Frequency response calculation method for three-phase system model of flexible direct current battery swap station

Abstract

The invention discloses a frequency response calculation method and device for a three-phase system model of a flexible direct current battery swap station, a medium and equipment, and relates to the technical field of power systems. Splitting the three-phase system model of the flexible direct current battery swap station to obtain three subsystems; for any subsystem, determining a sub-relational expression among the branch input voltage, the relational matrix, the branch admittance, the node admittance and the node voltage; mapping the sub-relational expression into a total relational expression among the input voltage, the relational matrix, the branch admittance, the node admittance and the node voltage in the three-phase system model; substituting the node admittance matrix, the relation matrix, the branch admittance matrix and the branch input voltage of the three-phase system model into the total relation to obtain the node voltage of the three-phase system model; and determining the frequency response of the three-phase system model according to the node voltage of the three-phase system model. According to the method, the frequency response calculation efficiency of the three-phase system model of the flexible direct current battery swap station can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and particularly to a method, device, medium and equipment for calculating the frequency response of a three-phase system model of a flexible DC substation. Background Art

[0002] With the transformation of the global energy structure and the rapid development of power technology, the AC-DC power distribution technology of flexible substations has attracted increasing attention in the industry. This technology can not only improve the power quality and power distribution reliability, but also support the access of renewable energy and promote the development of smart grids. A flexible DC substation is a power transmission and distribution facility that combines DC technology and flexible control technology. Different from traditional AC systems, flexible DC substations mainly use DC technology, which can provide more efficient and stable power transmission and distribution solutions. Moreover, it is equipped with an advanced intelligent control system that can monitor and manage the operating status of the power system in real time, realizing power regulation, optimization and intelligent management.

[0003] To ensure the reliable and efficient operation of the flexible DC substation system and evaluate the performance of the system in the face of abnormal situations, it is necessary to conduct a frequency response analysis on the three-phase system model of the flexible DC substation. Frequency response analysis is a common analysis method in the fields of control system theory and signal processing, which is used to study the response characteristics of a system to input signals of different frequencies. By analyzing the frequency response of the system, the dynamic characteristics of the system can be better understood, the control strategy can be optimized, and the system performance and stability can be improved to ensure the reliable and efficient operation of the flexible DC substation system.

[0004] However, in the prior art, the efficiency of calculating the frequency response of the three-phase system model of a flexible DC substation is low. Summary of the Invention

[0005] Based on this, it is necessary to provide a method, device, medium and equipment for calculating the frequency response of a three-phase system model of a flexible DC substation to solve the above technical problems, and this method can improve the efficiency of calculating the frequency response of the three-phase system model of the flexible DC substation.

[0006] The present invention adopts the following technical solutions:

[0007] The present invention provides a method for calculating the frequency response of a three-phase system model of a flexible DC substation, including:

[0008] Dividing the three-phase power filter and the three-phase transformer, and the three-phase transformer and the three-phase reactor in the three-phase system model of the flexible DC substation to obtain three subsystems;

[0009] For any subsystem, according to Kirchhoff's current law, Kirchhoff's voltage law, and the relationship between the branch admittance and the branch voltage column vector and branch current column vector in the subsystem, determine the sub-relationship between the branch input voltage, the relationship matrix, the branch admittance, the node admittance, and the node voltage;

[0010] Map the sub-relationship to the total relationship between the input voltage, the relationship matrix, the branch admittance, the node admittance, and the node voltage in the three-phase system model;

[0011] Obtain the node admittance matrix, the relationship matrix, the branch admittance matrix, and the branch input voltage of the three-phase system model, and substitute the node admittance matrix, the relationship matrix, the branch admittance matrix, and the branch input voltage of the three-phase system model into the total relationship to obtain the node voltage of the three-phase system model;

[0012] Determine the frequency response of the three-phase system model according to the node voltage of the three-phase system model.

[0013] Optionally, according to Kirchhoff's current law, Kirchhoff's voltage law, and the relationship between the branch admittance and the branch voltage column vector and branch current column vector in the subsystem, determine the sub-relationship between the branch input voltage, the relationship matrix, the node admittance, and the node voltage, including:

[0014] Substitute the relationship between the branch admittance and the branch voltage column vector and branch current column vector in the subsystem into Kirchhoff's current law, and combine with Kirchhoff's voltage law to obtain the relationship between the branch input voltage, the relationship matrix, the branch admittance, and the node output voltage;

[0015] According to the sub-relationship between the branch input voltage, the relationship matrix, the branch admittance, and the node output voltage, and the relationship between the branch admittance and the node admittance, determine the sub-relationship between the branch input voltage, the branch admittance, the node admittance, and the node output voltage.

[0016] Optionally, Kirchhoff's current law is:

[0017] A1I = 0;

[0018] where I is the branch current column vector of the subsystem, and A1 is the relationship matrix between the nodes in the subsystem;

[0019] Kirchhoff's voltage law is:

[0020] A1 Τ U n = U;

[0021] where A1 Τ is the transpose of A1, U n is the node voltage column vector of the subsystem, and U is the branch voltage column vector of the subsystem;

[0022] The relational expression between the branch admittance, the column vector of branch voltages, and the column vector of branch currents in the subsystem is as follows:

[0023] I = Y1U - Y1U S ;

[0024] Where Y1 is the branch admittance matrix of the subsystem; U S is the column vector of branch input voltages of the subsystem;

[0025] The relational expression between the branch input voltage, the relational matrix, the branch admittance, and the node output voltage is as follows:

[0026] AY1A1 T U n = A1Y1U S .

[0027] Where Y n1 = AY1A T , Y n1 is the node admittance matrix of the subsystem;

[0028] The sub-relational expression between the branch input voltage, the relational matrix, the branch admittance, the node admittance, and the node output voltage is as follows:

[0029] Y n1 U n = A1Y1U S .

[0030] Optionally, obtaining the node admittance matrix of the three-phase system model includes:

[0031] Obtaining the branch admittance matrix of each subsystem;

[0032] Obtaining the branch admittance matrix and the relational matrix of each subsystem;

[0033] Determining the node admittance matrix of each subsystem according to the branch admittance matrix and the relational matrix of each subsystem;

[0034] Representing the node admittance matrix of each subsystem in multiple blocks with the same number of rows and columns respectively;

[0035] Aggregating the node admittance matrices represented by each block according to the contributions of the three subsystems to the three-phase system model to obtain the node admittance matrix of the three-phase system model.

[0036] Optionally, the node admittance matrix of each subsystem is represented by 4 blocks with the same number of rows and columns as follows:

[0037]

[0038] Where Y n1is the nodal admittance matrix represented by sub - block for the first subsystem, Y n11 、Y n12 、Y n13 and Y n14 represent the 4 sub - blocks of the nodal admittance matrix of the first subsystem, Y

[0039] is the nodal admittance matrix represented by sub - block for the second subsystem, Y n2 、Y n21 、Y n22 、Y n23 and Y n24 represent the 4 sub - blocks of the nodal admittance matrix of the second subsystem, Y n3 is the nodal admittance matrix represented by sub - block for the third subsystem, Y n31 、Y n32 、Y n33 and Y n34 represent the 4 sub - blocks of the nodal admittance matrix of the third subsystem.

[0040] Optionally, according to the nodal voltages of the three - phase system model, determine the frequency response of the three - phase system model, including:

[0041] Obtain the output voltage of each phase and the input voltage of each phase from the nodal voltages in the three - phase system model;

[0042] According to the output voltage of each phase and the input voltage of each phase, obtain the frequency response of each phase in the three - phase system model.

[0043] Optionally, the calculation formula for the frequency response of each phase in the three - phase system model is:

[0044]

[0045] where, H(ω) A represents the frequency response of phase A in the three - phase system model, U a(9)～b(10) represents the output voltage of phase A in the three - phase system model, U A(1)～B(2) represents the input voltage of phase A in the three - phase system model, H(ω) B represents the frequency response of phase B in the three - phase system model, U b(10)～c(11) represents the output voltage of phase B in the three - phase system model, U B(2)～C represents the input voltage of phase B in the three - phase system model, H(ω) C represents the frequency response of phase C in the three - phase system model, U a(9)～c(11) represents the output voltage of phase C in the three - phase system model, U A(1)～C represents the input voltage of phase C in the three - phase system model.

[0046] The present invention provides a device for calculating the frequency response of a three-phase system model of a flexible DC substation, comprising:

[0047] A splitting module, configured to split between the three-phase power filter and the three-phase transformer, and between the three-phase transformer and the three-phase reactor in the three-phase system model of the flexible DC substation, to obtain three subsystems;

[0048] A first determination module, configured to, for any one of the subsystems, determine a sub-relationship between the branch input voltage, the relationship matrix, the branch admittance, the node admittance, and the node output voltage according to Kirchhoff's current law, Kirchhoff's voltage law, and the relationship between the branch admittance and the branch voltage column vector and the branch current column vector in the subsystem;

[0049] A mapping module, configured to map the sub-relationship to a total relationship between the input voltage, the relationship matrix, the branch admittance, the node admittance, and the output voltage in the three-phase system model;

[0050] A second determination module, configured to obtain the node admittance matrix, the relationship matrix, the branch admittance matrix, and the branch input voltage of the three-phase system model, and substitute the node admittance matrix, the relationship matrix, the branch admittance matrix, and the branch input voltage of the three-phase system model into the total relationship to obtain the node voltage of the three-phase system model;

[0051] A third determination module, configured to determine the frequency response of the three-phase system model according to the node voltage of the three-phase system model.

[0052] The present invention provides a computer-readable storage medium storing a computer program, which when executed by a processor implements the above method for calculating the frequency response of a three-phase system model of a flexible DC substation.

[0053] The present invention provides a computer device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein when the processor executes the program, it implements the above method for calculating the frequency response of a three-phase system model of a flexible DC substation.

[0054] At least one of the above technical solutions adopted by the present invention can achieve the following beneficial effects:

[0055] The present invention can decompose the three-phase system model of a complex flexible DC substation into subsystems. By constructing sub-relations between the branch input voltage, relation matrix, branch admittance, node admittance, and node output voltage of the subsystems, the construction of the total relation between the input voltage, relation matrix, node admittance, and output voltage in the three-phase system model is realized, so as to determine the node voltage of the three-phase system model, and thus quickly calculate the frequency response of the equivalent model of the three-phase system of the flexible DC substation. This method can improve the efficiency of calculating the frequency response of the equivalent model of the three-phase system of the flexible DC substation. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The drawings described herein are used to provide a further understanding of the present invention, and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0057] Figure 1 It is a schematic flow chart of a method for calculating the frequency response of a three-phase system model of a flexible DC substation provided by the present invention;

[0058] Figure 2 It is a schematic diagram of a three-phase system model of a flexible DC substation provided by the present invention;

[0059] Figure 3 It is a schematic diagram of a three-phase system model of a flexible DC substation split into 3 subsystems provided by the present invention;

[0060] Figure 4 It is a schematic diagram of a NIF model of a subsystem provided by the present invention;

[0061] Figure 5 It is another schematic flow chart of a method for calculating the frequency response of a three-phase system model of a flexible DC substation provided by the present invention;

[0062] Figure 6 It is a schematic diagram of a device for calculating the frequency response of a three-phase system model of a flexible DC substation provided by the present invention;

[0063] Figure 7 It is a schematic diagram of a computer device for implementing a method for calculating the frequency response of a three-phase system model of a flexible DC substation provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0064] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0065] The following will, with reference to the drawings, elaborate on the technical solutions provided by each embodiment of the present invention.

[0066] Figure 1 The following is a schematic flow diagram of a method for calculating the frequency response of a three-phase system model of a flexible DC substation in the present invention, which specifically includes the following steps:

[0067] S101, disconnect the three-phase power filter and the three-phase transformer, and the three-phase transformer and the three-phase reactor in the three-phase system model of the flexible DC substation to obtain three subsystems.

[0068] The three-phase system model of the flexible DC substation is an equivalent current model of the three-phase system of the flexible DC substation. As Figure 2 shown, it specifically includes a three-phase power filter, a three-phase transformer, and a three-phase reactor. Disconnect the three-phase power filter and the three-phase transformer, and the three-phase transformer and the three-phase reactor to obtain three subsystems. The impedance distribution modes of these 3 subsystems are relatively similar. Specifically, the equivalent current model of the three-phase system of the flexible DC substation is disassembled into three subsystems denoted as N1, N2, and N3 along nodes A(3), B(4), C(5) and A(6), B(7), C(8), as Figure 3 shown.

[0069] The impedance distribution mode of each subsystem is a point-to-point impedance (node-to-node impedance function, NIF) model. The NIF model of each subsystem is as Figure 4 shown. The NIF model includes 6 nodes and 18 branches. Branches 1-15 are branches without power sources, and branches 16-18 are three-phase voltage source branches. Voltage sources U A , U B , U C , and the internal resistances r A , r B , r C of each voltage source are connected to the three voltage source branches. Among them, O is the grounding point. The direction of the arrow of each branch in the figure represents the direction of the current flow of each branch, and the impedance between any two points is shown in the figure. Based on this, the coefficient matrix and branch admittance matrix of each subsystem can be obtained.

[0070] S102. For any subsystem, according to Kirchhoff's current law, Kirchhoff's voltage law, and the relationship between the branch admittance, branch voltage column vector, and branch current column vector in the subsystem, determine the sub-relationship between the branch input voltage, relationship matrix, branch admittance, node admittance, and node voltage.

[0071] Optionally, Kirchhoff's current law is:

[0072] A1I = 0 (1)

[0073] where I is the branch current column vector of the subsystem, A1 is the relationship matrix between the nodes in the subsystem, the dimension of the relationship matrix is the number of nodes n * the number of branches b, and the element a ij (i = 1, 2, 3,..., n; j = 1, 2,..., b) is defined as: when node i is associated with branch j and the direction of branch j is away from node i, a ij = 1; when node i is associated with branch j and the direction of branch j points to node i, a ij = -1; when node i is not associated with branch j, a ij = 0.

[0074] According to Figure 4 the model shown, the dimension of the relationship matrix is 6 * 18. According to its branch-node association property, its relationship matrix is:

[0075]

[0076] Kirchhoff's voltage law is:

[0077] A1 Τ U n = U (3)

[0078] where A1 Τ is the transpose of A1, U n is the node voltage column vector of the subsystem, and U is the branch voltage column vector of the subsystem.

[0079] When an external three-phase voltage source is applied, for example, to the three-phase voltage sources U Figure 4 in Appendix A 、U B 、U C , at this time, using the relationship between the branch admittance, branch voltage column vector U, and branch current column vector I, the relationship between the branch admittance, branch voltage column vector, and branch current column vector in the subsystem can be obtained as:

[0080] I = Y1U - Y1U S (4)

[0081] Among them, Y1 is the branch admittance matrix of the subsystem, and the elements in this matrix are the admittance values of each branch; U S is the column vector of branch input voltages of the subsystem.

[0082] For example, the branch admittance matrix Y1 is:

[0083] Y1 = diag[y1 y2 y3 y4 y5 y6 y7 y8 y9 y 10 y 11 y 12 y 13 y 14 y 15 1 / r A 1 / r B 1 / r C (5)

[0084] Among them, y i represents the admittance value of each branch, i represents the numbering order of the branches in the model, U s is the column vector of branch input voltages of the entire model. According to Figure 4 the model shown, U s is specifically:

[0085] U S = [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 U A U B U C T (6)

[0086] Optionally, according to Kirchhoff's current law, Kirchhoff's voltage law, and the relationship formula between the branch admittance, branch voltage column vector, and branch current column vector in the subsystem, determine the sub-relationship formula between the branch input voltage, relationship matrix, node admittance, and node voltage, including: substituting the relationship formula between the branch admittance, branch voltage column vector, and branch current column vector in the subsystem into Kirchhoff's current law, and combining Kirchhoff's voltage law to obtain the relationship formula between the branch input voltage, relationship matrix, branch admittance, and node output voltage; according to the sub-relationship formula between the branch input voltage, relationship matrix, branch admittance, and node output voltage, and the relationship between the branch admittance and node admittance, determine the sub-relationship formula between the branch input voltage, branch admittance, node admittance, and node output voltage.

[0087] That is, substituting I = Y1U - Y1U S into A1I = 0, and then combining with A1 Τ U n = U; the sub-relationship formula between the branch input voltage, relationship matrix, branch admittance, and node output voltage can be obtained as:​

[0088] AY1A1 T U n = A1Y1U S (7)

[0089] where Y n1 = AY1A T and Y n1 is the node admittance matrix of the subsystem. Therefore, formula (7) can be simplified to a sub-relation between the branch input voltage, relation matrix, branch admittance, node admittance, and node output voltage, which is:

[0090] Y n1 U n = A1Y1U S (8)

[0091] S103. Map the sub-relation to the total relation between the input voltage, relation matrix, branch admittance, node admittance, and node voltage in the three-phase system model.

[0092] The total relation between the input voltage, relation matrix, branch admittance, node admittance, and node voltage in the three-phase system model is: Y ll U N = AYU SS ; where Y ll is the node admittance matrix of the three-phase system model, U N is the node voltage column vector of the three-phase system model, A is the relation matrix of the three-phase system model, Y is the branch admittance matrix of the three-phase system model, and U SS is the branch input voltage column vector of the three-phase system model.

[0093] S104. Obtain the node admittance matrix, relation matrix, branch admittance matrix, and branch input voltage of the three-phase system model, and substitute the node admittance matrix, relation matrix, branch admittance matrix, and branch input voltage of the three-phase system model into the total relation to obtain the node voltage of the three-phase system model.

[0094] where, according to the branch admittance matrix of the subsystem, the branch admittance matrix Y of the entire three-phase system is formed. Specifically, it is arranged in the order of the branch numbers of the entire system as follows: Y1, Y2, and Y3 are the branch admittance matrices of the three subsystems in the three-phase system respectively; according to the relation matrices A1, A2, and A3 of the subsystem, the relation matrix A of the entire three-phase system is formed. Specifically, it is arranged in the order of the branch and node numbers of the entire system as: A = [A1 A2 A3]. The node voltage column vector of the three-phase system model can also be arranged in the order of the node numbers of the entire system.

[0095] Optionally, obtain the nodal admittance matrix of the three-phase system model, including: obtaining the branch admittance matrix and relationship matrix of each subsystem; determining the nodal admittance matrix of each subsystem according to the branch admittance matrix and relationship matrix of each subsystem; respectively representing the nodal admittance matrix of each subsystem with multiple sub-blocks having the same number of rows and columns; aggregating the nodal admittance matrices represented by each sub-block according to the contributions of the three subsystems to the three-phase system model to obtain the nodal admittance matrix of the three-phase system model.

[0096] Specifically, the nodal admittance matrix of each subsystem can be determined according to the admittance value of each branch in each subsystem, and the nodal admittance matrix of each subsystem can be calculated according to Y n1 = AY1A T Calculate the nodal admittance matrix of each subsystem.

[0097] Then the nodal admittance matrix of each subsystem is represented by 4 sub-blocks with the same number of rows and columns, in the form of:

[0098]

[0099] Among them, Y n1 is the nodal admittance matrix of the first subsystem represented by sub-blocks, Y n11 , Y n12 , Y n13 and Y n14 Table

[0100] The 4 sub-blocks of the nodal admittance matrix of the first subsystem, Y n2 is the nodal admittance matrix of the second subsystem represented by sub-blocks

[0101] point, Y n21 , Y n22 , Y n23 and Y n24 The 4 sub-blocks representing the nodal admittance matrix of the second subsystem

[0102] block, Y n3 is the nodal admittance matrix of the third subsystem represented by sub-blocks, Y n31 , Y n32 , Y n33 and Y n34 The

[0103] represents the 4 sub-blocks of the nodal admittance matrix of the 3 subsystems.

[0104] Then the nodal admittance matrix of the entire three-phase system model is:

[0105]

[0106] The nodal admittance matrix Y of the three-phase system ll, substitute the relationship matrix A, branch admittance matrix Y, and branch input voltage Uss into the total relationship formula to obtain the node voltage U of the three-phase system model. N .

[0107] S105, determine the frequency response of the three-phase system model according to the node voltage of the three-phase system model.

[0108] Optionally, determine the frequency response of the three-phase system model according to the node voltage of the three-phase system model, including: obtaining the output voltage of each phase and the input voltage of each phase from the node voltage in the three-phase system model; obtaining the frequency response of each phase in the three-phase system model according to the output voltage of each phase and the input voltage of each phase.

[0109] Specifically, the calculation formula for the frequency response of each phase in the three-phase system model is:

[0110]

[0111] where H(ω) A represents the frequency response of phase A in the three-phase system model, U a(9)～b(10) represents the output voltage of phase A in the three-phase system model, U A(1)～B(2) represents the input voltage of phase A in the three-phase system model, H(ω) B represents the frequency response of phase B in the three-phase system model, U b(10)～c(11) represents the output voltage of phase B in the three-phase system model, U B(2)～C represents the input voltage of phase B in the three-phase system model, H(ω) C represents the frequency response of phase C in the three-phase system model, U a(9)～c(11) represents the output voltage of phase C in the three-phase system model, U A(1)～C represents the input voltage of phase C in the three-phase system model.

[0112] Specifically, as Figure 2 shown, U a(9)～b(10) is the voltage difference between the voltage at node a(9) and the voltage at node b(10) of the system model; similarly, U b(10)～c(11) is the voltage difference between the voltage at node b(10) and the voltage at node c(11) of the system model; U a(9)～c(11) is the voltage difference between the voltage at node a(9) and the voltage at node c(11) of the system model; U A(1)～B(2) is the voltage difference between the voltage at node A(1) and the voltage at node B(2) of the system model; U B(2)～C is the voltage difference between the voltage at node B(2) and the voltage at node C of the system model; U A(1)～C is the voltage difference between the voltage at node A(1) and the voltage at node C of the system model.

[0113] In the present invention, a flexible DC substation is combined with a three-phase system model to achieve accurate calculation of frequency response. Traditional frequency response calculation methods usually analyze a single system or a system under steady-state operating conditions. However, combining a flexible DC substation with a three-phase system model may provide more accurate frequency response calculations for more realistic system operating conditions. It better considers the interconnection and influence between different components in the system, making the final frequency response results more reliable and practical.

[0114] Moreover, instead of directly establishing and solving a complete nodal equation for the system model, it first decomposes and then aggregates the system model, that is, it establishes and solves the model simultaneously. By disassembling the system model and decomposing the system into smaller subsystems, it simplifies the analysis process of complex systems, making the calculation of frequency response more efficient and accurate. As Figure 5 shown, it specifically includes the following steps:

[0115] S501, Modeling the equivalent model of the three-phase system of the flexible DC substation.

[0116] S502, Observe the impedance distribution pattern of the system model to determine a reasonable decomposition method and decompose the system model reasonably.

[0117] This system model has strong unit repeatability, and the impedance distribution pattern is relatively single and regular. The system model can be disassembled twice to obtain three simple NIF models, and there is no controlled coupling between subsystems.

[0118] S503, Analyze each subsystem separately and list the branch admittance matrices of each subsystem.

[0119] S504, Integrate the branch admittance matrices of each subsystem into the branch admittance matrix of the entire three-phase system model.

[0120] S505, Obtain the nodal admittance matrices of each subsystem from the branch admittance matrices of each subsystem in combination with the relationship matrices of each subsystem.

[0121] S506, Determine the frequency response according to the nodal admittance matrix of the entire three-phase system model.

[0122] The subsystems have similar impedance distribution patterns. Only one of the subsystems, namely the NIF model, needs to be analyzed. According to the given branch current directions and impedance distributions, the relationship matrix and branch admittance matrix of the NIF model are given. Based on the relationship between the nodal admittance matrix and the branch admittance matrix, its nodal admittance matrix is further obtained.

[0123] Joint solution of subsystems: Number each node and branch of the system model, mark the common nodes and non-common nodes. There is no mutual coupling between the branches of subsystems. Just add the node equations of the subsystems to the node equations of the large network according to the component contributions. Establish the electric current vector matrix and obtain its node voltage matrix according to the node voltage equation. And based on the above principle, derive the matrix algorithm for calculating its frequency response.

[0124] The present invention can decompose the equivalent model of the three-phase system of a complex flexible DC substation into subsystems. By quickly constructing the node voltage matrix of the subsystems and according to the connection relationships of each subsystem, quickly realize the construction of the node voltage matrix of the total system, so as to quickly calculate the frequency response of the equivalent model of the three-phase system of the flexible DC substation. This method can improve the efficiency of calculating the frequency response of the equivalent model of the three-phase system of the flexible DC substation.

[0125] When applying the frequency response calculation method for the three-phase system model of the flexible DC substation provided by the present invention, it is not necessary to execute according to Figure 1 the order of the steps shown. The specific execution order of each step can be determined according to needs, and the present invention does not limit this.

[0126] The above is the frequency response calculation method for the three-phase system model of the flexible DC substation provided by one or more embodiments of the present invention. Based on the same idea, the present invention also provides a corresponding frequency response calculation device for the three-phase system model of the flexible DC substation, as Figure 6 shown.

[0127] Figure 6 The figure shows a schematic diagram of a frequency response calculation device for the three-phase system model of the flexible DC substation provided by the present invention. The device 600 includes:

[0128] A splitting module 601, configured to split between the three-phase power filter and the three-phase transformer, and between the three-phase transformer and the three-phase reactor in the three-phase system model of the flexible DC substation to obtain three subsystems;

[0129] A first determination module 602, configured to, for any one of the subsystems, determine the sub-relationship between the branch input voltage, the relationship matrix, the branch admittance, the node admittance, and the node output voltage according to Kirchhoff's current law, Kirchhoff's voltage law, and the relationship between the branch admittance and the branch voltage column vector and the branch current column vector in the subsystem;

[0130] A mapping module 603, configured to map the sub-relationship to the total relationship between the input voltage, the relationship matrix, the branch admittance, the node admittance, and the output voltage in the three-phase system model;

[0131] The second determination module 604 is configured to obtain the node admittance matrix, relationship matrix, branch admittance matrix, and branch input voltage of the three-phase system model, substitute the node admittance matrix, relationship matrix, branch admittance matrix, and branch input voltage of the three-phase system model into the total relationship formula, and obtain the node voltage of the three-phase system model.

[0132] The third determination module 605 is configured to determine the frequency response of the three-phase system model according to the node voltage of the three-phase system model.

[0133] For the specific limitations of the frequency response calculation device for the three-phase system model of the flexible DC substation, reference can be made to the limitations of the frequency response calculation method for the three-phase system model of the flexible DC substation in the above text, which will not be elaborated here. Each module in the above frequency response calculation device for the three-phase system model of the flexible DC substation can be implemented in whole or in part by software, hardware, and their combination. The above modules can be embedded in the processor of the computer device in hardware form or independent of it, or stored in the memory of the computer device in software form, so that the processor can call and execute the operations corresponding to the above modules.

[0134] The present invention also provides a computer-readable storage medium, which stores a computer program that can be used to execute the above Figure 1 provided frequency response calculation method for the three-phase system model of the flexible DC substation.

[0135] The present invention also provides Figure 7 the structural schematic diagram of the computer device shown in, as Figure 7 shown, at the hardware level, the computer device includes a processor, an internal bus, a network interface, a memory, and a non-volatile memory. Of course, it may also include other hardware required for other services. The processor reads the corresponding computer program from the non-volatile memory into the memory and then runs it to implement the above Figure 1 provided frequency response calculation method for the three-phase system model of the flexible DC substation.

[0136] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, storage, database, or other medium used in the embodiments provided by the present invention can include at least one of non-volatile and volatile memories. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0137] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in the present invention.

Claims

1. A frequency response calculation method for a three-phase system model of a flexible DC substation, characterized in that Including: Separate the three-phase power filter and the three-phase transformer, and the three-phase transformer and the three-phase reactor in the three-phase system model of the flexible DC substation to obtain three subsystems; For any one of the subsystems, according to Kirchhoff's current law, Kirchhoff's voltage law, and the relationship between the branch admittance, branch voltage column vector, and branch current column vector in the subsystem, determine the sub-relationship between the branch input voltage, relationship matrix, branch admittance, node admittance, and node voltage; Map the sub-relationship to the total relationship between the input voltage, relationship matrix, branch admittance, node admittance, and node voltage in the three-phase system model; Obtain the node admittance matrix, relationship matrix, branch admittance matrix, and branch input voltage of the three-phase system model, and substitute the node admittance matrix, relationship matrix, branch admittance matrix, and branch input voltage of the three-phase system model into the total relationship to obtain the node voltage of the three-phase system model; Determine the frequency response of the three-phase system model according to the node voltage of the three-phase system model.

2. The method according to claim 1, wherein The step of determining the sub-relationship between the branch input voltage, relationship matrix, branch admittance, node admittance, and node output voltage according to Kirchhoff's current law, Kirchhoff's voltage law, and the relationship between the branch admittance, branch voltage column vector, and branch current column vector in the subsystem includes: Substitute the relationship between the branch admittance, branch voltage column vector, and branch current column vector in the subsystem into Kirchhoff's current law, and combine with Kirchhoff's voltage law to obtain the relationship between the branch input voltage, relationship matrix, branch admittance, and node output voltage; According to the sub-relationship between the branch input voltage, relationship matrix, branch admittance, and node output voltage, and the relationship between the branch admittance and the node admittance, determine the sub-relationship between the branch input voltage, relationship matrix, branch admittance, node admittance, and node output voltage.

3. The method according to claim 2, wherein Kirchhoff's current law is: A1I = 0; where I is the branch current column vector of the subsystem, and A1 is the relationship matrix between the nodes in the subsystem; Kirchhoff's voltage law is: A1 Τ U n = U; where A1 Τ is the transpose of A1, U n is the column vector of the node voltages of the subsystem, and U is the column vector of the branch voltages of the subsystem; The relationship between the branch admittance, branch voltage column vector, and branch current column vector in the subsystem is: I = Y1U - Y1U S ; Among them, Y1 is the branch admittance matrix of the subsystem; U S is the column vector of the branch input voltage of the subsystem; The relationship between the branch input voltage, relationship matrix, branch admittance, and node output voltage is: AY1A1 T U n = A1Y1U S ; Among them, Y n1 = AY1A T , Y n1 is the nodal admittance matrix of the subsystem; The sub-relationship between the branch input voltage, relationship matrix, branch admittance, node admittance, and node output voltage is: Y n1 U n = A1Y1U S .

4. The method according to claim 1, wherein Obtaining the node admittance matrix of the three-phase system model includes: Obtain the branch admittance matrix and relationship matrix of each subsystem; Determine the node admittance matrix of each subsystem according to the branch admittance matrix and relationship matrix of each subsystem; Represent the node admittance matrix of each subsystem with multiple blocks having the same number of rows and columns; Aggregate the node admittance matrices represented by each block according to the contributions of the three subsystems to the three-phase system model to obtain the node admittance matrix of the three-phase system model.

5. The method according to claim 4, wherein The node admittance matrix of each subsystem is represented by 4 blocks having the same number of rows and columns as: Among them, Y n1 is the nodal admittance matrix represented by the first subsystem block, Y n11 , Y n12 Y n13 Y n14 are the four blocks of the nodal admittance matrix of the first subsystem, Y n2 is the nodal admittance matrix represented by the second subsystem block, Y n21 , Y n22 , Y n23 and Y n24 represent the four blocks of the nodal admittance matrix of the second subsystem, Y n3 is the nodal admittance matrix represented by the third subsystem block, Y n31 , Y n32 , Y n33 and Y n34 represent the four blocks of the nodal admittance matrix of the third subsystem; The node admittance matrix of the three-phase system model is: Among them, Y ll is the nodal admittance matrix of the three-phase system model.

6. The method according to claim 1, wherein Determining the frequency response of the three-phase system model based on the node voltages of the three-phase system model includes: Obtaining the output voltage of each phase and the input voltage of each phase in the three-phase system from the node voltages of the three-phase system model; Obtaining the frequency response of each phase in the three-phase system model according to the output voltage of each phase and the input voltage of each phase.

7. The method according to claim 6, wherein The calculation formula for the frequency response of each phase in the three-phase system model is: Among them, H(ω) A represents the frequency response of phase A in the three-phase system model, U a(9)～b(10) represents the output voltage of phase A in the three-phase system model, U A(1)～B(2) represents the input voltage of phase A in the three-phase system model, H(ω) B represents the frequency response of phase B in the three-phase system model, U b(10)～c(11) represents the output voltage of phase B in the three-phase system model, U B(2)～C represents the input voltage of phase B in the three-phase system model, H(ω) C represents the frequency response of phase C in the three-phase system model, U a(9)～c(11) represents the output voltage of phase C in the three-phase system model, U A(1)～C represents the input voltage of phase C in the three-phase system model.

8. A frequency response calculation device for a three-phase system model of a flexible DC substation, characterized in that Including: A splitting module for splitting between the three-phase power filter and the three-phase transformer, and between the three-phase transformer and the three-phase reactor in the three-phase system model of the flexible DC substation to obtain three subsystems; A first determination module for, for any one of the subsystems, determining the sub-relationship between the branch input voltage, the relationship matrix, the branch admittance, the node admittance, and the node output voltage according to Kirchhoff's current law, Kirchhoff's voltage law, and the relationship between the branch admittance and the branch voltage column vector and the branch current column vector in the subsystem; A mapping module for mapping the sub-relationship to the total relationship between the input voltage, the relationship matrix, the branch admittance, the node admittance, and the output voltage in the three-phase system model; A second determination module for obtaining the node admittance matrix, the relationship matrix, the branch admittance matrix, and the branch input voltage of the three-phase system model, and substituting the node admittance matrix, the relationship matrix, the branch admittance matrix, and the branch input voltage of the three-phase system model into the total relationship to obtain the node voltages of the three-phase system model; A third determination module for determining the frequency response of the three-phase system model according to the node voltages of the three-phase system model.

9. A computer-readable storage medium, characterized in that, The storage medium stores a computer program, and when the computer program is executed by a processor, the method described in any one of claims 1 to 7 is implemented.

10. A computer device, characterized in that, Including a memory, a processor, and a computer program stored on the memory and executable on the processor, and when the processor executes the program, the method described in any one of claims 1 to 7 is implemented.

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