Grid-connected inverter multi-working condition outer admittance model construction method based on interpolation algorithm

Abstract

The application discloses a grid-connected inverter multi-working condition outer admittance model construction method based on an interpolation algorithm, relates to the field of new energy grid-connected small signal modeling, and comprises the following steps: determining a working condition range to be modeled and selecting typical operating working conditions, obtaining an outer admittance model of the grid-connected inverter under the selected typical operating working conditions by using a frequency scanning method; under the premise of fixed current and voltage, performing interpolation processing on the outer admittance models under different voltage and current working conditions; and further interpolating the data obtained by interpolation under non-selected working conditions to obtain an inverter model in the entire working condition range. The method provides a multi-working condition outer admittance modeling method of the grid-connected inverter, does not require structure and parameter information of equipment, and simultaneously reduces the work burden of using a large amount of measurement data.

Description

Technical Field

[0001] This invention relates to the field of small-signal modeling technology for grid-connected new energy sources, and in particular to a method for constructing multi-condition external admittance models for grid-connected inverters based on interpolation algorithms. Background Technology

[0002] In modern power systems, an increasing number of renewable energy sources, such as wind and solar power, are integrated into the grid via inverters. Due to the volatility of new energy sources and the diversity of grid operation modes, the operating conditions of grid-connected inverters exhibit multifaceted characteristics. The external admittance model of a grid-connected inverter is closely related to its operating conditions; different external admittance characteristics and the interaction with grid impedance can lead to different stability outcomes. Therefore, researching methods for constructing multi-condition external admittance models for grid-connected inverters has significant theoretical and technical value for power system stability assessment.

[0003] In existing technologies, the construction methods for multi-condition external admittance models of grid-connected inverters are mostly based on white-box models, that is, mathematical modeling is performed under the premise that the structure and parameters of the inverter and its controller are known. However, in actual engineering, due to trade secrets, manufacturers often do not provide the structure and parameters of the equipment, thus grid-connected inverters exhibit black-box characteristics. On the other hand, data-driven multi-condition modeling methods require a large amount of measurement data, are complex to implement, lack theoretical basis, and have poor interpretability. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, this invention provides a method for constructing external admittance models of grid-connected inverters under multiple operating conditions based on interpolation algorithms, which does not require structural and parameter information of the equipment, and at the same time reduces the workload of using a large amount of measurement data.

[0006] To address the aforementioned technical problems, this invention provides the following technical solution: a method for constructing a multi-condition external admittance model for grid-connected inverters based on interpolation algorithms, comprising:

[0007] The operating conditions to be modeled are determined and typical operating conditions are selected. The external admittance model of the grid-connected inverter under the selected typical operating conditions is obtained by frequency scanning method. Under the premise of fixed current and voltage, the external admittance model under different voltage and current conditions is interpolated. The data obtained by interpolation under non-selected operating conditions is used to further interpolate to obtain the inverter model for the entire operating condition range.

[0008] As a preferred embodiment of the multi-condition external admittance model construction method for grid-connected inverters based on interpolation algorithms described in this invention, the operating conditions include inverter output voltage U1 and current I1; the selection of typical operating conditions needs to cover the complete range of operating conditions, and the selected operating conditions in the same group need to meet the requirements of the same voltage or the same current. Under the premise of meeting the preset frequency standard, when the voltage is constant, the inverter admittance model is proportional to the current; when the current is constant, the admittance model is monotonic with the voltage.

[0009] As a preferred embodiment of the multi-condition external admittance model construction method for grid-connected inverters based on interpolation algorithms described in this invention, the external admittance model includes: superimposing small-signal voltages or currents of different frequencies at the grid-connected inverter port, then performing FFT analysis on the response current or voltage and the input voltage or current, obtaining the ratio of the current component to the voltage component as the measured inverter admittance, and obtaining the grid-connected inverter external admittance Y through the measured signal. inv The calculation method for (s) is as follows:

[0010]

[0011] In the formula: ω is the angular frequency, corresponding to the Laplace operator s, and s = jω; i p1,1 i p2,1 u p1,1 u p2,1 with i p1,2 i p2,2 u p1,2 u p2,2 These are the first and second groups of current and voltage signals at corresponding frequencies extracted by FFT.

[0012] As a preferred embodiment of the multi-condition external admittance model construction method for grid-connected inverters based on interpolation algorithms described in this invention, the interpolation processing of the external admittance models under different voltage and current conditions includes, under the premise of fixed current or voltage, the theoretical basis for interpolating the external admittance models under different voltage or current conditions to obtain new operating condition models is described as follows:

[0013] The mathematical model of the inverter's main circuit is expressed as follows:

[0014]

[0015] Among them, U d U q I d and I q These are the voltage and current dq components at the grid connection point, respectively; U dc It is the DC bus voltage; ω1 is the power frequency angular frequency; D d and D qThese represent the duty cycles of the d-axis and q-axis, respectively.

[0016] The linearized model of the circuit is:

[0017] (Ls+jω1L)ΔI dq =ΔD dq U dc -ΔU dq

[0018] Where the subscript dq denotes a complex vector, i.e., X dq =X d +jX q X is the corresponding state variable.

[0019] As a preferred embodiment of the multi-condition external admittance model construction method for grid-connected inverters based on interpolation algorithms described in this invention, the interpolation processing of the external admittance model under different voltage and current conditions includes, for the inverter controller, since the phase-locked loop and current loop are the basic control links, taking into account the influence, the small-signal model of the control circuit is represented as:

[0020]

[0021] Among them, G c (s) is the transfer function of the inner current loop; U cr It is the carrier amplitude of the inverter; Δθ PLL (s) is the small phase angle disturbance of the phase-locked loop output, expressed as:

[0022]

[0023] Among them, T pll (s) is the transfer function of the phase-locked loop.

[0024] As a preferred embodiment of the multi-condition external admittance model construction method for grid-connected inverters based on interpolation algorithms described in this invention, wherein: the interpolation processing of the external admittance model under different voltage and current conditions includes introducing I... dq =I1 and D dq =(U1+jω1LI1) / U dc The following formula is obtained:

[0025] A(s)ΔI dq (s)=B1(s)ΔU dq (s)

[0026]

[0027] Specifically, it can be elaborated as follows:

[0028]

[0029] Where U1 and I1 represent the inverter output voltage and current, respectively; L is the inverter's filter inductance; K d This represents the feedforward decoupling coefficient of the inner current loop; the other symbols have been defined previously.

[0030] As a preferred embodiment of the multi-condition external admittance model construction method for grid-connected inverters based on interpolation algorithms described in this invention, the interpolation processing of the external admittance model under different voltage and current conditions further includes, by rearranging, obtaining the external admittance matrix elements of the grid-connected inverter as follows:

[0031]

[0032] For grid-connected inverters, when the frequency is constant, the specific formula is as follows:

[0033]

[0034] in, The elements of the inverter external admittance model matrix are functions of operating conditions U1 and I1; a, b, c, d, and e are all constants.

[0035] Interpolation processing is performed on the external admittance model under different currents or voltages with a fixed voltage or current.

[0036] As a preferred embodiment of the multi-condition external admittance model construction method for grid-connected inverters based on interpolation algorithm described in this invention, the further interpolation includes obtaining an inverter admittance model operating condition that is the same as one of the selected operating conditions, i.e., the voltage or current is the same, and obtaining an inverter admittance with voltage and current different from the selected operating condition through further interpolation, thereby completing the external admittance modeling of the grid-connected inverter within the full range of operating conditions.

[0037] A computer device includes a memory and a processor, wherein the memory stores a computer program, characterized in that the processor executes the computer program to implement the steps of constructing a multi-condition external admittance model for a grid-connected inverter based on an interpolation algorithm.

[0038] A computer-readable storage medium having a computer program stored thereon, characterized in that, when the computer program is executed by a processor, it implements the steps of a method for constructing a multi-condition external admittance model of a grid-connected inverter based on an interpolation algorithm.

[0039] The beneficial effects of this invention are: 1) It is applicable to modeling grid-connected inverters containing black-box controllers. This invention first obtains the external admittance model under typical operating conditions through frequency scanning, and then obtains the external admittance model of the inverter under multiple operating conditions through interpolation algorithms. It does not require detailed structure and parameters of the controller, and has strong applicability. 2) The algorithm is simple and requires less measurement data. The modeling method disclosed in this invention is based on the general modeling of grid-connected inverters, has model-driven characteristics, and can improve modeling efficiency. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of a method for constructing a multi-condition external admittance model of a grid-connected inverter based on an interpolation algorithm, provided in one embodiment of the present invention.

[0042] Figure 2 This is a schematic diagram of the admittance model obtained by frequency scanning in a method for constructing a multi-condition external admittance model of a grid-connected inverter based on an interpolation algorithm, provided in an embodiment of the present invention.

[0043] Figure 3 This is a schematic diagram of the external admittance model of the inverter under different current conditions obtained by interpolation in the multi-condition external admittance model construction method of grid-connected inverter based on interpolation algorithm provided in an embodiment of the present invention.

[0044] Figure 4 This is a schematic diagram illustrating the verification of the external admittance model obtained by interpolation in a method for constructing a multi-condition external admittance model of a grid-connected inverter based on an interpolation algorithm, according to an embodiment of the present invention. Detailed Implementation

[0045] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0046] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0047] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0048] This invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of this invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not adhering to the usual scale. Furthermore, the schematic diagrams are merely examples and should not be construed as limiting the scope of protection of this invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0049] Furthermore, in the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used solely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. In addition, the terms "first," "second," or "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0050] Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" in this invention should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; similarly, they can refer to mechanical connections, electrical connections, or direct connections, or indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0051] Example 1, referring to Figure 1 This is the first embodiment of the present invention, which provides a method for constructing a multi-condition external admittance model of a grid-connected inverter based on an interpolation algorithm, including:

[0052] The operating conditions to be modeled are determined and typical operating conditions are selected. The external admittance model of the grid-connected inverter under the selected typical operating conditions is obtained by frequency scanning method. Under the premise of fixed current and voltage, the external admittance model under different voltage and current conditions is interpolated. The data obtained by interpolation under non-selected operating conditions is used to further interpolate to obtain the inverter model for the entire operating condition range.

[0053] The operating conditions include the inverter output voltage U1 and current I1. The selection of typical operating conditions needs to cover the complete range of operating conditions. The selected operating conditions in the same group need to meet the requirements of the same voltage or the same current. Under the premise of meeting the preset frequency standard, when the voltage is constant, the inverter admittance model is proportional to the current; when the current is constant, the admittance model is monotonic with the voltage.

[0054] The external admittance model includes superimposing small-signal voltages or currents of different frequencies at the grid-connected inverter port, then performing FFT analysis on the response current or voltage and the input voltage or current. The ratio of the current component to the voltage component is the measured inverter admittance, and the external admittance Y of the grid-connected inverter is obtained through the measured signal. inv The calculation method for (s) is as follows:

[0055]

[0056] In the formula: ω is the angular frequency, corresponding to the Laplace operator s, and s = jω; i p1,1 i p2,1 u p1,1 u p2,1 with i p1,2 i p2,2 u p1,2 u p2,2 These are the first and second groups of current and voltage signals at corresponding frequencies extracted by FFT.

[0057] The theoretical basis for interpolating the external admittance models under different voltage or current conditions to obtain new operating condition models under the premise of fixed current or voltage is described as follows:

[0058] The mathematical model of the inverter's main circuit is expressed as follows:

[0059]

[0060] Among them, U d U q I d and I q These are the voltage and current dq components at the grid connection point, respectively; U dc It is the DC bus voltage; ω1 is the power frequency angular frequency; D d and D q These represent the duty cycles of the d-axis and q-axis, respectively.

[0061] The linearized model of the circuit is:

[0062] (Ls+jω1L)ΔI dq =ΔD dq U dc -ΔU dq

[0063] Where the subscript dq denotes a complex vector, i.e., X dq =X d +jX q X is the relevant state variable.

[0064] For the inverter controller, since the phase-locked loop and current loop are the basic control elements, taking into account their effects, the small-signal model of the control circuit is represented as follows:

[0065]

[0066] Among them, G c (s) is the transfer function of the inner current loop; U cr It is the carrier amplitude of the inverter; Δθ PLL (s) is the small phase angle disturbance of the phase-locked loop output, expressed as:

[0067]

[0068] Among them, T pll (s) is the transfer function of the phase-locked loop.

[0069] Introducing I dq =I1 and D dq =(U1+jω1LI1) / U dc The following formula is obtained:

[0070] A(s)ΔI dq (s)=B1(s)ΔU dq (s)

[0071]

[0072] Specifically, it can be elaborated as follows:

[0073]

[0074] Where U1 and I1 represent the inverter output voltage and current, respectively; L is the inverter's filter inductance; K d This represents the feedforward decoupling coefficient of the inner current loop; the other symbols have been defined previously.

[0075] By rearranging, the external admittance matrix elements of the grid-connected inverter can be obtained as follows:

[0076]

[0077] For grid-connected inverters, when the frequency is constant, the specific formula is as follows:

[0078]

[0079] in, The elements of the inverter external admittance model matrix are functions of operating conditions U1 and I1; a, b, c, d, and e are all constants.

[0080] Interpolation is performed on the external admittance models under different currents or voltages, with the premise of a fixed voltage or current. For example, under the premise of a fixed voltage U1, the external admittance models of different currents I1 can be interpolated to obtain the external admittance models for all current conditions under this fixed voltage. The same principle applies to the case of a fixed current with different voltages.

[0081] The further interpolation includes obtaining an inverter admittance model operating condition that is the same as one of the selected operating conditions, i.e., the voltage or current is the same, and obtaining an inverter admittance with both voltage and current different from the selected operating condition through further interpolation, thus completing the external admittance modeling of the grid-connected inverter within the full range of operating conditions.

[0082] Example 2, refer to Figures 1-4 As an embodiment of the present invention, a method for constructing a multi-condition external admittance model of a grid-connected inverter based on an interpolation algorithm is provided. To verify the beneficial effects of the present invention, scientific demonstration is carried out through experiments.

[0083] Step 1: Determine the range of operating conditions to be modeled and select several typical operating conditions.

[0084] The target inverter has a rated voltage U1 = 0.69kV and a rated current I1 = 1.75kA. The operating conditions include the inverter output voltage U1 and current I1, with an operating range of U1: 0.9-1.1pu; I1: 0.2-1.0pu. The selection of typical operating conditions needs to cover the entire operating range, and conditions within the same group must have the same voltage or current. Therefore, for this embodiment, the selected typical operating conditions are shown in Table 1, where set r represents the operating condition number.

[0085] Table 1. Typical Operating Conditions

[0086]

[0087] Step 2: Use the frequency scanning method to obtain the external admittance model of the grid-connected inverter under the selected typical operating conditions.

[0088] In this embodiment, small signal voltages of different frequencies are superimposed at the grid-connected inverter port. The selected scanning frequency is [-994-841-708-596-502-422-355-299-251-211-178-151-126-106-89-75-63-53-45-38-32-26-21-17-13-9-7-5- 3-1,1:2:99,102108117127137149161174189204221239259281304329356386418452489531574621672728788853924995]Hz, a total of 110 frequency points, covering the frequency range of (-1000, 1000)Hz. Then, FFT analysis is performed on the response current and input voltage respectively, and the ratio of the current component to the voltage component is the measured inverter admittance. The external admittance Y of the grid-connected inverter is obtained through the measurement signal. inv The calculation method for (s) is as follows:

[0089]

[0090] In the formula: ω is the angular frequency, corresponding to the Laplace operator s, and s = jω; i p1,1 i p2,1 u p1,1 u p2,1 with i p1,2 i p2,2 u p1,2 u p2,2 These are the first and second groups of current and voltage signals at corresponding frequencies extracted by FFT. For example... Figure 3 The figure shows the inverter admittance model obtained by scanning at different voltages when I1 = 1.0pu. This includes amplitude and phase.

[0091] Step 3: Under the premise of fixed voltage, perform interpolation processing on the external admittance model under different current conditions.

[0092] According to the analysis in the invention description, for a grid-connected inverter, when the frequency is constant, we have:

[0093]

[0094] In the formula: The elements of the inverter's external admittance model matrix are functions of operating conditions U1 and I1; a, b, c, d, and e are all constants. Therefore, under the premise of a fixed voltage, interpolation processing is performed on the external admittance models under different current conditions to obtain models for other operating conditions. Figure 4 The external admittance model of the inverter under different current conditions obtained by interpolation when U1 = 1.0pu.

[0095] Step 4: Use the data obtained from interpolation under non-selected operating conditions to further interpolate and obtain the inverter model for the entire operating condition range.

[0096] In step 3, the inverter admittance model obtained through interpolation is always the same as the selected voltage condition U1 under any operating condition. Further interpolation can be used to obtain inverter admittances with voltage and current different from the selected operating condition. To verify the correctness of the interpolated model, an operating condition of U1 = 0.9pu & I1 = 0.51pu was selected, and the interpolated model was compared with the model obtained through frequency scanning. Figure 4 As shown, the two are basically consistent. This completes the external admittance modeling of the grid-connected inverter across the entire operating range.

[0097] In summary, this invention discloses a method for constructing a multi-condition external admittance model for grid-connected inverters based on an interpolation algorithm. It can perform multi-condition admittance modeling for inverters containing black-box controllers. Compared to existing multi-condition modeling methods, this invention obtains the external admittance model of the inverter under multiple operating conditions through an interpolation algorithm, without requiring detailed controller structure and parameters, thus exhibiting strong applicability. Furthermore, the algorithm of this invention is based on the general modeling of grid-connected inverters, possessing model-driven characteristics and improving modeling efficiency.

[0098] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

[0099] Example 3, the third embodiment of the present invention, differs from the previous two embodiments in that:

[0100] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0101] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0102] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0103] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0104] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0105] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for constructing a multi-condition external admittance model for grid-connected inverters based on interpolation algorithms, characterized in that: include, Determine the operating condition range to be modeled and select typical operating conditions. Use the frequency scanning method to obtain the external admittance model of the grid-connected inverter under the selected typical operating conditions. Under the premise of fixed current and voltage, the external admittance model under different voltage and current conditions is interpolated; The inverter model for the entire operating range is obtained by further interpolating the data obtained by interpolation under non-selected operating conditions. The operating conditions include the inverter output voltage U1 and current I1; the selection of typical operating conditions needs to include the complete range of operating conditions, and the selected operating conditions in the same group need to meet the requirements of the same voltage or the same current. Under the premise of meeting the preset frequency standard, when the voltage is constant, the inverter admittance model is proportional to the current; when the current is constant, the admittance model is monotonic with the voltage. The external admittance model includes performing FFT analysis on the response current or voltage and the input voltage or current by superimposing small-signal voltages or currents of different frequencies at the grid-connected inverter port. The ratio of the current component to the voltage component is the measured inverter admittance. The external admittance of the grid-connected inverter is obtained through the measured signal. The calculation method is as follows: In the formula: Let be the angular frequency, corresponding to the Laplace operator s, and i p1,1 i p2,1 u p1,1 u p2,1 with i p1,2 i p2,2 u p1,2 u p2,2 These are the first and second groups of current and voltage signals at corresponding frequencies extracted by FFT, respectively. The interpolation process for the external admittance model under different voltage and current conditions includes, under the premise of a fixed current or voltage, the theoretical basis for interpolating the external admittance model under different voltage or current conditions to obtain a new operating condition model is described as follows: The mathematical model of the inverter's main circuit is expressed as follows: Among them, U d U q I d and I q These are the voltage and current dq components at the grid connection point, respectively; U dc It is the DC bus voltage; It is the power frequency angular frequency; D d and D q These represent the duty cycles of the d-axis and q-axis, respectively. L For the inverter's filter inductance; The linearized model of the circuit is: Among them, subscript Represents a complex vector, that is , For the corresponding state variables.

2. The method for constructing a multi-condition external admittance model for a grid-connected inverter based on an interpolation algorithm as described in claim 1, characterized in that: The interpolation processing of the external admittance model under different voltage and current conditions includes, for the inverter controller, since the phase-locked loop and current loop are the basic control links, taking into account the influence, the small-signal model of the control circuit is expressed as: in, It is the transfer function of the inner current loop; It is the carrier amplitude of the inverter; It is the small phase angle disturbance of the phase-locked loop output, expressed as: in, It is the transfer function of the phase-locked loop.

3. The method for constructing a multi-condition external admittance model for grid-connected inverters based on interpolation algorithms as described in claim 2, characterized in that: The interpolation process for the external admittance model under different voltage and current conditions includes introducing... and The following formula is obtained: in, , and Specifically, it can be elaborated as follows: in, U 1 and I 1 represents the inverter output voltage and current, respectively; L For the inverter's filter inductance; This is the feedforward decoupling coefficient of the inner current loop.

4. The method for constructing a multi-condition external admittance model for a grid-connected inverter based on an interpolation algorithm as described in claim 3, characterized in that: The interpolation process for the external admittance model under different voltage and current conditions also includes, by simplifying, obtaining the external admittance matrix elements of the grid-connected inverter as follows: For grid-connected inverters, when the frequency is constant, the specific formula is as follows: in, The elements of the inverter external admittance model matrix are functions of operating conditions U1 and I1; a, b, c, d, and e are all constants. Interpolation processing is performed on the external admittance model under different currents or voltages with a fixed voltage or current.

5. The method for constructing a multi-condition external admittance model for a grid-connected inverter based on an interpolation algorithm as described in claim 4, characterized in that: The further interpolation includes obtaining an inverter admittance model operating condition that is the same as one of the selected operating conditions, i.e., the voltage or current is the same, and obtaining an inverter admittance with both voltage and current different from the selected operating condition through further interpolation, thus completing the external admittance modeling of the grid-connected inverter within the full range of operating conditions.

6. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 5.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 5.

Images