Frequency domain impedance network construction method of grid-connected system

Abstract

The invention discloses a frequency domain impedance network construction method of a grid-connected system, which is used for solving the problem that stability analysis cannot be met when large-scale new energy is accessed to a network due to the fact that a currently adopted new energy station equivalence method cannot realize construction of a large-scale wind power plant frequency domain network model. Obtaining the network topology of the grid-connected system and the modular representation of each network element; constructing a branch admittance matrix of the grid-connected system according to the network topology; according to a preset frequency domain network construction principle, the modular representations of all the network elements are interconnected, and an alternating current and direct current incidence matrix is constructed; and constructing a frequency domain impedance network of the grid-connected system according to the branch admittance matrix and the AC / DC incidence matrix. Therefore, based on the network topology of the grid-connected system and the modular representation of the network elements, the construction of the frequency-domain network model of the large-scale wind power plant required in the actual engineering can be realized by combining the matrix correlation derivation operation, and the constructed frequency-domain network model can accurately analyze the stability of the large-scale new energy network access.

Description

Technical Field

[0001] The present invention relates to the field of new energy grid-connected technology, and in particular to a frequency domain impedance network construction method for a grid-connected system, a frequency domain impedance network construction device for a grid-connected system, an electronic device and a storage medium. Background Art

[0002] With the increasing scarcity of energy resources and the gradual deterioration of the climate environment, renewable energy generation technology represented by wind and solar power has developed rapidly due to its good economic prospects. However, with the continuous expansion of the scale of new energy power generation, its grid connection stability problem has become increasingly prominent, thus posing a huge challenge to the safe and stable operation of the power system.

[0003] Impedance analysis is widely used in the evaluation of the stability of renewable energy grid connection because it can compactly characterize the high-order and broadband characteristics of the target system in the form of transfer functions, and has the advantages of strong scalability and easy measurement in circuits. The establishment of accurate impedance models for renewable energy units, stations, and clusters is a prerequisite for conducting large-scale renewable energy access stability analysis.

[0004] At present, the aggregate impedance modeling is mainly based on dynamic equivalence. The core is to dynamically aggregate the new energy stations or clusters. After obtaining the single-machine aggregation model, the mainstream impedance analysis modeling method can be applied to establish an aggregate impedance model that can characterize the characteristics of the station / cluster port. Taking wind farms as an example, with the construction of large-scale, centralized onshore wind farms in my country, and the widespread application of doubly-fed variable-speed wind turbines and permanent magnet direct-drive full-power units, the research on equivalent models of variable-speed wind farms has gradually become a hot topic.

[0005] Most of the current equivalent methods for new energy stations are based on the electrical characteristics of the station itself, and the parameters of the units in the station are aggregated. The impact of the access of new energy stations on the safety and stability of the system is not fully considered. At the same time, the topological structure of the new energy station used to study the equivalent is not in line with the actual engineering. The scale of the equivalent calculation example is limited to a few to a dozen wind turbines, which is quite different from the large-scale wind farm equivalent model required in actual engineering, and cannot meet the stability analysis of large-scale new energy when it is connected to the grid. Summary of the invention

[0006] The present invention provides a frequency domain impedance network construction method for a grid-connected system, a frequency domain impedance network construction device for a grid-connected system, an electronic device and a storage medium, which are used to solve or partially solve the problem that the current new energy station equivalent method cannot realize the construction of a large-scale wind farm frequency domain network model, resulting in the inability to meet the stability analysis when large-scale new energy is connected to the grid.

[0007] The present invention provides a method for constructing a frequency domain impedance network of a grid-connected system, the method comprising:

[0008] Obtaining a network topology of the grid-connected system and a modular representation of each network element;

[0009] Constructing a branch admittance matrix of the grid-connected system according to the network topology;

[0010] According to a preset frequency domain network construction principle, the modular representations of the network elements are interconnected to construct an AC / DC correlation matrix;

[0011] A frequency domain impedance network of the grid-connected system is constructed according to the branch admittance matrix and the AC / DC correlation matrix.

[0012] Optionally, the AC / DC association matrix is ​​a branch-node association matrix; the grid-connected system includes a plurality of AC subsystems and a plurality of DC subsystems; and according to a preset frequency domain network construction principle, the modular representations of the respective network elements are interconnected to construct an AC / DC association matrix, including:

[0013] Selecting at least one reference node for each of the AC subsystems and the DC subsystems;

[0014] According to the preset first frequency domain network construction principle and the relationship between branches and nodes in the network topology, interconnection is performed based on the modular representation of each of the network elements to construct a branch-node association matrix.

[0015] Optionally, constructing a frequency domain impedance network of the grid-connected system according to the branch admittance matrix and the AC / DC correlation matrix includes:

[0016] According to the branch admittance matrix and the branch-node association matrix, a node admittance matrix is ​​obtained by matrix calculation as a frequency domain impedance network of the grid-connected system.

[0017] Optionally, the AC / DC association matrix is ​​a branch-loop association matrix; the grid-connected system includes a plurality of AC subsystems and a plurality of DC subsystems; and according to a preset frequency domain network construction principle, the modular representations of the respective network elements are interconnected to construct an AC / DC association matrix, including:

[0018] Selecting at least one reference node for each of the AC subsystems and the DC subsystems;

[0019] According to the preset second frequency domain network construction principle and the relationship between branches and nodes in the network topology, interconnection is performed based on the modular representation of each of the network elements to construct a branch-loop association matrix.

[0020] Optionally, constructing a frequency domain impedance network of the grid-connected system according to the branch admittance matrix and the AC / DC correlation matrix includes:

[0021] Inverting the branch admittance matrix to obtain a branch impedance matrix;

[0022] According to the branch impedance matrix and the branch-loop association matrix, a loop impedance matrix is ​​obtained by matrix calculation as a frequency domain impedance network of the grid-connected system.

[0023] Optionally, the types of modular representation of the network element include modular representation of converter element, modular representation of AC element and modular representation of DC element.

[0024] Optionally, the method further comprises:

[0025] The network topology of the grid-connected system is constructed according to the modular representations of each converter element, the modular representations of each AC element, and the modular representations of each DC element.

[0026] The present invention also provides a frequency domain impedance network construction device for a grid-connected system, comprising:

[0027] A modular representation acquisition module, used to acquire the network topology of the grid-connected system and the modular representation of each network element;

[0028] A branch admittance matrix construction module, used to construct a branch admittance matrix of the grid-connected system according to the network topology;

[0029] An AC / DC correlation matrix construction module is used to interconnect the modular representations of the network elements according to a preset frequency domain network construction principle to construct an AC / DC correlation matrix;

[0030] The frequency domain impedance network construction module is used to construct the frequency domain impedance network of the grid-connected system according to the branch admittance matrix and the AC / DC correlation matrix.

[0031] The present invention also provides an electronic device, the device comprising a processor and a memory:

[0032] The memory is used to store program code and transmit the program code to the processor;

[0033] The processor is used to execute the frequency domain impedance network construction method of the grid-connected system as described in any one of the above items according to the instructions in the program code.

[0034] The present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium is used to store program codes, and the program codes are used to execute the frequency domain impedance network construction method of the grid-connected system as described in any one of the above items.

[0035] It can be seen from the above technical solutions that the present invention has the following advantages:

[0036] A method for constructing a frequency domain impedance network of a grid-connected system is provided. First, the network topology of the grid-connected system and the modular representation of each network element are obtained; then, the branch admittance matrix of the grid-connected system is constructed according to the network topology; then, according to the preset frequency domain network construction principle, the modular representations of each network element are interconnected to construct an AC / DC correlation matrix; finally, according to the branch admittance matrix and the AC / DC correlation matrix, a frequency domain impedance network of the grid-connected system is constructed. Thus, based on the network topology of the grid-connected system and the modular representation of the network elements, combined with the matrix correlation derivation operation, the construction of the frequency domain network model of the large-scale wind farm required in the actual project can be realized. Based on the frequency domain impedance network, when the system changes subsequently, it is only necessary to superimpose or eliminate the modular representation matrix of the corresponding network element at the changed node according to the topology change, so as to obtain a new system node matrix, thereby realizing the stability analysis of large-scale new energy access to the grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 A flowchart of the steps of a method for constructing a frequency domain impedance network of a grid-connected system;

[0039] Figure 2 It is a schematic diagram of a three-port admittance model of a converter in a local dq coordinate system;

[0040] Figure 3 A system network topology diagram in Example 1;

[0041] Figure 4 A system network topology diagram in Example 2;

[0042] Figure 5 is a directed graph in Example 2;

[0043] Figure 6 is a system equivalent circuit diagram under Example 2;

[0044] Figure 7 A system network topology diagram in Example 3;

[0045] Figure 8is a directed graph in Example 3;

[0046] Fig. 9 is a system equivalent circuit diagram under Example 3;

[0047] Fig.10 A structural block diagram of a frequency domain impedance network construction device for a grid-connected system. DETAILED DESCRIPTION

[0048] The embodiments of the present invention provide a frequency domain impedance network construction method for a grid-connected system, a frequency domain impedance network construction device for a grid-connected system, an electronic device and a storage medium, which are used to solve or partially solve the problem that the current new energy station equivalent method cannot realize the construction of a large-scale wind farm frequency domain network model, resulting in the inability to meet the stability analysis when large-scale new energy is connected to the grid.

[0049] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] As an example, most of the current equivalent methods for new energy stations are based on the electrical characteristics of the station itself, and the parameters of the units in the station are aggregated. The impact of the access of new energy stations on the safety and stability of the system is not fully considered. At the same time, the topological structure of the new energy station used to study the equivalent is not in line with the actual engineering. The scale of the equivalent calculation example is limited to a few to a dozen wind turbines, which is quite different from the large-scale wind farm equivalent model required in actual engineering, and cannot meet the stability analysis when large-scale new energy is connected to the grid.

[0051] Therefore, one of the core inventive points of the embodiment of the present invention is to provide a method for constructing a frequency domain impedance network of a grid-connected system. By obtaining the modular representation of each network element in the grid-connected system, and according to the pre-set frequency domain network construction principle, the modular representation of each network element is interconnected according to the network topology of the system, and an AC / DC correlation matrix is ​​constructed to further construct the frequency domain impedance network of the system, so as to realize the construction of the frequency domain network model of the large-scale wind farm required in the actual project. Based on the frequency domain impedance network, when the system changes subsequently, it is only necessary to superimpose or eliminate the modular representation matrix of the corresponding network element at the changed node according to the topological change, so as to obtain a new system node matrix, so as to realize the stability analysis of large-scale new energy access to the grid.

[0052] Reference Figure 1 , shows a flowchart of the steps of a method for constructing a frequency domain impedance network of a grid-connected system provided by an embodiment of the present invention, which may specifically include the following steps:

[0053] Step 101, obtaining the network topology of the grid-connected system and the modular representation of each network element;

[0054] The grid-connected system mentioned in the embodiment of the present invention is a wind-solar power grid-connected system, which may include multiple AC subsystems and multiple DC subsystems. The types of modular representations of network elements may include modular representations of converter elements, modular representations of AC elements, and modular representations of DC elements. The network topology of the wind-solar power grid-connected system may be constructed based on the modular representations of each converter element, each AC element, and each DC element.

[0055] Step 102, constructing a branch admittance matrix of the grid-connected system according to the network topology;

[0056] In this step, the branch admittance matrix of the grid-connected system is constructed according to the network topology. .

[0057] Step 103, interconnecting the modular representations of the network elements according to a preset frequency domain network construction principle to construct an AC / DC correlation matrix;

[0058] In an optional embodiment, the AC / DC association matrix may be a branch-node association matrix. Then, according to the preset frequency domain network construction principle, the modular representations of each network element are interconnected to construct the AC / DC association matrix, which may be specifically as follows: first, at least one reference node is selected for each AC subsystem and DC subsystem within the wind-solar power grid-connected system; then, according to the preset first frequency domain network construction principle and the relationship between branches and nodes in the network topology, the modular representations of each network element (converter element, DC element, AC element) are interconnected to construct the branch-node association matrix.

[0059] Among them, the first frequency domain network construction principle is:

[0060] (1)

[0061] in, is the branch-node association matrix The elements in .

[0062] Based on the modular representation matrix of the converter components, DC components and AC components obtained in the previous steps, the matrix elements and corresponding topological relationships corresponding to the modular representation matrix can be extracted to obtain the above frequency domain network construction principle. . Thus, for a single converter, DC component and AC component, the above Consistent with the established modular matrix elements, it can be further used for the construction of association matrices of multiple converters, DC elements, and AC elements.

[0063] In another optional embodiment, the AC / DC association matrix can also be a branch-loop association matrix. Then, according to the preset frequency domain network construction principle, the modular representations of each network element are interconnected to construct the AC / DC association matrix, which can be specifically as follows: first, at least one reference node is selected for each AC subsystem and DC subsystem within the wind-solar power grid-connected system; then, according to the preset second frequency domain network construction principle and the relationship between branches and nodes in the network topology, the modular representations of each network element are interconnected to construct the branch-loop association matrix.

[0064] Among them, the second frequency domain network construction principle is:

[0065] (2)

[0066] in, is the branch-loop incidence matrix The elements in .

[0067] Step 104: construct a frequency domain impedance network of the grid-connected system according to the branch admittance matrix and the AC / DC correlation matrix.

[0068] When the AC / DC correlation matrix is ​​a branch-node correlation matrix, the frequency domain impedance network of the grid-connected system is constructed according to the branch admittance matrix and the AC / DC correlation matrix. Specifically, it can be: and branch-node association matrix , the node admittance matrix is ​​obtained by matrix calculation as shown in equation (3) , as the frequency domain impedance network of the grid-connected system:

[0069] (3)

[0070] When the AC / DC correlation matrix is ​​a branch-loop correlation matrix, the frequency domain impedance network of the grid-connected system is constructed according to the branch admittance matrix and the AC / DC correlation matrix, which can be specifically:

[0071] First, take the inverse of the branch admittance matrix , and obtain the branch impedance matrix ; Then according to the branch impedance matrix and branch-loop association matrix , the loop impedance matrix is ​​obtained by matrix calculation as shown in equation (4) below: , as the frequency domain impedance network of the grid-connected system:

[0072] (4)

[0073] In the formula, Represents the branch impedance matrix.

[0074] In an embodiment of the present invention, a method for constructing a frequency domain impedance network of a grid-connected system is provided. By obtaining the modular representation of each network element in the grid-connected system, the modular representation of each network element is interconnected according to the network topology of the system according to the pre-set frequency domain network construction principle, and an AC / DC correlation matrix is ​​constructed to further construct the frequency domain impedance network of the system, so as to realize the construction of a frequency domain network model of a large-scale wind farm required in an actual project. Based on the frequency domain impedance network, when the system changes subsequently, it is only necessary to superimpose or eliminate the modular representation matrix of the corresponding network element at the changed node according to the topological change, so as to obtain a new system node matrix, so as to realize the stability analysis of large-scale new energy access to the grid.

[0075] In some embodiments, the modular representation of the network elements mentioned in the above embodiments may be obtained by executing the following process:

[0076] Take an AC subsystem in a wind and solar power grid-connected system as an example. Figure 2 A schematic diagram of a converter three-port admittance model in a local dq coordinate system is shown. The converter three-port admittance model is established based on the local dq coordinate system, which needs to be rotated to the global reference system before the subsequent analysis process is carried out.

[0077] Any converter in the AC subsystem is selected as the global dq reference system (as the reference converter), and the offset phase angle of the converter currently being analyzed relative to the reference converter is extracted according to the power flow calculation results.

[0078] After determining the offset phase angle, the rotation matrix of the current converter can be constructed according to the offset phase angle. The offset phase angle relative to the reference converter is , the rotation matrix can be constructed:

[0079] (5)

[0080] Based on the rotation matrix shown in equation (5), the converter can be rotated as follows: Correct the AC voltage and current:

[0081] (6)

[0082] In the formula, the superscript Represents the variables in the global dq coordinate system; represents the AC current before correction; represents the corrected AC current (corrected current); Indicates the AC voltage before correction; Indicates the corrected AC voltage (corrected voltage).

[0083] Substituting the corrected AC voltage and AC current into the three-port admittance model of the converter in the local dq reference system, the three-port admittance model of the converter in the global reference system can be obtained as follows:

[0084] (7)

[0085] in, , Respectively represents the converter DC current and DC voltage; , All are converters The AC and DC coupling terms corresponding to the controlled current source characterization; Indicates the converter The DC side admittance; Indicates the converter The AC side admittance of .

[0086] From the above equation, it can be seen that the impedance terms related to AC dynamics in the converter need to be rotated, while the DC terms do not need to be rotated. This is because power balancing eliminates the impact of the phase angle offset on the DC side.

[0087] Analogous to passive mutual inductance components, in actual calculations, the AC and DC coupling terms represented by the controlled current source need to be (Right now )and (Right now ) is expressed as the mutual inductance between the AC branch and the DC branch.

[0088] Based on the equivalent circuit of the converter three-port admittance model in the global reference system, the node voltage in the global reference system is used , , , Indicates branch voltage , :

[0089] (8)

[0090] In the formula, is the second-order identity matrix; is the AC and DC correlation matrix, that is, the branch-node correlation matrix.

[0091] At the same time, the node current in the global reference system is used , , , Indicates branch current , :

[0092] (9)

[0093] Substituting the matrix of equation (8) and the matrix of equation (9) into equation (7), the relationship between the node voltage and the node current can be obtained as follows:

[0094] (10)

[0095] Expanding equation (10), the modular representation of the converter components can be obtained as shown in equation (11):

[0096] (11)

[0097] In the formula, Used for branch-node expansion of AC terms and coupling terms; Used for branch-node expansion of DC terms; , , , All are nodes; is the DC side admittance; is the AC port admittance after global-local reference frame rotation; is the DC side to AC side coupling admittance element after the global-local reference system rotation; is the AC side to DC side coupling admittance element after the global-local reference frame rotation.

[0098] The modular characterization of converter components refers to the process of decomposing the various functional components or subsystems in the converter into independent and interchangeable modules, and performing standardized description and evaluation of these modules.

[0099] In addition, the AC and DC sides of the converter may be grounded (reference node). In this case, when the AC side and / or the DC side of the converter is grounded, the grounding boundary condition can be substituted into equation (10) to perform matrix row and column addition and subtraction operations to obtain a simplified converter component modular representation, so as to simplify the converter component modular representation of equation (11).

[0100] Specifically, AC and DC side grounding can mainly include the following three situations:

[0101] The first situation: the DC side of the converter element is not grounded, and the AC side is grounded.

[0102] For example, Figure 2 Nodes in The grounding boundary condition is: , Substituting the ground boundary condition into equation (10) and performing addition and subtraction operations on the rows and columns of the matrix, we can obtain the following equation (12):

[0103] (12)

[0104] The second situation: the DC side of the converter element is grounded, but the AC side is not grounded.

[0105] For example, Figure 2 Nodes in The grounding boundary condition is: , Substituting the ground boundary condition into equation (10) and performing matrix row and column addition and subtraction operations, we can obtain the following equation (13):

[0106] (13)

[0107] The third situation: Both the DC side and the AC side of the converter components are grounded.

[0108] For example, Figure 2 Nodes in , The grounding boundary condition is: , , , Substituting the ground boundary condition into equation (10) and performing addition and subtraction operations on the rows and columns of the matrix, we can obtain the following equation (14):

[0109] (14)

[0110] After the modular representation of the converter element is obtained, the modular representation of the AC element and the modular representation of the DC element can be derived based on the modular representation of the converter element.

[0111] Specifically, assuming that the AC branch The admittance size is According to formula (11), the modular representation of AC components can be derived as follows:

[0112] (15)

[0113] Assuming the DC branch The admittance size is According to formula (11), the modular representation of DC components can be derived as follows:

[0114] (16)

[0115] in, , For AC branch The endpoint of , For DC branch endpoint.

[0116] According to the above method, the modular characterization of each converter element, AC element and DC element in the wind-solar power grid-connected system can be obtained respectively for the construction of the frequency domain impedance network. Among them, the modular characterization of the converter element is used to characterize the three-port impedance. The modular characterization of the AC element is used to characterize the two-dimensional impedance. The modular characterization of the DC element is used to characterize the one-dimensional impedance. The modular characterization of the converter element, AC element and DC element obtained by this embodiment can be used for the network topology construction of the wind-solar power grid-connected system to accurately analyze the stability of large-scale new energy access to the grid.

[0117] In order to enable those skilled in the art to better understand the technical solution of the present invention, the embodiments of the present invention are described below through several specific examples.

[0118] Example 1:

[0119] The wind and solar power grid-connected system in this example is a simple site consisting of three nodes, five branches, and two wind turbines. Figure 3 The network topology diagram of its system.

[0120] according to Figure 3 The network topology shown can be written as the branch admittance matrix shown below :

[0121] (17)

[0122] Figure 3 The relationship between branches and nodes in the network topology shown includes: node 1 is the starting point of branch 1 and branch 2, node 2 is the starting point of branch 3 and branch 4, node 3 is the receiving point of branch 2 and branch 4 and the starting point of branch 5.

[0123] According to the frequency domain network construction principle given by formula (1), the branch-node association matrix can be obtained: for:

[0124] (18)

[0125] Then, according to the branch admittance matrix and branch-node association matrix , the node admittance matrix of the system can be calculated for:

[0126] (19)

[0127] Example 2:

[0128] The wind-solar power grid-connected system in this example is a point-to-point transmission system containing two VSC converters that interconnects two AC power grids through back-to-back transmission. Figure 4 For its system network topology diagram, Figure 5 For its directed graph, Figure 6 The equivalent circuit diagram of the system is shown in Figure 2.

[0129] according to Figure 4 The system network topology shown in the figure can be used to write the branch admittance matrix :

[0130] (20)

[0131] according to Figure 4 The relationship between branches and nodes in the network topology shown and Figure 5 According to the frequency domain network construction principle given by formula (1), the branch-node association matrix can be obtained. for:

[0132] (twenty one)

[0133] If we continue to calculate according to equation (21), the resulting node admittance matrix is ​​singular. The reason is that no reference node is selected for the DC region-A of the subsystem. Unlike the traditional pure AC system, for the AC-DC hybrid system, each AC subsystem and DC subsystem within it needs to select at least one reference node. Figure 6 As can be seen from the equivalent circuit shown, the power electronic converter separates the subsystems. In this case, it is not possible to avoid system matrix singularity by selecting only one reference node as in the traditional AC system.

[0134] Therefore, to solve the above matrix singularity problem, node 5 in DC region-A can be used as the reference node. Accordingly, the branch-node association matrix is ​​modified According to the branch admittance matrix and the modified branch-node association matrix , calculate the system's node admittance matrix As shown below:

[0135] (twenty two)

[0136] It can be seen that the matrix shown in formula (22) is reversible and non-singular.

[0137] Example 3:

[0138] The wind-solar power grid-connected system in this example is an actual wind farm grid-connected system that includes 25 double-fed wind turbines and 4 feeders. Among them, feeder 1 contains 8 nodes, feeder 2 contains 7 nodes, feeder 3 contains 10 nodes, feeder 4 contains 8 nodes, and the entire system contains 33 nodes. Figure 7 For its system network topology diagram, Figure 8 For its directed graph, Fig. 9 The equivalent circuit diagram of the system is given below.

[0139] Depend on Figure 7 and Figure 8 It can be seen that the above system can include three DC regions and four AC regions in total. Figure 7 The admittance network of the system is shown, Figure 8 Shows the directed graph of the system.

[0140] based on Figure 8 Given the definitions of voltage and current, and Fig. 9 The branch definition in can be written out as the branch admittance matrix :

[0141] (twenty three)

[0142] In the formula,

[0143] (twenty four)

[0144] based on Fig. 9 Given the branch-node relationship, the branch-node association matrix can be constructed as follows:

[0145] (25)

[0146] According to the branch admittance matrix and branch-node association matrix , the node admittance matrix of the system can be calculated :

[0147] (26)

[0148] In the formula,

[0149] (27)

[0150] (28)

[0151] Reference Fig.10, shows a structural block diagram of a frequency domain impedance network construction device for a grid-connected system provided by an embodiment of the present invention, which may specifically include:

[0152] A modular representation acquisition module 1001 is used to acquire the network topology of the grid-connected system and the modular representation of each network element;

[0153] A branch admittance matrix construction module 1002, configured to construct a branch admittance matrix of the grid-connected system according to the network topology;

[0154] The AC / DC correlation matrix construction module 1003 is used to interconnect the modular representations of the network elements according to the preset frequency domain network construction principle to construct the AC / DC correlation matrix;

[0155] The frequency domain impedance network construction module 1004 is used to construct the frequency domain impedance network of the grid-connected system according to the branch admittance matrix and the AC / DC correlation matrix.

[0156] In an optional embodiment, the AC / DC correlation matrix is ​​a branch-node correlation matrix; the grid-connected system includes a plurality of AC subsystems and a plurality of DC subsystems; the AC / DC correlation matrix construction module 1003 is specifically used for:

[0157] Selecting at least one reference node for each of the AC subsystems and the DC subsystems;

[0158] According to the preset first frequency domain network construction principle and the relationship between branches and nodes in the network topology, interconnection is performed based on the modular representation of each of the network elements to construct a branch-node association matrix.

[0159] In an optional embodiment, the frequency domain impedance network construction module 1004 is specifically used for:

[0160] According to the branch admittance matrix and the branch-node association matrix, a node admittance matrix is ​​obtained by matrix calculation as a frequency domain impedance network of the grid-connected system.

[0161] In an optional embodiment, the AC / DC correlation matrix is ​​a branch-loop correlation matrix; the grid-connected system includes a plurality of AC subsystems and a plurality of DC subsystems; the AC / DC correlation matrix construction module 1003 is specifically used for:

[0162] Selecting at least one reference node for each of the AC subsystems and the DC subsystems;

[0163] According to the preset second frequency domain network construction principle and the relationship between branches and nodes in the network topology, interconnection is performed based on the modular representation of each of the network elements to construct a branch-loop association matrix.

[0164] In an optional embodiment, the frequency domain impedance network construction module 1004 is specifically used for:

[0165] Inverting the branch admittance matrix to obtain a branch impedance matrix;

[0166] According to the branch impedance matrix and the branch-loop association matrix, a loop impedance matrix is ​​obtained by matrix calculation as a frequency domain impedance network of the grid-connected system.

[0167] In an optional embodiment, the types of modular representations of the network elements include modular representations of converter elements, modular representations of AC elements, and modular representations of DC elements.

[0168] In an optional embodiment, the device further includes:

[0169] The network topology building module is used to build the network topology of the grid-connected system according to the modular representations of each converter element, the modular representations of each AC element and the modular representations of each DC element.

[0170] As for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the aforementioned method embodiment.

[0171] It should be noted that, in order to enable those skilled in the art to better distinguish data of the same type but with different actual meanings, some technical features are distinguished by the first and the second in the embodiments of the present invention. The first and the second are only used for data distinction and have no other special meanings. It can be understood that the present invention is not limited to this.

[0172] An embodiment of the present invention further provides an electronic device, the device comprising a processor and a memory:

[0173] The memory is used to store the program code and transmit the program code to the processor;

[0174] The processor is used to execute the frequency domain impedance network construction method of the grid-connected system of any embodiment of the present invention according to the instructions in the program code.

[0175] An embodiment of the present invention further provides a computer-readable storage medium, which is used to store program codes, and the program codes are used to execute the frequency domain impedance network construction method of the grid-connected system of any embodiment of the present invention.

[0176] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0177] In the several embodiments provided by the present invention, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0178] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0179] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0180] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, etc., various media that can store program codes.

[0181] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features thereof may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for constructing a frequency domain impedance network of a grid-connected system, characterized in that: include: Obtaining a network topology of the grid-connected system and a modular representation of each network element; Constructing a branch admittance matrix of the grid-connected system according to the network topology; According to a preset frequency domain network construction principle, the modular representations of the network elements are interconnected to construct an AC / DC correlation matrix; A frequency domain impedance network of the grid-connected system is constructed according to the branch admittance matrix and the AC / DC correlation matrix.

2. The frequency domain impedance network construction method according to claim 1, characterized in that: The AC / DC association matrix is ​​a branch-node association matrix; the grid-connected system includes multiple AC subsystems and multiple DC subsystems; according to the preset frequency domain network construction principle, the modular representations of each of the network elements are interconnected to construct an AC / DC association matrix, including: Selecting at least one reference node for each of the AC subsystems and the DC subsystems; According to the preset first frequency domain network construction principle and the relationship between branches and nodes in the network topology, interconnection is performed based on the modular representation of each of the network elements to construct a branch-node association matrix.

3. The frequency domain impedance network construction method according to claim 2, characterized in that: The step of constructing a frequency domain impedance network of the grid-connected system according to the branch admittance matrix and the AC / DC correlation matrix includes: According to the branch admittance matrix and the branch-node association matrix, a node admittance matrix is ​​obtained by matrix calculation as a frequency domain impedance network of the grid-connected system.

4. The method for constructing a frequency domain impedance network according to claim 1, characterized in that: The AC / DC correlation matrix is ​​a branch-loop correlation matrix; the grid-connected system includes multiple AC subsystems and multiple DC subsystems; according to the preset frequency domain network construction principle, the modular representations of each of the network elements are interconnected to construct an AC / DC correlation matrix, including: Selecting at least one reference node for each of the AC subsystems and the DC subsystems; According to the preset second frequency domain network construction principle and the relationship between branches and nodes in the network topology, interconnection is performed based on the modular representation of each of the network elements to construct a branch-loop association matrix.

5. The method for constructing a frequency domain impedance network according to claim 4, characterized in that: The step of constructing a frequency domain impedance network of the grid-connected system according to the branch admittance matrix and the AC / DC correlation matrix includes: Inverting the branch admittance matrix to obtain a branch impedance matrix; According to the branch impedance matrix and the branch-loop association matrix, a loop impedance matrix is ​​obtained by matrix calculation as a frequency domain impedance network of the grid-connected system.

6. The method for constructing a frequency domain impedance network according to any one of claims 2 to 5, characterized in that: The types of modular representations of the network elements include modular representations of converter elements, modular representations of AC elements, and modular representations of DC elements.

7. The method for constructing a frequency domain impedance network according to claim 6, characterized in that: Also includes: The network topology of the grid-connected system is constructed according to the modular representations of each converter element, the modular representations of each AC element, and the modular representations of each DC element.

8. A frequency domain impedance network construction device for a grid-connected system, characterized in that: include: A modular representation acquisition module, used to acquire the network topology of the grid-connected system and the modular representation of each network element; A branch admittance matrix construction module, used to construct a branch admittance matrix of the grid-connected system according to the network topology; An AC / DC correlation matrix construction module is used to interconnect the modular representations of the network elements according to a preset frequency domain network construction principle to construct an AC / DC correlation matrix; The frequency domain impedance network construction module is used to construct the frequency domain impedance network of the grid-connected system according to the branch admittance matrix and the AC / DC correlation matrix.

9. An electronic device, characterized in that: The device comprises a processor and a memory: The memory is used to store program codes and transmit the program codes to the processor; The processor is used to execute the frequency domain impedance network construction method of the grid-connected system according to any one of claims 1-7 according to the instructions in the program code.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium is used to store program codes, and the program codes are used to execute the frequency domain impedance network construction method of the grid-connected system according to any one of claims 1-7.

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