Method, system and device for determining transient synchronization stability boundary of grid-following converter and medium

Abstract

The present application belongs to the technical field of grid-following converter operation and control, and discloses a method, system, device and medium for determining the transient synchronous stability boundary of a grid-following converter, to solve the problem of insufficient universality of existing analysis methods or being limited to specific operating conditions. The method comprises: a transient simulation step; an energy calculation step; an energy margin calculation step; a sensitivity calculation step; a critical value searching step; and a stability boundary determination step. To solve the problem of poor accuracy caused by existing methods being limited to specific operating conditions and model simplification, the present application establishes an accurate transient simulation model, introduces a mechanism for adaptively calculating the maximum potential energy, intelligently selects a direct calculation, disturbance iteration or voltage adjustment path according to the power angle trajectory dynamics, ensures that the method is applicable under different power grid structures, faults and operating modes, accurately captures the real stability boundary, and realizes accurate evaluation of transient synchronous stability.

Description

Technical Field

[0001] This invention belongs to the field of grid-connected converter operation and control technology, specifically relating to the method, system, equipment and medium for determining the transient synchronization stability boundary of a grid-connected converter. Background Technology

[0002] As a key interface between new energy sources and the power grid, the dynamic characteristics of grid-connected converters have an increasingly significant impact on system stability. Unlike synchronous generators, which have inherent rotational inertia and damping characteristics, grid-connected converters typically rely on phase-locked loops (PLLs) to achieve synchronization with the grid. When the grid experiences large disturbances such as short circuits, the synchronization stability of the PLL becomes particularly critical, with voltage dips at the grid connection point and their duration being the core factors causing out-of-synchronization and grid disconnection.

[0003] Currently, the transient synchronization stability analysis of grid-connected converters mainly draws on and extends the stability theory of traditional synchronous machines. Typical methods include:

[0004] Phase plane method: This method visually assesses stability by plotting the phase trajectories of the virtual power angle and angular velocity of the phase-locked loop after a fault. However, its analytical conclusions heavily rely on specific initial simulation conditions and network parameters, lacking universality and making it difficult to extract general rules applicable to a wide range of operating scenarios.

[0005] Lyapunov's direct method: This method assesses the stability region of a system by constructing a virtual energy function. Although theoretically rigorous, constructing an accurate energy function for grid-connected converters with complex control loops is very difficult. Existing methods usually require significant simplification, leading to conservative evaluation results that fail to accurately characterize the true stability boundary.

[0006] The equal-area rule: This method qualitatively judges stability by comparing the acceleration energy during a fault with the deceleration energy after the fault is cleared. However, its core model ignores the dynamic processes of the phase-locked loop and current loop controller, as well as system damping, making it difficult to accurately calculate the stability boundary quantitatively, resulting in significant errors in engineering applications.

[0007] In summary, existing analytical methods are either limited by specific working conditions and lack universality, or their accuracy is poor due to model simplification. Furthermore, their analytical processes are complex and their output results are not intuitive enough. Summary of the Invention

[0008] Based on the aforementioned shortcomings and deficiencies in the existing technology, one of the objectives of this invention is to at least solve one or more of the aforementioned problems in the existing technology. In other words, one of the objectives of this invention is to provide a method, system, device, and medium for determining the transient synchronization stability boundary of a grid-connected converter that meets one or more of the aforementioned requirements, so as to achieve rapid and accurate assessment of the transient synchronization stability of the grid-connected converter, thereby improving the safe and stable operation capability of the power grid and preventing systemic risks caused by synchronization instability.

[0009] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a method for determining the transient synchronization stability boundary of a grid-type converter, comprising the following steps:

[0011] S1. Transient simulation steps: Perform a preset fault transient simulation on the grid-connected converter system to obtain the dynamic response data of electrical quantities during the period from fault occurrence to fault clearing.

[0012] S2. Energy calculation steps: Based on the electrical quantity dynamic response data, calculate the kinetic energy and maximum potential energy of the phase-locked loop after the fault;

[0013] S3. Energy margin calculation steps: Based on the kinetic energy and the maximum potential energy, calculate the transient synchronous stability energy margin of the grid-connected converter;

[0014] S4. Sensitivity Calculation Steps: Based on the grid impedance parameters, the sensitivity of the transient synchronous stability energy margin to the grid connection point voltage is calculated using the chain rule.

[0015] S5. Critical value search step: Based on the sensitivity, determine the initial value of the voltage drop at the grid connection point, and starting from this initial value, adjust the voltage drop value through iterative approximation and re-execute the transient simulation until the preset convergence condition is met, thereby searching for the maximum voltage drop critical value at the grid connection point that maintains transient synchronization and stability.

[0016] S6. Stability boundary determination step: Change the fault duration and repeat the above steps to obtain a series of maximum voltage drop critical values ​​corresponding to different fault durations, thereby determining the transient synchronous stability boundary of the grid-connected converter.

[0017] As a preferred embodiment, the preset fault is a three-phase short-circuit fault on the power grid side; the fault occurrence and clearing times are respectively denoted as... and The electrical quantity dynamic response data includes the phase-locked loop virtual power angle. Phase-locked loop output angular velocity Grid connection point voltage of Axial components and the current loop current Axial components .

[0018] As a preferred option, the formula for calculating the kinetic energy of the phase-locked loop after a fault is:

[0019] ,

[0020] In the formula, and These are the output angular velocities of the phase-locked loop. exist and The value at any given moment.

[0021] As a preferred embodiment, calculating the maximum potential energy includes the following steps:

[0022] S21. Determine whether there is a maximum value point in the virtual power angle trajectory of the phase-locked loop after the fault is cleared.

[0023] S22. If a maximum point exists, at the first time point... The maximum potential energy is defined as follows: if the rate of change is zero for the first time and then turns positive thereafter. In the formula, This is the proportional gain of the phase-locked loop. The integral coefficient is... Voltage at grid connection point of Axial components The differential value;

[0024] S23. If there is a maximum point, but its rate of change turns negative after the first time point, then a virtual power angle disturbance is injected into the simulation system, and an iterative algorithm is used to correct the disturbance until the preset conditions are met, and then the maximum potential energy is calculated based on the disturbance at this time.

[0025] S24. If no maximum point exists, adjust the grid connection point voltage level after the fault in the simulation, re-execute the transient simulation, and return to step S21.

[0026] As a preferred embodiment, the step of using an iterative algorithm to correct the perturbation until a preset condition is met before calculating the maximum potential energy based on the perturbation at that moment is specifically as follows:

[0027] The perturbation is iteratively corrected using a bisection method until the condition is met later than the first time point. Second time point The virtual work angle trajectory is calculated only if its rate of change is zero for the first time and then turns positive, or if the absolute value of the difference between the disturbances injected in two consecutive iterations is less than a preset deviation value. The maximum potential energy is... .

[0028] As a preferred approach, the sensitivity is calculated as follows:

[0029] The transient synchronization stability energy margin is expressed as a function of the fault clearing time;

[0030] According to the chain rule, the sensitivity is decomposed into the product of the partial derivative of the energy margin with respect to the fault clearing time and the partial derivative of the fault clearing time with respect to the grid connection point voltage.

[0031] The calculation of the partial derivative of the grid connection point voltage at the fault clearing moment introduces the total resistance and total reactance between the grid connection point and the short circuit point.

[0032] As a preferred option, step S6 specifically involves:

[0033] Calculate in sequence for Actual value of maximum voltage drop at grid connection point when the transient synchronization of the time-tracking grid converter is stable. And construct a binary tuple based on the fault duration and the actual value of the maximum voltage drop. The duration of the fault is characterized as The maximum voltage drop at the grid connection point that maintains transient synchronization with the grid-connected converter is [value missing]. ,in , =1, 2, 3, ... , The value is a preset integer.

[0034] Secondly, the present invention provides a system for determining the transient synchronization stability boundary of a grid-type converter, used to implement the determination method described in the first aspect, including:

[0035] The simulation module is used to perform preset fault transient simulation on grid-connected converter systems and record the dynamic response data of electrical quantities during the period from fault occurrence to fault clearance.

[0036] The stability margin assessment module is used to calculate the transient synchronization stability margin of the grid converter based on the dynamic response data of electrical quantities.

[0037] The sensitivity calculation module is used to calculate the sensitivity of the transient synchronization stability margin of the grid-connected converter to the grid connection point voltage.

[0038] The voltage drop maximum calculation module is used to calculate the maximum voltage drop at the grid connection point when the grid-connected converter can maintain transient synchronization and stability.

[0039] Thirdly, the present invention provides an electronic device, the computer device including a memory, a processor, and a computer program, wherein the computer program, when executed by the processor, implements the determination method as described in the first aspect.

[0040] Fourthly, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the determination method as described in the first aspect.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. This invention significantly improves the universality and accuracy of stability assessment. Addressing the limitations of existing methods due to specific operating conditions and the resulting inaccuracies caused by model simplification, this invention establishes a precise transient simulation model and introduces an adaptive mechanism for calculating maximum potential energy (intelligently selecting direct calculation, disturbance iteration, or voltage adjustment paths based on the dynamic power angle trajectory). This ensures the method is applicable to different power grid structures, faults, and operating modes, accurately capturing the true stability boundary and achieving precise assessment of transient synchronous stability.

[0043] 2. This invention greatly simplifies the analysis process and improves evaluation efficiency. Addressing the problems of complex analysis processes and difficulty in rapid application of existing methods, this invention utilizes the sensitivity of stability margin to voltage to quickly locate the initial search value and combines it with the bisection method for efficient iteration, constructing an automated computational pipeline from simulation to criteria. This avoids the extensive manual intervention and repetitive simulations required by traditional trial-and-error methods, achieving rapid and automatic determination of stability boundaries.

[0044] 3. This invention provides intuitive and easy-to-understand engineering criteria, enabling "instant access" to evaluation results. Addressing the shortcomings of existing methods that produce abstract and unintuitive outputs, this invention condenses complex stability theory into a stability boundary in the form of a binary tuple: "fault duration - maximum permissible voltage drop." This criterion has a simple structure and clear physical meaning, requiring no complex theoretical interpretation. Power grid operators can directly make stability judgments by comparing fault information with the criterion database, greatly improving the efficiency of rapid evaluation and decision-making speed.

[0045] Further or more detailed beneficial effects will be described in conjunction with specific embodiments in the detailed implementation. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 This is a flowchart illustrating the determination method described in Embodiment 1 of the present invention.

[0048] Figure 2 This is a schematic diagram of the structure of the determination system described in Embodiment 2 of the present invention.

[0049] Figure 3 This is a structural diagram of the electronic device described in Embodiment 3 of the present invention.

[0050] Icon labels:

[0051] 300. Electronic devices;

[0052] 301. Processor; 302. Communication bus; 303. User interface; 304. Network interface; 305. Memory. Detailed Implementation

[0053] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0054] In the following description, several embodiments of the present invention are provided. Different embodiments can be substituted or combined. Therefore, the present invention can also be considered to include all possible combinations of the same and / or different embodiments described. Thus, if one embodiment includes features A, B, and C, and another embodiment includes features B and D, then the present invention should also be considered to include embodiments containing one or more other possible combinations of A, B, C, and D, even if such embodiments are not explicitly described in the following text.

[0055] The following description provides examples and does not limit the scope, applicability, or examples set forth in the claims. Changes may be made to the function and arrangement of the described elements without departing from the scope of the invention. Various processes or components may be appropriately omitted, substituted, or added to the various examples. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Furthermore, features described with respect to some examples may be combined into other examples.

[0056] To facilitate a better understanding of the embodiments of the present invention, its application scenarios will be explained before providing a detailed explanation of the specific implementation methods.

[0057] The determination method described in the embodiments of this specification is applied to the processes of "safety and stability analysis of high proportion of new energy access to power systems" and "grid-connected converter performance evaluation and control protection setting". In these scenarios, the application of the determination method aims to:

[0058] 1. Provide quantitative analysis tools for power grid planning and operation departments to assess the transient synchronization stability of new energy power plants when encountering short-circuit faults under a specific power grid structure, thereby identifying weak links in the system during the planning stage.

[0059] 2. Provide rapid stability criteria for power grid dispatch and control. By pre-calculating and generating stability boundaries (voltage-time pairs) under different fault scenarios, operators can quickly compare fault information with stability boundaries when actual faults occur, and immediately determine whether new energy generating units are facing the risk of losing synchronization, providing key basis for emergency control decisions (such as unit tripping and reactive power support).

[0060] 3. This method provides a theoretical basis for setting parameters of relay protection and automatic safety devices. It can accurately determine the critical voltage drop value for maintaining stability, and can be used to optimize the low-voltage ride-through curve in renewable energy stations, set the operating threshold of safety and stability control devices, and improve the overall safety and defense capabilities of the system.

[0061] The following is a brief explanation of the grid-connected converter, phase-locked loop, transient synchronous stability boundary, transient simulation, transient synchronous stability energy margin, sensitivity, and binary search method involved in several embodiments of this specification:

[0062] A grid-connected converter is a converter that synchronizes with the grid voltage phase through a phase-locked loop, and whose output current amplitude and phase are controlled by the grid voltage. It is the mainstream interface equipment for connecting new energy power generation units such as wind power and photovoltaic power to the grid, and its stability directly determines the grid connection characteristics of new energy power plants.

[0063] A phase-locked loop (PLL) is an automatic control system used to ensure that the AC signal generated inside the converter accurately tracks the grid voltage signal in terms of phase and frequency. It is the core control component for achieving synchronization between grid-connected converters and the grid. Under large disturbances, the dynamic response of the PLL may lose synchronization, leading to system stability problems.

[0064] The transient synchronous stability boundary refers to the set of critical conditions that enable a grid-connected converter to maintain synchronous stability with the power grid under fault disturbances. In this invention, this boundary is specifically represented as a curve or data set consisting of the maximum allowable voltage drop threshold at the grid connection point corresponding to different fault durations, serving as a quantitative boundary for dividing the stable and unstable regions.

[0065] Transient simulation refers to the use of computer mathematical models to simulate the dynamic changes of various electrical quantities (voltage, current, power angle, etc.) in a power system during the brief period from the occurrence and duration of a sudden fault (such as a short circuit) to its clearing. It is the basis for obtaining dynamic response data of these electrical quantities.

[0066] Transient synchronization stability energy margin is an indicator used to quantify the degree of transient synchronization stability. Based on the rotor motion equations analogous to a synchronous machine, it quantitatively assesses the degree to which the system is moving away from the instability boundary by calculating the relative magnitude between the kinetic energy of the phase-locked loop after a fault and the maximum potential energy the system can absorb. A positive margin indicates stability, while a negative or zero margin indicates instability.

[0067] In this invention, sensitivity refers to the sensitivity of the transient synchronous stability energy margin to the grid connection point voltage. It quantitatively describes how a small change in the grid connection point voltage will cause a change in the stability margin. Its magnitude reflects the degree of influence of voltage on stability and is a key guiding information for quickly searching the stability boundary.

[0068] The bisection method is an iterative numerical method for rapidly finding the roots of equations or the critical points of functions within an ordered interval. In this invention, it is used in two core iterative processes: first, in calculating the maximum potential energy, to determine the amount of virtual power angle disturbance required to bring the system to a critical stable state; and second, in searching for the critical voltage, to quickly locate the critical value of the maximum voltage drop at the grid connection point. This method ensures that the calculation converges to the true solution exponentially.

[0069] Example 1:

[0070] like Figure 1 As shown in the figure, this embodiment provides a method for determining the transient synchronization stability boundary of a grid-type converter, including the following steps:

[0071] S1. Transient simulation steps: Perform a preset fault transient simulation on the grid-connected converter system to obtain the dynamic response data of electrical quantities during the period from the occurrence of the fault to its clearing.

[0072] Specifically, in this embodiment, the preset fault is a three-phase short-circuit fault on the grid side of the grid-connected converter system, and the fault occurrence and clearing times are denoted as follows: and The electrical quantity dynamic response data includes the phase-locked loop virtual power angle. Phase-locked loop output angular velocity Grid connection point voltage of Axial components and the current loop current Axial components .

[0073] More specifically, the virtual power angle of the phase-locked loop is determined by... (1) Calculate, in equation (1), The output angle of the phase-locked loop. The angle represents the grid voltage.

[0074] S2. Energy calculation steps: Based on the electrical quantity dynamic response data, calculate the kinetic energy and maximum potential energy of the phase-locked loop after the fault.

[0075] Specifically, the formula for calculating the kinetic energy of the phase-locked loop after a fault is as follows:

[0076] (2),

[0077] In equation (2), and These are the output angular velocities of the phase-locked loop. exist and The value at any given moment.

[0078] Specifically, calculating the maximum potential energy includes the following steps:

[0079] S21. Determine whether there is a maximum value point in the virtual power angle trajectory of the phase-locked loop after the fault is cleared.

[0080] S22. When the fault is cleared, the virtual power angle trajectory has a maximum point, and The first time I was satisfied =0 and subsequently At that time, the maximum potential energy is calculated according to formula (3):

[0081] (3),

[0082] In equation (3), This is the proportional gain of the phase-locked loop. The integral coefficients of the phase-locked loop are... Let the differential operator be denoted as , then Voltage at grid connection point The differential value of .

[0083] S23. After the fault is cleared, the virtual power angle trajectory has a maximum point, but... The first time I was satisfied =0 and subsequently Then, perform multiple transient simulations again, and with The initial interval is determined using the bisection method in each simulation. The disturbance amount injected into the virtual power angle trajectory of the phase-locked loop at all times, until... (greater than) The virtual work angle trajectory at time 10 is satisfied for the first time. =0 and subsequently Or the virtual work angle trajectory satisfies the first time =0 and the absolute value of the difference between the two injected disturbance values ​​is less than the preset deviation value. The maximum potential energy is calculated according to formula (4):

[0084] (4);

[0085] The Calculate according to formula (5):

[0086] (5),

[0087] In equation (5), The equivalent inductance on the grid side, ω represents the angular velocity of the grid voltage.

[0088] S24. If the virtual power angle trajectory does not have a maximum point after the fault is cleared, then the voltage at the grid connection point after the fault will be increased. Then, perform the transient simulation again and return to S21.

[0089] S3. Energy margin calculation steps: Based on the kinetic energy and the maximum potential energy, calculate the transient synchronization stability energy margin of the grid-connected converter. The specific calculation process is as follows:

[0090] Based on the dynamic equation of the phase-locked loop output angular velocity (6) We can obtain:

[0091] (7),

[0092] consider and satisfy (8),

[0093] In equation (8), and These are the total reactance and total resistance between the grid connection point and the short circuit point, respectively.

[0094] Based on the above formula, we can obtain:

[0095] (9),

[0096] Due to the faulty phase-locked loop output angular velocity With fault clearing time Therefore, the transient synchronization stability margin is rewritten as (10) We can obtain:

[0097] (11).

[0098] S4. Sensitivity Calculation Steps: Based on the grid impedance parameters, the sensitivity of the transient synchronous stability energy margin to the grid connection point voltage is calculated using the chain rule. The specific calculation process is as follows:

[0099] Based on the chain rule, sensitivity is... Written as:

[0100] (12)

[0101] In (12), , , , Describes the differential operator.

[0102] Therefore, we get:

[0103] (13).

[0104] S5. Critical Value Search Step: Based on the sensitivity, determine the initial value of the voltage drop at the grid connection point. Starting from this initial value, adjust the voltage drop value through iterative approximation and re-execute the transient simulation until the preset convergence condition is met. This searches for the maximum voltage drop critical value at the grid connection point that maintains transient synchronization and stability. The specific calculation process is as follows:

[0105] S51. Calculate the initial value of the maximum voltage drop according to formula (14). :

[0106] (14)

[0107] In equation (14), for exist The value at time, by taking Phase-locked loop output angular velocity at time Phase-locked loop output angle Grid connection point voltage of Axial components and its differential value Perform the calculation.

[0108] S52, Let the number of transient simulations be... Set grid connection point voltage drop Perform the first transient simulation, if = If so, proceed to step S56; < Proceed to step S53; otherwise, proceed to step S54.

[0109] S53, Order , = , to proceed with the first Subtransient simulation, if = Proceed to step S56; if > ,make and with If the initial interval for the bisection method is given, proceed to step S55; otherwise, repeat this step.

[0110] The , The first The voltage drop at the grid connection point during subtransient simulation and The phase-locked loop outputs angular velocity at all times. =1, 2, 3, ...

[0111] S54, Order , = , to proceed with the first Subtransient simulation, if = Proceed to step S56; if < ,make and with If the initial interval is the bisection interval, proceed to step S55; otherwise, repeat this step.

[0112] S55, Order The voltage drop at the grid connection point is determined using the binary search method, and the process is repeated. Subtransient simulation, if or Proceed to step S56; otherwise, repeat this step; where, This is the allowable error value.

[0113] S56, Order ,by The fault clearing time is The time-synchronous grid converter can maintain the actual value of the maximum voltage drop at the grid connection point under transient synchronous stability.

[0114] S6. Stability Boundary Determination Steps: By changing the fault duration, repeat the aforementioned steps to obtain a series of maximum voltage drop critical values ​​corresponding to different fault durations, thereby determining the transient synchronous stability boundary of the grid-connected converter. The specific operation is as follows:

[0115] Calculate in sequence for Actual value of maximum voltage drop at grid connection point when the grid-connected converter is in transient synchronization and stable state. And construct a binary tuple based on the fault duration and the actual value of the maximum voltage drop. The duration of the fault is characterized as The maximum voltage drop at the grid connection point that maintains transient synchronization with the grid-connected converter is [value missing]. ,in , =1, 2, 3, ... , The value is a preset integer.

[0116] Example 2:

[0117] like Figure 2 As shown, this embodiment provides a system for determining the transient synchronization stability boundary of a grid-type converter, used to implement the determination method described in Embodiment 1, including:

[0118] The simulation module is used to perform preset fault transient simulation on grid-connected converter systems and record the dynamic response data of electrical quantities during the period from fault occurrence to fault clearance.

[0119] The stability margin assessment module is used to calculate the transient synchronization stability margin of the grid converter based on the dynamic response data of electrical quantities.

[0120] The sensitivity calculation module is used to calculate the sensitivity of the transient synchronization stability margin of the grid-connected converter to the grid connection point voltage.

[0121] The voltage drop maximum calculation module is used to calculate the maximum voltage drop at the grid connection point when the grid-connected converter can maintain transient synchronization and stability.

[0122] Specifically, the system also includes a parameter acquisition model for acquiring the grid-side equivalent inductance, phase-locked loop ratio, and integral parameters of the grid-connected converter system.

[0123] Example 3:

[0124] like Figure 3 As shown, this embodiment provides an electronic device, which may include: at least one processor, at least one network interface, a user interface, a memory, and at least one communication bus.

[0125] The communication bus can be used to enable communication between the various components mentioned above.

[0126] The user interface may include buttons, and optional user interfaces may also include standard wired interfaces and wireless interfaces.

[0127] The network interface may include, but is not limited to, Bluetooth modules, NFC modules, Wi-Fi modules, etc.

[0128] The processor may include one or more processing cores. It connects various parts of the electronic device via various interfaces and lines, executing instructions, programs, code sets, or instruction sets stored in memory, and accessing data stored in memory to perform various functions and process data. Optionally, the processor can be implemented using at least one hardware form of DSP, FPGA, or PLA. The processor may integrate one or more of the following: CPU, GPU, and modem. The CPU primarily handles the operating system, user interface, and applications; the GPU is responsible for rendering and drawing the content required for display; and the modem handles wireless communication. It is understood that the modem may also be implemented as a separate chip without being integrated into the processor.

[0129] The memory may include RAM or ROM. Optionally, the memory may include a non-transitory computer-readable medium. The memory can be used to store instructions, programs, code, code sets, or instruction sets. The memory may include a program storage area and a data storage area, wherein the program storage area may store instructions for implementing an operating system, instructions for at least one function (such as touch function, sound playback function, image playback function, etc.), instructions for implementing the above-described method embodiments, etc.; the data storage area may store data involved in the above-described method embodiments, etc. Optionally, the memory may also be at least one storage device located remotely from the aforementioned processor. The memory, as a computer storage medium, may include an operating system, a network communication module, a user interface module, and a defined application program. The processor can be used to invoke the defined application program stored in the memory and execute the steps of the determination method mentioned in the foregoing embodiments.

[0130] Example 4:

[0131] This embodiment provides a computer-readable storage medium storing instructions that, when executed on a computer or processor, cause the computer or processor to perform the above-described instructions. Figure 1 One or more steps in the illustrated embodiment. If the constituent modules of the above-described electronic device are implemented as software functional units and sold or used as independent products, they can be stored in the computer-readable storage medium.

[0132] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this specification are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in or transmitted through a computer-readable storage medium. The computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, Digital Subscriber Line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available media may be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., Digital Versatile Discs (DVDs)), or semiconductor media (e.g., Solid State Disks (SSDs)).

[0133] Those skilled in the art will understand that all or part of the processes in the method of Embodiment 1 described above can be implemented by a computer program instructing related hardware. This program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the methods described above. The aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks. Unless otherwise specified, the technical features of this embodiment and the implementation scheme can be combined arbitrarily.

[0134] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0135] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0136] The above description is merely an exemplary embodiment of the present invention and should not be construed as limiting the scope of the invention. Any equivalent changes and modifications made in accordance with the teachings of this invention are still within the scope of this invention. Those skilled in the art will readily conceive of embodiments of the invention upon considering the specification and practicing the disclosure herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not described herein. The specification and embodiments are to be considered exemplary only, and the scope and spirit of the invention are defined by the claims.

Claims

1. A method for determining the transient synchronization stability boundary of a grid-type converter, characterized in that, Includes the following steps: S1. Transient simulation steps: Perform a preset fault transient simulation on the grid-connected converter system to obtain the dynamic response data of electrical quantities during the period from fault occurrence to fault clearing. S2. Energy calculation steps: Based on the electrical quantity dynamic response data, calculate the kinetic energy and maximum potential energy of the phase-locked loop after the fault; S3. Energy margin calculation steps: Based on the kinetic energy and the maximum potential energy, calculate the transient synchronous stability energy margin of the grid-connected converter; Calculating the maximum potential energy includes the following steps: S21. Determine whether there is a maximum value point in the virtual power angle trajectory of the phase-locked loop after the fault is cleared. S22. If a maximum point exists, at the first time point... The maximum potential energy is defined as follows: if the rate of change is zero for the first time and then turns positive thereafter. In the formula, This is the proportional gain of the phase-locked loop. The integral coefficient is... Voltage at grid connection point of Axial components The differential value; S23. If there is a maximum point, but its rate of change turns negative after the first time point, then a virtual power angle disturbance is injected into the simulation system, and an iterative algorithm is used to correct the disturbance until the preset conditions are met, and then the maximum potential energy is calculated based on the disturbance at this time. S24. If there is no maximum point, adjust the grid connection point voltage level after the fault in the simulation, re-execute the transient simulation and return to step S21. S4. Sensitivity Calculation Steps: Based on the grid impedance parameters, the sensitivity of the transient synchronous stability energy margin to the grid connection point voltage is calculated using the chain rule. S5. Critical value search step: Based on the sensitivity, determine the initial value of the voltage drop at the grid connection point, and starting from this initial value, adjust the voltage drop value through iterative approximation and re-execute the transient simulation until the preset convergence condition is met, thereby searching for the maximum voltage drop critical value at the grid connection point that maintains transient synchronization and stability. S6. Stability boundary determination step: Change the fault duration and repeat the above steps to obtain a series of maximum voltage drop critical values ​​corresponding to different fault durations, thereby determining the transient synchronous stability boundary of the grid-connected converter.

2. The method for determining the transient synchronization stability boundary of a grid-connected converter according to claim 1, characterized in that: The preset fault is a three-phase short-circuit fault on the power grid side; The times of fault occurrence and resection are denoted as follows: and ; The electrical quantity dynamic response data includes the phase-locked loop virtual power angle. Phase-locked loop output angular velocity Grid connection point voltage of Axial components and the current loop current Axial components .

3. The method for determining the transient synchronization stability boundary of a grid-connected converter according to claim 2, characterized in that, The formula for calculating the kinetic energy of the phase-locked loop after a fault is: ， In the formula, and These are the output angular velocities of the phase-locked loop. exist and The value at any given moment.

4. The method for determining the transient synchronization stability boundary of a grid-connected converter according to claim 3, characterized in that, The step of using an iterative algorithm to correct the disturbance until a preset condition is met before calculating the maximum potential energy based on the disturbance at that moment is as follows: The perturbation is iteratively corrected using a bisection method until the condition is met later than the first time point. Second time point The virtual work angle trajectory is calculated only if its rate of change is zero for the first time and then turns positive, or if the absolute value of the difference between the disturbances injected in two consecutive iterations is less than a preset deviation value. The maximum potential energy is... .

5. The method for determining the transient synchronization stability boundary of a grid-connected converter according to claim 4, characterized in that, The sensitivity is calculated as follows: The transient synchronization stability energy margin is expressed as a function of the fault clearing time; According to the chain rule, the sensitivity is decomposed into the product of the partial derivative of the energy margin with respect to the fault clearing time and the partial derivative of the fault clearing time with respect to the grid connection point voltage. The calculation of the partial derivative of the grid connection point voltage at the fault clearing moment introduces the total resistance and total reactance between the grid connection point and the short circuit point.

6. The method for determining the transient synchronization stability boundary of a grid-connected converter according to claim 5, characterized in that, Step S6 is as follows: Calculate in sequence for Actual value of maximum voltage drop at grid connection point when the transient synchronization of the time-tracking grid converter is stable. And construct a binary tuple based on the fault duration and the actual value of the maximum voltage drop. The duration of the fault is characterized as The maximum voltage drop at the grid connection point that maintains transient synchronization with the grid-connected converter is [value missing]. ,in , =1, 2, 3, ... , The value is a preset integer.

7. A system for determining the transient synchronization stability boundary of a grid-type converter, characterized in that, For implementing the determination method as described in any one of claims 1 to 6, comprising: The simulation module is used to perform preset fault transient simulation on grid-connected converter systems and record the dynamic response data of electrical quantities during the period from fault occurrence to fault clearance. The stability margin assessment module is used to calculate the transient synchronization stability margin of the grid converter based on the dynamic response data of electrical quantities. The sensitivity calculation module is used to calculate the sensitivity of the transient synchronization stability margin of the grid-connected converter to the grid connection point voltage. The voltage drop maximum calculation module is used to calculate the maximum voltage drop at the grid connection point when the grid-connected converter can maintain transient synchronization and stability.

8. A computer device, the computer device comprising a memory, a processor, and a computer program, characterized in that, When the computer program is executed by a processor, it implements the determination method as described in any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the determination method as described in any one of claims 1 to 6.

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