A control method, device and photovoltaic tracking system for a photovoltaic tracking axis

Abstract

The present invention discloses a control method, device and photovoltaic tracking system for a photovoltaic tracking axis. Based on the maximum output power of an inverter, a budget tracking angle corresponding to the photovoltaic tracking axis is determined, and the tracking axis angle of the photovoltaic tracking axis is controlled to be adjusted towards the budget tracking angle. During the adjustment process of the tracking axis angle, the change trend of the inverter output current is determined, and the accuracy of the budget tracking angle is detected according to this current change trend. When it is determined that the budget tracking angle does not meet the accuracy requirements, the budget tracking angle is updated. The present invention obtains the theoretically maximum output power angle of the photovoltaic tracking axis, i.e., the budget tracking angle, based on the maximum output power of the inverter, and detects and updates the accuracy of the budget tracking angle by collecting the change trend of the inverter output current during the adjustment process of the tracking axis angle, so as to realize the closed-loop control of the controller for the photovoltaic tracking axis, thereby giving full play to the maximum power point tracking advantages of the photovoltaic tracking axis and the inverter and maximizing the power generation amount.

Description

Technical Field

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

[0002] In the field of photovoltaic tracking, a photovoltaic tracking system maximizes power generation by adjusting the tracking angle of a photovoltaic tracking axis. In existing tracking algorithms, most use traditional astronomical algorithms to make the photovoltaic tracking axis directly face the sun to increase the power generation of the photovoltaic tracking system. The traditional astronomical algorithm essentially calculates the sun position through information such as time and geographical parameters, and then adjusts the tracking angle of the photovoltaic tracking axis to directly face the sun at that moment. This method is relatively simple and universal. In addition, there are also improved astronomical algorithms proposed based on the traditional astronomical algorithm. The improved astronomical algorithm adds an intelligent AI algorithm on the basis of the traditional astronomical algorithm, and corrects the tracking angle for different weather types to increase power generation in scattered weather such as cloudy and overcast days.

[0003] However, whether it is the traditional astronomical algorithm or the improved astronomical algorithm, there is a problem that the tracking angle does not match the maximum power point tracking of the inverter, resulting in power generation loss. 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 axis to fully utilize the advantages of the photovoltaic tracking axis and the maximum power point tracking of the inverter and maximize power generation.

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

[0006] Determine a budget tracking angle corresponding to the photovoltaic tracking axis based on the maximum output power of the inverter;

[0007] Control the tracking axis angle of the photovoltaic tracking axis to adjust in the direction of the budget tracking angle;

[0008] During the adjustment process of the tracking axis angle, determine the change trend of the inverter output current;

[0009] Based on the change trend of the inverter output current, perform accuracy detection on the budget tracking angle, and update the budget tracking angle when it is determined that the budget tracking angle does not meet the accuracy requirements.

[0010] Optionally, the determining a budget tracking angle corresponding to the photovoltaic tracking axis based on the maximum output power of the inverter includes:

[0011] Use an astronomical algorithm to determine the astronomical angle of the tracking axis at the initial moment;

[0012] Determine the maximum output power of the inverter corresponding to the astronomical angle of the tracking axis;

[0013] Based on the conversion relationship between power and irradiance, obtain the total irradiance on the inclined plane corresponding to the maximum output power of the inverter;

[0014] According to the calculation equation of the total irradiance on the inclined plane, use the method of exhausting the total irradiance on the horizontal plane to obtain the direct irradiance on the horizontal plane, the diffuse irradiance on the horizontal plane, and the reflected irradiance;

[0015] Apply the inclined plane irradiance model to the direct irradiance on the horizontal plane, the diffuse irradiance on the horizontal plane, and the reflected irradiance, and use the exhaustion method to obtain the inclination angle corresponding to the maximum total irradiance on the inclined plane;

[0016] Determine the inclination angle as the budget tracking angle.

[0017] Optionally, the adjustment of the tracking axis angle of the photovoltaic tracking axis in the direction of the budget tracking angle includes:

[0018] Judge whether the weather type at the current moment has changed compared with the weather type at the previous moment;

[0019] If not, control the tracking axis angle to adjust in the direction of the budget tracking angle according to the first preset angular amplitude;

[0020] If so, control the tracking axis angle to adjust in the direction of the budget tracking angle according to the second preset angular amplitude, where the second preset angular amplitude is greater than the first preset angular amplitude.

[0021] Optionally, the weather type at the current moment is obtained by looking up from the correspondence between the weather type and the direct ratio based on the direct ratio at the current moment;

[0022] The weather type at the previous moment is obtained by looking up from the correspondence between the weather type and the direct ratio based on the direct ratio at the previous moment.

[0023] Optionally, the accuracy detection of the budget tracking angle is performed based on the change trend of the output current of the inverter, and when it is determined that the budget tracking angle does not meet the accuracy requirements, the budget tracking angle is updated, including:

[0024] When the weather type at the current moment has not changed compared with the weather type at the previous moment, determine the average current value at the current moment and the average current value at the previous moment;

[0025] When the average current value at the current moment is greater than the average current value at the previous moment, continue to control the angle of the tracking axis to adjust in the direction of the budget tracking angle, and at the same time, inversely deduce the current optimal tracking angle according to the average current value at the current moment;

[0026] Calculate the absolute value of the difference between the current optimal tracking angle and the optimal tracking angle at the previous moment, where the optimal tracking angle at the previous moment is inversely deduced in advance according to the average current value at the previous moment;

[0027] When the absolute value is not greater than the motor control accuracy, determine that the budget tracking angle meets the accuracy requirement and keep the budget tracking angle unchanged;

[0028] When the absolute value is greater than the motor control accuracy, update the budget tracking angle to the current optimal tracking angle, and control the angle of the tracking axis to adjust in the direction of the current optimal tracking angle;

[0029] Wherein, the average current value at the current moment is the average of the inverter output current value at the current moment and the inverter output current values before the current moment, and the average current value at the previous moment is the average of the inverter output current value at the previous moment and the inverter output current values before the previous moment.

[0030] Optionally, it further includes:

[0031] When the average current value at the current moment is not greater than the average current value at the previous moment, record the counting times as 1, update the budget tracking angle to the current optimal tracking angle, and control the angle of the tracking axis to adjust in the direction of the current optimal tracking angle.

[0032] Optionally, it further includes:

[0033] If the average current value at the next moment is not less than the average current value at the current moment, continue to increment the counting times by 1, update the current optimal tracking angle to the optimal tracking angle at the next moment, and control the angle of the tracking axis to adjust in the direction of the optimal tracking angle at the next moment;

[0034] If the sum of consecutive counting times is greater than the set threshold, stop controlling the adjustment of the tracking axis angle and keep the tracking angle unchanged at this time.

[0035] Optionally, the accuracy detection of the budget tracking angle based on the change trend of the inverter output current and the update of the budget tracking angle when it is determined that the budget tracking angle does not meet the accuracy requirement includes:

[0036] When the weather type at the current moment changes relative to the weather type at the previous moment, divide the second preset amplitude angle adjusted each time for the tracking axis angle into multiple angle adjustment segments;

[0037] Control the tracking axis angle to adjust towards the budget tracking angle direction by one of the angle adjustment segments each time;

[0038] After the adjustment of the first angle adjustment segment is completed, obtain the first output current of the inverter at the actual control angle and the second output current of the inverter at the initial angle;

[0039] If the first output current of the inverter is greater than the second output current of the inverter, control the tracking axis angle to start the adjustment of the second angle adjustment segment, and update the budget tracking angle according to the first output current of the inverter.

[0040] Optionally, it further includes:

[0041] After the adjustment of the Nth angle adjustment segment is completed, obtain the third output current of the inverter at the actual control angle of the Nth angle adjustment segment and the fourth output current of the inverter at the actual control angle of the N - 1th angle adjustment segment;

[0042] When the third output current of the inverter is greater than the fourth output current of the inverter, control the tracking axis angle to start the adjustment of the N + 1th angle adjustment segment, and update the budget tracking angle according to the Nth output current of the inverter, where 2 ≤ N ≤ M, N is a positive integer, and M is the total number of angle adjustment segments into which the second preset amplitude angle is divided. When N = M, there is no N + 1th angle adjustment segment.

[0043] A control device for a photovoltaic tracking axis, which is applied to the controller of a photovoltaic tracking system. The control device includes:

[0044] A budget tracking angle determination unit for determining the budget tracking angle corresponding to the photovoltaic tracking axis based on the maximum output power of the inverter;

[0045] An adjustment unit for controlling the tracking axis angle of the photovoltaic tracking axis to adjust towards the budget tracking angle direction;

[0046] A current change trend determination unit for determining the change trend of the inverter output current during the adjustment of the tracking axis angle;

[0047] An accuracy detection unit for performing accuracy detection on the budget tracking angle based on the change trend of the inverter output current, and updating the budget tracking angle when it is determined that the budget tracking angle does not meet the accuracy requirements.

[0048] Optionally, the budget tracking angle determination unit includes:

[0049] An astronomical angle determination subunit, configured to determine the astronomical angle of the tracking axis at the initial moment by using an astronomical algorithm;

[0050] A maximum output power determination subunit, configured to determine the maximum output power of the inverter corresponding to the astronomical angle of the tracking axis;

[0051] A total irradiance determination subunit, configured to obtain the total irradiance on the inclined plane corresponding to the maximum output power of the inverter based on the conversion relationship between power and irradiance;

[0052] A total irradiance decomposition subunit, configured to obtain the direct irradiance on the horizontal plane, the scattered irradiance on the horizontal plane, and the reflected irradiance by using the method of exhaustive horizontal plane total irradiance according to the calculation equation of the total irradiance on the inclined plane;

[0053] An inclination angle determination subunit, configured to use the inclined plane irradiance model for the direct irradiance on the horizontal plane, the scattered irradiance on the horizontal plane, and the reflected irradiance, and obtain the inclination angle corresponding to the maximum total irradiance on the inclined plane through the exhaustive method;

[0054] A budget tracking angle determination subunit, configured to determine the inclination angle as the budget tracking angle.

[0055] Optionally, the adjustment unit includes:

[0056] A judgment subunit, configured to judge whether the weather type at the current moment has changed relative to the weather type at the previous moment;

[0057] A first adjustment subunit, configured to control the tracking axis angle to adjust towards the budget tracking angle direction at a first preset amplitude angle when the judgment subunit judges no;

[0058] A second adjustment subunit, configured to control the tracking axis angle to adjust towards the budget tracking angle direction at a second preset amplitude angle when the judgment subunit judges yes, where the second preset amplitude angle is greater than the first preset amplitude angle.

[0059] Optionally, the accuracy detection unit includes:

[0060] An average value determination subunit, configured to determine the average current value at the current moment and the average current value at the previous moment when the weather type at the current moment has not changed relative to the weather type at the previous moment, where the average current value at the current moment is the average of the inverter output current value at the current moment and the inverter output current values before the current moment, and the average current value at the previous moment is the average of the inverter output current value at the previous moment and the inverter output current values before the previous moment;

[0061] An angle back-calculation subunit, configured to, when the average current value at the current moment is greater than the average current value at the previous moment, continue to control the angle of the tracking axis to adjust towards the budget tracking angle, and simultaneously back-calculate the current optimal tracking angle according to the average current value at the current moment;

[0062] A calculation subunit, configured to calculate the absolute value of the difference between the current optimal tracking angle and the optimal tracking angle at the previous moment, where the optimal tracking angle at the previous moment is pre-back-calculated according to the average current value at the previous moment;

[0063] An angle maintenance subunit, configured to, when the absolute value is not greater than the motor control accuracy, determine that the budget tracking angle meets the accuracy requirement and maintain the budget tracking angle unchanged;

[0064] A first update subunit, configured to, when the absolute value is greater than the motor control accuracy, update the budget tracking angle to the current optimal tracking angle, and control the angle of the tracking axis to adjust towards the current optimal tracking angle;

[0065] Optionally, the accuracy detection unit further includes:

[0066] A second update subunit, configured to, when the average current value at the current moment is not greater than the average current value at the previous moment, record the count number as 1, update the budget tracking angle to the current optimal tracking angle, and control the angle of the tracking axis to adjust towards the current optimal tracking angle;

[0067] Optionally, the accuracy detection unit further includes:

[0068] A third update subunit, configured to, if the average current value at the next moment is not less than the average current value at the current moment, continue to increment the count number by 1, update the current optimal tracking angle to the optimal tracking angle at the next moment, and control the angle of the tracking axis to adjust towards the optimal tracking angle at the next moment;

[0069] A stop adjustment subunit, configured to, if the sum of consecutive count numbers is greater than a set threshold, stop controlling the adjustment of the angle of the tracking axis and maintain the tracking angle at this time unchanged.

[0070] Optionally, the accuracy detection unit includes:

[0071] An angle division subunit, configured to, when the weather type at the current moment changes relative to the weather type at the previous moment, divide the second preset amplitude angle of each adjustment of the angle of the tracking axis into multiple angle adjustment segments;

[0072] The first control subunit is configured to control the tracking axis angle to be adjusted towards the budget tracking angle direction by one angle adjustment segment each time.

[0073] The first output current acquisition subunit is configured to, after the adjustment of the first angle adjustment segment ends, acquire the first output current of the inverter at the actual control angle and the second output current of the inverter at the initial angle.

[0074] The second control subunit is configured to, if the first output current of the inverter is greater than the second output current of the inverter, control the tracking axis angle to start the adjustment of the second angle adjustment segment and update the budget tracking angle according to the first output current of the inverter.

[0075] Optionally, the accuracy detection unit further includes:

[0076] The second output current acquisition subunit is configured to, after the adjustment of the Nth angle adjustment segment ends, acquire the third output current of the inverter at the actual control angle of the Nth angle adjustment segment and the fourth output current of the inverter at the actual control angle of the (N - 1)th angle adjustment segment.

[0077] The third control subunit is configured to, when the third output current of the inverter is greater than the fourth output current of the inverter, control the tracking axis angle to start the adjustment of the (N + 1)th angle adjustment segment and update the budget tracking angle according to the Nth output current of the inverter, where 2 ≤ N ≤ M, N is a positive integer, and M is the total number of angle adjustment segments into which the second preset amplitude angle is divided. When N = M, there is no (N + 1)th angle adjustment segment.

[0078] A photovoltaic tracking system includes: a photovoltaic module, a tracker, an inverter, and a controller, and the controller includes the control device of the photovoltaic tracking axis described above.

[0079] The controller is communicatively connected to the tracker and the inverter respectively. The tracker is mechanically connected to at least one photovoltaic module, and at least one photovoltaic module is connected to the DC side of the inverter.

[0080] As can be seen from the above technical solutions, the present invention discloses a control method, device and photovoltaic tracking system for a photovoltaic tracking axis. The control method is as follows: Based on the maximum output power of the inverter, determine the budget tracking angle corresponding to the photovoltaic tracking axis, control the tracking axis angle of the photovoltaic tracking axis to adjust in the direction of the budget tracking angle. During the adjustment process of the tracking axis angle, determine the change trend of the inverter output current. Based on the change trend of the inverter output current, perform accuracy detection on the budget tracking angle, and when it is determined that the budget tracking angle does not meet the accuracy requirements, update the budget tracking angle. The present invention obtains the theoretically maximum output power angle of the photovoltaic tracking axis, that is, the budget tracking angle, based on the maximum output power of the inverter. By collecting the change trend of the inverter output current during the adjustment process of the tracking axis angle, perform accuracy detection and update on the budget tracking angle, and realize the closed-loop control of the controller for the photovoltaic tracking axis, so as to give full play to the maximum power point tracking advantages of the photovoltaic tracking axis and the inverter, and maximize the power generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the disclosed drawings.

[0082] Figure 1 It is a flowchart of a control method for a photovoltaic tracking axis disclosed in an embodiment of the present invention;

[0083] Figure 2 It is a flowchart of a method for determining the budget tracking angle corresponding to the photovoltaic tracking axis based on the maximum output power of the inverter disclosed in an embodiment of the present invention;

[0084] Figure 3 It is a flowchart of a method for controlling the tracking axis angle of the photovoltaic tracking axis to adjust in the direction of the budget tracking angle disclosed in an embodiment of the present invention;

[0085] Figure 4 It is a schematic structural diagram of a control device for a photovoltaic tracking axis disclosed in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0086] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the 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 of 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 belong to the scope of protection of the present invention.

[0087] An embodiment of the present invention discloses a control method, device, and photovoltaic tracking system for a photovoltaic tracking axis. The control method is as follows: Based on the maximum output power of the inverter, determine the budget tracking angle corresponding to the photovoltaic tracking axis, control the tracking axis angle of the photovoltaic tracking axis to adjust in the direction of the budget tracking angle. During the adjustment process of the tracking axis angle, determine the change trend of the inverter output current. Based on the change trend of the inverter output current, perform accuracy detection on the budget tracking angle, and when it is determined that the budget tracking angle does not meet the accuracy requirements, update the budget tracking angle. The present invention obtains the theoretically maximum output power angle of the photovoltaic tracking axis, that is, the budget tracking angle, based on the maximum output power of the inverter. By collecting the change trend of the inverter output current during the adjustment process of the tracking axis angle, perform accuracy detection and update on the budget tracking angle, and realize the closed-loop control of the controller for the photovoltaic tracking axis, so as to give full play to the maximum power point tracking advantages of the photovoltaic tracking axis and the inverter, and maximize the power generation.

[0088] See Figure 1 , a flowchart of a control method for a photovoltaic tracking axis disclosed in an embodiment of the present invention. This method is applied to the controller of a photovoltaic tracking system. The control method includes:

[0089] Step S101, determine the budget tracking angle corresponding to the photovoltaic tracking axis based on the maximum output power of the inverter;

[0090] To achieve the matching of the tracking angle and the maximum power point tracking of the inverter, in this embodiment, first determine the budget tracking angle based on the maximum output power of the inverter. This budget tracking angle is also the initial tracking angle for adjusting the photovoltaic tracking axis.

[0091] Step S102, control the tracking axis angle of the photovoltaic tracking axis to adjust in the direction of the budget tracking angle;

[0092] Step S103, during the adjustment process of the tracking axis angle, determine the change trend of the inverter output current;

[0093] Among them, the change trend of the inverter output current refers to whether the inverter output current increases or decreases as the tracking axis angle is adjusted.

[0094] In practical applications, the change trend of the inverter output current can be determined by comparing the average current value at the current moment with the average current value at the previous moment.

[0095] Among them, the average current value at the current moment is: the average value of the inverter output current value at the current moment and the inverter output current values before the current moment (such as 90 groups of inverter output current data before the current moment, specifically determined according to the current acquisition frequency).

[0096] The average current value at the previous moment is: the average value of the inverter output current value at the previous moment and the inverter output current value before the previous moment.

[0097] Step S104: Based on the change trend of the inverter output current, perform accuracy detection on the budget tracking angle, and update the budget tracking angle when it is determined that the budget tracking angle does not meet the accuracy requirements.

[0098] Among them, the budget tracking angle not meeting the accuracy requirements means that: the budget tracking angle is not the current best tracking angle. In this case, it is necessary to update the budget tracking angle to the current best tracking angle.

[0099] In summary, the present invention discloses a control method for a photovoltaic tracking axis. Based on the maximum output power of the inverter, the corresponding budget tracking angle of the photovoltaic tracking axis is determined, and the tracking axis angle of the photovoltaic tracking axis is controlled to adjust in the direction of the budget tracking angle. During the adjustment process of the tracking axis angle, the change trend of the inverter output current is determined. Based on the change trend of the inverter output current, accuracy detection is performed on the budget tracking angle, and the budget tracking angle is updated when it is determined that the budget tracking angle does not meet the accuracy requirements. The present invention obtains the theoretically maximum output power angle of the photovoltaic tracking axis, that is, the budget tracking angle, based on the maximum output power of the inverter. By collecting the change trend of the inverter output current during the adjustment process of the tracking axis angle, accuracy detection and update are performed on the budget tracking angle, realizing the closed-loop control of the controller for the photovoltaic tracking axis, so as to give full play to the maximum power point tracking advantages of the photovoltaic tracking axis and the inverter and maximize the power generation.

[0100] To further optimize the above embodiment, refer to Figure 2 The flowchart of a method for determining the corresponding budget tracking angle of a photovoltaic tracking axis based on the maximum output power of an inverter disclosed in an embodiment of the present invention. The method includes:

[0101] Step S201: Use an astronomical algorithm to determine the astronomical angle of the tracking axis at the initial moment;

[0102] Specifically, according to the date, time, longitude and latitude parameters provided by the GPS (Global Positioning System) module, use an astronomical algorithm to calculate the astronomical angle θ1 of the tracking axis at the initial moment.

[0103] Step S202: Determine the inverter output power corresponding to the astronomical angle of the tracking axis;

[0104] Step S203: Based on the conversion relationship between power and irradiance, obtain the total irradiance of the inclined plane corresponding to the inverter output power;

[0105] Among them, the output power P of the inverter can be directly obtained, or the output power P of the inverter can be calculated according to the collected output current I and output voltage V of the inverter, and P = I·V.

[0106] Based on the conversion relationship between power and irradiance, the total irradiance G on the inclined plane corresponding to the output power of the inverter is obtained p The process is as follows:

[0107] (1) If there is no historical irradiance on the inclined plane and its corresponding inverter output power, a physical model can be used: according to the air temperature T air and inverter data (I, V or P), the component cell temperature T is jointly calculated using the component temperature calculation model and the photovoltaic power generation model pv and the total irradiance G on the inclined plane corresponding to the astronomical angle θ1 of the tracking axis at the initial moment p ;

[0108] Among them, the calculation formula of the component temperature calculation model is as follows:

[0109]

[0110] The calculation formula of the photovoltaic power generation model is as follows:

[0111]

[0112] In the formula, T pv,STC is the cell temperature under standard test conditions, and G STC is the irradiance under standard test conditions.

[0113] (2) If there are historical irradiance data on the inclined plane and its corresponding inverter output power, a machine learning method can be used. The total irradiance G on the inclined plane is calculated by constructing a machine learning model through the historical total irradiance on the inclined plane and its corresponding inverter output power p .

[0114] Generally, the accuracy of the machine learning model is higher than that of the physical model.

[0115] Step S204: According to the calculation equation of the total irradiance on the inclined plane, the direct irradiance on the horizontal plane, the scattered irradiance on the horizontal plane, and the reflected irradiance are obtained by using the method of exhausting the total irradiance on the horizontal plane;

[0116] In this embodiment, according to the calculation equation of the total irradiance G on the inclined plane p , the method of exhausting the total irradiance G on the horizontal plane is used to obtain the direct irradiance G on the horizontal plane b , the scattered irradiance G on the horizontal plane d and the reflected irradiance.

[0117] Among them, the total irradiance G on the inclined planep The calculation equation is as follows:

[0118] G p = G bp + G dp + G r ;

[0119] It should be noted that the direct irradiance G b on the horizontal plane can be solved according to the total irradiance G on the horizontal plane.

[0120] Specifically, according to the total irradiance G on the horizontal plane received in real time and the ideal solar irradiance G real on the ground horizontal plane, the clarity factor k T is calculated, where k T = G / G real .

[0121] The calculation formula for the ideal solar irradiance G real on the ground horizontal plane is as follows:

[0122]

[0123] In the formula, G sc is the solar constant, N d is the day number of the year, is the latitude; δ is the declination angle; w s is the hour angle at sunset, and h is the solar altitude angle.

[0124] According to the clarity factor k T the scattering ratio DF is calculated as follows (the calculation formula is different in different regions):

[0125] DF = 1.0 - 0.09k T ......(k T ≤ 0.22)

[0126] DF = 0.9511 - 0.01604k T + 4.388k T 2 - 16.638k T 3 + 12.336k T 4 ......(0.22 < k T ≤ 0.80)

[0127] DF = 0.165......(k T > 0.80)

[0128] The calculation formula for the scattered irradiance G d on the horizontal plane is as follows:

[0129] G d = G·(1 - DF);

[0130] The direct irradiance G on the horizontal plane b has the following calculation formula:

[0131] G b = G - G d .

[0132] Step S205: Apply the inclined plane irradiation model to the direct irradiance on the horizontal plane, the diffuse irradiance on the horizontal plane, and the reflected irradiance, and obtain the inclination angle corresponding to the maximum total irradiance on the inclined plane through the exhaustive method;

[0133] Step S206: Determine the inclination angle as the budget tracking angle.

[0134] To further optimize the above embodiment, refer to Figure 3 , the flowchart of the method for adjusting the tracking axis angle of the photovoltaic tracking axis in the direction of the budget tracking angle disclosed in the embodiment of the present invention, that is, step S102 specifically includes:

[0135] Step S301: Determine whether the weather type at the current moment has changed compared to the weather type at the previous moment. If not, execute step S302; if so, execute step S303;

[0136] Among them, the weather type can be rainy and cloudy days, cloudy days, sunny days, etc.

[0137] The determination process of the weather type is as follows:

[0138] First, calculate the direct ratio S according to the following formula:

[0139] S = G b / G;

[0140] In the formula, G b is the direct irradiance on the horizontal plane, and G is the total irradiance on the horizontal plane.

[0141] Secondly, based on historical meteorological data, through big data analysis, neural network algorithms, or other mathematical statistical analysis methods, obtain the corresponding relationship between the weather type and the direct ratio S, such as: rainy and cloudy days: 0 ≤ S < 0.15; cloudy days: 0.15 ≤ S < 0.58; sunny days: 0.58 ≤ S < 1, and infer the real-time weather type.

[0142] It should be noted that the corresponding relationship between the weather type and the direct ratio S may be different in different regions, mainly due to the different value range intervals of the direct ratio S in different weather types.

[0143] In this embodiment, the weather type at the current moment is obtained by looking up from the corresponding relationship between the weather type and the direct ratio based on the direct ratio at the current moment;

[0144] The weather type at the previous moment is obtained by looking up from the corresponding relationship between the weather type and the direct ratio based on the direct ratio at the previous moment.

[0145] Step S302: Control the angle of the tracking axis to adjust towards the budget tracking angle direction at the first preset amplitude angle;

[0146] Step S303: Control the angle of the tracking axis to adjust towards the budget tracking angle direction at the second preset amplitude angle.

[0147] Among them, the second preset amplitude angle is greater than the first preset amplitude angle. That is to say, the first preset amplitude angle is a smaller amplitude angle, and the second preset amplitude angle is a larger amplitude angle.

[0148] It should be noted that when it is determined that the budget tracking angle does not meet the accuracy requirements and needs to be updated, different measures are taken according to whether the weather type at the current moment changes relative to the weather type at the previous moment.

[0149] (1) When it is determined that the weather type at the current moment does not change relative to the weather type at the previous moment, control the angle of the tracking axis to adjust towards the budget tracking angle direction at the first preset amplitude angle (smaller amplitude angle), and at the same time collect and analyze the output current of the inverter. Since the output current of the inverter is real-time data and fluctuates greatly, current fluctuation smoothing processing is required. The present invention realizes current fluctuation smoothing processing by calculating the average current value.

[0150] Therefore, to further optimize the above embodiment, step S104 may include:

[0151] (1) When the weather type at the current moment does not change relative to the weather type at the previous moment, determine the average current value I(t) at the current moment and the average current value I(t - 1) at the previous moment;

[0152] Among them, the average current value I(t) at the current moment is the average value of the output current value of the inverter at the current moment and the output current values of the inverter before the current moment (such as 90 groups of output current data of the inverter before the current moment, specifically determined according to the current acquisition frequency). The average current value I(t - 1) at the previous moment is the average value of the output current value of the inverter at the previous moment and the output current values of the inverter before the previous moment (such as 90 groups of output current data of the inverter before the previous moment, specifically determined according to the current acquisition frequency).

[0153] (2) When the average current value at the current moment is greater than the average current value at the previous moment, continue to control the angle of the tracking axis to adjust towards the budget tracking angle direction, and at the same time inversely deduce the current optimal tracking angle θ(t) according to the average current value at the current moment;

[0154] (3) Calculate the absolute value of the difference between the current optimal tracking angle and the optimal tracking angle θ(t - 1) at the previous moment;

[0155] Wherein, the optimal tracking angle at the previous moment is obtained by inversely deducing according to the average current value at the previous moment in advance.

[0156] (4) When the absolute value is not greater than the motor control accuracy, it is determined that the budget tracking angle meets the accuracy requirement, and the budget tracking angle remains unchanged;

[0157] If |θ(t) - θ(t - 1)| ≤ m, where m is the motor control accuracy, it is determined that the budget tracking angle meets the accuracy requirement, the budget tracking angle is not updated, and the budget tracking angle remains unchanged.

[0158] (5) When the absolute value is greater than the motor control accuracy, update the budget tracking angle to the current optimal tracking angle, and control the tracking axis angle to adjust in the direction of the current optimal tracking angle.

[0159] If |θ(t) - θ(t - 1)| > m, update the budget tracking angle to θ(t), and control the tracking axis angle to adjust in the direction of θ(t).

[0160] (6) When the average current value at the current moment is not greater than the average current value at the previous moment, record the counting number as 1, update the budget tracking angle to the current optimal tracking angle, and control the tracking axis angle to adjust in the direction of the current optimal tracking angle.

[0161] If I(t) ≤ I(t - 1), record the counting number count = 1, at the same time update the budget tracking angle to θ(t), and control the tracking axis angle to adjust in the direction of θ(t).

[0162] (7) If the average current value at the next moment is not less than the average current value at the current moment, continue to add 1 to the counting number, update the current optimal tracking angle to the optimal tracking angle θ(t + 1) at the next moment, and control the tracking axis angle to adjust in the direction of the optimal tracking angle at the next moment; if the sum of consecutive counting numbers is greater than the set threshold, stop controlling the adjustment of the tracking axis angle and keep the tracking angle unchanged at this time.

[0163] Specifically, if I(t + 1) ≤ I(t), then continue to add 1 to the counting number, that is, count = count + 1, at the same time, update the budget angle to θ(t + 1), and control the tracking axis angle to adjust in the direction of θ(t + 1).

[0164] If the sum of consecutive counts is greater than the set threshold limit, stop controlling the tracking axis angle adjustment and keep the tracking angle unchanged at this time.

[0165] (2) When it is determined that the weather type at the current moment has changed relative to the weather type at the previous moment, control the tracking axis angle to adjust towards the budget tracking angle direction according to the second preset amplitude angle (the larger amplitude angle). To avoid the system instability caused by the excessive one-time adjustment of the photovoltaic tracking axis angle, in this embodiment, a strategy of dividing the second preset amplitude angle into multiple angle adjustment segments is adopted to control the angle of the photovoltaic tracking axis; at the same time, collect the output current of the inverter and perform fluctuation smoothing processing, and then analyze and judge.

[0166] Therefore, to further optimize the above embodiment, step S104 may include:

[0167] (1) When the weather type at the current moment has changed relative to the weather type at the previous moment, divide the second preset amplitude angle of each adjustment of the tracking axis angle into multiple angle adjustment segments;

[0168] Among them, the value of each angle adjustment segment can be determined according to the motor speed and the size of the adjustment angle, such as 5°, and the present invention does not make a limitation here.

[0169] (2) Control the tracking axis angle to adjust towards the budget tracking angle direction by one of the angle adjustment segments each time;

[0170] (3) After the adjustment of the first angle adjustment segment is completed, obtain the first output current of the inverter at the actual control angle and the second output current of the inverter at the initial angle;

[0171] (4) If the first output current of the inverter is greater than the second output current of the inverter, control the tracking axis angle to start the adjustment of the second angle adjustment segment, and update the budget tracking angle according to the first output current of the inverter.

[0172] Among them, in this embodiment, the corresponding optimal tracking angle is deduced from the first output current of the inverter, and the budget tracking angle is updated to the optimal tracking angle corresponding to the first output current of the inverter.

[0173] It should be noted that (1) to (4) in this embodiment are for the process of updating the budget tracking angle after the adjustment of the first angle adjustment segment is completed. Since the first angle adjustment segment is the first angle adjustment segment, when determining whether to update the budget tracking angle, the first output current of the inverter at the actual control angle and the second output current of the inverter at the initial angle are compared in size.

[0174] (5) After the adjustment of the Nth angle adjustment segment is completed, obtain the third output current of the inverter at the actual control angle of the Nth angle adjustment segment and the fourth output current of the inverter at the actual control angle of the (N - 1)th angle adjustment segment;

[0175] (6) When the third output current of the inverter is greater than the fourth output current of the inverter, control the tracking axis angle to start the adjustment of the (N + 1)th angle adjustment segment, and update the budget tracking angle according to the Nth output current of the inverter.

[0176] Wherein, 2 ≤ N ≤ M, N is a positive integer, and M is the total number of angle adjustment segments into which the second preset amplitude angle is divided. When N = M, there is no (N + 1)th angle adjustment segment.

[0177] In this embodiment, (5) and (6) are directed to the process of updating the budget tracking angle after the adjustment of the first angle adjustment segment is completed and after the tracking axis angle is adjusted according to the angle adjustment segment after the first angle adjustment segment. Since after the adjustment of the Nth angle adjustment segment is completed, the third output current of the inverter at the actual control angle of the Nth angle adjustment segment and the fourth output current of the inverter at the actual control angle of the (N - 1)th angle adjustment segment can be obtained. At this time, it is no longer necessary to consider the second output current of the inverter at the initial angle, but only to directly compare the third output current of the inverter and the fourth output current of the inverter.

[0178] Corresponding to the above method embodiment, the present invention also discloses a control device for a photovoltaic tracking axis.

[0179] See Figure 4 , a schematic structural diagram of a control device for a photovoltaic tracking axis disclosed in an embodiment of the present invention. The control device is applied to a controller of a photovoltaic tracking system, and the control device includes:

[0180] A budget tracking angle determination unit 401, configured to determine a budget tracking angle corresponding to the photovoltaic tracking axis based on the maximum output power of the inverter;

[0181] To achieve the tracking angle matching with the maximum power point tracking of the inverter, in this embodiment, the budget tracking angle is first determined based on the maximum output power of the inverter, and this budget tracking angle is also the initial tracking angle for adjusting the photovoltaic tracking axis.

[0182] An adjustment unit 402, configured to control the tracking axis angle of the photovoltaic tracking axis to adjust in the direction of the budget tracking angle;

[0183] A current change trend determination unit 403, configured to determine the change trend of the inverter output current during the adjustment of the tracking axis angle;

[0184] Among them, the changing trend of the inverter output current refers to whether the inverter output current increases or decreases as the tracking axis angle is adjusted.

[0185] In practical applications, the changing trend of the inverter output current can be determined by comparing the average current value at the current moment with the average current value at the previous moment.

[0186] Among them, the average current value at the current moment is: the average value of the inverter output current value at the current moment and the inverter output current values before the current moment (such as 90 groups of inverter output current data before the current moment, specifically determined according to the current acquisition frequency).

[0187] The average current value at the previous moment is: the average value of the inverter output current value at the previous moment and the inverter output current values before the previous moment.

[0188] The accuracy detection unit 404 is used to detect the accuracy of the budget tracking angle based on the changing trend of the inverter output current, and update the budget tracking angle when it is determined that the budget tracking angle does not meet the accuracy requirements.

[0189] Among them, the budget tracking angle not meeting the accuracy requirements means that: the budget tracking angle is not the current best tracking angle. In this case, the budget tracking angle needs to be updated to the current best tracking angle.

[0190] In summary, the present invention discloses a control device for a photovoltaic tracking axis, which determines the budget tracking angle corresponding to the photovoltaic tracking axis based on the maximum output power of the inverter, controls the tracking axis angle of the photovoltaic tracking axis to adjust towards the budget tracking angle. During the adjustment process of the tracking axis angle, the changing trend of the inverter output current is determined, and based on the changing trend of the inverter output current, the accuracy of the budget tracking angle is detected, and the budget tracking angle is updated when it is determined that the budget tracking angle does not meet the accuracy requirements. The present invention obtains the theoretically maximum output power angle of the photovoltaic tracking axis, that is, the budget tracking angle, based on the maximum output power of the inverter, and detects and updates the accuracy of the budget tracking angle by collecting the changing trend of the inverter output current during the adjustment process of the tracking axis angle, realizing the closed-loop control of the photovoltaic tracking axis by the controller, so as to give full play to the maximum power point tracking advantages of the photovoltaic tracking axis and the inverter and maximize the power generation.

[0191] To further optimize the above embodiment, the budget tracking angle determination unit 401 may include:

[0192] The astronomical angle determination subunit is used to determine the astronomical angle of the tracking axis at the initial moment by using an astronomical algorithm;

[0193] The maximum output power determination subunit is configured to determine the maximum output power of the inverter corresponding to the astronomical angle of the tracking axis;

[0194] The total irradiance determination subunit is configured to obtain the total irradiance of the inclined plane corresponding to the maximum output power of the inverter based on the conversion relationship between power and irradiance;

[0195] The total irradiance decomposition subunit is configured to obtain the direct irradiance on the horizontal plane, the diffuse irradiance on the horizontal plane, and the reflected irradiance by using the method of exhaustive horizontal plane total irradiance according to the calculation equation of the total irradiance of the inclined plane;

[0196] The inclination angle determination subunit is configured to use the inclined plane irradiance model for the direct irradiance on the horizontal plane, the diffuse irradiance on the horizontal plane, and the reflected irradiance, and obtain the inclination angle corresponding to the maximum total irradiance of the inclined plane through the exhaustive method;

[0197] The budget tracking angle determination subunit is configured to determine the inclination angle as the budget tracking angle.

[0198] It should be noted that for the specific working principles of the components in the budget tracking angle determination unit 401, please refer to the corresponding parts of the method embodiments, which will not be elaborated here.

[0199] To further optimize the above embodiments, the adjustment unit 402 may include:

[0200] The judgment subunit is configured to judge whether the weather type at the current moment has changed compared with the weather type at the previous moment;

[0201] The first adjustment subunit is configured to control the tracking axis angle to adjust towards the budget tracking angle direction at a first preset amplitude angle when the judgment subunit judges no;

[0202] The second adjustment subunit is configured to control the tracking axis angle to adjust towards the budget tracking angle direction at a second preset amplitude angle when the judgment subunit judges yes, where the second preset amplitude angle is greater than the first preset amplitude angle.

[0203] Among them, the weather type may be rainy and cloudy days, cloudy days, sunny days, etc.

[0204] The determination process of the weather type is as follows:

[0205] First, calculate the direct ratio S according to the following formula:

[0206] S = G b / G;

[0207] In the formula, G b is the direct irradiance on the horizontal plane, and G is the total irradiance on the horizontal plane.

[0208] Secondly, historical meteorological data is used to obtain the corresponding relationship between weather types and the direct ratio S through big data analysis, neural network algorithms or other mathematical statistical analysis methods. For example: rainy and cloudy days: 0 ≤ S < 0.15; partly cloudy days: 0.15 ≤ S < 0.58; sunny days: 0.58 ≤ S < 1, so as to infer the real-time weather type.

[0209] It should be noted that the corresponding relationship between weather types and the direct ratio S may be different in different regions, mainly because the value range intervals of the direct ratio S for different weather types are different.

[0210] It should be noted that when it is determined that the budget tracking angle does not meet the accuracy requirements and the budget tracking angle needs to be updated, different measures are taken according to whether the weather type at the current moment has changed compared with the weather type at the previous moment.

[0211] (1) When it is determined that the weather type at the current moment has not changed compared with the weather type at the previous moment, control the tracking axis angle to adjust towards the budget tracking angle according to the first preset amplitude angle (a relatively small amplitude angle), and at the same time collect and analyze the inverter output current. Since the inverter output current is real-time data and fluctuates greatly, current fluctuation smoothing processing is required. The present invention realizes current fluctuation smoothing processing by calculating the average current value.

[0212] Therefore, to further optimize the above embodiment, the accuracy detection unit 404 may include:

[0213] An average value determination subunit, configured to determine the current moment current average value and the previous moment current average value when the weather type at the current moment has not changed compared with the weather type at the previous moment, wherein the current moment current average value is: the average value of the inverter output current value at the current moment and the inverter output current values before the current moment, and the previous moment current average value is: the average value of the inverter output current value at the previous moment and the inverter output current values before the previous moment;

[0214] An angle back-calculation subunit, configured to continue to control the tracking axis angle to adjust towards the budget tracking angle when the current moment current average value is greater than the previous moment current average value, and at the same time back-calculate the current optimal tracking angle according to the current moment current average value;

[0215] A calculation subunit, configured to calculate the absolute value of the difference between the current optimal tracking angle and the previous moment optimal tracking angle, wherein the previous moment optimal tracking angle is pre-back-calculated according to the previous moment current average value;

[0216] An angle maintaining subunit, configured to determine that the budget tracking angle meets the accuracy requirement and maintain the budget tracking angle unchanged when the absolute value is not greater than the motor control accuracy;

[0217] A first updating subunit, configured to update the budget tracking angle to the current best tracking angle and control the tracking axis angle to adjust in the direction of the current best tracking angle when the absolute value is greater than the motor control accuracy.

[0218] To further optimize the above embodiment, the accuracy detection unit 404 may further include:

[0219] A second updating subunit, configured to record the counting times as 1, update the budget tracking angle to the current best tracking angle, and control the tracking axis angle to adjust in the direction of the current best tracking angle when the average current value at the current moment is not greater than the average current value at the previous moment.

[0220] To further optimize the above embodiment, the accuracy detection unit may further include:

[0221] A third updating subunit, configured to continue adding 1 to the counting times, update the current best tracking angle to the best tracking angle at the next moment, and control the tracking axis angle to adjust in the direction of the best tracking angle at the next moment if the average current value at the next moment is not less than the average current value at the current moment;

[0222] A stop adjusting subunit, configured to stop controlling the adjustment of the tracking axis angle and maintain the tracking angle unchanged at this time if the sum of consecutive counting times is greater than a set threshold.

[0223] (2) When it is determined that the weather type at the current moment changes relative to the weather type at the previous moment, control the tracking axis angle to adjust in the direction of the budget tracking angle according to a second preset amplitude angle (a larger amplitude angle). To avoid the system instability caused by the excessive one-time adjustment of the photovoltaic tracking axis angle, this embodiment adopts a strategy of dividing the second preset amplitude angle into multiple angle adjustment segments to control the angle of the photovoltaic tracking axis; at the same time, collect the inverter output current and perform fluctuation smoothing processing, and then analyze and judge.

[0224] To further optimize the above embodiment, the accuracy detection unit 404 may include:

[0225] An angle dividing subunit, configured to divide the second preset amplitude angle adjusted by the tracking axis angle each time into multiple angle adjustment segments when the weather type at the current moment changes relative to the weather type at the previous moment;

[0226] A first control subunit, configured to control the tracking axis angle to be adjusted towards the budget tracking angle direction by one of the angle adjustment segments each time.

[0227] A first output current acquisition subunit, configured to, after the adjustment of the first angle adjustment segment ends, acquire the first output current of the inverter at the actual control angle and the second output current of the inverter at the initial angle.

[0228] A second control subunit, configured to, if the first output current of the inverter is greater than the second output current of the inverter, control the tracking axis angle to start the adjustment of the second angle adjustment segment, and update the budget tracking angle according to the first output current of the inverter.

[0229] To further optimize the above embodiments, the accuracy detection unit may further include:

[0230] A second output current acquisition subunit, configured to, after the adjustment of the Nth angle adjustment segment ends, acquire the third output current of the inverter at the actual control angle of the Nth angle adjustment segment and the fourth output current of the inverter at the actual control angle of the (N - 1)th angle adjustment segment.

[0231] A third control subunit, configured to, when the third output current of the inverter is greater than the fourth output current of the inverter, control the tracking axis angle to start the adjustment of the (N + 1)th angle adjustment segment, and update the budget tracking angle according to the Nth output current of the inverter, where 2 ≤ N ≤ M, N is a positive integer, M is the total number of the angle adjustment segments into which the second preset amplitude angle is divided, and when N = M, there is no (N + 1)th angle adjustment segment.

[0232] It should be noted that for the specific working principles of the components in the control device, please refer to the corresponding parts of the method embodiments, which will not be elaborated here.

[0233] Corresponding to the above embodiments, the present invention also discloses a photovoltaic tracking system, including: a photovoltaic module, a tracker, an inverter, and a controller, where the controller includes the control device of the photovoltaic tracking axis in the above embodiments;

[0234] The controller is respectively communicatively connected to the tracker and the inverter, the 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 inverter.

[0235] Among them, for the control process of the photovoltaic tracking system for the photovoltaic tracking axis in this embodiment, please refer to the corresponding parts of the above embodiments, which will not be elaborated here.

[0236] In summary, the present invention discloses a photovoltaic tracking system, including a photovoltaic module, a tracker, an inverter, and a controller. The controller determines a budget tracking angle corresponding to the photovoltaic tracking axis based on the maximum output power of the inverter, controls the tracking axis angle of the photovoltaic tracking axis to adjust in the direction of the budget tracking angle. During the adjustment of the tracking axis angle, the change trend of the inverter output current is determined. Based on the change trend of the inverter output current, the accuracy of the budget tracking angle is detected, and when it is determined that the budget tracking angle does not meet the accuracy requirements, the budget tracking angle is updated. The present invention obtains the theoretically maximum output power angle of the photovoltaic tracking axis, that is, the budget tracking angle, based on the maximum output power of the inverter, and detects and updates the accuracy of the budget tracking angle by collecting the change trend of the inverter output current during the adjustment of the tracking axis angle, realizing the closed-loop control of the photovoltaic tracking axis by the controller, so as to give full play to the maximum power point tracking advantages of the photovoltaic tracking axis and the inverter and maximize the power generation.

[0237] Finally, it should also be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover a non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the presence of additional identical elements in the process, method, article or device including the element.

[0238] The various embodiments in this specification are described in a progressive manner, and the key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the various embodiments can be referred to each other.

[0239] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control method for a photovoltaic tracking axis, characterized in that, A controller applied to a photovoltaic tracking system, the control method comprising: Determining a budget tracking angle corresponding to a photovoltaic tracking axis based on the maximum output power of an inverter; Controlling the tracking axis angle of the photovoltaic tracking axis to adjust towards the budget tracking angle; During the adjustment of the tracking axis angle, determining the change trend of the inverter output current; Based on the change trend of the inverter output current, performing accuracy detection on the budget tracking angle, and when it is determined that the budget tracking angle does not meet the accuracy requirements, updating the budget tracking angle. During the update process, different update methods are adopted according to whether the weather type at the current moment changes relative to the weather type at the previous moment.

2. The control method according to claim 1, wherein The determining a budget tracking angle corresponding to a photovoltaic tracking axis based on the maximum output power of an inverter includes: Using an astronomical algorithm to determine the astronomical angle of the tracking axis at the initial moment; Determining the maximum output power of the inverter corresponding to the astronomical angle of the tracking axis; Based on the conversion relationship between power and irradiance, obtaining the total slope irradiance corresponding to the maximum output power of the inverter; According to the calculation equation of the total slope irradiance, using the method of exhaustive horizontal plane total irradiance to obtain the direct irradiance on the horizontal plane, the diffuse irradiance on the horizontal plane, and the reflected irradiance; Adopting a slope irradiance model for the direct irradiance on the horizontal plane, the diffuse irradiance on the horizontal plane, and the reflected irradiance, and obtaining the inclination angle corresponding to the maximum total slope irradiance through the exhaustive method; Determining the inclination angle as the budget tracking angle.

3. The control method according to claim 1, wherein The controlling the tracking axis angle of the photovoltaic tracking axis to adjust towards the budget tracking angle includes: Judging whether the weather type at the current moment changes relative to the weather type at the previous moment; If not, controlling the tracking axis angle to adjust towards the budget tracking angle according to a first preset amplitude angle; If so, controlling the tracking axis angle to adjust towards the budget tracking angle according to a second preset amplitude angle, where the second preset amplitude angle is greater than the first preset amplitude angle.

4. The control method according to claim 3, characterized in that The weather type at the current moment is obtained by looking up from the corresponding relationship between the weather type and the direct ratio based on the direct ratio at the current moment; The weather type at the previous moment is obtained by looking up from the corresponding relationship between the weather type and the direct ratio based on the direct ratio at the previous moment.

5. The control method according to claim 1, wherein The performing accuracy detection on the budget tracking angle based on the change trend of the inverter output current and updating the budget tracking angle when it is determined that the budget tracking angle does not meet the accuracy requirements includes: When the weather type at the current moment does not change relative to the weather type at the previous moment, determining the current moment current average value and the previous moment current average value; When the current moment current average value is greater than the previous moment current average value, continuing to control the tracking axis angle to adjust towards the budget tracking angle, and at the same time inversely deriving the current optimal tracking angle according to the current moment current average value; Calculating the absolute value of the difference between the current optimal tracking angle and the previous moment optimal tracking angle, where the previous moment optimal tracking angle is inversely derived in advance according to the previous moment current average value; When the absolute value is not greater than the motor control accuracy, it is determined that the budget tracking angle meets the accuracy requirement, and the budget tracking angle is maintained unchanged; When the absolute value is greater than the motor control accuracy, update the budget tracking angle to the current best tracking angle, and control the tracking axis angle to adjust in the direction of the current best tracking angle; Wherein, the average current value at the current moment is the average of the inverter output current value at the current moment and the inverter output current value before the current moment, and the average current value at the previous moment is the average of the inverter output current value at the previous moment and the inverter output current value before the previous moment.

6. The control method according to claim 5, characterized in that It further includes: When the average current value at the current moment is not greater than the average current value at the previous moment, record the counting number as 1, update the budget tracking angle to the current best tracking angle, and control the tracking axis angle to adjust in the direction of the current best tracking angle.

7. The control method according to claim 6, wherein It further includes: If the average current value at the next moment is not less than the average current value at the current moment, continue to add 1 to the counting number, update the current best tracking angle to the best tracking angle at the next moment, and control the tracking axis angle to adjust in the direction of the best tracking angle at the next moment; If the sum of consecutive counting numbers is greater than the set threshold, stop controlling the adjustment of the tracking axis angle and maintain the tracking angle at this time unchanged.

8. The control method according to claim 1, characterized in that, Based on the change trend of the inverter output current, perform accuracy detection on the budget tracking angle, and when it is determined that the budget tracking angle does not meet the accuracy requirement, update the budget tracking angle, including: When the weather type at the current moment changes relative to the weather type at the previous moment, divide the second preset amplitude angle adjusted by the tracking axis angle each time into multiple angle adjustment segments; Control the tracking axis angle to adjust in the direction of the budget tracking angle according to one of the angle adjustment segments each time; After the adjustment of the first angle adjustment segment is completed, obtain the first output current of the inverter at the actual control angle and the second output current of the inverter at the initial angle; If the first output current of the inverter is greater than the second output current of the inverter, control the tracking axis angle to start the adjustment of the second angle adjustment segment, and update the budget tracking angle according to the first output current of the inverter.

9. The control method according to claim 8, wherein It further includes: After the adjustment of the Nth angle adjustment segment is completed, obtain the third output current of the inverter at the actual control angle of the Nth angle adjustment segment and the fourth output current of the inverter at the actual control angle of the N-1th angle adjustment segment; When the third output current of the inverter is greater than the fourth output current of the inverter, control the tracking axis angle to start the adjustment of the N+1th angle adjustment segment, and update the budget tracking angle according to the Nth output current of the inverter, where 2≤N≤M, N is a positive integer, and M is the total number of angle adjustment segments into which the second preset amplitude angle is divided. When N = M, there is no N+1th angle adjustment segment.

10. A control device for a photovoltaic tracking axis, characterized in that, A controller applied to a photovoltaic tracking system, the control device includes: A budget tracking angle determination unit for determining a budget tracking angle corresponding to a photovoltaic tracking axis based on the maximum output power of an inverter; An adjustment unit for controlling the tracking axis angle of the photovoltaic tracking axis to be adjusted towards the budget tracking angle; A current change trend determination unit for determining the change trend of the inverter output current during the adjustment of the tracking axis angle; An accuracy detection unit for performing accuracy detection on the budget tracking angle based on the change trend of the inverter output current, and updating the budget tracking angle when it is determined that the budget tracking angle does not meet the accuracy requirements. During the update process, different update methods are adopted according to whether the weather type at the current moment has changed compared to the weather type at the previous moment.

11. The control device according to claim 10, characterized in that, The budget tracking angle determination unit includes: An astronomical angle determination subunit for determining the astronomical angle of the tracking axis at the initial moment using an astronomical algorithm; A maximum output power determination subunit for determining the maximum output power of the inverter corresponding to the astronomical angle of the tracking axis; A total irradiance determination subunit for obtaining the total irradiance on the inclined plane corresponding to the maximum output power of the inverter based on the conversion relationship between power and irradiance; A total irradiance decomposition subunit for obtaining the direct irradiance on the horizontal plane, the scattered irradiance on the horizontal plane, and the reflected irradiance by using the method of exhaustively listing the total irradiance on the horizontal plane according to the calculation equation of the total irradiance on the inclined plane; An inclination angle determination subunit for using an inclined plane irradiance model for the direct irradiance on the horizontal plane, the scattered irradiance on the horizontal plane, and the reflected irradiance, and obtaining the inclination angle corresponding to the maximum total irradiance on the inclined plane by the method of exhaustion; A budget tracking angle determination subunit for determining the inclination angle as the budget tracking angle.

12. The control device according to claim 10, characterized in that, The adjustment unit includes: A judgment subunit for judging whether the weather type at the current moment has changed compared to the weather type at the previous moment; A first adjustment subunit for controlling the tracking axis angle to be adjusted towards the budget tracking angle at a first preset amplitude angle when the judgment subunit judges no; A second adjustment subunit for controlling the tracking axis angle to be adjusted towards the budget tracking angle at a second preset amplitude angle when the judgment subunit judges yes, where the second preset amplitude angle is greater than the first preset amplitude angle.

13. The control device according to claim 10, characterized in that, The accuracy detection unit includes: An average value determination subunit for determining the average current value at the current moment and the average current value at the previous moment when the weather type at the current moment has not changed compared to the weather type at the previous moment. Wherein, the average current value at the current moment is the average of the inverter output current value at the current moment and the inverter output current values before the current moment, and the average current value at the previous moment is the average of the inverter output current value at the previous moment and the inverter output current values before the previous moment; An angle back-calculation sub-unit, configured to, when the average current value at the current moment is greater than the average current value at the previous moment, continue to control the angle of the tracking axis to adjust towards the budget tracking angle direction, and at the same time back-calculate the current optimal tracking angle according to the average current value at the current moment; A calculation sub-unit, configured to calculate the absolute value of the difference between the current optimal tracking angle and the optimal tracking angle at the previous moment, wherein the optimal tracking angle at the previous moment is pre-back-calculated according to the average current value at the previous moment; An angle maintenance sub-unit, configured to, when the absolute value is not greater than the motor control accuracy, determine that the budget tracking angle meets the accuracy requirement and maintain the budget tracking angle unchanged; A first update sub-unit, configured to, when the absolute value is greater than the motor control accuracy, update the budget tracking angle to the current optimal tracking angle, and control the angle of the tracking axis to change to adjust towards the current optimal tracking angle direction.

14. The control device according to claim 13, characterized in that, The accuracy detection unit further includes: A second update sub-unit, configured to, when the average current value at the current moment is not greater than the average current value at the previous moment, record the count number as 1, update the budget tracking angle to the current optimal tracking angle, and control the angle of the tracking axis to change to adjust towards the current optimal tracking angle direction.

15. The control device according to claim 14, characterized in that, The accuracy detection unit further includes: A third update sub-unit, configured to, if the average current value at the next moment is not less than the average current value at the current moment, continue to increment the count number by 1, update the current optimal tracking angle to the optimal tracking angle at the next moment, and control the angle of the tracking axis to change to adjust towards the optimal tracking angle direction at the next moment; A stop adjustment sub-unit, configured to, if the sum of consecutive count numbers is greater than a set threshold, stop controlling the adjustment of the angle of the tracking axis and maintain the tracking angle at this time unchanged.

16. The control device according to claim 10, characterized in that, The accuracy detection unit includes: An angle division sub-unit, configured to divide the second preset amplitude angle of each adjustment of the tracking axis angle into multiple angle adjustment segments when the weather type at the current moment changes relative to the weather type at the previous moment; A first control sub-unit, configured to control the angle of the tracking axis to adjust towards the budget tracking angle direction by one of the angle adjustment segments each time; A first output current acquisition sub-unit, configured to, when the adjustment of the first angle adjustment segment ends, acquire the first output current of the inverter at the actual control angle and the second output current of the inverter at the initial angle; A second control sub-unit, configured to, if the first output current of the inverter is greater than the second output current of the inverter, control the angle of the tracking axis to start the adjustment of the second angle adjustment segment, and update the budget tracking angle according to the first output current of the inverter.

17. The control device according to claim 16, characterized in that, The accuracy detection unit further includes: A second output current acquisition sub-unit, configured to, when the adjustment of the Nth angle adjustment segment ends, acquire the third output current of the inverter at the actual control angle of the Nth angle adjustment segment and the fourth output current of the inverter at the actual control angle of the (N - 1)th angle adjustment segment; A third control subunit, configured to, when the third output current of the inverter is greater than the fourth output current of the inverter, control the tracking axis angle to start the adjustment of the (N + 1)-th angle adjustment segment, and update the budget tracking angle according to the N-th output current of the inverter, where 2 ≤ N ≤ M, N is a positive integer, and M is the total number of the angle adjustment segments into which the second preset amplitude angle is divided. When N = M, there is no (N + 1)-th angle adjustment segment.

18. A photovoltaic tracking system, characterized in that, Comprising: a photovoltaic module, a tracker, an inverter, and a controller, where the controller includes the control device for a photovoltaic tracking axis according to any one of claims 10 to 17; the controller is communicatively connected to the tracker and the inverter respectively, the 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 inverter.

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