Stability evaluation method, system and equipment of power system and medium

Abstract

The invention discloses a stability evaluation method, system and device of a power system and a medium, and the method comprises the steps: obtaining the load parameters of each node in a power distribution network, and determining the voltage amplitude, first active power and first reactive power of a transformer substation bus based on the load parameters; based on the voltage amplitude, the first active power and the first reactive power, inputting a preset power distribution system model to obtain a first sensitivity matrix, a second sensitivity matrix and a plurality of sensitivity vectors, and based on the first sensitivity matrix, the second sensitivity matrix and each sensitivity vector, obtaining a plurality of sensitivity vectors; the power distribution system model is obtained by coupling a power supply system model and a power distribution network model at a substation bus; and evaluating the stability of the power system based on the power flow distribution. According to the invention, the accuracy and comprehensiveness of stability evaluation of the power system can be improved.

Description

Technical Field

[0001] The present application relates to the field of power systems, and in particular to a method, system, equipment, and medium for evaluating the stability of a power system. Background Art

[0002] The stability of the power system is crucial, and power flow calculation is an important means of accurately assessing its stability. The power system is composed of numerous power generation, transmission, transformation, distribution, and consumption links, with a complex structure and variable operating conditions. Factors such as fluctuations in power output at the power generation end, changes in transmission line parameters, and dynamic increases and decreases in load demand all have an impact on system stability. Power flow calculation can accurately simulate the transmission status of power in the network based on given system operating conditions, including the voltage amplitude and phase at each node and the power distribution of branches. This clearly presents key information such as whether the system's current power balance is good and whether the voltage level is within the allowable range. With this detailed data, it is possible to accurately determine whether the power system has stability issues such as frequency instability caused by power shortages or voltage collapse caused by voltage over-limit, providing a solid data foundation for ensuring the safe and stable operation of the power system.

[0003] Currently, power flow calculations primarily use traditional nonlinear power flow calculation methods and approximate linear power flow methods to assess power system stability. Traditional nonlinear power flow calculation methods establish precise mathematical models of the power system and employ iterative algorithms to solve node power equations. These methods can accurately simulate the complex operating states of the system, providing a reliable basis for system stability analysis. However, with the development of smart grids, the scale and complexity of distribution systems continue to expand. This method, when dealing with large-scale distribution systems, carries a heavy computational burden and struggles to meet real-time requirements. Approximate linear power flow methods address the shortcomings of traditional methods by simplifying and linearizing the model, improving computational efficiency. However, existing linear power flow methods have limitations when dealing with distribution systems that incorporate new intelligent controllable components (such as distributed energy resources and voltage control devices). They cannot accurately capture the impact of these new components on power flow distribution and system stability, thus compromising the accuracy and comprehensiveness of power system stability assessments.

[0004] Application Contents

[0005] The present application provides a method, system, device and medium for evaluating the stability of an electric power system to improve the accuracy and comprehensiveness of the stability evaluation of the electric power system.

[0006] In a first aspect, the present application provides a method for evaluating the stability of a power system, comprising:

[0007] Obtaining load parameters of each node in the distribution network, and determining a voltage amplitude, a first active power, and a first reactive power of a substation bus based on the load parameters, wherein the load parameters include a second active power and a second reactive power;

[0008] A preset distribution system model is input based on the voltage amplitude, the first active power, and the first reactive power, to obtain a first sensitivity matrix, a second sensitivity matrix, and a plurality of sensitivity vectors, and a power flow distribution of the distribution system is obtained based on the first sensitivity matrix, the second sensitivity matrix, and each of the sensitivity vectors, wherein the distribution system model is obtained by coupling a power supply system model and a distribution network model at a substation bus, the power supply system model is obtained by coupling an upstream network linear model, a substation linear model, and a VCD linear model, and the distribution network model is obtained by coupling an LNC model of each feeder to;

[0009] The stability of the power system is evaluated based on the power flow distribution.

[0010] The embodiment of the present application can provide reliable input for subsequent linear power flow calculations by determining the voltage amplitude, the first active power and the first reactive power of the substation bus, avoiding calculation deviations caused by inaccurate input data, thereby improving the accuracy of stability assessment; by calculating the sensitivity matrix and the sensitivity vector and calculating the power flow distribution, the mutual influence relationship between electrical variables can be quantitatively analyzed, thereby more accurately calculating the power flow distribution of the distribution system, providing a more accurate basis for stability assessment; by coupling the power supply system model and the distribution network model, covering all parts from the upstream network to the substation to the distribution network, it can comprehensively reflect the operation status of the entire power system; based on the power flow distribution, the stability of the power system can be evaluated, and multiple aspects of the power system can be comprehensively considered, and the stability state of the power system can be accurately and comprehensively judged, providing strong support for taking corresponding stability control measures. Compared with the existing technology, the present application can improve the accuracy and comprehensiveness of the stability assessment of the power system.

[0011] Furthermore, the determining of the voltage amplitude, the first active power, and the first reactive power of the substation bus based on the load parameters is specifically as follows:

[0012] Determining the active component and reactive component of the transformer output current based on the load parameters and a preset reference voltage;

[0013] Calculating the substation bus voltage based on the active component, the reactive component, and the reference voltage; if a difference between the substation bus voltage and the reference voltage is greater than a preset threshold, adjusting a first tap position until the substation bus voltage meets a preset condition, and outputting a voltage amplitude of the substation bus;

[0014] Based on the voltage amplitude, the active component, and the reactive component, the first active power and the first reactive power of the substation bus are respectively calculated.

[0015] In this way, by determining the voltage amplitude, the first active power and the first reactive power of the substation bus, reliable input can be provided for the subsequent linear power flow calculation, avoiding calculation deviations caused by inaccurate input data, thereby improving the accuracy of stability assessment.

[0016] Furthermore, the calculation formula for calculating the substation bus voltage based on the active component, the reactive component and the reference voltage is specifically:

[0017] V lv =V ref +r c I lv,a +x c I lv,r ;

[0018] Where V lv is the substation bus voltage; V ref is the desired reference voltage; r c and x c are the adjustment weights of VCD for active and reactive components respectively; I lv,a is the active component of the transformer output current; I lv,r is the reactive component of the transformer output current.

[0019] Furthermore, the expression of the power distribution system model is specifically:

[0020]

[0021] Where x f,,n Indicates the fth feeder, the The electrical variable vector of the nth branch and node; Indicates the initial operating conditions, the fth feeder, the The electrical variable vector of the nth branch and node is the reference value for power flow calculation; F is the total number of feeders in the distribution network, which is used to define the scale and scope of the distribution network; i represents the feeder number, which is used to distinguish different feeder paths; L i N represents the number of branches under the i-th feeder, reflecting the structural complexity of the feeder; ij It represents the number of nodes in the jth branch under the i-th feeder, and clarifies the specific composition of the branch; is the sensitivity matrix, the fth feeder, the The sensitivity of the change in the electrical variable of the nth branch and the nth node to the change in the load injection power of the i-th feeder, the j-th branch and the k-th node is used to quantify the mutual influence between the variables, including the first sensitivity matrix assuming discontinuous VCD operation and the second sensitivity matrix assuming continuous VCD operation; is the sensitivity vector, which indicates the sensitivity of the node voltage amplitude change to the voltage change and reflects the electrical coupling relationship between the node and the slack bus; It represents the load injection power change of the i-th feeder, j-th branch, and k-th node, reflecting the change of the active power or reactive power of the node; It represents the square change of the slack bus voltage, reflecting the voltage fluctuation of the system power supply point; β f,,n It is also a sensitivity vector, reflecting the impact of VCD action on the node electrical variables and quantifying the relationship between VCD operation and node operating status; Δx vcd,ss It represents the change in VCD control parameters, including the tap position change of VCD and other operating parameters, which directly affects the voltage regulation of the distribution network.

[0022] Furthermore, the power flow distribution of the power distribution system is obtained based on the first sensitivity matrix, the second sensitivity matrix and each of the sensitivity vectors, specifically:

[0023] determining, based on the first sensitivity matrix, a change in an electrical variable of the power distribution system under continuous regulation;

[0024] Determining a second tap position that satisfies a VCD control law based on the electrical variable change and the VCD control parameter;

[0025] The second tap position is converted into a discrete third tap position that can be used by an actual VCD device, and the power flow distribution of the power distribution system is calculated based on the second sensitivity matrix and the third tap position.

[0026] In this way, by calculating the sensitivity matrix and sensitivity vector and calculating the power flow distribution, the mutual influence relationship between electrical variables can be quantitatively analyzed, so as to more accurately calculate the power flow distribution of the distribution system and provide a more accurate basis for stability assessment.

[0027] Furthermore, the expression of the power supply system model is specifically:

[0028] For a tap changer without a regulator, the expression is:

[0029]

[0030] For a tap changer with a regulator, the expression is:

[0031]

[0032] Where Δx lv The vector representing the change in electrical variables at the substation bus lv includes the square of the voltage amplitude, the first active power, and the first reactive power. It reflects changes in the operating state of the power system at the substation bus. These changes are affected by both the upstream network and the operation of the transformer and VCD within the substation. It is a key variable connecting the power supply system and the distribution network, and its changes will further affect the power flow distribution within the distribution network. represents the change vector of electrical variables at the upstream network node uv, including the change in active power, reactive power and the square of voltage amplitude, reflecting the slight change in the operating state of the power system at the node uv; J tp1 、J tp2 、J tp3 and J tp4 are all Jacobian matrices; ΔN tr Indicates the change in the transformer tap ratio. By adjusting the tap ratio, the transformer ratio can be changed, thereby achieving voltage regulation; ΔV ref Indicates the change in the reference voltage.

[0033] Furthermore, the expression of the power distribution network model is specifically:

[0034]

[0035] Where, The vector representing the change of electrical variables in the line section of the nth linear component (LNC), including the change of variables such as active power, reactive power and the square of voltage amplitude, reflects the power flow and voltage change of the line under different operating conditions; The Jacobian matrix of the line section in the nth LNC describes the linear relationship between the change of the electrical variables of the line section and the change of the electrical variables of the previous node, reflecting the influence of the electrical characteristics of the line on the power flow distribution; Δx n-1 The vector representing the electrical variable change of the n-1th node, including the changes in the active power, reactive power, and square of the voltage amplitude at the node, serves as an input condition and affects the electrical variable changes of subsequent lines and nodes. The vector representing the change of electrical variables of the direct VCD part in the nth LNC, including the change of variables such as active power, reactive power and the square of voltage amplitude, reflects the operation of the direct VCD under different operating conditions and its impact on power flow distribution; It represents the Jacobian matrix between the direct VCD part and the line part in the nth LNC, describes the linear relationship between the change of the electrical variables of the direct VCD and the change of the electrical variables of the line part, and reflects the impact of the direct VCD on the line power flow; It represents the Jacobian matrix between the direct VCD part and the injection power change in the nth LNC, describes the linear relationship between the change of the electrical variables of the direct VCD and the injection power change, and reflects the impact of the injection power change on the direct VCD action; The power change vector of the direct VCD injected into the nth LNC includes the changes in active power and reactive power, reflecting the impact of the external injected power change on the direct VCD action, and thus affecting the power flow distribution; represents the electrical variable change vector of the fth feeder, the lth branch, and the nth node; The vector representing the change of electrical variables in the line section; Represents the electrical variable change vector of the direct VCD part; Represents the electrical variable change vector of the nth node; represents the Jacobian matrix of the nth node; Represents the load injection power change vector of the nth node.

[0036] In a second aspect, the present application provides a stability assessment system for a power system, comprising: an acquisition module, a calculation model, and an assessment model;

[0037] The acquisition module is configured to acquire load parameters of each node in the distribution network, and determine a voltage amplitude, a first active power, and a first reactive power of a substation bus based on the load parameters, wherein the load parameters include a second active power and a second reactive power;

[0038] The calculation module is configured to input a preset distribution system model based on the voltage amplitude, the first active power, and the first reactive power, obtain a first sensitivity matrix, a second sensitivity matrix, and a plurality of sensitivity vectors, and obtain a power flow distribution of the distribution system based on the first sensitivity matrix, the second sensitivity matrix, and each of the sensitivity vectors, wherein the distribution system model is obtained by coupling a power supply system model and a distribution network model at a substation bus, the power supply system model is obtained by coupling an upstream network linear model, a substation linear model, and a VCD linear model, and the distribution network model is obtained by coupling an LNC model of each feeder to;

[0039] The evaluation module is used to evaluate the stability of the power system based on the power flow distribution.

[0040] The embodiment of the present application can provide reliable input for subsequent linear power flow calculations by determining the voltage amplitude, the first active power and the first reactive power of the substation bus, avoiding calculation deviations caused by inaccurate input data, thereby improving the accuracy of stability assessment; by calculating the sensitivity matrix and the sensitivity vector and calculating the power flow distribution, the mutual influence relationship between electrical variables can be quantitatively analyzed, thereby more accurately calculating the power flow distribution of the distribution system, providing a more accurate basis for stability assessment; by coupling the power supply system model and the distribution network model, covering all parts from the upstream network to the substation to the distribution network, it can comprehensively reflect the operation status of the entire power system; based on the power flow distribution, the stability of the power system can be evaluated, and multiple aspects of the power system can be comprehensively considered, and the stability state of the power system can be accurately and comprehensively judged, providing strong support for taking corresponding stability control measures. Compared with the existing technology, the present application can improve the accuracy and comprehensiveness of the stability assessment of the power system.

[0041] In a third aspect, the present application also provides a terminal device comprising: one or more processors; a memory coupled to the processor for storing one or more programs; when the one or more programs are executed by the one or more processors, the one or more processors implement the power system stability assessment method as described in the present application.

[0042] In a fourth aspect, the present application also provides a terminal device, a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the method for evaluating the stability of the power system as described in the present application is implemented. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a flow chart of an embodiment of a method for evaluating the stability of a power system provided by the present application;

[0044] Figure 2 It is a structural diagram of the power supply system model provided by this application;

[0045] Figure 3 It is a structural diagram of the power distribution network model provided by this application;

[0046] Figure 4 This is the indirect VCD control model and circuit diagram provided by this application;

[0047] Figure 5 This is a schematic structural diagram of an embodiment of a power system stability assessment system provided by the present application;

[0048] Figure 6 It is a structural diagram of the terminal device provided in this application. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0050] It should be understood that the step numbers used herein are only for convenience of description and are not intended to limit the order in which the steps are executed.

[0051] It should be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0052] The terms “include” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0053] The term "and / or" refers to and includes any and all possible combinations of one or more of the associated listed items.

[0054] The stability of the power system is critical, and power flow calculation is an important means of evaluating its stability. The power system structure is complex and the operating conditions are changeable. Factors such as power fluctuations at the power generation end, changes in transmission line parameters, and increases and decreases in load demand all affect stability. Power flow calculation can simulate the power transmission state and present key information such as power balance and voltage level, helping to determine whether the system has stability problems and providing a data basis for safe and stable operation. Currently, power flow calculation mainly uses traditional nonlinear power flow calculation methods and approximate linear power flow methods. Traditional nonlinear power flow calculation methods can accurately simulate the complex operating conditions of the system by establishing precise mathematical models and using iterative algorithms to solve them. However, the computational burden is heavy when dealing with large-scale distribution systems, making it difficult to meet real-time requirements. The approximate linear power flow method simplifies and linearizes the processing model to improve computational efficiency, but it has limitations when dealing with distribution systems containing new intelligent controllable components, affecting the accuracy and comprehensiveness of stability assessments.

[0055] Next, the nouns involved in this application are analyzed:

[0056] Power flow calculation is a key computational tool in power system analysis, used to determine parameters such as the voltage and power distribution of each busbar during steady-state operation. Based on given system operating conditions (such as generator output power and load), it solves the power equations at the nodes in the power network to simulate the power transmission state within the network, including the voltage amplitude and phase at each node and the power distribution of each branch. This provides a clear picture of key information, such as whether the system's current power balance is good and whether voltage levels are within acceptable ranges.

[0057] Nonlinear power flow calculations are based on an accurate mathematical model of the power system, taking into account various nonlinear characteristics of the power system, such as generator output characteristics and line impedance characteristics. Nodal power equations are solved by applying iterative algorithms (such as the Newton-Raphson method and the Gauss-Seidel method).

[0058] Linear power flow calculations are achieved by simplifying and linearizing the mathematical model of the power system. When building the model, it approximates some of the system's nonlinear characteristics, such as ignoring higher-order terms, thereby transforming the originally complex nonlinear equations into linear ones. This method can significantly improve computational efficiency and is suitable for applications with high real-time requirements or when rapid estimation of power flow distribution is required.

[0059] Based on this, the embodiments of the present application provide a method, system, device and medium for evaluating the stability of an electric power system, which can improve the accuracy and comprehensiveness of the stability evaluation of the electric power system.

[0060] The embodiments of the present application provide a method, system, device and medium for evaluating the stability of an electric power system, which are specifically illustrated through the following embodiments. First, the method for evaluating the stability of an electric power system in the embodiments of the present application is described.

[0061] The stability assessment method of the power system provided in the embodiment of the present application relates to the field of power systems. The stability assessment method of the power system provided in the embodiment of the present application can be applied to a terminal, can be applied to a server side, and can also be software running in a terminal or a server side. In some embodiments, the terminal can be a smart phone, a tablet computer, a laptop computer, a desktop computer, etc.; the server side can be configured as an independent physical server, or can be configured as a server cluster or a distributed system composed of multiple physical servers, or can be configured as a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communications, middleware services, domain name services, security services, CDN, and big data and artificial intelligence platforms; the software can be an application that implements a stability assessment method for a power system, etc., but is not limited to the above forms.

[0062] The present application can also be used in numerous general or special computer system environments or configurations. For example: personal computers, server computers, handheld or portable devices, tablet devices, multiprocessor systems, microprocessor-based systems, set-top boxes, programmable consumer electronics, network PCs, minicomputers, mainframe computers, distributed computing environments including any of the above systems or devices, and the like. The present application can be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, and the like that perform specific tasks or implement specific abstract data types. The present application can also be practiced in distributed computing environments in which tasks are performed by remote processing devices connected via a communication network. In a distributed computing environment, program modules can be located in local and remote computer storage media including storage devices.

[0063] Example 1

[0064] Please refer to Figure 1 , Figure 1 This is a flow chart of an embodiment of a method for evaluating the stability of a power system provided by the present application, comprising steps S101 to S103;

[0065] Step S101, obtaining load parameters of each node in the distribution network, and determining a voltage amplitude, a first active power, and a first reactive power of a substation bus based on the load parameters, wherein the load parameters include a second active power and a second reactive power;

[0066] In some embodiments, the load parameters of each node in the distribution network are obtained, specifically: historical load parameters of each node are obtained through a smart meter or a user's power consumption system, or power monitoring equipment (such as PMU, SCADA system) is used to collect the load parameters corresponding to each node in the distribution network in real time, wherein the load parameters include a second active power and a second reactive power.

[0067] In some embodiments, in order to determine the voltage amplitude, the first active power and the first reactive power of the substation bus, it is also necessary to obtain, but not limited to: network topology parameters, line parameters, transformer parameters, voltage control device (VCD) parameters and distributed energy resource (DER) parameters.

[0068] It should be noted that the network topology parameters define the network topology of the distribution system, including the connection relationship between nodes and branches, such as the number of nodes, branch connection relationship, etc., and the acquisition method includes consulting the planning and design drawings of the distribution system, using network scanning tools, or conducting on-site surveys. The line parameters describe the electrical characteristics of the line, including resistance (R), reactance (X), conductance (G), and susceptance (B). The acquisition method includes consulting the line specification manual, performing line tests (such as AC impedance tests), or using power system analysis software for estimation. The transformer parameters describe the electrical characteristics of the transformer, including the transformation ratio (N tr ), resistance (R tr ), reactance (X tr ), etc., and the acquisition method includes consulting the transformer nameplate or technical documents, and performing transformer tests (such as short-circuit test and no-load test). The voltage control device (VCD) parameters describe the control characteristics and status of the voltage control device, such as the control law parameters (reference voltage Vref, first control parameter r c , the second control parameter x c The following parameters are used to describe the output characteristics and control mode of distributed energy resources, such as the output power and control mode (PQ control or PV control) of photovoltaic systems. These parameters can be obtained by consulting DER control system data, equipment technical documentation, or through on-site testing.

[0069] In some embodiments, the voltage amplitude, first active power and first reactive power of the substation bus are determined based on the load parameters, including: determining the active component and reactive component of the transformer output current based on the load parameters and a preset reference voltage; calculating the substation bus voltage based on the active component, the reactive component and the reference voltage; if the difference between the substation bus voltage and the reference voltage is greater than a preset threshold, adjusting the first tap position until the substation bus voltage meets the preset conditions, and outputting the voltage amplitude of the substation bus; based on the voltage amplitude, the active component and the reactive component, respectively calculating the first active power and the first reactive power of the substation bus. Specifically, first, a power supply system model including an upstream network, a substation and a VCD is established for calculating the substation bus parameters; second, with the help of a preset reference voltage V ref , the second active power P load The second reactive power Q load Converted into the initial active component of current I a and the initial reactive component I r , the relevant formula is: The currents of each branch are accumulated according to the network topology to obtain the total current component of the transformer output, which is also the active component I lv,a and the reactive component I lv,r Afterwards, the active component I lv,a , the reactive component I lv,r and the reference voltage V ref Substitute into the control logic formula to calculate the substation bus voltage V lv ; Then, if the substation bus voltage V lv With reference voltage V ref If the difference between the two is greater than the preset difference threshold, the first tap position ΔN is adjusted according to the preset step size. tr Recalculate the substation bus voltage V lv , until the accuracy requirements are met, the voltage amplitude of the substation bus is output; finally, after the voltage amplitude is determined, the first active power P of the substation bus is further solved by combining the power flow calculation principle and electrical connection relationship of the power grid, using known network parameters and load conditions, through the power balance equation and the relationship between node voltage and branch power. lv and the first reactive power Q lv This process involves a detailed analysis of the entire distribution network, including power injection at each node, power transmission along the line, and power conversion by the transformer. By establishing and solving the corresponding mathematical model, the active and reactive power of the substation busbars are ultimately obtained, allowing for a comprehensive understanding of the operating status of the distribution network and providing key data support for the optimized scheduling and reliable operation of the power grid.

[0070] In some embodiments, the calculation formula for calculating the substation bus voltage based on the active component, the reactive component and the reference voltage is specifically:

[0071] V lv =V ref +r c I lv,a +x c I lv,r ;

[0072] Where V lv is the substation bus voltage; V ref is the desired reference voltage; r c and x c are the adjustment weights of VCD for active and reactive components respectively; I lv,a is the active component of the transformer output current; I lv,r is the reactive component of the transformer output current.

[0073] It should be noted that it is necessary to use the above-obtained parameters (such as line parameters, transformer parameters, voltage control device parameters (VCD)) to establish a power supply system model. The structural diagram of the power supply system model is as follows: Figure 2 As shown, the power supply system model includes an upstream network linear model, a substation linear model and a voltage control device (VCD) linear model, wherein the upstream network linear model, i.e., the upper distribution system, is composed of a high-voltage or medium-voltage power grid, which is equivalent to a no-load voltage source V uv and short-circuit impedance X cc The substation transformer includes transformer series parameters (resistance R tr , Reactance X tr ) and the branch containing only VCD, that is, the model is modeled by transformer parameters and VCD parameters, and VCD is modeled by the transformer tap ratio of 1:N tr The voltage control device (VCD) linear model implements voltage regulation through a controller, and the goal is to adjust the tap position of the transformer to make the voltage amplitude V of the substation bus or virtual load center lv Stable at the desired voltage reference value V ref nearby, thus ensuring the stable operation of the power grid.

[0074] It should be noted that the output voltage amplitude V lv , the first active power P lv and the first reactive power Q lv These key output metrics are derived through a comprehensive calculation based on a variety of key input information, including network topology parameters, line parameters, transformer parameters, VCD parameters, load parameters, and distributed energy resource (DER) parameters. Specifically, these key output metrics are derived through scientific mathematical derivation and modeling analysis, by simulating the transmission and conversion of electricity within the power grid. Based on the grid topology and the electrical characteristics of each component, and applying circuit theory principles such as voltage and current relationships and power balance, these key output metrics provide the foundational data for subsequent distribution network models, enabling the entire model to accurately describe and solve the power flow distribution within the distribution network, providing strong support for practical applications such as real-time grid monitoring, fault analysis, and planning and decision-making.

[0075] It should be noted that the transformer tap ratio can be set automatically or manually. In the automatic case, the tap position is determined according to the control law to fix the voltage amplitude V of the substation bus or virtual load center. lv .

[0076] It should be noted that this approach not only maintains high accuracy but also significantly reduces computation time, making it suitable for real-time applications. It also cleverly handles the discrete variable characteristics of VCD, avoiding iterations and improving computational efficiency and the accuracy of the results. Traditional linear power flow methods often simplify discrete variables into continuous variables, ignoring the impact of discrete characteristics on power flow results. Finally, it can adapt to the introduction of new intelligent controllable components, such as distributed energy resources and voltage control devices, accurately modeling the control characteristics of these devices and improving the accuracy of power flow calculations. Existing linear power flow methods have limitations when handling these new components, resulting in reduced computational accuracy.

[0077] In this way, by determining the voltage amplitude, the first active power and the first reactive power of the substation bus, reliable input can be provided for the subsequent linear power flow calculation, avoiding calculation deviations caused by inaccurate input data, thereby improving the accuracy of stability assessment.

[0078] Step S102: Based on the voltage amplitude, the first active power, and the first reactive power, a preset distribution system model is input to obtain a first sensitivity matrix, a second sensitivity matrix, and a plurality of sensitivity vectors, and based on the first sensitivity matrix, the second sensitivity matrix, and each of the sensitivity vectors, a power flow distribution of the distribution system is obtained, wherein the distribution system model is obtained by coupling a power supply system model and a distribution network model at a substation bus, the power supply system model is obtained by coupling an upstream network linear model, a substation linear model, and a VCD linear model, and the distribution network model is obtained by coupling an LNC model of each feeder to;

[0079] It should be noted that it is necessary to construct the distribution system model for linear power flow calculation, wherein the distribution system model is obtained by coupling the power supply system model and the distribution network model at the substation bus. The power supply system model has been developed in detail above and will not be repeated here. The structural diagram of the distribution network model is as follows: Figure 3As shown in Figure 1, the distribution network model consists of multiple feeders, and each feeder is represented by a main line (i.e., trunk line) and branches (i.e., branch line 1 and branch line 2). A generalized line-node component (LNC) is used, and the electrical characteristics and connection relationships of these LNC components are converted into variables and parameters in the linear equation. The LNC components include lines, direct VCDs (such as SVRs or UPFCs), and nodes. The lines are represented by π-type equivalent circuits, and the nodes connect distributed energy resources (DERs) and voltage control devices (VCDs). Direct VCDs can be SVRs (autotransformers) and UPFCs (compensated Compensating voltage injection devices (SVRs) are autotransformers equipped with an automatic tap-changing mechanism that provide voltage regulation. UPFCs achieve voltage regulation by injecting compensating voltage. Indirect VCDs, such as capacitor banks (CBs) and dynamic reactive power compensation devices (D-STATCOMs), indirectly modify the voltage curve by injecting reactive power. Their models are developed based on control laws that describe how VCDs affect voltage and power flows in the distribution network. For example, CBs are represented by discretely varying susceptances, while D-STATCOMs and SVCs provide reactive power based on Q(V) droop control or node voltage regulation. Therefore, the aforementioned structures and parameters are used to establish linear equations, or distribution network models. By coupling the models of feeders and branches, the VCD models, and the node power balance equations, the overall distribution network model is formed.

[0080] It should be noted that the difference between direct VCD (such as SVR or UPFC) and indirect VCD (such as CB or D-STATCOM) lies in their location and function. A direct VCD is located in the line section of the feeder and is used to directly regulate the voltage in the line. Its model is described by the electrical variable change vector of the line section and the electrical variable change vector of the direct VCD section. An indirect VCD, on the other hand, is located at the node and indirectly changes the voltage curve by injecting reactive power. Its model is described by the electrical variable change vector of the node section (direct VCD directly affects the voltage and power flow of the line, while indirect VCD indirectly regulates the voltage by injecting reactive power at the node).

[0081] It should be noted that the indirect VCD control model and circuit diagram are as follows Figure 4 As shown in the figure, the line uses a DC equivalent model, with resistance (R) and reactance (X) labeled. Nodes are connected to indirect VCD devices, serving as reactive power injection points. Indirect VCD devices, also known as DC voltage controllers, consist of ideal DC devices (such as capacitor banks (CB), represented by discretely varying susceptances (B)) and controllers that generate reactive power compensation commands based on voltage deviations. The control logic is as follows: Droop control (QV): The D-STATCOM or SVC regulates reactive power through droop characteristics to maintain node voltage stability.

[0082] It should be noted that the power supply system model transforms the complex power supply system (including the high-voltage or medium-voltage upstream network and substations equipped with voltage control devices (VCDs)) into a linear equation. This provides the starting point and boundary conditions for the calculation of the power flow of the entire distribution network, namely the electrical parameters at the substation busbar, laying the foundation for subsequent power flow calculations within the distribution network. The distribution network model, on the other hand, explains how to transform the various components of the distribution network (feeders, branches, and various VCDs) into linear equations, translating the complex topology and device characteristics of the distribution network into a mathematically tractable form, thereby describing the power flow and voltage distribution within the distribution network. Once the power supply system model and distribution network model are obtained, they are coupled at the substation busbar to obtain the complete distribution system linear equations, which comprehensively describe and solve the power flow distribution of the entire distribution network, namely the quantitative relationship between voltage, power injection, and VCD operation at each node. This complete model is the key to achieving efficient and accurate power flow calculations, providing a solid theoretical and mathematical foundation for real-time monitoring, optimal scheduling, and planning decisions of the distribution network.

[0083] In some embodiments, the expression of the power supply system model is specifically:

[0084] For a tap changer without a regulator, the expression is:

[0085]

[0086] For a tap changer with a regulator, the expression is:

[0087]

[0088] Where Δx lv The vector representing the change in electrical variables at the substation bus lv includes the square of the voltage amplitude, the first active power, and the first reactive power. It reflects changes in the operating state of the power system at the substation bus. These changes are affected by both the upstream network and the operation of the transformer and VCD within the substation. It is a key variable connecting the power supply system and the distribution network, and its changes will further affect the power flow distribution within the distribution network. represents the change vector of electrical variables at the upstream network node uv, including the change in active power, reactive power and the square of voltage amplitude, reflecting the slight change in the operating state of the power system at the node uv; J tp1 、J tp2 、J tp3 and J tp4 are all Jacobian matrices; ΔN tr Indicates the change in the transformer tap ratio. By adjusting the tap ratio, the transformer ratio can be changed, thereby achieving voltage regulation; ΔVref Indicates the change in the reference voltage.

[0089] In some embodiments, the expression of the power distribution network model is specifically:

[0090]

[0091] Where, The vector representing the change of electrical variables in the line section of the nth linear component (LNC), including the change of variables such as active power, reactive power and the square of voltage amplitude, reflects the power flow and voltage change of the line under different operating conditions; The Jacobian matrix of the line section in the nth LNC describes the linear relationship between the change of the electrical variables of the line section and the change of the electrical variables of the previous node, reflecting the influence of the electrical characteristics of the line on the power flow distribution; Δx n-1 The vector representing the electrical variable change of the n-1th node, including the changes in the active power, reactive power, and square of the voltage amplitude at the node, serves as an input condition and affects the electrical variable changes of subsequent lines and nodes. The vector representing the change of electrical variables of the direct VCD part in the nth LNC, including the change of variables such as active power, reactive power and the square of voltage amplitude, reflects the operation of the direct VCD under different operating conditions and its impact on power flow distribution; It represents the Jacobian matrix between the direct VCD part and the line part in the nth LNC, describes the linear relationship between the change of the electrical variables of the direct VCD and the change of the electrical variables of the line part, and reflects the impact of the direct VCD on the line power flow; It represents the Jacobian matrix between the direct VCD part and the injection power change in the nth LNC, describes the linear relationship between the change of the electrical variables of the direct VCD and the injection power change, and reflects the impact of the injection power change on the direct VCD action; The power change vector of the direct VCD injected into the nth LNC includes the changes in active power and reactive power, reflecting the impact of the external injected power change on the direct VCD action, and thus affecting the power flow distribution; represents the electrical variable change vector of the fth feeder, the lth branch, and the nth node; The vector representing the change of electrical variables in the line section; Represents the electrical variable change vector of the direct VCD part; Represents the electrical variable change vector of the nth node; represents the Jacobian matrix of the nth node; Represents the load injection power change vector of the nth node.

[0092] It should be noted that the output of the upstream network and substation can be understood as the output of the power supply system model, which can be used as the starting point of the distribution network, that is, as the initial condition of the distribution network model, and can describe the operating status of the distribution network. Among them, the voltage amplitude of the substation bus output by the power supply system model is used to calculate the voltage distribution on the feeder, the output active power and reactive power: the first active power P output by the power supply system model lv and the first reactive power Q lv It is the input to the distribution network model and is used to calculate power flow and voltage changes on feeders. The distribution network model describes the structure of feeders and branches, as well as the characteristics of direct and indirect voltage and discharge (VCD). These models provide the basic data and structure for solving linear equations, enabling the linear equations to accurately describe the electrical relationships in the distribution network. The two are closely linked in the construction and solution of the distribution system model, jointly promoting the establishment and solution process of the linear power flow model for the entire distribution system. The output of the distribution system model is the power flow distribution of the distribution network, which comprehensively reflects the interaction and balance between the voltage, power injection, and VCD action at each node in the distribution network. By establishing and solving the distribution system model, the relationship between these variables can be accurately described and quantified, providing a key basis for the operation and optimization of the distribution network.

[0093] In some embodiments, the expression of the power distribution system model is specifically:

[0094]

[0095] Where, Indicates the fth feeder, the The electrical variable vector of the nth branch and node; Indicates the initial operating conditions, the fth feeder, the The electrical variable vector of the nth branch and node is the reference value for power flow calculation; F is the total number of feeders in the distribution network, which is used to define the scale and scope of the distribution network; i represents the feeder number, which is used to distinguish different feeder paths; L i N represents the number of branches under the i-th feeder, reflecting the structural complexity of the feeder; ij It represents the number of nodes in the jth branch under the i-th feeder, and clarifies the specific composition of the branch; is the sensitivity matrix, the fth feeder, the The sensitivity of the change in the electrical variable of the nth branch and the nth node to the change in the load injection power of the i-th feeder, the j-th branch and the k-th node is used to quantify the mutual influence between the variables, including the first sensitivity matrix assuming discontinuous VCD operation and the second sensitivity matrix assuming continuous VCD operation; is the sensitivity vector, which indicates the sensitivity of the node voltage amplitude change to the voltage change and reflects the electrical coupling relationship between the node and the slack bus; It represents the load injection power change of the i-th feeder, j-th branch, and k-th node, reflecting the change of the active power or reactive power of the node; It represents the square change of the slack bus voltage, reflecting the voltage fluctuation at the system power supply point; It is also a sensitivity vector, reflecting the impact of VCD action on the node electrical variables and quantifying the relationship between VCD operation and node operating status; Δx vcd,ss It represents the change in VCD control parameters, including the tap position change of VCD and other operating parameters, which directly affects the voltage regulation of the distribution network.

[0096] In some embodiments, after obtaining the distribution system model, it is necessary to calculate the voltage amplitude of the substation busbar. The first active power P lv and the first reactive power Q lv Input into the distribution system model, and then use the linear power flow algorithm to convert the complex nonlinear power flow problem into a linear problem for solution. According to the initial operating conditions of the distribution system (such as load level, network configuration, etc.), the first sensitivity matrix (continuous action), the second sensitivity matrix (discrete action) and several sensitivity vectors are calculated. Among them, the first sensitivity matrix describes the linear relationship between node voltage, power and VCD action when the VCD is continuously adjusted (such as continuous change of tap position), the second sensitivity matrix describes the system response when the VCD is actually discretely acted (such as fixed tap step size), and the sensitivity vector contains the sensitivity of the node voltage to the change of the slack bus voltage. and the impact of VCD action on node power

[0097] In some embodiments, the power flow distribution of the power distribution system is obtained based on the first sensitivity matrix, the second sensitivity matrix and each sensitivity vector, specifically as follows: based on the first sensitivity matrix, the change in the electrical variables of the power distribution system under continuous regulation is determined; based on the change in the electrical variables and the VCD control parameters, a second tap position that satisfies the VCD control law is determined; the second tap position is converted into a discrete third tap position that can be used by the actual VCD device, and the power flow distribution of the power distribution system is calculated based on the second sensitivity matrix and the third tap position. Specifically, first, when the first sensitivity matrix is ​​determined, the change in the electrical variables of the system under continuous regulation is calculated based on the first sensitivity matrix; then, based on the change in the electrical variables and the VCD control parameters (such as the reference voltage Vref, the first control parameter r c , the second control parameter xc The second tap position (for OLTC and SVR) that satisfies the control law is determined, and the discrete tap position closest to the calculated tap position, i.e., the third tap position, is selected. This step involves converting the continuously calculated tap position into a discrete position that can be used by the actual VCD device. This process does not directly correspond to a specific letter in the linear equation, but rather involves the processing of the tap position. Finally, the second sensitivity matrix is ​​used in combination with the discrete tap positions to determine the power flow distribution of the distribution system.

[0098] It should be noted that the model output is the power flow distribution of the entire distribution network, specifically the voltage level, power injection, and VCD operating status at each node. This accurately estimates the voltage amplitude, power flow, and device status (such as tap position) at each node in the distribution system. These outputs are obtained by solving the distribution system model and provide a detailed description of the flow and distribution of electrical energy within the distribution network. The output power flow distribution is closely related to the power supply model inputs (voltage amplitude, primary active power, and primary reactive power). These inputs determine the initial state and boundary conditions for the power flow calculation, while the output represents the steady-state operating status of the network under these conditions, taking into account factors such as the distribution network topology, line parameters, load demand, and VCD control characteristics. This input-output relationship demonstrates the model's comprehensive description and precise quantification of the distribution network's operating status, enabling operators to predict and analyze the network's output behavior based on the input conditions, thereby achieving effective management, control, and optimization of the distribution network.

[0099] In this way, by precalculating two sets of sensitivity matrices, the complex process of iterative solution required in traditional methods is avoided, thereby significantly improving the computational efficiency.

[0100] In this way, by calculating the sensitivity matrix and sensitivity vector and calculating the power flow distribution, the mutual influence relationship between electrical variables can be quantitatively analyzed, so as to more accurately calculate the power flow distribution of the distribution system and provide a more accurate basis for stability assessment.

[0101] Step S103: Evaluate the stability of the power system based on the power flow distribution.

[0102] In some embodiments, by analyzing the power transmission, voltage, current and other parameters of each device in the flow distribution results and comparing them with the rated parameters and allowable operating range of the device, it is possible to assess whether the device has abnormal operating conditions such as overload and overheating, and to promptly discover potential equipment failure hazards so that appropriate maintenance and repair measures can be taken to ensure stable operation of the system.

[0103] The embodiment of the present application can provide reliable input for subsequent linear power flow calculations by determining the voltage amplitude, the first active power and the first reactive power of the substation bus, avoiding calculation deviations caused by inaccurate input data, thereby improving the accuracy of stability assessment; by calculating the sensitivity matrix and the sensitivity vector and calculating the power flow distribution, the mutual influence relationship between electrical variables can be quantitatively analyzed, thereby more accurately calculating the power flow distribution of the distribution system, providing a more accurate basis for stability assessment; by coupling the power supply system model and the distribution network model, covering all parts from the upstream network to the substation to the distribution network, it can comprehensively reflect the operation status of the entire power system; based on the power flow distribution, the stability of the power system can be evaluated, and multiple aspects of the power system can be comprehensively considered, and the stability state of the power system can be accurately and comprehensively judged, providing strong support for taking corresponding stability control measures. Compared with the existing technology, the present application can improve the accuracy and comprehensiveness of the stability assessment of the power system.

[0104] Example 2

[0105] Please refer to Figure 5 , Figure 5 1 is a schematic structural diagram of an embodiment of a method for evaluating the stability of a power system provided in the present application, comprising: an acquisition module 100, a calculation model 200, and an evaluation model 300;

[0106] The acquisition module 100 is configured to acquire load parameters of each node in the distribution network and determine a voltage amplitude, a first active power, and a first reactive power of a substation bus based on the load parameters, wherein the load parameters include a second active power and a second reactive power;

[0107] The calculation module 200 is configured to input a preset distribution system model based on the voltage amplitude, the first active power, and the first reactive power, obtain a first sensitivity matrix, a second sensitivity matrix, and a plurality of sensitivity vectors, and obtain a power flow distribution of the distribution system based on the first sensitivity matrix, the second sensitivity matrix, and each of the sensitivity vectors, wherein the distribution system model is obtained by coupling a power supply system model and a distribution network model at a substation bus, the power supply system model is obtained by coupling an upstream network linear model, a substation linear model, and a VCD linear model, and the distribution network model is obtained by coupling an LNC model of each feeder to;

[0108] The evaluation module 300 is used to evaluate the stability of the power system based on the power flow distribution.

[0109] The information interaction, execution process, etc. between the modules within the above-mentioned power system stability assessment system are based on the same concept as the embodiment of the power system stability assessment method of the first aspect of the present invention, and the technical effects achieved are basically the same. For specific contents, please refer to the description in the first embodiment of the method of the present invention, and will not be repeated here.

[0110] The apparatus embodiments described above are merely illustrative, wherein the modules described as separate components may or may not be physically separate, i.e., they may be located in one location or distributed across multiple network elements. Some or all of these elements may be selected based on actual needs to achieve the objectives of the methods of this embodiment.

[0111] See also Figure 6 , Figure 6 The hardware structure of a terminal device according to another embodiment is shown. The terminal device includes:

[0112] The processor 601 may be implemented as a general-purpose CPU (Central Processing Unit), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided in the embodiments of the present application.

[0113] The memory 602 can be implemented in the form of a read-only memory (ROM), a static storage device, a dynamic storage device, or a random access memory (RAM). The memory 602 can store an operating system and other application programs. When the technical solutions provided in the embodiments of this specification are implemented through software or firmware, the relevant program code is stored in the memory 602 and is called by the processor 601 to execute the large model-based dialogue risk assessment method of the embodiments of this application.

[0114] Input / output interface 603, used to implement information input and output;

[0115] Communication interface 604, used to implement communication interaction between this device and other devices, which can be achieved through wired means (such as USB, network cable, etc.) or wireless means (such as mobile network, WiFi, Bluetooth, etc.);

[0116] Bus 605 , which transmits information between various components of the device (e.g., processor 601 , memory 602 , input / output interface 603 , and communication interface 604 );

[0117] The processor 601 , the memory 602 , the input / output interface 603 and the communication interface 604 are connected to each other in communication within the device via a bus 605 .

[0118] The present invention also provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the method for evaluating the stability of the power system as described in the first embodiment above is implemented.

[0119] Those skilled in the art will appreciate that all or part of the processes in the above-described method embodiments can be implemented by instructing related hardware through a computer program. The program can be stored in a computer-monitorable storage medium, and when executed, the program can include the processes in the above-described method embodiments. The storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM).

[0120] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present application in detail. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the scope of protection of the present application.

[0121] It is particularly pointed out that for those skilled in the art, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this application should be included in the scope of protection of this application.

Claims

1. A method for evaluating the stability of a power system, characterized in that: include: Obtaining load parameters of each node in the distribution network, and determining a voltage amplitude, a first active power, and a first reactive power of a substation bus based on the load parameters, wherein the load parameters include a second active power and a second reactive power; A preset distribution system model is input based on the voltage amplitude, the first active power, and the first reactive power, to obtain a first sensitivity matrix, a second sensitivity matrix, and a plurality of sensitivity vectors, and a power flow distribution of the distribution system is obtained based on the first sensitivity matrix, the second sensitivity matrix, and each of the sensitivity vectors, wherein the distribution system model is obtained by coupling a power supply system model and a distribution network model at a substation bus, the power supply system model is obtained by coupling an upstream network linear model, a substation linear model, and a VCD linear model, and the distribution network model is obtained by coupling an LNC model of each feeder to; The stability of the power system is evaluated based on the power flow distribution.

2. The method for evaluating the stability of a power system according to claim 1, wherein: The determining of the voltage amplitude, the first active power, and the first reactive power of the substation bus based on the load parameters is specifically as follows: Determining the active component and reactive component of the transformer output current based on the load parameters and a preset reference voltage; Calculating the substation bus voltage based on the active component, the reactive component, and the reference voltage; if a difference between the substation bus voltage and the reference voltage is greater than a preset threshold, adjusting a first tap position until the substation bus voltage meets a preset condition, and outputting a voltage amplitude of the substation bus; Based on the voltage amplitude, the active component, and the reactive component, the first active power and the first reactive power of the substation bus are respectively calculated.

3. The method for evaluating the stability of a power system according to claim 2, wherein: The calculation formula for calculating the substation bus voltage based on the active component, the reactive component and the reference voltage is specifically: V lv =V ref +r c I lv,a +x c I lv,r ; Where V lv is the substation bus voltage; V ref is the desired reference voltage; r c and x c are the adjustment weights of VCD for active and reactive components respectively; I lv,a is the active component of the transformer output current; I lv,r is the reactive component of the transformer output current.

4. The method for evaluating the stability of a power system according to claim 1, wherein: The expression of the power distribution system model is specifically: Where, Indicates the fth feeder, the The electrical variable vector of the nth branch and node; Indicates the initial operating conditions, the fth feeder, the The electrical variable vector of the nth branch and node is the reference value for power flow calculation; F is the total number of feeders in the distribution network, which is used to define the scale and scope of the distribution network; i represents the feeder number, which is used to distinguish different feeder paths; L i N represents the number of branches under the i-th feeder, reflecting the structural complexity of the feeder; ij It represents the number of nodes in the jth branch under the i-th feeder, and clarifies the specific composition of the branch; is the sensitivity matrix, the fth feeder, the The sensitivity of the change in the electrical variable of the nth branch and the nth node to the change in the load injection power of the i-th feeder, the j-th branch and the k-th node is used to quantify the mutual influence between the variables, including the first sensitivity matrix assuming discontinuous VCD operation and the second sensitivity matrix assuming continuous VCD operation; is the sensitivity vector, which indicates the sensitivity of the node voltage amplitude change to the voltage change and reflects the electrical coupling relationship between the node and the slack bus; It represents the load injection power change of the i-th feeder, j-th branch, and k-th node, reflecting the change of the active power or reactive power of the node; It represents the square change of the slack bus voltage, reflecting the voltage fluctuation at the system power supply point; It is also a sensitivity vector, reflecting the impact of VCD action on the node electrical variables and quantifying the relationship between VCD operation and node operating status; Δx vcd,ss It represents the change in VCD control parameters, including the tap position change of VCD and other operating parameters, which directly affects the voltage regulation of the distribution network.

5. The method for evaluating the stability of a power system according to claim 1, wherein: The power flow distribution of the power distribution system is obtained based on the first sensitivity matrix, the second sensitivity matrix and each of the sensitivity vectors, specifically: determining, based on the first sensitivity matrix, a change in an electrical variable of the power distribution system under continuous regulation; Determining a second tap position that satisfies a VCD control law based on the electrical variable change and the VCD control parameter; The second tap position is converted into a discrete third tap position that can be used by an actual VCD device, and the power flow distribution of the power distribution system is calculated based on the second sensitivity matrix and the third tap position.

6. The method for evaluating the stability of a power system according to claim 2, wherein: The expression of the power supply system model is specifically: For a tap changer without a regulator, the expression is: For a tap changer with a regulator, the expression is: Where Δx lv The vector representing the change in electrical variables at the substation bus lv includes the square of the voltage amplitude, the first active power, and the first reactive power. It reflects changes in the operating state of the power system at the substation bus. These changes are affected by both the upstream network and the operation of the transformer and VCD within the substation. It is a key variable connecting the power supply system and the distribution network, and its changes will further affect the power flow distribution within the distribution network. represents the change vector of electrical variables at the upstream network node uv, including the change in active power, reactive power and the square of voltage amplitude, reflecting the slight change in the operating state of the power system at the node uv; J tp1 、J tp2 、J tp3 and J tp4 are all Jacobian matrices; ΔN tr Indicates the change in the transformer tap ratio. By adjusting the tap ratio, the transformer ratio can be changed, thereby achieving voltage regulation; ΔV ref Indicates the change in the reference voltage.

7. The method for evaluating the stability of a power system according to claim 1, wherein: The expression of the power distribution network model is specifically: Where, The vector representing the change of electrical variables in the line section of the nth linear component (LNC), including the change of variables such as active power, reactive power and the square of voltage amplitude, reflects the power flow and voltage change of the line under different operating conditions; The Jacobian matrix of the line section in the nth LNC describes the linear relationship between the change of the electrical variables of the line section and the change of the electrical variables of the previous node, reflecting the influence of the electrical characteristics of the line on the power flow distribution; Δx n-1 The vector representing the electrical variable change of the n-1th node, including the changes in the active power, reactive power, and square of the voltage amplitude at the node, serves as an input condition and affects the electrical variable changes of subsequent lines and nodes. The vector representing the change of electrical variables of the direct VCD part in the nth LNC, including the change of variables such as active power, reactive power and the square of voltage amplitude, reflects the operation of the direct VCD under different operating conditions and its impact on power flow distribution; It represents the Jacobian matrix between the direct VCD part and the line part in the nth LNC, describes the linear relationship between the change of the electrical variables of the direct VCD and the change of the electrical variables of the line part, and reflects the impact of the direct VCD on the line power flow; It represents the Jacobian matrix between the direct VCD part and the injection power change in the nth LNC, describes the linear relationship between the change of the electrical variables of the direct VCD and the injection power change, and reflects the impact of the injection power change on the direct VCD action; The power change vector of the direct VCD injected into the nth LNC includes the changes in active power and reactive power, reflecting the impact of the external injected power change on the direct VCD action, and thus affecting the power flow distribution; represents the electrical variable change vector of the fth feeder, the lth branch, and the nth node; The vector representing the change of electrical variables in the line section; Represents the electrical variable change vector of the direct VCD part; Represents the electrical variable change vector of the nth node; represents the Jacobian matrix of the nth node; Represents the load injection power change vector of the nth node.

8. A stability assessment system for a power system, characterized in that: include: Acquisition modules, calculation models and evaluation models; The acquisition module is configured to acquire load parameters of each node in the distribution network, and determine a voltage amplitude, a first active power, and a first reactive power of a substation bus based on the load parameters, wherein the load parameters include a second active power and a second reactive power; The calculation module is configured to input a preset distribution system model based on the voltage amplitude, the first active power, and the first reactive power, obtain a first sensitivity matrix, a second sensitivity matrix, and a plurality of sensitivity vectors, and obtain a power flow distribution of the distribution system based on the first sensitivity matrix, the second sensitivity matrix, and each of the sensitivity vectors, wherein the distribution system model is obtained by coupling a power supply system model and a distribution network model at a substation bus, the power supply system model is obtained by coupling an upstream network linear model, a substation linear model, and a VCD linear model, and the distribution network model is obtained by coupling an LNC model of each feeder to; The evaluation module is used to evaluate the stability of the power system based on the power flow distribution.

9. A terminal device, characterized in that: include: one or more processors; a memory, coupled to the processor, for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the power system stability assessment method according to any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for evaluating the stability of a power system according to any one of claims 1 to 7 is implemented.

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