New energy power system stability evaluation method based on transient energy function and related device

Abstract

The invention provides a new energy power system stability evaluation method based on a transient energy function and a related device, and relates to the technical field of power systems. The method comprises the steps of dividing a new energy electric field, a synchronous generator and a load node type and establishing a dynamic model; constructing a kinetic energy function based on the block diagonalization inertia matrix, constructing a potential energy function by adopting trapezoidal integral, and synthesizing a total transient energy function; applying a fault and simulating to a clearing moment, and calculating the total energy of the system; taking the fault clearing state as a starting point, searching a nearest unstable equilibrium point through a gradient rising method, and calculating critical potential energy; and comparing the total energy with the critical potential energy to judge the transient stability. New energy and a synchronous machine are dynamically and uniformly incorporated into an energy framework for the first time, and the model accuracy is improved; through efficient energy modeling and balance point searching, rapid quantitative evaluation of the transient stability of the high-proportion new energy power system is achieved, and the method is suitable for online safety early warning and prevention control and has important engineering application value.

Description

Technical Field

[0001] This invention relates to the field of power system technology, specifically a method and related apparatus for stability assessment of new energy power systems based on transient energy functions. Background Technology

[0002] With the continuous advancement of new power system construction, renewable energy sources, represented by wind power, are being integrated into traditional synchronous machine-dominated power systems in large quantities. This leads to a decrease in system inertia and increased complexity in dynamic response. Traditional transient stability analysis methods based on time-domain simulation face problems such as low computational efficiency and difficulty in supporting real-time decision-making. While existing methods such as the continuous energy function method can improve analysis speed, their core relies on accurate transient energy function modeling. However, most current transient energy function models are still limited to pure synchronous generator systems, failing to effectively consider the dynamic behavior of converter-type power sources such as new energy sources. They neglect the coupling effects of new energy converter control and equivalent inertia, the nonlinear interaction between the new energy electric field and the synchronous machine, and the impact of equilibrium point migration on the potential energy structure after new energy integration. Currently, there is a lack of a unified energy framework that integrates the modeling of new energy sources, synchronous machines, loads, and AVR excitation systems. Furthermore, after obtaining the energy function, how to efficiently solve for unstable equilibrium points and accurately determine whether the trajectory has left the stable region is also a challenge in engineering applications. Therefore, it is urgent to propose a unified transient energy function modeling method that considers the dynamic characteristics of new energy sources, and to design a complete transient stability assessment process based on this energy function, so as to solve the technical bottleneck of power system security assessment under the background of high proportion of new energy access.

[0003] Based on this, this invention addresses the problem of energy function distortion and stability misjudgment caused by the current technology's failure to consider the dynamic impact of new energy sources. It proposes a method for constructing transient energy functions and assessing the stability of new energy power systems based on energy functions. By establishing a unified energy function model including new energy sources, synchronous generators, automatic voltage regulators, network power flow, and loads, and combining the path integral method with the direct energy function stability criterion, this method enables rapid and quantitative assessment of the transient stability of power systems with new energy power plant integration. This method integrates the dynamic characteristics of new energy units, achieving rapid and accurate stability assessment of complex power grids under large disturbances. It can be used for online safety early warning, critical clearance time calculation, and prevention and control strategy formulation, effectively addressing the challenges brought by high-proportion renewable energy integration, and possesses good theoretical value and industrial application prospects. Summary of the Invention

[0004] To address the aforementioned deficiencies or improvement needs of existing technologies, and to resolve the transient stability issues in power systems caused by the high proportion of renewable energy integration, this invention provides a method and related apparatus for evaluating the stability of renewable energy power systems based on transient energy functions. This method solves the problem of inaccurate traditional energy function modeling under renewable energy integration, and has the advantages of high computational efficiency and interpretable results. It is suitable for online safety early warning and prevention control, and has significant application prospects in practical engineering.

[0005] To achieve the above objectives, according to one aspect of the present invention, a method for stability assessment of new energy power systems based on transient energy functions is provided, comprising the following:

[0006] A stability assessment method for new energy power systems based on transient energy functions includes the following steps:

[0007] Step 1: Classify system node types

[0008] The power system is divided into new energy power plant connection nodes, synchronous generator connection nodes, and load nodes, and numbered accordingly. The node types are then output.

[0009] Step 2: Establish a dynamic node model

[0010] Based on the node types output in step 1, establish a dynamic model for each node;

[0011] Step 3: Define state variables and construct kinetic energy function

[0012] Based on the dynamic model output in step 2, a set of state variables is defined, and the system kinetic energy function is constructed using a block-diagonalized inertia matrix.

[0013] Step 4: Construct the potential energy function

[0014] By integrating each energy term using the trapezoidal rule approximation path, a numerically approximate potential energy function is output.

[0015] Step 5: Synthesize the total transient energy function

[0016] Based on the kinetic energy function output in step 3 and the potential energy function output in step 4, the total transient energy function is constructed.

[0017] Step 6: Obtain energy at the time of fault clearing

[0018] Based on the total energy function from step 5, a fault is applied and simulation is performed up to the fault clearance time. The system state variables at that time are obtained and substituted into the total energy function to calculate the total energy at the fault clearance time. total ;

[0019] Step 7: Search for the nearest unstable equilibrium point and calculate the critical potential energy.

[0020] Starting from the fault clearing state output in step 6, with the unit angular velocity fixed at 0, the state variables are iteratively updated using the gradient ascent method. Combined with power flow calculations to correct the voltage and phase angle, the nearest unstable equilibrium point is searched, and its critical potential energy is calculated. ;

[0021] Step 8: Determine the transient stability of the system

[0022] Based on the total energy output in step 6 total The critical potential energy output in step 7 Determine whether the system is transiently stable.

[0023] Furthermore, in step 2, dynamic models for each node are established, specifically including: the new energy node adopts an equivalent rotor motion equation combined with the power flow equation; the synchronous generator node adopts an excitation model containing transient electromotive force and AVR; and the load node adopts a constant power flow model.

[0024] Furthermore, the set of state variables in step 3 includes the angular velocities of the doubly fed wind farm and the synchronous generator.

[0025] Furthermore, the energy terms in step 4 include the reactive power partial derivative with respect to voltage and the active power partial derivative with respect to phase angle.

[0026] Furthermore, step 7 searches for the nearest unstable equilibrium point and calculates the critical potential energy, specifically including:

[0027] Step 7.1: Based on the system state at the time of fault clearing. As a starting point for the search;

[0028] Step 7.2: Fix the angular velocity of all units. =0 and the dynamic rate of change is zero, constructing an adjustable state variable vector. ;

[0029] Step 7.3: Maximize the potential energy function To achieve the goal, the gradient ascent method is used for iterative updates. ;

[0030] Step 7.4: After each iteration, correct the voltage and phase angle through power flow calculation to ensure that network constraints are met;

[0031] Step 7.5: Stop iterating when the gradient norm is less than a preset threshold, and obtain candidate points. ;

[0032] Step 7.6, Calculation The Hessian matrix is ​​calculated, and the presence of negative eigenvalues ​​is determined. If negative eigenvalues ​​are found, the point is identified as an unstable equilibrium point, and its potential energy is used as a threshold criterion, i.e., the critical potential energy. .

[0033] Furthermore, step 8, determining the transient stability of the system, specifically includes: comparing the total energy output in step 6. total The critical potential energy output in step 7 :like total < If the condition is met, the system is determined to be transiently stable; otherwise, it is determined to be unstable.

[0034] A stability assessment device for a new energy power system based on transient energy functions, comprising:

[0035] The system node type classification module is used to divide the power system into new energy power field connection nodes, synchronous generator connection nodes and load nodes and number them, and output the node type.

[0036] The node dynamic model building module is used to build dynamic models for each node based on its type.

[0037] The kinetic energy function construction module is used to define a set of state variables based on a dynamic model and construct the system's kinetic energy function using a block-diagonalized inertia matrix.

[0038] The potential energy function construction module is used to integrate each energy term through the trapezoidal rule approximation path and output a numerically approximate potential energy function.

[0039] The total transient energy function synthesis module is used to construct the total transient energy function from the kinetic and potential energy functions of the base output.

[0040] The fault clearance time energy acquisition module is used to apply a fault and simulate up to the clearance time based on the total energy function, obtain the system state variables at that time, and substitute them into the total energy function to calculate the total energy at the fault clearance time. total ;

[0041] The critical potential energy calculation module is used to start from the state at the fault clearance moment, fix the unit angular velocity at 0, iterate and update the state variables using the gradient ascent method, combine power flow calculation to correct the voltage and phase angle, search for the nearest unstable equilibrium point, and calculate its critical potential energy. ;

[0042] The system transient stability determination module is used to determine the stability based on total energy. total and critical potential energy Determine whether the system is transiently stable.

[0043] Furthermore, the critical potential energy calculation module is specifically used for:

[0044] Step 7.1: Based on the system state at the time of fault clearing. As a starting point for the search;

[0045] Step 7.2: Fix the angular velocity of all units. =0 and the dynamic rate of change is zero, constructing an adjustable state variable vector. ;

[0046] Step 7.3: Maximize the potential energy function To achieve the goal, the gradient ascent method is used for iterative updates. ;

[0047] Step 7.4: After each iteration, correct the voltage and phase angle through power flow calculation to ensure that network constraints are met;

[0048] Step 7.5: Stop iterating when the gradient norm is less than a preset threshold, and obtain candidate points. ;

[0049] Step 7.6, Calculation The Hessian matrix is ​​calculated, and the presence of negative eigenvalues ​​is determined. If negative eigenvalues ​​are found, the point is identified as an unstable equilibrium point, and its potential energy is used as a threshold criterion, i.e., the critical potential energy. .

[0050] A stability assessment system for a new energy power system based on transient energy functions includes: a computer-readable storage medium and a processor;

[0051] The computer-readable storage medium is used to store executable instructions;

[0052] The processor is used to read executable instructions stored in the computer-readable storage medium and execute the new energy power system stability assessment method based on transient energy function.

[0053] A non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the aforementioned method for evaluating the stability of a new energy power system based on a transient energy function.

[0054] This invention addresses the challenges posed by large-scale renewable energy integration to the transient stability analysis and assessment of power systems. It proposes a transient energy function method for evaluating the stability of novel power systems, and for the first time integrates doubly-fed induction generator (DFIG) wind farms, synchronous generators, AVRs, networks, and loads into a unified energy function framework. Simultaneously, it employs the trapezoidal rule to approximate the path integral, significantly improving the accuracy of potential energy calculation. Furthermore, by comparing the total system energy at the fault clearing moment with the critical potential energy of the nearest unstable equilibrium point, it achieves rapid determination of system transient stability, facilitating engineering applications and decision-making. Moreover, it has good scalability and can be extended to novel power system scenarios including photovoltaics, energy storage, and HVDC. In summary, this method has strong engineering applicability and can provide an important reference for transient stability analysis of power grids with large-scale renewable energy integration. Attached Figure Description

[0055] Figure 1 This is a flowchart of the stability assessment method for new energy power systems based on transient energy functions, as described in this invention. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] The following embodiments illustrate a method for evaluating the stability of a new energy power system based on a transient energy function, which includes the following steps:

[0058] Step 1: Divide the power system into new energy farm connection nodes, synchronous generator connection nodes, and load nodes. Taking a doubly-fed induction generator (DFIG) wind farm as an example, there are P wind farm nodes, numbered i=1,2,...,p; n+1 synchronous generator nodes, numbered i=p+1,...,p+n+1; and m load nodes, all of constant power load type, numbered i=p+n+2,...,p+n+m+1. Therefore, the total number of nodes is N=p+n+m+1. The voltage phase angle of all nodes is... The voltage amplitude is The elements of the admittance matrix are .

[0059] Step 2: Establish dynamic models for various types of nodes, including new energy nodes (taking doubly fed wind turbines as an example) using equivalent rotor motion equations combined with external power flow equations, synchronous generator nodes using a first-order excitation model including d-axis and q-axis transient electromotive forces and automatic voltage regulators (AVR), and load nodes using a constant power flow model.

[0060] First, a dynamic model of a doubly-fed induction generator (DFIG) wind farm is established (nodes i=1,2,...,p), and its electromechanical transient process is described using the equivalent rotor motion equation:

[0061] (1)

[0062] In the formula, Let be the relative speed deviation of the i-th unit's rotor; Let be the rotor angle of the i-th unit; The equivalent inertial constant of a doubly-fed wind farm; is the damping coefficient.

[0063] At the same time, electromagnetic power Originating from external current constraints:

[0064] (2)

[0065] (3)

[0066] in, and The equivalent internal potential of DFIG and its phase angle are determined by the control system.

[0067] Then, a synchronous generator model (nodes i=p+1, ..., p+n+1) is established, using a two-axis model with a first-order excitation system:

[0068] (4)

[0069] In the formula, and These are the transient electromotive forces along the d-axis and q-axis; and Synchronous reactance for the d-axis and q-axis; and For d-axis and q-axis transient reactance; and The d-axis and q-axis open-circuit transient time constants; This is the excitation voltage; The time constant of the automatic voltage regulator; For AVR feedback gain; This is the AVR constant.

[0070] The electromagnetic power model is as follows:

[0071] (5)

[0072] Finally, a load node model is established (nodes i = p + n + 2, ..., p + n + m + 1), and the constant power model satisfies the power flow equations:

[0073] (6)

[0074] (7)

[0075] Step 3: Define the set of system state variables and construct the system kinetic energy function.

[0076] First, define the combined angular velocity vector. The angular velocities of the doubly-fed wind farm and the synchronous generator can be expressed as follows:

[0077] (8)

[0078] (9)

[0079] Let the total inertia matrix be in block diagonal form:

[0080] (10)

[0081] In the formula, The inertial matrix of the doubly fed wind farm is a block-diagonalized matrix. This is the inertial matrix of the synchronous machine.

[0082] Therefore, the kinetic energy function of the system can be expressed as:

[0083] (11)

[0084] in, , which represents the relative rotational speed of all power generation units.

[0085] Step 4: Construct the potential energy function The path integral is approximated using the trapezoidal rule. The potential energy of a power system originates from energy storage, the magnetic field energy inside generators, and the action of controllers, and can be expressed as a path integral:

[0086] (12)

[0087] In the formula, denoted as , where z is the system potential energy; z is the comprehensive state variable.

[0088] Due to the difficulty of analytical calculation, the trapezoidal rule is used for approximate calculation of the integral of any function f(x) over the interval [a,b]:

[0089] (13)

[0090] Therefore, applying this to various energy terms (such as the reactive power partial derivative with respect to voltage, the active power partial derivative with respect to phase angle, etc.), we obtain a numerically approximate potential energy function:

[0091] (14)

[0092] in, It can be obtained through the trend Jacobian matrix. The transient electromotive force vector; This is the state combination vector.

[0093] Step 5: Construct the total transient energy function based on the system's kinetic energy function and potential energy function.

[0094] (15)

[0095] in, Let be the total transient energy function.

[0096] Step 6: Obtain the system state at the time of fault clearing and calculate the current total energy.

[0097] First, obtain the status at the time of fault clearing. Record all state variables:

[0098] (16)

[0099] Then, substitute the values ​​into the energy function to calculate the current total energy. total :

[0100] (17)

[0101] Step 7: Search for the nearest unstable equilibrium point in the corresponding failure mode and calculate its potential energy value as the critical potential energy. This invention uses the hill-climbing method as an example to search for the nearest imbalance point, but other methods can also be used to search for imbalance points.

[0102] Step 7.1 The system state at the time of fault clearing. As a starting point for the search;

[0103] Step 7.2 Fix the angular velocity of all units =0 and the dynamic rate of change is zero, constructing an adjustable state variable vector. ;

[0104] Step 7.3 to maximize the potential energy function To achieve the goal, the gradient ascent method is used for iterative updates. ;

[0105] Step 7.4 After each iteration, the voltage and phase angle are corrected by power flow calculation to ensure that network constraints are met;

[0106] Step 7.5 Stop iterating when the gradient norm is less than a preset threshold, and obtain candidate points. ;

[0107] Step 7.6 Calculation The Hessian matrix is ​​calculated, and the presence of negative eigenvalues ​​is determined. If negative eigenvalues ​​are found, the point is identified as an unstable equilibrium point, and its potential energy is used as a threshold criterion, i.e., the critical potential energy. .

[0108] Step 8: Compare total energy total With critical potential energy ;like total Less than If the condition is met, the system is determined to be transiently stable; otherwise, it is determined to be unstable.

[0109] Step 9: End.

[0110] The present invention proposes a method for stability assessment of new energy power systems based on transient energy functions. By establishing a unified energy function model considering doubly-fed wind farms, synchronous machines, AVRs, networks, and loads, it extends energy function analysis to new energy sources. Simultaneously, it improves the accuracy of potential energy calculation by approximating path integrals using the trapezoidal rule. Furthermore, after synthesizing the total transient energy function, it achieves rapid determination of system transient stability by comparing the total system energy at the fault clearing moment with the critical potential energy of the nearest unstable equilibrium point. This invention solves the problem of inaccurate traditional energy function modeling under new energy integration, and has the advantages of high computational efficiency and interpretable results, making it suitable for online safety early warning and prevention control.

[0111] This invention also provides a new energy power system stability assessment device based on transient energy function, comprising:

[0112] The system node type classification module is used to divide the power system into new energy power field connection nodes, synchronous generator connection nodes and load nodes and number them, and output the node type.

[0113] The node dynamic model building module is used to build dynamic models for each node based on its type.

[0114] The kinetic energy function construction module is used to define a set of state variables based on a dynamic model and construct the system's kinetic energy function using a block-diagonalized inertia matrix.

[0115] The potential energy function construction module is used to integrate each energy term through the trapezoidal rule approximation path and output a numerically approximate potential energy function.

[0116] The total transient energy function synthesis module is used to construct the total transient energy function from the kinetic and potential energy functions of the base output.

[0117] The fault clearance time energy acquisition module is used to apply a fault and simulate up to the clearance time based on the total energy function, obtain the system state variables at that time, and substitute them into the total energy function to calculate the total energy at the fault clearance time. total ;

[0118] The critical potential energy calculation module is used to start from the state at the fault clearance moment, fix the unit angular velocity at 0, iterate and update the state variables using the gradient ascent method, combine power flow calculation to correct the voltage and phase angle, search for the nearest unstable equilibrium point, and calculate its critical potential energy. ;

[0119] The system transient stability determination module is used to determine the stability based on total energy. total With critical potential energy Determine whether the system is transiently stable.

[0120] Another embodiment of the present invention provides a stability assessment system for a new energy power system based on transient energy functions, comprising: a computer-readable storage medium and a processor;

[0121] The computer-readable storage medium is used to store executable instructions;

[0122] The processor is used to read executable instructions stored in the computer-readable storage medium and execute the new energy power system stability assessment method based on transient energy function.

[0123] Another embodiment of the present invention provides a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the aforementioned method for evaluating the stability of a new energy power system based on a transient energy function.

[0124] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0125] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0126] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0127] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0128] This invention achieves efficient and accurate assessment of transient stability in new energy power systems through the following improvements:

[0129] 1. Unified Energy Framework Modeling: For the first time, new energy power plants (such as doubly fed wind farms), synchronous generators, AVR excitation systems, load and network dynamics are uniformly incorporated into the transient energy function framework, which solves the problem of energy function distortion caused by neglecting the dynamics of new energy in traditional models and improves the evaluation accuracy in scenarios with a high proportion of new energy access.

[0130] 2. High-precision energy function construction: The kinetic energy function is constructed by using a block-diagonalized inertia matrix, and the potential energy function is calculated by approximating the path integral using the trapezoidal rule. This significantly improves the numerical calculation accuracy of the energy term and overcomes the shortcomings of existing continuous energy function methods in modeling nonlinear interactions.

[0131] 3. Rapid stability determination: By combining the gradient ascent method with power flow calculation correction, the system efficiently searches for the nearest unstable equilibrium point and calculates the critical potential energy. Based on the comparison between the total energy and the critical potential energy at the fault clearing moment, the system achieves rapid stability determination. The computational efficiency is better than the traditional time-domain simulation method, and it supports online safety early warning and real-time decision-making.

[0132] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A method for stability assessment of new energy power system based on transient energy function, characterized in that, The method comprises the following steps: Step 1: dividing system node types Divide the power system into new energy power plant connected nodes, synchronous generator connected nodes and load nodes and number them, and output node types; Step 2: establishing a node dynamic model Based on the node types output in step 1, a dynamic model of each node is established; Step 3: defining state variables and constructing kinetic energy function Based on the dynamic model output in step 2, a set of state variables is defined, and a system kinetic energy function is constructed by using block diagonalization of the inertia matrix; Step 4: constructing potential energy function Integrate each energy term by using the trapezoidal rule to approximate the path, and output the numerically approximated potential energy function; Step 5: synthesizing total transient energy function Based on the kinetic energy function output in step 3 and the potential energy function output in step 4, a total transient energy function is constructed; Step 6: obtaining energy at fault clearing time Based on the total energy function of step 5, the fault is applied and simulated to the clearing time, the system state variables at the clearing time are obtained, and the total energy at the clearing time is calculated by substituting the total energy function total ; Step 7: searching for the nearest unstable equilibrium point and calculating critical potential energy Taking the state of the fault clearing time point output by step 6 as the starting point, fixing the unit angular velocity as 0, updating the state variable through the gradient ascent method, correcting the voltage and phase angle by combining the power flow calculation, searching for the nearest unstable equilibrium point, and calculating the critical potential energy thereof ; Step 8: determining system transient stability Total energy based on step 6 output total Critical potential energy with step 7 output Decides whether the system transient is stable.

2. The method of claim 1, wherein the method is characterized by: In step 2, the dynamic model of each node is established, which specifically includes: the equivalent rotor motion equation combined with the power flow equation for new energy nodes, the excitation model with transient electromotive force and AVR for synchronous generator nodes, and the constant power flow model for load nodes.

3. The method of claim 1, wherein the method further comprises: The set of state variables in step 3 includes the angular velocity of the doubly-fed wind power plant and the synchronous generator.

4. The method of claim 1, wherein the method further comprises: Each energy term in step 4 includes the partial derivative of reactive power with respect to voltage and the partial derivative of active power with respect to phase angle.

5. The method of claim 1, wherein the method further comprises: Step 7 searches for the nearest unstable equilibrium point and calculates the critical potential energy, which specifically includes: Step 7.1, system state at the time of the fault clearance as a search starting point; Step 7.2, fix the angular velocity of all the units = 0 and the dynamic change rate is zero, construct the adjustable state variable vector ; Step 7.3, Maximizing the potential function The gradient ascent method is used to iteratively update ; Step 7.4, after each iteration, the voltage and phase angle are corrected through power flow calculation to ensure that the network constraints are met; Step 7.

5. Stop iteration when the gradient norm is less than a preset threshold, resulting in a candidate point ; Step 7.6, calculation the Hessian matrix of the potential energy function and determine whether it has a negative eigenvalue, if so, it is identified as an unstable equilibrium point and its potential energy is taken as the criterion threshold, i.e. the critical potential energy .

6. The method of claim 1, wherein the method further comprises: Step 8 determining system transient stability specifically comprises: comparing the total energy outputted by step 6 total with the critical potential energy outputted by step 7 : if total < , determining system transient stability; otherwise, determining instability.

7. A transient energy function based new energy power system stability evaluation device, characterized in that, It comprises: A system node type division module is used to divide the power system into new energy power plant connected nodes, synchronous generator connected nodes and load nodes and number them, and output node types; A node dynamic model establishment module is used to establish a dynamic model of each node based on the node types; A kinetic energy function construction module is used to define a set of state variables based on the dynamic model, and construct a system kinetic energy function by using block diagonalization of the inertia matrix; A potential energy function construction module is used to integrate each energy term by using the trapezoidal rule to approximate the path, and output the numerically approximated potential energy function; A total transient energy function synthesis module is used to construct a total transient energy function based on the kinetic energy function and the potential energy function output; The fault clearing time energy acquisition module is configured to acquire the system state variable at the fault clearing time based on the total energy function, apply the fault and simulate to the clearing time, and calculate the total energy at the fault clearing time by substituting the system state variable into the total energy function total ; The critical potential energy calculation module is used to start from the state at the fault clearance moment, fix the unit angular velocity at 0, iterate and update the state variables using the gradient ascent method, combine power flow calculation to correct voltage and phase angle, search for the nearest unstable equilibrium point, and calculate its critical potential energy. ; a system transient stability determination module for determining whether the system is transiently stable based on the total energy total and the critical potential energy determining whether the system is transiently stable.

8. The transient energy function based new energy power system stability evaluation device of claim 1, wherein: The critical potential energy calculation module is specifically used for: Step 7.1, system state at the time of the fault clearance as a search starting point; Step 7.2, fix the angular velocity of all the units = 0 and the dynamic change rate is zero, construct the adjustable state variable vector ; Step 7.3, Maximizing the potential function The gradient ascent method is used to iteratively update ; Step 7.4, after each iteration, the voltage and phase angle are corrected through power flow calculation to ensure that the network constraints are met; Step 7.

5. Stop iteration when the gradient norm is less than a preset threshold, resulting in a candidate point ; Step 7.6, calculation the Hessian matrix of the potential energy function and determine whether it has a negative eigenvalue, if so, the unstable equilibrium point is identified and its potential energy is taken as the criterion threshold, i.e. the critical potential energy .

9. A transient energy function based new energy power system stability assessment system, comprising: A computer readable storage medium and a processor; The computer readable storage medium is used to store executable instructions; The processor is used to read the executable instructions stored in the computer readable storage medium, and execute the transient energy function based new energy power system stability evaluation method in any one of claims 1-6.

10. A non-transitory computer readable storage medium having stored thereon a computer program, which, when executed by a processor, implements the transient energy function based new energy power system stability evaluation method in any one of claims 1-6.

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