Active-disturbance-rejection wind power grid-connected power system frequency fluctuation stabilizing method and system and medium

Abstract

The invention discloses an active-disturbance-rejection wind power grid-connected power system frequency fluctuation stabilizing method and system and a medium. The method comprises the steps that a wind power grid-connected system frequency dynamic response model containing a variable-speed wind turbine generator set is established; on the basis of the wind power grid-connected system frequency dynamic response model, observing the real-time state of system frequency deviation, estimating and compensating internal and external comprehensive disturbance of the system, and adjusting the active power output response power grid frequency change of the variable-speed wind turbine generator in real time; the error between the system frequency deviation and the target frequency deviation is monitored in real time, the active power output of the variable-speed wind turbine generator is further adjusted, and wind power integration frequency fluctuation stabilization is achieved. According to the method, the frequency response characteristic of the wind turbine generator is improved, and the influence of wind power fluctuation on the system frequency is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power grid connection, and in particular to a method, system and medium for smoothing frequency fluctuations of a wind power grid connection power system with self-interference resistance. Background Art

[0002] Renewable energy generation represented by wind power has been rapidly developed and gradually replaced traditional thermal power units due to its advantages of cleanliness, low carbon and high efficiency, accelerating the transformation of my country's power system architecture to a new power system dominated by new energy. As one of the most widely used models in the wind power industry, variable-speed wind turbines are connected to the grid through converters, which decouples the rotor speed of the wind turbine from the grid frequency and cannot respond to changes in system frequency. In addition, variable-speed wind turbines usually operate in maximum power point tracking mode and do not have active frequency regulation capabilities. In power systems with a high proportion of wind power connected to the grid, random changes in wind speed can cause large fluctuations in wind power, and the transmission to the grid side may cause the risk of system frequency exceeding the limit, thereby triggering the actions of relay protection devices such as over-frequency cutting and low-frequency load shedding. In severe cases, it may cause a "frequency collapse" of the entire network.

[0003] Wind turbines improve the frequency regulation capability of the power grid through virtual inertial control and energy storage auxiliary control. However, in the face of severe wind power fluctuations causing large frequency deviations, the investment cost of energy storage equipment is high, the adjustment output is constrained by the service life, and the control strategy is complex, so it is difficult to adjust the system frequency in real time according to wind power fluctuations, load demand and real-time status of the power grid, which increases the burden of system frequency regulation. In addition, in response to the problem of power grid frequency fluctuations caused by wind power uncertainty, affected by the multi-variable and nonlinear input and output of wind turbine converters and the slow response of synchronous units, it is difficult to quickly track the random changes in wind power by only calculating the frequency regulation power of variable-speed wind turbines through actual measurement of frequency deviations, which will lead to poor wind turbine frequency regulation and insufficient utilization of rotor kinetic energy. Summary of the invention

[0004] In view of the above-mentioned defects of the prior art, the present invention provides a method, system and medium for smoothing the frequency fluctuations of wind power grid-connected power systems with self-disturbance rejection. Taking into account the multi-variable and nonlinear input and output characteristics of wind turbine converters and the slow response of synchronous units, an "observation + compensation" method is adopted with the help of an self-disturbance rejection control algorithm to solve the nonlinear and uncertain disturbances in the system. For frequency-sensitive mode scenarios, a system frequency fluctuation smoothing strategy based on self-disturbance rejection control is proposed, which improves the frequency stability of the power system under a high proportion of wind power penetration.

[0005] A method for smoothing frequency fluctuations of a wind power grid-connected power system with self-interference resistance comprises the following steps:

[0006] Establish a frequency dynamic response model of wind power grid-connected system containing variable speed wind turbines;

[0007] Based on the frequency dynamic response model of the wind power grid-connected system, observe the real-time state of the system frequency deviation, estimate and compensate for the comprehensive disturbances inside and outside the system, and adjust the active power output of the variable-speed wind turbine in real time to respond to the change of the grid frequency;

[0008] Real-time monitor the error between the system frequency deviation and the target frequency deviation, and further adjust the active power output of the variable-speed wind turbine to achieve the suppression of the frequency fluctuation of the wind power grid connection;

[0009] Furthermore, the specific steps for establishing the frequency dynamic response model of the wind power grid-connected system with variable-speed wind turbines include:

[0010] The rotor side of the variable-speed wind turbine adopts a typical power droop control structure. When the wind turbine suppresses the frequency, the active power regulation increment and the active power reference value are:

[0011] ΔP FR =-K p Δf sys (1)

[0012] P w =P MPPT +ΔP FR (2)

[0013] In the formula: K p =-1 / R is the fixed gain coefficient of the variable-speed wind turbine using power droop control; Δf sys is the frequency deviation between the measured frequency f sys of the AC system and the reference frequency of 50Hz; ΔP FR is the active power output increment of the fan; P w is the active power reference value of the fan; P MPPT is the active power output of the fan in the maximum power point tracking mode.

[0014] The frequency dynamic response model of the system is characterized as:

[0015]

[0016] In the formula: P TSG is the active power reference value of the traditional synchronous unit; P TSG0 is the initial output of the traditional synchronous unit; ΔP TSG is the additional power for frequency modulation of the TSG; P dtb is the power disturbance suffered by the system; P dtb0 is the original basic load of the system; ΔP dtb is the sudden increment of the basic load; H sys is the equivalent inertia time constant of the system; D sys is the equivalent damping coefficient of the system.

[0017] Under the normal operation state of the system, the active power outputs of traditional synchronous units and variable-speed wind turbines satisfy power balance with the base load, that is

[0018] P TSG0 +P MPPT =P dtb0 (4)

[0019] Linearizing the frequency dynamic response model of the system gives:

[0020]

[0021] Where: D sys ′=D sys +K p is the equivalent damping coefficient of the system with variable-speed wind turbines using power droop control.

[0022] Furthermore, based on the frequency dynamic response model of the wind power grid-connected system, observing the real-time state of the system frequency deviation, estimating and compensating for the comprehensive disturbances inside and outside the system, and adjusting the active power output of the variable-speed wind turbine in real time to respond to the change of the grid frequency, the specific steps include:

[0023] Through the linear extended state observer algorithm, the real-time and accurate estimation of the disturbance and the real-time tracking of the system frequency deviation are realized, and the existence and change of the disturbance are sensed, so as to better offset the influence of the disturbance on the frequency regulation process. Let Δf sys =x be the state variable, and according to the linearized system frequency dynamic response model, the state space equation of the system frequency response model is written as:

[0024]

[0025] Where: F(x,E(t)) is the comprehensive disturbance of the wind power grid-connected system, including multiple unknown disturbances that the system may face, such as wind speed uncertainty, response speed of traditional synchronous units, and external load changes; E(t) is the external disturbance that the whole system may be affected by; b 0 is the non-zero disturbance compensation coefficient of the real-time estimation value of the system comprehensive disturbance; u = u(t) and y = y(t) are the control variable input and output of the system respectively.

[0026] The variables in the state space equation can be expressed as:

[0027]

[0028] Introduce the real-time compensation of u(t) through b 0 into the linear extended state observer algorithm to establish real-time online connection with the system:

[0029]

[0030] The expanded observable of F(x, E(t)) is z 2 :

[0031]

[0032] Perform disturbance dynamic compensation linearization on the nonlinear system with wind power frequency modulation.

[0033]

[0034] To realize the observation of system disturbances, expand the state of F(x, E(t)) in the state - space equation and represent it with the state variable x 2 to obtain the following state - space expression:

[0035]

[0036] Where: x 1 is Δf sys , x 2 is the expanded state variable of the system disturbance.

[0037] To accurately and real - time observe the change of the state variable Δf sys and perform "observation + compensation" on the system F(x, E(t)), design the state - observation mechanism and disturbance expansion compensation method in the linear extended - state observer algorithm for suppressing the power - fluctuation of wind power grid - connection, and its output equation is:

[0038]

[0039] Where: z 1 is the observed value of the system for the state variable x 1 ; e is the deviation between the observed value of the state variable and the actual state of the system. η 1 , η 2 are the set control coefficients of the linear extended - state observer algorithm, η 1 takes the value of 2, and η 2 takes the value of 1.

[0040] According to the system - expanded - state - observation design method of the output equation, rewrite the linearized nonlinear system with wind power frequency modulation for disturbance dynamic compensation as:

[0041]

[0042] Furthermore, monitor the error between the real - time system frequency deviation and the target frequency deviation, and further adjust the active power output of the variable - speed wind turbine to realize the suppression of the wind - power grid - connection frequency fluctuation. The specific steps include:

[0043] The influence of the disturbance is cancelled by the linear error state feedback control algorithm, the rotor kinetic energy release intensity of the variable-speed wind turbine following system in real-time frequency state is improved, the wind power fluctuation is suppressed as much as possible, and x 1 tends to Δf sys_ref , and the output of the linear error state feedback control algorithm is designed as:

[0044] u 0 (t) = η 3 (Δf sys_ref - z 1 ) (14)

[0045] Where: η 3 is the control coefficient of the set linear error state feedback control algorithm, η 3 = 1 / 250h 2 , where h is the sampling step, and its value depends on the system control accuracy. Δf sys_ref is the frequency deviation, usually taken as 0.

[0046] Combining the linear extended state observation algorithm and the linear error state feedback control algorithm, the final output of the active power regulation increment when suppressing the frequency of the wind turbine is:

[0047]

[0048] Where, b 0 mainly realizes the compensation of the system F(x, E(t)), and its setting is strongly related to the system inertia time constant.

[0049] Furthermore, the value of b 0 is 1 / (2H sys ).

[0050] An active disturbance rejection system for suppressing the frequency fluctuation of a wind power grid-connected power system, comprising: a computer-readable storage medium and a processor;

[0051] The computer-readable storage medium is used to store executable instructions;

[0052] The processor is used to read the executable instructions stored in the computer-readable storage medium and execute the method for suppressing the frequency fluctuation of the active disturbance rejection wind power grid-connected power system.

[0053] A non-transitory computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the method for suppressing the frequency fluctuation of the active disturbance rejection wind power grid-connected power system is realized.

[0054] The present invention has the following beneficial effects compared with the prior art:

[0055] The present invention realizes accurate real-time observation of the frequency offset and estimation and compensation of comprehensive disturbances inside and outside the system. Based on feedforward control, it monitors in real time the error between the system frequency offset and the target reference frequency offset, and forms a dual closed-loop control structure by integrating the two, which can more effectively suppress unknown comprehensive disturbances in the system and finally offset the impact of disturbances on the frequency fluctuation of the wind power grid-connected system, enhancing the disturbance suppression ability of the wind power grid-connected system. Description of the Drawings

[0056] Figure 1 is a schematic flowchart of a method for suppressing frequency fluctuations in a wind power grid-connected power system with auto-disturbance rejection provided by an embodiment of the present invention;

[0057] Figure 2 is a control structure diagram for suppressing frequency fluctuations in a wind power grid-connected power system with auto-disturbance rejection provided by an embodiment of the present invention;

[0058] Figure 3 is a schematic structural diagram of a four-machine two-area system with wind power grid connection provided by an embodiment of the present invention;

[0059] Figure 4 is a schematic diagram of random wind speed variation provided by an embodiment of the present invention;

[0060] Figure 5 is a schematic diagram of system frequency variation under the conditions of random wind speed and a wind power penetration rate of 25% provided by an embodiment of the present invention;

[0061] Figure 6 is a schematic diagram of the active power output of a wind turbine under the conditions of random wind speed and a wind power penetration rate of 25% provided by an embodiment of the present invention;

[0062] Figure 7 is a schematic diagram of the probability distribution of system frequency deviation under the conditions of random wind speed and a wind power penetration rate of 25% provided by an embodiment of the present invention. Detailed Embodiments

[0063] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0064] Please refer to Figure 1 , the first aspect of the present invention provides a method for suppressing frequency fluctuations in a wind power grid-connected power system with auto-disturbance rejection, including the following steps:

[0065] Step 1: Establish a frequency dynamic response model for a wind power integration system with a variable-speed wind turbine;

[0066] Step 2: Based on the frequency dynamic response model of the wind power integration system, observe the real-time state of the system frequency deviation, estimate and compensate for the comprehensive disturbances inside and outside the system, and adjust the active power output of the variable-speed wind turbine in real time to respond to the change of the grid frequency;

[0067] Step 3: Monitor the error between the system frequency deviation and the target frequency deviation in real time, and further adjust the active power output of the variable-speed wind turbine to suppress the fluctuation of the wind power integration frequency;

[0068] The specific steps for establishing the frequency dynamic response model of the wind power integration system with a variable-speed wind turbine in Step 1 include:

[0069] The rotor side of the variable-speed wind turbine adopts a typical power droop control structure. When the wind turbine suppresses the frequency, the active power regulation increment and the active power reference value are:

[0070] ΔP FR =-K p Δf sys (1)

[0071] P w =P MPPT +ΔP FR (2)

[0072] In the formula: K p =-1 / R is the fixed gain coefficient of the variable-speed wind turbine using power droop control; Δf sys is the frequency deviation between the measured frequency f sys of the AC system and the reference frequency of 50 Hz; ΔP FR is the active power output increment of the fan; P w is the active power reference value of the fan; P MPPT is the active power output of the fan in the maximum power point tracking mode.

[0073] The frequency dynamic response model of the system is characterized as:

[0074]

[0075] In the formula: P TSG is the active power reference value of the traditional synchronous unit; P TSG0 is the initial output of the traditional synchronous unit; ΔP TSG is the additional power for frequency regulation of the TSG; P dtb is the power disturbance suffered by the system; P dtb0 is the original basic load of the system; ΔP dtb is the sudden increment of the basic load; H sys is the equivalent inertia time constant of the system; Dsys is the system equivalent damping coefficient.

[0076] Under the normal operation state of the system, the active power outputs of traditional synchronous units and variable-speed wind turbines and the base load satisfy power balance, that is

[0077] P TSG0 +P MPPT =P dtb0 (4)

[0078] Linearizing the frequency dynamic response model of the system gives:

[0079]

[0080] Where: D sys ′ = D sys +K p is the system equivalent damping coefficient of the system with variable-speed wind turbines adopting power droop control.

[0081] The second step is based on the frequency dynamic response model of the wind power grid-connected system, observes the real-time state of the system frequency deviation, estimates and compensates for the comprehensive internal and external disturbances of the system, and adjusts the active power output of the variable-speed wind turbine in real time to respond to the change of the grid frequency. The specific steps include:

[0082] The real-time and accurate estimation of the disturbance and the real-time tracking of the system frequency deviation are realized through the linear extended state observer algorithm, and the existence and change of the disturbance are sensed, so as to better offset the influence of the disturbance on the frequency modulation process. Let Δf sys =x be the state variable. According to the linearized system frequency dynamic response model, the state space equation of the system frequency response model is written as:

[0083]

[0084] Where: F(x, E(t)) is the comprehensive disturbance of the wind power grid-connected system, including multiple unknown disturbances that the system may face, such as wind speed uncertainty, response speed of traditional synchronous units, and external load changes; E(t) is the external disturbance that the whole system may be subject to; b 0 is the non-zero disturbance compensation coefficient of the real-time estimated value of the system comprehensive disturbance; u = u(t) and y = y(t) are the control variable input and output of the system respectively.

[0085] The variables in the state space equation can be expressed as:

[0086]

[0087] Introduce the real-time compensation of u(t) through b 0 into the linear extended state observer algorithm to establish a real-time online connection with the system:

[0088]

[0089] The extended observable of F(x, E(t)) is z 2 :

[0090]

[0091] Perform perturbation dynamic compensation linearization on the non - linear system with wind power frequency modulation.

[0092]

[0093] To achieve the observation of system perturbations, expand the state of F(x, E(t)) in the state - space equation and use the state variable x 2 to represent it, and then obtain the following state - space expression:

[0094]

[0095] where: x 1 is Δf sys , x 2 is the extended state variable of the system perturbation.

[0096] To achieve accurate and real - time observation of the change of the state variable Δf sys and the "observation + compensation" of the system F(x, E(t)), design the state - observation mechanism and the perturbation expansion compensation method in the linear extended state observation algorithm for suppressing the power fluctuation of wind power grid connection. Its output equation is:

[0097]

[0098] where: z 1 is the observed value of the system for the state variable x 1 ; e is the deviation between the observed value of the state variable and the actual state of the system. η 1 , η 2 are the set control coefficients of the linear extended state observation algorithm. η 1 takes the value of 2, and η 2 takes the value of 1.

[0099] According to the system extended state observation design method of the output equation, rewrite the perturbation dynamic compensation of the linearized non - linear system with wind power frequency modulation as:

[0100]

[0101] The third step mentioned above monitors the error between the system frequency deviation and the target frequency deviation in real - time, and further adjusts the active power output of the variable - speed wind turbine to achieve the suppression of the frequency fluctuation of wind power grid connection. The specific steps include:

[0102] The influence of the disturbance is cancelled by the linear error state feedback control algorithm, the rotor kinetic energy release force of the variable-speed wind turbine following the real-time frequency state of the system is increased, the wind power fluctuation is suppressed as much as possible, so that x 1 tends to Δf sys_ref . The output of the linear error state feedback control algorithm is designed as:

[0103] u 0 (t) = η 3 (Δf sys_ref - z 1 ) (14)

[0104] In the formula: η 3 is the control coefficient of the set linear error state feedback control algorithm, η 3 = 1 / 250h 2 , where h is the sampling step, and its value depends on the system control accuracy. Δf sys_ref is the frequency deviation, usually taken as 0.

[0105] Combining the linear extended state observation algorithm and the linear error state feedback control algorithm, the finally output active power regulation increment when suppressing the frequency of the wind turbine is:

[0106]

[0107] In the formula, b 0 mainly realizes the compensation of the system F(x, E(t)), and its setting is strongly related to the system inertia time constant, that is, b 0 can be taken as 1 / (2H sys ).

[0108] The embodiment of the present invention adopts Figure 2 the shown auto-disturbance rejection control method for suppressing the frequency fluctuation of the wind power grid-connected power system, and conducts simulation analysis in the Figure 3 shown four-machine two-area system with wind power grid connection. Figure 4 shows the influence of the active power output of the wind turbine on the system frequency change characteristics when the wind power is at a low penetration rate of 25% under the random continuous variable wind speed condition based on the average wind speed of 8.42 m / s, comparing the four cases of adding the control of the present invention, variable gain droop control, traditional fixed gain droop control, and no frequency modulation control to the wind turbine. In the case of no frequency modulation control, since there is a decoupling relationship between the rotational speed of the wind turbine and the system frequency, the active power output of the unit cannot effectively respond to the change of the system frequency, and the system mainly provides frequency support to the power grid by traditional synchronous units to suppress the frequency fluctuation. At this time, the random fluctuation of the wind speed will cause significant fluctuations in the system frequency and the active power output of the wind turbine, such as Figure 5 , 6As shown. The present invention exhibits excellent frequency modulation performance in the embodiments. When the wind turbine adopts the present invention, the over-frequency Δf max and the under-frequency Δf max are respectively reduced by 67.26%, 27.73%, 3.95% and 48.70%, 17.78%, 26.37% compared with the maximum power point tracking, fixed gain, and variable gain controls. In addition, from the Figure 7 schematic diagram of the probability distribution of the system frequency deviation shown, it can be seen that the probability that the steady-state frequency deviation of the present invention is concentrated in the range of ±0.1 Hz is greater than that of the other three control methods.

[0109] Another embodiment of the present invention provides a disturbance rejection wind power grid-connected power system frequency fluctuation suppression system, including: a computer-readable storage medium and a processor;

[0110] The computer-readable storage medium is used to store executable instructions;

[0111] The processor is used to read the executable instructions stored in the computer-readable storage medium and execute the disturbance rejection wind power grid-connected power system frequency fluctuation suppression method.

[0112] Another embodiment of the present invention provides a non-transitory computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the disturbance rejection wind power grid-connected power system frequency fluctuation suppression method is realized.

[0113] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories, CD-ROMs, optical memories, etc.) containing computer-usable program codes.

[0114] The present application is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram can be realized by computer program instructions, and the combination of the processes and / or blocks in the flowchart and / or block diagram can also be realized by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate means for realizing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0115] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to operate in a particular manner, such that the instructions stored in the computer-readable memory produce a manufacture including an instruction device that implements the functions specified in one or more processes and / or blocks Figure 1 of the process or processes and / or blocks Figure 1 of the block or blocks.

[0116] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, whereby the instructions executed on the computer or other programmable apparatus provide steps for implementing the functions specified in one or more processes and / or blocks Figure 1 of the process or processes and / or blocks Figure 1 of the block or blocks.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent replacements can still be made to the specific embodiments of the present invention. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A method for smoothing frequency fluctuations of wind power grid-connected power systems with self-interference resistance, characterized in that: The steps include: Establish a frequency dynamic response model of wind power grid-connected system containing variable speed wind turbines; Based on the wind power grid-connected system frequency dynamic response model, the real-time state of the system frequency deviation is observed, the comprehensive disturbance inside and outside the compensation system is estimated, and the active output of the variable-speed wind turbine is adjusted in real time to respond to the change of the grid frequency; The error between the system frequency deviation and the target frequency deviation is monitored in real time, and the active output of the variable-speed wind turbine is further adjusted to achieve the smoothing of wind power grid-connected frequency fluctuations.

2. The method for smoothing frequency fluctuations of wind power grid-connected power systems with active disturbance rejection according to claim 1, characterized in that: The specific steps of establishing a frequency dynamic response model of a wind power grid-connected system including a variable speed wind turbine generator system include: The rotor side of the variable speed wind turbine adopts a typical power droop control structure. When the wind turbine frequency is stabilized, the active power adjustment increment and active power reference value are: ΔP FR =-K p Δf sys (1) P w =P MPPT +ΔP FR (2) Where: K p =-1 / R is the fixed gain coefficient of the variable speed wind turbine using power droop control; Δf sys f is the measured frequency of the AC system sys Frequency deviation from the reference frequency 50Hz; ΔP FR P is the active output increment of the fan; w P is the reference value of the fan active power; MPPT It is the active power output of the wind turbine in the maximum power point tracking mode; The frequency dynamic response model of wind power grid-connected system is characterized as follows: Where: P TSG is the active power reference value of the traditional synchronous unit; P TSG0 is the initial output of the traditional synchronous unit; ΔP TSG Increase power for TSG frequency modulation; P dtb is the power disturbance of the system; P dtb0 is the original basic load of the system; ΔP dtb H is the sudden increase of basic load; sys is the system equivalent inertia time constant; D sys is the system equivalent damping coefficient; Under normal system operation, the active output of traditional synchronous units and variable speed wind turbines meets the power balance with the basic load, that is, P TSG0 +P MPPT =P dtb0 (4) The frequency dynamic response model of wind power grid-connected system is linearized to obtain: Where: D sys ′=D sys +K p It is the equivalent damping coefficient of the system with variable speed wind turbine using power droop control.

3. The method for smoothing frequency fluctuations of wind power grid-connected power systems with active disturbance rejection as claimed in claim 2, characterized in that: Based on the wind power grid-connected system frequency dynamic response model, the real-time state of the system frequency deviation is observed, the comprehensive disturbance inside and outside the compensation system is estimated, and the active output of the variable speed wind turbine is adjusted in real time to respond to the change of the grid frequency. The specific steps include: The linear extended state observation algorithm is used to accurately estimate the disturbance in real time and track the system frequency deviation in real time, so as to sense the existence and change of the disturbance and better offset the influence of the disturbance on the frequency modulation process. sys =x as the state variable, according to the linearized system frequency dynamic response model, the state space equation of the system frequency response model is written as: Where: F(x, E(t)) is the comprehensive disturbance of the wind power grid-connected system, including multiple unknown disturbances that the system may face, such as wind speed uncertainty, the response speed of traditional synchronous units, and external load changes; E(t) is the external disturbance that the entire system may be subject to; b0 is the non-zero disturbance compensation coefficient of the real-time estimated value of the system comprehensive disturbance; u = u(t) and y = y(t) are the control variable input and output of the system respectively; The variables in the state space equation are expressed as: u(t) is introduced into the linear extended state observation algorithm through b0 real-time compensation to establish real-time online connection with the system: The expanded observation of F(x,E(t)) is z2: Perform disturbance dynamic compensation linearization on nonlinear systems including wind power frequency modulation; In order to observe the system disturbance, the state space equation F(x, E(t)) is expanded and represented by the state variable x2, and the following state space expression is obtained: Where: x1 is Δf sys , x2 is the expanded state variable of the system disturbance; To achieve the state variable Δf sys Accurate and real-time observation of changes and "observation + compensation" of the system F(x, E(t)) are designed to smooth the power fluctuation of wind power grid-connected linear expansion state observation algorithm and the disturbance expansion compensation method. The output equation is: Where: z1 is the observed value of the system for the state variable x1; e is the deviation between the observed value of the state variable and the actual state of the system; η1 and η2 are the set control coefficients of the linear extended state observation algorithm, η1 is 2, and η2 is 1; According to the system extended state observation design method of the output equation, the linearized nonlinear system with wind power frequency modulation is rewritten for disturbance dynamic compensation as follows:

4. The method for smoothing frequency fluctuations of wind power grid-connected power systems with active disturbance rejection as claimed in claim 3, characterized in that: The real-time monitoring system frequency deviation and the target frequency deviation error are further adjusted to adjust the active output of the variable speed wind turbine to achieve the smoothing of wind power grid-connected frequency fluctuations. The specific steps include: The influence of disturbance is offset by linear error state feedback control algorithm, the rotor kinetic energy release of variable speed wind turbine is improved to follow the real-time frequency state of the system, and the wind power fluctuation is suppressed as much as possible, so that x1 tends to Δf sys_ref , the output of the linear error state feedback control algorithm is designed as: u0(t)=η3(Δf sys_ref -z1) (14) Where: η3 is the control coefficient of the set linear error state feedback control algorithm, η3 = 1 / 250h 2 , where h is the sampling step length, the value depends on the system control accuracy, Δf sys_ref is the frequency deviation; Combining the linear extended state observation algorithm and the linear error state feedback control algorithm, the designed wind turbine frequency smoothing active power regulation increment output is: Where b0 is mainly used to realize the compensation of system F(x, E(t)), and its setting is strongly related to the system inertia time constant.

5. The method for smoothing frequency fluctuations of wind power grid-connected power systems with active disturbance rejection as claimed in claim 4, characterized in that: b0 is 1 / (2H sys ).

6. The method for smoothing frequency fluctuations of wind power grid-connected power systems with active disturbance rejection as claimed in claim 4, characterized in that: Frequency deviation Δf sys_ref The value is 0.

7. A frequency fluctuation smoothing system for wind power grid-connected power system with self-interference resistance, comprising: A computer readable storage medium and a processor; The computer-readable storage medium is used to store executable instructions; The processor is used to read the executable instructions stored in the computer-readable storage medium to execute the method for smoothing frequency fluctuations of a wind power grid-connected power system with self-disturbance rejection according to any one of claims 1-6.

8. A non-transitory computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the method for smoothing frequency fluctuations of a wind power grid-connected power system with active disturbance rejection according to any one of claims 1 to 6 is implemented.

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