Control Method, Device and Photovoltaic System of Photovoltaic Tracking Bracket

Abstract

The present invention discloses a control method, device and photovoltaic system for a photovoltaic tracking bracket. The method includes: when the inverter output power data meets a preset full-load condition, acquiring measured irradiance data within a preset time period; predicting the predicted irradiance data at a first preset moment after the current moment according to the measured irradiance data within the preset time period; determining the inverter output power at the first preset moment according to the predicted irradiance data at the first preset moment and a preliminary optimal tracking angle; the time difference between the first preset moment and the current moment is less than or equal to the angle adjustment time interval of the photovoltaic tracking bracket; determining the optimal tracking angle of the photovoltaic tracking bracket at the next moment according to the inverter output power at the first preset moment; and controlling the photovoltaic tracking bracket to adjust to the optimal tracking angle. The present invention can avoid the inverter being in an overloaded state during the time from adjusting the tracking angle to the next adjustment of the tracking angle, and avoid damage to the inverter.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic power generation, and in particular to a control method, device and photovoltaic system for a photovoltaic tracking bracket. Background Art

[0002] In the design of a photovoltaic power station system, the ratio of the sum of the rated powers of the photovoltaic modules connected to the DC side to the rated power of the inverter is called the capacity ratio. With the advent of the parity era, reducing investment costs and increasing investment returns have become the most concerned topics in the entire industry. To a certain extent, increasing the capacity ratio, that is, "overmatching", can improve the utilization rate of equipment such as inverters, increase system revenue, and has a positive significance for reducing the cost per kilowatt-hour of the photovoltaic system. In addition, with the decrease in the cost and the increase in the reliability of the tracking bracket, more and more photovoltaic power stations use tracking brackets to increase power generation, and the tracking algorithm tracks sunlight according to the location.

[0003] The conventional sunny-day tracking strategy is an astronomical tracking algorithm, that is, keeping the surface of the module perpendicular to the incident sunlight so that the surface of the module can receive the most solar energy. Even when the power generation power of the inverter has reached the maximum power point, the conventional strategy is still to pursue the maximum irradiance.

[0004] However, in areas with good lighting conditions in summer, the irradiance conditions can be maintained above 1000 W / m 2 for a long time. At the optimal tracking angle, the irradiance value on the surface of the module can reach 1200 W / m 2 . In the case of overmatching, since the rated capacity of the AC side of the inverter is less than the DC side capacity, when the irradiance is close to 1000 W / m 2 , the power of the AC side has reached the rated power or the maximum power. When the irradiance continues to increase, the DC side voltage of the inverter will continue to rise, and the inverter is in an overloaded state. Figure 1 The following is a schematic diagram of the output power of an inverter Figure 1 As shown, the vertical axis represents the output power of the inverter. In summer on sunny days, the output power of the inverter can often exceed the rated power of the inverter and reach the maximum output power. In addition, in some slightly cloudy or cloudy days in summer except sunny days, due to the reflection of the clouds around the sun, the radiation on the surface of the module can suddenly increase, and the irradiance intensity even exceeds the intensity of the radiation at the top of the atmosphere (about 1361 W / m 2 ), and can reach above 1500 W / m 2 . This phenomenon is called the Cloud Edge Effect. Figure 2 The following is a schematic diagram of irradiance, as Figure 2As shown, the vertical axis represents the irradiance. Due to the cloud reflection effect, the irradiance value on the surface of the module suddenly increases. Since the temperature is usually very high in summer, in these two cases, if the existing tracking algorithm is used, the excessive irradiance and high temperature may cause the inverter to fail. Summary of the Invention

[0005] The present invention provides a control method, device and photovoltaic system for a photovoltaic tracking bracket to avoid the inverter being in an overloaded state during the time from adjusting the tracking angle to the next adjustment of the tracking angle, and to avoid damage to the inverter.

[0006] According to an aspect of the present invention, there is provided a control method for a photovoltaic tracking bracket, including:

[0007] Obtain the inverter output power data within a preset time period before the current moment, and when the inverter output power data meets the preset full-load condition, obtain the measured irradiance data within the preset time period;

[0008] Predict the predicted irradiance data at a first preset moment after the current moment according to the measured irradiance data within the preset time period;

[0009] Determine the preliminary optimal tracking angle of the photovoltaic tracking bracket, and determine the inverter output power at the first preset moment according to the predicted irradiance data at the first preset moment and the preliminary optimal tracking angle; wherein, the time difference between the first preset moment and the current moment is less than or equal to the angle adjustment time interval of the photovoltaic tracking bracket;

[0010] Determine the optimal tracking angle of the photovoltaic tracking bracket at the next moment according to the inverter output power at the first preset moment;

[0011] Control the photovoltaic tracking bracket to adjust to the optimal tracking angle.

[0012] Optionally, determining the preliminary optimal tracking angle of the photovoltaic tracking bracket includes:

[0013] Obtain the first bracket angle of the photovoltaic tracking bracket within a preset time period;

[0014] Determine the multiple theoretical output powers of the inverter corresponding to the photovoltaic tracking bracket at multiple preset angles according to the measured irradiance data, the inverter output power data and the first bracket angle, and determine the preliminary optimal tracking angle of the photovoltaic tracking bracket according to the multiple theoretical output powers of the inverter; wherein, the multiple preset angles are determined according to the first bracket angle, and the absolute value of the difference between the preset angle and the first bracket angle is less than a set value.

[0015] Optionally, determining the optimal tracking angle of the photovoltaic tracking bracket at the next moment according to the inverter output power at the first preset moment includes:

[0016] If the inverter output power at the first preset moment is less than the maximum power of the inverter, determining the preliminary optimal tracking angle as the optimal tracking angle of the photovoltaic tracking bracket at the next moment;

[0017] If the inverter output power at the first preset moment is greater than the maximum power of the inverter, re-determine a plurality of preset angles, and return to execute determining the plurality of theoretical output powers of the inverter corresponding to the photovoltaic tracking bracket at the plurality of preset angles according to the measured irradiance data, the inverter output power data, and the first bracket angle, and determining the preliminary optimal tracking angle of the photovoltaic tracking bracket according to the plurality of theoretical output powers of the inverter.

[0018] Optionally, re-determining a plurality of preset angles includes:

[0019] Re-determining the plurality of preset angles according to the second bracket angle of the photovoltaic tracking bracket at the second preset moment before the current moment, where the time difference between the current moment and the second preset moment is n times the angle adjustment time interval of the photovoltaic tracking bracket, n is an integer greater than or equal to 1, and the absolute value of the difference between each of the re-determined preset angles and the second bracket angle is less than a set value, the set value is greater than 0 and less than or equal to 10 degrees.

[0020] Optionally, determining the plurality of theoretical output powers of the inverter corresponding to the photovoltaic tracking bracket at the plurality of preset angles according to the measured irradiance data, the inverter output power data, and the first bracket angle includes:

[0021] Determining the irradiance on the surface of the photovoltaic module according to the measured irradiance data within the preset duration and the first bracket angle;

[0022] Determining the correspondence between the inverter output power and the irradiance on the surface of the photovoltaic module according to the irradiance and the inverter output power data;

[0023] Calculating the plurality of theoretical irradiances on the surface of the photovoltaic module corresponding to the plurality of preset angles according to the measured irradiance data at the current moment;

[0024] Determining the theoretical output powers of the inverter corresponding to the plurality of preset angles according to the plurality of theoretical irradiances and the correspondence between the inverter output power and the irradiance on the surface of the photovoltaic module.

[0025] Optionally, determining the preliminary optimal tracking angle according to the plurality of theoretical output powers of the inverter includes:

[0026] Determine the preset angle corresponding to the theoretical output power with the smallest difference from the preset power among the multiple theoretical output powers of the inverter as the preliminary optimal tracking angle, where the preset power is the rated power or the maximum power of the inverter.

[0027] Optionally, predicting the predicted irradiance data at a first preset moment after the current moment based on the measured irradiance data within the preset duration includes:

[0028] Calculating the first irradiance data within the preset duration according to the set model, and determining the corresponding relationship between the clear sky index and time based on the first irradiance data and the measured irradiance data;

[0029] Determining the predicted clear sky index at the first preset moment according to the corresponding relationship between the clear sky index and time;

[0030] Calculating the second irradiance data at the first preset moment according to the set model, and determining the predicted irradiance data at the first preset moment based on the second irradiance data and the predicted clear sky index.

[0031] Optionally, when the inverter output power data meets the preset full-load condition, obtaining the measured irradiance data within the preset duration includes:

[0032] Determining the average output power of the inverter within the preset duration according to the output power data of the inverter, and collecting the measured irradiance data within the preset duration when the ratio of the average output power to the maximum power of the inverter is greater than the preset ratio.

[0033] Optionally, the preset duration is less than the angle adjustment time interval.

[0034] According to another aspect of the present invention, there is provided a control device for a photovoltaic tracking bracket, including:

[0035] A data acquisition module, configured to acquire the inverter output power data within a preset duration before the current moment, and acquire the measured irradiance data within the preset duration when the inverter output power data meets the preset full-load condition;

[0036] An irradiance data prediction module, configured to predict the predicted irradiance data at a first preset moment after the current moment based on the measured irradiance data within the preset duration;

[0037] An output power determination module, configured to determine the preliminary optimal tracking angle of the photovoltaic tracking bracket, and determine the inverter output power at the first preset moment based on the predicted irradiance data at the first preset moment and the preliminary optimal tracking angle;

[0038] The optimal tracking angle determination module is configured to determine the optimal tracking angle of the photovoltaic tracking bracket at the next moment according to the inverter output power at the first preset moment;

[0039] The angle adjustment module is configured to control the photovoltaic tracking bracket to adjust to the optimal tracking angle.

[0040] According to another aspect of the present invention, there is provided a photovoltaic system, including:

[0041] Photovoltaic modules, a photovoltaic tracking bracket, an inverter, an environmental monitor, and a control device of the photovoltaic tracking bracket according to any embodiment of the present invention;

[0042] Wherein, the control device of the photovoltaic tracking bracket is respectively connected to the environmental monitor and the inverter, and the photovoltaic modules are arranged on the photovoltaic tracking bracket; the environmental monitor is configured to collect the measured irradiance data within a preset duration.

[0043] In the embodiment of the present invention, when the inverter output power meets the preset full-load condition, that is, when it is close to or at full load, the predicted irradiance data at the first preset moment after the current moment is predicted according to the measured irradiance data within the preset duration, and after determining the preliminary optimal tracking angle, the inverter output power at the first preset moment is calculated according to the preliminary optimal tracking angle and the predicted irradiance data at the first preset moment, and the optimal tracking angle of the photovoltaic tracking bracket at the next moment is determined according to the inverter output power at the first preset moment. Considering the inverter output power at the first preset moment after the current moment when determining the tracking angle at the next moment can effectively avoid the inverter being in an overloaded state during the time from adjusting the tracking angle to the next adjustment of the tracking angle, and avoid damage to the inverter.

[0044] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. Description of the Drawings

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings.

[0046] Figure 1 It is a schematic diagram of the inverter output power;

[0047] Figure 2 It is a schematic diagram of the irradiance;

[0048] Figure 3 It is a flowchart of a control method for a photovoltaic tracking bracket provided by an embodiment of the present invention;

[0049] Figure 4 It is a flowchart of another control method for a photovoltaic tracking bracket provided by an embodiment of the present invention;

[0050] Figure 5 It is a flowchart of another control method for a photovoltaic tracking bracket provided by an embodiment of the present invention;

[0051] Figure 6 It is a schematic diagram of a tracking power curve provided by this embodiment;

[0052] Figure 7 It is a schematic diagram of a control device for a photovoltaic tracking bracket provided by an embodiment of the present invention. Detailed implementation manners

[0053] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0054] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data used can be interchanged under appropriate circumstances so that the embodiments of the present invention described here can be implemented in an order different from those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device including a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0055] An embodiment of the present invention provides a control method for a photovoltaic tracking bracket, Figure 3 It is a flowchart of a control method for a photovoltaic tracking bracket provided by an embodiment of the present invention, referring to Figure 3 , the method includes:

[0056] S110. Obtain the inverter output power data within a preset time period before the current moment, and when the inverter output power data meets the preset full-load condition, obtain the measured irradiance data within the preset time period.

[0057] Among them, the preset duration can be determined according to the angle adjustment time interval ΔT of the photovoltaic tracking bracket. The preset duration can be less than ΔT, and can be ΔT / 2, etc. typically. ΔT is about 5 minutes, that is, the angle of the photovoltaic tracking bracket is adjusted every 5 minutes. Assume the current moment is T1, and obtain the inverter output power data within the preset duration before the current moment, that is, obtain the inverter output power data from T1 - ΔT / 2 to T1. The inverter output power data can include multiple data, and the power of the inverter can be collected once every set duration within the preset duration. Exemplarily, the inverter power collection interval can be set to f seconds, and n inverter power values can be collected within the preset duration, where n = (ΔT / 2)*60 / f. The inverter output power data meeting the preset full-load condition can be that the average value of the n inverter power values is greater than the set power value, or that all the n inverter power values are greater than the set power value, etc. Among them, the set power value is determined according to the maximum output power of the inverter, and can be 95% or 90% of the maximum output power of the inverter, etc. When the inverter output power data meets the preset full-load condition, if tracking continues according to the maximum irradiance data, it is easy to cause the inverter to be fully loaded and damage the inverter.

[0058] In addition, the irradiance data can include global horizontal irradiance (GHI), direct normal irradiance (DNI), and diffuse horizontal irradiance (DHI). The measured irradiance data can include the measured global horizontal irradiance (GHI), direct normal irradiance (DNI), and diffuse horizontal irradiance (DHI), and the measured irradiance data can be obtained through an environmental monitor.

[0059] S120. Predict the predicted irradiance data at the first preset moment after the current moment according to the measured irradiance data within the preset duration.

[0060] Specifically, the irradiance data within the preset duration and the irradiance data at the first preset moment can be predicted through a known physical model, determine the corresponding relationship between the measured irradiance data within the preset duration and the predicted irradiance values, and determine the predicted irradiance value according to this corresponding relationship and the irradiance data at the first preset moment predicted by the physical model. In addition, other methods can also be used to predict the predicted irradiance data, and this embodiment does not limit the specific prediction method.

[0061] S130. Determine the preliminary optimal tracking angle of the photovoltaic tracking bracket, and determine the inverter output power at the first preset moment according to the predicted irradiance data at the first preset moment and the preliminary optimal tracking angle. Among them, the time difference between the first preset moment and the current moment is less than or equal to the angle adjustment time interval of the photovoltaic tracking bracket.

[0062] Among them, the preliminary optimal tracking angle can be determined according to the angle of the photovoltaic tracking bracket at the current moment or can be determined according to existing tracking algorithms, and this embodiment does not make specific limitations. Exemplarily, the multiple preset angles can be multiple angles within plus or minus 10 degrees from the angle of the photovoltaic tracking bracket at the current moment. Specifically, the irradiance on the surface of the photovoltaic module at the first preset moment can be determined according to the predicted irradiance data and the preliminary optimal tracking angle at the first preset moment, and the output power of the inverter at the first preset moment can be determined according to the relationship between the irradiance and the output power of the inverter.

[0063] S140. Determine the optimal tracking angle of the photovoltaic tracking bracket at the next moment according to the output power of the inverter at the first preset moment.

[0064] S150. Control the photovoltaic tracking bracket to adjust to the optimal tracking angle.

[0065] Specifically, the next moment is the moment adjacent to the current moment, that is, immediately after determining the optimal tracking angle at the next moment, control the photovoltaic tracking bracket to adjust to the optimal tracking angle. The time difference between the first preset moment and the current moment is less than or equal to the angle adjustment time interval of the photovoltaic tracking bracket, that is, the angle of the photovoltaic tracking bracket will not be adjusted between the time when the bracket angle is adjusted at the next moment and the first preset moment. Exemplarily, the time difference between the first preset moment and the current moment can be equal to the angle adjustment time interval of the photovoltaic tracking bracket.

[0066] If the output power of the inverter at the first preset moment is less than the maximum output power of the inverter, the preliminary optimal tracking angle can be determined as the nearest tracking angle at the next moment. If the output power of the inverter at the first preset moment is greater than the maximum output power of the inverter, it means that if the angle of the photovoltaic tracking bracket is adjusted to the preliminary optimal tracking angle at the next moment, the output power of the inverter at the first preset moment after a certain period of time will be greater than the maximum output power of the inverter, which is likely to cause the inverter to be overloaded and damage the inverter. Therefore, it is necessary to re-determine the preliminary optimal tracking angle, and then determine the output power of the inverter at the first preset moment according to the predicted irradiance data and the re-determined preliminary optimal tracking angle, and continue to judge whether the output power of the inverter at the first preset moment is less than the maximum output power of the inverter. If the output power of the inverter at the first preset moment determined after re-determination is less than the maximum output power of the inverter, determine the re-determined preliminary optimal tracking angle as the optimal tracking angle of the photovoltaic tracking bracket at the next moment.

[0067] In an embodiment of the present invention, when the output power of the inverter meets the preset full-load condition, that is, when it is close to or at full load, the predicted irradiance data at a first preset moment after the current moment is predicted according to the measured irradiance data within a preset duration. After determining the preliminary optimal tracking angle, the output power of the inverter at the first preset moment is calculated based on the preliminary optimal tracking angle and the predicted irradiance data at the first preset moment, and the optimal tracking angle of the photovoltaic tracking bracket at the next moment is determined according to the output power of the inverter at the first preset moment. Considering the output power of the inverter at the first preset moment after the current moment when determining the tracking angle at the next moment can effectively prevent the inverter from being in an overloaded state during the time from when the tracking angle of the inverter is adjusted until the next adjustment of the tracking angle, and avoid damage to the inverter.

[0068] Optionally, determining the preliminary optimal tracking angle of the photovoltaic tracking bracket includes:

[0069] Obtaining a first bracket angle of the photovoltaic tracking bracket within a preset duration;

[0070] Determining a plurality of theoretical output powers of the inverter corresponding to the photovoltaic tracking bracket at a plurality of preset angles according to the measured irradiance data, the inverter output power data, and the first bracket angle, and determining the preliminary optimal tracking angle of the photovoltaic tracking bracket according to the plurality of theoretical output powers of the inverter; wherein, the plurality of preset angles are determined according to the first bracket angle, and the absolute value of the difference between the preset angle and the first bracket angle is less than a set value.

[0071] Specifically, the set value can be 5 degrees, 10 degrees, 15 degrees, etc. Exemplarily, a plurality of angles within plus or minus 10 degrees of the first bracket angle can be set as the preset angles. The n irradiance levels on the surface of the photovoltaic module within the preset duration can be determined according to n measured irradiance data and the first bracket angle, and the corresponding relationship between the inverter output power and the irradiance can be determined according to the inverter output power data. The surface irradiance of the photovoltaic module corresponding to the plurality of preset angles is determined according to the measured irradiance data at the current moment and the plurality of preset angles, and the plurality of theoretical output powers of the inverter corresponding to the plurality of preset angles are determined in combination with the corresponding relationship between the inverter output power and the irradiance. The angle corresponding to the power closest to the required output power among the plurality of theoretical output powers can be used as the preliminary optimal tracking angle. Exemplarily, the angle closest to the rated power or the maximum output power of the inverter can be used as the preliminary optimal tracking angle.

[0072] Determine multiple preset angles through the first support angle. The determination speed is relatively fast, and determine the preliminary optimal tracking angle according to the multiple theoretical output powers corresponding to the multiple preset angles, comprehensively considering the current inverter output power situation. While ensuring that the inverter can output the required output power, avoid the inverter being in an overloaded state during the time from adjusting the tracking angle to the next adjustment of the tracking angle, and avoid inverter damage.

[0073] Based on the above embodiment, this embodiment provides a control method for a photovoltaic tracking support. Figure 4 It is a flowchart of another control method for a photovoltaic tracking support provided by an embodiment of the present invention. Refer to Figure 4 and this method includes:

[0074] S110. Obtain the inverter output power data within a preset duration before the current moment, and when the inverter output power data meets the preset full-load condition, obtain the measured irradiance data within the preset duration.

[0075] S120. Predict the predicted irradiance data at a first preset moment after the current moment according to the measured irradiance data within the preset duration.

[0076] S131. Obtain the first support angle of the photovoltaic tracking support within a preset duration.

[0077] S132. Determine the multiple theoretical output powers of the inverter corresponding to the photovoltaic tracking support at multiple preset angles according to the measured irradiance data, the inverter output power data, and the first support angle, and determine the preliminary optimal tracking angle of the photovoltaic tracking support according to the multiple theoretical output powers of the inverter; wherein, the multiple preset angles are determined according to the first support angle, and the absolute value of the difference between the preset angle and the first support angle is less than a set value.

[0078] S133. Determine the inverter output power at the first preset moment according to the predicted irradiance data at the first preset moment and the preliminary optimal tracking angle.

[0079] S141. Determine whether the inverter output power at the first preset moment is less than the maximum power of the inverter. If so, continue to execute S142 and S150. If not, execute S143 and then return to execute S132.

[0080] S142. Determine the preliminary optimal tracking angle as the optimal tracking angle of the photovoltaic tracking support at the next moment.

[0081] S143. Re-determine multiple preset angles.

[0082] Specifically, the preset angle can be re-determined according to the first support angle, or the preset angle can be re-determined according to the angle of the photovoltaic tracking support before the current moment.

[0083] After re-determining multiple preset angles, re-determine the preliminary optimal tracking angle according to S132, and re-calculate the inverter output power at the first preset moment according to the re-determined preliminary optimal tracking angle and S133. Continue to determine whether the inverter output power at the first preset moment is less than the maximum power of the inverter. When the re-calculated inverter output power at the first preset moment is still greater than the maximum power of the inverter, continue to re-determine multiple preset angles until the re-calculated inverter output power at the first preset moment is less than the maximum power of the inverter.

[0084] Optionally, re-determining multiple preset angles includes:

[0085] Re-determine multiple preset angles according to the second support angle of the photovoltaic tracking support at the second preset moment before the current moment, where the time difference between the current moment and the second preset moment is n times the angle adjustment time interval of the photovoltaic tracking support, n is an integer greater than or equal to 1, and the absolute value of the difference between each of the multiple re-determined preset angles and the second support angle is less than a set value, the set value is greater than 0 and less than or equal to 10 degrees.

[0086] Specifically, when the multiple preset angles determined according to the first support angle cannot determine the optimal tracking angle, multiple preset angles can be re-determined first according to the second support angle of the second preset moment that is one angle adjustment time interval away from the current moment. When the optimal tracking angle still cannot be determined, continue to re-determine multiple preset angles according to the second support angle of the second preset moment that is two angle adjustment time intervals away from the current moment, and so on, until the optimal tracking angle is determined.

[0087] S150. Control the photovoltaic tracking support to adjust to the optimal tracking angle.

[0088] When the inverter output power at the first preset moment is less than the maximum power of the inverter in this embodiment, the preliminary optimal tracking angle is determined as the optimal tracking angle of the photovoltaic tracking bracket at the next moment. When the inverter output power at the first preset moment is less than the maximum power of the inverter, multiple preset angles are re-determined, and the preliminary optimal tracking angle is re-determined according to the multiple preset angles, and then the inverter output power at the next moment is re-determined until the inverter output power at the first preset moment is less than the maximum power of the inverter, which can effectively avoid the inverter being in an overloaded state during the period from the next moment of adjusting the tracking angle to the next adjustment of the tracking angle, and avoid damage to the inverter. And in this embodiment, multiple preset angles are determined according to the first bracket angle at the current moment, and multiple preset angles are re-determined according to the second bracket angle at the second moment before the current moment, which can determine multiple preset angles faster, so as to determine the preliminary optimal tracking angle and the optimal angle faster, and improve the operation speed.

[0089] Optionally, determining the multiple theoretical output powers of the inverter corresponding to the photovoltaic tracking bracket at multiple preset angles according to the measured irradiance data, the inverter output power data, and the first bracket angle includes:

[0090] Determining the irradiance on the surface of the photovoltaic module according to the measured irradiance data within the preset duration and the first bracket angle;

[0091] Determining the corresponding relationship between the inverter output power and the irradiance on the surface of the photovoltaic module according to the irradiance and the inverter output power data;

[0092] Calculating the multiple theoretical irradiances on the surface of the photovoltaic module corresponding to the multiple preset angles according to the measured irradiance data at the current moment;

[0093] Determining the theoretical output powers of the inverter corresponding to the multiple preset angles according to the multiple theoretical irradiances and the corresponding relationship between the inverter output power and the irradiance on the surface of the photovoltaic module.

[0094] Specifically, the measured irradiance data (including measured GHI, DHI, and DNI) and the first bracket angle data can be substituted into the inclined plane radiation amount calculation model to calculate the radiation degree on the surface of the photovoltaic module, and the irradiance data POA = [poa1, poa2,..., poan] can be obtained. The inverter output power data can be P = [p1, p2,..., pn], and the corresponding relationship between the inverter output power and the irradiance on the surface of the photovoltaic module is α = P / POA, α = [α1, α4,..., αn]. Specifically, the average value of α1, α4,..., and αn can be calculated to obtain the coefficient A, and A is the relationship coefficient between the inverter output power and the irradiance on the surface of the photovoltaic module.

[0095] Within the range of plus or minus 10° of the first support angle An, that is, within the range from An - 10° to An + 10°, a value is taken every 1° to obtain a plurality of preset angles. The measured irradiance data at the current moment and the plurality of preset angles are respectively substituted into the inclined plane irradiance calculation model to obtain the theoretical irradiance values POA' = [poa'1, poa'2, …, poa'21] on the surface of the photovoltaic module at 21 different preset angles. According to the relationship coefficient between the inverter output power and the irradiance on the surface of the photovoltaic module, the theoretical output power P' of the inverter at 21 preset angles can be obtained as P' = POA' * A.

[0096] In this embodiment, a plurality of theoretical irradiances on the surface of the photovoltaic module corresponding to the plurality of preset angles are calculated according to the measured irradiance data at the current moment; the theoretical output power of the inverter corresponding to the plurality of preset angles is determined according to the plurality of theoretical irradiances and the corresponding relationship between the inverter output power and the irradiance on the surface of the photovoltaic module. Since the corresponding relationship between the irradiance and the inverter output power is determined according to the measured irradiance data and the actual inverter output power data within the preset time period before the current moment, this corresponding relationship can more accurately reflect the relationship between the irradiance and the inverter output power, so that the determined plurality of theoretical output powers are more in line with the actual situation.

[0097] Optionally, determining the preliminary optimal tracking angle according to the plurality of theoretical output powers of the inverter includes:

[0098] The preset angle corresponding to the theoretical output power with the smallest difference from the preset power among the plurality of theoretical output powers of the inverter is determined as the preliminary optimal tracking angle, where the preset power is the rated power of the inverter or the maximum power of the inverter.

[0099] Specifically, by selecting the preset angle corresponding to the power closest to the rated power of the inverter or the power closest to the maximum power of the inverter as the preliminary optimal tracking angle, it can be ensured that the inverter has a high working efficiency.

[0100] This embodiment provides a control method for a photovoltaic tracking support based on the above embodiment. Figure 5 It is a flowchart of another control method for a photovoltaic tracking support provided by an embodiment of the present invention. Refer to Figure 5 and the method includes:

[0101] S110. Obtain the inverter output power data within the preset time period before the current moment, and when the inverter output power data meets the preset full-load condition, obtain the measured irradiance data within the preset time period.

[0102] Optionally, when the inverter output power data meets the preset full-load condition, obtaining the measured irradiance data within the preset time period includes:

[0103] Determine the average output power of the inverter within the preset duration according to the output power data of the inverter. When the ratio of the average output power to the maximum power of the inverter is greater than a preset ratio, collect the measured irradiance data within the preset duration.

[0104] Among them, the preset value can be any value greater than or equal to 90% and less than 100%. Exemplarily, it can be 95% or 98%, etc., and this embodiment does not make specific limitations. In addition, when the ratio of the average output power to the maximum power of the inverter is less than the preset ratio, an astronomical tracking algorithm can be used for angle tracking control of the photovoltaic tracking bracket.

[0105] Specifically, using the average output power of the inverter within the preset duration for full-load judgment can avoid the influence of instantaneous fluctuations in irradiance. In addition, since the tracking strategy of the photovoltaic tracking bracket is a step-by-step non-infinite variable speed real-time tracking of the sun, that is, the same angle is executed within each angle adjustment time interval, and the angle has hysteresis. Therefore, when the ratio of the average output power to the maximum power of the inverter is greater than the preset ratio, if the angle of the photovoltaic tracking bracket is adjusted to the maximum irradiance angle, the inverter may reach full load. Therefore, when the ratio of the average output power to the maximum power of the inverter is greater than the preset ratio, adopting the scheme of this embodiment for angle adjustment of the photovoltaic tracking bracket can avoid damage caused by the inverter reaching full load.

[0106] S121. Calculate the first irradiance data within the preset duration according to the set model, and determine the corresponding relationship between the clearness index and time according to the first irradiance data and the measured irradiance data.

[0107] S122. Determine the predicted clearness index at the first preset moment according to the corresponding relationship between the clearness index and time.

[0108] Specifically, existing physical models such as Ineichen or Perez can be used to calculate the clear-sky irradiance data at each moment, that is, the first irradiance data. The first irradiance data includes the first global horizontal irradiance GHIclear, the first direct normal irradiance DNIclear, and the first diffuse horizontal irradiance DHIclear. The corresponding relationship between the clear-sky index and time is calculated by combining the first irradiance data and the measured irradiance data. Taking the clear-sky index of GHI as an example, it is illustrated as follows: kt = measured GHI / GHIclear. Linear fitting is performed on the matrix KT = [kt1, kt2, …, ktn] composed of n clear-sky indices kt to obtain the relationship between the clear-sky index of GHI and time as kt = at + b, where a and b are fitting coefficients, kt is the clear-sky index of GHI, and t is time. Assuming that the change trend of the clear-sky index is consistent in a short period of time, the predicted clear-sky index kt’ of GHI at the first preset moment can be calculated from the fitting formula. The clear-sky index Kx’ of DNI and the clear-sky index Ky’ of DHI at the first preset moment can be calculated in the same process.

[0109] S123. Calculate the second irradiance data at the first preset moment according to the set model, and determine the predicted irradiance data at the first preset moment according to the second irradiance data and the predicted clear-sky index.

[0110] Specifically, existing physical models such as Ineichen or Perez can be used to calculate the second irradiance data at the first preset moment. The second irradiance data includes the second global horizontal irradiance GHIclear’, the second direct normal irradiance DNIclear’, and the second diffuse horizontal irradiance DHIclear’. The predicted irradiance data may include the predicted global horizontal irradiance GHI’, the predicted direct normal irradiance DNI’, and the predicted diffuse horizontal irradiance DHI’. Then the predicted global horizontal irradiance GHI’ at the first preset moment = GHIclear’ * kt’. Similarly, the predicted direct normal irradiance DNI’ = DNIclear’ * Kx’, and the predicted diffuse horizontal irradiance DHI’ = DHIclear’ * Ky’.

[0111] S130. Determine the preliminary optimal tracking angle of the photovoltaic tracking bracket, and determine the inverter output power at the first preset moment according to the predicted irradiance data and the preliminary optimal tracking angle at the first preset moment.

[0112] S140. Determine the optimal tracking angle of the photovoltaic tracking bracket at the next moment according to the inverter output power at the first preset moment.

[0113] S150. Control the photovoltaic tracking bracket to adjust to the optimal tracking angle.

[0114] In this embodiment, the corresponding relationship between the clearness index and time is determined based on the measured irradiance data within a preset duration and the first irradiance data calculated according to the model. The predicted clearness index at the first preset moment is determined according to the corresponding relationship between the clearness index and time, and the second irradiance data at the first preset moment is calculated according to the model. The predicted irradiance data at the first preset moment is determined based on the second irradiance data and the predicted clearness index. Since the predicted clearness index is determined based on the measured irradiance data and the first irradiance data calculated according to the model, the predicted irradiance data determined according to the clearness index is more consistent with the actual irradiance data.

[0115] Optionally, the preset duration is less than the angle adjustment time interval. That is, the measured irradiance data and the inverter output power data within the preset duration are more consistent with the current irradiance situation, so that the clearness index determined based on the measured irradiance data and the inverter output power data within the preset duration, and the corresponding relationship between the inverter output power and the irradiance are more consistent with the current moment, so that the predicted irradiance data and the inverter output power at the first preset moment determined according to the corresponding relationship between the clearness index and the irradiance of the inverter output power conform to the actual situation.

[0116] Figure 6 It is a schematic diagram of tracking the power curve provided by this embodiment. Refer to Figure 6 , the vertical axis represents the inverter output power. As can be seen from Figure 6 , in the embodiment of the present invention, when the output power of the inverter meets the overload condition, the tracking angle of the bracket is changed to reduce the incident radiation value, avoiding adverse effects on the inverter and other devices caused by excessive radiation. In addition, the embodiment of the present invention combines the measured irradiance data and the inverter output power data, and optimizes the tracking angle through a physical model and predicted radiation, enabling the components to achieve the maximum power generation and reducing power generation losses without increasing the bracket tracking frequency, thereby improving the system life.

[0117] The embodiment of the present invention also provides a control device for a photovoltaic tracking bracket. Figure 7 It is a schematic diagram of a control device for a photovoltaic tracking bracket provided by an embodiment of the present invention. Refer to Figure 7 , the control device 200 of the photovoltaic tracking bracket includes:

[0118] A data acquisition module 210, configured to acquire the inverter output power data within a preset duration before the current moment, and acquire the measured irradiance data within the preset duration when the inverter output power data meets the preset full-load condition.

[0119] An irradiance data prediction module 220, configured to predict the predicted irradiance data at a first preset moment after the current moment based on the measured irradiance data within the preset duration.

[0120] An output power determination module 230 is configured to determine a preliminary optimal tracking angle of the photovoltaic tracking bracket, and determine the inverter output power at the first preset moment according to the predicted irradiance data at the first preset moment and the preliminary optimal tracking angle.

[0121] An optimal tracking angle determination module 240 is configured to determine the optimal tracking angle of the photovoltaic tracking bracket at the next moment according to the inverter output power at the first preset moment.

[0122] An angle adjustment module 250 is configured to control the photovoltaic tracking bracket to adjust to the optimal tracking angle.

[0123] Optionally, the output power determination module 230 includes:

[0124] An angle acquisition unit is configured to acquire a first bracket angle of the photovoltaic tracking bracket within a preset duration;

[0125] A preliminary optimal angle determination unit is configured to determine multiple theoretical output powers of the inverter corresponding to the photovoltaic tracking bracket at multiple preset angles respectively according to the measured irradiance data, the inverter output power data, and the first bracket angle, and determine the preliminary optimal tracking angle of the photovoltaic tracking bracket according to the multiple theoretical output powers of the inverter; wherein, the multiple preset angles are determined according to the first bracket angle, and the absolute value of the difference between each preset angle and the first bracket angle is less than a set value.

[0126] Optionally, the optimal tracking angle determination module 240 includes:

[0127] A first determination unit is configured to, if the inverter output power at the first preset moment is less than the maximum power of the inverter, determine the preliminary optimal tracking angle as the optimal tracking angle of the photovoltaic tracking bracket at the next moment;

[0128] A second determination unit is configured to, if the inverter output power at the first preset moment is greater than the maximum power of the inverter, re-determine multiple preset angles, and return to execute determining multiple theoretical output powers of the inverter corresponding to the photovoltaic tracking bracket at multiple preset angles respectively according to the measured irradiance data, the inverter output power data, and the first bracket angle, and determine the preliminary optimal tracking angle of the photovoltaic tracking bracket according to the multiple theoretical output powers of the inverter.

[0129] Optionally, the second determination unit is specifically configured to:

[0130] Redetermine the plurality of preset angles according to the second bracket angle of the photovoltaic tracking bracket at a second preset moment before the current moment, where the time difference between the current moment and the second preset moment is n times the angle adjustment time interval of the photovoltaic tracking bracket, n is an integer greater than or equal to 1, and the absolute value of the difference between each of the plurality of redetermined preset angles and the second bracket angle is less than a set value, the set value is greater than 0 and less than or equal to 10 degrees.

[0131] Optionally, the preliminary optimal angle determination unit includes:

[0132] An irradiance determination unit, configured to determine the irradiance on the surface of the photovoltaic module according to the measured irradiance data within the preset duration and the first bracket angle;

[0133] A first correspondence determination unit, configured to determine the correspondence between the inverter output power and the irradiance on the surface of the photovoltaic module according to the irradiance and the inverter output power data;

[0134] A theoretical irradiance determination unit, configured to calculate a plurality of theoretical irradiances on the surface of the photovoltaic module corresponding to the plurality of preset angles respectively according to the measured irradiance data at the current moment;

[0135] A theoretical power determination unit, configured to determine the theoretical output power of the inverter corresponding to the plurality of preset angles according to the plurality of theoretical irradiances and the correspondence between the inverter output power and the irradiance on the surface of the photovoltaic module.

[0136] Optionally, the preliminary optimal angle determination unit is specifically configured to:

[0137] Determine the preset angle corresponding to the theoretical output power with the smallest difference from the preset power among the plurality of theoretical output powers of the inverter as the preliminary optimal tracking angle, where the preset power is the rated power or the maximum power of the inverter.

[0138] Optionally, the irradiance data prediction module 220 includes:

[0139] A second correspondence determination unit, configured to calculate first irradiance data within the preset duration according to a set model, and determine the correspondence between the clear sky index and time according to the first irradiance data and the measured irradiance data;

[0140] A clear sky index determination unit, configured to determine the predicted clear sky index at the first preset moment according to the correspondence between the clear sky index and time;

[0141] A predicted irradiance data determination unit, configured to calculate second irradiance data at the first preset moment according to the set model, and determine the predicted irradiance data at the first preset moment according to the second irradiance data and the predicted clear sky index.

[0142] Optionally, the data acquisition module 210 is specifically configured to:

[0143] Determine the average output power of the inverter within the preset duration according to the output power data of the inverter, and when the ratio of the average output power to the maximum power of the inverter is greater than a preset ratio, collect the measured irradiance data within the preset duration.

[0144] Optionally, the preset duration is less than the angle adjustment time interval.

[0145] An embodiment of the present invention further provides a photovoltaic system, including:

[0146] Photovoltaic modules, a photovoltaic tracking bracket, an inverter, an environmental monitor, and a control device for the photovoltaic tracking bracket according to any embodiment of the present invention;

[0147] Wherein, the control device of the photovoltaic tracking bracket is respectively connected to the environmental monitor and the inverter, and the photovoltaic modules are arranged on the photovoltaic tracking bracket; the environmental monitor is used to collect the measured irradiance data within a preset duration.

[0148] It should be understood that various forms of the processes shown above can be used, steps can be reordered, added, or deleted. For example, the steps described in the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solution of the present invention can be achieved, and this is not limited herein.

[0149] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub - combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A control method for a photovoltaic tracking bracket, characterized in that, Including: Obtain the inverter output power data within a preset duration before the current moment, and when the inverter output power data meets the preset full-load condition, obtain the measured irradiance data within the preset duration; Predict the predicted irradiance data at a first preset moment after the current moment according to the measured irradiance data within the preset duration; Determine the preliminary optimal tracking angle of the photovoltaic tracking bracket, and determine the inverter output power at the first preset moment according to the predicted irradiance data and the preliminary optimal tracking angle at the first preset moment; wherein, the time difference between the first preset moment and the current moment is less than or equal to the angle adjustment time interval of the photovoltaic tracking bracket; Determine the optimal tracking angle of the photovoltaic tracking bracket at the next moment according to the inverter output power at the first preset moment; wherein, if the inverter output power at the first preset moment is less than the maximum power of the inverter, determine the preliminary optimal tracking angle as the optimal tracking angle at the next moment; if the inverter output power at the first preset moment is greater than the maximum power of the inverter, re-determine the preliminary optimal tracking angle, then determine the inverter output power at the first preset moment according to the predicted irradiance data at the first preset moment and the re-determined preliminary optimal tracking angle, and when the re-determined inverter output power at the first preset moment is less than the maximum power of the inverter, determine the re-determined preliminary optimal tracking angle as the optimal tracking angle of the photovoltaic tracking bracket at the next moment; Control the photovoltaic tracking bracket to adjust to the optimal tracking angle.

2. The method according to claim 1, wherein Determining the preliminary optimal tracking angle of the photovoltaic tracking bracket includes: Obtain the first bracket angle of the photovoltaic tracking bracket within a preset duration; Determine the multiple theoretical output powers of the inverter corresponding to the photovoltaic tracking bracket at multiple preset angles respectively according to the measured irradiance data, the inverter output power data and the first bracket angle, and determine the preliminary optimal tracking angle of the photovoltaic tracking bracket according to the multiple theoretical output powers of the inverter; wherein, the multiple preset angles are determined according to the first bracket angle, and the absolute value of the difference between the preset angle and the first bracket angle is less than the set value.

3. The method according to claim 2, characterized in that, Determining the optimal tracking angle of the photovoltaic tracking bracket at the next moment according to the inverter output power at the first preset moment includes: If the inverter output power at the first preset moment is greater than the maximum power of the inverter, re-determine multiple preset angles, and return to execute determining the multiple theoretical output powers of the inverter corresponding to the photovoltaic tracking bracket at multiple preset angles respectively according to the measured irradiance data, the inverter output power data and the first bracket angle, and determine the preliminary optimal tracking angle of the photovoltaic tracking bracket according to the multiple theoretical output powers of the inverter.

4. The method according to claim 3, wherein Re-determining multiple preset angles includes: Redetermine the multiple preset angles according to the second bracket angle of the photovoltaic tracking bracket at a second preset moment before the current moment, where the time difference between the current moment and the second preset moment is n times the angle adjustment time interval of the photovoltaic tracking bracket, n is an integer greater than or equal to 1, and the absolute value of the difference between each of the multiple redetermined preset angles and the second bracket angle is less than a set value, the set value is greater than 0 and less than or equal to 10 degrees.

5. The method according to claim 2, characterized in that, Determine multiple theoretical output powers of the inverter corresponding to the photovoltaic tracking bracket at multiple preset angles according to the measured irradiance data, the inverter output power data, and the first bracket angle, including: Determine the irradiance on the surface of the photovoltaic module according to the measured irradiance data within the preset duration and the first bracket angle; Determine the corresponding relationship between the inverter output power and the irradiance on the surface of the photovoltaic module according to the irradiance and the inverter output power data; Calculate multiple theoretical irradiances on the surface of the photovoltaic module corresponding to the multiple preset angles according to the measured irradiance data at the current moment; Determine the theoretical output powers of the inverter corresponding to the multiple preset angles according to the multiple theoretical irradiances and the corresponding relationship between the inverter output power and the irradiance on the surface of the photovoltaic module.

6. The method according to claim 2, wherein Determine a preliminary optimal tracking angle according to the multiple theoretical output powers of the inverter, including: Determine the preset angle corresponding to the theoretical output power with the smallest difference from the preset power among the multiple theoretical output powers of the inverter as the preliminary optimal tracking angle, where the preset power is the rated power or the maximum power of the inverter.

7. The method according to claim 1, wherein Predict the predicted irradiance data at a first preset moment after the current moment according to the measured irradiance data within the preset duration, including: Calculate the first irradiance data within the preset duration according to a set model, and determine the corresponding relationship between the clear sky index and time according to the first irradiance data and the measured irradiance data; Determine the predicted clear sky index at the first preset moment according to the corresponding relationship between the clear sky index and time; Calculate the second irradiance data at the first preset moment according to the set model, and determine the predicted irradiance data at the first preset moment according to the second irradiance data and the predicted clear sky index.

8. The method according to claim 1, characterized in that, When the inverter output power data meets the preset full load condition, obtain the measured irradiance data within the preset duration, including: Determine the average output power of the inverter within the preset duration according to the output power data of the inverter, and collect the measured irradiance data within the preset duration when the ratio of the average output power to the maximum power of the inverter is greater than a preset ratio.

9. The method according to claim 1, wherein The preset duration is less than the angle adjustment time interval.

10. A control device for a photovoltaic tracking bracket, characterized in that, Including: A data acquisition module, configured to acquire the inverter output power data within a preset duration before the current moment, and acquire the measured irradiance data within the preset duration when the inverter output power data meets the preset full load condition; An irradiation data prediction module, configured to predict the predicted irradiation data at a first preset moment after the current moment according to the measured irradiation data within the preset duration; An output power determination module, configured to determine the preliminary optimal tracking angle of the photovoltaic tracking bracket, and determine the inverter output power at the first preset moment according to the predicted irradiation data and the preliminary optimal tracking angle at the first preset moment; An optimal tracking angle determination module, configured to determine the optimal tracking angle of the photovoltaic tracking bracket at the next moment according to the inverter output power at the first preset moment; wherein, if the inverter output power at the first preset moment is less than the maximum power of the inverter, determine the preliminary optimal tracking angle as the optimal tracking angle at the next moment; if the inverter output power at the first preset moment is greater than the maximum power of the inverter, re-determine the preliminary optimal tracking angle, and then determine the inverter output power at the first preset moment according to the predicted irradiation data and the re-determined preliminary optimal tracking angle. When the re-determined inverter output power at the first preset moment is less than the maximum power of the inverter, determine the re-determined preliminary optimal tracking angle as the optimal tracking angle of the photovoltaic tracking bracket at the next moment; An angle adjustment module, configured to control the photovoltaic tracking bracket to adjust to the optimal tracking angle.

11. A photovoltaic system, characterized in that, Comprising: A photovoltaic module, a photovoltaic tracking bracket, an inverter, an environmental monitor, and a control device for the photovoltaic tracking bracket according to claim 10; Wherein, the control device of the photovoltaic tracking bracket is respectively connected to the environmental monitor and the inverter, and the photovoltaic module is arranged on the photovoltaic tracking bracket; the environmental monitor is configured to collect the measured irradiation data within the preset duration.

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