Impedance network modeling method and device for ac-dc hybrid system

Abstract

The application relates to the technical field of power system modeling, in particular to an impedance network modeling method and device for an AC-DC hybrid system, wherein the method comprises the following steps: establishing impedance models of various power devices in the AC-DC hybrid system, and establishing an admittance matrix of AC network nodes except for a converter; and obtaining an impedance network model of the AC-DC hybrid system by establishing an admittance matrix of an AC system containing the converter and a multi-port model of a DC network. According to the embodiment of the application, the impedance model can represent the dynamic characteristics of the devices by circuit equation connection, and the voltage-current relationship of the system nodes is established, so that the impedance network model capable of representing the overall dynamic characteristics of the system is obtained, the modeling method can be applied to large-scale actual AC-DC hybrid system modeling, is favorable for oscillation mechanism analysis, the universality and comprehensiveness of the modeling method are enhanced, and the modeling result is more reliable.

Description

Technical Field

[0001] This application relates to the field of power system modeling technology, and in particular to an impedance network modeling method and apparatus for AC / DC hybrid systems. Background Technology

[0002] In related technologies, the oscillation stability of the power system can be studied by modeling the AC / DC hybrid power grid system, so as to ensure the safe and stable operation of the power grid.

[0003] However, in related technologies, existing modeling methods are complex and difficult to apply to large-scale real-world system modeling. They also have limited applicability and cannot accurately model large-scale complex AC / DC hybrid systems. This increases the complexity of modeling calculations, reduces the reliability of the constructed system model, and results in insufficient universality and comprehensiveness of the modeling methods, which urgently need to be addressed. Summary of the Invention

[0004] This application is based on the inventor's understanding of the following issues:

[0005] As the power system develops towards a high proportion of new energy sources and a high proportion of power electronics, a large number of power electronic converters are being connected to the power system for AC / DC power conversion. The future power system will be a hybrid AC / DC power grid.

[0006] However, the connection of a large number of power electronic devices significantly affects the dynamic characteristics of the system and may cause oscillation stability problems, which seriously threaten the safe and stable operation of the power grid. It is necessary to study the oscillation stability problem of AC-DC hybrid systems, and the first problem to be solved is the modeling problem of AC-DC hybrid systems.

[0007] Existing modeling methods commonly include state-space equation methods, source-load equivalent methods, and impedance network modeling methods. State-space equation modeling methods establish the system's differential-algebraic equations and transform them into state-space equations. While this method accurately characterizes the system's dynamic properties, the modeling process is complex and difficult to apply to large-scale systems. The source-load equivalent method divides the system into two parts at the converter grid connection node: the converter side is typically considered the source subsystem, and the grid side is typically considered the load subsystem. Impedance models are established for both the converter and grid sides. Then, based on the ratio of their admittances, the open-loop transfer function of the system is calculated to further analyze the system's oscillation stability. The advantage of this method is its simplicity; the disadvantage is that it is only applicable to simple interconnected grids dominated by converters, and its accuracy for large-scale complex AC / DC hybrid systems requires further verification. Impedance network modeling method establishes impedance models of each power device in the system, and connects the individual impedance models into a system-level impedance network using circuit equations. This impedance network typically uses the voltage and injected current of each node as input and output, forming a multiple-input multiple-output (MIMO) system. Then, the stability theory of MIMO system is used for analysis. The advantage of this method is that it can characterize the overall dynamic characteristics of the system and is applicable to the modeling of large-scale systems. However, it is currently mainly applicable to the modeling of AC power grids, rather than the impedance network modeling of AC / DC hybrid systems.

[0008] This application provides an impedance network modeling method and apparatus for AC / DC hybrid systems to address the problems in related technologies, such as the complexity of existing modeling methods, their difficulty in applying them to large-scale practical system modeling, their limited applicability, their inability to accurately model large-scale complex AC / DC hybrid systems, their increased complexity of modeling calculations, their reduced reliability of the constructed system model, and their lack of universality and comprehensiveness in modeling methods.

[0009] The first aspect of this application provides an impedance network modeling method for an AC / DC hybrid system, comprising the following steps: establishing impedance models for each power device in the AC / DC hybrid system; establishing AC network node admittance matrices excluding converters based on the impedance models of each power device in the AC / DC hybrid system; establishing an AC system admittance matrix including converters based on the node admittance matrices; establishing a multi-port model of the DC network; and combining the AC system admittance matrix including converters and the multi-port model of the DC network to obtain the impedance network model of the AC / DC hybrid system.

[0010] Optionally, in one embodiment of this application, the formula for establishing the admittance matrix of the AC network nodes other than the converter is:

[0011]

[0012] in, This represents the admittance matrix of the AC network nodes excluding the converter. This is a diagonal matrix, with the diagonal elements representing the admittance models of each AC device. This is the node-branch correlation matrix.

[0013] Optionally, in one embodiment of this application, the formula for establishing the admittance matrix of the AC system including the converter is:

[0014]

[0015] in, The AC system admittance matrix of the converter. Y is a 2n+m dimensional matrix extended by the admittance matrix of the AC network nodes excluding the converter. j The extended 2n+m dimensional matrix is ​​obtained from the three-port admittance model, where j is the converter device number in the AC / DC hybrid system, n is the number of AC nodes in the AC / DC hybrid system, and m is the number of converters in the AC / DC hybrid system; The block is denoted as

[0016]

[0017] Among them, Y 11 Y is a 2n-dimensional matrix. 22 Let Y be an m-dimensional matrix. 12 Y is a 2n×m dimensional matrix. 21 It is an m×2n dimensional matrix, where n is the number of AC nodes in the AC-DC hybrid system and m is the number of converters in the AC-DC hybrid system.

[0018] Optionally, in one embodiment of this application, the multiport impedance model of the DC network is Y. dc It is an m-dimensional matrix, Y dc It can be obtained through short-circuit coefficient measurement or node voltage method.

[0019] Optionally, in one embodiment of this application, the formula for establishing the impedance network model of the AC / DC hybrid system is:

[0020]

[0021] Among them, Y ext For the impedance network model of the AC / DC hybrid system, Y dc Y is a multi-port m-dimensional matrix of a DC network. 11 Y is a 2n-dimensional matrix. 22 Let n be an m-dimensional matrix, where n is the number of AC nodes in the AC / DC hybrid system and m is the number of converters in the AC / DC hybrid system.

[0022] A second aspect of this application provides an impedance network modeling device for an AC / DC hybrid system, comprising: a first construction module for establishing impedance models of each power device in the AC / DC hybrid system; a second construction module for establishing AC network node admittance matrices excluding converters based on the impedance models of each power device in the AC / DC hybrid system; a third construction module for establishing an AC system admittance matrix including converters based on the node admittance matrices; a fourth construction module for establishing a multi-port model of the DC network; and a modeling module for combining the AC system admittance matrix including converters and the multi-port model of the DC network to obtain the impedance network model of the AC / DC hybrid system.

[0023] Optionally, in one embodiment of this application, the formula for establishing the admittance matrix of the AC network nodes other than the converter is:

[0024]

[0025] in, This represents the admittance matrix of the AC network nodes excluding the converter. This is a diagonal matrix, with the diagonal elements representing the admittance models of each AC device. This is the node-branch correlation matrix.

[0026] Optionally, in one embodiment of this application, the formula for establishing the admittance matrix of the AC system including the converter is:

[0027]

[0028] Among them, among them, The AC system admittance matrix of the converter. Y is a 2n+m dimensional matrix extended by the admittance matrix of the AC network nodes excluding the converter. j The extended 2n+m dimensional matrix is ​​obtained from the three-port admittance model, where j is the converter device number in the AC / DC hybrid system, n is the number of AC nodes in the AC / DC hybrid system, and m is the number of converters in the AC / DC hybrid system; The block is denoted as

[0029]

[0030] Among them, Y 11 Y is a 2n-dimensional matrix. 22 Let Y be an m-dimensional matrix. 12 Y is a 2n×m dimensional matrix. 21 It is an m×2n dimensional matrix, where n is the number of AC nodes in the AC-DC hybrid system and m is the number of converters in the AC-DC hybrid system.

[0031] Optionally, in one embodiment of this application, the multiport impedance model of the DC network is Y. dc It is an m-dimensional matrix, Y dc It can be obtained through short-circuit coefficient measurement or node voltage method.

[0032] Optionally, in one embodiment of this application, the formula for establishing the impedance network model of the AC / DC hybrid system is:

[0033]

[0034] Among them, Y ext For the impedance network model of the AC / DC hybrid system, Y dc Y is a multi-port m-dimensional matrix of a DC network. 11 Y is a 2n-dimensional matrix. 22 Let n be an m-dimensional matrix, where n is the number of AC nodes in the AC / DC hybrid system and m is the number of converters in the AC / DC hybrid system.

[0035] A third aspect of this application provides an electronic device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the impedance network modeling method for an AC / DC hybrid system as described in the above embodiments.

[0036] A fourth aspect of this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the impedance network modeling method for an AC / DC hybrid system as described above.

[0037] This application's embodiments can establish impedance models for each power device in an AC / DC hybrid system. Based on these impedance models, the admittance moments of the AC network nodes (excluding the converter) are established. An AC system admittance matrix including the converter is then established based on the node admittance matrices. A multi-port model of the DC network is also established. Combining the AC system admittance matrix including the converter and the multi-port model of the DC network, an impedance network model of the AC / DC hybrid system is obtained. This model is applicable to large-scale practical system modeling and is beneficial for oscillation mechanism analysis, enhancing the versatility and comprehensiveness of the modeling method and making the modeling results more reliable. Therefore, it solves the problems in related technologies where existing modeling methods are complex, difficult to apply to large-scale practical system modeling, have limited applicability, cannot accurately model large-scale complex AC / DC hybrid systems, increase the complexity of modeling calculations, reduce the reliability of the constructed system model, and result in insufficient versatility and comprehensiveness of the modeling method.

[0038] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0039] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0040] Figure 1 This is a flowchart of an impedance network modeling method for an AC / DC hybrid system according to an embodiment of this application;

[0041] Figure 2 This is a flowchart illustrating the impedance network modeling of an AC / DC hybrid system according to an embodiment of this application.

[0042] Figure 3 This is a schematic diagram of the impedance network modeling device for an AC / DC hybrid system according to an embodiment of this application;

[0043] Figure 4 This is a schematic diagram of the structure of an electronic device according to an embodiment of this application. Detailed Implementation

[0044] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0045] The impedance network modeling method and apparatus for AC / DC hybrid systems according to embodiments of this application are described below with reference to the accompanying drawings. Addressing the issues raised in the background section regarding existing modeling methods, which are complex and difficult to apply to large-scale practical systems, have limited applicability, and cannot accurately model large-scale complex AC / DC hybrid systems, increasing the complexity of modeling calculations, reducing the reliability of the constructed system model, and resulting in insufficient versatility and comprehensiveness, this application provides an impedance network modeling method for AC / DC hybrid systems. This method can establish impedance models for each power device in the AC / DC hybrid system. Based on the impedance models of each power device, it establishes the admittance moments of AC network nodes excluding the converter. Based on the node admittance matrices, it establishes the AC system admittance matrix including the converter, and establishes a multi-port model of the DC network. Combining the AC system admittance matrix including the converter and the multi-port model of the DC network, it obtains the impedance network model of the AC / DC hybrid system. This method is applicable to large-scale practical system modeling, facilitates oscillation mechanism analysis, enhances the versatility and comprehensiveness of the modeling method, and makes the modeling results more reliable. This solves the problems in related technologies, such as the complexity of existing modeling methods, their difficulty in applying them to large-scale real-world system modeling, their limited applicability, their inability to accurately model large-scale complex AC / DC hybrid systems, their increased complexity of modeling calculations, their reduced reliability of the constructed system models, and their lack of universality and comprehensiveness in modeling methods.

[0046] Specifically, Figure 1 This is a flowchart illustrating an impedance network modeling method for an AC / DC hybrid system provided in an embodiment of this application.

[0047] like Figure 1 As shown, the impedance network modeling method for this AC / DC hybrid system includes the following steps:

[0048] In step S101, impedance models of each power device in the AC / DC hybrid system are established.

[0049] It is understood that the embodiments of this application can establish impedance models of each power device in an AC / DC hybrid system. For example, impedance models of each power device in an AC / DC hybrid system can be established through impedance external characteristic identification methods or state-space equation modeling methods, thereby obtaining relevant information about the impedance influence of each power device in the power system. Furthermore, the admittance matrix of AC network nodes other than the converter in the following steps can be constructed to provide basic information for the network model of the AC / DC hybrid system, while simplifying the process of establishing the device impedance model.

[0050] In step S102, based on the impedance model of each power device in the AC / DC hybrid system, the admittance matrix of the AC network nodes excluding the converter is established.

[0051] It is understood that, based on the impedance model of each power device in the AC / DC hybrid system in the above steps, the AC network node admittance matrix excluding the converter can be established, and then the AC system admittance matrix including the converter in the following steps can be established. This enables the relationship between system node voltage and current, and oscillation mechanism analysis can be performed at the physical level, thereby improving the depth of oscillation mechanism analysis in the modeling process.

[0052] Optionally, in one embodiment of this application, the formula for establishing the admittance matrix of AC network nodes other than the converter is:

[0053]

[0054] in, This represents the admittance matrix of the AC network nodes excluding the converter. This is a diagonal matrix, with the diagonal elements representing the admittance models of each AC device. This is the node-branch correlation matrix.

[0055] In practical implementation, assuming an AC / DC hybrid system has n AC nodes and m converters, the impedance / admittance model for AC equipment other than the converters is a two-dimensional frequency-coupled model. Based on the model and system topology, a 2n-dimensional node admittance matrix is ​​constructed.

[0056]

[0057] in, Here is the nodal admittance matrix. This is a diagonal matrix, with the diagonal elements representing the admittance models of each AC device. For the node-branch association matrix, we have

[0058]

[0059] Where I2 is a two-dimensional identity matrix. The Kronecker product can be obtained from the system topology, which yields the node-branch incidence matrix.

[0060] As can be seen from the above equation, the target matrix can establish the relationship between the system node voltage and current, thus broadening the physical meaning of oscillation mechanism analysis in the modeling process.

[0061] In step S103, an AC system admittance matrix including the converter is established based on the node admittance matrix.

[0062] It is understood that the embodiments of this application can establish the AC system admittance matrix including the converter based on the node admittance matrix in the above steps, and obtain the accurate admittance matrix of the circuit system, thereby providing the necessary construction conditions for the impedance network model of the AC-DC hybrid system in the following steps.

[0063] Optionally, in one embodiment of this application, the formula for establishing the admittance matrix of the AC system including the converter is:

[0064]

[0065] in, The AC system admittance matrix of the converter. Y is a 2n+m dimensional matrix extended by the admittance matrix of the AC network nodes excluding the converter. j The extended 2n+m dimensional matrix is ​​obtained from the three-port admittance model, where j is the converter device number in the AC / DC hybrid system, n is the number of AC nodes in the AC / DC hybrid system, and m is the number of converters in the AC / DC hybrid system; The block is denoted as

[0066]

[0067] Among them, Y 11 Y is a 2n-dimensional matrix. 22 Let Y be an m-dimensional matrix. 12 Y is a 2n×m dimensional matrix. 21 It is an m×2n dimensional matrix, where n is the number of AC nodes in the AC-DC hybrid system and m is the number of converters in the AC-DC hybrid system.

[0068] In actual implementation, the admittance matrix of the AC network nodes excluding the converter is first calculated as a 2n-dimensional matrix. By adding zero elements, it can be expanded into a 2n+m dimensional matrix, which has

[0069]

[0070] in, This is a 2n+m dimensional matrix extended by the admittance matrix of AC network nodes excluding the converter. Let n be the admittance matrix of the AC network nodes excluding the converters, where n is the number of AC nodes in the AC / DC hybrid system and m is the number of converters in the AC / DC hybrid system.

[0071] For the j-th converter device connected to the AC node numbered i, its three-port admittance model is expanded into a 2n+m dimensional matrix by adding a zero element, resulting in:

[0072]

[0073] Among them, Y j The matrix is ​​a 2n+m dimension matrix obtained by extending the three-port admittance model, where j is the converter equipment number in the AC / DC hybrid system, i is the AC node access number in the AC / DC hybrid system, n is the number of AC nodes in the AC / DC hybrid system, and m is the number of converters in the AC / DC hybrid system.

[0074] The admittance matrix of an AC system including a converter is It can be done in Add the aforementioned admittance matrices of all converters to the above,

[0075]

[0076] in, The AC system admittance matrix of the converter. Y is a 2n+m dimensional matrix extended by the admittance matrix of the AC network nodes excluding the converter. j The matrix is ​​a 2n+m dimension matrix obtained by extending the three-port admittance model, where j is the converter equipment number in the AC / DC hybrid system, n is the number of AC nodes in the AC / DC hybrid system, and m is the number of converters in the AC / DC hybrid system.

[0077] in, It can also be divided into blocks

[0078]

[0079] For ease of representation, where Y 11 Y is a 2n-dimensional matrix. 22 Let n be an m-dimensional matrix, where n is the number of AC nodes in the AC / DC hybrid system and m is the number of converters in the AC / DC hybrid system.

[0080] As can be seen from the above formula, the matrix calculation involved in the AC system admittance matrix including the converter is of low complexity and easy to calculate, thereby improving the applicability of modeling large-scale practical systems.

[0081] In step S104, a multi-port model of the DC network is established.

[0082] It is understood that the embodiments of this application can establish a multi-port model of a DC network. By establishing the multi-port model of the DC network, the necessary construction conditions are provided for the impedance network model of the AC / DC hybrid system in the following steps.

[0083] Optionally, in one embodiment of this application, the multiport impedance model of the DC network is Y. dc It is an m-dimensional matrix, Y dc It can be obtained through short-circuit coefficient measurement or node voltage method.

[0084] It is understood that in the embodiments of this application, the DC network can be represented as an m-port model, and can be represented by short-circuit parameters as an m-dimensional matrix Y. dc , where Y dc The parameters can be obtained using the nodal voltage method or short-circuit parameter measurement method to establish a multi-port model of the DC network.

[0085] In step S105, the impedance network model of the AC-DC hybrid system is obtained by combining the AC system admittance matrix including the converter and the multi-port model of the DC network.

[0086] It is understood that the embodiments of this application can combine the AC system admittance matrix including the converter in the above steps and the multi-port model of the DC network in the above steps to obtain the impedance network model of the AC-DC hybrid system, thereby further analyzing the oscillation stability problem of the AC-DC hybrid system to ensure the safe and stable operation of the power system.

[0087] Optionally, in one embodiment of this application, the formula for establishing the impedance network model of the AC / DC hybrid system is:

[0088]

[0089] Among them, Y ext For the impedance network model of the AC / DC hybrid system, Y dc Y is a multi-port m-dimensional matrix of a DC network. 11 Y is a 2n-dimensional matrix. 22 Let n be an m-dimensional matrix, where n is the number of AC nodes in the AC / DC hybrid system and m is the number of converters in the AC / DC hybrid system.

[0090] In actual implementation, the impedance network model of the AC / DC hybrid system is as follows:

[0091]

[0092] Among them, Y ext For the impedance network model of the AC / DC hybrid system, Y dc Y is a multi-port m-dimensional matrix of a DC network. 11 Y is a 2n-dimensional matrix. 22 Let n be an m-dimensional matrix, where n is the number of AC nodes in the AC / DC hybrid system and m is the number of converters in the AC / DC hybrid system.

[0093] According to the stability theory of multiple-input multiple-output (MIMO) systems, its transfer function detY ext The zeros of (s) represent the various oscillation modes of the system.

[0094] Furthermore, the impedance network model Y of the AC / DC hybrid system ext It can be transformed into an admittance matrix.

[0095] Y = Y 11 -Y 12 (Y 22 -Y dc ) -1 Y 21 ,

[0096] Where Y is the admittance matrix, Y dc Y is a multi-port m-dimensional matrix of a DC network. 11 Y is a 2n-dimensional matrix. 22 Let n be an m-dimensional matrix, where n is the number of AC nodes in the AC / DC hybrid system and m is the number of converters in the AC / DC hybrid system.

[0097] According to Schuler's theorem, the transfer functions detY(s) and detY ext The zeros of (s) are the same, and both are system oscillation modes.

[0098] As can be seen from the above equation, the impedance network model of the AC / DC hybrid system can be modeled by connecting the circuit equations to form a specific impedance model that can characterize the dynamics of the equipment, thereby obtaining an impedance network model that can characterize the overall dynamic characteristics of the system, which improves the comprehensiveness and practicality of the impedance network model of the AC / DC hybrid system.

[0099] like Figure 2 As shown below, the working content of the embodiment of this application will be described in detail with a specific example.

[0100] Step S201: Establish the impedance model of each power device in the AC / DC hybrid system.

[0101] In other words, impedance models of each power device in an AC / DC hybrid system are established using impedance external characteristic identification methods or state-space equation modeling methods.

[0102] Step S202: Establish the admittance matrix of the AC network excluding the converter.

[0103] In other words, suppose there are n AC nodes and m converters in an AC / DC hybrid system. For AC equipment other than converters, its impedance / admittance model is a two-dimensional frequency coupling model. Based on the model and system topology, a 2n-dimensional node admittance matrix is ​​constructed using the corresponding formula.

[0104] Step S203: Establish the AC network admittance matrix including the converter.

[0105] In other words, the 2n-dimensional node admittance matrix is ​​expanded into a 2n+m-dimensional matrix by adding zero elements. For the j-th converter device connected to the AC node numbered i, its three-port admittance model is expanded into a 2n+m-dimensional matrix by adding zero elements. Then, the AC system admittance matrix containing the converter is obtained from the two according to the formula.

[0106] Step S204: Establish a DC multi-port admittance model.

[0107] In other words, a DC network can be represented as an m-port model, which can be expressed as an m-dimensional matrix using short-circuit parameters, and can be obtained using the nodal voltage method or short-circuit parameter measurement method.

[0108] Step S205: Obtain the impedance network model of the AC / DC hybrid system.

[0109] In other words, an impedance network model of the AC / DC hybrid system is constructed. According to the stability theory of MIMO systems, the zeros of its transfer function are the oscillation modes of the system.

[0110] The impedance network modeling method for AC / DC hybrid systems proposed in this application can establish impedance models for each power device in the AC / DC hybrid system. Based on the impedance models of each power device in the AC / DC hybrid system, the admittance moments of AC network nodes (excluding converters) are established. Based on the node admittance matrices, an AC system admittance matrix including the converters is established. A multi-port model of the DC network is established. Combining the AC system admittance matrix including the converters and the multi-port model of the DC network, the impedance network model of the AC / DC hybrid system is obtained. This method is applicable to large-scale practical system modeling and is beneficial for oscillation mechanism analysis, enhancing the versatility and comprehensiveness of the modeling method and making the modeling results more reliable. Therefore, it solves the problems in related technologies, such as the complexity of existing modeling methods, their difficulty in applying them to large-scale practical system modeling, their limited applicability, their inability to accurately model large-scale complex AC / DC hybrid systems, the increased complexity of modeling calculations, the reduced reliability of the constructed system model, and the lack of versatility and comprehensiveness of the modeling methods.

[0111] Next, with reference to the accompanying drawings, an impedance network modeling apparatus for an AC / DC hybrid system according to an embodiment of this application is described.

[0112] Figure 3 This is a block diagram of the impedance network modeling device for an AC / DC hybrid system according to an embodiment of this application.

[0113] like Figure 3 As shown, the impedance network modeling device 10 of the AC / DC hybrid system includes: a first building module 100, a second building module 200, a third building module 300, a fourth building module 400, and a modeling module 500.

[0114] The first construction module 100 is used to establish the impedance model of each power device in the AC / DC hybrid system.

[0115] The second construction module 200 is used to establish the admittance matrix of AC network nodes, excluding converters, based on the impedance model of each power device in the AC / DC hybrid system.

[0116] The third construction module 300 is used to build an AC system admittance matrix including the converter based on the node admittance matrix.

[0117] The fourth building module 400 is used to build a multi-port model of the DC network.

[0118] Modeling module 500 is used to combine the admittance matrix of the AC system containing the converter and the multi-port model of the DC network to obtain the impedance network model of the AC-DC hybrid system.

[0119] Optionally, in one embodiment of this application, the formula for establishing the admittance matrix of AC network nodes other than the converter is:

[0120]

[0121] in, This represents the admittance matrix of the AC network nodes excluding the converter. This is a diagonal matrix, with the diagonal elements representing the admittance models of each AC device. This is the node-branch correlation matrix.

[0122] Optionally, in one embodiment of this application, the formula for establishing the admittance matrix of the AC system including the converter is:

[0123]

[0124] Among them, among them, The AC system admittance matrix of the converter. Y is a 2n+m dimensional matrix extended by the admittance matrix of the AC network nodes excluding the converter. j The matrix is ​​a 2n+m dimension matrix obtained by extending the three-port admittance model, where j is the converter device number in the AC / DC hybrid system, n is the number of AC nodes in the AC / DC hybrid system, and m is the number of converters in the AC / DC hybrid system.

[0125] Will The block is denoted as

[0126]

[0127] Among them, Y 11 Y is a 2n-dimensional matrix. 22 Let Y be an m-dimensional matrix.12 Y is a 2n×m dimensional matrix. 21 It is an m×2n dimensional matrix, where n is the number of AC nodes in the AC-DC hybrid system and m is the number of converters in the AC-DC hybrid system.

[0128] Optionally, in one embodiment of this application, the multiport impedance model of the DC network is Y. dc It is an m-dimensional matrix, Y dc It can be obtained through short-circuit coefficient measurement or node voltage method.

[0129] Optionally, in one embodiment of this application, the formula for establishing the impedance network model of the AC / DC hybrid system is:

[0130]

[0131] Among them, Y ext For the impedance network model of the AC / DC hybrid system, Y dc Y is a multi-port m-dimensional matrix of a DC network. 11 Y is a 2n-dimensional matrix. 22 Let n be an m-dimensional matrix, where n is the number of AC nodes in the AC / DC hybrid system and m is the number of converters in the AC / DC hybrid system.

[0132] It should be noted that the explanation of the aforementioned embodiment of the impedance network modeling method for AC / DC hybrid systems also applies to the impedance network modeling device for AC / DC hybrid systems in this embodiment, and will not be repeated here.

[0133] The impedance network modeling device for AC / DC hybrid systems proposed in this application can establish impedance models for each power device in the AC / DC hybrid system. Based on the impedance models of each power device in the AC / DC hybrid system, the admittance moments of AC network nodes (excluding converters) are established. Based on the node admittance matrices, an AC system admittance matrix including the converters is established. A multi-port model of the DC network is established. Combining the AC system admittance matrix including the converters and the multi-port model of the DC network, the impedance network model of the AC / DC hybrid system is obtained. This model is applicable to large-scale practical system modeling and is beneficial for oscillation mechanism analysis, enhancing the versatility and comprehensiveness of the modeling method and making the modeling results more reliable. Therefore, it solves the problems in related technologies, such as the complexity of existing modeling methods, their difficulty in applying them to large-scale practical system modeling, their limited applicability, their inability to accurately model large-scale complex AC / DC hybrid systems, the increased complexity of modeling calculations, the reduced reliability of the constructed system model, and the lack of versatility and comprehensiveness of the modeling methods.

[0134] Figure 4 A schematic diagram of the structure of an electronic device provided in an embodiment of this application. The electronic device may include:

[0135] The memory 401, the processor 402, and the computer program stored on the memory 401 and capable of running on the processor 402.

[0136] When the processor 402 executes the program, it implements the impedance network modeling method for the AC / DC hybrid system provided in the above embodiments.

[0137] Furthermore, electronic devices also include:

[0138] Communication interface 403 is used for communication between memory 401 and processor 402.

[0139] The memory 401 is used to store computer programs that can run on the processor 402.

[0140] The memory 401 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk storage device.

[0141] If the memory 401, processor 402, and communication interface 403 are implemented independently, then the communication interface 403, memory 401, and processor 402 can be interconnected via a bus to complete communication between them. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of representation, Figure 4 The bus is represented by a single thick line, but this does not mean that there is only one bus or one type of bus.

[0142] Optionally, in a specific implementation, if the memory 401, processor 402, and communication interface 403 are integrated on a single chip, then the memory 401, processor 402, and communication interface 403 can communicate with each other through an internal interface.

[0143] Processor 402 may be a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits configured to implement the embodiments of this application.

[0144] This embodiment also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the impedance network modeling method for the AC / DC hybrid system described above.

[0145] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0146] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0147] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or N executable instructions for implementing custom logic functions or processes, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the functions involved, as should be understood by those skilled in the art to which embodiments of this application pertain.

[0148] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and programmable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0149] It should be understood that the various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0150] Those skilled in the art will understand that all or part of the steps of the methods described in the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it includes one or a combination of the steps of the method embodiments.

[0151] Furthermore, the functional units in the various embodiments of this application can be integrated into a processing module, or each unit can exist physically separately, or two or more units can be integrated into a module. The integrated module can be implemented in hardware or as a software functional module. If the integrated module is implemented as a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium.

[0152] The storage medium mentioned above can be a read-only memory, a disk, or an optical disk, etc. Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. An impedance network modeling method of an AC-DC hybrid system, characterized in that, The method comprises the following steps: establishing impedance models of each power device in the AC-DC hybrid system; establishing a node admittance matrix of an AC network excluding the converter according to the impedance models of each power device in the AC-DC hybrid system; establishing an AC system admittance matrix including the converter according to the node admittance matrix; establishing a multi-port model of a DC network; and obtaining an impedance network model of the AC-DC hybrid system by combining the AC system admittance matrix including the converter and the multi-port model of the DC network; wherein the establishment formula of the impedance network model of the AC-DC hybrid system is: , wherein, is an impedance network model of the AC-DC hybrid system, is a multi-port impedance model of the DC network, is an m-dimensional matrix, is a 2n-dimensional matrix, is an m-dimensional matrix, n is the number of AC nodes in the AC-DC hybrid system, m is the number of converters in the AC-DC hybrid system, is a 2n x m-dimensional matrix, is an m x 2n-dimensional matrix; the establishment formula of the AC system admittance matrix including the converter is: , wherein, Yac is the admittance matrix of the AC system of the converter, Yext is a 2n+m dimensional matrix extended from the admittance matrix of the AC network nodes except the converter, Yext is a 2n+m dimensional matrix extended from the admittance matrix of the AC network nodes except the converter, will be described below. The block is denoted as: 。 2. The method of claim 1, wherein, the establishment formula of the node admittance matrix of the AC network excluding the converter is: , wherein, Y is the admittance matrix of the AC network nodes excluding the converter, Y is the admittance matrix of the AC network nodes excluding the converter, Y is the admittance matrix of the AC network nodes excluding the converter, 3. The method of claim 1, wherein, The Obtained by short circuit coefficient measurement method or node voltage method.

4. An impedance network modeling apparatus for an AC-DC hybrid system, characterized by comprising: The method comprises the following steps: a first construction module for establishing impedance models of each power device in the AC-DC hybrid system; a second construction module for establishing a node admittance matrix of an AC network excluding the converter according to the impedance models of each power device in the AC-DC hybrid system; a third construction module for establishing an AC system admittance matrix including the converter according to the node admittance matrix; a fourth construction module for establishing a multi-port model of a DC network; and a modeling module for obtaining an impedance network model of the AC-DC hybrid system by combining the AC system admittance matrix including the converter and the multi-port model of the DC network; wherein the establishment formula of the impedance network model of the AC-DC hybrid system is: , wherein, is an impedance network model of the AC-DC hybrid system, is a multi-port impedance model of the DC network, and is an m-dimensional matrix, is a 2n-dimensional matrix, is an m-dimensional matrix, n is the number of AC nodes in the AC-DC hybrid system, and m is the number of converters in the AC-DC hybrid system, is a 2n x m-dimensional matrix, is an m x 2n-dimensional matrix. the establishment formula of the AC system admittance matrix including the converter is: , wherein, Yac is the AC system admittance matrix of the converter, Yext is a 2n+m dimensional matrix extended from the admittance matrix of the AC network nodes other than the converter, Yext is a 2n+m dimensional matrix extended from the admittance matrix of the AC network nodes other than the converter, will be described below. The block is denoted as: 。 5. The apparatus of claim 4, wherein, the establishment formula of the node admittance matrix of the AC network excluding the converter is: , wherein, Y is the admittance matrix of the AC network nodes excluding the converter, is a diagonal matrix with diagonal elements being the admittance models of the AC devices, is the node-branch incidence matrix.

6. The apparatus of claim 4, wherein, The Obtained by short circuit coefficient measurement method or node voltage method.

7. An electronic device, comprising: The method comprises the following steps: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the impedance network modeling method of the AC-DC hybrid system according to any one of claims 1-3.

8. A computer-readable storage medium having stored thereon a computer program, characterized in that, The program is executed by the processor to implement the impedance network modeling method of the AC-DC hybrid system according to any one of claims 1-3.

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