Electromechanical transient simulation method and system for voltage stability of power system

Abstract

The invention discloses an electromechanical transient simulation method and system for the voltage stability of a power system, and the method comprises the steps: obtaining data after the system is disturbed, and obtaining a time constant when a load is disturbed to recover to a steady state, and a proportion coefficient related to a static active load and a reactive load through a parameter identification algorithm; listing a conventional ZIP static load model, constructing a dynamic ZIP load model by adopting a proportional integral differential link and an amplitude limiting link, and reflecting an input-output relationship between active and reactive loads and equivalent impedance; determining a system balance point according to a steady-state power flow calculation result, performing linearization processing on all dynamic equations of the whole network at the balance point to obtain a state space model, calculating a state matrix eigenvalue, and judging a voltage stability condition of a bus where a load is located according to a sign of a real part of a related eigenvalue; and performing dynamic time domain simulation on the adjusted system, applying N-1 or N-2 type line faults to the whole network, and simulating a possible voltage collapse scene of the system. And a theoretical support is provided for providing countermeasures after voltage instability.

Description

Background Art

[0002] With the deepening of voltage stability research, the problem of dynamic load modeling has further attracted the attention of researchers. It is generally believed that the static voltage characteristics of the load have an extremely important impact on the voltage stability of the system. In engineering, the voltage-power (VP or VQ) transfer characteristic curve of the power system, that is, the famous nose curve, is often used to analyze the static voltage stability of the power system. Generally speaking, the power system needs to operate under a certain margin with the nose point to ensure voltage stability. By adjusting the network parameters, the static voltage stability boundary required by the system can be ensured and the static voltage stability limit of the system can be improved. The nose curve of the power system actually reflects the dominant position of the dynamic characteristics of the load in the study of voltage stability: first, as the voltage at the node where the load is located decreases, the load absorbs reactive power from the system, thereby worsening the reactive balance of the system, and further forming a positive feedback mechanism of voltage drop; second, after the voltage drops, the load has the characteristics of dynamic recovery, and the active and reactive power will recover to a certain level at a certain speed, and even recover to the original level in extreme cases; third, the inherent characteristics of the dynamic load are to automatically adjust the equivalent impedance to achieve the active / reactive balance of the system.

[0003] Qualitatively, the dynamic load model used for voltage stability research must meet this inherent nature, that is, automatically adjust the equivalent impedance to maintain the active / reactive balance of the system. In addition, the load model also needs to be consistent with the static voltage stability analysis results in the stability analysis of the equilibrium point, and can effectively simulate voltage collapse in the transient process simulation, so as to achieve the purpose of unifying the transient simulation and the static voltage stability analysis results after the fault.

[0004] Based on the ZIP model, which is the most commonly used comprehensive load model in the industry, this invention proposes a modified ZIP load model. While accurately describing the load port characteristics, this model is used to conduct extensive quantitative research on voltage stability issues, reflecting the essential dynamic characteristics related to voltage instability. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method and system for electromechanical transient simulation of power system voltage stability in view of the deficiencies in the above-mentioned prior art, so as to solve the technical problem that the existing industrial load model is difficult to reflect the essence of voltage instability, conduct quantitative research on power system voltage stability, and accurately characterize the transient process of power system voltage instability.

[0006] The present invention adopts the following technical solutions: A method for simulating electromechanical transient state of voltage stability of a power system, comprising the following steps: S1. Obtain data on transient changes in voltage, active power and reactive power of the bus where the load is located after the system is disturbed, and use a parameter identification algorithm to obtain the time constant for the load to recover to a steady state, the proportional coefficients related to the static active load and reactive load, and the proportional coefficients related to the reactive load include constant power proportion, constant current proportion and constant impedance proportion parameters; S2. Based on the parameters obtained in step S1, a conventional ZIP static load model is written, load equivalent resistance and equivalent reactance are introduced as state variables of the dynamic load model, and a dynamic ZIP load model is constructed using a proportional integral differential link and a limiting link to reflect the input-output relationship between active and reactive loads and equivalent impedances; S3. Determine the system equilibrium point according to the steady-state power flow calculation results of step S2, and linearize all dynamic equations of the entire network at the equilibrium point to obtain a state space model, calculate the eigenvalue of the state matrix, and judge the voltage stability of the bus where the load is located according to the positive and negative signs of the real parts of the relevant eigenvalues; S4. Perform dynamic time domain simulation on the adjusted system, impose N-1 or N-2 type line faults on the entire network, and simulate the voltage collapse scenario that may occur in the system.

[0007] Preferably, step S2 specifically includes: S201, introducing load equivalent resistance as a state variable, the rate of change of the equivalent resistance is proportional to the difference between the actual active power at the measurement point and the active power calculated by the ZIP static load model, indicating that when the active power taken is lower than the required active power, a greater active power can be obtained by reducing its own resistance; S202, introducing load equivalent reactance as a state variable, the change rate of the equivalent reactance is proportional to the difference between the reactive power calculated by the ZIP static load model and the actual reactive power at the measuring point, indicating that when the active power taken is lower than the required active power, a greater active power can be obtained by increasing its own resistance; S203. Add a network connection equation to describe the relationship between the voltage, current and power of the bus where the load is located.

[0008] Preferably, the dynamic ZIP model is:

[0009]

[0010] in, It is the inverse of the active / reactive power recovery time constant; is the maximum / minimum value of the load equivalent resistance; is the maximum / minimum value of the load equivalent reactance; , and They are respectively the active power, reactive power and node voltage absorbed by the load in the steady state before the system is disturbed; , and They respectively represent the active power, reactive power and node voltage absorbed by the load after being disturbed; and Respectively represent the equivalent resistance and equivalent reactance of the load; coefficient a , b and c Respectively represent the proportion of constant impedance, constant current and constant power in the total load, and the subscript " p "and" q " represents the corresponding active and reactive power situations.

[0011] Preferably, the interface equation between the dynamic load model and the network is as follows:

[0012]

[0013]

[0014]

[0015]

[0016] in, represents the real / imaginary part of the receiving node voltage, Represents the real / imaginary part of the current flowing through the transmission line; and They represent the equivalent resistance and equivalent reactance of the load respectively; , and They respectively represent the active power, reactive power and node voltage absorbed by the load after being disturbed.

[0017] Preferably, in step S3, the voltage stability of the bus where the load is located is judged according to the positive and negative signs of the real parts of the relevant eigenvalues, the eigenvalues ​​of the coefficient matrix are calculated, and the relationship between the system eigenvalues ​​and the voltage stability of the power system is observed. The coefficient matrix is ​​specifically:

[0018] in, and is the equivalent resistance of the load and equivalent reactance The differential of Represents the receiving node voltage The real / imaginary part of the initial value, Indicates the current flowing through the transmission line The real / imaginary part of the initial value; It represents the initial value of equivalent resistance and equivalent reactance before the load is disturbed. Indicates the resistance and reactance of the transmission line; and They respectively represent the active power and reactive power absorbed by the load after being disturbed.

[0019] Preferably, the steady-state value of the line current is:

[0020] in, is the power supply voltage, is the line impedance amplitude, is the load equivalent impedance amplitude, is the line impedance power factor angle, is the load impedance power factor angle.

[0021] Preferably, the steady-state value of the receiving-end voltage is:

[0022] in, is the power supply voltage, is the line impedance amplitude, is the load equivalent impedance amplitude, is the line impedance power factor angle, is the load impedance power factor angle.

[0023] Preferably, step S4 is specifically: S401. Under the premise that the steady-state solution of the power flow calculation is used as the initial solution, the electromechanical transient simulation is performed on the whole system, the N-1 or N-2 type fault event set of the key line is defined, and batch operations are performed according to the expected fault event set, and the relevant transient simulation results are saved; S402, collecting node voltage change data of all buses in the entire network in the simulation results, evaluating the system's dynamic response capability for voltage recovery after a fault, and determining whether the voltage collapses in the fault scenario.

[0024] Preferably, the changes in voltage near the load center node due to large disturbances are recorded to determine the system voltage stability, screen the load nodes far away from the power center, list the lines connected to the load nodes at the head or end as lines to be disconnected, and simulate various possible line disconnection situations to form a line disconnection fault set.

[0025] In a second aspect, an embodiment of the present invention provides a power system voltage stability electromechanical transient simulation system, comprising: The data module obtains the data of transient changes in voltage, active power and reactive power of the bus where the load is located after the system is disturbed, and uses the parameter identification algorithm to obtain the time constant of the load recovery from the disturbance to the steady state, the proportional coefficient related to the static active load and the reactive load. The proportional coefficient related to the reactive load includes constant power proportion, constant current proportion and constant impedance proportion parameters; The construction module writes the conventional ZIP static load model based on the parameter list, introduces the load equivalent resistance and equivalent reactance as the state variables of the dynamic load model, and uses the proportional integral differential link and the limit link to construct the dynamic ZIP load model to reflect the input-output relationship between the active and reactive loads and the equivalent impedance; The calculation module determines the system equilibrium point based on the steady-state power flow calculation results, linearizes all dynamic equations of the entire network at the equilibrium point to obtain a state space model, calculates the eigenvalues ​​of the state matrix, and determines the voltage stability of the bus where the load is located based on the positive and negative signs of the real parts of the relevant eigenvalues; The simulation module performs dynamic time-domain simulation on the adjusted system, imposes N-1 or N-2 type line faults on the entire network, and simulates the voltage collapse scenario that may occur in the system.

[0026] In a third aspect, a computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above-mentioned method for electromechanical transient simulation of voltage stability of a power system when executing the computer program.

[0027] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, comprising a computer program, which, when executed by a processor, implements the steps of the above-mentioned method for electromechanical transient simulation of power system voltage stability.

[0028] Compared with the prior art, the present invention has at least the following beneficial effects: An electromechanical transient simulation method for power system voltage stability is used for transient process analysis of voltage at load nodes in power system. Compared with the original static ZIP load model, it can reflect the dynamic characteristics of voltage change from two aspects: small disturbance voltage stability analysis and large disturbance transient voltage stability.

[0029] Furthermore, the input-output relationship between the active load equivalent resistance adjustment characteristics and its dynamic characteristics is constructed, which is the basic model for the voltage stability analysis of the load node of the present invention. This model is essentially a type of differential equation that describes the dynamic change of the active load equivalent resistance, reflecting the adjustment of the load equivalent resistance after the active power balance of the power system is destroyed. It can be easily applied to small disturbance stability analysis and electromechanical transient simulation, and it is easy to form an objective and clear static voltage stability criterion; the input-output relationship between the active load equivalent reactance adjustment characteristics and its dynamic characteristics is constructed, which is the basic model for the voltage stability analysis of the load node of the present invention. Based on the logic of the constructed equivalent resistance dynamic model, the model supplements the influence of reactive load characteristics on the static stability of the system voltage and simplifies the physical law of reactive support of the load node voltage; the network interface algebraic relationship between the active load, reactive load and the electrical quantity of the load node is established using the xy coordinate system, which is the key step for the small disturbance stability analysis and electromechanical transient simulation of the present invention.

[0030] Furthermore, the core algorithm of the present invention is to conduct small disturbance voltage stability analysis for a specific system and accurately provide a generalized practical criterion for the static voltage stability of the power system. Based on the model established in step 2, the algorithm quantitatively points out the small disturbance analysis results when the system is running in the upper and lower halves of the nose curve, so that the static voltage stability of the power system can be determined by the characteristic value properties of the resistance reactance state variables.

[0031] Furthermore, constructing an N-1 or N-2 fault prediction set is a key step in the present invention to perform electromechanical transient simulation of voltage stability. For load center nodes where static voltage instability or voltage collapse may occur, the lines near the node are selected to be disconnected and screened to form a line fault set; performing large-interference voltage stability transient simulation on a specific system is the core algorithm of the present invention. Based on the model established in step S2 and the established fault set, the time domain simulation results can record the changes in load node voltage after the system is subjected to a large disturbance. According to the simulation results, it can be clearly judged whether the load node voltage remains at an acceptable level.

[0032] It can be understood that the beneficial effects of the second aspect mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here.

[0033] In summary, the method of the present invention can be used to analyze the system voltage stability, find out the weak load nodes of the system voltage stability and the key links that restrict the system voltage stability, and provide theoretical support for proposing countermeasures after voltage instability.

[0034] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings to be used in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 It is a schematic diagram of the process of the present invention; Figure 2 A dynamic ZIP model constructed using a simple integration link; Figure 3 For simple power system; Figure 4 A schematic diagram of a computer device provided by an embodiment of the present invention; Figure 5 A block diagram of an electronic device provided according to an embodiment of the present invention; Figure 6 It is a simple power system node voltage simulation curve diagram; Figure 7 This is a diagram showing the load impedance changes after a simple power system is disturbed; Figure 8 It is the active and reactive load diagram of a simple power system after being disturbed; Fig. 9 It is the topology diagram and voltage distribution diagram of IEEE14 system; Fig.10 This is a diagram of the node voltage changes in the IEEE14 system. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] In the description of the present invention, it should be understood that the terms “include” and “comprises” indicate the presence of described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0039] It should also 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, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0040] It should be further understood that the term "and / or" used in the present specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects are in an "or" relationship.

[0041] It should be understood that, although the terms first, second, third, etc. may be used to describe preset ranges, etc. in the embodiments of the present invention, these preset ranges should not be limited to these terms. These terms are only used to distinguish preset ranges from each other. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0042] The word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0043] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0044] The present invention provides a method for electromechanical transient simulation of voltage stability of power system. Based on the comprehensive load model ZIP model, a differential dynamic equation with load equivalent impedance as state variable is constructed, and the input-output relationship between active / reactive unbalance and equivalent impedance is described by using proportional integral link. On this basis, combined with the network interface algebraic equation, small disturbance stability analysis can be conveniently performed, revealing the non-periodic instability mechanism of voltage at the balance point, and can be used for transient simulation of bus voltage collapse. The dynamic load model proposed by the present invention uses resistance reactance as the state variable in the dynamic load model, avoiding the static constant power characteristics of the previous load model, allowing active and reactive loads to undergo step changes after being disturbed, and has a wider range of application and is more in line with the dynamic response mechanism of the actual load. In addition, the small disturbance stability analysis algorithm and batch fault voltage transient stability simulation algorithm proposed on the basis of the dynamic load model proposed by the present invention cross-verify the static voltage stability of the power system from the theoretical and simulation levels, respectively, avoiding the limitation of the traditional nose curve in judging stability according to the transmission power limit point, and revealing the connection between the static voltage stability of the system and the dynamic characteristics of the load.

[0045] See also Figure 1 The present invention provides a method for simulating the electromechanical transient state of voltage stability of a power system, comprising the following steps: S1. Obtain data on transient changes in voltage, active and reactive power of the bus where the load is located after the system is disturbed, and use parameter identification algorithm to obtain the time constant for the load to recover to a steady state, the proportional coefficients related to the static active load and reactive load, and the latter includes constant power ratio, constant current ratio and constant impedance ratio parameters; The input data of the calculation model obtained from relevant departments include the following data: The basic technical data for voltage stability analysis include: The time constant for the load to recover from disturbance to steady state, the constant active power ratio, the constant active current ratio, the constant active resistance ratio, the constant reactive power ratio, the constant reactive current ratio, and the constant reactive reactance ratio.

[0046] S2. Write a conventional ZIP static load model, introduce load equivalent resistance and equivalent reactance as state variables of the dynamic load model, and use proportional integral differential link and limit link to build a dynamic ZIP load model to reflect the input-output relationship between active and reactive loads and equivalent impedance; Establish the ZIP comprehensive load model and network handover equation, specifically: (1) Establish a polynomial ZIP static load model based on the static active proportional coefficient and the static reactive proportional coefficient: (1) (2) in, is the constant resistance ratio / constant reactance ratio; It is the constant active current ratio / constant reactive current ratio; It is the constant active load ratio / constant reactive load ratio; It is the active power / reactive power absorbed by the load in the steady state before the system is disturbed; It is the active power / reactive power actually absorbed by the load; The node voltage amplitude of the bus where the load is located in the steady state before the system is disturbed; is the node voltage amplitude of the bus where the load is located; The proportionality coefficients satisfy the following relationship: (3) (2) Establish the connection between the load model and the power network (4) (5) (6) in, is the real / imaginary part of the node voltage; The real / imaginary part of the current injected into the node.

[0047] Based on the fact that the load power regulation needs to be achieved through its own internal impedance regulation, the model is dynamically modified. The specific steps are as follows: S201. Introduce load equivalent resistance as a state variable. The rate of change of equivalent resistance (i.e., the derivative of equivalent resistance with respect to time) is proportional to the difference between the actual active power at the measurement point and the active power calculated by the ZIP static load model, indicating that when the active power taken is lower (higher) than the required active power, a greater (less) active power can be obtained by reducing (increasing) its own resistance; S202, introduce load equivalent reactance as a state variable, the rate of change of equivalent reactance (i.e., the derivative of equivalent reactance with respect to time) is proportional to the difference between the reactive power calculated by the ZIP static load model and the actual reactive power at the measuring point, indicating that when the active power taken is lower (higher) than the required active power, a greater (less) active power can be obtained by increasing (decreasing) its own resistance; S203. Add a network connection equation to describe the relationship between the voltage, current and power of the bus where the load is located.

[0048] The specific steps to establish a dynamic ZIP model are: Introduce load equivalent internal resistance and internal reactance to determine the change of load equivalent impedance The load equivalent resistance is defined as , the load equivalent reactance is Assuming that the voltage remains unchanged, the active power and Inversely proportional to the reactive power and Inversely proportional. When Reduce (increase) active power gain, increase (decrease) Increase (decrease) reactive power gain.

[0049] The PID (proportional integral differential) control link is used to describe the change of the load equivalent impedance, and the limit link is used to smooth the resistance reactance and limit the load level. Here, the simplest proportional integral link and limit link are taken as an example to establish a dynamic ZIP load model. Other more complex load dynamic behaviors are achieved by adding differential links, etc.: (7) (8) in, It is the active / reactive power demand of the conventional ZIP comprehensive load model.

[0050] according to Figure 2 The schematic diagram of the dynamic ZIP model constructed by the integral link constructs the dynamic change characteristics of the resistance reactance, and the generated resistance reactance is incorporated into the load node to achieve the steady-state characteristics of the ZIP model through self-regulation. Under this simulation structure, the dynamic ZIP load model is described as: (9) (10) in, It is the inverse of the active / reactive power recovery time constant; is the maximum / minimum value of the load equivalent resistance; It is the maximum / minimum value of the load equivalent reactance.

[0051] The interface equation between the dynamic load model and the network is established as follows: (11) (12) (13) (14) (15) S3. Determine the system equilibrium point based on the steady-state power flow calculation results, and perform linear processing on all dynamic equations of the entire network at the equilibrium point to obtain a state space model, calculate the state matrix eigenvalues, and determine the voltage stability of the bus where the load is located based on the positive and negative signs of the real parts of the relevant eigenvalues; See also Figure 3 , taking a simple power system as an example, a constant voltage source is connected to a dynamic ZIP load through two transmission lines; the power supply voltage is , the parallel impedance of the two transmission lines is , the load impedance is The steady-state value of the line current can be calculated as: (16) The steady-state value of the receiving terminal voltage is: (17) From equations (16) and (17), we can know that the real part of the steady-state value of the line current is and the imaginary part , the real part of the steady-state value of the receiving terminal voltage and the imaginary part , and the steady-state value of the load equivalent impedance and They are and . In addition, the network equation is supplemented as follows: (18) (19) in, , .

[0052] For simplicity, let the constant power portion of the dynamic ZIP load account for 100%, and linearize equations (9) to (15), (18) and (19) to obtain the following equations: (20) The eigenvalue of the coefficient matrix of equation (20) is calculated, and the relationship between the system eigenvalue and the voltage stability of the power system is observed.

[0053] S4. Perform dynamic time domain simulation on the adjusted system, impose N-1 or N-2 type line faults on the entire network, and simulate the voltage collapse scenario that may occur in the system.

[0054] A set of potential line break faults that may lead to voltage collapse is formed, and batch electromechanical transient simulation operations are carried out on this basis to record the changes in voltage near the load center node when it is subject to large disturbances, judge the system voltage stability, screen the load nodes that are far away from the power center (that is, the electrical connection with the power center is weak), and list the lines connected to the load nodes at the head or end as lines to be disconnected. Various possible line break situations are simulated to form a set of line break faults, such as single-line break, double-line break, etc.

[0055] S401. Under the premise that the steady-state solution of the power flow calculation is used as the initial solution, the electromechanical transient simulation is performed on the whole system, the N-1 or N-2 type fault event set of the key line is defined, and batch operations are performed according to the expected fault event set, and the relevant transient simulation results are saved; S402, collecting node voltage change data of all buses in the entire network in the simulation results, evaluating the system's dynamic response capability for voltage recovery after a fault, and determining whether the voltage collapses in the fault scenario.

[0056] It will be appreciated by those skilled in the art that various aspects of the present invention may be implemented as systems, methods or program products. Therefore, various aspects of the present invention may be specifically implemented in the following forms, namely: complete hardware implementation, complete software implementation (including firmware, microcode, etc.), or a combination of hardware and software implementations, which may be collectively referred to herein as "circuits", "modules" or "platforms".

[0057] In another embodiment of the present invention, a power system voltage stability electromechanical transient simulation system is provided, which can be used to implement the above-mentioned power system voltage stability electromechanical transient simulation method. Specifically, the power system voltage stability electromechanical transient simulation system includes a data module, a construction module, a calculation module and a simulation module.

[0058] The data module obtains data on transient changes in voltage, active and reactive power of the bus where the load is located after the system is disturbed, and uses a parameter identification algorithm to obtain the time constant for the load to recover to a steady state, the proportional coefficients related to the static active load and reactive load, and the proportional coefficients related to the reactive load include constant power proportion, constant current proportion and constant impedance proportion parameters; The construction module writes the conventional ZIP static load model based on the parameter list, introduces the load equivalent resistance and equivalent reactance as the state variables of the dynamic load model, and uses the proportional integral differential link and the limit link to construct the dynamic ZIP load model to reflect the input-output relationship between the active and reactive loads and the equivalent impedance; The calculation module determines the system equilibrium point based on the steady-state power flow calculation results, linearizes all dynamic equations of the entire network at the equilibrium point to obtain a state space model, calculates the eigenvalues ​​of the state matrix, and determines the voltage stability of the bus where the load is located based on the positive and negative signs of the real parts of the relevant eigenvalues; The simulation module performs dynamic time-domain simulation on the adjusted system, imposes N-1 or N-2 type line faults on the entire network, and simulates the voltage collapse scenario that may occur in the system.

[0059] In another embodiment of the present invention, a terminal device is provided, which includes a processor and a memory, wherein the memory is used to store a computer program, the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, and is specifically suitable for loading and executing one or more instructions to implement the corresponding method flow or corresponding function; the processor described in the embodiment of the present invention can be used for the operation of the electromechanical transient simulation method of power system voltage stability, including: Obtain data on transient changes in voltage, active and reactive power of the bus where the load is located after the system is disturbed, and use parameter identification algorithms to obtain the time constant for the load to recover to a steady state, the proportional coefficients related to the static active load and reactive load. The proportional coefficients related to the reactive load include constant power proportion, constant current proportion and constant impedance proportion parameters; write a conventional ZIP static load model based on the obtained parameters, introduce load equivalent resistance and equivalent reactance as state variables of the dynamic load model, and use proportional integral differential links and limiting links to construct a dynamic ZIP load model to reflect the input-output relationship between active and reactive loads and equivalent impedances; determine the system equilibrium point based on the steady-state power flow calculation results, and linearize all dynamic equations of the entire network at the equilibrium point to obtain a state space model, calculate the eigenvalues ​​of the state matrix, and judge the voltage stability of the bus where the load is located based on the positive and negative signs of the real parts of the relevant eigenvalues; perform dynamic time domain simulation on the adjusted system, impose N-1 or N-2 type line faults on the entire network, and simulate the voltage collapse scenario that may occur in the system.

[0060] In another embodiment of the present invention, the present invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a terminal device for storing programs and data. It is understandable that the computer-readable storage medium here can include both the built-in storage medium in the terminal device and the extended storage medium supported by the terminal device, and can be any tangible medium containing or storing a program, which can be used by an instruction execution system, device or device or used in combination with it. The computer-readable storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by the processor are also stored in the storage space, and these instructions can be one or more computer programs (including program codes). It should be noted that more specific examples (non-exhaustive list) of the computer-readable storage medium here include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0061] Computer readable storage media also include data signals propagated in baseband or as part of a carrier wave, which carry readable program codes. Such propagated data signals can take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. The readable storage medium can also be any readable medium other than a readable storage medium, which can send, propagate, or transmit a program for use by or in conjunction with an instruction execution system, device, or device. The program code contained on the readable storage medium can be transmitted using any appropriate medium, including but not limited to wireless, wired, optical cable, RF, etc., or any suitable combination of the above.

[0062] Program code for performing the operations of the present invention may be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java, C++, etc., and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user computing device, partially on the user device, as a separate software package, partially on the user computing device and partially on a remote computing device, or entirely on a remote computing device or server. In the case of a remote computing device, the remote computing device may be connected to the user computing device through any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computing device (e.g., through the Internet using an Internet service provider).

[0063] One or more instructions stored in a computer-readable storage medium may be loaded and executed by a processor to implement the corresponding steps of the electromechanical transient simulation method for voltage stability of a power system in the above embodiment; one or more instructions in the computer-readable storage medium may be loaded and executed by a processor as follows: Obtain data on transient changes in voltage, active and reactive power of the bus where the load is located after the system is disturbed, and use parameter identification algorithms to obtain the time constant for the load to recover to a steady state, the proportional coefficients related to the static active load and reactive load. The proportional coefficients related to the reactive load include constant power proportion, constant current proportion and constant impedance proportion parameters; write a conventional ZIP static load model based on the obtained parameters, introduce load equivalent resistance and equivalent reactance as state variables of the dynamic load model, and use proportional integral differential links and limiting links to construct a dynamic ZIP load model to reflect the input-output relationship between active and reactive loads and equivalent impedances; determine the system equilibrium point based on the steady-state power flow calculation results, and linearize all dynamic equations of the entire network at the equilibrium point to obtain a state space model, calculate the eigenvalues ​​of the state matrix, and judge the voltage stability of the bus where the load is located based on the positive and negative signs of the real parts of the relevant eigenvalues; perform dynamic time domain simulation on the adjusted system, impose N-1 or N-2 type line faults on the entire network, and simulate the voltage collapse scenario that may occur in the system.

[0064] See also Figure 4 , the terminal device is a computer device, and the computer device 60 of this embodiment includes: a processor 61, a memory 62, and a computer program 63 stored in the memory 62 and executable on the processor 61. When the computer program 63 is executed by the processor 61, the method for simulating the electromechanical transient state of the voltage stability of the power system in the embodiment is implemented. To avoid repetition, it is not described one by one here. Alternatively, when the computer program 63 is executed by the processor 61, the functions of each model / unit in the electromechanical transient state simulation system for the voltage stability of the power system in the embodiment are implemented. To avoid repetition, it is not described one by one here.

[0065] The computer device 60 may be a computing device such as a desktop computer, a notebook, a PDA, or a cloud server. The computer device 60 may include, but is not limited to, a processor 61 and a memory 62. Those skilled in the art will appreciate that Figure 4 This is only an example of the computer device 60 and does not constitute a limitation of the computer device 60. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the computer device may also include input and output devices, network access devices, buses, etc.

[0066] The processor 61 may be a central processing unit (CPU), or other general-purpose processors, central processing units, graphics processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, data processing logic based on quantum computing, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may be any conventional processor, etc.

[0067] The memory 62 may be an internal storage unit of the computer device 60, such as a hard disk or memory of the computer device 60. The memory 62 may also be an external storage device of the computer device 60, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc., equipped on the computer device 60.

[0068] Furthermore, the memory 62 may include both an internal storage unit of the computer device 60 and an external storage device. The memory 62 is used to store computer programs and other programs and data required by the computer device. The memory 62 may also be used to temporarily store data that has been output or is to be output.

[0069] Any reference to a memory, database or other medium used in the embodiments provided in the present application may include at least one of a non-volatile and a volatile memory. Non-volatile memory may include a read-only memory (ROM), a magnetic tape, a floppy disk, a flash memory, an optical memory, a high-density embedded non-volatile memory, a resistive random access memory (ReRAM), a magnetic random access memory (MRAM), a ferroelectric random access memory (FRAM), a phase change memory (PCM), a graphene memory, etc. Volatile memory may include a random access memory (RAM) or an external cache memory, etc. As an illustration and not limitation, RAM may be in various forms, such as a static random access memory (SRAM) or a dynamic random access memory (DRAM), etc.

[0070] The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. The non-relational database may include a distributed database based on blockchain, etc., but is not limited thereto. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but is not limited thereto.

[0071] See also Figure 5 The terminal device 600 is an electronic device, and the electronic device is in the form of a general computing device. The components of the electronic device may include but are not limited to: at least one processing unit 610, at least one storage unit 620, a bus 630 connecting different platform components (including the storage unit 620 and the processing unit 610), a display unit 640, etc.

[0072] The storage unit stores program codes, which can be executed by the processing unit 610, so that the processing unit 610 performs the steps according to various exemplary embodiments of the present invention described in the above method section of this specification. For example, the processing unit 610 can perform the following steps: Figure 1 Follow the steps shown in .

[0073] The storage unit 620 may include a readable medium in the form of a volatile storage unit, such as a random access memory unit (RAM) 6201 and / or a cache memory unit 6202 , and may further include a read-only memory unit (ROM) 6203 .

[0074] The storage unit 620 may also include a program / utility 6204 having a set (at least one) of program modules 6205, such program modules 6205 including but not limited to: an operating system, one or more application programs, other program modules, and program data, each of which or some combination may include an implementation of a network environment.

[0075] Bus 630 may represent one or more of several types of bus structures, including a memory unit bus or memory unit controller, a peripheral bus, an accelerated graphics port, a processing unit, or a local bus using any of a variety of bus architectures.

[0076] The electronic device 600 may also communicate with one or more external devices 700 (e.g., keyboards, pointing devices, Bluetooth devices, etc.), may also communicate with one or more devices that enable a user to interact with the electronic device 600, and / or communicate with any device that enables the electronic device 600 to communicate with one or more other computing devices (e.g., routers, modems, etc.). Such communication may be performed via an input / output (I / O) interface 650. Furthermore, the electronic device 600 may also communicate with one or more networks (e.g., a local area network (LAN), a wide area network (WAN), and / or a public network, such as the Internet) via a network adapter 660. The network adapter 660 may communicate with other modules of the electronic device 600 via a bus 630. It should be understood that, although not shown in the figure, other hardware and / or software modules may be used in conjunction with the electronic device 600, including but not limited to: microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage platforms, etc.

[0077] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings here can usually be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0078] Example Analysis In order to verify the effectiveness of the method proposed in this invention, a simple power system and an IEEE 14-bus system are selected for illustration in this example analysis.

[0079] (1) Simple power system: small disturbance stability analysis + voltage transient stability simulation For the simple power system studied in step S3, the base capacity of the whole system is assumed to be 100MVA and the rated voltage is 230kV. Ignoring the ground admittance, the impedance of a single-circuit transmission line is 0.017+0.092j, and the initial value of the load impedance is 0.15+0.06j. Considering that the load regulation is a slow process, the integral constants are taken as For simplicity, it is still assumed that the system's constant power load accounts for 100%.

[0080] First, the small disturbance stability analysis of the system is carried out. The power flow calculation of the system shows that there are two initial solutions for the receiving node voltage. The high voltage solution is , the low voltage solution is Generally speaking, the power system will operate at the operating point where the high voltage solution is located, and the low voltage solution means that the system has voltage collapse. Substituting the two initial voltage solutions and their corresponding line current initial values ​​into equation (20) respectively, we can get two sets of eigenvalues ​​of the power system. The eigenvalue corresponding to the high voltage solution is It is an oscillation mode, which means that the voltage of the receiving node is stable under the high voltage solution modeling. The characteristics corresponding to the low voltage solution are two real eigenvalues, one positive and one negative, and the results are , which shows that the voltage of the receiving node is unstable under the low voltage solution, and it shows monotonic instability after being disturbed.

[0081] Secondly, the system is subjected to electromechanical transient simulation to observe the dynamic behavior of the voltage at the receiving node after the system is disturbed under the dynamic ZIP model. This example is intended to show the recovery process of the system load after the disturbance, so the initial value of the load impedance is adjusted to 0.2911+0.1168j, and the other parameters remain unchanged. The simulation interval is 0 to 100 seconds. At 2 seconds, a three-phase grounding fault occurs in the middle of a circuit, and the circuit is cut off after 5 cycles. The voltage change of the receiving node is as follows: Figure 6 As shown in the figure, the load equivalent impedance changes as follows Figure 7 As shown in the figure, the active and reactive power consumed by the load impedance is as follows Figure 8 shown. Figure 6 It shows that after the fault is removed, the system voltage slowly drops for a period of time and then enters the recovery stage; Figure 7 It shows that the load equivalent resistance first drops and then gradually recovers, while the load equivalent reactance first increases slowly and then gradually drops, reflecting the process of reactive power supporting voltage.

[0082] (2) IEEE 14-bus system for voltage collapse scenario simulation This example aims to simulate the voltage collapse scenario of the system using the dynamic ZIP load model. Based on the original standard system, the initial load is adjusted to twice the original example. The flow calculation is performed on this example, and the load equivalent resistance and equivalent reactance are initialized using the flow results. Fig. 9 The voltage distribution of the IEEE14 standard example system is given. Red indicates a high voltage, green indicates that the voltage is in the normal range, and blue indicates that the voltage is low. The power flow results show that the voltage near the power center is maintained at a high level, while the voltage at the load center far away from the power center is generally low, which indicates that a line break near the load center is very likely to cause voltage collapse.

[0083] The simulation interval is from 0 seconds to 150 seconds. At 0.2 seconds, a three-phase grounding fault occurs in the middle of the line between node 6 and node 13 and between node 9 and node 14. After 4 cycles, these two lines are cut off. The voltage changes of each node after simulation are as follows: Fig.10 As shown in the figure, the voltage trajectory did not show any non-convergence in calculation and no numerical oscillation problem occurred. In addition, the nodes near the load center (such as node 12, node 13 and node 14) all experienced voltage collapse, and the voltage continued to drop to a lower level with no signs of recovery.

[0084] In summary, the present invention provides an electromechanical transient simulation method and system for voltage stability of an electric power system, which uses resistance reactance as the state variable in the dynamic load model, avoids the static constant power characteristics of the previous load model, allows active and reactive loads to undergo step changes after being disturbed, has a wider range of applications, and is more in line with the dynamic response mechanism of the actual load. In addition, the small disturbance stability analysis algorithm and batch fault voltage transient stability simulation algorithm proposed on the basis of the dynamic load model proposed in the present invention cross-verify the static voltage stability of the electric power system from both theoretical and simulation levels, avoid the limitations of the traditional nose curve in judging stability based on the transmission power limit point, and reveal the connection between the static voltage stability of the system and the dynamic characteristics of the load. In summary, the method proposed in the present invention can be used to analyze the degree of system voltage stability, find out the weak load nodes of system voltage stability and the key links that restrict system voltage stability, and provide theoretical support for proposing countermeasures after voltage instability.

[0085] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0086] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0087] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed in the present invention can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0088] In the embodiments provided by the present invention, it should be understood that the disclosed devices / terminals and methods can be implemented in other ways. For example, the device / terminal embodiments described above are only schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0089] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0090] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0091] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium, etc. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electric carrier signals and telecommunication signals.

[0092] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0093] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate 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 1A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0094] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0095] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for simulating electromechanical transient state of voltage stability of power system, characterized in that: The following steps are involved: S1. Obtain data on transient changes in voltage, active power and reactive power of the bus where the load is located after the system is disturbed, and use a parameter identification algorithm to obtain the time constant for the load to recover to a steady state, the proportional coefficients related to the static active load and reactive load, and the proportional coefficients related to the reactive load include constant power proportion, constant current proportion and constant impedance proportion parameters; S2. Based on the parameters obtained in step S1, a conventional ZIP static load model is written, load equivalent resistance and equivalent reactance are introduced as state variables of the dynamic load model, and a dynamic ZIP load model is constructed using a proportional integral differential link and a limiting link to reflect the input-output relationship between active and reactive loads and equivalent impedances; S3. Determine the system equilibrium point according to the steady-state power flow calculation results of step S2, and linearize all dynamic equations of the entire network at the equilibrium point to obtain a state space model, calculate the eigenvalue of the state matrix, and judge the voltage stability of the bus where the load is located according to the positive and negative signs of the real parts of the relevant eigenvalues; S4. Perform dynamic time domain simulation on the adjusted system, impose N-1 or N-2 type line faults on the entire network, and simulate the voltage collapse scenario that may occur in the system.

2. The method for simulating the electromechanical transient state of voltage stability of a power system according to claim 1, characterized in that: Step S2 is specifically as follows: S201, introducing load equivalent resistance as a state variable, the rate of change of the equivalent resistance is proportional to the difference between the actual active power at the measurement point and the active power calculated by the ZIP static load model, indicating that when the active power taken is lower than the required active power, a greater active power can be obtained by reducing its own resistance; S202, introducing load equivalent reactance as a state variable, the change rate of the equivalent reactance is proportional to the difference between the reactive power calculated by the ZIP static load model and the actual reactive power at the measuring point, indicating that when the active power taken is lower than the required active power, a greater active power can be obtained by increasing its own resistance; S203. Add a network connection equation to describe the relationship between the voltage, current and power of the bus where the load is located.

3. The method for simulating the electromechanical transient state of voltage stability of a power system according to claim 2, characterized in that: The dynamic ZIP model is: in, It is the inverse of the active / reactive power recovery time constant; is the maximum / minimum value of the load equivalent resistance; is the maximum / minimum value of the load equivalent reactance; , and They are respectively the active power, reactive power and node voltage absorbed by the load in the steady state before the system is disturbed; , and They respectively represent the active power, reactive power and node voltage absorbed by the load after being disturbed; and Respectively represent the equivalent resistance and equivalent reactance of the load; coefficient a , b and c Respectively represent the proportion of constant impedance, constant current and constant power in the total load, subscript " p "and" q " represents the corresponding active and reactive power situations.

4. The method for simulating electromechanical transient state of voltage stability of electric power system according to claim 3, characterized in that: The interface equation between the dynamic load model and the network is as follows: in, represents the real / imaginary part of the receiving node voltage, Represents the real / imaginary part of the current flowing through the transmission line; and They represent the equivalent resistance and equivalent reactance of the load respectively; , and They respectively represent the active power, reactive power and node voltage absorbed by the load after being disturbed.

5. The method for electromechanical transient simulation of power system voltage stability according to claim 1, characterized in that: In step S3, the voltage stability of the bus where the load is located is determined according to the positive and negative signs of the real parts of the relevant eigenvalues, the eigenvalues ​​of the coefficient matrix are calculated, and the relationship between the system eigenvalues ​​and the voltage stability of the power system is observed. The coefficient matrix is ​​specifically: in, and is the equivalent resistance of the load and equivalent reactance The differential of Represents the receiving node voltage The real / imaginary part of the initial value, Indicates the current flowing through the transmission line The real / imaginary part of the initial value; It represents the initial value of equivalent resistance and equivalent reactance before the load is disturbed. Indicates the resistance and reactance of the transmission line; and They respectively represent the active power and reactive power absorbed by the load after being disturbed.

6. The method for simulating electromechanical transient state of voltage stability of electric power system according to claim 5, characterized in that: The steady-state value of the line current is: in, is the power supply voltage, is the line impedance amplitude, is the load equivalent impedance amplitude, is the line impedance power factor angle, is the load impedance power factor angle.

7. The method for simulating electromechanical transient state of voltage stability of electric power system according to claim 5, characterized in that: The steady-state value of the receiving terminal voltage is: in, is the power supply voltage, is the line impedance amplitude, is the load equivalent impedance amplitude, is the line impedance power factor angle, is the load impedance power factor angle.

8. The method for simulating electromechanical transient state of voltage stability of electric power system according to claim 1, characterized in that: Step S4 is specifically as follows: S401. Under the premise that the steady-state solution of the power flow calculation is used as the initial solution, the electromechanical transient simulation is performed on the whole system, the N-1 or N-2 type fault event set of the key line is defined, and batch operations are performed according to the expected fault event set, and the relevant transient simulation results are saved; S402, collecting node voltage change data of all buses in the entire network in the simulation results, evaluating the system's dynamic response capability for voltage recovery after a fault, and determining whether the voltage collapses in the fault scenario.

9. The method for simulating electromechanical transient state of voltage stability of electric power system according to claim 8, characterized in that: Record the changes in voltage near the load center node when it is subject to large disturbances, determine the system voltage stability, screen the load nodes far away from the power center, list the lines connected to the load nodes at the head or end as lines to be disconnected, and simulate various possible line disconnection situations to form a line disconnection fault set.

10. An electromechanical transient simulation system for voltage stability of a power system, characterized in that: include: The data module obtains the data of transient changes in voltage, active power and reactive power of the bus where the load is located after the system is disturbed, and uses the parameter identification algorithm to obtain the time constant of the load recovery from the disturbance to the steady state, the proportional coefficient related to the static active load and the reactive load. The proportional coefficient related to the reactive load includes constant power proportion, constant current proportion and constant impedance proportion parameters; The construction module writes the conventional ZIP static load model based on the parameter list, introduces the load equivalent resistance and equivalent reactance as the state variables of the dynamic load model, and uses the proportional integral differential link and the limit link to construct the dynamic ZIP load model to reflect the input-output relationship between the active and reactive loads and the equivalent impedance; The calculation module determines the system equilibrium point based on the steady-state power flow calculation results, linearizes all dynamic equations of the entire network at the equilibrium point to obtain a state space model, calculates the eigenvalues ​​of the state matrix, and determines the voltage stability of the bus where the load is located based on the positive and negative signs of the real parts of the relevant eigenvalues; The simulation module performs dynamic time-domain simulation on the adjusted system, imposes N-1 or N-2 type line faults on the entire network, and simulates the voltage collapse scenario that may occur in the system.

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