Voltage source type blower and converter control method and device thereof

Abstract

The present disclosure provides a voltage source type fan and a converter control method and device thereof. The converter control method can include: in response to a grid-side voltage of a converter being less than or equal to a predetermined grid-side voltage threshold, maintaining a magnitude and an angular frequency of a virtual internal electromotive force associated with the converter as a steady-state magnitude and a steady-state angular frequency, respectively, wherein the virtual internal electromotive force is used to control the converter; and adjusting a virtual impedance to which the virtual internal electromotive force is applied according to the grid-side voltage and the virtual internal electromotive force.

Description

Technical Field

[0001] This disclosure relates to the field of wind power generation, specifically to a converter control method, converter control device, computer-readable storage medium, and control equipment for voltage source wind turbines. Background Technology

[0002] As the penetration rate of new energy power generation in the power system gradually increases, the power system exhibits characteristics such as weakened grid strength and reduced inertia. This increases the risks to the safety and stability of the power system, hindering its construction and development.

[0003] To enhance the supporting role of wind power generation in the power system, the development and application of voltage source type (i.e., grid-connected) wind turbines (i.e., wind turbine generators) have received widespread attention. Low-voltage faults caused by factors such as line short circuits are common fault types in power systems. In such cases, due to limitations in hardware overcurrent capacity, the control circuitry of voltage source type wind turbines may also enter the nonlinear region, further leading to transient instability. Therefore, it is necessary to effectively prevent the risks associated with low-voltage faults for voltage source type wind turbines. Summary of the Invention

[0004] The purpose of this disclosure is to provide a converter control method, converter control device, computer-readable storage medium, and control equipment for a voltage source wind turbine, which can provide effective grid strength support during low-voltage faults and fully utilize the capacity of the voltage source wind turbine.

[0005] According to embodiments of this disclosure, a converter control method for a voltage source wind turbine is provided. The converter control method includes: in response to the grid-side voltage of the converter being less than or equal to a predetermined grid-side voltage threshold, maintaining the amplitude and angular frequency of a virtual internal potential associated with the converter at a steady-state amplitude and steady-state angular frequency, respectively, wherein the virtual internal potential is used to control the converter, and the predetermined grid-side voltage threshold is determined based on and less than the rated grid-side voltage; and adjusting the virtual impedance to which the virtual internal potential is applied based on the grid-side voltage and the virtual internal potential.

[0006] According to another embodiment of this disclosure, a converter control device for a voltage source wind turbine is provided. The converter control device includes: an internal potential control unit configured to: maintain the amplitude and angular frequency of a virtual internal potential associated with the converter as steady-state amplitude and steady-state angular frequency, respectively, in response to the grid-side voltage of the converter being less than or equal to a predetermined grid-side voltage threshold, wherein the virtual internal potential is used to control the converter, and the predetermined grid-side voltage threshold is determined based on and less than the rated grid-side voltage; and a virtual impedance adjustment unit configured to: adjust the virtual impedance to which the virtual internal potential is applied, based on the grid-side voltage and the virtual internal potential.

[0007] According to embodiments of the present disclosure, a computer-readable storage medium storing a computer program is provided, which, when executed by a processor, implements the converter control method for a voltage source type wind turbine as described above.

[0008] According to an embodiment of this disclosure, a control device is provided, the control device comprising: a processor; and a memory storing a computer program, wherein when the computer program is executed by the processor, the converter control method for a voltage source type wind turbine as described above is implemented.

[0009] According to embodiments of this disclosure, a converter is provided, the converter including the converter control device or control equipment as described above.

[0010] According to embodiments of this disclosure, a voltage source type fan is provided, the voltage source type fan including the converter as described above.

[0011] The converter control method, converter control device, computer-readable storage medium, control equipment, converter, and voltage source wind turbine according to embodiments of the present disclosure can achieve at least one of the following technical effects: enabling the voltage source wind turbine to achieve stable grid-connected operation during low-voltage faults in the power grid; by adjusting the virtual impedance and / or other control parameters of the voltage source wind turbine, the wind turbine can still operate in voltage source control mode during low-voltage faults, exhibiting voltage source characteristics externally, without needing to switch to current source control mode; and effectively improving the strength support of the voltage source wind turbine for the power system or power grid during low-voltage faults, thereby enhancing the transient stability of the power system or power grid. Attached Figure Description

[0012] The above and other objects and features of this disclosure will become clearer from the following description taken in conjunction with the accompanying drawings.

[0013] Figure 1 This is a voltage source control block diagram of a grid-side converter according to an embodiment of the present disclosure.

[0014] Figure 2 This is a flowchart of a converter control method for a voltage source type wind turbine according to an embodiment of the present disclosure.

[0015] Figure 3 This is a flowchart of a converter control method for a voltage source type wind turbine according to an embodiment of the present disclosure.

[0016] Figure 4 This is a flowchart of a converter control method for a voltage source type wind turbine according to an embodiment of the present disclosure.

[0017] Figure 5This is a flowchart of a converter control method for a voltage source type wind turbine according to an embodiment of the present disclosure.

[0018] Figure 6 This is a block diagram of a converter control device for a voltage source type wind turbine according to an embodiment of the present disclosure.

[0019] Figure 7 This is a block diagram of a control device for a voltage source type fan according to an embodiment of the present disclosure. Detailed Implementation

[0020] In the field of wind power generation, grid-connected wind turbines refer to wind turbine units that use grid-connected control methods to achieve synchronization with the power grid. Their external characteristics are similar to those of a voltage source, hence they are also called "voltage source wind turbines." Grid-following wind turbines refer to wind turbine units that use phase-locked loops to monitor the grid phase to achieve synchronization with the power grid. Their external characteristics are similar to those of a current source, hence they are also called "current source wind turbines."

[0021] In wind power generation using voltage source (i.e., grid-connected) wind turbines, when a low-voltage fault is detected in the grid, the control mode of the grid-side converter is typically switched from voltage source control mode to current source (i.e., grid-connected) control mode. Then, when the low-voltage fault ends, it switches back from current source control mode to voltage source control mode. Thus, during a low-voltage fault, the wind turbine exhibits current source characteristics externally, unable to provide strength support to the power system. Furthermore, this control method is not feasible in islanded application scenarios.

[0022] In view of the difficulties in the existing technology, this invention proposes a converter control strategy for voltage source wind turbines, which can be executed during low voltage faults in the power grid. Under the premise of ensuring that the wind turbine does not disconnect from the grid abnormally, it can make full use of the effective capacity of the wind turbine to improve the transient stability of the power system.

[0023] The following description, in conjunction with the accompanying drawings, provides specific embodiments to aid the reader in gaining a comprehensive understanding of the methods, apparatus, and / or systems described herein. However, upon understanding this disclosure, various changes, modifications, and equivalents of the methods, apparatus, and / or systems described herein will become apparent. For example, the order of operations described herein is merely illustrative and is not limited to those orders set forth herein, but may be altered as will become clear upon understanding this disclosure, except for operations that must occur in a specific order. Furthermore, for clarity and conciseness, descriptions of features known in the art may be omitted.

[0024] The features described herein may be implemented in different forms and should not be construed as limited to the examples described herein. Rather, the examples described herein are provided only to illustrate some of the many feasible ways of implementing the methods, apparatus, and / or systems described herein, which will become clear upon understanding the disclosure of this application.

[0025] As used herein, the term “and / or” includes any one of the associated listed items and any combination of any two or more.

[0026] Although terms such as “first,” “second,” and “third” may be used herein to describe various components, assemblies, regions, layers, or parts, these components, assemblies, regions, layers, or parts should not be limited by these terms. Rather, these terms are used only to distinguish one component, assembly, region, layer, or part from another. Thus, without departing from the teaching of the examples described herein, the first component, first assembly, first region, first layer, or first part referred to as the first component, first assembly, first region, first layer, or first part may also be referred to as the second component, second assembly, second region, second layer, or second part.

[0027] The terminology used herein is for the purpose of describing various examples only and is not intended to limit disclosure. Unless the context clearly indicates otherwise, the singular form is intended to include the plural form as well. The terms “comprising,” “including,” and “having” indicate the presence of the described features, quantities, operations, components, elements, and / or combinations thereof, but do not preclude the presence or addition of one or more other features, quantities, operations, components, elements, and / or combinations thereof.

[0028] Unless otherwise defined, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains upon understanding this disclosure. Unless expressly defined herein, terms (such as those defined in a general dictionary) shall be interpreted as having a meaning consistent with their meaning in the context of the relevant field and in this disclosure, and shall not be interpreted in an idealized or overly formalistic manner.

[0029] Furthermore, in the description of the examples, detailed descriptions of well-known related structures or functions will be omitted when it is believed that such detailed descriptions would lead to a vague interpretation of this disclosure.

[0030] Figure 1 This is a voltage source control block diagram of a grid-side converter according to an embodiment of the present disclosure.

[0031] like Figure 1As shown, the grid-side converter 101 of the wind turbine can adopt a voltage source control strategy. The grid-side converter 101 is connected to the power grid 102. In the control module of the grid-side converter 101, the synchronization unit 103 outputs the angular frequency and phase angle θ of the virtual internal potential. p The reactive power / voltage control unit 104 outputs the amplitude U of the virtual internal potential. p Then, having angular frequency and phase angle θ p and amplitude U p The virtual internal potential is input to the current command generation stage 105. The current command generation stage 105 uses virtual impedance for control. The virtual internal potential is applied to the virtual impedance, and the virtual internal potential divided by the virtual impedance yields the output virtual current command. The virtual current command is then limited by the selectable current command limiter 106. Finally, after current closed-loop processing by the current loop 107 and modulation processing by SVPWM (Space Vector Pulse Width Modulation) 108, voltage source control of the grid-side converter 101 is achieved.

[0032] In this way, voltage source control of the wind turbine can be achieved, that is, a voltage source type wind turbine can be realized. The converter control method according to this disclosure can be used to control grid-side converters, but this disclosure is not limited to this and can also be applied to the control of other types of converters.

[0033] Figure 2 This is a flowchart of a converter control method for a voltage source type wind turbine according to an embodiment of the present disclosure.

[0034] A grid low-voltage fault can be identified when the grid-side voltage of the converter is too low (e.g., less than or equal to a predetermined grid-side voltage threshold). To avoid the series of problems caused by grid low-voltage faults, converter control needs to be performed in voltage source control mode without switching to current source control mode.

[0035] For example, in response to the grid-side voltage of the converter being less than or equal to a predetermined grid-side voltage threshold, the amplitude and angular frequency of the virtual internal potential associated with the converter are maintained at steady-state amplitude and steady-state angular frequency, respectively, wherein the virtual internal potential is used to control the converter.

[0036] like Figure 2 As shown, it can be determined whether the grid-side voltage of the converter is less than or equal to a predetermined voltage threshold by monitoring the grid-side voltage of the converter (step S21). In embodiments of this disclosure, the predetermined grid-side voltage threshold may be determined based on the rated grid-side voltage and is less than the rated grid-side voltage, for example, 0.9 times or less of the rated grid-side voltage.

[0037] In response to the grid-side voltage of the converter being less than or equal to a predetermined grid-side voltage threshold, the amplitude and angular frequency of the virtual internal potential associated with the converter are maintained at steady-state amplitude and steady-state angular frequency, respectively (step S22), wherein the virtual internal potential is used to control the converter. As shown above, the voltage source control of the converter is achieved using the virtual internal potential.

[0038] In embodiments of this disclosure, the steady-state amplitude and steady-state angular frequency can be the amplitude and angular frequency of the virtual internal potential when the grid-side voltage is within the steady-state grid-side voltage range, respectively, where the steady-state grid-side voltage range is higher than a predetermined grid-side voltage threshold. For example, the predetermined grid-side voltage threshold is 0.9 times the rated grid-side voltage, and the steady-state grid-side voltage range is greater than 0.9 times the rated grid-side voltage and less than 1.1 times the rated grid-side voltage. In other words, the steady-state grid-side voltage range can include the grid-side voltage under normal grid operation conditions, and the steady-state amplitude and steady-state angular frequency can represent the amplitude and angular frequency under normal operation conditions before or during a grid low-voltage fault. Thus, by locking the steady-state amplitude and steady-state angular frequency, it is possible to prevent low-voltage faults from causing the various control components of the wind turbine to malfunction under normal conditions.

[0039] After locking the steady-state amplitude and steady-state angular frequency, the virtual impedance to which the virtual internal potential is applied can be adjusted according to the grid-side voltage and the virtual internal potential (step S23).

[0040] In embodiments of this disclosure, the virtual impedance can be adjusted based on a target virtual impedance value determined according to the grid-side voltage and the virtual internal potential. The following will combine... Figure 3 Describe it.

[0041] Figure 3 This is a flowchart of a converter control method for a voltage source type wind turbine according to an embodiment of the present disclosure.

[0042] like Figure 3 As shown, when adjusting the virtual impedance to which the virtual internal potential is applied based on the grid-side voltage and the virtual internal potential, the target value of the virtual impedance can be determined based on the grid-side voltage, the virtual internal potential and the maximum withstand current of the converter (step S31).

[0043] For example, the virtual impedance target value can be calculated according to the following formula (1):

[0044]

[0045] Among them, R v X represents the virtual resistance. v U represents virtual reactance. p and θ p U represents the magnitude and phase (i.e., phase angle) of the virtual internal potential, respectively. g and θg These represent the amplitude and phase of the voltage at the wind turbine's grid connection point, respectively; I MAX This indicates the maximum withstand current value of the converter.

[0046] After determining the target value of the virtual impedance, the virtual impedance can be adjusted according to the target value (step S32).

[0047] Due to faults such as a drop in grid voltage, the wind turbine's output current increases rapidly. The current indicated by the grid-side current command may reach the upper limit of the limiting circuit, i.e., the upper limit of the predetermined current range. At this time, the wind turbine will exhibit current source characteristics. In order to enable the wind turbine to overcome the low-voltage fault with voltage source characteristics, it is necessary to adjust control parameters such as virtual impedance to reduce the current indicated by the grid-side current command, so that the grid-side current command exits the limiting state.

[0048] For example, after adjusting the virtual impedance to which the virtual internal potential is applied based on the grid-side voltage and the virtual internal potential, the virtual impedance can be adjusted according to the grid-side current command of the converter so that the amplitude of the grid-side current is within a predetermined current range.

[0049] Figure 4 This is a flowchart of a converter control method for a voltage source type wind turbine according to an embodiment of the present disclosure.

[0050] like Figure 4 As shown, the grid-side current command of the converter can be obtained (step S41). For example, the grid-side current command can be obtained from the converter's controller. During the converter's control process, the converter's controller outputs a grid-side current command to the converter so that the converter outputs current according to the grid-side current command. However, the current indicated by the grid-side current command may exceed the converter's maximum withstand current value, causing the grid-side current command to be in a "limited state". To remove the grid-side current command from the limited state, the virtual impedance needs to be adjusted.

[0051] Therefore, according to the grid-side current command of the converter, the virtual impedance is adjusted so that the amplitude of the grid-side current is within a predetermined current range (step S42). In embodiments of this disclosure, the upper limit of the predetermined current range can be the maximum withstand current value of the converter. For example, the maximum withstand current value can be more than one times the rated grid-side current.

[0052] Furthermore, the lower limit of the predetermined current range can be determined based on the upper limit of the current and the predetermined current margin. For example, the difference between the upper limit of the current and the lower limit of the predetermined current range can be less than or equal to the predetermined current margin, which can be determined based on the rated grid-side current. For example, the predetermined current margin can be 0.02 times or less of the rated grid-side current.

[0053] As mentioned above, by adjusting the virtual impedance according to the grid-side current command of the converter, the amplitude of the grid-side current can be ensured to be within a predetermined current range. The following section combines... Figure 5 Further describe how to adjust the virtual impedance.

[0054] Figure 5 This is a flowchart of a converter control method for a voltage source type wind turbine according to an embodiment of the present disclosure.

[0055] like Figure 5 As shown, it can be determined whether the current indicated by the grid-side current command is greater than the upper limit of the predetermined current range (step S51).

[0056] In practical applications, due to deviations introduced by sampling and control processes, the grid-side current command may remain in a shallowly limited state (e.g., the current value indicated by the grid-side current command (e.g., 1.22 times the rated grid-side current) is slightly greater than the converter's maximum withstand current (e.g., 1.2 times the rated grid-side current)) or a deeply limited state (e.g., the current value indicated by the grid-side current command (e.g., 3 times the rated grid-side current) is much greater than the converter's maximum withstand current (e.g., 1.2 times the rated grid-side current)). Therefore, the virtual impedance needs to be further adjusted based on whether the grid-side current command is in a limited state.

[0057] When adjusting the virtual impedance, the virtual impedance can be increased or decreased according to a predetermined slope. In embodiments of this disclosure, the predetermined slope represents a ramp-like slope rather than a step-like slope to avoid the virtual impedance changing too rapidly. For example, the predetermined range can be greater than zero and less than or equal to a predetermined slope value.

[0058] If it is determined that the current indicated by the grid-side current command is greater than the upper limit of the predetermined current range, the virtual impedance can be increased at a slope within the predetermined range (step S53). By slowly increasing the virtual impedance, the current value indicated by the grid-side current command or the amplitude of the grid-side current is reduced, thereby causing the grid-side current to exit the limiting state. When it is determined that the current indicated by the grid-side current command is less than or equal to the upper limit of the predetermined current range, the next step can be executed.

[0059] Further, it can be determined whether the current indicated by the grid-side current command is less than the lower limit of a predetermined current range (step S52). If it is determined that the current indicated by the grid-side current command is less than the upper limit of a predetermined current range, the virtual impedance can be reduced according to the slope of a predetermined range (step S54). By slowly reducing the virtual impedance, the current value indicated by the grid-side current command or the amplitude of the grid-side current is increased, thereby improving the short-circuit current level.

[0060] During low-voltage grid faults, wind turbines must be able to provide a large short-circuit current to support the fault; therefore, it is necessary to maximize the utilization of turbine capacity. Consequently, the virtual impedance needs to be adjusted based on grid-side current commands and a lower current limit determined by a predetermined current margin to enhance grid strength support.

[0061] Thus, by adjusting the virtual impedance, the current indicated by the grid-side current command can be kept within a predetermined current range; that is, the amplitude of the grid-side current can be kept within a predetermined current range. This part of the processing can end when it is determined that the current indicated by the grid-side current command is greater than or equal to the upper limit of the predetermined current range.

[0062] The following is combined with Figure 6 and Figure 7 A converter control device and control equipment are described that can perform the converter control method described above.

[0063] Figure 6 This is a block diagram of a converter control device 6 for a voltage source type wind turbine according to an embodiment of the present disclosure.

[0064] like Figure 6 As shown, the converter control device may include an internal potential control unit 61 and a virtual impedance adjustment unit 62.

[0065] The internal potential control unit 61 can be configured to maintain the amplitude and angular frequency of the virtual internal potential associated with the converter at a steady-state value and steady-state angular frequency, respectively, in response to the grid-side voltage of the converter being less than or equal to a predetermined grid-side voltage threshold, wherein the virtual internal potential is used to control the converter. The virtual impedance adjustment unit 62 can be configured to adjust the virtual impedance to which the virtual internal potential is applied, based on the grid-side voltage and the virtual internal potential.

[0066] For reference Figures 1 to 5 The converter control method for a voltage source type wind turbine described in the embodiments of this disclosure is used to understand the corresponding operation of each unit in the converter control device 6, and will not be repeated here for the sake of brevity.

[0067] Figure 7 This is a block diagram of the control device 7 for a voltage source type fan according to an embodiment of the present disclosure.

[0068] like Figure 7 As shown, the control device 7 may include: a processor 71; and a memory 72 storing a computer program 73. When the computer program 73 is executed by the processor, it implements the converter control method for the voltage source type wind turbine as described above. In the embodiments of this disclosure, when the computer program 73 is executed by the processor 71, it can implement the reference... Figures 1 to 5The following operations are described: in response to the grid-side voltage of the converter being less than or equal to a predetermined grid-side voltage threshold, the amplitude and angular frequency of the virtual internal potential associated with the converter are maintained at steady-state amplitude and steady-state angular frequency, respectively, wherein the virtual internal potential is used to control the converter; and the virtual impedance to which the virtual internal potential is applied is adjusted according to the grid-side voltage and the virtual internal potential.

[0069] For reference Figures 1 to 5 The converter control method for a voltage source type wind turbine according to an embodiment of this disclosure is used to understand the corresponding operation of the various components in the control device 7, and will not be repeated here for the sake of brevity. Figure 7 The control device shown is merely an example and should not be construed as limiting the functionality and scope of use of the embodiments disclosed herein.

[0070] According to embodiments of this disclosure, a converter is also provided, which may include the control device described above.

[0071] According to embodiments of this disclosure, a voltage source type fan is also provided, the voltage source type fan including the converter as described above.

[0072] According to embodiments of the present disclosure, a computer-readable storage medium is also provided, on which a computer program is stored, which, when executed, implements a converter control method for a voltage source type wind turbine according to embodiments of the present disclosure.

[0073] In embodiments of this disclosure, the computer-readable storage medium may carry one or more programs, which, when executed, can achieve reference... Figures 1 to 5 The following operations are described: in response to the grid-side voltage of the converter being less than or equal to a predetermined grid-side voltage threshold, the amplitude and angular frequency of the virtual internal potential associated with the converter are maintained at steady-state amplitude and steady-state angular frequency, respectively, wherein the virtual internal potential is used to control the converter; and the virtual impedance to which the virtual internal potential is applied is adjusted according to the grid-side voltage and the virtual internal potential.

[0074] Computer-readable storage media can be, for example, but not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatuses, or devices, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In embodiments of this disclosure, a computer-readable storage medium can be any tangible medium that contains or stores a computer program that can be used by or in conjunction with an instruction execution system, apparatus, or device. The computer program contained on the computer-readable storage medium can be transmitted using any suitable medium, including but not limited to: wires, optical cables, RF (radio frequency), etc., or any suitable combination thereof. A computer-readable storage medium can be included in any apparatus; it can also exist independently without being assembled into that apparatus.

[0075] The above has been referred to Figures 1 to 7 A converter control method, converter control device, computer-readable storage medium, control equipment, converter, and voltage source type wind turbine according to embodiments of the present disclosure are described. However, it should be understood that: Figure 6 The converter control device and its individual units shown can be configured to perform specific functions as software, hardware, firmware, or any combination thereof. Figure 7 The control device shown is not limited to the components shown above, but some components can be added or removed as needed, and the above components can also be combined.

[0076] The converter control method, converter control device, computer-readable storage medium, control equipment, converter, and voltage source wind turbine according to embodiments of the present disclosure can achieve at least one of the following technical effects: enabling the voltage source wind turbine to achieve stable grid-connected operation during low-voltage faults in the power grid; by adjusting the virtual impedance and / or other control parameters of the voltage source wind turbine, the wind turbine can still operate in voltage source control mode during low-voltage faults, exhibiting voltage source characteristics externally, without needing to switch to current source control mode; it can be executed during low-voltage faults in the power grid, and can fully utilize the effective capacity of the wind turbine to improve the transient stability of the power system or power grid while ensuring that the wind turbine does not abnormally disconnect from the grid; it can effectively improve the strength support of the voltage source wind turbine for the power system or power grid during low-voltage faults.

[0077] The control logic or functions performed by the various components or controllers in the aforementioned apparatus or device can be represented by flowcharts or similar diagrams in one or more accompanying drawings. These drawings provide representative control strategies and / or logic, which can be implemented using one or more processing strategies (such as event-driven, interrupt-driven, multitasking, multithreading, etc.). Therefore, the various steps or functions shown may be performed in the order shown, in parallel, or in some cases omitted. Although not always explicitly shown, those skilled in the art will recognize that one or more steps or functions shown may be repeatedly performed depending on the specific processing strategy used.

[0078] Although this disclosure has been shown and described with reference to preferred embodiments, those skilled in the art will understand that various modifications and variations may be made to these embodiments without departing from the spirit and scope of this disclosure as defined by the claims.

Claims

1. A method of controlling a converter of a voltage source type blower, characterized by, The converter control method comprises: in response to the grid-side voltage of the converter being less than or equal to a predetermined grid-side voltage threshold, maintaining the amplitude and the angular frequency of a virtual internal electric potential associated with the converter as a steady-state amplitude and a steady-state angular frequency respectively, wherein the virtual internal electric potential is used to control the converter, and the predetermined grid-side voltage threshold is determined according to a rated grid-side voltage and is less than the rated grid-side voltage; adjusting a virtual impedance applied to the virtual internal electric potential according to the grid-side voltage and the virtual internal electric potential, wherein the converter control method further comprises, after adjusting the virtual impedance applied to the virtual internal electric potential according to the grid-side voltage and the virtual internal electric potential, adjusting the virtual impedance according to a grid-side current command of the converter so that the amplitude of the grid-side current is within a predetermined current range.

2. The method of claim 1, wherein The steady-state amplitude and the steady-state angular frequency are respectively an amplitude and an angular frequency of the virtual internal electric potential when the grid-side voltage is within a steady-state grid-side voltage range, wherein the steady-state grid-side voltage range is higher than the predetermined grid-side voltage threshold.

3. The method of claim 1, wherein The adjusting the virtual impedance applied to the virtual internal electric potential according to the grid-side voltage and the virtual internal electric potential comprises: determining a virtual impedance target value according to the grid-side voltage, the virtual internal electric potential and a maximum tolerable current of the converter; adjusting the virtual impedance according to the virtual impedance target value.

4. The method of claim 3, wherein The upper limit of the current range is a maximum tolerable current value of the converter; or / and, a difference between the upper limit of the current range and a lower limit of the current range is less than or equal to a predetermined current margin, and the predetermined current margin is determined according to a rated grid-side current.

5. The method according to any one of claims 1 to 4, wherein When adjusting the virtual impedance, the virtual impedance is increased or decreased according to a slope of a predetermined range.

6. A converter control device for a voltage source type blower, characterized by comprising: The converter control device comprises: an internal electric potential control unit configured to, in response to the grid-side voltage of the converter being less than or equal to a predetermined grid-side voltage threshold, maintain the amplitude and the angular frequency of a virtual internal electric potential associated with the converter as a steady-state amplitude and a steady-state angular frequency respectively, wherein the virtual internal electric potential is used to control the converter, and the predetermined grid-side voltage threshold is determined according to a rated grid-side voltage and is less than the rated grid-side voltage; a virtual impedance adjustment unit configured to adjust a virtual impedance applied to the virtual internal electric potential according to the grid-side voltage and the virtual internal electric potential, wherein the virtual impedance adjustment unit is further configured to, after adjusting the virtual impedance applied to the virtual internal electric potential according to the grid-side voltage and the virtual internal electric potential, adjust the virtual impedance according to a grid-side current command of the converter so that the amplitude of the grid-side current is within a predetermined current range.

7. A computer readable storage medium storing a computer program, characterized in that, The computer program, when executed by the processor, implements the converter control method of the voltage source type fan as claimed in any one of claims 1 to 5.

8. A control device characterized by comprising: The control device comprises: a processor; a memory storing a computer program, wherein the computer program, when executed by the processor, implements the converter control method of the voltage source type fan as claimed in any one of claims 1 to 5.

9. A current transformer, characterized by The converter comprises the converter control device for a voltage source type fan as claimed in claim 6 or the control apparatus as claimed in claim 8.

10. A voltage source type blower, characterized by, The converter comprises the converter as claimed in claim 9.

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