Flexible interconnection system large disturbance stability analysis method, device, equipment and medium

Abstract

The present application relates to a kind of flexible interconnection system large disturbance stability analysis method, device, equipment and medium, wherein, method includes: the simplified circuit model of flexible interconnection system is established;According to the simplified circuit model, direct current side mixed potential function and each area mixed potential function are constructed;According to the direct current side mixed potential function, direct current side stability criterion is obtained;According to the mixed potential function of each area, each area stability criterion under the influence of direct current side is obtained;The direct current side stability criterion and each area stability criterion are combined to obtain the large signal stability criterion of flexible interconnection system.The present application can be suitable for most low-voltage area flexible interconnection scene.

Description

Technical Field

[0001] This invention relates to the field of stability analysis technology for power electronic converters, and in particular to a method, apparatus, equipment, and medium for large disturbance stability analysis of flexible interconnected systems. Background Technology

[0002] With the introduction of the "dual carbon" target and the development of microgrid technology, traditional distribution substations face numerous difficulties, including challenges in expansion, large-scale absorption of distributed energy, and the inability to achieve power interaction. Flexible interconnected distribution technology, through power electronic converters, constructs low-voltage DC buses near distribution substations. This enables flexible interaction between substations and allows for the absorption of distributed energy via the DC bus, providing a solution to change the traditional single-transformer substation operation and improve power supply levels. However, the integration of a large proportion of power electronic equipment results in flexible interconnected systems exhibiting low inertia and weak damping, thus highlighting system stability issues.

[0003] Existing research on the stability analysis of DC systems can be divided into two categories: small-signal and large-signal. Small-signal stability analysis mainly targets small-amplitude or short-term disturbances, such as small fluctuations in generator output power, parameter changes caused by the charging and discharging of energy storage systems, and line parameter disturbances, to assess the impact of small disturbances on the system. Common small-signal disturbance analyses mainly rely on the eigenvalue method based on state-space models and impedance analysis based on equivalent impedance models. However, small-signal stability only ensures that the system is asymptotically stable near the equilibrium point. When the system's operating state deviates significantly from the equilibrium point, the small-signal model obtained through local linearization is often invalid. Therefore, it is necessary to establish a large-signal model for the system. Large-signal stability analysis is usually based on Lyapunov's second method, which characterizes the attraction domain of the system using Lyapunov functions. However, this only provides a sufficient condition for system stability, namely, that the attraction domain is conservative. The more suitable the Lyapunov second method is, the lower the conservatism of the attraction domain, and the closer the estimated attraction domain is to the true attraction domain. Therefore, constructing a suitable Lyapunov second method is crucial for analyzing the large-signal stability of the system. However, most existing studies are focused on specific topologies and lack a unified analysis method applicable to the vast majority of systems. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method, apparatus, equipment and medium for analyzing the stability of flexible interconnection systems under large disturbances, which can be applied to most low-voltage distribution area flexible interconnection scenarios.

[0005] The technical solution adopted by this invention to solve its technical problem is: to provide a method for analyzing the stability of a flexible interconnected system under large disturbances, comprising the following steps:

[0006] Establish a simplified circuit model for the flexible interconnected system;

[0007] Based on the simplified circuit model, construct the DC-side hybrid potential function and the hybrid potential function for each transformer area;

[0008] The DC-side stability criterion is obtained based on the DC-side mixed potential function.

[0009] Based on the mixed potential function of each transformer area, the stability criteria of each transformer area under the influence of the DC side are obtained;

[0010] The DC-side stability criterion and the stability criteria of each transformer area are combined to obtain the large-signal stability criterion of the flexible interconnection system.

[0011] When establishing a simplified circuit model for the flexible interconnection system, the transformer substation is equivalent to a DC system, and the DC-side equipment is equivalent to a constant power load, a constant current load, or a constant impedance load according to the control strategy.

[0012] The DC-side mixed potential function is expressed as: Where P(i,v) is the DC-side hybrid potential function, and v dc Indicates the DC side voltage, i oK P represents the DC-side current of the Kth transformer area. CPL R represents the power of a constant power load. L This represents the resistance of a constant impedance load.

[0013] The mixed potential function of each transformer area is expressed as follows: Among them, P k (i,v) is the mixed potential function of the k-th transformer region, v dc Indicates the DC side voltage, i oK P represents the DC-side current of the Kth transformer area. CPL R represents the power of a constant power load. L R represents the resistance of a constant impedance load. f i represents the equivalent resistance between the converter and the power grid. dk V represents the current of the k-th converter. dk This represents the voltage of the k-th converter.

[0014] The DC-side stability criterion obtained based on the DC-side mixed potential function is specifically as follows:

[0015] Calculate the second-order partial derivative of the current potential function with respect to the current variable in the DC-side hybrid potential function;

[0016] Calculate the second-order partial derivative of the voltage potential function with respect to the voltage variable in the DC-side hybrid potential function;

[0017] By ensuring that the sum of the minimum eigenvalues ​​of the second-order partial derivatives of the current variable and the second-order partial derivatives of the voltage variable is greater than 0, the DC-side stability criterion is obtained.

[0018] The stability criterion for each transformer area under the influence of the DC side, obtained based on the mixed potential function of each transformer area, is as follows:

[0019] Calculate the second-order partial derivative of the current potential function with respect to the current variable in the mixed potential function of each transformer area;

[0020] Calculate the second-order partial derivative of the voltage potential function with respect to the voltage variable in the mixed potential function of each transformer area;

[0021] By ensuring that the sum of the minimum eigenvalues ​​of the second-order partial derivatives of the current variable and the second-order partial derivatives of the voltage variable is greater than 0, the stability criteria for each transformer substation are obtained.

[0022] The technical solution adopted by this invention to solve its technical problem is: to provide a large disturbance stability analysis device for a flexible interconnected system, comprising:

[0023] A module is established to create a simplified circuit model for flexible interconnected systems.

[0024] The module is used to construct the DC-side hybrid potential function and the hybrid potential function of each transformer area based on the simplified circuit model.

[0025] The first stability criterion module is used to obtain the DC-side stability criterion based on the DC-side mixed potential function.

[0026] The second stability criterion module is used to obtain the stability criterion of each transformer area under the influence of the DC side based on the mixed potential function of each transformer area.

[0027] The merging module is used to merge the DC-side stability criterion and the stability criterion of each transformer area to obtain the large-signal stability criterion of the flexible interconnection system.

[0028] When establishing a simplified circuit model of the flexible interconnection system, the module equates the transformer area to a DC system and the DC-side equipment to a constant power load, constant current load, or constant impedance load according to the control strategy.

[0029] The DC-side mixed potential function is expressed as: Where P(i,v) is the DC-side hybrid potential function, and v dc Indicates the DC side voltage, i oK P represents the DC-side current of the Kth transformer area. CPL R represents the power of a constant power load. L This represents the resistance of a constant impedance load.

[0030] The mixed potential function of each transformer area is expressed as follows: Among them, P k (i,v) is the mixed potential function of the k-th transformer region, v dc Indicates the DC side voltage, ioK P represents the DC-side current of the Kth transformer area. CPL R represents the power of a constant power load. L R represents the resistance of a constant impedance load. f i represents the equivalent resistance between the converter and the power grid. dk V represents the current of the k-th converter. dk This represents the voltage of the k-th converter.

[0031] The first stability criterion module includes:

[0032] The first calculation unit is used to calculate the second-order partial derivative of the current potential function with respect to the current variable in the DC-side hybrid potential function;

[0033] The second calculation unit is used to calculate the second-order partial derivative of the voltage potential function with respect to the voltage variable in the DC-side hybrid potential function;

[0034] The first stability criterion acquisition unit is used to ensure that the sum of the minimum eigenvalue of the second-order partial derivative of the current variable and the minimum eigenvalue of the second-order partial derivative of the voltage variable is greater than 0, thereby obtaining the DC-side stability criterion.

[0035] The second stability criterion module includes:

[0036] The third calculation unit is used to calculate the second-order partial derivative of the current potential function with respect to the current variable in the mixed potential function of each transformer area.

[0037] The fourth calculation unit is used to calculate the second-order partial derivative of the voltage potential function with respect to the voltage variable in the mixed potential function of each transformer area;

[0038] The second stability criterion acquisition unit is used to ensure that the sum of the minimum eigenvalue of the second-order partial derivative of the current variable and the minimum eigenvalue of the second-order partial derivative of the voltage variable is greater than 0, thereby obtaining the stability criteria for each transformer area.

[0039] The technical solution adopted by the present invention to solve its technical problem is: to provide an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the above-mentioned flexible interconnection system large disturbance stability analysis method.

[0040] The technical solution adopted by the present invention to solve its technical problem is: to provide a computer-readable storage medium on which a computer program is stored, wherein when the computer program is executed by a processor, the steps of the above-mentioned method for analyzing the stability of flexible interconnected systems under large disturbances are implemented.

[0041] Beneficial effects

[0042] Due to the adoption of the above technical solutions, this invention has the following advantages and positive effects compared with the prior art: This invention divides the stability criteria into two parts: "DC side stability criteria" and "low-voltage distribution area stability criteria", which clarifies which part of the parameter defects in the flexible interconnection system leads to system instability. It provides a theoretical basis for the planning, design, operation control and fault diagnosis of flexible interconnection systems, and provides a unified architecture for the large disturbance stability analysis of flexible interconnection systems, which is applicable to most low-voltage distribution area flexible interconnection scenarios. Attached Figure Description

[0043] Figure 1 This is a flowchart of the large disturbance stability analysis method for a flexible interconnected system according to the first embodiment of the present invention;

[0044] Figure 2 This is a system topology diagram according to an embodiment of the present invention;

[0045] Figure 3 This is a simplified circuit model diagram in an embodiment of the present invention. Detailed Implementation

[0046] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0047] The first embodiment of the present invention relates to a method for analyzing the stability of a flexible interconnected system under large disturbances, such as... Figure 1 As shown, the method includes: establishing a simplified circuit model of the flexible interconnect system; constructing a DC-side mixed potential function and a mixed potential function for each transformer area based on the simplified circuit model; obtaining a DC-side stability criterion based on the DC-side mixed potential function; obtaining a stability criterion for each transformer area under the influence of the DC side based on the mixed potential function for each transformer area; and merging the DC-side stability criterion and the stability criterion for each transformer area to obtain a large-signal stability criterion for the flexible interconnect system. This method utilizes the standardization of the flexible interconnect system architecture to simplify system modeling, thereby expanding its application scope. It is applicable to the stability analysis of most flexible interconnect systems, and the obtained stability criterion provides the relationship between system circuit parameters, control parameters, and load power, providing a theoretical basis for the planning, design, and operation control of flexible interconnect systems.

[0048] The present invention will be further illustrated by a specific embodiment below.

[0049] To facilitate subsequent analysis and derivation, the third stability theorem of the mixed potential function theory is restated as follows:

[0050] The mixed potential function P(i,v) of the system is:

[0051] P(i,v)=-A(i)+B(v)+(i,γv-α)

[0052] Where A(i) and B(v) are the current potential function and voltage potential function, respectively, γ is a constant matrix related to the circuit structure, and the elements in the matrix are ±1 or 0, and α is a constant vector. The second-order partial derivative of the current potential function A(i) with respect to the current is defined as: The second-order partial derivative of the voltage potential function B(v) with respect to voltage is expressed as: Let μ1 be L -1 / 2 A ii (i)L -1 / 2 The smallest eigenvalue, that is, the smallest eigenvalue of the second-order partial derivative of the current variable, μ2 is C -1 / 2 B vv (v)C -1 / 2 The smallest eigenvalue, that is, the smallest eigenvalue of the second-order partial derivative of the voltage variable, if it satisfies

[0053] μ1+μ2>0

[0054] Then P * The time derivative of (i,v) is less than 0, indicating that this point is the equilibrium point of the system. Let be the Lyapunov function of the system. If as |i|+|v|→∞, then P * If (i,v)→∞, then the system is asymptotically stable over a large range.

[0055] The flexible interconnected system studied in this embodiment includes two low-voltage distribution areas, a set of photovoltaic systems, a set of DC power ports, and a set of energy storage systems, such as... Figure 2 As shown.

[0056] First, a simplified model of the system is performed. Based on the control strategy, the DC-side photovoltaic system, energy storage, charging piles, and low-voltage distribution area are simplified. The low-voltage distribution area is equivalent to a DC system, and energy storage, etc., are equivalent to constant power loads, constant current loads, and constant impedance loads according to the control strategy. The mathematical model of the DC / AC converter of the low-voltage distribution area in this embodiment, in the dq0 coordinate system, can be expressed as follows:

[0057]

[0058] Among them, e d v d and i d These represent the d-axis components of the grid voltage, converter output voltage, and converter current, respectively. q v q and i qLet R be the q-axis components of the grid voltage, converter output voltage, and converter current, respectively. f and L f The equivalent resistance and equivalent inductance between the converter and the power grid include LC filters, line impedance, etc. Ignoring the q-axis component, we have:

[0059]

[0060] This equation describes the equivalent DC system of a low-voltage distribution area. On the DC side, the photovoltaic system operates at its maximum power point, and the energy storage system operates at constant power; therefore, both can be considered constant power loads, and the DC power input port can be considered a constant impedance load. Low-voltage distribution areas using constant power control are considered constant power sources (loads), while those using droop control or constant DC voltage control are considered constant current loads. Taking droop control as an example, the simplified circuit model of the system is finally obtained as follows: Figure 3 As shown.

[0061] The DC-side mixed potential function can be expressed as: Among them, v dc Indicates the DC side voltage, i oK P represents the DC-side current of the Kth transformer area. CPL R represents the power of a constant power load. L This represents the resistance of a constant impedance load.

[0062] Since there are only two substations in this embodiment, the DC-side hybrid potential function in this embodiment is:

[0063] The current potential function A(i) and voltage potential function B(v) in the DC-side hybrid potential function dc They are respectively:

[0064] Therefore, the voltage potential function B(v) dc ) for v dc The second-order partial derivative is:

[0065]

[0066] In the formula, r k k is the droop control coefficient. pv and k iv These are the proportional and integral coefficients of the voltage loop PI controller, i ok R is the DC-side current of the k-th transformer area. fk Let i be the equivalent resistance between the converter and the power grid in the k-th distribution area. dk Let L be the converter current of the k-th transformer area. fk Let be the equivalent inductance between the converter and the power grid in the k-th distribution area. This is the rated value of the DC bus voltage.

[0067] definition: Among them, C dc The DC bus capacitance, therefore the stability criterion for the DC side is:

[0068] The mixed potential function of a transformer substation cannot ignore the current loop; therefore, the mixed potential function of each substation is expressed as follows: Take station 1 in this embodiment as an example.

[0069] Since this embodiment only includes two substations, the substation mixing potential function for substation 1 in this embodiment is:

[0070]

[0071] The current potential function A(i) in the mixed potential function of this transformer area d1 ) and voltage potential function B(v dc They are respectively:

[0072]

[0073] Current potential function A(i) d1 ) to i d1 and the voltage potential function B(v) dc ) for v dc The second-order partial derivative is:

[0074]

[0075] Where, k pi k is the proportionality coefficient of the current loop. pv This is the proportional gain of the voltage loop PI controller.

[0076] definition: The stability criterion for zone 1 is:

[0077] The process for obtaining the stability criterion for transformer area 2 is the same as that for transformer area 1. Therefore, the stability criterion for transformer area 2 is:

[0078] By combining the stability criteria for transformer area 1, transformer area 2, and the DC-side stability criteria, the large-signal stability criterion for the entire flexible interconnection system is obtained as follows:

[0079] It is not difficult to see that this invention divides the stability criteria into two parts: "DC-side stability criteria" and "low-voltage distribution area stability criteria". It clarifies which part of the parameter defects in the flexible interconnection system leads to system instability, providing a theoretical basis for the planning, design, operation control and fault diagnosis of flexible interconnection systems. It also provides a unified architecture for the large disturbance stability analysis of flexible interconnection systems, which is applicable to most low-voltage distribution area flexible interconnection scenarios.

[0080] The second embodiment of the present invention relates to a large disturbance stability analysis device for a flexible interconnected system, comprising:

[0081] A module is established to create a simplified circuit model for flexible interconnected systems.

[0082] The module is used to construct the DC-side hybrid potential function and the hybrid potential function of each transformer area based on the simplified circuit model.

[0083] The first stability criterion module is used to obtain the DC-side stability criterion based on the DC-side mixed potential function.

[0084] The second stability criterion module is used to obtain the stability criterion of each transformer area under the influence of the DC side based on the mixed potential function of each transformer area.

[0085] The merging module is used to merge the DC-side stability criterion and the stability criterion of each transformer area to obtain the large-signal stability criterion of the flexible interconnection system.

[0086] When establishing a simplified circuit model of the flexible interconnection system, the module equates the transformer area to a DC system and the DC-side equipment to a constant power load, constant current load, or constant impedance load according to the control strategy.

[0087] The DC-side mixed potential function is expressed as: Where P(i,v) is the DC-side hybrid potential function, and v dc Indicates the DC side voltage, i oK P represents the DC-side current of the Kth transformer area. CPL R represents the power of a constant power load. L This represents the resistance of a constant impedance load.

[0088] The mixed potential function of each transformer area is expressed as follows: Among them, P k (i,v) is the mixed potential function of the k-th transformer region, v dc Indicates the DC side voltage, i oK P represents the DC-side current of the Kth transformer area. CPL R represents the power of a constant power load. L R represents the resistance of a constant impedance load. f i represents the equivalent resistance between the converter and the power grid.dk V represents the current of the k-th converter. dk This represents the voltage of the k-th converter.

[0089] The first stability criterion module includes:

[0090] The first calculation unit is used to calculate the second-order partial derivative of the current potential function with respect to the current variable in the DC-side hybrid potential function;

[0091] The second calculation unit is used to calculate the second-order partial derivative of the voltage potential function with respect to the voltage variable in the DC-side hybrid potential function;

[0092] The first stability criterion acquisition unit is used to ensure that the sum of the minimum eigenvalue of the second-order partial derivative of the current variable and the minimum eigenvalue of the second-order partial derivative of the voltage variable is greater than 0, thereby obtaining the DC-side stability criterion.

[0093] The second stability criterion module includes:

[0094] The third calculation unit is used to calculate the second-order partial derivative of the current potential function with respect to the current variable in the mixed potential function of each transformer area.

[0095] The fourth calculation unit is used to calculate the second-order partial derivative of the voltage potential function with respect to the voltage variable in the mixed potential function of each transformer area;

[0096] The second stability criterion acquisition unit is used to ensure that the sum of the minimum eigenvalue of the second-order partial derivative of the current variable and the minimum eigenvalue of the second-order partial derivative of the voltage variable is greater than 0, thereby obtaining the stability criteria for each transformer area.

[0097] The third embodiment of the present invention relates to an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the large disturbance stability analysis method for a flexible interconnected system according to the first embodiment.

[0098] The fourth embodiment of the present invention relates to a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the large disturbance stability analysis method for a flexible interconnected system according to the first embodiment.

[0099] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. The solutions in the embodiments of the present invention can be implemented using various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0100] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0101] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0102] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0103] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0104] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for analyzing the stability of a flexible interconnected system under large disturbances, characterized in that, Includes the following steps: Establish a simplified circuit model for the flexible interconnected system; Based on the simplified circuit model, the DC-side mixed potential function and the mixed potential function for each transformer area are constructed; the DC-side mixed potential function is expressed as follows: The mixed potential function of each transformer area is expressed as: ;in, The DC-side mixed potential function is... Indicates the DC side voltage. This represents the DC-side current of the Kth transformer substation. This indicates the power of a constant power load. Represents the resistance of a constant impedance load. For the first The mixed potential function of each transformer area This represents the equivalent resistance between the converter and the power grid. Indicates the first The current of the converter Indicates the first The voltage of the converter; The DC-side stability criterion is obtained based on the DC-side mixed potential function. Based on the mixed potential function of each transformer area, the stability criteria of each transformer area under the influence of the DC side are obtained; The DC-side stability criterion and the stability criteria of each transformer area are combined to obtain the large-signal stability criterion of the flexible interconnection system.

2. The method for analyzing the stability of a flexible interconnected system under large disturbances according to claim 1, characterized in that, When establishing a simplified circuit model for the flexible interconnection system, the transformer substation is equivalent to a DC system, and the DC-side equipment is equivalent to a constant power load, a constant current load, or a constant impedance load according to the control strategy.

3. The method for analyzing the stability of a flexible interconnected system under large disturbances according to claim 1, characterized in that, The DC-side stability criterion obtained based on the DC-side mixed potential function is specifically as follows: Calculate the second-order partial derivative of the current potential function with respect to the current variable in the DC-side hybrid potential function; Calculate the second-order partial derivative of the voltage potential function with respect to the voltage variable in the DC-side hybrid potential function; By ensuring that the sum of the minimum eigenvalues ​​of the second-order partial derivatives of the current variable and the second-order partial derivatives of the voltage variable is greater than 0, the DC-side stability criterion is obtained.

4. The method for analyzing the stability of a flexible interconnected system under large disturbances according to claim 1, characterized in that, The stability criterion for each transformer area under the influence of the DC side, obtained based on the mixed potential function of each transformer area, is as follows: Calculate the second-order partial derivative of the current potential function with respect to the current variable in the mixed potential function of each transformer area; Calculate the second-order partial derivative of the voltage potential function with respect to the voltage variable in the mixed potential function of each transformer area; By ensuring that the sum of the minimum eigenvalues ​​of the second-order partial derivatives of the current variable and the second-order partial derivatives of the voltage variable is greater than 0, the stability criteria for each transformer substation are obtained.

5. A device for analyzing the stability of a flexible interconnected system under large disturbances, characterized in that, include: A module is established to create a simplified circuit model for flexible interconnected systems. The construction module is used to construct the DC-side mixed potential function and the mixed potential function of each transformer area based on the simplified circuit model; the DC-side mixed potential function is expressed as: The mixed potential function of each transformer area is expressed as: ;in, The DC-side mixed potential function is... Indicates the DC side voltage. This represents the DC-side current of the Kth transformer substation. This indicates the power of a constant power load. Represents the resistance of a constant impedance load. For the first The mixed potential function of each transformer area This represents the equivalent resistance between the converter and the power grid. Indicates the first The current of the converter Indicates the first The voltage of the converter; The first stability criterion module is used to obtain the DC-side stability criterion based on the DC-side mixed potential function. The second stability criterion module is used to obtain the stability criterion of each transformer area under the influence of the DC side based on the mixed potential function of each transformer area. The merging module is used to merge the DC-side stability criterion and the stability criterion of each transformer area to obtain the large-signal stability criterion of the flexible interconnection system.

6. The large disturbance stability analysis device for flexible interconnected systems according to claim 5, characterized in that, When establishing a simplified circuit model of the flexible interconnection system, the module equates the transformer area to a DC system and the DC-side equipment to a constant power load, constant current load, or constant impedance load according to the control strategy.

7. The large disturbance stability analysis device for flexible interconnected systems according to claim 5, characterized in that, The first stability criterion module includes: The first calculation unit is used to calculate the second-order partial derivative of the current potential function with respect to the current variable in the DC-side hybrid potential function; The second calculation unit is used to calculate the second-order partial derivative of the voltage potential function with respect to the voltage variable in the DC-side hybrid potential function; The first stability criterion acquisition unit is used to ensure that the sum of the minimum eigenvalue of the second-order partial derivative of the current variable and the minimum eigenvalue of the second-order partial derivative of the voltage variable is greater than 0, thereby obtaining the DC-side stability criterion.

8. The large disturbance stability analysis device for flexible interconnected systems according to claim 5, characterized in that, The second stability criterion module includes: The third calculation unit is used to calculate the second-order partial derivative of the current potential function with respect to the current variable in the mixed potential function of each transformer area. The fourth calculation unit is used to calculate the second-order partial derivative of the voltage potential function with respect to the voltage variable in the mixed potential function of each transformer area; The second stability criterion acquisition unit is used to ensure that the sum of the minimum eigenvalue of the second-order partial derivative of the current variable and the minimum eigenvalue of the second-order partial derivative of the voltage variable is greater than 0, thereby obtaining the stability criteria for each transformer area.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the large disturbance stability analysis method for flexible interconnected systems as described in any one of claims 1-4.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the large disturbance stability analysis method for flexible interconnected systems as described in any one of claims 1-4.

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