New energy unit frequency distribution analysis method and device based on comprehensive inertia control

Abstract

The invention discloses a new energy unit frequency distribution analysis method and device based on comprehensive inertia control, and the method comprises the steps: constructing a wind turbine generator comprehensive inertia control model according to the characteristics of a new energy unit; establishing a power system frequency response model considering comprehensive inertia control according to a traditional thermal power generating unit frequency response model and the comprehensive inertia control model of the wind turbine generator; according to the influence of grid connection of the wind generating set on the frequency space characteristics of the novel power system, combining the obtained frequency deviation of the power system, constructing a frequency response space distribution characteristic model of the power system, and obtaining the frequency response space distribution characteristics of the power system; and setting a dispersion degree coefficient, and carrying out quantitative evaluation on the power system frequency response spatial distribution characteristics. Based on a system node frequency deviation expression, factors influencing power grid frequency space distribution characteristics are analyzed, and a mathematical model of the frequency space distribution characteristics is provided.

Description

Technical Field

[0001] The present invention relates to the technical field of frequency analysis of new energy power systems, and in particular to a frequency distribution analysis method and device for new energy units based on comprehensive inertia control. Background Art

[0002] When the power system is in operation, it often suffers from power imbalance due to disturbance factors such as load changes, line faults, and unit start-up and shutdown. During the active-frequency response process, the frequency will show a more obvious spatial distribution characteristic. The spatial distribution characteristics of the power grid frequency refer to the differences in the frequency of each node in time and space after the power grid is disturbed. With the access of new energy units and a large number of power electronic components to the power grid, the inertia level in some areas has dropped significantly, resulting in the increasingly obvious frequency spatial distribution characteristics, which seriously affects the protection, control, and analysis of the system frequency. The proportion of new energy units in the power grid is getting higher and higher, and new energy units may become the main "frequency regulation role" of the power system. It is feasible to improve the spatial distribution characteristics of the power grid frequency through virtual inertia control of new energy units. Traditional virtual inertia control is currently a commonly used frequency regulation method for new energy units, but in actual applications, the inertia support it provides to the power system cannot guarantee the stability of the frequency of the new power system. Therefore, in order to ensure the safe and stable operation of the new power system, it is necessary to further consider the inertia control method of new energy units to improve the frequency spatial distribution characteristics of the new power system.

[0003] At present, domestic scholars have done a lot of research on the spatial distribution characteristics of power grid frequency. In the "Study on the Dynamic Spatial Distribution Characteristics and Influence Mechanism of Frequency in Large-Scale Power Grids", the disturbance propagation in the power grid is regarded as a "frequency wave" and the transmission line is regarded as a propagation medium. With the help of wave theory, a spatial evolution model of power grid frequency dynamics taking into account the spatial distribution characteristics is established. Through empirical orthogonal functions and other methods, the spatial distribution characteristics of frequency dynamic response are analyzed. "Study on High-order Frequency Response Model and Spatial Dynamic Distribution Relationship of Wide-area Power System" proposes a high-order frequency response model of the power system based on the traditional SFR (System Frequency Response, SFR) model, which improves the accuracy of the system frequency response model to a certain extent, and quantitatively analyzes the influence of generator inertia distribution, the shortest electrical distance, different disturbance positions and disturbance sizes on the frequency spatial distribution characteristics. However, the above research objects are traditional power systems, and the impact of new energy units is not considered, so it is difficult to apply to new power systems. "Research on Frequency Distribution Characteristics of Wide Area Power Grid Based on Data Mining Technology" uses time series data mining technology based on KNN (K-Nearest Neighbor Classification, KNN) classification algorithm and cross-correlation function analysis method to study the spatial distribution characteristics of power grid frequency. Although this method can more intuitively represent the spatial distribution characteristics of frequency with images, it does not analyze the reasons for the spatial distribution characteristics of power grid frequency, and it is difficult to clarify the mechanism that affects the spatial distribution characteristics of frequency, and it is impossible to improve the spatial distribution characteristics of frequency on the basis of this study. "Analysis of Spatial Distribution Characteristics of Frequency in New Energy Power System" combines the frequency response characteristics of each component in the new energy power system, establishes a frequency dynamic analytical model taking into account the spatial distribution characteristics, and studies and analyzes the spatial distribution characteristics of frequency in new energy power systems with different structures. However, it does not consider that the virtual inertia of new energy units and other controls bring certain support capabilities for the frequency of the power grid to new energy units, and does not propose corresponding methods to solve the obvious problem of spatial frequency characteristics of new power systems, and cannot guarantee the frequency stability of new power systems.

[0004] Therefore, it is urgent to study new frequency stability control methods for power systems with high penetration rates. Summary of the invention

[0005] To this end, the present invention provides a frequency distribution analysis method and device for a new energy unit based on comprehensive inertia control. Aiming at the increasingly obvious problem of frequency spatial distribution characteristics of new power systems, a comprehensive inertia control method is proposed on the basis of a traditional single virtual inertia control method. In combination with the frequency response model of traditional thermal power units, a power system frequency response model including new energy comprehensive inertia control is established. Based on the system node frequency deviation expression, the factors affecting the frequency spatial distribution characteristics of the power grid are analyzed, and a mathematical model for describing the frequency spatial distribution characteristics is proposed. In order to quantitatively analyze the frequency spatial distribution characteristics of system nodes, an inertia evaluation index for analyzing the frequency spatial distribution characteristics is proposed.

[0006] In order to achieve the above object, the present invention provides the following technical solution: A frequency distribution analysis method for a new energy unit based on comprehensive inertia control, comprising:

[0007] According to the characteristics of new energy units, a comprehensive inertia control model of wind turbine units is constructed; the comprehensive inertia control model of wind turbine units is used to alleviate the frequency-space characteristics of the power system;

[0008] According to the frequency response model of the thermal power unit, combined with the comprehensive inertia control model of the wind turbine unit, a power system frequency response model considering comprehensive inertia control is established; the frequency deviation of the power system is obtained through calculation and processing of the power system frequency response model considering comprehensive inertia control;

[0009] According to the influence of the grid connection of wind turbines on the frequency spatial characteristics of the power system, combined with the obtained frequency deviation of the power system, a power system frequency response spatial distribution characteristic model is constructed; and the power system frequency response spatial distribution characteristic is obtained by calculation and processing of the power system frequency response spatial distribution characteristic model;

[0010] A dispersion degree coefficient is set, and the spatial distribution characteristics of the frequency response of the power system are quantitatively evaluated by the dispersion degree coefficient.

[0011] As a preferred solution of the frequency distribution analysis method of new energy units based on comprehensive inertia control, the inertia control power increment, torque control increment and active power increment provided to the system of the wind turbine unit are calculated by the comprehensive inertia control model of the wind turbine unit;

[0012] The calculation formulas for the inertia control power increment, the torque control increment, and the active power increment provided to the system of the wind turbine generator set are respectively:

[0013]

[0014] P ref =P f -ΔP t P

[0015] Where P f , ΔP t , P ref They are the inertia control power increment, torque control increment and active power increment provided to the system of the wind turbine. K d , K p , K t are virtual inertia control coefficient, droop control coefficient, and torque control coefficient respectively; s is a constant in the automatic control theory; T d is the filter time constant; Δf, Δω r are frequency deviation and rotor speed deviation respectively; ω ro is the initial speed of the wind turbine rotor.

[0016] As a preferred solution of the frequency distribution analysis method of new energy units based on comprehensive inertia control, in the process of obtaining the frequency deviation of the power system through the calculation and processing of the power system frequency response model considering comprehensive inertia control, the calculation expression of the frequency deviation is:

[0017]

[0018] Where Δf sys is the power system frequency deviation; ΔP sys is the power disturbance of the power system; H sys is the equivalent inertia of the power system; D is the damping coefficient of the thermal power unit; α is the penetration rate of the new energy unit, and satisfies 0<α<1; G i (s) is the speed governor characteristic of the thermal power unit.

[0019] As a preferred solution of the frequency distribution analysis method of new energy units based on comprehensive inertia control, the mathematical expression of the power system frequency response spatial distribution characteristic model is:

[0020]

[0021] Where Δf i is the frequency deviation of node i; η P(i) , η H(i) are active power disturbance distribution coefficient and inertia distribution coefficient respectively; H i is the inertia of node i; Δp i The active power injected into each node; ΔP sys The disturbance of the power system.

[0022] As a preferred solution of the frequency distribution analysis method of new energy units based on comprehensive inertia control, the expression of the dispersion coefficient is:

[0023]

[0024] Where θ is the dispersion coefficient; Δf max,COI is the maximum deviation of the inertial center frequency; is the maximum frequency deviation of each node; m is the number of nodes in the system.

[0025] The present invention also provides a frequency distribution analysis device for a new energy unit based on comprehensive inertia control, based on the above frequency distribution analysis method for a new energy unit based on comprehensive inertia control, comprising:

[0026] A wind turbine integrated inertia control model building module is used to build a wind turbine integrated inertia control model according to the characteristics of the new energy unit; the wind turbine integrated inertia control model is used to alleviate the frequency-space characteristics of the power system;

[0027] A power system frequency response model construction and processing module considering comprehensive inertia control is used to establish a power system frequency response model considering comprehensive inertia control based on the frequency response model of the thermal power unit and in combination with the comprehensive inertia control model of the wind turbine unit; and obtain the frequency deviation of the power system through calculation and processing of the power system frequency response model considering comprehensive inertia control;

[0028] The module for constructing and processing the model of spatial distribution characteristics of the frequency response of the power system is used to construct the model of spatial distribution characteristics of the frequency response of the power system according to the influence of the grid connection of the wind turbine generator set on the spatial frequency characteristics of the power system and the obtained frequency deviation of the power system; the spatial distribution characteristics of the frequency response of the power system are obtained by calculating and processing the model of spatial distribution characteristics of the frequency response of the power system;

[0029] The module for quantitatively evaluating the spatial distribution characteristics of the frequency response of a power system is used to set a dispersion degree coefficient and to quantitatively evaluate the spatial distribution characteristics of the frequency response of the power system through the dispersion degree coefficient.

[0030] As a preferred solution of the frequency distribution analysis device of new energy units based on comprehensive inertia control, in the wind turbine unit comprehensive inertia control model construction module, the inertia control power increment, torque control increment and active power increment provided to the system of the wind turbine unit are calculated by the comprehensive inertia control model of the wind turbine unit;

[0031] The calculation formulas for the inertia control power increment, the torque control increment, and the active power increment provided to the system of the wind turbine generator set are respectively:

[0032]

[0033] P ref =P f -ΔP t P

[0034] Where P f , ΔP t , P ref They are the inertia control power increment, torque control increment and active power increment provided to the system of the wind turbine. K d , K p , K t are virtual inertia control coefficient, droop control coefficient, and torque control coefficient respectively; s is a constant in the automatic control theory; T d is the filter time constant; Δf, Δω r are frequency deviation and rotor speed deviation respectively; ω ro is the initial speed of the wind turbine rotor.

[0035] As a preferred solution of the frequency distribution analysis device of new energy units based on comprehensive inertia control, in the power system frequency response model construction and processing module considering comprehensive inertia control, in the process of obtaining the frequency deviation of the power system through calculation and processing of the power system frequency response model considering comprehensive inertia control, the calculation expression of the frequency deviation is:

[0036]

[0037] Where Δf sys is the power system frequency deviation; ΔP sys is the power disturbance of the power system; H sys is the equivalent inertia of the power system; D is the damping coefficient of the thermal power unit; α is the penetration rate of the new energy unit, and satisfies 0<α<1; G i (s) is the speed governor characteristic of the thermal power unit.

[0038] As a preferred solution of the frequency distribution analysis device of new energy units based on comprehensive inertia control, in the power system frequency response spatial distribution characteristic model construction and processing module, the mathematical expression of the power system frequency response spatial distribution characteristic model is:

[0039]

[0040] Where Δf i is the frequency deviation of node i; η P(i) , η H(i) are active power disturbance distribution coefficient and inertia distribution coefficient respectively; H i is the inertia of node i; Δp i The active power injected into each node; ΔP sys The disturbance of the power system.

[0041] As a preferred solution of the frequency distribution analysis device of new energy units based on comprehensive inertia control, in the quantitative evaluation module of the spatial distribution characteristics of the power system frequency response, the expression of the dispersion degree coefficient is:

[0042]

[0043] Where θ is the dispersion coefficient; Δf max,COI is the maximum deviation of the inertial center frequency; is the maximum frequency deviation of each node; m is the number of nodes in the system.

[0044] The present invention has the following advantages: according to the characteristics of the new energy generator set, a comprehensive inertia control model of the wind turbine set is constructed; the comprehensive inertia control model of the wind turbine set is used to alleviate the frequency-spatial characteristics of the power system; according to the frequency response model of the thermal power generator set, combined with the comprehensive inertia control model of the wind turbine set, a power system frequency response model considering comprehensive inertia control is established; the frequency deviation of the power system is obtained by calculating and processing the power system frequency response model considering comprehensive inertia control; according to the influence of the grid connection of the wind turbine generator set on the frequency-spatial characteristics of the power system, combined with the obtained frequency deviation of the power system, a power system frequency response spatial distribution characteristic model is constructed; the power system frequency response spatial distribution characteristic is obtained by calculating and processing the power system frequency response spatial distribution characteristic model; a dispersion degree coefficient is set, and the power system frequency response spatial distribution characteristic is quantitatively evaluated by the dispersion degree coefficient. The present invention proposes a quantitative index of the spatial distribution characteristic of the power grid frequency based on the inertia center, the maximum frequency deviation, the frequency change rate and other indicators, characterizes the spatial distribution characteristic of the power grid frequency, and proposes an inertia control method to solve the problem that the frequency spatial distribution characteristic of some areas is obvious due to the "low inertia and low frequency" of the new energy generator set in the new power system. The frequency spatial distribution characteristics of the new power system are becoming more and more significant due to the access of new energy units, and the frequency spatial distribution characteristics of the power grid are specifically affected by the size and position of the disturbance, the inertia response of the system and the primary frequency regulation capability, and the electrical distance between the disturbance node and other nodes in the power grid. The frequency spatial distribution characteristic model proposed hereby can characterize the frequency spatial distribution characteristics of the system, and the model has high accuracy. The quantitative index of the frequency spatial distribution characteristics of the power grid proposed in the present invention can well reveal the frequency spatial distribution characteristics of the new power system, which is helpful for the study of the frequency stability of the power grid. The inertia control method proposed in the present invention can improve the inertia level of each node in the system compared with the single virtual inertia control, further improve the frequency stability of the power system, and improve the frequency spatial distribution characteristics of the power grid, and the effectiveness of the proposed method is verified by the simulation example system. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0046] The structures, proportions, sizes, etc. illustrated in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantial technical significance. Any structural modification, change in proportion or adjustment of size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0047] Figure 1 This is a flow chart of a frequency distribution analysis method for a new energy generator set based on comprehensive inertia control provided in Example 1 of the present invention;

[0048] Figure 2 A schematic diagram of a frequency response curve of a power system in a frequency distribution analysis method for a new energy generator set based on comprehensive inertia control provided in Example 1 of the present invention;

[0049] Figure 3 It is a schematic diagram of a simplified model of the frequency response of a traditional thermal power unit in the frequency distribution analysis method of a new energy unit based on comprehensive inertia control provided in Example 1 of the present invention;

[0050] Figure 4 A schematic diagram of the structure of a DFIG wind turbine in the frequency distribution analysis method of a new energy unit based on comprehensive inertia control provided in Example 1 of the present invention;

[0051] Figure 5 It is a schematic diagram of a wind power integrated inertia control block in a frequency distribution analysis method for new energy generator sets based on integrated inertia control provided in Example 1 of the present invention;

[0052] Figure 6 A schematic diagram of a power system frequency response model considering the integrated inertia control of new energy in the frequency distribution analysis method of new energy units based on integrated inertia control provided in Example 1 of the present invention;

[0053] Figure 7 A schematic diagram of an improved IEEE 10 machine 39 node system in a possible embodiment provided in Embodiment 1 of the present invention;

[0054] Figure 8Schematic diagram of the frequency response of each node under three models in a possible embodiment provided in Embodiment 1 of the present invention; wherein (a) is the maximum frequency deviation of each node under the three modes, and (b) is the frequency change rate of each node under the three modes;

[0055] Fig. 9 Schematic diagram of node frequency dispersion degree in three modes in a possible embodiment provided in Embodiment 1 of the present invention; wherein (a) is a heat map of node frequency dispersion degree index in mode 1, (b) is a heat map of node frequency dispersion degree index in mode 2, and (c) is a heat map of node frequency dispersion degree index in mode 3;

[0056] Fig.10 Schematic diagram of equivalent inertia of each node in three modes in a possible embodiment provided in Embodiment 1 of the present invention; wherein (a) is a schematic diagram of equivalent inertia of each node in mode 1, (b) is a schematic diagram of equivalent inertia of each node in mode 2, and (c) is a schematic diagram of equivalent inertia of each node in mode 3;

[0057] Fig.11 A schematic diagram showing a comparison between a mathematical model value and a simulation value of a frequency-space distribution characteristic in a possible embodiment provided in Embodiment 1 of the present invention;

[0058] Fig.12 This is a schematic diagram of the architecture of the frequency distribution analysis device for new energy units based on comprehensive inertia control provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0059] The following is a description of the implementation of the present invention by specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. 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.

[0060] Example 1

[0061] See also Figure 1 Embodiment 1 of the present invention provides a frequency distribution analysis method for a new energy unit based on comprehensive inertia control, comprising the following steps:

[0062] S1. According to the characteristics of new energy units, a comprehensive inertia control model of wind turbines is constructed; the comprehensive inertia control model of wind turbines is used to alleviate the frequency-space characteristics of the power system;

[0063] S2. According to the frequency response model of the thermal power unit, combined with the comprehensive inertia control model of the wind turbine unit, a power system frequency response model considering comprehensive inertia control is established; and the frequency deviation of the power system is obtained by calculation and processing of the power system frequency response model considering comprehensive inertia control;

[0064] S3. According to the influence of the grid connection of wind turbines on the frequency spatial characteristics of the power system, combined with the obtained frequency deviation of the power system, a power system frequency response spatial distribution characteristic model is constructed; and the power system frequency response spatial distribution characteristic is obtained by calculation and processing of the power system frequency response spatial distribution characteristic model;

[0065] S4. Setting a dispersion coefficient, and using the dispersion coefficient to quantitatively evaluate the spatial distribution characteristics of the power system frequency response.

[0066] In this embodiment, in step S1, a comprehensive inertia control model of a wind turbine is constructed according to the characteristics of the new energy unit; the comprehensive inertia control model of the wind turbine is used to alleviate the frequency-space characteristics of the power system;

[0067] Specifically, when a disturbance occurs in the power system, the grid frequency will also fluctuate. During the fluctuation process, the power system will take some measures to suppress this fluctuation, such as Figure 2 As shown. Figure 2 It can be seen that the commonly used frequency regulation methods in power systems are: inertia response and primary frequency regulation.

[0068] Inertia response: When the disturbance causes the system power to drop, the speed of the synchronous generator decreases, and the change in rotor kinetic energy is injected into the grid in the form of electric power, slowing down the frequency drop and providing short-term frequency support for the system. The inertia time constant H is defined as:

[0069]

[0070] Where: E is the rotational kinetic energy in the unit; S n is the rated capacity of the unit; J is the moment of inertia of the rotor; ω is the rated speed of the rotor.

[0071] Primary frequency regulation: When the grid frequency deviates from the rated value, the speed regulator acts to increase the mechanical power input of the prime mover, and works together with the load frequency effect to support the frequency to reach a new balance at a slightly lower level. Compared with the short-term frequency support provided by the inertia response, when the frequency deviation exists, the primary frequency regulation response can provide the system with continuous active frequency support capability to prevent the frequency from continuing to drop.

[0072] In this embodiment, when establishing a power system frequency response model considering the inertia control of new energy sources, due to the low controllability of the load, only the inertia regulation and speed regulation system of the generator set are considered, and the influence of reactive power and partial inertia existing in the load on the electromechanical transient frequency response is ignored.

[0073] The simplified frequency response model of traditional thermal power units is as follows: Figure 3 shown. Figure 3 Where H is the inertia time constant of the thermal power unit; D is the damping coefficient of the thermal power unit; K mi is the mechanical power gain factor of the thermal power unit; F Ri is the power proportion of the high-pressure cylinder of the thermal motor; T Ri is the time constant of the steam turbine reheater of the thermal power unit; R is the regulation coefficient of the governor.

[0074] from Figure 3 You can get:

[0075] ΔP G =G i (s)Δf(2)

[0076]

[0077] Where: ΔP G is the mechanical power deviation of the thermal power unit; G i (s) is the speed governor characteristic of the thermal power unit; Δf is the frequency deviation of the thermal power unit.

[0078] Traditional renewable energy units do not have frequency regulation capabilities, but GB38755-2019 "Guidelines for Power System Safety and Stability" clearly requires that renewable energy stations should have certain frequency support and frequency regulation capabilities. Therefore, renewable energy units connected to the grid in the future need to provide the system with a certain level of frequency support. DFIG (Doubly fed Induction Generator, DFIG) units have the advantages of low cost, high efficiency and flexible control. They are currently the most widely used wind turbines. Therefore, taking the DFIG wind turbine as an example, its structural diagram is as follows: Figure 4 As shown, the unit structure mainly includes an induction motor, a converter, etc., and the converter control mainly includes virtual inertia control, MPPT control, and variable pitch control.

[0079] For new energy units mainly based on wind turbines, the kinetic energy hidden in their wind turbine rotors cannot be ignored. Their virtual inertia control generally takes the system frequency deviation as input and the active power provided to the system as output. This virtual inertia control method is single and fixed. However, for wind turbines, their virtual inertia with a single control method has poor support capability for grid frequency in actual applications, making it difficult to ensure the frequency stability of the power system.

[0080] To address this problem, the present invention proposes a comprehensive inertia control method to alleviate the frequency-space characteristics of the new power system. Figure 5 As shown in the figure: f n , f0 are the rated frequency and current frequency of the system respectively; ω r ,ω ro are the wind turbine rotor speed and its initial value respectively; Δf, Δω r are frequency deviation and rotor speed deviation respectively; T d is the filter time constant; K d , K p , K t They are virtual inertia control coefficient, droop control coefficient, and torque control coefficient respectively; K opt is the MPPT control coefficient; P e , P f , ΔP t , P ref They are the electromagnetic power of the wind turbine, the inertia control power increment, the torque control increment, and the active power increment provided to the system.

[0081] from Figure 5 Get P f , ΔP t , P ref The expressions are:

[0082]

[0083]

[0084] P ref =P f -ΔP t (6)

[0085] When a wind turbine is running, assuming that its wind speed remains constant, its input mechanical power is:

[0086] P m =0.5ρπR 2 C p (λ,β)v 3 (7)

[0087] Where ρ is the air density; R is the radius of the fan blade; C p is the wind energy utilization coefficient; λ is the blade tip number ratio; β is the pitch angle; v is the wind speed.

[0088] When the wind speed is greater than the rated wind speed, due to limitations of its mechanical structure, the wind turbine usually adjusts the frequency by changing the pitch angle rather than by inertia adjustment. Therefore, we only discuss the case where the wind speed is less than the rated wind speed. At this time, the mechanical input power increment is:

[0089]

[0090] Where: ΔC ω is the mechanical power increment coefficient.

[0091] Because the damping coefficient of the wind turbine rotor is generally very small, the damping coefficient is ignored here, and the wind turbine rotor motion equation is obtained:

[0092]

[0093] In the formula, H DFIG is the virtual inertia time constant of the wind turbine; ΔP e is the electromagnetic power increment of the wind turbine. Ignoring the influence of reactive voltage, the electromagnetic power increment ΔP e It can be equivalent to the first-order inertia link of the inner loop control of the quadrature-axis current of the converter related to the electromagnetic torque, and its expression is:

[0094]

[0095] Where: is the converter control time constant.

[0096] After normalizing equation (9) to unit value, the rotor frequency deviation of the low-frequency value can be expressed as the grid angular frequency increment, that is: Δf≈Δω e , and perform Laplace transform on equation (9) to obtain:

[0097]

[0098] The equivalent virtual inertia of a wind turbine generator set can be defined as:

[0099]

[0100] Where: eo ,ω nom are the initial value of the grid angular frequency and the rated angular speed of the wind turbine respectively.

[0101] Furthermore, the converter response speed is fast and its dynamic process can be ignored, that is, φ = 0. Then, the virtual inertia time constant expression of the wind turbine is obtained:

[0102]

[0103] Here H eq Indicates the frequency regulation capability of wind turbines. Within a certain range, H eq The larger it is, the stronger its frequency modulation ability is, otherwise vice versa.

[0104] In this embodiment, in step S2, a power system frequency response model considering comprehensive inertia control is established according to the frequency response model of the thermal power unit and in combination with the comprehensive inertia control model of the wind turbine unit; the frequency deviation of the power system is obtained by calculation and processing of the power system frequency response model considering comprehensive inertia control;

[0105] Specifically, in order to further study the frequency spatial distribution characteristics of the power system, based on the frequency response model of the traditional thermal power unit, combined with the comprehensive inertia control model of the wind turbine unit proposed in this invention, a power system frequency response model considering comprehensive inertia control is established, such as Figure 6 shown.

[0106] Figure 6 In the sys is the power disturbance of the power system, Δf sys is the power system frequency deviation; ΔP G is the power increment of the thermal power unit speed governor; H sys is the equivalent inertia of the power system, and its expression is:

[0107] H sys =αH eq +(1-α)H(14)

[0108] Where: α is the penetration rate of new energy units, and it satisfies 0<α<1.

[0109] Depend on Figure 6 The other expressions obtained are:

[0110]

[0111]

[0112] From equations (15) and (16), we can get the system frequency deviation expression Δf sys :

[0113]

[0114] From the analysis of formula (17), it can be seen that the magnitude of the system frequency deviation is mainly affected by factors such as the disturbance size, system inertia time constant, damping coefficient, permeability, and thermal power unit speed governor characteristics.

[0115] In this embodiment, in step S3, according to the influence of the grid connection of wind turbines on the frequency spatial characteristics of the power system, combined with the obtained frequency deviation of the power system, a power system frequency response spatial distribution characteristic model is constructed; the power system frequency response spatial distribution characteristic is obtained by calculation and processing of the power system frequency response spatial distribution characteristic model;

[0116] Specifically, in order to further analyze the impact of wind turbine grid connection on the frequency spatial characteristics of the new power system, a frequency response spatial distribution characteristic model of the new power system is established.

[0117] When a disturbance occurs in the power system, the active power and frequency disturbance process of the new power system is different from that of the traditional power system, which is expanded from the main three stages to four stages: disturbance power distribution stage, voltage source type inertia response stage, current source type virtual inertia and synchronous power supply primary frequency modulation stage, power electronic equipment frequency modulation exit and energy recovery stage. n The node has a size of ΔP n Disturbance, at the initial stage of disturbance, the system active power and frequency disturbance process have not reached the frequency modulation stage. At this time, the active power injected by each node is:

[0118]

[0119] Where P i is the active power injected into each node; E i is the potential of the i-th node; B ij , G ij is the susceptance and conductance between nodes i and j; m is the number of nodes; β ij is the phase difference between nodes i and j.

[0120] Assume that after node n is disturbed, the voltage phase angle becomes (β n0 +Δβ n ), and after linearizing equation (18), we get:

[0121]

[0122] Where ΔP i is the active power imbalance of each node; β ij0 For node i, j The initial phase difference between ij is the synchronization power coefficient between nodes i and j; Q in is the node i and the disturbance node n The synchronous power factor between

[0123] Furthermore, the unbalanced power allocated to node i can be expressed as:

[0124]

[0125] Correspondingly, the frequency deviation expression of each node in the system is written according to the system frequency deviation expression of formula (18):

[0126]

[0127] Where Δf iis the frequency deviation of node i; H i is the inertia of node i.

[0128] From the analysis of formula (21), we can get that the main factors affecting the frequency are: 1) ΔP n The size of the disturbance; 2) H i The size of the equivalent inertia level of the general node; 3) the size of the D damping coefficient; 4) the size of the α permeability; 5) the speed regulator characteristics of the thermal power unit can represent the primary frequency regulation capability of the system. However, in this part, the influence of the D damping coefficient on the frequency is smaller than that of several other factors and is generally a constant value. Therefore, by increasing the inertia and frequency support of the wind turbine to the power grid, the inertia level of the system as a whole and each node is increased. i , and thus improving the spatial distribution characteristics of power grid frequency is an effective way.

[0129] When the node in the system n The disturbance ΔP occurs at n When , the disturbance of node n can be considered as the power disturbance of the power system, that is:

[0130] ΔP sys =ΔP n (twenty two)

[0131] Formula (21) is combined with formula (17). Based on the above analysis of the damping coefficient, the influence of the damping coefficient on the frequency space distribution characteristics is temporarily ignored. At the same time, based on the traditional power system with very low penetration rate, it can be approximately considered that there is only one type of power source, the thermal power unit, in the system. At this time, the system frequency space distribution characteristics are extremely unobvious, so it can be considered that the speed regulator has little influence on the frequency space distribution characteristics. Therefore, the influence of the damping coefficient and the thermal power unit speed regulator is temporarily ignored, and the mathematical model of the system frequency space distribution characteristics is obtained:

[0132]

[0133]

[0134]

[0135] Where η P(i) , η H(i) They are active power disturbance distribution coefficient and inertia distribution coefficient respectively; Δp i The active power injected into each node; ΔP sys The disturbance of the power system.

[0136] It can be seen from formula (13) that due to the comprehensive inertia control of wind turbines, the overall inertia level of the new power system increases, and the inertia distribution coefficient η is adjusted H(i) , thereby improving the system frequency spatial distribution characteristics.

[0137] In this embodiment, in step S4, a dispersion coefficient is set, and the spatial distribution characteristics of the power system frequency response are quantitatively evaluated by the dispersion coefficient.

[0138] Specifically, the spatial distribution characteristics of power grid frequency are affected by multiple factors, and it is necessary to define frequency spatial distribution characteristics evaluation indicators from multiple angles. Existing literature provides the following indicators: 1) Rate of change of frequency (ROCOF): the frequency fluctuation value per unit time after the disturbance occurs; 2) Maximum frequency deviation: the value at the maximum frequency fluctuation after the disturbance occurs.

[0139] In order to better analyze the spatial distribution characteristics of power grid frequency, the center of inertia frequency (COI) is used as the reference object of power grid frequency, which is defined as:

[0140]

[0141] In the formula, f COI is the inertial center frequency; f i f is the bus frequency connected to thermal power unit i; t The bus frequency connected to the new energy unit t.

[0142] The above-mentioned related indicators only show the difference of frequency response of each node to reflect the frequency spatial distribution characteristics, and cannot intuitively reflect the frequency distribution characteristics of each node in the system. The present invention proposes a dispersion coefficient θ as a quantitative indicator of the frequency spatial distribution characteristics of the power grid, and its expression is as follows:

[0143]

[0144] Where: Δf max,COI is the maximum deviation of the inertial center frequency; Δf max,i is the maximum frequency deviation of each node; m is the number of nodes in the system. The larger the index Θ is, the more obvious the spatial distribution characteristics of the power grid frequency are, and the worse the system stability is.

[0145] In a possible embodiment, an example of frequency space distribution characteristic analysis of an improved IEEE 10-machine 39-node system built based on Matlab / Simulink is provided as follows:

[0146] Based on Matlab / Simulink, an improved IEEE10 machine 39 node system is built. Figure 7The system consists of 10 power plants, 19 loads and 34 lines, of which G1-G8 are synchronous units, W1-W2 are wind farms, each wind farm consists of 80 wind turbines (DFIG), and the speed regulator models of the 8 synchronous units and the related parameters of the 2 wind farms are the same. The rated frequency of the system is 60Hz, the base capacity of the system is 100MVA, and the related parameters of the synchronous units and wind turbines are shown in Tables 1 and 2 respectively.

[0147]

[0148] Table 1 Synchronous unit related parameters

[0149]

[0150] Table 2 Wind turbine related parameters

[0151] Assume that at the 18th node in the improved IEEE 10-machine 39-node system, the load suddenly increases by 800MW at t=5s. In order to verify the feasibility of the frequency space mathematics of the power system and the effectiveness of the proposed method in improving the frequency space distribution characteristics of the power grid, the following three modes are set:

[0152] Mode 1: Wind turbines do not participate in frequency regulation;

[0153] Mode 2: Single virtual inertia control mode;

[0154] Mode 3: The frequency integrated control mode proposed in this paper.

[0155] Under the above assumptions, the ROCOF and maximum frequency deviation of each node in the system under the above three modes are obtained as follows: Figure 8 shown.

[0156] exist Figure 8 In (a), the maximum frequency deviations of all nodes of the improved IEEE10-machine-39 system under three models are compared. In mode 1, the maximum frequency deviation of the system is larger, among which the maximum frequency deviation at node 39 reaches 0.43Hz, and the frequency deviations of each node vary greatly in value, showing a more serious spatial distribution characteristic of the power grid frequency. In mode 2, virtual inertia control is added to the wind turbines in the system. Although the maximum frequency deviation of each node of the system is smaller than that of mode 1, the improvement is still not obvious. Compared with mode 1 and mode 2, the maximum frequency deviation of each node of the system is significantly smaller in mode 3 based on the frequency comprehensive control mode proposed in this paper, and the numerical difference of the maximum frequency deviation of each node is also relatively fixed, which fully demonstrates that the spatial distribution characteristic of the power grid frequency is improved and the system frequency stability is relatively good.

[0157] exist Figure 8In (b), the frequency change rates of all nodes of the improved IEEE10-machine-39 system under three modes are compared. In mode 1, since the wind turbines cannot provide inertia support for the system, the frequency change rate of each node is large and more serious at the wind turbine grid-connected node, and the overall system shows poor frequency regulation capability; in mode 2 based on single virtual inertia control, the wind turbines provide weak inertia support for the system, and the frequency change of some nodes is slower than that of mode 1, and the problem of poor frequency regulation capability of the overall system has not been solved; and compared with modes 1 and 2, mode 3 not only has a smaller overall frequency change rate of the system, but also relatively consistent frequency change rates of each node, improving the spatial distribution characteristics of the grid frequency. In the figure, the frequency change rates of nodes 1, 9, 24, and 29 of the three models are not much different. The specific reason is that the inertia response of thermal power units has a much greater effect on the above nodes than wind turbines.

[0158] After obtaining the frequency response of each node in the system, the maximum frequency deviation and frequency change rate of COI in the three modes are calculated by formula (24), as shown in Table 3.

[0159]

[0160] Table 3 Inertial center frequency response in three modes

[0161] As can be seen from Table 3, the maximum frequency deviation and ROCOF of COI in mode 3 are lower in value than those in mode 1 and mode 2, indicating that the overall system frequency stability level is higher in mode 3.

[0162] In order to further verify the effectiveness of the inertia control model proposed in this invention in improving the spatial distribution characteristics of the power grid frequency, the frequency dispersion degree heat map of each node under the three modes is obtained based on formula (24), as shown in Fig. 9 shown.

[0163] Fig. 9 (a), (b), and (c) are heat maps of the frequency dispersion of system nodes in modes 1, 2, and 3, respectively. Each diagram is divided into 40 small parts, where 1-39 represents the frequency dispersion of each of the 39 nodes in the system, and COI represents the dispersion of the center of inertia of the system. The darker the color, the greater the dispersion, the more obvious the spatial distribution characteristics of the power grid frequency, and the worse the system stability.

[0164] Depend on Fig. 9 (a), (b), and (c) show that the dispersion index of most nodes in Mode 1 and Mode 2 is between 2 and 3, and some nodes have a higher dispersion index. Compared with Mode 1 and Mode 2, Mode 3

[0165] The degree of dispersion of all nodes decreases, the general node dispersion index is between 0 and 1, and the maximum node dispersion index does not exceed 2, indicating that the spatial distribution characteristics of the power grid frequency are significantly improved, and the power grid frequency stability under mode three is better.

[0166] The different frequency-space distribution characteristics under the three models are quantitatively analyzed, and the inertia distribution of each node in the improved 10-machine 39-node system under the three models is obtained as follows: Fig.10 shown.

[0167] pass Fig.10 (a), (b), and (c) can directly observe the inertia space distribution of each node of the system under the three models. Fig.10 (a) is the inertia distribution diagram of mode 1. The inertia of nodes 1-39 does not change with time. The reason is that in this mode, the wind turbines connected to the grid do not have virtual inertia control, only the fixed inertia provided by the thermal power units, and the overall inertia level is relatively low. Fig.10 (b) Because the wind turbine is attached with a single virtual inertia control, the inertia of the node changes with time, and when the disturbance occurs (t = 10s), the inertia of each node reaches the maximum value. Compared with mode 1, although the inertia level has increased overall, the increase is difficult to alleviate the frequency-spatial distribution characteristics of the wind turbine under grid connection; Fig.10 (c) is the inertia distribution of each node in mode three. The time-varying characteristics of the inertia of each node are similar to those of mode two, but compared with modes one and two, the inertia level of each node is higher. This also explains why mode three can alleviate the frequency-space distribution characteristics, and further illustrates the effectiveness of the present invention.

[0168] In order to reduce the randomness of the experimental results, the frequency deviation data of different nodes under the three models are randomly obtained to verify the feasibility of the frequency space distribution mathematical model. The nodes taken by the three models are shown in Table 4, and the frequency space distribution characteristic model values ​​of the nodes corresponding to mode 1, mode 2, and mode 3 are obtained as follows: Fig.11 shown.

[0169]

[0170]

[0171] Table 4 Different node numbers taken by three modes

[0172] Fig.11 The figure shows the comparison between the mathematical model value and the simulation value of the frequency-space distribution characteristic. The red, green, and blue colors are the simulation values ​​of the corresponding nodes in the three modes. The dotted lines in the figure are the values ​​calculated by the mathematical model of the frequency-space distribution characteristic of formula (23). Fig.11It can be seen from the results that the values ​​calculated by the mathematical model of frequency-space distribution characteristics are basically equal to the values ​​obtained by simulation, and the error is very small, which shows that the model can show the frequency-space distribution characteristics and is conducive to better analysis of frequency-space distribution characteristics.

[0173] In summary, the present invention constructs a comprehensive inertia control model of wind turbines according to the characteristics of new energy units; the comprehensive inertia control model of wind turbines is used to alleviate the frequency-spatial characteristics of the power system; according to the frequency response model of thermal power units, combined with the comprehensive inertia control model of wind turbines, a power system frequency response model considering comprehensive inertia control is established; the frequency deviation of the power system is obtained by calculating and processing the power system frequency response model considering comprehensive inertia control; according to the influence of wind turbines on the frequency-spatial characteristics of the power system, combined with the obtained frequency deviation of the power system, a power system frequency response spatial distribution characteristic model is constructed; the power system frequency response spatial distribution characteristic is obtained by calculating and processing the power system frequency response spatial distribution characteristic model; the dispersion degree coefficient is set, and the power system frequency response spatial distribution characteristic is quantitatively evaluated by the dispersion degree coefficient. The present invention proposes a quantitative index of the spatial distribution characteristic of the power grid frequency based on the inertia center, the maximum frequency deviation, the frequency change rate and other indicators, characterizes the spatial distribution characteristic of the power grid frequency, and proposes an inertia control method to solve the problem that the frequency spatial distribution characteristics of some areas are obvious due to the "low inertia and low frequency" of new energy units in the new power system. The frequency spatial distribution characteristics of the new power system are becoming more and more significant due to the access of new energy units, and the frequency spatial distribution characteristics of the power grid are specifically affected by the size and position of the disturbance, the inertia response of the system and the primary frequency regulation capability, and the electrical distance between the disturbance node and other nodes in the power grid. The frequency spatial distribution characteristic model proposed hereby can characterize the frequency spatial distribution characteristics of the system, and the model has high accuracy. The quantitative index of the frequency spatial distribution characteristics of the power grid proposed in the present invention can well reveal the frequency spatial distribution characteristics of the new power system, which is helpful for the study of the frequency stability of the power grid. The inertia control method proposed in the present invention can improve the inertia level of each node in the system compared with the single virtual inertia control, further improve the frequency stability of the power system, and improve the frequency spatial distribution characteristics of the power grid, and the effectiveness of the proposed method is verified by the simulation example system.

[0174] It should be noted that the method of the embodiment of the present disclosure can be performed by a single device, such as a computer or a server. The method of the present embodiment can also be applied in a distributed scenario and completed by multiple devices cooperating with each other. In the case of such a distributed scenario, one of the multiple devices can only perform one or more steps in the method of the embodiment of the present disclosure, and the multiple devices will interact with each other to complete the described method.

[0175] It should be noted that the above describes some embodiments of the present disclosure. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the above embodiments and still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0176] Example 2

[0177] See also Fig.12 Embodiment 2 of the present invention also provides a frequency distribution analysis device for a new energy unit based on comprehensive inertia control, including:

[0178] The wind turbine integrated inertia control model construction module 001 is used to construct a wind turbine integrated inertia control model according to the characteristics of the new energy unit; the wind turbine integrated inertia control model is used to alleviate the frequency-space characteristics of the power system;

[0179] The power system frequency response model construction and processing module 002 considering comprehensive inertia control is used to establish a power system frequency response model considering comprehensive inertia control based on the frequency response model of the thermal power unit and in combination with the comprehensive inertia control model of the wind turbine unit; the frequency deviation of the power system is obtained through calculation and processing of the power system frequency response model considering comprehensive inertia control;

[0180] The power system frequency response spatial distribution characteristic model construction and processing module 003 is used to construct a power system frequency response spatial distribution characteristic model according to the influence of the wind turbine generator set grid connection on the power system frequency spatial characteristic, combined with the obtained frequency deviation of the power system; and obtain the power system frequency response spatial distribution characteristic through calculation and processing of the power system frequency response spatial distribution characteristic model;

[0181] The power system frequency response spatial distribution characteristic quantitative evaluation module 004 is used to set a dispersion degree coefficient, and to quantitatively evaluate the power system frequency response spatial distribution characteristic through the dispersion degree coefficient.

[0182] In this embodiment, in the wind turbine integrated inertia control model construction module 001, the wind turbine integrated inertia control model is used to calculate the inertia control power increment, torque control increment, and active power increment provided to the system of the wind turbine;

[0183] The calculation formulas for the inertia control power increment, the torque control increment, and the active power increment provided to the system of the wind turbine generator set are respectively:

[0184]

[0185] P ref =P f -ΔP t P

[0186] Where P f , ΔP t , P ref They are the inertia control power increment, torque control increment and active power increment provided to the system of the wind turbine. K d , K p , K t are virtual inertia control coefficient, droop control coefficient, and torque control coefficient respectively; s is a constant in the automatic control theory; T d is the filter time constant; Δf, Δω r are frequency deviation and rotor speed deviation respectively; ω ro is the initial speed of the wind turbine rotor.

[0187] In this embodiment, in the power system frequency response model construction and processing module 002 considering comprehensive inertia control, in the process of obtaining the frequency deviation of the power system through calculation and processing of the power system frequency response model considering comprehensive inertia control, the calculation expression of the frequency deviation is:

[0188]

[0189] Where Δf sys is the power system frequency deviation; ΔP sys is the power disturbance of the power system; H sys is the equivalent inertia of the power system; D is the damping coefficient of the thermal power unit; α is the penetration rate of the new energy unit, and satisfies 0<α<1; G i (s) is the speed governor characteristic of the thermal power unit.

[0190] In this embodiment, in the power system frequency response spatial distribution characteristic model construction and processing module 003, the mathematical expression of the power system frequency response spatial distribution characteristic model is:

[0191]

[0192] Where Δf i is the frequency deviation of node i; η P(i) , η H(i) are active power disturbance distribution coefficient and inertia distribution coefficient respectively; H i is the inertia of node i; Δp i The active power injected into each node; ΔP sys The disturbance of the power system.

[0193] In this embodiment, in the power system frequency response spatial distribution characteristic quantitative evaluation module 004, the expression of the dispersion degree coefficient is:

[0194]

[0195] Where θ is the dispersion coefficient; Δf max,COI is the maximum deviation of the inertial center frequency; is the maximum frequency deviation of each node; m is the number of nodes in the system.

[0196] It should be noted that the information interaction, execution process and other contents between the modules of the above-mentioned system are based on the same concept as the method embodiment in Example 1 of the present application, and the technical effects they bring are the same as those of the method embodiment of the present application. For specific contents, please refer to the description in the method embodiment shown above in the present application, and will not be repeated here.

[0197] Example 3

[0198] Embodiment 3 of the present invention provides a non-transitory computer-readable storage medium, in which a program code for a frequency distribution analysis method for a new energy unit based on integrated inertia control is stored. The program code includes instructions for executing embodiment 1 or any possible implementation method thereof.

[0199] The computer-readable storage medium may be any available medium that can be accessed by a computer or a data storage device such as a server or a data center that includes one or more available media. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)).

[0200] Example 4

[0201] Embodiment 4 of the present invention provides an electronic device, including: a memory and a processor;

[0202] The processor and the memory communicate with each other via a bus; the memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to execute the frequency distribution analysis method of new energy units based on comprehensive inertia control of Example 1 or any possible implementation thereof.

[0203] Specifically, the processor can be implemented by hardware or by software. When implemented by hardware, the processor can be a logic circuit, an integrated circuit, etc.; when implemented by software, the processor can be a general-purpose processor implemented by reading software codes stored in a memory. The memory can be integrated in the processor or can be located outside the processor and exist independently.

[0204] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present invention is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable systems. The computer instructions can be stored in a computer-readable storage medium, or transmitted from a computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions can be transmitted from a website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center.

[0205] Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general computing system, they can be concentrated on a single computing system, or distributed on a network composed of multiple computing systems, and optionally, they can be implemented by a program code executable by a computing system, so that they can be stored in a storage system and executed by the computing system, and in some cases, the steps shown or described can be executed in a different order than here, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. Thus, the present invention is not limited to any specific combination of hardware and software.

[0206] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A frequency distribution analysis method for new energy units based on comprehensive inertia control, characterized in that: include: According to the characteristics of new energy units, a comprehensive inertia control model for wind turbines is constructed; The wind turbine integrated inertia control model is used to mitigate the frequency-space characteristics of the power system; According to the frequency response model of the thermal power unit, combined with the comprehensive inertia control model of the wind turbine unit, a power system frequency response model considering comprehensive inertia control is established; the frequency deviation of the power system is obtained through calculation and processing of the power system frequency response model considering comprehensive inertia control; According to the influence of the grid connection of wind turbines on the frequency spatial characteristics of the power system, combined with the obtained frequency deviation of the power system, a power system frequency response spatial distribution characteristic model is constructed; and the power system frequency response spatial distribution characteristic is obtained by calculation and processing of the power system frequency response spatial distribution characteristic model; A dispersion degree coefficient is set, and the spatial distribution characteristics of the frequency response of the power system are quantitatively evaluated by the dispersion degree coefficient.

2. The frequency distribution analysis method of new energy units based on comprehensive inertia control according to claim 1 is characterized in that: The wind turbine generator set comprehensive inertia control model is used to calculate the inertia control power increment, torque control increment and active power increment provided to the system of the wind turbine generator set; The calculation formulas for the inertia control power increment, the torque control increment, and the active power increment provided to the system of the wind turbine generator set are respectively: P ref =P f -ΔP t Where P f , ΔP t , P ref They are the inertia control power increment, torque control increment and active power increment provided to the system of the wind turbine. K d , K p , K t are virtual inertia control coefficient, droop control coefficient, and torque control coefficient respectively; s is a constant in the automatic control theory; T d is the filter time constant; Δf, Δω r are frequency deviation and rotor speed deviation respectively; ω ro is the initial speed of the wind turbine rotor.

3. The frequency distribution analysis method of new energy units based on comprehensive inertia control according to claim 2 is characterized in that: In the process of obtaining the frequency deviation of the power system by calculating and processing the power system frequency response model considering the comprehensive inertia control, the calculation expression of the frequency deviation is: Where Δf sys is the power system frequency deviation; ΔP sys is the power disturbance of the power system; H sys is the equivalent inertia of the power system; D is the damping coefficient of the thermal power unit; α is the penetration rate of the new energy unit, and satisfies 0<α<1; G i (s) is the speed governor characteristic of the thermal power unit.

4. The frequency distribution analysis method of new energy units based on comprehensive inertia control according to claim 3 is characterized in that: The mathematical expression of the power system frequency response spatial distribution characteristic model is: Where Δf i is the frequency deviation of node i; η P(i) , η H(i) are active power disturbance distribution coefficient and inertia distribution coefficient respectively; H i is the inertia of node i; Δp i The active power injected into each node; ΔP sys The disturbance of the power system.

5. The frequency distribution analysis method of new energy units based on comprehensive inertia control according to claim 4 is characterized in that: The expression of the dispersion coefficient is: Where θ is the dispersion coefficient; Δf max,COI is the maximum deviation of the inertial center frequency; Δf maxi , is the maximum frequency deviation of each node; m is the number of nodes in the system.

6. A frequency distribution analysis device for a new energy unit based on comprehensive inertia control, adopting the frequency distribution analysis method for a new energy unit based on comprehensive inertia control according to any one of claims 1 to 5, characterized in that: include: A wind turbine integrated inertia control model building module is used to build a wind turbine integrated inertia control model based on the characteristics of new energy units; The wind turbine integrated inertia control model is used to mitigate the frequency-space characteristics of the power system; A power system frequency response model construction and processing module considering comprehensive inertia control is used to establish a power system frequency response model considering comprehensive inertia control based on the frequency response model of the thermal power unit and in combination with the comprehensive inertia control model of the wind turbine unit; and obtain the frequency deviation of the power system through calculation and processing of the power system frequency response model considering comprehensive inertia control; The module for constructing and processing the model of spatial distribution characteristics of the frequency response of the power system is used to construct the model of spatial distribution characteristics of the frequency response of the power system according to the influence of the grid connection of the wind turbine generator set on the spatial frequency characteristics of the power system and the obtained frequency deviation of the power system; the spatial distribution characteristics of the frequency response of the power system are obtained by calculating and processing the model of spatial distribution characteristics of the frequency response of the power system; The module for quantitatively evaluating the spatial distribution characteristics of the frequency response of a power system is used to set a dispersion degree coefficient and to quantitatively evaluate the spatial distribution characteristics of the frequency response of the power system through the dispersion degree coefficient.

7. The frequency distribution analysis device for new energy units based on comprehensive inertia control according to claim 6 is characterized in that: In the wind turbine integrated inertia control model construction module, the wind turbine integrated inertia control model is used to calculate the inertia control power increment, torque control increment, and active power increment provided to the system of the wind turbine; The calculation formulas for the inertia control power increment, the torque control increment, and the active power increment provided to the system of the wind turbine generator set are respectively: P ref =P f -ΔP t Where P f , ΔP t , P ref They are the inertia control power increment, torque control increment and active power increment provided to the system of the wind turbine. K d , K p , K t are virtual inertia control coefficient, droop control coefficient, and torque control coefficient respectively; s is a constant in the automatic control theory; T d is the filter time constant; Δf, Δω r are frequency deviation and rotor speed deviation respectively; ω ro is the initial speed of the wind turbine rotor.

8. The frequency distribution analysis device for new energy units based on comprehensive inertia control according to claim 7 is characterized in that: In the power system frequency response model construction and processing module considering comprehensive inertia control, in the process of obtaining the frequency deviation of the power system through calculation and processing of the power system frequency response model considering comprehensive inertia control, the calculation expression of the frequency deviation is: Where Δf sys is the power system frequency deviation; ΔP sys is the power disturbance of the power system; H sys is the equivalent inertia of the power system; D is the damping coefficient of the thermal power unit; α is the penetration rate of the new energy unit, and satisfies 0<α<1; G i (s) is the speed governor characteristic of the thermal power unit.

9. The frequency distribution analysis device for new energy units based on comprehensive inertia control according to claim 8 is characterized in that: In the power system frequency response spatial distribution characteristic model construction and processing module, the mathematical expression of the power system frequency response spatial distribution characteristic model is: Where Δf i is the frequency deviation of node i; η P(i) , η H(i) are active power disturbance distribution coefficient and inertia distribution coefficient respectively; H i is the inertia of node i; Δp i The active power injected into each node; ΔP sys The disturbance of the power system.

10. The frequency distribution analysis device for new energy units based on comprehensive inertia control according to claim 9 is characterized in that: In the power system frequency response spatial distribution characteristic quantitative evaluation module, the expression of the dispersion coefficient is: Where θ is the dispersion coefficient; Δf max,COI is the maximum deviation of the inertial center frequency; Δf maxi , is the maximum frequency deviation of each node; m is the number of nodes in the system.

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