Method, system and equipment for judging grid-connected oscillation of power electronic converter and medium

Abstract

The invention discloses a grid-connected oscillation judgment method, system and equipment of a power electronic converter and a medium, and particularly relates to the technical field of oscillation judgment, and the technical key points are as follows: constructing an amplitude-frequency curve and a phase-frequency curve by using the SISO impedance of a power grid and the SISO impedance of the power electronic converter obtained by broadband impedance measurement; in the amplitude-frequency curve, obtaining a frequency value when the SISO impedance characteristic amplitude of the power grid is equal to the SISO impedance characteristic amplitude of the power electronic converter, and obtaining a phase difference of the same frequency value in the phase-frequency curve; and combining the phase difference with a pre-constructed broadband oscillation criterion to obtain an oscillation judgment result of the converter grid-connected system. The SISO impedance characteristic of the power grid and the SISO impedance characteristic of the power electronic converter, which are obtained by broadband impedance measurement, are utilized to more conveniently and quickly judge whether the system has the risk of broadband oscillation caused by harmonic amplification of the system; meanwhile, a broadband oscillation criterion is provided, and a critical oscillation region is introduced, so that the grid-connected oscillation criterion is defined more clearly.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oscillation judgment, in particular to a power electronic converter grid-connected oscillation judgment method, system, device and medium. BACKGROUND

[0002] With the progress of power electronic converter grid-connected (for example: photovoltaic, wind power grid-connected, full-power variable speed pumping grid-connected, high-speed railway, etc.), a large number of power electronic converters are connected to the grid. Due to the mismatch between the impedance characteristics of the power electronic converter and the grid, the system may have insufficient phase margin in some specific frequency bands, which may cause system oscillation problems. Therefore, accurately obtaining the wideband impedance characteristics of the power electronic converter grid-connected system is the key to analyzing the wideband oscillation of the system.

[0003] The existing power electronic converter grid-connected oscillation criterion is often based on multiple-input multiple-output (MIMO) impedance characteristics; the MIMO impedance characteristics of the power electronic converter grid-connected system are obtained through impedance modeling / measurement, and then the eigenvalues of the corresponding MIMO impedance are solved, and the impedance ratio analysis is performed using the eigenvalues to determine whether the system has wideband oscillation phenomenon; but the existing technology needs to obtain the MIMO impedance characteristics of the power electronic converter grid-connected system, and then solve the eigenvalues for impedance ratio analysis to determine whether the system oscillates, which is more complex. At the same time, the existing technology simply uses the positive and negative of the phase margin to determine whether the system oscillates, but in actual application, sometimes the system with positive phase margin may also oscillate (weak phase margin), for which the existing technology is not accurate. SUMMARY

[0004] The technical problem to be solved by the present application is that the process of using MIMO impedance characteristics to solve eigenvalues for impedance ratio analysis to determine whether the system oscillates is relatively complex. The purpose is to provide a power electronic converter grid-connected oscillation judgment method, system, device and medium, which uses the grid SISO impedance characteristics and the power electronic converter SISO impedance characteristics obtained by wideband impedance measurement to more conveniently and quickly determine whether the system has harmonic amplification and thus leads to the risk of wideband oscillation of the system, solving the problem of using MIMO impedance characteristics to solve eigenvalues for impedance ratio analysis to determine whether the system oscillates, which is relatively complex. At the same time, a wideband oscillation criterion is provided, which introduces a critical oscillation region to make the grid-connected oscillation criterion more clear.

[0005] The present application is implemented by the following technical solutions:

[0006] A power electronic converter grid-connected oscillation judgment method, the method comprising:

[0007] In the grid-connected system of the converter, the grid SISO impedance and the power electronic converter SISO impedance obtained by wideband impedance measurement are used to construct the amplitude-frequency curve and the phase-frequency curve.

[0008] In the amplitude-frequency curve, the frequency value at which the amplitude of the grid SISO impedance characteristic is equal to the amplitude of the power electronic converter SISO impedance characteristic is obtained, and in the phase-frequency curve, the phase difference of the same frequency value is obtained.

[0009] The phase difference is used in combination with the pre-constructed wideband oscillation criterion to obtain the oscillation judgment result of the converter grid-connected system.

[0010] Further, in the grid-connected system of the converter, the grid SISO impedance and the power electronic converter SISO impedance obtained by wideband impedance measurement are used, specifically:

[0011] Harmonic disturbance is injected into the grid-connected point in the grid-connected system of the converter, the port response voltage and current information is obtained, and the grid SISO impedance and the power electronic converter SISO impedance are calculated using the port response voltage and current information.

[0012] Further, the method further comprises:

[0013] An equivalent impedance model of the grid-connected system is constructed, and the equivalent grid voltage, the converter impedance characteristic and the grid impedance characteristic are obtained.

[0014] The equivalent grid voltage, the converter impedance characteristic and the grid impedance characteristic are used to construct a voltage relationship function of the grid-connected system of the converter.

[0015] The correlation between the phase difference and the wideband oscillation phenomenon is obtained according to the voltage relationship function of the grid-connected system of the converter, and a wideband oscillation criterion is constructed based on the correlation between the phase difference and the wideband oscillation phenomenon.

[0016] Further, the pre-constructed wideband oscillation criterion is specifically:

[0017] When the phase difference is between 0° and 120°, the grid-connected system of the power electronic converter is stable.

[0018] When the phase difference is between 120° and 180°, the grid-connected system of the power electronic converter has an oscillation risk.

[0019] When the phase difference is between 180° and 360°, the grid-connected system of the power electronic converter oscillates.

[0020] The application also provides a power electronic converter grid-connected oscillation judgment system, which is used in the power electronic converter grid-connected oscillation judgment method described above, and the system comprises:

[0021] A curve construction module is configured to construct an amplitude-frequency curve and a phase-frequency curve by using grid SISO impedance and power electronic converter SISO impedance obtained by wideband impedance measurement in a converter grid-connected system.

[0022] A phase difference acquisition module is configured to acquire a frequency value at which a grid SISO impedance characteristic amplitude is equal to a power electronic converter SISO impedance characteristic amplitude in the amplitude-frequency curve, and acquire a phase difference of the same frequency value in the phase-frequency curve.

[0023] A system oscillation judgment module is configured to obtain a converter grid-connected system oscillation judgment result by using the phase difference in combination with a pre-constructed wideband oscillation criterion.

[0024] Further, in the converter grid-connected system, the grid SISO impedance and the power electronic converter SISO impedance obtained by wideband impedance measurement are specifically as follows:

[0025] A harmonic disturbance is injected into a grid-connected point in the converter grid-connected system, port response voltage and current information is acquired, and the grid SISO impedance and the power electronic converter SISO impedance are calculated by using the port response voltage and current information.

[0026] Further, the method further comprises:

[0027] An equivalent impedance model of the grid-connected system is constructed, equivalent grid voltage, converter impedance characteristics and grid impedance characteristics are acquired;

[0028] The equivalent grid voltage, the converter impedance characteristics and the grid impedance characteristics are used to construct a converter grid-connected system voltage relationship function;

[0029] An association relationship between the phase difference and the wideband oscillation phenomenon is acquired according to the converter grid-connected system voltage relationship function, and a wideband oscillation criterion is constructed based on the association relationship between the phase difference and the wideband oscillation phenomenon.

[0030] The application also provides a computer device comprising a system memory and a processor, wherein the system memory stores a computer program, and the processor implements the steps of the method in any one of the above embodiments when executing the computer program.

[0031] The application also provides a computer readable storage medium, which stores a computer program, and the computer program implements the steps of the method in any one of the above embodiments when executed by a processor.

[0032] The application also provides a computer program product comprising instructions, which, when executed by a computer device cluster, cause the computer device cluster to perform the method in any one of the above embodiments.

[0033] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0034] In this invention, the SISO impedance characteristics of the power grid and the SISO impedance characteristics of the power electronic converter obtained by wideband impedance measurement are used to more conveniently and quickly determine whether the system has harmonic amplification and thus the risk of wideband oscillation. This solves the problem that the process of using MIMO impedance characteristics to solve eigenvalues ​​and perform impedance ratio analysis to determine whether the system oscillates is relatively complicated. At the same time, a wideband oscillation criterion is provided, introducing a critical oscillation region, which makes the definition of grid-connected oscillation criteria clearer. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0036] Figure 1 This is a flowchart illustrating a method for determining grid-connected oscillations in a power electronic converter, as described in this embodiment.

[0037] Figure 2 This is a circuit diagram of the equivalent impedance model of the grid-connected system given in this embodiment;

[0038] Figure 3 This is a schematic diagram of the phase difference in the oscillation criterion region given in this embodiment;

[0039] Figure 4 This is a schematic diagram of the amplitude-frequency curve and phase-frequency curve in this embodiment example;

[0040] Figure 5 This is a schematic diagram of the DC voltage output of the power electronic converter under different grid equivalent resistances in this example embodiment;

[0041] Figure 6 This is a schematic diagram of a power electronic converter grid-connected oscillation judgment system in this embodiment;

[0042] Figure 7 This is a schematic diagram of the structure of a computer device in this embodiment. Detailed Implementation

[0043] The exemplary embodiments of this disclosure are described below with reference to the accompanying drawings, including various details of the embodiments to aid understanding, and should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope of this disclosure. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.

[0044] In this disclosure, unless otherwise stated, the use of terms such as "first," "second," etc., to describe various elements is not intended to limit the positional, temporal, or importance relationships of these elements; such terms are merely used to distinguish one element from another. In some examples, the first element and the second element may refer to the same instance of that element, while in other cases, based on the context, they may refer to different instances.

[0045] The terminology used in the description of the various examples in this disclosure is for the purpose of describing particular examples only and is not intended to be limiting. Unless the context explicitly indicates otherwise, an element may be one or more unless the number of elements is specifically limited. Furthermore, the term "and / or" as used in this disclosure covers any one of the listed items and all possible combinations thereof.

[0046] Example 1

[0047] See Figure 1 , Figure 1 This embodiment illustrates a flowchart of a method for determining grid-connected oscillations in a power electronic converter. The method includes:

[0048] S1: In a converter grid-connected system, the amplitude-frequency curve and phase-frequency curve are constructed using the grid SISO impedance and power electronic converter SISO impedance obtained by wideband impedance measurement.

[0049] It should be noted that in a power electronic converter grid-connected system, the grid SISO impedance and power electronic converter SISO impedance obtained by broadband impedance measurement can be used to further analyze the system stability. The stability criterion is as follows: In the formula, SISO impedance characteristics of the power grid; The SISO impedance characteristics of the power electronic converter can be analyzed to determine system stability. Phase margin is achieved; where SISO impedance characteristic refers to single-input single-output impedance characteristic.

[0050] S2: In the amplitude-frequency curve, obtain the frequency value when the amplitude of the SISO impedance characteristic of the power grid is equal to the amplitude of the SISO impedance characteristic of the power electronic converter, and obtain the phase difference of the same frequency value in the phase-frequency curve.

[0051] S3: Using the phase difference combined with the pre-constructed wideband oscillation criterion, the oscillation judgment result of the converter grid-connected system is obtained.

[0052] Specifically, in this invention, the SISO impedance characteristics of the power grid and the SISO impedance characteristics of the power electronic converter obtained by wideband impedance measurement can be used to more conveniently and quickly determine whether the system has harmonic amplification, which may lead to the risk of wideband oscillation. This solves the problem that the process of using MIMO impedance characteristics to solve eigenvalues ​​and perform impedance ratio analysis to determine whether the system is oscillating is relatively complex. At the same time, a wideband oscillation criterion is provided, introducing a critical oscillation region, which makes the definition of grid-connected oscillation criteria clearer.

[0053] In another implementation, harmonic disturbances are injected into the grid connection point of the converter grid connection system to obtain port response voltage and current information. The grid SISO impedance and power electronic converter SISO impedance are calculated using the port response voltage and current information. The calculation method is to divide the port voltage by the port current. This SISO impedance calculation method is a conventional technique in the field and will not be described in detail here.

[0054] In another implementation, the method further includes: constructing an equivalent impedance model of the grid-connected system to obtain the equivalent grid voltage, converter impedance characteristics, and grid impedance characteristics; using the equivalent grid voltage, converter impedance characteristics, and grid impedance characteristics to construct a voltage relationship function for the converter-grid-connected system; obtaining the correlation between phase difference and broadband oscillation phenomenon based on the voltage relationship function of the converter-grid-connected system, and constructing a broadband oscillation criterion based on the correlation between phase difference and broadband oscillation phenomenon.

[0055] Specifically, in this embodiment, see Figure 2 The diagram shows a circuit schematic of the equivalent impedance model of a grid-connected system. Using the equivalent grid voltage, converter impedance characteristics, and grid impedance characteristics, a voltage relationship function for the converter-grid-connected system is constructed, specifically as follows: ,in, and These are the equivalent grid voltage and the grid connection point voltage of the power electronic converter, respectively. The impedance characteristics of the power grid; Impedance characteristics of power electronic converters;

[0056] When the amplitude of the SISO impedance characteristic of the power grid is equal to the amplitude of the SISO impedance characteristic of the power electronic converter, that is, at the intersection of the amplitude-frequency curves, and Equal, therefore In this case, the above relational function is: Therefore, if Phase difference , No comparison A large value indicates that no harmonics are amplified, and the system has sufficient phase margin; if Phase difference , It will be more than A large phase margin indicates the possibility of harmonic amplification in the system, and insufficient phase margin leads to the risk of broadband oscillation. When the phase difference is greater than 180°, the system phase margin is less than 0°, and broadband oscillation will occur.

[0057] Based on the above analysis, see Figure 3 As shown, when the phase difference is less than 120°, it is located at Figure 3 The green (stable) region indicates that sufficient phase margin will maintain system stability; as the phase difference increases, the phase margin decreases; when the phase difference is greater than 120° and less than 180°, it is located in... Figure 3 In the gray (critical oscillation) region, a weak phase margin may lead to amplification of corresponding harmonics, posing a risk of broadband oscillation; when the phase difference is greater than 180° and less than 360°, it is located in... Figure 3 In the red (oscillation) region, a negative phase margin will cause the system to experience broadband oscillations or even instability. Therefore, the constructed broadband oscillation criterion is as follows: when the phase difference is between 0° and 120°, the power electronic converter grid-connected system is stable; when the phase difference is between 120° and 180°, the power electronic converter grid-connected system has the risk of oscillation; when the phase difference is between 180° and 360°, the power electronic converter grid-connected system oscillates.

[0058] For example, in this embodiment, an example is given where, with the power electronic converter parameters unchanged, the equivalent resistance value on the grid side is changed (0.01Ω, 0.04Ω, 0.07Ω), and its amplitude-frequency curve and phase-frequency curve are as follows. Figure 4 As shown, the red line represents the grid impedance, the blue line represents the power electronic converter impedance, and the pink line represents the phase margin curve. It can be seen that at the intersection of the amplitudes of the power electronic converter impedance and the grid impedance, the system phase margin is small, around 0°, so the system will exhibit oscillation.

[0059] First, the equivalent resistance of the power grid is set to 0.01Ω. The system has the smallest and negative phase margin, and is in a state of... Figure 3 The red area in the diagram indicates that the system may be experiencing oscillation and divergence. The actual system output is as follows: Figure 5As shown in (a), the system is indeed in an oscillating divergent state at this point; when the equivalent resistance of the power grid increases to 0.04Ω, the phase margin of the system improves, and it is in a state of oscillation and divergence. Figure 3 The gray area in the image will reduce the oscillation phenomenon, and the actual system output will behave as follows: Figure 5 As shown in (b), the system's divergent oscillations are reduced to approximately constant-amplitude oscillations. Finally, when the equivalent grid resistance is further increased to 0.07Ω, the system's phase margin is further enhanced, and the oscillation phenomenon will be weakened. The actual system output performance is as follows: Figure 5 As shown in (c), the oscillation phenomenon of the system gradually decreases, but it is still in a state of flux. Figure 3 The gray area in the image still carries the risk of oscillation, manifesting as weak oscillations; this verifies the effectiveness of the broadband oscillation criterion proposed in this invention.

[0060] Example 2

[0061] See Figure 6 As shown, the present invention also provides a power electronic converter grid-connected oscillation judgment system, which is used in any of the above-described power electronic converter grid-connected oscillation judgment methods, the system comprising:

[0062] Curve construction module 100 is used to construct amplitude frequency curves and phase frequency curves in a converter grid-connected system using the grid SISO impedance and power electronic converter SISO impedance obtained by wideband impedance measurement.

[0063] The phase difference acquisition module 200 is used to acquire the frequency value when the amplitude of the SISO impedance characteristic of the power grid and the amplitude of the SISO impedance characteristic of the power electronic converter are equal in the amplitude-frequency curve, and to acquire the phase difference of the same frequency value in the phase-frequency curve.

[0064] The system oscillation judgment module 300 is used to obtain the oscillation judgment result of the converter grid-connected system by combining the phase difference with the pre-constructed wideband oscillation criterion.

[0065] Furthermore, in the converter grid-connected system, the grid SISO impedance and power electronic converter SISO impedance obtained by wideband impedance measurement are specifically: injecting harmonic disturbances into the grid connection point of the converter grid-connected system, obtaining port response voltage and current information, and using the port response voltage and current information to calculate the grid SISO impedance and power electronic converter SISO impedance.

[0066] Furthermore, the system also includes: constructing an equivalent impedance model of the grid-connected system to obtain the equivalent grid voltage, converter impedance characteristics, and grid impedance characteristics; using the equivalent grid voltage, converter impedance characteristics, and grid impedance characteristics to construct a voltage relationship function for the converter-grid-connected system; obtaining the correlation between phase difference and broadband oscillation phenomenon based on the voltage relationship function of the converter-grid-connected system, and constructing a broadband oscillation criterion based on the correlation between phase difference and broadband oscillation phenomenon.

[0067] It should be noted that the modules in the system of Embodiment 2 correspond to the steps in the method of Embodiment 1. The steps in the method of Embodiment 1 have been described in detail in Embodiment 1, and the module content in the system will not be described in detail in this Embodiment 2.

[0068] Example 3

[0069] See Figure 7 This embodiment also provides a computer device, including a system memory 1005 and a processor 1001. The system memory 1005 stores a computer program, and the processor 1001 executes the computer program to implement the steps of any of the methods described above.

[0070] It should be noted that the processor 1001 is used to execute the steps in the above method embodiments according to the instructions in the program code. Alternatively, when the processor 1001 executes the computer program, it implements the functions of each module / unit in the above system / device embodiments.

[0071] Specifically, in this embodiment, the computer program can be divided into one or more modules / units. One or more modules / units are stored in the system memory 1005 and executed by the processor 1001 to complete this application. One or more modules / units can be a series of computer program instruction segments capable of performing specific functions, which describe the execution process of the computer program in the terminal device.

[0072] The terminal device can be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor 1001 and a system memory 1005. Those skilled in the art will understand that this does not constitute a limitation on the terminal device, which may include more or fewer components than shown, or a combination of certain components, or different components. For example, the terminal device may also include an input / output device 1003, a network access device 1002, a bus 1006, etc.

[0073] Processor 1001 can 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. The general-purpose processor can be a microprocessor, or processor 100 can be any conventional processor.

[0074] System memory 1005 can be an internal storage unit of the terminal device, such as a hard drive or RAM. System memory 1005 can also be a storage device 1004 of the terminal device, such as an external hard drive, SmartMedia Card (SMC), Secure Digital (SD) card, or FlashCard. Furthermore, system memory 1005 can include both internal storage units and storage device 1004. System memory 1005 is used to store computer programs and other programs and data required by the terminal device. System memory 1005 can also be used to temporarily store data that has been output or will be output.

[0075] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0076] Example 4

[0077] This embodiment provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of any of the methods described above.

[0078] The computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or any combination thereof. More specific examples of computer-readable storage media (a non-exhaustive list) include: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), registers, hard disks, optical fibers, compact disc read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof, or any other form of computer-readable storage medium in the art.

[0079] An exemplary storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and storage medium can reside within an application-specific integrated circuit (ASIC). In embodiments of the invention, the computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, system, or device.

[0080] Example 5

[0081] This embodiment also provides a computer program product containing instructions that, when executed by a cluster of computer devices, cause the cluster of computer devices to perform the method described in Embodiment 1.

[0082] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for judging grid-connected oscillation of a power electronic converter, characterized in that, The methods include: In a converter grid-connected system, the amplitude-frequency curve and phase-frequency curve are constructed using the grid SISO impedance obtained by wideband impedance measurement and the power electronic converter SISO impedance. In the amplitude-frequency curve, obtain the frequency value when the amplitude of the SISO impedance characteristic of the power grid is equal to the amplitude of the SISO impedance characteristic of the power electronic converter, and obtain the phase difference of the same frequency value in the phase-frequency curve. By combining the phase difference with a pre-constructed broadband oscillation criterion, the oscillation judgment result of the converter grid-connected system is obtained.

2. The method for judging grid-connected oscillation of a power electronic converter according to claim 1, characterized in that, In a converter-connected grid system, the SISO impedance of the power grid and the SISO impedance of the power electronic converter, obtained using broadband impedance measurement, are specifically as follows: Harmonic disturbances are injected into the grid connection point of the converter grid connection system to obtain port response voltage and current information. The grid SISO impedance and power electronic converter SISO impedance are calculated using the port response voltage and current information.

3. The method for judging grid-connected oscillation of a power electronic converter according to claim 1, characterized in that, The method also includes: Construct an equivalent impedance model of the grid-connected system to obtain the equivalent grid voltage, converter impedance characteristics, and grid impedance characteristics; A voltage relationship function for a converter-grid connected system is constructed using the equivalent grid voltage, converter impedance characteristics, and grid impedance characteristics. The correlation between phase difference and wideband oscillation phenomenon is obtained by using the voltage relationship function of the converter grid-connected system, and a wideband oscillation criterion is constructed based on the correlation between phase difference and wideband oscillation phenomenon.

4. The method for judging grid-connected oscillation of a power electronic converter according to claim 1, characterized in that, The pre-constructed broadband oscillation criterion is as follows: When the phase difference is between 0° and 120°, the grid-connected system of the power electronic converter is stable. When the phase difference is between 120° and 180°, there is a risk of oscillation in the grid-connected system of the power electronic converter; When the phase difference is between 180° and 360°, the power electronic converter grid-connected system oscillates.

5. A power electronic converter grid-connected oscillation judgment system, characterized in that, This system is used in the grid-connected oscillation judgment method for a power electronic converter as described in any one of claims 1-4, wherein the system comprises: The curve construction module is used to construct amplitude-frequency and phase-frequency curves in a converter grid-connected system using the grid SISO impedance obtained by wideband impedance measurement and the power electronic converter SISO impedance. The phase difference acquisition module is used to obtain the frequency value when the amplitude of the SISO impedance characteristic of the power grid and the amplitude of the SISO impedance characteristic of the power electronic converter are equal in the amplitude-frequency curve, and to obtain the phase difference of the same frequency value in the phase-frequency curve. The system oscillation judgment module is used to obtain the oscillation judgment result of the converter grid-connected system by combining the phase difference with the pre-constructed wideband oscillation criterion.

6. The power electronic converter grid-connected oscillation judgment system according to claim 5, characterized in that, In a converter-connected grid system, the SISO impedance of the power grid and the SISO impedance of the power electronic converter, obtained using broadband impedance measurement, are specifically as follows: Harmonic disturbances are injected into the grid connection point of the converter grid connection system to obtain port response voltage and current information. The grid SISO impedance and power electronic converter SISO impedance are calculated using the port response voltage and current information.

7. The power electronic converter grid-connected oscillation judgment system according to claim 5, characterized in that, The system also includes: Construct an equivalent impedance model of the grid-connected system to obtain the equivalent grid voltage, converter impedance characteristics, and grid impedance characteristics; A voltage relationship function for a converter-grid connected system is constructed using the equivalent grid voltage, converter impedance characteristics, and grid impedance characteristics. The correlation between phase difference and wideband oscillation phenomenon is obtained by using the voltage relationship function of the converter grid-connected system, and a wideband oscillation criterion is constructed based on the correlation between phase difference and wideband oscillation phenomenon.

8. A computer device comprising a system memory and a processor, wherein the system 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 4.

9. 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 described in any one of claims 1 to 4.

10. A computer program product containing instructions, characterized in that, When the instructions are executed by a cluster of computer devices, the cluster of computer devices causes the cluster of computer devices to perform the method as described in any one of claims 1 to 4.

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