Anti-reflux device, system and method and power generation system

Abstract

The invention relates to an anti-backflow device, system and method and a power generation system. The anti-countercurrent device comprises an AC-DC conversion power supply module used for taking power from an inverter power grid side to obtain a DC power supply signal to at least supply power to a main control module; the detection module is connected in series in the electric energy output branch of the single photovoltaic power generation unit and is used for detecting, obtaining and outputting a first flow direction signal containing current flow direction information in the electric energy output branch; the electronic switch module is connected in series in the electric energy output branch and is used for connecting or disconnecting the electric energy output branch; and the main control module is used for acquiring the first flow direction signal to obtain the current flow direction and controlling the on-off of the electronic switch module according to the current flow direction. According to the embodiment of the invention, current detection, reverse current blocking and automatic recovery can be automatically controlled by the system, manual intervention is not needed, and the maintenance cost of the power station is greatly reduced.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic power generation technology, and in particular to an anti-backflow device, system, method and power generation system. Background Art

[0002] At present, in photovoltaic power generation systems, anti-reverse flow solutions are usually set up to prevent possible current backflow. For example, a MOS tube is connected in series at the output end of a photovoltaic string / module, and the drain-source voltage of the MOS tube is detected to determine whether current backflow occurs and to implement control to cut off the current backflow path. However, this voltage detection and control process is relatively complicated.

[0003] For another example, traditional high-voltage axial diodes are connected in series at the output end of photovoltaic strings / modules to cut off the current backflow path. However, the forward voltage drop of the diode is too high under normal circumstances, which consumes tens of watts of power and generates severe heat, resulting in high power consumption and low reliability.

[0004] Therefore, it is urgent to propose an anti-backflow solution with simple detection and control process, low power consumption and high reliability. Summary of the invention

[0005] In view of this, the embodiments of the present application provide a backflow prevention device, a backflow prevention system, a photovoltaic power generation system, a backflow prevention method, a main control device, a system platform device and a storage medium to solve at least one problem existing in the background technology.

[0006] In a first aspect, an embodiment of the present application provides a backflow prevention device, the backflow prevention device comprising:

[0007] An AC-DC conversion power supply module is connected to the grid side of the inverter, and is used to obtain an AC power supply signal from the grid side of the inverter, and convert the AC power supply signal into a DC power supply signal to at least supply power to the main control module;

[0008] A detection module is connected in series in an electric energy output branch of a single photovoltaic power generation unit, and is used to detect, obtain and output a first flow direction signal containing current flow direction information in the electric energy output branch; the electric energy output branch is connected in parallel to a first power supply terminal connection line on the grid side of the inverter;

[0009] an electronic switch module, connected in series in the power output branch, for switching on the power output branch so that a single photovoltaic power generation unit outputs power to the grid side of the inverter; or, switching off the power output branch to cut off the current backflow loop; and

[0010] A main control module is connected to the AC / DC conversion power supply module to obtain the DC power supply signal; and is respectively connected to the detection module and the electronic switch module to obtain the first flow direction signal to obtain the current flow direction, and control the on and off of the electronic switch module according to the current flow direction.

[0011] In combination with the first aspect, in an optional implementation,

[0012] The detection module is used to determine and obtain the first flow direction signal according to the detected signal sampling value in the electric energy output branch.

[0013] In combination with the first aspect, in an optional implementation,

[0014] The first signal transmission end of the detection module is connected to the output end of a single photovoltaic power generation unit, the second signal transmission end of the detection module is connected to the first signal end of the electronic switch module, and the detection output end of the detection module is connected to the main control module;

[0015] The second signal end of the electronic switch module is connected to the first power supply end connection line of the inverter grid side, and the control end of the electronic switch module is connected to the main control module.

[0016] In combination with the first aspect, in an optional implementation,

[0017] The electronic switch module includes at least one of the following: an electronic circuit breaker; a relay; a high-voltage MOS tube; and a high-voltage DC contactor.

[0018] In combination with the first aspect, in an optional implementation,

[0019] The electronic switch module is configured as a normally open type.

[0020] In combination with the first aspect, in an optional implementation,

[0021] The detection module includes a current sensor.

[0022] In combination with the first aspect, in an optional implementation,

[0023] The photovoltaic power generation unit includes a photovoltaic string or a photovoltaic module.

[0024] In a second aspect, an embodiment of the present application provides a backflow prevention system, the backflow prevention system comprising:

[0025] At least one backflow prevention device as described in the first aspect; and

[0026] The system platform end is respectively connected to each of the anti-backflow devices for communicating and monitoring the current flow direction in the power output branch of each photovoltaic power generation unit and controlling the on and off of the electronic switch module of each of the anti-backflow devices.

[0027] In conjunction with the second aspect, in an optional implementation, the backflow prevention system further includes a communication base station, which is respectively connected to the system platform end and each of the backflow prevention devices for communicating data and instructions between the system platform end and the backflow prevention devices;

[0028] The main control module of the anti-backflow device is also used to transmit a second flow direction signal containing current flow direction information in the electric energy output branch to the system platform end; the system platform end is also used to obtain the second flow direction signal to obtain the current flow direction, and generate a control instruction according to the current flow direction to control the on and off of the electronic switch module of the anti-backflow device.

[0029] In a third aspect, an embodiment of the present application provides a photovoltaic power generation system, the photovoltaic power generation system comprising:

[0030] At least one power generation circuit connected in parallel between the first power terminal connection line and the GND ground line on the grid side of the inverter;

[0031] Wherein, each power generation circuit comprises a single photovoltaic power generation unit connected in series and the anti-backflow device as described in the first aspect.

[0032] In a fourth aspect, an embodiment of the present application provides a backflow prevention method, which is applied to a backflow prevention device, and the backflow prevention method includes:

[0033] During the operation process in which a single photovoltaic power generation unit is connected in parallel between the first power terminal connection line and the GND ground line on the grid side of the inverter through the backflow prevention device, the electronic switch module of the backflow prevention device is controlled to be closed;

[0034] Obtain the current flow direction in the power output branch of a single photovoltaic power generation unit;

[0035] When the current flows in the opposite direction to the normal direction, the electronic switch module is controlled to be disconnected to cut off the connection between the single photovoltaic power generation unit and the grid side of the inverter;

[0036] Starting timing when the electronic switch module is disconnected to obtain a first duration;

[0037] When the first duration reaches a first threshold time, the current flow direction is reacquired, and when the reacquired current flow direction is the same as the normal flow direction, the electronic switch module is controlled to remain closed; when the reacquired current flow direction is opposite to the normal flow direction, the process returns to the step of controlling the electronic switch module to be disconnected.

[0038] In conjunction with the fourth aspect, in an optional implementation manner, the backflow prevention method further includes:

[0039] After the power plant is completed and put into operation, the electronic switch modules of all anti-backflow devices are controlled to close;

[0040] Obtain the current flow direction in the power output branch of each photovoltaic power generation unit;

[0041] Reporting the current flow direction to the system platform end;

[0042] Obtaining a shutdown instruction issued by the system platform end when the current flow direction in any photovoltaic power generation unit power output branch is opposite to the normal flow direction;

[0043] Under the control of the shutdown instruction, the electronic switch module of the anti-backflow device connected to the photovoltaic power generation unit is controlled to be disconnected;

[0044] Obtaining an on instruction issued by the system platform end at a second threshold time after issuing the off instruction;

[0045] Under the control of the start instruction, the electronic switch module is controlled to close to regain the current direction, and returns to the step of reporting the current direction to the system platform end, so that when the current direction is the same as the normal direction, the electronic switch module is controlled to remain closed; when the current direction is opposite to the normal direction, the electronic switch module is controlled to open.

[0046] In a fifth aspect, an embodiment of the present application provides a backflow prevention method, which is applied to a system platform end in a backflow prevention system, and the backflow prevention method includes:

[0047] Obtain the current flow direction in the power output branch of each photovoltaic power generation unit;

[0048] When the current flow direction in the power output branch of any photovoltaic power generation unit is opposite to the normal flow direction, a shutdown command is generated and sent to the main control module in the anti-backflow device connected to the photovoltaic power generation unit to control the electronic switch module in the anti-backflow device connected to the photovoltaic power generation unit to disconnect;

[0049] After the shutdown instruction is issued, start timing to obtain a second duration;

[0050] When the second duration reaches the second threshold time, an opening instruction is sent to the main control module to control the electronic switch module to close, and return to the step of obtaining the current flow direction in the power output branch of each photovoltaic power generation unit.

[0051] In a sixth aspect, an embodiment of the present application provides a main control device, the main control device comprising:

[0052] A first processing module is used to control the electronic switch module of the anti-backflow device to close during the operation process in which a single photovoltaic power generation unit is connected in parallel between the first power terminal connection line and the GND ground line on the grid side of the inverter through the anti-backflow device;

[0053] The second processing module is used to obtain the current flow direction in the power output branch of a single photovoltaic power generation unit;

[0054] A third processing module is used to control the electronic switch module to disconnect when the current flows in the opposite direction to the normal direction, so as to cut off the connection between the single photovoltaic power generation unit and the grid side of the inverter;

[0055] A fourth processing module, configured to start timing when the electronic switch module is disconnected to obtain a first duration;

[0056] The fifth processing module is used to reacquire the current flow direction when the first duration reaches a first threshold time, and when the reacquired current flow direction is the same as the normal flow direction, control the electronic switch module to remain closed; when the reacquired current flow direction is opposite to the normal flow direction, return to the third processing module.

[0057] In a seventh aspect, an embodiment of the present application provides a system platform device, the system platform device comprising:

[0058] A sixth processing module, used to obtain the current flow direction in the power output branch of each photovoltaic power generation unit;

[0059] The seventh processing module is used to generate and issue a shutdown instruction to the main control module in the anti-backflow device connected to any photovoltaic power generation unit when the current flow direction in the power output branch of any photovoltaic power generation unit is opposite to the normal flow direction, so as to control the electronic switch module in the anti-backflow device connected to the photovoltaic power generation unit to disconnect;

[0060] An eighth processing module, configured to start timing after issuing the shutdown instruction to obtain a second duration;

[0061] The ninth processing module is used to send an opening instruction to the main control module to control the electronic switch module to close when the second duration reaches the second threshold time, and return to the sixth processing module.

[0062] In an eighth aspect, an embodiment of the present application provides a main control device, the main control device comprising:

[0063] a memory storing instructions; and

[0064] A processor is configured to execute the instructions to implement the anti-backflow method as described in the fourth aspect.

[0065] In a ninth aspect, an embodiment of the present application provides a system platform device, the system platform device comprising:

[0066] a memory storing instructions; and

[0067] A processor is configured to execute the instructions to implement the anti-backflow method as described in the fifth aspect.

[0068] In the tenth aspect, an embodiment of the present application provides a storage medium, in which a computer program is stored. When the computer program is executed, it can implement the anti-backflow method as described in the fourth aspect or the anti-backflow method as described in the fifth aspect.

[0069] The beneficial effects of the technical solution provided by the embodiment of the present application include: through the detection module and the main control module, the current direction in the power output branch of a single photovoltaic power generation unit is monitored in real time. When a reverse current occurs, the electronic switch module connected in series in the branch is immediately disconnected to cut off the current backflow path to avoid the reverse flow phenomenon between different photovoltaic power generation units. Therefore, the embodiment of the present application can prevent and control the current backflow phenomenon caused by the voltage difference between photovoltaic components and photovoltaic strings due to the number of deployments, optimizer regulation, shielding, etc., and realize the backflow prevention; it can be compatible with the backflow prevention between photovoltaic components and photovoltaic strings at the same time, and can automatically restore power generation after the current is normal, without manual intervention, simplifying the detection and control process; and the series internal resistance of the electronic switch module connected in series is usually at the milliohm level, which can ensure small power loss and heat generation under normal conditions of large current, low power consumption and high reliability, simple structural design, and high cost performance. The current detection, reverse flow blocking and automatic recovery of the embodiment of the present application can all be automatically controlled by the system without manual intervention, which greatly reduces the maintenance cost of the power station. And because the electric energy output branch is connected in parallel to the first power supply terminal connection line on the grid side of the inverter, each physical photovoltaic power generation unit can be configured with a separate anti-backflow device, and different anti-backflow devices can work independently of each other, thereby improving reliability and ensuring safe and stable operation of the system.

[0070] Additional aspects and advantages of the embodiments of the present application will be given in part in the description below and in part will become apparent from the description below or will be learned through the practice of the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The drawings are not necessarily drawn to scale, and local features may be enlarged or reduced to more clearly show the details of the local features. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0072] Figure 1 A schematic diagram of a principle block diagram of a specific example of an anti-backflow device in an embodiment of the present application;

[0073] Figure 2 A circuit diagram of a specific example of a backflow prevention device in an embodiment of the present application;

[0074] Figure 3 A schematic diagram of a specific example of current flow in an embodiment of the present application;

[0075] Figure 4 A schematic diagram of a principle block diagram of a specific example of an anti-backflow system in an embodiment of the present application;

[0076] Figure 5 This is a schematic flow chart of Example 1 of the backflow prevention method in the embodiments of the present application;

[0077] Figure 6 This is a schematic flow chart of Example 2 of the backflow prevention method in the embodiment of the present application;

[0078] Figure 7 This is a schematic flow chart of Example 3 of the backflow prevention method in the embodiments of the present application;

[0079] Figure 8 A schematic diagram of a principle block diagram of a specific example of a main control device in an embodiment of the present application;

[0080] Fig. 9 A schematic diagram of a principle block diagram of a specific example of a system platform device in an embodiment of the present application;

[0081] Fig.10 It is a structural diagram of a specific example of a main control device or a system platform device in an embodiment of the present application. DETAILED DESCRIPTION

[0082] In order to make the technical solutions and beneficial effects of the present application more obvious and easy to understand, the following is a detailed description by listing specific embodiments. The drawings are not necessarily drawn to scale, and local features may be enlarged or reduced to more clearly show the details of the local features; unless otherwise defined, the technical and scientific terms used herein have the same meanings as those in the technical field to which the present application belongs.

[0083] The embodiments of the present application are not exhaustive, but are only illustrative of some embodiments, and are not intended to be a specific limitation on the scope of protection of the present application. In the absence of contradiction, each step in a certain embodiment can be implemented as an independent embodiment, and the steps can be arbitrarily combined. For example, in a certain embodiment, the solution after removing some steps can also be implemented as an independent embodiment, and the order of the steps in a certain embodiment can be arbitrarily exchanged. In addition, the optional implementations in a certain embodiment can be arbitrarily combined; in addition, the embodiments can be arbitrarily combined, for example, some or all of the steps of different embodiments can be arbitrarily combined, and a certain embodiment can be arbitrarily combined with the optional implementations of other embodiments.

[0084] In each embodiment of the present application, unless otherwise specified or there is a logical conflict, the terms and / or descriptions between the embodiments are consistent and can be referenced to each other. The technical features in different embodiments can be combined to form a new embodiment based on their internal logical relationships.

[0085] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application.

[0086] In the embodiments of the present application, unless otherwise specified, elements expressed in the singular form, such as "a", "an", "the", "above", "said", "aforementioned", "this", etc., may mean "one and only one", or "one or more", "at least one", etc. For example, when using articles such as "a", "an", "the" in English in translation, the noun after the article may be understood as a singular expression or a plural expression.

[0087] In the embodiments of the present application, "plurality" refers to two or more.

[0088] In some embodiments, the terms "at least one", "one or more", "a plurality of", "multiple", etc. can be used interchangeably.

[0089] The prefixes such as "first" and "second" in the embodiments of the present application are only used to distinguish different description objects, and do not constitute restrictions on the position, order, priority, value or content of the description objects. The statement of the description object refers to the description in the context of the claims or embodiments, and should not constitute unnecessary restrictions due to the use of prefixes. For example, the numerical value of the description object is not limited by the ordinal number, and can be one or more. Take "first device" as an example, where the numerical value of "device" can be one or more. In addition, the objects modified by different prefixes can be the same or different. For example, if the description object is "device", the "first device" and the "second device" can be the same device or different devices, and their types can be the same or different.

[0090] In some embodiments, the term "connection" may indicate that an electrical signal or data is transmitted between a connected end and a connected end, and may be understood as "electrical connection", "communication connection", etc. "Connection" may be a direct connection between two components, an indirect connection established through other components, internal communication between two components, or any other possible connection form.

[0091] This specification provides method operation steps such as embodiments or flow charts, but may include more or fewer operation steps based on conventional or non-creative labor. The order of steps listed in the embodiments is only one way of executing the order of many steps and does not represent the only execution order. When the actual device, system or server product is executed, it can be executed in the order of the method shown in the embodiments or the drawings or in parallel (for example, in a parallel processor or multi-threaded processing environment).

[0092] The embodiment of the present application provides a backflow prevention device, which can be applied to solar photovoltaic power generation, etc. Figure 1 A schematic diagram of a principle block diagram of a specific example of an anti-backflow device in an embodiment of the present application is shown. As shown in the figure, the anti-backflow device includes:

[0093] An AC-DC power supply module 24 is connected to the grid side of the inverter, and is used to obtain an AC power supply signal from the grid side of the inverter, and convert the AC power supply signal into a DC power supply signal to at least supply power to the main control module 23;

[0094] A detection module 21 is connected in series in an electric energy output branch of a single photovoltaic power generation unit, and is used to detect, obtain and output a first flow direction signal containing current flow direction information in the electric energy output branch; the electric energy output branch is connected in parallel to a first power supply terminal connection line on the grid side of the inverter;

[0095] The electronic switch module 22 is connected in series in the power output branch, and is used to conduct the power output branch so that a single photovoltaic power generation unit outputs power to the grid side of the inverter; or disconnect the power output branch to cut off the current backflow loop; and

[0096] The main control module 23 is connected to the AC / DC conversion power supply module 24 to obtain the DC power supply signal; and is respectively connected to the detection module 21 and the electronic switch module 22 to obtain the first flow direction signal to obtain the current flow direction, and control the on and off of the electronic switch module according to the current flow direction.

[0097] In the embodiment of the present application, the AC-DC conversion power supply module 24 can take power from the inverter grid side and convert it into a DC power supply to power the main control module 23 and other functional modules. In an exemplary embodiment, the detection module 21 and the electronic switch module 22 can also be powered by the AC-DC conversion power supply module 24, but it is not limited to this and can also be powered by other forms. The specific circuit structure of the AC-DC conversion power supply module 24 can be set according to actual needs.

[0098] The main control module 23 can be used to implement the scheduling and control of the entire system, and can monitor the first flow direction signal from the detection module 21 in real time, and then monitor the current flow direction in real time. The electronic switch module 22 can be in an open state by default, for example, it can be a normally open electronic switch, of course, it is not limited to this, and the electronic switch module 22 can also be a normally closed type.

[0099] When the current flows normally, the electronic switch module 22 is closed to ensure that a single photovoltaic power generation unit (such as a photovoltaic string or a photovoltaic module) generates electricity normally; once the current reverse is detected, the main control module 23 immediately sends a shutdown command to the electronic switch module 22 to cut off the power output branch where the current reverse occurs, that is, the current backflow loop, to prevent the abnormality from occurring. The main control module 23 may include a processor, the processor is connected to a memory, the memory stores instructions, and the processor calls the instructions stored in the memory to implement the functions of the main control module 23.

[0100] During the installation of photovoltaic power generation units, due to improper installation, the number of photovoltaic modules installed between photovoltaic strings under the same MPPT (Max-Power-Point-Tracking) path or under different MPPT paths is different, resulting in voltage differences, which in turn causes current backflow between different photovoltaic strings / modules, leading to power generation anomalies, fires and other serious accidents before the photovoltaic modules are put into use. Even if different photovoltaic strings are installed with the same number of photovoltaic modules in strict accordance with the specifications, in actual use, due to shading, optimizer regulation and other situations, there will also be a high voltage difference between different photovoltaic strings / modules, causing current backflow, resulting in severe heating and damage to the modules, and even fire accidents.

[0101] In this way, the embodiment of the present application realizes real-time monitoring of the current direction in the power output branch of a single photovoltaic power generation unit through the detection module 21 and the main control module 23. When reverse current occurs, the electronic switch module 22 connected in series in the branch is immediately disconnected to cut off the current backflow path to avoid the reverse flow phenomenon between different photovoltaic power generation units. Therefore, the embodiment of the present application can prevent and control the current backflow phenomenon caused by the voltage difference between photovoltaic components and photovoltaic strings due to the number of deployments, optimizer regulation, shielding, etc., and realize anti-reverse flow; it can be compatible with the anti-reverse flow backflow between photovoltaic components and photovoltaic strings at the same time, and can automatically restore power generation after the current is normal, without manual intervention, simplifying the detection and control process; and the series internal resistance of the electronic switch module connected in series is usually at the milliohm level, which can ensure small power loss and heat generation under normal conditions of large current, low power consumption and high reliability, simple structural design, and high cost performance. The current detection, reverse flow blocking and automatic recovery of the embodiment of the present application can all be automatically controlled by the system without manual intervention, greatly reducing the maintenance cost of the power station. And because the electric energy output branch is connected in parallel to the first power supply terminal connection line on the grid side of the inverter, each physical photovoltaic power generation unit can be configured with a separate anti-backflow device, and different anti-backflow devices can work independently of each other, thereby improving reliability and ensuring safe and stable operation of the system.

[0102] In an optional implementation, the detection module 21 is used to determine and obtain the first flow direction signal according to the detected signal sampling value in the electric energy output branch.

[0103] In the embodiment of the present application, the signal sampling value detected by the detection module 21 can be set according to actual needs. For example, the signal sampling value can be a voltage signal sampling value, or it can also be a current signal sampling value or a magnetic signal sampling value. The first flow direction signal output by the detection module 21 can be a voltage or current signal, which can be set according to actual needs.

[0104] Figure 2A circuit diagram of a specific example of the backflow prevention device in the embodiment of the present application is shown. As shown in the figure, in an optional embodiment, the first signal transmission end of the detection module 21 is connected to the output end of a single photovoltaic power generation unit, the second signal transmission end of the detection module 21 is connected to the first signal end of the electronic switch module 22, and the detection output end of the detection module 21 is connected to the main control module 23;

[0105] The second signal end of the electronic switch module 22 is connected to the first power supply end connection line of the inverter grid side, and the control end of the electronic switch module 22 is connected to the main control module 23 .

[0106] In the embodiment of the present application, the first signal transmission end and the second signal transmission end of the detection module 21 can be used to receive or output electrical signals on the transmission channel respectively. By detecting the voltage at both ends of the first signal transmission end and the second signal transmission end or the current between the two ends, a current or voltage sampling value can be obtained, and can be output to the main control module 23 through the detection output end of the detection module 21.

[0107] The electronic switch module 22 may include a control end, a first signal end and a second signal end. Its working principle is that under the control of the control signal input into the control end, the path between the first signal end and the second signal end is turned on or off to connect or block the signal transmission between the first signal end and the second signal end.

[0108] The detection module 21 and the electronic switch module 22 are sequentially connected in series in the power output branch of a single photovoltaic power generation unit, but are not limited thereto. The electronic switch module 22 can also be arranged between a single photovoltaic power generation unit and the detection module 21, or can also be connected in series in the power output branch in other ways.

[0109] The first power supply terminal connection line on the grid side of the inverter may be a positive power supply connection line, or may be a GND ground line, and may be set according to actual needs.

[0110] In an optional implementation, the electronic switch module 22 includes at least one of the following: an electronic circuit breaker; a relay; a high-voltage MOS tube; and a high-voltage DC contactor.

[0111] In this way, by using electronic circuit breakers, relays or high-voltage MOS tubes (metal oxide semiconductor field effect transistors), the series internal resistance can be at the milliohm level, resulting in low power consumption and heat generation under normal power generation conditions, thereby improving reliability and safety.

[0112] In an optional implementation, the electronic switch module 22 is configured as a normally open type.

[0113] In this way, the electronic switch module 22 adopts a normally open design, that is, when the system loses power or fails, the electronic switch module is in a disconnected state. When the anti-backflow device connected to a single photovoltaic power generation unit fails to work due to power supply or internal circuit failure, the electronic switch module can be restored to the initial default disconnected state to ensure safe and stable operation of the system.

[0114] In an optional implementation, the detection module 21 includes a current sensor.

[0115] It is understandable that the specific circuit structures of the electronic switch module 22 and the detection module 21 can be set according to actual needs. For example, the electronic switch module 22 may include a plurality of switch devices connected in series and / or in parallel, or may also include other devices such as resistors. The detection module 21 may also include other devices such as resistors.

[0116] In some examples, the detection module 21 can detect through a current sensor to obtain the current flow direction of the power output branch of a single photovoltaic power generation unit, or it can also detect through other detection methods, such as using a voltage sensor to detect the current flow direction in the power output branch, or using a magnetic induction sensor, Hall effect device, etc.

[0117] In an embodiment of the present application, the first signal transmission end of the detection module 21 (such as a current sensor) can be a positive power input end or a negative power input end; correspondingly, its second signal transmission end can be a negative power input end or a positive power input end.

[0118] In an optional embodiment, the photovoltaic power generation unit includes a photovoltaic string or a photovoltaic module.

[0119] In this exemplary embodiment, the photovoltaic modules can be connected in series to form a photovoltaic string. The number of photovoltaic power generation units can be N, and accordingly, the number of backflow prevention devices can also be N, where N can be a natural number greater than or equal to 1.

[0120] Figure 3 A schematic diagram showing a specific example of current flow in an embodiment of the present application is shown. As shown in the figure, under normal circumstances, a single photovoltaic power generation unit outputs voltage to the inverter grid side in parallel through a closed electronic switch module.

[0121] When current backflow occurs, the current follows Figure 3 The reverse current flows in the direction of the backflow current. At this time, the electronic switch module is controlled to disconnect, cutting off the current backflow loop of a single photovoltaic power generation unit. Other photovoltaic power generation units can still generate electricity normally.

[0122] In this way, when the power station is in the construction stage, the photovoltaic power generation units are not connected to the system during the series connection process. Each photovoltaic power generation unit is equipped with an anti-backflow device. The built-in detection module and main control module of the anti-backflow device can monitor the current flow between itself and the adjacent photovoltaic power generation units in real time. When the main control module determines that the current is flowing in the opposite direction, the electronic switch module can be immediately controlled to disconnect, cut off the current backflow loop, and realize the reverse current local protection action. Then, according to the detection cycle set by the main control module, the electronic switch module can be closed to monitor the current flow again; if the current flow is normal, the electronic switch module is controlled to close to ensure the normal power generation of the system; otherwise, it continues to remain disconnected until the current flow is normal, and then the electronic switch module is closed.

[0123] The present application also provides a backflow prevention system. Figure 4 A schematic diagram of a principle block diagram of a specific example of an anti-backflow system in an embodiment of the present application is shown. As shown in the figure, the anti-backflow system includes:

[0124] At least one backflow prevention device 20 as described in the above embodiment; and

[0125] The system platform end 30 is respectively connected to each of the anti-backflow devices 20 for communication, and is used to monitor the current flow direction in the power output branch of each photovoltaic power generation unit, and to control the on and off of the electronic switch module of each of the anti-backflow devices 20.

[0126] In the embodiment of the present application, the system platform end 30 is mainly used for real-time monitoring of the current flow direction of each photovoltaic power generation unit after the photovoltaic power generation unit is installed and put into operation, and sending a shut-off or closing instruction to the anti-backflow device 20. For example, the system platform end 30 can be a cloud management platform.

[0127] In an exemplary embodiment, when the system platform end 30 detects that the current flow in the power output branch of a photovoltaic power generation unit is reversed, a shutdown command can be issued to control the electronic switch module connected to the photovoltaic power generation unit to shut down, so that the parallel branch of the photovoltaic power generation unit is disconnected from the grid side of the inverter and the parallel branches of other photovoltaic power generation units, thereby improving reliability.

[0128] Then, the system platform end 30 can issue an opening instruction according to the set cycle, and at the same time detect whether the current flow direction returns to normal. If it returns to normal, the electronic switch module is controlled to close to ensure that the photovoltaic power generation unit generates electricity normally; otherwise, the electronic switch module continues to be turned off to prevent current backflow from causing abnormalities.

[0129] In an optional embodiment, the backflow prevention system also includes a communication base station 40, which is respectively communicatively connected to the system platform end 30 and each of the backflow prevention devices 20 to transmit communication data and / or instructions (signals) between the system platform end 30 and the backflow prevention device 20.

[0130] In the embodiment of the present application, the communication base station 40 serves as a communication hub between the system platform end 30 and the anti-backflow device 20, and each anti-backflow device 20 can serve as an RSD node. RSD (Rack Scale Design) nodes may refer to the basic hardware components that constitute the rack computing unit, and each node may include a processor (such as a CPU), memory, local storage, and a network interface, etc. The communication base station 40 may receive a second flow direction signal containing current flow direction information in the power output branch from the anti-backflow device 20, and transmit it uplink to the system platform end 30; and may receive real-time control instructions from the system platform end 30 downlink, and send them to the designated anti-backflow device 20, thereby ultimately achieving rapid shutdown or closure of a single photovoltaic power generation unit.

[0131] The communication method between the system platform end 30 and the backflow prevention device 20 is not limited to the communication base station 40, and can also be direct communication interaction.

[0132] The backflow prevention device 20 can be communicatively connected to the system platform end 30 and / or communicatively connected to the communication base station 40 through the main control module 23 .

[0133] In an optional embodiment, the main control module 23 of the anti-backflow device 20 is also used to transmit a second flow direction signal containing current flow direction information in the electric energy output branch to the system platform end 30; the system platform end 30 is also used to obtain the second flow direction signal to obtain the current flow direction, and generate a control instruction according to the current flow direction to control the on and off of the electronic switch module 22 of the anti-backflow device 20.

[0134] In this way, the embodiment of the present application detects the backflow of current by means of the linkage control of the anti-backflow device connected to a single photovoltaic power generation unit and the system platform end, cuts off the current backflow path, avoids abnormal accidents, and ensures the safety of the solar photovoltaic module power generation system. And by combining the anti-backflow device and the system platform end, it can cover the anti-backflow in all stages of power station construction and operation. It can target the current backflow phenomenon caused by the voltage difference between photovoltaic modules and strings due to the number of deployments, optimizers, shading, etc., and achieve the anti-backflow effect in the two situations of the photovoltaic power generation unit series connection process in the early stage of power station construction and the operation process after the power station construction is completed.

[0135] In the early stage of power station construction, during the series connection of photovoltaic power generation units, a series anti-reverse flow device is configured for each photovoltaic power generation unit to detect the current flow direction between itself and the adjacent photovoltaic power generation units. Once a reverse flow occurs, the anti-reverse flow device cuts off its parallel branch through the electronic switch module to prevent the reverse flow from occurring.

[0136] When the power station is completed and put into operation, when current backflow occurs between different photovoltaic power generation units due to shading of some photovoltaic power generation units and mismatch of optimizer control voltage regulation, the system platform (such as cloud management platform) monitors the current flow direction of each parallel branch of each photovoltaic power generation unit in real time. When reverse flow occurs, the platform sends a shutdown command to the parallel branch of the photovoltaic power generation unit, cuts off the parallel branch of the photovoltaic power generation unit, and prevents the reverse flow from occurring.

[0137] Then, the embodiment of the present application can effectively avoid the voltage mismatch between different photovoltaic power generation units in the construction phase of the photovoltaic power station, as well as the current backflow, abnormal heating, fire and other serious accidents between different photovoltaic power generation units caused by optimizer regulation, shadow shielding and other reasons during operation. In addition, the installation is simple and convenient. During the operation of the power station, it can automatically detect and cut off the reverse flow. After the reverse flow fault disappears, the system can automatically resume normal operation. No manual participation is required throughout the process, which greatly reduces the operation and maintenance costs of the power station and ensures that the power station operates stably and reliably throughout its life cycle during the construction and deployment phase and the normal operation phase.

[0138] The present application also provides a photovoltaic power generation system, referring to Figure 2 , the photovoltaic power generation system comprises:

[0139] At least one power generation circuit 100 connected in parallel between the first power terminal connection line and the GND ground line on the grid side of the inverter;

[0140] Each of the power generation circuits 100 includes a single photovoltaic power generation unit 10 connected in series and a backflow prevention device 20 as described in the above embodiment.

[0141] The embodiment of the present application also provides a backflow prevention method, which can be applied to the main control module of the backflow prevention device to prevent backflow between photovoltaic power generation units (such as photovoltaic modules, photovoltaic strings) during the power station construction phase and the power station operation phase. Figure 5 The flowchart of Example 1 of the anti-backflow method in the embodiment of the present application is shown. As shown in the figure, the anti-backflow method includes:

[0142] S101: During the operation of a single photovoltaic power generation unit being connected in parallel between a first power terminal connection line and a GND ground line on the grid side of an inverter through a backflow prevention device, controlling an electronic switch module of the backflow prevention device to be closed;

[0143] S102: Obtaining the current flow direction in the power output branch of a single photovoltaic power generation unit;

[0144] S103: When the current flow direction is opposite to the normal flow direction, controlling the electronic switch module to be disconnected to cut off the connection between the single photovoltaic power generation unit and the grid side of the inverter;

[0145] S104: starting timing when the electronic switch module is disconnected to obtain a first duration;

[0146] S105: When the first duration reaches a first threshold time, the current direction is reacquired, and when the reacquired current direction is the same as the normal direction, the electronic switch module is controlled to remain closed; when the reacquired current direction is opposite to the normal direction, the process returns to the step of controlling the electronic switch module to be disconnected.

[0147] In an exemplary embodiment, the electronic switch module of the anti-backflow device may be a normally open design, which is in an open state by default. By controlling the electronic switch module to close, the detection module of the anti-backflow device may perform current sampling.

[0148] The current flow direction in the power output branch of a single photovoltaic power generation unit is obtained in step S102 by determining the current flow direction in the power output branch of the photovoltaic power generation unit according to the received electrical signal sampling value of the detection module.

[0149] When the current flow direction is the same as the normal flow direction in step S103, the process returns to step S102 to continue acquiring the current flow direction in the power output branch of the single photovoltaic power generation unit.

[0150] The normal flow direction and the first threshold time can be set according to actual needs. The first threshold time can be used to configure a detection cycle for the main control module. When the first duration reaches the first threshold time, it can indicate that a detection cycle is completed.

[0151] In this way, when the power station is in the construction stage and the photovoltaic power generation unit is not connected to the system, the embodiment of the present application monitors the current flow direction between the photovoltaic power generation unit itself and the adjacent photovoltaic power generation unit in real time during the access operation of the photovoltaic power generation unit. For example, when the main control module (local controller) detects that the current is flowing in reverse, it immediately controls the electronic switch module to shut down and cut off the reverse flow path. Then, according to the detection cycle set by the local controller, the electronic switch module is closed and the current flow direction is monitored again; if the current flow direction is normal, the electronic switch module is maintained closed, otherwise it continues to be controlled to be disconnected until the current flow direction is normal. In this way, during the access operation of a single photovoltaic power generation unit, it is possible to detect current backflow, prevent reverse flow, avoid abnormal accidents, and improve safety.

[0152] Figure 6 The flowchart of Example 2 of the anti-backflow method in the embodiment of the present application is shown. As shown in the figure, in an optional embodiment, the anti-backflow method further includes:

[0153] S201: After the power plant is completed and put into operation, the electronic switch modules of all anti-backflow devices are controlled to close;

[0154] S202: Obtain the current flow direction in the power output branch of each photovoltaic power generation unit;

[0155] S203: reporting the current flow direction to the system platform end;

[0156] S204: Obtaining a shutdown instruction issued by the system platform when the current flow direction in any photovoltaic power generation unit power output branch is opposite to the normal flow direction;

[0157] S205: Under the control of the shutdown instruction, the electronic switch module of the backflow prevention device connected to the photovoltaic power generation unit is controlled to be disconnected;

[0158] S206: Acquire a start instruction issued by the system platform end at a second threshold time after issuing the shutdown instruction;

[0159] S207: Under the control of the start instruction, the electronic switch module is controlled to close to regain the current direction, and returns to the step of reporting the current direction to the system platform end, so that when the current direction is the same as the normal direction, the electronic switch module is controlled to remain closed; when the current direction is opposite to the normal direction, the electronic switch module is controlled to open.

[0160] In an exemplary embodiment, reporting the current direction to the system platform in step S203 may be sending a signal containing the current direction information (such as an electrical signal sampling value) to the system platform; or, may be reporting through a communication base station.

[0161] The sending of the shutdown instruction in step S204 and the sending of the start instruction in step S206 may also be sent through a communication base station.

[0162] In step S206, the system platform sends an on instruction at a second threshold time after sending the off instruction. The system platform starts timing after sending the off instruction to obtain a second duration, and sends an on instruction when the second duration reaches the second threshold time.

[0163] The second threshold time can be set according to actual needs. The second threshold time can be used to configure a detection cycle for the system platform. When the second duration reaches the second threshold time, it can indicate that a detection cycle is completed.

[0164] In this way, when the power station is put into operation, the anti-backflow device configured on the photovoltaic power generation unit side monitors the current flow direction in the power output branch of each photovoltaic power generation unit in real time, and uploads it to the system platform end (such as the cloud management platform). When the system platform end finds that the current of any photovoltaic power generation unit is reversed, it can immediately send a shutdown command to the electronic switch module in the anti-backflow device connected to the photovoltaic power generation unit through the communication base station, so that it is turned off and the current backflow path is blocked; next, according to the set detection cycle, the start command is issued, and at the same time, it is detected whether the current flow direction in the power output branch of the photovoltaic power generation unit has returned to normal. If it has returned to normal, the electronic switch module is controlled to close to ensure the normal power generation of the photovoltaic power generation unit; otherwise, it continues to control its shutdown to prevent abnormalities caused by current backflow. In this way, it can prevent the backflow between photovoltaic modules and photovoltaic strings, and ensure the safety of the solar photovoltaic module power generation system.

[0165] The embodiment of the present application also provides a backflow prevention method, which can be applied to the system platform end of the backflow prevention system to prevent backflow between photovoltaic modules and photovoltaic strings during the operation phase of the power station. Figure 7 The flowchart of Example 3 of the anti-backflow method in the embodiment of the present application is shown. As shown in the figure, the anti-backflow method includes:

[0166] S301: Obtain the current flow direction in the power output branch of each photovoltaic power generation unit;

[0167] S302: When the current flow direction in the power output branch of any photovoltaic power generation unit is opposite to the normal flow direction, a shutdown instruction is generated and issued to the main control module in the anti-backflow device connected to the photovoltaic power generation unit to control the electronic switch module in the anti-backflow device connected to the photovoltaic power generation unit to disconnect;

[0168] S303: starting timing after the shutdown instruction is issued to obtain a second duration;

[0169] S304: When the second duration reaches the second threshold time, an opening instruction is issued to the main control module to control the electronic switch module to close, and return to the step of obtaining the current flow direction in the power output branch of each photovoltaic power generation unit.

[0170] In this way, the system platform can monitor the current flow direction of each photovoltaic power generation unit in real time during the operation phase, and can send shutdown or closing instructions to each anti-backflow device through the communication base station, ultimately achieving rapid shutdown or closing of a single photovoltaic power generation unit, and realizing full automatic control of current detection, backflow blocking and automatic recovery without human intervention, greatly reducing the maintenance cost of the power station.

[0171] The following describes the device, electronic device, storage medium, etc. used to execute the anti-backflow method provided in this application. The specific implementation process and technical effects are described above and will not be repeated below.

[0172] The embodiment of the present application also provides a main control device, Figure 8 The schematic diagram of the principle block diagram of a specific example of the main control device in the embodiment of the present application is shown. As shown in the figure, the main control device includes:

[0173] The first processing module 201 is used to control the electronic switch module of the anti-backflow device to close during the operation process in which a single photovoltaic power generation unit is connected in parallel between the first power terminal connection line and the GND ground line on the grid side of the inverter through the anti-backflow device;

[0174] The second processing module 202 is used to obtain the current flow direction in the power output branch of a single photovoltaic power generation unit;

[0175] A third processing module 203 is used to control the electronic switch module to disconnect when the current flow direction is opposite to the normal flow direction, so as to cut off the connection between the single photovoltaic power generation unit and the grid side of the inverter;

[0176] A fourth processing module 204, configured to start timing when the electronic switch module is disconnected to obtain a first duration;

[0177] The fifth processing module 205 is used to reacquire the current flow direction when the first duration reaches a first threshold time, and when the reacquired current flow direction is the same as the normal flow direction, control the electronic switch module to remain closed; when the reacquired current flow direction is opposite to the normal flow direction, return to the third processing module 203.

[0178] The embodiment of the present application also provides a system platform device, Fig. 9 A schematic diagram of a principle block diagram of a specific example of a system platform device in an embodiment of the present application is shown. As shown in the figure, the system platform device includes:

[0179] The sixth processing module 301 is used to obtain the current flow direction in the power output branch of each photovoltaic power generation unit;

[0180] The seventh processing module 302 is used to generate and issue a shutdown instruction to the main control module in the anti-backflow device connected to any photovoltaic power generation unit when the current flow direction in the power output branch of any photovoltaic power generation unit is opposite to the normal flow direction, so as to control the electronic switch module in the anti-backflow device connected to the photovoltaic power generation unit to disconnect;

[0181] An eighth processing module 303, configured to start timing after the shutdown instruction is issued to obtain a second duration;

[0182] The ninth processing module 304 is configured to send an opening instruction to the main control module to control the electronic switch module to close when the second duration reaches the second threshold time, and return to the sixth processing module 301 .

[0183] It should be understood that the division of the units or modules in the above devices is only a division of logical functions, and in actual implementation, they can be fully or partially integrated into one physical entity, or they can be physically separated. In addition, the units or modules in the device can be implemented in the form of a processor calling software: for example, the device includes a processor, the processor is connected to a memory, the memory stores instructions, and the processor calls the instructions stored in the memory to implement any of the above methods or implement the functions of the units or modules of the above devices.

[0184] The present application also provides a main control device, the main control device comprising:

[0185] a memory storing instructions; and

[0186] A processor is configured to execute the instructions to implement the above-mentioned backflow prevention method.

[0187] The embodiment of the present application further provides a system platform device, the system platform device comprising:

[0188] a memory storing instructions; and

[0189] A processor is configured to execute the instructions to implement the above-mentioned backflow prevention method.

[0190] Fig.10A structural schematic diagram of a specific example of a main control device or a system platform device in an embodiment of the present application is shown. As shown in the figure, the main control device or the system platform device may include a processor, a memory, a network interface, a display, and an input device connected via a system bus. Among them, the processor can be used to provide computing and control capabilities. The memory may include a non-volatile storage medium and an internal memory. The non-volatile storage medium may store an operating system and a computer program. The internal memory may provide an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The network interface may be used to communicate with an external terminal via a network connection. The display may be a liquid crystal display or an electronic ink display. The input device may be a touch layer covered on the display, or a button, a trackball or a touchpad provided on the housing of the main control device or the system platform device, or an external keyboard, touchpad or mouse, etc.

[0191] Those skilled in the art will understand that Fig.10 The structure shown in the figure is only a block diagram of a part of the structure related to the scheme of the present application, and does not constitute a limitation on the main control device or system platform device to which the scheme of the present application is applied. The specific main control device or system platform device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0192] An embodiment of the present application also provides a storage medium, in which a computer program is stored. When the computer program is executed, it can implement the above-mentioned anti-backflow method applied to the main control device or the above-mentioned anti-backflow method applied to the system platform device.

[0193] The computer program may also be used in Fig.10 The memory of the main control device or system platform device contains the above-mentioned program modules, and the computer program composed of the program modules can realize the functions corresponding to the steps in the anti-backflow method described in the above embodiment when executed.

[0194] The embodiment of the present application also provides a computer program product or a computer program, which includes a computer instruction, and the computer instruction is stored in a computer-readable storage medium. The processor of the main control device or the system platform device reads the computer instruction from the computer-readable storage medium, and the processor executes the computer instruction, so that the main control device or the system platform device executes the anti-backflow method provided in the above various implementations.

[0195] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. Among them, any reference to memory, storage, database or other medium used in the embodiments provided in the present application may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in a variety of forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0196] It should be understood that the above embodiments are exemplary and are not intended to include all possible implementations included in the claims. Various modifications and changes may be made on the basis of the above embodiments without departing from the scope of the present disclosure. Similarly, the various technical features of the above embodiments may be arbitrarily combined to form other embodiments of the present application that may not be explicitly described. Therefore, the above embodiments only express several implementations of the present application and do not limit the scope of protection of the patent of this application.

Claims

1. A backflow prevention device, characterized in that: The anti-backflow device comprises: An AC / DC conversion power supply module is connected to the grid side of the inverter, and is used to obtain an AC power supply signal from the grid side of the inverter, and convert the AC power supply signal into a DC power supply signal to at least supply power to the main control module; A detection module is connected in series in an electric energy output branch of a single photovoltaic power generation unit, and is used to detect, obtain and output a first flow direction signal containing current flow direction information in the electric energy output branch; the electric energy output branch is connected in parallel to a first power supply terminal connection line on the grid side of the inverter; an electronic switch module, connected in series in the power output branch, for conducting the power output branch so that a single photovoltaic power generation unit outputs power to the grid side of the inverter; or disconnecting the power output branch to cut off the current backflow loop; and A main control module is connected to the AC / DC conversion power supply module to obtain the DC power supply signal; and is respectively connected to the detection module and the electronic switch module to obtain the first flow direction signal to obtain the current flow direction, and control the on and off of the electronic switch module according to the current flow direction.

2. The backflow prevention device according to claim 1, characterized in that: The detection module is used to determine and obtain the first flow direction signal according to the detected signal sampling value in the electric energy output branch.

3. The backflow prevention device according to claim 1, characterized in that: The first signal transmission end of the detection module is connected to the output end of a single photovoltaic power generation unit, the second signal transmission end of the detection module is connected to the first signal end of the electronic switch module, and the detection output end of the detection module is connected to the main control module; The second signal end of the electronic switch module is connected to the first power supply end connection line of the inverter grid side, and the control end of the electronic switch module is connected to the main control module.

4. The backflow prevention device according to claim 1, characterized in that: The electronic switch module includes at least one of the following: an electronic circuit breaker; a relay; a high-voltage MOS tube; and a high-voltage DC contactor.

5. The backflow prevention device according to claim 1, characterized in that: The electronic switch module is configured as a normally open type.

6. The backflow prevention device according to claim 1, characterized in that: The detection module includes a current sensor.

7. The backflow prevention device according to any one of claims 1 to 6, characterized in that: The photovoltaic power generation unit includes a photovoltaic string or a photovoltaic module.

8. A backflow prevention system, characterized in that: The anti-backflow system comprises: At least one backflow prevention device according to any one of claims 1 to 7; and The system platform end is respectively connected to each of the anti-backflow devices for communicating and monitoring the current flow direction in the power output branch of each photovoltaic power generation unit and controlling the on and off of the electronic switch module of each of the anti-backflow devices.

9. The backflow prevention system according to claim 8, characterized in that: The backflow prevention system further includes a communication base station, which is respectively connected to the system platform end and each of the backflow prevention devices for communication data and / or instructions between the system platform end and the backflow prevention devices; The main control module of the anti-backflow device is also used to transmit a second flow direction signal containing current flow direction information in the electric energy output branch to the system platform end; the system platform end is also used to obtain the second flow direction signal to obtain the current flow direction, and generate a control instruction according to the current flow direction to control the on and off of the electronic switch module of the anti-backflow device.

10. A photovoltaic power generation system, characterized in that: The photovoltaic power generation system comprises: At least one power generation circuit connected in parallel between the first power terminal connection line and the GND ground line on the grid side of the inverter; Wherein, each power generation circuit comprises a single photovoltaic power generation unit connected in series and an anti-backflow device as described in any one of claims 1-7.

11. A backflow prevention method, applied to a main control module of a backflow prevention device, characterized in that: The anti-backflow method comprises: During the operation process in which a single photovoltaic power generation unit is connected in parallel between the first power terminal connection line and the GND ground line on the grid side of the inverter through the backflow prevention device, the electronic switch module of the backflow prevention device is controlled to be closed; Obtain the current flow direction in the power output branch of a single photovoltaic power generation unit; When the current flows in the opposite direction to the normal direction, the electronic switch module is controlled to be disconnected to cut off the connection between the single photovoltaic power generation unit and the grid side of the inverter; Starting timing when the electronic switch module is disconnected to obtain a first duration; When the first duration reaches a first threshold time, the current flow direction is reacquired, and when the reacquired current flow direction is the same as the normal flow direction, the electronic switch module is controlled to remain closed; when the reacquired current flow direction is opposite to the normal flow direction, the process returns to the step of controlling the electronic switch module to be disconnected.

12. The backflow prevention method according to claim 11, characterized in that: The anti-backflow method also includes: After the power plant is completed and put into operation, the electronic switch modules of all anti-backflow devices are controlled to close; Obtain the current flow direction in the power output branch of each photovoltaic power generation unit; Reporting the current flow direction to the system platform end; Obtaining a shutdown instruction issued by the system platform end when the current flow direction in any photovoltaic power generation unit power output branch is opposite to the normal flow direction; Under the control of the shutdown instruction, the electronic switch module of the anti-backflow device connected to the photovoltaic power generation unit is controlled to be disconnected; Obtaining an on instruction issued by the system platform end at a second threshold time after issuing the off instruction; Under the control of the start instruction, the electronic switch module is controlled to close to regain the current direction, and returns to the step of reporting the current direction to the system platform end, so that when the current direction is the same as the normal direction, the electronic switch module is controlled to remain closed; when the current direction is opposite to the normal direction, the electronic switch module is controlled to open.

13. A backflow prevention method, applied to a system platform end in a backflow prevention system, characterized in that: The anti-backflow method comprises: Obtain the current flow direction in the power output branch of each photovoltaic power generation unit; When the current flow direction in the power output branch of any photovoltaic power generation unit is opposite to the normal flow direction, a shutdown command is generated and sent to the main control module in the anti-backflow device connected to the photovoltaic power generation unit to control the electronic switch module in the anti-backflow device connected to the photovoltaic power generation unit to disconnect; After the shutdown instruction is issued, start timing to obtain a second duration; When the second duration reaches the second threshold time, an opening instruction is sent to the main control module to control the electronic switch module to close, and return to the step of obtaining the current flow direction in the power output branch of each photovoltaic power generation unit.

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