Multi-device transient interaction analysis method for new energy flexible direct delivery system

Abstract

The invention provides a multi-device transient interaction analysis method of a new energy flexible direct output system, and relates to the technical field of transient stability analysis and discrimination of a new energy power system, and the method comprises the steps: constructing a system nonlinear mathematical model; constructing a differential equation of the system based on the nonlinear mathematical model of the system, and constructing an objective function to solve an unstable equilibrium point of the differential equation; determining a dominant unstable equilibrium point of the system under the fault based on the unstable equilibrium point; based on the dominant unstable equilibrium point and a system Jacobian matrix, calculating participation factors of different state variables to the dominant unstable equilibrium point, quantitatively analyzing the participation degrees of different links or devices participating in system transient dynamic according to the sizes of the participation factors, and determining links or devices of dominant transient synchronization. And the interaction between different links or devices is quantitatively analyzed. According to the method, the capability of quantitative calculation of the multi-device transient interaction strength of the new energy flexible direct delivery system can be practically improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of transient stability analysis and identification of new energy power systems, and in particular to a method for analyzing transient interactions of multiple devices in a new energy flexible direct current transmission system. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art.

[0003] In recent years, a large number of new energy power generation equipment represented by wind power and photovoltaic power generation have been connected to the power grid through voltage source converters, which has increased the penetration rate of power electronic devices in the power grid. Since large-scale new energy bases are far away from the load center, the flexible direct current transmission technology is currently a more appropriate solution to transmit large-scale new energy. However, the lack of supporting synchronous power supply at the power grid of new energy sending end, strong interaction of multiple power electronic equipment, complex power grid structure and changeable operation mode are the characteristics of typical power electronic power system. It has complex transient stability mechanism and difficult to analyze the interaction of multiple power electronic equipment, which seriously threatens the safety of the power grid at the sending end and the reliable absorption of new energy.

[0004] In order to ensure the safety of the power grid at the sending end and the reliable consumption of new energy, the existing technology has been studied in the field of small disturbance stability analysis and transient analysis. In the field of small disturbance stability analysis, the dominant link of the new energy converter has been analyzed based on the state space modeling or impedance modeling method. For transient stability analysis, a small number of studies have conducted dominant research on the nonlinear model of the new energy converter based on the singular perturbation theory. However, when the time constants (or bandwidths) of different controllers are close, the singular perturbation theory is at risk of failure. Therefore, it is necessary to further study the transient dominant link of the new energy converter. At present, some studies believe that PLL dynamics is the dominant link of VSC transient stability. Therefore, based on the second-order equation that only considers PLL dynamics, some studies use EAC, energy function, Lyapunov function and other methods to analyze the transient synchronous stability of the single VSC grid-connected system. Another part of the study believes that the power balance dynamics on the DC capacitor dominates the transient synchronization process of the VSC, so a second-order model that only considers DC capacitor dynamics and DC voltage control is established, and transient synchronous stability analysis is carried out on this basis.

[0005] However, the above two models are based on physical intuition and ignore the coupling between links. The theoretical basis is relatively weak, lacking quantitative analysis and theoretical support for the contribution of different links to transient processes. Therefore, due to the lack of clear understanding of the transient characteristics of multiple devices in the flexible direct current transmission system of new energy, especially the lack of clear understanding of the transient interaction of multiple links, the transient interaction of multiple devices, and the size of the interaction, the existing analysis methods cannot characterize the interaction between multiple devices in the system, and lack analytical calculation methods and corresponding quantitative evaluation indicators. Summary of the invention

[0006] In order to solve the above problems, the present invention proposes a method for analyzing transient interactions of multiple devices in a new energy via flexible direct current transmission system. Aiming at the scenario of a new energy via flexible direct current transmission system, the method quantitatively determines the dominant links and equipment that dominate the transient stability of the system under severe faults, calculates the intensity of transient interactions of multiple devices, and guides the transient stability enhancement and improvement control strategy of the new energy via flexible direct current transmission system.

[0007] According to some embodiments, the present disclosure adopts the following technical solutions:

[0008] The transient interaction analysis method of multiple devices in the flexible direct current transmission system of renewable energy includes:

[0009] According to the topological structure and relevant parameters of the new energy transmission system through flexible direct current, a nonlinear mathematical model of the system is constructed. The nonlinear mathematical model of the system includes the nonlinear mathematical model of the new energy equipment and the nonlinear mathematical model of the flexible direct current equipment.

[0010] The differential equation of the system is constructed based on the nonlinear mathematical model of the system. The differential equation of the system is used as a constraint condition, and the objective function is constructed with the minimum sum of the squares of the voltage difference and the current difference as the goal to obtain the unstable equilibrium point of the differential equation of the system.

[0011] Based on the unstable equilibrium point, the system Jacobian matrix and the post-fault system trajectory, determining the dominant unstable equilibrium point of the system under the fault from the unstable equilibrium point;

[0012] Based on the dominant unstable equilibrium point and the Jacobian matrix of the system, the participation factors of different state variables to the dominant unstable equilibrium point are calculated to obtain the participation factors of each state variable. According to the size of the participation factor of each state variable, the participation degree of different links or equipment in the transient dynamics of the system is quantitatively analyzed. According to the participation degree of different links or equipment in the transient dynamics of the system, the link or equipment that dominates the transient synchronization is determined, thereby quantitatively analyzing the size of the interaction between different links or equipment.

[0013] According to some embodiments, the present disclosure adopts the following technical solutions:

[0014] The transient interaction analysis system of multiple devices in the flexible direct current transmission system of new energy includes:

[0015] A model building module is used to build a nonlinear mathematical model of the system according to the topological structure and related parameters of the new energy transmission system through flexible direct current. The nonlinear mathematical model of the system includes the nonlinear mathematical model of the new energy equipment and the nonlinear mathematical model of the flexible direct current equipment.

[0016] The optimization solution module is used to construct the differential equation of the system based on the nonlinear mathematical model of the system, take the differential equation of the system as the constraint condition, construct the objective function with the minimum sum of the square of the voltage difference and the current difference as the goal, and obtain the unstable equilibrium point of the differential equation of the system;

[0017] Based on the unstable equilibrium point, the system Jacobian matrix and the post-fault system trajectory, determining the dominant unstable equilibrium point of the system under the fault from the unstable equilibrium point;

[0018] The quantitative analysis module is used to calculate the participation factors of different state variables to the dominant unstable equilibrium point based on the dominant unstable equilibrium point and the system Jacobian matrix to obtain the participation factors of each state variable. According to the size of the participation factor of each state variable, the participation degree of different links or equipment in the transient dynamics of the system is quantitatively analyzed. According to the participation degree of different links or equipment in the transient dynamics of the system, the link or equipment that dominates the transient synchronization is determined, thereby quantitatively analyzing the size of the interaction between different links or equipment.

[0019] According to some embodiments, the present disclosure adopts the following technical solutions:

[0020] A non-transitory computer-readable storage medium is used to store computer instructions. When the computer instructions are executed by a processor, the method for analyzing transient interactions of multiple devices in a new energy flexible direct current transmission system is implemented.

[0021] According to some embodiments, the present disclosure adopts the following technical solutions:

[0022] An electronic device comprises: a processor, a memory and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory so that the electronic device executes the method for analyzing transient interactions of multiple devices in the new energy flexible direct current transmission system.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The method for analyzing transient interactions of multiple devices in a new energy via flexible direct current transmission system disclosed in the present invention obtains the topological structure and related parameters of the new energy via flexible direct current transmission system, establishes nonlinear mathematical models of the new energy equipment and the flexible direct current equipment respectively, and then constructs a nonlinear mathematical model of the system. The mathematical model used is accurate, the calculation process is clear, and the calculation of the quantitative indicators given is simple, which is easy for engineering personnel to understand and master, and is convenient for the engineering and field applications of existing large-scale new energy via flexible direct current transmission systems.

[0025] The method for analyzing transient interaction of multiple devices in a new energy via flexible direct current transmission system disclosed in the present invention calculates participation factors of different state variables to the dominant unstable equilibrium point based on the dominant unstable equilibrium point and the system Jacobian matrix, and quantitatively analyzes the degree of participation of different links or devices in the transient dynamics of the system according to the size of the participation factor, determines the link or device that dominates transient synchronization, and quantitatively analyzes the size of the interaction between different links or devices. The transient interaction intensity index of the new energy via flexible direct current transmission system provided by the present invention has fast calculation speed, high accuracy and strong credibility, which is very beneficial to the online real-time quantitative evaluation and calculation of the transient stability of the new energy via flexible direct current transmission system. It can also be used for theoretical research on the influence mechanism of specific fault types on the transient interaction of large-scale new energy via flexible direct current transmission system, quantitatively determine the key equipment and links that determine the transient stability of the system, and then propose corresponding transient stability enhancement control strategies in a targeted manner. On the whole, it can effectively improve the transient stability evaluation and improvement capabilities of large-scale new energy via flexible direct current transmission system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings constituting a part of the present disclosure are used to provide a further understanding of the present disclosure. The illustrative embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation on the present disclosure.

[0027] Figure 1 It is a flow chart of a method for analyzing transient interactions of multiple devices in a new energy flexible direct current transmission system according to an embodiment of the present disclosure;

[0028] Figure 2 This is a network topology diagram of the new energy flexible direct current transmission system of the embodiment of the present disclosure. DETAILED DESCRIPTION

[0029] The present disclosure is further described below in conjunction with the accompanying drawings and embodiments.

[0030] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanation of the present disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present disclosure belongs.

[0031] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0032] Example 1

[0033] In one embodiment of the present disclosure, a method for analyzing transient interaction of multiple devices in a new energy flexible direct current transmission system is provided, including four steps: system modeling, equilibrium point calculation, determination of dominant unstable equilibrium point, and calculation of interaction factors between links / devices. The specific process steps include:

[0034] Step 1: According to the topological structure and relevant parameters of the new energy transmission system through flexible direct current, a nonlinear mathematical model of the system is constructed. The nonlinear mathematical model of the system includes the nonlinear mathematical model of the new energy equipment and the nonlinear mathematical model of the flexible direct current equipment;

[0035] Step 2: Construct the differential equation of the system based on the nonlinear mathematical model of the system, take the differential equation of the system as the constraint condition, construct the objective function with the minimum sum of the square of the voltage difference and the current difference as the goal, and find the unstable equilibrium point of the differential equation of the system;

[0036] Step 3: Based on the unstable equilibrium point, the system Jacobian matrix and the post-fault system trajectory, determine the dominant unstable equilibrium point of the system under the fault from the unstable equilibrium points;

[0037] Step 4: Based on the dominant unstable equilibrium point and the Jacobian matrix of the system, calculate the participation factors of different state variables to the dominant unstable equilibrium point to obtain the participation factors of each state variable. According to the size of the participation factor of each state variable, quantitatively analyze the participation degree of different links or equipment in the transient dynamics of the system. According to the participation degree of different links or equipment in the transient dynamics of the system, determine the link or equipment that dominates the transient synchronization, thereby quantitatively analyzing the size of the interaction between different links or equipment.

[0038] As an embodiment, the present disclosure provides a method for analyzing transient interaction of multiple devices in a new energy flexible direct current transmission system, and the specific implementation process is as follows:

[0039] Step 1: Obtain the topological structure and related parameters of the flexible direct current transmission system for new energy, establish nonlinear mathematical models of new energy equipment and flexible direct current equipment respectively, and then construct a nonlinear mathematical model of the system;

[0040] Specifically, the modeling of the nonlinear mathematical model of the large-scale renewable energy via flexible direct current transmission system is mainly to establish the nonlinear mathematical model of the renewable energy via flexible direct current transmission system by acquiring relevant data such as the controller parameters of the renewable energy equipment and the flexible direct current equipment in the flexible direct current transmission system, the system operating conditions and the transmission line impedance of the power network.

[0041] Furthermore, according to the topological structure and relevant parameters of the flexible direct current transmission system for renewable energy, a nonlinear mathematical model of the flexible direct current equipment is established, including: according to the dynamics of DC capacitors, DC voltage control, and virtual synchronization and control dynamics in the flexible direct current transmission system for renewable energy, a nonlinear mathematical model of the flexible direct current sending end converter station in the flexible direct current transmission system for renewable energy is constructed;

[0042] Among them, the new energy equipment considers the dynamics of DC capacitors, DC voltage control and phase locked loop (PLL) dynamics. The nonlinear mathematical model of the new energy equipment in the new energy flexible DC transmission system is:

[0043]

[0044] Where · represents the differential of the variable with respect to time, i.e. d() / dt, x pll Respectively represent the angle of PLL output and the integrator output variable; x dvc ,u dc ,u ucref Represent the DC voltage control integrator output, DC voltage and DC voltage reference value respectively. p,pll ,k i,pll are the proportional and integral controller parameters of the PLL. tq Represents the q-axis component of the terminal voltage. k i,dvc is the DC voltage integral controller parameter. in and P e are the input power and electromagnetic power respectively.

[0045] Furthermore, according to the topological structure and relevant parameters of the flexible direct current transmission system for renewable energy, a nonlinear mathematical model of the flexible direct current equipment is established, including: according to the dynamics of DC capacitors, DC voltage control, and virtual synchronization and control dynamics in the flexible direct current transmission system for renewable energy, a nonlinear mathematical model of the flexible direct current sending end converter station in the flexible direct current transmission system for renewable energy is constructed;

[0046] Among them, the flexible direct current equipment considers the dynamics of DC capacitors, DC voltage control, and virtual synchronous generator (VSG) dynamics. The nonlinear mathematical model of the flexible direct current sending end converter station in the new energy transmission system is:

[0047]

[0048] Where δ and ω represent the angle and frequency of VSG output respectively; x dvc P represents the integral controller output of DC voltage control; J, D are the inertia and damping control parameters of VSG. ref It is the power reference value output by the DC voltage control link.

[0049] At the same time, combined with the algebraic equation of the quasi-stable network (power frequency network), the quasi-stable network refers to the impedance system of the network at a power frequency of 50Hz, such as:

[0050]

[0051] Among them, I v and I c Represent the injected current vector of the power node and the current source node, U c and U v Represent the node voltage vectors of the current source node and the voltage source node respectively.

[0052] Step 2: Construct the differential equation of the system based on the nonlinear mathematical model of the system, take the differential equation of the system as the constraint condition, construct the objective function with the minimum sum of the squares of the voltage difference and the current difference as the goal, and find the unstable equilibrium point of the differential equation;

[0053] Firstly, the differential equation of the system is constructed based on the nonlinear mathematical model of the system, including: constructing the algebraic equation of the quasi-steady-state network, and combining the nonlinear mathematical model of the new energy equipment, the nonlinear mathematical model of the flexible direct current sending end converter station and the algebraic equation of the quasi-steady-state network to form the differential equation of the system based on the nonlinear mathematical model of the system and the algebraic equation of the quasi-steady-state network.

[0054] The differential equation of the system can be formed by combining the nonlinear mathematical model of new energy equipment, the nonlinear mathematical model of the flexible direct current sending end converter station and the algebraic equation of the quasi-steady-state network. This model can also be used to study the stability mechanism of small and large disturbances and quantitative evaluation of the new energy flexible direct current sending system.

[0055] Specifically, based on the nonlinear mathematical model of the system, all initial points that may converge to the unstable equilibrium point are constructed, where the unstable equilibrium point refers to the solution of the nonlinear equation; the initial point of the unstable equilibrium point divides a certain device and the rest into two asynchronous regions, and the initial point of the unstable equilibrium point is the initial value of the solution given when using the optimization function. First, according to the physical meaning of the unstable equilibrium point, the initial point set of the unstable equilibrium point input to the optimization algorithm is constructed, that is, the initial value of any angle is between π / 2 and π, that is, it is set to:

[0056]

[0057] Among them, x0 is the steady-state equilibrium point, x equ,i is the initial point of construction.

[0058] Furthermore, by constructing the objective function and constraint conditions, the unstable equilibrium point is transformed into an optimization problem, where the constraint condition is the differential equation of the system, and the objective function is the minimum sum of the squares of the voltage difference (the difference between the voltage reference value and the calculated value of the voltage source node) and the current difference (the difference between the voltage reference value and the calculated value of the current source node). The objective function is:

[0059] F(x equ )=∑(U num -U ref ) 2 +∑(I num -I ref ) 2

[0060] Among them, U num and I num The difference between the voltage calculated value and the flow calculated value obtained by substituting the equilibrium point into the power flow equation; U ref and I ref are the voltage reference value and the current reference value of the voltage source node and the current source node.

[0061] The possible set of unstable equilibrium points can be obtained by using mature optimization algorithms (such as @fminsearch or @fmincon in MATLAB).

[0062] Step 3: Based on the unstable equilibrium point, the Jacobian matrix of the system and the tangent plane equation of each unstable equilibrium point are calculated, and the dominant unstable equilibrium point of the system under the fault is determined by combining the system trajectory after the fault and the corresponding tangent plane equation. The main step is to bring the obtained unstable equilibrium point into the Jacobian matrix of the system, calculate the left and right eigenvectors corresponding to the unstable characteristic roots of the unstable equilibrium point, and then construct the tangent plane equation of the unstable equilibrium point according to the left and right eigenvectors corresponding to the unstable characteristic roots of the unstable equilibrium point.

[0063] The fault trajectory obtained by numerical simulation is used to determine the target tangent plane that first intersects the fault trajectory from the tangent plane equations of each unstable equilibrium point, so that the unstable equilibrium point corresponding to the target tangent plane is the dominant unstable equilibrium point of the system under this fault.

[0064] Specifically, according to the nonlinear mathematical model equation of the system, the Jacobian matrix of the system can be obtained by the following formula, namely:

[0065]

[0066] Among them, J is the system Jacobian matrix, y1 Tis the corresponding left eigenvector. According to the manifold-related theory, the tangent plane equation of each unstable equilibrium point can be written as:

[0067]

[0068] Among them, F(x) is the tangent plane equation, x is the state variable fault trajectory, and x equ is the value of the unstable equilibrium point.

[0069] Combining the fault trajectory and the tangent plane equation F(x), the unstable equilibrium point corresponding to the tangent plane that the fault estimates intersects first is the dominant unstable equilibrium point under this fault.

[0070] Step 4: Based on the dominant unstable equilibrium point and the system Jacobian matrix, calculate the participation factors of different state variables to the dominant unstable equilibrium point. According to the size of the participation factor, quantitatively analyze the degree of participation of different links or equipment in the transient dynamics of the system, determine the links or equipment that dominate transient synchronization, and quantitatively analyze the size of the interaction between different links or equipment.

[0071] Among them, based on the dominant unstable equilibrium point and the system Jacobian matrix, the participation factors of different state variables to the dominant unstable equilibrium point are calculated to obtain the participation factors of each state variable, including: according to the system Jacobian matrix and the dominant unstable equilibrium point, solving the participation factors of all state variables to the unstable characteristic roots of the dominant unstable equilibrium point to obtain the participation factors of each state variable.

[0072] Specifically, according to the obtained Jacobian matrix and the dominant unstable equilibrium point, the participation factors of all state quantities to the unstable characteristic roots of the dominant unstable equilibrium point are solved as follows:

[0073]

[0074] Among them, p k is the participation factor of the kth state variable to the unstable characteristic root. y and z are the corresponding left and right eigenvectors, y k and z k is the kth value of the left and right eigenvectors.

[0075] Furthermore, based on the dominant unstable equilibrium point and the Jacobian matrix of the system, the participation factors of different state variables to the dominant unstable equilibrium point are calculated to obtain the participation factors of each state variable. According to the size of the participation factor of each state variable, the participation degree of different devices in the transient dynamics of the system is quantitatively analyzed, including:

[0076] The participation factor of each device is obtained by summing up the participation factors of the state variables contained in each device, and the ratio of the device with the largest participation factor to the sum of the participation factors of other devices is used to quantify the interaction intensity between different devices.

[0077] Furthermore, the sum of the participation factors of the state variables contained in each link is obtained, where the state variables are a set of variables that fully describe the motion of the system, including but not limited to x pll x dvc ,u dc ,δ,ω, the link participation factor is:

[0078] p loop,i =∑p k

[0079] Among them, p loop,i Represents the degree of participation of the ith link in the transient dynamics of the system. Therefore, the ratio of the link with the largest participation factor to the sum of the participation factors of other links can be used to quantify the interaction intensity between different links, that is:

[0080]

[0081] Among them, α index is the interaction strength index between links, p loop,max is the value of the link with the largest participation factor. Similarly, the sum of the participation factors of the state variables contained in each device is obtained, and the device participation factor is:

[0082] p device,i =∑p k

[0083] Among them, p device,i Represents the degree of participation of the ith device in the transient dynamics of the system. Therefore, the ratio of the device with the largest participation factor to the sum of the participation factors of other devices can be used to quantify the interaction intensity between different devices, that is:

[0084]

[0085] Among them, β index is the interaction strength index between devices, p device,max It is the value of the device with the largest participation factor. According to the size of the participation factor, we can quantitatively compare and analyze the degree of participation of different links or devices in the transient dynamics of the system, determine the link or device that dominates transient synchronization, and quantitatively analyze the size of the interaction between different links or devices.

[0086] Simulation experiment

[0087] The present disclosure can use the new energy through flexible direct current transmission system as an example to calculate the interaction strength between multiple devices to detect the effectiveness of the method described in the present invention. The simplified new energy through flexible direct current transmission system is shown in the attached figure. Figure 2As shown, the new energy adopts phase-locked loop control, the flexible direct current adopts virtual synchronous machine control, and the sending end system is equivalent to a synchronous machine. The voltage drop fault of the equivalent voltage source of the sending end system is considered, that is, the voltage drops from 1.0pu to 0.65pu, 0.62pu and 0.60pu. The participation factor of the dominant link / equipment and the interaction strength index between links / equipment calculated by the method of the present invention are shown in Table 1.

[0088] Table 1 Participation factors of leading links / equipment and interaction intensity indexes between links / equipment

[0089]

[0090] In summary, the present disclosure can effectively improve the ability to quantify the intensity of transient interactions among multiple devices in a new energy system through flexible direct current transmission, and can also further study the impact of factors such as different fault types, fault severity, system network topology, and system operating conditions on the interaction among multiple devices. The quantitative index of interaction intensity is fast in calculation speed, high in efficiency, clear and understandable, and is convenient for existing large-scale engineering scenarios of new energy systems through flexible direct current transmission, and has great advantages in engineering site calculations and online transient interaction evaluation by engineering personnel.

[0091] Example 2

[0092] In one embodiment of the present disclosure, a system for analyzing transient interaction of multiple devices in a new energy flexible direct current transmission system is provided, comprising:

[0093] A model building module is used to build a nonlinear mathematical model of the system according to the topological structure and related parameters of the new energy transmission system through flexible direct current. The nonlinear mathematical model of the system includes the nonlinear mathematical model of the new energy equipment and the nonlinear mathematical model of the flexible direct current equipment.

[0094] The optimization solution module is used to construct the differential equation of the system based on the nonlinear mathematical model of the system, take the differential equation of the system as the constraint condition, construct the objective function with the minimum sum of the square of the voltage difference and the current difference as the goal, and obtain the unstable equilibrium point of the differential equation of the system;

[0095] Based on the unstable equilibrium point, the system Jacobian matrix and the post-fault system trajectory, determining the dominant unstable equilibrium point of the system under the fault from the unstable equilibrium point;

[0096] The quantitative analysis module is used to calculate the participation factors of different state variables to the dominant unstable equilibrium point based on the dominant unstable equilibrium point and the system Jacobian matrix to obtain the participation factors of each state variable. According to the size of the participation factor of each state variable, the participation degree of different links or equipment in the transient dynamics of the system is quantitatively analyzed. According to the participation degree of different links or equipment in the transient dynamics of the system, the link or equipment that dominates the transient synchronization is determined, thereby quantitatively analyzing the size of the interaction between different links or equipment.

[0097] Example 3

[0098] In one embodiment of the present disclosure, a non-transitory computer-readable storage medium is provided, wherein the non-transitory computer-readable storage medium is used to store computer instructions. When the computer instructions are executed by a processor, the method for analyzing transient interactions of multiple devices in the new energy flexible direct current transmission system is implemented.

[0099] Example 4

[0100] In one embodiment of the present disclosure, an electronic device is provided, including: a processor, a memory, and a computer program; wherein the processor is connected to the memory, the computer program is stored in the memory, and when the electronic device is running, the processor executes the computer program stored in the memory, so that the electronic device executes the multi-device transient interaction analysis method of the new energy flexible direct current transmission system.

[0101] The present disclosure is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present disclosure. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0102] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0103] Although the above describes the specific implementation methods of the present disclosure in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present disclosure. Technical personnel in the relevant field should understand that on the basis of the technical solution of the present disclosure, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present disclosure.

Claims

1. A method for analyzing transient interaction of multiple devices in a new energy flexible direct current transmission system, characterized in that: include: According to the topological structure and relevant parameters of the new energy transmission system through flexible direct current, a nonlinear mathematical model of the system is constructed. The nonlinear mathematical model of the system includes the nonlinear mathematical model of the new energy equipment and the nonlinear mathematical model of the flexible direct current equipment. The differential equation of the system is constructed based on the nonlinear mathematical model of the system. The differential equation of the system is used as a constraint condition, and the objective function is constructed with the minimum sum of the squares of the voltage difference and the current difference as the goal to obtain the unstable equilibrium point of the differential equation of the system. Based on the unstable equilibrium point, the system Jacobian matrix and the post-fault system trajectory, determining the dominant unstable equilibrium point of the system under the fault from the unstable equilibrium point; Based on the dominant unstable equilibrium point and the Jacobian matrix of the system, the participation factors of different state variables to the dominant unstable equilibrium point are calculated to obtain the participation factors of each state variable. According to the size of the participation factor of each state variable, the participation degree of different links or equipment in the transient dynamics of the system is quantitatively analyzed. According to the participation degree of different links or equipment in the transient dynamics of the system, the link or equipment that dominates the transient synchronization is determined, thereby quantitatively analyzing the size of the interaction between different links or equipment.

2. The method for analyzing transient interaction of multiple devices in a new energy flexible direct current transmission system as claimed in claim 1, characterized in that: According to the topological structure and related parameters of the new energy flexible direct current transmission system, a nonlinear mathematical model of the new energy equipment is established, including: according to the DC capacitor dynamics, DC voltage control and phase-locked loop dynamics in the new energy flexible direct current transmission system, a nonlinear mathematical model of the new energy equipment in the new energy flexible direct current transmission system is constructed.

3. The method for analyzing transient interaction of multiple devices in a new energy flexible direct current transmission system according to claim 1, characterized in that: According to the topological structure and related parameters of the new energy via flexible direct current transmission system, a nonlinear mathematical model of the flexible direct current equipment is established, including: according to the dynamics of DC capacitors, DC voltage control, and virtual synchronization and control dynamics in the new energy via flexible direct current transmission system, a nonlinear mathematical model of the flexible direct current sending end converter station in the new energy via flexible direct current transmission system is constructed.

4. The method for analyzing transient interaction of multiple devices in a new energy flexible direct current transmission system according to claim 1, characterized in that: The differential equations of the system are constructed based on the nonlinear mathematical model of the system, including: constructing the algebraic equations of the quasi-steady-state network, and based on the nonlinear mathematical model of the system and the algebraic equations of the quasi-steady-state network, the nonlinear mathematical model of the new energy equipment, the nonlinear mathematical model of the flexible direct current sending end converter station and the algebraic equations of the quasi-steady-state network are combined to form the differential equations of the system.

5. The method for analyzing transient interaction of multiple devices in a new energy flexible direct current transmission system as claimed in claim 1, characterized in that: Based on the nonlinear mathematical model of the system, all initial points that may converge to the unstable equilibrium point are constructed. According to the physical meaning of the unstable equilibrium point, the initial point set of the unstable equilibrium point input into the optimization algorithm is constructed. That is, the initial points of the unstable equilibrium point divide a certain device and the rest into two asynchronous areas, satisfying that the initial value of any angle is between π / 2 and π.

6. The method for analyzing transient interaction of multiple devices in a new energy flexible direct current transmission system as claimed in claim 1, characterized in that: The voltage difference is the difference between the voltage reference value and the voltage calculation value of the voltage source node, and the current difference is the difference between the current reference value and the current calculation value of the current source node. The objective function is: F(x equ )=∑(U num -U ref ) 2 +∑(I num -I ref ) 2 Among them, U num and I num The difference between the voltage calculated value and the flow calculated value obtained by substituting the equilibrium point into the power flow equation; U ref and I ref are the voltage reference value and the current reference value of the voltage source node and the current source node.

7. The method for analyzing transient interaction of multiple devices in a new energy flexible direct current transmission system as claimed in claim 1, characterized in that: Based on the dominant unstable equilibrium point and the system Jacobian matrix, the participation factors of different state variables to the dominant unstable equilibrium point are calculated to obtain the participation factor of each state variable, including: according to the system Jacobian matrix and the dominant unstable equilibrium point, the participation factors of all state variables to the unstable characteristic roots of the dominant unstable equilibrium point are solved to obtain the participation factor of each state variable.

8. The method for analyzing transient interaction of multiple devices in a new energy flexible direct current transmission system as claimed in claim 1, characterized in that: Based on the dominant unstable equilibrium point and the Jacobian matrix of the system, the participation factors of different state variables to the dominant unstable equilibrium point are calculated to obtain the participation factors of each state variable. According to the size of the participation factors of each state variable, the participation degree of different devices in the transient dynamics of the system is quantitatively analyzed, including: The participation factor of each device is obtained by summing up the participation factors of the state variables contained in each device, and the ratio of the device with the largest participation factor to the sum of the participation factors of other devices is used to quantify the interaction intensity between different devices.

9. A multi-device transient interaction analysis system for a new energy flexible direct current transmission system, characterized in that: include: A model building module is used to build a nonlinear mathematical model of the system according to the topological structure and related parameters of the new energy transmission system through flexible direct current. The nonlinear mathematical model of the system includes the nonlinear mathematical model of the new energy equipment and the nonlinear mathematical model of the flexible direct current equipment. The optimization solution module is used to construct the differential equation of the system based on the nonlinear mathematical model of the system, take the differential equation of the system as the constraint condition, construct the objective function with the minimum sum of the square of the voltage difference and the current difference as the goal, and obtain the unstable equilibrium point of the differential equation of the system; Based on the unstable equilibrium point, the system Jacobian matrix and the post-fault system trajectory, determining the dominant unstable equilibrium point of the system under the fault from the unstable equilibrium point; The quantitative analysis module is used to calculate the participation factors of different state variables to the dominant unstable equilibrium point based on the dominant unstable equilibrium point and the system Jacobian matrix to obtain the participation factors of each state variable. According to the size of the participation factor of each state variable, the participation degree of different links or equipment in the transient dynamics of the system is quantitatively analyzed. According to the participation degree of different links or equipment in the transient dynamics of the system, the link or equipment that dominates the transient synchronization is determined, thereby quantitatively analyzing the size of the interaction between different links or equipment.

10. The multi-device transient interaction analysis system of the new energy flexible direct current transmission system as claimed in claim 9, characterized in that: In the model building module, a nonlinear mathematical model of new energy equipment is established based on the topological structure and related parameters of the new energy flexible direct current transmission system, including: constructing a nonlinear mathematical model of new energy equipment in the new energy flexible direct current transmission system based on the DC capacitor dynamics, DC voltage control and phase-locked loop dynamics in the new energy flexible direct current transmission system.

11. The multi-device transient interaction analysis system of the new energy flexible direct current transmission system as claimed in claim 9, characterized in that: In the model building module, a nonlinear mathematical model of the flexible DC equipment is established according to the topological structure and related parameters of the new energy via flexible DC transmission system, including: constructing a nonlinear mathematical model of the flexible DC sending end converter station in the new energy via flexible DC transmission system according to the DC capacitor dynamics, DC voltage control, and virtual synchronization and control dynamics in the new energy via flexible DC transmission system.

12. The multi-device transient interaction analysis system of the new energy flexible direct current transmission system as claimed in claim 9, characterized in that: In the optimization solution module, the differential equation of the system is constructed based on the nonlinear mathematical model of the system, including: constructing the algebraic equation of the quasi-steady-state network, based on the nonlinear mathematical model of the system and the algebraic equation of the quasi-steady-state network, combining the nonlinear mathematical model of the new energy equipment, the nonlinear mathematical model of the flexible direct current sending end converter station and the algebraic equation of the quasi-steady-state network to form the differential equation of the system.

13. The multi-device transient interaction analysis system of the new energy flexible direct current transmission system as claimed in claim 9, characterized in that: In the optimization solution module, based on the nonlinear mathematical model of the system, all initial points that may converge to the unstable equilibrium point are constructed. According to the physical meaning of the unstable equilibrium point, the initial point set of the unstable equilibrium point input into the optimization algorithm is constructed, that is, the initial point of the unstable equilibrium point divides a certain device and the rest into two asynchronous areas, satisfying that the initial value of any angle is between π / 2 and π.

14. The multi-device transient interaction analysis system of the new energy flexible direct current transmission system as claimed in claim 9, characterized in that: In the quantitative analysis module, based on the dominant unstable equilibrium point and the system Jacobian matrix, the participation factors of different state variables to the dominant unstable equilibrium point are calculated to obtain the participation factor of each state variable, including: according to the system Jacobian matrix and the dominant unstable equilibrium point, solving the participation factors of all state variables to the unstable characteristic roots of the dominant unstable equilibrium point to obtain the participation factor of each state variable.

15. The multi-device transient interaction analysis system of the new energy flexible direct current transmission system as claimed in claim 14, characterized in that: According to the size of the participation factor of each state variable, the participation degree of different links in the transient dynamics of the system is quantitatively analyzed, including: obtaining the participation factor of each link by summing up the participation factors of the state variables contained in each link, and quantifying the interaction intensity between different links by the ratio of the link with the largest participation factor to the sum of the participation factors of other links.

16. The multi-device transient interaction analysis system of the new energy flexible direct current transmission system as claimed in claim 14, characterized in that: Based on the dominant unstable equilibrium point and the Jacobian matrix of the system, the participation factors of different state variables to the dominant unstable equilibrium point are calculated to obtain the participation factors of each state variable. According to the size of the participation factors of each state variable, the participation degree of different devices in the transient dynamics of the system is quantitatively analyzed, including: The participation factor of each device is obtained by summing up the participation factors of the state variables contained in each device, and the ratio of the device with the largest participation factor to the sum of the participation factors of other devices is used to quantify the interaction intensity between different devices.

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