Improved optimal torque control method for improving dynamic response performance of wind turbine

Abstract

The application discloses an improved optimal torque method for improving dynamic response performance of a wind turbine, and belongs to the technical field of maximum power point tracking control strategies of wind turbines. The improved optimal torque method for improving dynamic response performance of a wind turbine comprises the following steps: S1, setting a given rotational speed deviation threshold value ε; S2, obtaining a wind speed v of a windward surface of the wind turbine at a current moment k k and an actual rotational speed of a wind wheel ω r,k , and calculating a theoretical optimal rotational speed ω opt,k of the wind wheel; the improved optimal torque method for improving dynamic response performance of a wind turbine can switch between constant power control and optimal rotational speed method MPPT control by judging the deviation between the theoretical optimal rotational speed and the actual rotational speed of the wind turbine, thereby obtaining better acceleration and deceleration response performance and rotational speed tracking effect than a traditional optimal torque method, and effectively improving the wind energy capturing efficiency of the wind turbine.

Description

Technical Field

[0001] This invention relates to the field of maximum power point tracking control strategy technology for wind turbines, and more specifically, to an improved optimal torque method for enhancing the dynamic response performance of wind turbines. Background Technology

[0002] In recent years, with the large-scale development of clean energy, wind power generation technology has received increasing attention. Compared with traditional fixed-speed wind turbines, variable-speed wind turbines have higher power generation efficiency and lower structural loads, and are therefore gradually becoming the mainstream. To enable wind turbines to efficiently capture wind energy, maximum power point tracking (MPPT) control is generally used, aiming to control the rotor speed to track the optimal speed determined by the real-time wind speed. There are many methods for implementing MPPT control in wind turbines. Among them, the optimal torque method, by setting a cubic relationship between a reference power command and the rotor speed, allows the wind turbine to automatically approach the optimal speed. This method has a relatively small impact on the operating load of the wind turbine and has a simple and easy-to-implement control structure, and has therefore been widely used in engineering.

[0003] However, the optimal torque method, which adjusts according to the rotor speed, suffers from a slow response. Specifically, the dynamic process of the wind turbine controlled by this method approaching the optimal speed takes a considerable amount of time, and this problem becomes increasingly prominent as the rotor's moment of inertia increases. Furthermore, this method itself cannot achieve a faster response speed through parameter adjustments, resulting in a lower wind energy capture efficiency for the wind turbine.

[0004] To address this, related technical research has improved the optimal torque method from two aspects: reducing torque gain and shrinking the tracking interval. Specifically, the torque gain reduction method improves the wind turbine's response performance by decreasing the torque gain coefficient; the tracking interval shrinking method improves overall capture efficiency by abandoning the tracking of the optimal speed at low wind speeds. However, these methods still improve the optimal torque method by modifying the wind turbine's maximum power tracking curve from a steady-state perspective. The torque gain reduction method only shows good acceleration performance in specific wind speed scenarios, and the tracking interval shrinking method does not improve the wind turbine's response speed. Therefore, it is necessary to improve the optimal torque method from a dynamic perspective to give it good acceleration and deceleration response performance, while inheriting the advantages of the optimal torque method and further improving the wind turbine's wind energy capture efficiency. Summary of the Invention

[0005] 1. Technical problems to be solved

[0006] To address the problems existing in the prior art, the purpose of this invention is to provide an improved optimal torque method to enhance the dynamic response performance of wind turbines. This method can select different control modes based on the absolute value deviation between the theoretical optimal speed and the actual speed of the wind turbine. When the deviation is large, it maintains a constant power command to accelerate and track the theoretical optimal speed; when the deviation is small, it operates with the optimal torque method to tend towards the theoretical optimal speed, thereby achieving good speed tracking effect and effectively improving wind energy capture efficiency.

[0007] 2. Technical Solution

[0008] To solve the above problems, the present invention adopts the following technical solution.

[0009] An improved optimal torque method for enhancing the dynamic response performance of wind turbines, the torque method comprising the following steps:

[0010] S1: Set threshold ε for given speed deviation;

[0011] S2: Obtain the wind speed v at the windward side of wind turbine k at the current moment. k With windmill ω r,k Calculate the theoretical optimal speed ω of the wind turbine based on its actual rotational speed. opt,k ;

[0012] S3: When |ω| is satisfied r,k -ω opt,k If |<ε, or k=0, then the wind turbine sets the reference power command using the optimal torque method, or satisfies |ω r,k -ω opt,k If |≥ε and k>0, then the reference power command of the wind turbine remains unchanged at the holding time.

[0013] S4: Register the reference power command at the current time k and send this reference power command to the converter for implementation.

[0014] Furthermore, the speed deviation setting threshold in step S1 is initialized to a coefficient greater than 0.

[0015] Furthermore, the formula for calculating the theoretical optimal rotational speed in step S2 is as follows:

[0016]

[0017] Where, λ opt The optimal tip speed ratio is determined by the aerodynamic characteristics of the wind turbine and is obtained by measuring and fitting the wind energy capture coefficient curve; R is the radius of the wind turbine.

[0018] Furthermore, in step S3, the wind turbine sets the reference power command P at the current time k using the optimal torque method. ref,k ,Right now:

[0019]

[0020] Among them, K opt =0.5ρπR 5 C Pmax / λ opt Approximately a constant, C Pmax The maximum wind energy capture factor (ω) is obtained by fitting a wind energy capture factor curve. r.bgn This is the starting power generation speed.

[0021] Furthermore, in step S3, the wind turbine maintains the reference power command at time k-1 unchanged, that is:

[0022] P ref,k =P ref,k-1

[0023] Among them, P ref,k-1 The wind turbine reference power command is stored at time k-1.

[0024] Furthermore, the purpose of registering the reference power command at the current time k in step S4 is to determine whether to use it as the reference power command for the wind turbine in step S3 or not when time k+1.

[0025] 3. Beneficial effects

[0026] Compared with the prior art, the advantages of this invention are:

[0027] (1) The improved optimal torque method of the present invention improves the dynamic response performance of wind turbines by judging the deviation between the theoretical optimal speed and the actual speed of the wind turbine, and switches between constant power control and optimal speed method MPPT control, thereby obtaining better acceleration and deceleration response performance and speed tracking effect than the traditional optimal torque method, and effectively improving the wind energy capture efficiency of the wind turbine. Attached Figure Description

[0028] Appendix Figure 1 The flowchart of the improved optimal torque method for enhancing the dynamic response performance of wind turbines according to the present invention is shown below;

[0029] Appendix Figure 2 This is a control block diagram of the improved optimal torque method for enhancing the dynamic response performance of wind turbines according to the present invention.

[0030] Appendix Figure 3 A comparison chart showing the theoretical optimal speed obtained from simulation, the actual speed of the wind turbine obtained by the traditional optimal torque method, and the actual speed curve of the wind turbine obtained by the improved optimal torque method proposed in this invention;

[0031] Appendix Figure 4A comparison diagram of the low-speed shaft torque curves obtained from simulation using the traditional optimal torque method and the improved optimal torque method proposed in this invention.

[0032] Appendix Figure 5 The output power curves of the traditional optimal torque method and the improved optimal torque method proposed in this invention are compared using simulation. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0034] Example 1:

[0035] Please see Figure 1-2 An improved optimal torque method for enhancing the dynamic response performance of wind turbines is proposed, specifically: given a set threshold ε for the speed deviation, the set threshold ε is initialized to a coefficient greater than 0, and the wind speed v at the current time k is obtained. k With the actual rotational speed ω of the wind turbine r,k Calculate the theoretical optimal rotational speed ω of the wind turbine. opt,k The theoretical optimal speed calculation formula is:

[0036]

[0037] Where, λ opt The optimal tip speed ratio is determined by the aerodynamic characteristics of the wind turbine and is obtained by measuring and fitting the wind energy capture coefficient curve; R is the radius of the wind turbine.

[0038] Determine ω r,k -ω opt,k If the condition <ε, or k=0, is met, then the wind turbine sets the reference power command P using the optimal torque method. ref,k ,Right now:

[0039]

[0040] Among them, K opt =0.5ρπR 5 C Pmax / λ opt Approximately a constant, C Pmax The maximum wind energy capture factor (ω) is obtained by fitting a wind energy capture factor curve. r.bgn This is the starting power generation speed.

[0041] If this condition is not met, the wind turbine will maintain the reference power command at time k-1, i.e.:

[0042] P ref,k-1 The wind turbine reference power command registered at time k-1;

[0043] It stores the reference power command at the current time k. When time k+1, it is used to determine whether the command is used as the reference power command for the wind turbine or not.

[0044] Example 2:

[0045] The control effect was simulated using FAST (Fatigue, Aerodynamics, Structures, and Turbulence), an open-source professional wind turbine simulation software provided by the National Renewable Energy Laboratory (NREL) of the U.S. Department of Energy. The wind turbine model used was the 600kW CART3 experimental model developed by NREL, and the specific parameters are shown in Table 1 below.

[0046] Table 1 Main Parameters of NREL 600kW CART3 Wind Turbine

[0047] Rated power 600KW Rated wind turbine speed 37.1rpm Cut-in / Rated wind speed 3 / 13.5m / s Wheel height 36.6m wind turbine radius 20m Moment of inertia <![CDATA[5.492×10 5 kgm 2 ]]> Optimal tip speed ratio 5.8 Maximum wind energy utilization coefficient 0.46

[0048] The method proposed in this invention is compared with the traditional optimal torque method, demonstrating that the method has good speed tracking performance under turbulent wind conditions and can effectively improve wind energy capture efficiency.

[0049] A 600-second turbulent wind speed with an average wind speed of 5 m / s and turbulence intensity of level A was generated using Bladed software. Simulations were then performed in FAST using two different control methods, and the results are as follows: Figure 3 , Figure 4 , Figure 5 As shown. Figure 3 By comparing the actual wind turbine speed curves of the theoretical optimal speed, the traditional optimal torque method, and the improved optimal torque method proposed in this invention, it can be clearly concluded that the improved optimal torque method proposed in this invention has a better speed tracking effect, especially during the process of a significant increase in wind speed around 100s. Figure 4 A comparison of the low-speed shaft torque curves of the traditional optimal torque method and the improved optimal torque method proposed in this invention clearly shows that the improved optimal torque method proposed in this invention has a smaller impact on shaft load compared to the traditional optimal torque method. Figure 5 The output power curves of the traditional optimal torque method and the improved optimal torque method proposed in this invention clearly show that the wind turbine output power command of the improved optimal torque method proposed in this invention is faster and more flexible, thereby improving the dynamic response performance of the wind turbine.

[0050] In this simulation experiment, the wind energy capture efficiency of the traditional optimal torque method was 85.74%, while that of the method proposed in this invention was 87.91%. This demonstrates that the improved optimal torque method proposed in this invention, which enhances the dynamic response performance of wind turbines, has good adaptability to turbulent wind conditions and effectively improves wind energy capture efficiency.

[0051] The above description is merely a preferred embodiment of the present invention; however, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and its improved concepts, should be covered within the scope of protection of the present invention.

Claims

1. An improved optimal torque method for enhancing the dynamic response performance of wind turbines, characterized in that, The torque method includes the following steps: S1: Set threshold for given speed deviation ; S2: Obtain the wind speed at the windward side of wind turbine k at the current moment. With the actual rotational speed of the wind turbine Calculate the theoretical optimal rotational speed of the wind turbine. The theoretical optimal speed is calculated using the following formula: ； in, The optimal tip speed ratio is determined by the aerodynamic characteristics of the wind turbine and is obtained by measuring and fitting the wind energy capture coefficient curve; R is the radius of the wind turbine. S3: When | - |< If k=0, then the wind turbine sets the reference power command using the optimal torque method, when | - |≥ If k > 0, then the wind turbine maintains the reference power command at time k-1 unchanged, where the wind turbine sets the reference power command using the optimal torque method. Right now: ； in, =0.5ρπ , The maximum wind energy capture factor is obtained by fitting the wind energy capture factor curve. This is the starting power generation speed; S4: Register the reference power command at the current time k and send this reference power command to the converter for implementation.

2. The improved optimal torque method for enhancing the dynamic response performance of wind turbines according to claim 1, characterized in that: In step S1, the speed deviation setting threshold is initialized to a number greater than 0.

3. The improved optimal torque method for enhancing the dynamic response performance of wind turbines according to claim 1, characterized in that: In step S3, the wind turbine maintains the reference power command at time k-1 unchanged, that is: ； in, The wind turbine reference power command is stored at time k-1.

4. The improved optimal torque method for enhancing the dynamic response performance of wind turbines according to claim 1, characterized in that: The purpose of registering the reference power command at the current time k in step S4 is to determine whether to use it as the reference power command for the wind turbine in step S3 or not when time k+1.

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