Wind turbine blade stall monitoring method and system

Abstract

The present invention discloses a method and system for monitoring blade stall of a wind turbine generator set. The method includes the following steps: S1, obtaining the operating data of the wind turbine generator set and the real-time aerodynamic twist angle of the blade; S2, obtaining the real-time operating angle of attack of the blade cross section based on the operating data of the wind turbine generator set and the real-time aerodynamic twist angle of the blade; S3, comparing the real-time operating angle of attack with a preset critical angle of attack; when the real-time operating angle of attack is greater than the preset critical angle of attack, it is determined that the blade of the wind turbine generator set is stalled. The present invention calculates the real-time operating angle of attack of the blade through the real-time aerodynamic twist angle of the blade, and then determines whether the blade is in a stall state based on the comparison between the real-time operating angle of attack and the preset critical angle of attack, thereby ensuring the safe operation of the unit; compared with monitoring wind turbine stall through cross-sectional aerodynamic parameters, power curve, and vibration frequency, this method is more accurate and reliable.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of wind power generation, and in particular to a method and system for monitoring blade stall of a wind turbine generator set. Background Art

[0002] With the development of wind farms in mountainous areas and high-altitude areas, the air density in high-altitude areas is relatively thin, and wind turbines are prone to stall under low air density. After stalling, the power of the wind turbine cannot meet the design requirements, and the blades are accompanied by stall flutter, causing blade damage.

[0003] Current technologies often determine the critical stall angle of attack based on aerodynamic parameters of a cross-section; or obtain wind turbine operating status data and guaranteed power curve data to perform a preliminary stall boundary analysis based on edge data; or determine whether a wind turbine is in a stall state by collecting vibration data and vibration frequency, and then adjust the pitch angle to ensure safe operation of the wind turbine. However, stall monitoring achieved by these technologies is inaccurate and unreliable. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: in response to the technical problems existing in the prior art, the present invention provides a method and system for monitoring the stall of blades of a wind turbine generator set that can monitor the stall accurately and reliably.

[0005] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0006] A method for monitoring blade stall of a wind turbine generator set comprises the following steps:

[0007] S1. Obtaining the operating data of the wind turbine and the real-time aerodynamic twist angle of the blades;

[0008] S2. Obtaining the real-time operating angle of attack of the blade cross section based on the operating data of the wind turbine generator set and the real-time aerodynamic twist angle of the blade;

[0009] S3. Compare the real-time operating angle of attack with a preset critical angle of attack; when the real-time operating angle of attack is greater than the preset critical angle of attack, determine that the wind turbine blades are stalled.

[0010] Preferably, in step S1, the corresponding operating data includes one or more of generator speed, generator torque, pitch angle, pitch rate, generated power, air density, blade operating parameters and axial induction factor.

[0011] Preferably, in step S1 , the real-time aerodynamic twist angle of the blade is obtained by acquiring the torque deformation of the blade in a real-time state.

[0012] Preferably, the torque deformation includes the torque deformation at the 1 / 2*L cross section and the 2 / 3*L cross section of the blade.

[0013] Preferably, the calculation formula for the real-time attack angle of the blade section in step S2 is:

[0014]

[0015] Where α is the real-time operating angle of attack, a is the axial induction factor, v is the wind speed, r is the length from the blade cross section to the blade root, θ is the fixed twist angle, β is the pitch angle, and η is the real-time aerodynamic twist angle.

[0016] Preferably, after step S3, the method further includes:

[0017] S4. Obtaining the corresponding simulated pitch angle by running the attack angle in real time;

[0018] S5. Adjusting the pitch amount of the wind turbine generator according to the simulated pitch angle.

[0019] Preferably, a given pitch angle is obtained according to the simulated pitch angle, and then the pitch amount is adjusted according to the given pitch angle.

[0020] Preferably, the calculation formula for a given pitch angle is:

[0021]

[0022] in is a given pitch angle, α is the real-time operating angle of attack, βin is the simulated pitch angle corresponding to the real-time operating angle of attack, an is the critical angle of attack at the 2 / 3*L section of the blade, where L is the blade length.

[0023] Preferably, the corresponding relationship between the real-time operating angle of attack and the preset critical angle of attack and the simulated pitch angle is obtained through simulation.

[0024] The present invention also discloses a wind turbine blade stall monitoring system, comprising a memory and a processor, wherein the memory stores a computer program, and the computer program executes the steps of the above method when executed by the processor.

[0025] Compared with the prior art, the advantages of the present invention are:

[0026] The present invention calculates the real-time operating angle of attack of the blades through the real-time aerodynamic twist angle of the blades, and then determines whether the blades are in a stall state based on the comparison between the real-time operating angle of attack and the preset critical angle of attack, thereby ensuring the safe operation of the unit; at the same time, the power output of the unit is guaranteed by real-time pitch angle adjustment, so that the power generation loss is lower than the power generation loss caused by stall; compared with monitoring the stall of the wind turbine set through cross-sectional aerodynamic parameters, power curve, and vibration frequency, this method is more accurate and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The flowchart of the monitoring method of the present invention in an embodiment. DETAILED DESCRIPTION

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0029] like Figure 1 As shown, the method for monitoring blade stall of a wind turbine generator set according to an embodiment of the present invention includes the following steps:

[0030] S1. Obtaining the operating data of the wind turbine and the real-time aerodynamic twist angle of the blades;

[0031] S2. Obtaining the real-time operating angle of attack of the blade cross section based on the operating data of the wind turbine generator set and the real-time aerodynamic twist angle of the blade;

[0032] S3. Compare the real-time operating angle of attack with a preset critical angle of attack; when the real-time operating angle of attack is greater than the preset critical angle of attack, determine that the wind turbine blades are stalled.

[0033] The present invention calculates the real-time operating angle of attack of the blades through the real-time aerodynamic twist angle of the blades, and then determines whether the blades are in a stall state based on the comparison between the real-time operating angle of attack and the preset critical angle of attack, thereby ensuring the safe operation of the unit; compared with monitoring the stall of the wind turbine through cross-sectional aerodynamic parameters, power curve, and vibration frequency, this method is more accurate and reliable. The specific analysis is as follows: monitoring whether the wind turbine is stalled through cross-sectional aerodynamic parameters, power curve, and vibration frequency is prone to misdetection. For example, if the power curve does not meet the rated requirements under the rated state, it may be caused by blade icing, resulting in a decrease in the aerodynamic performance of the blades, or it may be caused by corrosion of the leading edge of the blades; monitoring through vibration frequency may be caused by other factors such as flutter, vortex-induced vibration, etc.; while calculating the real-time operating angle of attack of the blades through real-time aerodynamic twist angle is more direct, and there is a unique corresponding relationship between the real-time operating angle of attack and stall, so this method is more accurate and reliable.

[0034] In a specific embodiment, the wind turbine operating data in step S1 includes generator speed, generator torque, pitch angle, pitch rate, power generation, air density, blade operating parameters, axial induction factor, etc. The above operating data are conventional data of the wind turbine and can be directly obtained in the wind turbine control system.

[0035] In one specific embodiment, in step S1, the blade's real-time aerodynamic twist angle is obtained by acquiring the blade's torque deformation in real time. Specifically, torque sensors are installed at the blade's (1 / 2)*L and (2 / 3)*L sections, where L is the blade length. The torque sensors measure the blade's real-time torque deformation and convert it into the blade's real-time aerodynamic twist angle. Determining the blade's real-time aerodynamic twist angle by measuring the torque deformation at these two reasonable locations ensures data accuracy while minimizing the number of torque sensors and reducing costs.

[0036] In a specific embodiment, after step S3, the method further includes the following steps:

[0037] S4. Obtaining the corresponding simulated pitch angle by running the attack angle in real time;

[0038] S5. Adjusting the pitch amount of the wind turbine generator according to the simulated pitch angle.

[0039] Specifically, in step S5, a given pitch angle is obtained according to the simulated pitch angle, and then the pitch amount is adjusted according to the given pitch angle; wherein the calculation formula of the given pitch angle is:

[0040]

[0041] in is a given pitch angle, α is the real-time operating angle of attack, βin is the simulated pitch angle corresponding to the real-time operating angle of attack, an is the critical angle of attack at the 2 / 3*L section of the blade, where L is the blade length.

[0042] When the blades stall, the above-mentioned pitch control is used to ensure the safe operation of the unit. The above-mentioned pitch control process is adjusted according to the real-time operating angle of attack, and its adjustment accuracy is high.

[0043] The present invention also discloses a wind turbine blade stall monitoring system, comprising a memory and a processor, wherein the memory stores a computer program, and the computer program executes the steps of the above method when executed by the processor. Of course, the above monitoring system can also be divided into multiple modules corresponding to the steps of the method, specifically as follows Figure 1 As shown, it includes an angle of attack conversion module, a data query module, a data comparison module, a data identification module and a pitch angle conversion module. The specific steps performed by each module can be found in the following specific embodiments.

[0044] The method of the present invention will be further described below based on a complete specific embodiment:

[0045] During the operation of the wind turbine, the wind turbine operating data is obtained, including generator speed, generator torque, pitch angle, pitch rate, power generation, air density, blade operating parameters, axial induction factor, etc.

[0046] Torque sensors are installed at the (1 / 2)*L section and (2 / 3)*L section of the blade (where L is the blade length). The torque sensors measure the torque deformation of the blade in real time and convert it into the real-time aerodynamic twist angle η of the blade.

[0047] In the angle of attack conversion module: the real-time angle of attack of the blade section is calculated using the above-mentioned measured data. The conversion formula is as follows:

[0048]

[0049] Where α is the angle of attack, a is the axial induction factor, v is the wind speed, r is the length of the blade section from the blade root, θ is the fixed twist angle, β is the pitch angle, and η is the measured blade twist angle.

[0050] A large pre-set database contains the critical angles of attack of each blade airfoil section; the average value of the simulated running angles of attack at the blade (1 / 2)*L section to the (2 / 3)*L section under different wind speeds and air densities + 1.28 times the standard deviation, such as P11 = P1mean + 1.28*δ1. The stall risk under simulation conditions is determined by determining the size of P11 and the critical angle of attack. The database under the wind speed Vx condition is shown in Table 1 below:

[0051] Table 1

[0052]

[0053] The critical angle of attack of the turbine is found through the data query module and then compared with the real-time operating angle of attack obtained by the conversion of the angle of attack mentioned above through the data comparison module. If the real-time operating angle of attack is less than the critical angle of attack, it is determined that there is no stall and the turbine continues to operate. If the real-time operating angle of attack is greater than the critical angle of attack, it is determined to be a stall.

[0054] Furthermore, the data recognition module identifies the equivalence between the real-time running angle of attack and the simulated angle of attack value in the database, and finds the corresponding simulated pitch angle, such as α=Pin, and the corresponding pitch is βin;

[0055] The pitch angle conversion module adjusts the pitch angle based on the simulated pitch angle. The adjustment principle is shown in the following formula:

[0056]

[0057] By a given pitch angle Adjust the pitch amount to ensure safe operation of the unit.

[0058] The present invention measures the real-time aerodynamic twist angle of the unit blades in real time, converts it into a real-time operating angle of attack, and then compares it with the critical angle of attack. If the unit stalls, the simulated pitch angle is searched and identified through a simulation database, and the pitch angle is adjusted in real time to ensure the safe operation of the unit. At the same time, the power output of the unit is guaranteed by real-time pitch angle adjustment, so that the power generation loss is lower than the power generation loss caused by stall.

[0059] As shown in this disclosure and the claims, unless the context clearly indicates an exception, the words "a", "an", "an" and / or "the" do not specifically refer to the singular, but also include the plural. The words "first", "second" and similar words used in this disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "include" or "comprise" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect.

[0060] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions based on the principles of the present invention are within the scope of protection of the present invention. It should be noted that for those skilled in the art, various improvements and modifications that do not depart from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A method for monitoring blade stall of a wind turbine generator set, characterized in that: Including steps: S1. Obtaining the operating data of the wind turbine and the real-time aerodynamic twist angle of the blades; S2. Obtaining the real-time operating angle of attack of the blade cross section based on the operating data of the wind turbine generator set and the real-time aerodynamic twist angle of the blade; S3. Comparing the real-time operating angle of attack with a preset critical angle of attack; When the real-time operating angle of attack is greater than a preset critical angle of attack, it is determined that the wind turbine blades are stalled; After step S3, the method further includes: S4. Obtaining the corresponding simulated pitch angle by running the attack angle in real time; S5. Adjusting the pitch amount of the wind turbine generator according to the simulated pitch angle.

2. The method for monitoring blade stall of a wind turbine generator set according to claim 1, characterized in that: In step S1 , the corresponding operating data includes one or more of generator speed, generator torque, pitch angle, pitch rate, generated power, air density, blade operating parameters and axial induction factor.

3. The method for monitoring blade stall of a wind turbine generator set according to claim 1, characterized in that: In step S1 , the real-time aerodynamic twist angle of the blade is obtained by acquiring the torque deformation of the blade in real-time state.

4. The method for monitoring blade stall of a wind turbine generator set according to claim 3, characterized in that: The torque deformation includes the torque deformation at the 1 / 2*L section and the 2 / 3*L section of the blade.

5. The method for monitoring blade stall of a wind turbine generator set according to any one of claims 1 to 4, characterized in that: The calculation formula of the real-time attack angle of the blade section in step S2 is: Where α is the real-time operating angle of attack, a is the axial induction factor, v is the wind speed, r is the length from the blade cross section to the blade root, θ is the fixed twist angle, β is the pitch angle, and η is the real-time aerodynamic twist angle.

6. The method for monitoring blade stall of a wind turbine generator set according to claim 1, characterized in that: In step S5, a given pitch angle is obtained according to the simulated pitch angle, and then the pitch amount is adjusted according to the given pitch angle.

7. The method for monitoring blade stall of a wind turbine generator set according to claim 6, characterized in that: The calculation formula for a given pitch angle is: in is a given pitch angle, α is the real-time operating angle of attack, βin is the simulated pitch angle corresponding to the real-time operating angle of attack, αn is the critical angle of attack at the 2 / 3*L section of the blade, where L is the blade length.

8. The method for monitoring blade stall of a wind turbine generator set according to claim 7, characterized in that: The corresponding relationship between the real-time operating angle of attack, the preset critical angle of attack and the simulated pitch angle is obtained through simulation.

9. A wind turbine blade stall monitoring system, comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the computer program is executed by a processor, the computer program performs the steps of the method according to any one of claims 1 to 8.

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