively accurate prediction result of direct solar radiation.

[0175] Historical cloud coverage determination unit 504 is used to determine the historical cloud coverage rate within the first preset time period before the current moment based on each of the solar radiation intensity influence areas.

[0176] Cloud coverage rate, also known as the proportion of cloud-covered area, is specifically the ratio of the cloud-covered area to the area affected by solar radiation intensity.

[0177] The future cloud coverage determination unit 505 is used to predict the future cloud coverage rate for a second preset time period after the current moment based on the changing trend of each of the historical cloud coverage rates.

[0178] Assuming clouds are rigid bodies, related studies have shown that this assumption can achieve ideal computational results in ultra-short-term forecasting (within 10 minutes). According to R... cBy observing the changing trend, the future cloud coverage rate for the second preset time period after the current moment can be calculated, such as the future cloud coverage rate R for the next five minutes after the current moment. c11 .

[0179] Historical cloud coverage trends can be obtained through simple linear trend calculations or other fitting methods.

[0180] The future clear sky index determination unit 506 is used to determine the future clear sky index corresponding to the future cloud coverage rate based on the correlation between cloud coverage rate and clear sky index.

[0181] The tracking angle determination unit 507 is used to determine the optimal tracking angle of the photovoltaic tracking bracket based on the magnitude of the future clear sky index.

[0182] The magnitude of the future clear sky index can determine whether the sky will be clear or contain cirrus or stratus clouds, thus determining the optimal tracking angle for the photovoltaic tracking bracket.

[0183] In summary, this invention discloses a control method for a photovoltaic tracking bracket. Based on the current total solar radiation intensity and the current clear sky radiation intensity incident on the horizontal plane, a current clear sky index is determined to establish the current irradiance level. When the current clear sky index is less than a preset index value, cloudy weather is identified. At this point, all cloud images collected within the current moment and a first preset time period prior to the current moment are acquired. Image recognition technology is used to extract the solar radiation intensity influence area containing the sun's position from each cloud image. Based on the historical cloud coverage trend within the solar radiation intensity influence area, the future cloud coverage rate for a second preset time period after the current moment is predicted, obtaining the cloud change trend within the solar radiation intensity influence area. Based on the correlation between cloud coverage rate and the clear sky index, the future clear sky index corresponding to the future cloud coverage rate is determined. Therefore, the optimal tracking angle of the photovoltaic tracking bracket is determined based on the magnitude of the future clear sky index. This invention considers the cloud change trend within the solar radiation intensity influence area when determining the optimal tracking angle, effectively avoiding the continuous rotation of the photovoltaic tracking bracket due to complex and changeable weather, thereby increasing the power generation of the photovoltaic power station and extending the service life of the photovoltaic tracking bracket.

[0184] To further optimize the above embodiments, the region extraction unit 503 may include:

[0185] The cropping subunit is used to crop the edge distortion positions of each cloud image using an image processing library to obtain the target cloud image;

[0186] A sun position determination subunit is used to determine the sun's position on the target cloud image;

[0187] The region extraction subunit is used to extract the region within a preset distance from the sun's position as the solar radiation intensity influence region.

[0188] To further optimize the above embodiments, the solar position determination subunit is specifically used for:

[0189] Obtain the current geographical location of the sun, which includes: zenith angle and azimuth angle;

[0190] The position of the sun is determined on the target cloud image based on the zenith angle and the azimuth angle.

[0191] To further optimize the above embodiments, the historical cloud coverage determination unit 504 may include:

[0192] The cloud coverage area determination subunit is used to extract cloud map features from each of the solar radiation intensity influence areas using a convolutional neural network, and determine the cloud coverage area in the solar radiation intensity influence areas based on the cloud map features;

[0193] The historical cloud coverage determination subunit is used to determine the historical cloud coverage of the corresponding cloud image based on each cloud coverage area and the corresponding solar radiation intensity influence area.

[0194] To further optimize the above embodiments, the clear sky index determination unit may include:

[0195] The radiation intensity acquisition subunit is used to acquire all historical total solar radiation intensity and historical clear sky radiation intensity within the first preset time period before the current moment.

[0196] The clear sky index sequence determination subunit is used to determine each historical clear sky index within the first preset time period before the current moment based on each of the historical total solar radiation intensity and each of the historical clear sky radiation intensity, so as to obtain the historical clear sky index sequence.

[0197] A fitting subunit is used to linearly fit the historical clear sky index sequence and the historical cloud coverage sequence to obtain the correlation between the cloud coverage and the clear sky index. The historical cloud coverage sequence includes each of the historical cloud coverage rates within the first preset time period before the current moment.

[0198] The Future Clear Sky Index Determination Subunit is used to determine the Future Clear Sky Index corresponding to the future cloud coverage rate based on the correlation between the cloud coverage rate and the clear sky index.

[0199] To further optimize the above embodiments, the tracking angle determination unit may include:

[0200] The judgment subunit is used to determine whether the future clear sky index is less than the preset index value;

[0201] The comparison subunit is used to compare the current clear sky index with the future clear sky index when the judgment subunit determines that it is true.

[0202] The current irradiance value determination subunit is used to input the current solar radiation intensity corresponding to the current clear sky index into the tilt surface radiation calculation model if the current clear sky index is not less than the future clear sky index, so as to obtain the current irradiance value corresponding to each tilt angle of the tilt surface radiation calculation model.

[0203] The first tracking angle determination subunit is used to determine the tilt angle corresponding to the largest current irradiance value among the various current irradiance values ​​as the optimal tracking angle of the photovoltaic tracking bracket.

[0204] To further optimize the above embodiments, the tracking angle determination unit may further include:

[0205] The radiation intensity prediction subunit is used to obtain the predicted solar radiation intensity for the second preset time period after the current moment based on the future clear sky index and the clear sky model at the corresponding time if the current clear sky index is less than the future clear sky index.

[0206] The predicted irradiance value determination subunit is used to input the predicted solar radiation intensity into the tilted surface radiation calculation model to obtain the predicted irradiance value corresponding to each tilt angle of the tilted surface radiation calculation model.

[0207] The second tracking angle determination subunit is used to determine the tilt angle corresponding to the largest predicted irradiance value among the predicted irradiance values ​​as the optimal tracking angle of the photovoltaic tracking bracket.

[0208] To further optimize the above embodiments, the tracking angle determination unit 507 may further include:

[0209] The third tracking angle determination subunit is used to determine the optimal tracking angle of the photovoltaic tracking bracket using an astronomical algorithm when the judgment subunit determines that it is not.

[0210] It should be noted that for the specific working principles of each component in the device embodiment, please refer to the corresponding section of the method embodiment, which will not be repeated here.

[0211] The present invention also discloses a photovoltaic tracking system, comprising: a photovoltaic module, a photovoltaic tracker, a photovoltaic inverter, and a controller, wherein the controller includes the control device of the photovoltaic tracking bracket in the above embodiments;

[0212] The controller is communicatively connected to the photovoltaic tracker and the photovoltaic inverter respectively. The photovoltaic tracker is mechanically connected to at least one of the photovoltaic modules, and at least one of the photovoltaic modules is connected to the DC side of the photovoltaic inverter.

[0213] The control process of the photovoltaic tracking system over the photovoltaic tracking bracket can be found in the corresponding section of the above embodiments, and will not be repeated here.

[0214] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0215] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0216] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those 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 invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control method for a photovoltaic tracking bracket, characterized in that, A controller applied to a photovoltaic tracking system, the control method comprising: The current clear sky index is determined based on the current total solar radiation intensity incident on the horizontal plane and the current clear sky radiation intensity. When the current clear sky index is less than the preset index value, acquire all cloud images collected at the current time and within the first preset time period before the current time. Extract the region of solar radiation intensity influence containing the sun's position from each of the cloud images; Based on each of the solar radiation intensity influence areas, determine the historical cloud coverage rate within the first preset time period prior to the current moment; Predict the future cloud coverage rate for a second preset time period after the current moment based on the changing trends of the historical cloud coverage rates; Based on the correlation between cloud coverage and clear sky index, the future clear sky index corresponding to the future cloud coverage is determined. The optimal tracking angle of the photovoltaic tracking bracket is determined based on the magnitude of the future clear sky index.

2. The control method according to claim 1, characterized in that, The step of extracting the solar radiation intensity influence area containing the sun's position from each of the cloud images includes: The target cloud image is obtained by cropping the edge distortion positions of each cloud image using an image processing library; Determine the position of the sun on the target cloud image; Using the sun's position as the center point, the area within a preset distance from the center point is extracted as the solar radiation intensity influence area.

3. The control method according to claim 2, characterized in that, Determining the position of the sun on the target cloud image includes: Obtain the current geographical location of the sun, which includes: zenith angle and azimuth angle; The position of the sun is determined on the target cloud image based on the zenith angle and the azimuth angle.

4. The control method according to claim 1, characterized in that, Determining the historical cloud coverage rate within the first preset time period prior to the current moment based on each of the solar radiation intensity influence areas includes: Cloud map features are extracted from each of the solar radiation intensity affected areas using a convolutional neural network, and the cloud coverage area in the solar radiation intensity affected areas is determined based on the cloud map features. Based on each cloud coverage area and the corresponding solar radiation intensity affected area, the historical cloud coverage rate of the corresponding cloud image is determined.

5. The control method according to claim 1, characterized in that, Based on the correlation between cloud coverage and clear sky index, the future clear sky index corresponding to the future cloud coverage is determined, including: Obtain all historical total solar radiation intensity and historical clear-sky radiation intensity within the first preset time period prior to the current moment; Based on the historical total solar radiation intensity and the historical clear sky radiation intensity, determine the historical clear sky index within the first preset time period before the current moment to obtain the historical clear sky index sequence. The historical clear sky index sequence and the historical cloud coverage sequence are linearly fitted to obtain the correlation between the cloud coverage and the clear sky index. The historical cloud coverage sequence includes the historical cloud coverage rates within the first preset time period before the current time. Based on the correlation between cloud coverage and clear sky index, the future clear sky index corresponding to the future cloud coverage is determined.

6. The control method according to claim 1, characterized in that, Determining the optimal tracking angle of the photovoltaic tracking bracket based on the future clear sky index includes: Determine whether the future clear sky index is less than the preset index value; If so, compare the current clear sky index with the future clear sky index; If the current clear sky index is not less than the future clear sky index, then the current solar radiation intensity corresponding to the current clear sky index is input into the tilt surface radiation calculation model to obtain the current irradiance value corresponding to each tilt angle of the tilt surface radiation calculation model. The tilt angle corresponding to the largest current irradiance value among all the current irradiance values ​​is determined as the optimal tracking angle of the photovoltaic tracking bracket.

7. The control method according to claim 6, characterized in that, Also includes: If the current clear sky index is less than the future clear sky index, then based on the future clear sky index and the clear sky model at the corresponding time, the predicted solar radiation intensity for the second preset time period after the current time is obtained. The predicted solar radiation intensity is input into the tilted surface radiation calculation model to obtain the predicted irradiance value corresponding to each tilt angle of the tilted surface radiation calculation model. The tilt angle corresponding to the maximum predicted irradiance value among all the predicted irradiance values ​​is determined as the optimal tracking angle of the photovoltaic tracking bracket.

8. The control method according to claim 6, characterized in that, Also includes: If the future clear sky index is not less than the preset index value, then an astronomical algorithm is used to determine the optimal tracking angle of the photovoltaic tracking bracket.

9. A control device for a photovoltaic tracking bracket, characterized in that, A controller for a photovoltaic tracking system, the control device comprising: The current clear sky index determination unit is used to determine the current clear sky index based on the current total solar radiation intensity and the current clear sky radiation intensity incident on the horizontal plane. The cloud image acquisition unit is used to acquire all cloud images collected at the current time and within a first preset time period before the current time when the current clear sky index is less than a preset index value. A region extraction unit is used to extract the region affected by solar radiation intensity containing the location of the sun from each of the cloud images; The historical cloud coverage determination unit is used to determine the historical cloud coverage rate within the first preset time period before the current moment based on each of the solar radiation intensity influence areas. The future cloud coverage determination unit is used to predict the future cloud coverage rate for a second preset time period after the current moment based on the changing trends of each of the historical cloud coverage rates. The future clear sky index determination unit is used to determine the future clear sky index corresponding to the future cloud coverage rate based on the correlation between cloud coverage rate and clear sky index. The tracking angle determination unit is used to determine the optimal tracking angle of the photovoltaic tracking bracket based on the magnitude of the future clear sky index.

10. The control device according to claim 9, characterized in that, The region extraction unit includes: The cropping subunit is used to crop the edge distortion positions of each cloud image using an image processing library to obtain the target cloud image; A sun position determination subunit is used to determine the sun's position on the target cloud image; The region extraction subunit is used to extract the region within a preset distance from the sun's position as the solar radiation intensity influence region.

11. The control device according to claim 10, characterized in that, The solar position determination subunit is specifically used for: Obtain the current geographical location of the sun, which includes: zenith angle and azimuth angle; The position of the sun is determined on the target cloud image based on the zenith angle and the azimuth angle.

12. The control device according to claim 9, characterized in that, The historical cloud coverage determination unit includes: The cloud coverage area determination subunit is used to extract cloud map features from each of the solar radiation intensity influence areas using a convolutional neural network, and determine the cloud coverage area in the solar radiation intensity influence areas based on the cloud map features; The historical cloud coverage determination subunit is used to determine the historical cloud coverage of the corresponding cloud image based on each cloud coverage area and the corresponding solar radiation intensity influence area.

13. The control device according to claim 9, characterized in that, The future clear sky index determination unit includes: The radiation intensity acquisition subunit is used to acquire all historical total solar radiation intensity and historical clear sky radiation intensity within the first preset time period before the current moment. The clear sky index sequence determination subunit is used to determine each historical clear sky index within the first preset time period before the current moment based on each of the historical total solar radiation intensity and each of the historical clear sky radiation intensity, so as to obtain the historical clear sky index sequence. A fitting subunit is used to linearly fit the historical clear sky index sequence and the historical cloud coverage sequence to obtain the correlation between the cloud coverage and the clear sky index. The historical cloud coverage sequence includes each of the historical cloud coverage rates within the first preset time period before the current moment. The Future Clear Sky Index Determination Subunit is used to determine the Future Clear Sky Index corresponding to the future cloud coverage rate based on the correlation between the cloud coverage rate and the clear sky index.

14. The control device according to claim 9, characterized in that, The tracking angle determination unit includes: The judgment subunit is used to determine whether the future clear sky index is less than the preset index value; The comparison subunit is used to compare the current clear sky index with the future clear sky index when the judgment subunit determines that it is true. The current irradiance value determination subunit is used to input the current solar radiation intensity corresponding to the current clear sky index into the tilt surface radiation calculation model if the current clear sky index is not less than the future clear sky index, so as to obtain the current irradiance value corresponding to each tilt angle of the tilt surface radiation calculation model. The first tracking angle determination subunit is used to determine the tilt angle corresponding to the largest current irradiance value among the various current irradiance values ​​as the optimal tracking angle of the photovoltaic tracking bracket.

15. The control device according to claim 14, characterized in that, The tracking angle determination unit also includes: The radiation intensity prediction subunit is used to obtain the predicted solar radiation intensity for the second preset time period after the current moment based on the future clear sky index and the clear sky model at the corresponding time if the current clear sky index is less than the future clear sky index. The predicted irradiance value determination subunit is used to input the predicted solar radiation intensity into the tilted surface radiation calculation model to obtain the predicted irradiance value corresponding to each tilt angle of the tilted surface radiation calculation model. The second tracking angle determination subunit is used to determine the tilt angle corresponding to the largest predicted irradiance value among the predicted irradiance values ​​as the optimal tracking angle of the photovoltaic tracking bracket.

16. The control device according to claim 14, characterized in that, The tracking angle determination unit also includes: The third tracking angle determination subunit is used to determine the optimal tracking angle of the photovoltaic tracking bracket using an astronomical algorithm when the judgment subunit determines that it is not.

17. A photovoltaic tracking system, characterized in that, include: Photovoltaic modules, photovoltaic trackers, photovoltaic inverters, and controllers, wherein the controller includes the control device for the photovoltaic tracking bracket as described in any one of claims 9 to 16; The controller is communicatively connected to the photovoltaic tracker and the photovoltaic inverter respectively. The photovoltaic tracker is mechanically connected to at least one of the photovoltaic modules, and at least one of the photovoltaic modules is connected to the DC side of the photovoltaic inverter.

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