A decoupling simulation method for a power system and related devices

Abstract

The present invention discloses a decoupled simulation method for a power system and related devices. When constructing the subsystem state space model and the main system node voltage model, the present invention uses the boundary node voltage on the main system side as the voltage source voltage of the Thevenin equivalent circuit on the subsystem side, and uses the VSC branch current as the boundary node current on the main system side, which is used as the current source current of the Norton equivalent circuit on the main system side. During decoupled simulation, the subsystem state space model is solved to obtain the boundary node current on the main system side at the next moment. The boundary node current on the main system side at the next moment updates the current source current in the main system model. The updated main system model is solved to obtain the boundary node voltage on the subsystem side at the next moment. The boundary node voltage on the subsystem side at the next moment updates the voltage source voltage of the subsystem state model, thereby realizing the decoupled simulation of the power system, and there is no delay error in this method, improving the accuracy of the simulation.

Description

Technical Field

[0001] The present invention relates to a decoupling simulation method for a power system and related devices, belonging to the field of electromagnetic transient simulation. Background Art

[0002] A large-scale power electronic power system introduces a large number of switching devices, greatly increasing the computational pressure within a single simulation step. The research on modeling methods for a single power electronic converter alone is not sufficient to meet the real-time simulation requirements of the overall system, and real-time performance can only be achieved through parallel computing on multiple different simulation platforms.

[0003] The first step in implementing parallel simulation is to decouple the system by dividing the total system model into multiple subsystems for parallel solution. The decoupling of traditional power systems generally uses the propagation delay of transmission lines to decompose the system into different subsystems, but there will be delays between the decoupled subsystems.

[0004] Some scholars have proposed a method based on multi-port Thevenin equivalent (Multi-area Thevenin Equivalent, MATE), and some scholars have also proposed a method based on latency insertion method (LIM). By performing staggered calculations on branch currents and node voltages at different time nodes and alternately updating the calculated current and voltage values. However, this method has intermediate steps and has special requirements for the topological structure of the subsystem: that is, the branch must contain an inductor and the node must contain a capacitance to ground.

[0005] In summary, the parallel simulation of real-time simulation of a power electronic power system needs to be calculated in two steps by inserting delays or splitting nodes to achieve the purpose of decoupling, but this method has delay errors. Especially in the case of faults, the system current changes sharply, which easily causes oscillations in the simulation and affects the simulation accuracy and stability of the system during transient operation. Summary of the Invention

[0006] The present invention provides a decoupling simulation method for a power system and related devices, which solves the problems disclosed in the background art.

[0007] According to one aspect of the present disclosure, there is provided a decoupling simulation method for a power system, including:

[0008] Taking the connection node between the VSC branch and the AC system as the demarcation node, dividing the power system into a main system and a subsystem; wherein, the main system is the system where the AC system is located, and the subsystem is the system where the VSC branch is located;

[0009] Taking the boundary node voltage on the main system side as the voltage source voltage of the Thevenin equivalent circuit on the subsystem side, a subsystem state space model is constructed. Taking the VSC branch current as the boundary node current on the main system side and the boundary node current on the main system side as the current source current of the Norton equivalent circuit on the main system side, a main system node voltage model is constructed.

[0010] According to the subsystem state space model and the main system node voltage model, power system decoupling simulation is carried out. Among them, in the decoupling simulation, the boundary node current on the main system side at the next moment is obtained by solving the subsystem state space model, the current source current in the main system model is updated according to the boundary node current on the main system side at the next moment, the main system model is solved, the boundary node voltage on the subsystem side at the next moment is obtained, and the voltage source voltage of the subsystem state model is updated according to the boundary node voltage on the subsystem side at the next moment.

[0011] In some embodiments of the present disclosure, the subsystem state space model is the state space equation of the subsystem, and the backward Euler method is used for discrete solution; the main system node voltage model is the node voltage equation of the main system, and the trapezoidal method is used for discrete solution.

[0012] In some embodiments of the present disclosure, the boundary node current on the main system side at the next moment is only related to the current source current at the current moment and the output voltage on the main system side at the next moment. The formula is:

[0013] i Nodal (k + 1) = i eq (k) + a 11 v1(k + 1)

[0014] In the formula, i Nodal (k + 1) is the boundary node current on the main system side at the k + 1 moment, i eq (k) is the current source current at the k moment, a 11 is the circuit topology coefficient of the main system, and v1(k + 1) is the output voltage of the main system at the k + 1 moment.

[0015] In some embodiments of the present disclosure, the boundary node voltage on the subsystem side at the next moment is only related to the voltage source voltage at the current moment and the output current on the subsystem side at the next moment; the formula is:

[0016] v Nodal (k + 1) = v eq (k) + a 22 i2(k + 1)

[0017] In the formula, v Nodal (k + 1) is the boundary node voltage on the subsystem side at the k + 1 moment, v eq (k) is the voltage source voltage at the k moment, a 22is the circuit topology coefficient of the subsystem, and i2(k + 1) is the output current on the subsystem side at the (k + 1)-th moment.

[0018] According to another aspect of the present disclosure, there is provided a power system decoupling simulation device, including:

[0019] A splitting module that takes the connection node between the VSC branch and the AC system as the demarcation node and divides the power system into a main system and a subsystem; wherein, the main system is the system where the AC system is located, and the subsystem is the system where the VSC branch is located;

[0020] A construction module that takes the demarcation node voltage on the main system side as the voltage source voltage of the Thevenin equivalent circuit on the subsystem side, constructs a subsystem state space model, takes the VSC branch current as the demarcation node current on the main system side, and takes the demarcation node current on the main system side as the current source current of the Norton equivalent circuit on the main system side, and constructs a main system node voltage model;

[0021] A simulation module that performs power system decoupling simulation according to the subsystem state space model and the main system node voltage model; wherein, in the decoupling simulation, the demarcation node current on the main system side at the next moment is obtained by solving the subsystem state space model, the current source current in the main system model is updated according to the demarcation node current on the main system side at the next moment, the main system model is solved to obtain the demarcation node voltage on the subsystem side at the next moment, and the voltage source voltage of the subsystem state model is updated according to the demarcation node voltage on the subsystem side at the next moment.

[0022] In some embodiments of the present disclosure, the subsystem state space model is the state space equation of the subsystem, and the backward Euler method is used for discrete solution; the main system node voltage model is the node voltage equation of the main system, and the trapezoidal method is used for discrete solution.

[0023] In some embodiments of the present disclosure, in the simulation module, the demarcation node current on the main system side at the next moment is only related to the current source current at the current moment and the output voltage on the main system side at the next moment, and the formula is:

[0024] i Nodal (k + 1) = i eq (k) + a 11 v1(k + 1)

[0025] In the formula, i Nodal (k + 1) is the demarcation node current on the main system side at the (k + 1)-th moment, i eq (k) is the current source current at the k-th moment, a 11 is the circuit topology coefficient of the main system, and v1(k + 1) is the output voltage of the main system at the (k + 1)-th moment.

[0026] In some embodiments of the present disclosure, in the simulation module, the voltage of the boundary node on the subsystem side at the next moment is only related to the voltage of the voltage source at the current moment and the output current on the subsystem side at the next moment; the formula is:

[0027] v Nodal (k + 1) = v eq (k) + a 22 i2(k + 1)

[0028] In the formula, v Nodal (k + 1) is the voltage of the boundary node on the subsystem side at the (k + 1)-th moment, v eq (k) is the voltage of the voltage source at the k-th moment, a 22 is the circuit topology coefficient of the subsystem, and i2(k + 1) is the output current on the subsystem side at the (k + 1)-th moment.

[0029] According to another aspect of the present disclosure, there is provided a computer-readable storage medium storing one or more programs, the one or more programs including instructions that, when executed by a computing device, cause the computing device to execute the power system decoupling simulation method.

[0030] According to another aspect of the present disclosure, there is provided a computer device including one or more processors and one or more memories, the one or more programs being stored in the one or more memories and configured to be executed by the one or more processors, the one or more programs including instructions for executing the power system decoupling simulation method.

[0031] The beneficial effects achieved by the present invention: When constructing the subsystem state space model and the main system node voltage model, the present invention uses the voltage of the boundary node on the main system side as the voltage source voltage of the Thevenin equivalent circuit on the subsystem side, and the VSC branch current as the boundary node current on the main system side, which is the current source current of the Norton equivalent circuit on the main system side. During decoupling simulation, the subsystem state space model is solved to obtain the boundary node current on the main system side at the next moment, and the boundary node current on the main system side at the next moment updates the current source current in the main system model. The updated main system model is solved to obtain the voltage of the boundary node on the subsystem side at the next moment, and the voltage of the boundary node on the subsystem side at the next moment updates the voltage source voltage of the subsystem state model, thereby realizing the decoupling simulation of the power system, and there is no delay error in this method, improving the accuracy of the simulation. Description of the Drawings

[0032] Figure 1 is a flowchart of the power system decoupling simulation method;

[0033] Figure 2 is a schematic diagram of the node decomposition method

[0034] Figure 3Schematic diagram of the decoupled simulation method for power systems;

[0035] Figure 4 Schematic diagram for solving the global solution based on the nodal analysis method;

[0036] Figure 5 Comparison chart of the simulation acceleration effects under different numbers of VSCs;

[0037] Figure 6 Block diagram of the decoupled simulation device for power systems. Specific implementation manners

[0038] Next, the technical solutions in the embodiments of the present disclosure will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way limits the present disclosure and its application or use. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present disclosure.

[0039] Unless otherwise specified, the relative arrangements of components and steps, numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present disclosure.

[0040] Meanwhile, it should be understood that for the sake of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationship.

[0041] For technologies, methods, and devices known to those of ordinary skill in the relevant art, detailed discussions may not be made, but where appropriate, the technologies, methods, and devices should be regarded as part of the specification.

[0042] In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0043] It should be noted that: similar symbols and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0044] To solve the problem of delay error existing in the existing decoupled simulation method, the present disclosure proposes a decoupled simulation method for power systems and related devices.

[0045] Figure 1 Schematic diagram of an embodiment of the decoupled simulation method for power systems of the present disclosure, Figure 1 The embodiments of can be executed by a simulation terminal.

[0046] As Figure 1 shown, in Step 1 of the embodiment, the connection node between the VSC branch and the AC system is taken as the demarcation node, and the power system is divided into a main system and a subsystem; among them, the main system is the system where the AC system is located, and the subsystem is the system where the VSC branch is located.

[0047] It should be noted that, as Figure 2 shown, the connection node between the VSC branch (i.e., the branch where the VSC is located) and the power system is the place with the least coupling information. Therefore, when decomposing the power system, the connection point is taken as the demarcation node, so that the power system can be divided into the main system where the AC system is located and the subsystem where the VSC branch is located.

[0048] Return Figure 1 , in Step 2 of the embodiment, the voltage of the demarcation node on the main system side is used as the voltage source voltage of the Thevenin equivalent circuit on the subsystem side to construct a subsystem state space model, the VSC branch current is used as the current of the demarcation node on the main system side, and the current of the demarcation node on the main system side is used as the current source current of the Norton equivalent circuit on the main system side to construct a main system node voltage model.

[0049] It should be noted that during decoupled simulation, corresponding models need to be constructed for each split system. Since there are many switching nodes inside the subsystem, in some embodiments, a subsystem state space model is constructed for the subsystem. Specifically, the state space equation is written with the inductor current and capacitor voltage as state variables, which can effectively reduce the matrix order; while the main system has a complex structure and it is difficult to directly write the state space equation. Therefore, in some embodiments, a main system node voltage model is constructed for the main system. Specifically, it is the node voltage equation of the main system, and the node analysis method can be used to improve the simulation speed.

[0050] The two models can be expressed as:

[0051]

[0052] In the formula, is the derivative of the state variables of the main system and the subsystem, a 11 is the circuit topology coefficient of the main system, a 22 is the circuit topology coefficient of the subsystem, a 12 is the coupling coefficient between the circuits of the main system and the subsystem, a 21 is the coupling coefficient between the circuits of the subsystem and the main system, b1 is the input coefficient of the main system, b2 is the input coefficient of the subsystem, x1 and x2 are the state variables of the main system and the subsystem respectively, and u is the system input.

[0053] The subsystem state space model can be discretely solved using the backward Euler method, and the main system node voltage model can be solved by discrete using the trapezoidal method, and we can get:

[0054]

[0055] where T s is the simulation step size, x1(k) and x1(k - 1) are the main system state variables at time k and k - 1 respectively, x2(k) and x2(k - 1) are the subsystem state variables at time k and k - 1 respectively, and u(k - 1) and u(k) are the system inputs at time k - 1 and k respectively.

[0056] After rearranging the above equation, we can get:

[0057]

[0058] In the formula, the value of x2(k) can be substituted into x1(k). From the rearranged formula, it can be seen that to solve x2(k), only x1(k - 1) and x2(k - 1) at the previous moment are needed, and the value of x1(k) is not required. At the same time, x1(k) only needs the value at the previous moment of the VSC branch to perform the calculation. Therefore, decoupling can be achieved without inserting a delay between the subsystem and the main system.

[0059] Return Figure 1 , step 3 of the embodiment, perform power system decoupling simulation according to the subsystem state - space model and the main system node voltage model; wherein, in the decoupling simulation, solve the subsystem state - space model to obtain the boundary node current on the main system side at the next moment, update the current source current in the main system model according to the boundary node current on the main system side at the next moment, solve the main system model to obtain the boundary node voltage on the subsystem side at the next moment, and update the voltage source voltage of the subsystem state model according to the boundary node voltage on the subsystem side at the next moment.

[0060] It should be noted that, since the boundary node voltage on the main system side is used as the voltage source voltage of the Thevenin equivalent circuit on the subsystem side, the VSC branch current is used as the boundary node current on the main system side, and the boundary node current on the main system side is used as the current source current of the Norton equivalent circuit on the main system side, we can get:

[0061]

[0062] where i Nodal (k) is the boundary node current on the main system side at time k, v Nodal (k) is the boundary node voltage on the subsystem side at time k, i Nodal (k - 1) is the boundary node current on the main system side at time k - 1, v Nodal (k - 1) is the boundary node voltage on the subsystem side at time k - 1, v1(k) is the output voltage of the main system at time k, i2(k) is the output current on the subsystem side at time k, ANodal is the impedance matrix coefficient at the boundary node, A Nd_1 is the coupling coefficient between the main system and the boundary node current, A Nd_2 is the coupling coefficient between the subsystem and the boundary node voltage.

[0063] Take the historical terms at time k-1 as known quantities, i.e.:

[0064]

[0065] In the formula, i eq (k-1) is the current source current at time k-1, v eq (k-1) is the voltage source voltage at time k-1.

[0066] Then the above formula can be rewritten as:

[0067]

[0068] Assume the current time is k, then based on the above formula, we can get:

[0069] i Nodal (k+1) = i eq (k) + a 11 v1(k+1)

[0070] v Nodal (k+1) = v eq (k) + a 22 i2(k+1)

[0071] In the formula, i Nodal (k+1) is the boundary node current on the main system side at time k+1, i eq (k) is the current source current at time k, v1(k+1) is the output voltage of the main system at time k+1, v Nodal (k+1) is the boundary node voltage on the subsystem side at time k+1, v eq (k) is the voltage source voltage at time k, i2(k+1) is the output current on the subsystem side at time k+1.

[0072] It can be seen from the above formula that the boundary node current on the main system side at the next moment is only related to the current source current at the current moment and the output voltage of the main system at the next moment, and the boundary node voltage on the subsystem side at the next moment is only related to the voltage source voltage at the current moment and the output current of the subsystem at the next moment. Therefore, the current source and the main system can be calculated on the same simulation platform, and the voltage source and the subsystem can be calculated on the same simulation platform to achieve parallel simulation.

[0073] The principle of the above power system decoupling simulation method can be as Figure 3 and 4As shown in the figure, in the figure, I = GV + I history is the equation of the main system nodal analysis method, i j (k + 1) = f(v j (k), v con (k)); where, I is the VSC branch, V is the boundary node voltage, G is the main system admittance matrix, I history is the current history term, v j (k) is the j-phase voltage on the subsystem side at time k, v con (k) is the j-phase output voltage on the AC side of the converter at time k, i j (k + 1) is the j-phase current on the main system side at time k + 1.

[0074] To verify the efficiency of the method proposed in this paper, a comparison was made with a reference model without using the above decoupling method under different numbers of VSCs. The comparison results are as Figure 5 shown. Among them, the simulation time of the decoupling model is used as the reference value (p.u. value). When the number of VSCs reaches 50, the above method increases the simulation speed by nearly 180 times, thus indicating that this method is suitable for the parallel simulation of large-scale power electronic power systems.

[0075] The above method realizes the decoupled simulation of the power system, and there is no delay error, improving the simulation accuracy. At the same time, this method can be applied to the parallel simulation of large-scale power electronic power systems.

[0076] Figure 6 is a schematic diagram of an embodiment of the power system decoupled simulation device of the present disclosure. Figure 6 The embodiment is a virtual device that can be loaded and executed by a simulation terminal (such as a computer), and includes a splitting module, a construction module, and a simulation module.

[0077] The splitting module of the embodiment is configured to use the connection node between the VSC branch and the AC system as the boundary node to divide the power system into a main system and a subsystem; where, the main system is the system where the AC system is located, and the subsystem is the system where the VSC branch is located.

[0078] It should be noted that the connection node between the VSC branch (i.e., the branch where the VSC is located) and the power system has the least coupling information. Therefore, when decomposing the power system, the connection point is used as the boundary node, so that the power system can be divided into the main system where the AC system is located and the subsystem where the VSC branch is located.

[0079] The construction module of the embodiment is configured to construct a subsystem state space model by using the boundary node voltage on the main system side as the voltage source voltage of the Thevenin equivalent circuit on the subsystem side, and use the VSC branch current as the boundary node current on the main system side and the boundary node current on the main system side as the current source current of the Norton equivalent circuit on the main system side to construct a main system node voltage model.

[0080] In the written embodiment, the subsystem state space model is the state space equation of the subsystem, and the backward Euler method is used for discrete solution; the main system node voltage model is the node voltage equation of the subsystem, and the trapezoidal method is used for discrete solution.

[0081] The simulation module of the embodiment is configured to perform a decoupled simulation of the power system according to the subsystem state space model and the main system node voltage model; wherein, in the decoupled simulation, the boundary node current on the main system side at the next moment is obtained by solving the subsystem state space model, the current source current in the main system model is updated according to the boundary node current on the main system side at the next moment, the main system model is solved to obtain the boundary node voltage on the subsystem side at the next moment, and the voltage source voltage of the subsystem state model is updated according to the boundary node voltage on the subsystem side at the next moment.

[0082] In some embodiments, in the simulation module, the boundary node current on the main system side at the next moment is only related to the current source current at the current moment and the output voltage on the main system side at the next moment; the boundary node voltage on the subsystem side at the next moment is only related to the voltage source voltage at the current moment and the output current on the subsystem side at the next moment; the formula is:

[0083] i Nodal (k + 1) = i eq (k) + a 11 v1(k + 1)

[0084] v Nodal (k + 1) = v eq (k) + a 22 i2(k + 1)

[0085] In the formula, i Nodal (k + 1) is the boundary node current on the main system side at the k + 1 moment, i eq (k) is the current source current at the k moment, a 11 is the circuit topology coefficient of the main system, v1(k + 1) is the output voltage of the main system at the k + 1 moment, v Nodal (k + 1) is the boundary node voltage on the subsystem side at the k + 1 moment, v eq (k) is the voltage source voltage at the k moment, a 22 is the circuit topology coefficient of the subsystem, and i2(k + 1) is the output current on the subsystem side at the k + 1 moment.

[0086] Similar to the above method, the above device realizes the decoupled simulation of the power system, has no delay error, improves the simulation accuracy, and at the same time, this method is applicable to the parallel simulation of large-scale power electronic power systems.

[0087] Based on the same technical solution, the present disclosure also relates to a computer-readable storage medium storing one or more programs, the one or more programs including instructions that, when executed by a computing device, cause the computing device to execute the power system decoupled simulation method.

[0088] Based on the same technical solution, the present disclosure also relates to a computer device including one or more processors and one or more memories, the one or more programs being stored in the one or more memories and configured to be executed by the one or more processors, the one or more programs including instructions for executing the power system decoupled simulation method.

[0089] Those skilled in the art should understand that the embodiments of the present invention may be provided as a method, a system, or a computer program product. Therefore, the present invention may take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories, CD-ROMs, optical memories, etc.) containing computer-usable program code.

[0090] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of flows and / or blocks in the flowcharts and / or block diagrams, can be realized by computer program instructions. These computer program instructions can be provided to the processors of general-purpose computers, special-purpose computers, embedded processors, or other programmable data processing devices to generate a machine, such that the instructions executed by the processors of the computer or other programmable data processing devices generate a device for realizing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0091] These computer program instructions can also be stored in a computer-readable memory capable of guiding a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, the instruction device realizing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0092] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus, so that a series of operation steps are executed on the computer or other programmable apparatus to generate a computer-implemented process, thereby the instructions executed on the computer or other programmable apparatus provide steps for implementing the functions specified in one process or a plurality of processes and / or blocks Figure 1 one process or a plurality of processes and / or blocks Figure 1 in one block or a plurality of blocks.

[0093] The above are only embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included in the scope of the claims of the present invention pending approval of the application.

Claims

1. A decoupling simulation method for a power system, characterized in that, including: Taking the connection node between the VSC branch and the AC system as the demarcation node, dividing the power system into a main system and a subsystem; wherein, the main system is the system where the AC system is located, and the subsystem is the system where the VSC branch is located; Taking the voltage of the demarcation node on the main system side as the voltage source voltage of the Thevenin equivalent circuit on the subsystem side, constructing the subsystem state space model, taking the VSC branch current as the demarcation node current on the main system side, and taking the demarcation node current on the main system side as the current source current of the Norton equivalent circuit on the main system side, constructing the main system node voltage model; According to the subsystem state space model and the main system node voltage model, perform decoupled simulation of the power system; wherein, in the decoupled simulation, solve the subsystem state space model to obtain the demarcation node current on the main system side at the next moment, update the current source current in the main system model according to the demarcation node current on the main system side at the next moment, solve the main system model, obtain the demarcation node voltage on the subsystem side at the next moment, and update the voltage source voltage of the subsystem state model according to the demarcation node voltage on the subsystem side at the next moment; the demarcation node current on the main system side at the next moment is only related to the current source current at the current moment and the output voltage on the main system side at the next moment; the demarcation node voltage on the subsystem side at the next moment is only related to the voltage source voltage at the current moment and the output current on the subsystem side at the next moment.

2. The power system decoupling simulation method according to claim 1, wherein The subsystem state space model is the state space equation of the subsystem, and the backward Euler method is used for discrete solution; the main system node voltage model is the node voltage equation of the main system, and the trapezoidal method is used for discrete solution.

3. The power system decoupling simulation method according to claim 1 or 2, characterized in that, The demarcation node current on the main system side at the next moment, the formula is: i Nodal (k + 1) = i eq (k) + a 11 v1(k + 1) where i Nodal (k + 1) is the boundary node current on the main system side at time k + 1, and i eq (k) is the current source current at time k, a 11 is the circuit topology coefficient of the main system, and v1(k + 1) is the output voltage of the main system at time k + 1.

4. The power system decoupling simulation method according to claim 1 or 2, characterized in that The demarcation node voltage on the subsystem side at the next moment, the formula is: v Nodal (k + 1)= v eq (k)+ a 22 i2(k + 1) where, v Nodal (k + 1) is the sub-system side boundary node voltage at the (k + 1)-th moment, v eq (k) is the voltage source voltage at the k-th moment, a 22 is the circuit topology coefficient of the sub-system, and i2(k + 1) is the output current on the sub-system side at the (k + 1)-th moment.

5. A decoupling simulation device for a power system, characterized in that, including: A splitting module, taking the connection node between the VSC branch and the AC system as the demarcation node, dividing the power system into a main system and a subsystem; wherein, the main system is the system where the AC system is located, and the subsystem is the system where the VSC branch is located; A construction module, taking the voltage of the demarcation node on the main system side as the voltage source voltage of the Thevenin equivalent circuit on the subsystem side, constructing the subsystem state space model, taking the VSC branch current as the demarcation node current on the main system side, and taking the demarcation node current on the main system side as the current source current of the Norton equivalent circuit on the main system side, constructing the main system node voltage model; A simulation module, according to the subsystem state space model and the main system node voltage model, perform decoupled simulation of the power system; wherein, in the decoupled simulation, solve the subsystem state space model to obtain the demarcation node current on the main system side at the next moment, update the current source current in the main system model according to the demarcation node current on the main system side at the next moment, solve the main system model, obtain the demarcation node voltage on the subsystem side at the next moment, and update the voltage source voltage of the subsystem state model according to the demarcation node voltage on the subsystem side at the next moment; the demarcation node current on the main system side at the next moment is only related to the current source current at the current moment and the output voltage on the main system side at the next moment; the demarcation node voltage on the subsystem side at the next moment is only related to the voltage source voltage at the current moment and the output current on the subsystem side at the next moment.

6. The power system decoupling simulation device according to claim 5, characterized in that, The subsystem state space model is the state space equation of the subsystem, and the backward Euler method is used for discrete solution; the main system node voltage model is the node voltage equation of the main system, and the trapezoidal method is used for discrete solution.

7. The power system decoupling simulation device according to claim 5 or 6, characterized in that, In the simulation module, the current at the boundary node on the main system side at the next moment is given by the formula: i Nodal (k + 1) = i eq (k) + a 11 v1(k + 1) where i Nodal (k + 1) is the boundary node current on the main system side at the (k + 1)-th moment, and i eq (k) is the current source current at the k-th moment, a 11 is the circuit topology coefficient of the main system, and v1(k + 1) is the output voltage of the main system at the (k + 1)-th moment.

8. The power system decoupling simulation device according to claim 5 or 6, characterized in that, In the simulation module, the voltage at the boundary node on the subsystem side at the next moment is given by the formula: v Nodal (k + 1) = v eq (k) + a 22 i2(k + 1) where, v Nodal (k + 1) is the sub-system side boundary node voltage at the (k + 1)-th moment, v eq (k) is the voltage source voltage at the k-th moment, a 22 is the circuit topology coefficient of the sub-system, and i2(k + 1) is the output current on the sub-system side at the (k + 1)-th moment.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores one or more programs, and the one or more programs include instructions that, when executed by a computing device, cause the computing device to perform the method according to any one of claims 1 to 4.

10. A computer device, characterized in that, Comprising: One or more processors and one or more memories, the one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, and the one or more programs include instructions for performing the method according to any one of claims 1 to 4.

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