Method for determining the system frequency equilibrium point after a fault, considering a detailed dynamic component model

Abstract

This application provides a method for determining the frequency equilibrium point of a post-fault system considering a detailed dynamic component model. The method includes: performing power flow calculations on the system before the fault to obtain the results; determining the steady-state values ​​of the equilibrium point state variables and the steady-state values ​​of the equilibrium point algebraic variables under a given operating condition based on the power flow calculation results; determining the full system model based on the system's component model, the steady-state values ​​of the equilibrium point state variables, and the steady-state values ​​of the equilibrium point algebraic variables; constructing a phase reference node selection equation, which is used to determine the phase reference nodes; determining the initial iteration conditions of the system based on the fault type; and solving the full system model and the phase reference node selection equation based on the initial iteration conditions to determine the frequency equilibrium point of the post-fault system. This method solves the problem that existing technologies rely on system time-domain simulation for determining the post-fault frequency equilibrium point, which leads to slow analysis of the post-fault system behavior due to the slow online application of time-domain simulation.

Description

Technical Field

[0001] This application relates to the technical field of determining the frequency balance point of a system after a fault, and more specifically, to a method, apparatus, computer-readable storage medium, and electronic device for determining the frequency balance point of a system after a fault, taking into account a detailed dynamic component model. Background Technology

[0002] Power flow calculation is fundamental to power system planning, operation, and stability analysis. In conventional power flow calculations, a relaxed node is typically selected, and it is assumed that the unbalanced power caused by disturbances is balanced by this node. In reality, faults or operations such as line interruptions, generator disconnection, and load shedding often generate significant unbalanced power, leading to changes in system frequency. Furthermore, the relationship between unbalanced power and system frequency regulation is often the result of the combined effects of the generators involved in frequency regulation within the system. Static power flow calculations cannot accurately predict the actual operating conditions of the system after a fault. Existing post-fault system stability analysis often relies on time-domain simulation software. By analyzing the system equations of various dynamic components and selecting an appropriate simulation step size, the variation curves of each state variable of the system under different disturbances are obtained. Due to the solution characteristics of algebraic-differential equation systems, the computational workload of the time-domain solution of thousands of nonlinear differential equation systems in actual power systems is very large, requiring a considerable amount of time to complete. While the dynamic power flow method simplifies the analysis of the frequency regulation effect of each generator and speed control system in the system, it can better reflect the equilibrium state of the actual system after a fault than traditional power flow calculation. However, it also has problems such as insufficient accuracy of generator models, large errors between DC single-pole blocking and simulation results, and poor convergence.

[0003] The mathematical essence of power flow calculation in power systems remains solving a system of multivariate nonlinear equations, primarily using iterative methods. To more accurately reflect the distribution of unbalanced power among dynamic components of the system, we consider introducing system frequency as a state variable and establishing a detailed dynamic component model for solving the frequency equilibrium point. Currently, solving the frequency equilibrium point after a fault relies on system time-domain simulation. However, for online applications, the slow time-domain simulation process is not conducive to rapid analysis of system behavior after a fault. Therefore, a fast solution method for the frequency equilibrium point considering a detailed dynamic component model of the system is needed.

[0004] Actual simulations have revealed that the behavior of a power system after a fault can be calculated and analyzed using the post-fault equilibrium point. Different fault types and power system configurations lead to varying system behaviors. Solving for the post-fault frequency equilibrium point not only allows us to assess system stability by understanding its ability to reach equilibrium after a disturbance before the fault occurs, but also reveals potential system problems, enabling optimization of system operation and providing a reference for system planning and operation. Furthermore, with the expansion of power system scale and the increasing proportion of renewable energy, uncertainties in system operation increase, reliability decreases, and the types and number of potential system faults increase. Therefore, accurately judging the post-fault system behavior is of great significance. Summary of the Invention

[0005] The main objective of this application is to provide a method, apparatus, computer-readable storage medium, and electronic device for determining the frequency balance point of a post-fault system considering a detailed dynamic component model, so as to at least solve the problem that the solution of the frequency balance point after a fault in the prior art depends on the system time-domain simulation, and the slow online application time-domain simulation process leads to slow analysis of the behavior of the post-fault system.

[0006] To achieve the above objectives, according to one aspect of this application, a method for determining the frequency equilibrium point of a system after a fault, considering a detailed dynamic component model, is provided, comprising: performing power flow calculation on the system before the fault to obtain power flow calculation results; determining the steady-state values ​​of the equilibrium point state variables and the steady-state values ​​of the equilibrium point algebraic variables of the system under a given operating condition based on the power flow calculation results; determining a full system model based on the component model of the system, the steady-state values ​​of the equilibrium point state variables, and the steady-state values ​​of the equilibrium point algebraic variables, wherein the full system model includes a power supply model, a load model, and network equations; constructing a phase reference node selection equation, wherein the phase reference node selection equation is used to determine a phase reference node, the phase reference node being the node least affected by changes in disturbance voltage and power parameters for different disturbance points; determining the initial iteration conditions of the system based on the fault type of the system, and solving the full system model and the phase reference node selection equation based on the initial iteration conditions to determine the frequency equilibrium point of the system after the fault.

[0007] Optionally, the power supply model in the overall system model is determined based on the component model of the system, the steady-state values ​​of the equilibrium point state variables, and the steady-state values ​​of the equilibrium point algebraic variables, including:

[0008] According to the first system of equations:

[0009]

[0010] Determine the power supply model of the entire system model, wherein X d With X qV represents the synchronous reactance of the d-axis and q-axis, respectively. x With V y R represents the voltage at the x-terminal and the voltage at the y-terminal of the generator, respectively. a For stator resistance, I Gx and I Gy These represent the x- and y-axis components of the power injection current, respectively, and K is the regulator gain coefficient. A For the voltage regulator gain, K V For the proportional integral, V ref R is the reference value for the excitation voltage. C For the load compensation resistance component, X C For the load compensation reactance component, D is the damping coefficient, F is the system frequency after the fault, and Y is the load compensation reactance component. ref K is the reference value for the valve opening. GW b is the rotational speed amplification factor. p δ represents the proportion of constant current loads, and δ is the power angle.

[0011] Optionally, the load model in the overall system model is determined based on the component model of the system, the steady-state values ​​of the equilibrium point state variables, and the steady-state values ​​of the equilibrium point algebraic variables, including:

[0012] According to the second system of equations:

[0013]

[0014] The load model of the entire system model is determined, where V0 is the initial steady-state voltage, and P... L0 and Q L0 a is the power absorbed by the load at the initial steady-state voltage and frequency. P and a Q 、b P and b Q c P and c Q These represent the proportions of constant impedance load, constant current load, and constant power load, respectively; F is the system frequency after the fault; and L... DP L is the active frequency factor. DQ I is the reactive frequency factor. Lx and I Ly These represent the components of the load injection current along the x-axis and y-axis, respectively.

[0015] Optionally, the network equations in the full system model are determined based on the component model of the system, the steady-state values ​​of the equilibrium point state variables, and the steady-state values ​​of the equilibrium point algebraic variables, including:

[0016] According to the first formula:

[0017] Determine the network equations of the entire system model, where i = 1, 2, ..., n. The injected current of the power supply. Injecting current into the load, Y ij Let be the mutual admittance between node i and node j. The voltage at node j.

[0018] Optionally, a phase reference node selection equation is constructed, including:

[0019] According to the second formula: Construct the phase reference node selection equation, where V kx and V ky Let θ represent the components of the voltage at reference node k along the x and y axes, respectively. k0 Let be the voltage phase at node k.

[0020] Optionally, determining the initial iteration conditions of the system based on the fault type of the system includes: determining the ground state disturbance value based on the fault type of the system, and determining whether the ground state disturbance value is greater than a preset disturbance value, wherein the ground state disturbance value is determined based on the voltage, frequency, and power of the fault node of the system; if the ground state disturbance value is less than or equal to the preset disturbance value, the initial iteration conditions of the system's pre-fault equilibrium point are used as the initial iteration conditions of the post-fault equilibrium point.

[0021] Optionally, after determining whether the ground state perturbation value is greater than a preset perturbation value, the method further includes:

[0022] If the ground state perturbation value is determined to be greater than the preset perturbation value, then according to the third formula: Determine the initial iteration conditions, wherein, Let x( be the corrected initial value for the iteration) 0 ) represents the initial iteration point before correction, p represents the fault parameter, p0 represents the initial value of the fault parameter, and h represents the initial iteration point before correction. p h is the partial derivative with respect to the fault parameter p. x Let x be the partial derivative with respect to the state variable x.

[0023] According to another aspect of this application, a device for determining the frequency equilibrium point of a system after a fault, considering a detailed dynamic component model, is provided, comprising: a first determining unit, configured to perform power flow calculation on the system before the fault, obtain power flow calculation results, and determine the steady-state values ​​of the equilibrium point state variables and the steady-state values ​​of the equilibrium point algebraic variables of the system under a given operating condition based on the power flow calculation results; a second determining unit, configured to determine a full system model based on the component model of the system, the steady-state values ​​of the equilibrium point state variables, and the steady-state values ​​of the equilibrium point algebraic variables, the full system model including a power supply model, a load model, and network equations; a construction unit, configured to construct a phase reference node selection equation, wherein the phase reference node selection equation is used to determine a phase reference node, the phase reference node being the node least affected by changes in disturbance voltage and power parameters for different disturbance points; and a third determining unit, configured to determine the initial iteration conditions of the system based on the fault type of the system, and solve the full system model and the phase reference node selection equation based on the initial iteration conditions to determine the frequency equilibrium point of the system after the fault.

[0024] According to another aspect of this application, a computer-readable storage medium is provided, the computer-readable storage medium including a stored program, wherein, when the program is executed, it controls the device where the computer-readable storage medium is located to perform any of the described methods for determining the post-fault system frequency balance point considering a detailed dynamic element model.

[0025] According to another aspect of this application, an electronic device is provided, comprising: one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including methods for performing any of the described methods for determining the post-fault system frequency balance point considering a detailed dynamic element model.

[0026] This application utilizes the technical solution to perform power flow calculations on the system before a fault, obtaining the power flow calculation results. Based on these results, the steady-state values ​​of the equilibrium point state variables and the steady-state values ​​of the equilibrium point algebraic variables under a given operating condition are determined. A full system model is then determined based on the system's component models, the steady-state values ​​of the equilibrium point state variables, and the steady-state values ​​of the equilibrium point algebraic variables. This full system model includes a power supply model, a load model, and network equations. A phase reference node selection equation is constructed to determine the phase reference nodes, which are the nodes least affected by changes in disturbance voltage and power parameters for different disturbance points. Initial iteration conditions are determined based on the system's fault type, and the full system model and the phase reference node selection equation are solved based on these initial iteration conditions to determine the frequency equilibrium point of the system after the fault. This solution solves the problem in existing technologies where the determination of the frequency equilibrium point after a fault relies on system time-domain simulation, leading to slow analysis of the system's behavior after a fault due to the slow online application of time-domain simulation. This solution efficiently calculates the frequency equilibrium point of the system after a fault. Attached Figure Description

[0027] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0028] Figure 1 A hardware block diagram of a mobile terminal that performs a method for determining the frequency balance point of a system after a fault, taking into account a detailed dynamic element model, according to an embodiment of this application is shown.

[0029] Figure 2 A flowchart illustrating a method for determining the frequency balance point of a system after a fault, taking into account a detailed dynamic component model, according to an embodiment of this application, is shown.

[0030] Figure 3 A schematic diagram illustrating the specific power system fault balance point calculation process provided according to an embodiment of this application is shown.

[0031] Figure 4 A block diagram of an FV-type excitation system according to an embodiment of this application is shown;

[0032] Figure 5 A block diagram of a GM-type regulating system according to an embodiment of this application is shown;

[0033] Figure 6 A block diagram of a GA-type electro-hydraulic servo system according to an embodiment of this application is shown;

[0034] Figure 7 A block diagram of a TW-type turbine system according to an embodiment of this application is shown;

[0035] Figure 8 A structural block diagram of a device for determining the frequency balance point of a faulted system considering a detailed dynamic element model, according to an embodiment of this application, is shown. Detailed Implementation

[0036] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0037] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0038] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0039] As described in the background section, the existing technology for determining the post-fault frequency balance point relies on system time-domain simulation. The slow online application of time-domain simulation results in slow analysis of the post-fault system behavior. To address the problem that the existing technology for determining the post-fault frequency balance point relies on system time-domain simulation, and the slow online application of time-domain simulation results in slow analysis of the post-fault system behavior, embodiments of this application provide a method, apparatus, computer-readable storage medium, and electronic device for determining the post-fault system frequency balance point considering a detailed dynamic component model.

[0040] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0041] The methods and embodiments provided in this application can be executed on a mobile terminal, computer terminal, or similar computing device. Taking running on a mobile terminal as an example, Figure 1This is a hardware structure block diagram of a mobile terminal for a method of determining the post-fault system frequency balance point considering a detailed dynamic component model, according to an embodiment of the present invention. Figure 1 As shown, a mobile terminal may include one or more ( Figure 1 Only one is shown in the diagram. A processor 102 (which may include, but is not limited to, a microprocessor MCU or a programmable logic device FPGA, etc.) and a memory 104 for storing data are also shown. The mobile terminal may further include a transmission device 106 for communication functions and an input / output device 108. Those skilled in the art will understand that... Figure 1 The structure shown is for illustrative purposes only and does not limit the structure of the mobile terminal described above. For example, the mobile terminal may also include components that are more... Figure 1 The more or fewer components shown, or having the same Figure 1 The different configurations shown.

[0042] Memory 104 can be used to store computer programs, such as application software programs and modules, like the computer program corresponding to the method for determining the post-fault system frequency balance point considering a detailed dynamic element model in this embodiment of the invention. Processor 102 executes various functional applications and data processing by running the computer program stored in memory 104, thereby implementing the above-described method. Memory 104 may include high-speed random access memory and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, memory 104 may further include memory remotely located relative to processor 102, and these remote memories can be connected to the mobile terminal via a network. Examples of the aforementioned networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof. Transmission device 106 is used to receive or send data via a network. Specific examples of the aforementioned networks may include wireless networks provided by the mobile terminal's communication provider. In one example, transmission device 106 includes a Network Interface Controller (NIC), which can be connected to other network devices via a base station to communicate with the Internet. In one example, the transmission device 106 may be a radio frequency (RF) module, which is used to communicate with the Internet wirelessly.

[0043] This embodiment provides a method for determining the frequency balance point of a fault-based system considering a detailed dynamic element model, which runs on a mobile terminal, computer terminal, or similar computing device. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0044] Figure 2 This is a flowchart illustrating a method for determining the post-fault system frequency balance point based on a detailed dynamic component model, according to an embodiment of this application. Figure 2 As shown, the method includes the following steps:

[0045] Step S201: Perform power flow calculation on the system before the fault, obtain the power flow calculation results, and determine the steady-state values ​​of the equilibrium point state variables and the steady-state values ​​of the equilibrium point algebraic variables of the system under the given operating conditions based on the power flow calculation results.

[0046] Specifically, based on the power flow calculation of the power grid system before the fault, the steady-state values ​​of the equilibrium point state variables and the steady-state values ​​of the equilibrium point algebraic variables can be determined according to the calculation results.

[0047] Step S202: Determine the whole system model based on the system's component model, steady-state values ​​of equilibrium point state variables, and steady-state values ​​of equilibrium point algebraic variables. The whole system model includes the power supply model, load model, and network equations.

[0048] The power grid system's component model includes generators, transformers, transmission lines, loads, and switching equipment. These components are interconnected, enabling the normal operation of the power grid system and ensuring the supply of electrical energy through transmission and distribution. Generators are the energy source of the power grid system. Transformers step up or step down the voltage of the electricity generated by generators, then transmit the electricity to loads in different areas through transmission lines, and finally, switching equipment controls the flow and distribution of electrical energy. The operation of the entire power grid system is accomplished through the coordination and cooperation of these components.

[0049] Specifically, based on the component models of the system, the expressions for the power supply model and load model for solving the equilibrium point under steady state are derived, and the whole system model for solving the equilibrium point is further formed by combining the network equations.

[0050] Step S203: Construct the phase reference node selection equation, wherein the phase reference node selection equation is used to determine the phase reference node, and the phase reference node is the node that is least affected by the disturbance voltage and power parameter changes for different disturbance points.

[0051] Specifically, regarding the selection of phase reference nodes, for different disturbed points, selecting nodes that are less affected by changes in parameters such as disturbance voltage and power as phase reference nodes can effectively avoid the initial value deviating from the convergence region. This is reflected in the network topology as nodes that are electrically far from the disturbed point, which can be quantitatively calculated through the equivalent impedance between nodes.

[0052] Step S204: Determine the initial iteration conditions of the system based on the fault type, and solve the full system model and phase reference node selection equation based on the initial iteration conditions to determine the frequency equilibrium point of the system after the fault.

[0053] Specifically, for obtaining the initial iteration conditions of the ground state, most ground state disturbances can be directly obtained by using the equilibrium point before the fault as the initial iteration condition of the equilibrium point after the fault. For some ground state disturbances that have a significant impact on the stability margin and can cause significant local power flow in the power grid, the tangent method can be directly considered to obtain the initial iteration conditions. For severe faults, the continuous method is used to select an appropriate step size to track the equilibrium point after the fault.

[0054] This embodiment performs power flow calculations on the system before the fault, obtaining the results. Based on these results, it determines the steady-state values ​​of the equilibrium point state variables and the steady-state values ​​of the equilibrium point algebraic variables under a given operating condition. The entire system model is determined based on the system's component models, the steady-state values ​​of the equilibrium point state variables, and the steady-state values ​​of the equilibrium point algebraic variables. This model includes a power supply model, a load model, and network equations. A phase reference node selection equation is constructed to determine the phase reference nodes, which are the nodes least affected by changes in disturbance voltage and power parameters for different disturbance points. The initial iteration conditions are determined based on the system's fault type, and the entire system model and the phase reference node selection equation are solved based on these conditions to determine the frequency equilibrium point of the system after the fault. This approach solves the problem in existing technologies where solving the post-fault frequency equilibrium point relies on system time-domain simulation, leading to slow analysis of post-fault system behavior due to the slow online application of time-domain simulation. It can efficiently calculate the post-fault system frequency equilibrium point.

[0055] In the specific implementation process, the power supply model in the whole system model is determined based on the system's component model, the steady-state values ​​of the equilibrium point state variables, and the steady-state values ​​of the equilibrium point algebraic variables, including:

[0056] According to the first system of equations:

[0057]

[0058] Determine the power supply model for the entire system, where X d With X q V represents the synchronous reactance of the d-axis and q-axis, respectively. x With Vy R represents the voltage at the x-terminal and the voltage at the y-terminal of the generator, respectively. a For stator resistance, I Gx and I Gy These represent the x- and y-axis components of the power injection current, respectively, and K is the regulator gain coefficient. A For the voltage regulator gain, K V For the proportional integral, V ref R is the reference value for the excitation voltage. C For the load compensation resistance component, X C For the load compensation reactance component, D is the damping coefficient, F is the system frequency after the fault, and Y is the load compensation reactance component. ref K is the reference value for the valve opening. GW b is the rotational speed amplification factor. p δ represents the proportion of constant current loads, and δ is the power angle.

[0059] This method first requires modeling the power source, such as a commonly used four-winding synchronous generator model, whose stator voltage steady-state balance equation is:

[0060]

[0061] Among them, X d and X q These represent the d-axis and q-axis synchronous reactances, respectively; V d and V q Let represent the voltage along the d-axis and q-axis. Equation (1) involves the voltage and current along the dq-axis, which satisfy the dq-xy coordinate transformation relationship with the voltage and current in the network. The coordinate transformation formula considering voltage and current is:

[0062]

[0063]

[0064] For excitation, taking a simple FV-type excitation system as an example, and considering the existence of the PSS DC blocking element, the steady-state additional excitation input is zero. The steady-state equation derivation is as follows:

[0065] E fq =K FV (V ref -V C (4)

[0066] In the formula, V ref K is the reference value for the excitation voltage. FV V is the proportionality coefficient. C To measure the compensation voltage, compare it with the generator's terminal voltage V. x and V y The relationship between them is:

[0067]

[0068] In the formula, R C X C The resistive and reactive components are for load compensation.

[0069] Consider the rotor motion equations of a synchronous generator, with the system frequency F after disturbance. S =F N F redefines the frequency reference, and has

[0070]

[0071] Among them, P m ,P e D and T J These represent the prime mover's mechanical power, prime mover's electromagnetic power, rotor damping coefficient, and rotor inertia time constant, respectively; F is the system frequency after the fault. Synchronous generator electromagnetic power P e The expression is given by the grid connection point equation:

[0072]

[0073] For the prime mover and its speed control system, taking a simple GM-GA-TW turbine and its speed control system as an example, the steady-state equations are derived as follows:

[0074]

[0075] In the formula, Y ref K is the reference value for the valve opening. W and b p These are the regulator gain coefficient and the difference coefficient, respectively. Substituting equations (2) to (5) into equation (1), and equations (7) and (8) into equation (6), we can obtain the power supply model in the full system model of the synchronous generator set after the disturbance.

[0076] Specifically, the load model in the overall system model is determined based on the system's component model, the steady-state values ​​of the equilibrium point state variables, and the steady-state values ​​of the equilibrium point algebraic variables, including:

[0077] According to the second system of equations:

[0078]

[0079] Determine the load model for the entire system, where V0 is the initial steady-state voltage and P... L0 and Q L0 a is the power absorbed by the load at the initial steady-state voltage and frequency. P and a Q 、b P and bQ c P and c Q These represent the proportions of constant impedance load, constant current load, and constant power load, respectively; F is the system frequency after the fault; and L... DP L is the active frequency factor. DQ I is the reactive frequency factor. Lx and I Ly These represent the components of the load injection current along the x-axis and y-axis, respectively.

[0080] For the load model, this method selects a ZIP model that considers voltage and frequency characteristics, resulting in:

[0081]

[0082] Where V0 is the initial steady-state voltage, P L0 and Q L0 a is the power absorbed by the load at the initial steady-state voltage and frequency. P and a Q ,b P and b Q ,c P and c Q These represent the proportions of constant impedance loads, constant current loads, and constant power loads, respectively, K. P and K Q The load variation factor is relative to the system frequency. The grid connection point equation is also considered:

[0083]

[0084] Substituting equation (11) into equation (10), we can obtain the load model of the entire system after the disturbance.

[0085] More specifically, the network equations in the overall system model are determined based on the system's component models, the steady-state values ​​of the equilibrium point state variables, and the steady-state values ​​of the equilibrium point algebraic variables, including:

[0086] According to the first formula:

[0087] Determine the network equations for the entire system model, where i = 1, 2, ..., n. The injected current of the power supply. Injecting current into the load, Y ij Let be the mutual admittance between node i and node j. The voltage at node j.

[0088] This method consists of the aforementioned power source model, load model, and network equations, forming a complete system model.

[0089] Furthermore, the phase reference node selection equation is constructed, including:

[0090] According to the second formula: Construct the phase reference node selection equation, where V kx and V ky Let θ represent the components of the voltage at reference node k along the x and y axes, respectively. k0 Let be the voltage phase at node k.

[0091] This method, in selecting phase reference nodes, chooses nodes that are less affected by changes in parameters such as disturbance voltage and power for different disturbed points. This can effectively avoid the initial value deviating from the convergence region. This is reflected in the network topology as nodes that are electrically far from the disturbed point, and can be quantitatively calculated through the equivalent impedance between nodes.

[0092] Furthermore, the initial iteration conditions of the system are determined based on the system's fault type, including:

[0093] The ground state disturbance value is determined based on the fault type of the system, and it is determined whether the ground state disturbance value is greater than the preset disturbance value. The ground state disturbance value is determined based on the voltage, frequency and power of the fault node of the system.

[0094] When the ground state disturbance value is less than or equal to the preset disturbance value, the initial iteration condition of the system's pre-fault equilibrium point is used as the initial iteration condition of the post-fault equilibrium point.

[0095] Specifically, after determining whether the ground-state perturbation value is greater than a preset perturbation value, the method further includes:

[0096] If the ground state perturbation value is determined to be greater than the preset perturbation value, then according to the third formula: Determine the initial iteration conditions, where, Let x( be the corrected initial value for the iteration) 0) The initial iteration point before correction, p is the fault parameter, p0 is the initial value of the fault parameter, and h p h is the partial derivative with respect to the fault parameter p. x Let x be the partial derivative with respect to the state variable x.

[0097] This method obtains the initial iteration conditions for the ground state. For most ground state disturbances, the equilibrium point before the fault can be directly used as the initial iteration condition for the equilibrium point after the fault. For some ground state disturbances that have a significant impact on the stability margin and can cause significant local power flow in the power grid, the tangent method can be directly considered to obtain the initial iteration conditions. For more complex and severe faults, the continuous method is used to select an appropriate step size to track the equilibrium point after the fault.

[0098] To enable those skilled in the art to better understand the technical solution of this application, the implementation process of the method for determining the system frequency balance point after a fault, which considers a detailed dynamic component model, will be described in detail below with reference to specific embodiments.

[0099] This embodiment relates to a specific method for determining the frequency balance point of a post-fault system, considering a detailed dynamic component model, such as... Figure 3 As shown, it includes the following steps:

[0100] 1) Calculate the power flow of the system before the fault, and use the power flow calculation results to calculate the values ​​of each variable under the initial operating conditions, so as to obtain the initial steady-state values ​​of the equilibrium point state variables and algebraic variables;

[0101] 2) Derive the power supply model and load model expressions for solving the equilibrium point under steady state based on the component model of the system, and further form the whole system model for solving the equilibrium point by combining the network equations;

[0102] 3) The nonlinear equations are made well-posed by selecting phase reference nodes;

[0103] 4) Modify the parameters of the iterative equation system according to different fault types and form the initial values ​​of the iteration. For ground state disturbances, the initial values ​​of the equilibrium point can be predicted by the tangent method at the equilibrium point before the disturbance. For severe faults, the continuous method is used to select an appropriate step size to track the equilibrium point after the fault.

[0104] 5) Iteratively solve and analyze the stability at the equilibrium point.

[0105] In step 2), a complete system model for solving the equilibrium point is required. A typical example of a complete system equilibrium point model is given below. For ease of representation, the index of the i-th node is ignored in the derivation.

[0106] First, the power supply needs to be modeled. For example, a commonly used four-winding synchronous generator model has the following stator voltage steady-state balance equation:

[0107]

[0108] Among them, X d and X q These represent the d-axis and q-axis synchronous reactances, respectively; V d and V q Let represent the voltage along the d-axis and q-axis. Equation (1) involves the voltage and current along the dq-axis, which satisfy the dq-xy coordinate transformation relationship with the voltage and current in the network. The coordinate transformation formula considering voltage and current is:

[0109]

[0110] For excitation, taking a simple FV-type excitation system as an example, the transfer function block diagram is as follows: Figure 4 As shown, considering the presence of the PSS DC blocking element, the steady-state additional excitation input is zero, and the steady-state equation derivation is as follows:

[0111] E fq =K FV (V ref -V C (4)

[0112] In the formula, V ref K is the reference value for the excitation voltage. FV V is the proportionality coefficient. C To measure the compensation voltage, compare it with the generator's terminal voltage V. x and V y The relationship between them is:

[0113]

[0114] In the formula, R C X C The resistive and reactive components are for load compensation.

[0115] Consider the rotor motion equations of a synchronous generator, with the system frequency F after disturbance. S =F N F redefines the frequency reference, resulting in:

[0116]

[0117] Among them, P m ,P e D and T J These represent the prime mover's mechanical power, prime mover's electromagnetic power, rotor damping coefficient, and rotor inertia time constant, respectively; F is the system frequency after the fault. Synchronous generator electromagnetic power P e The expression is given by the grid connection point equation:

[0118]

[0119] For the prime mover and its speed control system, taking a simple GM-GA-TW turbine and its speed control system as an example, the block diagram of the GM control system in the transfer function block diagram is as follows: Figure 5 The block diagram of the GA type electro-hydraulic servo system is shown below. Figure 6 As shown in the diagram and the block diagram of the TW type prime mover. Figure 7 As shown, the equations under steady state are derived as follows:

[0120]

[0121] In the formula, is the reference value of the valve opening, and and are the regulator gain coefficient and the difference coefficient, respectively. Substituting equations (2) to (5) into equation (1), and equations (7) and (8) into equation (6), we can obtain the steady-state equation of the synchronous generator set after the disturbance:

[0122]

[0123] Then, for the load model, selecting the ZIP model that considers voltage and frequency characteristics, we have:

[0124]

[0125] Where V0 is the initial steady-state voltage, P L0 and Q L0 a is the power absorbed by the load at the initial steady-state voltage and frequency. P and a Q ,b P and b Q ,c P and c Q These represent the proportions of constant impedance loads, constant current loads, and constant power loads, respectively, K. P and K Q The load variation factor is relative to the system frequency. The grid connection point equation is also considered:

[0126]

[0127] Substituting equation (11) into equation (10), we can obtain the steady-state equation of the load after the disturbance:

[0128]

[0129] Finally, the communication network is characterized as follows:

[0130]

[0131] In the formula, where, The injected current of the power supply. Inject current into the load.

[0132] Equations (9), (12), and (13) together form the full system model for calculating the equilibrium point of a specified system.

[0133] In step 3), regarding the selection of the phase reference node, for different disturbed points, selecting a node less affected by changes in parameters such as disturbance voltage and power as the phase reference node can effectively avoid the initial value deviating from the convergence region. This is reflected in the network topology as a node that is electrically far from the disturbed point. The equivalent impedance between nodes can be quantitatively calculated. The equivalent impedance between nodes i and j is numerically equal to the voltage difference between nodes i and j after injecting a unit current into node i.

[0134]

[0135] By the superposition principle, equation (12) is transformed into:

[0136] Z ij,equ =(Z ii -Z ij )-(Z ij -Z jj (15)

[0137] Among them, Z ii Z jj and Z ij These represent the self-impedance of node i, the self-impedance of node j, and the mutual impedance of nodes ij, respectively. The larger the equivalent impedance with respect to the faulty node and the greater the electrical distance from the fault point, the more suitable it is as a phase reference node.

[0138] After selecting the phase reference node accordingly, the equations corresponding to the phase reference node are supplemented in the nonlinear equation system for equilibrium point calculation composed of equations (9), (12), and (13):

[0139]

[0140] Where k is the phase reference node number, and the voltage phase at that point is θ. k0 The x-axis and y-axis components of the voltage are V. kx and V ky At this point, the number of unknowns equals the number of equations, and the system of equations is well-determined.

[0141] In step 4), the initial iteration conditions for the ground state are determined. For most ground state disturbances, the pre-fault equilibrium point can be directly used as the initial iteration condition for the post-fault equilibrium point. For some ground state disturbances that significantly affect the stability margin and can cause significant local power flow in the power grid, the tangent method can be directly considered to obtain the initial iteration conditions, with the active power load at load node i determined by P. L0,i Change to P L1,i For example, replace the load model in the equilibrium point solution equations with:

[0142]

[0143] Assuming the system equations are extended to h(x,u)=0, the corrected initial iteration conditions are obtained:

[0144]

[0145] For more complex and severe faults, the process of finding the equilibrium point can be divided into a continuous process, with the active power output of the synchronous machine at node a determined by Y. G0,a Change to Y G1,a After a short-circuit fault occurs on line bc, the active load at load node d is transferred to P. L0,d Change to P L1,d Reactive load is determined by Q L0,d Change to Q L1,d Taking this as an example, a fault scalar parameter λ is introduced to describe the continuous change process of the fault. The iterative equations are modified according to different fault types as follows:

[0146]

[0147] in, Let be the parameterized opening of the prime mover valve at node a, the self-impedance of nodes b and c, the mutual impedance between nodes b and c, the initial active load and the initial reactive load at node d, and λ be a scalar parameter describing the continuous change of the fault and λ∈[0,1].

[0148] By replacing the corresponding elements in the equilibrium point solution equation with the variable form in equation (18), we obtain h(x,λ)=0, and then the tangent vector at the equilibrium point is formed by the following equation:

[0149]

[0150] And estimate according to the following formula:

[0151]

[0152] In the formula, h is the step size, which needs to be corrected according to the curvature of the curve formed by the continuous method to ensure that the approximate solution falls within the convergence region while having a large step size.

[0153] The correction equation is:

[0154]

[0155] In the formula, x k These are continuous parameters.

[0156] In step 5), the error is finally calculated by comparing it with the transient simulation results, and the existence of the equilibrium point is determined in order to analyze the universality of the solution method.

[0157] The percentage of relative error between the calculated result and the transient simulation is determined by the following formula:

[0158]

[0159] Among them, F S F represents the transient simulation result. C This indicates the calculation result.

[0160] Compared with the prior art, the advantages of this embodiment are:

[0161] First, the accuracy of the model considered is basically the same as that of transient simulation software. For the equilibrium point problem after a fault, it has an accuracy that conventional power flow calculation methods and dynamic power flow calculation methods cannot achieve.

[0162] Second: Compared with the transient simulation process, the method in this embodiment greatly reduces the computational complexity of solving the equilibrium point after the fault, and has obvious advantages in terms of computational speed and storage space.

[0163] Third: The gradient-based initial iteration condition proposed in this embodiment can generate initial values ​​for different faults with a small amount of computation, and the continuous method can give a definite conclusion on whether the equilibrium point exists after the fault, providing guidance for the stability analysis of the system after the fault. It has a wide range of applications in actual power grid security analysis and dispatching accident handling.

[0164] To verify the accuracy and computational efficiency of the method for determining the post-fault system frequency equilibrium point based on the detailed dynamic component model in this embodiment, programming and simulation were performed on an Intel(R)Core(TM) i5-7400@3.00GHz personal computer equipped with 8.00GB RAM, using the MATLAB R2021a and DSP 2.3.33.1 software platform. The modeling method in Chapter 2 and the calculation and analysis method in Chapter 3 were verified using a 39-bus system and the Hainan power grid system as test systems.

[0165] Considering various ground state perturbation types, the specific perturbation descriptions are shown in Table 1.

[0166] Table 1

[0167]

[0168] It should be noted that for faults 1 to 6, the initial values ​​for the equilibrium point iteration are directly obtained from the system equilibrium point before the fault. However, for faults 7 and 8, the system equilibrium point before the fault cannot converge. In these cases, the tangent method is used to correct the equilibrium point before the fault and then use it as the initial value for iteration. The voltage deviation changes before and after correction are compared with the transient simulation results in Table 2. The iteration convergence error is selected as ε = 10. -5 .

[0169] Table 2

[0170]

[0171] Considering various basic disturbance types, the comparison results of system frequency calculations after various disturbances in Table 1 are shown in Table 3. In order to obtain accurate and stable simulation values ​​of the system equilibrium point after disturbances, the time-domain simulation step size in the table is set to 0.25 cycles, the total simulation time for disturbances 1-4 and 7-8 is set to 200s, and the total simulation time for disturbances 5-6 is set to 80s.

[0172] Table 3

[0173]

[0174] Since the stability of a stable system is not easily altered after being subjected to various basic disturbances, the direct equilibrium point calculation method proposed in this paper combines the advantages of fast calculation speed and accurate time-domain simulation in the power flow method. It also typically requires less computational resources, including CPU and memory, to obtain the equilibrium point of the system after disturbance more conveniently and accurately. It meets the requirements for real-time monitoring of the steady-state characteristics of the system in terms of both time and accuracy, and can further provide guidance for monitoring the behavior of the system after disturbance and optimizing the power grid operation strategy.

[0175] Considering various severe fault types, fault information is described in Table 4, where the numbers following G, L, and B represent the number of generators tripped due to faults, the number of lines disconnected after a three-phase short circuit, and the number of loads experiencing faults, respectively. A comparison of the calculated balance point results and simulation results is shown in Table 5.

[0176] Table 4

[0177]

[0178] The calculation results of the equilibrium points for the above severe faults show that the existence of an equilibrium point after a fault is a prerequisite for the system to maintain stability. Faults that prevent the equilibrium point from existing will cause some nodes in the system to exceed the voltage stability margin, resulting in voltage instability, manifested as monotonic voltage instability, corresponding to fault 11. When an equilibrium point exists, there are two scenarios: if the system has sufficient damping, the amplitude of the fluctuations caused by the fault can gradually decrease, and the system reaches stability, corresponding to fault 9; in the second scenario, the system damping is insufficient, and the amplitude of the fluctuations caused by the fault cannot be reduced, causing the system's node voltages and frequencies to remain in an oscillating state for a long time or even lose synchronization. This indicates that the calculation results of this method have good performance in predicting the transient stability of the system after a fault, and are very suitable for judging the transient stability of the system after a fault and for online safety assessment. Of course, the above discussion on the equilibrium point problem is based on the fault clearing time being less than the maximum clearing time. When the fault clearing time is large, even if an equilibrium point exists, the system cannot achieve stability, and the discussion on the equilibrium point problem becomes meaningless.

[0179] This application also provides a device for determining the post-fault system frequency balance point considering a detailed dynamic component model. It should be noted that this device can be used to execute the method for determining the post-fault system frequency balance point considering a detailed dynamic component model provided in this application. This device is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0180] The following describes the device for determining the frequency balance point of a fault-based system, which takes into account a detailed dynamic component model, provided in the embodiments of this application.

[0181] Figure 8 This is a schematic diagram of a device for determining the frequency balance point of a system after a fault, based on an embodiment of this application and considering a detailed dynamic component model. Figure 8 As shown, the device includes:

[0182] The first determining unit 81 is used to perform power flow calculation on the system before the fault, obtain the power flow calculation result, and determine the steady-state value of the equilibrium point state variable and the steady-state value of the equilibrium point algebraic variable of the system under a given operating condition based on the power flow calculation result.

[0183] The second determining unit 82 is used to determine the whole system model based on the system's component model, the steady-state values ​​of the equilibrium point state variables and the steady-state values ​​of the equilibrium point algebraic variables. The whole system model includes the power supply model, the load model and the network equations.

[0184] The construction unit 83 is used to construct the phase reference node selection equation, wherein the phase reference node selection equation is used to determine the phase reference node, which is the node least affected by the disturbance voltage and power parameter changes for different disturbance points.

[0185] The third determining unit 84 is used to determine the initial iteration conditions of the system according to the fault type of the system, and to solve the whole system model and the phase reference node selection equation according to the initial iteration conditions to determine the frequency balance point of the system after the fault.

[0186] In this embodiment, the first determining unit performs power flow calculations on the system before the fault, obtains the power flow calculation results, and determines the steady-state values ​​of the equilibrium point state variables and the steady-state values ​​of the equilibrium point algebraic variables under a given operating condition based on the power flow calculation results. The second determining unit determines the full system model based on the system's component model, the steady-state values ​​of the equilibrium point state variables, and the steady-state values ​​of the equilibrium point algebraic variables. The full system model includes a power supply model, a load model, and network equations. The construction unit constructs the phase reference node selection equation, which is used to determine the phase reference node, which is the node least affected by changes in disturbance voltage and power parameters for different disturbance points. The third determining unit determines the initial iteration conditions of the system based on the system's fault type, and solves the full system model and the phase reference node selection equation based on the initial iteration conditions to determine the frequency equilibrium point of the system after the fault. This solves the problem that the solution of the frequency equilibrium point after the fault in the prior art relies on system time-domain simulation, which leads to slow analysis of the system behavior after the fault due to the slow online application time-domain simulation process. This unit can efficiently calculate the frequency equilibrium point of the system after the fault.

[0187] As an optional approach, the second determining unit includes a first determining module, used to determine the first set of equations:

[0188]

[0189] Determine the power supply model for the entire system, where X d With X q V represents the synchronous reactance of the d-axis and q-axis, respectively. x With V y R represents the voltage at the x-terminal and the voltage at the y-terminal of the generator, respectively. a For stator resistance, I Gx and I Gy These represent the x- and y-axis components of the power injection current, respectively, and K is the regulator gain coefficient. A For the voltage regulator gain, K V For the proportional integral, V ref R is the reference value for the excitation voltage. C For the load compensation resistance component, X C For the load compensation reactance component, D is the damping coefficient, F is the system frequency after the fault, and Y is the load compensation reactance component. ref K is the reference value for the valve opening. GW b is the rotational speed amplification factor. p δ represents the proportion of constant current loads, and δ is the power angle.

[0190] In one optional scheme, the second determining unit includes a second determining module, used to determine the load model in the whole system model based on the system's component model, the steady-state values ​​of the equilibrium point state variables, and the steady-state values ​​of the equilibrium point algebraic variables, including: based on the second set of equations:

[0191]

[0192] Determine the load model for the entire system, where V0 is the initial steady-state voltage and P... L0 and Q L0 a is the power absorbed by the load at the initial steady-state voltage and frequency. P and a Q 、b P and b Q c P and c Q These represent the proportions of constant impedance load, constant current load, and constant power load, respectively; F is the system frequency after the fault; and L... DP L is the active frequency factor. DQ I is the reactive frequency factor. Lx and I Ly These represent the components of the load injection current along the x-axis and y-axis, respectively.

[0193] In one alternative, the second determining unit includes a third determining module, used to determine the first formula: Determine the network equations for the entire system model, where i = 1, 2, ..., n. The injected current of the power supply. Injecting current into the load, Y ij Let be the mutual admittance between node i and node j. The voltage at node j.

[0194] An alternative approach is that the building unit includes a building module for use according to the second formula: Construct the phase reference node selection equation, where V kx and V ky Let θ represent the components of the voltage at reference node k along the x and y axes, respectively. k0 Let be the voltage phase at node k.

[0195] In one optional scheme, the third determining unit includes a fourth determining module and an adopting module. The fourth determining module is used to determine the ground state disturbance value according to the fault type of the system, and to determine whether the ground state disturbance value is greater than a preset disturbance value. The ground state disturbance value is determined according to the voltage, frequency and power of the fault node of the system. The adopting module is used to adopt the initial iteration condition of the system's pre-fault equilibrium point as the initial iteration condition of the post-fault equilibrium point when the ground state disturbance value is less than or equal to the preset disturbance value.

[0196] In an optional embodiment, the third determining unit further includes a fifth determining module, used to determine, based on a third formula, when the ground state perturbation value is determined to be greater than a preset perturbation value: Determine the initial iteration conditions, where, Let x( be the corrected initial value for the iteration) 0 ) represents the initial iteration point before correction, p represents the fault parameter, p0 represents the initial value of the fault parameter, and h represents the initial iteration point before correction. p h is the partial derivative with respect to the fault parameter p. x Let x be the partial derivative with respect to the state variable x.

[0197] The fault-based system frequency balance point determination device considering a detailed dynamic component model includes a processor and a memory. The first determining unit, second determining unit, construction unit, and third determining unit are all stored as program units in the memory. The processor executes these program units stored in the memory to achieve their respective functions. All of the above modules reside in the same processor; alternatively, the modules may be located in different processors in any combination.

[0198] The processor contains a kernel, which retrieves the corresponding program units from memory. One or more kernels can be configured. Adjusting kernel parameters addresses the issue that current methods rely on system time-domain simulation for solving post-fault frequency balance points. This slow process of online time-domain simulation leads to slow analysis of post-fault system behavior.

[0199] The memory may include non-permanent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one memory chip.

[0200] This invention provides a computer-readable storage medium including a stored program, wherein, when the program is executed, it controls the device where the computer-readable storage medium is located to perform the above-described method for determining the post-fault system frequency balance point considering a detailed dynamic component model.

[0201] This invention provides a processor for running a program, wherein the program executes the above-described method for determining the post-fault system frequency balance point considering a detailed dynamic component model.

[0202] This invention provides a device including a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps of determining the post-fault system frequency balance point method, which at least considers the detailed dynamic component model described above. The device described herein can be a server, PC, PAD, mobile phone, etc.

[0203] This application also provides a computer program product that, when executed on a data processing device, is adapted to perform a program that initializes a method for determining the frequency balance point of a post-fault system that considers at least the above-described detailed dynamic component model.

[0204] It is obvious to those skilled in the art that the modules or steps of the present invention described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. They can be implemented using computer-executable program code, and thus can be stored in a storage device for execution by a computing device. In some cases, the steps shown or described can be performed in a different order than those described herein, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, the present invention is not limited to any particular combination of hardware and software.

[0205] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0206] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0207] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0208] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0209] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0210] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0211] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0212] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0213] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for determining the frequency equilibrium point of a post-fault system considering a detailed dynamic component model, characterized in that, include: Power flow calculation is performed on the system before the fault to obtain the power flow calculation results. Based on the power flow calculation results, the steady-state values ​​of the equilibrium point state variables and the steady-state values ​​of the equilibrium point algebraic variables of the system under a given operating condition are determined. The full system model is determined based on the component model of the system, the steady-state value of the equilibrium point state variable, and the steady-state value of the equilibrium point algebraic variable. The full system model includes a power supply model, a load model, and network equations. A phase reference node selection equation is constructed, wherein the phase reference node selection equation is used to determine the phase reference node, which is the node least affected by the disturbance voltage and power parameter changes for different disturbance points; The initial iteration conditions of the system are determined based on the fault type of the system, and the frequency equilibrium point of the system after the fault is determined by solving the full system model and the phase reference node selection equation based on the initial iteration conditions. Determining the initial iteration conditions of the system based on the fault type of the system includes: The ground state disturbance value is determined according to the fault type of the system, and it is determined whether the ground state disturbance value is greater than a preset disturbance value. The ground state disturbance value is determined according to the voltage, frequency and power of the fault node of the system. If the ground state disturbance value is less than or equal to the preset disturbance value, the initial iteration condition of the system's pre-fault equilibrium point is used as the initial iteration condition of the post-fault equilibrium point. After determining whether the ground state perturbation value is greater than a preset perturbation value, the method further includes: If the ground state perturbation value is determined to be greater than the preset perturbation value, then according to the third formula: Determine the initial iteration conditions, wherein, The corrected initial values ​​for the iteration. The initial iteration point before correction, where p is the fault parameter. These are the initial values ​​for the fault parameters. The partial derivative with respect to the fault parameter p, Let x be the partial derivative with respect to the state variable x.

2. The method according to claim 1, characterized in that, The power supply model in the overall system model is determined based on the component model of the system, the steady-state values ​​of the equilibrium point state variables, and the steady-state values ​​of the equilibrium point algebraic variables, including: According to the first system of equations: ， The power supply model of the entire system model is determined, wherein, and These represent the d-axis and q-axis synchronous reactances, respectively. and These represent the voltage at the x-terminal and the voltage at the y-terminal of the generator, respectively. For stator resistance, and These represent the x-axis and y-axis components of the power injection current, respectively, and K is the regulator gain coefficient. For voltage regulator gain, For proportional integrals, This is the reference value for the excitation voltage. For the load compensation resistance component, The load compensation reactance component is given, where D is the damping coefficient and F is the post-fault system frequency. This is a reference value for the valve opening. This is the rotational speed amplification factor. This represents the proportion of constant current loads. For the angle of attack.

3. The method according to claim 1, characterized in that, The load model in the overall system model is determined based on the component model of the system, the steady-state values ​​of the equilibrium point state variables, and the steady-state values ​​of the equilibrium point algebraic variables, including: According to the second system of equations: ， The load model of the entire system model is determined, wherein, The initial steady-state voltage, and This refers to the power absorbed by the load at the initial steady-state voltage and frequency. and , and , and These represent the proportions of constant impedance load, constant current load, and constant power load, respectively, and F is the system frequency after the fault. The active frequency factor, For reactive frequency factor, and These represent the components of the load injection current along the x-axis and y-axis, respectively.

4. The method according to claim 1, characterized in that, Based on the component model of the system, the steady-state values ​​of the equilibrium point state variables, and the steady-state values ​​of the equilibrium point algebraic variables, the network equations in the full system model are determined, including: According to the first formula: , Determine the network equations of the entire system model, wherein, , The injected current of the power supply. Inject current into the load, Let be the mutual admittance between node i and node j. The voltage at node j.

5. The method according to claim 1, characterized in that, Constructing the phase reference node selection equation includes: According to the second formula: Construct the phase reference node selection equation, wherein, and These are the x- and y-axis components of the voltage at reference node k, respectively. Let be the voltage phase at node k.

6. An apparatus for determining the frequency equilibrium point of a post-fault system considering a detailed dynamic component model, used to execute the method for determining the frequency equilibrium point of a post-fault system considering a detailed dynamic component model as described in any one of claims 1 to 5, characterized in that, include: The first determining unit is used to perform power flow calculation on the system before the fault, obtain the power flow calculation result, and determine the steady-state value of the equilibrium point state variable and the steady-state value of the equilibrium point algebraic variable of the system under a given operating condition based on the power flow calculation result. The second determining unit is used to determine the whole system model based on the component model of the system, the steady-state value of the equilibrium point state variable and the steady-state value of the equilibrium point algebraic variable, wherein the whole system model includes a power supply model, a load model and network equations. A construction unit is used to construct a phase reference node selection equation, wherein the phase reference node selection equation is used to determine the phase reference node, which is the node least affected by the disturbance voltage and power parameter changes for different disturbance points; The third determining unit is used to determine the initial iteration conditions of the system according to the fault type of the system, and to solve the full system model and the phase reference node selection equation according to the initial iteration conditions to determine the frequency balance point of the system after the fault.

7. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored program, wherein, when the program is executed, it controls the device containing the computer-readable storage medium to perform the method for determining the post-fault system frequency balance point considering a detailed dynamic element model as described in any one of claims 1 to 5.

8. An electronic device, characterized in that, include: One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including a method for performing a post-fault system frequency balance point determination method considering a detailed dynamic element model as described in any one of claims 1 to 5.

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