A power system stability analysis method and system based on impedance measurement data

Abstract

The application provides a power system stability analysis method based on impedance measurement data, comprising determining that the current analysis condition is a condition corresponding to an equivalent circuit diagram based on a converter topology structure diagram, wherein a disturbance voltage source is in series or a disturbance current source is in parallel; under the current analysis condition, disturbance voltage components and disturbance current components generated on the converter side are obtained to obtain converter impedance measurement data carrying amplitudes and phase angles at several frequency points, and disturbance voltage components and disturbance current components generated on the power grid side are obtained to obtain power grid equivalent impedance measurement data carrying amplitudes and phase angles at several frequency points; the converter impedance measurement data and the power grid equivalent impedance measurement data at the same frequency point are compared, and according to each comparison result, the risk of oscillation instability of the power system is judged. The application is implemented to reduce the complexity of impedance measurement operation, thereby improving the analysis accuracy.

Description

Technical Field

[0001] This invention relates to the field of power system technology, and in particular to a method and system for power system stability analysis based on impedance measurement data. Background Technology

[0002] Currently, my country's new energy industry is developing rapidly, with large-scale deployment of various new energy power plants, such as solar and wind power plants, profoundly changing the traditional power system structure dominated by synchronous generators and posing significant challenges to the stability of today's power systems. In various new energy power plants, such as solar and wind power plants, converters are the most common electrical equipment. In recent years, there have been numerous reports both domestically and internationally of wide-frequency oscillations in system voltage under new energy scenarios. Therefore, solving the small-signal stability problem of power systems dominated by converters is imperative.

[0003] Power system stability analysis based on converter impedance is a commonly used method. It primarily uses the converter's impedance curve to determine the potential negative damping region of the system, thereby identifying the frequency range within which the power system may experience oscillations and instability. In theoretical research, methods such as harmonic linearization modeling can establish a theoretical impedance model of the converter. The relationship between this theoretical curve and the equivalent impedance of the power grid can be used to determine the small-signal stability of the power system. However, in practical engineering, due to the confidentiality of control parameters and control structures, the theoretical impedance curve of the converter is generally difficult to obtain. Measurement methods are typically used to obtain the converter's impedance. However, impedance measurement data is discrete at different frequency points. To obtain continuous values ​​close to the theoretical curve, the interval between measurement frequencies needs to be reduced to a very small value, thus increasing the complexity of impedance measurement operations.

[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 power system stability analysis based on impedance measurement data, which aims to reduce the complexity of impedance measurement operation and thus improve the accuracy of analysis.

[0006] To address the aforementioned technical problems, embodiments of the present invention provide a power system stability analysis method based on impedance measurement data, the method comprising the following steps:

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

[0008] Under the current analysis conditions, the disturbance voltage component and disturbance current component generated on the converter side are acquired to calculate the converter impedance measurement data carrying amplitude and phase angle at several discrete frequency points. The disturbance voltage component and disturbance current component generated on the grid side are acquired to calculate the grid equivalent impedance measurement data carrying amplitude and phase angle at several 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 power system oscillation instability is judged based on the comparison results.

[0010] The specific steps for comparing converter impedance measurement data with grid equivalent impedance measurement data at the same frequency point, and determining the risk of power system oscillation instability based on each comparison result, include:

[0011] 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 at each frequency point. These are then compared with predetermined values ​​to select one or more frequency points corresponding to the voltage intersection frequency points when the absolute values ​​of the amplitude differences are all less than the predetermined values.

[0012] 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 at each voltage intersection frequency point. This is then compared with a predetermined angle value to determine one or more voltage intersection frequency points corresponding to when the absolute value of the phase angle difference is greater than the predetermined angle value as voltage oscillation instability frequency points.

[0013] The risk of power system oscillation instability at each voltage oscillation instability frequency point was determined.

[0014] The method further includes:

[0015] By employing predetermined strategies, the risk of power system oscillation instability at each voltage oscillation instability frequency point is eliminated; wherein, the predetermined strategies are one or more of the following: adjusting control parameters, increasing virtual impedance control, and changing the steady-state operating point of the converter.

[0016] The method further includes:

[0017] One or more selected frequency points corresponding to when the absolute value of the phase angle difference is less than or equal to the predetermined angle value are determined as voltage small-signal stable frequency points, and it is further determined that the power system under each voltage small-signal stable frequency point is small-signal stable.

[0018] The method further includes:

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

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

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

[0022] This invention also provides a power system stability analysis system based on impedance measurement data, comprising:

[0023] The analysis condition confirmation unit 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 the equivalent circuit diagram corresponding to the converter topology diagram.

[0024] The impedance measurement data acquisition unit is used to acquire the disturbance voltage component and disturbance current component generated on the converter side under the current analysis condition, so as to calculate the converter impedance measurement data carrying amplitude and phase angle at a discrete number of frequency points, and to acquire the disturbance voltage component and disturbance current component generated on the grid side, so as to calculate the grid equivalent impedance measurement data carrying amplitude and phase angle at a discrete number of 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 to determine the risk of power system oscillation and instability based on each comparison result.

[0026] The system stability analysis unit includes:

[0027] The 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 at each frequency point. It is further compared with a predetermined value to select one or more frequency points corresponding to the voltage intersection frequency points when the absolute value of the amplitude difference is less than the predetermined value.

[0028] The phase angle comparison and judgment module is used to subtract the phase angle 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 at each voltage intersection frequency point. It is further compared with a predetermined angle value to determine one or more voltage intersection frequency points corresponding to when the absolute value of the phase angle difference is greater than the predetermined angle value as voltage oscillation instability frequency points.

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

[0030] The system stability analysis unit further includes:

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

[0032] The small-signal stability judgment module is used to determine one or more selected frequency points corresponding to when the absolute value of the phase angle difference is less than or equal to the predetermined angle value as voltage small-signal stable frequency points, and further determine that the power system under each voltage small-signal stable frequency point is small-signal stable.

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

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

[0035] This invention directly uses converter impedance measurement data and power grid equivalent impedance measurement data obtained through simulated frequency sweep or actual measurement to determine the potential voltage oscillation risk in the power system. This helps subsequent impedance optimization and adjustment techniques to eliminate the negative damping region of the system impedance, thereby reducing the complexity of impedance measurement operations and improving the accuracy of analysis. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0037] Figure 1 A flowchart of a power system stability analysis method based on impedance measurement data provided in an embodiment of the present invention;

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

[0039] Figure 3 for Figure 2 The equivalent circuit diagram of the converter topology includes a disturbance voltage source connected in series.

[0040] Figure 4 A flowchart illustrating the implementation of an application scenario for a power system stability analysis method based on impedance measurement data, provided by an embodiment of the present invention.

[0041] Figure 5 This is a schematic diagram of a power system stability analysis system based on impedance measurement data, provided as an embodiment of the present invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the present invention clearer, 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 power system stability analysis method based on impedance measurement data is proposed in an embodiment of the present invention. The method includes the following steps:

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

[0045] The specific process is as follows, based on Figure 2 The converter topology diagram is transformed into the corresponding equivalent circuit diagram, and a disturbance voltage source (such as...) is connected in series in this equivalent circuit diagram. Figure 3 (As shown) or a disturbance current source is connected in parallel to form a new equivalent circuit diagram of the converter topology. This is beneficial to set several frequency points by using 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 several frequency points.

[0046] Step S2: Under the current analysis condition, acquire the disturbance voltage component and disturbance current component generated on the converter side to calculate the converter impedance measurement data carrying amplitude and phase angle at several discrete frequency points, and acquire the disturbance voltage component and disturbance current component generated on the grid side to calculate the grid equivalent impedance measurement data carrying amplitude and phase angle at several discrete frequency points.

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

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

[0049] Step S3: Compare the converter impedance measurement data with the grid equivalent impedance measurement data at the same frequency point, and judge the risk of power system oscillation instability 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 at each frequency point. Then, these are compared with a predetermined value (value k) to select one or more frequency points corresponding to the absolute values ​​of the amplitude differences that are all less than the predetermined value as voltage intersection frequency points; conversely, one or more frequency points corresponding to the absolute values ​​of the amplitude differences that are all greater than or equal to the predetermined value are determined as voltage non-intersection frequency points.

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

[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 when the absolute value of the phase angle difference is less than or equal to the predetermined angle value are determined as 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 this embodiment of the invention, the method further includes: eliminating the risk of power system oscillation instability at each voltage oscillation instability frequency point through a predetermined strategy, thereby eliminating the small-signal instability region 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, increasing virtual impedance control, and changing the steady-state operating point of the converter.

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

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

[0056] Step 2: Based on the disturbance voltage and disturbance current generated on the grid side, calculate the grid equivalent impedance measurement data through the disturbance voltage component and disturbance current component generated on the grid side. That is, the grid equivalent impedance measurement data at discrete frequency points, including amplitude and phase angle.

[0057] Step 3: Based on the absolute value of the amplitude difference between the converter impedance measurement data and the equivalent grid 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 as follows: if the absolute value of the amplitude difference between the converter impedance measurement data and the equivalent grid impedance measurement data at the corresponding frequency point is less than a certain set value k, then the possible impedance amplitude intersection frequency range is determined. The larger the value of k, the larger the possible impedance amplitude intersection frequency range; conversely, the smaller the value of k, the smaller the possible impedance amplitude intersection frequency range.

[0058] Step 4: Calculate the absolute value of the phase angle difference between the converter impedance measurement data and the grid equivalent impedance measurement data at each corresponding frequency point within the impedance amplitude intersection frequency range. If the absolute value of the phase angle difference between the converter impedance and the grid equivalent impedance is found to be greater than the predetermined angle value of 180° within the impedance amplitude intersection frequency range, it indicates that the power system is at risk of oscillation and 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 is at risk of oscillation and instability, the small-signal instability region of the power system can be eliminated by adjusting control parameters, adding virtual impedance control, and changing the steady-state operating point of the converter, so as to ensure the safe and stable operation of the system. If the system is not at risk of oscillation and instability, wait for the next impedance measurement command to obtain new impedance measurement data, and repeat the above steps.

[0060] like Figure 5 As shown in the figure, 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 the equivalent circuit diagram corresponding to the converter topology diagram.

[0062] Impedance measurement data acquisition unit 120 is used to acquire the disturbance voltage component and disturbance current component generated on the converter side under the current analysis condition, so as to calculate the converter impedance measurement data carrying amplitude and phase angle at discrete frequency points, and to acquire the disturbance voltage component and disturbance current component generated on the grid side, so as to calculate the grid equivalent impedance measurement data carrying amplitude and phase angle at 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 to determine the risk of power system oscillation and instability based on each comparison result.

[0064] The system stability analysis unit 130 includes:

[0065] The 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 at each frequency point. It is further compared with a predetermined value to select one or more frequency points corresponding to the voltage intersection frequency points when the absolute value of the amplitude difference is less than the predetermined value.

[0066] The phase angle comparison and judgment module is used to subtract the phase angle 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 at each voltage intersection frequency point. It is further compared with a predetermined angle value to determine one or more voltage intersection frequency points corresponding to when the absolute value of the phase angle difference is greater than the predetermined angle value as voltage oscillation instability frequency points.

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

[0068] The system stability analysis unit 130 further includes:

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

[0070] The small-signal stability judgment module is used to determine one or more selected frequency points corresponding to when the absolute value of the phase angle difference is less than or equal to the predetermined angle value as voltage small-signal stable frequency points, and further determine that the power system under each voltage small-signal stable frequency point is small-signal stable.

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

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

[0073] This invention directly uses converter impedance measurement data and power grid equivalent impedance measurement data obtained through simulated frequency sweep or actual measurement to determine the potential voltage oscillation risk in the power system. This helps subsequent impedance optimization and adjustment techniques to eliminate the negative damping region of the system impedance, thereby reducing the complexity of impedance measurement operations and improving the accuracy of analysis.

[0074] It is worth noting that the various system modules included in the above system embodiments 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 each functional module are only for easy differentiation and are not used to limit the scope of protection of the present invention.

[0075] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, such as ROM / RAM, disk, optical disk, etc.

[0076] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A power system stability analysis method based on impedance measurement data, characterized in that, The method includes the following steps: Determine the current analysis condition; wherein, the current analysis condition is the condition in which a disturbance voltage source is connected in series or a disturbance current source is connected in parallel in the equivalent circuit diagram corresponding to the converter topology diagram; Under the current analysis conditions, the disturbance voltage component and disturbance current component generated on the converter side are acquired to calculate the converter impedance measurement data carrying amplitude and phase angle at several discrete frequency points. The disturbance voltage component and disturbance current component generated on the grid side are acquired to calculate the grid equivalent impedance measurement data carrying amplitude and phase angle at several discrete frequency points. The converter impedance measurement data and the grid equivalent impedance measurement data at the same frequency point are compared, and the risk of power system oscillation and instability is judged based on the comparison results. The converter impedance measurement data at each frequency point is obtained by dividing the disturbance voltage component generated on the converter side by the disturbance current component generated on the converter side at the same frequency point. The grid equivalent impedance measurement data at each frequency point is obtained by dividing the disturbance voltage component generated on the grid side by the disturbance current component generated on the grid side at the same frequency point. The specific steps for comparing converter impedance measurement data with grid equivalent impedance measurement data at the same frequency point, and determining the risk of power system oscillation instability based on each comparison result, include: 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 at each frequency point. These are then compared with predetermined values ​​to select one or more frequency points corresponding to the voltage intersection frequency points when the absolute values ​​of the amplitude differences are all less than the predetermined values. 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 at each voltage intersection frequency point. This is then compared with a predetermined angle value to determine one or more voltage intersection frequency points corresponding to when the absolute value of the phase angle difference is greater than the predetermined angle value as voltage oscillation instability frequency points. The risk of power system oscillation instability at each voltage oscillation instability frequency point was determined.

2. The power system stability analysis method based on impedance measurement data as described in claim 1, characterized in that, The method further includes: By employing predetermined strategies, the risk of power system oscillation instability at each voltage oscillation instability frequency point is eliminated; wherein, the predetermined strategies are one or more of the following: adjusting control parameters, increasing virtual impedance control, and changing the steady-state operating point of the converter.

3. The power system stability analysis method based on impedance measurement data as described in claim 2, characterized in that, The method further includes: One or more selected frequency points corresponding to when the absolute value of the phase angle difference is less than or equal to the predetermined angle value are determined as voltage small-signal stable frequency points, and it is further determined that the power system under each voltage small-signal stable frequency point is small-signal stable.

4. The power system stability analysis method based on impedance measurement data as described in claim 2, characterized in that, The method further includes: One or more frequency points corresponding to the absolute values ​​of the amplitude differences are all greater than or equal to the predetermined values ​​are identified as voltage non-intersection frequency points, and it is further determined that the power system does not oscillate and is stable at each voltage non-intersection frequency point.

5. The power system stability analysis method based on impedance measurement data as described in claim 1, characterized in that, The disturbance voltage and disturbance current components generated on the converter side and the grid side are obtained directly through simulated frequency sweep or actual measurement.

6. A power system stability analysis system based on impedance measurement data, characterized in that, include: The analysis condition confirmation unit 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 the equivalent circuit diagram corresponding to the converter topology diagram. The impedance measurement data acquisition unit is used to acquire the disturbance voltage component and disturbance current component generated on the converter side under the current analysis condition, so as to calculate the converter impedance measurement data carrying amplitude and phase angle at a discrete number of frequency points, and to acquire the disturbance voltage component and disturbance current component generated on the grid side, so as to calculate the grid equivalent impedance measurement data carrying amplitude and phase angle at a discrete number of frequency points. The system stability analysis unit compares the converter impedance measurement data with the grid equivalent impedance measurement data at the same frequency point, and judges the risk of power system oscillation and instability based on each comparison result. The converter impedance measurement data at each frequency point is obtained by dividing the disturbance voltage component generated on the converter side by the disturbance current component generated on the converter side at the same frequency point. The grid equivalent impedance measurement data at each frequency point is obtained by dividing the disturbance voltage component generated on the grid side by the disturbance current component generated on the grid side at the same frequency point. The system stability analysis unit includes: The 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 at each frequency point. It is further compared with a predetermined value to select one or more frequency points corresponding to the voltage intersection frequency points when the absolute value of the amplitude difference is less than the predetermined value. The phase angle comparison and judgment module is used to subtract the phase angle 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 at each voltage intersection frequency point. It is further compared with a predetermined angle value to determine one or more voltage intersection frequency points corresponding to when the absolute value of the phase angle difference is greater than the predetermined angle value as voltage oscillation instability frequency points. The oscillation instability risk assessment module is used to determine the risk of power system oscillation instability at each voltage oscillation instability frequency point.

7. The power system stability analysis system based on impedance measurement data as described in claim 6, characterized in that, The system stability analysis unit also includes: The oscillation instability risk elimination module is used to eliminate the risk of power system oscillation instability at each voltage oscillation instability frequency point through a predetermined strategy; wherein the predetermined strategy is one or more of the following: adjusting control parameters, increasing virtual impedance control, and changing the steady-state operating point of the converter. The small-signal stability judgment module is used to determine one or more selected frequency points corresponding to when the absolute value of the phase angle difference is less than or equal to the predetermined angle value as voltage small-signal stable frequency points, and further determine that the power system under each voltage small-signal stable frequency point is small-signal stable. The stable and non-oscillating judgment module is used to determine one or more frequency points corresponding to when the absolute value of the amplitude difference is greater than or equal to the predetermined value as voltage non-intersection frequency points, and further determine that the power system does not oscillate and is stable at each voltage non-intersection frequency point.

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