A centralized-distributed two-layer cooperative frequency support control method

Abstract

This invention discloses a centralized-distributed dual-layer coordinated frequency support control method, belonging to the field of wind power frequency support, comprising the following steps: S1, acquiring wind turbine operating state parameters; S2, based on speed limit constraints, iteratively estimating the speed-constrained critical disturbance power; S3, based on frequency regulation power limit constraints, iteratively estimating the frequency regulation power-constrained critical disturbance power; S4, fusing the speed-constrained and frequency regulation power-constrained critical disturbance powers to determine the final critical disturbance power; S5, determining the coordination coefficient based on the final critical disturbance power; S6, performing centralized-distributed dual-layer coordinated frequency support control for multiple wind turbines based on the determined coordination coefficient. The above-mentioned centralized-distributed dual-layer coordinated frequency support control method has significant advantages in system stability, equipment safety, and engineering practicality, providing key technical support for wind power participation in primary frequency regulation in new power systems.

Description

Technical Field

[0001] This invention relates to the field of wind power frequency support technology, and in particular to a centralized-distributed dual-layer collaborative frequency support control method. Background Technology

[0002] In power systems with a high proportion of wind power connected to the grid, wind turbines face critical issues of physical limit constraints and frequency regulation capability assessment when participating in frequency regulation. In existing technologies, wind turbine frequency regulation control strategies typically do not fully consider the dual constraints of speed limits and frequency regulation power limits, leading to the following technical shortcomings:

[0003] 1. When the system disturbance power exceeds the physical limit of the wind turbine, the speed protection mechanism is easily triggered, causing a secondary drop in system frequency. That is, when the wind turbine speed touches the safe operating speed threshold, the speed protection is activated, and the wind turbine is forced to exit frequency regulation and enter the operation recovery stage, resulting in a secondary drop in system frequency and affecting frequency stability.

[0004] 2. Traditional frequency regulation power allocation criteria (such as the average allocation method and the wind speed weighting method) do not take into account the real-time operating status and safety margin of the wind turbines, which leads to some units undertaking excessive frequency regulation tasks and triggering the power limit. At this time, it will be impossible to provide additional power support, and the actual frequency response effect will deviate from the expected target. Summary of the Invention

[0005] The purpose of this invention is to provide a centralized-distributed two-layer cooperative frequency support control method to solve the above-mentioned technical problems.

[0006] To achieve the above objectives, the present invention provides a centralized-distributed two-layer cooperative frequency support control method, comprising the following steps:

[0007] S1. Obtain the operating status parameters of the wind turbine, including wind speed, disturbance power, rotational speed, output power and physical limit parameters;

[0008] S2. Based on the speed limit constraint, the critical disturbance power of the speed constraint type is estimated iteratively.

[0009] S3. Based on the frequency modulation power limit constraint, the critical disturbance power of the frequency modulation power constraint type is predicted iteratively.

[0010] S4. Combine the speed-constrained critical disturbance power and the frequency-controlled critical disturbance power to determine the final critical disturbance power;

[0011] S5. Determine the coordination coefficient based on the final critical disturbance power;

[0012] S6. Perform centralized-distributed dual-layer coordinated frequency support control for multiple wind turbines based on the determined coordination coefficients.

[0013] Preferably, step S2 specifically includes the following steps:

[0014] S21. Initialization: Set the estimated speed-constrained critical disturbance power range to the minimum deficit disturbance power ΔP. L min - Maximum shortfall disturbance power ΔP L max And set the initial speed-constrained disturbance deficit power as Iteration count n = 0;

[0015] S22. Based on the single-mass block transmission system model, construct the rotor motion equations of the wind turbine:

[0016]

[0017] In the formula, P wm P represents the mechanical power captured by the wind turbine. we Indicates the active power output of the wind turbine; H w ω represents the time constant of inertia of the fan rotor. r This represents the rotor speed; t is a time variable.

[0018] S23, Based on the rotational speed range [ω] rmin ,ω rN ], capturing mechanical power P from the wind turbine wm Divided into N LPM The wind turbine captures mechanical power P in the i-th segment by fitting an aerodynamic model. wm,i :

[0019]

[0020] In the formula, ω rmin Indicates the lower limit of the rotor's safe operating speed; ω rN Indicates the upper limit of rotor speed; z 1,i z 2,i and z 3,i All represent the fitting coefficients;

[0021] S24. Substitute formula (1) into formula (2), and change the expected output power of the wind turbine. Considered P we ,get:

[0022]

[0023] S25. Using the MATLAB numerical solver ode45, the fan speed trajectory is obtained by iteratively solving formula (3) to obtain the nth iteration speed trajectory. and lower limit of rotational speed trajectory

[0024] S26. Speed ​​safety threshold judgment: Determine whether the speed safety threshold is met. ε is the convergence accuracy threshold. If satisfied, the speed-constrained critical disturbance power for the nth iteration is output. The estimated speed-constrained critical disturbance power ΔP L,ωlim Otherwise, proceed to step S27;

[0025] S27, Corrected speed-constrained critical disturbance power like Let the speed-constrained critical disturbance power of the (n+1)th iteration be... And order n = n + 1, and return to step S24;

[0026] like Let the speed-constrained critical disturbance power of the (n+1)th iteration be... make When n = n + 1, return to step S24.

[0027] Preferably, the frequency modulation power limit constraint mentioned in step S3 includes converter capacity, limiting electromagnetic torque and maximum allowable output power;

[0028] Specifically, it includes the following steps:

[0029] S31. Initialization: Set the estimated frequency modulation power constraint critical disturbance power range to the minimum deficit disturbance power to the maximum deficit disturbance power, and set the initial frequency modulation power constraint disturbance deficit power to [value missing]. Iteration count n = 0;

[0030] S32. Based on the nth iteration rotational speed trajectory obtained in step S25 and lower limit of rotational speed trajectory Maximum output power of computer-side converter

[0031]

[0032] In the formula, This represents the expected output power of the wind turbine in the nth iteration; This represents the rotor speed of the wind turbine at the nth iteration;

[0033] S33. Determine if the condition is met. If satisfied, output the frequency-modulated power-constrained critical disturbance power for the nth iteration. Otherwise, proceed to step S34; P r,max This indicates the maximum output power limit of the machine-side converter;

[0034] S34, Modified frequency modulation power-constrained critical disturbance power like Let the frequency modulation power-constrained critical disturbance power of the (n+1)th iteration be... And order n = n + 1, return to step S32;

[0035] like Let the frequency modulation power-constrained critical disturbance power of the (n+1)th iteration be... And order When n = n + 1, return to step S32.

[0036] Preferably, in step S3, the estimated frequency modulation power-constrained critical disturbance power ΔP is obtained. L,Plim =min{ΔP L,Prlim ,ΔP L,Twelim ,ΔP L,Pwelim}, ΔP L,Prlim Let ΔP represent the critical disturbance power based on power point tracking constraints. L,Twelim ΔP represents the critical disturbance power based on converter capacity constraints. L,Pwelim This represents the critical disturbance power based on the electrical power output constraint.

[0037] In step S4, the final critical disturbance power ΔP is set. L,th =min{ΔP L,ωlim ,ΔP L,Plim}

[0038] Preferably, step S5 specifically includes the following steps:

[0039] S51. Assume that wind turbines in the same wind turbine group are equivalent to one wind turbine unit, and obtain the frequency regulation power undertaken by the h-th equivalent wind turbine unit in the j-th wind farm. for:

[0040]

[0041] In the formula, denoted by , where represents the frequency regulation output coefficient of the j-th wind farm; C represents the collaborative allocation coefficient of the wind farm cluster. This represents the rated capacity of the wind turbine group within the j-th wind farm; and Let represent the equivalent capacity and the percentage of equivalent wind turbine capacity of the h-th equivalent wind turbine unit in the j-th wind farm, respectively. Indicates the frequency regulation power command for the wind farm; N sum This represents the total number of wind farms participating in coordinated frequency regulation;

[0042] S52. Establish frequency regulation power of wind turbine units under frequency feedback control. Quantitative relationship between frequency deviation and unit characteristics:

[0043]

[0044] In the formula, k represents the coordination coefficient of the h-th equivalent wind turbine unit within the j-th wind farm; F Indicates the feedback coefficient; Indicates the minimum deviation command for system frequency; H w ω represents the time constant of inertia of the fan rotor. r0 The rotor's rated speed is represented by s; the complex frequency variable of the Laplace transform is represented by k. m Represents the mechanical power fitting coefficient; k t Represents the electric power fitting coefficient;

[0045] S53. Substituting formula (6) into formula (5) yields:

[0046]

[0047] S54. Assuming that the wind speed of all wind turbines in all wind farms is the same as the wind speed of the h-th equivalent wind turbine, we get:

[0048]

[0049] S55. Substituting formula (8) into formula (7) yields:

[0050]

[0051] Preferably, step S6 specifically includes the following steps:

[0052] S61, Grid Frequency Deviation Trigger: Set the frequency change Δf(t) detected at the grid connection point as the frequency regulation trigger signal for the wind farm, and set the frequency dead zone;

[0053] S62. Wind Farm Group Response: Wind turbines within the wind farm are divided into turbine groups, and turbines within the same group are assigned the same auxiliary frequency regulation feedback function and coordination coefficient. The auxiliary frequency regulation feedback function... The expression is as follows:

[0054]

[0055] In the formula, α represents the basic adjustment coefficient of the auxiliary frequency modulation feedback function; γ1 and γ2 both represent the dynamic correction coefficients of the auxiliary frequency modulation feedback function; t A μ1 represents the activation time threshold of the auxiliary frequency modulation feedback function; μ2 and μ1 both represent the time constant of the exponential term.

[0056] Preferably, in step S62, the auxiliary frequency modulation feedback function is corrected using the following correction function g(Δf′,d).

[0057]

[0058] In the formula, d represents the damping coefficient of the correction function; Δf′ represents the corrected frequency deviation reference value.

[0059] Therefore, the present invention employs the above-mentioned centralized-distributed two-layer cooperative frequency support control method, which has the following beneficial effects:

[0060] 1. Dual-constraint modeling: Simultaneously considering speed limit constraints and frequency regulation power limit constraints, the two types of critical disturbance power are estimated through iterative calculations to avoid evaluation bias caused by a single constraint;

[0061] 2. Dynamic iterative correction mechanism: Iteratively solve the critical disturbance power, continuously narrow the interval until convergence, and improve the prediction accuracy;

[0062] 3. Group wind turbines in the wind farm according to their characteristics, and share auxiliary frequency regulation feedback functions and coordination coefficients within the same group to reduce the number of control parameters and improve the feasibility of the project;

[0063] 4. Verify the converter capacity, speed limit and other constraints in the power distribution and control strategy in real time to ensure that the frequency regulation power command does not exceed the equipment limit and extend the life of the wind turbine.

[0064] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0065] Figure 1 This is a flowchart of a centralized-distributed two-layer cooperative frequency support control method according to the present invention.

[0066] Figure 2 This invention provides a multi-wind turbine collaborative control process that considers the collaboration coefficient in a centralized-distributed dual-layer collaborative frequency support control method.

[0067] Figure 3 This is a topology diagram of the improved multi-wind farm 4-unit 13-node example described in the verification example of the present invention;

[0068] Figure 4 This is a diagram showing the system frequency fluctuation after a sudden load increase of 270MW, as described in the verification example of the present invention.

[0069] Figure 5 This is a diagram showing the fluctuation of the total output of each wind farm after a sudden increase of 270MW in load, as described in the verification example of this invention.

[0070] Figure 6 This is a comparison diagram of the equivalent wind turbine speed distribution in each wind farm after a sudden load increase of 270MW, as described in the verification example of the present invention. Detailed Implementation

[0071] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the embodiments of the present invention and are not intended to limit the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.

[0072] It should be noted that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, such as a process, method, system, product, or server that includes a series of steps or units, not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product, or device.

[0073] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0074] like Figure 1 and Figure 2 As shown, a centralized-distributed two-layer cooperative frequency support control method includes the following steps:

[0075] S1. Obtain the operating status parameters of the wind turbine, including wind speed, disturbance power, rotational speed, output power and physical limit parameters;

[0076] S2. Based on the speed limit constraint, the critical disturbance power of the speed constraint type is estimated iteratively.

[0077] Step S2 specifically includes the following steps:

[0078] S21. Initialization: Set the estimated speed-constrained critical disturbance power range to the minimum deficit disturbance power ΔP. L min - Maximum shortfall disturbance power ΔP L max And set the initial speed-constrained disturbance deficit power as Iteration count n = 0;

[0079] S22. Based on the single-mass block transmission system model, construct the rotor motion equations of the wind turbine:

[0080]

[0081] In the formula, P wmP represents the mechanical power captured by the wind turbine. we Indicates the active power output of the wind turbine; H w ω represents the time constant of inertia of the fan rotor. r This represents the rotor speed; t is a time variable.

[0082] S23, Based on the rotational speed range [ω] rmin ,ω rN ], capturing mechanical power P from the wind turbine wm Divided into N LPM The wind turbine captures mechanical power P in the i-th segment by fitting an aerodynamic model. wm,i :

[0083]

[0084] In the formula, ω rmin Indicates the lower limit of the rotor's safe operating speed; ω rN Indicates the upper limit of rotor speed; z 1,i z 2,i and z 3,i All represent the fitting coefficients;

[0085] S24. Substitute formula (1) into formula (2), and change the expected output power of the wind turbine. Considered P we ,get:

[0086]

[0087] S25. Using the MATLAB numerical solver ode45, the fan speed trajectory is obtained by iteratively solving formula (3) to obtain the nth iteration speed trajectory. and lower limit of rotational speed trajectory

[0088] S26. Speed ​​safety threshold judgment: Determine whether the speed safety threshold is met. ε is the convergence accuracy threshold. If satisfied, the speed-constrained critical disturbance power for the nth iteration is output. The estimated speed-constrained critical disturbance power ΔP L,ωlim Otherwise, proceed to step S27;

[0089] S27, Corrected speed-constrained critical disturbance power like Let the speed-constrained critical disturbance power of the (n+1)th iteration be... And order n = n + 1, and return to step S24;

[0090] like Let the speed-constrained critical disturbance power of the (n+1)th iteration be... make When n = n + 1, return to step S24.

[0091] S3. Based on the frequency modulation power limit constraint, the critical disturbance power of the frequency modulation power constraint type is predicted iteratively.

[0092] The frequency modulation power limit constraints mentioned in step S3 include converter capacity, limiting electromagnetic torque, and maximum allowable output power;

[0093] Specifically, it includes the following steps:

[0094] S31. Initialization: Set the estimated frequency modulation power constraint critical disturbance power range to the minimum deficit disturbance power to the maximum deficit disturbance power, and set the initial frequency modulation power constraint disturbance deficit power to [value missing]. Iteration count n = 0;

[0095] S32. Based on the nth iteration rotational speed trajectory obtained in step S25 and lower limit of rotational speed trajectory Maximum output power of computer-side converter

[0096]

[0097] In the formula, This represents the expected output power of the wind turbine in the nth iteration; This represents the rotor speed of the wind turbine at the nth iteration;

[0098] S33. Determine if the condition is met. If satisfied, output the frequency-modulated power-constrained critical disturbance power for the nth iteration. Otherwise, proceed to step S34; P r,max This indicates the maximum output power limit of the machine-side converter;

[0099] S34, Modified frequency modulation power-constrained critical disturbance power like Let the frequency modulation power-constrained critical disturbance power of the (n+1)th iteration be... And order n = n + 1, return to step S32;

[0100] like Let the frequency modulation power-constrained critical disturbance power of the (n+1)th iteration be... And order When n = n + 1, return to step S32.

[0101] In step S3, the estimated frequency modulation power-constrained critical disturbance power ΔP is obtained. L,Plim =min{ΔPL,Prlim ,ΔP L,Twelim ,ΔP L,Pwelim}, ΔP L,Prlim Let ΔP represent the critical disturbance power based on power point tracking constraints. L,Twelim ΔP represents the critical disturbance power based on converter capacity constraints. L,Pwelim This represents the critical disturbance power based on the electrical power output constraint.

[0102] S4. Combine the speed-constrained critical disturbance power and the frequency-controlled critical disturbance power to determine the final critical disturbance power;

[0103] In step S4, the final critical disturbance power ΔP is set. L,th =min{ΔP L,ωlim ,ΔP L,Plim}

[0104] S5. Determine the coordination coefficient based on the final critical disturbance power;

[0105] Step S5 specifically includes the following steps:

[0106] S51. Assume that wind turbines in the same wind turbine group are equivalent to one wind turbine unit, and obtain the frequency regulation power undertaken by the h-th equivalent wind turbine unit in the j-th wind farm. for:

[0107]

[0108] In the formula, OMF FM,j denoted by , where represents the frequency regulation output coefficient of the j-th wind farm; C represents the collaborative allocation coefficient of the wind farm cluster. This represents the rated capacity of the wind turbine group within the j-th wind farm; and Let represent the equivalent capacity and the percentage of equivalent wind turbine capacity of the h-th equivalent wind turbine unit in the j-th wind farm, respectively. Indicates the frequency regulation power command for the wind farm; N sum This represents the total number of wind farms participating in coordinated frequency regulation;

[0109] S52. Establish frequency regulation power of wind turbine units under frequency feedback control. Quantitative relationship between frequency deviation and unit characteristics:

[0110]

[0111] In the formula, k represents the coordination coefficient of the h-th equivalent wind turbine unit within the j-th wind farm; F Indicates the feedback coefficient; Indicates the minimum deviation command for system frequency; H wω represents the time constant of inertia of the fan rotor. r0 The rotor's rated speed is represented by s; the complex frequency variable of the Laplace transform is represented by k. m Represents the mechanical power fitting coefficient; k t Represents the electric power fitting coefficient;

[0112] S53. Substituting formula (6) into formula (5) yields:

[0113]

[0114] S54. Assuming that the wind speed of all wind turbines in all wind farms is the same as the wind speed of the h-th equivalent wind turbine, we get:

[0115]

[0116] S55. Substituting formula (8) into formula (7) yields:

[0117]

[0118] S6. Perform centralized-distributed dual-layer coordinated frequency support control for multiple wind turbines based on the determined coordination coefficients.

[0119] Step S6 specifically includes the following steps:

[0120] S61, Grid Frequency Deviation Trigger: Set the frequency change Δf(t) detected at the grid connection point as the frequency regulation trigger signal for the wind farm, and set the frequency dead zone;

[0121] S62. Wind Farm Group Response: Wind turbines within the wind farm are divided into turbine groups, and turbines within the same group are assigned the same auxiliary frequency regulation feedback function and coordination coefficient. The auxiliary frequency regulation feedback function... The expression is as follows:

[0122]

[0123] In the formula, α represents the basic adjustment coefficient of the auxiliary frequency modulation feedback function; γ1 and γ2 both represent the dynamic correction coefficients of the auxiliary frequency modulation feedback function; t A μ1 represents the activation time threshold of the auxiliary frequency modulation feedback function; μ2 and μ1 both represent the time constant of the exponential term.

[0124] Preferably, in step S62, the auxiliary frequency modulation feedback function is corrected using the following correction function g(Δf′,d).

[0125]

[0126] In the formula, d represents the damping coefficient of the correction function; Δf′ represents the corrected frequency deviation reference value.

[0127] The frequency support control method proposed in this embodiment is essentially designed based on the idea of ​​"centralized decision-making at the upper level and distributed coordination at the lower level". By evaluating the frequency regulation capability of the wind farm and its units in the wind farm central control center, the frequency regulation tasks to be undertaken by each wind farm and the coordinated control parameters of the units in the wind farm are determined, and the decision results are sent to each unit in the wind farm for distributed coordinated control.

[0128] Verification Example

[0129] In this verification example, based on such Figure 3 The improved 4-machine 13-node example with multiple wind farms shown verifies the effectiveness of the invention. The system includes three synchronous turbines and three wind farms: WF1, WF2, and WF3. Wind farms WF1 and WF3 are each replaced by three equivalent wind turbine units, while wind farm WF2 is replaced by two equivalent wind turbine units. The number of turbine units in the three wind farms are 300, 200, and 100, respectively. Detailed turbine parameters are shown in Table 1.

[0130] Table 1 Wind Turbine Parameters

[0131]

[0132]

[0133] Table 2 Wind speed and number of wind turbines at each wind farm

[0134]

[0135] The following strategies are implemented under different disturbance power scenarios: Strategy 1—Wind farms do not participate in frequency regulation; Strategy 2—Wind farms adopt traditional fixed-parameter integrated inertia control (analogous to traditional synchronous units, with droop coefficient set to 20, virtual inertia coefficient set to 2Hw, and frequency regulation time set to 25s); Strategy 3—The cooperative strategy of this application.

[0136] The system's rated frequency was set to 50Hz, and the total system load was 1800MW. The upper limits for converter capacity, electromagnetic torque, and operating output power were set to 0.3pu, 1.2pu, and 1.2pu, respectively; the critical safety lower limit for speed was set to 0.7pu. A load surge event of 270MW (15% of the total load) was simulated at 2 seconds. The results are as follows... Figures 4-6 As shown, when the system experiences load disturbances of varying degrees, the cooperative control strategy proposed in Strategy 3 can effectively raise the minimum system frequency and reduce or even avoid secondary frequency drops. Furthermore, Strategy 3 demonstrates better control performance than Strategy 1 and Strategy 2, thus proving the effectiveness of this application.

[0137] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A centralized-distributed dual-layer coordinated frequency support control method, characterized in that: The method comprises the following steps: S1, acquiring a wind turbine operating state parameter, the wind turbine operating state parameter comprising a wind speed, a disturbance power, a rotating speed, an output power and a physical limit parameter; S2, estimating a rotating speed constraint type critical disturbance power through iteration based on a rotating speed limit value constraint; S3, estimating a frequency modulation power constraint type critical disturbance power through iteration based on a frequency modulation power limit value constraint; S4, fusing the rotating speed constraint type critical disturbance power and the frequency modulation power constraint type critical disturbance power to determine a final critical disturbance power; S5, determining a coordination coefficient based on the final critical disturbance power; S6, performing a multi-wind turbine centralized-distributed double-layer coordination frequency support control based on the determined coordination coefficient; The step S2 specifically comprises the following steps: S22, constructing a wind turbine rotor motion equation based on a single mass block transmission system model: S21, initialization: set the estimated speed-constrained critical disturbance power range to the minimum deficiency disturbance power - maximum deficiency disturbance power and set the initial speed-constrained disturbance deficiency power to , number of iterations ; Otherwise, performing a step S27; （1）； wherein represents the wind turbine captured mechanical power; represents the wind turbine output active power; represents the wind turbine rotor inertia time constant; represents the rotor rotational speed; is a time variable; S23. According to the range of rotational speed captured by the wind turbine into segments, and then fitting the wind turbine captured by the wind turbine : （2）； wherein represents the lower limit of the safe rotational speed of the rotor; represents the upper limit of the rotational speed of the rotor; , and each represents a fitting coefficient; S24, substituting formula (1) into formula (2), and substituting the expected output power of the wind turbine is regarded as , we get: （3）； S25, the numerical solver ode45 of MATLAB is used to iteratively solve formula (3) to obtain the fan speed trajectory, and the first iteration speed trajectory and the lower limit value of the speed trajectory ; S26, rotate speed safety threshold judgment: judge whether to meet , is the convergence precision threshold, if it is met, output the rotate speed constraint type critical disturbance power of the first iteration as the estimated rotate speed constraint type critical disturbance power ;​ The frequency modulation power limit value constraint of the step S3 comprises a converter capacity, a limit electromagnetic torque and a maximum allowable output power; S27, correct the speed constraint type critical perturbation power If , let the speed constraint type critical perturbation power of the first iteration be , let , , and return to step S24; If , let the rotational speed constraint type critical perturbation power of the first iteration be , let , , return to step S24.

2. The centralized-distributed dual-layer collaborative frequency support control method according to claim 1, characterized in that: The step S3 specifically comprises the following steps: The step S5 specifically comprises the following steps: S53, substituting the formula (6) into the formula (5) to obtain: S31, initialization: set the estimated frequency modulation power constraint type critical disturbance power range to the minimum shortage disturbance power ~ the maximum shortage disturbance power, and set the initial frequency modulation power constraint type disturbance shortage power to , the number of iterations ; S32、based on the first iteration speed trajectory obtained in step S25 second iteration speed trajectory and the lower limit value of the speed trajectory computer-side converter output maximum power : （4）； In the formula, Indicates the first The expected output power of the wind turbine in the next iteration; Indicates the first The rotor speed of the wind turbine in the next iteration; S33, judging whether the condition is satisfied , if the condition is satisfied, outputting the frequency modulation power-constrained critical perturbation power of the first iteration , otherwise, executing step S34; , otherwise, executing step S34; denotes the maximum output power limit of the machine-side converter S34, correct the frequency-modulated power constraint type critical fluctuation power : if , let the frequency-modulated power constraint type critical fluctuation power of the th iteration be , and let , , return to step S32; If , let the frequency modulation power constraint type critical perturbation power of the th iteration be , and let , , return to step S32.

3. The centralized-distributed dual-layer collaborative frequency support control method according to claim 2, characterized in that: In step S3, the estimated frequency-modulated power-constrained critical disturbance power is obtained , denotes the critical disturbance power based on the power tracking constraint, denotes the critical disturbance power based on the inverter capacity constraint, denotes the critical disturbance power based on the electrical power output constraint; In step S4, the final critical perturbation power is set .

4. The centralized-distributed dual-layer collaborative frequency support control method according to claim 3, characterized in that: S55, substituting the formula (8) into the formula (7) to obtain: S51, set the equivalent of the fan in the same fan group as a wind turbine, get the first The frequency modulation power of the first Equivalent wind turbine in the first Wind farm is: （5）； In the formula, Indicates the first Frequency regulation output coefficient of a wind farm; This represents the collaborative allocation coefficient of the wind farm cluster; Indicates the first The rated capacity of the wind turbine group within a wind farm; and They represent the first The first wind farm The equivalent capacity of the equivalent wind turbine units and the proportion of equivalent wind turbine capacity; This indicates the frequency regulation power command for the wind farm; This represents the total number of wind farms participating in coordinated frequency regulation; S52, establish the frequency feedback control of wind turbine, frequency modulation power Quantitative relationship between frequency deviation and unit characteristics: （6）； wherein represents the number of wind farms represents the number of equivalent wind turbines represents the number of equivalent wind turbines in the represents the feedback coefficient represents the minimum deviation instruction of the system frequency represents the rotor inertia time constant of the wind turbine represents the rated rotor speed represents the complex frequency variable of the Laplace transform represents the mechanical power fitting coefficient represents the electrical power fitting coefficient The step S6 specifically comprises the following steps: （7）； S54、Assuming that the wind speed of all wind turbines in all wind farm stations is the first the equivalent wind fan, the wind speed is obtained: （8）； ​ （9）。 5. The centralized-distributed dual-layer collaborative frequency support control method according to claim 4, characterized in that: ​ S61, grid frequency deviation trigger: set the frequency change of the grid point is monitored Trigger signal for wind farm frequency modulation, and set the value of the frequency dead zone; S62, wind farm grouping response: wind turbines in the wind farm are divided into groups, and the same auxiliary frequency modulation feedback function and coordination coefficient are set for wind turbines in the same group, wherein the auxiliary frequency modulation feedback function The expression is as follows: （10）； wherein denotes a base regulation coefficient of the auxiliary frequency modulation feedback function; and both denote dynamic correction coefficients of the auxiliary frequency modulation feedback function; denotes an activation time threshold of the auxiliary frequency modulation feedback function; and both denote exponential term time constants.

6. The centralized-distributed dual-layer collaborative frequency support control method according to claim 5, characterized in that: In step S62, the following correction function is utilized Correction auxiliary frequency modulation feedback function : （11）； In the formula, represents a damping coefficient of the correction function; represents a corrected frequency deviation reference value.

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