A wind turbine independent variable pitch control method and system

Abstract

The application belongs to the technical field of wind power generation, and particularly relates to a wind turbine independent variable pitch control method and system, comprising the following steps: 1) obtaining a basic advance pitch angle β output by an advance pitch controller and a corresponding compensation pitch angle provided for at least one blade; taking the sum of the basic advance pitch angle and the compensation pitch angle as a final advance pitch angle of the blade; wherein the compensation pitch angle is obtained according to the basic advance pitch angle, a maximum allowable compensation angle fluctuation amplitude, a compensation coefficient K, a current azimuth angle of the blade and an azimuth compensation angle; the azimuth compensation angle is used to make the blade azimuth angle close to 90°; the maximum allowable compensation angle fluctuation amplitude is determined according to the basic advance pitch angle β; the compensation coefficient K is greater than 0; 2) respectively independently controlling the pitch of each corresponding blade based on the final advance pitch angle corresponding to each blade. Thus, the application solves the problems of poor effect of reducing the blade root load and loss of power generation in the prior art.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of wind power generation, and particularly relates to a wind turbine independent variable pitch control method and system. BACKGROUND

[0002] The control mode of the wind turbine for the pitch angle is generally to take the rated rotating speed as the target of the variable pitch control. When the rotating speed of the generator is lower than the rated rotating speed, at least one controller outputs a variable for reducing the pitch angle. When the rotating speed of the generator is higher than the rated rotating speed, at least one controller outputs a variable for increasing the pitch angle. For convenience of description, the variable pitch controller is referred to as the main controller.

[0003] With the increase of the single machine capacity of the wind turbine and the development of the low wind speed wind turbine, the length of the blade is also increasing, which leads to the rapid increase of the load of the wind turbine blade root, and becomes the difficulty of the whole machine design and the key factor of restricting the cost of the whole machine.

[0004] Since the limit load often appears near the rated wind speed, the advance variable pitch strategy is a common method for load reduction in the prior art. The advance variable pitch controller outputs the variable pitch control instruction and controls the advance variable pitch of the blade according to one or several of the wind speed, the rotating speed of the generator, the power or other variables before the main controller controls the variable pitch of the blade. However, although the advance variable pitch controller controls the advance variable pitch, the power generation near the rated wind speed is also lost.

[0005] In the prior art, another common method for load reduction is the independent variable pitch algorithm. The independent variable pitch algorithm is generally applied to the variable pitch main controller, needs to collect the blade root load as the feedback control signal, or controls according to the wind shear, but these independent variable pitch algorithms either greatly increase the cost of the wind turbine or the actual load reduction effect is not as expected.

[0006] In summary, in order to reduce the load of the blade root of the wind turbine, the power generation near the rated wind speed is lost, the cost of the wind turbine is increased, or the actual load reduction effect is poor, and there is no ideal solution. SUMMARY

[0007] The present application aims to provide a wind turbine independent variable pitch control method and system to solve the problems of poor load reduction effect and loss of power generation in the prior art.

[0008] To solve the above technical problems, the technical solutions provided by the present application and the beneficial effects corresponding to the technical solutions are as follows:

[0009] The wind turbine independent variable pitch control method of the present application comprises the following steps:

[0010] 1) obtaining a basic advance pitch angle β outputted by an advance pitch controller and a corresponding compensation pitch angle provided for at least one blade ; summing the basic advance pitch angle β and the compensation pitch angle as a final advance pitch angle γ of the blade;

[0011] wherein the compensation pitch angle is obtained according to the basic advance pitch angle β, a maximum allowable compensation angle fluctuation amplitude Δ, a compensation coefficient K, a current azimuth angle of the blade and an azimuth compensation angle; the azimuth compensation angle is used to make the azimuth angle of the blade close to 90°; the maximum allowable compensation angle fluctuation amplitude Δ is determined according to the basic advance pitch angle β; the compensation coefficient K is greater than 0;

[0012] 2) independently controlling each corresponding blade pitch based on the corresponding final advance pitch angle γ of each blade.

[0013] The beneficial effects of the above technical solution are: the final advance pitch angle γ of the blade of the present application adds the compensation pitch angle on the basis of the basic advance pitch angle, and each blade pitch is independently controlled based on the compensated advance pitch angle γ. The compensation pitch angle is obtained according to the basic advance pitch angle β, the maximum allowable compensation angle fluctuation amplitude Δ, the compensation coefficient K, the current azimuth angle of the blade and the azimuth compensation angle. The present application uses an independent pitch algorithm in the advance pitch strategy to supplement the advance pitch angle for each blade. The supplemented advance pitch angle is maximum when the blade reaches the azimuth angle (90°+θ) to reduce the load, and is minimum when the blade reaches the azimuth angle (270°+θ) to improve the power generation. The present application also does not need to add other acquisition devices, and the cost is low. Therefore, the present application solves the problems of poor load reduction effect and power loss in the prior art.

[0014] Further, the calculation formula of the compensation pitch angle is as follows:

[0015] when β < Δ,

[0016] when β ≥ Δ,

[0017] wherein K is a coefficient, θ is an azimuth compensation angle, and δ is a current azimuth angle of the blade.

[0018] Further, in order to improve the load reduction effect, the value range of K is [0, 1].

[0019] Further, the value range of the azimuth compensation angle is [-15, 30].

[0020] Further, step 2) comprises:

[0021] ​If the pitch angle of the blade is determined by the pitch angle α output by the main controller, and the pitch angle α is greater than the final advance pitch angle γ, the pitch angle of the blade is determined by the final advance pitch angle γ.

[0022] Further, in order to improve the load reduction effect and increase the power generation, a corresponding compensation pitch angle is provided for each of the three blades in step 1) to obtain three final advance pitch angles γ1, γ2 and γ3 corresponding to the three blades respectively; and in step 2), the corresponding blades are independently controlled based on the final advance pitch angles corresponding to the three blades respectively.

[0023] In order to solve the above problems, the application further provides a wind turbine independent pitch control system, which comprises a processor for executing program commands to realize the wind turbine independent pitch control method of the application. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a flow chart of the wind turbine independent pitch control method of the application;

[0025] Figure 2 is an azimuth angle diagram of the blades in the wind turbine in the method embodiment of the application;

[0026] Figure 3 is a diagram showing the pitch angle changes of the three blades in the method embodiment of the application;

[0027] Figure 4 is a diagram showing the comparison of the blade root loads obtained by using the application and using the prior art in the method embodiment of the application. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the application more clear, the application will be further described in detail below with reference to the drawings and embodiments.

[0029] Method embodiment:

[0030] The wind turbine independent pitch control method embodiment of the application,

[0031] Based on the analysis of the gravity moment component of the blade root load and the summary of the operation rules, the application provides an open-loop control wind turbine independent pitch algorithm based on the advance pitch control strategy, which is used to reduce the blade root load and improve the power generation.

[0032] In order to achieve the above purpose, the application provides a compensation pitch angle for each blade on the basis of the advance pitch angle β output by the advance pitch controller Wherein, the basic advance pitch angle β is obtained according to prior art, such as according to wind speed, generator speed and power calculation.

[0033] The specific steps include as follows, such as Figure 1

[0034] The first step: obtaining the determined compensation pitch angle and the final advance pitch angle γ.

[0035] 1) The compensation pitch angle is expressed by formula as Wherein, K is a coefficient (also called compensation coefficient), the coefficient K is used to provide power for reducing the pitch angle when controlling the blade pitch of the final advance pitch angle γ in the software algorithm of the second step, the value range of k is [0, 1], and δ is the current azimuth angle of the blade. The azimuth angle of the blade is the angle between the position of the blade in the vertical direction of the blade tip and the upward direction, that is, when the blade tip of a blade points upward, the azimuth angle of the blade is 0°; when the blade tip points upward again after rotating one circle, the azimuth angle of the blade is 360°. That is to say, the azimuth angle of the blade is a continuously and periodically changing angle value between 0° and 360° along with the rotation of the blade. As shown in Figure 2 , the azimuth angle of the blade 1 is 0°, and the azimuth angle of the blade 2 is 120°. Starting from the vertical direction of the blade tip, the azimuth angle δ gradually increases along the rotation direction, δ ∈ [0°, 360°), and θ is the azimuth compensation angle, -15°≤ θ ≤ 30°, the azimuth compensation angle is used to make the azimuth angle of the blade close to 90°.

[0036] The final advance pitch angle γ of each blade is determined by the basic advance pitch angle β and the compensation pitch angle , which is expressed by formula as:

[0037]

[0038] γ = β + β (K + sin (δ - θ))

[0039] Wherein, in the embodiment, the three blades are independently controlled, and since the azimuth angles are different, the final advance pitch angle γ of each blade is also different.

[0040] 2) In order to better realize the load reduction effect, when the basic advance pitch angle β reaches or exceeds the maximum allowable compensation angle fluctuation amplitude Δ, the pitch angle compensation formula is replaced by:

[0041]

[0042] ​The maximum allowable compensation angle fluctuation amplitude Δ is the maximum amplitude of sine fluctuation, which is determined according to the basic advance pitch angle β, and the greater the basic advance pitch angle β, the greater the maximum allowable compensation angle fluctuation amplitude Δ.

[0043] The formula of the final advance pitch angle γ becomes:

[0044] When β < Δ, γ = β + β (K + sin (δ - θ))

[0045] When β ≥ Δ, γ = β + Δ (K + sin (δ - θ))

[0046] Second step: the main controller adopts unified pitch control of three blades, and the output pitch angle α is adjusted on the basis of the final advance pitch angle γ.

[0047] For each blade, when the pitch angle α output by the main controller is greater than the final advance pitch angle γ of the blade, the pitch of the blade is controlled by the pitch angle α of the main controller. When the pitch angle α output by the main controller is less than the final advance pitch angle γ of the blade, the pitch of the blade is controlled by the final advance pitch angle γ. That is, the pitch angle α of the blade pitch is:

[0048] When α > γ, α = α

[0049] When α < γ, α = γ.

[0050] The content of the application is simulated and tested, and the relevant parameters K = 1, δ = 0°, and Δ = 4° in the simulation test, and the pitch angle of each blade is as shown in Figure 3 The horizontal axis represents time Time, and the vertical axis represents angle deg; Blade 1 pitch angle is the pitch angle of blade 1; Blade 2 pitch angle is the pitch angle of blade 2; Blade 3 pitch angle is the pitch angle of blade 3. During the period of control of the final advance pitch angle γ of the blade pitch, the three blades independently pitch, and the phases are 120° apart. With the increase of the pitch angle α of the main controller, the pitch of each blade starts to be controlled by α during α2γ. With the decrease of the pitch angle α of the main controller, the pitch of each blade starts to be controlled by γ during γ > α.

[0051] The simulated blade root simulation load M xy As shown in Figure 4 The curve with "△" is the blade root load before the implementation of the embodiment, and the curve without "△" is the blade root load after the implementation of the embodiment. The load is significantly reduced after the implementation of the embodiment.

[0052] The application is to reduce load and improve power generation, and an independent pitch algorithm is used in the advance pitch strategy to individually supplement an advance pitch angle for each blade, the supplemented advance pitch angle is maximum when the blade reaches an azimuth angle (90°+θ) to reduce load, and the supplemented advance pitch angle is minimum when the blade reaches an azimuth angle (270°+θ) to improve power generation.

[0053] System embodiments:

[0054] An embodiment of the independent pitch control system of the wind turbine generator set of the application is an advance pitch controller or other controller, the advance pitch controller or other controller calculates an advance pitch angle γ, and then transmits the advance pitch angle γ to a main controller, and the main controller adjusts an output pitch angle α according to the advance pitch angle γ.

[0055] The system includes a memory, a processor and an internal bus, the processor, the memory and the internal bus complete mutual communication and data interaction. The memory includes at least one software function module stored in the memory, the processor executes various function applications and data processing by running the software program and the module stored in the memory, and realizes the independent pitch control method of the wind turbine generator set introduced in the method embodiments of the application.

[0056] The processor can be a microprocessor MCU, a programmable logic device FPGA, a programmable logic controller PLC and the like processing device.

[0057] The memory can be various memories for storing information by using electric energy, such as RAM, ROM and the like; and can also be various memories for storing information by using magnetic energy, such as a hard disk, a floppy disk, a magnetic tape, a magnetic core memory, a bubble memory, a U disk and the like.

Claims

1. A wind turbine generator system independent variable pitch control method, characterized by: The method comprises the following steps: 1) obtaining a base pitch advance angle βout from an advance pitch controller output and a corresponding compensation pitch angle βcomp provided for at least one blade summing the base pitch advance angle βout and the compensation pitch angle βcomp as a final pitch advance angle γ for the blade ​ Wherein, the compensation pitch angle The azimuth compensation angle is obtained according to the basic advance pitch angle β, the maximum allowable compensation angle fluctuation amplitude Δ, the compensation coefficient K, the current azimuth angle of the blade, and the azimuth compensation angle. The azimuth compensation angle is used to make the azimuth angle of the blade close to 90°. The maximum allowable compensation angle fluctuation amplitude Δ is determined according to the basic advance pitch angle β. The compensation coefficient K is greater than 0. 2) independently controlling the pitch of each blade based on the final advanced pitch angle γ corresponding to each blade; Compensating pitch angle The formula for calculating the compensation pitch angle is as follows: β < Δ, β ≥ Δ, Wherein, K is a coefficient, θ is an azimuth compensation angle, and δ is the current azimuth angle of the blade.

2. The wind turbine generator system independent pitch control method according to claim 1, characterized by: The value range of K is [0, 1].

3. The wind turbine generator system independent pitch control method according to claim 1, characterized by: The value range of the azimuth compensation angle is [-15, 30].

4. The wind turbine generator system independent pitch control method according to claim 1, characterized by: In step 2), the pitch angle of the blade is determined by the pitch angle α output by the main controller if the pitch angle α output by the main controller is greater than the final advanced pitch angle γ, and the pitch angle of the blade is determined by the final advanced pitch angle γ if the pitch angle α output by the main controller is less than the final advanced pitch angle γ. In step 1), one corresponding compensation pitch angle is provided for each of the three blades, and the final advanced pitch angles γ1, γ2 and γ3 corresponding to the three blades are obtained; in step 2), the pitch of each corresponding blade is independently controlled based on the final advanced pitch angle corresponding to each blade.

5. The wind turbine generator system independent pitch control method according to any one of claims 1 to 4, characterized by: The system comprises a processor configured to execute program commands to implement the wind turbine independent pitch control method according to any one of claims 1 to 5.

6. A wind turbine generator system independent pitch control system characterized by: ​

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