Method for analyzing multi-device transient interaction of new energy through flexible direct transmission system

Abstract

The present disclosure provides a multi-device transient interaction analysis method of a new energy through flexible direct transmission system, relates to the technical field of new energy power system transient stability analysis and discrimination, and comprises the following steps: constructing a system nonlinear mathematical model; constructing a differential equation of the system based on the system nonlinear mathematical model, constructing an objective function to obtain a non-steady equilibrium point of the differential equation; determining a dominant non-steady equilibrium point of the system under fault based on the non-steady equilibrium point; calculating participation factors of different state variables to the dominant non-steady equilibrium point based on the dominant non-steady equilibrium point and a Jacobian matrix of the system; quantitatively analyzing the participation degree of different links or devices in the transient dynamic of the system according to the size of the participation factors, determining the links or devices of dominant transient synchronization, and quantitatively analyzing the interaction size between different links or devices. The present disclosure can practically improve the quantitative calculation ability of the multi-device transient interaction strength of the new energy through flexible direct transmission system.

Description

Technical Field

[0001] This disclosure relates to the field of transient stability analysis and discrimination technology for new energy power systems, specifically to a method for analyzing the transient interactions of multiple devices in a new energy power transmission system via flexible direct transmission. Background Technology

[0002] The statements in this section are merely background information relating to this disclosure and do not necessarily constitute prior art.

[0003] In recent years, a large number of new energy power generation devices, represented by wind power and photovoltaics, have been connected to the power grid via voltage source converters, leading to a continuous increase in the penetration rate of power electronic devices in the power grid. Since large-scale new energy bases are located far from load centers, flexible DC transmission technology is currently a suitable solution for transmitting large-scale new energy. However, the lack of supporting synchronous power sources at the sending-end power grid, strong interactions among multiple power electronic devices, complex grid structure, and variable operating modes are typical characteristics of power electronic systems. These systems suffer from complex transient stability mechanisms and difficulties in analyzing the interactions among multiple power electronic devices, seriously threatening the security of the sending-end power grid and the reliable absorption of new energy.

[0004] To ensure the safety of the sending-end power grid and the reliable absorption of new energy sources, existing technologies have been researched in the fields of small-disturbance stability analysis and transient analysis. In small-disturbance stability analysis, state-space modeling or impedance modeling methods have been used to analyze the dominant element of the new energy converter. For transient stability analysis, a few studies have conducted dominant research on the nonlinear model of the new energy converter based on singular perturbation theory. However, when the time constants (or bandwidths) of different controllers are close, singular perturbation theory risks failure. Therefore, determining the dominant transient element of the new energy converter requires further in-depth research. Currently, some studies consider PLL dynamics to be the dominant element of VSC transient stability. Therefore, based on second-order equations considering only PLL dynamics, some studies have used EAC, energy functions, Lyapunov functions, etc., to analyze the transient synchronization stability of a single VSC grid-connected system. Other studies consider the power balance dynamics on the DC capacitor to dominate the transient synchronization process of the VSC, thus establishing a second-order model considering only DC capacitor dynamics and DC voltage control, and conducting transient synchronization stability analysis based on this model.

[0005] However, both of the above models are based on physical intuition and ignore the coupling between links, resulting in a relatively weak theoretical foundation. They lack quantitative analysis and theoretical support regarding the contribution of different links to the transient process. Therefore, due to the insufficient understanding of the transient characteristics of multiple devices in the new energy transmission system via flexible direct transmission, especially the lack of clarity regarding the transient interactions between multiple links, the transient interactions between multiple devices, and the magnitude of these interactions, existing analytical methods cannot characterize the interactions between multiple devices in the system, and there is a lack of analytical calculation methods and corresponding quantitative evaluation indicators. Summary of the Invention

[0006] To address the aforementioned issues, this disclosure proposes a method for analyzing the transient interactions of multiple devices in a new energy transmission system via flexible direct transmission. Specifically, for scenarios involving new energy transmission systems via flexible direct transmission, this method quantifies and identifies the dominant components and devices responsible for the transient stability of the system under severe faults, calculates the intensity of transient interactions among multiple devices, and guides control strategies for enhancing and improving the transient stability of the new energy transmission system via flexible direct transmission.

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

[0008] A method for analyzing the transient interactions of multiple devices in a new energy transmission system via flexible direct transmission includes:

[0009] Based on the topology and relevant parameters of the new energy transmission system via flexible direct current transmission, 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 system's differential equations are constructed based on the nonlinear mathematical model of the system. The system's differential equations are used as constraints, and the objective function is constructed with the goal of minimizing the sum of the squares of the voltage difference and current difference. The unsteady equilibrium point of the system's differential equations is then obtained.

[0011] Based on the aforementioned unstable equilibrium point, the system Jacobian matrix, and the system trajectory after the fault, the dominant unstable equilibrium point of the system under the fault is determined from the unstable equilibrium point.

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

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

[0014] A multi-device transient interaction analysis system for new energy transmission via flexible direct power transmission includes:

[0015] The model building module is used to construct a nonlinear mathematical model of the system based on the topology and related parameters of the new energy transmission system via flexible direct current transmission. 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 equations of the system based on the nonlinear mathematical model of the system. The objective function is constructed with the differential equations of the system as constraints and the goal of minimizing the sum of the squares of the voltage difference and current difference, and the unsteady equilibrium point of the differential equations of the system is obtained.

[0017] Based on the aforementioned unstable equilibrium point, the system Jacobian matrix, and the system trajectory after the fault, the dominant unstable equilibrium point of the system under the fault is determined from the unstable equilibrium point.

[0018] The quantitative analysis module is used to calculate the participation factors of different state variables on the dominant unsteady equilibrium point based on the dominant unsteady equilibrium point and the system Jacobian matrix. Based on the magnitude of the participation factors of each state variable, the module quantitatively analyzes the degree of participation of different links or devices in the system's transient dynamics. Based on the degree of participation of different links or devices in the system's transient dynamics, the module determines the dominant transient synchronization link or device, thereby quantitatively analyzing the magnitude of the interaction between different links or devices.

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

[0020] A non-transitory computer-readable storage medium is provided for storing computer instructions, which, when executed by a processor, implement the multi-device transient interaction analysis method of the new energy transmission system via flexible direct transmission.

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

[0022] An electronic device includes 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 to enable the electronic device to perform the multi-device transient interaction analysis method for the new energy transmission system via flexible direct transmission.

[0023] Compared with the prior art, the beneficial effects of this disclosure are as follows:

[0024] This disclosure presents a method for analyzing the transient interactions of multiple devices in a new energy transmission system via flexible direct transmission. It obtains the topology and related parameters of the new energy transmission system via flexible direct transmission, establishes nonlinear mathematical models for the new energy devices and flexible direct transmission devices respectively, and then constructs a nonlinear mathematical model of the system. The mathematical models used are accurate, the calculation process is clear, and the quantitative indicators given are simple to calculate, making them easy for engineers to understand and master. This method is suitable for the engineering and field application of existing large-scale new energy transmission systems via flexible direct transmission.

[0025] This disclosed method for analyzing the transient interactions of multiple devices in a new energy transmission system via flexible direct transmission is based on the dominant unstable equilibrium point and the system Jacobian matrix. It calculates the participation factors of different state variables on the dominant unstable equilibrium point, and quantifies the degree of participation of different links or devices in the system's transient dynamics based on the magnitude of these participation factors. It identifies the dominant transient synchronization link or device and quantifies the interaction magnitude between different links or devices. The provided transient interaction intensity index for the new energy transmission system via flexible direct transmission is fast, accurate, and reliable, making it highly beneficial for online real-time quantitative assessment and calculation of the transient stability of such systems. It can also be used for theoretical research on the impact mechanism of specific fault types on the transient interactions of large-scale new energy transmission systems via flexible direct transmission, quantifying and identifying key devices and links that determine system transient stability, and then proposing targeted transient stability enhancement control strategies. Overall, it can effectively improve the transient stability assessment and enhancement capabilities of large-scale new energy transmission systems via flexible direct transmission. Attached Figure Description

[0026] The accompanying drawings, which form part of this disclosure, are used to provide a further understanding of this disclosure. The illustrative embodiments of this disclosure and their descriptions are used to explain this disclosure and do not constitute an undue limitation of this disclosure.

[0027] Figure 1 This is a flowchart of the multi-device transient interaction analysis method for a new energy transmission system via flexible direct transmission, according to an embodiment of this disclosure.

[0028] Figure 2 This is a network topology diagram of a new energy transmission system via flexible direct transmission according to an embodiment of this disclosure. Detailed Implementation

[0029] The present disclosure will be further described below with reference to the accompanying drawings and embodiments.

[0030] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this disclosure. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0032] Example 1

[0033] One embodiment of this disclosure provides a method for analyzing the transient interactions of multiple devices in a new energy direct transmission system via flexible transmission, comprising four steps: system modeling, equilibrium point calculation, determination of the dominant unstable equilibrium point, and calculation of interaction factors between links / devices. The specific process steps include:

[0034] Step 1: Based on the topology and relevant parameters of the new energy transmission system via flexible direct current transmission, construct a nonlinear mathematical model of the system. 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 system's differential equations based on the system's nonlinear mathematical model. Using the system's differential equations as constraints, construct the objective function with the goal of minimizing the sum of the squares of the voltage difference and current difference, and find the unsteady equilibrium point of the system's differential equations.

[0036] Step 3: Based on the unstable equilibrium point, the system Jacobian matrix, and the system trajectory after the fault, 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 system Jacobian matrix, calculate the participation factors of different state variables to the dominant unstable equilibrium point. Based on the magnitude of the participation factors of each state variable, quantitatively analyze the degree of participation of different links or devices in the system's transient dynamics. Based on the degree of participation of different links or devices in the system's transient dynamics, determine the dominant transient synchronization link or device, thereby quantitatively analyzing the magnitude of the interaction between different links or devices.

[0038] As one embodiment, this disclosure provides a method for analyzing the transient interactions of multiple devices in a new energy transmission system via flexible direct transmission. The specific implementation process is as follows:

[0039] Step 1: Obtain the topology and relevant parameters of the new energy transmission system via flexible direct current transmission, establish nonlinear mathematical models of the new energy equipment and the flexible direct current equipment respectively, and then construct the nonlinear mathematical model of the system.

[0040] Specifically, the modeling of the nonlinear mathematical model of the large-scale new energy transmission system via flexible direct current transmission mainly involves obtaining relevant data such as the controller parameters of the new energy equipment and the flexible direct current equipment in the system, the system operating conditions, and the transmission line impedance of the power network, and then establishing the nonlinear mathematical model of the new energy transmission system via flexible direct current transmission.

[0041] Furthermore, based on the topology and related parameters of the new energy transmission system via flexible direct current transmission, a nonlinear mathematical model of the flexible direct current equipment is established, including: based on the dynamics of the DC capacitor, DC voltage control, and virtual synchronization and control dynamics in the new energy transmission system via flexible direct current transmission, a nonlinear mathematical model of the converter station at the flexible direct current transmission end in the new energy transmission system via flexible direct current transmission is constructed.

[0042] Among them, considering 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 flexible DC transmission system is as follows:

[0043]

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

[0045] Furthermore, based on the topology and related parameters of the new energy transmission system via flexible direct current transmission, a nonlinear mathematical model of the flexible direct current equipment is established, including: based on the dynamics of the DC capacitor, DC voltage control, and virtual synchronization and control dynamics in the new energy transmission system via flexible direct current transmission, a nonlinear mathematical model of the converter station at the flexible direct current transmission end in the new energy transmission system via flexible direct current transmission is constructed.

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

[0047]

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

[0049] Furthermore, combining the algebraic equations of quasi-steady-state networks (power frequency networks), a quasi-steady-state network refers to the impedance system of a network at a power frequency of 50Hz, such as:

[0050]

[0051] Among them, I v and I c U represents the injected current vectors at the power node and the current source node, respectively. c and U v These 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. Using the differential equation of the system as the constraint condition, construct the objective function with the goal of minimizing the sum of the squares of the voltage difference and current difference, and find the unsteady equilibrium point of the differential equation.

[0053] First, 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 forming the differential equations of the system by combining the nonlinear mathematical model of the new energy equipment, the nonlinear mathematical model of the flexible direct transmission converter station, and the algebraic equations of the quasi-steady-state network based on the nonlinear mathematical model of the system and the algebraic equations of the quasi-steady-state network.

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

[0055] Specifically, based on the system's nonlinear mathematical model, all possible initial points that converge to an unstable equilibrium point are constructed. An unstable equilibrium point refers to a solution to the nonlinear equation. Each initial point of an unstable equilibrium point divides a device and the rest into two asynchronous regions. These initial points are the initial values ​​given when using the optimization function. First, based on the physical meaning of the unstable equilibrium point, a set of initial points for the unstable equilibrium points input to the optimization algorithm is constructed, satisfying that the initial value for any angle is between π / 2 and π. This is set as follows:

[0056]

[0057] Where x0 is the steady-state equilibrium point, x equ,i This is the initial point for construction.

[0058] Furthermore, by constructing the objective function and constraints, the determination of the unsteady equilibrium point is transformed into an optimization problem. The constraints are the system's differential equations, and the objective function is to minimize the sum of the squares of the voltage difference (the difference between the reference and calculated voltage values ​​at voltage source nodes) and the current difference (the difference between the reference and calculated voltage values ​​at current source nodes). 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 This is the difference between the calculated voltage and the calculated flow obtained by substituting the equilibrium point into the power flow equations; U ref and I ref These are the voltage reference values ​​and current reference values ​​for the voltage source node and the current source node.

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

[0062] Step 3: Based on the unstable equilibrium points, calculate the system Jacobian matrix and the tangent plane equation for each unstable equilibrium point. Combining the system trajectory after the fault and the corresponding tangent plane equation, determine the dominant unstable equilibrium point under the fault. This mainly involves substituting the obtained unstable equilibrium point into the system Jacobian matrix, calculating the left and right eigenvectors corresponding to the unstable eigenvalues ​​of that unstable equilibrium point, and then constructing the tangent plane equation for that unstable equilibrium point based on the left and right eigenvectors corresponding to the unstable eigenvalues.

[0063] The fault trajectory obtained from 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. Thus, the unstable equilibrium point corresponding to the target tangent plane is the dominant unstable equilibrium point of the system under this fault.

[0064] Specifically, based on the system's nonlinear mathematical model equations, the system's Jacobian matrix can be obtained using the following formula:

[0065]

[0066] Where J is the system Jacobian matrix, y1 TLet be the corresponding left eigenvector. According to manifold correlation theory, the equation of the tangent plane at each unstable equilibrium point can be written as:

[0067]

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

[0069] Combining the fault trajectory and the tangent plane equation F(x), the unstable equilibrium point corresponding to the first intersecting tangent plane in the fault estimation 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 on the dominant unstable equilibrium point. According to the magnitude of the participation factors, quantify the degree of participation of different links or devices in the transient dynamics of the system, determine the dominant transient synchronization link or device, and quantify the interaction magnitude between different links or devices.

[0071] Specifically, based on the dominant unstable equilibrium point and the system Jacobian matrix, the participation factors of different state variables with respect to the dominant unstable equilibrium point are calculated to obtain the participation factors of each state variable. This includes: based on the system Jacobian matrix and the dominant unstable equilibrium point, solving for the participation factors of all state variables with respect to the unstable eigenvalues ​​of the dominant unstable equilibrium point to obtain the participation factors of each state variable.

[0072] Specifically, based on the obtained Jacobian matrix and the dominant unstable equilibrium point, the participation factors of all state variables with the unstable eigenvalues ​​of the dominant unstable equilibrium point are solved as follows:

[0073]

[0074] Where, p k Let be the participation factor of the k-th state variable with respect to the unstable eigenvalues. y and z are the corresponding left and right eigenvectors, respectively. k and z k This represents the k-th value of the left and right eigenvectors.

[0075] Furthermore, based on the dominant unsteady equilibrium point and the system Jacobian matrix, the participation factors of different state variables with respect to the dominant unsteady equilibrium point are calculated to obtain the participation factors of each state variable. Based on the magnitude of the participation factors of each state variable, the degree of participation of different devices in the system's transient dynamics is quantitatively analyzed, including:

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

[0077] Furthermore, the sum of the participation factors of the state variables included in each stage is calculated, where the state variables are a set of variables that completely describe the motion of the system, including but not limited to... x pll x dvc ,u dc The factors involved in the process are: δ,ω.

[0078] p loop,i =∑p k

[0079] Where, p loop,i This represents the degree of participation of the i-th element in the system's transient dynamics. Therefore, the intensity of interaction between different elements can be quantified by the ratio of the element with the largest participation factor to the sum of the participation factors of the other elements, i.e.:

[0080]

[0081] Where, α index p is an index of the strength of inter-linkage interaction. loop,max This is the value of the component with the largest participation factor. Similarly, the sum of the participation factors of the state variables contained in each device is calculated, and the device participation factor is:

[0082] p device,i =∑p k

[0083] Where, p device,i This represents the degree of participation of the i-th device in the system's transient dynamics. Therefore, the intensity of interaction between different devices can be quantified by the ratio of the device with the largest participation factor to the sum of the participation factors of the other devices, i.e.:

[0084]

[0085] Where, β index p is an index of the interaction strength between devices. device,max This is the value of the device with the largest participation factor. Based on the magnitude of the participation factor, we can quantitatively compare and analyze the degree of participation of different links or devices in the system's transient dynamics, determine the link or device that dominates transient synchronization, and quantitatively analyze the magnitude of the interaction between different links or devices.

[0086] Simulation Experiment

[0087] This disclosure uses a new energy system via flexible direct transmission as an example to calculate the interaction strength between multiple devices to test the effectiveness of the method described in this invention. A simplified new energy system via flexible direct transmission is shown in the attached figure. Figure 2As shown, the new energy source adopts phase-locked loop control, and the flexible DC transmission adopts virtual synchronous machine control. The sending-end system is equivalent to a synchronous machine. Fault considerations include voltage drop faults of the equivalent voltage source of the sending-end system, specifically voltage drops from 1.0 pu to 0.65 pu, 0.62 pu, and 0.60 pu. The participation factors of the dominant links / equipment and the interaction strength indices between links / equipment calculated by the method described in this invention are shown in Table 1.

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

[0089]

[0090] In summary, this disclosure effectively improves the ability to quantify the transient interaction intensity of multiple devices in a new energy transmission system via flexible direct transmission. Furthermore, it allows for further research into the impact of different fault types, fault severity, system network topology, and system operating conditions on the interactions between multiple devices. The described interaction intensity quantification index is fast, efficient, clear, and easy to understand, facilitating engineering scenarios in existing large-scale new energy transmission systems via flexible direct transmission. It offers significant advantages in on-site engineering calculations and online transient interaction assessments by engineers.

[0091] Example 2

[0092] One embodiment of this disclosure provides a multi-device transient interaction analysis system for a new energy transmission system via flexible direct transmission, comprising:

[0093] The model building module is used to construct a nonlinear mathematical model of the system based on the topology and related parameters of the new energy transmission system via flexible direct current transmission. 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 equations of the system based on the nonlinear mathematical model of the system. The objective function is constructed with the differential equations of the system as constraints and the goal of minimizing the sum of the squares of the voltage difference and current difference, and the unsteady equilibrium point of the differential equations of the system is obtained.

[0095] Based on the aforementioned unstable equilibrium point, the system Jacobian matrix, and the system trajectory after the fault, the dominant unstable equilibrium point of the system under the fault is determined from the unstable equilibrium point.

[0096] The quantitative analysis module is used to calculate the participation factors of different state variables on the dominant unsteady equilibrium point based on the dominant unsteady equilibrium point and the system Jacobian matrix. Based on the magnitude of the participation factors of each state variable, the module quantitatively analyzes the degree of participation of different links or devices in the system's transient dynamics. Based on the degree of participation of different links or devices in the system's transient dynamics, the module determines the dominant transient synchronization link or device, thereby quantitatively analyzing the magnitude of the interaction between different links or devices.

[0097] Example 3

[0098] One embodiment of this disclosure provides a non-transitory computer-readable storage medium for storing computer instructions. When the computer instructions are executed by a processor, they implement the multi-device transient interaction analysis method of the new energy transmission system via flexible direct transmission.

[0099] Example 4

[0100] One embodiment of this disclosure provides an electronic device, including a processor, a memory, and a computer program; wherein the processor is connected to the memory, and the computer program is stored in the memory. When the electronic device is running, the processor executes the computer program stored in the memory to enable the electronic device to perform the multi-device transient interaction analysis method for the new energy transmission system via flexible direct transmission.

[0101] This disclosure is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create a machine for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

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

[0103] While the specific embodiments of this disclosure have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of this disclosure. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of this disclosure are still within the scope of protection of this disclosure.

Claims

1. A method for analyzing multi-device transient interaction of a new energy flexible direct transmission system, characterized in that, The method comprises the following steps: According to the topology structure and related parameters of the new energy through flexible transmission system, a nonlinear mathematical model of the system is constructed, including a nonlinear mathematical model of new energy equipment and a nonlinear mathematical model of flexible equipment; Based on the nonlinear mathematical model of the system, a differential equation of the system is constructed, and a target function is constructed with the square sum of voltage difference and current difference as the minimum as the constraint condition of the differential equation of the system. Based on the non-steady equilibrium point, the system Jacobian matrix and the system trajectory after the fault, the dominant non-steady equilibrium point of the system under the fault is determined from the non-steady equilibrium point. Based on the dominant non-steady equilibrium point and the system Jacobian matrix, the participation factors of different state variables to the dominant non-steady equilibrium point are calculated to obtain the participation factors of each state variable. 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. in, U num and I num The voltage and current values ​​are obtained by substituting the equilibrium point into the power flow equations. U ref and I ref are the voltage reference value and the current reference value for the voltage source node and the current source node.

2. The method of claim 1, wherein the new energy through flexible sending out system multi-device transient interaction analysis method is characterized in that, According to the topology structure and related parameters of the new energy through flexible 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 through flexible transmission system, a nonlinear mathematical model of the new energy equipment in the new energy through flexible transmission system is constructed.

3. The method of claim 1, wherein the method further comprises: According to the topology structure and related parameters of the new energy through flexible 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 through flexible transmission system, a nonlinear mathematical model of the new energy equipment in the new energy through flexible transmission system is constructed.

4. The method of claim 1, wherein the new energy through flexible sending out system multi-device transient interaction analysis method is characterized in that, Based on the nonlinear mathematical model of the system, a differential equation of the system is constructed, including: constructing the algebraic equation of the quasi-steady network, based on the nonlinear mathematical model of the system and the algebraic equation of the quasi-steady network, the nonlinear mathematical model of the new energy equipment, the nonlinear mathematical model of the flexible sending end converter station and the algebraic equation of the quasi-steady network are combined to form the differential equation of the system.

5. The method of claim 1, wherein, Based on the nonlinear mathematical model of the system, all possible initial points converging to the non-steady equilibrium point are constructed, and the initial point set of the non-steady equilibrium point for input optimization algorithm is constructed according to the physical meaning of the non-steady equilibrium point, that is, the initial point of the non-steady equilibrium point divides a certain device and the remaining part into two asynchronous regions, and the initial value of any angle is between π / 2 and π.

6. The method of claim 1, wherein, Based on the dominant non-steady equilibrium point and the system Jacobian matrix, the participation factors of different state variables to the dominant non-steady equilibrium point are calculated to obtain the participation factors of each state variable, including: according to the system Jacobian matrix and the dominant non-steady equilibrium point, the participation factors of all state variables to the non-steady characteristic root of the dominant non-steady equilibrium point are solved to obtain the participation factors of each state variable.

7. The method of claim 1, wherein, Based on the dominant non-equilibrium point and the Jacobian matrix of the system, the participation factors of different state variables to the dominant non-equilibrium point are calculated to obtain the participation factors of the state variables, and the participation degrees of different devices in the transient dynamic state of the system are quantitatively analyzed according to the sizes of the participation factors of the state variables, including: The sum of the participation factors of the state variables contained in each device is obtained to obtain the participation factor of each device, and the interaction strength between different devices is quantified by the ratio of the participation factor of the device with the largest participation factor to the sum of the participation factors of other devices.

8. A multi-device transient interaction analysis system for a new energy system transmitted by a flexible direct system, characterized in that, Including: The model construction module is configured to construct a system nonlinear mathematical model according to a topological structure and related parameters of the new energy through flexible transmission system, the system nonlinear mathematical model including a nonlinear mathematical model of the new energy device and a nonlinear mathematical model of the flexible device; The optimization solving module is configured to construct a differential equation of the system based on the system nonlinear mathematical model, construct an objective function with the differential equation of the system as a constraint condition and a square sum of voltage difference and current difference as a target, and solve a non-equilibrium point of the differential equation of the system; Based on the non-equilibrium point, the Jacobian matrix of the system, and the system trajectory after the fault, the dominant non-equilibrium point of the system under the fault is determined from the non-equilibrium point; The quantitatively analyzing module is configured to calculate participation factors of different state variables to the dominant non-equilibrium point based on the dominant non-equilibrium point and the Jacobian matrix of the system to obtain the participation factors of the state variables, and quantitatively analyze the participation degrees of different links or devices in the transient dynamic state of the system according to the sizes of the participation factors of the state variables, determine the link or device of the dominant transient synchronization according to the participation degrees of different links or devices in the transient dynamic state of the system, and thus quantitatively analyze the interaction sizes between different links or devices. The voltage difference is a difference between a voltage reference value and a voltage calculation value of a voltage source node, the current difference is a difference between a current reference value and a current calculation value of a current source node, and the objective function is a square sum of the differences, i.e.: in, U num and I num The voltage and current values ​​are obtained by substituting the equilibrium point into the power flow equations. U ref and I ref are the voltage reference value and the current reference value for the voltage source node and the current source node.

9. The multi-device transient interaction analysis system of a new energy through flexible direct transmission system according to claim 8, wherein, In the model construction module, the nonlinear mathematical model of the new energy device is established according to the topological structure and related parameters of the new energy through flexible transmission system, including: the nonlinear mathematical model of the new energy device in the new energy through flexible transmission system is constructed according to the DC capacitor dynamics, DC voltage control and phase-locked loop dynamics in the new energy through flexible transmission system.

10. The multi-device transient interaction analysis system of a new energy through flexible direct transmission system according to claim 8, wherein, In the model construction module, the nonlinear mathematical model of the flexible device is established according to the topological structure and related parameters of the new energy through flexible transmission system, including: the nonlinear mathematical model of the flexible sending end converter station in the new energy through flexible transmission system is constructed according to the DC capacitor dynamics, DC voltage control and virtual synchronization and control dynamics in the new energy through flexible transmission system.

11. The multi-device transient interaction analysis system of a new energy through flexible direct transmission system of claim 8, wherein, In the optimization solving module, the differential equation of the system is constructed based on the system nonlinear mathematical model, including: the algebraic equation of the quasi-steady network is constructed, the nonlinear mathematical model of the new energy device, the nonlinear mathematical model of the flexible sending end converter station and the algebraic equation of the quasi-steady network are formed into the differential equation of the system based on the system nonlinear mathematical model and the algebraic equation of the quasi-steady network.

12. The multi-device transient interaction analysis system of a new energy through flexible direct transmission system of claim 8, wherein, In the optimization solving module, based on the system nonlinear mathematical model, all possible initial points converging to the unstable equilibrium point are constructed, and 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 point of the unstable equilibrium point divides a certain device and the rest into two asynchronous regions, and the initial value of any angle is between π / 2 and π.

13. The multi-device transient interaction analysis system of a new energy through flexible direct transmission system of claim 8, wherein, 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 factors 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 eigenvalue of the dominant unstable equilibrium point are solved to obtain the participation factors of each state variable.

14. The multi-device transient interaction analysis system of a new energy flexible direct transmission system of claim 13, wherein, According to the size of the participation factors of each state variable, the participation degree of different links in the system transient dynamic is quantitatively analyzed, including: the sum of the participation factors of the state variables contained in each link is obtained to obtain the participation factor of each link, and the ratio of the participation factor of the link with the largest participation factor to the sum of the participation factors of other links is used to quantify the interaction strength between different links.

15. The multi-device transient interaction analysis system of a new energy flexible direct transmission system of claim 13, wherein, 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, and according to the size of the participation factors of each state variable, the participation degree of different devices in the system transient dynamic is quantitatively analyzed, including: The sum of the participation factors of the state variables contained in each device is obtained to obtain the participation factor of each device, and the ratio of the participation factor of the device with the largest participation factor to the sum of the participation factors of other devices is used to quantify the interaction strength between different devices.

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