Method, system, device and medium for equivalent of power grid with new energy repeatedly low penetration characteristics

Abstract

The present application belongs to the technical field of power system automation, and discloses a power grid equivalence method, system, device and medium for preserving new energy repeated low penetration characteristics, to solve the problems of low simulation efficiency, long analysis time and inability to accurately preserve new energy repeated low penetration characteristics. The method comprises: taking a new energy collection bus as a starting point, and classifying the transmission lines of the power grid into sections; based on the section classification result, calculating the sensitivity of the short-circuit ratio of the new energy collection bus after each line in each section is opened; based on the sensitivity result, determining the internal system, the external system and the boundary node connecting the internal system and the external system; equivalent to the external system by the multi-port Thevenin equivalence method; according to the consistency of the new energy repeated low penetration situation of the system before and after equivalence under the line outage fault, the final equivalent power grid is determined. The present application improves the analysis efficiency of the new energy repeated low penetration characteristics while ensuring the simulation accuracy.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of power system automation, and particularly relates to a power grid equivalence method, system, device and medium for preserving new energy repeated low penetration characteristics. BACKGROUND

[0002] With the development of energy field technology, the construction of new power systems is accelerating, and the proportion of new energy such as wind power and photovoltaic power in power grids is rapidly rising. Compared with traditional power equipment, power electronic equipment has obvious differences in physical structure, control method, dynamic response characteristics, and interaction with other equipment. Its fast and flexible control characteristics have a significant impact on the dynamic behavior of the power system.

[0003] In the scenario of high proportion of new energy access to weak power grids, new energy may repeatedly enter and exit low voltage ride through (low penetration) when high power output occurs. This will cause non-periodic fluctuations in new energy power, voltage and other electrical quantities, which may lead to large-scale disconnection of new energy units, seriously threatening the safe and stable operation of the power grid, and also affecting the effective utilization of new energy.

[0004] In order to accurately grasp the characteristics of new energy repeated low penetration, deeply understand and effectively deal with power grid oscillation risk, and ensure the safe and stable operation of the power grid, full electromagnetic simulation of high proportion of new energy power grid is needed. However, due to the complexity of the model, simulation step and other factors, when full electromagnetic simulation is performed on large power grids, there are problems of low simulation efficiency and long analysis time. And in the process of grid equivalence, the existing technology cannot accurately preserve the characteristics of new energy repeated low penetration, and it is difficult to meet the requirements of accurate analysis of the characteristics of high proportion of new energy power grid and ensuring its safe and stable operation. SUMMARY

[0005] Based on the above-mentioned shortcomings and deficiencies in the prior art, one of the purposes of the present application is to at least solve one or more of the above-mentioned problems in the prior art, in other words, one of the purposes of the present application is to provide a power grid equivalence method, system, device and medium for preserving new energy repeated low penetration characteristics to meet one or more of the above-mentioned requirements, so as to improve the analysis efficiency of new energy repeated low penetration characteristics while ensuring the simulation accuracy.

[0006] In order to achieve the above-mentioned purposes of the application, the following technical solutions are adopted:

[0007] In a first aspect, the present invention provides a power grid equivalent method for preserving the repeated low-voltage characteristics of renewable energy sources, comprising the following steps: S1, dividing the power grid transmission lines into graded sections starting from the renewable energy collection bus; S2, calculating the sensitivity of each line in each section to the short-circuit ratio of the renewable energy collection bus after the line is interrupted, based on the section division results of step S1; S3, determining the internal system, the external system, and the boundary nodes connecting the internal system and the external system based on the sensitivity results calculated in step S2; S4, performing equivalent grading of the external system at the boundary nodes determined in step S3 using the multi-port Thevenin equivalent method; S5, determining the final equivalent power grid based on the consistency of the renewable energy repeated low-voltage characteristics of the system before and after grading under a line break fault.

[0008] As a preferred embodiment, step S1, which involves classifying the power grid transmission lines into graded sections, specifically: defining the set of lines directly connected to the new energy collection bus as the first-level section, defining the new energy collection bus as the starting point of the first-level section, and defining all nodes at opposite ends of the lines in the first-level section as the ending point of the first-level section; and so on. s The end point of the first section is taken as the first s Starting from the +1 level section, search for lines connected to the starting point, excluding nodes at the opposite end as the first... s The set of remaining routes consisting of lines starting or ending at a section of level 1 or lower is defined as the first set. s +1 level cross section, in which all line-to-line nodes are defined as the +1 level cross section. s The endpoint of the +1 level section; among which, s The integer is greater than or equal to 1, and so on, until the cross-section of the entire power grid is completed.

[0009] As a preferred approach, in step S2, the sensitivity of each line in each section is obtained based on the difference in the short-circuit ratio of the new energy collection bus before and after the interruption; the larger the sensitivity value, the greater the impact of the interruption of this line on the short-circuit ratio of the new energy collection bus.

[0010] As a preferred embodiment, step S3, which involves determining the internal system, the external system, and the boundary nodes connecting the internal and external systems, specifically includes: [The text abruptly ends here, likely due to an incomplete sentence or missing information.] s The sensitivity of each line in the first-level section after disconnection is compared with the preset sensitivity threshold value; if the first-level section is disconnected... s If the sensitivity of all lines in the first-level section is less than the preset sensitivity threshold value, then the first-level section will be used. s The set of level-1 cross-section lines is used as a cut-set partitioning system to divide the level-1 cross-section lines. sThe end points of all lines in the sectional collection are determined as boundary nodes; the system from the new energy station to the new energy collection bus and from the new energy collection bus to the boundary nodes is divided into an internal system, and the system outside the boundary nodes is divided into an external system.

[0011] As a preferred solution, the external system is equivalenced by the multi-port Thevenin equivalent method in step S4, specifically: all the boundary nodes are numbered to obtain a boundary node set; a boundary node association matrix is established based on the boundary node set; an equivalent impedance matrix and an equivalent electromotive force vector of the external system are solved based on the impedance matrix and the node voltage matrix of the system before equivalence, so as to equivalencethe external system into a series model of equivalent electromotive force and equivalent impedance connected with each boundary node.

[0012] As a preferred solution, the final equivalent power grid is determined in step S5, including steps: S51, performing electromagnetic transient simulation modeling on the internal system, so as to obtain the system after equivalence; S52, in the original system before equivalence, respectively performing line breaking fault simulation on each line in each sectional surface, and counting the total number of new energy stations entering repeated low penetration state after each line breaking fault and the set thereof ; S53, in the system after equivalence, repeating the line breaking fault simulation of sub-step S52, and obtaining the corresponding total number of new energy stations after equivalence and the set thereof ; S54, comparing the statistical results before and after equivalence, if for the line breaking fault of all simulated lines and , the current equivalent system is determined as the final equivalent power grid; S55, if and are not met, the preset sensitivity threshold is reduced, and step S3 is returned to be re-executed until the conditions are met.

[0013] In a second aspect, the present application provides a power grid equivalent system for preserving the repeated low-pass characteristics of new energy, which is used to implement the power grid equivalent method as described in the first aspect, and comprises: a section division module, configured to divide the power transmission lines in the power grid into hierarchical sections starting from a new energy collection bus in the power grid; a sensitivity calculation module, configured to calculate the sensitivity of each power transmission line in each section to the short-circuit ratio of the new energy collection bus after the line is opened; a system determination module, configured to determine an internal system, an external system, and a boundary node connecting the internal system and the external system based on the calculated sensitivity results; an equivalent calculation module, configured to equivalently calculate the external system at the boundary node by using a multi-port Thevenin equivalent method; and an equivalent grid determination module, configured to determine a final equivalent grid according to the consistency of the repeated low-pass characteristics of new energy in the system before and after the equivalent under the line outage fault.

[0014] As a preferred solution, the equivalent grid determination module comprises a verification unit configured to perform the following verification operation: in the original system before the equivalent and the system after the equivalent, respectively simulate the line outage fault of each power transmission line in each section and count the repeated low-pass characteristics of new energy; compare whether the two counting results are completely consistent; if not, trigger the system determination module and the equivalent calculation module to determine the internal system, the external system, the boundary node and perform the equivalent calculation again with the adjusted parameters.

[0015] In a third aspect, the present application provides an electronic device, which comprises a memory, a processor, and a computer program, and the computer program is executed by the processor to implement the power grid equivalent method as described in the first aspect.

[0016] In a fourth aspect, the present application provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the power grid equivalent method as described in the first aspect.

[0017] Compared with the prior art, the present application has the following beneficial effects:

[0018] 1. The present application adopts a unique process of "from near to far, hierarchical screening, and precise equivalent". Starting from the new energy collection point, the power grid lines are divided into sections level by level. This way from near to far can clearly define the research scope, making the analysis more hierarchical and targeted. By calculating the sensitivity of line opening to short-circuit ratio, a key indicator, hierarchical screening can accurately measure the impact of remote grid faults on the core research area (new energy collection bus), avoiding the problems of ambiguous analysis range and lack of focus in traditional methods, and laying a solid foundation for subsequent precise equivalent.

[0019] 2. In the precise equivalence step, this invention simplifies external systems with less impact using a multi-port Thevenin equivalent model based on the results of hierarchical screening. This effectively reduces the complexity of the power grid and improves computational efficiency. For internal systems with greater impact, however, their detailed models are retained, ensuring the accuracy and completeness of key components. This differentiated equivalence strategy, compared to the uniform simplification or oversimplification methods of traditional techniques, can preserve the key characteristics of the power grid to the greatest extent while ensuring computational efficiency. This makes the equivalent power grid closer to reality, providing a reliable basis for subsequent analysis and research.

[0020] 3. This invention introduces a cause-and-effect verification mechanism, using the exact number and set of renewable energy power stations experiencing repeated low-voltage crossings before and after the equivalent grid connection failure as a standard to verify the correctness of the equivalent grid results. This standard is directly related to the operational performance of renewable energy power stations under actual fault conditions, and can intuitively reflect the degree to which the equivalent grid reflects the characteristics of the actual power grid. If the verification results are inconsistent, the parameters are adjusted and the equivalent grid is re-equivalent until they are completely consistent, ensuring the accuracy and reliability of the equivalent results, effectively avoiding analytical errors caused by inaccurate equivalence, and providing a strong guarantee for the safe and stable operation of the power grid.

[0021] In summary, this invention, through its scientific and reasonable equivalence process, precise equivalence strategy, and rigorous verification standards, has significant advantages in improving the relevance of analysis, ensuring the accuracy of equivalence, and guaranteeing the reliability of results. It provides more effective methods and tools for the research and analysis of high-proportion renewable energy power grids.

[0022] Further or more detailed beneficial effects will be described in conjunction with specific embodiments in the detailed implementation. Attached Figure Description

[0023] 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.

[0024] Figure 1 This is a flowchart illustrating the power grid equivalence method provided in an embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of the structure of the power grid equivalent system provided in an embodiment of the present invention.

[0026] Figure 3 This is a structural diagram of the electronic device provided in the embodiment of the present invention.

[0027] Icon labels:

[0028] 300. Electronic devices;

[0029] 301. Processor; 302. Communication bus; 303. User interface; 304. Network interface; 305. Memory. Detailed Implementation

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] The power grid equivalent method described in the embodiments of this specification is applied to the analysis, planning, and operation control process of high-proportion renewable energy access to the power grid. In these scenarios, the application of the power grid equivalent method aims to accurately grasp the characteristics of the power grid, improve the efficiency and accuracy of the analysis of the repeated low-voltage oscillation characteristics of renewable energy, ensure the safe and stable operation of the power grid, and at the same time reduce the computational complexity and improve the efficiency and feasibility of the research work.

[0035] The following is a brief explanation of the new energy collection bus, hierarchical cross-section division, short-circuit ratio sensitivity, boundary nodes, multi-port Thevenin equivalent method, electromagnetic transient simulation modeling, and equivalent power grid involved in several embodiments of this specification:

[0036] A renewable energy aggregation bus refers to the point where electricity generated by numerous renewable energy power generation devices (such as wind turbines and photovoltaic arrays) is collected in areas with a high proportion of renewable energy connected to the power grid. Through the renewable energy aggregation bus, dispersed renewable energy can be concentrated and then transmitted to the main power grid, facilitating unified management and dispatch. It occupies a critical position in the power grid structure, and its operational status has a significant impact on the stability of the entire renewable energy integration area's power grid.

[0037] The hierarchical cross-section division in this invention refers to dividing the power grid into levels of cross-sections, starting from the renewable energy collection bus, much like peeling an onion. This division method helps to clearly define the degree of influence of different regions on the core research area (renewable energy collection point). By dividing the power grid into different levels of cross-sections according to the distance from the renewable energy collection point, subsequent analysis can be more targeted, allowing for a gradual and in-depth study of the power grid characteristics from the local to the overall perspective.

[0038] The sensitivity of the short-circuit ratio is a key metric for measuring the impact of remote power grid faults on the core research area (new energy aggregation point). This invention, by calculating the sensitivity of the short-circuit ratio to line interruptions, can quantitatively analyze the degree of change in the short-circuit ratio under different line interruption conditions, thereby determining the magnitude of the impact of the line interruption on the new energy aggregation point. This provides a crucial basis for hierarchical screening, helping to determine which areas have a smaller impact on the core area and which have a larger impact.

[0039] Boundary nodes are key nodes in the power grid equivalence process that divide the internal system (the part retaining the detailed model) and the external system (the part undergoing equivalence simplification). They clarify the scope and limits of the equivalence, ensuring that the internal system accurately reflects the characteristics of the core research area, while the external system is simplified through appropriate equivalence methods to reduce computational load. The proper selection of boundary nodes is crucial to the accuracy of the equivalence results.

[0040] The multi-port Thevenin equivalent method can transform a complex external power grid into a Thevenin equivalent circuit with multiple ports, including equivalent voltage sources and equivalent impedances. In this way, the external system can be greatly simplified and the computational complexity reduced while preserving the key influence of the external system on the internal system. At the same time, it can ensure that the equivalent power grid can accurately reflect the electrical characteristics of the external system on the internal system.

[0041] Electromagnetic transient simulation modeling involves power equipment such as new energy generating units and transmission lines. By establishing an accurate electromagnetic transient simulation model, the dynamic response of the power grid under various fault conditions (such as line breakage faults) can be simulated, and the operating characteristics of new energy power plants under these conditions, such as repeated low-voltage ride-through, can be accurately analyzed, providing theoretical basis and analytical means for the safe and stable operation of the power grid.

[0042] The equivalent power grid refers to the present invention, which, while retaining the detailed model of the core research area, reasonably simplifies the external system. It can reflect the key characteristics of the actual power grid, while having low computational complexity, making it convenient for large-scale power grid analysis and research, such as analyzing the impact of new energy access on the power grid and evaluating the stability of the power grid. At the same time, the "effect-to-cause" verification mechanism ensures the consistency of the equivalent power grid with the actual power grid in key characteristics.

[0043] Example 1:

[0044] like Figure 1 As shown, this embodiment provides a power grid equivalent method to preserve the repeated low-voltage ride characteristics of renewable energy sources, including the following steps: S1, dividing the power grid transmission lines into graded sections starting from the renewable energy collection bus; S2, based on the section division results of step S1, calculating the sensitivity of each line in each section to the short-circuit ratio of the renewable energy collection bus after the line is interrupted; S3, based on the sensitivity results calculated in step S2, determining the internal system, the external system, and the boundary nodes connecting the internal system and the external system; S4, at the boundary nodes determined in step S3, performing equivalent evaluation of the external system using the multi-port Thevenin equivalent method; S5, determining the final equivalent power grid based on the consistency of the renewable energy repeated low-voltage ride characteristics of the system before and after the equivalent evaluation under the fault of line interruption.

[0045] Specifically, step S1, which involves dividing the power grid transmission lines into graded sections, includes: defining the set of lines directly connected to the new energy collection bus as the first-level section; defining the new energy collection bus as the starting point of the first-level section; and defining the nodes at the opposite ends of all lines in the first-level section as the ending points of the first-level section; and so on. s The end point of the first section is taken as the first s Starting from the +1 level section, search for lines connected to the starting point, excluding nodes at the opposite end as the first... s The set of remaining routes consisting of lines starting or ending at a section of level 1 or lower is defined as the first set. s +1 level cross section, in which all line-to-line nodes are defined as the +1 level cross section. s The endpoint of the +1 level section; among which, s The integer is greater than or equal to 1, and so on, until the cross-section of the entire power grid is completed.

[0046] Specifically, in step S2, based on the difference in the short-circuit ratio of the new energy collection bus before and after the interruption, the sensitivity of each line in each section is obtained; the larger the sensitivity value, the greater the impact of the interruption of this line on the short-circuit ratio of the new energy collection bus. More specifically, the formula for calculating the sensitivity is as follows:

[0047] (1)

[0048] In equation (1), Indicates the first s The first section of the first class i The sensitivity of each line, The short-circuit ratio of the new energy collection bus before the line is disconnected. For the first s The first section of the first class i The short-circuit ratio of the new energy collection bus after the line is disconnected.

[0049] Specifically, step S3, which involves determining the internal system, the external system, and the boundary node connecting the internal system and the external system, specifically: [The text abruptly ends here, likely due to an incomplete sentence or a formatting error.] s The sensitivity of each line in the first-level section after disconnection is compared with the preset sensitivity threshold value; if the first-level section is disconnected... s If the sensitivity of all lines in the first-level section is less than the preset sensitivity threshold value, then the first-level section will be used. s The set of level-1 cross-section lines is used as a cut-set partitioning system to divide the level-1 cross-section lines. s The endpoints of all lines in the set of cross-sections are determined as boundary nodes; the system from the new energy power station to the new energy collection bus, and the system from the new energy collection bus to the boundary node are classified as internal systems, and the system outside the boundary node is classified as external systems.

[0050] Specifically, step S4 involves equivalencing the external system using the multi-port Thevenin equivalence method, which includes: numbering all the boundary nodes to obtain a boundary node set; establishing a boundary node correlation matrix based on the boundary node set; and solving for the equivalent impedance matrix and equivalent electromotive force vector of the external system based on the impedance matrix and node voltage matrix of the system before equivalence, thereby equivalencing the external system to a series model of equivalent electromotive force and equivalent impedance connected to each of the boundary nodes.

[0051] More specifically, the expression for the set of boundary nodes is:

[0052] (2)

[0053] In equation (2), This represents the total number of boundary nodes;

[0054] The expression for the boundary node correlation matrix is ​​as follows:

[0055] (3)

[0056] In equation (3), Indicates the first j The correlation matrix of each port is composed of boundary nodes. b k and bl Composition, where 1 and -1 are respectively the first and second digits of the first digit. k and the l The value of the column;

[0057] The formulas for calculating the equivalent impedance matrix and equivalent electromotive force vector of the external system are as follows:

[0058] (4)

[0059] In equation (4), The impedance matrix of the system before equivalence is given. This is the node voltage matrix of the system before the equivalent values ​​are calculated.

[0060] Specifically, step S5, determining the final equivalent power grid, includes the following steps: S51, performing detailed electromagnetic transient simulation modeling on the internal system (it should be noted that any feasible method in the existing technology can be used to complete the electromagnetic transient simulation modeling), thereby obtaining the equivalent system; S52, in the original system before equivalence, performing line break fault simulation on each line in each level section, and counting the total number of new energy power stations that enter repeated low-voltage crossing state after each line break fault. and its set , S53. In the equivalent system, repeat the disconnection fault simulation in sub-step S52 to obtain the total number of new energy power stations corresponding to the equivalent system. and its set S54. Compare the statistical results before and after the equivalent value. If the open circuit fault of all simulated lines satisfies the following conditions... and If so, the current equivalent system will be determined as the final equivalent power grid; S55, if not satisfied and If the preset sensitivity threshold is lowered, the process returns to step S3 and repeats until the condition is met.

[0061] Example 2:

[0062] like Figure 2As shown, this embodiment provides a power grid equivalent system that preserves the repeated low-voltage characteristics of renewable energy sources, used to implement the power grid equivalent method as described in the first aspect. It includes: a cross-section division module, used to divide the power grid transmission lines into graded cross-sections starting from the renewable energy collection bus in the power grid; a sensitivity calculation module, used to calculate the sensitivity of each transmission line in each cross-section to the short-circuit ratio of the renewable energy collection bus after the line is broken; a system determination module, used to determine the internal system, the external system, and the boundary nodes connecting the internal and external systems based on the calculated sensitivity results; an equivalent calculation module, used to perform equivalent calculation on the external system at the boundary nodes using the multi-port Thevenin equivalent method; and an equivalent power grid determination module, used to determine the final equivalent power grid based on the consistency of the renewable energy repeated low-voltage characteristics of the system before and after the equivalent calculation under a line break fault.

[0063] Specifically, this embodiment provides a preferred implementation, wherein the equivalent power grid determination module includes a verification unit for performing the following verification operations: in the original system before equivalence and in the system after equivalence, simulations of line breakage faults are performed on each transmission line in each level section, and the repeated low-voltage transmission of new energy sources is statistically analyzed; the statistical results of the two sets of data are compared to see if they are completely consistent; if they are inconsistent, the system determination module and the equivalent calculation module are triggered to redetermine the internal system, external system, and boundary nodes with the adjusted parameters and perform equivalent calculations.

[0064] Example 3:

[0065] 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.

[0066] The communication bus can be used to enable communication between the various components mentioned above.

[0067] The user interface may include buttons, and optional user interfaces may also include standard wired interfaces and wireless interfaces.

[0068] The network interface may include, but is not limited to, Bluetooth modules, NFC modules, Wi-Fi modules, etc.

[0069] 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.

[0070] 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 equivalent application programs. The processor can be used to call the equivalent application programs stored in the memory and execute the steps of the power grid equivalence method mentioned in the foregoing embodiments.

[0071] Example 4:

[0072] 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.

[0073] 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)).

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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 power grid equivalent method for preserving the repeated low-voltage characteristics of renewable energy sources, characterized in that, Including the following steps: S1. Starting from the new energy collection bus, the power grid transmission lines are divided into graded sections. S2. Based on the cross-section division results of step S1, calculate the sensitivity of each line in each cross-section to the short-circuit ratio of the new energy collection bus after the line is broken. S3. Based on the sensitivity results calculated in step S2, determine the internal system, the external system, and the boundary nodes connecting the internal system and the external system. S4. The external system is equivalent to the boundary nodes determined in step S3 using the multi-port Thevenin equivalent method. Step S4, which involves equivalencing the external system using the multi-port Thevenin equivalence method, specifically includes: Number all the boundary nodes to obtain a boundary node set; Establish a boundary node association matrix based on the aforementioned set of boundary nodes; Based on the impedance matrix and node voltage matrix of the equivalent system, the equivalent impedance matrix and equivalent electromotive force vector of the external system are obtained by solving, thereby making the external system equivalent to a series model of equivalent electromotive force and equivalent impedance connected to each of the boundary nodes. S5. Based on the consistency of the system before and after the equivalent grid in the repeated low-voltage transmission of new energy sources under the fault of line disconnection, determine the final equivalent grid. Step S5, which involves determining the final equivalent power grid, includes the following steps: S51. Perform electromagnetic transient simulation modeling on the internal system to obtain the equivalent system; S52. In the original system before equivalence, simulate line breakage faults for each line in each level of cross-section, and count the total number of new energy power stations that enter repeated low-voltage crossing state after each line breakage fault. and its set ; S53. In the equivalent system, repeat the disconnection fault simulation in sub-step S52, and count the total number of new energy power stations corresponding to the equivalent system. and its set ; S54. Compare the statistical results before and after the equivalent value. If for all simulated line open circuit faults, the following conditions are met... and If so, the current equivalent system will be determined as the final equivalent power grid; S55, if not satisfied and If the preset sensitivity threshold is lowered, the process returns to step S3 and repeats until the condition is met.

2. The power grid equivalent method for preserving the repeated low-voltage characteristics of new energy sources according to claim 1, characterized in that, Step S1, which involves classifying the transmission lines of the power grid into graded sections, specifically includes: The set of lines directly connected to the new energy collection bus is defined as the first-level section, the new energy collection bus is defined as the starting point of the first-level section, and the nodes at the opposite ends of all lines in the first-level section are defined as the ending point of the first-level section. With the first s The end point of the first section is taken as the first s Starting from the +1 level section, search for lines connected to the starting point, excluding nodes at the opposite end as the first... s The set of remaining routes consisting of lines starting or ending at a section of level 1 or lower is defined as the first set. s +1 level cross section, in which all line-to-line nodes are defined as the +1 level cross section. s The end point of the +1 level section; in, s The integer is greater than or equal to 1, and so on, until the cross-section of the entire power grid is completed.

3. The power grid equivalent method for preserving the repeated low-voltage characteristics of new energy sources according to claim 2, characterized in that: In step S2, the sensitivity of each line in each level section is obtained based on the difference in short-circuit ratio of the new energy collection bus before and after the interruption. The higher the sensitivity value, the greater the impact of the line interruption on the short-circuit ratio of the new energy collection bus.

4. The power grid equivalent method for preserving the repeated low-voltage characteristics of new energy sources according to claim 3, characterized in that, Step S3, which involves determining the internal system, the external system, and the boundary nodes connecting the internal system and the external system, specifically includes: The first s The sensitivity of each line in the cross section after disconnection is compared with the preset sensitivity threshold value; If the first s If the sensitivity of all lines in the first-level section is less than the preset sensitivity threshold value, then the first-level section will be used. s The set of level-1 cross-section lines is used as a cut-set partitioning system to divide the level-1 cross-section lines. s The endpoints of all lines in the set of cross-sections are determined as boundary nodes; The system from the new energy power station to the new energy collection bus, and the system from the new energy collection bus to the boundary node are classified as the internal system, and the system outside the boundary node is classified as the external system.

5. A power grid equivalent system that preserves the repeated low-voltage characteristics of renewable energy sources, characterized in that, For implementing the power grid equivalence method as described in any one of claims 1 to 4, comprising: The cross-section division module is used to divide the power grid transmission lines into hierarchical cross-sections, starting from the new energy gathering bus in the power grid. The sensitivity calculation module is used to calculate the sensitivity of the short-circuit ratio of the new energy collection bus after each transmission line in each cross-section is broken. The system determination module is used to determine the internal system, the external system, and the boundary nodes connecting the internal system and the external system based on the calculated sensitivity results. The equivalent calculation module is used to perform equivalent calculations on the external system at the boundary nodes using the multi-port Thevenin equivalent method. The equivalent grid determination module is used to determine the final equivalent grid based on the consistency of the system before and after equivalence in the repeated low-voltage ride-through of new energy sources under line failure.

6. A power grid equivalent system for preserving the repeated low-voltage characteristics of renewable energy sources according to claim 5, characterized in that, The equivalent power grid determination module includes a verification unit for performing the following verification operations: In the original system before and after the equivalence, the line breakage fault simulation was carried out for each transmission line in each level section, and the repeated low-voltage transmission of new energy was statistically analyzed. Compare whether the two statistical results are completely consistent; If there is a discrepancy, the system determination module and the equivalent calculation module are triggered to redetermine the internal system, external system, and boundary nodes with the adjusted parameters and perform equivalent calculations.

7. 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 power grid equivalence method as described in any one of claims 1 to 4.

8. 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 power grid equivalence method as described in any one of claims 1 to 4.

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