Transient power impact amount and transient stability limit estimation method and system

Abstract

The invention relates to the technical field of transient power angle stability of a power system, in particular to a transient power impact quantity and transient stability limit estimation method and system. Giving model parameters, and establishing a thermal power sending model; calculating the internal potential and the power angle of the generator according to the tail end power of the generator branch and the line sending end node voltage; based on the generator rotor motion equation, calculating the unit oscillation frequency after the fault; and calculating the peak value of the power fluctuation of the tie line after the fault occurs, and establishing an estimation formula of the transient stability limit in combination with the static stability limit and the transient power impact after the fault occurs. According to the method, by accurately calculating the transient power impact quantity and the transient stability limit, more accurate data support is provided, and engineers are helped to better evaluate the stability condition and potential risks of the power grid. The rapid estimation method also supports flexible adjustment of the power grid under different operation conditions and fault conditions, facilitates optimization of configuration and management of power resources, and ensures continuity and efficiency of power supply.

Description

Technical Field

[0001] The present invention relates to the technical field of transient power angle stability of electric power systems, and in particular to a method and system for estimating transient power impact and transient stability limit. Background Art

[0002] The transient stability transmission power limit of the power system is an important basis for evaluating the safety and stability level of the power grid, and can provide reliable information for the preventive control and dispatching operation of the power system. The transient stability transmission power limit includes the removal time limit, energy limit and section power limit. In the transient stability analysis and safety control analysis of the power system, it is usually necessary to calculate this critical parameter. However, since the critical fault removal time and energy limit are difficult for dispatchers to control, and the power of the section can be controlled within the limit value by arranging the operation mode, the power limit of the section is an important basis for arranging the operation mode of the power system and grasping the transient stability capability of the system. At present, the methods for obtaining the transient stability transmission power limit of the tie line mainly include the time domain simulation method and the direct method, but the two methods cannot take into account both the calculation accuracy and calculation efficiency. In order to improve the calculation efficiency of the transient stability limit in actual engineering applications, the transient power impact during the fault period can be introduced to estimate the transient stability limit in combination with the power supply relationship between the static stability limit after the accident and the transient stability transmission power limit.

[0003] The present invention takes the thermal power transmission system as the research object, considers the static stability limit after the accident and the generator power angle oscillation frequency during the fault, derives the transient power impact formula of the power angle first swing during the fault, and further establishes the transient stability limit estimation formula considering the static stability limit after the accident and the transient power impact. The transient stability limits under different initial power modes are compared, and the results verify the adaptability of the proposed transient stability limit estimation formula. Summary of the invention

[0004] In view of the above problems existing in the prior art, the present invention is proposed.

[0005] Therefore, the present invention provides a method for estimating transient power impact and transient stability limit, which can solve the problems of low computational efficiency and difficulty in balancing accuracy and efficiency in traditional power system stability analysis, and the traditional method cannot fully evaluate the impact of complex faults on system stability, especially in predicting transient dynamics and power impacts during faults.

[0006] To solve the above technical problems, the present invention provides the following technical solutions, a method for estimating transient power impact and transient stability limit, comprising: given model parameters, establishing a thermal power delivery model; calculating the internal potential and power angle of the generator through the power at the end of the generator branch and the voltage at the node at the line sending end; calculating the oscillation frequency of the unit after a fault based on the generator rotor motion equation; calculating the peak value of the power fluctuation of the interconnection line after the fault occurs, and establishing an estimation formula for the transient stability limit in combination with the static stability limit and the transient power impact after the fault.

[0007] As a preferred solution of the method for estimating transient power impact and transient stability limit described in the present invention, wherein: the establishment of thermal power transmission model includes thermal power generation modeling and transmission system modeling;

[0008] The thermal power generation modeling includes setting the generator terminal voltage, power, generator transient reactance and transmission equipment reactance parameters;

[0009] The power transmission equipment includes a transformer and a power transmission line;

[0010] The transmission system modeling includes the modeling of transmission lines, transformers, nodes and buses.

[0011] As a preferred solution of the transient power impact and transient stability limit estimation method described in the present invention, the calculation of the internal potential and power angle of the generator includes obtaining the internal potential and power angle of the generator according to the power at the end of the generator branch and the voltage at the node at the line sending end, and the formula is expressed as follows:

[0012] δ G =arcsin(P e *X Σ / E′ q U G )

[0013]

[0014] Among them, δ G is the generator terminal voltage angle, arcsin(·) is the inverse sine function, P e is the electromagnetic power at the generator end, X Σ is the equivalent reactance of the transformer and line between the generator and the system, E' q is the potential inside the generator, U G is the generator terminal voltage, is the reactive power at the generator end, E s is the system side voltage, cos(·) is the cosine function, ΔU G is the longitudinal component of voltage, δU G is the voltage transverse component, X d is the direct-axis synchronous reactance of the generator, δ qis the generator power angle, X' d is the transient reactance of the generator.

[0015] As a preferred solution of the method for estimating transient power impact and transient stability limit described in the present invention, the generator rotor motion equation is expressed as follows:

[0016]

[0017] Where, f is the unit oscillation frequency, ω 0 is the rated speed, T j is the generator inertia time constant, is the power angle δ 0 The derivative of electromagnetic power with respect to power angle.

[0018] As a preferred solution of the method for estimating transient power impact and transient stability limit described in the present invention, the calculation of the unit oscillation frequency after the fault includes calculating the unit oscillation frequency after the tie line fault based on the generator rotor motion equation, and the formula is expressed as:

[0019]

[0020] Among them, K s is the synchronous torque coefficient.

[0021] As a preferred solution of the transient power impact and transient stability limit estimation method described in the present invention, wherein: the peak value of the interconnection line power fluctuation after the fault occurs is calculated, including the square wave response of the second-order linear system, and the transient power impact formula is expressed as follows:

[0022] D P =ΔP·τ·2πf

[0023] Among them, D P is the transient power impact, τ is the equivalent time of power loss, and ΔP is the peak power fluctuation after the fault.

[0024] As a preferred solution of the method for estimating a transient power impact and a transient stability limit described in the present invention, the estimation formula for establishing the transient stability limit includes combining the post-fault static stability limit and the transient power impact to establish a transient stability limit estimation formula.

[0025]

[0026] Among them, P max is the static stability limit after fault, X Σ2 is the sum of the equivalent reactance of the transmission line and transformer after the fault, P st is the transient stability limit after a fault.

[0027] Another object of the present invention is to provide a transient power impact and transient stability limit estimation system to improve the defects of traditional power system stability analysis, especially to improve the efficiency and accuracy of transient stability limit estimation of a single-machine infinite system when facing a power grid failure. In conventional methods, it takes a long time to process complex dynamics and large amounts of data, which is an obvious shortcoming for power system operation and maintenance that requires rapid response. The present invention introduces a rapid estimation method that allows power system engineers to obtain key system stability indicators in a short period of time, which is crucial for timely adjustment of power grid operations and prevention of potential large-scale failures. The present invention utilizes optimized mathematical models and algorithms to simplify the calculation process, thereby significantly improving the calculation speed without sacrificing accuracy, and can meet the application needs of power systems in real-time environments.

[0028] As a preferred solution of a transient power impact and transient stability limit estimation system described in the present invention, it includes: a model building module, a potential and power angle calculation module, an oscillation frequency calculation module and a stability limit estimation module;

[0029] The model building module builds a thermal power transmission model, including thermal power generation modeling, transmission system modeling and system side modeling;

[0030] The potential and power angle calculation module calculates the internal potential and power angle of the generator through the power at the end of the generator branch and the voltage at the node at the line sending end, providing key data for stability analysis;

[0031] The oscillation frequency calculation module calculates the oscillation frequency of the unit after a fault based on the generator rotor motion equation and analyzes the response speed and stability of the system;

[0032] The stability limit estimation module combines the post-fault static stability limit and the calculated transient power impact to derive an estimation formula for the maximum stable power level that the system can achieve after a specific fault.

[0033] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and is characterized in that when the processor executes the computer program, the steps of a method described in any one of the transient power impact quantity and transient stability limit estimation methods are implemented.

[0034] A computer-readable storage medium having a computer program stored thereon, characterized in that when the computer program is executed by a processor, the steps of a method described in any one of a transient power impulse quantity and a transient stability limit estimation method are implemented.

[0035] Beneficial effects of the present invention: The method of the present invention reduces the time required for calculations, allowing system operators to respond quickly after a fault occurs, thereby enhancing the reliability and safety of the power grid. The method of the present invention provides more accurate data support by accurately calculating transient power impact quantities and transient stability limits, helping engineers to better assess the stability and potential risks of the power grid. The rapid estimation method also supports the flexible adjustment of the power grid in the face of different operating conditions and fault conditions, helps to optimize the allocation and management of power resources, and ensures the continuity and efficiency of power supply, thereby improving the economy of the power grid while ensuring that the power supply needs of the public and industrial users are stably met. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0037] Figure 1 A pure AC thermal power transmission system model diagram of a transient power impact and transient stability limit estimation method provided by an embodiment of the present invention.

[0038] Figure 2 A model diagram of an AC / DC parallel thermal power transmission system providing a transient power impact and transient stability limit estimation method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0039] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0040] Embodiment 1 is the first embodiment of the present invention, which provides a method for estimating transient power impact and transient stability limit, including:

[0041] S1: Given the model parameters, establish a thermal power transmission model.

[0042] It should be noted that the establishment of the thermal power transmission model includes thermal power generation modeling, transmission system modeling and system side modeling;

[0043] The main components and functions of thermal power plant modeling are as follows:

[0044] Voltage and active power: Set the output voltage and power of the thermal generator.

[0045] Reactance and resistance: including synchronous reactance, transient reactance, etc. These parameters determine the behavior of the generator under dynamic conditions.

[0046] Control systems: such as excitation control and speed control systems, used to maintain the stability and efficiency of generator operation.

[0047] The main components and functions of transmission system modeling are as follows:

[0048] Transformer: Used to adjust voltage to a level suitable for long distance transmission.

[0049] Transmission lines: Resistance and reactance parameters determine transmission efficiency and transmission losses.

[0050] Protection devices: These include circuit breakers and relays, used to protect the system in the event of a fault.

[0051] Node and bus modeling: Setting the appropriate voltage level for each node or bus of the system affects the voltage distribution of the entire power grid. Nodes, as the connection points between power stations, loads and transmission lines, are key to power flow and voltage calculations.

[0052] The power transmission equipment includes a transformer and a power transmission line.

[0053] The purpose of establishing a thermal power transmission model is to simulate and analyze how thermal power plants can effectively transmit electricity to the power grid, which is key to the performance evaluation and optimization of the power system. This model is crucial for system stability analysis, especially in predicting and responding to power grid failures and their impact on stability. It provides basic data for the following analysis and calculations. Through the thermal power model, engineers can evaluate the behavior of generators under different operating conditions, optimize power generation efficiency and response strategies, and ensure efficient operation under various power grid conditions.

[0054] S2: Calculate the internal potential and power angle of the generator through the power at the end of the generator branch and the voltage at the node at the line sending end.

[0055] It should be noted that the calculation of the internal potential and power angle of the generator includes obtaining the internal potential and power angle of the generator according to the power at the end of the generator branch and the voltage at the node at the line sending end. The formula is expressed as follows:

[0056] δ G =arcsin(P e *X Σ / E′ q U G )

[0057]

[0058] Among them, δ G is the generator terminal voltage angle, arcsin(·) is the inverse sine function, P e is the electromagnetic power at the generator end, X Σ is the equivalent reactance of the transformer and line between the generator and the system, E' q is the internal potential of the generator, U G is the generator terminal voltage, is the reactive power at the generator end, E s is the system side voltage, cos(·) is the cosine function, ΔU G is the longitudinal component of voltage, δU G is the voltage transverse component, X d is the generator direct-axis synchronous reactance, δ q is the generator power angle, X' d is the transient reactance of the generator.

[0059] S3: Based on the generator rotor motion equation, calculate the unit oscillation frequency after the fault.

[0060] It should be noted that the generator rotor motion equation is expressed as:

[0061]

[0062] Where, f is the unit oscillation frequency, ω 0 is the rated speed, T j is the generator inertia time constant, is the power angle δ 0 The derivative of electromagnetic power with respect to power angle.

[0063] Further, the calculation of the unit oscillation frequency after the fault includes calculating the unit oscillation frequency after the tie line has a three-way N-1 fault based on the generator rotor motion equation. The generator rotor motion equation formula is expressed as:

[0064]

[0065] Among them, K s is the synchronous torque coefficient.

[0066] The three-phase N-1 fault assumes that in this most serious single-component failure scenario, the system can still maintain the transmission and distribution of power by reconfiguring or using alternative paths. In practical applications, this analysis is crucial to the design and operation security of the power grid, especially in large power grids with high loads or high dependencies.

[0067] S4: Calculate the peak value of the interconnection line power fluctuation after the fault occurs, and establish an estimation formula for the transient stability limit by combining the static stability limit and transient power impact after the fault.

[0068] It should be noted that the calculation of the peak value of the interconnection line power fluctuation after the fault occurs includes the square wave response of the second-order linear system. This response refers to the output or reaction of the second-order linear system when the system input is a square wave signal. The transient power impact formula is expressed as:

[0069] D P =ΔP·τ·2πf

[0070] Among them, D P is the transient power impact, τ is the equivalent time of power loss, and ΔP is the peak power fluctuation after the fault.

[0071] Furthermore, the transient stability limit estimation formula includes combining the post-fault static stability limit and the transient power impact to establish a transient stability limit estimation formula.

[0072]

[0073] Among them, P max is the static stability limit after fault, X Σ2 is the sum of the equivalent reactance of the transmission line and transformer after the fault, P st is the transient stability limit after a fault.

[0074] In summary, according to the power disturbance, power loss time and oscillation frequency after AC / DC fault, the calculation formula of transient power impact can be obtained, which reflects the impact energy, and the transient stability limit can be obtained according to the static stability limit after the accident - 0.5 times the transient power impact. The proposed transient power impact and transient stability limit estimation method can greatly improve the calculation efficiency when evaluating the actual engineering grid strength, while also ensuring accuracy.

[0075] The above is a schematic scheme of a transient power impact and transient stability limit estimation method of this embodiment. It should be noted that the technical scheme of the transient power impact and transient stability limit estimation system and the technical scheme of the transient power impact and transient stability limit estimation method described above belong to the same concept, and the details of the technical scheme of the transient power impact and transient stability limit estimation system not described in detail in this embodiment can be referred to the description of the technical scheme of the transient power impact and transient stability limit estimation method described above.

[0076] The transient power impact and transient stability limit estimation system in this embodiment includes: a model building module, a potential and power angle calculation module, an oscillation frequency calculation module and a stability limit estimation module;

[0077] The model building module builds a thermal power transmission model, including thermal power generation modeling, transmission system modeling and system side modeling;

[0078] The potential and power angle calculation module calculates the internal potential and power angle of the generator through the power at the end of the generator branch and the voltage at the node at the line sending end, providing key data for stability analysis;

[0079] The oscillation frequency calculation module calculates the oscillation frequency of the unit after a fault based on the generator rotor motion equation and analyzes the response speed and stability of the system;

[0080] The stability limit estimation module combines the post-fault static stability limit and the calculated transient power impact to derive an estimation formula for the maximum stable power level that the system can achieve after a specific fault.

[0081] This embodiment further provides a computing device, which is applicable to the case of a transient power impact amount and a transient stability limit estimation method, and includes:

[0082] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.

[0083] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0084] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0085] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0086] Example 2, reference Figure 1 , which is the second embodiment of the present invention, provides a method for estimating transient power impact and transient stability limit. In order to verify the accuracy of the method for estimating transient power impact and transient stability limit proposed in the present invention, a pure AC thermal power transmission system model is built using the power system analysis software PSD-BPA, such as Figure 1 As shown, the modeling parameters are as follows:

[0087] The generator adopts the classic second-order model, and its rated capacity P N =600MW, transient reactance per unit value X' based on the generator's own capacity d =0.25, transformer equivalent reactance X T =0.15, generator inertia time constant T j =60s, generator terminal voltage U G =1.0. Take the system base capacity S B =100MVA, the system side voltage vector is E s =1.0∠0°, equivalent reactance on the system side X s =0.017, single-circuit reactance of transmission line X L=0.06, considering the line voltage level is 220kV, so the line three permanent N-1 fault clearing time is 6 cycles, that is, τ = 0.12s. The initial electromagnetic power of the generator is arranged to be P 0 =550MW.

[0088] The internal potential and power angle of the generator are obtained based on the power at the end of the generator branch and the voltage at the node at the line sending end. First, the reactive output of the generator is calculated based on the initial electromagnetic power and the voltage at the head and end.

[0089]

[0090] Calculate the internal potential and power angle of the generator,

[0091]

[0092] Based on the generator rotor motion equation, the unit oscillation frequency after the tie line has a three-period N-1 fault is calculated, and the synchronous torque coefficient is:

[0093]

[0094] The unit oscillation frequency is,

[0095]

[0096] According to the square wave response of the second-order linear system, the peak value of the interconnection line power fluctuation after the fault occurs is calculated. The fault removal time is considered to be 0.12 seconds, that is, the transient power impact D P for,

[0097] D P =ΔP·τ·2πf=5.5×0.12×2π×0.8179=3.39

[0098] Combining the static stability limit after the accident and the transient power impact, the transient stability limit estimation formula is established. The static stability limit and transient stability limit after the accident are respectively:

[0099]

[0100] That is, the temporary stability limit is 576.7MW, and the error with the BPA simulation calculation result is 3.72%.

[0101] Taking into account the different operation modes in actual projects, the influence of different initial electromagnetic powers on the transient power impact is analyzed, and P 0 =300MW, 400MW and 500MW, compared with the BPA simulation results, the comparison error results are shown in Table 1.

[0102] Table 1 Error table of different initial electromagnetic power to temporary stability limit

[0103] <![CDATA[P 0 ]]> 300 400 500 Calculation results of the proposed method 607.4 591 587.65 BPA simulation results 599 599 599 error 1.4％ 1.34％ 1.89％

[0104] It can be seen from Table 1 that the calculation results of the proposed transient stability limit estimation formula are within 2% of the BPA simulation results, and can be well applied to the calculation value of the transient stability transmission power limit in actual engineering applications. At the same time, for different output operation modes, the transient stability limit estimation formula can improve the calculation efficiency while having good applicability.

[0105] Example 3, reference Figure 2 , which is the second embodiment of the present invention, provides a method for estimating transient power impact and transient stability limit. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through experiments.

[0106] The above embodiment is applicable to small systems transmitted through AC channels. This embodiment takes the AC / DC parallel thermal power transmission system as the research object to analyze the applicability of the transient stability power impact and transient stability limit estimation formula under DC disturbance. Figure 2 shown.

[0107] The modeling parameters are set as follows: the generator adopts the classic second-order model, and its rated capacity P N =600MW, a total of 20 thermal power units, transient reactance per unit value X based on the generator's own capacity d =0.25, single transformer reactance per unit value Generator inertia time constant T j =60s, generator terminal voltage U G =1.0. Take the system base capacity S B =100MVA, the system side voltage vector is E s =1.0∠0°, equivalent reactance on the system side X s =0.00158, single-circuit reactance per unit value of transmission line The line voltage level is 525kV. The DC model uses the two-terminal DC classical model, considering the DC commutation failure twice and the third commutation success fault disturbance, the fault disturbance time is 10 cycles, that is, τ = 0.2s.

[0108] Taking into account the different operating modes in actual projects, the influence of different initial electromagnetic powers on the transient power impact is analyzed, and DC powers of 8000MW, 7000MW and 6000MW are arranged respectively, and compared with the BPA simulation calculation results. The comparison error results are shown in Table 2 below.

[0109] Table 2 Error table of different DC power to temporary stability limit

[0110] <![CDATA[P DC ]]> 8000 7000 6000 Calculation results of the proposed method 3639 4243 5053 BPA simulation results 3040 3800 4560 error 19.69％ 11.67％ 10.81％

[0111] It can be seen from Table 2 that the calculation results of the proposed transient stability limit estimation formula have an error of 10%-20% compared with the BPA simulation results. Compared with AC disturbances, the error is relatively large, but it can meet the error requirements of engineering calculations and can be used to guide the system grid strength assessment under DC disturbances.

[0112] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for estimating transient power impact and transient stability limit, characterized in that: include, Given the model parameters, a thermal power transmission model is established; Calculate the internal potential and power angle of the generator through the power at the end of the generator branch and the voltage at the node at the line sending end; Based on the generator rotor motion equation, calculate the unit oscillation frequency after the fault; The peak value of the interconnection line power fluctuation after a fault occurs is calculated, and the estimation formula for the transient stability limit is established by combining the static stability limit and transient power impact after the fault.

2. The method for estimating transient power impact and transient stability limit according to claim 1, characterized in that: The establishment of the thermal power transmission model includes thermal power generation modeling and transmission system modeling; The thermal power generation modeling includes setting the generator terminal voltage, power, generator transient reactance and transmission equipment reactance parameters; The power transmission equipment includes a transformer and a power transmission line; The transmission system modeling includes the modeling of transmission lines, transformers, nodes and buses.

3. A method for estimating transient power impact and transient stability limit according to claim 2, characterized in that: The calculation of the internal potential and power angle of the generator includes obtaining the internal potential and power angle of the generator according to the power at the end of the generator branch and the voltage at the node at the line sending end. The formula is expressed as follows: δ G =arcsin(P e *X Σ / TEACHER' q U G ) Among them, δ G is the generator terminal voltage angle, arcsin(·) is the inverse sine function, P e is the electromagnetic power at the generator end, X Σ is the equivalent reactance of the transformer and line between the generator and the system, E' q is the potential inside the generator, U G is the generator terminal voltage, is the reactive power at the generator end, E s is the system side voltage, cos(·) is the cosine function, ΔU G is the longitudinal component of voltage, δU G is the voltage transverse component, X d is the generator direct-axis synchronous reactance, δ q is the generator power angle, X' d is the transient reactance of the generator.

4. A method for estimating transient power impact and transient stability limit according to claim 3, characterized in that: The generator rotor motion equation is expressed as: Where f is the unit oscillation frequency, ω0 is the rated speed, T j is the generator inertia time constant, is the derivative of the electromagnetic power with respect to the power angle at the power angle δ0.

5. A method for estimating transient power impact and transient stability limit according to claim 4, characterized in that: The calculation of the unit oscillation frequency after the fault includes calculating the unit oscillation frequency after the tie line fault based on the generator rotor motion equation, and the formula is expressed as: Among them, K s is the synchronous torque coefficient.

6. A method for estimating transient power impact and transient stability limit according to claim 5, characterized in that: The peak value of the power fluctuation of the interconnection line after the fault occurs is calculated by the square wave response of the second-order linear system. The transient power impact amount formula is expressed as follows: D P =ΔP·τ·2πf Among them, D P is the transient power impact, τ is the equivalent time of power loss, and ΔP is the peak power fluctuation after the fault.

7. A method for estimating transient power impact and transient stability limit according to claim 6, characterized in that: The transient stability limit estimation formula includes combining the post-fault static stability limit and the transient power impact to establish a transient stability limit estimation formula, which is expressed as: Among them, P max is the static stability limit after fault, X Σ2 is the sum of the equivalent reactance of the transmission line and transformer after the fault, P st is the transient stability limit after a fault.

8. A system based on a method for estimating transient power impact and transient stability limit according to any one of claims 1 to 7, characterized in that: It includes a model building module, a potential and power angle calculation module, an oscillation frequency calculation module and a stability limit estimation module; The model building module builds a thermal power transmission model, including thermal power generation modeling, transmission system modeling and system side modeling; The potential and power angle calculation module calculates the internal potential and power angle of the generator through the power at the end of the generator branch and the voltage at the node at the line sending end, providing key data for stability analysis; The oscillation frequency calculation module calculates the oscillation frequency of the unit after a fault based on the generator rotor motion equation and analyzes the response speed and stability of the system; The stability limit estimation module combines the post-fault static stability limit and the calculated transient power impact to derive an estimation formula for the maximum stable power level that the system can achieve after a specific fault.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

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

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