Concentrating device and photovoltaic system

Abstract

The invention relates to the technical field of photovoltaic equipment, and discloses a light gathering device and a photovoltaic system.The light gathering device comprises a bottom plate, a supporting frame is fixedly connected to the bottom plate, a transverse frame is fixedly connected to the middle of the supporting frame, a driving shell is fixedly connected to the middle of the transverse frame, and a driving motor is fixedly connected into the driving shell; a disc is fixedly connected to the shaft end of the driving motor, an inserting hole is formed in the position, deviating from the axis, of the disc in a penetrating mode, and a vertical rod is movably inserted into the inserting hole. Through the overall design, the instant perceptibility of angle adjustment can be effectively improved, in the operation process, a user can grasp the angle change situation in real time and clearly know the current adjustment progress and the current angle position through cooperation of the scale marks of the vertical rod and the disc without depending on external auxiliary tools or past experience, and the operation efficiency is improved. Blind operation in the adjusting process is avoided, clear visual reference is provided for each step of adjustment, and adjusting deviation caused by untimely perception is reduced.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic equipment technology, specifically to a concentrating device and a photovoltaic system. Background Technology

[0002] In the field of solar photovoltaic power generation, solar panels and photovoltaic modules serve as the core power generation unit, and their working principle is based on the photovoltaic effect. When sunlight shines on solar cells made of semiconductor materials (such as monocrystalline silicon and polycrystalline silicon), photons with sufficient energy excite electrons to transition, generating electron-hole pairs. Under the influence of the built-in electric field formed by the PN junction within the cell, electrons and holes separate and move in different directions, thereby forming a current in the external circuit, realizing the direct conversion of solar energy into electrical energy. To ensure that the solar panel receives optimal sunlight and can absorb solar energy and convert it into electrical energy to the maximum extent, its irradiation angle needs to be precisely adjusted. Currently, the common angle adjustment methods are mainly manual and electronic control.

[0003] In small-scale applications, such as residential rooftop photovoltaic power generation systems and solar power supply for small commercial facilities, manual adjustment is more common due to the high cost of electronic control methods. This involves expensive motors, controllers, sensors, and complex wiring and maintenance costs. However, manual adjustment has significant limitations. Operators lack an intuitive and precise angle feedback mechanism when adjusting the tilt angle of solar panels, making it difficult to ensure that each panel is adjusted to the ideal angle. This leads to easy angle deviations between adjacent panels. The aforementioned angle deviations can cause a series of serious problems. In terms of sunlight, solar panels with a higher angle will cast shadows on the surfaces of adjacent solar panels with a lower angle; even if only a small area is shaded, the power generation of the solar panel will drop significantly because the shaded area will limit the current output of the entire series branch, resulting in significant light and shadow losses, which seriously affect the overall power generation efficiency. Regarding wind resistance, when the angle of a solar panel deviates, its "shape factor" changes abruptly, causing the wind load it bears to differ significantly from other solar panels in the same row. At this point, the airflow around the solar panel becomes turbulent, disrupting the original uniform force balance of the entire row. Under strong winds, this uneven force often triggers resonance in the entire solar panel array. When the resonance amplitude increases beyond the support structure's capacity, it can even lead to the dangerous situation of the entire row of solar panels overturning, causing devastating damage to the solar power generation facility and resulting in huge economic losses. Furthermore, while auxiliary devices using electronic control offer advantages in automation and adjustment precision, they also exhibit significant drawbacks in windy conditions. The control motor directly connected to the solar panel is prone to loosening of its shaft during frequent panel movement. This loosening not only causes issues like eccentricity and jamming during motor operation, affecting the accuracy and stability of angle adjustment, but also accelerates wear on internal components, significantly shortening the motor's lifespan. Frequent motor replacements not only increase maintenance costs but can also lead to prolonged periods of inoperability for the solar power system, further reducing power generation revenue.

[0004] In summary, existing methods for adjusting the angle of solar panels, whether manual or electronic, have significant shortcomings, severely impacting the power generation efficiency, stability, and safety of solar power systems. Therefore, developing a concentrator and photovoltaic system capable of precisely adjusting the tilt angle of solar panels, effectively avoiding angle deviations, significantly improving wind resistance, and simultaneously addressing the issue of easily damaged electronically controlled motors in high winds has become a critical technical challenge urgently needing to be solved in the current solar photovoltaic power generation field.

[0005] Therefore, we propose a concentrating device and photovoltaic system to solve the above problems. Summary of the Invention

[0006] To achieve the above objectives, the present invention provides a focusing device, comprising a base plate, a support frame fixedly connected to the base plate, a crossbar fixedly connected to the middle of the support frame, a drive housing fixedly connected to the middle of the crossbar, a drive motor fixedly connected inside the drive housing; a disc fixedly connected to the shaft end of the drive motor, an insertion hole being provided through the disc at an off-center position, a vertical rod being movably inserted into the insertion hole, and graduation lines being provided equidistantly on the vertical rod.

[0007] Preferably, a sleeve is fixedly connected to the top of the vertical rod, a transmission rod is slidably connected inside the sleeve, and swing plates are fixedly connected to both ends of the transmission rod.

[0008] Preferably, the upper part of the support frame has symmetrical holes, and a rotating rod is rotatably connected inside the holes of the support frame. The bottom of the swing plate is fixedly connected to the rotating rod.

[0009] Preferably, the end face of the rotating rod located on the side wall of the base plate has a mounting groove, and a solar panel is provided between the two mounting grooves.

[0010] Preferably, the wall of the mounting groove fits against the edge of the solar panel, and the mounting groove and the solar panel are connected by a snap-fit ​​method.

[0011] Preferably, the insertion hole is slidably adapted to the vertical rod, and the scale line is used in conjunction with the upper surface of the disk, so that the reading is performed when both are flush.

[0012] Preferably, the transmission rod is slidably adapted to the sleeve.

[0013] The present invention also provides a photovoltaic system, including a photovoltaic module array for converting solar energy into direct current, wherein the photovoltaic module array includes solar panels; A string inverter, whose input terminal is connected to the photovoltaic module array, is used to invert DC power into AC power; a box-type transformer, whose input terminal is connected to the output terminal of the string inverter, is used to initially boost the AC power. The main transformer, whose input terminal is connected to the output terminal of the box-type transformer, is used to further boost the AC power after the initial voltage boost to the grid connection voltage. A reactive power compensation device is connected to the power transmission line between the box-type transformer and the main transformer; The auxiliary support system includes a DC power supply device and an uninterruptible power supply device. The DC power supply device is connected to the system control load, and the uninterruptible power supply device is connected to the system's key monitoring load. The control and protection system includes a power control module, a fault recording module, and a relay protection module. The power control module is communicatively connected to the string inverter and the main transformer, respectively. The fault recording module and the relay protection module are electrically connected to the box-type transformer, the main transformer, and the transmission lines connected to the external power grid.

[0014] Preferably, the power control module includes an active power control module and a reactive power control module; The active power control module can receive external dispatch instructions and adjust the output power of the string inverter so that the deviation between the total active power of the system and the dispatch instructions does not exceed a preset value. The reactive power control module can control the reactive power compensation device to output or absorb reactive power in accordance with changes in grid voltage, thereby stabilizing the voltage of the transmission line between the box-type transformer and the main transformer.

[0015] Preferably, the relay protection module includes a main transformer protection unit, a line protection unit, and an inverter protection unit; The main transformer protection unit is used to monitor the current, voltage and temperature of the main transformer, and triggers protection action when overcurrent, overvoltage or overtemperature occurs; The line protection unit is used to monitor the current and voltage of the transmission lines between the box-type transformer and the main transformer, and between the main transformer and the external power grid. When a short circuit or open circuit occurs, the protection action is triggered. The inverter protection unit is used to monitor the input voltage and output current of the string inverter. When overcurrent, overvoltage or grid abnormality occurs, it controls the string inverter to disconnect from the grid.

[0016] (III) Beneficial Effects Compared with the prior art, the present invention provides a concentrating device and a photovoltaic system, which have the following beneficial effects: 1. Through its overall design, this invention offers the following advantages to the overall operation: The system enhances the real-time perception of angle adjustment. During operation, users do not need to rely on external auxiliary tools or past experience. Through the cooperation of the scale lines on the vertical rod and the disc, they can keep track of the angle changes in real time, clearly know the current adjustment progress and the current angle position, avoid blind operation during the adjustment process, and make each adjustment have a clear visual reference, reducing adjustment deviations caused by untimely perception. Enhanced stability after angle locking: When the device is adjusted to the target angle, the cooperation between the scale line and the disc helps confirm the final angle lock state. Unlike devices without feedback, where adjacent solar panels may shift during angle adjustment and the operator cannot detect it in time, causing differences in wind load between the solar panels and other solar panels in the same row, the force balance is completely broken, leading to resonance of the entire solar panel group and even overturning. This ensures that the device maintains stable performance in windy environments over a long period of time.

[0017] 2. The present invention, through its multi-sliding connection design between components, brings the following advantages to the overall operation: Extending the lifespan of the drive motor and reducing wear on core components: Achieving "buffered transmission" of wind force. When the solar panel is impacted by wind, the force is not directly applied to the drive motor, but is transmitted layer by layer through components such as rotating rods, transmission rods, oscillating plates, vertical rods, and discs. During the transmission process, each component can disperse and dissipate part of the impact force through its own structural characteristics, avoiding a single component or drive motor from directly bearing concentrated loads. This significantly reduces the stress on the drive motor, reduces wear on key components such as gears and bearings inside the motor, fundamentally slows down the aging rate of the motor, and effectively extends its service life. To avoid the risk of losses associated with "direct connection," compared to designs where the solar panel is directly connected to the drive motor, where wind impact directly translates into a rigid force on the motor, potentially leading to motor overload, component deformation, or even shutdown, the multi-component layered transmission design uses "step-by-step force relief" to control the force acting on the drive motor within a safe range. This reduces the frequency of maintenance and replacement costs caused by excessive force on the motor, ensuring the long-term stable operation of the device's core drive components.

[0018] To improve the stability of the device against wind impact and reduce overall structural damage: Enhance the "balance" of force transmission. The multi-component connection method can transform the wind impact on the solar panel into a dispersed force along the rotating rod, transmission rod and other components, avoiding structural deformation caused by localized stress concentration. For example, the swing plate can buffer the lateral wind force through small swings, and the cooperation between the vertical rod and the disc can further adjust the direction of force transmission, making the entire device more uniformly stressed under wind, reducing problems such as component breakage and loosening of connections caused by excessive local stress, and improving the overall wind-resistant structural stability of the device.

[0019] 3. This invention provides comprehensive protection for the stable and safe operation of photovoltaic systems: The DC power supply device in the auxiliary protection system adopts a valve-regulated sealed lead-acid battery pack, which operates in float charging mode to provide continuous DC power to control loads such as control and protection systems and high-voltage switchgear, ensuring that the control loop can still work normally even when the power grid is abnormal; the uninterruptible power supply device provides uninterrupted AC power to key monitoring loads such as monitoring servers and communication equipment, avoiding monitoring and communication interruptions caused by mains power outages, and ensuring real-time monitoring and data transmission of system operating status.

[0020] The power control module in the control and protection system can receive external dispatch commands and precisely adjust the output power of the string inverter and the reactive power output of the reactive power compensation device to ensure that the total active power of the system meets the dispatch requirements, while stabilizing the transmission line voltage and improving the system power factor. The fault recording module can record fault electrical quantity data in real time to support fault analysis and location. The relay protection module can quickly detect the fault status of the main transformer, transmission line, and string inverter, trigger protection actions in a timely manner, cut off the fault circuit, and prevent the fault from escalating.

[0021] Furthermore, the concentrator ensures that the solar panels are angled uniformly, avoiding uneven wind loads caused by angular deviations, preventing the risk of resonance or overturning of the entire row of solar panels, and ensuring the structural safety of the system. These design features work together to not only improve the operational stability and safety of the photovoltaic system itself, but also ensure good compatibility between the system and the external power grid, providing a reliable guarantee for the smooth grid connection of electricity. Attached Figure Description

[0022] Figure 1 This is a three-dimensional schematic diagram of the main structure of the present invention; Figure 2 This is a side view of the main structure of the present invention; Figure 3 This is a diagram showing the working state of the main structure of the present invention; Figure 4 For the present invention Figure 3 Enlarged view of the structure at point A in the middle; Figure 5This is another perspective view of the main structure in operation in this invention; Figure 6 This is a flowchart of the energy conversion and boosting process of the photovoltaic system in this invention; Figure 7 This is a flowchart of the photovoltaic system grid connection, power transmission, and auxiliary support process in this invention; Figure 8 This is a flowchart of the photovoltaic system control and protection system in this invention.

[0023] In the picture: 1. Base plate; 2. Support frame; 3. Horizontal frame; 4. Drive housing; 5. Drive motor; 6. Disc; 7. Insertion hole; 8. Vertical rod; 9. Scale line; 10. Sleeve; 11. Transmission rod; 12. Swing plate; 13. Rotating rod; 14. Mounting slot; 15. Solar panel; 16. Photovoltaic module array; 17. String inverter; 18. Box-type transformer; 19. Main transformer; 20. Reactive power compensation device; 21. DC power supply device; 22. Uninterruptible power supply device; 23. Power control module; 231. Active power control module; 232. Reactive power control module; 24. Fault recording module; 25. Relay protection module; 251. Main transformer protection unit; 252. Line protection unit; 253. Inverter protection unit. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0026] Example 1 Please refer to Figures 1 to 5 As shown: A solar concentrator includes a base plate 1, a support frame 2 fixedly connected to the base plate 1, a crossbar 3 fixedly connected to the middle of the support frame 2, a drive housing 4 fixedly connected to the middle of the crossbar 3, a drive motor 5 fixedly connected inside the drive housing 4, a disc 6 fixedly connected to the shaft end of the drive motor 5, an insertion hole 7 through the disc 6 at its off-center, a vertical rod 8 movably inserted into the insertion hole 7, graduation lines 9 evenly spaced on the vertical rod 8, a sleeve 10 fixedly connected to the top of the vertical rod 8, a transmission rod 11 slidably connected inside the sleeve 10, swing plates 12 fixedly connected to both ends of the transmission rod 11, symmetrical holes opened on the upper part of the support frame 2, a rotating rod 13 rotatably connected inside the holes of the support frame 2, the bottom of the swing plate 12 fixedly connected to the rotating rod 13, an installation groove 14 opened on the end face of the rotating rod 13 located on the side wall of the base plate 1, and a solar panel 15 is fitted into the two installation grooves 14.

[0027] in: The insertion hole 7 is slidably adapted to the vertical rod 8.

[0028] The scale line 9 can be matched with the upper surface of the disc 6 to assist the operator in judging the angle; unlike the existing technology that is manually cranked and lacks angle feedback equipment.

[0029] The transmission rod 11 is slidably fitted to the sleeve 10.

[0030] The mounting slot 14 can be used to attach and install the solar panel 15.

[0031] Working principle: During use, the angle adjustment operator of the solar panel 15 starts the drive motor 5 inside the drive housing 4 via the main controller of the device. The rotating drive motor 5 drives the disc 6 to rotate. As the disc 6 rotates, it forces the vertical rod 8 to move along with the sleeve 10 under the action of the insertion hole 7. (See attached diagram.) Figure 4 and appendix Figure 5 When the assembly consisting of the insertion hole 7 and the sleeve 10 rotates around the axis of the disk 6, the sleeve 10 will swing along the swing plate 12 via the sliding transmission rod 11 inside it; since the swing plate 12 and the rotating rod 13 are fixedly connected, the rotating rod 13 will also swing along with the swing plate 12. Thus, the solar panel 15 in the mounting slot 14 will shift in angle during the swing of the rotating rod 13. Furthermore, during the aforementioned process, the vertical rod 8 moves vertically through the insertion hole 7 on the disc 6. Since the vertical rod 8 is known to have a scale line 9, and the scale line 9 is designed to work in conjunction with the upper surface of the disc 6, with the reading taken when both are flush, the operator can determine the adjustment angle by observing the flush position of the scale line 9 with the upper surface of the disc 6 during the aforementioned solar panel 15 angle adjustment process. This ensures the accuracy of the solar panel 15 angle adjustment, reduces light and shadow loss, and improves the force balance of the entire row of solar panels 15 under wind action, ensuring its wind resistance performance.

[0032] Please refer to the above work process. Figures 1 to 5 .

[0033] Example 2 See Figures 6-8 As shown, the present invention also provides a photovoltaic system applied to the concentrating device in Embodiment 1, including a photovoltaic module array 16 for converting solar energy into direct current, wherein the photovoltaic module array 16 includes solar panels 15; A string inverter 17, whose input terminal is connected to the photovoltaic module array 16, is used to invert DC power into AC power. The input terminal of the box-type transformer 18 is connected to the output terminal of the string inverter 17, and is used to initially boost the AC voltage. The main transformer 19 has its input terminal connected to the output terminal of the box-type transformer 18, and is used to further boost the AC power after the initial voltage boost to the grid access voltage. The reactive power compensation device 20 is connected to the power transmission line between the box-type transformer 18 and the main transformer 19. The auxiliary support system includes a DC power supply device 21 and an uninterruptible power supply device 22. The DC power supply device 21 is connected to the system control load, and the uninterruptible power supply device 22 is connected to the system key monitoring load. The control and protection system includes a power control module 23, a fault recording module 24, and a relay protection module 25. The power control module 23 is communicatively connected to the string inverter 17 and the main transformer 19, respectively. The fault recording module 24 and the relay protection module 25 are electrically connected to the box-type transformer 18, the main transformer 19, and the transmission lines connected to the external power grid.

[0034] Preferably, the power control module 23 includes an active power control module 231 and a reactive power control module 232; the active power control module 231 can receive external dispatch instructions and adjust the output power of the string inverter 17 so that the deviation between the total active power of the system and the dispatch instructions does not exceed a preset value; the reactive power control module 232 can control the reactive power compensation device 20 to output or absorb reactive power in combination with the grid voltage changes, and stabilize the voltage of the transmission line between the box transformer 18 and the main transformer 19.

[0035] Preferably, the relay protection module 25 includes a main transformer protection unit 251, a line protection unit 252, and an inverter protection unit 253. The main transformer protection unit 251 is used to monitor the current, voltage, and temperature of the main transformer 19, and triggers protection action when overcurrent, overvoltage, or overtemperature occurs. The line protection unit 252 is used to monitor the current and voltage of the transmission lines between the box-type transformer 18 and the main transformer 19, and between the main transformer 19 and the external power grid, and triggers protection action when short circuit or open circuit occurs. The inverter protection unit 253 is used to monitor the input voltage and output current of the string inverter 17, and controls the string inverter 17 to disconnect from the power grid when overcurrent, overvoltage, or power grid abnormality occurs.

[0036] The main workflow of this photovoltaic system is as follows: During the power generation and grid connection phase of the photovoltaic system, solar panels 15, adjusted to the optimal angle, receive solar energy and convert it into direct current (DC) through the photovoltaic effect. A photovoltaic array 16, composed of several solar panels 15, collects the DC power and transmits it to a string inverter 17 via a DC cable. Under the control of the power control module 23, the string inverter 17 tracks the maximum output power of the photovoltaic array 16 in real time and simultaneously inverts the DC power into low-voltage AC power that meets the grid frequency of 50Hz and voltage requirements. This low-voltage AC power is then transmitted to a box-type transformer 18 via an AC cable.

[0037] After receiving low-voltage AC power, the box-type transformer 18 initially steps it up to medium-voltage AC power, such as 35kV, to reduce energy loss during long-distance transmission. The medium-voltage AC power is then transmitted to the main transformer 19 via a high-voltage cable. The main transformer 19 further steps up the medium-voltage AC power to high-voltage AC power, such as 220kV, which meets the requirements for external power grid connection. Subsequently, the high-voltage AC power is connected to the external power grid through a high-voltage transmission line, enabling the sale of electricity to the grid.

[0038] Throughout the entire power generation and grid connection process, the auxiliary support system and the control and protection system continue to play their roles: the DC power supply device 21 in the auxiliary support system provides a stable DC power supply for the control and protection system, high-voltage switchgear and other control loads to ensure the continuous operation of the control loop; the uninterruptible power supply device 22 provides uninterrupted AC power supply for key monitoring loads such as the monitoring SCADA server and remote communication cabinet to avoid monitoring and communication interruptions caused by mains power outages. The reactive power control module 232 in the control and protection system monitors the voltage of the transmission line between the box-type transformer 18 and the main transformer 19 in real time, controls the reactive power compensation device 20 to output or absorb reactive power, and stabilizes the line voltage. The fault recording module 24 collects electrical quantities such as current and voltage of the transmission line and the main transformer 19 in real time. When the system experiences faults such as current exceeding the limit or voltage abnormality, it automatically records the electrical quantity waveforms at the time of the fault, providing data support for fault analysis. The main transformer protection unit 251 in the relay protection module 25 monitors the current, voltage and temperature of the main transformer 19, the line protection unit 252 monitors the current and voltage of the transmission line, and the inverter protection unit 253 monitors the input voltage and output current of the string inverter 17. When faults such as overcurrent, overvoltage, and short circuit are detected, the protection action is immediately triggered to cut off the fault circuit, prevent the fault from expanding, and ensure the safety of the system equipment.

[0039] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0040] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A light-concentrating device, comprising a base plate (1), characterized in that: A support frame (2) is fixedly connected to the base plate (1), a cross frame (3) is fixedly connected to the middle of the support frame (2), a drive housing (4) is fixedly connected to the middle of the cross frame (3), and a drive motor (5) is fixedly connected inside the drive housing (4). A disc (6) is fixedly connected to the shaft end of the drive motor (5). A through hole (7) is provided on the disc (6) off-center. A vertical rod (8) is movably inserted into the through hole (7). Scale lines (9) are provided on the vertical rod (8) at equal intervals.

2. A concentrating device according to claim 1, characterized in that: A sleeve (10) is fixedly connected to the top of the vertical rod (8), and a transmission rod (11) is slidably connected inside the sleeve (10). A swing plate (12) is fixedly connected to both ends of the transmission rod (11).

3. A concentrating device according to claim 2, characterized in that: The support frame (2) has symmetrical holes on its upper part. A rotating rod (13) is rotatably connected inside the holes of the support frame (2). The bottom of the swing plate (12) is fixedly connected to the rotating rod (13).

4. A concentrating device according to claim 3, characterized in that: The rotating rod (13) has a mounting groove (14) on its end face at the side wall of the base plate (1), and a solar panel (15) is provided between the two mounting grooves (14).

5. A concentrating device according to claim 4, characterized in that: The wall of the mounting groove (14) is in contact with the edge of the solar panel (15), and the mounting groove (14) and the solar panel (15) are connected by a snap-fit ​​method.

6. A concentrating device according to claim 5, characterized in that: The insertion hole (7) is slidably adapted to the vertical rod (8), and the scale line (9) is used in conjunction with the upper surface of the disk (6) to take readings when both are flush.

7. A concentrating device according to claim 6, characterized in that: The transmission rod (11) is slidably adapted to the sleeve (10).

8. A photovoltaic system applied to a concentrating device according to any one of claims 1-7, characterized in that: It includes a photovoltaic module array (16) for converting solar energy into direct current, the photovoltaic module array (16) including solar panels (15); A string inverter (17) is connected to the photovoltaic module array (16) at its input end and is used to invert DC power into AC power. A box-type transformer (18) is connected at its input end to the output end of the string inverter (17) for initial voltage boosting of AC power. The main transformer (19) has its input end connected to the output end of the box-type transformer (18) and is used to further boost the AC power after the initial boost to the grid access voltage. The reactive power compensation device (20) is connected to the transmission line between the box-type transformer (18) and the main transformer (19); The auxiliary support system includes a DC power supply device (21) and an uninterruptible power supply device (22), wherein the DC power supply device (21) is connected to the system control load, and the uninterruptible power supply device (22) is connected to the system key monitoring load; The control and protection system includes a power control module (23), a fault recording module (24), and a relay protection module (25). The power control module (23) is communicatively connected to the string inverter (17) and the main transformer (19), respectively. The fault recording module (24) and the relay protection module (25) are electrically connected to the box transformer (18), the main transformer (19), and the transmission line connected to the external power grid.

9. A photovoltaic system according to claim 8, characterized in that: The power control module (23) includes an active power control module (231) and a reactive power control module (232). The active power control module (231) can receive external dispatch instructions and adjust the output power of the string inverter (17) so that the deviation between the total active power of the system and the dispatch instructions does not exceed a preset value. The reactive power control module (232) can control the reactive power compensation device (20) to output or absorb reactive power in combination with the grid voltage change, thereby stabilizing the voltage of the transmission line between the box transformer (18) and the main transformer (19).

10. A photovoltaic system according to claim 9, characterized in that: The relay protection module (25) includes a main transformer protection unit (251), a line protection unit (252), and an inverter protection unit (253). The main transformer protection unit (251) is used to monitor the current, voltage and temperature of the main transformer (19), and triggers protection action when overcurrent, overvoltage or overtemperature occurs; the line protection unit (252) is used to monitor the current and voltage of the transmission lines between the box-type transformer (18) and the main transformer (19) and between the main transformer (19) and the external power grid, and triggers protection action when short circuit or open circuit occurs. The inverter protection unit (253) is used to monitor the input voltage and output current of the string inverter (17). When overcurrent, overvoltage or grid abnormality occurs, it controls the string inverter (17) to disconnect from the grid.

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