Method and device for evaluating minimum inertia of power system

Abstract

The invention relates to the technical field of new energy power generation operation control, and particularly provides a power system minimum inertia evaluation method and device, and the method comprises the steps: determining a system minimum inertia value considering a frequency change rate constraint based on the maximum power variation of a system; determining a system minimum inertia value considering the maximum frequency deviation of the system based on the maximum frequency deviation of the system after the maximum power disturbance of the system; and determining the minimum inertia of the power system based on the minimum inertia value of the system considering the frequency change rate constraint and the minimum inertia value of the system considering the maximum frequency deviation of the system. According to the technical scheme provided by the invention, the requirements of the system frequency change rate constraint and the maximum frequency difference constraint on the minimum inertia of the system are comprehensively considered, so that the evaluation value of the minimum inertia of the system is obtained, visual data support is provided for a dispatching operation department, and the stability of the system frequency is guaranteed.

Description

Technical Field

[0001] The present invention relates to the field of renewable energy power generation operation control technology, and in particular to a method and device for evaluating minimum inertia of an electric power system. Background Art

[0002] Compared with the traditional synchronous system, the large-scale access of new energy in the high-proportion power electronic power system replaces some synchronous units. The decoupling characteristics of new energy power electronics and its maximum power tracking mode gradually reduce the system inertia level and weaken the frequency regulation capability. In addition, the commissioning of ultra-high voltage and large-capacity cross-regional DC transmission has blocked the cross-regional inertia support and power response under disturbance, seriously deteriorating the system frequency stability under large disturbances.

[0003] The relative reduction of system inertia causes a huge change in the frequency characteristics under disturbance. On the one hand, the reduction of inertia leads to an increase in the rate of change of frequency (RoCoF) under disturbance, which increases the risk of distributed power supply disconnection and threatens the safe operation of conventional units. In the 8.9 blackout in the UK, new energy and DC input accounted for about 50% before the accident, and the instantaneous cumulative power loss reached 1131MW. RoCoF exceeded the anti-islanding protection setting value of the distributed power supply equipment level by 0.125Hz / s, causing about 350MW of distributed power supply to disconnect from the grid, further increasing the unbalanced power of the system, and the frequency dropped rapidly, eventually triggering low-frequency load reduction to cause a large-scale power outage. On the other hand, the reduction of inertia further reduces the lowest frequency point, increasing the possibility of triggering the third line of defense low-frequency load reduction. In severe cases, the frequency of the speed regulation system has not yet been activated, or the frequency cannot be restored through sufficient primary frequency regulation. In the above-mentioned 8.9 accident in the UK, the larger disturbance power and smaller inertia level eventually triggered low-frequency load reduction and caused a power outage. In the 2016 South Australia blackout, wind power and photovoltaic power generation accounted for 48.36% before the accident. Extreme weather caused the interconnection line to be severely overloaded and tripped, and the RoCoF was as high as 6Hz / s. The larger RoCoF and lower frequency minimum point caused the frequency to collapse before the low-frequency load reduction could take effect, eventually leading to a power outage across South Australia.

[0004] In summary, system inertia is an important physical quantity that prevents rapid frequency changes under disturbances. Its relative reduction increases the RoCoF under disturbances, thereby reducing the lowest frequency point. In order to ensure that the RoCoF after the disturbance does not exceed the set value of the anti-islanding protection of the distributed power source, causing it to be disconnected from the grid and damage the synchronous machine, and to leave enough adjustment time for the primary frequency regulation to avoid triggering the third line of defense, a high-proportion power electronic power system needs to ensure a certain inertia level. Therefore, it is necessary to carry out an assessment of the minimum inertia required for a high-proportion new energy power system, quickly calculate the minimum inertia required under the current system operating conditions, and provide data support for the stability of the grid frequency. Summary of the invention

[0005] In order to overcome the above defects, the present invention proposes a method and device for evaluating minimum inertia of a power system.

[0006] In a first aspect, a method for evaluating minimum inertia of an electric power system is provided, the method comprising:

[0007] Determine the minimum inertia value of the system considering the frequency change rate constraint based on the maximum power change of the system;

[0008] Determine the minimum inertia value of the system considering the maximum frequency deviation of the system based on the maximum frequency deviation of the system after the maximum power disturbance occurs in the system;

[0009] The minimum inertia of the power system is determined based on the minimum inertia value of the system considering the frequency change rate constraint and the minimum inertia value of the system considering the maximum frequency deviation of the system.

[0010] Preferably, the calculation formula of the minimum inertia value of the system considering the frequency change rate constraint is as follows:

[0011]

[0012] In the above formula, is the minimum inertia value of the system considering the frequency change rate constraint, △P max is the maximum power variation of the system, RoCoF limit is the limit of the frequency change rate.

[0013] Furthermore, the limit of the frequency change rate satisfies:

[0014]

[0015] In the above formula, H sys is the required inertia of the system.

[0016] Furthermore, the maximum power variation of the system is the maximum power variation of the system when a disturbance occurs in the system and the synchronous machine speed regulation system and the new energy primary frequency regulation are not activated.

[0017] Furthermore, the frequency change rate limit RoCoF limit =2Hz / s.

[0018] Preferably, the calculation formula of the system minimum inertia value considering the system maximum frequency deviation is as follows:

[0019]

[0020] In the above formula, is the minimum inertia value of the system considering the maximum frequency deviation of the system, L is the correction coefficient, H sys is the required inertia of the system.

[0021] Furthermore, the process of obtaining the correction coefficient includes:

[0022] Step 1: Initialize the correction coefficient to 0;

[0023] Step 2: Calculate the minimum inertia value of the system considering the maximum frequency deviation of the system, and put the minimum inertia value of the system considering the maximum frequency deviation of the system into the system time domain model or the regional power grid equivalent model, obtain the maximum deviation value of the system frequency after the maximum power disturbance occurs in the system, and add the maximum deviation value of the system frequency after the maximum power disturbance occurs in the system to the system frequency deviation set;

[0024] Step 3 determines whether the correction coefficient is greater than or equal to 1. If so, output the correction coefficient corresponding to the maximum value in the system frequency deviation set. Otherwise, set the correction coefficient L=L+0.05 and return to step 2.

[0025] In a second aspect, a power system minimum inertia evaluation device is provided, the power system minimum inertia evaluation device comprising:

[0026] A first determination module is used to determine a system minimum inertia value considering a frequency change rate constraint based on a system maximum power change amount;

[0027] A second determination module is used to determine the system minimum inertia value considering the maximum frequency deviation of the system based on the maximum frequency deviation of the system after the maximum power disturbance occurs in the system;

[0028] The third determination module is used to determine the minimum inertia of the power system based on the minimum inertia value of the system considering the frequency change rate constraint and the minimum inertia value of the system considering the maximum frequency deviation of the system.

[0029] In a third aspect, a computer device is provided, comprising: one or more processors;

[0030] The processor is used to store one or more programs;

[0031] When the one or more programs are executed by the one or more processors, the power system minimum inertia estimation method is implemented.

[0032] In a fourth aspect, a computer-readable storage medium is provided, on which a computer program is stored, and when the computer program is executed, the method for evaluating the minimum inertia of the power system is implemented.

[0033] The above one or more technical solutions of the present invention have at least one or more of the following beneficial effects:

[0034] The present invention relates to the field of renewable energy power generation operation control technology, and specifically provides a method and device for evaluating the minimum inertia of an electric power system, including: determining the minimum inertia value of the system considering the frequency change rate constraint based on the maximum power change of the system; determining the minimum inertia value of the system considering the maximum frequency deviation of the system based on the maximum deviation of the system frequency after the maximum power disturbance of the system; determining the minimum inertia of the electric power system based on the minimum inertia value of the system considering the frequency change rate constraint and the minimum inertia value of the system considering the maximum frequency deviation of the system. The technical solution provided by the present invention comprehensively considers the requirements for the minimum inertia of the system from the two aspects of the system frequency change rate constraint and the maximum frequency difference constraint, and then obtains the evaluation value of the minimum inertia of the system, providing intuitive data support for the dispatching and operation department, and ensuring the stability of the system frequency. Furthermore, the technical solution provided by the present invention can adapt to complex power grid operating conditions and various operating scenarios, and calculates the minimum inertia required by the system according to different operating conditions and scenarios. The proposed solution has universality. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 1 is a schematic flow chart of the main steps of the method for evaluating the minimum inertia of a power system according to an embodiment of the present invention;

[0036] Figure 2 is a schematic diagram of the structure of the IEEE39 improved model used to verify the effectiveness of the proposed method according to an embodiment of the present invention;

[0037] Figure 3 It is a diagram showing the minimum inertia required for the system considering the frequency change rate constraint under different power disturbances in an embodiment of the present invention;

[0038] Figure 4 is a frequency variation curve diagram of node 36 under different inertia scenarios of an embodiment of the present invention;

[0039] Figure 5 is a curve diagram of the minimum inertia required for the system considering the maximum frequency difference constraint under different power disturbances in an embodiment of the present invention;

[0040] Figure 6 is a curve diagram of the minimum inertia required by the system when the maximum frequency difference setting value of the system is changed according to an embodiment of the present invention;

[0041] Figure 7 It is a main structural block diagram of the power system minimum inertia estimation device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The specific implementation modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0043] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] As disclosed in the background technology, compared with the traditional synchronous system, the large-scale access of new energy in the high-proportion power electronic power system replaces some synchronous units. The decoupling characteristics of new energy power electronics and its maximum power tracking mode gradually reduce the system inertia level and weaken the frequency regulation capability. In addition, the commissioning of ultra-high voltage and large-capacity cross-regional direct current transmission has blocked the cross-regional inertia support and power response under disturbance, seriously deteriorating the system frequency stability under large disturbance.

[0045] The relative reduction of system inertia causes a huge change in the frequency characteristics under disturbance. On the one hand, the reduction of inertia leads to an increase in the rate of change of frequency (RoCoF) under disturbance, which increases the risk of distributed power supply disconnection and threatens the safe operation of conventional units. In the 8.9 blackout in the UK, new energy and DC input accounted for about 50% before the accident, and the instantaneous cumulative power loss reached 1131MW. RoCoF exceeded the anti-islanding protection setting value of the distributed power supply equipment level by 0.125Hz / s, causing about 350MW of distributed power supply to disconnect from the grid, further increasing the unbalanced power of the system, and the frequency dropped rapidly, eventually triggering low-frequency load reduction to cause a large-scale power outage. On the other hand, the reduction of inertia further reduces the lowest frequency point, increasing the possibility of triggering the third line of defense low-frequency load reduction. In severe cases, the frequency of the speed regulation system has not yet been activated, or the frequency cannot be restored through sufficient primary frequency regulation. In the above-mentioned 8.9 accident in the UK, the larger disturbance power and smaller inertia level eventually triggered low-frequency load reduction and caused a power outage. In the 2016 South Australia blackout, wind power and photovoltaic power generation accounted for 48.36% before the accident. Extreme weather caused the interconnection line to be severely overloaded and tripped, and the RoCoF was as high as 6Hz / s. The larger RoCoF and lower frequency minimum point caused the frequency to collapse before the low-frequency load reduction could take effect, eventually leading to a power outage across South Australia.

[0046] In summary, system inertia is an important physical quantity that prevents rapid frequency changes under disturbances. Its relative reduction increases the RoCoF under disturbances, thereby reducing the lowest frequency point. In order to ensure that the RoCoF after the disturbance does not exceed the set value of the anti-islanding protection of the distributed power source, causing it to be disconnected from the grid and damage the synchronous machine, and to leave enough adjustment time for the primary frequency regulation to avoid triggering the third line of defense, a high-proportion power electronic power system needs to ensure a certain inertia level. Therefore, it is necessary to carry out an assessment of the minimum inertia required for a high-proportion new energy power system, quickly calculate the minimum inertia required under the current system operating conditions, and provide data support for the stability of the grid frequency.

[0047] In order to improve the above problems, the present invention relates to the field of new energy power generation operation control technology, and specifically provides a method and device for evaluating the minimum inertia of a power system, including: determining the minimum inertia value of the system considering the frequency change rate constraint based on the maximum power change of the system; determining the minimum inertia value of the system considering the maximum frequency deviation of the system based on the maximum deviation of the system frequency after the maximum power disturbance occurs in the system; determining the minimum inertia of the power system based on the minimum inertia value of the system considering the frequency change rate constraint and the minimum inertia value of the system considering the maximum frequency deviation of the system. The technical solution provided by the present invention comprehensively considers the requirements for the minimum inertia of the system from the two aspects of the system frequency change rate constraint and the maximum frequency difference constraint, and then obtains the evaluation value of the minimum inertia of the system, which provides intuitive data support for the dispatching and operation departments, and ensures the stability of the system frequency. Furthermore, the technical solution provided by the present invention can adapt to complex power grid operating conditions and various operating scenarios, and calculates the minimum inertia required by the system according to different operating conditions and scenarios. The proposed solution has universality.

[0048] The above scheme is described in detail below.

[0049] Example 1

[0050] See attached Figure 1 , Figure 1 FIG. 1 is a flow chart showing the main steps of a method for evaluating the minimum inertia of a power system according to an embodiment of the present invention. Figure 1 As shown, the method for evaluating the minimum inertia of a power system in an embodiment of the present invention mainly includes the following steps:

[0051] Step S101: determining a system minimum inertia value taking into account a frequency change rate constraint based on a system maximum power change amount;

[0052] Step S102: determining a system minimum inertia value taking into account the maximum frequency deviation of the system based on the maximum frequency deviation of the system after the maximum power disturbance occurs in the system;

[0053] Step S103: Determine the minimum inertia of the power system based on the minimum inertia value of the system considering the frequency change rate constraint and the minimum inertia value of the system considering the maximum frequency deviation of the system.

[0054] In this embodiment, the calculation formula of the minimum inertia value of the system considering the frequency change rate constraint is as follows:

[0055]

[0056] In the above formula, is the minimum inertia value of the system considering the frequency change rate constraint, △P max is the maximum power variation of the system, RoCoF limit is the limit of the frequency change rate.

[0057] In this embodiment, the maximum power variation of the system is the maximum power variation of the system when a disturbance occurs in the system and the synchronous machine speed regulation system and the new energy primary frequency regulation are not in operation.

[0058] At the moment of disturbance in the system, the synchronous machine speed regulation system and the new energy primary frequency regulation do not work, and the unbalanced power is supported only by the inertia sources of the system. At this time, the maximum value of the system frequency change rate can be calculated (the minimum value corresponds to the active power shortage, and the maximum value corresponds to the active power surplus), and the limit value of the frequency change rate satisfies:

[0059]

[0060] In the above formula, H sys is the required inertia of the system.

[0061] At present, the protection settings based on the frequency change rate are mainly aimed at the anti-islanding protection of distributed power sources. Many countries and regions with relatively developed distributed development have clearly put forward requirements for RoCoF as the anti-islanding protection threshold. For example, the UK RoCoF protection device is set to ±0.125Hz / s, and the Australian power grid requires that RoCoF does not exceed ±0.5Hz / s. However, with the increase in the penetration rate of new energy and the insufficient level of system inertia, various countries have increased the anti-islanding protection action threshold of distributed power sources. For example, the UK and Denmark have increased the anti-islanding protection threshold from ±0.125Hz / s and ±0.5Hz / s to ±1Hz / s and ±2.5Hz / s, respectively. In addition, in order to prevent the synchronous unit from causing pole slip and damaging the synchronous machine structure, the system RoCoF is required to not exceed ±2Hz / s. In this embodiment, the limit value of the frequency change rate RoCoF limit =2Hz / s.

[0062] The main function of the primary frequency regulation of the power system is to change the unit output according to the frequency deviation to prevent the system frequency from continuing to rise or fall; the main function of the inertia support is to mitigate the speed of system frequency change and buy time for the primary frequency regulation, thereby reducing the frequency deviation to a certain extent. The system frequency deviation is affected by many factors such as the primary frequency regulation capability and the inertia support capability. If only the inertia acts, the system frequency will continue to fall. With the continuous improvement of the system's new energy output, the national standards GB / T19963.1-2021 "Technical Regulations for the Access of Wind Farms to the Power System" and GB / T 19964-2012 "Technical Regulations for the Access of Photovoltaic Power Stations to the Power System" both clearly require wind farms and photovoltaic power stations to have primary frequency regulation capabilities to support the stability of the grid frequency. Therefore, it can be considered that the primary frequency regulation capability remains unchanged during the process of replacing the synchronous generator set with new energy units, and only the system inertia size is changed. At this time, the calculation formula for the minimum inertia value of the system considering the maximum frequency deviation of the system is as follows:

[0063]

[0064] In the above formula, is the minimum inertia value of the system considering the maximum frequency deviation of the system, L is the correction coefficient, H sys is the required inertia of the system.

[0065] In one embodiment, the process of obtaining the correction coefficient includes:

[0066] Step 1: Initialize the correction coefficient to 0;

[0067] Step 2: Calculate the minimum inertia value of the system considering the maximum frequency deviation of the system, and put the minimum inertia value of the system considering the maximum frequency deviation of the system into the system time domain model or the regional power grid equivalent model, obtain the maximum deviation value of the system frequency after the maximum power disturbance occurs in the system, and add the maximum deviation value of the system frequency after the maximum power disturbance occurs in the system to the system frequency deviation set;

[0068] Step 3 determines whether the correction coefficient is greater than or equal to 1. If so, output the correction coefficient corresponding to the maximum value in the system frequency deviation set. Otherwise, set the correction coefficient L=L+0.05 and return to step 2.

[0069] For low-frequency disturbance events, in order to prevent low-frequency load shedding, the lowest frequency point after the disturbance is not lower than the first round of low-frequency load shedding action value, which is generally set to 49Hz; for high-frequency disturbance events, in order to prevent high-frequency machine shedding action, it is required that the system frequency is not higher than 50.6Hz before the safety and stability control device is activated. In the example description, the high-frequency machine shedding problem of the sending-end power grid is not considered for the time being, and a certain margin is considered, and the maximum frequency difference is set to 49.2Hz.

[0070] After obtaining the system minimum inertia value considering the frequency change rate constraint and the power system minimum inertia value considering the frequency deviation constraint, the minimum inertia requirement to maintain the current system frequency stability can be obtained, providing intuitive data reference for the power grid dispatching department.

[0071] like Figure 2 As shown in Figure 2, the effectiveness of the proposed method is verified based on the improved IEEE 39-node system. In order to make the frequency characteristics of different nodes in the system more obvious after the power disturbance, the transmission lines 17-18 and 25-26 in the original system are disconnected during the simulation verification. Figure 4 As shown in the figure, considering the impact of different types of new energy grid penetration rates on grid frequency stability, the synchronous generators connected to nodes 33 and 34 in the original system are replaced with grid-following new energy power generation systems of the same capacity, and the synchronous generators connected to nodes 35 and 36 in the original system are replaced with grid-building new energy power generation systems of the same capacity. By presetting the expected fault set of system frequency events, the improved Figure 2 In the system shown, it is found that when the power disturbance occurs at node 23, the calculated inertia of node 36 is the smallest. Therefore, in order to more intuitively illustrate the accuracy and effectiveness of the proposed method, the example is explained with emphasis on the area where node 36 is located (i.e., area 3 in the figure), where the inertia evaluation value is 1.6s.

[0072] First, the minimum inertia required considering the RoCoF constraint is analyzed. According to formula (2), the minimum inertia required by the system under different power disturbances and RoCoF constraints is calculated as follows: Figure 3 As shown. Figure 3 It can be seen that the greater the disturbance power and the smaller the |RoCoFlimit| constraint, the greater the minimum inertia required by the system. In the example, the maximum disturbance of the area 3 system is set to the disconnection of the new energy unit G6 (650MW, accounting for 16.67% of the total capacity of the regional power grid).

[0073] For RoCoF constraints, RoCoF limit When the value is 2Hz / s, the minimum inertia required for the area 3 system under the G6 off-grid disturbance is 2.08s, while the inertia of the regional system is 1.60s at this time, and the system faces the risk of frequency instability. The G7 pseudo-synchronous coefficient is changed from 3.771 to 9, and the equivalent inertia of the regional system is 2.5s at this time. The frequency curve of node 36 before and after the virtual coefficient is changed is as follows Figure 4 As shown. Figure 4 It can be seen that after changing the G7 virtual synchronization coefficient, the maximum RoCoF of the system is improved and meets the RoCoF constraint requirements.

[0074] Secondly, analyze the minimum inertia required considering the frequency deviation constraint. Set the maximum allowable deviation value of the system to 49.2Hz, and use the electromechanical simulation platform or frequency response model to obtain the minimum inertia value of the system under the maximum frequency deviation constraint, such as Figure 5 At the same time, if the maximum power disturbance is set to 0.167pu, the minimum inertia required by the system in region 3 under different frequency difference constraints is as follows: Figure 6 As shown. Figure 5 , Figure 6 It can be seen that under a certain frequency threshold constraint, the system minimum inertia requirement is approximately linearly related to the maximum power disturbance; under a certain power disturbance, the system minimum inertia requirement is nonlinearly related to the frequency threshold. When the frequency threshold is too high, the system inertia requirement increases sharply.

[0075] For the Case 6 region 3 system, the maximum disturbance is set to the disconnection of the new energy unit G6, and the maximum operating frequency difference of the system is set to 49.2Hz. The minimum inertia required for the region 3 system under this disturbance is 1.8429s, while the grid inertia assessment value is 1.6s at this time, and the system faces the risk of frequency instability. The virtual synchronization coefficient of G7 is changed from 3.771 to 9. At this time, the equivalent inertia of the regional system is 2.5s. The frequency curve of node 36 before and after the virtual coefficient is changed is as follows Figure 4 As shown. Figure 4 It can be seen that after changing the G7 virtual synchronization coefficient, the maximum frequency difference of the system is improved and meets the frequency minimum point threshold requirement.

[0076] In summary, for the Case 6 region 3 system, when the maximum disturbance is set to the new energy unit G6 disconnected from the grid, the minimum inertia required for the regional system when the RoCoF constraint is considered is is 2.08s; when considering the maximum frequency difference constraint, the minimum inertia required for the regional system is 1.8429. When the two constraints are considered comprehensively, the minimum inertia H required by the regional system is min It is 2.08s.

[0077] Example 2

[0078] Based on the same inventive concept, the present invention also provides a minimum inertia evaluation device for a power system, such as Figure 7 As shown, the power system minimum inertia evaluation device includes:

[0079] A first determination module is used to determine a system minimum inertia value considering a frequency change rate constraint based on a system maximum power change amount;

[0080] A second determination module is used to determine the system minimum inertia value considering the maximum frequency deviation of the system based on the maximum frequency deviation of the system after the maximum power disturbance occurs in the system;

[0081] The third determination module is used to determine the minimum inertia of the power system based on the minimum inertia value of the system considering the frequency change rate constraint and the minimum inertia value of the system considering the maximum frequency deviation of the system.

[0082] Preferably, the calculation formula of the minimum inertia value of the system considering the frequency change rate constraint is as follows:

[0083]

[0084] In the above formula, is the minimum inertia value of the system considering the frequency change rate constraint, △P max is the maximum power variation of the system, RoCoF limit is the limit of the frequency change rate.

[0085] Furthermore, the limit of the frequency change rate satisfies:

[0086]

[0087] In the above formula, H sys is the required inertia of the system.

[0088] Furthermore, the maximum power variation of the system is the maximum power variation of the system when a disturbance occurs in the system and the synchronous machine speed regulation system and the new energy primary frequency regulation are not activated.

[0089] Furthermore, the frequency change rate limit RoCoF limit =2Hz / s.

[0090] Preferably, the calculation formula of the system minimum inertia value considering the system maximum frequency deviation is as follows:

[0091]

[0092] In the above formula, is the minimum inertia value of the system considering the maximum frequency deviation of the system, L is the correction coefficient, H sys is the required inertia of the system.

[0093] Furthermore, the process of obtaining the correction coefficient includes:

[0094] Step 1: Initialize the correction coefficient to 0;

[0095] Step 2: Calculate the minimum inertia value of the system considering the maximum frequency deviation of the system, and put the minimum inertia value of the system considering the maximum frequency deviation of the system into the system time domain model or the regional power grid equivalent model, obtain the maximum deviation value of the system frequency after the maximum power disturbance occurs in the system, and add the maximum deviation value of the system frequency after the maximum power disturbance occurs in the system to the system frequency deviation set;

[0096] Step 3 determines whether the correction coefficient is greater than or equal to 1. If so, output the correction coefficient corresponding to the maximum value in the system frequency deviation set. Otherwise, set the correction coefficient L=L+0.05 and return to step 2.

[0097] Example 3

[0098] Based on the same inventive concept, the present invention also provides a computer device, which includes a processor and a memory, wherein the memory is used to store a computer program, the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, and is specifically suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding function, so as to implement the steps of a method for evaluating the minimum inertia of a power system in the above embodiment.

[0099] Example 4

[0100] Based on the same inventive concept, the present invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device for storing programs and data. It can be understood that the computer-readable storage medium here can include both built-in storage media in a computer device and, of course, extended storage media supported by the computer device. The computer-readable storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by a processor are also stored in the storage space, and these instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the steps of a method for evaluating the minimum inertia of a power system in the above embodiment.

[0101] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0102] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0103] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0104] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for evaluating minimum inertia of a power system, characterized in that: The method comprises: Determine the minimum inertia value of the system considering the frequency change rate constraint based on the maximum power change of the system; Determine the minimum inertia value of the system considering the maximum frequency deviation of the system based on the maximum frequency deviation of the system after the maximum power disturbance occurs in the system; The minimum inertia of the power system is determined based on the minimum inertia value of the system considering the frequency change rate constraint and the minimum inertia value of the system considering the maximum frequency deviation of the system.

2. The method according to claim 1, characterized in that The calculation formula for the minimum inertia value of the system considering the frequency change rate constraint is as follows: In the above formula, is the minimum inertia value of the system considering the frequency change rate constraint, △P max is the maximum power variation of the system, RoCoF limit is the limit of the frequency change rate.

3. The method according to claim 2, characterized in that The frequency change rate limit meets the following requirements: In the above formula, H sys is the required inertia of the system.

4. The method according to claim 3, characterized in that The maximum power variation of the system is the maximum power variation of the system when a disturbance occurs in the system and the synchronous machine speed regulation system and the new energy primary frequency regulation are not in operation.

5. The method according to claim 3, characterized in that The limit value of the frequency change rate RoCoF limit =2Hz / s.

6. The method according to claim 1, characterized in that The calculation formula for the minimum inertia value of the system considering the maximum frequency deviation of the system is as follows: In the above formula, is the minimum inertia value of the system considering the maximum frequency deviation of the system, L is the correction coefficient, H sys is the required inertia of the system.

7. The method according to claim 6, characterized in that The process of obtaining the correction coefficient includes: Step 1: Initialize the correction coefficient to 0; Step 2: Calculate the minimum inertia value of the system considering the maximum frequency deviation of the system, and put the minimum inertia value of the system considering the maximum frequency deviation of the system into the system time domain model or the regional power grid equivalent model, obtain the maximum deviation value of the system frequency after the maximum power disturbance occurs in the system, and add the maximum deviation value of the system frequency after the maximum power disturbance occurs in the system to the system frequency deviation set; Step 3 determines whether the correction coefficient is greater than or equal to 1. If so, output the correction coefficient corresponding to the maximum value in the system frequency deviation set. Otherwise, set the correction coefficient L=L+0.05 and return to step 2.

8. A minimum inertia evaluation device for a power system, characterized in that: The device comprises: A first determination module is used to determine a system minimum inertia value considering a frequency change rate constraint based on a system maximum power change amount; A second determination module is used to determine the system minimum inertia value considering the maximum frequency deviation of the system based on the maximum frequency deviation of the system after the maximum power disturbance occurs in the system; The third determination module is used to determine the minimum inertia of the power system based on the minimum inertia value of the system considering the frequency change rate constraint and the minimum inertia value of the system considering the maximum frequency deviation of the system.

9. A computer device, characterized in that: include: one or more processors; The processor is used to store one or more programs; When the one or more programs are executed by the one or more processors, the method for estimating minimum inertia of a power system according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium, characterized in that: A computer program is stored thereon, and when the computer program is executed, the method for estimating the minimum inertia of the power system as claimed in any one of claims 1 to 7 is implemented.

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