Segmented speed recovery control and multi-dimensional evaluation method for wind power frequency regulation

Abstract

The present invention proposes a segmented speed recovery control for wind power frequency regulation and a multi-dimensional evaluation method thereof, which relates to the field of wind turbine frequency regulation. According to the power grid system frequency response model, the wind turbine aerodynamic model and the wind turbine power response model under the GFM control strategy, a multi-dimensional speed recovery evaluation index system is constructed; a segmented speed recovery control strategy is formulated, and the recovery process is divided into three stages: aerodynamic power recovery, wind turbine power recovery and final speed recovery. The power control function of each stage is designed, and each recovery stage is optimized using the evaluation index system; according to the characteristics of the rotor kinetic energy release type grid-type wind turbine during frequency regulation operation, a segmented speed recovery strategy is formulated to embed the traditional grid-type wind turbine control strategy. The present application constructs a multi-dimensional evaluation framework, formulates a segmented recovery strategy and optimizes parameters in real time, quantitatively evaluates the speed recovery performance, balances the secondary frequency drop suppression and recovery rate, and improves the frequency support capability of the wind turbine.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbine frequency regulation, and in particular to a segmented speed recovery control for wind power frequency regulation and a multi-dimensional evaluation method thereof. Background Art

[0002] As renewable energy, primarily powered by power electronics, continues to grow in the grid, the number of traditional synchronous generators decreases, leading to a reduction in the power system's moment of inertia and weakened frequency regulation capabilities, posing a challenge to the safe and stable operation of the grid. Therefore, improving the dynamic frequency support capabilities of wind turbines has become a key issue in maintaining the safe operation of high-penetration renewable power grids.

[0003] Currently, technical solutions for wind turbine frequency regulation (FR) fall into two main categories: additional energy storage systems (ESS) and utilizing wind turbine rotor kinetic energy. In ESS solutions, energy storage devices are coordinated or connected in parallel to the wind turbine's DC bus, enabling rapid response to power demands on a timescale of minutes to hours. However, ESSs typically operate independently of the wind turbine, increasing system complexity and cost. In contrast, rotor kinetic energy solutions release kinetic energy from the wind turbine's rotor-shaft system, providing frequency support on a timescale of seconds. These solutions offer the advantages of fast response and the absence of additional equipment. However, after the kinetic energy is released, this solution requires reducing wind turbine power to restore speed, causing new active power disturbances in the grid and potentially leading to a secondary frequency drop (SFD) in the grid frequency. Alternatively, there are solutions that increase rotor kinetic energy reserves by operating the wind turbine at overspeed. However, these solutions do not operate the wind turbines continuously in maximum power point tracking (MPPT) conditions, resulting in reduced power generation efficiency and economic losses.

[0004] The operating process of frequency regulation based on rotor kinetic energy can be divided into two stages: kinetic energy release and speed recovery.

[0005] (1) Kinetic energy release phase: Increase wind turbine output power to achieve grid frequency support. Mainstream control strategies include grid following (GFL) and grid forming (GFM). Traditional GFL strategies rely on grid voltage measurement and have limited performance under weak grid conditions. GFM strategies use virtual synchronous generator technology to simulate the inertial response and primary frequency regulation of synchronous machines, providing stable frequency support capabilities under complex grid conditions.

[0006] (2) Speed ​​recovery phase: Reduce the wind turbine output power to restore the rotor speed to the MPPT operating state. Existing MPPT-based recovery strategies are prone to significant secondary frequency drops. While speed recovery strategies that use power limit load reduction or flexible load reduction can suppress disturbances to a certain extent, there is a problem of mutual constraints between the recovery speed and the disturbance amplitude, making coordinated optimization difficult.

[0007] With the increase in wind turbine capacity and wind power penetration, wind farm clusters contain considerable kinetic energy. Utilizing rotor kinetic energy to enhance wind turbine frequency regulation has become an inevitable trend. Furthermore, improving speed recovery after kinetic energy release is crucial for improving wind turbine frequency regulation and maintaining grid frequency security.

[0008] Existing research on the speed recovery process mainly focuses on suppressing the secondary frequency drop of the power grid. There is insufficient analysis of the dynamic characteristics of the entire speed recovery process, making it difficult to take into account the dual requirements of rapid speed recovery and grid frequency stability.

[0009] In summary, in grids with a high proportion of renewable energy, actively supporting grid frequency with wind turbines by releasing rotor kinetic energy still faces two core challenges: first, balancing the speed recovery rate with the magnitude of the secondary dip in grid frequency to achieve rapid speed recovery while suppressing grid frequency disturbances; and second, quantifying and characterizing the speed recovery characteristics to optimize the speed recovery process. A more efficient and adaptive speed recovery control method and a multi-dimensional, quantifiable speed recovery characteristic evaluation method are urgently needed to improve the frequency support capabilities of wind turbines in new power systems with a high proportion of renewable energy. Summary of the Invention

[0010] In order to solve the above problems, the present invention proposes a segmented speed recovery control for wind power frequency regulation and its multidimensional evaluation method, so as to achieve coordinated optimization between the recovery rate and the secondary frequency drop disturbance, and quantitatively evaluate the speed recovery performance, thereby enhancing the wind turbine's active frequency support capability for the power grid.

[0011] In order to achieve the above object, the present invention adopts the following technical solutions:

[0012] In a first aspect, the present invention provides a segmented speed recovery control for wind power frequency regulation and a multi-dimensional evaluation method thereof, comprising:

[0013] A multi-dimensional speed recovery evaluation index system is constructed based on the power grid system frequency response model, wind turbine aerodynamic model and wind turbine power response model under the GFM control strategy.

[0014] Develop a segmented speed recovery control strategy, dividing the speed recovery process into three stages: aerodynamic power recovery, wind turbine power recovery, and final speed recovery. Design power control functions for each stage, and use the evaluation index system to optimize each recovery stage in real time.

[0015] According to the characteristics of the grid-type wind turbine with rotor kinetic energy release during frequency modulation operation, a segmented speed recovery strategy is formulated to embed the control strategy of the traditional grid-type wind turbine.

[0016] In a second aspect, the present invention provides a wind turbine generator set comprising a wind turbine generator set body and a control component, wherein the control component is configured to execute the steps of a segmented speed recovery control method for wind power frequency regulation and a multi-dimensional evaluation method thereof as described in the first aspect.

[0017] In a third aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of a segmented speed recovery control method for wind power frequency regulation and a multi-dimensional evaluation method thereof as described in the first aspect.

[0018] In a fourth aspect, the present invention provides a computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the steps of a segmented speed recovery control for wind power frequency regulation and a multi-dimensional evaluation method thereof as described in the first aspect are implemented.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The present invention makes an important contribution to the existing problems of wind turbines participating in grid frequency regulation in new power systems with a high proportion of renewable energy. On the one hand, the segmented speed recovery strategy developed can achieve refined control for the targets at different stages of the speed recovery process, making up for the limitations of existing speed recovery control methods that only focus on speed recovery or frequency secondary drop suppression, and achieve coordinated optimization of speed recovery and secondary frequency drop, significantly improving the frequency support capability of wind turbines in complex power grid environments, and providing key technical support for maintaining the safe operation of high-penetration renewable power grids. On the other hand, by constructing a multi-dimensional speed recovery evaluation method, the dynamic characteristics of the speed recovery process can be accurately and comprehensively evaluated, making up for the shortcomings of existing evaluation methods that only consider secondary frequency drop conditions, and providing an important extension and supplement to the wind turbine frequency regulation performance evaluation method.

[0021] (2) This invention utilizes the operating state characteristics of different stages in the speed recovery process to refine the speed recovery process into the aerodynamic power recovery stage, the wind turbine power recovery stage, and the final speed recovery stage. Guided by the operating states and goals of different stages, a segmented speed recovery control method is designed. This method can achieve refined control of the speed recovery speed and secondary disturbances of the grid frequency, optimize the overall speed recovery process performance, and further improve the wind turbine's active support capability for the grid frequency.

[0022] (3) For the speed recovery process, this paper proposes a multi-dimensional speed recovery characteristic quantitative evaluation method that includes five indicators: maximum frequency deviation (during the secondary frequency drop), maximum frequency change rate (during the secondary frequency drop), aerodynamic power recovery duration, wind turbine power change intensity, and power generation loss. This method takes into account the local characteristics of the secondary frequency drop and power recovery speed of the power grid, as well as the overall characteristics of power and electricity during the speed recovery period. It can achieve a quantitative evaluation of existing speed recovery strategies and provide clear directional guidance for the optimization design of new speed recovery control strategies.

[0023] (4) The present invention achieves seamless switching between frequency regulation operation and normal operation by dynamically comparing the aerodynamic power of the wind turbine with the power of the wind turbine generator set. This design avoids conflicts between different control strategies, ensuring that the rotor enters the speed recovery stage in a timely manner after the kinetic energy is released, and automatically returns to the efficient power generation state after the recovery is completed. The dynamic switching mechanism can significantly improve the operating efficiency of the wind turbine generator set, while suppressing the secondary frequency drop of the power grid and reducing the power generation loss caused by continuous non-MPPT operation. In addition, this embedded method relies on real-time power characteristic judgment to enhance the adaptability of the wind turbine generator set to complex power grid conditions, providing a key technical path for the frequency support capability and economic balance of the generator set in a high proportion of renewable energy power grid, and can effectively improve the system frequency stability and operational reliability.

[0024] (5) This invention designs a segmented speed recovery control method and an embedding method with the traditional grid-type wind turbine control strategy. Based on the proposed multi-dimensional evaluation method, a comparative analysis of the existing speed recovery control method and the designed segmented speed recovery method was conducted under the conditions of 10% and 30% wind power penetration, verifying the significant superiority and applicability of the proposed method.

[0025] Advantages of additional aspects of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their description are used to explain the present invention but do not constitute a limitation of the present invention.

[0027] Figure 1 A main flow chart of a segmented speed recovery control and multi-dimensional evaluation method for wind power frequency regulation provided by an embodiment of the present invention;

[0028] Figure 2 A schematic diagram of an active power control strategy for a grid-connected wind turbine generator system according to an embodiment of the present invention;

[0029] Figure 3 Schematic diagram of power control paths for different speed recovery methods provided by an embodiment of the present invention;

[0030] Figure 4 A schematic diagram of system frequency response (corresponding to a 10% load step disturbance) at different wind power penetration levels provided by an embodiment of the present invention;

[0031] Figure 5 Schematic diagram of the definition of system frequency response parameters and a schematic diagram of the dynamic model of the wind turbine rotor speed recovery phase provided by an embodiment of the present invention; wherein (a) is a schematic diagram of the definition of system frequency response parameters, and (b) is a schematic diagram of the dynamic model;

[0032] Figure 6 The inertia time constant of frequency modulation power load reduction of different wind turbines provided by the embodiment of the present invention System power imbalance under Schematic diagram of change trend and relative frequency deviation ( ) Schematic diagram of the change trend; where (a) represents the system power imbalance Schematic diagram of the change trend, (b) represents the relative frequency deviation ( ) Schematic diagram of changing trends;

[0033] Figure 7 A schematic diagram of the speed recovery process and corresponding evaluation indicators provided by an embodiment of the present invention;

[0034] Figure 8 A schematic diagram of a segmented speed recovery power control path provided by an embodiment of the present invention;

[0035] Figure 9 A flow chart of the design of a segmented speed recovery strategy provided by an embodiment of the present invention;

[0036] Figure 10 A schematic diagram of a control strategy for a grid-type wind turbine generator system including segmented speed recovery control provided by an embodiment of the present invention;

[0037] Figure 11 A power system topology diagram of a wind farm grid-connected operating condition provided by an embodiment of the present invention;

[0038] Figure 12Detailed operating status waveforms of a single wind turbine provided by an embodiment of the present invention; wherein, (a) displays the change of the grid frequency over time; (b) displays the change of the wind turbine stator phase voltage over time; (c) displays the change of the wind turbine stator current over time; (d) displays the change of the wind turbine excitation current over time; (e) displays the change of the grid-side converter current over time; (f) displays the change of the wind turbine stator power over time; (g) displays the change of the grid-side converter power over time; (h) displays the change of the wind turbine output power over time; (i) displays the change of the wind turbine rotor speed over time; (j) displays the change of the wind turbine virtual power angle over time; (k) displays the change of the wind turbine virtual excitation potential over time;

[0039] Figure 13 Frequency and power response waveforms of a power system with a 10% wind power penetration rate under load step conditions, provided by an embodiment of the present invention; (a) shows the time-varying frequency of the grid; (b) shows the time-varying output power of the synchronous generator; (c) shows the time-varying output power of the wind turbine;

[0040] Figure 14 Figure 1 shows the time-varying speed recovery performance indicators for a 10% wind power penetration scenario provided by an embodiment of the present invention (all values ​​are normalized to the baseline of Method 4). (a) shows the time-varying MPD indicator, (b) shows the time-varying MFD indicator, (c) shows the time-varying APRT indicator, (d) shows the time-varying PTI-2 indicator, and (e) shows the time-varying TEDL indicator.

[0041] Figure 15 A comparison chart of the speed recovery performance indicators of the four methods provided in the embodiments of the present invention in a scenario with a 10% wind power penetration rate;

[0042] Figure 16 Frequency and power response waveforms of a power system with a 30% wind power penetration rate under load step conditions, provided by an embodiment of the present invention; (a) shows the time-varying grid frequency; (b) shows the time-varying synchronous generator output power; and (c) shows the time-varying wind turbine output power (all values ​​are normalized to the baseline of Method 4).

[0043] Figure 17 A comparison chart of the speed recovery performance indicators of the four methods provided in the embodiments of the present invention in a scenario with a 30% wind power penetration rate. DETAILED DESCRIPTION

[0044] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0045] Example 1

[0046] like Figure 1 As shown, this embodiment discloses a segmented speed recovery control and multi-dimensional evaluation method for wind power frequency regulation, including the following steps:

[0047] Step 1: Construct a multi-dimensional speed recovery evaluation index system based on the power grid system frequency response model, wind turbine aerodynamic model, and wind turbine power response model under the GFM control strategy;

[0048] Step 2: Develop a segmented speed recovery control strategy, dividing the speed recovery process into three stages: aerodynamic power recovery, wind turbine power recovery, and final speed recovery. Design power control functions for each stage, and use the evaluation index system to optimize each recovery stage in real time.

[0049] Step 3: According to the characteristics of the grid-type wind turbine with rotor kinetic energy release during frequency modulation operation, a segmented speed recovery strategy is developed to embed the control strategy of the traditional grid-type wind turbine.

[0050] The following combination Figure 1 , a segmented speed recovery control for wind power frequency regulation and a multi-dimensional evaluation method thereof disclosed in this embodiment are described in detail.

[0051] The effectiveness and challenges of various technical solutions for wind turbine frequency regulation, whether using additional energy storage systems or utilizing rotor kinetic energy, are closely related to the system's frequency response characteristics. Therefore, in order to explore effective ways to enhance the dynamic frequency support capabilities of wind turbines, it is necessary to first analyze the nature of the power system's frequency response. By clarifying the model and characteristics of the system's frequency response, we can accurately identify the key changes in the system's frequency response after a high proportion of renewable energy is integrated, providing a theoretical basis for optimizing wind turbine frequency regulation strategies.

[0052] (1) Model and characteristics of system frequency response

[0053] Fundamentally, system frequency response is the transient process of dynamically redistributing power between sources and loads based on various frequency characteristics when active power is unbalanced on the grid. In traditional power systems, the frequency response of synchronous generators (SGs) and loads determines the system frequency response (SFR). However, as wind power capacity and its contribution to total power generation increase, the frequency response characteristics of wind power will alter the system frequency response.

[0054] 1. Conventional system frequency response model

[0055] (1) Synchronous generator frequency response model

[0056] The frequency response model of a synchronous generator is usually derived from the rotor dynamic equations:

[0057]

[0058] Where, is the mechanical power, is the electromagnetic power, is the rotational speed, J is the moment of inertia, D is the damping coefficient, is the speed change, It's time.

[0059] Power systems often contain multiple synchronous generators. Due to the differences in parameters between the units, interactions between them are inevitable, which complicates the overall frequency response model of the system. To simplify the overall frequency response model, the analysis will first focus on the steady-state component of the frequency response of each unit within the frequency regulation time range, that is, the common frequency characteristic:

[0060]

[0061] Where, is the interference power, It is i The frequency-to-power transfer function of a synchronous motor is given by equation (1). The speed regulator is introduced and the following assumptions are considered:

[0062] ① Constant generator terminal voltage: This isolates the frequency response by separating frequency dynamics from transient effects of the excitation system (such as automatic voltage regulators and power system stabilizers).

[0063] ②Linearized speed regulator: The synchronous generator set speed regulator model eliminates nonlinear effects such as speed regulator dead zone and actuator saturation limit.

[0064] Frequency to power transfer function of synchronous motor It can be written as follows:

[0065]

[0066] In the formula, the subscript i Indicates the i Parameters of a synchronous generator unit. is the primary frequency modulation (PFR) droop coefficient, is the equivalent time constant of the speed regulator system, represents the Laplace operator.

[0067] Furthermore, formula (3) is a general frequency response model of synchronous units. Given the similarity of the model structures, it can be combined to obtain the aggregate frequency response model of multiple synchronous generators:

[0068]

[0069] Where, 、 、 It represents the equivalent moment of inertia, equivalent damping coefficient and primary frequency modulation droop coefficient of the synchronous generator after aggregation.

[0070] (2) Load frequency response model

[0071] The load, mainly composed of motors, has frequency regulation characteristics. Within a single frequency modulation control time range, this embodiment only considers the steady-state frequency characteristics of the load and ignores its dynamic response to the frequency change rate, thereby simplifying the load frequency response model and reducing the order of its frequency response model.

[0072]

[0073] Where, is the load regulation power, is the load droop coefficient, It is the grid frequency change.

[0074] 2. Wind farm frequency response model

[0075] (1) Wind power frequency support principles and stages

[0076] Wind turbines provide frequency support for the grid, relying primarily on the kinetic energy stored in their shafts to provide additional power when the grid frequency drops. This process can be broken down into two phases with opposing characteristics: kinetic energy release (where the wind turbine releases rotor kinetic energy to provide frequency support) and speed recovery (where kinetic energy is replenished).

[0077] (2) Power characteristics of wind turbines during the kinetic energy release phase

[0078] Wind turbines are connected to the grid via power electronic converters or controlled by power electronic converters, with their frequency response determined by power control strategies. This structure facilitates flexible and controllable frequency regulation, but also increases the complexity of wind turbine aerodynamics.

[0079] The aerodynamic model of the wind turbine generator system used in this embodiment is:

[0080]

[0081] Where, represents the aerodynamic power of the wind turbine, ρis the air density, R represents the rotor radius, is a function of the wind energy utilization coefficient (depending on the wind tip speed ratio λ and propeller angle ), v is the wind speed, is the rotational speed, is an intermediate variable.

[0082] Assuming that the change of wind speed within the time range of one frequency modulation in seconds is negligible, the aerodynamic power of the wind turbine is Will only be related to the speed Then equation (5) can be simplified to a single variable function:

[0083]

[0084] In terms of power control, the virtual synchronous generator (VSG) strategy is a typical grid-based control strategy. This method embeds the power control model of the synchronous generator into the outer loop power control of the wind turbine, thereby simulating the output characteristics of the synchronous generator. The control structure is as follows: Figure 2 shown.

[0085] Due to the similarity between the power characteristics of wind turbines and synchronous turbines under the grid-type strategy, the transfer function from frequency to power of wind turbines is Similar to the synchronous unit structure in formula (3), as shown in formula (8):

[0086]

[0087] In the formula, the subscript i Indicates the i Parameters of a wind turbine. 、 、 and represent virtual inertia, virtual damping, virtual droop coefficient and equivalent transfer function of frequency modulation control respectively.

[0088] Comparing the frequency responses of the wind turbine in equation (8) and the synchronous generator in equation (3), it can be found that although their inertia and damping coefficients are similar, their primary frequency regulation mechanisms are different. This difference can be attributed to two main factors:

[0089] ① Fast power response: The PFR power output of the wind turbine is not affected by the inertia of the speed regulator, and can achieve fast active power injection after the frequency drops.

[0090] ② Aerodynamic coupling: Increasing the active power output of the wind turbine will lead to a decrease in speed (determined by the wind turbine shaft system dynamics in formula (9)), thereby reducing the wind turbine aerodynamic power and restricting the frequency modulation power.

[0091]

[0092] Where, represents the aerodynamic power of the wind turbine, Indicates the output power of the wind turbine. Represents the moment of inertia of the wind turbine shaft system.

[0093] For the wind turbine frequency response transfer function in formula (8), different primary frequency regulation control links This will result in different frequency responses. Two representative schemes for primary frequency regulation control of grid-connected wind turbines are as follows:

[0094] ①Similar scheme to the primary frequency regulation of synchronous units (excluding the lag link of the synchronous unit speed regulator)

[0095]

[0096] Although this method can achieve higher frequency modulation power, the significant reduction in power at the end of frequency modulation will cause grid power disturbance and lead to a large secondary frequency drop.

[0097] ② Frequency modulation power continuous load reduction plan

[0098] Considering the decrease in aerodynamic power caused by the decrease in rotor speed, the frequency modulation power should be adjusted with the speed. Gradually decreases. Due to the constant restriction of the coefficients of the linear time-varying system transfer function, Variables cannot be directly substituted into transfer functions In order to simulate The associated primary FM power drops. This embodiment uses a first-order high-pass filter to simulate the specific FM power drop dynamics:

[0099]

[0100] Where, This method reduces the power derating at the end of frequency regulation and can effectively reduce the risk of secondary frequency drop.

[0101] (3) Wind turbine power characteristics during speed recovery

[0102] During the wind turbine speed recovery phase, the wind turbine no longer actively responds to grid frequency deviations, but instead becomes a source of power fluctuations, negatively impacting grid frequency stability. Power-speed control function It determines the power characteristics of the wind turbine during the speed recovery phase, and its design is crucial to balancing rotor kinetic energy recovery and grid frequency stability.

[0103] The power-speed control function trajectory corresponding to the existing speed recovery control method and the segmented speed recovery method proposed in this embodiment is as follows: Figure 3 As shown in FIG, the speed recovery process corresponds to the trajectory of the operating point B or C returning to the steady-state operating point A before the frequency modulation operation. A comparison between the existing speed recovery method and the segmented speed recovery method is shown in Table 1.

[0104] Table 1 Comparison of four speed recovery strategies

[0105]

[0106] Existing methods do not fully address the trade-off between speed recovery and secondary frequency drop suppression. This embodiment proposes a speed recovery performance evaluation method and a detailed design process for the segmented speed recovery method in the following section, "(II) Wind Turbine Unit Segmented Speed ​​Recovery Method and Evaluation Method."

[0107] (4) Power system frequency response characteristics

[0108] By integrating the synchronous generator frequency response model in Equations (3)-(4), the load frequency response model in Equation (5), and the wind turbine frequency response model in Equations (8) and (11), a system-level frequency response model of the power system is established.

[0109] Under a 10% load step disturbance, the dynamic frequency response of wind power penetration levels from 0% to 50% is simulated, as shown in Figure 4 Compared to synchronous generators, wind turbines have faster frequency response dynamics. Therefore, as wind power penetration increases, their effectiveness in suppressing the rate of change of frequency (RoCoF) and improving the lowest frequency point (frequency valley) during frequency regulation gradually improves. However, during the rotor speed recovery phase, increased wind power penetration leads to greater active power reduction, exacerbating the severity of secondary frequency dips in the grid.

[0110] (2) Wind turbine unit segmented speed recovery method and its evaluation method

[0111] During wind turbine speed recovery, secondary grid frequency drops pose a significant challenge to system frequency recovery. These drops can further increase grid frequency deviations, posing a serious threat to the safe and stable operation of the grid. During speed recovery, there is an inherent constraint between the magnitude of the secondary frequency drop and the speed recovery rate. This means that we cannot simply consider reducing the SFD amplitude or simply pursuing an increase in the recovery rate; instead, we need to conduct comprehensive optimization from a holistic perspective. Based on this, in this embodiment, a multi-dimensional speed recovery assessment method is constructed, and a targeted multi-stage speed recovery method is developed.

[0112] 1. SFD mechanism during wind turbine speed recovery

[0113] The switch from kinetic energy release to speed recovery in wind turbine operation mode will cause power load shedding, which will in turn trigger a secondary frequency drop in the power grid. When the wind turbine enters the speed recovery operation state, the system frequency response model changes to a synchronous generator-dominated mode. At this time, only the synchronous generator provides inertial response and primary frequency regulation power. At this time, the wind turbine power is derated. The resulting system frequency response is the secondary frequency drop of the power grid. Therefore, assuming that when the wind turbine exits the frequency regulation mode, the system frequency has reached a steady state, that is, The resulting system frequency response is a zero-state response. The system frequency response parameter definition and dynamic model for the rotor speed recovery phase are as follows: Figure 5 shown.

[0114] Figure 5 (a) shows the sequence of events after the disturbance: at time When load disturbance occurs, wind turbines participate in the active support of grid frequency; at time The wind turbine enters the speed recovery state and the grid frequency drops for the second time. The severity of the grid frequency drop can be measured by the maximum frequency change rate. and the maximum relative frequency deviation Quantify.

[0115] Figure 5 (b) shows the The following are the definitions of the relevant parameters: The power reduction of the wind turbine. is the system power imbalance, relative to The synchronous generator rotor speed deviation at time relative to The system frequency deviation at the moment.

[0116] Determined by the maximum system unbalanced power:

[0117]

[0118] according to Figure 5 The mathematical model in (b) can be used to derive the power derating of the wind turbine. Unbalanced power in the system The transfer function This transfer function can quantify the impact of wind power derating on system power imbalance, and thus calculate according to formula (12) .

[0119]

[0120] Similarly, according to Figure 5 The dynamic model shown in (b) can be deduced from arrive The transfer function This transfer function quantifies the impact of wind power load shedding on system frequency and can be used to calculate the maximum frequency deviation .

[0121]

[0122] Input interference in the pull domain (s) through the time domain power step signal In series with the first-order inertia link, the dynamic characteristics of power load reduction of the wind turbine during the rotor speed recovery stage are simulated. The expression is:

[0123]

[0124] Where, Indicates the inertia time constant of wind turbine power reduction. When it approaches zero, the disturbance is approximately a step disturbance; on the contrary, when When it is large, in the initial stage of disturbance ( ), Approximately behaves as a linear perturbation. The setting can simulate the power load reduction characteristics of methods 1 to 4 in Table 1 during the speed recovery stage.

[0125] Amplitude of wind turbine power reduction Set to 0.03 pu of the system load power (corresponding to 10% wind turbine load reduction at 30% wind power penetration). Under the input disturbance conditions defined by formula (15), the system power imbalance is calculated using formulas (13) and (14): and frequency deviation And obtain its time domain response result through Laplace inverse transform and ,like Figure 6 shown.

[0126] like Figure 6 As shown, and The transient characteristics of The differences show obvious differences. Figure 6 (a) It can be seen that when When the system power deviation decreases The maximum value of gradually approaches the disturbance power amplitude; on the contrary, when As it increases, the maximum power deviation gradually decreases. At the same time, according to formula (12), the maximum frequency change rate Also decreased. Figure 6 As shown in (b), The increase of the maximum frequency deviation Gradually decrease.

[0127] Therefore, in the same Under the condition of disturbance amplitude, moderately reducing the power load reduction rate has been proven to be able to effectively alleviate the secondary frequency drop of the power grid and improve the system frequency response.

[0128] 2. Speed ​​Recovery Performance Evaluation Framework

[0129] During speed recovery, the speed of recovery and the magnitude of the power disturbance to the power system exhibit a dynamic interplay. Higher load shedding can accelerate speed recovery but lead to more severe secondary frequency drops. Moderately reducing load shedding can mitigate secondary frequency drops but prolongs speed recovery time. This extended recovery time also exacerbates the grid's active power shortage, negatively impacting frequency recovery.

[0130] It can be seen that the evaluation of speed recovery performance is very critical. A comprehensive evaluation method can effectively guide the optimization design of the speed recovery control strategy. Therefore, this embodiment proposes a multi-dimensional speed recovery performance evaluation method containing five indicators based on the local and overall characteristics of the speed recovery process, such as Figure 7 As shown in the figure, different indicators correspond to different recovery stages.

[0131] Figure 7 middle, represents the initial wind turbine aerodynamic power, Indicates the maximum wind turbine aerodynamic power reduction, Indicates that the aerodynamic power has recovered to 90% moment, Indicates the time when the speed recovery is completed. The evaluation indicators are detailed below.

[0132] (1) Maximum power deviation (MPD): MPD index can represent the speed recovery period. , used to indicate the severity of the secondary frequency drop.

[0133] (2) Maximum frequency deviation (MFD): The MFD indicator describes the speed recovery period. , used to indicate the severity of the secondary frequency drop.

[0134] Power reduction occurs primarily during the aerodynamic power recovery phase, i.e., the initial speed recovery phase. Therefore, the MPD and MFD indicators are used to quantify the local characteristics of this phase.

[0135] (3) Aerodynamic Recovery Time (APRT): The APRT indicator describes the speed at which the wind turbine aerodynamic power recovers. The wind turbine aerodynamic power recovery is the result of power reduction and is the basis for wind turbine power recovery. The calculation formula for APRT is:

[0136]

[0137] This indicator is mainly reflected in the wind turbine power recovery phase, which is the middle stage of the speed recovery process. Therefore, the APRT indicator is used to quantify the local characteristics of this stage.

[0138] (4) Second-order power variation intensity (PTI-2): The PTI-2 indicator is the variance of the second-order difference of the power sequence during the speed recovery period, which is used to quantify the smoothness of the power variation of the wind turbine during the recovery process. A lower PTI-2 value indicates a smoother power variation, thereby reducing the disturbance to the grid frequency. The PTI-2 calculation formula is:

[0139]

[0140] Where, n represents the number of elements in the power sequence, is the second-order difference sequence of the power sequence, and the calculation formula is:

[0141]

[0142] Where, represents the first-order power difference sequence, and the calculation formula is:

[0143]

[0144] Where, Represents the power sequence.

[0145] (5) Transient energy dissipation loss (TEDL): The TEDL indicator is calculated by integrating the difference between the initial power and the actual power during the recovery process. This indicator comprehensively reflects the depth of power reduction and the dynamic process of aerodynamic power recovery, and quantifies the efficiency of the rotor speed recovery process. The calculation formula of TEDL is:

[0146]

[0147] Where, is the initial power.

[0148] PTI-2 and TEDL are indicators designed for the overall characteristics of the speed recovery process. They reflect the smoothness of power control and the power recovery efficiency, respectively, and quantify the performance of the speed recovery process at all stages.

[0149] 3. Design method of segmented speed recovery

[0150] Speed ​​recovery is achieved by controlling the power of the wind turbine. The segmented speed recovery method proposed in this embodiment is based on the following principles:

[0151] (1) According to the above conclusions, the balance between the severity of the secondary frequency drop and the aerodynamic power recovery rate can be adjusted by controlling the power reduction rate of the wind turbine in the initial stage of rotor speed recovery.

[0152] (2) According to the aerodynamic characteristics defined by equations (5) and (6), the sensitivity of aerodynamic power to rotor speed changes decreases when approaching the maximum power tracking operating state. Therefore, when the rotor speed recovers to the MPPT reference value, aerodynamic power recovery precedes speed recovery. When aerodynamic power is close to recovery, the active power output of the wind turbine can be restored first.

[0153] (3) In the final stage of speed recovery, when the wind turbine power is close to the MPPT state, the relatively small difference between the aerodynamic power and the electric power is used to smoothly complete the final stage of speed recovery.

[0154] (4) The third-order Bezier curve is used to ensure smooth transition of each stage during the speed recovery process and eliminate sudden power disturbances during stage conversion.

[0155] Based on the above principle, a power control curve for the segmented speed recovery method is designed. , its trajectory is as follows Figure 8 BKRMA shown.

[0156] In the figure, point A ( , ) represents the steady-state operating point, point B ( , ) represents the initial operating point of speed recovery, point H ( , ) corresponds to the working point when the wind turbine aerodynamic power recovers to 90%. Line segment BK corresponds to the first recovery stage (aerodynamic power recovery stage) and its slope is ( <0, indicating power derating), BK is on the straight line The Bezier curve KRM corresponds to the second recovery stage (wind turbine power recovery stage); the line segment MA corresponds to the third recovery stage (final speed recovery stage), and its slope is ( >0, indicating increased power), MA is located on the straight line superior.

[0157] The design process is as follows Figure 9 shown.

[0158] Initialization: Determine point A ( , ), determine point B ( , ), and use formulas (5)-(6) to calculate point H( , ).

[0159] Step 1: Determine the first stage power reduction slope , that is, the control function of the power load shedding intensity can be adjusted, and a straight line is established equation:

[0160]

[0161] Determine the power increase slope in the third stage , that is, the control function of the power increase rate is adjustable, and a straight line is established equation:

[0162]

[0163] Calculate straight line ( = ) and straight line and The intersection points I and J:

[0164]

[0165] Step 2: Design Bezier curve KRM. Design scaling parameters 、 to determine the endpoints of the Bezier curve.

[0166]

[0167] Point K ( , ) and dot M ( , ) can be calculated as follows:

[0168]

[0169] Parameter δ is the control parameter of Bezier curve, and the control point N( ) and O( ) is determined by the following formula:

[0170]

[0171] by x Is a parameter variable, the parametric equation of the third-order cubic Bezier curve defined by the control points K, N, O and M is:

[0172]

[0173] Step 3: Synthesize the power control function corresponding to the three-stage overall power control curve BKRMA This function can be stored in the memory of the real-time controller in the form of a data table, and the association of input and output data can be realized by a table lookup method, which can be used for the implementation of the real-time controller.

[0174] 4. Wind turbine coordinated control strategy with segmented speed recovery

[0175] like Figure 10 As shown in Figure 1, power control is the core of the wind turbine control strategy. In normal operation and frequency regulation, MPPT control provides active power reference. When the wind turbine power is less than the wind turbine aerodynamic power ( < ), the rotor kinetic energy release ends, and the power control logic switches to the segmented speed recovery control. When the wind turbine power is greater than the wind turbine aerodynamic power ( > ), the power control logic switches to MPPT to resume normal operation.

[0176] Example 1

[0177] To verify and compare the effectiveness of the proposed segmented speed recovery control for wind power frequency regulation and its multidimensional evaluation method, this example developed an operational scenario for connecting a wind farm to the power system. The dynamic operating waveforms of a single wind turbine during grid frequency regulation and speed recovery are detailed. Furthermore, based on the quantitative multidimensional evaluation method described in "(II) Wind Turbine Segmented Speed ​​Recovery Method and Evaluation Method," the proposed segmented speed recovery method was compared with three existing speed recovery methods under different wind power penetration conditions (10% and 30%).

[0178] Figure 11 and Table 2 show the grid system topology and parameters under this operation condition.

[0179] Table 2 Main parameters of the power system

[0180]

[0181] 1. Grid frequency drop operation

[0182] Import the recorded data of a certain actual power grid fault into the power grid frequency configuration of this embodiment. Figure 12 (a)-(k) show the detailed operating waveforms of a single doubly-fed induction generator (DFIG) using the staged speed recovery method.

[0183] Figure 12 Grid frequency in (a) It dropped to a minimum of 49.85 Hz at 14.2 seconds. Before the disturbance, the wind turbine maintained stable operation under rated conditions. Figure 12 The phase voltage in (b) stabilizes at 780 V. From 14.2 to 36.6 seconds, the wind turbine releases rotor kinetic energy for frequency regulation. From 36.3 to 109 seconds, speed recovery is performed using a staged speed recovery method, and normal operation is fully restored after 109 seconds.

[0184] During the kinetic energy release period (14.2-36.6 seconds), Figure 12 Stator current in (c) I s increased to 4.5 kA (increase of 23.8%), making Figure 12 Stator power in (f) From 4.2 MW to 5.2 MW. With the release of kinetic energy, Figure 12 The speed in (i) From 187 rad / s to 155 rad / s, the fan changes from super-synchronous operation to sub-synchronous operation. Figure 12 (d) Excitation current frequency changes while reducing the slip power transfer, resulting in Figure 12 (e) Grid-side converter current Reduce by 500 A, Figure 12 (g) Grid-side converter power A decrease of 0.9 MW. Figure 12 (h) Wind turbine output power increased to 5.8 MW (a 16% increase). At 36.6 seconds, and Figure 12 (h) The aerodynamic power of the wind turbine If they are equal, the control logic switches to segmented speed recovery control. Figure 12 Virtual power angle in (j) and Figure 12 Virtual excitation potential in (k) Determines the above power dynamic characteristics.

[0185] During the speed recovery phase (36.3-109 seconds), the wind turbine power Control is performed according to the preset reference value of the segmented speed recovery method:

[0186] Phase 1 (36.3-59 seconds): Wind turbine power The load is reduced at a rate of 0.017 MW / s, so that the speed is restored from 155 rad / s to 174 rad / s. The electromagnetic parameters at this stage ( 、 、 、 ) exhibits a dynamic pattern that operates in the opposite direction relative to the kinetic energy release, confirming the reversal of energy conversion during recovery.

[0187] The second stage (59-66.6 seconds): At 59 seconds, the aerodynamic power is shown in Figure (h) The power has recovered to 90% of the power drop during the kinetic energy release phase (recovered to 4.96 MW). It then quickly increased to 4.8 MW, reaching 96% of normal operating power.

[0188] The third stage (59-109 seconds): Use a smaller power unloading to gradually restore the speed to the final value.

[0189] During the entire speed recovery period, the wind turbine power Continuous stepless change.

[0190] 2. Wind power penetration rate 10% scenario

[0191] Figure 11 The power system shown consists of a wind farm and 20 5-MW wind turbines. The total system load of 950 MW is provided by the wind farm (rated power) of 100 MW and three SGs (856 MW, 71.3% of their total rated power of 1200 MW). At t = 15 seconds, the load increases by 50 MW (5.3% of the total load). The corresponding system frequency and power responses are shown in Figure 1. Figure 13 Figures (a)-(c) show four wind turbine speed recovery strategies—Method I (Met-I, MPPT-based SRS), Method II (Met-II, power-limited MPPT SRS), Method III (Met-III, smooth power transition SRS), and Method IV (Met-IV, segmented SRS of this embodiment)—are compared and validated under the same frequency regulation controller. Their dynamic responses are quantified in these figures.

[0192] Figure 11The power system shown consists of a wind farm consisting of 20 wind turbines, each with a capacity of 5 MW. The total system load is 950 MW, of which the wind farm operates at a rated capacity of 100 MW, and the three synchronous generators provide 856 MW of load (71.3% of the total rated capacity of 1200 MW of the synchronous units). At t = 15 seconds, the system experiences a sudden increase in load of 50 MW (approximately 5.3% of the total load). The system's frequency and power responses are shown in Figure 1. Figure 13 Among them, method 1 is the MPPT speed recovery method, method 2 is the power limiting MPPT speed recovery method, method 3 is the flexible power load reduction speed recovery method, and method 4 is the segmented speed recovery method proposed in this invention.

[0193] like Figure 13 As shown in Figure 2, the speed recovery starts at 43 seconds. Methods 1 and 2 use a step-by-step power reduction strategy, resulting in the wind farm output power A step-down occurs (e.g. Figure 13 (c)). The wind power shortage will be compensated by the synchronous generator through its speed regulator response (such as Figure 13 (b) Method 1 reduces the power step by 38.7 MW, which is 6.8 times the 5.7 MW reduction in Method 2, thus causing a greater grid disturbance. Accordingly, Method 1 causes a grid frequency drop of 0.08 Hz (e.g. Figure 13 (a) , while the grid frequency drop caused by method 2 is 0.02 Hz.

[0194] Compared to Methods 1 and 2, Methods 3 and 4 employ a continuous power reduction strategy, resulting in less grid disturbance. Continuous power reduction can effectively mitigate secondary dips in grid frequency, but speed recovery is slower. Compared to Method 3, Method 4's staged speed recovery strategy achieves faster wind power recovery by optimizing power control at each stage.

[0195] The four speed recovery methods were evaluated using the multi-dimensional speed recovery evaluation method containing five indicators proposed in "(II) Wind turbine unit segmented speed recovery method and its evaluation method". Figure 13 During the speed recovery process shown in the figure, the recovery process-related characteristic variables are calculated from five perspectives: power deviation, frequency deviation, wind turbine aerodynamic power, wind turbine power and energy dissipation loss, and are displayed in Figure 14 (a)-(e).

[0196] according to Figure 14(a)-(e) Characteristic variables are used to calculate the speed recovery performance indicators (MPD, MFD, APRT, PTI-2 and TEDL) of methods 1 to 4 and are displayed on the Figure 15 The indicators of the four methods are converted based on the indicators of method 4. Figure 15 As shown in the figure, the segmented speed recovery method proposed in the present invention exhibits better power smoothing capability, and achieves effective coordination between suppressing the secondary frequency drop (SFD) of the power grid and accelerating the recovery of aerodynamic power, meeting the preset multi-objective operation requirements.

[0197] 3. Scenario with a wind power penetration rate of 30%

[0198] In this scenario, the wind farm consists of 60 5 MW wind turbines (for a total installed capacity of 300 MW). The total system load is 950 MW, of which the wind farm provides 300 MW and the three synchronous generators provide 652 MW (54.3% of the total rated capacity of 1200 MW). At t = 15 seconds, the load increases by 50 MW (5.3% of the total load). The corresponding system frequency and power responses are as follows: Figure 16 (a)-(c) are shown. The rotor speed recovery performance indicators of methods 1 to 4 are as follows: Figure 17 shown.

[0199] Figure 16 Grid frequency in (a) 、 Figure 16 (b) Synchronous unit power and Figure 16 Wind power in (c) The dynamic characteristics of Figure 13 The corresponding waveforms in are very similar. Figure 17 The speed recovery performance index of methods 1 to 4 is also consistent with Figure 15 These results show that the proposed step-by-step speed recovery method also has excellent dynamic performance when the wind power penetration rate is 30%.

[0200] Comparative analysis under wind power penetration rates of 10% and 30% shows that the fast frequency response of wind turbines can increase the lowest frequency point after disturbance from 49.87Hz to 49.90Hz ( =+0.03Hz). The reduction of frequency deviation reduces the frequency regulation power, thereby extending the frequency regulation exit time from t=43 seconds to t=48.7 seconds under the kinetic energy limitation of the wind turbine ( = +5.7 seconds).

[0201] The comparative analysis of the 10% and 30% wind power penetration scenarios shows that the fast frequency response of the wind turbines increases the lowest frequency point after the disturbance from 49.87 Hz to 49.90 Hz ( = +0.03 Hz). The reduction in frequency deviation reduces the power required for frequency regulation, thereby extending the time to the end of kinetic energy release operation from t=43 seconds to t=48.7 seconds under the condition of the same kinetic energy reserve of the wind turbine ( = +5.7 seconds).

[0202] Furthermore, higher wind power penetration exacerbates the secondary frequency drop in the grid during the rotor speed recovery phase. Under Method 1, the minimum frequency drops from 49.85 Hz in the 10% penetration scenario to 49.71 Hz in the 30% penetration scenario. Therefore, the proposed segmented speed recovery strategy demonstrates significant effectiveness in ensuring safe grid operation during the speed recovery phase in high wind power penetration scenarios.

[0203] Example 2

[0204] This embodiment provides a wind turbine generator set, including a wind turbine generator set body and a control component, wherein the control component is configured to execute the steps of a segmented speed recovery control method for wind power frequency regulation and a multi-dimensional evaluation method thereof as described in the first embodiment.

[0205] Example 3

[0206] This embodiment provides a computer-readable storage medium having a computer program stored thereon. When the program is executed by a processor, the steps of the segmented speed recovery control and multi-dimensional evaluation method for wind power frequency regulation described in the first embodiment above are implemented.

[0207] Example 4

[0208] This embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the steps of the segmented speed recovery control and multi-dimensional evaluation method for wind power frequency regulation described in the first embodiment are implemented.

[0209] The steps involved in Examples 2 to 4 above correspond to those in Example 1. For detailed implementation, please refer to the relevant description of Example 1. The term "computer-readable storage medium" should be understood to mean a single medium or multiple media that includes one or more instruction sets; it should also be understood to include any medium that can store, encode, or carry an instruction set for execution by a processor and cause the processor to perform any method of the present invention.

[0210] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A segmented speed recovery control and multi-dimensional evaluation method for wind power frequency regulation, characterized in that: include: A multi-dimensional speed recovery evaluation index system is constructed based on the power grid system frequency response model, wind turbine aerodynamic model and wind turbine power response model under the GFM control strategy. A segmented speed recovery control strategy is formulated, and the speed recovery process is divided into three stages: aerodynamic power recovery, wind turbine power recovery, and final speed recovery. The power control function of each stage is designed, and the evaluation index system is used to optimize each recovery stage in real time; wherein, the power control function of each stage specifically includes: in the aerodynamic power recovery stage, a control function with adjustable power load reduction intensity is set to suppress the secondary drop of grid frequency; in the final speed recovery stage, a control function with adjustable power increase rate is set to achieve flexible approximation of MPPT operating conditions; in the wind turbine power recovery stage, the optical connection between the first stage and the third stage is realized by using Bezier curve. Smooth transition; the use of the evaluation index system to optimize each recovery stage in real time, specifically: according to the power grid system frequency response model, based on the maximum power deviation and maximum frequency deviation indicators of the speed recovery process, used to quantitatively characterize the impact of the speed recovery process on the secondary drop of the power grid frequency; according to the wind turbine aerodynamic model, based on the aerodynamic recovery time indicator, used to quantitatively characterize the aerodynamic power recovery speed of the wind turbine; according to the wind turbine power data of the wind turbine power response model during the speed recovery process, based on the two indicators of second-order power change intensity and transient energy dissipation loss, used to quantitatively characterize the power fluctuation and frequency regulation operation efficiency of the overall speed recovery process; According to the characteristics of the grid-type wind turbine with rotor kinetic energy release during frequency regulation operation, a segmented speed recovery strategy is formulated to embed the control strategy of the traditional grid-type wind turbine. Specifically, when the wind turbine power is less than the aerodynamic power, the segmented speed recovery strategy is triggered for control; when the wind turbine power is greater than the aerodynamic power, the maximum power point tracking state control is restored to achieve dynamic switching between frequency regulation and normal operation mode.

2. The segmented speed recovery control and multi-dimensional evaluation method for wind power frequency modulation according to claim 1, characterized in that: According to the power grid system frequency response model, the wind turbine aerodynamic model and the wind turbine power response model under the GFM control strategy, a multi-dimensional speed recovery evaluation index system is constructed, specifically: According to the differences in frequency response characteristics among the power grid system frequency response model, wind turbine aerodynamic model and wind turbine power response model under the GFM control strategy, the maximum power deviation, maximum frequency deviation, aerodynamic recovery time, second-order power variation intensity and transient energy dissipation loss are extracted to construct a multi-dimensional speed recovery evaluation index system.

3. The segmented speed recovery control and multi-dimensional evaluation method for wind power frequency modulation according to claim 2, characterized in that: The aerodynamic recovery time is the difference between the time required for the aerodynamic power to recover to 90% and the recovery start time; The second-order power variation intensity is obtained by calculating the variance of the second-order difference of the power sequence during the rotor speed recovery period; The transient energy dissipation loss is obtained by integrating the difference between the initial power and the actual power.

4. The segmented speed recovery control and multi-dimensional evaluation method for wind power frequency modulation according to claim 2, characterized in that: The power control curve of the segmented speed recovery strategy is initialized to determine the steady-state operating point, the initial operating point, and the aerodynamic power recovery point. A linear equation is established by combining the power derating slope and the incremental slope. The linear equation is then generated by scaling parameters and Bezier curve control points and stored in a lookup table for real-time control.

5. A wind turbine generator system, characterized in that: The invention comprises a wind turbine body and a control component, wherein the control component is used to execute the steps of a segmented speed recovery control and multi-dimensional evaluation method for wind power frequency regulation as described in any one of claims 1 to 4.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of a segmented speed recovery control method for wind power frequency regulation and a multi-dimensional evaluation method thereof are implemented as described in any one of claims 1 to 4.

7. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the steps of the segmented speed recovery control and multi-dimensional evaluation method for wind power frequency regulation according to any one of claims 1 to 4 are implemented.

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