Method for evaluating and designing inertia adjustable capability of power system, and system

Abstract

The present invention relates to the field of operation status monitoring and safety evaluation of power systems, and particularly to a method for evaluating and designing inertia adjustable capability of a power system, and a system. Disclosed in the present invention are a novel method for evaluating and designing inertia adjustable capability of a power system, and a terminal device. On the basis of obtained basic data of a power system, a system minimum inertia requirement when the system satisfies a frequency stability constraint, the system actual inertia level, and the maximum inertia level that the system can obtain are calculated. Then, a mechanism for evaluating the inertia adjustable capacity of a power system is constructed, and criteria for designing the inertia adjustable capacity of a power system in different scenarios are clarified. The present invention can assist and guide power grid-related personnel in formulating / to formulate reasonable power startup modes and inertia compensation and regulation measures, improve the inertia safety level of power systems under the background of large-scale new energy access, and provide strong inertia support for large-scale new energy acceptance.

Description

A method and system for evaluating and designing the adjustable inertia capability of a power system Technical Field

[0001] The present invention belongs to the field of power system operation status monitoring and safety evaluation, and in particular relates to a power system inertia adjustable capability evaluation and design method and system. Background Art

[0002] With the commissioning of numerous new energy projects and DC (direct current) projects, the installed capacity of asynchronous power sources within the power system continues to increase. However, under conventional control, asynchronous power sources cannot actively provide inertia support to the system, resulting in a significant decrease in system rotational inertia and a consequent weakening of the system's frequency support capability. This significantly increases the risk of triggering high-frequency generator shedding and low-frequency load shedding in the event of high-power disturbances such as DC blocking or grid disconnection of new energy clusters. Furthermore, with the large-scale commissioning of new energy sources, the fluctuation characteristics of system inertia will increase significantly. According to relevant energy transition plans and my country's "dual carbon" goals, the dominance of asynchronous power generation will become increasingly prominent in the future, further exacerbating the "low inertia" and "variable inertia" characteristics and operational complexity of the power grid. Therefore, the rational design of the power system's inertia adjustability has become a key issue that needs to be addressed in the context of the "dual carbon" goals and the construction of new power systems, and holds significant research value.

[0003] Current issues related to inertia in new power systems primarily focus on inertia demand and inertia level assessment. However, there is a lack of inertia adjustability assessment and design criteria for system operation and planning. As a result, the coupling relationship between the prominent "low inertia" and "variable inertia" issues and system frequency stability is still not fully considered in grid planning and operation. This inability to truly reflect the actual inertia adjustability of new power systems and the requirements for inertia adjustability configuration is insufficient, making it difficult to provide a reference for selecting control methods for traditional synchronous unit startup and renewable energy grid-connected converters under the massive operation of new power systems. Therefore, it is necessary to fully consider the intertwined coupling relationship between system inertia and system frequency stability. Based on the inertia demand under the constraints of system frequency stability, the design criteria for system inertia adjustability under different disturbance scales should be clarified. This will provide a reference for system planning and operation personnel to take preventive measures in advance, avoid triggering low-frequency load shedding, high-frequency generator tripping, and even system disconnection under large-capacity active power surges, and maximize the system's renewable energy absorption capacity.

[0004] Summary of the Invention

[0005] In view of the above-mentioned problems, the present invention is proposed.

[0006] Therefore, the technical problem solved by the present invention is: how to provide a method and terminal equipment for evaluating and designing the adjustable inertia capability of a power system, determine the level of the adjustable inertia capability of the system, determine the design criteria for the adjustable inertia capability of the power system under different fault scenarios, and ensure the inertia safety of the power system.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solutions: a method for evaluating and designing the inertia adjustability of a power system, comprising: collecting basic power system data, including the system load level, the rated capacity, kinetic energy and operating status of various types of generator sets, the system frequency regulation capability and the system frequency control strategy; and using theoretical calculations to obtain the system inertia level and the system inertia requirement under different expected disturbance scales, in combination with the system inertia requirement and the system frequency safety index limit requirements; grading the power system inertia adjustability based on the obtained system inertia level and inertia requirement, in combination with the foreseeable fault scale of the system, constructing an inertia adjustability calculation index, and generating design criteria for the system inertia adjustability under different fault scenarios.

[0008] As a preferred solution of the method for evaluating and designing the adjustable inertia capability of a power system according to the present invention, the system inertia demand and the system frequency safety index limit requirements include the power system inertia level H sys Expressed as:

[0009] Where n and m represent the number of synchronous units in the system and the number of new energy units with simulated inertia control, respectively; H s,i represents the inertia of the i-th synchronous unit; H v,j represents the simulated inertia size of the jth new energy unit with simulated inertia control; x i Indicates the operating status of the i-th synchronous unit; y j Indicates the operating status of the j-th new energy unit.

[0010] As a preferred solution of the method for evaluating and designing the adjustable inertia capability of a power system described in the present invention, the system inertia requirement and the system frequency safety index limitation requirements also include the system inertia requirement H under system N-1 fault. sc,1 Expressed as:

[0011] Where ΔP N-1 Indicates the scale of system N-1 failure; Indicates the safety limit of the frequency change rate corresponding to the system N-1 fault; Δf sc1 It represents the maximum frequency deviation safety limit corresponding to the system N-1 fault; α1 and β1 are the frequency safety factors corresponding to the system N-1 fault; R sysIndicates the system frequency modulation rate; f d Indicates the system frequency modulation dead zone; D sys represents the equivalent damping of the system; t s It represents the system's primary frequency modulation delay time; f0 represents the system's rated frequency; ln represents the logarithm of the natural logarithm with the constant e as the base.

[0012] As a preferred solution of the method for evaluating and designing the adjustable inertia capability of a power system described in the present invention, the system inertia requirement and the system frequency safety index limit requirements also include the system inertia requirement H under system N-2 fault. sc,2 Expressed as:

[0013] Where ΔP N-2 Indicates the scale of system N-2 failure; Indicates the safety limit of the frequency change rate corresponding to the system N-2 fault; Δf sc2 It represents the maximum frequency deviation safety limit corresponding to the system N-2 fault; α2 and β2 are the frequency safety factors corresponding to the system N-2 fault; R sys Indicates the system frequency modulation rate; D sys Indicates the system frequency modulation dead zone; ΔP c Indicates the system emergency frequency control quantity; t c Indicates the system emergency frequency control delay time; t s It represents the system's primary frequency modulation delay time; f0 represents the system's rated frequency; ln represents the logarithm of the natural logarithm with the constant e as the base.

[0014] As a preferred embodiment of the method for evaluating and designing the inertia adjustability of a power system described in the present invention, the grading of the inertia adjustability of the power system includes dividing the inertia adjustability of the power system into a first-level adjustability and a second-level adjustability according to the foreseeable fault scale of the system, wherein the first-level adjustability corresponds to N-1 faults and the second-level adjustability corresponds to N-2 faults.

[0015] As a preferred solution of the method for evaluating and designing the adjustable inertia capability of a power system according to the present invention, the first-level adjustable capability coefficient K R,1 Expressed as:

[0016] Among them, H max Indicates the maximum inertia level that the power system can obtain; H sc,1 It represents the inertia requirement corresponding to the N-1 fault in the power system, H sys Indicates the current inertia level of the power system.

[0017] The secondary adjustable capacity coefficient KR,2 Expressed as:

[0018] Among them, H max Indicates the maximum inertia level that the power system can obtain; H sc,2 It represents the inertia requirement corresponding to the power system N-2 fault, H sys Indicates the current inertia level of the power system.

[0019] As a preferred embodiment of the method for evaluating and designing the inertia adjustability of a power system according to the present invention, the design criteria for the system inertia adjustability under different fault scenarios include: under the N-1 fault scenario, the first-level inertia adjustability of the power system is designed to meet the following requirements:

[0020] Where ΔH TZ,1 is the maximum inertia loss corresponding to the system N-1 accident, ΔH TW is the maximum fluctuation range of the system inertia level under normal operation; γ is the safety margin coefficient of the system inertia adjustable capacity;

[0021] It should be noted that when the system's first-level inertia adjustable capacity coefficient K R,1 When the above formula is satisfied, the system's first-level inertia adjustable capacity is sufficient; otherwise, it is insufficient and measures should be taken to increase the system's adjustable inertia resources.

[0022] In the N-2 fault scenario, the power system's secondary inertia adjustability is designed to meet the following requirements:

[0023] Where ΔH TZ,2 is the maximum inertia loss corresponding to the system N-2 accident, ΔH TW is the maximum fluctuation range of the system inertia level under normal operation; γ is the safety margin coefficient of the system inertia adjustable capacity.

[0024] It should be noted that when the system secondary inertia adjustable capacity coefficient K R,2 When the above formula is satisfied, the system's secondary inertia adjustable capacity is sufficient; otherwise, it is insufficient and measures should be taken to increase the system's adjustable inertia resources.

[0025] Another object of the present invention is to provide a power system inertia adjustability evaluation and design system, which can solve the technical problem of how to effectively evaluate and design the inertia adjustability of the power system through a data acquisition module, an inertia demand calculation module, an inertia adjustability grading module and an index calculation module.

[0026] To solve the above technical problems, the present invention provides the following technical solutions: a power system inertia adjustability evaluation and design system, comprising a data acquisition module, an inertia demand calculation module, an inertia adjustability classification module and an index calculation module;

[0027] The data acquisition module is used to collect basic data of the power system, including system load level, rated capacity, kinetic energy and operating status of various types of generator sets, system frequency regulation capability and system frequency control strategy;

[0028] The inertia demand calculation module is used to obtain the system inertia level and the system inertia demand under different disturbance scales by theoretical calculation based on the collected data and the requirements of the system frequency safety index limit;

[0029] The inertia adjustable capability grading module is used to grade the inertia adjustable capability of the power system according to the system inertia level and inertia demand, combined with the expected fault scale of the system;

[0030] The index calculation module is used to construct an inertia adjustability calculation index and generate a system inertia adjustability design criterion under different fault scenarios.

[0031] A computer device includes a memory and a processor, wherein the memory stores a computer program, and is characterized in that when the processor executes the computer program, it implements the steps of a method for evaluating and designing the adjustable inertia capability of a power system.

[0032] A computer-readable storage medium stores a computer program thereon, wherein when the computer program is executed by a processor, the computer program implements the steps of a method for evaluating and designing the adjustable inertia capability of a power system.

[0033] The beneficial effects of the present invention are as follows: at the grid planning level, the present invention combines the system inertia safety constraints to clarify the inertia adjustable capacity criteria of the new power system, which can provide a reference for the power supply planning and new energy access planning of the grid planning department, and assist in determining the future system's new energy safety access ratio and control method, load level, DC transmission level and power supply structure; at the dispatching and operation level, the present invention can assist grid operation and dispatching personnel in understanding the system's inertia adjustable capacity status under different operating scenarios, realize inertia safety monitoring under complex and changeable system operating modes, and provide a basis for refined inertia control, and enhance the grid's ability to resist large-capacity active power shocks (such as DC blocking and new energy grid disconnection) by formulating prevention and emergency control strategies. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them:

[0035] FIG1 is a flow chart of a method for evaluating and designing the adjustable inertia capability of a power system provided by an embodiment of the present invention.

[0036] FIG2 is a schematic diagram of a modified 39-bus New England system topology structure in an example simulation of a method for evaluating and designing the adjustable inertia capability of a power system provided by an embodiment of the present invention.

[0037] FIG3 is a system frequency response curve under C1 and C2 fault scenarios in a simulation of an inventive example of a method for evaluating and designing the adjustable inertia capability of a power system provided by an embodiment of the present invention.

[0038] FIG4 is a schematic structural diagram of a power system inertia adjustable capability evaluation and design system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0039] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is given in conjunction with the accompanying drawings. It is obvious that the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in this field without creative work should fall within the scope of protection of the present invention.

[0040] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0041] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0042] The present invention is described in detail with reference to schematic diagrams. For ease of illustration, cross-sectional views of device structures may be partially enlarged and not to scale when describing embodiments of the present invention. Furthermore, the schematic diagrams are merely illustrative and should not limit the scope of the present invention. Furthermore, in actual production, the three-dimensional dimensions of length, width, and depth should be included.

[0043] In the description of the present invention, it should be noted that the terms "upper, lower, inner, and outer" and other references to orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first, second, or third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0044] In this disclosure, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be interpreted broadly. For example, they may refer to fixed, removable, or integral connections. They may also refer to mechanical, electrical, or direct connections, indirect connections through an intermediary, or internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in this disclosure.

[0045] Example 1

[0046] 1 , which shows an embodiment of the present invention, provides a method for evaluating and designing the adjustable inertia capability of a power system, including:

[0047] S1: Collect basic data of the power system, including system load level, rated capacity, kinetic energy and operating status of various types of generator sets, system frequency regulation capability and system frequency control strategy. Combined with the system inertia requirements and the system frequency safety index limit requirements, theoretical calculation is used to obtain the system inertia level and the system inertia requirements under different expected disturbance scales;

[0048] Furthermore, the system inertia demand and system frequency security index limit requirements include the power system inertia level H sys Expressed as:

[0049] Where n and m represent the number of synchronous units in the system and the number of new energy units with simulated inertia control, respectively; H s,i represents the inertia of the i-th synchronous unit; H v,j represents the simulated inertia size of the jth new energy unit with simulated inertia control; x i Indicates the operating status of the i-th synchronous unit; y jIndicates the operating status of the j-th new energy unit.

[0050] Furthermore, the system inertia requirement and system frequency safety index limit requirements also include the system inertia requirement H under system N-1 fault sc,1 Expressed as:

[0051] Where ΔP N-1 Indicates the scale of system N-1 failure; Indicates the safety limit of the frequency change rate corresponding to the system N-1 fault; Δf sc1 It represents the maximum frequency deviation safety limit corresponding to the system N-1 fault; α1 and β1 are the frequency safety factors corresponding to the system N-1 fault; R sys Indicates the system frequency modulation rate; f d Indicates the system frequency modulation dead zone; D sys represents the equivalent damping of the system; t s It represents the system's primary frequency modulation delay time; f0 represents the system's rated frequency; ln represents the logarithm of the natural logarithm with the constant e as the base.

[0052] Furthermore, the system inertia requirement and system frequency safety index limit requirements also include the system inertia requirement H under system N-2 fault sc,2 Expressed as:

[0053] Where ΔP N-2 Indicates the scale of system N-2 failure; Indicates the safety limit of the frequency change rate corresponding to the system N-2 fault; Δf sc2 It represents the maximum frequency deviation safety limit corresponding to the system N-2 fault; α2 and β2 are the frequency safety factors corresponding to the system N-2 fault; R sys Indicates the system frequency modulation rate; D sys Indicates the system frequency modulation dead zone; ΔP c Indicates the system emergency frequency control quantity; t c Indicates the system emergency frequency control delay time; t s It represents the system's primary frequency modulation delay time; f0 represents the system's rated frequency; ln represents the logarithm of the natural logarithm with the constant e as the base.

[0054] S2: Based on the obtained system inertia level and inertia demand, combined with the foreseeable fault scale of the system, the power system inertia adjustability is classified, an inertia adjustability calculation index is constructed, and the design criteria for the system inertia adjustability under different fault scenarios are generated.

[0055] Furthermore, the grading of the power system inertia adjustability includes dividing the power system inertia adjustability level into first-level adjustability and second-level adjustability according to the foreseeable fault scale of the system, wherein the first-level adjustability corresponds to N-1 faults and the second-level adjustability corresponds to N-2 faults.

[0056] Furthermore, the first-level adjustable capacity coefficient K R,1 Expressed as:

[0057] Among them, H max Indicates the maximum inertia level that the power system can obtain; H sc,1 It represents the inertia requirement corresponding to the N-1 fault in the power system, H sys Indicates the current inertia level of the power system.

[0058] The secondary adjustable capacity coefficient K R,2 Expressed as:

[0059] Among them, H max Indicates the maximum inertia level that the power system can obtain; H sc,2 It represents the inertia requirement corresponding to the power system N-2 fault, H sys Indicates the current inertia level of the power system.

[0060] Furthermore, the design criteria for the system inertia adjustability under different fault scenarios include that under the N-1 fault scenario, the first-level inertia adjustability of the power system is designed to meet the following requirements:

[0061] Where ΔH TZ,1 is the maximum inertia loss corresponding to the system N-1 accident, ΔH TW is the maximum fluctuation range of the system inertia level under normal operation; γ is the safety margin coefficient of the system inertia adjustable capacity;

[0062] In the N-2 fault scenario, the power system's secondary inertia adjustability is designed to meet the following requirements:

[0063] Where ΔH TZ,2 is the maximum inertia loss corresponding to the system N-2 accident, ΔH TW is the maximum fluctuation range of the system inertia level under normal operation; γ is the safety margin coefficient of the system inertia adjustable capacity.

[0064] Example 2

[0065] The second embodiment of the present invention is different from the previous embodiment in that:

[0066] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0067] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0068] More specific examples (a non-exhaustive list) of computer-readable media include the following: an electrical connection with one or more wires (electronic devices), a portable computer disk cartridge (magnetic devices), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disc read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering, or processing in another suitable manner as necessary, and then stored in a computer memory.

[0069] It should be understood that various parts of the present invention can be implemented using hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0070] Example 3

[0071] 4 , which shows a third embodiment of the present invention, provides a power system inertia adjustable capability evaluation and design method system, including a data security exchange channel, a database isolation device, a security isolation exchange device, a platform centralized management system, and a business threat correlation analysis module;

[0072] The data security exchange channel is used to select an appropriate data exchange channel according to the type of data, structure, volume and delay requirements that need to be exchanged between the internal and external networks;

[0073] The database isolation device is used to control access to the database of the internal and external network and filter high-risk operations to protect the security of the database;

[0074] The secure isolation exchange device is used to perform strong logical isolation and information ferry exchange to protect data security;

[0075] The platform centralized management system is used to uniformly monitor and manage the operating status of all devices on the platform, and obtain the platform's operating status and security events in real time;

[0076] The business threat correlation analysis module is used to perform business threat correlation analysis on data exchange between the internal and external networks according to the data security exchange channel type, and handle abnormal data exchange behavior.

[0077] Example 4

[0078] 2-3 , a fourth embodiment of the present invention provides a method for evaluating and designing the adjustable inertia capability of a power system. To verify the beneficial effects of the present invention, scientific demonstration is performed through economic benefit calculations and experiments.

[0079] (1) Obtain basic data of the power system based on the power grid monitoring system, including system load level, rated capacity, kinetic energy and operating status of various types of generator sets, system frequency regulation capability, system interconnection line power and system frequency control strategy.

[0080] (2) Based on the basic data of the power system obtained and the operating status of each type of unit, the current inertia level H of the power system is calculated. sys for:

[0081] Where n and m represent the number of synchronous units in the system and the number of new energy units with simulated inertia control, respectively; H s,i represents the inertia of the i-th synchronous unit; H v,j represents the simulated inertia size of the jth new energy unit with simulated inertia control; x i Indicates the operating status of the i-th synchronous unit; y j Indicates the operating status of the j-th new energy unit.

[0082] (3) According to the operating status of the power system, the system N-1 fault set is constructed, and then based on the coupling relationship between the system inertia demand and the frequency security constraint index, the influence of the system primary frequency regulation is considered to obtain the system inertia demand H under N-1 fault. sc,1 for:

[0083] Where ΔP N-1 Indicates the scale of system N-1 failure; Indicates the safety limit of the frequency change rate corresponding to the system N-1 fault; Δf sc1 It represents the maximum frequency deviation safety limit corresponding to the system N-1 fault; α1 and β1 are the frequency safety factors corresponding to the system N-1 fault; R sys Indicates the system frequency modulation rate; f d Indicates the system frequency modulation dead zone; D sys represents the equivalent damping of the system; t s It represents the system's primary frequency modulation delay time; f0 represents the system's rated frequency; ln represents the logarithm of the natural logarithm with the constant e as the base.

[0084] (4) According to the operating status of the power system, the system N-2 fault set is constructed, and then based on the coupling relationship between the system inertia demand and the frequency security constraint index, and considering the influence of the system primary frequency regulation and system frequency emergency control, the system inertia demand H under N-2 fault is obtained. sc,2 for:

[0085] Where ΔP N-2 Indicates the scale of system N-2 failure; Indicates the safety limit of the frequency change rate corresponding to the system N-2 fault; Δf sc2 It represents the maximum frequency deviation safety limit corresponding to the system N-2 fault; α2 and β2 are the frequency safety factors corresponding to the system N-2 fault; Rsys Indicates the system frequency modulation rate; D sys Indicates the system frequency modulation dead zone; ΔP c Indicates the emergency frequency control quantity; t c Indicates the system emergency frequency control delay time; t s It represents the system's primary frequency modulation delay time; f0 represents the system's rated frequency; ln represents the logarithm of the natural logarithm with the constant e as the base.

[0086] (5) According to the foreseeable fault scale of the system, the power system inertia adjustability level is divided into primary inertia adjustability and secondary inertia adjustability. The primary inertia adjustability corresponds to N-1 faults, and the secondary inertia adjustability corresponds to N-2 faults.

[0087] (6) Combining the system inertia level, the inertia demand corresponding to the system N-1 fault scenario and the maximum inertia support that the system can currently obtain, the power system first-level inertia adjustable capacity coefficient K is obtained. R,1 for:

[0088] Among them, H max Indicates the maximum inertia level that the power system can obtain; H sc,1 Indicates the inertia requirement corresponding to the N-1 fault in the power system; H sys Indicates the current inertia level of the power system.

[0089] (7) Combining the system inertia level, the inertia demand corresponding to the system N-2 fault scenario and the maximum inertia support that the system can currently obtain, the power system secondary inertia adjustable capacity coefficient K is obtained. R,2 Expressed as:

[0090] Among them, H max Indicates the maximum inertia level that the power system can obtain; H sc,2 Indicates the inertia requirement corresponding to the power system N-2 fault; H sys Indicates the current inertia level of the power system.

[0091] (8) In order to ensure that the power system has sufficient available inertia resources in normal operation or fault state, from the perspective of safe inertia operation, the power system first-level inertia adjustable capacity coefficient K is calculated for the N-1 fault scenario. R,1 Should be designed to meet:

[0092] Where ΔH TZ,1 is the maximum inertia loss corresponding to the system N-1 accident, ΔH TWis the maximum fluctuation range of the inertia level of the normal operating system; γ is the safety margin coefficient of the system inertia adjustable capacity.

[0093] (9) When the system's first-level inertia adjustable capacity coefficient K R,1 When step (8) is met, the system's first-level inertia adjustable capacity is sufficient; otherwise, it is insufficient and measures should be taken to increase the system's adjustable inertia resources.

[0094] (10) In order to ensure that the power system has sufficient available inertia resources in normal operation or fault state, from the perspective of safe inertia operation, the power system secondary inertia adjustable capacity coefficient K is used for the N-2 fault scenario. R,2 Should be designed to meet:

[0095] Where ΔH TZ,2 is the maximum inertia loss corresponding to the system N-2 accident, ΔH TW is the maximum fluctuation range of the system inertia level under normal operation; γ is the safety margin coefficient of the system inertia adjustable capacity.

[0096] (11) When the system secondary inertia adjustable capacity coefficient K R,2 When step (10) is met, the system's secondary inertia adjustable capacity is sufficient; otherwise, it is insufficient and measures should be taken to increase the system's adjustable inertia resources.

[0097] As shown in Figure 1, the method of the embodiment of the present invention is used to evaluate the system inertia level in real time based on basic data such as the system load level, startup and shutdown mode, and generator set parameters. The coupling relationship between system frequency security and system inertia demand is simultaneously utilized to determine the system inertia demand under system frequency security constraints. Furthermore, based on the proposed inertia adjustability coefficient index, evaluation and design criteria for inertia adjustability that meets system inertia safety are established for different fault scenarios. This clarifies the inertia adjustability level of the new power system, provides sufficient adjustable inertia resources for grid personnel, and ensures safe and stable system operation under different disturbance scales.

[0098] The simulation process of the embodiment of the present invention is as follows:

[0099] A 39-node New England system was constructed within the DIgSILENT PowerFactory simulation platform. G03, G04, and G08 in the original model were replaced with wind farms consisting of 160, 160, and 140 5MW wind turbines (W1, W2, and W3), respectively. Nodes 30, 31, 32, 33, 34, 35, 36, 37, and 39 were equipped with adjustable inertia resources (IRS1 through IRS10), as shown in Figure 2. The rated parameters of the new energy stations and conventional generators are shown in Table 1.

[0100] Table 1 Rated capacity and inertia time constant of each unit and existing adjustable inertia resources in the modified 39-bus system

[0101] The following examples take two scenarios, C1, where a 400MW fault occurs and wind turbines W1 to W3 are excluded from inertia and system frequency control, and C2, where a 750MW fault occurs and the emergency frequency control power is 150MW. The inertia requirement and inertia adjustability design values ​​for the system under frequency stability constraints are verified. The frequency security constraint indicators for scenarios C1 and C2 are shown in Table 2.

[0102] Table 2 Frequency safety constraint index values ​​corresponding to scenarios C1 and C2

[0103] According to the inertia requirement calculation model proposed in step S1 of the present invention, the system inertia requirements of the system under different disturbance scenarios considering the frequency safety constraint can be obtained respectively, as shown in Table 3.

[0104] Table 3 Inertia requirements corresponding to scenarios S1 and S2

[0105] According to Table 3, the inertia levels of the test system are set to the corresponding critical levels, and the corresponding frequency response curves for different disturbance event scenarios are shown in Figures 3(a) and 3(b). From Figure 3(a), the maximum frequency change rate corresponding to the C1 disturbance event is 0.49Hz / s, which is basically consistent with the 0.50Hz / s constraint setting value; from Figure 3(b), it can be seen that the maximum frequency deviation corresponding to the C2 disturbance event is 0.49Hz, which is basically consistent with the 0.50Hz constraint setting value. In summary, the above results verify the effectiveness and accuracy of the system inertia demand calculation model under the frequency safety constraint calculated by the embodiment of the present invention. Furthermore, according to the calculation method for the system inertia adjustability coefficient described in step 2, the inertia adjustability values ​​at each level are obtained as shown in Table 4. Table 4 shows that the first-level inertia adjustability of the test system is sufficient, that is, it satisfies 16875>3600; however, the corresponding second-level inertia adjustability is insufficient, that is, it satisfies 16875<23400. According to the inertia adjustability design criteria described in step S2, to ensure the safety of the system inertia level under the N-2 disturbance, the system should also add an additional 6520MW.s of inertia resources.

[0106] Table 4 The test system should be equipped with adjustable inertia at each level / MW.s

[0107] In summary, the novel method for evaluating and designing the inertia adjustability of a power system proposed in the embodiments of the present invention establishes a novel evaluation and design criterion for the inertia adjustability of a power system based on the current system inertia level, the maximum achievable inertia level of the system, and the inertia requirement of the system to meet frequency safety constraints. This method can effectively assist operators and planners in identifying the adequacy of the system's inertia adjustability, providing a foundation for the subsequent refined regulation and optimized configuration of inertia resources.

[0108] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be covered by the scope of the claims of the present invention.

Claims

1. A method for evaluating and designing the adjustable inertia capability of a power system, characterized in that: include: Collect basic data of the power system, including system load level, rated capacity, kinetic energy and operating status of various types of generator sets, system frequency regulation capability and system frequency control strategy, and use theoretical calculation to obtain the system inertia level and the system inertia demand under different disturbance scales based on the system inertia demand and system frequency safety index limit requirements; According to the obtained system inertia level and inertia demand, combined with the foreseeable fault scale of the system, the power system inertia adjustable capacity is graded, the inertia adjustable capacity calculation index is constructed, and the system inertia adjustable capacity design criteria are generated.

2. A method for evaluating and designing the adjustable inertia capability of a power system according to claim 1, characterized in that: The system inertia demand and system frequency security index limit requirements include the power system inertia level H sys It is expressed as: Where n and m represent the number of synchronous units in the system and the number of new energy units with simulated inertia control, respectively; H s,i represents the inertia of the ith synchronous unit; H v,j represents the simulated inertia size of the jth new energy unit with simulated inertia control; x i Indicates the operating status of the i-th synchronous unit; y j Indicates the operating status of the j-th new energy unit.

3. A method for evaluating and designing the adjustable inertia capability of a power system according to claim 2, characterized in that: The system inertia requirement and system frequency safety index limit requirements also include the system inertia requirement H under system N-1 fault sc,1 It is expressed as: Among them, ΔP N-1 Indicates the scale of system N-1 failure; Indicates the frequency change rate safety limit corresponding to the system N-1 fault; Δf sc1 represents the maximum frequency deviation safety limit corresponding to the system N-1 fault; α1 and β1 are the frequency safety factors corresponding to the system N-1 fault; R sys Indicates the system frequency modulation rate; f d Indicates the system frequency modulation dead zone; D sys represents the system equivalent damping; t s It represents the delay time of the system's primary frequency modulation; f0 represents the rated frequency of the system; ln represents the logarithm of the natural logarithm with the constant e as the base.

4. A method for evaluating and designing the adjustable inertia capability of a power system according to claim 3, characterized in that: The system inertia requirement and system frequency safety index limit requirements also include the system inertia requirement H under system N-2 fault sc,2 It is expressed as: Among them, ΔP N-2 Indicates the scale of system N-2 failure; Indicates the frequency change rate safety limit corresponding to the system N-2 fault; Δf sc2 represents the maximum frequency deviation safety limit corresponding to the system N-2 fault; α2 and β2 are the frequency safety factors corresponding to the system N-2 fault; R sys Indicates the system frequency modulation rate; D sys Indicates the system frequency modulation dead zone; ΔP c Indicates the system emergency frequency control quantity; t c Indicates the system emergency frequency control delay time; t s It represents the delay time of the system's primary frequency modulation; f0 represents the rated frequency of the system; ln represents the logarithm of the natural logarithm with the constant e as the base.

5. A method for evaluating and designing the adjustable inertia capability of a power system according to claim 4, characterized in that: The grading of the power system inertia adjustable capacity includes dividing the power system inertia adjustable capacity level into primary adjustable capacity and secondary adjustable capacity according to the foreseeable fault scale of the system, wherein the primary adjustable capacity corresponds to N-1 faults and the secondary adjustable capacity corresponds to N-2 faults.

6. A method for evaluating and designing the adjustable inertia capability of a power system according to claim 5, characterized in that: The first-level adjustable capacity coefficient K R,1 It is expressed as: Among them, H max Indicates the maximum inertia level that the power system can obtain; H sc,1 It represents the inertia requirement corresponding to the N-1 fault in the power system, H sys Indicates the current inertia level of the power system; The secondary adjustable capacity coefficient K R,2 It is expressed as: Among them, H max Indicates the maximum inertia level that the power system can obtain; H sc,2 It represents the inertia requirement corresponding to the power system N-2 fault, H sys Indicates the current inertia level of the power system.

7. A method for evaluating and designing the adjustable inertia capability of a power system according to claim 6, characterized in that: The system inertia adjustable capacity design criteria include that under the N-1 fault scenario, the first-level inertia adjustable capacity of the power system is designed to meet the following requirements: Where ΔH TZ,1 is the maximum inertia loss corresponding to the system N-1 accident, ΔH TW is the maximum fluctuation range of the system inertia level under normal operation; γ is the safety margin coefficient of the system inertia adjustable capacity; In the N-2 fault scenario, the power system secondary inertia adjustable capability is designed to meet the following requirements: Where ΔH TZ,2 is the maximum inertia loss corresponding to the system N-2 accident, ΔH TW is the maximum fluctuation range of the system inertia level under normal operation; γ is the safety margin coefficient of the system inertia adjustable capacity.

8. A system using a method for evaluating and designing the adjustable inertia capability of a power system as claimed in any one of claims 1 to 7, characterized in that: It includes a data acquisition module, an inertia demand calculation module, an inertia adjustable capability classification module and an index calculation module; The data acquisition module is used to collect basic data of the power system, including system load level, rated capacity, kinetic energy and operating status of various types of generator sets, system frequency regulation capability and system frequency control strategy; The inertia demand calculation module is used to obtain the inertia level of the system and the inertia demand of the system under different disturbance expected disturbance scales by theoretical calculation according to the collected data and the requirements of the system frequency safety index limit; The inertia adjustable capacity classification module is used to classify the inertia adjustable capacity of the power system according to the system inertia level and inertia demand, combined with the predictable fault scale of the system; The index calculation module is used to construct an inertia adjustable capacity calculation index and generate a system inertia adjustable capacity design criterion under different fault scenarios.

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

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

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