Solar maximum power point tracking system and method based on sun motion trail

Abstract

The invention discloses a solar maximum power point tracking system and method based on sun motion trails, and belongs to the technical field of solar application. The system comprises an initialization and pre-starting module, a sun-oriented movement track module, a data processing module, a control module, a driving module, an MPPT module, an energy storage module and a power supply, and the initialization and pre-starting module is used for initialization and pre-starting of the system and communicates with the sun-oriented movement track module; the sun-oriented movement track module is respectively communicated with the data processing module and the MPPT module, the data processing module, the control module and the driving module are communicated in sequence, the control module controls the driving module to move according to information transmitted by the data processing module, the MPPT module is communicated with the energy storage module, and output electric energy is stored in the energy storage module. According to the solar azimuth information provided by the spherical detector, the stepping motor is adjusted, so that sunlight always directly irradiates the photovoltaic power generation panel, the photovoltaic power generation panel works at the maximum power point, and the energy utilization rate is maximized.

Description

Technical Field

[0001] The invention belongs to the technical field of solar energy application, and in particular relates to a solar energy maximum power point tracking system based on an apparent sun motion trajectory. Background Art

[0002] Today, as the energy crisis becomes increasingly serious, solar energy has gradually gained wide attention and application due to its advantages of cleanliness and economy. In the development of solar energy technology, people have gradually discovered that tracking solar energy can greatly improve the utilization rate of solar energy. According to the photovoltaic PU curve, finding the maximum power point helps to improve the utilization efficiency, so the research on tracking solar energy and its maximum power point has gradually attracted people's attention. At present, the solar automatic tracking system can be divided into: visual sun trajectory tracking system, photoelectric tracking system, tracking system based on digital image processing and hybrid tracking system according to the different tracking methods of the control system; according to the execution mode, it can be divided into single-axis tracking system and dual-axis tracking system. In the traditional tracking method, the solar tracking control system based on solar thermal power generation divides the direction and angle adjustment into coarse adjustment and fine adjustment. Coarse adjustment means that the photovoltaic panel is facing the part with sunlight according to the longitude and latitude data of the sun's azimuth on that day, and then the photosensitive sensor is used to detect the point where the light is vertically irradiated for fine adjustment, so that the photovoltaic panel is perpendicular to the incident light.

[0003] The shadow information on the existing sundial can only directly reflect the changes in the movement trajectory of the sun within a day. Since the sun rises in the east and sets in the west within a day and moves within the Tropic of Cancer and the Tropic of Capricorn within a year, in order to be applicable throughout the year, the altitude and azimuth of the sun must be calculated through formulas. The calculation is complicated, the procedure is cumbersome, and the calculation results are not accurate enough. Summary of the invention

[0004] In view of the above technical problems, the present invention provides a solar maximum power point tracking system and tracking method based on the apparent sun motion trajectory. The system adjusts the stepper motors in the horizontal and vertical axes according to the sun position information provided by the spherical detector, so that the sunlight always directly hits the photovoltaic power generation panel to obtain the maximum solar radiation energy, and then tracks the maximum power point of the solar energy so that it always works at the maximum power point to maximize the energy utilization rate.

[0005] The spherical detector of the present invention can realize the omni-directional and all-weather solar motion trajectory, process the collected information data, and realize the dual-axis control of the photovoltaic power generation panel and the tracking algorithm of the maximum power point of solar energy.

[0006] The spherical detector of the present invention has a one-to-one correspondence between the matrix output by the photosensitive sensor and the result output by the data processor, and also has a one-to-one correspondence with the adjustment steps of the stepping motor. Each output result corresponds to an adjustment of the stepping motor, which is adjusted to the position where the sun is directly shining, so as to achieve sun tracking. After finding the position where the sun is directly shining, the maximum radiation can be obtained, and then the maximum power point is tracked, so that the photovoltaic power generation panel always works near the maximum power point, and the photovoltaic power generation rate is maximized.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] The present invention discloses a solar maximum power point dual-axis tracking system based on the apparent sun motion trajectory, comprising an initialization and pre-starting module, an apparent sun motion trajectory module, a data processing module, a control module, a driving module, an MPPT module, an energy storage module and a power supply. The initialization and pre-starting module is used for the initialization and pre-starting of the system and communicates with the apparent sun motion trajectory module. The apparent sun motion trajectory module communicates with the data processing module and the MPPT module respectively. The data processing module, the control module and the driving module communicate in sequence. The control module controls the movement of the driving module according to the information transmitted by the data processing module, so that the photovoltaic power generation panel of the apparent sun motion trajectory module tracks the movement of the sun's motion trajectory and always remains directly exposed to the sun to receive the maximum radiation energy. The MPPT module communicates with the energy storage module, and the output electric energy is stored in the energy storage module.

[0009] Furthermore, the apparent sun motion trajectory module includes a photovoltaic panel and a spherical detector. The spherical detector is located on the south side of the photovoltaic panel, and the ground is flat and there are no obstructions around it. A plurality of photosensors are arranged on the spherical detector.

[0010] Furthermore, the spherical part of the spherical detector is supported on the ground by a supporting frame, and four layers of photosensitive sensor belts are evenly distributed on the upper hemisphere of the spherical part of the spherical detector. From bottom to top, each layer is distributed with 12, 8, 4, and 1 photosensitive sensors respectively, which are used to detect the movement trajectory of the sun in all directions.

[0011] Furthermore, a spherical protective shell is provided outside the spherical part of the spherical detector, and a concave lens is provided on the protective shell corresponding to each photosensitive sensor for focusing light.

[0012] Furthermore, according to the solar position information provided by the spherical detector, the stepper motors of the photovoltaic panels are adjusted in the horizontal and vertical axes, so that the sunlight always directly hits the photovoltaic panels to obtain the maximum solar radiation energy, and then the maximum power point of solar energy is tracked, so that the photovoltaic panels always work at the maximum power point to maximize energy utilization.

[0013] The tracking method of the solar maximum power point dual-axis tracking system based on the apparent sun motion trajectory of the present invention comprises the following specific steps:

[0014] Step 1: Initialize the system, select the photosensor on the spherical detector facing due east as the initial photosensor, which is the first photosensor to receive sunlight every day. The initial orientation of the photovoltaic panel is the same as that of the initial photosensor;

[0015] Step 2: Pre-start. When the light intensity received by the photosensor on the star detector exceeds its startup threshold, the signal detected by the photosensor is transmitted to the power module, which supplies power to the entire tracking system and the system starts working. When it is extremely cloudy or at night, the photosensor cannot detect the light intensity and the system automatically resets.

[0016] Step 3: The solar motion trajectory module is also connected to a time module, which sets a detection interval Δt, detects the intensity of sunlight every Δt, and adjusts the rotation position of the photovoltaic panel according to the detection result;

[0017] If the original photosensor that receives the highest solar light intensity still receives the strongest light, there is no need to adjust the position of the photovoltaic panel. If the new photosensor receives the highest light intensity, adjust the photosensor to the corresponding position according to steps 4 to 7:

[0018] Step 4: The data processing module collects and preprocesses the information detected by the detector. First, each photosensitive sensor is numbered as [ij], where i and j are two digits respectively, i represents the layer number where the photosensitive sensor is located, the first layer i=0, j represents the number of bits of the photosensitive sensor on a certain layer, and a logical value is attached; wherein the initial photosensitive sensor is numbered as

[0001] , and the numbers increase in a clockwise direction; the logical value is defined as: the photosensitive sensor not directly exposed to the sun has a small light intensity, a large resistance and a large voltage, and is set to "0", the photosensitive sensor directly exposed to the sun has a large light intensity, a small resistance value and a small voltage, and is set to "1", and the position where the photosensitive sensor is not set is occupied by "0", and the logical values ​​of all photosensitive sensor states form a 12×4 matrix, and the position of the direct sunlight point can be determined by reading the position number of "1";

[0019] Step 5: Information processing: Use the data processing module to search for "1" one by one from the first row from left to right in the matrix obtained above, and record the number of digits read when "1" is found, recorded as n, and use formula (1.1) and formula (1.2) to match the "1" indicating the sun's position with the number of the photosensor directly exposed to the sun, and get

[0020]

[0021] j=n-12i(Formula 1.2)

[0022] in The rounding symbol is used. If the result of the calculation is a negative number, the rounding value is 0.

[0023] Step 6: The dual-axis control of the photovoltaic panel uses a three-phase stepper motor with a step angle of 1.5°. The control method is to send pulses to the horizontal axis stepper motor and the vertical axis stepper motor respectively according to the photosensitive sensor number corresponding to the sun's position. The calculation formula for the number of pulses sent is shown in formula (1.3) and formula (1.4):

[0024]

[0025] n 竖直 =20i (Formula 1.4)

[0026] Where n 水平 Represents the number of pulses sent to the horizontal stepper motor, n 竖直 Represents the number of pulses sent to the vertical stepper motor;

[0027] Step 7: The horizontal stepper motor drives the adjustment of the photovoltaic panel in the horizontal direction, and the vertical stepper motor drives the adjustment of the photovoltaic panel in the vertical direction, so as to realize the dual-axis solar tracking of the photovoltaic panel, that is, after the photovoltaic panel is adjusted once, the current position information and step number information are stored, and when the position is adjusted next time, a pulse is sent according to the difference generated by the comparison with the currently stored step number information. After the pulse is sent, the step number difference is zero, and the photovoltaic panel has been adjusted to the position where it is vertically illuminated by the sun again;

[0028] Step 8: Use the hysteresis comparison method to track the maximum power point of the MPPT module; that is, do not track the maximum power point when the light intensity changes rapidly, and track it when the light intensity is stable, so that the output of the solar photovoltaic panel is fixed near the maximum power point to achieve the maximum energy utilization rate;

[0029] Step 9: The energy storage module consists of an inverter and a battery. The inverter converts the direct current generated by the solar photovoltaic panel into alternating current to charge the battery. It is used to store excess electrical energy from the photovoltaic panel so that it can continue to provide power at night or under low radiation conditions.

[0030] Furthermore, the start-up threshold of each photosensor is set to 600 Lux.

[0031] Furthermore, the data processing method of step 5 is as follows:

[0032] Step 5.1: Initialization setting, set the initial value of variable n to n=0;

[0033] Step 5.2: Read the logic values ​​in the matrix one by one, and set n=n+1 each time a logic value is read;

[0034] Step 5.3: If the currently read logical value is 0, repeat step 5.2. If the currently read logical value is 1, use the values ​​of i and j to calculate the number of the photosensor according to (Formula 1.1) and (Formula 1.2), and exit the data processing program.

[0035] Furthermore, the hysteresis comparison method in step 8 is specifically as follows:

[0036] Step 8.1: Collect the current and voltage of the photovoltaic panel, calculate the output power Pb of the photovoltaic panel, thereby determining the working point b on the UI curve of the photovoltaic panel, and set a variable sign = 0;

[0037] Step 8.2: Apply a small disturbance ΔU to the value of the current input signal, collect the voltage after the disturbance, Ua=Ub+ΔU, Uc=Ub-ΔU, and calculate the power at the current points a, b, and c, Pa, Pb, and Pc;

[0038] Step 8.3: If Pb≤Pc, then sign=sign+1, otherwise sign=sign-1; then compare Pa and Pb, if Pa is less than or equal to Pb, then sign=sign+1, otherwise sign=sign-1;

[0039] Step 8.4: Get the sign value of this disturbance. If sign = 2, the output power of point c is the maximum at this time. If sign = 0, the output power of point b is the maximum at this time. If sign = -2, the output power of point a is the maximum at this time. Adjust the angle of the photovoltaic panel so that its working state moves to the point with the maximum power at this time.

[0040] Step 8.5: Repeat the process of sampling, comparing, judging and adjusting until the output power of the photovoltaic panel is stabilized near the maximum power point.

[0041] Furthermore, the hysteresis comparison method is replaced by a disturbance interference method.

[0042] The beneficial effects of the present invention are:

[0043] 1. The present invention combines the two adjustment steps of coarse adjustment and fine adjustment in the prior art into one step, directly locates through the signal sent by the photosensitive sensor, and then controls the photovoltaic panel to rotate to the desired position. The present invention can realize the solar trajectory tracking throughout the year and in all locations only by intuitively reflecting the sun's position through a spherical detector and outputting the information to the drive module. The maximum power point tracking of the present invention uses the hysteresis comparison method to track the maximum power point. Compared with the disturbance interference method, the hysteresis comparison method does not add external disturbances, reduces power consumption, and can make judgments after the external environment is stabilized, reducing the possibility of misjudgment.

[0044] 2. The spherical detector designed by the present invention can locate and collect information about the sun's position all day and all year round. Due to the initialization and pre-start parts, the correct tracking of the sun's position can be guaranteed even in a complex weather environment with alternating sunny and cloudy weather. The principles of the information acquisition module and the drive module of the present invention are relatively simple, and dual-axis drive can be achieved without too many calculation formulas. In the maximum power point tracking part, the MPPT hysteresis comparison method has a clear principle and is easy to operate compared to the traditional perturbation observation method. It is highly tolerant to weather and surrounding environment, can reduce energy loss during tracking, and improve accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a block diagram of the tracking system of the present invention.

[0046] Figure 2 It is a structural schematic diagram of the spherical detector of the present invention.

[0047] Figure 3 It is a sample diagram of a matrix formed by information collection of the present invention.

[0048] Figure 4 It is a flow chart of the information processing part of the present invention.

[0049] Figure 5 It is a flow chart of the hysteresis comparison method of the present invention.

[0050] In the figure: 1. spherical detector, 2. photosensor, 3. protective shell, 4. concave lens, 5. support frame. DETAILED DESCRIPTION

[0051] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0052] Example: Figure 1As shown, the present invention is a dual-axis tracking system for maximum power point of solar energy based on the apparent sun motion trajectory, including an initialization and pre-start module, an apparent sun motion trajectory module, a data processing module, a control module, a drive module, an MPPT module, an energy storage module and a power supply. The initialization and pre-start module is used for initialization and pre-start of the system, and communicates with the apparent sun motion trajectory module. The apparent sun motion trajectory module communicates with the data processing module and the MPPT module respectively. The data processing module, the control module and the drive module communicate in sequence. The control module controls the movement of the drive module according to the information transmitted by the data processing module, so that the photovoltaic power generation panel of the apparent sun motion trajectory module tracks the movement of the sun's motion trajectory and always keeps being directly exposed to the sun to receive the maximum radiation energy. The MPPT module communicates with the energy storage module, and the output electric energy is stored in the energy storage module.

[0053] Furthermore, the apparent sun motion trajectory module includes a photovoltaic panel and a spherical detector 1. The spherical detector 1 is located on the south side of the photovoltaic panel, and the ground is flat and there are no obstructions around it. A plurality of photosensors 2 are arranged on the spherical detector 1.

[0054] Furthermore, if Figure 2 As shown, the spherical part of the spherical detector 1 is supported on the ground by a support frame 5, and four layers of photosensitive sensor belts are evenly distributed on the upper hemisphere of the spherical part of the spherical detector 1. From bottom to top, each layer is distributed with 12, 8, 4, and 1 photosensitive sensors 2, respectively, for all-round detection of the sun's movement trajectory.

[0055] The spherical part of the spherical detector 1 is covered with a spherical protective shell 3 , and the protective shell 3 is provided with concave lenses 4 corresponding to each photosensitive sensor 2 for focusing light.

[0056] The present invention adopts the tracking method of the dual-axis tracking system of the maximum power point of solar energy based on the apparent sun motion trajectory, and adjusts the stepper motors of the horizontal and vertical axes of the photovoltaic panels according to the sun position information provided by the spherical detector, so that the sunlight always directly hits the photovoltaic panels to obtain the maximum solar radiation energy, and then tracks the maximum power point of solar energy, so that the photovoltaic panels always work at the maximum power point to maximize energy utilization.

[0057] The specific steps are:

[0058] Step 1: Initialize the tracking system. Select the photosensor on the spherical detector facing due east as the initial photosensor, which is the first photosensor to receive the sun every day. The initial orientation of the photovoltaic panel is the same as that of the initial photosensor.

[0059] Step 2: Pre-start. When the light intensity received by the photosensor on the star detector exceeds its startup threshold, the signal detected by the photosensor is transmitted to the power module, which supplies power to the entire tracking system and the system starts working. When it is extremely cloudy or at night, the photosensor cannot detect the light intensity and the system automatically resets.

[0060] The light intensity at night is about 0.03-0.3 Lux, and the light intensity at sunrise and sunset is about 300-400 Lux; the light intensity on cloudy days is generally 500 Lux; in the summer when the weather is clear, the light intensity of the sun is the highest, which can reach 60000-100000 Lux, so the start threshold set for each photosensor in the present invention is 600 Lux;

[0061] Step 3: The apparent sun motion trajectory detection module is used to detect the position of the sun, wherein the spherical detector 1 is used to detect the sun's trajectory; since the position of the sun will change significantly once within a period of time, it is a very uneconomical strategy to detect the sun's position in real time. Therefore, the apparent sun motion trajectory module is also connected to a time module, and by setting a detection interval Δt, the sun's light intensity is detected every Δt, and the rotation position of the photovoltaic panel is adjusted according to the detection result;

[0062] If the original photosensor that receives the highest solar light intensity still receives the strongest light, there is no need to adjust the position of the photovoltaic panel. If it is detected that the new photosensor receives the highest light intensity, adjust the photosensor to the corresponding position according to steps 4 to 7 below:

[0063] Step 4: The data processing module collects and preprocesses the information detected by the detector. First, each photosensor is numbered [ij], where i and j are two digits respectively, i represents the layer number of the photosensor, the first layer i=00, j represents the number of the photosensor on a certain layer, such as the 12th photosensor on the first layer is numbered

[0012] , and a logical value is attached; the initial photosensor is numbered

[0001] , and the numbers increase in the clockwise direction; the logical value is defined as: the photosensor that is not directly exposed to the sun has a small light intensity, a large resistance and a large voltage, and is set to "0"; the photosensor that is directly exposed to the sun has a large light intensity, a small resistance and a small voltage, and is set to "1", and the position where the photosensor is not set is occupied by "0", and the logical values ​​of all photosensor states form a 12×4 matrix, as shown in the attached Figure 3 As shown in FIG. 1 , the matrix is ​​obtained by taking the seventh photosensor of the second layer as an example, and the position of the direct sunlight point can be determined by reading the position number of “1”;

[0064] Step 5: Information processing: Use the data processing module to search for "1" one by one from the first row from left to right in the matrix obtained above, and record the number of digits read when "1" is found, recorded as n, and use formula (1.1) and formula (1.2) to match the "1" indicating the sun's position with the number of the photosensor directly exposed to the sun, and get

[0065]

[0066] j=n-12i(Formula 1.2)

[0067] in The rounding symbol is used. If the result of the calculation is a negative number, the rounding value is 0.

[0068] like Figure 4 As shown, the data processing method is as follows:

[0069] Step 5.1: Initialization setting, set the initial value of variable n to n=0;

[0070] Step 5.2: Read the logical values ​​in the matrix one by one, and set n=n+1 each time a logical value is read;

[0071] Step 5.3: If the currently read logical value is 0, repeat step 5.2. If the currently read logical value is 1, use the values ​​of i and j to calculate the number of the photosensor according to (Formula 1.1) and (Formula 1.2), and exit the data processing program.

[0072] Step 6: The dual-axis control of the photovoltaic panel uses a three-phase stepper motor with a step angle of 1.5°. The control method is to send pulses to the horizontal axis stepper motor and the vertical axis stepper motor respectively according to the photosensitive sensor number corresponding to the sun's position. The calculation formula for the number of pulses sent is shown in formula (1.3) and formula (1.4):

[0073]

[0074] n 竖直 =20i (Formula 1.4)

[0075] where n 水平 Represents the number of pulses sent to the horizontal stepper motor, n 竖直 Represents the number of pulses sent to the vertical stepper motor;

[0076] Step 7: The horizontal stepper motor drives the adjustment of the photovoltaic panel in the horizontal direction, and the vertical stepper motor drives the adjustment of the photovoltaic panel in the vertical direction, so as to realize the dual-axis solar tracking of the photovoltaic panel, that is, after the photovoltaic panel is adjusted once, the current position information and step number information are stored, and when the position is adjusted next time, a pulse is sent according to the difference generated by the comparison with the currently stored step number information. After the pulse is sent, the step number difference is zero, and the photovoltaic panel has been adjusted to the position where it is vertically illuminated by the sun again;

[0077] Step 8: Use the hysteresis comparison method to track the maximum power point of the MPPT module; that is, do not track the maximum power point when the light intensity changes rapidly, and track it when the light intensity is stable, so that the output of the solar photovoltaic panel is fixed near the maximum power point to achieve the maximum energy utilization rate;

[0078] like Figure 5 As shown, the hysteresis comparison method is as follows:

[0079] Step 8.1: Collect the current and voltage of the photovoltaic panel, calculate the output power Pb of the photovoltaic panel, thereby determining the working point b on the UI curve of the photovoltaic panel, and set a variable sign = 0;

[0080] Step 8.2: Apply a small disturbance ΔU to the value of the current input signal, collect the voltage after the disturbance, Ua=Ub+ΔU, Uc=Ub-ΔU, and calculate the power at the current points a, b, and c, Pa, Pb, and Pc;

[0081] Step 8.3: If Pb≤Pc, then sign=sign+1, otherwise sign=sign-1; then compare Pa and Pb, if Pa is less than or equal to Pb, then sign=sign+1, otherwise sign=sign-1;

[0082] Step 8.4: Get the sign value of this disturbance. If sign = 2, the output power of point c is the maximum at this time. If sign = 0, the output power of point b is the maximum at this time. If sign = -2, the output power of point a is the maximum at this time. Adjust the angle of the photovoltaic panel so that its working state moves to the point with the maximum power at this time.

[0083] Step 8.5: Repeat the process of sampling, comparing, judging and adjusting until the output power of the photovoltaic panel is stabilized near the maximum power point.

[0084] Step 9: The energy storage module consists of an inverter and a battery. The inverter converts the direct current generated by the solar photovoltaic panel into alternating current to charge the battery. It is used to store excess electrical energy from the photovoltaic panel so that it can continue to provide power at night or under low radiation conditions.

[0085] The hysteresis comparison method described in the present invention is replaced by the disturbance interference method. The disturbance interference method is one of the most common methods of MPPT. The principle is simple and easy to implement, and is often used in large grid-connected photovoltaic arrays. The present invention reduces energy consumption and improves accuracy as much as possible during the tracking process, and the disturbance interference method can also realize the MPPT module function.

[0086] It can be understood that the above specific description of the present invention is only used to illustrate the present invention and is not limited to the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that the present invention can still be modified or replaced by equivalents to achieve the same technical effects; as long as the use requirements are met, they are within the protection scope of the present invention.

Claims

1. A dual-axis solar maximum power point tracking system based on the apparent sun motion trajectory, characterized by: It includes an initialization and pre-start module, a visible sun motion trajectory module, a data processing module, a control module, a drive module, an MPPT module, an energy storage module and a power supply. The initialization and pre-start module is used for the initialization and pre-start of the system and communicates with the visible sun motion trajectory module. The visible sun motion trajectory module communicates with the data processing module and the MPPT module respectively. The data processing module, the control module and the drive module communicate in sequence. The control module controls the movement of the drive module according to the information transmitted by the data processing module, so that the photovoltaic power generation panel of the visible sun motion trajectory module tracks the movement of the sun's motion trajectory and always keeps being directly exposed to the sun to receive the maximum radiation energy. The MPPT module communicates with the energy storage module, and the output electric energy is stored in the energy storage module.

2. The solar maximum power point dual-axis tracking system based on the apparent sun motion trajectory according to claim 1, characterized in that: The apparent sun motion trajectory module includes a photovoltaic panel and a spherical detector. The spherical detector is located on the south side of the photovoltaic panel, and the ground is flat and there are no obstructions around it. A plurality of photosensitive sensors are arranged on the spherical detector.

3. The solar maximum power point dual-axis tracking system based on the apparent sun motion trajectory according to claim 1, characterized in that: The spherical part of the spherical detector is supported on the ground by a supporting frame. Four layers of photosensitive sensor belts are evenly distributed on the upper hemisphere of the spherical part of the spherical detector. From bottom to top, each layer is distributed with 12, 8, 4, and 1 photosensitive sensors respectively, which are used to detect the movement trajectory of the sun in all directions.

4. The solar maximum power point dual-axis tracking system based on the apparent sun motion trajectory according to claim 1, characterized in that: The spherical part of the spherical detector is covered with a spherical protective shell, and concave lenses are respectively arranged on the protective shell corresponding to each photosensitive sensor for focusing light.

5. A tracking method of a solar maximum power point dual-axis tracking system based on the apparent sun motion trajectory as claimed in any one of claims 1 to 4, characterized in that: According to the solar position information provided by the spherical detector, the stepper motors of the photovoltaic panels are adjusted in the horizontal and vertical axes to ensure that sunlight always directly hits the photovoltaic panels to obtain the maximum solar radiation energy. The maximum power point of solar energy is then tracked to ensure that the photovoltaic panels always work at the maximum power point to maximize energy utilization.

6. According to the tracking method of the solar maximum power point dual-axis tracking system based on the apparent sun motion trajectory of claim 5, the specific steps are: Step 1: Initialize the system, select the photosensor on the spherical detector facing due east as the initial photosensor, which is the first photosensor to receive sunlight every day. The initial orientation of the photovoltaic panel is the same as that of the initial photosensor; Step 2: Pre-start. When the light intensity received by the photosensor on the star detector exceeds its startup threshold, the signal detected by the photosensor is transmitted to the power module, which supplies power to the entire tracking system and the system starts working. When it is extremely cloudy or at night, the photosensor cannot detect the light intensity and the system automatically resets. Step 3: The solar motion trajectory module is also connected to a time module, which sets a detection interval Δt, detects the intensity of sunlight every Δt, and adjusts the rotation position of the photovoltaic panel according to the detection result; If the original photosensor that receives the highest solar light intensity still receives the strongest light, there is no need to adjust the position of the photovoltaic panel. If the new photosensor receives the highest light intensity, adjust the photosensor to the corresponding position according to steps 4 to 7: Step 4: The data processing module collects and preprocesses the information detected by the detector. First, each photosensitive sensor is numbered as [ij], where i and j are two digits respectively, i represents the layer number where the photosensitive sensor is located, i=0 for the first layer, j represents the number of bits of the photosensitive sensor on a certain layer, and a logical value is attached; the initial photosensitive sensor is numbered as [0001], and the numbers increase in a clockwise direction; the logical value is defined as: the photosensitive sensor not directly exposed to the sun has a small light intensity, a large resistance and a large voltage, and is set to "0", the photosensitive sensor directly exposed to the sun has a large light intensity, a small resistance value and a small voltage, and is set to "1", and the position where the photosensitive sensor is not set is occupied by "0", and the logical values ​​of all photosensitive sensor states form a 12×4 matrix, and the position of the direct sunlight point can be determined by reading the position number of "1"; Step 5: Information processing: Use the data processing module to search for "1" one by one from the first row from left to right in the matrix obtained above, and record the number of digits read when "1" is found, recorded as n, and use formula (1.1) and formula (1.2) to match the "1" indicating the sun's position with the number of the photosensor directly exposed to the sun, and get j=n-12i (Formula 1.2) in The rounding symbol is used. If the result of the calculation is a negative number, the rounding value is 0. Step 6: The dual-axis control of the photovoltaic panel uses a three-phase stepper motor with a step angle of 1.5°. The control method is to send pulses to the horizontal axis stepper motor and the vertical axis stepper motor respectively according to the photosensitive sensor number corresponding to the sun's position. The calculation formula for the number of pulses sent is shown in formula (1.3) and formula (1.4): n 竖直 =20i (Formula 1.4) Where n 水平 Represents the number of pulses sent to the horizontal stepper motor, n 竖直 Represents the number of pulses sent to the vertical stepper motor; Step 7: The horizontal stepper motor drives the adjustment of the photovoltaic panel in the horizontal direction, and the vertical stepper motor drives the adjustment of the photovoltaic panel in the vertical direction, so as to realize the dual-axis solar tracking of the photovoltaic panel, that is, after the photovoltaic panel is adjusted once, the current position information and step number information are stored, and when the position is adjusted next time, a pulse is sent according to the difference generated by the comparison with the currently stored step number information. After the pulse is sent, the step number difference is zero, and the photovoltaic panel has been adjusted to the position where it is vertically illuminated by the sun again; Step 8: Use the hysteresis comparison method to track the maximum power point of the MPPT module; that is, do not track the maximum power point when the light intensity changes rapidly, and track it when the light intensity is stable, so that the output of the solar photovoltaic panel is fixed near the maximum power point to achieve the maximum energy utilization rate; Step 9: The energy storage module consists of an inverter and a battery. The inverter converts the direct current generated by the solar photovoltaic panel into alternating current to charge the battery. It is used to store excess electrical energy from the photovoltaic panel so that it can continue to provide power at night or under low radiation conditions.

7. The dual-axis tracking method of solar maximum power point based on apparent solar motion trajectory according to claim 1, characterized in that: The start threshold of each photosensitive sensor is set to 600 Lux.

8. The dual-axis tracking method for solar maximum power point based on apparent solar motion trajectory according to claim 1, characterized in that: The data processing method of step 5 is as follows: Step 5.1: Initialization setting, set the initial value of variable n to n=0; Step 5.2: Read the logic values ​​in the matrix one by one, and set n=n+1 each time a logic value is read; Step 5.3: If the currently read logical value is 0, repeat step 5.

2. If the currently read logical value is 1, use the values ​​of i and j to calculate the number of the photosensor according to (Formula 1.1) and (Formula 1.2), and exit the data processing program.

9. The dual-axis tracking method for solar maximum power point based on apparent solar motion trajectory according to claim 1, characterized in that: The hysteresis comparison method in step 8 is specifically as follows: Step 8.1: Collect the current and voltage of the photovoltaic panel, calculate the output power Pb of the photovoltaic panel, thereby determining the working point b on the UI curve of the photovoltaic panel, and set a variable sign = 0; Step 8.2: Apply a small disturbance ΔU to the value of the current input signal, collect the voltage after the disturbance, Ua=Ub+ΔU, Uc=Ub-ΔU, and calculate the power at the current points a, b, and c, Pa, Pb, and Pc; Step 8.3: If Pb≤Pc, then sign=sign+1, otherwise sign=sign-1; then compare Pa and Pb, if Pa is less than or equal to Pb, then sign=sign+1, otherwise sign=sign-1; Step 8.4: Get the sign value of this disturbance. If sign = 2, the output power of point c is the maximum at this time. If sign = 0, the output power of point b is the maximum at this time. If sign = -2, the output power of point a is the maximum at this time. Adjust the angle of the photovoltaic panel so that its working state moves to the point with the maximum power at this time. Step 8.5: Repeat the process of sampling, comparing, judging and adjusting until the output power of the photovoltaic panel is stabilized near the maximum power point.

10. The dual-axis tracking method of solar maximum power point based on apparent solar motion trajectory according to claim 1, characterized in that: The hysteresis comparison method is replaced by a disturbance interference method.

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