A grid-connected and off-grid switching device, a photovoltaic storage system, and a grid-connected and off-grid switching method

Abstract

The present application relates to the field of inverter technology, and in particular to an on-grid and off-grid switching device, a photovoltaic storage system and an on-grid and off-grid switching method. The on-grid and off-grid switching device includes a protection module and an inverter module. The output port of the inverter module is used to connect to a load to supply power to the load, and the output port of the inverter module is also used to connect to a power grid; the protection module is connected to the inverter module and to the power grid, and is used to control the inverter module to be in a on-grid mode when a first condition is detected, and to control the inverter module to be in an off-grid mode when a second condition is detected. The present application solves the problems of a single switching strategy, a large influence of mains power and a complex system structure in an inverter on-grid and off-grid switching device, and realizes automatic identification of whether the power grid is abnormal and switching to an on-grid and off-grid mode, thereby protecting the photovoltaic storage system and the load.

Description

Technical Field

[0001] The present application relates to the technical field of inverters, and in particular to a grid-connected and off-grid switching device, a photovoltaic storage system, and a grid-connected and off-grid switching method. Background Art

[0002] At present, the known photovoltaic energy storage power generation system can be divided into off-grid power generation system and grid-connected power generation system according to the different operation modes of the system. Photovoltaic grid-connected inverter is used to convert the direct current generated by solar panels into alternating current and directly transmit it to the power grid or supply the load, that is, the output end of the inverter will be directly or through a transformer and electrically connected to the power grid and the load. Photovoltaic energy storage power generation system is generally composed of photovoltaic cells, grid-connected inverters and public distribution networks.

[0003] The photovoltaic storage system and the power grid are connected through a grid-connected inverter to achieve two modes: grid-connected and off-grid. When the power grid fails or blackouts, or in some remote areas where the power grid is unstable or the cost of electricity is high, in order to enhance energy independence and protect equipment safety, the inverter needs to be switched to an off-grid state to ensure that the connected loads can continue to receive power supply. When the existing photovoltaic storage system detects an abnormality in the power grid, the inverter switches to off-grid mode. At this time, the load carried by the inverter continues to be used without being affected, while the load carried by the grid will stop working due to the influence of the mains, causing the load carried by the photovoltaic storage system to be unable to work normally.

[0004] The inverter on-grid and off-grid switching device of the existing photovoltaic storage system has the problems of single switching strategy, great influence by the mains power and complex system structure. Summary of the invention

[0005] In view of this, the embodiments of the present application provide an on-grid / off-grid switching device, a device, a photovoltaic storage system and an on-grid / off-grid switching method, aiming to solve the problems of the inverter on-grid / off-grid switching device having a single switching strategy, being greatly affected by the mains power and having a complex system structure, and to realize automatic identification of whether the power grid is abnormal and switching the on-grid / off-grid mode, so as to protect the photovoltaic storage system and the load.

[0006] A first aspect of an embodiment of the present application provides a grid-connected and off-grid switching device, comprising:

[0007] An inverter module, wherein an output port of the inverter module is used to connect to a load to supply power to the load, and the output port of the inverter module is also used to connect to a power grid;

[0008] A protection module is connected to the inverter module and to the power grid, and is used to control the inverter module to be in a grid-connected mode when a first condition is detected, and to control the inverter module to be in an off-grid mode when a second condition is detected.

[0009] In one of the embodiments, the protection module includes a switch unit and a control unit;

[0010] The switch unit includes a first sub-switch and a second sub-switch, wherein the first sub-switch is connected to a first phase line of the power grid and is used to control the on or off of the first phase line;

[0011] The second sub-switch is connected to the second phase line of the power grid and is used to control the conduction or disconnection of the second phase line;

[0012] The control unit is connected to the switch unit, and is used to control the switch unit to be turned on or off so as to control the first phase line and the second phase line to be turned on or off.

[0013] In one embodiment, the protection module also includes a detection unit, which is connected to the control unit. The detection unit is used to detect whether the first condition and the second condition are met, and the control unit controls the on or off of the switch unit according to the detection result of the detection unit.

[0014] In one of the embodiments, the control unit is further configured to, under the first condition, control the switch unit to be turned on when the detection unit detects the first sub-condition, and control the switch unit to remain turned on when the detection unit does not detect the first sub-condition;

[0015] Under the second condition, when the detection unit detects the first sub-condition, the switch unit is controlled to be turned off, and when the detection unit does not detect the first sub-condition, the switch unit is controlled to remain turned off.

[0016] In one of the embodiments, the protection module further includes a communication module, and the communication module is used for communication between the protection module and the inverter module;

[0017] When the first condition is met and the communication is abnormal, the control unit controls the switch unit to turn off when the detection unit detects the first sub-condition, and the control unit controls the switch unit to turn on and stop the inverter module from supplying power to the load when the detection unit does not detect the first sub-condition;

[0018] When the second condition is met and the communication is normal, the control unit controls the switch unit to remain turned off.

[0019] In one of the embodiments, the first condition indicates that the power grid is normal, and the second condition indicates that the power grid is abnormal;

[0020] The first sub-condition indicates that the subsequent stage of the protection module has an output, and the subsequent stage is a side of the switch unit connected to the inverter module.

[0021] In one embodiment, the switch unit is a magnetic latching relay, a control coil of the magnetic latching relay is connected to the control unit, and the magnetic latching relay has a first contact, a second contact, a third contact, and a fourth contact;

[0022] The first contact is connected to the first phase line, the second contact is connected to a first output port of the inverter module, the third contact is connected to the second phase line, and the fourth contact is connected to a second output port of the inverter module.

[0023] In one of the embodiments, the power grid is a broken-phase power grid.

[0024] The second aspect of the embodiment of the present application provides a photovoltaic storage system, including a photovoltaic component, an energy storage component and the grid-connected and off-grid switching device provided by the first aspect of the embodiment of the present application, wherein the photovoltaic component is used to store the collected solar energy into the energy storage component, and the energy storage component is connected to the inverter module.

[0025] A third aspect of the embodiments of the present application provides a grid-connected and off-grid switching method, which is applied to the grid-connected and off-grid switching device provided in the first aspect of the embodiments of the present application, including:

[0026] When the protection module detects that the power grid is normal, the communication between the inverter module and the protection module is normal, and the subsequent stage of the protection module has output, the protection module turns on the power grid and controls the inverter module to enter the grid-connected mode, and when the subsequent stage of the protection module has no output, the protection module is kept connected to the power grid;

[0027] When the protection module detects that the power grid is abnormal and the communication between the inverter module and the protection module is normal and the subsequent stage of the protection module has output, the protection module disconnects the power grid and controls the inverter module to enter an off-grid mode, and when the subsequent stage of the protection module has no output, the protection module is kept disconnected from the power grid;

[0028] When the protection module detects that the power grid is normal and the communication between the inverter module and the protection module is abnormal and the subsequent stage of the protection module has output, the protection module disconnects the power grid and the inverter module supplies power to the load; and when the subsequent stage of the protection module has no output, the protection module turns on the power grid and controls the inverter module to stop output;

[0029] When the protection module detects that the power grid is abnormal and the communication between the inverter module and the protection module is abnormal, the protection module disconnects the power grid.

[0030] The beneficial effects of the embodiments of the present application are as follows: when the protection module detects the first condition, the inverter module is controlled to work in the grid-connected mode; when the second condition is detected, the inverter module is controlled to work in the off-grid mode. The protection module can automatically identify whether the grid is abnormal and automatically switch the on-grid and off-grid working modes of the inverter module. Under the premise of ensuring the power of the inverter module, the load and the inverter module are not affected by the grid and maintain normal operation, thereby improving the reliability of the on-grid and off-grid switching device and simplifying the structure of the inverter on-grid and off-grid system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0032] Figure 1 A schematic diagram of the principle of an on-grid and off-grid switching device provided in one embodiment of the present application;

[0033] Figure 2 A schematic diagram of the principle of an on-grid and off-grid switching device provided in another embodiment of the present application;

[0034] Figure 3 A schematic diagram of the principle of a switch unit provided in an embodiment of the present application;

[0035] Figure 4 A schematic diagram of a driving circuit of a switch unit provided in an embodiment of the present application;

[0036] Figure 5 A schematic diagram of the internal circuit of an inverter module provided in one embodiment of the present application;

[0037] Figure 6 A schematic diagram of the principles of a photovoltaic storage system provided in one embodiment of the present application. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0039] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0040] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0041] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0042] See also Figure 1 As shown, the embodiment of the present application provides a grid-connected and off-grid switching device 10, which includes a protection module 100 and an inverter module 200. The output port of the inverter module 200 is used to connect to the load to supply power to the load. The output port of the inverter module 200 is also used to connect to the power grid. The protection module 100 is connected to the inverter module 200 and connected to the power grid. The protection module 100 is used to control the inverter module 200 to be in the grid-connected mode when a first condition is detected. When the protection module 100 detects a second condition, the inverter module 200 is controlled to be in the off-grid mode. It can be understood that when the inverter module 200 is in the grid-connected mode, the load is powered by the power grid and the inverter module 200, and the load is mainly powered by the inverter module 200. When the inverter module 200 is in the off-grid mode, the load is powered by the inverter module 200. Among them, the output port of the inverter module 200 includes a first output port GRIDL and a second output port GRIDN.

[0043] The on-grid and off-grid switching device 10 provided in the first aspect of the embodiment of the present application controls the inverter module 200 to work in the on-grid mode when the protection module 100 detects the first condition, and controls the inverter module 200 to work in the off-grid mode when the second condition is detected. The protection module 100 can automatically identify whether the power grid is abnormal and automatically switch the on-grid and off-grid working mode of the inverter module 200. Under the premise of ensuring the power of the inverter module 200, the load and the inverter module 200 are not affected by the power grid and maintain normal operation, thereby improving the reliability of the on-grid and off-grid switching device 10 and simplifying the structure of the inverter on-grid and off-grid system.

[0044] See also Figure 2 In one embodiment, the protection module 100 includes a switch unit 110 and a control unit 130. The switch unit 110 includes a first sub-switch K1 and a second sub-switch K2. The first sub-switch K1 is connected to the first phase line L1 of the power grid and is used to control the conduction or disconnection of the first phase line L1. The second sub-switch K2 is connected to the second phase line L2 of the power grid and is used to control the conduction or disconnection of the second phase line L2. The control unit 130 is connected to the switch unit 110, and the control unit 130 is used to control the conduction or disconnection of the switch unit 110 to control the conduction or disconnection of the first phase line L1 and the second phase line L2. It can be understood that, under normal circumstances, the conduction and disconnection actions of the first sub-switch K1 and the second sub-switch K2 are synchronized, that is, the two are in the conduction state or the off state at the same time.

[0045] In some possible embodiments, the first sub-switch K1 and the second sub-switch K2 may be commonly used switch forms in power systems, such as air switches, circuit breakers, relay switches, etc. Preferably, the first sub-switch K1 and the second sub-switch K2 are relay switches.

[0046] See also Figure 2 In one embodiment, the protection module 100 also includes a detection unit 120, which is connected to a control unit 130. The detection unit 120 is used to detect whether the first condition and the second condition are met. The control unit 130 controls the on or off of the switch unit 110 according to the detection result of the detection unit 120.

[0047] See also Figure 2 In one embodiment, the control unit 130 is also used to control the switch unit 110 to be turned on under the first condition when the detection unit 120 detects the first sub-condition, and to control the switch unit to remain turned on when the detection unit 120 does not detect the first sub-condition.

[0048] Under the second condition, when the detection unit 120 detects the first sub-condition, the switch unit 110 is controlled to be turned off, and when the detection unit 120 does not detect the first sub-condition, the switch unit 110 is controlled to remain turned off.

[0049] The first condition here is, for example, that the power supply of the power grid is normal. When the power supply of the power grid is normal, when the detection unit 120 detects the first sub-condition, the switch 110 is controlled to be turned on. At this time, the power grid can supply power to the load and the inverter module 200 enters the grid-connected mode. When the detection unit 120 does not detect the first sub-condition, the switch unit 110 is still controlled to remain in the on state. When the power grid is normally powered, the grid-connected switching device 10 chooses to be connected to the grid.

[0050] See also Figure 2 , in one embodiment, the loads are multiple.

[0051] See also Figure 2 In one embodiment, the protection module 100 further includes a communication module (not shown in the figure), which is used for communication between the protection module 100 and the inverter module 200. In some embodiments, the communication between the protection module 100 and the inverter module 200 is CAN communication.

[0052] When the first condition is met and the communication is abnormal, the control unit 130 controls the switch unit 110 to turn off when the detection unit 120 detects the first sub-condition. When the detection unit 120 does not detect the first sub-condition, the control unit 130 controls the switch unit 110 to turn on and stops the inverter module 200 from supplying power to the load. When the second condition is met and the communication is normal, the control unit 130 controls the switch unit 110 to remain turned off.

[0053] Here, the first condition is, for example, that the power supply of the power grid is normal. When the power supply of the power grid is normal, there is an abnormality in the communication between the protection module 100 and the inverter module 200, for example, there is an abnormality such as inability to communicate, communication suspension, communication interruption, abnormal communication data, network failure, etc. between the protection module 100 and the inverter module 200. When the detection unit 120 detects the first sub-condition, the switch unit 110 is turned off, and the off-grid switching device 10 is disconnected from the power grid, and the inverter module 200 supplies power to the load. When the detection unit 120 does not detect the first sub-condition, the switch unit 110 is turned on, and the inverter module 200 is stopped from supplying power to the load, that is, the inverter module 200 is not allowed to carry the load. It can be understood that in the embodiment of the present application, the protection module 100 is powered by the inverter module 200.

[0054] When the power supply of the power grid is normal, but the communication between the inverter module 200 and the protection module 100 is abnormal, the working mode of the inverter module 200 and the state of the protection module 100 are determined according to whether the first sub-condition is met. When the first sub-condition is detected, the switch unit 110 is turned off, and the inverter module 200 supplies power to the load, protecting the power safety of the off-grid switching device 10, and ensuring that the load can continue to work without power outage. When the first sub-condition is not detected, the switch unit 110 is turned on, that is, the power grid can supply power to the load. At the same time, since the abnormal communication indicates that the inverter module 200 may have some fault problems, the inverter module 200 is prohibited from outputting, protecting the safety of the inverter module 200 and the load. Further, when the power grid is abnormal and the communication between the inverter module 200 and the protection module 100 is normal, the control unit 130 controls the switch unit 110 to remain turned off. When the power grid is abnormal, the inverter module 200 enters the off-grid mode, and the inverter module 200 carries the load, ensuring that the load can continue to work without power outage.

[0055] Further, in some embodiments, when the second condition is met and the communication is abnormal, the control unit 130 controls the switch unit 110 to remain turned off.

[0056] In some other embodiments, the switch unit 110 can perform manual switch control to avoid certain extremely special situations, such as abnormal power supply of the protection module 100, which cannot automatically achieve switch control and remains in the off state, and cannot be restored to the grid in time when the grid is restored.

[0057] In one embodiment, the first condition indicates that the power grid is normal, and the second condition indicates that the power grid is abnormal.

[0058] The first sub-condition indicates that the subsequent stage of the protection module 100 has an output, and the subsequent stage is a side where the switch unit 110 is connected to the inverter module 200 .

[0059] See also Figure 2 In one embodiment, the protection module 100 can monitor the voltage and / or current of the front and rear stages of the protection module 100 in real time through the detection unit 120. In some embodiments, the front-stage voltage of the protection module 100 is realized by the grid voltage sampling circuit. Since the front-stage voltage of the protection module 100 is very large, the voltage sampling circuit first divides the voltage through a resistor, and then converts it into a sinusoidal voltage between 0 and 3V through a differential amplifier circuit, and sends the voltage sampling signal to the control unit 130. The control unit 130 calculates the instantaneous value and effective value of the front-stage voltage of the protection module 100. This grid voltage sampling circuit is a common circuit setting in the art and will not be described in detail here.

[0060] See also Figure 2The principles of the grid current sampling circuit and the grid voltage sampling circuit are basically the same. Among them, in the grid current sampling, the sampling line can pass through the magnetic ring of the protection module 100 to reduce the current. The magnetic ring is a ring-shaped magnet made of magnetic material (such as ferrite, nickel-zinc ferrite or manganese-zinc ferrite, etc.), and its interior has magnetic conductivity. When the current passes through the cable or wire, the magnetic ring will affect the flow of the current by changing the magnetic field around the cable. This grid current sampling circuit is a common circuit setting in the field and will not be described in detail here.

[0061] In some embodiments, the protection module 100 further includes a WIFI module.

[0062] In one of the embodiments, the detection unit 120 of the grid-connected and off-grid switching device 10 provided in the embodiment of the present application samples the front-stage and rear-stage voltages of the protection module 100 , and samples the front-stage current of the protection module 100 .

[0063] See also Figure 2 , Figure 3 and Figure 4 , Figure 3 The schematic diagram of the switch unit 110 in one embodiment of the present application is shown. Figure 4 FIG. 1 is a schematic diagram of a driving circuit of the switch unit 110 in an embodiment of the present application.

[0064] In one embodiment, the switch unit 110 is a magnetic latching relay, a control coil J1 of the magnetic latching relay is connected to the control unit 130, and the magnetic latching relay has a first contact D1, a second contact D2, a third contact D3 and a fourth contact D4.

[0065] The first contact D1 is connected to the first phase line L1, the second contact D2 is connected to the first output port GRIDL of the inverter module 200, the third contact D3 is connected to the second phase line L2, and the fourth contact D4 is connected to the second output port GRIDN of the inverter module 200, that is, the first contact D1 and the third contact D3 correspond to the voltages on the first phase line L1 and the second phase line L2 of the power grid, respectively, and the second contact D2 and the fourth contact D4 correspond to the voltages on the first output port GRIDL and the second output port GRIDN of the inverter module 200, respectively. The control coil J1 has a fifth contact D5, a sixth contact D6 and a seventh contact D7, please combine Figure 4 The fifth contact D5 and the seventh contact D7 are the two ends of the control coil J1, and the sixth contact D6 of the control coil J1 is grounded. The first contact D1 and the third contact D3 are used to indicate the front-stage voltage, that is, the mains voltage of the power grid, that is, the front-stage voltage of the protection module 100, and the second contact D2 and the fourth contact D4 are used to indicate the rear-stage voltage of the protection module 100.

[0066] Specifically, see Figure 2 , Figure 3 and Figure 4 , signal A and signal B are internal trigger signals of the control unit 130, wherein signal A is a conduction control signal, and signal B is a shutdown control signal. When signal A comes, the gate voltage of the first switch tube Q1 is higher than its emitter voltage, and the first switch tube Q1 is turned on, so that the gate of the second switch tube Q2 forms a loop. At this time, the emitter voltage of the second switch tube Q2 is higher than its gate voltage, and the second switch tube Q2 is turned on, and the driving power drives the relay coil J1 (control coil J1), and the switch unit 110 is turned on. The same is true for signal B. When signal B comes, the switch unit 110 is turned off. It can be understood that the driving power comes from the control unit 130, and the signals A and B are indirectly derived from the detection unit 120. In some embodiments, the control unit 130 and the detection unit 120 of the protection module 100 are integrated on a control motherboard.

[0067] See also Figure 1 In one embodiment, the power grid is a broken phase power grid, specifically, the broken phase split-phase power grid includes a first phase line L1, a second phase line L2 and a neutral line N.

[0068] See also Figure 1 and Figure 5 , Figure 5 The figure shows the internal wiring schematic diagram of the inverter module 200 in one embodiment of the present application. When the inverter module 200 works in the grid-connected mode, the internal relays RY1, RY2, RY3 and RY4 of the inverter module 200 are turned on, and the relays RY5, RY6, RY7 and RY8 are turned off. When the inverter module 200 works in the off-grid mode, the internal relays RY1, RY2, RY3 and RY4 of the inverter module 200 are turned off, and the relays RY5, RY6, RY7 and RY8 are turned on.

[0069] The on-grid and off-grid switching device 10 provided in the first aspect of the embodiment of the present application controls the inverter module 200 to work in the on-grid mode when the protection module 100 detects the first condition, and controls the inverter module 200 to work in the off-grid mode when the second condition is detected. The protection module 100 can automatically identify whether the power grid is abnormal and automatically switch the on-grid and off-grid working mode of the inverter module 200. Under the premise of ensuring the power of the inverter module 200, the load and the inverter module 200 are not affected by the power grid and maintain normal operation, thereby improving the reliability of the on-grid and off-grid switching device 10, simplifying the structure of the inverter on-grid and off-grid system, and greatly reducing the problem of complex wiring.

[0070] See also Figure 6The second aspect of the embodiment of the present application provides a photovoltaic storage system, which includes a photovoltaic component 300, an energy storage component 400 and the on-grid switching device 10 provided in the first aspect of the embodiment of the present application. The photovoltaic component 300 is used to store the collected solar energy into the energy storage component 400, and the energy storage component 400 is connected to the inverter module 200. In some embodiments, the energy storage component 400 and the inverter module 200 of the photovoltaic storage system can be integrated together, that is, in the form of an energy storage inverter all-in-one machine.

[0071] See also Figure 6 In one embodiment, the photovoltaic storage system further includes a distribution box 500, which is used to distribute the power of the power grid or the inverter module 200 to various loads. It can be understood that the photovoltaic storage system has multiple loads.

[0072] Please combine Figure 1-Figure 5 A third aspect of the embodiment of the present application provides a grid-connected and off-grid switching method, which is applied to the grid-connected and off-grid switching device 10 provided in the first aspect of the embodiment of the present application. The grid-connected and off-grid switching method includes:

[0073] When the protection module 100 detects that the power grid is normal, the communication between the inverter module 200 and the protection module 100 is normal, and the subsequent stage of the protection module 100 has output, the protection module 100 turns on the power grid and controls the inverter module 200 to enter the grid-connected mode, and when the subsequent stage of the protection module 100 has no output, the protection module 100 keeps being connected to the power grid.

[0074] When the protection module 100 detects a grid abnormality and the communication between the inverter module 200 and the protection module 100 is normal and the subsequent stage of the protection module 100 has output, the protection module 100 disconnects from the grid and controls the inverter module 200 to enter the off-grid mode, and when the subsequent stage of the protection module 100 has no output, the protection module 100 remains disconnected from the grid.

[0075] When the protection module 100 detects that the power grid is normal and the communication between the inverter module 200 and the protection module 100 is abnormal and the subsequent stage of the protection module 100 has output, the protection module 100 disconnects the power grid and the inverter module 200 supplies power to the load. When the subsequent stage of the protection module 100 has no output, the protection module 100 turns on the power grid and controls the inverter module 200 to stop output.

[0076] When the protection module 100 detects that the power grid is abnormal and the communication between the inverter module 200 and the protection module 100 is abnormal, the protection module 100 disconnects the power grid.

[0077] The on-grid and off-grid switching method provided in the embodiment of the present application is that the protection module 100 can sample the grid voltage and / or current, determine whether the grid is abnormal, and transmit the information to the inverter module 200 through the CAN communication line, and synchronously perform on-grid and off-grid control in combination with the status of the inverter module 200, which can ensure that the load and the inverter module 200 are not affected by the abnormality of the grid under the power premise of the inverter module 200, and maintain normal operation, and there is no need to connect a load to the inverter module 200 as an emergency load, thereby saving a lot of wiring and costs.

[0078] Furthermore, in some embodiments, the on-grid and off-grid switching method further includes an initialization monitoring step, and the initialization step includes:

[0079] When the system is powered on, the inverter module 200 remains in a standby or non-off-grid output state, and the protection module 100 remains turned off.

[0080] The protection module 100 samples the voltage and current of the front and rear stages to determine whether the power grid is abnormal.

[0081] The protection module 100 samples the voltage at the rear stage to determine whether the rear stage of the inverter module 200 has output.

[0082] It is determined whether the communication between the protection module 100 and the inverter module 200 is abnormal.

[0083] Furthermore, in some embodiments, the on-grid and off-grid switching method further includes an operation monitoring step, and the initialization step includes:

[0084] When the system operates normally, the inverter module 200 remains in the grid-connected state, and the protection module 100 remains turned on.

[0085] The protection module 100 samples the voltage and current of the front and rear stages to determine whether the power grid is abnormal.

[0086] The protection module 100 samples the voltage at the rear stage to determine whether the rear stage of the inverter module 200 has output.

[0087] It is determined whether the communication between the protection module 100 and the inverter module 200 is abnormal.

[0088] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A grid-connected and off-grid switching device, comprising: An inverter module, wherein an output port of the inverter module is used to connect to a load to supply power to the load, and the output port of the inverter module is also used to connect to a power grid; A protection module, the protection module is connected to the inverter module and to the power grid, and is used to control the inverter module to be in a grid-connected mode when a first condition is detected, and to control the inverter module to be in an off-grid mode when a second condition is detected; The protection module includes a switch unit and a control unit; the protection module also includes a detection unit, the detection unit is connected to the control unit, the detection unit is used to detect whether the first condition and the second condition are met, and the control unit controls the on or off of the switch unit according to the detection result of the detection unit; the protection module also includes a communication module, and the communication module is used for communication between the protection module and the inverter module; The control unit is further configured to control the switch unit to be turned on when the detection unit detects the first sub-condition under the first condition, and control the switch unit to remain turned on when the detection unit does not detect the first sub-condition; Under the second condition, when the detection unit detects the first sub-condition, the switch unit is controlled to be turned off, and when the detection unit does not detect the first sub-condition, the switch unit is controlled to remain turned off; When the first condition is met and the communication is abnormal, the control unit controls the switch unit to turn off when the detection unit detects the first sub-condition, and the control unit controls the switch unit to turn on and stop the inverter module from supplying power to the load when the detection unit does not detect the first sub-condition; When the second condition is met and the communication is normal, the control unit controls the switch unit to remain turned off; The first condition indicates that the power grid is normal, and the second condition indicates that the power grid is abnormal; The first sub-condition indicates that the subsequent stage of the protection module has an output, and the subsequent stage is a side of the switch unit connected to the inverter module.

2. The on-grid and off-grid switching device according to claim 1, characterized in that: The switch unit includes a first sub-switch and a second sub-switch, wherein the first sub-switch is connected to a first phase line of the power grid and is used to control the on or off of the first phase line; The second sub-switch is connected to the second phase line of the power grid and is used to control the conduction or disconnection of the second phase line; The control unit is connected to the switch unit, and is used to control the switch unit to be turned on or off so as to control the first phase line and the second phase line to be turned on or off.

3. The on-grid and off-grid switching device according to claim 2, characterized in that: The switch unit is a magnetic latching relay, a control coil of the magnetic latching relay is connected to the control unit, and the magnetic latching relay has a first contact, a second contact, a third contact and a fourth contact; The first contact is connected to the first phase line, the second contact is connected to a first output port of the inverter module, the third contact is connected to the second phase line, and the fourth contact is connected to a second output port of the inverter module.

4. The on-grid and off-grid switching device according to claim 2, characterized in that: The power grid is a broken-phase power grid.

5. A solar storage system, characterized in that: It comprises a photovoltaic component, an energy storage component and the on-grid and off-grid switching device as described in any one of claims 1 to 4, wherein the photovoltaic component is used to store the collected solar energy into the energy storage component, and the energy storage component is connected to the inverter module.

6. A grid-connected and off-grid switching method, applied to the grid-connected and off-grid switching device according to any one of claims 1 to 4, characterized in that: include: When the protection module detects that the power grid is normal, the communication between the inverter module and the protection module is normal, and the subsequent stage of the protection module has output, the protection module turns on the power grid and controls the inverter module to enter the grid-connected mode, and when the subsequent stage of the protection module has no output, the protection module is kept connected to the power grid; When the protection module detects that the power grid is abnormal and the communication between the inverter module and the protection module is normal and the subsequent stage of the protection module has output, the protection module disconnects the power grid and controls the inverter module to enter an off-grid mode, and when the subsequent stage of the protection module has no output, the protection module is kept disconnected from the power grid; When the protection module detects that the power grid is normal and the communication between the inverter module and the protection module is abnormal and the subsequent stage of the protection module has output, the protection module disconnects the power grid and the inverter module supplies power to the load; and when the subsequent stage of the protection module has no output, the protection module turns on the power grid and controls the inverter module to stop output; When the protection module detects that the power grid is abnormal and the communication between the inverter module and the protection module is abnormal, the protection module disconnects the power grid.

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