A method, system and medium for identifying and suppressing vibration of a network-constructed multi-machine key converter

Abstract

The present application relates to the technical field of power system stability control, and particularly relates to a network-constructed multi-machine key converter identification and vibration suppression method, system and medium, the method comprising: obtaining a capacity matrix and a network side power frequency admittance matrix of a network-constructed converter multi-machine system; constructing an extended impedance matrix according to the capacity matrix and the network side power frequency admittance matrix; determining a first modal state or a second modal state according to the minimum eigenvalue distribution of the extended impedance matrix; determining a first participation factor in the first modal state, or determining a comprehensive participation factor according to the participation factors of a plurality of dominant modes in the second modal state, and determining a key network-constructed converter according to the first participation factor or the comprehensive participation factor; and only implementing low-frequency oscillation suppression control on the key network-constructed converter. Through the present application, the problem that it is difficult to accurately identify the key converter which plays a dominant role in low-frequency stability in the network-constructed converter multi-machine system and accordingly realize targeted low-frequency oscillation suppression is effectively solved.

Description

Technical Field

[0001] This invention relates to the field of power system stability control technology, and in particular to a method, system and medium for identifying and suppressing vibration of key multi-machine converters in a grid-connected system. Background Technology

[0002] With the increasing electronic sophistication of new energy power systems, grid-connected converters are gradually being applied to power systems due to their ability to actively establish voltage and provide frequency support. However, when multiple grid-connected converters are connected in parallel or mixed with grid-connected converters, their dynamic coupling can easily lead to low-frequency oscillations. In existing technologies, CN118983792A determines the oscillation risk and equipment correlation in multi-converter systems through impedance equivalence, state-space modeling, eigenvalue analysis, and participation factor analysis. However, it relies on a relatively complete equipment control model and does not establish an adaptive key converter identification and selective control mechanism for multiple similar dominant modes. CN119864825B uses capacity matrices, network admittance matrices, and eigenvalues ​​to evaluate the low-frequency stability of grid-connected multi-machine systems, but it does not further identify the key grid-connected converters that play a dominant role in low-frequency stability and implement targeted control accordingly. Therefore, existing technologies still face the problem of accurately identifying the key grid-connected converters that truly affect the low-frequency stability of the system under complex dominant mode conditions and thus failing to achieve targeted low-frequency oscillation suppression.

[0003] The information disclosed in this background section is intended only to enhance the understanding of the general background of this disclosure and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0004] This invention provides a method, system, and medium for identifying and suppressing vibration in a grid-type multi-machine key converter, which can effectively solve the problems in the background art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for identifying and suppressing vibration in a grid-type multi-machine key converter, characterized in that the method includes: Obtain the capacity matrix and network-side power frequency admittance matrix of a multi-machine grid-type converter system; Construct an extended impedance matrix based on the capacity matrix and the network-side power frequency admittance matrix; The first mode state or the second mode state is determined based on the minimum eigenvalue distribution of the extended impedance matrix. The first mode state corresponds to a single dominant mode, and the second mode state corresponds to multiple dominant modes. In the first mode state, the first participation factor of each grid-type converter is determined, or in the second mode state, the comprehensive participation factor of each grid-type converter is determined according to the participation factors corresponding to multiple dominant modes, and the key grid-type converter is determined according to the first participation factor or the comprehensive participation factor. Low-frequency oscillation suppression control is implemented only for the key grid-type converter.

[0006] Furthermore, the network-side power frequency admittance matrix is ​​the power frequency admittance matrix obtained after eliminating the internal passive nodes in the multi-machine system of the grid-type converter, and the network-side hybrid admittance-impedance transfer relationship is established based on the matrix sub-blocks in the network-side power frequency admittance matrix corresponding to the grid-type converter access node and the grid-type converter access node.

[0007] Furthermore, the construction of the extended impedance matrix includes: The equivalent network admittance matrix corresponding to the access node of the grid-type converter is determined based on the matrix sub-blocks of the network-side power frequency admittance matrix. Construct the capacity matrix in diagonal form based on the capacity of each of the grid-type converters; The extended impedance matrix is ​​obtained by performing a capacity-weighted summation on the inverse of the equivalent network admittance matrix using the capacity matrix: .

[0008] Further, determining the first modal state or the second modal state includes: Determine the relative interval between the smallest and second smallest eigenvalues ​​of the extended impedance matrix; If the relative interval is greater than a preset threshold, the grid-type converter multi-machine system is determined to be in the first mode state; When the relative interval is less than or equal to the preset threshold, the grid-type converter multi-machine system is determined to be in the second mode state.

[0009] Furthermore, in the first modal state, the first... The first participation factor of the grid-type converter is determined according to the following formula: ; in, The smallest eigenvalue of the extended impedance matrix is... and The left and right eigenvectors corresponding to the minimum eigenvalue are respectively the first and second eigenvectors. One element, The first of the extended impedance matrix One diagonal element.

[0010] Furthermore, in the second modal state, the determination of the integrated participation factor includes: Multiple feature values ​​whose relative interval with the minimum feature value is not greater than a preset threshold are determined as the dominant feature values ​​corresponding to the multiple dominant modes; The modal weights of each dominant mode are determined based on the ratio between the minimum eigenvalue and each of the dominant eigenvalues. According to the dominant modes described above, the first The participation factors and corresponding modal weights of the grid-type converter are determined according to: ; Determine the first The integrated participation factor of the aforementioned grid-type converter, wherein... The number of the dominant modes, For the first Modal weights of the dominant modes, For the first The grid-type converter mentioned above is in the first Participation factors under the dominant mode.

[0011] Furthermore, the determination of the key grid-type converters includes: sorting each grid-type converter from largest to smallest according to the first participation factor or the comprehensive participation factor, and then ranking the top-ranked converters... The aforementioned grid-type converter is identified as the key grid-type converter, wherein... These are preset parameters set according to the system scale or operational requirements of the multi-machine grid converter system.

[0012] Furthermore, the low-frequency oscillation suppression control is achieved by introducing an additional control loop in the key grid-type converter, wherein the additional control loop is an additional damping control loop or a virtual impedance control loop.

[0013] A vibration suppression and identification system for a grid-type multi-machine key converter, the system comprising: The system parameter acquisition module acquires the capacity matrix and network-side power frequency admittance matrix of the multi-machine network converter system. The extended impedance construction module constructs an extended impedance matrix based on the capacity matrix and the network-side power frequency admittance matrix. The dominant mode determination module determines the first mode state or the second mode state based on the minimum eigenvalue distribution of the extended impedance matrix. The first mode state corresponds to a single dominant mode, and the second mode state corresponds to multiple dominant modes. The key equipment identification module determines the first participation factor of each grid-type converter in the first mode state, or determines the comprehensive participation factor of each grid-type converter based on the participation factors corresponding to multiple dominant modes in the second mode state, and identifies the key grid-type converter based on the first participation factor or the comprehensive participation factor. The low-frequency oscillation suppression module only implements low-frequency oscillation suppression control for critical grid-type converters.

[0014] A computer-readable storage medium stores a computer program, the computer program including program instructions, which, when executed by a processor, can implement the aforementioned method for identifying and suppressing vibrations in a network-type multi-machine key converter.

[0015] The technical solution of this invention can achieve the following technical effects: By constructing an extended impedance model for a multi-machine grid-type converter system, the dominant mode type is determined based on the minimum eigenvalue distribution. Participation factors or comprehensive participation factors are calculated for different mode states to identify key grid-type converters. Then, low-frequency oscillation suppression control is implemented only on the key grid-type converters. This effectively solves the problem of accurately identifying the key converters that play a dominant role in low-frequency stability in a multi-machine grid-type converter system and thus achieving targeted low-frequency oscillation suppression.

[0016] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0017] 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 recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A flowchart illustrating the vibration suppression measurement method for identifying key multi-machine converters in a grid-type system; Figure 2 A schematic diagram of the IEEE 39-node system; Figure 3 A three-dimensional diagram of the participation factors in the IEEE 39-node system; Figure 4 A comprehensive participation factor diagram for the IEEE 39-node system; Figure 5The simulation comparison diagram shows the active power of each converter under the three calculation examples. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] Example 1; like Figure 1 As shown, this application provides a method for identifying and suppressing vibration in a grid-type multi-machine key converter. The method includes: S10: Obtain the capacity matrix and network-side power frequency admittance matrix of the multi-machine network converter system; S20: Construct the extended impedance matrix based on the capacity matrix and the network-side power frequency admittance matrix; S30: Determine the first mode state or the second mode state based on the minimum eigenvalue distribution of the extended impedance matrix. The first mode state corresponds to a single dominant mode, and the second mode state corresponds to multiple dominant modes. S40: Determine the first participation factor of each grid-type converter in the first mode state, or determine the comprehensive participation factor of each grid-type converter in the second mode state based on the participation factors corresponding to multiple dominant modes, and determine the key grid-type converter based on the first participation factor or the comprehensive participation factor. S50: Low-frequency oscillation suppression control is implemented only for critical grid-type converters.

[0022] Specifically, this embodiment provides a method for identifying and suppressing vibration of key grid-type multi-machine converters, which is applicable to multi-machine parallel systems of grid-type converters and hybrid systems composed of grid-type converters and grid-connected converters. Obtain the capacity matrix and network-side power frequency admittance matrix of a multi-machine grid-type converter system. The capacity matrix consists of the capacities of each grid-type converter in the system. The network-side power frequency admittance matrix is ​​used to characterize the electrical connection relationships on the network side of the system. For systems containing internal passive nodes, after eliminating the internal passive nodes, the power frequency admittance matrix is ​​divided into corresponding sub-blocks. , , and ; When grid-connected converters and integrated grid-connected converters are connected in parallel, the network-side hybrid admittance-impedance transfer function matrix in current / voltage form is established: ; in, ; ; ; ; ; In the formula, and These are the voltage disturbance column vector and the current disturbance column vector of the grid-type converter, respectively. and These are the voltage disturbance column vector and the current disturbance column vector of the grid-connected converter, respectively. , , and This is the corresponding submatrix of the network-side hybrid admittance-impedance transfer function matrix; , , and This refers to the sub-block corresponding to the power frequency admittance matrix after eliminating internal passive nodes; for identity matrix; This is the transfer matrix corresponding to the line; For the Laplace operator, Represents synchronous rotational speed. Represents the line resistance-to-inductance ratio; Determine the equivalent network admittance matrix based on the corresponding sub-block of the network-side power frequency admittance matrix: ; Construct the capacity matrix: ; Then, the extended impedance matrix is ​​constructed: ; In the formula, The equivalent network admittance matrix; A diagonal matrix representing the capacity of grid-type converters; , to These represent the capacities of each grid-type converter; This refers to the number of grid-type converters in the system. It is the first power of the capacity matrix; It is the inverse of the equivalent network admittance matrix; For extended impedance matrix of multi-machine grid converter system; Calculate the eigenvalues ​​of the extended impedance matrix, denoted as . And satisfy: ; In the formula, For the characteristic value index, It is the smallest eigenvalue. The second smallest eigenvalue; to determine whether the smallest eigenvalue is dense, when... hour, and If the interval is significant, it is treated as a single dominant mode and defined as the first mode state; otherwise, it is treated as multiple dominant modes and defined as the second mode state; where, Given a threshold, it is used to determine the density between the smallest feature values; In the first modal state, the participation factor corresponding to the access node of each grid-type converter is calculated, and this participation factor is used as the first participation factor; in the second modal state... The first participation factor of the grid-type converter access node for: ; In the formula, For the first The first participation factor corresponding to the access node of the grid-type converter; For the extended impedance matrix The smallest eigenvalue; and They are respectively The first corresponding to the left eigenvector and the right eigenvector One element; For the extended impedance matrix The One diagonal element; the magnitude of the first participation factor is used to reflect the degree of participation of the corresponding grid-type converter in a single dominant mode; In the second modal state, determine The smallest eigenvalues ​​that are close to each other: ; In the formula, It represents the number of the smallest eigenvalues ​​that are closest to each other, and also the number of dominant modes; The dominant mode number; For the first The eigenvalues ​​corresponding to each dominant mode; each Corresponding to a dominant mode, the first The set of participating factors corresponding to each dominant mode is denoted as . ,in, For the first The dominant mode is the 1st Participation factors of individual grid-type converters; To distinguish the importance of each dominant mode, weights are introduced: ; In the formula, For the first The weights corresponding to the dominant mode are calculated by combining the participation factors and weights of each dominant mode. The overall participation factor of a grid-type converter: ; In the formula, For the first The comprehensive participation factor of the grid-type converter is used to reflect the first... The degree of integrated participation of individual grid-type converters in multiple dominant modes; After obtaining the first participation factor or the comprehensive participation factor, the grid-type converters are ranked according to the magnitude of the corresponding participation factor; in the first mode state, the key grid-type converters are determined according to the magnitude of the first participation factor; in the second mode state, the key grid-type converters are determined according to the magnitude of the comprehensive participation factor; specifically, the first participation factor or the comprehensive participation factor is selected and ranked from largest to smallest. One grid-type converter is used as the key grid-type converter, among which... These are preset parameters that can be set according to system scale or operational requirements; the key network converter refers to the network converter that plays a leading role in the low-frequency stability of the system during multi-machine interaction, as determined by the evaluation results of participation factors. After identifying the key grid-type converters, additional control loops are introduced only for the key grid-type converters to implement low-frequency oscillation suppression control. The additional control loops include additional damping control and virtual impedance control. By implementing targeted control on the identified key grid-type converters, low-frequency oscillation suppression of the multi-machine system of grid-type converters is achieved, while avoiding the uniform configuration of control strategies for all grid-type converters.

[0023] The technical solution of this invention constructs an extended impedance model for a multi-machine grid converter system, identifies the dominant mode type based on the minimum eigenvalue distribution, and calculates participation factors or comprehensive participation factors for different mode states to identify key grid converters. This allows for the implementation of low-frequency oscillation suppression control only on the key grid converters, effectively solving the problem of accurately identifying the key converters that play a dominant role in low-frequency stability in a multi-machine grid converter system and achieving targeted low-frequency oscillation suppression accordingly.

[0024] Furthermore, the network-side power frequency admittance matrix is ​​the power frequency admittance matrix obtained after eliminating the internal passive nodes in the multi-machine system of the grid-type converter. The network-side hybrid admittance-impedance transfer relationship is established based on the matrix sub-blocks in the network-side power frequency admittance matrix corresponding to the grid-type converter access nodes and the grid-type converter access nodes.

[0025] As a preferred embodiment of the above, in a hybrid system consisting of a grid-type converter and a grid-connected converter, a network-side power frequency admittance matrix is ​​formed according to the system network topology, and passive nodes are eliminated to preserve the network electrical relationship between the grid-type converter access nodes and the grid-connected converter access nodes; passive nodes refer to nodes that are not used as access nodes of either the grid-type converter or the grid-connected converter and are eliminated during the network equivalence process. The power frequency admittance matrix after eliminating internal passive nodes is divided into blocks according to the access nodes of the grid-type converter and the grid-connected converter, resulting in corresponding matrix sub-blocks. , , and Furthermore, the network-side hybrid admittance-impedance transfer relationship is established using each matrix sub-block to characterize the coupling relationship between voltage disturbances, current disturbances, and the network in grid-type converters and mesh-type converters. Among them, the network-side hybrid admittance-impedance transfer relationship refers to the network equivalent relationship that uses admittance and impedance relationships to describe the disturbance transfer characteristics of grid-type converters and grid-connected converters after they are connected to the network; the network-side power frequency admittance information obtained by this processing is used for the subsequent construction of the extended impedance matrix.

[0026] Furthermore, the construction of the extended impedance matrix includes: The equivalent network admittance matrix corresponding to the access node of the grid-type converter is determined based on the matrix sub-blocks of the network-side power frequency admittance matrix. Construct a diagonal capacity matrix based on the capacity of each grid-type converter; By applying a capacity-weighted summation to the inverse of the equivalent network admittance matrix using the capacity matrix, the extended impedance matrix is ​​obtained: .

[0027] As a preferred embodiment of the above, the equivalent network admittance matrix corresponding to the access node of the grid-type converter is determined according to the matrix sub-blocks of the network-side power frequency admittance matrix; the equivalent network admittance matrix refers to the network admittance matrix used to characterize the electrical coupling relationship between each access node of the grid-type converter after eliminating the explicit influence of the access node of the grid-type converter on the network equation; specifically, according to the matrix sub-blocks , , and Perform matrix operations to obtain This transforms the original network relationship into an equivalent network relationship oriented towards the access nodes of the grid-type converter; Construct a capacity matrix based on the capacity of each grid-type converter. The capacity matrix is ​​in diagonal form, with each diagonal element corresponding to the capacity of a grid-type converter. The matrix dimension corresponds to the number of grid-type converters in the system. This matrix is ​​used to introduce the capacity differences of different grid-type converters into the analysis of multi-machine systems. For the equivalent network admittance matrix Inverse the equation to obtain the equivalent network impedance relationship between the access nodes of the grid-type converter, and then use the capacity matrix. Capacitance weighting of the equivalent network impedance yields the extended impedance matrix. Capacity weighting refers to introducing matrix factors formed by the capacity of the network converters on both sides of the equivalent network impedance, so that the extended impedance matrix simultaneously contains network coupling information and capacity information of each network converter; the extended impedance matrix is ​​used for subsequent eigenvalue calculation and dominant mode discrimination.

[0028] Furthermore, the determination of the first or second modal state includes: Determine the relative interval between the smallest and second smallest eigenvalues ​​of the extended impedance matrix; When the relative interval is greater than a preset threshold, the multi-machine system of the grid converter is determined to be in the first mode state; When the relative interval is less than or equal to a preset threshold, the multi-machine system of the grid converter is determined to be in the second mode state.

[0029] As a preferred embodiment of the above, the eigenvalues ​​of the extended impedance matrix are calculated and sorted according to their size. The smallest and second smallest eigenvalues ​​are used as the criteria for determining the dominant mode state. The smallest eigenvalue is the eigenvalue with the smallest value after sorting, and the second smallest eigenvalue is the eigenvalue that is adjacent to the smallest eigenvalue and has the second smallest value. Calculate the relative interval between the smallest eigenvalue and the second smallest eigenvalue; the relative interval is a quantity obtained by normalizing the difference between the two relative to the smallest eigenvalue, used to measure the degree of separation between the two smaller eigenvalues; compare the relative interval with a preset threshold, which is a given threshold used to determine whether the smallest eigenvalues ​​are densely distributed; When the relative interval is greater than the preset threshold, it indicates that the interval between the minimum eigenvalue and the second smallest eigenvalue is significant, and the minimum eigenvalue is not densely distributed. The current state is determined as the first modal state. The first modal state refers to the state in which the low-frequency stability of the system is mainly determined by a single dominant mode. In this state, the dominant mode corresponding to the minimum eigenvalue is used for subsequent participation factor calculation. When the relative interval is less than or equal to the preset threshold, it indicates that there are similar eigenvalues ​​near the minimum eigenvalue, and the minimum eigenvalues ​​are densely distributed. The current state is determined as the second modal state. The second modal state refers to the state in which the low-frequency stability of the system is determined by multiple dominant modes. In this state, the dominant modes corresponding to multiple similar minimum eigenvalues ​​are comprehensively involved in factor analysis.

[0030] Furthermore, in the first mode state, the first The first participation factor of a grid-type converter is determined according to the following formula: ; in, The smallest eigenvalue of the extended impedance matrix. and These are the left and right eigenvectors corresponding to the minimum eigenvalue, respectively. One element, For the extended impedance matrix, the first One diagonal element.

[0031] As a preferred embodiment of the above, in the first modal state, the dominant mode corresponding to the minimum eigenvalue of the extended impedance matrix is ​​taken as the object of participation factor analysis; the first participation factor is defined as an evaluation quantity used to characterize the degree of participation of each grid-type converter access node in the minimum eigenvalue under a single dominant mode condition. The larger the first participation factor, the higher the degree of participation of the corresponding grid-type converter in the dominant mode. Minimum eigenvalues ​​of the extended impedance matrix Calculate the corresponding left and right eigenvectors, and extract the corresponding left and right eigenvectors respectively. The first grid-type converter access node corresponding to the first element and Simultaneously, obtain the extended impedance matrix. diagonal elements According to the aforementioned calculation relationship of the participating factors, the first... The first participation factor corresponding to a network converter ;in, This refers to the node number connected to the grid-type converter. The smallest eigenvalue of the extended impedance matrix. and These are the left and right eigenvectors corresponding to the smallest eigenvalue, respectively. One element, For the extended impedance matrix, the first One diagonal element; The above calculations are performed sequentially on each grid-type converter access node in the system to obtain the first participation factor corresponding to each grid-type converter, providing an evaluation basis for subsequently determining the key grid-type converters according to their participation level.

[0032] Furthermore, in the second modal state, the determination of the comprehensive participation factors includes: Multiple eigenvalues ​​whose relative interval with the minimum eigenvalue is no greater than a preset threshold are determined as the dominant eigenvalues ​​corresponding to multiple dominant modes; The modal weights of each dominant mode are determined based on the ratio between the minimum eigenvalue and each dominant eigenvalue. According to the first dominant mode The participation factors and corresponding modal weights of each grid-type converter are determined according to: ; Determine the first The comprehensive participation factor of a grid-type converter, among which... The number of dominant modes, For the first Modal weights of the dominant modes, For the first The grid-type converter in the first Participation factors under the dominant mode.

[0033] As a preferred embodiment of the above, in the second modal state, the eigenvalues ​​that are close to each other are determined from the eigenvalues ​​of the extended impedance matrix. Each minimum eigenvalue is assigned a minimum eigenvalue and is used as a dominant eigenvalue corresponding to a dominant mode. A dominant eigenvalue is an eigenvalue used to characterize the corresponding dominant mode when multiple dominant modes jointly affect the low-frequency stability of the system. This represents the number of the smallest eigenvalues ​​that are close to each other, and also represents the number of dominant modes participating in the comprehensive evaluation; Calculate the participation factors of each grid-type converter under each dominant mode to obtain the set of participation factors corresponding to each dominant mode; The set of participation factors corresponding to each dominant mode reflects the degree of participation of each grid-type converter in the system under that dominant mode. The dominant mode number is used to distinguish the importance of different dominant modes. The corresponding mode weight is determined based on the relationship between the minimum eigenvalue and each dominant eigenvalue. The mode weight is a weighting coefficient used to characterize the relative importance of different dominant modes in the comprehensive evaluation. The closer the eigenvalue is to the minimum eigenvalue, the greater the corresponding weight. The participation factors of the same grid-type converter under each dominant mode are weighted and combined with the corresponding mode weights to obtain the comprehensive participation factor of each grid-type converter. The comprehensive participation factor refers to the evaluation quantity that comprehensively reflects the degree of participation of the same grid-type converter in multiple dominant modes when there are multiple dominant modes. It is used to form a unified key evaluation basis for each grid-type converter and to be used for subsequent ranking and identification of key grid-type converters.

[0034] Furthermore, the determination of key grid-type converters includes: ranking each grid-type converter from largest to smallest according to the first participation factor or comprehensive participation factor, and then ranking the top-ranked converters... One grid-type converter was identified as the key grid-type converter, among which... These are preset parameters set according to the system scale or operational requirements of a multi-machine grid converter system.

[0035] As a preferred embodiment of the above embodiments, after calculating the participation degree of each grid-type converter, the corresponding evaluation quantity is selected and sorted according to the current modal state; in the first modal state, the first participation factor of each grid-type converter is used as the sorting basis; in the second modal state, the comprehensive participation factor of each grid-type converter is used as the sorting basis, and the grid-type converters are arranged from large to small according to the evaluation quantity; the larger the evaluation quantity, the higher the participation degree of the corresponding grid-type converter in the dominant mode of the system; Select the top-ranked results from the sorted list. A grid-type converter is used as the key grid-type converter; among them... The preset parameter indicates the number of key grid-type converters that need to be determined. It can be set according to the system scale or operation requirements of the multi-machine grid-type converter system. Key grid-type converters refer to grid-type converters with relatively large participation factors or comprehensive participation factors, which play a dominant role in the low-frequency stability of the system during multi-machine interaction. Through the above sorting and screening, the grid-type converters in the system are distinguished according to their degree of participation in low-frequency stability, providing control targets for configuring low-frequency oscillation suppression control only for key grid-type converters.

[0036] Furthermore, low-frequency oscillation suppression control is achieved by introducing an additional control loop in the key grid-type converter. The additional control loop is either an additional damping control loop or a virtual impedance control loop.

[0037] As a preferred embodiment of the above, after determining the key grid-type converter, an additional control loop is introduced only for the identified key grid-type converter, while the other grid-type converters maintain their original control methods. The additional control loop refers to the control link added to the original control structure of the grid-type converter to improve the low-frequency oscillation characteristics of the system. It can be an additional damping control or a virtual impedance control. When using additional damping control, the additional damping control loop is configured in the key grid-type converter to improve the attenuation capability of low-frequency oscillations through additional control action; when using virtual impedance control, a virtual impedance control loop is introduced into the key grid-type converter to suppress low-frequency oscillations by changing the equivalent control characteristics of the corresponding converter. After the additional control loop configuration is completed, when the system experiences disturbances and low-frequency oscillations, the key grid-type converter will take on the targeted oscillation suppression role, without the need to add additional control to all grid-type converters. By limiting the additional control objects, the number of additional controllers and the mutual influence between the control parameters of multiple machines can be reduced, while improving the low-frequency stability of the multi-machine grid-type converter system.

[0038] Example 2; Based on the same inventive concept as the vibration suppression measurement method for identifying a grid-type multi-machine key converter in the foregoing embodiments, the present invention also provides a vibration suppression measurement system for identifying a grid-type multi-machine key converter, the system comprising: The system parameter acquisition module acquires the capacity matrix and network-side power frequency admittance matrix of the multi-machine network converter system. The extended impedance construction module constructs an extended impedance matrix based on the capacity matrix and the network-side power frequency admittance matrix. The dominant mode determination module determines the first mode state or the second mode state based on the minimum eigenvalue distribution of the extended impedance matrix. The first mode state corresponds to a single dominant mode, and the second mode state corresponds to multiple dominant modes. The key equipment identification module determines the first participation factor of each grid-type converter in the first mode state, or determines the comprehensive participation factor of each grid-type converter based on the participation factors corresponding to multiple dominant modes in the second mode state, and identifies the key grid-type converter based on the first participation factor or the comprehensive participation factor. The low-frequency oscillation suppression module only implements low-frequency oscillation suppression control for critical grid-type converters.

[0039] The adjustment system described above in this invention can effectively realize a method for identifying and suppressing vibration of a grid-type multi-machine key converter. The technical effects it can achieve are as described in the above embodiments, and will not be repeated here.

[0040] Example 3; Based on the same inventive concept as the method for identifying and suppressing vibration of a grid-type multi-machine key converter in the foregoing embodiments, the present invention also provides a computer-readable storage medium storing a computer program, the computer program including program instructions, which, when executed by a processor, can realize the method for identifying and suppressing vibration of a grid-type multi-machine key converter.

[0041] Example 4; This invention is built in the MATLAB / Simulink environment as follows Figure 2 The method shown is based on the IEEE 39-node system and is used to verify the correctness of the key converter identification and low-frequency oscillation suppression method for a multi-machine grid converter system. Three sets of calculation examples are designed for verification. In the three sets of calculation examples, the system is connected to a total of 5 grid-type energy storage units (nodes 30, 33, 34, 35, 38, grid-type converters numbered 1, 2, 3, 4, 5) and 4 grid-connected wind farms (nodes 31, 32, 37, 39, grid-connected converters numbered 1, 2, 3, 4). Figure 3 This paper presents a three-dimensional plot of the participation factors of the IEEE 39-node system in an embodiment of the present invention. The plot uses normalized eigenvalues ​​as the x-axis, where normalized eigenvalues ​​are used to eliminate differences in eigenvalue scale under different operating conditions for easy comparison. The converter number is on the y-axis, and the participation factor is on the z-axis, clearly reflecting the degree of participation of each converter in low-frequency oscillations in different dominant modes. Each group of bars of the same color visually presents the distribution of the participation factors of each converter in a mode. For example, the innermost bright yellow bar group corresponds to the distribution of the participation factors of the dominant mode. In this example, the minimum eigenvalue distribution is sparse, with only one dominant mode. Therefore, the distribution of the bright yellow bar group is consistent with the overall participation factor result. Figure 4 The integrated participation factor diagram of the IEEE 39-node system in this embodiment of the invention is shown; it can be seen that converters 2 and 3 have the largest participation factors, so converters 2 and 3 are identified as key units; All three cases experienced a voltage drop at 2.5s and recovered after 0.05s; Case A was the original system without introducing additional control loops, Case B introduced virtual impedance loops on the voltage outer loops of critical converters 2 and 3, and Case C adopted the same suppression strategy on non-critical converters 1 and 5. Figure 5 The active power output of each device is given in three examples. In example a, after the voltage is restored, the active power output of each converter oscillates with the same amplitude, and the system is in a critically stable state. In example b, after the voltage is restored, the active power of each converter converges quickly to a stable value, and the system stability is significantly improved. In example c, after the voltage is restored, the active power of each converter oscillates with the same amplitude, and the system is still in a critically stable state. This embodiment demonstrates that by controlling only a few key converters identified by the method of the present invention, the low-frequency oscillation of the entire multi-machine system can be effectively suppressed. While achieving significant stability, it greatly reduces the number of controllers that need to be configured and tuned.

[0042] Although this application has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made thereto without departing from the spirit and scope of this application. Accordingly, this specification and drawings are merely exemplary illustrations of the application as defined herein, and are to be considered as covering any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from its scope. Thus, if such modifications and modifications fall within the scope of this application and its equivalents, this application intends to include such modifications and modifications.

Claims

1. A method for identifying and measuring vibration suppression in a grid-type multi-machine key converter, characterized in that, The method includes: Obtain the capacity matrix and the network-side power frequency admittance matrix of a multi-machine grid-type converter system; Construct an extended impedance matrix based on the capacity matrix and the network-side power frequency admittance matrix; The first mode state or the second mode state is determined based on the minimum eigenvalue distribution of the extended impedance matrix. The first mode state corresponds to a single dominant mode, and the second mode state corresponds to multiple dominant modes. In the first mode state, the first participation factor of each grid-type converter is determined, or in the second mode state, the comprehensive participation factor of each grid-type converter is determined according to the participation factors corresponding to multiple dominant modes, and the key grid-type converter is determined according to the first participation factor or the comprehensive participation factor. Low-frequency oscillation suppression control is implemented only for the key grid-type converter.

2. The method for identifying and suppressing vibration of a grid-type multi-machine key converter according to claim 1, characterized in that, The network-side power frequency admittance matrix is ​​the power frequency admittance matrix obtained after eliminating the internal passive nodes in the multi-machine system of the grid-type converter. The network-side hybrid admittance-impedance transfer relationship is established based on the matrix sub-blocks in the network-side power frequency admittance matrix corresponding to the grid-type converter access nodes and the grid-type converter access nodes.

3. The method for identifying and suppressing vibration in a grid-type multi-machine key converter according to claim 1, characterized in that, The construction of the extended impedance matrix includes: The equivalent network admittance matrix corresponding to the access node of the grid-type converter is determined based on the matrix sub-blocks of the network-side power frequency admittance matrix. Construct the capacity matrix in diagonal form based on the capacity of each of the grid-type converters; The extended impedance matrix is ​​obtained by performing a capacity-weighted summation on the inverse of the equivalent network admittance matrix using the capacity matrix: 。 4. The method for identifying and suppressing vibration in a grid-type multi-machine key converter according to claim 1, characterized in that, Determining the first modal state or the second modal state includes: Determine the relative interval between the smallest and second smallest eigenvalues ​​of the extended impedance matrix; If the relative interval is greater than a preset threshold, the grid-type converter multi-machine system is determined to be in the first mode state; When the relative interval is less than or equal to the preset threshold, the grid-type converter multi-machine system is determined to be in the second mode state.

5. The method for identifying and suppressing vibration in a grid-type multi-machine key converter according to claim 1, characterized in that, In the first modal state, the first The first participation factor of the grid-type converter is determined according to the following formula: ； in, The smallest eigenvalue of the extended impedance matrix is... and The left and right eigenvectors corresponding to the minimum eigenvalue are respectively the first and second eigenvectors. One element, The first of the extended impedance matrix One diagonal element.

6. The method for identifying and suppressing vibration in a grid-type multi-machine key converter according to claim 1, characterized in that, In the second modal state, the determination of the integrated participation factor includes: Multiple feature values ​​whose relative interval with the minimum feature value is not greater than a preset threshold are determined as the dominant feature values ​​corresponding to the multiple dominant modes; The modal weights of each dominant mode are determined based on the ratio between the minimum eigenvalue and each of the dominant eigenvalues. According to the dominant modes described above, the first The participation factors and corresponding modal weights of the grid-type converter are determined according to: ； Determine the first The integrated participation factor of the aforementioned grid-type converter, wherein... The number of the dominant modes, For the first Modal weights of the dominant modes, For the first The grid-type converter mentioned above is in the first Participation factors under the dominant mode.

7. The method for identifying and suppressing vibration in a grid-type multi-machine key converter according to claim 1, characterized in that, The determination of the key grid-type converters includes: sorting each grid-type converter from largest to smallest according to the first participation factor or the comprehensive participation factor, and then ranking the top-ranked converters... The aforementioned grid-type converter is identified as the key grid-type converter, wherein... These are preset parameters set according to the system scale or operational requirements of the multi-machine grid converter system.

8. The method for identifying and suppressing vibration in a grid-type multi-machine key converter according to claim 1, characterized in that, The low-frequency oscillation suppression control is achieved by introducing an additional control loop in the key grid-type converter. The additional control loop is an additional damping control loop or a virtual impedance control loop.

9. A vibration suppression measurement system for identifying key multi-machine grid-type converters, characterized in that, The system includes: The system parameter acquisition module acquires the capacity matrix and network-side power frequency admittance matrix of the multi-machine network converter system. The extended impedance construction module constructs an extended impedance matrix based on the capacity matrix and the network-side power frequency admittance matrix. The dominant mode determination module determines the first mode state or the second mode state based on the minimum eigenvalue distribution of the extended impedance matrix. The first mode state corresponds to a single dominant mode, and the second mode state corresponds to multiple dominant modes. The key equipment identification module determines the first participation factor of each grid-type converter in the first mode state, or determines the comprehensive participation factor of each grid-type converter based on the participation factors corresponding to multiple dominant modes in the second mode state, and identifies the key grid-type converter based on the first participation factor or the comprehensive participation factor. The low-frequency oscillation suppression module only implements low-frequency oscillation suppression control for critical grid-type converters.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which includes program instructions that, when executed by a processor, can implement the method for identifying and suppressing vibration of a grid-type multi-machine key converter as described in any one of claims 1-8.

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