Switch combination detection method of optical storage system and optical storage system

Abstract

The invention provides a switch combination detection method of an optical storage system and the optical storage system, the optical storage system is electrically connected with a power grid, the optical storage system comprises a photovoltaic management unit, an energy storage management unit and an inverter, the inverter comprises an inverter circuit, a controller and a switch combination, the switch combination comprises a plurality of groups of switch devices, each group of switching devices comprises two switching devices which are connected in series, the inverter circuit comprises at least one phase line and a neutral line, and a group of switching devices is arranged in each of the at least one phase line and the neutral line. The control signal is used for controlling switching devices in the switch combination to be switched on or switched off; after the switch combination responds to the control signal to complete switching-on or switching-off of the switching device, voltage of the input end and the output end of the switch combination is obtained; and judging whether the voltages of the input end and the output end of the switch combination meet a preset voltage condition, and judging whether the switch combination has a fault according to a judgment result.

Description

Technical Field

[0001] This application relates to the field of power supply systems, and more particularly to a method for detecting switch combinations in a photovoltaic-storage system and the photovoltaic-storage system itself. Background Technology

[0002] With increasing global emphasis on environmental protection and sustainable development, traditional energy sources face numerous challenges, including limited resources and environmental pollution. To achieve cleaner and lower-carbon energy, renewable energy sources such as solar and wind power have experienced rapid development. One example is the photovoltaic (PV) energy storage system, which typically refers to a solar photovoltaic power generation and storage system. This system can include photovoltaic modules and battery modules. The photovoltaic modules utilize the photovoltaic effect to convert solar energy into electricity, while the battery modules store this electricity for use when sunlight is not needed. The system can also include an inverter, allowing it to connect to the power grid for coordinated operation.

[0003] To avoid safety hazards, a switchgear assembly needs to be installed in the inverter to achieve electrical isolation between the photovoltaic-storage system and the grid. The switchgear assembly can be a relay or a contactor, etc. When the inverter is not operating, the switchgear assembly can be disconnected to ensure that the inverter has no electrical connection to the grid. If a switch in the switchgear assembly fails due to sticking, it will pose a significant safety hazard to the photovoltaic-storage system.

[0004] In existing technologies, detection circuits can be used to detect faults in switches within a switch assembly. However, most detection circuits on the market are complex and costly. Furthermore, due to variations in the parameters of the components selected for the detection circuit, additional errors can easily be introduced during the detection process, thus affecting the detection results. Summary of the Invention

[0005] In view of this, the embodiments of this application aim to provide a method for detecting the switching combination of a photovoltaic energy storage system and a photovoltaic energy storage system.

[0006] Firstly, a method for detecting the switch combination of a photovoltaic-storage system is provided. This system is electrically connected to the power grid and includes a photovoltaic management unit (PV management unit), an energy storage management unit (ESM) and an inverter. The PV management unit includes photovoltaic modules and a photovoltaic DC-DC converter module. The ESM includes a battery module and a battery DC-DC converter module. The inverter includes an inverter circuit, a controller, and a switch combination. The switch combination includes multiple sets of switching devices, each set including two switches connected in series. The inverter circuit includes at least one phase line and a neutral line, with a set of switching devices installed in each phase line and neutral line. Both the PV management unit and the ESM are connected to the inverter circuit. The circuit includes electrical connections: the inverter circuit and the switch assembly are electrically connected; the switch assembly is electrically connected to the power grid; and the controller is electrically connected to the inverter circuit, the switch assembly, and the power grid. The detection method includes: sending a control signal to the switch assembly through the controller, the control signal being used to control the closing or opening of the switching devices in the switch assembly; after the switch assembly responds to the control signal and completes the closing or opening of the switching devices, acquiring the voltage at the input and output terminals of the switch assembly; determining whether the voltage at the input and output terminals of the switch assembly meets the preset voltage conditions; and judging whether there is a fault in the switch assembly based on the judgment result. The preset voltage conditions are related to the output power of the photovoltaic energy storage system.

[0007] According to the first aspect, a first sub-switch device and a second sub-switch device are set in the neutral line. The first sub-switch device and the second sub-switch device belong to a group of switch devices in a switch combination. The preset voltage condition includes that the voltage at the input terminal and the output terminal of the switch combination is less than a first preset voltage value. It is determined whether the voltage at the input terminal and the output terminal of the switch combination meets the preset voltage condition. Based on the determination result, it is determined whether there is a fault in the switch combination, including: when the control signal controls the first sub-switch device to close and the second sub-switch device to open, and the voltage at the input terminal and the output terminal of the switch combination meets the preset voltage condition, it is determined that the second sub-switch device has a sticking fault, and / or when the control signal controls the first sub-switch device to open and the second sub-switch device to close, and the voltage at the input terminal and the output terminal of the switch combination meets the preset voltage condition, it is determined that the first sub-switch device has a sticking fault.

[0008] According to the first aspect, or any implementation of the first aspect above, the preset voltage condition includes the voltage at the input terminal and the output terminal of the switch combination being greater than the second preset voltage value. It is determined whether the voltage at the input terminal and the output terminal of the switch combination meets the preset voltage condition. Based on the determination result, it is determined whether the switch combination has a fault, including: when the control signal controls both the first sub-switch device and the second sub-switch device to be closed, and the voltage at the input terminal and the output terminal of the switch combination meets the preset voltage condition, it is determined that the first sub-switch device and / or the second sub-switch device has an open circuit fault.

[0009] According to the first aspect, or any implementation of the first aspect above, a third sub-switch device and a fourth sub-switch device are provided in at least one phase line. The third sub-switch device and the fourth sub-switch device belong to a group of switches in a switch combination. All switches in the group located on the neutral line are closed. The preset voltage condition includes that the voltage at the input terminal and the output terminal of the switch combination is less than a third preset voltage value. It is determined whether the voltage at the input terminal and the output terminal of the switch combination meets the preset voltage condition. Based on the determination result, it is determined whether there is a fault in the switch combination, including: when the control signal controls the third sub-switch device to close and the fourth sub-switch device to open, and the voltage at the input terminal and the output terminal of the switch combination meets the preset voltage condition, it is determined that the fourth sub-switch device has a sticking fault, and / or when the control signal controls the third sub-switch device to open and the fourth sub-switch device to close, and the voltage at the input terminal and the output terminal of the switch combination meets the preset voltage condition, it is determined that the third sub-switch device has a sticking fault.

[0010] According to the first aspect, or any implementation of the first aspect above, the preset voltage condition includes the voltage at the input terminal and the output terminal of the switch combination being greater than the fourth preset voltage value. It is determined whether the voltage at the input terminal and the output terminal of the switch combination meets the preset voltage condition. Based on the determination result, it is determined whether the switch combination has a fault, including: when the control signal controls both the third sub-switch device and the fourth sub-switch device to be closed, and the voltage at the input terminal and the output terminal of the switch combination meets the preset voltage condition, it is determined that the third sub-switch device and / or the fourth sub-switch device has an open circuit fault.

[0011] According to the first aspect, or any implementation of the first aspect above, the inverter circuit includes a first phase line, a second phase line, and a third phase line. A first switching device and a fifth switching device are arranged in the first phase line, a second switching device and a sixth switching device are arranged in the second phase line, a third switching device and a seventh switching device are arranged in the third phase line, and a fourth switching device and an eighth switching device are arranged in the neutral line. The first, second, third, and fourth switching devices are electrically connected to the inverter circuit, and the fifth, sixth, seventh, and eighth switching devices are electrically connected to the power grid.

[0012] According to the first aspect, or any implementation of the first aspect above, the control signal satisfies one or more of the following: the control signal controls the closing or closing of the first switching device, the second switching device, and the third switching device; the control signal controls the closing or closing of the fourth switching device; the control signal controls the closing or closing of the fifth switching device, the sixth switching device, and the seventh switching device; the control signal controls the closing or closing of the eighth switching device.

[0013] According to the first aspect, or any implementation of the first aspect above, the control signal satisfies one or more of the following: the control signal controls the closing or closing of the first switching device, the sixth switching device, and the seventh switching device; the control signal controls the closing or closing of the fourth switching device; the control signal controls the closing or closing of the second switching device, the third switching device, and the fifth switching device; the control signal controls the closing or closing of the eighth switching device.

[0014] According to the first aspect, or any implementation of the first aspect above, the control signal satisfies one or more of the following: the control signal controls the closing or closing of the first switching device, the third switching device, and the sixth switching device; the control signal controls the closing or closing of the fourth switching device; the control signal controls the closing or closing of the second switching device, the fifth switching device, and the seventh switching device; the control signal controls the closing or closing of the eighth switching device.

[0015] Secondly, this application provides a photovoltaic-storage system, which is electrically connected to the power grid. The system includes: a photovoltaic management unit, comprising photovoltaic modules and photovoltaic DC-DC modules; an energy storage management unit, comprising battery modules and battery DC-DC modules; and an inverter, comprising an inverter circuit, a controller, and a switch assembly. The switch assembly includes multiple sets of switching devices, each set comprising two switches connected in series. The switch assembly is electrically connected to the power grid. The inverter circuit includes at least one phase line and a neutral line, and each phase line and neutral line is provided with a set of switching devices. Both the photovoltaic management unit and the energy storage management unit are electrically connected to the inverter circuit. The inverter circuit is electrically connected to the switch assembly. The controller is electrically connected to the inverter circuit, the switch assembly, and the power grid to send control signals to the switch assembly. The control signals are used to control the switching devices in the switch assembly to close or open. The switch assembly is used to respond to the control signals to complete the closing or opening of the switching devices. The photovoltaic-energy storage system is used to determine whether the voltages at the input and output terminals of the switch assembly meet the preset voltage conditions, and to determine whether there is a fault in the switch assembly based on the determination results. The preset voltage conditions are related to the output power of the photovoltaic-energy storage system.

[0016] Thirdly, this application provides a computer-readable storage medium for computer-executable program code, the program code including a switching combination detection method for performing a first-side optical storage system.

[0017] Fourthly, embodiments of this application provide a computer program that includes commands for executing the switch combination detection method of the optical storage system of the first aspect.

[0018] The switch combination detection method for a photovoltaic energy storage system proposed in this application can control the closing or opening of different switching devices in the switch combination via control signals, and determine whether the voltage at the input and output terminals of the switch combination meets preset voltage conditions to determine whether the switch combination has a fault. Because the detection logic of this method is simple and does not require complex circuit configuration, it reduces the complexity and cost of the photovoltaic energy storage system. Furthermore, this method can detect the combination of different switching devices closing or opening, combined with reasonable preset voltage conditions, thereby improving the accuracy of the detection results. Attached Figure Description

[0019] Figure 1 This is a schematic flowchart of a switch combination detection method for a photovoltaic energy storage system provided in an embodiment of this application.

[0020] Figure 2 This is a schematic diagram of the structure of a photoelectric storage system provided in an embodiment of this application.

[0021] Figure 3 This is a schematic diagram of another optical storage system provided in an embodiment of this application.

[0022] Figure 4 This is a schematic diagram of another optical storage system provided in an embodiment of this application.

[0023] Figure 5 This is a schematic diagram of a start switch combination detection process proposed in an embodiment of this application.

[0024] Figure 6 This is a flowchart illustrating the judgment logic for switch combination detection provided in an embodiment of this application.

[0025] Figure 7 This is a timing logic diagram for controlling switching devices in a switch combination detection method, provided in an embodiment of this application.

[0026] Figure 8 This is a schematic diagram of the structure of a photovoltaic energy storage system provided in an embodiment of this application. Detailed Implementation

[0027] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0028] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0029] The terms "first" and "second," etc., used in the specification and claims of this application are used to distinguish different objects, not to describe a specific order of objects. For example, "first target object" and "second target object," etc., are used to distinguish different target objects, not to describe a specific order of target objects.

[0030] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0031] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0032] With increasing global emphasis on environmental protection and sustainable development, traditional energy sources face numerous challenges, including limited resources and environmental pollution. To achieve cleaner and lower-carbon energy, renewable energy sources such as solar and wind power have experienced rapid development. One example is the photovoltaic (PV) energy storage system, which typically refers to a solar photovoltaic power generation and storage system. This system can include photovoltaic modules and battery modules. The photovoltaic modules utilize the photovoltaic effect to convert solar energy into electricity, while the battery modules store this electricity for use when sunlight is not needed. The system can also include an inverter, allowing it to connect to the power grid for coordinated operation.

[0033] To avoid safety hazards, a switchgear assembly is required in the inverter to achieve electrical isolation between the photovoltaic-storage system and the grid. This switchgear assembly can be a relay or contactor, etc. When the inverter is not operating, the switchgear assembly can be disconnected to ensure complete electrical disconnection between the inverter and the grid. If a switch in the switchgear assembly fails due to sticking, it will pose a significant safety hazard to the photovoltaic-storage system. Therefore, before connecting the photovoltaic-storage system to the grid, fault detection of the switches in the switchgear assembly is necessary to ensure that the assembly is in normal working order. Furthermore, accurately detecting and locating the faulty switch when it fails to close or open can significantly reduce maintenance time and costs for the photovoltaic-storage system.

[0034] In existing technologies, to detect whether a switch in a switch combination is faulty, a detection circuit can be set up to test the switch combination. For example, for a single-phase inverter, a switch combination can be set only at the output terminal of the single-phase inverter and the grid terminal, and a corresponding detection circuit can be set up based on this switch combination. However, for a three-phase inverter, a switch combination needs to be set up at the output terminal of each phase of the three-phase inverter and the grid terminal, and a corresponding detection circuit needs to be set up based on this switch combination. This process makes the circuit structure more complex, resulting in higher system costs. Moreover, because the component parameters selected by the detection circuit are different, and the circuit is affected by temperature changes during operation, the detection circuit is prone to introducing additional errors during the switch combination fault detection process, thus affecting the fault detection results.

[0035] To address the aforementioned problems, this application proposes a method for detecting the switch combination in a photovoltaic energy storage system. The following section discusses this method in conjunction with... Figure 1 The embodiments of this application will be described below.

[0036] Figure 1 This is a flowchart illustrating a switch combination detection method for a photovoltaic energy storage system provided in an embodiment of this application. Figure 1 The photovoltaic and energy storage system in the middle can be connected to the power grid to... Figure 2 For example, Figure 2 This is a schematic diagram of a photovoltaic-storage system provided in an embodiment of this application. The photovoltaic-storage system may include a photovoltaic management unit, an energy storage management unit, and an inverter. The inverter may include an inverter circuit, a controller, and a switch assembly. The switch assembly may include multiple sets of switching devices, and each set of switching devices may include two switches connected in series. Both the photovoltaic management unit and the energy storage management unit may be electrically connected to the inverter circuit. The inverter circuit is electrically connected to the switch assembly, and the switch assembly is electrically connected to the power grid. The controller is electrically connected to the inverter circuit, the switch assembly, and the power grid.

[0037] In some embodiments, the photovoltaic management unit may include photovoltaic modules and photovoltaic DC-DC modules, and the energy storage management unit may include battery modules and battery DC-DC modules.

[0038] In some embodiments, the inverter circuit may include at least one phase line and a neutral line, and a set of switching devices connected in series may be provided in both the phase line and the neutral line. Optionally, the inverter circuit in a single-phase inverter may include one phase line and a neutral line. A set of switching devices connected in series may be provided in both the phase line and the neutral line. Optionally, the inverter circuit in a three-phase inverter may include three phase lines and a neutral line, and a set of switching devices connected in series may be provided in each of the three phase lines and the neutral line.

[0039] Figure 1 The current control method shown may include steps S110 and S130.

[0040] Step S110: The controller sends a control signal to the switch assembly. The control signal can be used to control the switching devices in the switch assembly to close or open.

[0041] In some embodiments, before the photovoltaic storage system is connected to the grid, a control signal can be sent to the switch assembly via the controller to control the switching devices in the switch assembly to close or open, thereby realizing fault detection of the switching devices in the switch assembly.

[0042] Step S120: After the switch combination completes the closing or opening of the switching device in response to the control signal, the voltages at the input and output terminals of the switch combination are obtained.

[0043] In some embodiments, after the switch assembly receives a control signal from the controller, it can close or open the switching devices in the switch assembly according to the control signal. Optionally, different control signals can control different switching devices to close or open.

[0044] For example, such as Figure 3 As shown, the inverter is a three-phase inverter. The switch combination includes switching devices S1, S2, S3, S4, S5, S6, S7, and S8. The inverter circuit includes three phase lines and one neutral line. Switching devices S1 and S5 are located on the first phase line, switching devices S2 and S6 are located on the second phase line, switching devices S3 and S7 are located on the third phase line, and switching devices S4 and S8 are located on the neutral line. The controller can send different control signals to control the closing or opening of the switching devices. For example, the controller can send four sets of control signals: controlling the closing or opening of switching devices S1-S3; controlling the closing or opening of switching device S4; controlling the closing or opening of switching devices S5-S7; and controlling the closing or opening of switching device S8.

[0045] In some embodiments, after the switch combination completes the closing or opening operation of the switching device in response to a control signal, the controller can obtain the voltage at the input and output terminals of the switch combination. For example... Figure 3 The controller can sample voltages from seven groups: X_L1-X_N, X_L2-X_N, X_L3-X_N, Y_L1-Y_N, Y_L2-Y_N, Y_L3-Y_N, and X_N-Y_N, based on different control signals. For example, when all switches in the switch combination are open, the controller can send a control signal to the switch combination to close switch S8. In this case, the controller can sample voltages from X_N to Y_N. The input voltage of the switch combination can be X_N, and the output voltage can be Y_N.

[0046] In some embodiments, the voltages at the input and output terminals of the switch combination can be the effective values ​​of the voltages at the input and output terminals of the switch combination after the switch combination closes or opens in response to a control signal. Exemplarily, these effective voltage values ​​can be obtained by sampling the input and output voltages of the switch combination over a period of time. The voltage sampling values ​​can be obtained by calculating the average value over one mains cycle and further calculating the effective value of the AC voltage. Of course, other sampling periods and sampling methods can also be used, and this embodiment of the invention does not limit these methods.

[0047] In some embodiments, the optical storage system may include sampling unit 1 and sampling unit 2, both of which can be electrically connected to a controller. Sampling unit 1 can acquire the voltage at the input terminal of the switch combination and send that voltage to the controller; sampling unit 2 can acquire the voltage at the output terminal of the switch combination and send that voltage to the controller. Figure 4 As shown, Figure 4 This is a schematic diagram of the structure of a photovoltaic energy storage system provided in an embodiment of this application. Figure 4 In the process, sampling unit 1 can send the collected input voltage value of the switch combination to the controller, and sampling unit 2 can send the collected output voltage value of the switch combination to the controller.

[0048] Step S130: Determine whether the voltage at the input and output terminals of the switch combination meets the preset voltage conditions, and determine whether the switch combination has a fault based on the determination result.

[0049] In some embodiments, after the switch combination completes the closing or opening of the switching device in response to the control signal, the controller can obtain the voltage at the input and output terminals of the switch combination, and determine whether the switching device responding to the control signal is faulty based on whether the voltage at the input and output terminals of the switch combination at this time meets the preset voltage conditions.

[0050] In some embodiments, the preset voltage condition can be related to the output power of the photovoltaic-storage system, or it can be understood as being related to the output and design of the photovoltaic-storage system. For example, when the photovoltaic-storage system provides power to a home or small commercial space, the inverter in the system can be a single-phase inverter. When the photovoltaic-storage system provides power to a large commercial building or industrial facility, the inverter in the system can be a three-phase inverter. The output voltages of single-phase and three-phase inverters are different; for example, single-phase inverters typically output 220V or 110V AC, while three-phase inverters typically output 380V, 400V, or 415V. Furthermore, the circuitry included in the photovoltaic-storage system is designed differently depending on the application scenario. Therefore, the preset voltage condition will vary depending on the design of the photovoltaic-storage system, which is determined based on the required output power. Thus, the preset voltage condition can be related to the output power of the photovoltaic-storage system. The embodiments of this application can realize the combined detection of multi-state switching devices through different control signals. Combined with preset voltage conditions, the location of faulty switching devices can be accurately located, thereby improving the reliability of the detection results.

[0051] In some embodiments, the preset voltage condition may include the voltages at the input and output terminals of the switch combination when it is normally closed or closed. Therefore, by comparing the obtained voltages at the input and output terminals of the switch combination with the preset voltage condition, it can be determined whether the switch combination is faulty, and thus a fault detection result can be generated.

[0052] The switch combination detection method for a photovoltaic energy storage system proposed in this application can control the closing or opening of different switching devices in the switch combination via control signals, and determine whether the voltage at the input and output terminals of the switch combination meets preset voltage conditions to determine whether there is a fault in the switch combination. Because the detection logic of this method is simple and does not require complex circuit configuration, it reduces the complexity and cost of the photovoltaic energy storage system. Furthermore, this method can detect the combination of different switching devices closing or opening, combined with reasonable preset voltage conditions, thereby improving the accuracy of the detection results.

[0053] In inverter circuits, whether single-phase or three-phase inverters, the neutral line plays a crucial role. For example, the neutral line balances the load and provides a zero-potential reference. Therefore, the presence or absence of faults in the switching devices located on the neutral line is critical to the safe operation and performance of the photovoltaic-storage system. Prioritizing the inspection of switching devices located on the neutral line can narrow down the scope of troubleshooting for switch combinations, thereby improving the efficiency of fault location.

[0054] In some embodiments, a first sub-switching device and a second sub-switching device can be provided on the neutral line in the inverter circuit, and the first sub-switching device and the second sub-switching device are connected in series. It is understood that the first sub-switching device and the second sub-switching device both belong to a group of switching devices in a switching combination.

[0055] In some embodiments, the preset voltage condition may include the voltage at the input and output terminals of the switch combination being less than a first preset voltage value. Optionally, the first preset voltage value may be the voltage value at the input and output terminals of the switch combination when the first and second sub-switches on the neutral line are operating normally; for example, the first preset voltage value may be 20V.

[0056] In some embodiments, when the control signal controls the first sub-switch device to close and the second sub-switch device to open, and the voltages at the input and output terminals of the switch combination meet a preset voltage condition, it can be determined that the second sub-switch device has a sticking fault. Optionally, when the voltages at the input and output terminals of the switch combination are less than a first preset voltage value, it can be considered that the second sub-switch device is sticking.

[0057] In some embodiments, when the control signal controls the first sub-switch device to open and the second sub-switch device to close, and the voltages at the input and output terminals of the switch combination meet a preset voltage condition, it is determined that the first sub-switch device has a sticking fault. Optionally, when the voltages at the input and output terminals of the switch combination are less than a first preset voltage value, the first sub-switch device can be considered to be sticking.

[0058] by Figure 3 For example, in the switch combination, switching devices S1, S2, S3, S4, S5, S6, S7, and S8 are all in the open state. S8 can be the first sub-switch device located on the neutral line, and S4 can be the second sub-switch device located on the neutral line. The controller sends a control signal to the switch combination, which controls S8 to close. After S8 closes, the controller can obtain the voltage values ​​of the input terminal X_N and the output terminal Y_N of the switch combination, denoted as V1. After obtaining V1, the controller can continue to send control signals to the switch combination, this time controlling S8 to open and S4 to close. After S8 opens and S4 closes, the controller can obtain the voltage values ​​of the input terminal X_N and the output terminal Y_N of the switch combination as V2.

[0059] The presence of faults in switches S4 and S8 can be determined by checking whether V1 and V2 meet preset voltage conditions. Optionally, if V1 is less than a first preset voltage value, then switch S4 has a sticking fault; if V2 is less than the first preset voltage value, then switch S8 has a sticking fault. For example, the first preset voltage value can be 20V.

[0060] In some embodiments, the preset voltage condition may further include the voltage at the input and output terminals of the switch combination being greater than a second preset voltage value. Optionally, the second preset voltage value may be the voltage value at the input and output terminals of the switch combination when the first and second sub-switches on the neutral line are operating normally; for example, the second preset voltage value may be 5V.

[0061] In some embodiments, when the control signal controls both the first and second sub-switches to close, and the voltages at the input and output terminals of the switch combination meet a preset voltage condition, it can be determined that both the first and second sub-switches have an open-circuit fault, or either the first or second sub-switches have an open-circuit fault. Optionally, when the voltage at the input and output terminals of the switch combination is greater than a second preset voltage value, it can be considered that both the first and second sub-switches have an open-circuit fault, or either the first or second sub-switches have an open-circuit fault.

[0062] Continue with Figure 3 For example, in the switch combination, switching devices S1, S2, S3, S4, S5, S6, S7, and S8 are all in the open state. S8 can be the first sub-switch device located on the neutral line, and S4 can be the second sub-switch device located on the neutral line. Through the above embodiment, it is determined that neither S4 nor S8 has a sticking fault. The controller can send a control signal to the switch combination, which controls both S4 and S8 to close. When both S4 and S8 are closed, the controller can obtain the voltage value V3 at the input terminal X_N and the output terminal Y_N of the switch combination.

[0063] When V3 is greater than the second preset voltage value, it can be assumed that both S4 and S8 have an open-circuit fault, or that either of the switching devices in S4 and S8 has an open-circuit fault. For example, the second preset voltage value can be 5V.

[0064] In some embodiments, the controller acquires the input and output voltages of the switch combination by acquiring voltage sampling values ​​over a period of time. For example, the effective voltage value of X_N-Y_N can be obtained by the following formula: Where T1 to T2 is the sampling time, V n0 The effective voltage value of X_N-Y_N.

[0065] Since the neutral line can balance the load and provide a zero-point reference, it plays a very important role in the inverter circuit. Therefore, prioritizing the testing of switching devices located on the neutral line can narrow down the scope of troubleshooting for switching combinations, thereby improving the efficiency of fault location.

[0066] In some instances, once it is determined that the switching devices on the neutral line are functioning correctly, fault detection can continue on the switching devices on the phase lines of the inverter circuit.

[0067] In some instances, a third and fourth sub-switching device can be configured in at least one phase line of the inverter circuit, connected in series. It is understood that the third and fourth sub-switching devices belong to a group of switching devices in a switching combination.

[0068] In some embodiments, when all the switching devices on the neutral line are closed, the preset voltage condition may include the voltage at the input and output terminals of the switch combination being less than a third preset voltage value. Optionally, the third preset voltage value may be the voltage value at the input and output terminals of the switch combination when all the switching devices on the neutral line are normally closed; for example, the third preset voltage value may be 20V.

[0069] In some embodiments, when the control signal controls the third sub-switch to close and the fourth sub-switch to open, and the voltages at the input and output terminals of the switch combination meet a preset voltage condition, it can be determined that the fourth sub-switch has a sticking fault. Optionally, when the voltages at the input and output terminals of the switch combination are less than a third preset voltage value, it can be considered that the fourth sub-switch is sticking.

[0070] In some embodiments, when the control signal controls the third sub-switch device to open and the fourth sub-switch device to close, and the voltages at the input and output terminals of the switch combination meet a preset voltage condition, it is determined that the third sub-switch device has a sticking fault. Optionally, when the voltages at the input and output terminals of the switch combination are less than a preset third voltage value, the third sub-switch device can be considered to be sticking.

[0071] Figure 3 In the circuit, switching devices S4 and S8 in the switch combination are normally closed, while switching devices S1, S2, S3, S5, S6, and S7 are all open. S1 can be the third sub-switching device installed on at least one phase line, and S5 can be the fourth sub-switching device installed on at least one phase line. The controller sends a control signal to the switch combination, which controls S1 to close. After S1 closes, the controller can obtain the voltage value V4 of X_L1-X_N. After obtaining V4, the controller can continue to send control signals to the switch combination, which control S1 to open and S5 to close. After S1 opens and S5 closes, the controller can obtain the voltage value V5 of Y_L1-Y_N.

[0072] In some embodiments, the voltage values ​​of X_L1-X_N can be obtained based on the voltage values ​​of X_L1, Y_L1, and X_N-Y_N. For example, V4 can be obtained using the following formula: Where T1 to T2 is the sampling time, V 10 V4 is the effective value of the voltage. xl1n (t) represents the voltage sampling of X_L1, V yl1n (t) represents the voltage sampling of Y_L1.

[0073] Determine whether V4 and V5 meet preset voltage conditions to determine if S1 and S5 are faulty. Optionally, if V4 is less than a third preset voltage value, it can be considered that switching device S5 has a sticking fault; if V5 is less than a third preset voltage value, it can be considered that switching device S1 has a sticking fault. For example, the third preset voltage value can be 20V.

[0074] In some embodiments, the preset voltage condition may include the voltage at the input and output terminals of the switch combination being greater than a fourth preset voltage value. Optionally, the fourth preset voltage value may be the voltage value at the input and output terminals of the switch combination when all the switching devices on the neutral line are normally closed; for example, the fourth preset voltage value may be 20V.

[0075] In some embodiments, when the control signal controls both the third and fourth sub-switches to close, and the voltages at the input and output terminals of the switch combination meet a preset voltage condition, it can be determined that both the third and fourth sub-switches have an open-circuit fault, or either the third or fourth sub-switches have an open-circuit fault. Optionally, when the voltage at the input and output terminals of the switch combination is greater than a fourth preset voltage value, it can be considered that both the third and fourth sub-switches have an open-circuit fault, or either the third or fourth sub-switches have an open-circuit fault.

[0076] Figure 3 In the switch combination, switching devices S4 and S8 are normally closed, while switching devices S1, S2, S3, S5, S6, and S7 are all open. S1 can be the third sub-switching device installed on at least one phase line, and S5 can be the fourth sub-switching device installed on at least one phase line. Through the above embodiment, it is determined that neither S1 nor S5 has a sticking fault. The controller sends a control signal to the switch combination, which controls both S1 and S5 to close. When both S1 and S5 are closed, the controller can obtain the voltage value of X_L1-Y_L1 as V6.

[0077] In some embodiments, the voltage values ​​of X_L1-Y_L1 can be obtained based on the voltage values ​​of X_L1, Y_L1 and X_N-Y_N.

[0078] When V6 is greater than the fourth voltage preset value, it can be considered that both S1 and S5 have an open circuit fault, or that either of the switching devices in S1 and S5 has an open circuit fault. For example, the fourth voltage preset value can be 20V.

[0079] In some embodiments, the inverter circuit may include multiple phase lines, and a set of series-connected switching devices may be set on each phase line. The controller can control different switching devices to close or open by sending different control signals, thereby measuring the voltage at the input and output terminals of the switch combination, and further detecting whether the switching devices in the multiple phase lines are faulty by combining preset voltage conditions. For example, when the inverter circuit includes three phase lines and one neutral line, a set of switching devices on the neutral line can be set to close. The control signal can control the three switching devices closest to the inverter circuit in the three phase lines to close, obtaining the corresponding voltage values; then, these three switching devices are opened, and the control signal is sent to control the three switching devices closest to the grid in the three phase lines to close, obtaining the corresponding voltage values. These two corresponding voltage values ​​are then combined with preset voltage conditions to determine whether there is a sticking fault in the switching devices in the three phase lines; alternatively, the switching devices in all three phase lines can be closed to obtain the corresponding voltage values. If the voltage values ​​meet the preset voltage conditions, it can be determined whether there is an opening fault in the switching devices in these three phase lines. It should be understood that each phase line needs to be calculated.

[0080] by Figure 3 For example, in the switch combination, if switches S4 and S8 are normally closed, it can also be understood that all switches on the neutral line are normal and in the closed state, while switches S1, S2, S3, S5, S6, and S7 are all in the open state. The inverter circuit includes three phase lines. Switches S1 and S5 are located on the first phase line, switches S2 and S6 are located on the second phase line, and switches S3 and S7 are located on the third phase line. Switches S1, S2, and S3 are electrically connected to the inverter circuit, while switches S5, S6, and S7 are electrically connected to the power grid.

[0081] For example, the controller sends a control signal to the switch combination, which can control the closing of switches S1-S3. After S1-S3 is closed, the controller can obtain the voltage values ​​of X_L1-X_N as V41, X_L2-X_N as V42, and X_L3-X_N as V43. After obtaining V41, V42, and V43, the controller can continue to send a control signal to the switch combination, which controls S1-S3 to open and S5-S7 to close. After S1 is opened and S5 is closed, the controller can obtain the voltage values ​​of Y_L1-Y_N as V51, Y_L2-Y_N as V52, and Y_L3-Y_N as V53.

[0082] If V41 is less than the third preset voltage value, then switch S5 is considered to have a sticking fault; if V42 is less than the third preset voltage value, then switch S6 is considered to have a sticking fault; if V43 is less than the third preset voltage value, then switch S7 is considered to have a sticking fault. If V51 is less than the third preset voltage value, then switching device S1 is considered to have a sticking fault, and so on.

[0083] In some embodiments, V41 can be obtained by sampling using the following formula:

[0084] V 10 It is V41.

[0085] V42 can be obtained by sampling using the following formula:

[0086] V 20 It is V42.

[0087] V43 can be obtained by sampling using the following formula:

[0088] V 30 It is V43.

[0089] For example, a control signal can be sent to the switch combination via a controller, which can control S1-S3 and S5-S7 to be closed. When S1-S3 and S5-S7 are all closed, the controller can obtain the voltage value of X_L1-Y_L1 as V61, the voltage value of X_L2-Y_L2 as V62, and the voltage value of X_L3-Y_L3 as V63.

[0090] When V61 is greater than the fourth voltage preset value, it can be assumed that both S1 and S5 have open circuit faults, or that either of the switching devices in S1 and S5 has an open circuit fault, and so on. This will not be elaborated further here.

[0091] The following is based on Figure 3 , Figure 5 , Figure 6 and Figure 7 The embodiments of this application will be described using an example. Figure 3 This is a structural example diagram of a photovoltaic energy storage system shown in an embodiment of this application. The photovoltaic energy storage system is connected to the power grid. Figure 3 The photovoltaic-storage system shown includes a three-phase inverter. The inverter circuit includes three phase lines and one neutral line. Switching devices S1 and S5 are located on the first phase line, switching devices S2 and S6 are located on the second phase line, switching devices S3 and S7 are located on the third phase line, and switching devices S4 and S8 are located on the neutral line. Switching devices S1, S2, S3, and S4 are connected to the inverter circuit, while switching devices S5, S6, S7, and S8 are connected to the power grid. Figure 3 The switching device in this can be a relay.

[0092] Figure 5 This is a schematic flowchart of a start-up switch combination detection method proposed in an embodiment of this application. Since photovoltaics output energy based on sunlight, the output voltage of the photovoltaic management unit will fluctuate depending on the intensity of sunlight. Therefore, in order to keep the output voltage of the photovoltaic management unit stable and ensure that the output voltage of the photovoltaic-storage system meets the grid connection requirements, the bus VBUS needs to be raised to a system preset value before grid connection. For example, when raising the bus VBUS, the photovoltaic management unit takes priority over the energy storage management unit. The bus VBUS voltage is raised to the system preset value. When the photovoltaic-storage system includes a three-phase inverter, three system preset values ​​can be obtained, such as: VxL1yN*1.414*2+10V, VxL2yN*1.414*2+10V, and VxL3yN*1.414*2+10V. Typically, the maximum value among the three system preset values ​​is selected.

[0093] Figure 5 Before connecting a photovoltaic (PV) and energy storage (ESS) system to the grid, it's essential to first check if the grid voltage is sufficient for the system. If it is, then determine if the PV voltage is sufficient to activate the DC-DC converter module of the PV management unit (PV management unit). If the PV management unit's DC-DC converter module can activate, it should be started. Before activation, it's necessary to check if the VBUS voltage reaches a preset value. If it does, switch combination detection can begin. If the PV voltage cannot activate the DC-DC converter module, it's necessary to determine if the energy storage management unit's DC-DC converter module can activate. If the energy storage management unit's DC-DC converter module can activate, it's necessary to check if the VBUS voltage reaches a preset value. If it does, switch combination detection can begin.

[0094] Figure 6 Showing Figure 3 Judgment logic flow for the detection of switch combination in a solar-powered energy storage system. Figure 6 The switching device in the switch assembly can be a relay. Preset value 1 can be a first voltage preset value, preset value 2 can be a second voltage preset value, preset value 3 can be a third voltage preset value, and preset value 4 can be a fourth voltage preset value. In some embodiments, the first, second, third, and fourth voltage preset values ​​can be the same or different. Optionally, the first, third, and fourth voltage preset values ​​can all be 20V, and the second preset voltage value is 5V.

[0095] Figure 6 This includes steps S100 to S1100.

[0096] Step S100, when according to Figure 5 After the process shown confirms that the switch combination detection can be initiated, the controller can obtain the initial voltage V0 at the input and output terminals of the switch combination. At this time, all switching devices S1 to S8 are in the open state. When the initial voltage V0 meets the normal voltage value, the fault detection of the switching devices is activated.

[0097] In step S200, the controller sends a control signal to close the switching device S8 and acquires the voltage value V1 of the input terminal X_N and the output terminal Y_N in the switch combination. If V1 is less than the preset value 1, the switching device S4 is considered to be stuck. Otherwise, proceed to step S300 to continue the detection.

[0098] In step S300, the controller sends a control signal to disconnect the control switch S8.

[0099] In step S400, the controller sends a control signal to close the switching device S4 and obtains the voltage value V2 of X_N-Y_N. If V2 is less than the preset value 1, the switching device S8 is considered to be stuck. Otherwise, proceed to step S500 to continue the detection.

[0100] In step S500, the controller sends a control signal to disconnect the switching device S4.

[0101] In step S600, the controller sends a control signal to close switching devices S4 and S8 and obtains the voltage value V3. If V3 is greater than the preset value 2, it is considered that both switching devices S4 and S8 have an open circuit fault, or either switching device S4 or S8 has an open circuit fault. Otherwise, step S700 is adjusted, and the detection continues.

[0102] Step S700: Keep switching devices S4 and S8 closed.

[0103] In step S800, the controller sends a control signal to close switching devices S1-S3 and obtains the voltage V4 of X_N-Y_N. For example, the voltage value of X_L1-X_N can be obtained as V41, the voltage value of X_L2-X_N as V42, and the voltage value of X_L3-X_N as V43. When V4 is less than a preset value of 3, it is considered that the switching device of the corresponding phase line is stuck. Otherwise, proceed to step S900 to continue the detection.

[0104] In step S900, the controller sends a control signal to disconnect switching devices S1-S3.

[0105] In step S1000, the controller sends a control signal to close switching devices S5-S7 and acquires the voltage V5 of X_L(1-3)-X_N. For example, the voltage value of Y_L1-Y_N can be acquired as V51, the voltage value of Y_L2-Y_N as V52, and the voltage value of Y_L3-Y_N as V53. When V5 is less than a preset value of 3, it is considered that the switching device of the corresponding phase line is stuck. Otherwise, proceed to step S1100 to continue the detection.

[0106] In step S1100, the controller sends a control signal to disconnect switching devices S5-S7.

[0107] In step S1200, the controller sends a control signal to close switching devices S1-S3 and S5-S7, and obtains the voltage V6 of X_L(1-3)-Y_L(1-3). For example, the voltage value of X_L1-Y_L1 can be V61, the voltage value of X_L2-Y_L2 can be V62, and the voltage value of X_L3-Y_L3 can be V63. When V6 is greater than the preset value of 4, it is considered that there is an open circuit fault in the corresponding phase line switching device. Otherwise, all switching devices are normal.

[0108] Figure 7 Based on Figure 6 The shown diagram illustrates the timing logic of control steps S1-S8 in the judgment logic flow for switch combination detection. (See diagram for example.) Figure 7 As shown, the control signals can be divided into four groups: control switching device S8; control switching devices S5-S7; control switching device S4; and control switching devices S1-S3. This embodiment uses only four groups of control signals to perform fault detection on switching devices S1-S8. This detection method employs relatively simple detection logic and requires only a few control signals to complete the detection of the switch combination. Therefore, it can effectively reduce system complexity and system cost.

[0109] The switch combination detection method for a photovoltaic energy storage system proposed in this application can control the closing or opening of different switching devices in the switch combination via control signals, and determine whether the voltage at the input and output terminals of the switch combination meets preset voltage conditions to determine whether the switch combination has a fault. Because the detection logic of this method is simple and does not require complex circuit configuration, it reduces the complexity and cost of the photovoltaic energy storage system. Furthermore, this method can detect the combination of different switching devices closing or opening, combined with reasonable preset voltage conditions, thereby improving the accuracy of the detection results. Simultaneously, since the neutral line can balance the load and provide a zero-point reference, prioritizing the detection of switching devices located on the neutral line can narrow down the scope of switch combination troubleshooting, thereby improving the efficiency of fault location.

[0110] In some embodiments, the inverter circuit may include a first phase line, a second phase line, a third phase line, and a neutral line. The switch combination may include a first switch device, a second switch device, a third switch device, a fourth switch device, a fifth switch device, a sixth switch device, a seventh switch device, and an eighth switch device. The first and fifth switch devices are disposed in the first phase line and connected in series; the second and sixth switch devices are disposed in the second phase line and connected in series; the third and seventh switch devices are disposed in the third phase line and connected in series; and the fourth and eighth switch devices are disposed in the neutral line and connected in series. The first, second, third, and fourth switch devices are electrically connected to the inverter circuit, and the fifth, sixth, seventh, and eighth switch devices are electrically connected to the power grid.

[0111] In some embodiments, different control signals can be used to control the first, second, third, fourth, fifth, sixth, seventh, and eighth switching devices to close or open, so as to achieve fault detection of the switch combination.

[0112] For example, the control signal may satisfy one or more of the following: the control signal controls the closing or closing of the first switching device, the second switching device, and the third switching device; the control signal controls the closing or closing of the fourth switching device; the control signal controls the closing or closing of the fifth switching device, the sixth switching device, and the seventh switching device; the control signal controls the closing or closing of the eighth switching device.

[0113] by Figure 3For example, after starting the switch combination detection process, the switch combination can be detected through four sets of control signals. The control signals are: control switch device S8; control switch devices S5-S7; control switch device S4; and control switch devices S1-S3.

[0114] For example, the control signal may satisfy one or more of the following: the control signal controls the closing or closing of the first switching device, the sixth switching device, and the seventh switching device; the control signal controls the closing or closing of the fourth switching device; the control signal controls the closing or closing of the second switching device, the third switching device, and the fifth switching device; the control signal controls the closing or closing of the eighth switching device.

[0115] by Figure 3 For example, after starting the switch combination detection process, the switch combination can be detected through four sets of control signals. The control signals are: control switch device S8; control switch devices S1, S6, and S7; control switch device S4; and control switch devices S2, S3, and S5.

[0116] For example, the control signal may satisfy one or more of the following: the control signal controls the closing or closing of the first switching device, the third switching device, and the sixth switching device; the control signal controls the closing or closing of the fourth switching device; the control signal controls the closing or closing of the second switching device, the fifth switching device, and the seventh switching device; the control signal controls the closing or closing of the eighth switching device.

[0117] by Figure 3 For example, after starting the switch combination detection process, the switch combination can be detected through four sets of control signals. The control signals are: control switch device S8; control switch devices S1, S3, and S6; control switch device S4; and control switch devices S2, S5, and S7.

[0118] It should be understood that although multiple sets of control signals for different switching devices can be generated, the fault detection and judgment logic for the switching devices can adopt the methods and processes described in the above embodiments, and will not be repeated here.

[0119] This application embodiment enables fault detection of switch combinations using only four different sets of control signals. This detection method not only employs relatively simple detection logic but also eliminates the need for individual control signals for each switch device in the switch combination, requiring only a small number of control signals to complete fault detection. Therefore, it effectively reduces system complexity and cost while improving fault location efficiency. Furthermore, since the neutral line can balance the load and provide a zero-point reference, individual control can be applied to the switch devices located on the neutral line, narrowing the scope of troubleshooting for the switch combination and further improving fault location efficiency.

[0120] The method embodiments of this application have been described in detail above. Based on the above, this application also proposes a photoelectric storage system, which will be discussed below in conjunction with... Figure 8 The system embodiments of this application are described in detail below. It should be understood that the descriptions of the method embodiments above correspond to the descriptions of the system embodiments; therefore, any parts not described in detail can be referred to the foregoing method embodiments.

[0121] Figure 8 This is a schematic diagram of the structure of a photoelectric storage system provided in an embodiment of this application. Figure 8 The photovoltaic-storage system shown is electrically connected to the power grid. The photovoltaic-storage system includes:

[0122] A photovoltaic management unit may include photovoltaic modules and photovoltaic DC-DC modules;

[0123] Energy storage management unit, which may include battery module and battery DC-DC module;

[0124] An inverter may include an inverter circuit, a controller, and a switch assembly. The switch assembly may include multiple sets of switching devices, each set of switching devices may include two switching devices connected in series. The switch assembly is electrically connected to the power grid. The inverter circuit may include at least one phase line and a neutral line, and a set of switching devices is provided in each of the at least one phase line and the neutral line. The photovoltaic management unit and the energy storage management unit are both electrically connected to the inverter circuit. The inverter circuit is electrically connected to the switch assembly. The controller is electrically connected to the inverter circuit, the switch assembly, and the power grid, and can send control signals to the switch assembly. The control signals can be used to control the switching devices in the switch assembly to close or open.

[0125] In some embodiments, the switch combination can be used to respond to control signals, thereby enabling the switching devices to close or open. The photovoltaic energy storage system can be used to determine whether the voltages at the input and output terminals of the switch combination meet preset voltage conditions, and based on the determination result, to determine whether the switch combination is faulty. The preset voltage conditions are related to the output power of the photovoltaic energy storage system.

[0126] Furthermore, this application also proposes a computer-readable storage medium storing a computer program. When the computer program is executed by a computer, it implements the operation in the switch combination detection method of the optical storage system provided in the above embodiments. The specific steps will not be described in detail here.

[0127] This application also proposes a computer program that includes commands for executing the switch combination detection method for the optical storage system provided in the above embodiments.

[0128] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity / operation / object from another, and do not necessarily require or imply any such actual relationship or order between these entities / operations / objects; the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0129] For the device embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and relevant details can be found in the description of the method embodiments. The device embodiments described above are merely illustrative, and the units described as separate components may or may not be physically separate. Some or all of the modules can be selected according to actual needs to achieve the purpose of this application. Those skilled in the art can understand and implement this without creative effort.

[0130] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0131] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, television, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0132] The above are merely embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for detecting the switching combination of a photovoltaic energy storage system, characterized in that, The photovoltaic-storage system is electrically connected to the power grid. The system includes a photovoltaic management unit, an energy storage management unit, and an inverter. The photovoltaic management unit includes photovoltaic modules and a photovoltaic DC-DC module. The energy storage management unit includes a battery module and a battery DC-DC module. The inverter includes an inverter circuit, a controller, and the switch assembly. The switch assembly includes multiple sets of switching devices, each set consisting of two switches connected in series. The inverter circuit includes at least one phase line and a neutral line. Each of the at least one phase line and the neutral line is equipped with a set of switching devices. The photovoltaic management unit and the energy storage management unit are both electrically connected to the inverter circuit. The inverter circuit is electrically connected to the switch assembly. The switch assembly is electrically connected to the power grid. The controller is electrically connected to the inverter circuit, the switch assembly, and the power grid. The detection method includes: The controller sends a control signal to the switch assembly, the control signal being used to control the closing or opening of the switching device in the switch assembly; After the switch combination responds to the control signal to close or open the switching device, the voltage at the input terminal and the output terminal of the switch combination is obtained; Determine whether the voltages at the input and output terminals of the switch combination meet preset voltage conditions, and determine whether the switch combination is faulty based on the determination result. The preset voltage condition is related to the output power of the photovoltaic energy storage system.

2. The detection method according to claim 1, characterized in that, A first sub-switch device and a second sub-switch device are provided in the neutral line. The first sub-switch device and the second sub-switch device belong to a group of switches in the switch combination. The preset voltage condition includes that the voltage at the input terminal and the output terminal of the switch combination is less than a first preset voltage value. The step of determining whether the voltage at the input terminal and the output terminal of the switch combination meets the preset voltage condition, and determining whether the switch combination has a fault based on the determination result, includes: When the control signal controls the first sub-switch device to close and the second sub-switch device to open, and the voltages at the input and output terminals of the switch combination meet the preset voltage conditions, it is determined that the second sub-switch device has a sticking fault, and / or... When the control signal controls the first sub-switch device to open and the second sub-switch device to close, and the voltage at the input and output terminals of the switch combination meets the preset voltage condition, it is determined that the first sub-switch device has a sticking fault.

3. The detection method according to claim 2, characterized in that, The preset voltage condition includes that the voltage at the input terminal and the output terminal of the switch combination is greater than a second preset voltage value. The step of determining whether the voltage at the input terminal and the output terminal of the switch combination meets the preset voltage condition, and determining whether the switch combination is faulty based on the determination result, includes: When the control signal controls both the first sub-switch device and the second sub-switch device to close, and the voltage at the input and output terminals of the switch combination meets the preset voltage condition, it is determined that the first sub-switch device and / or the second sub-switch device has an open circuit fault.

4. The detection method according to claim 1, characterized in that, A third sub-switch device and a fourth sub-switch device are provided in at least one phase line. The third sub-switch device and the fourth sub-switch device belong to a group of switches in the switch combination. All switches in the group located on the neutral line are closed. The preset voltage condition includes that the voltage at the input terminal and the output terminal of the switch combination is less than a third preset voltage value. The step of determining whether the voltage at the input terminal and the output terminal of the switch combination meets the preset voltage condition, and determining whether the switch combination has a fault based on the determination result, includes: When the control signal controls the third sub-switch to close and the fourth sub-switch to open, and the voltages at the input and output terminals of the switch combination meet the preset voltage conditions, it is determined that the fourth sub-switch has a sticking fault, and / or... When the control signal controls the third sub-switch device to open and the fourth sub-switch device to close, and the voltage at the input and output terminals of the switch combination meets the preset voltage condition, it is determined that the third sub-switch device has a sticking fault.

5. The detection method according to claim 4, characterized in that, The preset voltage condition includes that the voltage at the input terminal and the output terminal of the switch combination is greater than a fourth preset voltage value. The step of determining whether the voltage at the input terminal and the output terminal of the switch combination meets the preset voltage condition, and determining whether the switch combination is faulty based on the determination result, includes: When the control signal controls both the third sub-switch and the fourth sub-switch to close, and the voltages at the input and output terminals of the switch combination meet the preset voltage conditions, it is determined that the third sub-switch and / or the fourth sub-switch has an open-circuit fault.

6. The detection method according to claim 1, characterized in that, The inverter circuit includes a first phase line, a second phase line, and a third phase line. A first switching device and a fifth switching device are disposed in the first phase line; a second switching device and a sixth switching device are disposed in the second phase line; a third switching device and a seventh switching device are disposed in the third phase line; and a fourth switching device and an eighth switching device are disposed in the neutral line. The first, second, third, and fourth switching devices are electrically connected to the inverter circuit, and the fifth, sixth, seventh, and eighth switching devices are electrically connected to the power grid.

7. The detection method according to claim 6, characterized in that, The control signal satisfies one or more of the following: The control signal controls the closing or closing of the first switching device, the second switching device, and the third switching device; The control signal controls the closing or closing of the fourth switching device; The control signal controls the closing or closing of the fifth, sixth, and seventh switching devices; The control signal controls the closing or closing of the eighth switching device.

8. The detection method according to claim 6, characterized in that, The control signal satisfies one or more of the following: The control signal controls the closing or closing of the first switching device, the sixth switching device, and the seventh switching device; The control signal controls the closing or closing of the fourth switching device; The control signal controls the closing or closing of the second, third, and fifth switching devices; The control signal controls the closing or closing of the eighth switching device.

9. The detection method according to claim 6, characterized in that, The control signal satisfies one or more of the following: The control signal controls the closing or closing of the first switching device, the third switching device, and the sixth switching device; The control signal controls the closing or closing of the fourth switching device; The control signal controls the closing or closing of the second switching device, the fifth switching device, and the seventh switching device; The control signal controls the closing or closing of the eighth switching device.

10. A photovoltaic energy storage system, characterized in that, The photovoltaic-storage system is electrically connected to the power grid, and the photovoltaic-storage system includes: A photovoltaic management unit, comprising photovoltaic modules and a photovoltaic DC-DC module; Energy storage management unit, the energy storage management unit includes a battery module and a battery DC-DC module; An inverter includes an inverter circuit, a controller, and a switch assembly. The switch assembly includes multiple sets of switching devices, each set comprising two switching devices connected in series. The switch assembly is electrically connected to the power grid. The inverter circuit includes at least one phase line and a neutral line, and each phase line and the neutral line has one set of the switching devices. A photovoltaic management unit and an energy storage management unit are both electrically connected to the inverter circuit. The inverter circuit is electrically connected to the switch assembly. The controller is electrically connected to the inverter circuit, the switch assembly, and the power grid to send control signals to the switch assembly. These control signals are used to control the switching devices in the switch assembly to close or open. The switch combination is used to respond to control signals to close or open the switching device. The optical energy storage system is used to determine whether the voltages at the input and output terminals of the switch combination meet preset voltage conditions, and to determine whether the switch combination is faulty based on the determination result. The preset voltage conditions are related to the output power of the optical energy storage system.

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