A method for modeling harmonic impedance of a converter and related devices

Abstract

The application discloses a kind of converter harmonic impedance modeling method and related equipment, belong to converter technical field, first obtain grid-connected point voltage and the space vector of current, space vector can accurately reflect the size and direction of voltage and current in real time, compared with traditional scalar modeling, provide more comprehensive information.Harmonic power under positive and negative sequence harmonic influence is sequentially calculated based on space vector, reference voltage after power control loop and harmonic voltage output by inverter, based on inverter side and grid-connected point positive sequence harmonic voltage, negative sequence harmonic voltage and power grid main circuit, the modeling of harmonic impedance model is carried out, the harmonic model of coupling frequency impedance matrix form is used, the interaction relationship between harmonic voltage and harmonic current can be more accurately described, the coupling relationship of different frequency harmonics after converter, so as to improve the accuracy and reliability of analysis result, provide a solid model foundation for harmonic flow research.

Description

Technical Field

[0001] This invention belongs to the field of converter technology, specifically a converter harmonic impedance modeling method and related equipment. Background Technology

[0002] In recent years, the demand for renewable energy has been increasing, and power electronic devices and equipment have gradually penetrated into my country's power system. As a core component of new energy grid-connected systems, the optimization of grid-connected converters and the improvement of their modeling techniques are crucial for the stable operation of the power system and the improvement of power quality. Through power control strategies, grid-connected converters can provide voltage and frequency support to the grid, effectively addressing operational challenges under weak grid conditions. Harmonic impedance modeling, as an effective means of analyzing the dynamic interaction between grid-connected converters and the grid, has become a current research hotspot.

[0003] In the field of harmonic impedance modeling, harmonic linearization is a classic and widely used technique. It establishes a linear relationship between harmonic voltage and harmonic current by linearizing the system under small disturbance conditions. This method, based on system circuit parameters, control structure, and rated operating state, obtains the system's harmonic impedance model by injecting a small voltage signal of a specific frequency and measuring the corresponding current response. However, with the increasing complexity and nonlinearity of new energy grid-connected systems, existing harmonic linearization methods are facing challenges in terms of accuracy and applicability.

[0004] In the harmonic impedance modeling of converters, the existing technology has the following technical shortcomings:

[0005] 1) Limited model accuracy: Because the harmonic linearization method ignores higher-order nonlinear terms, the model has insufficient accuracy in complex nonlinear systems and strong coupling effects.

[0006] 2) Improper handling of frequency coupling effect: In power systems, there may be coupling relationships between different harmonics. Existing models often use simplified methods to deal with this coupling effect, which makes the models unable to accurately reflect the real behavior of the system.

[0007] 3) Impedance modeling difficulties: When the AC system is unbalanced, the steady-state operating point will no longer be a constant DC value. Existing models have difficulties in impedance modeling under unbalanced conditions, which limits the practical application range of the models. Summary of the Invention

[0008] This invention provides a method and related equipment for modeling harmonic impedance of converters, which solves the problems of difficulty in modeling harmonic impedance of converters and limited model accuracy.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] A method for modeling harmonic impedance of a converter includes:

[0011] Inject harmonics at the grid connection point to obtain the space vectors of the grid connection point voltage and current.

[0012] The active and reactive power injected into the grid is calculated based on the space vector of voltage and current at the grid connection point.

[0013] Active and reactive power are fed into the power control loop to obtain the amplitude and phase of the reference voltage;

[0014] The magnitude and phase of the reference voltage are combined into a reference vector, and the d-axis and q-axis components of the reference voltage in the dq coordinate system are obtained based on the reference vector.

[0015] Based on the d-axis and q-axis components of the reference voltage in the dq coordinate system, the reference voltage is transformed to the abc coordinate system to obtain the positive-sequence harmonic voltage and the negative-sequence harmonic voltage.

[0016] Obtain the voltage and current relationship of the main circuit of the power grid, and establish a harmonic impedance model based on the voltage and current relationship of the main circuit of the power grid and the positive and negative harmonic voltages.

[0017] Preferably, the method for obtaining the space vectors of the grid connection point voltage and current is as follows:

[0018]

[0019] in, The amplitude of the fundamental voltage at the grid connection point, For natural constants, For the fundamental voltage phase at the grid connection point, For imaginary numbers, The positive sequence harmonic voltage amplitude at the grid connection point. For the positive sequence harmonic voltage phase at the grid connection point, The negative sequence harmonic voltage amplitude at the grid connection point. For the negative sequence harmonic voltage phase at the grid connection point, The amplitude of the fundamental current at the grid connection point, Phase of the fundamental current at the grid connection point, The amplitude of the positive sequence harmonic current at the grid connection point, For the phase of the positive sequence harmonic current at the grid connection point, For the amplitude of negative sequence harmonic current at the grid connection point, This refers to the phase of the negative sequence harmonic current at the grid connection point.

[0020] Preferably, the steps for calculating the active and reactive power injected into the grid based on the space vectors of the grid connection point voltage and current are as follows:

[0021] The complex power at the grid connection point is calculated based on the spatial vectors of the voltage and current at the grid connection point. The real and imaginary parts of the complex power are then separated to obtain the active and reactive power injected into the grid.

[0022] Preferably, the amplitude and phase of the reference voltage are as follows:

[0023]

[0024]

[0025] in, For the phase of the reference voltage, The amplitude of the reference voltage, Inverter droop factor, Active power reference value For reactive power reference value, For reactive power, For active power, The rated angular frequency of the inverter output, This refers to the rated phase of the inverter's output voltage.

[0026] A converter harmonic impedance modeling system includes:

[0027] Vector acquisition module: used to inject harmonics at the grid connection point and acquire the space vectors of the grid connection point voltage and current;

[0028] Power calculation module: used to calculate the active and reactive power injected into the grid based on the space vector of voltage and current at the grid connection point;

[0029] Feed-in module: Used to feed active and reactive power into the power control loop to obtain the amplitude and phase of the reference voltage;

[0030] Synthesis module: Used to synthesize the amplitude and phase of the reference voltage into a reference vector, and obtain the d-axis component and q-axis component of the reference voltage in the dq coordinate system based on the reference vector;

[0031] Conversion module: used to convert the reference voltage to the abc coordinate system based on the d-axis and q-axis components of the reference voltage in the dq coordinate system, to obtain the positive sequence harmonic voltage and the negative sequence harmonic voltage;

[0032] Modeling module: Used to obtain the voltage and current relationship of the main circuit of the power grid, and to establish a harmonic impedance model based on the voltage and current relationship of the main circuit of the power grid and the positive and negative harmonic voltages.

[0033] Preferably, in the vector acquisition module, the method for acquiring the space vectors of the grid connection point voltage and current is as follows:

[0034]

[0035] in, The amplitude of the fundamental voltage at the grid connection point, For natural constants, For the fundamental voltage phase at the grid connection point, For imaginary numbers, The positive sequence harmonic voltage amplitude at the grid connection point. For the positive sequence harmonic voltage phase at the grid connection point, The negative sequence harmonic voltage amplitude at the grid connection point. For the negative sequence harmonic voltage phase at the grid connection point, The amplitude of the fundamental current at the grid connection point, Phase of the fundamental current at the grid connection point, The amplitude of the positive sequence harmonic current at the grid connection point, For the phase of the positive sequence harmonic current at the grid connection point, For the amplitude of negative sequence harmonic current at the grid connection point, This refers to the phase of the negative sequence harmonic current at the grid connection point.

[0036] Preferably, in the power calculation module, the steps for calculating the active and reactive power injected into the grid based on the space vectors of the grid connection point voltage and current are as follows:

[0037] The complex power at the grid connection point is calculated based on the spatial vectors of the voltage and current at the grid connection point. The real and imaginary parts of the complex power are then separated to obtain the active and reactive power injected into the grid.

[0038] Preferably, in the feed module, the amplitude and phase of the reference voltage are as follows:

[0039]

[0040]

[0041] in, For the phase of the reference voltage, The amplitude of the reference voltage, Inverter droop factor, Active power reference value For reactive power reference value, For reactive power, For active power, The rated angular frequency of the inverter output, This refers to the rated phase of the inverter's output voltage.

[0042] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements steps such as a converter harmonic impedance modeling method.

[0043] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of a converter harmonic impedance modeling method.

[0044] Compared with existing technologies, this invention has the following advantages: This invention provides a converter harmonic impedance modeling method. First, it obtains the space vectors of voltage and current at the grid connection point. The space vectors can reflect the magnitude and direction of voltage and current in real time and accurately, providing more comprehensive information compared to traditional scalar modeling. Based on the space vectors, the harmonic power under the influence of positive and negative sequence harmonics is calculated sequentially. The reference voltage after the power control loop and the harmonic voltage output by the inverter are then calculated. Based on the positive and negative sequence harmonic voltages at the inverter side and the grid connection point, as well as the main circuit of the power grid, a harmonic impedance model is constructed. The harmonic model in the form of a coupled frequency impedance matrix can more accurately describe the interaction between harmonic voltage and harmonic current, and the coupling relationship of different frequency harmonics after passing through the converter, thereby improving the accuracy and reliability of the analysis results and providing a solid model foundation for harmonic power flow research. Attached Figure Description

[0045] Figure 1 This is a flowchart of a converter harmonic impedance modeling method according to the present invention;

[0046] Figure 2 This is a grid-connected topology diagram of a grid-type converter according to an embodiment of the present invention;

[0047] Figure 3 This is a flowchart of a converter harmonic impedance modeling system according to the present invention. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0049] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0050] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0051] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0052] like Figure 1 As shown, the present invention provides a converter harmonic impedance modeling method, including:

[0053] S101 injects harmonics at the grid connection point and obtains the space vectors of the grid connection point voltage and current.

[0054] S102 calculates the active and reactive power injected into the grid based on the space vector of voltage and current at the grid connection point;

[0055] S103 feeds active and reactive power into the power control loop to obtain the amplitude and phase of the reference voltage;

[0056] S104 synthesizes the amplitude and phase of the reference voltage into a reference vector, and obtains the d-axis component and q-axis component of the reference voltage in the dq coordinate system based on the reference vector;

[0057] S105 transforms the reference voltage to the abc coordinate system based on the d-axis and q-axis components of the reference voltage in the dq coordinate system, thereby obtaining the positive-sequence harmonic voltage and the negative-sequence harmonic voltage.

[0058] S106 obtains the voltage and current relationship of the main circuit of the power grid, and establishes a harmonic impedance model based on the voltage and current relationship of the main circuit of the power grid and the positive and negative harmonic voltages.

[0059] Furthermore, the specific method for obtaining the space vectors of the grid connection point voltage and current is as follows:

[0060]

[0061] in, The amplitude of the fundamental voltage at the grid connection point, For natural constants, For the fundamental voltage phase at the grid connection point, For imaginary numbers, The positive sequence harmonic voltage amplitude at the grid connection point. For the positive sequence harmonic voltage phase at the grid connection point, The negative sequence harmonic voltage amplitude at the grid connection point. For the negative sequence harmonic voltage phase at the grid connection point, The amplitude of the fundamental current at the grid connection point, Phase of the fundamental current at the grid connection point, The amplitude of the positive sequence harmonic current at the grid connection point, For the phase of the positive sequence harmonic current at the grid connection point, For the amplitude of negative sequence harmonic current at the grid connection point, This refers to the phase of the negative sequence harmonic current at the grid connection point.

[0062] Furthermore, the specific steps for calculating the active and reactive power injected into the grid based on the space vectors of the grid connection point voltage and current are as follows:

[0063] The complex power at the grid connection point is calculated based on the spatial vectors of the voltage and current at the grid connection point. The real and imaginary parts of the complex power are then separated to obtain the active and reactive power injected into the grid.

[0064] Furthermore, the amplitude and phase of the reference voltage are as follows:

[0065]

[0066]

[0067] in, For the phase of the reference voltage, The amplitude of the reference voltage, Inverter droop factor, Active power reference value For reactive power reference value, For reactive power, For active power, The rated angular frequency of the inverter output, This refers to the rated phase of the inverter's output voltage.

[0068] Another embodiment of the present invention provides a converter harmonic impedance modeling method for a grid-type converter based on droop control;

[0069] Compared to traditional grid-connected converters, grid-connected converters can independently establish the grid's frequency and voltage, possessing voltage maintenance and active inertial support capabilities. By simulating the function of a synchronous generator, they provide support for the stability of the power system. Grid-connected converters do not rely on grid-side synchronous generator regulation, enabling AC power systems to operate under complex conditions.

[0070] Injecting harmonics into the system, the steady-state voltage and current at the grid connection point can be expressed as:

[0071]

[0072] Since the three-phase voltage and current differ by 120°, the voltage and current expressions for phase b and phase c at the grid connection point can be easily obtained based on the phase relationships under positive and negative sequences. The active and reactive power in the control loop are calculated using the voltage and current at the grid connection point. For ease of representation, the complex power at the grid connection point is calculated using the voltage and current space vectors. The complex power expression is shown in equation (2).

[0073]

[0074] and The voltage and current space vectors at the grid connection point are expressed in equation (3).

[0075]

[0076] Substituting equation (3) into equation (2), the real and imaginary parts of the complex power can be separated to obtain the active and reactive power injected into the power grid.

[0077]

[0078] Equation (4) consists of two types of power: DC power and AC power. DC power is composed of fundamental frequency power and harmonic power of the same frequency, while AC power is determined by voltage and current of different frequencies. DC power and power reference value. and The difference between the power and the reference voltage generated by the power control module determines the steady-state operating point of the AC system. Therefore, only the AC component in the power will cause harmonics in the reference voltage.

[0079] Active and reactive power are fed into the power control loop to generate a reference voltage. The mathematical model is expressed as follows:

[0080]

[0081] Substituting equation (4) into equation (5) yields the amplitude and phase of the reference voltage.

[0082]

[0083] The voltage synthesis module yields the d-axis and q-axis components of the reference voltage. When the system reaches steady state, the voltage reference phase... have

[0084]

[0085] Assuming that the d-axis coincides with the reference voltage space vector, a first-order Taylor series expansion is performed near the steady-state operating point of the system, ignoring higher-order nonlinear terms, and the response generated by the harmonics after passing through the voltage synthesis module is obtained as shown in (8).

[0086]

[0087] For low-order harmonics, the output voltage of the voltage synthesis module is the same as the voltage at the VSC device terminal. By converting the voltage in the synchronous rotating coordinate system back to the abc coordinate system, the equation can be obtained as shown in (9).

[0088]

[0089] Since there is no coupling effect between the positive and negative sequences, the kth positive sequence harmonic voltage and the negative sequence harmonic voltage can be expressed as (10) and (11).

[0090]

[0091] according to Figure 1 Inverter voltage With grid connection point voltage and current The relationship is

[0092]

[0093] Substituting (10) and (11) into (12) yields

[0094]

[0095] From the final expressions in (13) and (14), it can be determined that, in addition to the interaction between harmonics of the same frequency, the control loop introduces the interaction between different harmonics, such as the positive 5th harmonic current causing the positive 3rd harmonic voltage. Based on the above derivation, the harmonic impedance model of the grid converter can be expressed as follows:

[0096]

[0097] like Figure 3 As shown, another embodiment of the present invention provides a converter harmonic impedance modeling system, comprising:

[0098] Vector acquisition module: used to inject harmonics at the grid connection point and acquire the space vectors of the grid connection point voltage and current;

[0099] Power calculation module: used to calculate the active and reactive power injected into the grid based on the space vector of voltage and current at the grid connection point;

[0100] Feed-in module: Used to feed active and reactive power into the power control loop to obtain the amplitude and phase of the reference voltage;

[0101] Synthesis module: Used to synthesize the amplitude and phase of the reference voltage into a reference vector, and obtain the d-axis component and q-axis component of the reference voltage in the dq coordinate system based on the reference vector;

[0102] Conversion module: used to convert the reference voltage to the abc coordinate system based on the d-axis and q-axis components of the reference voltage in the dq coordinate system, to obtain the positive sequence harmonic voltage and the negative sequence harmonic voltage;

[0103] Modeling module: Used to obtain the voltage and current relationship of the main circuit of the power grid, and to establish a harmonic impedance model based on the voltage and current relationship of the main circuit of the power grid and the positive and negative harmonic voltages.

[0104] In the vector acquisition module, the specific method for obtaining the space vectors of grid connection point voltage and current is as follows:

[0105]

[0106] in, The amplitude of the fundamental voltage at the grid connection point, For natural constants, For the fundamental voltage phase at the grid connection point, For imaginary numbers, The positive sequence harmonic voltage amplitude at the grid connection point. For the positive sequence harmonic voltage phase at the grid connection point, The negative sequence harmonic voltage amplitude at the grid connection point. For the negative sequence harmonic voltage phase at the grid connection point, The amplitude of the fundamental current at the grid connection point, Phase of the fundamental current at the grid connection point, The amplitude of the positive sequence harmonic current at the grid connection point, For the phase of the positive sequence harmonic current at the grid connection point, For the amplitude of negative sequence harmonic current at the grid connection point, This refers to the phase of the negative sequence harmonic current at the grid connection point.

[0107] In the power calculation module, the specific steps for calculating the active and reactive power injected into the grid based on the space vector of the grid connection point voltage and current are as follows:

[0108] The complex power at the grid connection point is calculated based on the spatial vectors of the voltage and current at the grid connection point. The real and imaginary parts of the complex power are then separated to obtain the active and reactive power injected into the grid.

[0109] In the feed module, the amplitude and phase of the reference voltage are as follows:

[0110]

[0111]

[0112] in, For the phase of the reference voltage, The amplitude of the reference voltage, Inverter droop factor, Active power reference value For reactive power reference value, For reactive power, For active power, The rated angular frequency of the inverter output, This refers to the rated phase of the inverter's output voltage.

[0113] An embodiment of the present invention provides a terminal device. This terminal device includes a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps in the various method embodiments described above. Alternatively, when the processor executes the computer program, it implements the functions of each module / unit in the various device embodiments described above.

[0114] The computer program can be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present invention.

[0115] The terminal device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0116] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0117] The memory can be used to store the computer program and / or module. The processor implements various functions of the terminal device by running or executing the computer program and / or module stored in the memory and calling the data stored in the memory.

[0118] If the modules / units integrated into the terminal device 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, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electrical carrier signals and telecommunication signals.

[0119] Although embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, and not restrictive. Those skilled in the art, guided by the specification, can make many other modifications without departing from the scope of the claims of the present invention, and all of these modifications are within the scope of protection of the present invention.

Claims

1. A method for modeling harmonic impedance of a converter, characterized in that, include: Inject harmonics at the grid connection point to obtain the space vectors of the grid connection point voltage and current. The active and reactive power injected into the grid is calculated based on the space vector of voltage and current at the grid connection point. Active and reactive power are fed into the power control loop to obtain the amplitude and phase of the reference voltage; The magnitude and phase of the reference voltage are combined into a reference vector, and the d-axis and q-axis components of the reference voltage in the dq coordinate system are obtained based on the reference vector. Based on the d-axis and q-axis components of the reference voltage in the dq coordinate system, the reference voltage is transformed to the abc coordinate system to obtain the positive-sequence harmonic voltage and the negative-sequence harmonic voltage. Obtain the voltage and current relationship of the main circuit of the power grid, and establish a harmonic impedance model based on the voltage and current relationship of the main circuit of the power grid and the positive and negative harmonic voltages.

2. The converter harmonic impedance modeling method according to claim 1, characterized in that, The specific method for obtaining the space vectors of grid connection point voltage and current is as follows: in, The fundamental voltage amplitude at the grid connection point, For natural constants, For the fundamental voltage phase at the grid connection point, For imaginary numbers, The positive sequence harmonic voltage amplitude at the grid connection point. For the positive sequence harmonic voltage phase at the grid connection point, The negative sequence harmonic voltage amplitude at the grid connection point. For the negative sequence harmonic voltage phase at the grid connection point, The amplitude of the fundamental current at the grid connection point, For the fundamental current phase at the grid connection point, The amplitude of the positive sequence harmonic current at the grid connection point, For the phase of the positive sequence harmonic current at the grid connection point, The amplitude of the negative sequence harmonic current at the grid connection point, This refers to the phase of the negative sequence harmonic current at the grid connection point.

3. The converter harmonic impedance modeling method according to claim 1, characterized in that, The specific steps for calculating the active and reactive power injected into the grid based on the space vectors of the voltage and current at the grid connection point are as follows: The complex power at the grid connection point is calculated based on the spatial vectors of the voltage and current at the grid connection point. The real and imaginary parts of the complex power are then separated to obtain the active and reactive power injected into the grid.

4. The converter harmonic impedance modeling method according to claim 1, characterized in that, The magnitude and phase of the reference voltage are as follows: in, For the phase of the reference voltage, The amplitude of the reference voltage, Inverter droop factor, Active power reference value For reactive power reference value, For reactive power, For active power, The rated angular frequency of the inverter output, This refers to the rated phase of the inverter's output voltage.

5. A converter harmonic impedance modeling system, characterized in that, include: Vector acquisition module: used to inject harmonics at the grid connection point and acquire the space vectors of the grid connection point voltage and current; Power calculation module: used to calculate the active and reactive power injected into the grid based on the space vector of voltage and current at the grid connection point; Feed-in module: Used to feed active and reactive power into the power control loop to obtain the amplitude and phase of the reference voltage; Synthesis module: Used to synthesize the amplitude and phase of the reference voltage into a reference vector, and obtain the d-axis component and q-axis component of the reference voltage in the dq coordinate system based on the reference vector; Conversion module: used to convert the reference voltage to the abc coordinate system based on the d-axis and q-axis components of the reference voltage in the dq coordinate system, to obtain the positive sequence harmonic voltage and the negative sequence harmonic voltage; Modeling module: Used to obtain the voltage and current relationship of the main circuit of the power grid, and to establish a harmonic impedance model based on the voltage and current relationship of the main circuit of the power grid and the positive and negative harmonic voltages.

6. A converter harmonic impedance modeling system according to claim 5, characterized in that, In the vector acquisition module, the specific method for obtaining the space vectors of grid connection point voltage and current is as follows: in, The fundamental voltage amplitude at the grid connection point, For natural constants, For the fundamental voltage phase at the grid connection point, For imaginary numbers, The positive sequence harmonic voltage amplitude at the grid connection point. For the positive sequence harmonic voltage phase at the grid connection point, The negative sequence harmonic voltage amplitude at the grid connection point. For the negative sequence harmonic voltage phase at the grid connection point, The amplitude of the fundamental current at the grid connection point, For the fundamental current phase at the grid connection point, The amplitude of the positive sequence harmonic current at the grid connection point, For the phase of the positive sequence harmonic current at the grid connection point, The amplitude of the negative sequence harmonic current at the grid connection point, This refers to the phase of the negative sequence harmonic current at the grid connection point.

7. A converter harmonic impedance modeling system according to claim 5, characterized in that, In the power calculation module, the specific steps for calculating the active and reactive power injected into the grid based on the space vector of the grid connection point voltage and current are as follows: The complex power at the grid connection point is calculated based on the spatial vectors of the voltage and current at the grid connection point. The real and imaginary parts of the complex power are then separated to obtain the active and reactive power injected into the grid.

8. A converter harmonic impedance modeling system according to claim 5, characterized in that, In the feed module, the amplitude and phase of the reference voltage are as follows: in, For the phase of the reference voltage, The amplitude of the reference voltage, Inverter droop factor, Active power reference value For reactive power reference value, For reactive power, For active power, The rated angular frequency of the inverter output, This refers to the rated phase of the inverter's output voltage.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the converter harmonic impedance modeling method as described in any one of claims 1 to 4.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the converter harmonic impedance modeling method as described in any one of claims 1 to 4.

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