Frequency response analysis method and system based on double inertia centers

Abstract

The invention discloses a frequency response analysis method and system based on double inertia centers, and relates to the technical field of power frequency modulation analysis. The method provided by the invention comprises the steps of S1, respectively establishing frequency response models for various frequency modulation resources in a power system, S2, constructing a first inertia center by aggregating inertia of a synchronous generator set and a frequency modulation function of a network tracking system based on the frequency response models, and constructing a second inertia center through the inertia of the aggregation networking system and the frequency modulation function of the matched energy storage system. According to the method, on the basis of a traditional frequency response model, the frequency fluctuation difference between the frequency of the new energy inertia center and the frequency of a conventional unit is distinguished through the double inertia centers, and the frequency response process of the network construction type new energy system can be accurately calculated.

Description

Technical Field

[0001] This invention relates to the field of power frequency regulation analysis technology, and in particular to a frequency response analysis method and system based on dual inertia centers. Background Technology

[0002] As the penetration rate of new energy sources in the power system continues to increase, the frequency regulation space of synchronous generators is compressed, and the grid inertia is significantly reduced, resulting in more severe frequency fluctuations in the system. Relying solely on synchronous motors for frequency regulation can no longer meet the frequency security requirements of modern power systems.

[0003] In traditional power system analysis, the inertial center frequency is often used as the main indicator to describe the overall frequency fluctuation of the system, and its calculation method is based on a weighted average of the inertia weights of each unit. However, with the continuous advancement of large-scale grid connection of new energy sources, there are significant differences in dynamic characteristics and frequency response between new energy clusters and conventional thermal power clusters in the system. New energy units, which account for a smaller proportion, often exhibit larger frequency fluctuations, and this local instability is "masked" by the averaging effect of the center frequency. In addition, the introduction of grid-connected converters provides additional inertial support to the power system, enhancing the system's ability to resist frequency fluctuations. However, grid-connected generators do not have actual physical rotors or governor mechanisms, and the conventional method of aggregating the inertia of synchronous machines and grid-connected generators will lead to frequency response errors.

[0004] Therefore, relying solely on the inertial center frequency to describe the frequency characteristics of a power system is no longer sufficient to meet the requirements for local frequency dynamics and frequency security under current complex operating conditions. Summary of the Invention

[0005] This invention provides a frequency response analysis method and system based on dual inertia centers to solve the problem that the existing method of using the weighted average inertia of each unit as a single inertia center frequency to describe the frequency characteristics of the system cannot meet the requirements of local frequency dynamic analysis and frequency security under the complex operating conditions of the new energy penetration system.

[0006] This invention is achieved through the following technical solution: A first aspect of the present invention provides a frequency response analysis method based on dual centers of inertia, comprising: Frequency response models are established for various frequency regulation resources in the power system; the frequency regulation resources include synchronous generator sets, grid-connected frequency regulation systems, and grid-connected frequency regulation systems. Based on the frequency response models of various frequency regulation resources, a first inertia center and a second inertia center are constructed. The first inertia center is obtained by aggregating the inertia of synchronous generator sets and the frequency regulation function of grid-connected frequency regulation systems, while the second inertia center is obtained by aggregating the inertia of grid-connected frequency regulation systems and the frequency regulation function of supporting energy storage systems. The overall system frequency is obtained based on the frequencies of the first inertia center and the second inertia center.

[0007] The frequency response analysis method proposed in this invention considers the participation of grid-connected renewable energy sources. First, frequency response models are established for various frequency regulation resources in the power system. Taking into account the extended loops of various frequency regulation resources, such as traditional synchronous generator sets, grid-connected frequency regulation systems, and grid-connected frequency regulation systems, a first inertia center is established by aggregating the inertia of synchronous generator sets and the frequency regulation function of grid-connected frequency regulation systems. A second inertia center is constructed by aggregating the inertia of grid-connected frequency regulation systems and the frequency regulation function of supporting energy storage systems, thus forming a dual-inertia center frequency response model containing multiple frequency regulation resources. This dual-inertia center model, based on traditional frequency response models, effectively considers the participation of multiple resources in the frequency response and distinguishes the frequency fluctuation differences between the renewable energy inertia center frequency and the conventional unit frequency. Therefore, it can accurately calculate the frequency response process of systems containing grid-connected renewable energy sources, meeting the local frequency dynamic analysis needs of integrated power systems and realizing the safety assessment of integrated power systems.

[0008] In some embodiments, the grid-connected frequency regulation system includes grid-connected wind turbines and grid-connected energy storage systems, and the grid-connected frequency regulation system includes a grid-connected converter.

[0009] In some implementations, the following frequency regulation control strategy is adopted for the grid-connected wind turbine: Inertial control is applied to the wind turbine by simulating the inertial response process and primary frequency regulation process of a synchronous generator. Inertial support is provided by controlling the wind turbine to release the rotational kinetic energy stored in the wind turbine. The load reduction reserve power is used to provide primary frequency regulation function through the spare capacity; The frequency response model of the grid-connected wind turbine is expressed as follows:

[0010] in, To match the frequency regulation power of grid-connected wind turbines, For virtual inertial control parameters, These are the primary frequency modulation control parameters. To match the frequency regulation time constant of the grid-type fan, This represents the frequency change value. For the Laplace operator.

[0011] In some implementations, the grid-connected energy storage system adopts a droop control mode, and the frequency response model of the grid-connected energy storage system is expressed as follows:

[0012] in, To match the auxiliary output power of the grid-connected energy storage system, This is the energy storage frequency droop control coefficient. For energy storage control time constant, This represents the frequency change value. For the Laplace operator.

[0013] In some embodiments, the grid-connected frequency regulation system further includes a high-voltage direct current transmission system employing a DC frequency limiting controller; The frequency regulation strategy of the high-voltage direct current transmission system is as follows: the DC frequency limit controller simulates the primary frequency regulation process of the synchronous generator, and the DC line transmission power is changed according to the frequency deviation value to provide auxiliary power support. The frequency response model of the high-voltage direct current transmission system is expressed as follows:

[0014] in, This represents the total transmission power of the high-voltage direct current (HVDC) transmission system after DC power adjustment. , These are the proportional and integral coefficients of the PI controller, respectively. The DC frequency modulation time constant is... This represents the frequency change value. For the Laplace operator.

[0015] In some implementations, the grid-type converter simulates the physical characteristics of a synchronous generator using virtual synchronization technology to achieve self-synchronization. The frequency response model of the grid-type converter is expressed as follows:

[0016] in, For the output electromagnetic power of the grid-type converter, E For the grid-connected system potential, For the difference in effort angle, The equivalent voltage of a grid-type converter. This is a virtual impedance.

[0017] In some implementations, the frequency response model of the synchronous generator set is expressed as:

[0018] in, The output frequency of the synchronous generator set. This is the gain coefficient. For high-pressure cylinder gain, The reheat time constant is R This represents the droop coefficient of the synchronous generator. This represents the frequency change value. For the Laplace operator.

[0019] In some implementations, the first center of inertia is represented as:

[0020]

[0021]

[0022] in, The frequency of the first center of inertia The disturbance power allocated to the first center of inertia. This represents the external disturbance power of the system. The total capacity of the first center of inertia. The total capacity of the second center of inertia. It is the sum of the total capacity of the first center of inertia and the second center of inertia. For the Laplace operator, The inertia weight of the second center of inertia, Y, For auxiliary functions, The inertia constant of the first center of inertia, The damping coefficient at the first center of inertia. The proportion of synchronous machines. This is the auxiliary power transfer function of the synchronous generator governor. For the auxiliary power transfer function of virtual inertial control of grid-type wind turbines, The proportion of energy storage capacity allocated to wind turbines. To match the auxiliary power transfer function of grid-type energy storage droop control, This is the proportional coefficient for the transmission capacity of DC lines. This is the auxiliary power transfer function for a DC transmission FLC. The inertia constant of the second center of inertia, The damping coefficient at the second center of inertia. For the auxiliary power transfer function of the virtual speed governor of the grid-type wind turbine, This is a virtual impedance.

[0023] The second center of inertia is represented as:

[0024] in, The frequency of the second center of inertia The disturbance power allocated to the second center of inertia. For the Laplace operator, The frequency of the first center of inertia For auxiliary functions, This is a virtual impedance.

[0025] In some implementations, the overall system frequency obtained based on the frequencies of the first and second inertia centers is expressed as:

[0026] in, For the overall system frequency, The frequency of the first center of inertia The frequency of the second center of inertia The inertia weight of the first center of inertia. The inertia weight of the second inertia center.

[0027] A second aspect of the present invention provides a frequency response analysis system based on dual centers of inertia, comprising: The frequency response modeling module is used to establish frequency response models for various frequency regulation resources in the grid system; the frequency regulation resources include synchronous generator sets, grid-connected frequency regulation systems, and grid-connected frequency regulation systems. The dual inertia center modeling module is used to construct a first inertia center and a second inertia center based on the frequency response models of various frequency regulation resources. The first inertia center is obtained by aggregating the inertia of synchronous generator sets and the frequency regulation function of grid-connected frequency regulation systems, while the second inertia center is obtained by aggregating the inertia of grid-connected frequency regulation systems and the frequency regulation function of supporting energy storage systems. The system frequency analysis module is used to obtain the overall system frequency based on the frequency of the first inertia center and the frequency of the second inertia center.

[0028] Compared with existing technologies, this invention has the following advantages and beneficial effects: Addressing the problem of reduced inertia and decreased frequency regulation capability due to increased new energy penetration, leading to greater frequency regulation demands on power systems, this invention quantitatively analyzes the frequency characteristics of various grid-connected frequency regulation resources and grid-connected power generation, establishing frequency response models for each type of frequency regulation resource. Simultaneously, considering the difference in inertia between grid-connected power generation and conventional synchronous machines, a dual-inertia-center extended frequency response model incorporating multiple frequency regulation resources is established. Based on traditional frequency response models, the inertia-center model effectively considers the participation of multiple resources in the frequency response and distinguishes the frequency fluctuation differences between the inertia-center frequency of new energy and the frequency of conventional units, enabling accurate calculation of the frequency response process of grid-connected new energy systems. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 This is a flowchart of a frequency response analysis method based on dual inertia centers according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a wind turbine frequency response model according to an embodiment of the present invention; Figure 3 This is a schematic diagram of a frequency response model of a grid-connected energy storage system according to an embodiment of the present invention; Figure 4 This is a schematic diagram of a DC FLC frequency response model according to an embodiment of the present invention; Figure 5A This is an equivalent structural diagram of a grid-type converter according to an embodiment of the present invention; Figure 5B This is a network-type active frequency control diagram according to an embodiment of the present invention; Figure 6 This is a schematic diagram of a dual-inertia-center extended frequency response model according to an embodiment of the present invention; Figure 7A This is a frequency response curve of a dual inertia center with a grid-type power generation capacity of 10% according to an embodiment of the present invention. Figure 7B This is a frequency response curve of a dual inertia center with a grid-type power generation capacity of 50% according to an embodiment of the present invention. Figure 7C This is a frequency response curve of a dual inertia center with a grid-type power generation capacity of 90% according to an embodiment of the present invention. Figure 8 This is a curve illustrating the influence of the minimum inertia time constant under different capacities and RoCoF constraints on a dual inertia center according to an embodiment of the present invention. Figure 9 This is a steady-state frequency curve of a dual inertia center under different grid power generation ratios and control parameters according to an embodiment of the present invention. Figure 10 This is a schematic diagram of a 62-node power system; Figure 11A This is the frequency response curve of a hybrid AC / DC transmission network containing new energy sources with a grid-type power generation capacity of 10%. Figure 11B This is the frequency response curve of a hybrid AC / DC transmission network containing new energy sources with 50% of the grid-type power generation capacity. Figure 11C It is the frequency response curve of the AC / DC hybrid power transmission network containing new energy sources with 90% of the grid-type power generation capacity; Figure 12A This is the system output power curve of the first inertia center of the AC / DC hybrid transmission network containing new energy sources; Figure 12B This is a system output power curve of the second inertia center of the AC / DC hybrid transmission network containing new energy sources; Figure 13A It is a graph showing the impact of power interaction between power generation systems in a hybrid AC / DC transmission network containing new energy sources under different virtual impedances. Figure 13B It is a graph showing the influence of the angle of attack between power generation systems in a hybrid AC / DC transmission network containing new energy sources under different virtual impedances; Figure 14A It is an AC / DC hybrid transmission network containing new energy sources with different virtual inertial time constants. Curve showing the influence of synchronous machine inertia on output power; Figure 14B It is an AC / DC hybrid transmission network containing new energy sources with different virtual inertial time constants. Curve showing the influence of inertia output power on grid-type inertia; Figure 14C This is a graph showing the influence of the angle of attack between power generation systems on the AC / DC hybrid power-end network containing new energy sources under different virtual inertial time constants. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this invention are only for explaining this invention and are not intended to limit this invention.

[0031] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to other steps or units inherent in the device.

[0032] The terminology used in the various embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to limit the various embodiments of the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which the various embodiments of the invention pertain. The terms (such as those defined in a generally used dictionary) are to be interpreted as having the same meaning as in the context of the relevant technical field and are not to be interpreted as having an idealized or overly formal meaning, unless clearly defined in the various embodiments of the invention.

[0033] The embodiments of the present invention provide a frequency response analysis method and system based on dual inertia centers, which is applicable to the frequency response analysis of multi-resource frequency modulation systems with new energy penetration, and is conducive to realizing local frequency dynamic analysis of multi-resource frequency modulation systems and improving the accuracy of frequency response analysis.

[0034] Please see Figure 1 The flowchart illustrates a frequency response analysis method based on dual inertia centers according to an embodiment of the present invention, which includes the following steps.

[0035] S1 establishes frequency response models for various frequency regulation resources in the power system. These resources include synchronous generator units, grid-connected frequency regulation systems, and grid-connected frequency regulation systems.

[0036] S2, based on the frequency response model of various frequency regulation resources, constructs the first inertia center by aggregating the inertia of synchronous generator sets and the frequency regulation function of grid-connected systems, and constructs the second inertia center by aggregating the inertia of grid-connected systems and the frequency regulation function of supporting energy storage systems.

[0037] S3, the overall system frequency is obtained based on the frequency of the first inertia center and the frequency of the second inertia center.

[0038] Grid-connected frequency regulation systems cannot construct voltage and frequency on their own; they need to operate in tandem with the power grid via a phase-locked loop (PLL). Essentially, they are equivalent to current sources. Currently, widely used grid-connected wind turbines and renewable energy storage systems are mostly grid-connected converters. Grid-connected systems cannot actively provide inertia support, and as the scale increases, the overall system inertia decreases. This makes it difficult to provide necessary frequency response support when the system experiences disturbances, resulting in significant frequency fluctuations compared to conventional generating units.

[0039] Unlike grid-connected frequency regulation systems that rely on the voltage and frequency of the power grid, grid-connected frequency regulation systems actively provide voltage and frequency support by simulating the characteristics of synchronous generators, and are widely used in scenarios requiring autonomous regulation capabilities. A grid-connected converter can essentially be equivalent to an amplitude converter. and phase The equivalent internal resistance of a controlled voltage source, after the introduction of virtual impedance control, can be expressed as... The converter is connected to the AC power grid through a common grid connection point.

[0040] In traditional power system analysis, the inertial center frequency is often used as the main indicator to describe the overall frequency fluctuation of the system. Its calculation method is based on a weighted average of the inertia weights of each generator unit. However, the actual frequency fluctuations of different generators after a fault vary, with a smaller proportion of new energy generators often exhibiting larger frequency fluctuations. This local instability is "masked" by the averaging effect of the center frequency. Furthermore, grid-connected generators lack physical rotors and governor mechanisms, and conventional methods of aggregating the inertia of synchronous machines and grid-connected generators will lead to frequency response errors. Therefore, relying solely on the inertial center frequency to describe the frequency characteristics of a power system is no longer sufficient to meet the demands for local frequency dynamics under current complex operating conditions.

[0041] This invention addresses the increasing proportion of grid-connected devices in current power systems by constructing a dual inertiacenters model to more comprehensively describe the frequency response processes of synchronous and grid-connected power generation systems, as well as the power exchange between these systems. Based on traditional system frequency response models, a dual inertiacenters-based extended system frequency response model (DIESFR) is established. Considering the frequency regulation resources of a high-voltage power grid exporting large-scale AC / DC hybrid power grid, including synchronous generators, renewable energy generation, energy storage, DC power, and grid-connected converters, and integrating the above frequency response models, the dual inertiacenters model is used to analyze the frequency characteristics of such a grid.

[0042] In some implementations, the grid-connected frequency regulation system includes grid-connected wind turbines and grid-connected energy storage systems, while the grid-connected frequency regulation system includes grid-connected converters and grid-connected wind turbines. Furthermore, the grid-connected frequency regulation system also includes a high-voltage direct current transmission system employing a DC frequency limiting controller.

[0043] See Table 1, which lists the auxiliary power transfer functions for various types of frequency regulation resources. This embodiment considers the inertia of synchronous machines and grid-connected generation separately, with the first inertia center... i The system integrates the inertia of all synchronous generators and inertia-free frequency regulation equipment, such as grid-connected wind power generation, grid-connected energy storage, and DC frequency regulation functions; the second inertia center j It considers the grid inertia separately, and aggregates the inertia of all grid-type power generation and supporting energy storage devices.

[0044] Table 1 Characteristics of Multi-Type Hybrid FM Resources

[0045] In step S1, the specific process of establishing frequency response models for various frequency regulation resources in the power system is as follows.

[0046] (1) Synchronous generator set.

[0047] The frequency response model of a synchronous generator set is expressed as follows:

[0048] In the formula, The output frequency of the synchronous generator set. This is the gain coefficient. For high-pressure cylinder gain, The reheat time constant is R This represents the droop coefficient of the synchronous generator. This represents the frequency change value; For the Laplace operator.

[0049] The auxiliary power transfer function of the synchronous generator set is then expressed as:

[0050] (2) Grid-type wind turbine.

[0051] Grid-connected wind turbines controlled by converters cannot actively provide inertia support, and the overall system inertia decreases with increasing scale, making it difficult to provide necessary frequency response support when the system experiences disturbances. Therefore, the control strategy of the wind turbines is changed to the following frequency regulation control strategy: a strategy of applying comprehensive inertial control to the wind turbines by simulating the inertia response process and primary frequency regulation process of synchronous generators; providing inertial support by controlling the wind turbines to release the rotational kinetic energy stored in the rotor; and providing primary frequency regulation function through reserve capacity after reserving support power after load reduction.

[0052] The frequency response model of a grid-connected wind turbine with integrated inertial control output is expressed as follows:

[0053] in, To match the frequency regulation power of grid-connected wind turbines, For virtual inertial control parameters, These are the primary frequency modulation control parameters. To match the frequency regulation time constant of the grid-type fan, This represents the frequency change value. For the Laplace operator.

[0054] The auxiliary power transfer function of the grid-type wind turbine is then expressed as:

[0055] The frequency modulation power of the mesh fan will be adjusted. Power superimposed on the MPPT control output of the wind turbine The reference power of the wind turbine is obtained from the above. ,like Figure 2 The schematic diagram of the frequency response model of the wind turbine shown is as follows:

[0056] (3) Grid-connected energy storage system.

[0057] To ensure the safety and stability of the power system under the new circumstances, power sources should have primary frequency regulation capabilities, and a large number of new energy power plants should be equipped with energy storage services for peak shaving and frequency regulation in proportion. Traditional grid-connected new energy energy storage is mainly centralized electrochemical energy storage, which is essentially equivalent to a current source. The difference between it and new energy power generation is that the discharge time is fast and it can supplement the instantaneous power required by the grid, which can better make up for the difficulty of frequency regulation of new energy.

[0058] The frequency response mode of grid-connected energy storage adopts droop control, and the frequency response model is as follows: Figure 3 As shown, the frequency response model is expressed as:

[0059] in, To match the auxiliary output power of the grid-connected energy storage system, This is the energy storage frequency droop control coefficient. For energy storage control time constant, This represents the frequency change value. For the Laplace operator.

[0060] The auxiliary power transfer function of the grid-type energy storage system is then expressed as:

[0061] (4) High-voltage direct current transmission system.

[0062] High-voltage direct current (HVDC) transmission is an important method for inter-regional power transmission. However, while replacing traditional AC transmission lines, it also fragments the system's inertia, making it impossible to share inertia across regions. For networks that transmit large-scale renewable energy via multiple HVDC lines, a DC frequency limit controller (FLC) can be used to simulate the primary frequency regulation performance of a synchronous generator. By adjusting the power transmitted through the HVDC lines based on the frequency deviation, it can provide auxiliary power support for the system.

[0063] The principle of DC FLC control is that when a frequency deviation occurs, the proportional-integral controller obtains the power increment value, thereby changing the original DC line transmission power reference value. Typically, FLC control uses a reverse frequency deviation recovery model. When the frequency deviation improves and returns to the dead zone, the additional auxiliary power reference value of the inverse adjustment output of the integral element is zero. The frequency response model is as follows: Figure 4 As shown. When the frequency deviation exceeds the control dead zone, the additional positive and negative auxiliary power... and for:

[0064] in, , These represent the forward and reverse auxiliary power outputs of the high-voltage direct current transmission system when the frequency deviation exceeds the control dead zone, respectively. , These are the forward and reverse dead zone values ​​controlled by the DC frequency limit controller. , These are the proportional and integral coefficients of the PI controller, respectively. This represents the frequency change value. The DC frequency modulation time constant is... This is the total transmitted power value after DC additional power adjustment.

[0065] The frequency response model of a high-voltage direct current transmission system is expressed as follows:

[0066] in, This represents the total transmission power of the high-voltage direct current (HVDC) transmission system after DC power adjustment. , These are the proportional and integral coefficients of the PI controller, respectively. The DC frequency modulation time constant is... This represents the frequency change value. For the Laplace operator.

[0067] The auxiliary power transfer function of the high-voltage direct current transmission system is expressed as follows:

[0068] (5) Grid-type converter.

[0069] Grid-type converters simulate the physical characteristics of synchronous generators using virtual synchronization technology to achieve self-synchronization. Therefore, grid-type converters can essentially be equivalent to amplitude converters. and phase The equivalent internal resistance of a controlled voltage source, after the introduction of virtual impedance control, can be expressed as... The equivalent structure diagram of the converter after it is connected to the AC power grid through a common grid connection point is as follows: Figure 5A As shown. The frequency response model of the grid-type converter can then be expressed as:

[0070] in, For the output electromagnetic power of the grid-type converter, E For the grid-connected system potential, For the difference in effort angle, The equivalent voltage of a grid-type converter. This is a virtual impedance.

[0071] For functions such as frequency regulation and inertia, the rotor motion equations of a synchronous generator and the primary frequency regulation power-frequency static characteristics are generally used for simulation. Therefore, the network-type simulation equations are:

[0072] in, H It is the inertial constant. , , These are mechanical power, electromagnetic power, and rated active power, respectively. The damping coefficient is... This represents the droop coefficient of the synchronous generator. This is the gain coefficient. For high-pressure cylinder gain, The reheat time constant is This is the primary frequency modulation power. This represents the frequency change value. For the Laplace operator, This represents the change in the angle difference.

[0073] By introducing network-based simulation equations, the converter acquires inertial response and droop functionality in its external characteristics, and possesses a control structure similar to that of a synchronous machine, such as... Figure 5B The network-type active power frequency control diagram shown illustrates that when external load changes induce disturbances... After the inertial response, the grid-type converter adjusts its frequency deviation using a unit adjustment coefficient. Automatic adjustment of mechanical power This value ensures that the power remains synchronized.

[0074] Then, the auxiliary power transfer function of the grid-type converter is expressed as:

[0075] In the formula, For auxiliary power of grid-type converters, , They are nodes i, j The frequency change value, = , representing the change in work angle difference.

[0076] (6) Grid-type fan.

[0077] The frequency response model of a synchronously controlled grid-type wind turbine is expressed as:

[0078] In the formula, For the acceleration power of grid-type wind turbines, This represents the frequency change value. For the Laplace operator, The inertial time constant, is the damping coefficient.

[0079] The auxiliary power transfer function of a synchronously controlled grid-type wind turbine is expressed as:

[0080] The frequency response model of a grid-type wind turbine using a virtual debugger is expressed as follows:

[0081] In the formula, For auxiliary output power of grid-type wind turbines, The unit adjustment coefficient, It is a time constant. This represents the frequency change value. For the Laplace operator.

[0082] The auxiliary power transfer function of the grid-connected wind turbine using a virtual debugger is then expressed as:

[0083] Based on the aforementioned dual-center-of-inertia model, the DIESFR model is used to analyze the frequency characteristics of a hybrid AC / DC power grid for large-scale renewable energy transmission, yielding the following results: Figure 6 The extended frequency response model with two centers of inertia is shown, where α First center of inertia i The proportion of synchronous machines in the system λ The proportion of energy storage capacity allocated to wind turbines; , , These are the DC line transmission capacity ratio, the ratio and the integral coefficient, respectively.

[0084] The external disturbance power of the system is Neglecting inter-machine oscillations, the disturbance power distributed among each center of inertia is determined by the inertial time constant and the installed capacity, expressed as:

[0085] In the formula, First center of inertia i The allocated disturbance power, , The first center of inertia i Intra-system frequency modulation resources k Its inertial constant and capacity; First center of inertia i Inertia weight; , The first center of inertia i Total capacity and all centers of inertia (first center of inertia) i +Second center of inertia j (Total capacity)

[0086] Based on the frequency modulation transfer function of each resource, write the expression for the frequency change of each inertia center system:

[0087] in , Center of inertia i The equivalent inertial time constant and equivalent damping coefficient; , , , , These are, respectively, the primary frequency regulation power of the synchronous generator, the auxiliary power of the grid-connected wind turbine, the auxiliary power of the grid-connected energy storage, the DC auxiliary power, and the inter-system transmission power.

[0088] Based on the frequency variation expressions of each inertia center system mentioned above, the first inertia center can be obtained. i The frequency expression is:

[0089] in,

[0090]

[0091] In the formula, First center of inertia i frequency, First center of inertia i The allocated disturbance power, This represents the external disturbance power of the system. First center of inertiai Total capacity Second center of inertia j Total capacity First center of inertia i Second center of inertia j The sum of the total capacity, For the Laplace operator, Second center of inertia j Inertia weights, Y, For auxiliary functions, The inertia constant of the first center of inertia, The damping coefficient at the first center of inertia. The proportion of synchronous machines. This is the auxiliary power transfer function of the synchronous generator governor. For the auxiliary power transfer function of virtual inertial control of grid-type wind turbines, The proportion of energy storage capacity allocated to wind turbines. To match the auxiliary power transfer function of grid-type energy storage droop control, This is the proportional coefficient for the transmission capacity of DC lines. This is the auxiliary power transfer function for a DC transmission FLC. The inertia constant of the second center of inertia, The damping coefficient at the second center of inertia. For the auxiliary power transfer function of the virtual speed governor of the grid-type wind turbine, This is a virtual impedance.

[0092] Second center of inertia j The frequency expression is:

[0093] in,

[0094] In the formula, Second center of inertia j frequency, Second center of inertia j The allocated disturbance power, For the Laplace operator, First center of inertia i frequency, For auxiliary functions, This is a virtual impedance.

[0095] From the frequency expressions of each center of inertia, the expression for the average frequency of the overall center of inertia can be obtained as follows:

[0096] in, For the overall system frequency, First center of inertia i frequency, Second center of inertia j frequency, First center of inertia i Inertia weight, Second center of inertia j Inertia weight.

[0097] Furthermore, the present invention analyzes the frequency characteristics of the system based on the above dual inertia model. The analysis items include: (1) the influence of the dual inertia center on the frequency response; and (2) the influence of grid-type power generation on the frequency index.

[0098] (1) The influence of dual centers of inertia on frequency response.

[0099] Traditional SFR (Synchronous Frequency Response) models aggregate synchronous generators into a single equivalent device. With the addition of new energy sources, to describe their primary frequency regulation characteristics, their speed regulation characteristics are aggregated with those of the synchronous machine governor according to their contribution ratio. This only affects the magnitude of the system's power response to disturbances, and the overall model remains undistorted. However, with the development of grid-based power generation, unlike traditional converters which hinder the ability of rotating components to express inertia, grid-based power generation can provide instantaneous support during disturbances, much like synchronous generators. The large capacity and manually configurable inertia parameters of grid-based power generation have a significant impact on the system's internal frequency response. Simply aggregating the inertia of grid-based new energy sources with that of synchronous machines fails to distinguish their inertia response processes. Furthermore, due to the difference in inertia magnitude, the frequency responses of the two inertia centers to disturbances are also different; using a single inertia center to describe the frequency response process will result in distortion.

[0100] Taking the parameters of a real renewable energy transmission grid as an example, after converting grid-connected wind turbines to grid-connected ones, the system frequency before the disturbance is 50Hz. After a sustained step disturbance with a sudden 5% increase in load, the frequency response of different grid-connected power generation ratios is as follows: Figures 7A-7C As shown, Figure 7A The frequency response of the grid-connected power generation capacity was demonstrated at 10%. Figure 7B The frequency response of the grid-connected power generation capacity at 50% was demonstrated. Figure 7C It demonstrates the frequency response of the grid-connected power generation capacity at 90%.

[0101] Depend on Figures 7A-7C It can be seen that the response processes of the two center-of-inertia models are significantly different. When the proportion of grid-connected power generation is low, the system average frequency is... Frequency of the synchronous machine inertia system Similar. As the proportion of grid-connected power generation increases, Gradually approaching the frequency of a network-type inertial system Therefore, the average frequency or the frequency response of the single center of inertia model cannot represent the actual response process of each system, and the error is relatively large. Especially when the proportion is moderate, the average frequency cannot express the response process of the two systems.

[0102] For the entire frequency response process, as the proportion of grid-connected power generation increases, the time it takes for the frequency to drop to its lowest point... The transition time to the steady-state frequency is advanced, resulting in a reduction in the system damping ratio. This is because grid-connected generators lack a physical speed governor; their operation relies on the time constant of a virtual speed governor controlled by the converter. (0.5-2s) Reheat time constant compared to synchronous generator (6-12s) is much smaller, and the overall frequency response speed of the system is faster.

[0103] (2) The impact of grid-connected power generation on frequency indicators.

[0104] Consider the first center of inertia mentioned above i Second center of inertia j The step response of the frequency expression is that of a high-order system, making it difficult to directly obtain the time-domain solution. Therefore, it is necessary to find the minimum point of the frequency drop. The following approximations are made: The time constant of the synchronous generator speed control system on a large time scale is ignored; the distance between the two systems is ignored, and a strong correlation between them is considered. The value approaches zero; the frequency regulation system of the grid-connected wind turbine is combined with the primary frequency regulation of the synchronous generator. The maximum frequency drop at this point is a conservative estimate, smaller than the actual value. If the frequency regulation parameters satisfy the minimum frequency constraint under this conservative estimate, then the actual system must also satisfy it. The corresponding time-domain solution of the frequency response is:

[0105] in,

[0106] and These are the equivalent primary frequency modulation parameters.

[0107] The time-domain form of the system's frequency response after the inverse Laplace transform is:

[0108] The time at which the maximum frequency deviation occurs is ,for The corresponding time, then for:

[0109] according to and The two equations can calculate the corresponding indices for the lowest frequency drop point. Table 2 shows the lowest frequency point and its corresponding time for different grid-type power generation capacities. At low capacity ratios, the low-order model has a smaller error; however, as the capacity ratio increases, the error increases due to neglecting the influence of the grid-type governor's time constant. The low-order model can be used for conservative estimation of the minimum parameter settings for the grid-type governor.

[0110] Table 2 Comparison of model frequencies for power generation ratios of different grid configurations

[0111] The rate of change of frequency (RoCoF) of a power system reflects the speed at which the system frequency changes during disturbances. RoCoF is a crucial indicator of the system's dynamic frequency response and directly relates to whether the system frequency reaches its dynamic safety limits. Typically, the rate of change of frequency reaches its maximum value at the initial stage of a frequency disturbance. According to Laplace's initial value theorem, this value originates from the first center of inertia mentioned above. i Second center of inertia j The maximum value of RoCoF for the two systems can be obtained from the frequency expression:

[0112] in, The system's rated frequency, This is the equivalent inertial time constant of the entire system.

[0113] The maximum value of RoCoF for both systems indicates that the initial RoCoF for each center of inertia is the same, and its magnitude is only related to the magnitude of the disturbance. and equivalent inertial time constant This is relevant. Therefore, the minimum inertial time constant of the grid-type power generation can be calculated based on the maximum initial RoCoF constraint. for:

[0114] Then the minimum inertial time constant can be obtained. The relationship with RoCoF constraints, such as Figure 8 As shown, Figure 8 The minimum inertia time constant is shown for different capacities and RoCoF constraints. H j The impact of ).

[0115] Depend on Figure 8It can be seen that when the system has stricter requirements for the RoCoF index, a larger grid-connected power generation system inertial time constant is needed, and the required inertia level increases accordingly with the increase of the disturbance magnitude. For a certain RoCoF index requirement, the larger the grid-connected power generation capacity, the smaller the required grid-connected power generation system inertial time constant can be. This is because the synchronous machine system has not been replaced, and simply increasing the grid-connected power generation capacity can improve the overall inertial time constant level of the system. Thanks to the parameter control principle of the converter, the grid-connected power generation... The adjustable range of parameters is much larger than the conventional value, which allows RoCoF to be adjusted more flexibly. However, sufficient energy storage is required to provide the corresponding power for the inertia, otherwise it will cause a serious secondary frequency drop.

[0116] steady-state frequency of power system The deviation can reflect the system's ability to resist active disturbances through a single frequency modulation on a short time scale. According to the final value theorem of the Laplace transform, the deviation is determined by the first center of inertia. i Second center of inertia j The frequency expression can be obtained as follows:

[0117] In the formula, the steady-state frequency of the two centers of inertia Equal to, and consistent with the single center of inertia. Under a certain grid-connected power generation ratio, the steady-state frequency... Frequency regulation parameters of grid-connected power generation and energy storage frequency regulation parameters Strongly correlated, their relationship is as follows Figure 9 As shown, Figure 9 The effects of different grid-connected power generation ratios and control parameters on steady-state frequency are shown.

[0118] The following modeling and simulation of a planned new energy transmission system in a certain region is performed, and a dual-inertia frequency response model of the above embodiment of the present invention is established for it, verifying the practical application effectiveness of the dual-inertia center model of the present invention.

[0119] like Figure 10 The diagram shows a 62-node power system diagram of a regional renewable energy transmission system, including 5 thermal power units (B1-B5) and 11 wind farms (D1-D11). The basic capacity ratio of thermal power units to grid-connected wind turbines is 6:4. Energy storage for the wind turbines is configured at 10% of the system capacity, and DC transmission capacity accounts for 30% of the total capacity. The system's power deficit is set at [missing value]. A hybrid AC / DC transmission network incorporating new energy sources was constructed based on the PSASP full-time simulation software platform.

[0120] (1) Verification of the dual-inertia center frequency response model of AC / DC hybrid transmission network containing new energy sources.

[0121] Set a step disturbance for a sudden increase in load The magnitude is 15%, and the system frequency before the disturbance is 50Hz. The system frequency response of grid-connected power generation with different capacity proportions planned for existing wind power bases is shown in the following results. Figures 11A-11C As shown, Figure 11A The frequency response of the grid-connected power generation capacity at 10% is shown. Figure 11B The system frequency response with 50% of the grid-connected generating capacity is shown. Figure 11C The system frequency response is shown when the grid-connected power generation capacity is 90%.

[0122] As shown in the figure, the simulation results are consistent with the theoretical analysis conclusions above. Due to electrical distance, the average frequency impact can be represented by the receiving-end output frequency for the receiving-end network. The larger the proportion of grid-type power generation, the greater the weight of its impact on the frequency response waveform. For the sending-end network, the average frequency cannot distinguish the frequency differences between inertia centers, so it is necessary to obtain the corresponding frequency change curves using the corresponding inertia centers separately.

[0123] The dual-inertia model, which separates grid-connected power generation and synchronous machine power generation, can clearly illustrate the power response process of each system, such as... Figure 12A-12B As shown, Figure 12A The first center of inertia is shown. i The system output power, Figure 12B The second center of inertia is shown. j The system output power. The set system disturbance magnitude. It is 10%. As can be observed from the figure, after combining the additional power of all outputs, the perturbed center of inertia... i and center of inertia j The per-unit values ​​of the overall output response power are all around 10%, which is consistent with the magnitude of the disturbance power, providing additional power to the system to compensate for the power lost due to the disturbance. At the center of inertia... i Within the system, the synchronous generator provides output power for the inertial response at the moment of disturbance. The power of the inertial response gradually decreases over time, while the synchronous rotor decelerates and converts its own kinetic energy into supporting power. When the inertial response power falls below zero, the rotor absorbs power from the system; this power source is the power generated by the primary frequency regulation. At the center of inertia... j Within the system, the output response power is roughly in line with the center of inertia. i resemblance.

[0124] Considering factors affecting power response other than capacity ratio, further distinguish different virtual impedances. The impact on the electrical distance and interactive power between synchronous machine center of inertia systems and network-type systems, such as Figures 13A-13B As shown, Figure 13AThe effect of different virtual impedances on the interactive power between power generation systems is shown. Figure 13B The effect of different virtual impedances on the angle of attack between power generation systems is shown.

[0125] according to Figures 13A-13B It can be seen that with virtual impedance As the virtual impedance decreases, the power supplied by the grid-connected generator to the synchronous generator system increases, alleviating the overall system frequency drop and correspondingly reducing the generator angle-of-attack difference between the two systems. Interharmonic oscillations will occur when the virtual impedance is less than 0.1, so the lower limit is set to 0.1. When the virtual impedance exceeds 2, the supplied power can be basically ignored.

[0126] In summary, the smaller the virtual impedance value, the more ideal the frequency support effect, the greater the interactive power between generators, the additional power support for the power generation system being supported, the relief of frequency regulation power pressure, and the weakening of frequency fluctuation differences between power generation systems.

[0127] (2) The influence of grid-type power generation parameters on frequency response of AC / DC hybrid transmission network containing new energy sources.

[0128] Virtual inertial time constant set by grid-type power generation Besides affecting the initial power allocation during disturbances, it also affects the power angle difference between power generation systems, thus influencing the magnitude and direction of interconnected power. This is done when setting virtual impedance. Given a constant of 0.1, the inertial time constant of the network structure is... The analysis and simulation results are as follows: Figures 14A-14C .

[0129] Figures 14A-14C The initial inertial response power emitted by each center of inertia is shown under different inertial time constants. Figure 14A Different virtual inertial time constants are shown. The impact on the output power of the synchronous machine's inertia. Figure 14B Different virtual inertial time constants are shown. The impact on the output power of the grid-type inertia. Figure 14C Different virtual inertial time constants are shown. The impact on the angle of attack between power generation systems.

[0130] In the early stages of the disturbance It is possible to see the maximum power of the initial response when When the value is 0, the network-type equipment is equivalent to the follow-the-network type, and does not respond to frequency changes in the early stage of disturbance, with a response output value of zero, only emitting auxiliary power during one frequency modulation process. With... Increasing this will affect the inertia weight. The magnitude of this value causes a decrease in the initial inertial response power of the synchronous generator to disturbances. This manifests as grid-connected power generation equipment bearing a larger share of the disturbance power, resulting in a corresponding increase in the initial inertial response power of the grid-connected power generation. When the virtual inertial time constant of the grid-connected power generation is set... When the inertia exceeds 3, the aggregated inertia level of grid-connected power generation equipment surpasses the inherent inertia of synchronous generators. For the power system, this inertia will bear the majority of the inertial response power during disturbances. Simultaneously, the power angle difference between synchronous generators and grid-connected power generation changes from positive to negative. Figure 14C As shown, the power output direction of the interconnection between the two centers of inertia will be reversed, transforming into a synchronous generator generating power to support the grid-type system.

[0131] In summary, this invention addresses the issue of increased frequency regulation demands on power systems due to rising renewable energy penetration, reduced inertia, and decreased frequency regulation capabilities. To study the frequency stability of grid-connected renewable energy systems integrated into the power system, this invention first quantitatively analyzes the frequency characteristics of various grid-connected frequency regulation resources and grid-connected generation, while also considering the difference in inertia between grid-connected generation and conventional synchronous machines. A dual-inertia center frequency response model incorporating multiple frequency regulation resources is established. Then, based on this model, the impact of grid-connected renewable energy parameters on frequency safety indicators such as maximum frequency deviation, rate of change of frequency, and steady-state deviation is quantitatively analyzed. Finally, using a real AC / DC hybrid renewable energy sending-end network as an example, simulations verify the effectiveness of the proposed method, and the impact of grid-connected generation parameters and virtual impedance on inter-system interconnection power is further analyzed.

[0132] Embodiments of the present invention also provide a frequency response analysis system based on dual centers of inertia, comprising: The frequency response modeling module is used to establish frequency response models for various frequency regulation resources in the grid system; among which, frequency regulation resources include synchronous generator sets, grid-connected frequency regulation systems, and grid-connected frequency regulation systems. The dual inertia center modeling module is used to construct a first inertia center and a second inertia center based on the frequency response models of various frequency regulation resources. The first inertia center is obtained by aggregating the inertia of synchronous generator sets and the frequency regulation function of grid-connected frequency regulation systems, while the second inertia center is obtained by aggregating the inertia of grid-connected frequency regulation systems and the frequency regulation function of supporting energy storage systems. The system frequency analysis module is used to obtain the overall system frequency based on the frequency of the first inertia center and the frequency of the second inertia center.

[0133] Embodiments of the present invention also provide an electronic device comprising a processor and a memory, wherein the number of processors may be one or more. The memory, as a computer-readable storage medium, can be used to store software programs, computer-executable programs, and modules. The processor executes various functional applications and data processing of the electronic device by running the software programs, instructions, and modules stored in the memory, thereby implementing the frequency response analysis method based on dual inertia centers according to any of the above embodiments of the present invention.

[0134] The memory may primarily comprise a program storage area and a data storage area. The program storage area may store the operating system and at least one application program required for a given function; the data storage area may store data created based on terminal usage. Furthermore, the memory may include high-speed random access memory (RAM) and non-volatile memory, such as at least one disk storage device, flash memory, or other non-volatile solid-state storage device. In some instances, the memory may further include memory remotely located relative to the processor, which can be connected to the electronic device via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks (LANs), mobile communication networks, and combinations thereof.

[0135] Embodiments of the present invention also provide a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the frequency response analysis method based on dual inertia centers according to any embodiment of the present invention.

[0136] The computer storage medium of this invention can be any combination of one or more computer-readable media. A computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. A computer-readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of computer-readable storage media (a non-exhaustive list) include: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this invention, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0137] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. Computer-readable signal media may also be any computer-readable medium other than computer-readable storage media, capable of sending, propagating, or transmitting programs for use by or in connection with an instruction execution system, apparatus, or device.

[0138] Embodiments of the present invention also provide a computer program product that, when run on a computer, causes the computer to execute the frequency response analysis method based on dual inertia centers according to any of the above embodiments of the present invention.

[0139] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A frequency response analysis method based on dual centers of inertia, characterized in that, include: Frequency response models are established for various frequency regulation resources in the power system; the frequency regulation resources include synchronous generator sets, grid-connected frequency regulation systems, and grid-connected frequency regulation systems. Based on the frequency response models of various frequency regulation resources, a first inertia center and a second inertia center are constructed. The first inertia center is obtained by aggregating the inertia of synchronous generator sets and the frequency regulation function of grid-connected frequency regulation systems, while the second inertia center is obtained by aggregating the inertia of grid-connected frequency regulation systems and the frequency regulation function of supporting energy storage systems. The overall system frequency is obtained based on the frequencies of the first inertia center and the second inertia center.

2. The frequency response analysis method based on dual centers of inertia according to claim 1, characterized in that, The grid-connected frequency regulation system includes grid-connected wind turbines and grid-connected energy storage systems, while the grid-connected frequency regulation system includes grid-connected converters.

3. The frequency response analysis method based on dual centers of inertia according to claim 2, characterized in that, The following frequency regulation control strategy is adopted for the grid-connected wind turbine: Inertial control is applied to the wind turbine by simulating the inertial response process and primary frequency regulation process of a synchronous generator. Inertial support is provided by controlling the wind turbine to release the rotational kinetic energy stored in the wind turbine. The load reduction reserve power is used to provide primary frequency regulation function through the spare capacity; The frequency response model of the grid-connected wind turbine is expressed as follows: in, To match the frequency regulation power of grid-connected wind turbines, For virtual inertial control parameters, These are the primary frequency modulation control parameters. To match the frequency regulation time constant of the grid-type fan, This represents the frequency change value. For the Laplace operator.

4. The frequency response analysis method based on dual centers of inertia according to claim 2, characterized in that, The grid-connected energy storage system adopts a droop control mode, and the frequency response model of the grid-connected energy storage system is expressed as follows: in, To match the auxiliary output power of the grid-connected energy storage system, This is the energy storage frequency droop control coefficient. For energy storage control time constant, This represents the frequency change value. For the Laplace operator.

5. The frequency response analysis method based on dual centers of inertia according to claim 2, characterized in that, The grid-connected frequency regulation system also includes a high-voltage direct current transmission system employing a DC frequency limiting controller; The frequency regulation strategy of the high-voltage direct current transmission system is as follows: the DC frequency limit controller simulates the primary frequency regulation process of the synchronous generator, and the DC line transmission power is changed according to the frequency deviation value to provide auxiliary power support. The frequency response model of the high-voltage direct current transmission system is expressed as follows: in, This represents the total transmission power of the high-voltage direct current (HVDC) transmission system after DC power adjustment. , These are the proportional and integral coefficients of the PI controller, respectively. The DC frequency modulation time constant is... This represents the frequency change value. For the Laplace operator.

6. The frequency response analysis method based on dual centers of inertia according to claim 2, characterized in that, The grid-type converter simulates the physical characteristics of a synchronous generator through virtual synchronization technology to achieve self-synchronization. The frequency response model of the grid-type converter is expressed as follows: in, For the output electromagnetic power of the grid-type converter, E For the grid-connected system potential, For the difference in effort angle, The equivalent voltage of a grid-type converter. This is a virtual impedance.

7. The frequency response analysis method based on dual centers of inertia according to claim 1, characterized in that, The frequency response model of the synchronous generator set is expressed as follows: in, The output frequency of the synchronous generator set. This is the gain coefficient. For high-pressure cylinder gain, The reheat time constant is R This represents the droop coefficient of the synchronous generator. This represents the frequency change value. For the Laplace operator.

8. The frequency response analysis method based on dual centers of inertia according to claim 1, characterized in that, The frequency of the first center of inertia is expressed as: in, The frequency of the first center of inertia The disturbance power allocated to the first center of inertia. This represents the external disturbance power of the system. The total capacity of the first center of inertia. The total capacity of the second center of inertia. It is the sum of the total capacity of the first center of inertia and the second center of inertia. For the Laplace operator, The inertia weight of the second center of inertia, Y, For auxiliary functions, The inertia constant of the first center of inertia, The damping coefficient at the first center of inertia. The proportion of synchronous machines. This is the auxiliary power transfer function of the synchronous generator governor. For the auxiliary power transfer function of virtual inertial control of grid-type wind turbines, The proportion of energy storage capacity allocated to wind turbines. To match the auxiliary power transfer function of grid-type energy storage droop control, This is the proportional coefficient for the transmission capacity of DC lines. This is the auxiliary power transfer function for a DC transmission FLC. The inertia constant of the second center of inertia, The damping coefficient at the second center of inertia. For the auxiliary power transfer function of the virtual speed governor of the grid-type wind turbine, Virtual impedance; The frequency of the second center of inertia is expressed as: in, The frequency of the second center of inertia The disturbance power allocated to the second center of inertia. For the Laplace operator, The frequency of the first center of inertia For auxiliary functions, This is a virtual impedance.

9. The frequency response analysis method based on dual centers of inertia according to claim 8, characterized in that, The overall system frequency, obtained based on the frequencies of the first and second inertia centers, is expressed as follows: in, For the overall system frequency, The frequency of the first center of inertia The frequency of the second center of inertia The inertia weight of the first center of inertia. The inertia weight of the second inertia center.

10. A frequency response analysis system based on dual centers of inertia, characterized in that, include: The frequency response modeling module is used to establish frequency response models for various frequency regulation resources in the grid system; the frequency regulation resources include synchronous generator sets, grid-connected frequency regulation systems, and grid-connected frequency regulation systems. The dual inertia center modeling module is used to construct a first inertia center and a second inertia center based on the frequency response models of various frequency regulation resources. The first inertia center is obtained by aggregating the inertia of synchronous generator sets and the frequency regulation function of grid-connected frequency regulation systems, while the second inertia center is obtained by aggregating the inertia of grid-connected frequency regulation systems and the frequency regulation function of supporting energy storage systems. The system frequency analysis module is used to obtain the overall system frequency based on the frequency of the first inertia center and the frequency of the second inertia center.

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