Switch type anti-reflux device

Abstract

The utility model provides a switch type anti-reflux device. The device comprises a control unit, a plurality of photovoltaic modules, a plurality of branch switches, a voltage and current acquisition unit, a switch state detection unit, a plurality of switch state control units, a power grid side and an electricity load, the control unit is connected with the voltage and current acquisition unit, the on-off state detection unit and the on-off state control unit; the plurality of photovoltaic modules are connected with the plurality of branch switches in a one-to-one correspondence manner, and the branch switches are connected between the corresponding photovoltaic modules and the electricity loads; the on-off state detection unit and the on-off state control unit are connected with the plurality of branch switches; the plurality of switch state control units are connected with the plurality of branch switches in a one-to-one correspondence manner; the voltage and current acquisition unit is connected between a power grid side and an electricity load. According to the embodiment of the invention, the method achieves the fine adjustment of the power generation power, and improves the utilization rate of photovoltaic power generation resources.

Description

Technical Field

[0001] The present application relates to the field of distributed photovoltaic power generation new energy technology, and in particular to a switch type backflow prevention device. Background Art

[0002] The distributed photovoltaic grid-connected power supply system is connected to the public power grid distribution system at the same time. In view of the special requirements for load change control, the power supply department needs to ensure the quality and reliability of power supply to users. At the same time, the operation of the distributed photovoltaic grid-connected power supply system cannot affect the safety of the distribution system. Therefore, at present, when the quota of distributed photovoltaic power generation exceeds a certain proportion, the distributed photovoltaic power source is not allowed to reverse power to the power system, that is, the phenomenon of grid-connected reverse power is not allowed.

[0003] However, in the prior art, a main circuit breaker is set on the photovoltaic side and the grid side, and the grid-connected reverse power problem is solved by a "one-size-fits-all" method of controlling the opening and closing of the main circuit breaker. That is, when the grid-connected reverse power phenomenon is detected, the main switch of the main circuit breaker is turned off. At this time, all photovoltaic power generation cannot be used, resulting in a waste of photovoltaic power generation resources. The control method is relatively simple and crude. This control method is difficult to finely adjust and disconnect the power of photovoltaic power generation to solve the grid-connected reverse power problem. Utility Model Content

[0004] The present application provides a switch type backflow prevention device to solve the problems mentioned in the above background technology.

[0005] The present application provides a switch type backflow prevention device, comprising: a control unit, a plurality of photovoltaic modules, a plurality of branch switches, a voltage and current acquisition unit, a switch state detection unit, a plurality of switch state control units, a grid side, and a power load;

[0006] The control unit is respectively connected to the voltage and current acquisition unit, the switch state detection unit, and the switch state control unit;

[0007] The plurality of photovoltaic components are connected to the plurality of branch switches in a one-to-one correspondence, and the branch switches are connected between the corresponding photovoltaic components and the power loads;

[0008] The switch state detection unit said multiple branch switches are connected;

[0009] The multiple switch state control units are connected to the multiple branch switches in a one-to-one correspondence;

[0010] The voltage and current acquisition unit is connected between the power grid side and the power load.

[0011] Optionally, a control main switch, a main switch state detection unit and a main switch state control unit, wherein the main switch state detection unit and the main switch state control unit are respectively connected to the control main switch, one end of the control main switch is connected to the grid side, and the other end of the control main switch is connected to the multiple branch switches;

[0012] The main switch state control unit and the main switch state detection unit are connected to the control unit respectively.

[0013] Optionally, the switch type backflow prevention device further comprises: a display screen and a button, the display screen is connected to the button and the control unit, and the button is connected to the control unit.

[0014] Optionally, the switch-type backflow prevention device further includes: an inverter, wherein the inverter is connected between the photovoltaic component and the corresponding branch switch.

[0015] Optionally, the switch-type backflow prevention device further comprises: a grid-connected switch, the grid-connected switch being connected between the grid side and the power load, and the grid-connected switch being connected to the control unit;

[0016] The voltage and current acquisition unit is connected between the grid-connected switch and the power load.

[0017] Optionally, the control unit is connected to the voltage and current acquisition unit, the switch state detection unit, and the switch state control unit via a communication line.

[0018] Optionally, the voltage and current acquisition unit includes: a current transformer and a voltage transformer;

[0019] The current transformer and the voltage transformer are both connected to the control unit.

[0020] Optionally, the switch state control unit includes: an optocoupler switch and a relay, the branch switch includes a circuit breaker, one end of the optocoupler switch is connected to the control unit, the other end of the optocoupler switch is connected to one end of the relay, and the other end of the relay is connected to the circuit breaker;

[0021] The circuit breaker is connected between the corresponding photovoltaic assembly and the power load.

[0022] In this embodiment, the switch type anti-backflow device includes: a control unit, multiple photovoltaic modules, multiple branch switches, a voltage and current acquisition unit, a switch state detection unit, multiple switch state control units, a power grid side, and an electrical load; the control unit is connected to the voltage and current acquisition unit, the switch state detection unit, and the switch state control unit; multiple photovoltaic modules are connected to multiple branch switches in a one-to-one correspondence; the switch state detection unit and the switch state control unit are both connected to multiple branch switches; the voltage and current acquisition unit is connected between the power grid side and the electrical load. Compared with the prior art, the present application uses multiple branch switches, a voltage and current acquisition unit, a switch state detection unit, and a switch state control unit. When a grid-connected reverse power problem occurs, the branch switches are closed one by one, instead of directly closing the main switch of the main circuit breaker after detecting the grid-connected reverse power phenomenon, thereby realizing fine adjustment of the power generation power, improving the utilization rate of photovoltaic power generation resources, and avoiding the reverse power problem from affecting the equipment used on the grid side, making the grid side more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 A schematic diagram of the structure of a switch type backflow prevention device provided in one embodiment of the present application;

[0025] Figure 2 A schematic structural diagram of a switch type backflow prevention device provided in another embodiment of the present application;

[0026] Figure 3 A logic diagram of a switch type backflow prevention device provided in one embodiment of the present application;

[0027] Figure 4 A schematic diagram of the structure of an optical coupler switch provided in an embodiment of the present application

[0028] In the figure: 1-control unit; 2-photovoltaic module; 3-branch switch; 4-voltage and current acquisition unit; 5-switch state detection unit; 6-switch state control unit; 7-grid side; 8-power load; 9-control main switch; 10-human-machine interaction device; 11-relay; 12-inverter; 13-optical coupler switch; 14-grid switch; 15-main switch state control unit; 16-main switch state detection unit; 17-circuit breaker. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application is clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work also fall within the scope of protection of the present application.

[0030] Figure 1 This is a switch type anti-backflow device according to an embodiment of the present application. Figure 1 As shown, it includes: a control unit 1, multiple photovoltaic modules 2, multiple branch switches 3, a voltage and current acquisition unit 4, a switch state detection unit 5, multiple switch state control units 6, a grid side 7, and an electrical load 8;

[0031] The control unit 1 is connected to the voltage and current acquisition unit 4, the switch state detection unit 5, and the switch state control unit 6 respectively;

[0032] A plurality of photovoltaic modules 2 are connected to a plurality of branch switches 3 in a one-to-one correspondence, and the branch switches 3 are connected between the corresponding photovoltaic modules 2 and the power load 8;

[0033] The switch state detection unit 5 is connected to the plurality of branch switches 3 respectively;

[0034] A plurality of switch state control units 6 are connected to a plurality of branch switches 3 in a one-to-one correspondence;

[0035] The voltage and current acquisition unit 4 is connected between the grid side 7 and the electrical load 8 .

[0036] Among them, the control unit 1 can be, for example, a micro control unit 1 (Micro Control Unit, MCU), and the control unit 1 is connected to the voltage and current acquisition unit 4, and is used to receive the voltage and current between the current grid side and the power load 8 detected by the voltage and current acquisition unit 4, and calculate the power corresponding to the current voltage and current, wherein the voltage and current between the current grid side 7 and the power load 8 detected by the voltage and current acquisition unit 4 include a value and a direction. When the voltage and current are detected to be positive values, it means that the grid side 7 provides electrical energy to the power load 8, and the corresponding power is positive power, that is, the power described below; when the voltage and current are detected to be negative values, it means that the power generation power of the photovoltaic component 2 is greater than the power required by the power load 8. At this time, the excess electrical energy flows to the grid side 7, and the corresponding power is reverse power.

[0037] The control unit 1 is connected to the switch state detection unit 5 and is used to obtain the current switch state of each branch switch 3 detected by the switch state detection unit 5 .

[0038] The control unit 1 is connected to the switch state control unit 6 and is used to control the on and off of the corresponding branch switch 3 through the switch state control unit 6 .

[0039] Among them, the switch state detection unit 5 can be a voltage sensor or a current sensor. When the switch state detection unit 5 is a voltage sensor, when the voltage in the voltage sensor detection circuit is greater than the first preset voltage value, the branch switch 3 is in a closed state, and the switch state detection unit 5 transmits the detection result to the control unit 1. When the voltage in the voltage sensor detection circuit is less than the second preset voltage value, the branch switch 3 is in an open state, and the switch state detection unit 5 transmits the detection result to the control unit 1. Furthermore, the first preset voltage value is greater than the second preset voltage value.

[0040] When the switch state detection unit 5 is a current sensor, when the current in the current sensor detection circuit is greater than the first preset current value, the branch switch 3 is in a closed state, and the switch state detection unit 5 transmits the detection result to the control unit 1; when the current in the current sensor detection circuit is less than the second preset current value, the branch switch 3 is in an open state, and the switch state detection unit 5 transmits the detection result to the control unit 1; further, the first preset current value is greater than the second preset current value.

[0041] Among them, the photovoltaic component 2 is used to provide the electricity required by the electrical load 8. The photovoltaic component 2 is generally set under the sun. When light shines on the metal of the photovoltaic component 2, the energy of the light is completely absorbed by the electrons in the metal. When the energy absorbed by the electrons is large enough, they can overcome the internal gravity of the metal to do work, leave the metal surface and escape, thus becoming photoelectrons, that is, the photovoltaic component 2 generates electrical energy.

[0042] Among them, the branch switch 3 is connected between the power load 8 and the photovoltaic component 2, and is used to control the on and off between the corresponding photovoltaic component 2 and the power load 8, so as to control whether the photovoltaic component 2 provides power to the power load 8, thereby solving the problem of reverse power.

[0043] Furthermore, each branch switch 3 is connected to a corresponding photovoltaic module 2 , so that each branch switch 3 controls a photovoltaic module 2 , thereby achieving refined adjustment and control of the photovoltaic module 2 .

[0044] In addition, the number of photovoltaic modules 2 is set according to the needs of the work site, and the number of branch switches 3 is set according to the number of photovoltaic modules 2 .

[0045] The use process of the above switch type backflow prevention device is as follows:

[0046] During the operation of the photovoltaic module 2, the grid side 7 and the power load 8, the voltage and current acquisition unit 4 detects the current and voltage between the current grid side 7 and the power load 8 in real time, and uploads the detection result to the control unit 1 in real time. The control unit 1 calculates the power corresponding to the current voltage and current, and determines whether there is a reverse power situation at present.

[0047] When the control unit 1 determines that there is a reverse power situation, the control unit 1 detects whether the time when the reverse power situation occurs exceeds the preset time. When the reverse power exceeds the preset time, the control unit 1 obtains the current state of each branch switch 3, such as open or closed, through the switch state detection unit 5. After the control unit 1 obtains the current state of each branch switch 3, the control unit 1 determines the branch switch 3 that is currently in the closed state, and sends a disconnection control instruction to a corresponding switch state control unit 6 of one of the branch switches 3 that is currently in the closed state. The switch state control unit 6 controls the corresponding branch switch 3 to be opened according to the disconnection control instruction.

[0048] At this time, the electric energy provided by the photovoltaic module 2 is reduced, resulting in changes in the current and voltage between the grid side 7 and the power load 8. Then, the voltage and current acquisition unit 4 continues to upload the current and voltage between the grid side 7 and the power load 8 detected in real time to the control unit 1. When the control unit 1 determines that there is still a reverse power situation, one of the branch switches 3 that is currently in a closed state is disconnected in the above manner until there is no reverse power situation or all branch switches 3 are in an open state.

[0049] When the control unit 1 determines that there is power consumption between the grid side 7 and the power load 8 and the power consumption exceeds the predetermined range, it is necessary to increase the power provided by the photovoltaic assembly 2 to the power load 8. The control unit 1 obtains the current state of each branch switch 3 through the switch state detection unit 5, and determines the branch switch 3 that is currently in the disconnected state. The control unit 1 sends a closing control instruction to a corresponding switch state control unit 6 of one of the branch switches 3 that is currently in the disconnected state, and the switch state control unit 6 controls the corresponding branch switch 3 to close according to the closing control instruction.

[0050] At this time, the electric energy provided by the photovoltaic module 2 increases, resulting in changes in the current and voltage between the grid side 7 and the power load 8. When the control unit 1 determines that there is still power consumption and the power consumption exceeds the predetermined range, one of the branch switches 3 that is currently in the closed state is closed in the above manner until there is no power consumption and the power consumption exceeds the predetermined range or all the branch switches 3 are in the closed state.

[0051] In this embodiment, the switch type reverse current prevention device includes: a control unit 1, a plurality of photovoltaic modules 2, a plurality of branch switches 3, a voltage and current acquisition unit 4, a switch state detection unit 5, a plurality of switch state control units 6, a grid side 7, and an electrical load 8; the control unit 1 is connected to the voltage and current acquisition unit 4, the switch state detection unit 5, and the switch state control unit 6; a plurality of photovoltaic modules 2 are connected to a plurality of branch switches 3 in a one-to-one correspondence; the switch state detection unit 5 and the switch state control unit 6 are both connected to a plurality of branch switches 3; the voltage and current acquisition unit 4 is connected between the grid side 7 and the electrical load 8. Compared with the prior art, the present application uses a plurality of branch switches 3, a voltage and current acquisition unit 4, a switch state detection unit 5, and a switch state control unit 6, and when a grid reverse power problem occurs, the branch switches 3 are closed one by one, instead of directly closing the main switch of the main circuit breaker after detecting the grid reverse power phenomenon, thereby realizing fine adjustment of the power generation, improving the utilization rate of photovoltaic power generation resources, and avoiding the generation of reverse power problems that affect the equipment used on the grid side 7, making the grid side 7 more stable.

[0052] Alternatively, if Figure 2 and Figure 3 As shown, the switch type backflow prevention device also includes: a control main switch 9, a main switch state detection unit 16 and a main switch state control unit 15, the main switch state detection unit 16 and the main switch state control unit 15 are respectively connected to the control main switch 9, one end of the control main switch 9 is connected to the grid side 7, and the other end of the control main switch 9 is connected to multiple branch switches 3;

[0053] The main switch state control unit 15 and the main switch state detection unit 16 are connected to the control unit 1 respectively.

[0054] Among them, the main switch 9 is controlled to be in a normally closed state. When the control unit 1 detects the existence of a reverse power situation and the switch state detection unit 5 detects that all branch switches 3 are disconnected, and the reverse power situation occurs for more than a preset time, and the control unit 1 detects that the main switch 9 is controlled to be in a closed state through the main switch state detection unit 16, the control unit 1 sends a disconnect control instruction to the main switch state control unit 15, and the main switch state control unit 15 controls the main switch 9 to be disconnected, thereby alleviating the reverse power situation.

[0055] When the power consumption exceeds the set range and the control unit 1 detects that the main switch 9 is in the disconnected state through the main switch state detection unit 16, the control unit 1 sends a closing control instruction to the main switch state control unit 15, and the main switch state control unit 15 controls the main switch 9 to close again, thereby providing the power generation power of the photovoltaic component 2 to the power load 8.

[0056] In addition, in actual working process, there is rarely a situation where the main control switch 9 needs to be disconnected.

[0057] Alternatively, if Figure 3 As shown, the switch type backflow prevention device further includes: a human-machine interaction device 10 , which is connected to the control unit 1 .

[0058] Among them, the human-machine interaction device 10 is a display screen and a keyboard, a touch screen, etc., wherein, when the human-machine interaction device 10 is a display screen and a keyboard, the display screen is connected to the keyboard, and both are connected to the control unit 1. The control unit 1 uploads the received current voltage and current, the power corresponding to the current voltage and current, the switch state of each branch switch 3, and the switch state of the control main switch 9 to the display screen of the human-machine interaction device 10 for display, so that the staff can intuitively understand the current switch state of each switch. The keyboard of the human-machine interaction device 10 is used to input data such as preset time and preset range. For example, the preset time is 1s, and the preset range is that the power consumption is 90% of the photovoltaic power generation power, and it is displayed on the display screen of the human-machine interaction device 10, which is convenient for the staff to operate.

[0059] When the human-computer interaction device 10 is a touch screen, the touch screen integrates the functions of a display screen and buttons, which will not be described in detail here.

[0060] Alternatively, if Figure 2 As shown, the switch type backflow prevention device further includes an inverter 12 , which is connected between the photovoltaic assembly 2 and the corresponding branch switch 3 .

[0061] The inverter 12 is used to control the output power of the photovoltaic module 2 to prevent excessive output power from damaging the circuit and affecting the service life of other equipment, such as the branch switch 3 .

[0062] Alternatively, if Figure 2 As shown, the switch type backflow prevention device further includes a grid-connected switch 14, the grid-connected switch 14 is connected between the grid side 7 and the power load 8, and the grid-connected switch 14 is connected to the control unit 1;

[0063] The voltage and current acquisition unit 4 is connected between the grid-connected switch 14 and the electrical load 8 .

[0064] The grid-connected switch 14 is a normally closed switch. In actual operation, the grid-connected switch 14 is generally not disconnected. When the device fails and needs to be stopped, the control unit 1 controls the grid-connected switch 14 to close to prevent the grid side 7 from continuing to supply power.

[0065] Among them, the voltage and current acquisition unit 4 is connected between the grid-connected switch 14 and the power load 8, and is used to collect the values ​​and flow directions of the voltage and current on the grid side 7, and upload them to the control unit 1. The control unit 1 calculates the corresponding power. Furthermore, the positive direction of the current and voltage is from the grid side 7 to the power load 8, and the reverse direction of the voltage and current is from the photovoltaic module 2 to the grid side 7.

[0066] Optionally, the control unit 1 is connected to the voltage and current acquisition unit 4 , the switch state detection unit 5 , and the switch state control unit 6 via a communication line.

[0067] Among them, the communication circuit is an RS485 communication cable, which is used to connect the control unit 1 with the voltage and current acquisition unit 4, the switch state detection unit 5, and the switch state control unit 6 respectively, to improve the signal transmission rate between the control unit 1 and other units and prevent other electromagnetic interference from causing transmission signal errors.

[0068] Optionally, the voltage and current acquisition unit 4 includes a current transformer and a voltage transformer.

[0069] Among them, the current transformer is used to detect the direction of the current between the current grid side 7 and the power load 8, and to detect the magnitude of the current. When the direction of the current is from the grid side 7 to the power load 8, the current is positive, and when the direction of the current is from the photovoltaic component 2 to the grid side 7, the current is negative.

[0070] Among them, the voltage transformer is used to detect the direction of the current voltage between the grid side 7 and the power load 8, and to detect the magnitude of the current voltage. When the direction of the voltage is from the grid side 7 to the power load 8, the voltage is a positive number, and when the direction of the voltage is from the photovoltaic module 2 to the grid side 7, the voltage is a negative number.

[0071] Alternatively, if Figure 2 and Figure 4 As shown, the switch state control unit 6 includes: an optical coupler switch 13 and a relay 11, the branch switch 3 includes a circuit breaker 17, one end of the optical coupler switch 13 is connected to the control unit 1, the other end of the optical coupler switch 13 is connected to one end of the relay 11, and the other end of the relay 11 is connected to the circuit breaker 17;

[0072] The circuit breaker 17 is connected between the corresponding photovoltaic assembly 2 and the electrical load 8 .

[0073] Among them, the switch state control unit 6 is configured to be composed of an optocoupler switch 13 and a relay 11, and the optocoupler switch 13 is connected to the control unit 1. When the optocoupler switch 13 receives the disconnection control instruction or the closing control instruction sent by the control unit 1, the optocoupler switch 13 is opened or closed accordingly according to the control instruction. When the optocoupler switch 13 is disconnected, the coil of the relay 11 is energized so that the contacts of the relay 11 are disconnected. When the contacts of the relay 11 are disconnected, the circuit breaker 17 is disconnected, and the photovoltaic component 2 connected to the current circuit breaker 17 stops providing electrical energy to the electrical load 8. When the optocoupler switch 13 is closed, the coil of the relay 11 is energized so that the contacts of the relay 11 are closed. When the contacts of the relay 11 are closed, the circuit breaker 17 is closed, and the photovoltaic component 2 connected to the current circuit breaker 17 provides electrical energy to the electrical load 8.

[0074] By controlling the light-emitting diode in the optocoupler switch 13 to light up and turn off, the switch is controlled to close and open. The optocoupler switch 13 is used to isolate the control signal, protect the circuit, prevent the circuit from being affected by excessive voltage or current, and improve the safety of the system.

[0075] Furthermore, the optocoupler switch 13 includes a light-emitting diode and a phototransistor. When the control unit 1 controls the voltage of the light-emitting diode in the optocoupler switch 13, when the voltage meets the light-emitting voltage of the light-emitting diode in the optocoupler switch 13, the light-emitting diode emits light, and the phototransistor at the other end is turned on. At this time, the coil of the relay 11 is energized, the contacts of the relay 11 are closed, and the circuit breaker 17 is closed. When the control unit 1 controls the voltage of the light-emitting diode in the optocoupler switch 13, when the voltage is lower than the light-emitting voltage of the light-emitting diode in the optocoupler switch 13, the light-emitting diode does not emit light, and the phototransistor at the other end is disconnected. At this time, the coil of the relay 11 loses power, the contacts of the relay 11 are disconnected, and the circuit breaker 17 is disconnected.

[0076] In the present application, the structure of the main switch state detection unit 16 refers to the structure of the switch state detection unit 5 and will not be repeated here.

[0077] In the present application, the structure of the main switch state control unit 15 refers to the structure of the switch state control unit 6 , which will not be described in detail here. Correspondingly, the control main switch 9 may also be a circuit breaker 17 .

[0078] Finally, it should be noted that all contents not described in the technical solution of this application can be implemented using existing technologies. In addition, the above embodiments are only used to illustrate the technical solution of this application, rather than to limit it; although the application is described in detail with reference to the above embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the above embodiments, or replace some or all of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A switch type backflow prevention device, characterized in that: include: Control unit, multiple photovoltaic modules, multiple branch switches, voltage and current acquisition unit, switch state detection unit, multiple switch state control units, grid side, power load; The control unit is respectively connected to the voltage and current acquisition unit, the switch state detection unit, and the switch state control unit; The plurality of photovoltaic components are connected to the plurality of branch switches in a one-to-one correspondence, and the branch switches are connected between the corresponding photovoltaic components and the power loads; The switch state detection unit is connected to the plurality of branch switches; The multiple switch state control units are connected to the multiple branch switches in a one-to-one correspondence; The voltage and current acquisition unit is connected between the power grid side and the power load.

2. The switch type backflow prevention device according to claim 1, characterized in that: Also includes: A control main switch, a main switch state detection unit and a main switch state control unit, wherein the main switch state detection unit and the main switch state control unit are respectively connected to the control main switch, one end of the control main switch is connected to the grid side, and the other end of the control main switch is connected to the multiple branch switches; The main switch state control unit and the main switch state detection unit are connected to the control unit respectively.

3. The switch type backflow prevention device according to claim 1, characterized in that: It also includes a human-computer interaction device, which is connected to the control unit.

4. The switch type backflow prevention device according to claim 1, characterized in that: An inverter is also included, and the inverter is connected between the photovoltaic assembly and the corresponding branch switch.

5. The switch type backflow prevention device according to claim 1, characterized in that: It also includes a grid-connected switch, which is connected between the grid side and the power load, and the grid-connected switch is connected to the control unit; The voltage and current acquisition unit is connected between the grid-connected switch and the power load.

6. The switch type backflow prevention device according to claim 1, characterized in that: The control unit is connected to the voltage and current acquisition unit, the switch state detection unit, and the switch state control unit via a communication line.

7. The switch type backflow prevention device according to any one of claims 1 to 6, characterized in that: The voltage and current acquisition unit includes: a current transformer and a voltage transformer; The current transformer and the voltage transformer are both connected to the control unit.

8. The switch type backflow prevention device according to any one of claims 1 to 6, characterized in that: The switch state control unit includes: an optocoupler switch and a relay, the branch switch includes a circuit breaker, one end of the optocoupler switch is connected to the control unit, the other end of the optocoupler switch is connected to one end of the relay, and the other end of the relay is connected to the circuit breaker; The circuit breaker is connected between the corresponding photovoltaic assembly and the power load.

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