Method and device for improving adaptability of wide short-circuit ratio range of grid-connected new energy

Abstract

The present invention discloses a method and device for improving the adaptability of a wide short circuit ratio range of a grid-forming new energy source. The method draws a Bode diagram according to a full-order impedance model of a grid-forming converter and the impedance of a power grid, and uses the Bode diagram to verify the stability problem existing in the grid-connected system of the grid-forming new energy converter; locates the frequency band where oscillation instability occurs according to the existing stability problem; and uses a hybrid virtual impedance method to replace a traditional virtual impedance reshaping method in a control structure to improve the adaptability of a wide short circuit ratio range of the grid-forming converter, thereby solving the problem that the traditional method has a relatively limited scope of action and may introduce negative damping into other frequency bands outside the frequency band of interest, thereby providing a reference for improving the adaptability of a wide short circuit ratio range of a grid-forming new energy source.

Description

Technical Field

[0001] The present application relates to the field of grid-connected control of new energy converters, and specifically to a method and device for improving the adaptability of a wide short-circuit ratio range of a grid-connected new energy converter. Background Art

[0002] Grid-connected inverters based on grid control have been widely studied due to their excellent control and support capabilities under weak power grids. However, with the increase in the penetration rate of new energy and the degree of power electronics, the complexity of the power grid has also increased. Grid-connected inverters are faced with a grid-connected environment with a wide range of power grid strengths. This makes grid-connected inverters face a greater risk of sub-synchronous resonance (SSR). The SSR problem of grid-connected inverters is closely related to the wide range of changes in the short circuit ratio (SCR) of the power grid. Therefore, improving the adaptability of grid-connected inverters in power grids with a wide range of short circuit ratios is an important issue that needs to be solved urgently.

[0003] Traditional methods for improving grid-connected stability of grid-connected converters include virtual impedance method and virtual admittance method. The virtual impedance method introduces a virtual impedance feedforward term before the voltage control link, that is, introduces the voltage components of virtual resistance and virtual inductance on the reference voltage before the voltage loop, so that the impedance phase of the converter after adding virtual impedance presents strong inductive properties near the fundamental frequency. The virtual admittance method replaces the voltage control link with virtual admittance to achieve the purpose of converting the voltage reference value into the current reference value, and introduces positive damping through "s=jω" to enable it to have full-band influence capability.

[0004] However, in actual engineering, the introduction of virtual impedance makes the impedance of the converter still show strong capacitive impedance in the lower frequency band, which makes the phase margin of the grid-type converter smaller in the low short-circuit ratio grid environment and has a greater risk of instability. Virtual admittance control can be approximated as a voltage loop without a proportional link, which has a certain voltage control effect. However, according to existing literature, the voltage loop integral coefficient k vi The existence of is the main reason for the phase spike of the subsynchronous frequency band of the converter impedance, and the extremely small voltage loop proportional coefficient k vp It will greatly enhance the negative resistance characteristics of the converter.

[0005] In summary, traditional stability improvement methods are usually proposed to address stability issues in specific frequency bands, with a relatively limited scope of action and the possibility of introducing negative damping into frequency bands other than the frequency band of interest. Therefore, it is difficult for traditional methods to enhance the adaptability of grid-connected converters in power grids with a wide short-circuit ratio range in the entire frequency band. Summary of the invention

[0006] In view of the above, the present invention provides a method for improving the adaptability of the wide short circuit ratio range of grid-type new energy. It improves the adaptability of the wide short circuit ratio range of the grid-type converter based on the hybrid virtual impedance method, solves the problem that the traditional method has a relatively limited scope of action and may introduce negative damping to other frequency bands outside the frequency band of concern, and provides a reference for improving the adaptability of the wide short circuit ratio range of grid-type new energy.

[0007] According to a first aspect of an embodiment of the present application, a method for improving the adaptability of a wide short circuit ratio range of a network-building new energy is provided, comprising:

[0008] Draw the impedance Bode diagram based on the full-order impedance model of the grid-connected converter and the grid impedance to verify the grid-connected stability;

[0009] Based on the grid stability test results and combined with the grid stability constraints, locate the frequency bands that cause stability problems;

[0010] According to the frequency band, a hybrid virtual impedance method is used to replace the virtual impedance reshaping method to improve the adaptability of the wide short-circuit ratio range of the grid-type converter. The hybrid virtual impedance method is introduced by introducing the virtual admittance analogy virtual impedance method into the current reference value.

[0011] Optionally, the full-order impedance model of the grid-type converter includes a power calculation link, a power control link, a voltage and current control link, a coordinate transformation link, and a filtering link. The small signal model expressions of each link are as follows:

[0012] Power calculation link:

[0013] Power control link:

[0014] Voltage control link:

[0015] Current control link:

[0016] Filtering stage:

[0017] Coordinate transformation link:

[0018] Where P and Q represent active power and reactive power respectively; E and θ are the d-axis voltage reference value and coordinate transformation angle respectively; u d，q 、i d，q 、e d，q and i id，qare the dq axis components of the grid connection point voltage, current and output port voltage, current respectively; “~” represents the small signal component, the superscript “s” represents the variable in the actual coordinate system; the superscript “c” represents the variable in the control coordinate system; the superscript “r” represents the reference value of the modulation link; G i and G u are the transfer function matrices from voltage and current to active and reactive power in the actual coordinate system, G PQ and G v are the transfer function matrices from power and voltage to reference phase and reference voltage amplitude respectively; G Hv and G Hi are the transfer function matrices for voltage control and current control respectively; G ωL and G ωC are the decoupling terms of voltage control and current control respectively; G Lf and G Cf are the transfer functions of the filter inductor and filter capacitor respectively; U, I and E are the steady-state values ​​of u, i, and e respectively.

[0019] Optionally, the full-order impedance model of the grid-type converter is as follows:

[0020]

[0021] Among them, Z cdq To construct the impedance model of the grid-type converter, and They are the dq axis small signal components of the grid connection point voltage and current respectively. cdq It also includes the inertia constant J and the damping coefficient D p , droop coefficient D q , voltage loop integral coefficient K, voltage loop proportional coefficient k vp , voltage loop integration coefficient k vi , current loop proportionality coefficient k ip , current loop proportionality coefficient k ii , filter inductor L f And the filter capacitor C f And other main control parameters;

[0022] The grid impedance is represented by Z g =R g +jω g L g , where R g is the grid resistance, L g is the grid inductance. When the grid is a purely inductive grid, R g =0, then Z g =R g +jω g L g , combining the converter impedance with the grid impedance Bode diagram.

[0023] Optionally, an impedance Bode diagram is drawn based on the full-order impedance model of the grid-connected converter and the grid impedance to verify the grid-connected stability, including:

[0024] Based on the Bode diagram analysis of the combined converter and grid impedance, when the grid is a purely inductive grid, the grid impedance amplitude is a straight line related to the frequency in the Bode diagram; when the grid short-circuit ratio increases, the grid equivalent impedance decreases, and the grid impedance amplitude characteristic curve moves to the right; by drawing the grid impedance characteristic curves with different short-circuit ratios, it is observed whether the phase difference corresponding to the intersection of the grid impedance amplitude and the converter impedance amplitude exceeds 180°, that is, as the grid short-circuit ratio changes, whether the grid-connected system will operate in the negative damping zone; if there is a situation where it operates in the negative damping zone, it means that the converter grid-connected system has a grid adaptability problem in a wide short-circuit ratio range.

[0025] Optionally, the grid-connected stability constraint condition is as follows:

[0026]

[0027] Among them, Z c represents the transformer impedance, s x =jω x ,ω x =2πf x , f x Indicates the frequency corresponding to the amplitude intersection point.

[0028] Optionally, the method of analogizing virtual admittance to virtual impedance is introduced into the current reference value, as shown in the following formula:

[0029]

[0030] Among them, R v and L v are virtual resistance and virtual inductance respectively, v d and v q are the dq axis voltages in the dq coordinate system, E is the d axis voltage reference value, i is dr and i qr are the dq axis current reference values ​​respectively.

[0031] According to a second aspect of an embodiment of the present application, a device for improving the adaptability of a wide short-circuit ratio range of a network-building new energy is provided, comprising:

[0032] A test module is used to draw an impedance Bode diagram based on the full-order impedance model of the grid-connected converter and the grid impedance to test the grid-connected stability;

[0033] A positioning module is used to locate the frequency band causing stability problems based on the grid stability test results and grid stability constraint conditions;

[0034] The adaptability improvement module is used to improve the adaptability of the wide short-circuit ratio range of the grid-type converter by replacing the virtual impedance reshaping method with a hybrid virtual impedance method according to the frequency band. The hybrid virtual impedance method is introduced by introducing the method of virtual admittance analogy virtual impedance into the current reference value.

[0035] According to a second aspect of an embodiment of the present application, there is provided an electronic device, including:

[0036] one or more processors;

[0037] A memory for storing one or more programs;

[0038] When the one or more programs are executed by the one or more processors, the one or more processors implement the method as described in the first aspect.

[0039] According to a second aspect of an embodiment of the present application, a computer-readable storage medium is provided, on which computer instructions are stored. When the instructions are executed by a processor, the steps of the method described in the first aspect are implemented.

[0040] The technical solution provided by the embodiments of the present application may have the following beneficial effects:

[0041] It can be seen from the above embodiments that the present invention provides a method for improving the adaptability of the wide short-circuit ratio range of a grid-type new energy source based on the full-order impedance model of the grid-type converter. The method improves the adaptability of the wide short-circuit ratio range of the grid-type converter based on the hybrid virtual impedance method, solves the problem that the traditional method has a relatively limited scope of action and may introduce negative damping to other frequency bands outside the frequency band of interest, and provides a reference for improving the adaptability of the wide short-circuit ratio range of a grid-type new energy source.

[0042] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0044] Figure 1 It is a flow chart of a method for improving the adaptability of a wide short-circuit ratio range of a grid-connected new energy system according to an exemplary embodiment.

[0045] Figure 2 It is a structural block diagram of a grid-connected system of a grid-connected converter according to an exemplary embodiment.

[0046] Figure 3is a control block diagram of a hybrid virtual impedance method according to an exemplary embodiment.

[0047] Figure 4 is a block diagram of virtual impedance / admittance control according to an exemplary embodiment.

[0048] Figure 5 The impedance characteristic of a grid-connected converter with hybrid virtual impedance control is shown according to an exemplary embodiment.

[0049] Figure 6 The figure is a hybrid virtual impedance validity verification result shown according to an exemplary embodiment.

[0050] Figure 7 It is a block diagram of a device for improving the adaptability of a wide short-circuit ratio range of a grid-connected new energy system according to an exemplary embodiment.

[0051] Figure 8 The diagram is a schematic structural diagram of an electronic device according to an exemplary embodiment. DETAILED DESCRIPTION

[0052] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0053] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0054] It should be understood that although the terms first, second, third, etc. may be used in the present application to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0055] Figure 1is a flow chart of a method for improving the adaptability of a wide short circuit ratio range of a network-building new energy system according to an exemplary embodiment. Figure 1 As shown, the method may include the following steps:

[0056] S1: Draw the impedance Bode diagram based on the full-order impedance model of the grid-connected converter and the grid impedance to verify the grid-connected stability;

[0057] Specifically, in order to verify the grid-connected stability of the grid-connected new energy converter, the full-order impedance model of the grid-connected converter should include the power calculation link, power control link, voltage and current control link, coordinate transformation link and filtering link. The small signal model of each link is as follows:

[0058] Power calculation link:

[0059] Power control link:

[0060] Voltage control link:

[0061] Current control link:

[0062] Filtering stage:

[0063] Coordinate transformation link:

[0064] Where P and Q represent active power and reactive power respectively; E and θ are the d-axis voltage reference value and coordinate transformation angle respectively; u d，q 、i d，q 、e d，q and i id，q are the dq axis components of the grid connection point voltage, current and output port voltage, current respectively; “~” represents the small signal component, the superscript “s” represents the variable in the actual coordinate system; the superscript “c” represents the variable in the control coordinate system; the superscript “r” represents the reference value of the modulation link; G i and G u are the transfer function matrices from voltage and current to active and reactive power in the actual coordinate system, G PQ and G v are the transfer function matrices from power and voltage to reference phase and reference voltage amplitude respectively; G Hv and G Hi are the transfer function matrices for voltage control and current control respectively; G ωL and G ωC are the decoupling terms of voltage control and current control respectively; G Lf and G Cfare the transfer functions of the filter inductor and filter capacitor respectively; U, I and E are the steady-state values ​​of u, i, and e respectively.

[0065] The full-order impedance model of the grid-type converter is shown as follows:

[0066]

[0067] Among them, Z cdq To construct the impedance model of the grid-type converter, and They are the dq axis small signal components of the grid connection point voltage and current, and include the inertia constant J, damping coefficient D p , droop coefficient D q , voltage loop integral coefficient K, voltage loop proportional coefficient k vp , voltage loop integration coefficient k vi , current loop proportionality coefficient k ip , current loop proportionality coefficient k ii , filter inductor L f And the filter capacitor C f The grid-connected stability test of the grid-connected converter is based on the impedance Bode diagram of the converter and the grid. The grid impedance is represented by Z g =R g +jω g L g , where R g is the grid resistance, L g is the grid inductance. When the grid is a purely inductive grid, R g =0, then Z g =R g +jω g L g . Combine the impedance Bode diagram of the converter and the grid. When the grid is a purely inductive grid, the grid impedance amplitude is a straight line related to the frequency in the Bode diagram. When the short-circuit ratio of the grid increases, the equivalent impedance of the grid decreases, and the grid impedance amplitude characteristic curve moves to the right. By drawing the impedance characteristic curve of the grid with different short-circuit ratios, observe whether the phase difference corresponding to the intersection of the grid impedance amplitude and the converter impedance amplitude exceeds 180°, that is, as the short-circuit ratio of the grid changes, whether the grid-connected system will operate in the negative damping zone. If there is a situation of operating in the negative damping zone, it means that the converter grid-connected system has a problem of grid adaptability in a wide short-circuit ratio range. In this way, the grid-connected stability results tested by the full-order impedance model combined with the grid impedance can more truly reflect the state of the grid-connected converter in actual operation.

[0068] S2: Based on the grid stability test results and combined with the grid stability constraints, locate the frequency bands that cause stability problems;

[0069] Specifically, the grid connection stability constraint used when locating a frequency band with poor adaptability is as follows:

[0070]

[0071] Among them, Z c represents the transformer impedance, s x =jω x ,ω x =2πf x , f x Indicates the frequency corresponding to the amplitude intersection point.

[0072] Use this formula to obtain f x The range can accurately reflect the frequency range of instability problems between the grid-type converter and the power grid, and locate the frequency band in which the grid-type converter has stability problems under a wide short-circuit ratio power grid.

[0073] S3: According to the located frequency band, a hybrid virtual impedance method is used to replace the virtual impedance reshaping method to improve the adaptability of the wide short-circuit ratio range of the grid-type converter. The hybrid virtual impedance method is introduced by introducing the method of virtual admittance analogy virtual impedance into the current reference value.

[0074] Specifically, the control block diagram of the hybrid virtual impedance method is as follows: Figure 3 As shown, the hybrid virtual impedance method introduces the method of virtual admittance analogy virtual impedance into the current reference value by referring to the traditional virtual impedance introduction method, which is shown in the following formula:

[0075]

[0076] Among them, R v and L v are virtual resistance and virtual inductance respectively, v d and v q are the dq axis voltages in the dq coordinate system, E is the d axis voltage reference value, i is dr and i qr are the dq axis current reference values ​​respectively.

[0077] The improved current reference value can be expressed as,

[0078]

[0079] Use hybrid virtual impedance control link to replace Figure 4 The voltage control link in the traditional grid-type converter control strategy shown in the figure is replaced by the converter impedance characteristic Figure 5As shown in the figure, the intersection point of the converter impedance and the grid impedance amplitude using hybrid virtual impedance control has shifted from the original subsynchronous frequency band to the low-frequency and high-frequency bands, and the converter impedance phase also shows resistance inductance in almost all frequency bands. It can be seen that the new control structure can not only improve the fundamental frequency impedance characteristics but also improve the phase margin in a wide frequency band. It greatly enhances the adaptability of the grid-type converter in a wide short-circuit ratio grid environment.

[0080] The hardware-in-the-loop experiment was carried out on the Typhoon 602+ experimental platform. A grid-connected converter system was built in Typhoon 602+. The control link of the system was implemented by the actual TMS320F28335 / Spartan 6XC6SLX16 DSP+FPGA hardware circuit board. The system parameters were set according to Table 1. Since the difference between the grid-connected converter with voltage and current dual closed-loop control and the grid-connected converter with hybrid virtual impedance control is only the voltage control link and the hybrid virtual impedance link, the effectiveness of the hybrid virtual impedance control strategy can be verified by switching voltage control / hybrid virtual impedance control. The verification results are shown in Table 1. Figure 6 As shown in the figure, the results show that when SCR=12, the grid-connected system using voltage and current dual closed-loop control cannot operate stably. At this time, the hybrid virtual impedance control strategy is enabled to restore the system to stable operation, and it can still be stable after the short-circuit ratio changes to 20 and 3, which verifies the effectiveness of the proposed control strategy.

[0081] Table 1: Parameters of grid-connected converters

[0082]

[0083] It can be seen from the above embodiments that the present application provides a method for improving the adaptability of a wide short-circuit ratio range of a grid-type new energy source based on the full-order impedance model of the grid-type converter. The method improves the adaptability of a wide short-circuit ratio range of a grid-type converter based on a hybrid virtual impedance method, and solves the problem that the traditional method has a relatively limited scope of action and may introduce negative damping to other frequency bands outside the frequency band of interest.

[0084] Corresponding to the aforementioned embodiment of the method for improving the adaptability of the wide short circuit ratio range of a network-building new energy, the present application also provides an embodiment of a device for improving the adaptability of the wide short circuit ratio range of a network-building new energy.

[0085] Figure 7 1 is a block diagram of a device for improving the adaptability of a wide short-circuit ratio range of a network-building new energy source according to an exemplary embodiment. Figure 7 , the device comprises:

[0086] Verification module 1 is used to draw an impedance Bode diagram based on the full-order impedance model of the grid-connected converter and the grid impedance to verify the grid-connected stability;

[0087] Positioning module 2, used to locate the frequency band causing stability problems according to the grid stability test results and grid stability constraint conditions;

[0088] The adaptability improvement module 3 is used to improve the adaptability of the wide short-circuit ratio range of the grid-type converter by replacing the virtual impedance reshaping method with a hybrid virtual impedance method according to the frequency band. The hybrid virtual impedance method is introduced by introducing the method of virtual admittance analogy virtual impedance into the current reference value.

[0089] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0090] For the device embodiment, since it basically corresponds to the method embodiment, the relevant parts can refer to the partial description of the method embodiment. The device embodiment described above is only schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present application scheme. A person of ordinary skill in the art can understand and implement it without paying any creative work.

[0091] Accordingly, the present application also provides an electronic device, including: one or more processors; a memory for storing one or more programs; when the one or more programs are executed by the one or more processors, the one or more processors implement the above-mentioned method for improving the adaptability of the wide short-circuit ratio range of the network-building new energy. Figure 8 As shown, it is a hardware structure diagram of a device for improving the adaptability of a wide short-circuit ratio range of a network-building type new energy provided by an embodiment of the present invention, in which any device with data processing capability is located, except Figure 8 In addition to the processor, memory, DMA controller, disk, and non-volatile memory shown, any device with data processing capabilities in which the apparatus in the embodiment is located may also include other hardware, which will not be described in detail, generally based on the actual functions of the device with data processing capabilities.

[0092] Accordingly, the present application also provides a computer-readable storage medium having computer instructions stored thereon, which, when executed by a processor, implement the above-mentioned method for improving the adaptability of the wide short-circuit ratio range of a network-type new energy. The computer-readable storage medium may be an internal storage unit of any device with data processing capabilities described in any of the foregoing embodiments, such as a hard disk or a memory. The computer-readable storage medium may also be an external storage device, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), an SD card, a flash card (Flash Card), etc. equipped on the device. Furthermore, the computer-readable storage medium may also include both an internal storage unit and an external storage device of any device with data processing capabilities. The computer-readable storage medium is used to store the computer program and other programs and data required by any device with data processing capabilities, and may also be used to temporarily store data that has been output or is to be output.

[0093] Those skilled in the art will readily appreciate other embodiments of the present application after considering the description and practicing the contents disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The description and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the claims.

[0094] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A method for improving the adaptability of wide short-circuit ratio range of network-building new energy, characterized in that: include: Draw the impedance Bode diagram based on the full-order impedance model of the grid-connected converter and the grid impedance to verify the grid-connected stability; Based on the grid stability test results and combined with the grid stability constraints, locate the frequency bands that cause stability problems; According to the frequency band, a hybrid virtual impedance method is used to replace the virtual impedance reshaping method to improve the adaptability of the wide short-circuit ratio range of the grid-type converter. The hybrid virtual impedance method is introduced by introducing the virtual admittance analogy virtual impedance method into the current reference value.

2. The method according to claim 1, characterized in that The full-order impedance model of the grid-type converter includes power calculation link, power control link, voltage and current control link, coordinate transformation link and filtering link. The small signal model expressions of each link are as follows: Power calculation link: Power control link: Voltage control link: Current control link: Filtering stage: Coordinate transformation link: Where P and Q represent active power and reactive power respectively; E and θ are the d-axis voltage reference value and coordinate transformation angle respectively; u d，q 、i d，q 、e d，q and i id，q are the dq axis components of the grid connection point voltage, current and output port voltage, current respectively; "~" indicates the small signal component, the superscript "s" indicates the variable in the actual coordinate system; the superscript "c" indicates the variable in the control coordinate system; the superscript "r" indicates the reference value of the modulation link; G i and G u are the transfer function matrices from voltage and current to active and reactive power in the actual coordinate system, G PQ and G v are the transfer function matrices from power and voltage to reference phase and reference voltage amplitude respectively; G Hv and G Hi are the transfer function matrices for voltage control and current control respectively; G ωL and G ωC are the decoupling terms of voltage control and current control respectively; G Lf and G Cf are the transfer functions of the filter inductor and filter capacitor respectively; U, I and E are the steady-state values ​​of u, i, and e respectively.

3. The method according to claim 1, characterized in that The full-order impedance model of the grid-type converter is shown in the following formula: Among them, Z cdq To construct the impedance model of the grid-type converter, and are the dq axis small signal components of the grid connection point voltage and current respectively; Z cdq It also includes the inertia constant J and the damping coefficient D p , droop coefficient D q , voltage loop integral coefficient K, voltage loop proportional coefficient k vp , voltage loop integration coefficient k vi , current loop proportionality coefficient k ip , current loop proportionality coefficient k ii 、Filter inductor L f And the filter capacitor C f Main control parameters: The grid impedance is represented by Z g =R g +jω g L g , where R g is the grid resistance, L g is the grid inductance; when the grid is a purely inductive grid, R g =0, then Z g =R g +jω g L g , combining the converter impedance with the grid impedance Bode diagram.

4. The method according to claim 1, characterized in that Draw the impedance Bode diagram based on the full-order impedance model of the grid-connected converter and the grid impedance to verify the grid-connected stability, including: Based on the Bode diagram analysis of the combined converter and grid impedance, when the grid is a purely inductive grid, the grid impedance amplitude is a straight line related to the frequency in the Bode diagram; when the grid short-circuit ratio increases, the grid equivalent impedance decreases, and the grid impedance amplitude characteristic curve moves to the right; by drawing the grid impedance characteristic curves with different short-circuit ratios, it is observed whether the phase difference corresponding to the intersection of the grid impedance amplitude and the converter impedance amplitude exceeds 180°, that is, as the grid short-circuit ratio changes, whether the grid-connected system will operate in the negative damping zone; if there is a situation where it operates in the negative damping zone, it means that the converter grid-connected system has a grid adaptability problem in a wide short-circuit ratio range.

5. The method according to claim 1, characterized in that: The grid-connected stability constraint condition is as follows: Among them, Z c represents the transformer impedance, s x =jω x ,ω x =2πf x , f x Indicates the frequency corresponding to the amplitude intersection point.

6. The method according to claim 1, characterized in that The method of using virtual admittance analogy with virtual impedance is introduced into the current reference value, as shown in the following formula: Among them, R v and L v are virtual resistance and virtual inductance respectively, v d and v q are the dq axis voltages in the dq coordinate system, E is the d axis voltage reference value, i is dr and i qr are the dq axis current reference values ​​respectively.

7. A device for improving the adaptability of a wide short-circuit ratio range of a network-building new energy source, characterized in that: include: A test module is used to draw an impedance Bode diagram based on the full-order impedance model of the grid-connected converter and the grid impedance to test the grid-connected stability; A positioning module is used to locate the frequency band causing stability problems based on the grid stability test results and grid stability constraint conditions; The adaptability improvement module is used to improve the adaptability of the wide short-circuit ratio range of the grid-type converter by replacing the virtual impedance reshaping method with a hybrid virtual impedance method according to the frequency band. The hybrid virtual impedance method is introduced by introducing the method of virtual admittance analogy virtual impedance into the current reference value.

8. An electronic device, characterized in that: include: one or more processors; A memory for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having computer instructions stored thereon, characterized in that: When the instruction is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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