Photovoltaic energy storage system

Abstract

Provided in the present application is a photovoltaic energy storage system, comprising an inverter and an energy storage apparatus. The inverter comprises a direct-current conversion circuit, a direct-current bus, an inverter circuit and a switch assembly, wherein the switch assembly comprises a first end, a second end and a third end, the first end and the third end each being used for being connected between a negative electrode of a photovoltaic module and a negative electrode of the direct-current bus, and the second end being connected to a positive electrode of the direct-current bus; the switch assembly is used for controlling the disconnection between a negative input end of the direct-current conversion circuit and the positive electrode of the direct-current bus and the connection between the negative input end of the direct-current conversion circuit and the negative electrode of the direct-current bus; or the switch assembly is used for controlling the connection between the negative input end of the direct-current conversion circuit and the positive electrode of the direct-current bus and the disconnection between the negative input end of the direct-current conversion circuit and the negative electrode of the direct-current bus. The technical solution can reduce the complexity of the photovoltaic energy storage system and the number of devices, thereby further lowering costs.

Description

A photoelectric storage system

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 20, 2023, with application number 202311771998.0 and application name “A Photovoltaic Storage System”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of power electronics technology, and more specifically, to a photovoltaic storage system and a control method applied to the photovoltaic storage system. Background Art

[0003] As countries around the world continue to promote energy conservation, emission reduction and energy transformation, renewable energy power generation technology has received increasing attention. Among them, photovoltaic power generation systems have been widely used in power systems and microgrids due to their technological maturity and economic efficiency.

[0004] However, photovoltaic power generation systems have long been plagued by inefficiencies. After a period of use, photovoltaic modules experience performance degradation, leading to a drop in the overall system's output power. Research has found that the cause of this phenomenon is the high voltage between the circuitry within the crystalline silicon photovoltaic module and its grounded metal frame, which causes a continuous degradation in the module's power generation performance. This phenomenon is known as potential induced degradation (PID).

[0005] To address the PID problem of photovoltaic modules, a voltage compensation module is typically installed in photovoltaic power generation systems. For example, for the photovoltaic storage inverter in a photovoltaic storage system, even at night when the photovoltaic modules are not outputting energy, the energy storage system still provides energy to the photovoltaic storage inverter, allowing the photovoltaic storage inverter to continue to operate on the grid. At this time, the negative pole (PV-) of the photovoltaic module is continuously at a negative voltage relative to the earth (PE). A switching device, such as a relay, is required to disconnect the negative pole (PV-) of the photovoltaic module from the negative output terminal (BUS-) of the photovoltaic storage inverter. The voltage compensation module is then used to raise the voltage between the negative pole (PV-) of the photovoltaic module and the earth (PE) to a positive voltage.

[0006] Therefore, current PID compensation technology solutions for photovoltaic storage systems require a separate voltage compensation module, or integrate the voltage compensation module into the AC auxiliary power source to achieve PID compensation for photovoltaic modules. However, this increases the complexity of the photovoltaic power generation system and the number of components, significantly increasing costs.

[0007] Based on this, how to reduce the complexity of the photovoltaic storage system, reduce the number of components, and thus reduce costs has become an urgent problem to be solved.

[0008] Summary of the Invention

[0009] The present application provides a photovoltaic storage system that can perform PID compensation on photovoltaic modules at night without setting up an additional voltage compensation module in the photovoltaic storage system, thereby reducing the complexity of the photovoltaic storage system, reducing the number of components, and further reducing costs.

[0010] In a first aspect, a photovoltaic storage system is provided, comprising: an inverter and an energy storage device, the inverter comprising a DC conversion circuit, a DC bus, an inverter circuit and a switch component, the positive input end of the DC conversion circuit is used to connect to the positive pole of the photovoltaic component, the negative input end of the DC conversion circuit is used to connect to the negative pole of the photovoltaic component, the positive output end of the DC conversion circuit is connected to the positive pole of the DC bus, the negative output end of the DC conversion circuit is connected to the negative pole of the DC bus, the positive pole of the DC bus is connected to the positive input end of the inverter circuit and the positive pole of the energy storage device, the negative pole of the DC bus is connected to the negative input end of the inverter circuit and the negative pole of the energy storage device, wherein the switch component comprises the first One end, a second end and a third end, the first end and the third end are respectively used to connect the negative pole of the photovoltaic component and the negative pole of the DC bus, the first end and the third end are used to control the on-off between the negative pole of the photovoltaic component and the negative pole of the DC bus, the second end is connected to the positive pole of the DC bus, the switch component is used to control the disconnection between the negative input end of the DC conversion circuit and the positive pole of the DC bus and the conduction between the negative input end of the DC conversion circuit and the negative pole of the DC bus, or the switch component is used to control the conduction between the negative input end of the DC conversion circuit and the positive pole of the DC bus and the disconnection between the negative input end of the DC conversion circuit and the negative pole of the DC bus.

[0011] According to the above technical solution, a switch assembly is provided in the photovoltaic storage system, wherein the first and third ends of the switch assembly are respectively used to connect the negative pole of the photovoltaic module and the negative pole of the DC bus, and the second end of the switch assembly is connected to the positive pole of the DC bus. The switch assembly is used to control the disconnection between the negative input terminal of the DC conversion circuit and the positive pole of the DC bus, and the conduction between the negative input terminal of the DC conversion circuit and the negative pole of the DC bus, or the switch assembly is used to control the conduction between the negative input terminal of the DC conversion circuit and the positive pole of the DC bus, and the disconnection between the negative input terminal of the DC conversion circuit and the negative pole of the DC bus. At night, the energy storage device provides energy to the inverter. When the controller controls the first and second ends of the photovoltaic module to conduct, the voltage output by the energy storage device can be input to the negative pole of the photovoltaic module, so that the voltage of the negative pole of the photovoltaic module relative to the ground is raised to zero voltage or positive voltage, thereby implementing PID compensation for the photovoltaic module at night. Furthermore, because the embodiments of the present application do not require an additional voltage compensation module in the photovoltaic storage system, the complexity of the photovoltaic storage system can be reduced, the number of components can be reduced, and the cost can be further reduced.

[0012] In conjunction with the first aspect, in certain implementations of the first aspect, the first end and the third end are respectively connected between the negative pole of the photovoltaic module and the negative pole of the DC bus, including: the first end is connected to the negative pole of the photovoltaic module, and the third end is connected to the negative input terminal of the DC conversion circuit; or the first end is connected to the negative input terminal of the DC conversion circuit, and the third end is connected to the negative output terminal of the DC conversion circuit; or the first end is connected to the negative output terminal of the DC conversion circuit, and the third end is connected to the negative pole of the DC bus. According to the above technical solution, the complexity of the photovoltaic storage system can be reduced, the number of components can be reduced, and the cost can be further reduced.

[0013] In combination with the first aspect, in certain implementations of the first aspect, the photovoltaic storage system also includes a controller, which is used to: when the output voltage and / or output current of the photovoltaic component is less than or equal to a threshold, control the first end and the second end to be conductive, and control the first end and the third end to be disconnected, and the positive voltage output by the energy storage device is used to raise the voltage of the negative pole of the photovoltaic component to the ground to zero voltage or positive voltage.

[0014] According to the above technical solution, when the output voltage and / or output current of the photovoltaic component is less than or equal to the threshold, the controller controls the first end and the second end of the switch component to be turned on. Since the second end of the switch component is connected to the positive pole of the DC bus, the controller controls the first end and the second end of the switch component to be turned on so that the voltage output by the energy storage device can be input to the negative pole of the photovoltaic component, thereby raising the voltage value of the negative pole (PV-) of the photovoltaic component to the ground to zero voltage or positive voltage, so as to achieve PID compensation of the photovoltaic component by the photovoltaic storage system at night. In addition, since the embodiment of the present application does not require an additional voltage compensation module to be set in the photovoltaic storage system, it can reduce the complexity of the photovoltaic storage system, reduce the number of components, and further reduce costs.

[0015] In conjunction with the first aspect, in certain implementations of the first aspect, the controller is further configured to: when the output voltage and / or output current of the photovoltaic module exceeds the threshold, disconnect the first terminal from the second terminal and connect the first terminal to the third terminal, so that the DC power output by the photovoltaic module is used to supply the inverter circuit and the energy storage device. This technical solution can reduce the complexity of the photovoltaic energy storage system, reduce the number of components, and further lower costs.

[0016] In conjunction with the first aspect, in certain implementations of the first aspect, the solar-to-storage system further includes a current limiting device, one end of which is connected to the positive electrode of the DC bus, and the other end of which is connected to the second end. According to the above technical solution, the complexity of the solar-to-storage system can be reduced, the number of components can be reduced, and the cost can be further reduced.

[0017] In combination with the first aspect, in certain implementations of the first aspect, the controller is further used to: when the voltage of the DC bus is less than or equal to a first preset value, control the switching tube of the DC conversion circuit to an open-loop switching mode; wherein, when the switching tube is in the open-loop switching mode, the voltage across the first end and the third end decreases.

[0018] According to the above technical solution, when the energy storage device in the solar-storage system is powered off and shut down (for example, due to a battery SOC limit shutdown, a device failure, a low battery charge, or manual shutdown of the energy storage switch), the first and third terminals of the switch assembly S1 can be safely connected before the solar-storage system is powered off and shut down. This prevents contact damage, increased contact impedance, and even damage to the switch assembly, thereby improving overall system reliability.

[0019] In combination with the first aspect, in certain implementations of the first aspect, the controller is further used to: when the voltage value across the first end and the third end is less than or equal to a second preset value, control the first end to be disconnected from the second end, and control the first end to be connected to the third end, wherein the second preset value is the safety shutdown voltage value across the first end and the second end.

[0020] According to the above technical solution, when the energy storage device in the solar-storage system is powered off and shut down (for example, due to a battery SOC limit shutdown, a device failure, a low battery charge, or manual shutdown of the energy storage switch), the first and third terminals of the switch assembly S1 can be safely connected before the solar-storage system is powered off and shut down. This prevents contact damage, increased contact impedance, and even damage to the switch assembly, thereby improving overall system reliability.

[0021] In combination with the first aspect, in certain implementations of the first aspect, the controller is further used to: when the duration of the switch tube in the open-loop wave transmission mode is greater than or equal to a preset duration, control the first end to be disconnected from the second end, and control the first end to be connected to the third end.

[0022] According to the above technical solution, when the energy storage device in the solar-storage system is powered off and shut down (for example, due to a battery SOC limit shutdown, a device failure, a low battery charge, or manual shutdown of the energy storage switch), the first and third terminals of the switch assembly S1 can be safely connected before the solar-storage system is powered off and shut down. This prevents contact damage, increased contact impedance, and even damage to the switch assembly, thereby improving overall system reliability.

[0023] In conjunction with the first aspect, in certain implementations of the first aspect, the current limiting device includes at least one of the following: a resistor, an inductor, and a capacitor. According to the above technical solution, the complexity of the solar energy storage system can be reduced, the number of components can be reduced, and the cost can be further reduced.

[0024] In conjunction with the first aspect, in certain implementations of the first aspect, the solar storage system further includes a first diode connected in parallel across the first and third ends, wherein a forward current of the first diode is in a direction opposite to a direction of a current flowing through the first and third ends when the first and third ends are conductive. According to the above technical solution, the first diode is provided in anti-parallel connection across the first and third ends of the switch assembly, thereby eliminating the effects of overvoltage in the circuit.

[0025] In combination with the first aspect, in certain implementations of the first aspect, the switch component includes any one of the following: a relay, a metal oxide semiconductor field effect transistor (MOSFIT), and an insulated gate bipolar transistor (IGBT).

[0026] In a second aspect, an inverter is provided, comprising: a DC conversion circuit, a DC bus, an inverter circuit and a switch component, wherein the positive input terminal of the DC conversion circuit is used to connect to the positive pole of the photovoltaic component, the negative input terminal of the DC conversion circuit is used to connect to the negative pole of the photovoltaic component, the positive output terminal of the DC conversion circuit is connected to the positive pole of the DC bus, the negative output terminal of the DC conversion circuit is connected to the negative pole of the DC bus, the positive pole of the DC bus is connected to the positive input terminal of the inverter circuit, the negative pole of the DC bus is connected to the negative input terminal of the inverter circuit, the positive pole of the DC bus is used to connect to the positive pole of the energy storage device, and the negative pole of the DC bus is used to connect to the negative pole of the energy storage device, wherein the switch component The switch component comprises a first end, a second end and a third end, wherein the first end and the third end are respectively used to be connected between the negative pole of the photovoltaic component and the negative pole of the DC bus, and the first end and the third end are used to control the on-off between the negative pole of the photovoltaic component and the negative pole of the DC bus, the second end is connected to the positive pole of the DC bus, and the switch component is used to control the disconnection between the negative input end of the DC conversion circuit and the positive pole of the DC bus and the conduction between the negative input end of the DC conversion circuit and the negative pole of the DC bus, or the switch component is used to control the conduction between the negative input end of the DC conversion circuit and the positive pole of the DC bus and the disconnection between the negative input end of the DC conversion circuit and the negative pole of the DC bus.

[0027] According to the above technical solution, a switch assembly is provided in the inverter, wherein the first and third ends of the switch assembly are respectively connected between the negative pole of the photovoltaic module and the negative pole of the DC bus, and the second end of the switch assembly is connected to the positive pole of the DC bus. The switch assembly is used to control the disconnection between the negative input end of the DC conversion circuit and the positive pole of the DC bus, and the conduction between the negative input end of the DC conversion circuit and the negative pole of the DC bus, or the switch assembly is used to control the conduction between the negative input end of the DC conversion circuit and the positive pole of the DC bus, and the disconnection between the negative input end of the DC conversion circuit and the negative pole of the DC bus. At night, the energy storage device provides energy to the inverter. When the controller controls the first and second ends of the photovoltaic module to conduct, the voltage output by the energy storage device can be input to the negative pole of the photovoltaic module, so that the voltage of the negative pole of the photovoltaic module relative to the ground is raised to zero voltage or positive voltage, thereby achieving PID compensation for the photovoltaic module at night. Furthermore, since the embodiments of the present application do not require an additional voltage compensation module to be provided in the photovoltaic storage system, the complexity of the photovoltaic storage system can be reduced, the number of components can be reduced, and the cost can be further reduced.

[0028] In conjunction with the second aspect, in certain implementations of the second aspect, the first end and the third end are respectively used to connect between the negative pole of the photovoltaic module and the negative pole of the DC bus, including: the first end is used to connect the negative pole of the photovoltaic module, and the third end is connected to the negative input terminal of the DC conversion circuit; or the first end is connected to the negative input terminal of the DC conversion circuit, and the third end is connected to the negative output terminal of the DC conversion circuit; or the first end is connected to the negative output terminal of the DC conversion circuit, and the third end is connected to the negative pole of the DC bus. According to the above technical solution, the complexity of the photovoltaic storage system can be reduced, the number of components can be reduced, and the cost can be further reduced.

[0029] In combination with the second aspect, in certain implementations of the second aspect, the inverter further includes a controller, which is used to: when the output voltage and / or output current of the photovoltaic component is less than or equal to a threshold, control the first end and the second end to be conductive, and control the first end and the third end to be disconnected, and the positive voltage output by the energy storage device is used to raise the voltage of the negative pole of the photovoltaic component to the ground to zero voltage or positive voltage.

[0030] According to the above technical solution, when the output voltage and / or output current of the photovoltaic component is less than or equal to the threshold, the controller controls the first end and the second end of the switch component to be turned on. Since the second end of the switch component is connected to the positive pole of the DC bus, the controller controls the first end and the second end of the switch component to be turned on so that the voltage output by the energy storage device can be input to the negative pole of the photovoltaic component, thereby raising the voltage value of the negative pole (PV-) of the photovoltaic component to the ground to zero voltage or positive voltage, so as to achieve PID compensation of the photovoltaic component by the photovoltaic storage system at night. In addition, since the embodiment of the present application does not require an additional voltage compensation module to be set in the photovoltaic storage system, it can reduce the complexity of the photovoltaic storage system, reduce the number of components, and further reduce costs.

[0031] In conjunction with the second aspect, in certain implementations of the second aspect, the controller is further configured to: when the output voltage and / or output current of the photovoltaic module exceeds the threshold, disconnect the first terminal from the second terminal and connect the first terminal to the third terminal, so that the DC power output by the photovoltaic module is used to supply the inverter circuit and the energy storage device. This technical solution can reduce the complexity of the photovoltaic energy storage system, reduce the number of components, and further lower costs.

[0032] In conjunction with the second aspect, in certain implementations of the second aspect, the inverter further includes a current limiting device, one end of the current limiting device being connected to the positive electrode of the DC bus, and the other end of the current limiting device being connected to the second end. According to the above technical solution, the complexity of the solar-to-storage system can be reduced, the number of components can be reduced, and the cost can be further reduced.

[0033] In combination with the second aspect, in certain implementations of the second aspect, the controller is further used to: when the voltage of the DC bus is less than or equal to a first preset value, control the switching tube of the DC conversion circuit to an open-loop switching mode; wherein, when the switching tube is in the open-loop switching mode, the voltage across the first end and the third end decreases.

[0034] According to the above technical solution, when the energy storage device in the solar-storage system is powered off and shut down (for example, due to a battery SOC limit shutdown, a device failure, a low battery charge, or manual shutdown of the energy storage switch), the first and third terminals of the switch assembly can be safely connected before the solar-storage system is powered off and shut down. This prevents contact damage, increased contact impedance, and even damage to the switch assembly, thereby improving overall system reliability.

[0035] In combination with the second aspect, in certain implementations of the second aspect, the controller is also used to: when the voltage value across the first end and the third end is less than or equal to a second preset value, control the first end to be disconnected from the second end, and control the first end to be connected to the third end, wherein the second preset value is the safety shutdown voltage value across the first end and the second end.

[0036] According to the above technical solution, when the energy storage device in the solar-storage system is powered off and shut down (for example, due to a battery SOC limit shutdown, a device failure, a low battery charge, or manual shutdown of the energy storage switch), the first and third terminals of the switch assembly can be safely connected before the solar-storage system is powered off and shut down. This prevents contact damage, increased contact impedance, and even damage to the switch assembly, thereby improving overall system reliability.

[0037] In combination with the second aspect, in certain implementations of the second aspect, the controller is further used to: when the duration of the switch tube in the open-loop wave transmission mode is greater than or equal to a preset duration, control the first end to be disconnected from the second end, and control the first end to be connected to the third end.

[0038] According to the above technical solution, when the energy storage device in the solar-storage system is powered off and shut down (for example, due to a battery SOC limit shutdown, a device failure, a low battery charge, or manual shutdown of the energy storage switch), the first and third terminals of the switch assembly can be safely connected before the solar-storage system is powered off and shut down. This prevents contact damage, increased contact impedance, and even damage to the switch assembly, thereby improving overall system reliability.

[0039] In conjunction with the second aspect, in certain implementations of the second aspect, the current limiting device includes at least one of the following: a resistor, an inductor, and a capacitor. According to the above technical solution, the complexity of the solar energy storage system can be reduced, the number of components can be reduced, and the cost can be further reduced.

[0040] In conjunction with the second aspect, in certain implementations of the second aspect, the inverter further includes a first diode connected in parallel across the first and third terminals, wherein a forward current of the first diode is in a direction opposite to a direction of a current flowing through the first and third terminals when the first and third terminals are conductive. According to the above technical solution, the first diode is provided in anti-parallel connection across the first and third terminals of the switch assembly, thereby eliminating the effects of overvoltage in the circuit.

[0041] In a third aspect, a control method is provided, which includes: obtaining the output voltage and / or output current of a photovoltaic component; when the output voltage and / or output current of the photovoltaic component is less than or equal to a threshold value, controlling the first end and the second end of the switch component to be turned on, and controlling the first end and the third end to be turned off, so that the positive voltage output by the energy storage device is used to raise the voltage of the negative pole of the photovoltaic component to the ground to zero voltage or positive voltage; or, when the output voltage and / or output current of the photovoltaic component is less than or equal to the threshold value, controlling the first end and the second end to be turned off, and controlling the first end and the third end of the switch component to be turned on, so that the direct current output by the photovoltaic component is used to supply the inverter circuit and the energy storage device; wherein the positive pole of the energy storage device and the positive input terminal of the inverter circuit are connected to the DC bus The first end and the third end are respectively used to be connected between the negative pole of the photovoltaic module and the negative pole of the DC bus. The first end and the third end are used to control the on-off between the negative pole of the photovoltaic module and the negative pole of the DC bus. The second end is connected to the positive pole of the DC bus. The switch component is used to control the disconnection between the negative input terminal of the DC conversion circuit and the positive pole of the DC bus and the conduction between the negative input terminal of the DC conversion circuit and the negative pole of the DC bus. Alternatively, the switch component is used to control the conduction between the negative input terminal of the DC conversion circuit and the positive pole of the DC bus and the disconnection between the negative input terminal of the DC conversion circuit and the negative pole of the DC bus.

[0042] According to the above technical solution, when the output voltage and / or output current of the photovoltaic component is less than or equal to the threshold, the controller controls the first end and the second end of the switch component to be turned on. Since the second end of the switch component is connected to the positive pole of the DC bus, the controller controls the first end and the second end of the switch component to be turned on so that the positive voltage output by the energy storage device can be input to the negative pole of the photovoltaic component, thereby raising the voltage value of the negative pole (PV-) of the photovoltaic component to the ground to zero voltage or positive voltage, so as to achieve PID compensation of the photovoltaic component by the photovoltaic storage system at night. In addition, since the embodiment of the present application does not require an additional voltage compensation module to be set in the photovoltaic storage system, it can reduce the complexity of the photovoltaic storage system, reduce the number of components, and further reduce costs.

[0043] In combination with the third aspect, in certain implementations of the third aspect, the method further includes: obtaining the voltage of the DC bus; when the voltage of the DC bus is less than a first preset value, controlling the switching tube of the DC conversion circuit to operate in an open-loop switching mode; wherein, when the switching tube is in the open-loop switching mode, the voltages across the first end and the third end decrease.

[0044] According to the above technical solution, when the energy storage device in the solar-storage system is powered off and shut down (for example, due to a battery SOC limit shutdown, a device failure, a low battery charge, or manual shutdown of the energy storage switch), the first and third terminals of the switch assembly S1 can be safely connected before the solar-storage system is powered off and shut down. This prevents contact damage, increased contact impedance, and even damage to the switch assembly, thereby improving overall system reliability.

[0045] In combination with the third aspect, in certain implementations of the third aspect, the method further includes: obtaining voltage values ​​across the first end and the third end; when the voltage values ​​across the first end and the third end are less than or equal to a second preset value, controlling the first end and the third end to be conducted, and controlling the first end and the second end of the switch component to be disconnected, wherein the second preset value is a safe shutdown voltage value across the first end and the second end.

[0046] According to the above technical solution, when the energy storage device in the solar-storage system is powered off and shut down (for example, due to a battery SOC limit shutdown, a device failure, a low battery charge, or manual shutdown of the energy storage switch), the first and third terminals of the switch assembly S1 can be safely connected before the solar-storage system is powered off and shut down. This prevents contact damage, increased contact impedance, and even damage to the switch assembly, thereby improving overall system reliability.

[0047] In combination with the third aspect, in certain implementations of the third aspect, the method further includes: when the duration of the switch tube in the open-loop wave transmission mode is greater than or equal to a preset duration, controlling the first end to be connected to the third end, and controlling the first end to be disconnected from the second end.

[0048] According to the above technical solution, when the energy storage device in the solar-storage system experiences a shutdown (e.g., due to a battery SOC limit shutdown, a device failure, a low battery charge, or manual shutdown of the energy storage switch), the first and third terminals of the switch assembly S1 can be safely connected before the solar-storage system shuts down. This prevents contact damage, increased contact impedance, and even damage to the switch assembly, thereby improving overall system reliability.

[0049] In combination with the third aspect, in certain implementations of the third aspect, the switch component includes any one of the following: a relay, a metal oxide semiconductor field effect transistor (MOSFIT), and an insulated gate bipolar transistor (IGBT). BRIEF DESCRIPTION OF THE DRAWINGS

[0050] FIG1 is a schematic diagram of an application scenario of a photovoltaic storage system provided in an embodiment of the present application.

[0051] FIG2 is a schematic structural diagram of a solar storage system 100 provided in yet another embodiment of the present application.

[0052] FIG3 is a schematic structural diagram of a solar storage system 100 provided in yet another embodiment of the present application.

[0053] FIG4 is a schematic structural diagram of a solar storage system 100 provided in yet another embodiment of the present application.

[0054] FIG5 is a schematic structural diagram of a solar storage system 100 provided in yet another embodiment of the present application.

[0055] FIG6 is a schematic structural diagram of a DC conversion circuit 121 provided in an embodiment of the present application.

[0056] FIG7 is a schematic diagram of a current path of a switch tube Q1 in a DC conversion circuit 121 provided in an embodiment of the present application when in an open-loop wave generation mode.

[0057] FIG8 is a schematic diagram showing how the voltage values ​​at the first and third terminals of the switch component S1 change with time when the switch tube Q1 is in the open-loop wave generating mode.

[0058] FIG9 is a schematic flow chart of a control method 900 provided in an embodiment of the present application.

[0059] FIG10 is a schematic flow chart of a control method 900 provided in yet another embodiment of the present application.

[0060] FIG11 is a schematic flow chart of a control method 900 provided in yet another embodiment of the present application. DETAILED DESCRIPTION

[0061] The technical solution in this application will be described below with reference to the accompanying drawings.

[0062] In the description of the embodiments of the present application, unless otherwise specified, “ / ” means or, for example, A / B can mean A or B; “and / or” in this article is merely a way to describe the association relationship of associated objects, indicating that three relationships can exist, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone.

[0063] In the embodiments of the present application, prefixes such as "first" and "second" are used only to distinguish different description objects and have no limiting effect on the position, order, priority, quantity or content of the described objects. The use of prefixes such as ordinal numbers to distinguish description objects in the embodiments of the present application does not constitute a restriction on the described objects. For the statement of the described objects, please refer to the description in the context of the claims or embodiments, and the use of such prefixes should not constitute an unnecessary restriction. In addition, in the description of this embodiment, unless otherwise specified, the meaning of "plurality" is two or more.

[0064] References to "in some embodiments" and the like in this specification mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in one or more embodiments of the present application. Thus, phrases such as "in some embodiments" and the like appearing in different places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "including," "comprising," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized.

[0065] The application scenario of the photovoltaic storage system provided in the embodiment of the present application is described in detail below with reference to FIG1 .

[0066] Figure 1 is a schematic diagram of an application scenario for a photovoltaic storage system according to an embodiment of the present application. As shown in Figure 1 , the devices in the photovoltaic storage system 110 application scenario include: photovoltaic modules 110, photovoltaic inverters 120, and energy storage devices 130. Optionally, photovoltaic storage system 110 may also include: a power grid 140 and a load 150.

[0067] Specifically, photovoltaic assembly 110, also known as a photovoltaic array, includes multiple photovoltaic strings. Photovoltaic is also called photovoltaic, or simply PV. A string is also called a string. Each photovoltaic string includes multiple photovoltaic panels connected in series. Photovoltaic panels are used to convert light energy into electrical energy. The electrical energy generated by photovoltaic panels is direct current (DC). The voltage across a photovoltaic string is equal to the sum of the voltages generated by the multiple photovoltaic panels. The output power of photovoltaic assembly 110 can represent the electrical energy output per unit time by the photovoltaic assembly.

[0068] PV inverter 120 can convert direct current (DC) from PV panels 110 into alternating current (AC) and transmit the AC power to grid 140 or load 150. Alternatively, PV inverter 120 can transmit the DC power from PV panels 110 to energy storage device 130 for charging. It should be noted that direct current (DC) is also called direct current, and alternating current (AC) is also called alternating current. PV inverter 120 can also be referred to as a DC-AC converter or inverter circuit (DC-AC).

[0069] Optionally, the photovoltaic inverter 120 may further include a voltage stabilizing module (not shown in the figure), which can realize the voltage stabilization function of the voltage output by the power generation module. Exemplarily, the voltage stabilizing module can be a DC-DC converter, or a DC-DC converter, or a DC conversion circuit (DC-DC). As an example, the DC conversion circuit (DC-DC) can be set in the maximum power point tracking (MPPT) module in the photovoltaic inverter. It should be noted that the DC conversion circuit (DC-DC) is usually set before the inverter circuit (DC-AC) in the photovoltaic inverter 120, and is used to stabilize the DC power output by the photovoltaic module 110 and output it to the inverter circuit.

[0070] Continuing with Figure 1 , energy storage device 130 in photovoltaic storage system 110 can store and release electrical energy. For example, energy storage device 130 can store DC power from photovoltaic modules 110. Energy storage device 130 can also power grid 140 or load 150 via photovoltaic inverter 120. Therefore, energy storage device 130 has a wide range of applications, including but not limited to household applications, industrial green power applications, and smart photovoltaic power plant scenarios.

[0071] As can be seen from the above description, photovoltaic inverter 120 is a converter that can convert direct current (DC) into alternating current (AC). Specifically, photovoltaic inverter 120 can include two DC ports (e.g., DC port 1 and DC port 2) and an AC port. The two DC ports are used to connect photovoltaic module 110 and energy storage device 130, respectively. For example, DC port 1 is used to connect photovoltaic module 110, and DC port 2 is used to connect energy storage device 130. The AC port can be used to output AC power, which can be distributed through a distribution box (not shown), such as to grid 140 and load 150.

[0072] PV panels 110 can feed power to grid 140 and supply power to load 150 via the DC port. Energy storage device 130 can supply power to load 150 via the DC port. Grid 140 can supply power to load 150 via the AC port. In other words, PV inverter 130 serves as the connection hub between load 150 and the energy module (which may include PV panels 110, energy storage device 130, and grid 140).

[0073] Currently, in the practical application of solar-storage systems, during daytime grid-connected power generation, the high voltage between the circuits in the photovoltaic modules and their grounded metal frames will cause a continuous degradation in the power generation performance of the photovoltaic modules. This phenomenon is called potential induced degradation (PID).

[0074] To address the PID problem of photovoltaic modules, a voltage compensation module is typically installed in photovoltaic power generation systems. For example, for the photovoltaic storage inverter in a photovoltaic storage system, even at night when the photovoltaic modules are not outputting energy, the energy storage system still provides energy to the photovoltaic storage inverter, allowing the photovoltaic storage inverter to continue to operate on the grid. At this time, the negative pole (PV-) of the photovoltaic module is continuously at a negative voltage relative to the earth (PE). A switching device, such as a relay, is required to disconnect the negative pole (PV-) of the photovoltaic module from the negative output terminal (BUS-) of the photovoltaic storage inverter. The voltage compensation module is then used to raise the voltage between the negative pole (PV-) of the photovoltaic module and the earth (PE) to a positive voltage.

[0075] Therefore, current PID compensation technology solutions for photovoltaic storage systems require a separate voltage compensation module, or integrate the voltage compensation module into the AC auxiliary power source to achieve PID compensation for photovoltaic modules. However, this increases the complexity of the photovoltaic power generation system and the number of components, significantly increasing costs.

[0076] Based on this, the present application aims to provide a photovoltaic storage system that can perform PID compensation on photovoltaic modules at night without setting up an additional voltage compensation module in the photovoltaic storage system, thereby reducing the complexity of the photovoltaic storage system, reducing the number of devices, and further reducing costs.

[0077] FIG2 is a schematic structural diagram of a solar storage system 100 provided in yet another embodiment of the present application.

[0078] As shown in FIG2 , the photovoltaic energy storage system 100 includes an inverter 120 and an energy storage device 130 , wherein the inverter 120 includes a DC conversion circuit 121 , a DC bus, an inverter circuit 122 and a switch component 160 .

[0079] Specifically, the positive input terminal of the DC conversion circuit 121 is used to connect to the positive electrode of the photovoltaic module 110, and the negative input terminal of the DC conversion circuit 121 is used to connect to the negative electrode of the photovoltaic module 110. The photovoltaic module 110 is used to convert light energy into direct current. It should be noted that the input terminals (positive input terminal and negative input terminal) of the DC conversion circuit 121 can be used to connect to one or more photovoltaic modules 110. It should be understood that this embodiment of the present application does not limit this. In addition, the specific description of the photovoltaic module 110 can be referred to the above, and will not be repeated here.

[0080] The positive output terminal of the DC conversion circuit 121 is connected to the positive pole of the DC bus, and the negative output terminal of the DC conversion circuit 121 is connected to the negative pole of the DC bus. The positive pole of the DC bus is connected to the positive input terminal of the inverter circuit 122 and the positive pole of the energy storage device 130, and the negative pole of the DC bus is connected to the negative input terminal of the inverter circuit 122 and the negative pole of the energy storage device 130. The DC conversion circuit 121 is used to convert the voltage of the input DC power and output it, while the inverter circuit 122 is used to convert the input DC power into AC power for output.

[0081] Optionally, the DC conversion circuit 121 may be a Boost circuit. Exemplarily, the DC conversion circuit 121 may be an MPPT circuit, or may be a circuit capable of implementing an MPPT function. It should be understood that this application does not impose any limitation on this.

[0082] It should be noted that the DC conversion circuit 121 is equivalent to the voltage stabilizing module described above, and the inverter circuit 122 is equivalent to the DC-AC converter described above. For the relevant descriptions of the DC conversion circuit 121, the inverter circuit 122, and the energy storage device 130, please refer to the above descriptions and will not be repeated here. For ease of understanding, the DC conversion circuit and the inverter circuit are uniformly used in the following embodiments for description.

[0083] Optionally, the energy storage device 130 may include a battery module. For example, the battery module may also be referred to as a battery pack.

[0084] Optionally, the energy storage device 130 may further include a direct current (DC)-DC conversion circuit, which is electrically connected to the battery module.

[0085] Continuing with FIG. 2 , in the embodiment of the present application, switch assembly 160 includes a first end, a second end, and a third end. The first end and the third end of switch assembly 160 are respectively connected between the negative pole of photovoltaic assembly 110 and the negative pole of the DC bus. The first and third ends of switch assembly 160 are used to control the on / off connection between the negative pole of photovoltaic assembly 110 and the negative pole of the DC bus. The second end of switch assembly 160 is connected to the positive pole of the DC bus.

[0086] Specifically, the switch component 160 is used to control the disconnection between the negative input terminal of the DC conversion circuit 121 and the positive pole of the DC bus and the conduction between the negative input terminal of the DC conversion circuit 121 and the negative pole of the DC bus, or the switch component 160 is used to control the conduction between the negative input terminal of the DC conversion circuit 121 and the positive pole of the DC bus and the disconnection between the negative input terminal of the DC conversion circuit 121 and the negative pole of the DC bus.

[0087] It should be noted that the first and third ends of the switch assembly 160 are respectively connected between the negative pole of the photovoltaic assembly 110 and the negative pole of the DC bus. This can be understood as the first end of the switch assembly 160 being directly or indirectly connected to the negative pole of the photovoltaic assembly 110, and the third end of the switch assembly 160 being directly or indirectly connected to the negative pole of the DC bus. For example, the following examples illustrate possible connection locations for the switch assembly in the photovoltaic storage system 100. Figure 3 is a schematic structural diagram of a photovoltaic storage system 100 provided in another embodiment of the present application.

[0088] For example, in one possible implementation, a first end of the switch assembly 160 is connected to the negative electrode of the photovoltaic assembly 110, a second end of the switch assembly 160 is connected to the positive electrode of the DC bus, and a third end of the switch assembly 160 is connected to the negative input terminal of the DC conversion circuit 121, as shown in FIG3(a).

[0089] For example, in one possible implementation, a first end of the switch component 160 is connected to the negative input terminal of the DC converter circuit 121, a second end of the switch component 160 is connected to the positive electrode of the DC bus, and a third end of the switch component 160 is connected to the negative output terminal of the DC converter circuit 121. In other words, the switch component 160 is disposed between the negative input terminal and the negative output terminal of the DC converter circuit 121, as shown in FIG3(b).

[0090] For example, in one possible implementation, the first end of the switch component 160 is connected to the negative output end of the DC conversion circuit 121, the second end of the switch component 160 is connected to the positive pole of the DC bus, and the third end of the switch component 160 is connected to the negative pole of the DC bus, as shown in Figure 4.

[0091] It should also be noted that the second end of the switch component 160 is connected to the positive pole of the DC bus. It can be understood that the second end of the switch component 160 is directly or indirectly connected to the positive output terminal (BUS+) of the DC conversion circuit 121.

[0092] It should be noted that the connection mentioned above may be a direct connection, or may be an indirect connection through other devices (such as inductors, capacitors, etc.).

[0093] Furthermore, the switch component 160 mentioned above is used to control the disconnection between the negative input terminal of the DC conversion circuit 121 and the positive pole of the DC bus, and the conduction between the negative input terminal of the DC conversion circuit 121 and the negative pole of the DC bus, or the switch component 160 is used to control the conduction between the negative input terminal of the DC conversion circuit 121 and the positive pole of the DC bus, and the disconnection between the negative input terminal of the DC conversion circuit 121 and the negative pole of the DC bus. It can be understood that even if there are other passive devices (such as inductors, capacitors, etc.) between the negative input terminal of the DC conversion circuit 121 and the negative pole of the DC bus or the DC conversion circuit 121 and the positive pole of the DC bus, it will not affect the switch component 160's ability to control the energy flow between the energy storage device 130 and the negative pole of the photovoltaic component 110.

[0094] Alternatively, FIG4 is a schematic structural diagram of a photovoltaic storage system 100 provided in another embodiment of the present application. The photovoltaic storage system 100 may further include a current limiting device 170. As shown in FIG4 , one end of the current limiting device 170 is connected to the positive electrode of the DC bus, and the other end of the current limiting device 170 is connected to the second end of the switch assembly 160. In other words, the second end of the switch assembly 160 can be indirectly connected to the positive electrode of the DC bus through the current limiting device 170.

[0095] Exemplarily, the current limiting device 170 may be a resistor, a capacitor, or an inductor. It should be understood that the current limiting device 170 is provided for safety considerations, and the embodiment of the present application does not limit the type of the current limiting device 170.

[0096] Furthermore, in the embodiment of the present application, the photovoltaic storage system 100 may further include a controller (not shown). Optionally, in one possible implementation, the controller is configured to: control the first terminal and the second terminal of the photovoltaic assembly 110 to be conductive when the output voltage and / or output current of the photovoltaic assembly 110 is less than or equal to a threshold value.

[0097] It should be noted that the output voltage and / or output current of the photovoltaic assembly 110 is less than or equal to the threshold value, which can be understood as that at night, the photovoltaic assembly 110 no longer converts light energy into direct current, resulting in the current or voltage output by the photovoltaic assembly 110 being less than or equal to the threshold value. Specifically, for the photovoltaic storage system 100, at night, the energy storage device 130 provides energy to the inverter circuit 122, and the inverter circuit 122 continues to operate in grid connection. When the controller controls the first and second ends of the photovoltaic assembly 110 to be turned on, the voltage output by the energy storage device can be input to the negative pole of the photovoltaic assembly 110, so that the voltage of the negative pole of the photovoltaic assembly 110 to the ground is raised to zero voltage or positive voltage, so as to realize PID compensation of the photovoltaic assembly 110 by the photovoltaic storage system at night.

[0098] For example, in one possible implementation, the controller is configured to: when the output voltage of photovoltaic assembly 110 is less than or equal to a threshold, control the first and second terminals of switch assembly 160 to be conductive, and control the first and third terminals of switch assembly 160 to be disconnected. It should be understood that the threshold in this case is a voltage threshold.

[0099] For example, in one possible implementation, the controller is configured to: when the output current of photovoltaic assembly 110 is less than or equal to a threshold, control the first and second terminals of switch assembly 160 to be conductive, and control the first and third terminals of switch assembly 160 to be disconnected. It should be understood that the threshold in this case is a current threshold.

[0100] For example, in one possible implementation, the controller is configured to: when the output voltage and output current of photovoltaic assembly 110 are both less than or equal to threshold values, control the first and second terminals of switch assembly 160 to be conductive, and control the first and third terminals of switch assembly 160 to be disconnected. It should be understood that the threshold values ​​in this case are a current threshold and a voltage threshold, respectively. That is, when both the output voltage and the output current are less than or equal to the threshold values, it can be understood that the output voltage is less than or equal to the voltage threshold, and the output current is also less than or equal to the current threshold.

[0101] Optionally, in one possible implementation, the controller is also used to control the first and second ends of the switch component 160 to be disconnected, and control the first and third ends of the switch component 160 to be turned on when the output voltage and / or output current of the photovoltaic component 110 is greater than a threshold.

[0102] The output voltage and / or output current of photovoltaic assembly 110 being greater than the threshold value can be understood as indicating that during the day, photovoltaic assembly 110 converts light energy into direct current (DC) output, and the current or voltage output by photovoltaic assembly 110 is greater than the threshold value. The controller disconnects the first and second terminals of switch assembly 160 and connects the first and third terminals of switch assembly 160, enabling photovoltaic assembly 110 to normally output DC power during the day to supply inverter circuit 122 and energy storage device 130.

[0103] For example, in one possible implementation, the controller is configured to, when the output voltage of photovoltaic assembly 110 is greater than a threshold, control the first and second terminals of switch assembly 160 to be disconnected, and control the first and third terminals of switch assembly 160 to be conductive. It should be understood that the threshold in this case is a voltage threshold.

[0104] For example, in one possible implementation, the controller is configured to, when the output current of photovoltaic assembly 110 is greater than a threshold, control the first and second terminals of switch assembly 160 to be disconnected, and control the first and third terminals of switch assembly 160 to be connected. It should be understood that the threshold in this case is a current threshold.

[0105] In one possible implementation, the controller is configured to, when both the output voltage and output current of photovoltaic assembly 110 are greater than threshold values, control the first and second terminals of switch assembly 160 to be disconnected, and control the first and third terminals of switch assembly 160 to be conductive. It should be understood that the threshold values ​​in this case are a current threshold and a voltage threshold, respectively. In other words, when both the output voltage and output current are greater than the threshold values, it can be understood that the output voltage is greater than the voltage threshold, and the output current is also greater than the current threshold.

[0106] FIG5 is a schematic structural diagram of a solar storage system 100 provided in yet another embodiment of the present application.

[0107] Optionally, in the embodiment of the present application, the switch assembly 160 may be a single-pole double-throw switch, as shown in FIG5(a).

[0108] Optionally, in an embodiment of the present application, the switch assembly 160 may also be a switch assembly 160 composed of two independent single-pole single-throw switches, as shown in (b) of Figure 5 , where the fixed ends of the single-pole single-throw switch RY1 and the single-pole single-throw switch RY2 are connected in series to form the switch assembly 160.

[0109] It should be noted that the switch component 160 mentioned above can be a relay, or a metal oxide semiconductor field effect transistor (MOSFIT), or an insulated gate bipolar transistor (IGBT). It should be understood that the embodiment of the present application is not limited to this.

[0110] Optionally, in one possible implementation, the solar energy storage system 100 further includes a first diode D1, as shown in FIG4 , connected in parallel across the first and third terminals of the switch assembly 160. The direction of the forward current of the first diode is opposite to the direction of the current flowing through the first and third terminals of the switch assembly when the first and third terminals are conductive.

[0111] Specifically, as shown in Figure 4, the direction of the forward current of the first diode D1 is opposite to the direction of the current flowing through the first end and the third end when the first end and the third end of the switch component 160 are turned on. It can be understood that the first diode D1 is reversely connected in parallel to the first end and the third end of the switch component 160.

[0112] It should be understood that the purpose of providing the first diode D1 between the first and third terminals of the switch assembly is to eliminate the effects of overvoltage. For example, when the photovoltaic assembly 110 outputs a voltage, the voltage difference between the first and third terminals of the switch assembly 160 is first eliminated by the first diode D1, and then the first and third terminals of the switch assembly 160 are closed.

[0113] It should be noted that the position of the switch component 160 shown in FIG4 is for illustration only. Since the first diode D1 can be provided in anti-parallel connection at both the first and third terminals of the switch component 160, the position of the first diode D1 is not limited to that shown in FIG4. It should be understood that the present embodiment is not limited to this.

[0114] In summary, according to the above technical solution, when the output voltage and / or output current of the photovoltaic component is less than or equal to the threshold, the controller controls the first and second ends of the switch component to be turned on, and controls the first and third ends of the switch component to be turned off. Since the second end of the switch component is connected to the positive pole of the DC bus, the controller controls the first and second ends of the switch component to be turned on, and the voltage output by the energy storage device can be input to the negative pole of the photovoltaic component, so that the voltage value of the negative pole (PV-) of the photovoltaic component to the earth is raised to zero voltage or positive voltage, so as to realize PID compensation of the photovoltaic component by the photovoltaic storage system at night. In addition, since the embodiment of the present application does not require an additional voltage compensation module to be set in the photovoltaic storage system, it can reduce the complexity of the photovoltaic storage system, reduce the number of components, and further reduce costs.

[0115] However, if the energy storage device in the solar-storage system loses power (for example, due to a battery SOC limit shutdown, a device failure, a low battery charge, or manual shutdown of the energy storage switch), the solar-storage system loses power. To ensure the solar-storage system can function properly during daytime when the photovoltaic panels have output voltage or current, it is necessary to control the first and third terminals of the switch assembly to conduct before the energy storage device is powered off.

[0116] However, because the inverter in a solar-storage system continues to operate in grid-connected mode at night, the second terminal of the switch assembly is connected to the positive terminal of the DC bus. This can raise the voltage between the negative terminal (PV-) of the PV assembly and the ground (PE) to zero or positive voltage, resulting in a large voltage difference between the first and third terminals of the switch assembly. In this case, if the controller switches the first and third terminals on, it may damage the switch assembly contacts, increase contact impedance, affect the reliability of the entire system, and in severe cases, even damage the switch assembly.

[0117] To avoid the aforementioned problem with the switch assembly, in the embodiment of the present application, the controller is further configured to control the switching transistor Q1 in the DC converter circuit 121 to operate in an open-loop mode when the DC bus voltage is less than or equal to a first preset value. The first preset value is a pre-set voltage value.

[0118] It should be understood that the DC bus voltage can be considered as the input bus voltage of the inverter circuit 122 in the inverter, or the input bus voltage of the auxiliary power source in the inverter 120. When the DC bus voltage is less than or equal to the first preset value, it can be understood that the energy storage device 130 in the solar-storage system 100 has reached a lower limit shutdown state, and in this case, the energy storage device 130 does not provide energy to the inverter 120.

[0119] It should be noted that when the controller controls the switch tube Q1 in the DC conversion circuit 121 to be in the open-loop wave generating mode, the voltage across the first terminal and the third terminal of the switch component 160 decreases.

[0120] The structure of the DC converter circuit 121 and the current path of the switch tube in the DC converter circuit in the open-loop wave-generating mode are described in detail below with reference to Figures 6 and 7. Figure 6 is a schematic structural diagram of a DC converter circuit 121 provided in an embodiment of the present application, and Figure 7 is a schematic diagram of the current path of the switch tube Q1 in the DC converter circuit 121 in the open-loop wave-generating mode provided in an embodiment of the present application.

[0121] As shown in Figure 6, the DC conversion circuit 121 includes: a positive input terminal, a negative input terminal, an inductor L1, a switch component S1, a second diode D2, a switch tube Q1 and a bus capacitor C1, a positive output terminal (BUS+) and a negative output terminal (BUS-). Among them, the positive input terminal and the negative input terminal are used to connect to one or more photovoltaic modules (not shown in the figure), and the positive output terminal (BUS+) and the negative output terminal (BUS-) are used to connect to the DC bus. One end of the bus capacitor C1 is connected to the positive output terminal (BUS+), and the other end of the bus capacitor C1 is connected to the negative output terminal (BUS-).

[0122] It should be understood that the switch component S1 is equivalent to the switch component 160 described above. For ease of understanding, the switch component S1 will be uniformly used for detailed description below.

[0123] It should be noted that the switch tube Q1 can be a metal oxide semiconductor field effect transistor (MOSFIT) or an insulated gate bipolar transistor (IGBT). It should be understood that the embodiment of the present application does not limit this.

[0124] Specifically, one end of the inductor L1 is connected to the positive input terminal, the other end of the inductor L1 is connected to the anode of the second diode D2, the anode of the second diode D2 is also connected to the first end of the switch tube Q1, the cathode of the second diode D2 is connected to the positive output terminal (BUS+), the second end of the switch tube Q1 is connected to the negative output terminal (BUS-), and the second end of the switch tube Q1 is also connected to the third end of the switch component S1, and the first end of the switch component S1 is connected to the negative input terminal.

[0125] Optionally, when the switch tube Q1 is a MOS tube, the first terminal is the drain and the second terminal is the source. That is, the anode of the second diode D2 is also connected to the drain of the switch tube Q1, the source of the switch tube Q1 is connected to the negative output terminal (BUS-), and the source of the switch tube Q1 is also connected to the third terminal of the switch component S1.

[0126] Optionally, when the switch tube Q1 is an IGBT, the first terminal is the emitter and the second terminal is the collector. That is, the anode of the second diode D2 is also connected to the emitter of the switch tube Q1, the collector of the switch tube Q1 is connected to the negative output terminal (BUS-), and the collector of the switch tube Q1 is also connected to the third terminal of the switch component S1.

[0127] Optionally, the DC conversion circuit 121 may further include a filter capacitor C2 , wherein one end of the filter capacitor C2 is connected to the positive input end, and the other end of the filter capacitor C2 is connected to the negative input end.

[0128] Optionally, the DC conversion circuit 121 may further include a common-mode inductor, wherein the input ports (positive input and negative input) of the DC conversion circuit 121 are connected to the input port of the common-mode inductor, and the output ports of the common-mode inductor are connected to the output ports (positive output and negative output) of the DC conversion circuit 121. The common-mode inductor is used to filter common-mode noise in the AC power.

[0129] Optionally, the DC conversion circuit 121 may further include a filter capacitor C3 , wherein one end of the filter capacitor C3 is connected to the positive input end, and the other end of the filter capacitor C3 is connected to the negative input end.

[0130] It should be noted that the specific structure of the DC converter circuit 121 shown in FIG6 is only for illustration, and it should be understood that the present invention is not limited thereto. For example, the position of the switch component S1 is not limited to the position shown in FIG6 .

[0131] Furthermore, when the controller controls the switch tube Q1 to be in the open-loop ripple generation mode, the current path in the DC conversion circuit 121 is as shown in FIG7 .

[0132] Referring to Figure 7(a), when switch Q1 turns on, current flows from Y-capacitor C4 through the PV module (or its equivalent diode), inductor L1, switch Q1, Y-capacitor C5, and ultimately to the chassis, forming a loop. At this point, the energy in Y-capacitors C1 and C5 is transferred to inductor L1 through the current flow shown in Figure 7(a).

[0133] However, when the switch tube Q1 is turned off, the current on the inductor L1 continues to flow, and the current path is shown in FIG7( b ). The second diode D2 is turned on, and the current flows through the bus capacitor C1 .

[0134] In this way, as the switch tube Q1 is continuously turned on and off in the open-loop wave generation mode, the energy on the Y capacitor C4 and the Y capacitor C5 can be released, thereby causing the voltage across the first and third terminals of the switch component S1 to continuously decrease.

[0135] Figure 8 is a schematic diagram illustrating how the voltage across the first and third terminals of the switch component S1 varies over time when the switch tube Q1 is in open-loop ripple generation mode. It should be noted that the waveforms shown in Figure 8 specifically include: waveforms of the voltage variation across the first and third terminals of the switch component S1 (e.g., waveforms 1, 2, and 3) and a driving waveform of the switch tube Q1 in open-loop ripple generation mode (e.g., waveform 4).

[0136] As can be seen from Figure 8, when switch Q1 is not in open-loop ripple generation mode, that is, before time t0, the controller does not control switch Q1 to be in open-loop ripple generation mode. It can be seen that the voltage across the first and second terminals of switch component S1 drops slowly (waveform 1). When switch Q1 is in open-loop ripple generation mode, that is, after time t0, the controller controls switch Q1 to be in open-loop ripple generation mode. It can be seen that in open-loop ripple generation mode, due to the continuous on and off of switch Q1, the voltage across the first and third terminals of switch component S1 drops rapidly (waveform 2).

[0137] Optionally, in an embodiment of the present application, the controller is further configured to control the first and third terminals of the switch assembly S1 to conduct when the voltage across the first and third terminals is less than or equal to a second preset value. The second preset value is a safe shutdown voltage across the first and third terminals of the switch assembly S1, which can be understood as a critical voltage at which the first and third terminals of the switch assembly S1 can safely conduct. That is, when the voltage across the first and third terminals of the switch assembly S1 is less than or equal to the second preset value, the first and third terminals of the switch assembly S1 conduct without causing contact damage, increased contact impedance, or damage to the switch assembly S1.

[0138] It should be noted that the second preset value is a threshold value set in advance.

[0139] Exemplarily, as shown in FIG8 , the second preset value is taken as a voltage value V2 for example.

[0140] Optionally, in a possible implementation, when the voltage value across the first terminal and the third terminal of the switch component S1 is less than or equal to the voltage value V2, the controller controls the first terminal and the third terminal of the switch component S1 to be conductive.

[0141] On the contrary, when the voltage values ​​across the first and third ends of the switch component S1 are greater than the voltage value V2, the controller controls the first and third ends of the switch component S1 to remain disconnected until the detection device detects that the voltage values ​​across the first and third ends of the switch component S1 are less than or equal to the voltage value V2, and then the controller controls the first and third ends of the switch component S1 to be turned on.

[0142] Optionally, in a possible implementation, the controller is further configured to control the first end and the third end of the switch component S1 to be conductive when the duration of the switch tube being in the open-loop ripple mode is greater than or equal to a preset duration.

[0143] It should be understood that the preset duration is the time required for the voltage across the first and third terminals of the switch component S1 to drop to a second preset value when the switch tube is in the open-loop wave transmission mode. It should be understood that the description of the second preset value can be referred to above and will not be repeated here.

[0144] Specifically, the controller starts timing when the switch tube Q1 is in the open-loop wave transmission mode. For example, as shown in Figure 8, the moment when the switch tube Q1 starts to be in the open-loop wave transmission mode is time t0. At this time, the controller starts timing, and when the duration of the switch tube Q1 in the open-loop wave transmission mode is greater than or equal to the preset duration, the first end and the third end of the control switch component S1 are turned on.

[0145] As shown in FIG8 , illustratively, taking the second preset value as the voltage value V2 as an example, it can be seen from the figure that the critical moment corresponding to the voltage value V2 is moment t1, that is, the moment when the voltage between the first end and the second end of the switch component S1 drops to V2 is moment t1. At this time, it is assumed that the preset time length is the time period (t1-t0).

[0146] For example, in one possible implementation, the controller begins timing when the switch Q1 begins to operate in the open-loop ripple generation mode. Subsequently, when the duration of the switch Q1 operating in the open-loop ripple generation mode equals a preset duration, the controller controls the first and third terminals of the switch component S1 to conduct. For example, the controller may control the first and third terminals of the switch component S1 to conduct when the timing reaches a preset duration (e.g., a time period (t1-t0)).

[0147] For example, in one possible implementation, the controller begins timing when the switch Q1 begins to operate in the open-loop ripple mode. Subsequently, when the duration of the open-loop ripple mode held by the switch Q1 exceeds a preset duration, the controller controls the first and third terminals of the switch assembly S1 to conduct. In other words, the controller can control the first and third terminals of the switch assembly S1 to conduct at any time after the timing reaches a preset duration (e.g., time period (t1-t0)). For example, as shown in FIG8 , the controller can control the first and third terminals of the switch assembly S1 to conduct at time t2. The time period (t2-t0) is greater than the time period (t1-t0).

[0148] It should be noted that the open-loop wave generation mode described above is only an example, and the present application can also be applied to other wave generation modes. For example, as long as the voltage across the switching component of the switch tube Q1 can be reduced to a certain threshold (such as a second preset value) in this wave generation mode, it can be sufficient.

[0149] According to the above technical solution, when the energy storage device in the solar-storage system is powered off and shut down (for example, due to a battery SOC limit shutdown, a device failure, a low battery charge, or manual shutdown of the energy storage switch), the first and third terminals of the switch assembly S1 can be safely connected before the solar-storage system is powered off and shut down. This prevents contact damage, increased contact impedance, and even damage to the switch assembly S1, thereby improving overall system reliability.

[0150] FIG9 is a schematic flow chart of a control method 900 provided in an embodiment of the present application. As shown in FIG9 , the control method 900 specifically includes steps S910 and S920, which are described in detail below. It should be noted that the control method can be applied to the aforementioned photovoltaic storage system or to other photovoltaic power generation scenarios, and it should be understood that the present embodiment does not limit this.

[0151] It should be noted in advance that the relevant steps in the embodiments of the present application described below can be executed by the optical storage system, or the corresponding steps can be specifically executed by the controller.

[0152] S910: Obtain the output voltage and / or output current of the photovoltaic module.

[0153] S920 , when the output voltage and / or output current of the photovoltaic assembly is less than or equal to a threshold, controlling the first and second ends of the switch assembly to be turned on, and controlling the first and third ends of the switch assembly to be turned off.

[0154] It should be noted that when the output voltage and / or output current of a photovoltaic module is less than or equal to a threshold value, it can be understood that at night, the photovoltaic module no longer converts light energy into direct current, resulting in the output current or voltage of the photovoltaic module being less than or equal to the threshold value. For a photovoltaic storage system, at night, the energy storage device provides energy to the inverter. When the controller controls the first and second terminals of the photovoltaic module to conduct and the first and third terminals to disconnect, the voltage output by the energy storage device can be input to the negative electrode of the photovoltaic module, so that the voltage of the negative electrode of the photovoltaic module relative to the ground is raised to zero voltage or positive voltage, thereby achieving PID compensation for the photovoltaic module at night.

[0155] For example, in one possible implementation, when the output voltage of the photovoltaic assembly is less than or equal to a threshold, the controller controls the first and second terminals of the switch assembly to be conductive, and controls the first and third terminals of the switch assembly to be disconnected. It should be understood that the threshold in this case is a voltage threshold.

[0156] For example, in one possible implementation, when the output current of the photovoltaic assembly is less than or equal to a threshold, the controller controls the first and second terminals of the switch assembly to be conductive, and controls the first and third terminals of the switch assembly to be disconnected. It should be understood that the threshold in this case is a current threshold.

[0157] For example, in one possible implementation, when the output voltage and output current of the photovoltaic assembly are both less than or equal to threshold values, the controller controls the first and second terminals of the switch assembly to conduct, and controls the first and third terminals of the switch assembly to disconnect. It should be understood that the threshold values ​​in this case are a current threshold and a voltage threshold, respectively. That is, when both the output voltage and the output current are less than or equal to the threshold values, it can be understood that the output voltage is less than or equal to the voltage threshold, and the output current is also less than or equal to the current threshold.

[0158] Optionally, in a possible implementation, the method may further include: when the output voltage and / or output current of the photovoltaic component is greater than a threshold, the controller controls the first and second ends of the switch component to be disconnected, and controls the first and third ends of the switch component to be turned on.

[0159] The output voltage and / or output current of the photovoltaic module being greater than the threshold value can be understood as indicating that, during the day, the photovoltaic module converts light energy into direct current (DC) output, and the current or voltage output by the photovoltaic module is greater than the threshold value. The controller controls the first and second terminals of the switch assembly to be disconnected, and the first and third terminals of the switch assembly to be conductive, so that the photovoltaic module can normally output DC power during the day to supply the inverter circuit and the energy storage device.

[0160] For example, in one possible implementation, when the output voltage of the photovoltaic assembly is greater than a threshold, the controller controls the first and second terminals of the switch assembly to be disconnected, and controls the first and third terminals of the switch assembly to be connected. It should be understood that the threshold in this case is a voltage threshold.

[0161] For example, in one possible implementation, when the output current of the photovoltaic assembly is greater than a threshold, the controller controls the first and second terminals of the switch assembly to be disconnected, and controls the first and third terminals of the switch assembly to be connected. It should be understood that the threshold in this case is a current threshold.

[0162] In one possible implementation, when both the output voltage and output current of the photovoltaic module are greater than threshold values, the controller controls the first and second terminals of the switch component to be disconnected, and controls the first and third terminals of the switch component to be conductive. It should be understood that the threshold values ​​in this case are a current threshold and a voltage threshold, respectively. In other words, when both the output voltage and output current are greater than the threshold values, it can be understood that the output voltage is greater than the voltage threshold, and the output current is also greater than the current threshold.

[0163] In summary, according to the above technical solution, when the output voltage and / or output current of the photovoltaic component is less than or equal to the threshold, the controller controls the first and second ends of the switch component to be turned on, and controls the first and third ends of the switch component to be turned off. Since the second end of the switch component is connected to the positive pole of the DC bus, the controller controls the first and second ends of the switch component to be turned on, and the voltage output by the energy storage device can be input to the negative pole of the photovoltaic component, so that the voltage value of the negative pole (PV-) of the photovoltaic component to the earth is raised to zero voltage or positive voltage, so as to realize PID compensation of the photovoltaic component by the photovoltaic storage system at night. In addition, since the embodiment of the present application does not require an additional voltage compensation module to be set in the photovoltaic storage system, it can reduce the complexity of the photovoltaic storage system, reduce the number of components, and further reduce costs.

[0164] However, if the energy storage device in the solar-storage system loses power and shuts down (for example, due to a battery SOC limit, a device failure, a low battery charge, or manual shutdown of the energy storage switch), the solar-storage system loses power. To ensure the solar-storage system can function properly during daytime when the photovoltaic panels have output voltage or current, it is necessary to control the first and third terminals of the switch assembly to conduct before the energy storage device is powered down.

[0165] However, because the inverter in a solar-storage system continues to operate in grid-connected mode at night, the second terminal of the switch assembly is connected to the positive terminal of the DC bus. This can raise the voltage between the negative terminal (PV-) of the PV assembly and the ground (PE) to zero or positive voltage, resulting in a large voltage difference between the first and third terminals of the switch assembly. In this case, if the controller switches the first and third terminals on, it may damage the switch assembly contacts, increase contact impedance, affect the reliability of the entire system, and in severe cases, even damage the switch assembly.

[0166] Based on this, another embodiment of the present application provides a control method that can avoid the above-mentioned problems in the switch component. As shown in Figure 10, Figure 10 is a schematic flow chart of a control method 900 provided by another embodiment of the present application. The method may also include:

[0167] Step S931: obtaining the voltage of the DC bus.

[0168] Step S941 : When the voltage of the DC bus is less than or equal to a first preset value, control the switching tube in the DC conversion circuit to operate in an open-loop mode, wherein the first preset value is a pre-set voltage value.

[0169] It should be understood that the DC bus voltage can be considered the input bus voltage of the inverter circuit in the inverter, or the input bus voltage of the auxiliary power source in the inverter. A DC bus voltage less than or equal to the first preset value can be understood as a lower limit shutdown of the energy storage device in the solar-storage system, in which case the energy storage device does not provide energy to the inverter.

[0170] It should be noted that when the controller controls the switch tube Q1 in the DC conversion circuit to be in the open-loop wave generating mode, the voltage across the first terminal and the third terminal of the switch component decreases.

[0171] It should be understood that for the description of the voltage across the first and third terminals of the switch component continuously decreasing when the switch tube Q1 is in the open-loop wave generation mode, reference can be made to the relevant descriptions of Figures 7 to 8 above. For the sake of simplicity, they are not repeated here.

[0172] Step S951: obtaining voltage values ​​across the first terminal and the third terminal of the switch component.

[0173] Step S961: When the voltage value across the first terminal and the third terminal of the switch component is less than or equal to a second preset value, the first terminal and the third terminal of the switch component are controlled to be conductive.

[0174] Among them, the second preset value is the safe shutdown voltage value across the first and third ends of the switch component, which can be understood as: the critical voltage value at which the first and third ends of the switch component can be safely turned on, that is, when the voltage across the first and third ends of the switch component is less than or equal to the second preset value, when the first and third ends of the switch component are turned on, there will be no problems such as contact damage, increased contact impedance, and damage to the switch component.

[0175] It should be noted that the second preset value is a threshold value set in advance.

[0176] Exemplarily, as shown in FIG8 , the second preset value is taken as a voltage value V2 for example.

[0177] Optionally, in a possible implementation, when the voltage value across the first terminal and the third terminal of the switch component is less than or equal to the voltage value V2, the controller controls the first terminal and the third terminal of the switch component to be conductive.

[0178] On the contrary, when the voltage values ​​across the first and third ends of the switch component are greater than the voltage value V2, the controller controls the first and third ends of the switch component to remain disconnected, until the obtained voltage values ​​across the first and third ends of the switch component are less than or equal to the voltage value V2, and then the controller controls the first and third ends of the switch component to be turned on.

[0179] Alternatively, in a possible implementation, FIG11 is a schematic flow chart of a control method 900 provided in yet another embodiment of the present application. As shown in FIG11 , step S951 and step S961 may be replaced by step S952. That is, after executing step S941, step S952 is executed.

[0180] In step S952 , when the duration of the switch tube being in the open-loop ripple mode is greater than or equal to a preset duration, the controller controls the first terminal and the third terminal of the switch component to be conductive.

[0181] It should be understood that the preset duration is a pre-set duration. It should be noted that the preset duration is the time required for the voltage across the first and third terminals of the switch component to drop to a second preset value when the switch tube is in open-loop ripple mode. It should be understood that the description of the second preset value can be found above and is not repeated here.

[0182] Specifically, the controller starts timing when the switch tube Q1 is in the open-loop wave transmission mode. For example, as shown in Figure 8, the moment when the switch tube Q1 starts to be in the open-loop wave transmission mode is time t0. At this time, the controller starts timing, and when it is determined that the time length of the switch tube Q1 in the open-loop wave transmission mode is greater than or equal to the preset time length, the first end and the third end of the control switch component are turned on.

[0183] As shown in Figure 8, illustratively, taking the second preset value as the voltage value V2 as an example, it can be seen from the figure that the critical moment corresponding to the voltage value V2 is moment t1, that is, the moment when the voltage between the first end and the second end of the switch component drops to V2 is moment t1. At this time, it is assumed that the preset time length is the time period (t1-t0).

[0184] For example, in one possible implementation, the controller begins timing when the switch tube Q1 begins to operate in the open-loop ripple generation mode. Subsequently, when the duration of the switch tube Q1 operating in the open-loop ripple generation mode equals a preset duration, the controller controls the first terminal and the third terminal of the switch component to conduct. For example, the controller may control the first terminal and the third terminal of the switch component to conduct when the timing reaches a preset duration (e.g., a time period (t1-t0)).

[0185] For example, in one possible implementation, the controller begins timing when the switch Q1 begins to operate in the open-loop ripple mode. Subsequently, when the duration of the open-loop ripple mode remains greater than a preset duration, the controller controls the first and third terminals of the switch assembly to conduct. In other words, the controller can control the first and third terminals of the switch assembly to conduct at any time after the timing reaches a preset duration (e.g., time period (t1-t0)). For example, as shown in FIG7 , the controller can control the first and third terminals of the switch assembly to conduct at time t2. The time period (t2-t0) is greater than the time period (t1-t0).

[0186] According to the above technical solution, when the energy storage device in the solar-storage system is powered off and shut down (for example, due to a battery SOC limit shutdown, a device failure, a low battery charge, or manual shutdown of the energy storage switch), the first and third terminals of the switch assembly can be safely connected before the solar-storage system is powered off and shut down. This prevents contact damage, increased contact impedance, and even damage to the switch assembly, thereby improving overall system reliability.

[0187] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0188] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0189] In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0190] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0191] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0192] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0193] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A solar energy storage system, characterized in that: include: An inverter and an energy storage device, wherein the inverter comprises a DC conversion circuit, a DC bus, an inverter circuit and a switch component, The positive input terminal of the DC conversion circuit is used to connect the positive electrode of the photovoltaic module, and the negative input terminal of the DC conversion circuit is used to connect the negative electrode of the photovoltaic module. The positive output terminal of the DC conversion circuit is connected to the positive electrode of the DC bus, the negative output terminal of the DC conversion circuit is connected to the negative electrode of the DC bus, the positive electrode of the DC bus is connected to the positive input terminal of the inverter circuit and the positive electrode of the energy storage device, and the negative electrode of the DC bus is connected to the negative input terminal of the inverter circuit and the negative electrode of the energy storage device. Wherein, the switch component includes a first end, a second end and a third end, the first end and the third end are respectively used to connect between the negative pole of the photovoltaic component and the negative pole of the DC bus, the first end and the third end are used to control the on-off between the negative pole of the photovoltaic component and the negative pole of the DC bus, the second end is connected to the positive pole of the DC bus, the switch component is used to control the disconnection between the negative input end of the DC conversion circuit and the positive pole of the DC bus and the conduction between the negative input end of the DC conversion circuit and the negative pole of the DC bus, or the switch component is used to control the conduction between the negative input end of the DC conversion circuit and the positive pole of the DC bus and the disconnection between the negative input end of the DC conversion circuit and the negative pole of the DC bus.

2. The photovoltaic storage system according to claim 1, characterized in that: The first end and the third end are respectively used to be connected between the negative electrode of the photovoltaic module and the negative electrode of the DC bus, and include: The first end is used to connect the negative pole of the photovoltaic module, and the third end is connected to the negative input end of the DC conversion circuit; or, The first end is connected to the negative input end of the DC conversion circuit, and the third end is connected to the negative output end of the DC conversion circuit; or, The first end is connected to the negative output end of the DC conversion circuit, and the third end is connected to the negative electrode of the DC bus.

3. The photovoltaic storage system according to claim 1 or 2, characterized in that: The optical storage system further includes a controller, which is used for: When the output voltage and / or output current of the photovoltaic component is less than or equal to a threshold value, the first end and the second end are controlled to be turned on, and the first end and the third end are controlled to be disconnected, and the positive voltage output by the energy storage device is used to raise the voltage of the negative pole of the photovoltaic component to the ground to zero voltage or positive voltage.

4. The solar storage system according to claim 3, characterized in that: The controller is also used for: When the output voltage and / or output current of the photovoltaic component is greater than the threshold value, the first end is controlled to be disconnected from the second end, and the first end is controlled to be connected to the third end, and the direct current output by the photovoltaic component is used to supply the inverter circuit and the energy storage device.

5. The photovoltaic storage system according to any one of claims 1 to 4, characterized in that: The solar energy storage system further includes a current limiting device. One end of the current limiting device is connected to the positive electrode of the DC bus, and the other end of the current limiting device is connected to the second end.

6. The photovoltaic storage system according to any one of claims 1 to 5, characterized in that: The controller is also used for: When the voltage of the DC bus is less than or equal to a first preset value, controlling the switching tube of the DC conversion circuit to operate in an open-loop mode; Wherein, when the switch tube is in the open-loop wave generating mode, the voltage across the first end and the third end decreases.

7. The photovoltaic storage system according to claim 6, characterized in that: The controller is also used for: When the voltage value across the first end and the third end is less than or equal to a second preset value, the first end is controlled to be disconnected from the second end, and the first end is controlled to be connected to the third end, wherein the second preset value is a safe shutoff voltage value across the first end and the second end.

8. The solar storage system according to claim 6, characterized in that: The controller is also used for: When the duration of the switch tube being in the open-loop wave-generating mode is greater than or equal to a preset duration, the first end is controlled to be disconnected from the second end, and the first end is controlled to be connected to the third end.

9. The photovoltaic storage system according to any one of claims 5 to 8, characterized in that: The current limiting device includes at least one of the following: Resistors, inductors, capacitors.

10. The photovoltaic storage system according to any one of claims 1 to 9, characterized in that: The solar energy storage system further includes a first diode, The first diode is connected in parallel to both ends of the first end and the third end, wherein the direction of the forward current of the first diode is opposite to the direction of the current flowing through the first end and the third end when the first end and the third end are turned on.

11. An inverter, characterized in that: include: DC conversion circuit, DC bus, inverter circuit and switch components, The positive input terminal of the DC conversion circuit is used to connect the positive electrode of the photovoltaic module, and the negative input terminal of the DC conversion circuit is used to connect the negative electrode of the photovoltaic module. The positive output terminal of the DC conversion circuit is connected to the positive electrode of the DC bus, the negative output terminal of the DC conversion circuit is connected to the negative electrode of the DC bus, the positive electrode of the DC bus is connected to the positive input terminal of the inverter circuit, the negative electrode of the DC bus is connected to the negative input terminal of the inverter circuit, the positive electrode of the DC bus is used to connect to the positive electrode of the energy storage device, and the negative electrode of the DC bus is used to connect to the negative electrode of the energy storage device. Wherein, the switch component includes a first end, a second end and a third end, the first end and the third end are respectively used to connect between the negative pole of the photovoltaic component and the negative pole of the DC bus, the first end and the third end are used to control the on-off between the negative pole of the photovoltaic component and the negative pole of the DC bus, the second end is connected to the positive pole of the DC bus, the switch component is used to control the disconnection between the negative input end of the DC conversion circuit and the positive pole of the DC bus and the conduction between the negative input end of the DC conversion circuit and the negative pole of the DC bus, or the switch component is used to control the conduction between the negative input end of the DC conversion circuit and the positive pole of the DC bus and the disconnection between the negative input end of the DC conversion circuit and the negative pole of the DC bus.

12. The inverter according to claim 11, characterized in that: The first end and the third end are respectively used to be connected between the negative electrode of the photovoltaic module and the negative electrode of the DC bus, and include: The first end is used to connect the negative pole of the photovoltaic module, and the third end is connected to the negative input end of the DC conversion circuit; or, The first end is connected to the negative input end of the DC conversion circuit, and the third end is connected to the negative output end of the DC conversion circuit; or, The first end is connected to the negative output end of the DC conversion circuit, and the third end is connected to the negative electrode of the DC bus.

13. The inverter according to claim 11 or 12, characterized in that: The inverter further includes a controller, which is used for: When the output voltage and / or output current of the photovoltaic component is less than or equal to a threshold value, the first end and the second end are controlled to be turned on, and the first end and the third end are controlled to be disconnected, and the positive voltage output by the energy storage device is used to raise the voltage of the negative pole of the photovoltaic component to the ground to zero voltage or positive voltage.

14. The inverter according to claim 13, characterized in that: The controller is also used for: When the output voltage and / or output current of the photovoltaic component is greater than the threshold value, the first end is controlled to be disconnected from the second end, and the first end is controlled to be connected to the third end, and the direct current output by the photovoltaic component is used to supply the inverter circuit and the energy storage device.

15. The inverter according to any one of claims 11 to 14, characterized in that: The inverter further includes a current limiting device, One end of the current limiting device is connected to the positive electrode of the DC bus, and the other end of the current limiting device is connected to the second end.

16. The inverter according to any one of claims 11 to 15, characterized in that: The inverter further includes a first diode, The first diode is connected in parallel to both ends of the first end and the third end, wherein the direction of the forward current of the first diode is opposite to the direction of the current flowing through the first end and the third end when the first end and the third end are turned on.

17. A control method, characterized in that: The method comprises: Obtaining output voltage and / or output current of a photovoltaic module; When the output voltage and / or output current of the photovoltaic component is less than or equal to a threshold value, the first terminal and the second terminal of the switch component are controlled to be turned on, and the first terminal and the third terminal are controlled to be turned off, so that the positive voltage output by the energy storage device is used to raise the voltage of the negative electrode of the photovoltaic component to the ground to zero voltage or positive voltage; or, When the output voltage and / or output current of the photovoltaic assembly is less than or equal to the threshold value, the first end is controlled to be disconnected from the second end, and the first end is controlled to be connected to the third end of the switch assembly, so that the direct current output by the photovoltaic assembly is used to supply the inverter circuit and the energy storage device; The positive electrode of the energy storage device and the positive input terminal of the inverter circuit are connected to the positive electrode of the DC bus, and the negative electrode of the energy storage device and the negative input terminal of the inverter circuit are connected to the negative electrode of the DC bus. The first end and the third end are respectively used to connect between the negative pole of the photovoltaic component and the negative pole of the DC bus, the first end and the third end are used to control the on-off between the negative pole of the photovoltaic component and the negative pole of the DC bus, the second end is connected to the positive pole of the DC bus, the switch component is used to control the disconnection between the negative input end of the DC conversion circuit and the positive pole of the DC bus and the conduction between the negative input end of the DC conversion circuit and the negative pole of the DC bus, or the switch component is used to control the conduction between the negative input end of the DC conversion circuit and the positive pole of the DC bus and the disconnection between the negative input end of the DC conversion circuit and the negative pole of the DC bus, The positive output terminal of the DC conversion circuit is connected to the positive electrode of the DC bus, and the negative output terminal of the DC conversion circuit is connected to the negative electrode of the DC bus.

18. The control method according to claim 17, characterized in that: The method further comprises: Obtaining the voltage of the DC bus; When the voltage of the DC bus is less than a first preset value, controlling the switching tube of the DC conversion circuit to operate in an open-loop mode; Wherein, when the switch tube is in the open-loop wave generating mode, the voltage across the first end and the third end decreases.

19. The control method according to claim 18, characterized in that: The method further comprises: Obtaining voltage values ​​across the first terminal and the third terminal; When the voltage value between the first end and the third end is less than or equal to a second preset value, the first end is controlled to be connected to the third end, and the first end is controlled to be disconnected from the second end of the switch component. The second preset value is a safe cutoff voltage value between the first end and the second end.

20. The control method according to claim 18, characterized in that: The method further comprises: When the duration of the switch tube being in the open-loop wave-generating mode is greater than or equal to a preset duration, the first end is controlled to be connected to the third end, and the first end is controlled to be disconnected from the second end.

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