Power supply system based on automatic switching

Abstract

The utility model provides an automatic switching-based power supply system, which comprises a mains supply system, a photovoltaic system and an automatic switching device, and is characterized in that the photovoltaic system comprises a plurality of photovoltaic power generation modules, and the automatic switching device comprises a plurality of first switch units and a first control unit; wherein the power supply end of the mains supply system is connected with the power supply end of the load; the power supply ends of the plurality of first switch units are respectively connected with the power supply ends of the plurality of photovoltaic power generation modules, and the power supply ends of the plurality of first switch units are connected with the power supply end of the load after being connected in parallel; a plurality of output ends of the first control unit are respectively connected with input ends of the plurality of first switch units, and the first control unit is used for controlling the on-off of the plurality of first switch units, so that the current of the power supply end of the photovoltaic system is matched with the current of the power supply end of the load. According to the power supply system based on automatic switching disclosed by the invention, the problem that the photovoltaic system supplies power to the commercial power system and the waste of electric energy generated by the photovoltaic system is avoided.

Description

Technical Field

[0001] The present disclosure relates to the technical field of power supply, and in particular to a power supply system based on automatic switching. Background Art

[0002] While using distributed photovoltaic systems to reduce municipal power consumption, to ensure the quality of municipal power supply is maintained, power supply authorities typically require that the electricity generated by distributed photovoltaic systems be used solely for their own consumption, with no surplus power allowed to be fed to the grid. However, current photovoltaic system power generation is difficult to control, making it very easy for the system to generate more power than the actual load consumption. Furthermore, backflow prevention devices and other equipment used in these systems can directly cut off the system's power supply when the system generates surplus power, resulting in the load's electricity consumption being solely covered by the municipal power supply, while the energy generated by the photovoltaic system is wasted. This practice significantly increases the load's electricity costs, making it difficult to meet low-cost operational requirements. Summary of the Invention

[0003] The present disclosure aims to solve one of the technical problems in the related art at least to a certain extent.

[0004] To this end, the purpose of the present disclosure is to provide a power supply system based on automatic switching.

[0005] To achieve the above-mentioned purpose, the present disclosure provides a power supply system based on automatic switching, including: a mains power system, a photovoltaic system and an automatic switching device, the photovoltaic system including: multiple photovoltaic power generation modules, the automatic switching device including: multiple first switch units and a first control unit; wherein, the power supply end of the mains power system is connected to the power supply end of the load; the power supply ends of multiple first switch units are respectively connected to the power supply ends of multiple photovoltaic power generation modules, and the power supply ends of multiple first switch units are connected in parallel to the power supply end of the load; multiple output ends of the first control unit are respectively connected to the input ends of multiple first switch units, and the first control unit is used to control the on and off of multiple first switch units so that the current at the power supply end of the photovoltaic system matches the current at the power supply end of the load.

[0006] Optionally, the automatic switching device further includes: a first current detection unit, wherein a detection end of the first current detection unit is arranged at the power supply end of the load, and an output end of the first current detection unit is connected to an input end of the first control unit.

[0007] Optionally, the automatic switching device further includes: a second current detection unit, wherein the detection end of the second current detection unit is arranged at the parallel end of the plurality of first switch units, and the output end of the second current detection unit is connected to the input end of the first control unit.

[0008] Optionally, the photovoltaic system also includes: multiple inverter modules, which are connected in series between the power supply end of the first switch unit and the power supply end of the photovoltaic power generation module, and the power supply ends of multiple inverter modules are respectively connected to the power supply ends of multiple photovoltaic power generation modules, and the power supply ends of multiple inverter modules are respectively connected to the power supply ends of multiple first switch units.

[0009] Optionally, the power supply system also includes: a transformer, which is connected in series between the power supply end of the AC power system and the power supply end of the load, and the power supply end of the transformer is connected to the power supply end of the AC power system, and the power supply end of the transformer is connected to the power supply end of the load.

[0010] Optionally, the power supply end of the first control unit is connected to the power supply end of the mains power system.

[0011] Optionally, the power supply system also includes: a backflow prevention device, which includes: a second switch unit and a second control unit; wherein, the second switch unit is connected in series between the parallel ends of multiple first switch units and the power supply end of the load, and the power supply end of the second switch unit is connected to the parallel ends of multiple first switch units, and the power supply end of the second switch unit is connected to the power supply end of the load; the output end of the second control unit is connected to the input end of the second switch unit, and the second control unit is used to control the second switch unit to disconnect when the photovoltaic system supplies power to the mains system.

[0012] Optionally, the backflow prevention device further includes: a third current detection unit, the detection end of the third current detection unit is arranged at the power supply end of the load, and the output end of the third current detection unit is connected to the input end of the second control unit.

[0013] Optionally, the backflow prevention device further includes: a fourth current detection unit, the detection end of the fourth current detection unit is arranged at the parallel end of the plurality of first switch units, and the output end of the fourth current detection unit is connected to the input end of the second control unit.

[0014] Optionally, the power supply end of the second control unit is connected to the power supply end of the mains power system.

[0015] The technical solution provided by the present disclosure may have the following beneficial effects:

[0016] Since the multiple output ends of the first control unit are respectively connected to the input ends of the multiple first switch units, the first control unit can independently control the on and off of each first switch unit, thereby controlling the number of photovoltaic power generation modules participating in the load power supply, and then achieving the matching of the current at the power supply end of the photovoltaic system and the current at the load power supply end. As a result, the problem of "surplus power being connected to the grid" when the photovoltaic system supplies power to the mains system is avoided, and a higher power quality of the mains system is ensured. At the same time, this method will not directly cut off the power supply of the photovoltaic system, avoiding the waste of power generated by the photovoltaic system, thereby ensuring a lower electricity cost for the load and meeting the low-cost operation requirements.

[0017] Additional aspects and advantages of the present disclosure will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and / or additional aspects and advantages of the present disclosure will become apparent and readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0019] Figure 1 This is a circuit diagram of a power supply system based on automatic switching proposed in one embodiment of the present disclosure;

[0020] Figure 2 This is a circuit diagram of a backflow prevention device in a power supply system based on automatic switching proposed in one embodiment of the present disclosure;

[0021] As shown in the figure: 1. Mains power system;

[0022] 2. Photovoltaic system, 21. Photovoltaic power generation module, 22. Inverter module;

[0023] 3. Automatic switching device, 31. First switch unit, 32. First control unit, 33. First current detection unit, 34. Second current detection unit;

[0024] 4. Transformer;

[0025] 5. Backflow prevention device, 51. Second switch unit, 52. Second control unit, 53. Third current detection unit, 54. Fourth current detection unit;

[0026] 6. Load. DETAILED DESCRIPTION

[0027] The following describes in detail embodiments of the present disclosure, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present disclosure and are not to be construed as limiting the present disclosure. On the contrary, the embodiments of the present disclosure include all variations, modifications, and equivalents that fall within the spirit and scope of the appended claims.

[0028] like Figure 1 As shown, an embodiment of the present disclosure proposes a power supply system based on automatic switching, including: a mains power system 1, a photovoltaic system 2 and an automatic switching device 3, the photovoltaic system 2 includes: multiple photovoltaic power generation modules 21, the automatic switching device 3 includes: multiple first switch units 31 and a first control unit 32; wherein, the power supply end of the mains power system 1 is connected to the power supply end of the load 6, the power supply ends of the multiple first switch units 31 are respectively connected to the power supply ends of the multiple photovoltaic power generation modules 21, and the power supply ends of the multiple first switch units 31 are connected in parallel to the power supply end of the load 6, the multiple output ends of the first control unit 32 are respectively connected to the input ends of the multiple first switch units 31, and the first control unit 32 is used to control the on and off of the multiple first switch units 31 so that the current at the power supply end of the photovoltaic system 2 matches the current at the power supply end of the load 6.

[0029] It can be understood that since the power supply end of the mains system 1 is connected to the power supply end of the load 6, the mains system 1 can supply power to the load 6, and since the power supply ends of multiple first switch units 31 are respectively connected to the power supply ends of multiple photovoltaic power generation modules 21, and the power supply ends of multiple first switch units 31 are connected in parallel to the power supply end of the load 6, when the first switch unit 31 is turned on, the photovoltaic power generation module 21 can supply power to the load 6. Therefore, by utilizing the power supply of the photovoltaic power generation module 21, the energy consumption of the mains system 1 can be reduced, thereby reducing the electricity cost of the load 6.

[0030] Moreover, since the multiple output ends of the first control unit 32 are respectively connected to the input ends of the multiple first switch units 31, the first control unit 32 can independently control the on and off of each first switch unit 31, thereby being able to control the number of photovoltaic power generation modules 21 participating in the power supply of the load 6, thereby achieving the matching of the current at the power supply end of the photovoltaic system 2 and the current at the power supply end of the load 6, thereby avoiding the problem of "surplus power being connected to the grid" when the photovoltaic system 2 supplies power to the mains system 1, and ensuring a higher power quality of the mains system 1. At the same time, this method will not directly cut off the power supply of the photovoltaic system 2, avoiding the waste of the power generated by the photovoltaic system 2, thereby ensuring a lower electricity cost for the load 6 and meeting the low-cost operation requirements.

[0031] It should be noted that the mains power system 1 refers to the municipal power supply system. The mains power system 1 transmits and distributes electric energy to the load 6 through the power network. The mains power system 1 may include: transmission and distribution lines, substations, distribution stations, etc. The specific type of the mains power system 1 can be set according to actual needs and is not limited to this.

[0032] Photovoltaic system 2 refers to a photovoltaic power generation system. Photovoltaic system 2 uses the photovoltaic effect of photovoltaic cells to directly convert solar radiation energy into electrical energy. Photovoltaic system 2 is a distributed structure, including: multiple photovoltaic power generation modules 21. Photovoltaic power generation modules 21 can perform independent photovoltaic power generation. The specific type of photovoltaic system 2 can be set according to actual needs and is not limited to this.

[0033] The automatic switching device 3 is used for automatic switching of the photovoltaic system 2 .

[0034] The first switch unit 31 is used for on-off control of the path between the photovoltaic power generation module 21 and the load 6 . The specific type of the first switch unit 31 can be set according to actual needs and is not limited thereto.

[0035] The first control unit 32 is used to control the on and off of the first switch unit 31 . The specific type of the first control unit 32 can be set according to actual needs and is not limited thereto.

[0036] The number of the first switch units 31 corresponds to the number of the photovoltaic power generation modules 21. Specifically, when the number of the first switch units 31 and the number of the photovoltaic power generation modules 21 are both N, then under the control of the first control unit 32, n first switch units 31 can be turned on at the same time, and n is an integer from 1 to N. The specific value of n can be determined according to the current at the power supply end of the load 6, aiming to ensure that the difference between the current at the power supply end of the photovoltaic system 2 and the current at the power supply end of the load 6 is within a preset range.

[0037] like Figure 1 As shown, in some embodiments, the automatic switching device 3 also includes: a first current detection unit 33, the detection end of the first current detection unit 33 is set at the power supply end of the load 6, and the output end of the first current detection unit 33 is connected to the input end of the first control unit 32.

[0038] It can be understood that since the detection end of the first current detection unit 33 is set at the power supply end of the load 6, and the output end of the first current detection unit 33 is connected to the input end of the first control unit 32, the first current detection unit 33 can detect the current signal at the load 6 end and convert the current signal and send it to the first control unit 32, so that the first control unit 32 can control the on and off state of the first switch unit 31 according to the current signal at the load 6 end, thereby ensuring the precise matching between the current at the power supply end of the photovoltaic system 2 and the current at the power supply end of the load 6.

[0039] It should be noted that the first current detection unit 33 is used to detect the current at the load 6 end. The specific type of the first current detection unit 33 can be set according to actual needs and is not limited to this. For example, the first current detection unit 33 can be a current transformer.

[0040] like Figure 1 As shown, in some embodiments, the automatic switching device 3 further includes: a second current detection unit 34, the detection end of the second current detection unit 34 is set at the parallel end of the multiple first switching units 31, and the output end of the second current detection unit 34 is connected to the input end of the first control unit 32.

[0041] It can be understood that since the detection end of the second current detection unit 34 is set at the parallel end of multiple first switch units 31, and the output end of the second current detection unit 34 is connected to the input end of the first control unit 32, the second current detection unit 34 can detect the current signal at the end of the photovoltaic system 2 and convert the current signal and send it to the first control unit 32, so that the first control unit 32 can control the on and off state of the first switch unit 31 according to the current signal at the end of the photovoltaic system 2, thereby ensuring the precise matching between the current at the power supply end of the photovoltaic system 2 and the current at the power supply end of the load 6.

[0042] It should be noted that the second current detection unit 34 is used to detect the current at the photovoltaic system 2 end. The specific type of the second current detection unit 34 can be set according to actual needs and is not limited to this. For example, the second current detection unit 34 can be a current transformer.

[0043] like Figure 1 As shown, in some embodiments, the photovoltaic system 2 further includes: multiple inverter modules 22, the inverter modules 22 are connected in series between the power supply end of the first switch unit 31 and the power supply end of the photovoltaic power generation module 21, and the power supply ends of the multiple inverter modules 22 are respectively connected to the power supply ends of the multiple photovoltaic power generation modules 21, and the power supply ends of the multiple inverter modules 22 are respectively connected to the power supply ends of the multiple first switch units 31.

[0044] It can be understood that since the power supply ends of multiple inverter modules 22 are respectively connected to the power supply ends of multiple photovoltaic power generation modules 21, and the power supply ends of multiple inverter modules 22 are respectively connected to the power supply ends of multiple first switch units 31, the inverter module 22 can convert the direct current generated by the photovoltaic power generation module 21 into alternating current, and when the first switch unit 31 is turned on, the alternating current is transmitted to the load 6, thereby meeting the power demand of the load 6.

[0045] It should be noted that the inverter module 22 is used for inverting electric energy, that is, converting direct current into alternating current. The specific type of the inverter module 22 can be set according to actual needs and is not limited to this. For example, the inverter module 22 can be an inverter.

[0046] The number of the inverter modules 22 corresponds to the number of the photovoltaic power generation modules 21 .

[0047] like Figure 1 As shown, in some embodiments, the power supply system also includes: a transformer 4, which is connected in series between the power supply end of the mains system 1 and the power supply end of the load 6, and the power supply end of the transformer 4 is connected to the power supply end of the mains system 1, and the power supply end of the transformer 4 is connected to the power supply end of the load 6.

[0048] It can be understood that since the power supply end of the transformer 4 is connected to the power supply end of the mains system 1, and the power supply end of the transformer 4 is connected to the power supply end of the load 6, the transformer 4 can convert the electric energy generated by the mains system 1 and transmit it to the load 6, thereby meeting the power demand of the load 6.

[0049] It should be noted that the transformer 4 is used for converting electric energy, stepping up or down the voltage. The specific type of the transformer 4 can be set according to actual needs and is not limited to this.

[0050] In some embodiments, the power supply terminal of the first control unit 32 is connected to the power supply terminal of the mains power system 1 .

[0051] It can be understood that since the power supply end of the first control unit 32 is connected to the power supply end of the AC power system 1, when all the first switch units 31 are disconnected, the first control unit 32 can still be powered stably, thereby ensuring the stable control of the first switch unit 31 by the first control unit 32.

[0052] like Figure 1 and Figure 2 As shown, in some embodiments, the power supply system further includes: a backflow prevention device 5, the backflow prevention device 5 includes: a second switch unit 51 and a second control unit 52; wherein, the second switch unit 51 is connected in series between the parallel ends of multiple first switch units 31 and the power supply end of the load 6, and the power supply end of the second switch unit 51 is connected to the parallel ends of multiple first switch units 31, the power supply end of the second switch unit 51 is connected to the power supply end of the load 6, the output end of the second control unit 52 is connected to the input end of the second switch unit 51, and the second control unit 52 is used to control the second switch unit 51 to disconnect when the photovoltaic system 2 supplies power to the mains system 1.

[0053] It can be understood that since the second switch unit 51 is connected in series between the parallel ends of multiple first switch units 31 and the power supply end of the load 6, and the output end of the second control unit 52 is connected to the input end of the second switch unit 51, the second control unit 52 can use the on and off of the second switch unit 51 to realize the power supply control of the photovoltaic system 2. Therefore, when the automatic switching device 3 fails, the anti-backflow device 5 can realize the power supply interruption of the photovoltaic system 2, thereby utilizing double protection to avoid the "surplus power access" problem of the photovoltaic system 2 supplying power to the mains system 1, and ensure the higher power quality of the mains system 1.

[0054] It should be noted that the backflow prevention device 5 is used for backflow protection of the photovoltaic system 2. When the photovoltaic system 2 supplies power to the load 6, if it also generates surplus electricity, the surplus electricity will flow back to the mains system 1. The backflow prevention device 5 uses the timely disconnection of the second switch unit 51 to avoid the problem of "surplus electricity going online".

[0055] The second switch unit 51 is used to control the power supply of the photovoltaic system 2. Specifically, when the second switch unit 51 is turned on, the photovoltaic system 2 can supply power to the load 6, and excess power can also be transmitted to the mains system 1. When the second switch unit 51 is turned off, the photovoltaic system 2 cannot supply power to the load 6 or the mains system 1. The specific type of the second switch unit 51 can be set according to actual needs and is not limited to this.

[0056] The second control unit 52 is used to control the on and off of the second switch unit 51. The specific type of the second control unit 52 can be set according to actual needs and is not limited to this.

[0057] like Figure 2 As shown, in some embodiments, the backflow prevention device 5 also includes: a third current detection unit 53, the detection end of the third current detection unit 53 is set at the power supply end of the load 6, and the output end of the third current detection unit 53 is connected to the input end of the second control unit 52.

[0058] It can be understood that since the detection end of the third current detection unit 53 is set at the power supply end of the load 6, and the output end of the third current detection unit 53 is connected to the input end of the second control unit 52, the third current detection unit 53 can detect the current signal at the load 6 end and convert the current signal and send it to the second control unit 52, so that the second control unit 52 can control the on-off state of the second switch unit 51 according to the current signal at the load 6 end, thereby effectively avoiding the "surplus power grid connection" problem of the photovoltaic system 2 supplying power to the mains system 1.

[0059] It should be noted that the third current detection unit 53 is used to detect the current at the load 6 end. The specific type of the third current detection unit 53 can be set according to actual needs and is not limited to this. For example, the third current detection unit 53 can be a current transformer.

[0060] like Figure 2 As shown, in some embodiments, the backflow prevention device 5 also includes: a fourth current detection unit 54, the detection end of the fourth current detection unit 54 is set at the parallel end of the multiple first switch units 31, and the output end of the fourth current detection unit 54 is connected to the input end of the second control unit 52.

[0061] It can be understood that since the detection end of the fourth current detection unit 54 is set at the parallel end of multiple first switch units 31, the output end of the fourth current detection unit 54 is connected to the input end of the second control unit 52, so that the fourth current detection unit 54 can detect the current signal at the end of the photovoltaic system 2 and convert the current signal and send it to the second control unit 52, so that the second control unit 52 can control the on-off state of the second switch unit 51 according to the current signal at the end of the photovoltaic system 2, thereby effectively avoiding the "surplus power grid connection" problem of the photovoltaic system 2 supplying power to the mains system 1.

[0062] It should be noted that the fourth current detection unit 54 is used to detect the current at the photovoltaic system 2 end. The specific type of the fourth current detection unit 54 can be set according to actual needs and is not limited to this. For example, the fourth current detection unit 54 can be a current transformer.

[0063] In some embodiments, the power supply terminal of the second control unit 52 is connected to the power supply terminal of the mains power system 1 .

[0064] It can be understood that since the power supply end of the second control unit 52 is connected to the power supply end of the AC power system 1, when all the first switch units 31 and the second switch units 51 are disconnected, the second control unit 52 can still be powered stably, thereby ensuring the stable control of the second switch unit 51 by the second control unit 52.

[0065] The power supply system of this embodiment is based on automatic switching, which has the following advantages compared with the traditional anti-backflow protection method: the proportion of the photovoltaic power generation module 21 put into operation to the power consumption capacity of the operating load can be set, so as to always maintain the maximum utilization rate of the photovoltaic system 2; the "one-size-fits-all" effect of the anti-backflow device 5 is avoided, thereby avoiding the waste of the electricity generated by the photovoltaic system 2; the anti-backflow device 5 is still provided and used as a backup device, which plays a "double insurance" role and prevents the occurrence of "surplus power on the grid"; the automatic switching device 3 not only controls the photovoltaic system 2 according to the changes in the operating equipment, but also controls its input and removal according to the power generation of the photovoltaic system 2, thereby realizing two-way control; the automatic switching device 3 can be directly installed on the side of the AC combiner box of the photovoltaic system 2 without changing the existing system structure of the photovoltaic system 2, thereby greatly reducing the transformation cost.

[0066] It should be noted that, in the description of this disclosure, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance. In addition, in the description of this disclosure, unless otherwise specified, the meaning of "plurality" is two or more.

[0067] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code that includes one or more executable instructions for implementing the steps of a specific logical function or process, and the scope of the preferred embodiments of the present disclosure includes additional implementations in which functions may be performed out of the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present disclosure belong.

[0068] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present disclosure. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0069] Although the embodiments of the present disclosure have been shown and described above, it is understood that the above embodiments are illustrative and are not to be construed as limitations on the present disclosure. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present disclosure.

Claims

1. A power supply system based on automatic switching, characterized in that: include: A commercial power system, a photovoltaic system and an automatic switching device, wherein the photovoltaic system includes: a plurality of photovoltaic power generation modules, and the automatic switching device includes: a plurality of first switch units and a first control unit; Wherein, the power supply end of the mains system is connected to the power supply end of the load; The power supply ends of the plurality of first switch units are respectively connected to the power supply ends of the plurality of photovoltaic power generation modules, and the power supply ends of the plurality of first switch units are connected in parallel to the power supply end of the load; The multiple output ends of the first control unit are respectively connected to the input ends of the multiple first switch units, and the first control unit is used to control the on and off of the multiple first switch units so that the power supply end current of the photovoltaic system matches the power supply end current of the load.

2. The power supply system based on automatic switching according to claim 1, characterized in that: The automatic switching device also includes: A first current detection unit, wherein a detection end of the first current detection unit is arranged at the power supply end of the load, and an output end of the first current detection unit is connected to an input end of the first control unit.

3. The power supply system based on automatic switching according to claim 1, characterized in that: The automatic switching device also includes: A second current detection unit, wherein a detection end of the second current detection unit is arranged at a parallel end of a plurality of the first switch units, and an output end of the second current detection unit is connected to an input end of the first control unit.

4. The power supply system based on automatic switching according to claim 1, characterized in that: The photovoltaic system further comprises: Multiple inverter modules are connected in series between the power supply end of the first switch unit and the power supply end of the photovoltaic power generation module, and the power supply ends of the multiple inverter modules are respectively connected to the power supply ends of the multiple photovoltaic power generation modules, and the power supply ends of the multiple inverter modules are respectively connected to the power supply ends of the multiple first switch units.

5. The power supply system based on automatic switching according to claim 1, characterized in that: The power supply system further includes: A transformer is connected in series between the power supply end of the mains system and the power supply end of the load, and the power supply end of the transformer is connected to the power supply end of the mains system, and the power supply end of the transformer is connected to the power supply end of the load.

6. The power supply system based on automatic switching according to claim 1, characterized in that: The power supply end of the first control unit is connected to the power supply end of the mains power system.

7. The power supply system based on automatic switching according to any one of claims 1 to 6, characterized in that: The power supply system further includes: The backflow prevention device comprises: a second switch unit and a second control unit; The second switch unit is connected in series between the parallel ends of the plurality of first switch units and the power supply end of the load, and the power supply end of the second switch unit is connected to the parallel ends of the plurality of first switch units, and the power supply end of the second switch unit is connected to the power supply end of the load; The output end of the second control unit is connected to the input end of the second switch unit, and the second control unit is used to control the second switch unit to be disconnected when the photovoltaic system supplies power to the mains system.

8. The power supply system based on automatic switching according to claim 7, characterized in that: The anti-backflow device also includes: A third current detection unit, wherein a detection end of the third current detection unit is arranged at the power supply end of the load, and an output end of the third current detection unit is connected to an input end of the second control unit.

9. The power supply system based on automatic switching according to claim 7, characterized in that: The anti-backflow device also includes: A fourth current detection unit, wherein a detection end of the fourth current detection unit is arranged at a parallel end of a plurality of the first switch units, and an output end of the fourth current detection unit is connected to an input end of the second control unit.

10. The power supply system based on automatic switching according to claim 7, characterized in that: The power supply end of the second control unit is connected to the power supply end of the mains power system.

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