Power system stability analysis method and system based on impedance measurement data

Abstract

The invention provides a power system stability analysis method based on impedance measurement data. The method comprises the following steps: determining that a current analysis working condition is a working condition in which a disturbance voltage source is connected in series or a disturbance current source is connected in parallel in an equivalent circuit diagram corresponding to a converter topological structure diagram; under the current analysis working condition, acquiring a disturbance voltage component and a disturbance current component generated at the converter side so as to obtain converter impedance measurement data carrying amplitudes and phase angles at a plurality of frequency points, and acquiring a disturbance voltage component and a disturbance current component generated at the power grid side so as to obtain the impedance measurement data; obtaining power grid equivalent impedance measurement data carrying amplitudes and phase angles under a plurality of frequency points; and comparing the impedance measurement data of the converter with the equivalent impedance measurement data of the power grid at the same frequency point, and judging the risk of oscillation instability of the power system according to each comparison result. Implementation of the invention aims to reduce complexity of impedance measurement operation, thereby improving analysis accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a method and system for analyzing power system stability based on impedance measurement data. Background Art

[0002] At present, the development of my country's new energy industry is changing with each passing day. Various new energy production stations such as solar energy and wind energy have been put into use on a large scale, which has profoundly changed the traditional power system structure with synchronous generators as the main body, and brought major challenges to the stability of today's power system. In various new energy production stations such as solar energy and wind energy, converters are the most common electrical equipment. In recent years, there have been continuous reports of wide-band oscillations in system voltage under new energy scenarios at home and abroad. Therefore, it is imperative to solve the small signal stability problem of power systems dominated by converters.

[0003] The power system stability analysis method based on converter impedance is one of the more commonly used methods at present. It mainly determines the possible negative damping area of ​​the system based on the converter impedance curve, so as to determine the frequency range where the power system may experience oscillation instability. In theoretical research, the theoretical impedance model of the converter can be established through methods such as harmonic linearization modeling. The relationship between the theoretical curve and the equivalent impedance of the power grid can determine the small signal stability of the power system. However, in actual engineering, due to the confidentiality of control parameters and control structures, the theoretical impedance curve of the converter is generally difficult to obtain, and the impedance of the converter is usually obtained by measurement. However, the impedance measurement data is discrete according to different frequency points. If you want to obtain a continuous value close to the theoretical curve, you need to reduce the interval of the measurement frequency to a very small value, which increases the complexity of the impedance measurement operation.

[0004] Therefore, it is necessary to propose a power system stability analysis method based on impedance measurement data, so as to directly analyze the small signal stability of the system based on discrete converter impedance measurement data. Summary of the invention

[0005] The technical problem to be solved by the embodiments of the present invention is to provide a method and system for analyzing power system stability based on impedance measurement data, aiming to reduce the complexity of impedance measurement operation and thus improve the accuracy of analysis.

[0006] In order to solve the above technical problems, an embodiment of the present invention provides a method for analyzing power system stability based on impedance measurement data, the method comprising the following steps:

[0007] Determine a current analysis condition; wherein the current analysis condition is a condition in which a disturbance voltage source is connected in series or a disturbance current source is connected in parallel in an equivalent circuit diagram corresponding to a converter topology diagram;

[0008] Under the current analysis condition, the disturbance voltage component and the disturbance current component generated on the converter side are obtained to calculate the converter impedance measurement data with amplitude and phase angle at a number of discrete frequency points, and the disturbance voltage component and the disturbance current component generated on the grid side are obtained to calculate the grid equivalent impedance measurement data with amplitude and phase angle at a number of discrete frequency points;

[0009] The converter impedance measurement data at the same frequency point is compared with the grid equivalent impedance measurement data, and the risk of oscillation instability in the power system is determined based on each comparison result.

[0010] The specific steps of comparing the converter impedance measurement data with the grid equivalent impedance measurement data at the same frequency point and judging the risk of oscillation instability of the power system according to each comparison result include:

[0011] Subtract the amplitudes of the converter impedance measurement data and the grid equivalent impedance measurement data at the same frequency point and take the absolute value to obtain the absolute value of the amplitude difference obtained at each frequency point, and further compare them with a predetermined value to select one or more frequency points corresponding to the absolute values ​​of the amplitude differences being less than the predetermined value as voltage intersection frequency points;

[0012] Subtract the phase angles between the converter impedance measurement data and the grid equivalent impedance measurement data at the same voltage intersection frequency point and take the absolute value to obtain the absolute value of the phase angle difference obtained at each voltage intersection frequency point, and further compare them with the predetermined angle value to determine that one or more voltage intersection frequency points corresponding to the absolute value of the phase angle difference is greater than the predetermined angle value as the voltage oscillation instability frequency point;

[0013] It is determined that the power system at each voltage oscillation instability frequency point has the risk of oscillation instability.

[0014] Wherein, the method further comprises:

[0015] The risk of oscillation instability in the power system at each voltage oscillation instability frequency point is eliminated through a predetermined strategy; wherein the predetermined strategy is one or more of adjusting control parameters, adding virtual impedance control and changing the steady-state operating point of the converter.

[0016] Wherein, the method further comprises:

[0017] It is determined that one or more selected frequency points corresponding to when the absolute values ​​of the phase angle differences are all less than or equal to the predetermined angle value are voltage small signal stable frequency points, and it is further determined that the power system at each voltage small signal stable frequency point is small signal stable.

[0018] Wherein, the method further comprises:

[0019] It is determined that one or more frequency points corresponding to when the absolute values ​​of the amplitude differences are greater than or equal to the predetermined value are voltage non-intersecting frequency points, and it is further determined that the power system at each voltage non-intersecting frequency point does not oscillate and is stable.

[0020] Among them, the converter impedance measurement data at each frequency point is obtained by dividing the disturbance voltage component generated on the converter side at the same frequency point by the disturbance current component generated on the converter side; the grid equivalent impedance measurement data at each frequency point is obtained by dividing the disturbance voltage component generated on the grid side at the same frequency point by the disturbance current component generated on the grid side.

[0021] The disturbance voltage component and the disturbance current component generated on the converter side and the grid side are directly obtained through simulated frequency sweep or actual measurement.

[0022] The embodiment of the present invention also provides a power system stability analysis system based on impedance measurement data, including:

[0023] An analysis condition confirmation unit, used to determine a current analysis condition; wherein the current analysis condition is a condition in which a disturbance voltage source is connected in series or a disturbance current source is connected in parallel in an equivalent circuit diagram corresponding to a converter topology diagram;

[0024] An impedance measurement data acquisition unit is used to obtain the disturbance voltage component and the disturbance current component generated on the converter side under the current analysis working condition, so as to calculate the converter impedance measurement data with amplitude and phase angle at a plurality of discrete frequency points, and obtain the disturbance voltage component and the disturbance current component generated on the grid side, so as to calculate the grid equivalent impedance measurement data with amplitude and phase angle at a plurality of discrete frequency points;

[0025] The system stability analysis unit is used to compare the converter impedance measurement data with the grid equivalent impedance measurement data at the same frequency point, and judge the risk of oscillation instability of the power system based on each comparison result.

[0026] Wherein, the system stability analysis unit comprises:

[0027] An amplitude comparison and judgment module is used to subtract the amplitudes between the converter impedance measurement data and the grid equivalent impedance measurement data at the same frequency point and take the absolute value to obtain the absolute value of the amplitude difference obtained at each frequency point, and further compare with a predetermined value to select one or more frequency points corresponding to the absolute values ​​of the amplitude differences being less than the predetermined value as voltage intersection frequency points;

[0028] A phase angle comparison and judgment module is used to subtract the phase angles between the converter impedance measurement data and the grid equivalent impedance measurement data at the same voltage intersection frequency point and take the absolute value to obtain the absolute value of the phase angle difference obtained at each voltage intersection frequency point, and further compare with the predetermined angle value to determine that one or more voltage intersection frequency points corresponding to the absolute value of the phase angle difference is greater than the predetermined angle value as the voltage oscillation instability frequency point;

[0029] The oscillation instability risk judgment module is used to determine the risk of oscillation instability occurring in the power system at each voltage oscillation instability frequency point.

[0030] Wherein, the system stability analysis unit further includes:

[0031] An oscillation instability risk elimination module is used to eliminate the risk of oscillation instability of the power system at each voltage oscillation instability frequency point through a predetermined strategy; wherein the predetermined strategy is one or more of adjusting control parameters, adding virtual impedance control, and changing the steady-state operating point of the converter;

[0032] A small signal stability judgment module is used to determine that one or more selected frequency points corresponding to the absolute values ​​of the phase angle differences are all less than or equal to the predetermined angle value are voltage small signal stable frequency points, and further determine that the power system at each voltage small signal stable frequency point is small signal stable;

[0033] The stable and non-oscillating judgment module is used to determine that one or more frequency points corresponding to the absolute values ​​of the amplitude differences are greater than or equal to the predetermined values ​​are voltage non-intersecting frequency points, and further determine that the power system at each voltage non-intersecting frequency point does not oscillate and is stable.

[0034] Implementing the embodiments of the present invention has the following beneficial effects:

[0035] The present invention directly uses the converter impedance measurement data and the grid equivalent impedance measurement data obtained by simulating frequency sweep or actual measurement to determine the possible voltage oscillation risk of the power system, so as to help subsequent impedance optimization adjustment and other technical means to eliminate the negative damping area of ​​the system impedance, thereby aiming to reduce the complexity of the impedance measurement operation and improve the analysis accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying creative labor, other drawings obtained based on these drawings still belong to the scope of the present invention.

[0037] Figure 1 A flow chart of a method for analyzing power system stability based on impedance measurement data provided by an embodiment of the present invention;

[0038] Figure 2 A converter topology diagram in a power system stability analysis method based on impedance measurement data provided by an embodiment of the present invention;

[0039] Figure 3 for Figure 2 The equivalent circuit diagram of the converter topology structure has a disturbance voltage source in series;

[0040] Figure 4 A flowchart for realizing an application scenario of a method for analyzing power system stability based on impedance measurement data provided by an embodiment of the present invention;

[0041] Figure 5 A schematic structural diagram of a power system stability analysis system based on impedance measurement data provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0042] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings.

[0043] like Figure 1 As shown in the figure, a method for analyzing power system stability based on impedance measurement data is proposed in an embodiment of the present invention, and the method comprises the following steps:

[0044] Step S1, determining the current analysis condition; wherein the current analysis condition is a condition in which a disturbance voltage source is connected in series or a disturbance current source is connected in parallel in an equivalent circuit diagram corresponding to the converter topology diagram;

[0045] The specific process is based on Figure 2 The converter topology diagram is transformed into a corresponding equivalent circuit diagram, and a disturbance voltage source (such as Figure 3 As shown) or in parallel with a disturbance current source to form a new equivalent circuit diagram of the converter topology diagram, this is conducive to setting a number of frequency points through a disturbance voltage source or a disturbance current source, so as to continuously obtain discrete converter impedance measurement data and grid equivalent impedance measurement data at the set number of frequency points.

[0046] Step S2, under the current analysis working condition, obtaining the disturbance voltage component and the disturbance current component generated on the converter side to calculate the converter impedance measurement data with amplitude and phase angle at a number of discrete frequency points, and obtaining the disturbance voltage component and the disturbance current component generated on the grid side to calculate the grid equivalent impedance measurement data with amplitude and phase angle at a number of discrete frequency points;

[0047] The specific process is as follows: first, based on Figure 3 Under the working conditions, the disturbance voltage components and disturbance current components generated on the converter side and the grid side at several frequency points are obtained directly through simulation frequency sweep or actual measurement;

[0048] Secondly, the disturbance voltage component generated on the converter side at the same frequency point is divided by the disturbance current component generated on the converter side to obtain the converter impedance measurement data at each frequency point; and the disturbance voltage component generated on the grid side at the same frequency point is divided by the disturbance current component generated on the grid side to obtain the grid equivalent impedance measurement data at each frequency point; wherein the converter impedance measurement data and the grid equivalent impedance measurement data both carry amplitude and phase angle.

[0049] Step S3: compare the converter impedance measurement data and the grid equivalent impedance measurement data at the same frequency point, and determine the risk of oscillation instability of the power system based on each comparison result.

[0050] The specific process is as follows: first, the amplitudes of the converter impedance measurement data and the grid equivalent impedance measurement data at the same frequency point are subtracted and the absolute values ​​are taken to obtain the absolute values ​​of the amplitude differences obtained at each frequency point, and further compared with a predetermined value (value k) to select one or more frequency points corresponding to when the absolute values ​​of the amplitude differences are all less than the predetermined value as voltage intersection frequency points; conversely, one or more frequency points corresponding to when the absolute values ​​of the amplitude differences are all greater than or equal to the predetermined value are determined as voltage non-intersection frequency points;

[0051] Secondly, it is directly determined that the power system at each voltage non-intersecting frequency point does not oscillate and is stable; or, the phase angles between the converter impedance measurement data and the grid equivalent impedance measurement data at the same voltage intersection frequency point are subtracted and the absolute value is taken to obtain the absolute value of the phase angle difference obtained at each voltage intersection frequency point, and further compared with a predetermined angle value (such as 180 degrees) to determine that one or more voltage intersection frequency points corresponding to the absolute value of the phase angle difference is greater than the predetermined angle value as the voltage oscillation instability frequency point;

[0052] Finally, it is determined that the power system at each voltage oscillation instability frequency point is at risk of oscillation instability; conversely, one or more selected frequency points corresponding to the absolute values ​​of the phase angle differences that are less than or equal to the predetermined angle values ​​are determined to be voltage small signal stable frequency points, and it is further determined that the power system at each voltage small signal stable frequency point is small signal stable.

[0053] In an embodiment of the present invention, the method further includes: eliminating the risk of oscillation instability in the power system at each voltage oscillation instability frequency point through a predetermined strategy, thereby eliminating the small signal unstable area of ​​the power system to ensure the safe and stable operation of the power system; wherein the predetermined strategy is one or more of adjusting control parameters, adding virtual impedance control and changing the steady-state operating point of the converter.

[0054] like Figure 4 As shown, the application scenario of a power system stability analysis method based on impedance measurement data provided in an embodiment of the present invention is further described as follows:

[0055] Step 1: Connect a disturbance voltage source in series in the equivalent main circuit diagram of the converter, and calculate the port impedance measurement value of the converter through the disturbance voltage component and the disturbance current component generated on the converter side, that is, the converter impedance measurement data at several discrete frequency points, including amplitude and phase angle.

[0056] Step 2: According to the disturbance voltage and disturbance current generated on the grid side, the grid equivalent impedance measurement data is calculated through the disturbance voltage component and the disturbance current component generated on the grid side, that is, the grid equivalent impedance measurement data at a number of discrete frequency points, including amplitude and phase angle.

[0057] Step 3: According to the absolute value of the amplitude difference between the converter impedance measurement data and the grid equivalent impedance measurement data at the corresponding frequency point, determine the possible impedance amplitude intersection frequency range (i.e., composed of multiple voltage intersection frequency points). The determination method is that if the absolute value of the amplitude difference between the converter impedance measurement data and the grid equivalent impedance measurement data at the corresponding frequency point is less than a certain set value k, the possible impedance amplitude intersection frequency range is determined. The larger the k value is set, the larger the possible impedance amplitude intersection frequency range is, and vice versa, the smaller the possible impedance amplitude intersection frequency range is.

[0058] Step 4: Calculate the absolute value of the phase angle difference between the converter impedance measurement data at each corresponding frequency point within the impedance amplitude intersection frequency range and the grid equivalent impedance measurement data at the corresponding frequency point. If it is found that the absolute value of the phase angle difference between the converter impedance and the grid equivalent impedance within the impedance amplitude intersection frequency range is greater than the predetermined angle value of 180, it indicates that the power system is at risk of oscillation instability within the impedance amplitude intersection frequency range; otherwise, the power system is small signal stable within the impedance amplitude intersection frequency range.

[0059] Step 5: If the system has the risk of oscillation instability, the small signal instability area of ​​the power system is eliminated by adjusting the control parameters, adding virtual impedance control, changing the steady-state operation point of the converter, etc., to ensure the safe and stable operation of the system. If the system does not have the risk of oscillation instability, wait for the next impedance measurement instruction to obtain new impedance measurement data and repeat the above steps.

[0060] like Figure 5 As shown, a power system stability analysis system based on impedance measurement data is provided in an embodiment of the present invention, comprising:

[0061] The analysis condition confirmation unit 110 is used to determine the current analysis condition; wherein the current analysis condition is a condition in which a disturbance voltage source is connected in series or a disturbance current source is connected in parallel in an equivalent circuit diagram corresponding to the converter topology diagram;

[0062] The impedance measurement data acquisition unit 120 is used to obtain the disturbance voltage component and the disturbance current component generated on the converter side under the current analysis working condition, so as to calculate the converter impedance measurement data with amplitude and phase angle at a plurality of discrete frequency points, and obtain the disturbance voltage component and the disturbance current component generated on the grid side, so as to calculate the grid equivalent impedance measurement data with amplitude and phase angle at a plurality of discrete frequency points;

[0063] The system stability analysis unit 130 is used to compare the converter impedance measurement data with the grid equivalent impedance measurement data at the same frequency point, and determine the risk of oscillation instability of the power system according to each comparison result.

[0064] Wherein, the system stability analysis unit 130 includes:

[0065] An amplitude comparison and judgment module is used to subtract the amplitudes between the converter impedance measurement data and the grid equivalent impedance measurement data at the same frequency point and take the absolute value to obtain the absolute value of the amplitude difference obtained at each frequency point, and further compare with a predetermined value to select one or more frequency points corresponding to the absolute values ​​of the amplitude differences being less than the predetermined value as voltage intersection frequency points;

[0066] A phase angle comparison and judgment module is used to subtract the phase angles between the converter impedance measurement data and the grid equivalent impedance measurement data at the same voltage intersection frequency point and take the absolute value to obtain the absolute value of the phase angle difference obtained at each voltage intersection frequency point, and further compare with the predetermined angle value to determine that one or more voltage intersection frequency points corresponding to the absolute value of the phase angle difference is greater than the predetermined angle value as the voltage oscillation instability frequency point;

[0067] The oscillation instability risk judgment module is used to determine the risk of oscillation instability occurring in the power system at each voltage oscillation instability frequency point.

[0068] Wherein, the system stability analysis unit 130 further includes:

[0069] An oscillation instability risk elimination module is used to eliminate the risk of oscillation instability of the power system at each voltage oscillation instability frequency point through a predetermined strategy; wherein the predetermined strategy is one or more of adjusting control parameters, adding virtual impedance control, and changing the steady-state operating point of the converter;

[0070] A small signal stability judgment module is used to determine that one or more selected frequency points corresponding to the absolute values ​​of the phase angle differences are all less than or equal to the predetermined angle value are voltage small signal stable frequency points, and further determine that the power system at each voltage small signal stable frequency point is small signal stable;

[0071] The stable and non-oscillating judgment module is used to determine that one or more frequency points corresponding to the absolute values ​​of the amplitude differences are greater than or equal to the predetermined values ​​are voltage non-intersecting frequency points, and further determine that the power system at each voltage non-intersecting frequency point does not oscillate and is stable.

[0072] Implementing the embodiments of the present invention has the following beneficial effects:

[0073] The present invention directly uses the converter impedance measurement data and the grid equivalent impedance measurement data obtained by simulating frequency sweep or actual measurement to determine the possible voltage oscillation risk of the power system, so as to help subsequent impedance optimization adjustment and other technical means to eliminate the negative damping area of ​​the system impedance, thereby aiming to reduce the complexity of the impedance measurement operation and improve the analysis accuracy.

[0074] It is worth noting that in the above system embodiment, the various system modules included are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be achieved; in addition, the specific names of the various functional modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of the present invention.

[0075] A person skilled in the art can understand that all or part of the steps in the above-mentioned embodiment method can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, such as ROM / RAM, disk, CD-ROM, etc.

[0076] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for analyzing power system stability based on impedance measurement data, characterized in that: The method comprises the following steps: Determine a current analysis condition; wherein the current analysis condition is a condition in which a disturbance voltage source is connected in series or a disturbance current source is connected in parallel in an equivalent circuit diagram corresponding to a converter topology diagram; Under the current analysis condition, the disturbance voltage component and the disturbance current component generated on the converter side are obtained to calculate the converter impedance measurement data with amplitude and phase angle at a number of discrete frequency points, and the disturbance voltage component and the disturbance current component generated on the grid side are obtained to calculate the grid equivalent impedance measurement data with amplitude and phase angle at a number of discrete frequency points; The converter impedance measurement data at the same frequency point is compared with the grid equivalent impedance measurement data, and the risk of oscillation instability in the power system is determined based on each comparison result.

2. The power system stability analysis method based on impedance measurement data according to claim 1, characterized in that: The specific steps of comparing the converter impedance measurement data at the same frequency point with the grid equivalent impedance measurement data and judging the risk of oscillation instability of the power system according to each comparison result include: Subtract the amplitudes of the converter impedance measurement data and the grid equivalent impedance measurement data at the same frequency point and take the absolute value to obtain the absolute value of the amplitude difference obtained at each frequency point, and further compare them with a predetermined value to select one or more frequency points corresponding to the absolute values ​​of the amplitude differences being less than the predetermined value as voltage intersection frequency points; Subtract the phase angles between the converter impedance measurement data and the grid equivalent impedance measurement data at the same voltage intersection frequency point and take the absolute value to obtain the absolute value of the phase angle difference obtained at each voltage intersection frequency point, and further compare them with the predetermined angle value to determine that one or more voltage intersection frequency points corresponding to the absolute value of the phase angle difference is greater than the predetermined angle value as the voltage oscillation instability frequency point; It is determined that the power system at each voltage oscillation instability frequency point has the risk of oscillation instability.

3. The power system stability analysis method based on impedance measurement data according to claim 2, characterized in that: The method further comprises: The risk of oscillation instability in the power system at each voltage oscillation instability frequency point is eliminated through a predetermined strategy; wherein the predetermined strategy is one or more of adjusting control parameters, adding virtual impedance control and changing the steady-state operating point of the converter.

4. The power system stability analysis method based on impedance measurement data according to claim 3, characterized in that: The method further comprises: It is determined that one or more selected frequency points corresponding to when the absolute values ​​of the phase angle differences are all less than or equal to the predetermined angle value are voltage small signal stable frequency points, and it is further determined that the power system at each voltage small signal stable frequency point is small signal stable.

5. The power system stability analysis method based on impedance measurement data according to claim 3, characterized in that: The method further comprises: It is determined that one or more frequency points corresponding to when the absolute values ​​of the amplitude differences are greater than or equal to the predetermined value are voltage non-intersecting frequency points, and it is further determined that the power system at each voltage non-intersecting frequency point does not oscillate and is stable.

6. The power system stability analysis method based on impedance measurement data according to claim 1, characterized in that: The converter impedance measurement data at each frequency point is obtained by dividing the disturbance voltage component generated on the converter side at the same frequency point by the disturbance current component generated on the converter side; the grid equivalent impedance measurement data at each frequency point is obtained by dividing the disturbance voltage component generated on the grid side at the same frequency point by the disturbance current component generated on the grid side.

7. The power system stability analysis method based on impedance measurement data according to claim 6, characterized in that: The disturbance voltage component and the disturbance current component generated on the converter side and the grid side are directly obtained through simulated frequency sweep or actual measurement.

8. A power system stability analysis system based on impedance measurement data, characterized in that: include; An analysis condition confirmation unit, used to determine a current analysis condition; wherein the current analysis condition is a condition in which a disturbance voltage source is connected in series or a disturbance current source is connected in parallel in an equivalent circuit diagram corresponding to a converter topology diagram; An impedance measurement data acquisition unit is used to obtain the disturbance voltage component and the disturbance current component generated on the converter side under the current analysis working condition, so as to calculate the converter impedance measurement data with amplitude and phase angle at a plurality of discrete frequency points, and obtain the disturbance voltage component and the disturbance current component generated on the grid side, so as to calculate the grid equivalent impedance measurement data with amplitude and phase angle at a plurality of discrete frequency points; The system stability analysis unit is used to compare the converter impedance measurement data with the grid equivalent impedance measurement data at the same frequency point, and judge the risk of oscillation instability of the power system based on each comparison result.

9. The power system stability analysis system based on impedance measurement data according to claim 8, characterized in that: The system stability analysis unit comprises: An amplitude comparison and judgment module is used to subtract the amplitudes between the converter impedance measurement data and the grid equivalent impedance measurement data at the same frequency point and take the absolute value to obtain the absolute value of the amplitude difference obtained at each frequency point, and further compare with a predetermined value to select one or more frequency points corresponding to the absolute values ​​of the amplitude differences being less than the predetermined value as voltage intersection frequency points; A phase angle comparison and judgment module is used to subtract the phase angles between the converter impedance measurement data and the grid equivalent impedance measurement data at the same voltage intersection frequency point and take the absolute value to obtain the absolute value of the phase angle difference obtained at each voltage intersection frequency point, and further compare with the predetermined angle value to determine that one or more voltage intersection frequency points corresponding to the absolute value of the phase angle difference is greater than the predetermined angle value as the voltage oscillation instability frequency point; The oscillation instability risk judgment module is used to determine the risk of oscillation instability occurring in the power system at each voltage oscillation instability frequency point.

10. The power system stability analysis system based on impedance measurement data according to claim 9, characterized in that: The system stability analysis unit also includes: An oscillation instability risk elimination module is used to eliminate the risk of oscillation instability of the power system at each voltage oscillation instability frequency point through a predetermined strategy; wherein the predetermined strategy is one or more of adjusting control parameters, adding virtual impedance control, and changing the steady-state operating point of the converter; A small signal stability judgment module is used to determine that one or more selected frequency points corresponding to the absolute values ​​of the phase angle differences are all less than or equal to the predetermined angle value are voltage small signal stable frequency points, and further determine that the power system at each voltage small signal stable frequency point is small signal stable; The stable and non-oscillating judgment module is used to determine that one or more frequency points corresponding to the absolute values ​​of the amplitude differences are greater than or equal to the predetermined values ​​are voltage non-intersecting frequency points, and further determine that the power system at each voltage non-intersecting frequency point does not oscillate and is stable.

Images