Control method and device of grid-connected inverter, controller, grid-connected system and medium

Abstract

The application provides a grid-connected inverter control method, device, controller, grid-connected system and medium. The grid-connected inverter control method comprises: when the grid-connected inverter is in an overcurrent protection state, monitoring the inverter output current of the grid-connected inverter; when the inverter output current of the grid-connected inverter is less than or equal to a preset current back difference value, controlling the grid-connected inverter to switch from the overcurrent protection state to a normal working state; wherein the preset current back difference value is less than or equal to the rated output current of the grid-connected inverter, and the preset current back difference value is greater than zero. The application can make the grid-connected inverter return to the normal working state when the inverter output current of the grid-connected inverter decreases to the preset current back difference value during high voltage ride through and when the grid-connected inverter is in the overcurrent protection state, avoid the situation that the high voltage ride through fails due to the overcurrent protection of the grid-connected inverter, successfully complete the high voltage ride through, and meet the relevant standard regulations.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of grid-connected technology, and particularly relates to a control method and device of a grid-connected inverter, a controller, a grid-connected system and a medium. BACKGROUND

[0002] GB / T 37408-2019 standard stipulates that when the grid voltage rises due to grid fault or disturbance, the A-type inverter must have high voltage ride-through capability, that is, within a certain voltage rise range and time interval, the A-type inverter can ensure continuous operation without being disconnected from the grid. However, at the moment of high voltage ride-through recovery, the grid voltage decreases and is lower than the output voltage of the grid-connected inverter, resulting in overcurrent of the grid-connected inverter current, and then the grid-connected inverter will be overcurrent protected and shut down, resulting in failure of high voltage ride-through and failure to meet the relevant standard stipulations. SUMMARY

[0003] The embodiments of the present application provide a control method, device, controller and grid-connected system of a grid-connected inverter and a medium to solve the problem that at the moment of high voltage ride-through recovery, the grid-connected inverter will be overcurrent protected and shut down, resulting in failure of high voltage ride-through of the grid-connected inverter and failure to meet the relevant standard stipulations.

[0004] In a first aspect, the embodiments of the present application provide a control method of a grid-connected inverter, comprising:

[0005] monitoring an inverter output current of the grid-connected inverter when the grid-connected inverter is in an overcurrent protection state;

[0006] controlling the grid-connected inverter to switch from the overcurrent protection state to a normal working state when the inverter output current of the grid-connected inverter is less than or equal to a preset current back-off value;

[0007] wherein the preset current back-off value is less than or equal to a rated output current of the grid-connected inverter and greater than zero.

[0008] In a possible implementation, before monitoring the inverter output current of the grid-connected inverter when the grid-connected inverter is in the overcurrent protection state, the control method of the grid-connected inverter further comprises:

[0009] controlling the grid-connected inverter to enter the overcurrent protection state when it is detected that the inverter output current of the grid-connected inverter is greater than or equal to a preset overcurrent protection value;

[0010] wherein the preset overcurrent protection value is greater than the rated output current.

[0011] In a possible implementation, when the grid-connected inverter is in the overcurrent protection state, an inverter loop in the grid-connected inverter stops working, and the inverter output current of the grid-connected inverter decreases;

[0012] When the grid-connected inverter is switched from the over-current protection state to the normal working state, the inverter loop in the grid-connected inverter resumes normal working.

[0013] In a possible implementation, after the grid-connected inverter is controlled to be switched from the over-current protection state to the normal working state, the control method of the grid-connected inverter further includes:

[0014] The inverter output voltage of the grid-connected inverter is controlled to track the grid voltage.

[0015] In a possible implementation, when the inverter output current of the grid-connected inverter is less than or equal to a preset current back-off value, the grid-connected inverter is controlled to be switched from the over-current protection state to the normal working state, including:

[0016] When the inverter output current of the grid-connected inverter is less than or equal to the preset current back-off value and lasts for a first preset time length, the grid-connected inverter is controlled to be switched from the over-current protection state to the normal working state.

[0017] In a possible implementation, a difference between the preset over-current protection value and the preset current back-off value satisfies that the grid-connected inverter will not repeatedly enter the over-current protection state.

[0018] In a second aspect, an embodiment of the present application provides a control device of a grid-connected inverter, including:

[0019] An over-current monitoring module is configured to monitor an inverter output current of the grid-connected inverter when the grid-connected inverter is in an over-current protection state.

[0020] A recovery module is configured to control the grid-connected inverter to be switched from the over-current protection state to a normal working state when the inverter output current of the grid-connected inverter is less than or equal to a preset current back-off value.

[0021] The preset current back-off value is less than or equal to a rated output current of the grid-connected inverter.

[0022] In a third aspect, an embodiment of the present application provides a controller including a memory and a processor, the memory is configured to store a computer program, and the processor is configured to call and run the computer program stored in the memory to execute the control method of the grid-connected inverter as described in the first aspect or any possible implementation of the first aspect.

[0023] In a fourth aspect, an embodiment of the present application provides a grid-connected system including a grid-connected inverter and a controller as described in the third aspect; the grid-connected inverter is controlled by the controller.

[0024] In a fifth aspect, an embodiment of the present application provides a computer readable storage medium, which stores a computer program. The computer program is executed by a processor to implement the steps of the control method of the grid-connected inverter according to the first aspect or any possible implementation manner of the first aspect.

[0025] The embodiment of the present application provides a control method and device of a grid-connected inverter, a controller, a grid-connected system and a medium. The method monitors an inverter output current of the grid-connected inverter when the grid-connected inverter is in an overcurrent protection state, and controls the grid-connected inverter to switch from the overcurrent protection state to a normal working state when it is monitored that the inverter output current of the grid-connected inverter is less than or equal to a preset current hysteresis value. The preset current hysteresis value is less than or equal to a rated output current of the grid-connected inverter and greater than zero. Through the above method, when the grid-connected inverter is in the overcurrent protection state during high voltage ride through, the grid-connected inverter can be restored to the normal working state when the inverter output current thereof is reduced to the preset current hysteresis value, so that the failure of the high voltage ride through caused by the overcurrent protection of the grid-connected inverter is avoided, the high voltage ride through can be successfully completed, and the relevant standard requirements are met. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort.

[0027] Figure 1 is a flowchart of the control method of the grid-connected inverter provided by the embodiment of the present application;

[0028] Figure 2 is a structural schematic diagram of the control device of the grid-connected inverter provided by the embodiment of the present application;

[0029] Figure 3 is a schematic diagram of the controller provided by the embodiment of the present application. DETAILED DESCRIPTION

[0030] In the following description, specific details are set forth such as particular system configurations, techniques, etc., in order to provide a thorough understanding of the embodiments of the present application. However, it should be apparent to those skilled in the art that the present application can be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.

[0031] In order to make the objects, technical solutions and advantages of the present application clearer, the following will be described by specific embodiments in conjunction with the drawings.

[0032] Referring to Figure 1 It shows the implementation flowchart of the control method of the grid-connected inverter provided by the embodiment of the present application. The execution subject of the control method of the grid-connected inverter can be a controller.

[0033] The control method of the grid-connected inverter can include:

[0034] In S101, when the grid-connected inverter is in the over-current protection state, the inverter output current of the grid-connected inverter is monitored.

[0035] As described above, when high voltage ride through occurs, at the moment of high voltage ride through recovery, the grid voltage will decrease and be lower than the inverter output voltage of the grid-connected inverter, resulting in over-current phenomenon of the grid-connected inverter, and then the grid-connected inverter will perform over-current protection and be in the over-current protection state.

[0036] When the grid-connected inverter is in the over-current protection state, the inverter output current of the grid-connected inverter will gradually decrease. In order to avoid high voltage ride through failure, the inverter output current of the grid-connected inverter needs to be monitored, and when the inverter output current meets certain conditions, the grid-connected inverter is restored to normal work, avoiding the inverter output current of the grid-connected inverter decreasing to 0 and resulting in high voltage ride through failure.

[0037] In S102, when the inverter output current of the grid-connected inverter is less than or equal to a preset current hysteresis value, the grid-connected inverter is controlled to switch from the over-current protection state to the normal working state.

[0038] The preset current hysteresis value is less than or equal to the rated output current of the grid-connected inverter and greater than zero.

[0039] The embodiment sets the preset current hysteresis value, which is greater than zero and less than or equal to the rated output current of the grid-connected inverter. The specific value can be determined according to actual requirements or related experiments, which is not specifically limited here. For example, the preset current hysteresis value can be set to a value close to the rated output current, and the preset current hysteresis value can be set to 80% or 90% of the rated output current, etc.

[0040] When it is monitored that the inverter output current of the grid-connected inverter is less than or equal to the preset current hysteresis value, it indicates that the inverter output current of the grid-connected inverter is no longer over-current. At this time, the grid-connected inverter can be controlled to switch from the over-current protection state to the normal working state, avoiding being in the over-current protection state all the time, making the inverter output current decrease to 0, and resulting in high voltage ride through failure.

[0041] The embodiment monitors the inverter output current of the grid-connected inverter when the grid-connected inverter is in the over-current protection state, and controls the grid-connected inverter to switch from the over-current protection state to the normal working state when it is monitored that the inverter output current of the grid-connected inverter is less than or equal to the preset current return difference value. The preset current return difference value is less than or equal to the rated output current of the grid-connected inverter and greater than zero. Through the above method, when the grid-connected inverter is in the over-current protection state during high voltage ride through, the grid-connected inverter can be restored to the normal working state when the inverter output current thereof is reduced to the preset current return difference value, thereby avoiding the failure of high voltage ride through due to over-current protection of the grid-connected inverter, successfully completing the high voltage ride through, and meeting the relevant standard requirements.

[0042] In some embodiments, before S101, the control method of the grid-connected inverter can further include:

[0043] When it is detected that the inverter output current of the grid-connected inverter is greater than or equal to the preset over-current protection value, the grid-connected inverter is controlled to enter the over-current protection state.

[0044] The preset over-current protection value is greater than the rated output current.

[0045] The preset over-current protection value is greater than the rated output current.

[0046] During normal working of the grid-connected inverter, the inverter output current of the grid-connected inverter can be monitored in real time. When the inverter output current of the grid-connected inverter is greater than or equal to the preset over-current protection value, it is determined that the inverter output current is too large, the controller enters the over-current protection state, and the inverter output current is gradually reduced to avoid damage to the device.

[0047] In some embodiments, when the grid-connected inverter is in the over-current protection state, the inverter circuit in the grid-connected inverter stops working, and the inverter output current of the grid-connected inverter decreases.

[0048] When the grid-connected inverter switches from the over-current protection state to the normal working state, the inverter circuit in the grid-connected inverter resumes normal working.

[0049] When the grid-connected inverter is in the over-current protection state, the inverter circuit in the grid-connected inverter stops working, and therefore the inverter output current of the grid-connected inverter gradually decreases. When the grid-connected inverter switches from the over-current protection state to the normal working state, the inverter circuit in the grid-connected inverter resumes normal working, and therefore the inverter output current of the grid-connected inverter gradually increases and returns to the normal value.

[0050] In some embodiments, after the grid-connected inverter is switched from the over-current protection state to the normal working state in S102, the method for controlling the grid-connected inverter further includes:

[0051] The inverter output voltage of the grid-connected inverter is controlled to track the grid voltage.

[0052] After the grid-connected inverter returns to the normal working state, the inverter output voltage of the grid-connected inverter needs to be controlled to track the grid voltage to achieve grid connection, thereby successfully completing the high-voltage ride-through.

[0053] In some embodiments, S102 can include:

[0054] When the inverter output current of the grid-connected inverter is less than or equal to the preset current back-off value and lasts for a first preset time length, the grid-connected inverter is switched from the over-current protection state to the normal working state.

[0055] To avoid repeated switching between the over-current protection state and the normal working state, in the embodiment, when it is monitored that the inverter output current of the grid-connected inverter is less than or equal to the preset current back-off value and the duration that the inverter output current of the grid-connected inverter is less than or equal to the preset current back-off value is greater than or equal to the first preset time length, the grid-connected inverter is switched from the over-current protection state to the normal working state, otherwise, the grid-connected inverter is kept in the over-current protection state.

[0056] The value of the first preset time length can be set according to actual needs, which is not specifically limited here. For example, the first preset time length can be 2 sampling periods, 3 sampling periods, etc.

[0057] In some embodiments, the difference between the preset over-current protection value and the preset current back-off value satisfies that the grid-connected inverter will not repeatedly enter the over-current protection state.

[0058] When the difference between the preset overcurrent protection value and the preset current back difference value is too small, when the inverter output current of the grid-connected inverter is greater than or equal to the preset overcurrent protection value, the grid-connected inverter is controlled to enter the overcurrent protection state, at this time, the inverter output current of the grid-connected inverter is reduced, and it is not necessary to reduce too much, so as to meet the condition that the inverter output current of the grid-connected inverter is less than or equal to the preset current back difference value, at this time, the grid-connected inverter is controlled to switch from the overcurrent protection state to the normal working state, the inverter output current of the grid-connected inverter is increased, and it is not necessary to increase too much, so as to meet the condition that the inverter output current of the grid-connected inverter is greater than or equal to the preset overcurrent protection value, and enter the overcurrent protection state, which will make the grid-connected inverter repeatedly switch between the overcurrent protection state and the normal working state. Therefore, the preset overcurrent protection value and the preset current back difference value need to have a certain difference, and the difference between the preset overcurrent protection value and the preset current back difference value meets the condition that the grid-connected inverter will not repeatedly switch between the overcurrent protection state and the normal working state. The size of the difference can be determined according to relevant experiments, and is not limited here.

[0059] The method provided by the embodiment can not only successfully implement high-voltage ride-through, but also avoid software bugs without changing software parameters, avoid increasing the cost of hardware modification without changing the circuit topology, and reduce the fluctuation range of the inverter output current during high-voltage ride-through recovery, thereby reducing the bus voltage fluctuation and avoiding the occurrence of bus overvoltage faults.

[0060] It should be understood that the size of the serial number of each step in the above embodiment does not mean the order of execution, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiment of the application.

[0061] The following is a device embodiment of the application, and for details not described in detail, reference can be made to the corresponding method embodiments described above.

[0062] Figure 2 The structure of the control device of the grid-connected inverter provided by the embodiment of the application is shown, only the parts related to the embodiment of the application are shown for convenience of description, and the details are described as follows:

[0063] As shown in Figure 2 The control device 20 of the grid-connected inverter can include an overcurrent monitoring module 21 and a recovery module 22.

[0064] The overcurrent monitoring module 21 is configured to monitor the inverter output current of the grid-connected inverter when the grid-connected inverter is in the overcurrent protection state;

[0065] The recovery module 22 is configured to control the grid-connected inverter to switch from the overcurrent protection state to the normal working state when the inverter output current of the grid-connected inverter is less than or equal to the preset current back difference value;

[0066] The preset current back-off value is less than or equal to the rated output current of the grid-connected inverter.

[0067] In a possible implementation, the control device 20 of the grid-connected inverter can further include an overcurrent protection module.

[0068] The overcurrent protection module is configured to, when the grid-connected inverter is in an overcurrent protection state, control the grid-connected inverter to enter the overcurrent protection state when it is detected that the inverter output current of the grid-connected inverter is greater than or equal to a preset overcurrent protection value before monitoring the inverter output current of the grid-connected inverter.

[0069] The preset overcurrent protection value is greater than the rated output current.

[0070] In a possible implementation, when the grid-connected inverter is in the overcurrent protection state, the inverter loop in the grid-connected inverter stops working, and the inverter output current of the grid-connected inverter decreases.

[0071] When the grid-connected inverter is switched from the overcurrent protection state to a normal working state, the inverter loop in the grid-connected inverter resumes normal working.

[0072] In a possible implementation, the recovery module 22 can be further configured to:

[0073] After controlling the grid-connected inverter to be switched from the overcurrent protection state to the normal working state, control the inverter output voltage of the grid-connected inverter to track the grid voltage.

[0074] In a possible implementation, the recovery module 22 is specifically configured to:

[0075] When the inverter output current of the grid-connected inverter is less than or equal to the preset current back-off value and lasts for a first preset time length, control the grid-connected inverter to be switched from the overcurrent protection state to the normal working state.

[0076] In a possible implementation, the difference between the preset overcurrent protection value and the preset current back-off value satisfies that the grid-connected inverter will not repeatedly enter the overcurrent protection state.

[0077] Figure 3 is a schematic diagram of the controller provided by the embodiment. As shown in the figure, the controller 4 of the embodiment includes a processor 40 and a memory 41. The memory 41 is configured to store a computer program 42, and the processor 40 is configured to invoke and run the computer program 42 stored in the memory 41 to perform the steps in each of the above control methods of the grid-connected inverter. Figure 3 Figure 1 ​S101-S102. Alternatively, the processor 40 is configured to invoke and run the computer program 42 stored in the memory 41, so as to realize the functions of the modules / units in the above-mentioned various apparatus embodiments, for example Figure 2 the functions of the modules / units 21-22.

[0078] For example, the computer program 42 can be divided into one or more modules / units, which are stored in the memory 41 and executed by the processor 40 to complete the present application. The one or more modules / units can be a series of computer program instruction segments capable of completing a specific function, which are used to describe the execution process of the computer program 42 in the controller 4. For example, the computer program 42 can be divided into Figure 2 the modules / units 21-22.

[0079] The controller 4 can include, but is not limited to, the processor 40 and the memory 41. Those skilled in the art can understand that the controller 4 can include more or less components, or combine certain components, or different components, for example, the controller can also include an input / output device, a network access device, a bus, etc. Figure 3 The controller 4 is only an example and does not constitute a limitation on the controller 4, and can include more or less components than the illustration, or combine certain components, or different components, for example, the controller can also include an input / output device, a network access device, a bus, etc.

[0080] The processor 40 can be a central processing unit (CPU), and can also be other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor.

[0081] The memory 41 can be an internal storage unit of the controller 4, such as a hard disk or a memory of the controller 4. The memory 41 can also be an external storage device of the controller 4, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the controller 4. Further, the memory 41 can also include both the internal storage unit and the external storage device of the controller 4. The memory 41 is used to store the computer program and other programs and data required by the controller. The memory 41 can also be used to temporarily store data that has been output or is to be output.

[0082] Corresponding to the above controller, the embodiment of the present application also provides a grid-connected system, comprising a grid-connected inverter and any of the above controllers; the grid-connected inverter is controlled by the controller.

[0083] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the above-mentioned division of each functional unit and module is exemplified, and in actual application, the above-mentioned functions can be completed by different functional units and modules according to needs, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. Each functional unit and module in the embodiment can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or software. In addition, the specific names of each functional unit and module are only for easy distinction, and do not limit the protection scope of the present application. The specific working process of the unit and module in the above system can refer to the corresponding process in the foregoing method embodiments, which will not be described here.

[0084] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described or recorded in detail in a certain embodiment can be referred to the related description of other embodiments.

[0085] Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized in electronic hardware or a combination of computer software and electronic hardware. Whether the functions are executed in hardware or software depends on the specific application and design constraints of the technical solution. A person skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0086] In the embodiments of the present application, it should be understood that the disclosed apparatuses / controllers and methods can be implemented in other ways. For example, the above-described apparatus / controller embodiments are merely schematic. The division of the modules or units is merely logical function division. There can be another division manner in actual implementation. For example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interfaces, devices or units, and can be electrical, mechanical or other forms.

[0087] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e., can be located in one place or distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the embodiments.

[0088] In addition, each functional unit in each embodiment of the present application can be integrated into a processing unit, or each unit can be physically present separately, or two or more units can be integrated into one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0089] The integrated module / unit, if realized in the form of a software functional unit and sold or used as an independent product, can be stored in a computer readable storage medium. Based on this understanding, all or part of the processes in the above-described embodiment methods can also be completed by a computer program instructing related hardware, and the computer program can be stored in a computer readable storage medium. When the processor executes the computer program, the steps of the above-described each grid-connected inverter control method embodiment can be implemented. The computer program includes computer program code, which can be in the form of source code, object code, executable file or some intermediate form. The computer readable medium can include any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium, etc.

[0090] The above-described embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A control method of a grid-connected inverter, characterized by, The method comprises the following steps: monitoring the inverter output current of the grid-connected inverter when the grid-connected inverter is in an overcurrent protection state; wherein, when high voltage ride through occurs, at the moment of high voltage ride through recovery, the grid voltage will decrease and be lower than the inverter output voltage of the grid-connected inverter, resulting in overcurrent phenomenon of the grid-connected inverter, and then the grid-connected inverter will perform overcurrent protection and be in the overcurrent protection state; controlling the grid-connected inverter to switch from the overcurrent protection state to a normal working state when the inverter output current of the grid-connected inverter is less than or equal to a preset current back difference value; wherein, the preset current back difference value is less than or equal to the rated output current of the grid-connected inverter and greater than zero; when the grid-connected inverter is in the overcurrent protection state, the inverter circuit in the grid-connected inverter stops working, and the inverter output current of the grid-connected inverter decreases; when the grid-connected inverter switches from the overcurrent protection state to the normal working state, the inverter circuit in the grid-connected inverter resumes normal working.

2. The control method of the grid-connected inverter according to claim 1, characterized by, Before the step of monitoring the inverter output current of the grid-connected inverter when the grid-connected inverter is in the overcurrent protection state, the control method of the grid-connected inverter further comprises the following steps: controlling the grid-connected inverter to enter the overcurrent protection state when it is detected that the inverter output current of the grid-connected inverter is greater than or equal to a preset overcurrent protection value; wherein, the preset overcurrent protection value is greater than the rated output current.

3. The control method of the grid-connected inverter according to claim 1, characterized by, After the step of controlling the grid-connected inverter to switch from the overcurrent protection state to the normal working state, the control method of the grid-connected inverter further comprises the following step: controlling the inverter output voltage of the grid-connected inverter to track the grid voltage.

4. The control method of the grid-connected inverter according to any one of claims 1 to 3, characterized by, The step of controlling the grid-connected inverter to switch from the overcurrent protection state to the normal working state when the inverter output current of the grid-connected inverter is less than or equal to the preset current back difference value comprises the following step: controlling the grid-connected inverter to switch from the overcurrent protection state to the normal working state when the inverter output current of the grid-connected inverter is less than or equal to the preset current back difference value and lasts for a first preset time length.

5. The control method of the grid-connected inverter according to claim 2, characterized by, The difference between the preset overcurrent protection value and the preset current back difference value satisfies that the grid-connected inverter will not repeatedly enter the overcurrent protection state.

6. A control device of a grid-connected inverter, characterized by comprising: The method comprises the following steps: an overcurrent monitoring module, configured to monitor the inverter output current of the grid-connected inverter when the grid-connected inverter is in an overcurrent protection state; wherein, when high voltage ride through occurs, at the moment of high voltage ride through recovery, the grid voltage will decrease and be lower than the inverter output voltage of the grid-connected inverter, resulting in overcurrent phenomenon of the grid-connected inverter, and then the grid-connected inverter will perform overcurrent protection and be in the overcurrent protection state; a recovery module, configured to control the grid-connected inverter to switch from the overcurrent protection state to a normal working state when the inverter output current of the grid-connected inverter is less than or equal to a preset current back difference value; The preset current back difference value is less than or equal to a rated output current of the grid-connected inverter; when the grid-connected inverter is in an over-current protection state, an inverter loop in the grid-connected inverter stops working, and an inverter output current of the grid-connected inverter is reduced; when the grid-connected inverter is switched from the over-current protection state to a normal working state, the inverter loop in the grid-connected inverter resumes normal working.

7. A controller characterized by comprising: The grid-connected inverter comprises a memory and a processor, the memory is used for storing a computer program, and the processor is used for calling and running the computer program stored in the memory to execute the control method of the grid-connected inverter according to any one of claims 1 to 5.

8. A grid-connected system characterized by, The grid-connected inverter is controlled by the controller.

9. A computer-readable storage medium storing a computer program, the computer program comprising instructions that, when executed by a computer, cause the computer to perform the method of any one of claims 1 to 8. The computer program is executed by the processor to implement the steps of the control method of the grid-connected inverter according to any one of claims 1 to 5.

Images