Networking mode switching control method and device for new energy grid-connected inverter

Abstract

The invention provides a new energy grid-connected inverter and grid-building mode switching control method and device, and relates to the technical field of grid connection. According to the method, the short-circuit ratio of the alternating-current system connected with the grid-connected inverter is obtained in real time, and the short-circuit ratio is used for measuring the strength of the alternating-current system connected with the grid-connected inverter; the current control mode of the grid-connected inverter is obtained, and the current control mode is a network following type control mode or a network constructing type control mode; a first preset threshold value and a second preset threshold value are obtained, and the first preset threshold value is larger than the second preset threshold value; and switching the current control mode according to the short circuit ratio, a first preset threshold value and a second preset threshold value. Through real-time monitoring and dynamic adjustment of the control mode, fluctuation of the short-circuit ratio can be effectively handled, it is ensured that the system is kept stable under different operation conditions, and the fault risk caused by short circuit can be reduced.

Description

Technical Field

[0001] The present application relates to the field of grid-connected technology, and in particular to a method and device for controlling switching between a new energy grid-connected inverter and a grid-connected network mode. Background Art

[0002] In power systems, the short circuit ratio (SCR) is an important parameter for measuring system stability. Fluctuations in the SCR value may be caused by a variety of factors, including load changes, generator start-up and shutdown, network topology adjustments, and external interference. Such fluctuations will affect the dynamic characteristics of the system, and thus affect the synchronization of the generator and the overall stability of the system. In the case of large fluctuations in the SCR, traditional stability control strategies are often unable to effectively respond, resulting in serious consequences such as oscillation, loss of step, or even collapse of the system. Summary of the invention

[0003] The present disclosure provides a new energy grid-connected inverter and a grid-connected network mode switching control method and a device thereof, so as to at least solve the problem in the related art that the traditional stable control strategy is often unable to effectively cope with the situation of large fluctuations in SCR.

[0004] The first aspect of the present application proposes a method for switching control between a new energy grid-connected inverter and a grid-forming mode, including: obtaining in real time the short-circuit ratio of the AC system to which the grid-connected inverter is connected, wherein the short-circuit ratio is used to measure the strength of the AC system to which the grid-connected inverter is connected; obtaining the current control mode of the grid-connected inverter, wherein the current control mode is a grid-following control mode or a grid-forming control mode; obtaining a preset first preset threshold and a second preset threshold, wherein the first preset threshold is greater than the second preset threshold; switching the current control mode according to the short-circuit ratio, the first preset threshold and the second preset threshold.

[0005] According to one embodiment of the present application, in response to the current control mode being a grid-forming control mode, the current control mode is switched according to the short-circuit ratio, the first preset threshold and the second preset threshold, including: in response to the short-circuit ratio being greater than the first preset threshold, the grid-connected inverter is switched from the grid-forming control mode to the grid-following control mode; or, in response to the short-circuit ratio being greater than the first preset threshold and lasting for a duration greater than the first preset duration, the grid-connected inverter is switched from the grid-forming control mode to the grid-following control mode.

[0006] According to one embodiment of the present application, in response to the current control mode being a grid-following control mode, the current control mode is switched according to the short-circuit ratio, the first preset threshold and the second preset threshold, including: in response to the short-circuit ratio being less than the second preset threshold, the grid-connected inverter is switched from the grid-following control mode to the grid-forming control mode; or, in response to the short-circuit ratio being less than the second preset threshold and the duration being greater than the second preset duration, the grid-connected inverter is switched from the grid-following control mode to the grid-forming control mode.

[0007] According to one embodiment of the present application, the short-circuit ratio of the AC system to which the grid-connected inverter is connected is obtained in real time, including: obtaining the short-circuit capacity and the rated system power of the AC system; and taking the ratio of the short-circuit capacity to the rated system power as the short-circuit ratio.

[0008] According to one embodiment of the present application, the short-circuit ratio of the AC system to which the grid-connected inverter is connected is obtained in real time, including: obtaining the rated AC voltage, rated system power and AC system impedance of the AC system; and determining the short-circuit ratio of the AC system according to the rated AC voltage, rated system power and AC system impedance.

[0009] The second aspect of the present application proposes a new energy grid-connected inverter grid-following and grid-forming mode switching control device, including: a first acquisition module, used to acquire the short-circuit ratio of the AC system to which the grid-connected inverter is connected in real time, wherein the short-circuit ratio is used to measure the strength of the AC system to which the grid-connected inverter is connected; a second acquisition module, used to acquire the current control mode of the grid-connected inverter, wherein the current control mode is a grid-following control mode or a grid-forming control mode; a third acquisition module, used to acquire a preset first preset threshold value and a second preset threshold value, wherein the first preset threshold value is greater than the second preset threshold value; a mode switching module, used to switch the current control mode according to the short-circuit ratio, the first preset threshold value and the second preset threshold value.

[0010] According to one embodiment of the present application, in response to the current control mode being a grid-forming control mode, the mode switching module is also used to: in response to the short-circuit ratio being greater than a first preset threshold, switch the grid-connected inverter from the grid-forming control mode to the grid-following control mode; or, in response to the short-circuit ratio being greater than the first preset threshold and the duration being greater than the first preset duration, switch the grid-connected inverter from the grid-forming control mode to the grid-following control mode.

[0011] According to one embodiment of the present application, in response to the current control mode being a grid-following control mode, the mode switching module is also used to: in response to the short-circuit ratio being less than a second preset threshold, switch the grid-connected inverter from the grid-following control mode to the grid-forming control mode; or, in response to the short-circuit ratio being less than the second preset threshold and the duration being greater than the second preset duration, switch the grid-connected inverter from the grid-following control mode to the grid-forming control mode.

[0012] According to one embodiment of the present application, the first acquisition module is further used to: acquire the short-circuit capacity and rated system power of the AC system; and use the ratio of the short-circuit capacity to the rated system power as the short-circuit ratio.

[0013] According to one embodiment of the present application, the first acquisition module is further used to: acquire the rated AC voltage, rated system power and AC system impedance of the AC system; and determine the short-circuit ratio of the AC system based on the rated AC voltage, rated system power and AC system impedance.

[0014] The third aspect embodiment of the present application proposes an electronic device, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, and the instructions are executed by the at least one processor to implement the new energy grid-connected inverter and grid-connected networking mode switching control method as described in the first aspect embodiment of the present application.

[0015] The fourth aspect embodiment of the present application proposes a non-transitory computer-readable storage medium storing computer instructions, wherein the computer instructions are used to implement the new energy grid-connected inverter and grid-connecting mode switching control method as described in the first aspect embodiment of the present application.

[0016] The fifth aspect of the present application provides a computer program product, including a computer program, which, when executed by a processor, implements the new energy grid-connected inverter and grid-connected networking mode switching control method as described in the first aspect of the present application.

[0017] The technical solution provided by the embodiments of the present disclosure brings at least the following beneficial effects: the present application can effectively cope with the fluctuation of the short-circuit ratio through real-time monitoring and dynamic adjustment of the control mode, ensure that the system remains stable under different operating conditions, and reduce the risk of failure caused by short circuit; through effective control strategies, equipment failures and downtime are reduced, thereby reducing operation and maintenance costs and improving the economic benefits of the system.

[0018] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0020] Figure 1 It is a schematic diagram of an exemplary implementation of a new energy grid-connected inverter and a grid-connecting mode switching control method shown in an embodiment of the present application.

[0021] Figure 2It is a schematic diagram of an exemplary implementation of a new energy grid-connected inverter and a grid-connecting mode switching control method shown in an embodiment of the present application.

[0022] Figure 3 It is a schematic diagram of an exemplary implementation of a new energy grid-connected inverter and a grid-connecting mode switching control method shown in an embodiment of the present application.

[0023] Figure 4 A new energy grid-connected inverter and a grid-connecting mode switching control device are shown in an embodiment of the present application.

[0024] Figure 5 It is a connection diagram of a new energy grid-connected inverter shown in an embodiment of the present application.

[0025] Figure 6 It is a schematic diagram of an electronic device shown in one embodiment of the present application. DETAILED DESCRIPTION

[0026] Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0027] Figure 1 is a schematic diagram of an exemplary implementation of a new energy grid-connected inverter and a grid-connected grid mode switching control method shown in the present application, such as Figure 1 As shown, the mode switching control method of the grid-connected inverter includes the following steps:

[0028] S101, obtaining in real time a short-circuit ratio of an AC system to which the grid-connected inverter is connected, wherein the short-circuit ratio is used to measure the strength of the AC system to which the grid-connected inverter is connected.

[0029] As a feasible method, when obtaining the short-circuit ratio of the AC system to which the grid-connected inverter is connected in real time, the short-circuit capacity and the rated system power of the AC system are first obtained; and then the ratio of the short-circuit capacity to the rated system power is used as the short-circuit ratio.

[0030] As another feasible method, when obtaining the short-circuit ratio of the AC system to which the grid-connected inverter is connected in real time, the rated AC voltage, rated system power and AC system impedance of the AC system are first obtained; then the short-circuit ratio of the AC system is determined based on the rated AC voltage, rated system power and AC system impedance.

[0031] The above two methods of obtaining the short-circuit ratio of the AC system to which the grid-connected inverter is connected can be expressed by the following formula:

[0032]

[0033] In the above formula, SCR represents the short-circuit ratio of the AC system to which the grid-connected inverter is connected, S ac Indicates the short-circuit capacity of the AC system, P dN Indicates the rated system power of the AC system, U pcc represents the rated AC voltage of the AC system, and Z represents the AC system impedance of the AC system.

[0034] S102, obtaining a current control mode of the grid-connected inverter, wherein the current control mode is a grid-following control mode or a grid-building control mode.

[0035] New energy grid-connected inverters are important devices that convert renewable energy (such as solar energy and wind energy) into AC power that meets the requirements of the power grid. During the grid-connected process, the control mode of the inverter directly affects the stability and efficiency of its operation. At present, there are mainly two control modes: grid-following control mode and grid-building control mode.

[0036] The grid-following control mode means that the inverter follows the frequency and voltage changes of the grid when connected to the grid. This control mode is suitable for strong grid environments and can make full use of the stability of the grid to ensure the coordinated operation of the inverter and the grid. However, in the case of weak or extremely weak grids, the grid-following control mode may cause stability problems, and even fail to achieve stable operation in extremely weak grids.

[0037] The grid-building control mode is a control method that actively builds grid operating conditions and is suitable for extremely weak and weak grids. This mode enables the inverter to operate independently of the grid state and has better stability, especially in poor grid conditions, and can effectively maintain system stability and power quality. However, in a strong grid environment, grid-building control may cause system instability.

[0038] S103: Obtain a preset first threshold and a second preset threshold, wherein the first preset threshold is greater than the second preset threshold.

[0039] The first preset threshold and the second preset threshold can be set according to actual conditions. The first preset threshold is greater than the second preset threshold.

[0040] S104, switching the current control mode according to the short-circuit ratio, the first preset threshold and the second preset threshold.

[0041] As a feasible method, if the current short-circuit ratio is greater than the first preset threshold, it means that the system operation is stable and the current grid-following control mode can be maintained; if the current short-circuit ratio is lower than the first preset threshold but higher than the second preset threshold, it may be necessary to evaluate whether to switch to the grid-forming control mode to enhance the stability of the system; when the short-circuit ratio is lower than the second preset threshold, the system operation enters a critical state, and it should be immediately switched to the grid-forming control mode to ensure the safety and stability of the system.

[0042] As another feasible method, if the current short-circuit ratio is less than the second preset threshold, the current grid-forming control mode can be maintained; if the current short-circuit ratio is lower than the first preset threshold but higher than the second preset threshold, it may be necessary to evaluate whether to switch to the grid-following control mode to enhance the stability of the system; when the short-circuit ratio is greater than the first preset threshold, the system operation enters a critical state, and should be immediately switched to the grid-following control mode to ensure the safety and stability of the system.

[0043] The embodiments of the present application can effectively cope with fluctuations in the short-circuit ratio by real-time monitoring and dynamically adjusting the control mode, thereby ensuring that the system remains stable under different operating conditions and reducing the risk of failures caused by short circuits; through effective control strategies, equipment failures and downtime are reduced, thereby reducing operation and maintenance costs and improving the economic benefits of the system.

[0044] Figure 2 is a schematic diagram of an exemplary implementation of a new energy grid-connected inverter and a grid-connected grid mode switching control method shown in the present application, such as Figure 2 As shown, the mode switching control method of the grid-connected inverter includes the following steps:

[0045] S201, obtaining in real time the short-circuit ratio of the AC system to which the grid-connected inverter is connected, wherein the short-circuit ratio is used to measure the strength of the AC system to which the grid-connected inverter is connected.

[0046] S202, obtaining a current control mode of the grid-connected inverter, wherein the current control mode is a grid-following control mode or a grid-building control mode.

[0047] S203: Obtain a preset first preset threshold and a second preset threshold, wherein the first preset threshold is greater than the second preset threshold.

[0048] Regarding the specific implementation of steps S201 to S203, reference may be made to the specific introduction of the relevant parts in the above embodiments, which will not be elaborated here.

[0049] S204, in response to the current control mode being a grid-forming control mode and in response to the short-circuit ratio being greater than a first preset threshold, switching the grid-connected inverter from the grid-forming control mode to the grid-following control mode.

[0050] If the current control mode is the grid-forming control mode, the short-circuit ratio of the AC system to which the grid-connected inverter is connected is monitored in real time. If the short-circuit ratio is detected to be greater than a first preset threshold, the grid-connected inverter is immediately switched from the grid-forming control mode to the grid-following control mode.

[0051] S205 , in response to the current control mode being the grid-following control mode and in response to the short-circuit ratio being less than a second preset threshold, switching the grid-connected inverter from the grid-following control mode to the grid-forming control mode.

[0052] If the current control mode is the grid-following control mode, the short-circuit ratio of the AC system to which the grid-connected inverter is connected is monitored in real time. If the short-circuit ratio is detected to be less than a second preset threshold, the grid-connected inverter is immediately switched from the grid-following control mode to the grid-building control mode.

[0053] By dynamically switching the control mode according to the SCR value, the embodiment of the present application enables the system to quickly respond and adjust the operating strategy when the grid strength changes. This adaptability helps to maintain the overall stability of the power system and reduce the risk of grid failure. When the grid is weak and the load fluctuates greatly, the grid-forming control mode can improve the system's anti-interference ability and reduce the risk of equipment damage due to overload or voltage fluctuations. When the grid conditions are good, the use of the grid-following control mode can improve the power generation efficiency and maximize the utilization of renewable energy. When the grid conditions are poor, switching to the grid-forming control mode can ensure the safe operation of the inverter.

[0054] Figure 3 is a schematic diagram of an exemplary implementation of a new energy grid-connected inverter and a grid-connected grid mode switching control method shown in the present application, such as Figure 3 As shown, the mode switching control method of the grid-connected inverter includes the following steps:

[0055] S301, obtaining in real time the short-circuit ratio of the AC system to which the grid-connected inverter is connected, wherein the short-circuit ratio is used to measure the strength of the AC system to which the grid-connected inverter is connected.

[0056] S302, obtaining a current control mode of the grid-connected inverter, wherein the current control mode is a grid-following control mode or a grid-building control mode.

[0057] S303: Obtain a preset first preset threshold and a second preset threshold, wherein the first preset threshold is greater than the second preset threshold.

[0058] Regarding the specific implementation of steps S301 to S303, reference may be made to the specific introduction of the relevant parts in the above embodiments, which will not be elaborated here.

[0059] S304, in response to the current control mode being a grid-forming control mode, and in response to the short-circuit ratio being greater than a first preset threshold and the duration being greater than a first preset duration, switching the grid-connected inverter from the grid-forming control mode to the grid-following control mode.

[0060] A first preset duration is pre-set, and if the current control mode is a grid-forming control mode, and the short-circuit ratio is greater than a first preset threshold and the duration is greater than the first preset duration, the grid-connected inverter is switched from the grid-forming control mode to the grid-following control mode.

[0061] S305, in response to the current control mode being a grid-following control mode, and in response to the short-circuit ratio being less than a second preset threshold and the duration being greater than a second preset duration, switching the grid-connected inverter from the grid-following control mode to the grid-forming control mode.

[0062] A second preset duration is pre-set, and if the current control mode is a grid-following control mode, and the short-circuit ratio is less than a second preset threshold and the duration is greater than the second preset duration, the grid-connected inverter is switched from the grid-following control mode to the grid-forming control mode.

[0063] The values ​​of the first preset time length and the second preset time length may be equal or unequal, and may be set according to specific circumstances.

[0064] When the control mode is switched in the embodiment of the present application, a certain time delay (a first preset time length and a second preset time length) is set to help avoid unnecessary switching due to instantaneous fluctuations and avoid system instability caused by frequent switching.

[0065] Figure 4 Schematic diagram of a new energy grid-connected inverter and grid-connected network mode switching control device shown in the present application, such as Figure 4 As shown, the new energy grid-connected inverter and grid-connected network mode switching control device 400 includes a first acquisition module 401, a second acquisition module 402, a third acquisition module 403 and a mode switching module 404, wherein:

[0066] The first acquisition module 401 is used to acquire in real time the short-circuit ratio of the AC system to which the grid-connected inverter is connected, wherein the short-circuit ratio is used to measure the strength of the AC system to which the grid-connected inverter is connected.

[0067] The second acquisition module 402 is used to acquire the current control mode of the grid-connected inverter, wherein the current control mode is a grid-following control mode or a grid-building control mode.

[0068] The third acquisition module 403 is used to acquire a preset first preset threshold and a second preset threshold, wherein the first preset threshold is greater than the second preset threshold.

[0069] The mode switching module 404 is used to switch the current control mode according to the short circuit ratio, the first preset threshold and the second preset threshold.

[0070] Through real-time monitoring and dynamic adjustment of the control mode, this device can effectively cope with fluctuations in the short-circuit ratio, ensure that the system remains stable under different operating conditions, and reduce the risk of failures caused by short circuits. Through effective control strategies, it can reduce equipment failures and downtime, thereby reducing operation and maintenance costs and improving the economic benefits of the system.

[0071] Further, in response to the current control mode being a grid-forming control mode, the mode switching module 404 is also used to: in response to the short-circuit ratio being greater than a first preset threshold, switch the grid-connected inverter from the grid-forming control mode to the grid-following control mode; or, in response to the short-circuit ratio being greater than the first preset threshold and the duration being greater than the first preset duration, switch the grid-connected inverter from the grid-forming control mode to the grid-following control mode.

[0072] Further, in response to the current control mode being the grid-following control mode, the mode switching module 404 is also used to: in response to the short-circuit ratio being less than a second preset threshold, switch the grid-connected inverter from the grid-following control mode to the grid-forming control mode; or, in response to the short-circuit ratio being less than the second preset threshold and the duration being greater than the second preset duration, switch the grid-connected inverter from the grid-following control mode to the grid-forming control mode.

[0073] Furthermore, the first acquisition module 401 is further used to: acquire the short-circuit capacity and the rated system power of the AC system; and use the ratio of the short-circuit capacity to the rated system power as the short-circuit ratio.

[0074] Furthermore, the first acquisition module 401 is further used to: acquire the rated AC voltage, rated system power and AC system impedance of the AC system; and determine the short circuit ratio of the AC system according to the rated AC voltage, rated system power and AC system impedance.

[0075] Figure 5 This is a schematic diagram of a system connection of a new energy grid-connected inverter shown in this application. Figure 5As shown, the system is composed of a new energy grid-connected inverter (501), a new energy grid-connected inverter grid-connected and grid-connected mode switching control device (502, which has the same structure as the new energy grid-connected inverter grid-connected and grid-connected mode switching control device introduced above), a control mode (503), and a power grid (504). Among them, the new energy grid-connected inverter (501) obtains the SCR value of the power grid (504) through the technical algorithm of the new energy grid-connected inverter grid-connected and grid-connected mode switching control device (502), and then adaptively determines whether the control mode (503) should work in a grid-connected control mode or a grid-connected control mode according to the obtained SCR, thereby effectively improving the stability of the new energy grid-connected inverter (501) when the SCR fluctuates greatly.

[0076] In order to implement the above embodiment, the present application embodiment further proposes an electronic device 600, such as Figure 6 As shown, the electronic device 600 includes: a processor 601 and a memory 602 that is communicatively connected to the processor, the memory 602 stores instructions that can be executed by at least one processor, and the instructions are executed by at least one processor 601 to implement the new energy grid-connected inverter and grid-connected network mode switching control method as shown in the above embodiment.

[0077] In order to implement the above embodiments, the embodiments of the present application also propose a non-transitory computer-readable storage medium storing computer instructions, wherein the computer instructions are used to enable the computer to implement the new energy grid-connected inverter and grid-connected network mode switching control method as shown in the above embodiments.

[0078] In order to implement the above embodiments, the embodiments of the present application also propose a computer program product, including a computer program, which, when executed by a processor, implements the new energy grid-connected inverter and grid-connected network mode switching control method as shown in the above embodiments.

[0079] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0080] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0081] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0082] It should be noted that in the embodiments of the present application, certain software, components, models and other existing solutions in the industry may be mentioned, and they should be regarded as exemplary. Their purpose is only to illustrate the feasibility of implementing the technical solution of the present application, but it does not mean that the applicant has or will necessarily use the solution.

[0083] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A method for controlling the switching of a new energy grid-connected inverter and a grid-connected network mode, characterized in that: include: Acquire in real time the short-circuit ratio of the AC system to which the grid-connected inverter is connected, wherein the short-circuit ratio is used to measure the strength of the AC system to which the grid-connected inverter is connected; Acquire a current control mode of the grid-connected inverter, wherein the current control mode is a grid-following control mode or a grid-building control mode; Obtaining a preset first preset threshold and a second preset threshold, wherein the first preset threshold is greater than the second preset threshold; The current control mode is switched according to the short-circuit ratio, the first preset threshold, and the second preset threshold.

2. The method according to claim 1, characterized in that In response to the current control mode being a meshed control mode, switching the current control mode according to the short-circuit ratio, the first preset threshold, and the second preset threshold includes: In response to the short-circuit ratio being greater than the first preset threshold, switching the grid-connected inverter from a grid-building control mode to a grid-following control mode; or, In response to the short-circuit ratio being greater than the first preset threshold and the duration being greater than the first preset duration, the grid-connected inverter is switched from a grid-building control mode to a grid-following control mode.

3. The method according to claim 2, characterized in that In response to the current control mode being a grid-following control mode, switching the current control mode according to the short-circuit ratio, the first preset threshold, and the second preset threshold includes: In response to the short-circuit ratio being less than the second preset threshold, switching the grid-connected inverter from a grid-following control mode to a grid-building control mode; or, In response to the short-circuit ratio being less than the second preset threshold and the duration being greater than the second preset duration, the grid-connected inverter is switched from a grid-following control mode to a grid-forming control mode.

4. The method according to claim 3, characterized in that The real-time acquisition of the short-circuit ratio of the AC system to which the grid-connected inverter is connected includes: Obtaining the short-circuit capacity and rated system power of the AC system; The ratio of the short-circuit capacity to the rated system power is used as the short-circuit ratio.

5. The method according to claim 3, characterized in that: The real-time acquisition of the short-circuit ratio of the AC system to which the grid-connected inverter is connected includes: Obtaining the rated AC voltage, rated system power and AC system impedance of the AC system; The short circuit ratio of the AC system is determined according to the rated AC voltage, the rated system power and the AC system impedance.

6. A new energy grid-connected inverter and grid-connected network mode switching control device, characterized in that: include: A first acquisition module is used to acquire in real time the short-circuit ratio of the AC system to which the grid-connected inverter is connected, wherein the short-circuit ratio is used to measure the strength of the AC system to which the grid-connected inverter is connected; A second acquisition module is used to acquire a current control mode of the grid-connected inverter, wherein the current control mode is a grid-following control mode or a grid-building control mode; A third acquisition module, used to acquire a preset first preset threshold and a second preset threshold, wherein the first preset threshold is greater than the second preset threshold; A mode switching module is used to switch the current control mode according to the short-circuit ratio, the first preset threshold and the second preset threshold.

7. The device according to claim 6, characterized in that In response to the current control mode being a meshing control mode, the mode switching module is further configured to: In response to the short-circuit ratio being greater than the first preset threshold, switching the grid-connected inverter from a grid-building control mode to a grid-following control mode; or, In response to the short-circuit ratio being greater than the first preset threshold and the duration being greater than the first preset duration, the grid-connected inverter is switched from a grid-building control mode to a grid-following control mode.

8. The device according to claim 7, characterized in that In response to the current control mode being the grid-following control mode, the mode switching module is further configured to: In response to the short-circuit ratio being less than the second preset threshold, switching the grid-connected inverter from a grid-following control mode to a grid-building control mode; or, In response to the short-circuit ratio being less than the second preset threshold and the duration being greater than the second preset duration, the grid-connected inverter is switched from a grid-following control mode to a grid-forming control mode.

9. An electronic device, comprising: at least one processor; as well as, a memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the method according to any one of claims 1 to 5.

10. A non-transitory computer-readable storage medium storing computer instructions, wherein: The computer instructions are used to cause the computer to execute the method according to any one of claims 1-5.

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