Extreme vertical wind shear identification and de-rating control method and system for wind turbine generators

Abstract

The application discloses a kind of extreme vertical wind shear identification and load reduction control method and system of wind turbine unit, comprising: obtaining the blade root bending moment of two directions of blade root, i.e. blade root flapping bending moment and blade root edgewise bending moment, according to current measured variable pitch angle, obtain blade root out-of-plane bending moment by rotation transformation;Current blade azimuth angle is obtained, and the blade root out-of-plane bending moment is carried out coordinate transformation, and the wind wheel pitch bending moment is calculated;Based on wind wheel pitch bending moment and current average wind speed, the vertical wind shear coefficient is calculated, when the vertical wind shear coefficient exceeds preset threshold, the current wind condition is identified as extreme vertical wind shear;When the current wind condition is identified as extreme vertical wind shear, additional independent variable pitch instruction is calculated and output, which is superimposed on the variable pitch instruction output by the variable pitch controller, to generate additional bending moment on the wind wheel, which cancels out the wind wheel pitch bending moment.The application is based on the measured blade root load, identifies whether the current is extreme vertical wind shear, and reduces the load by additional independent variable pitch instruction.

Description

Technical Field

[0001] This invention relates to the technical field of wind turbine control, and in particular to a method, system, storage medium, and computing device for identifying extreme vertical wind shear and controlling load reduction in wind turbines. Background Technology

[0002] During their entire lifecycle, wind turbines inevitably encounter various extreme wind conditions. Among these, operation under extreme wind shear is a type of extreme condition that IEC design specifications require consideration of. Extreme wind shear is divided into two categories: extreme horizontal wind shear and extreme vertical wind shear. Extreme horizontal wind shear refers to a rapid change in the average wind speed along the horizontal direction at the rotor plane; extreme vertical wind shear refers to a rapid change in the average wind speed along the vertical direction at the rotor plane. Extreme wind shear can cause significant unbalanced loads on the rotor plane, resulting in ultimate loads on components such as the blade root, hub, and yaw bearing. For large wind turbines, due to the larger rotor diameter, the impact of extreme wind shear on the ultimate loads of components is even more significant. Currently, existing control strategies cannot identify extreme vertical wind shear conditions, and therefore cannot effectively reduce loads for extreme vertical wind shear. Summary of the Invention

[0003] The primary objective of this invention is to overcome the shortcomings and deficiencies of the prior art and provide a method for identifying and controlling extreme vertical wind shear in wind turbines. Based on the measured blade root load, the method identifies whether the current situation is extreme vertical wind shear and reduces the load by adding independent pitch commands.

[0004] The second objective of this invention is to provide an extreme vertical wind shear identification and load reduction control system for wind turbine generators.

[0005] A third objective of this invention is to provide a storage medium.

[0006] A fourth objective of this invention is to provide a computing device.

[0007] The first objective of this invention is achieved through the following technical solution: a method for identifying and controlling extreme vertical wind shear in wind turbine generators, comprising the following operations:

[0008] Obtain the blade root bending moment in two directions, namely the blade root flapping bending moment and the blade root oscillation bending moment. Based on the current measured pitch angle, obtain the blade root out-of-plane bending moment through rotation transformation.

[0009] Obtain the current blade azimuth angle, perform coordinate transformation on the out-of-plane bending moment at the blade root, and calculate the wind turbine pitching moment;

[0010] Based on the wind turbine pitch moment and the current average wind speed, the vertical wind shear coefficient is calculated. When the vertical wind shear coefficient exceeds the preset threshold, the current wind condition is identified as extreme vertical wind shear.

[0011] When the current wind condition is identified as extreme vertical wind shear, an additional independent pitch command is calculated and output, which is superimposed on the pitch command output by the pitch controller. The additional bending moment generated on the wind turbine is reduced by the pitch moment of the wind turbine.

[0012] Furthermore, a load sensor, called a blade root load sensor, needs to be installed at the root of each blade. This sensor can measure the bending moment in two directions at the blade root in real time: the blade root flapping moment and the blade root oscillation moment. The blade root flapping moment refers to the load generated by the blade bending and deforming from the pressure surface to the suction surface; the positive direction of the blade root flapping moment is defined as the pressure surface being stretched while the suction surface is compressed. The blade root oscillation moment refers to the load generated by the blade bending and deforming from the trailing edge to the leading edge; the positive direction of the blade root oscillation moment is defined as the trailing edge being stretched while the leading edge is compressed.

[0013] The blade root out-of-plane bending moment refers to the blade root bending moment generated by the bending deformation of the blade relative to the wind turbine plane in the direction perpendicular to the wind turbine plane; the positive direction of the blade root out-of-plane bending moment is defined as the direction of the blade bending perpendicular to the wind turbine plane and along the tail of the nacelle; since the wind turbine continuously adjusts the pitch during operation, it is necessary to perform a rotational transformation on the blade root flapping moment and the blade root oscillation moment in order to obtain the blade root out-of-plane bending moment.

[0014] The formula for calculating the out-of-plane bending moment at the leaf root is as follows:

[0015]

[0016] In the above formula, M out1 M represents the external load on the root surface of the first blade; out2 Indicates the external load on the root surface of the second blade; M out3 M represents the external load on the root surface of the third blade; flap1 M represents the flapping moment at the root of the first blade measured by the sensor. flap2 M represents the flapping moment at the root of the second blade, measured by the sensor. flap3 M represents the flapping moment at the root of the third blade measured by the sensor. edge1 M represents the root oscillation bending moment of the first blade measured by the sensor; edge2 M represents the root oscillation bending moment of the second blade measured by the sensor; edge3 This represents the root oscillation bending moment of the third blade measured by the sensor; Indicates the average pitch angle after filtering;

[0017] The formula for calculating the average pitch angle after filtering is as follows:

[0018]

[0019] In the above formula, F represents the filtered average pitch angle; β (s) represents the pitch angle filter, which includes a low-pass filter and a band-stop filter; This indicates the pitch angle of the first blade measured by the sensor. This indicates the pitch angle of the second blade measured by the sensor. This indicates the pitch angle of the third blade measured by the sensor.

[0020] Furthermore, the current blade azimuth angle is obtained by collecting the azimuth angle sensor. The wind turbine pitch moment reflects the force imbalance of the wind turbine plane in the vertical direction. Due to the existence of vertical wind shear, the wind speed in the upper half of the wind turbine plane is higher than that in the lower half of the wind turbine plane, resulting in a large thrust on the upper half of the wind turbine plane and a small thrust on the lower half of the wind turbine plane, thus generating the wind turbine pitch moment.

[0021] The reference coordinate system for the wind turbine pitch moment is a fixed coordinate system, which is fixed at the center of the hub, stationary relative to the nacelle, and does not rotate with the wind turbine; the reference coordinate system for the blade root out-of-plane bending moment is a rotating coordinate system, which is fixed on the wind turbine and rotates with the wind turbine; in order to obtain the wind turbine pitch moment, it is necessary to transform the blade root out-of-plane bending moment in the rotating coordinate system to the fixed coordinate system.

[0022] The formula for calculating the pitch moment of the wind turbine is as follows:

[0023]

[0024] In the above formula, M D Indicates the pitch moment of the wind turbine; M out1 M represents the external load on the root surface of the first blade; out2 Indicates the external load on the root surface of the second blade; M out3 This indicates the external load on the root surface of the third blade; This indicates the azimuth angle measured for the first blade.

[0025] Furthermore, when a wind turbine encounters extreme vertical wind shear, the wind speed in the upper half of the rotor plane is higher than that in the lower half of the rotor plane, resulting in a large thrust in the upper half of the rotor plane and a small thrust in the lower half of the rotor plane. This generates a large rotor pitch moment. The rotor pitch moment has a clear linear relationship with the vertical wind shear coefficient. Therefore, the vertical wind shear coefficient can be derived by applying the rotor pitch moment.

[0026] The formula for calculating the vertical wind shear coefficient is as follows:

[0027]

[0028] In the above formula, Indicates the vertical wind shear coefficient; This represents the average wind speed, obtained by performing a moving average filter on the measured wind speed. The scaling factor representing the pitch moment of the wind turbine to the vertical wind shear coefficient is expressed through the average wind speed. Obtained by looking up the table; The bias factor representing the pitch moment of the wind turbine to the vertical wind shear coefficient is expressed by the average wind speed. Obtained by looking up the table;

[0029] If the vertical wind shear coefficient exceeds the normal wind shear coefficient and reaches a specific value, the current wind condition should be identified as extreme vertical wind shear. Therefore, an extreme vertical wind shear threshold is set. When the vertical wind shear coefficient is detected to exceed the extreme wind shear threshold, the extreme vertical wind shear status flag is set to true; otherwise, it is set to false. The definition of the extreme vertical wind shear status flag is as follows:

[0030]

[0031] In the above formula, Indicates the extreme vertical wind shear state flag; K max This indicates the extreme vertical wind shear threshold; if indicates a conditional judgment, and other indicates other cases.

[0032] Furthermore, if the extreme vertical wind shear status flag is true, it indicates that the current wind condition is extreme vertical wind shear. At this time, the blades, hub, yaw bearing and tower top of the wind turbine will be subjected to large loads. By superimposing an independent pitch command on the pitch angle of the wind turbine, an additional bending moment can be generated on the wind turbine. When this additional bending moment is opposite to the pitch bending moment of the wind turbine caused by wind shear, it can offset the bending moment load generated by extreme vertical wind shear.

[0033] The calculation formula for additional independent pitch commands is as follows:

[0034]

[0035] In the above formula, This indicates an additional independent pitch command for the first blade; This indicates an additional independent pitch command for the second blade; Indicates an additional independent pitch command for the third blade; A V,shear Indicates the amplitude gain of the additional pitch command; Indicates the vertical wind shear coefficient; ω represents the azimuth angle measured for the first blade. r τ represents the measured rotational speed of the wind turbine; τ represents the time delay of the pitch control system.

[0036] The pitch control controller outputs a pitch command, which is then superimposed with an additional independent pitch command to obtain the final pitch command. This final pitch command is transmitted to the pitch actuator, and the blades execute pitch control based on this final pitch command. The final pitch command is defined as follows:

[0037]

[0038] In the above formula, This indicates the final pitch command for the first blade; This indicates the final pitch command for the second blade; This indicates the final pitch command for the third blade; This indicates the pitch command output by the pitch controller for the first blade. This indicates the pitch command output by the pitch controller for the second blade; This indicates the pitch control output for the third blade. This indicates an additional independent pitch command for the first blade; This indicates an additional independent pitch command for the second blade; This indicates an additional independent pitch control command for the third blade; This indicates an extreme vertical wind shear state flag; if indicates a conditional judgment, and other indicates other situations.

[0039] The second objective of this invention is achieved through the following technical solution: an extreme vertical wind shear identification and load reduction control system for wind turbine generators, used to implement the aforementioned extreme vertical wind shear identification and load reduction control method for wind turbine generators, comprising:

[0040] The blade root out-of-plane bending moment acquisition module is used to acquire the blade root bending moment in two directions, namely the blade root flapping bending moment and the blade root oscillation bending moment. Based on the current measured pitch angle, the blade root out-of-plane bending moment is obtained through rotation transformation.

[0041] The wind turbine pitch moment calculation module is used to obtain the current blade azimuth angle, perform coordinate transformation on the out-of-plane bending moment at the blade root, and calculate the wind turbine pitch moment.

[0042] The extreme vertical wind shear identification module calculates the vertical wind shear coefficient based on the wind turbine pitch moment and the current average wind speed. When the vertical wind shear coefficient exceeds a preset threshold, the current wind condition is identified as extreme vertical wind shear.

[0043] The extreme vertical wind shear control module is used to calculate and output additional independent pitch commands when the current wind condition is identified as extreme vertical wind shear. These commands are superimposed on the pitch commands output by the pitch controller, and the additional bending moment generated on the wind turbine is reduced by the pitch moment of the wind turbine.

[0044] The third objective of this invention is achieved through the following technical solution: a storage medium storing a program, which, when executed by a processor, implements the above-mentioned method for identifying extreme vertical wind shear and controlling load reduction in wind turbine units.

[0045] The fourth objective of this invention is achieved through the following technical solution: a computing device, including a processor and a memory for storing processor-executable programs, wherein when the processor executes the program stored in the memory, it implements the above-mentioned method for identifying and reducing load on wind turbine generators.

[0046] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0047] 1. This invention constructs the wind turbine pitch moment by using blade root load. Based on the linear relationship between the wind turbine pitch moment and extreme vertical wind shear, it provides a method for identifying extreme vertical wind shear, which can effectively identify extreme vertical wind shear.

[0048] 2. This invention generates an additional bending moment in the rotor plane by superimposing an independent pitch command on the pitch command. This moment is opposite to the pitch moment generated by extreme vertical wind shear, which can significantly reduce the ultimate load under extreme vertical wind shear. Attached Figure Description

[0049] Figure 1 This is an architecture diagram of the system of the present invention. Detailed Implementation

[0050] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0051] Example 1

[0052] This embodiment discloses a method for identifying extreme vertical wind shear and controlling load reduction in wind turbine generators, specifically performing the following operations:

[0053] 1) The blade root bending moment in two directions, namely the blade root flapping bending moment and the blade root oscillation bending moment, is acquired by the blade root load sensor. Based on the current measured pitch angle, the out-of-plane bending moment of the blade root is obtained by rotation transformation.

[0054] Each blade needs to be equipped with a load sensor at its root, called a blade root load sensor. This sensor measures the bending moment in two directions at the blade root in real time: the blade root flapping moment and the blade root oscillation moment. The blade root flapping moment is the load generated by the blade bending and deforming from the pressure surface to the suction surface; the positive direction of the blade root flapping moment is defined as the pressure surface being stretched while the suction surface is compressed. The blade root oscillation moment is the load generated by the blade bending and deforming from the trailing edge to the leading edge; the positive direction of the blade root oscillation moment is defined as the trailing edge being stretched while the leading edge is compressed.

[0055] The blade root out-of-plane bending moment refers to the blade root bending moment generated by the bending deformation of the blade relative to the wind turbine plane in the direction perpendicular to the wind turbine plane; the positive direction of the blade root out-of-plane bending moment is defined as the direction of the blade bending perpendicular to the wind turbine plane and along the tail of the nacelle; since the wind turbine continuously adjusts the pitch during operation, it is necessary to perform a rotational transformation on the blade root flapping moment and the blade root oscillation moment in order to obtain the blade root out-of-plane bending moment.

[0056] The formula for calculating the out-of-plane bending moment at the leaf root is as follows:

[0057]

[0058] In the above formula, M out1 M represents the external load on the root surface of the first blade; out2 Indicates the external load on the root surface of the second blade; M out3 M represents the external load on the root surface of the third blade; flap1 M represents the flapping moment at the root of the first blade measured by the sensor. flap2 M represents the flapping moment at the root of the second blade, measured by the sensor. flap3 M represents the flapping moment at the root of the third blade measured by the sensor. edge1 M represents the root oscillation bending moment of the first blade measured by the sensor; edge2 M represents the root oscillation bending moment of the second blade measured by the sensor; edge3 This represents the root oscillation bending moment of the third blade measured by the sensor; Indicates the average pitch angle after filtering;

[0059] The formula for calculating the average pitch angle after filtering is as follows:

[0060]

[0061] In the above formula, F represents the filtered average pitch angle; β (s) represents the pitch angle filter, which includes a low-pass filter and a band-stop filter; This indicates the pitch angle of the first blade measured by the sensor. This indicates the pitch angle of the second blade measured by the sensor. This indicates the pitch angle of the third blade measured by the sensor.

[0062] 2) The current blade azimuth angle is acquired by the azimuth sensor, the out-of-plane bending moment at the blade root is transformed by coordinate transformation, and the pitching moment of the wind turbine is calculated.

[0063] The pitch moment of the wind turbine reflects the unbalanced force on the wind turbine plane in the vertical direction. Due to the existence of vertical wind shear, the wind speed in the upper half of the wind turbine plane is higher than that in the lower half of the wind turbine plane, resulting in a large thrust on the upper half of the wind turbine plane and a small thrust on the lower half of the wind turbine plane, thus generating the pitch moment of the wind turbine.

[0064] The reference coordinate system for the wind turbine pitch moment is a fixed coordinate system, which is fixed at the center of the hub, stationary relative to the nacelle, and does not rotate with the wind turbine; the reference coordinate system for the blade root out-of-plane bending moment is a rotating coordinate system, which is fixed on the wind turbine and rotates with the wind turbine; in order to obtain the wind turbine pitch moment, it is necessary to transform the blade root out-of-plane bending moment in the rotating coordinate system to the fixed coordinate system.

[0065] The formula for calculating the pitch moment of the wind turbine is as follows:

[0066]

[0067] In the above formula, M D Indicates the pitch moment of the wind turbine; M out1 M represents the external load on the root surface of the first blade; out2 Indicates the external load on the root surface of the second blade; M out3 This indicates the external load on the root surface of the third blade; This indicates the azimuth angle measured for the first blade.

[0068] 3) Based on the wind turbine pitch moment and the current average wind speed, the vertical wind shear coefficient is calculated. When the vertical wind shear coefficient exceeds the preset threshold, the current wind condition is identified as extreme vertical wind shear.

[0069] When a wind turbine encounters extreme vertical wind shear, the wind speed in the upper half of the rotor plane is higher than that in the lower half of the rotor plane, resulting in a larger thrust in the upper half of the rotor plane and a smaller thrust in the lower half of the rotor plane. This generates a large rotor pitch moment. The rotor pitch moment has a clear linear relationship with the vertical wind shear coefficient. Therefore, the vertical wind shear coefficient can be derived by applying the rotor pitch moment.

[0070] The formula for calculating the vertical wind shear coefficient is as follows:

[0071]

[0072] In the above formula, Indicates the vertical wind shear coefficient; This represents the average wind speed, obtained by performing a moving average filter on the measured wind speed. The scaling factor representing the pitch moment of the wind turbine to the vertical wind shear coefficient is expressed through the average wind speed. Obtained by looking up the table; The bias factor representing the pitch moment of the wind turbine to the vertical wind shear coefficient is expressed by the average wind speed. Obtained by looking up the table;

[0073] If the vertical wind shear coefficient exceeds the normal wind shear coefficient and reaches a specific value, the current wind condition should be identified as extreme vertical wind shear. Therefore, an extreme vertical wind shear threshold is set. When the vertical wind shear coefficient is detected to exceed the extreme wind shear threshold, the extreme vertical wind shear status flag is set to true; otherwise, it is set to false. The definition of the extreme vertical wind shear status flag is as follows:

[0074]

[0075] In the above formula, Indicates the extreme vertical wind shear state flag; K max This indicates the extreme vertical wind shear threshold; if indicates a conditional judgment, and other indicates other cases.

[0076] 4) When the current wind condition is identified as extreme vertical wind shear, an additional independent pitch command is calculated and output, which is superimposed on the pitch command output by the pitch controller. The additional bending moment generated on the wind turbine is reduced by the pitch moment of the wind turbine.

[0077] If the extreme vertical wind shear status flag is true, it indicates that the current wind condition is extreme vertical wind shear. At this time, the blades, hub, yaw bearing and tower top of the wind turbine will be subjected to a large load. By superimposing an independent pitch command on the pitch angle of the wind turbine, an additional bending moment can be generated on the wind rotor. When this additional bending moment is opposite to the pitch bending moment of the wind rotor caused by wind shear, it can offset the bending moment load generated by extreme vertical wind shear.

[0078] The calculation formula for additional independent pitch commands is as follows:

[0079]

[0080] In the above formula, This indicates an additional independent pitch command for the first blade; This indicates an additional independent pitch command for the second blade; Indicates an additional independent pitch command for the third blade; A V,shear Indicates the amplitude gain of the additional pitch command; Indicates the vertical wind shear coefficient; ω represents the azimuth angle measured for the first blade. r τ represents the measured rotational speed of the wind turbine; τ represents the time delay of the pitch control system.

[0081] The pitch control controller outputs a pitch command, which is then superimposed with an additional independent pitch command to obtain the final pitch command. This final pitch command is transmitted to the pitch actuator, and the blades execute pitch control based on this final pitch command. The final pitch command is defined as follows:

[0082]

[0083] In the above formula, This indicates the final pitch command for the first blade; This indicates the final pitch command for the second blade; This indicates the final pitch command for the third blade; This indicates the pitch command output by the pitch controller for the first blade. This indicates the pitch command output by the pitch controller for the second blade; This indicates the pitch control output for the third blade. This indicates an additional independent pitch command for the first blade; This indicates an additional independent pitch command for the second blade; This indicates an additional independent pitch control command for the third blade; This indicates an extreme vertical wind shear state flag; if indicates a conditional judgment, and other indicates other situations.

[0084] Example 2

[0085] This embodiment discloses an extreme vertical wind shear identification and load reduction control system for wind turbines, used to implement the extreme vertical wind shear identification and load reduction control method for wind turbines described in Embodiment 1, such as... Figure 1 As shown, the system includes the following functional modules:

[0086] The blade root out-of-plane bending moment acquisition module is used to acquire the blade root bending moment in two directions, namely the blade root flapping bending moment and the blade root oscillation bending moment. Based on the current measured pitch angle, the blade root out-of-plane bending moment is obtained through rotation transformation.

[0087] The wind turbine pitch moment calculation module is used to obtain the current blade azimuth angle, perform coordinate transformation on the out-of-plane bending moment at the blade root, and calculate the wind turbine pitch moment.

[0088] The extreme vertical wind shear identification module calculates the vertical wind shear coefficient based on the wind turbine pitch moment and the current average wind speed. When the vertical wind shear coefficient exceeds a preset threshold, the current wind condition is identified as extreme vertical wind shear.

[0089] The extreme vertical wind shear control module is used to calculate and output additional independent pitch commands when the current wind condition is identified as extreme vertical wind shear. These commands are superimposed on the pitch commands output by the pitch controller, and the additional bending moment generated on the wind turbine is reduced by the pitch moment of the wind turbine.

[0090] Example 3

[0091] This embodiment discloses a storage medium storing a program. When the program is executed by a processor, it implements the extreme vertical wind shear identification and load reduction control method for wind turbines described in Embodiment 1.

[0092] The storage medium in this embodiment can be a disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), USB flash drive, portable hard drive, etc.

[0093] Example 4

[0094] This embodiment discloses a computing device, including a processor and a memory for storing processor-executable programs. When the processor executes the program stored in the memory, it implements the extreme vertical wind shear identification and load reduction control method for wind turbines described in Embodiment 1.

[0095] The computing device described in this embodiment may be a desktop computer, laptop computer, smartphone, PDA handheld terminal, tablet computer, programmable logic controller (PLC), or other terminal device with processor function.

[0096] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for identifying extreme vertical wind shear and controlling load reduction in wind turbine generators, characterized in that, Perform the following operations: Obtain the blade root bending moment in two directions, namely the blade root flapping bending moment and the blade root oscillation bending moment. Based on the current measured pitch angle, obtain the blade root out-of-plane bending moment through rotation transformation. Obtain the current blade azimuth angle, perform coordinate transformation on the out-of-plane bending moment at the blade root, and calculate the wind turbine pitching moment; Based on the wind turbine pitch moment and the current average wind speed, the vertical wind shear coefficient is calculated. When the vertical wind shear coefficient exceeds the preset threshold, the current wind condition is identified as extreme vertical wind shear. When the current wind condition is identified as extreme vertical wind shear, an additional independent pitch command is calculated and output, which is superimposed on the pitch command output by the pitch controller. The additional bending moment generated on the wind turbine is reduced by the pitch moment of the wind turbine. When a wind turbine encounters extreme vertical wind shear, the wind speed in the upper half of the rotor plane is higher than that in the lower half of the rotor plane, resulting in a large thrust in the upper half of the rotor plane and a small thrust in the lower half of the rotor plane. This generates a large rotor pitch moment. The rotor pitch moment has a clear linear relationship with the vertical wind shear coefficient. Therefore, the vertical wind shear coefficient can be derived by applying the rotor pitch moment. The formula for calculating the vertical wind shear coefficient is as follows: ； In the above formula, Indicates the vertical wind shear coefficient; This represents the average wind speed, obtained by performing a moving average filter on the measured wind speed. The scaling factor representing the pitch moment of the wind turbine to the vertical wind shear coefficient is expressed through the average wind speed. Obtained by looking up the table; The bias factor representing the pitch moment of the wind turbine to the vertical wind shear coefficient is expressed by the average wind speed. Obtained by looking up the table; If the vertical wind shear coefficient exceeds the normal wind shear coefficient and reaches a specific value, the current wind condition should be identified as extreme vertical wind shear. Therefore, an extreme vertical wind shear threshold is set. When the vertical wind shear coefficient is detected to exceed the extreme wind shear threshold, the extreme vertical wind shear status flag is set to true; otherwise, it is set to false. The definition of the extreme vertical wind shear status flag is as follows: ； In the above formula, Indicates the flag for extreme vertical wind shear conditions; This indicates the extreme vertical wind shear threshold; if indicates a conditional judgment, and other indicates other cases. If the extreme vertical wind shear status flag is true, it indicates that the current wind condition is extreme vertical wind shear. At this time, the blades, hub, yaw bearing and tower top of the wind turbine will be subjected to large loads. By superimposing an independent pitch command on the pitch angle of the wind turbine, an additional bending moment can be generated on the wind rotor. When this additional bending moment is opposite to the pitch bending moment of the wind rotor caused by wind shear, it can offset the bending moment load generated by extreme vertical wind shear. The calculation formula for additional independent pitch commands is as follows: ； In the above formula, This indicates an additional independent pitch command for the first blade; This indicates an additional independent pitch command for the second blade; This indicates an additional independent pitch control command for the third blade; Indicates the amplitude gain of the additional pitch command; Indicates the vertical wind shear coefficient; This indicates the azimuth angle measured for the first blade; Indicates the measured rotational speed of the wind turbine; Indicates the time delay of the pitch control system; The pitch control controller outputs a pitch command, which is then superimposed with an additional independent pitch command to obtain the final pitch command. This final pitch command is transmitted to the pitch actuator, and the blades execute pitch control based on this final pitch command. The final pitch command is defined as follows: ； In the above formula, This indicates the final pitch command for the first blade; This indicates the final pitch command for the second blade; This indicates the final pitch command for the third blade; This indicates the pitch command output by the pitch controller for the first blade. This indicates the pitch command output by the pitch controller for the second blade; This indicates the pitch control output for the third blade. This indicates an additional independent pitch command for the first blade; This indicates an additional independent pitch command for the second blade; This indicates an additional independent pitch control command for the third blade; This indicates an extreme vertical wind shear state flag; if indicates a conditional judgment, and other indicates other situations.

2. The method for identifying and reducing load on wind turbine generators according to claim 1, characterized in that, Each blade needs to have a load sensor installed at its root, called a blade root load sensor. These sensors can measure the bending moments in two directions at the blade root in real time: the blade root flapping moment and the blade root oscillation moment. The blade root flapping moment is the load generated by the blade bending and deforming from the pressure surface to the suction surface; the positive direction of the blade root flapping moment is defined as the pressure surface being stretched while the suction surface is compressed. The blade root oscillation moment is the load generated by the blade bending and deforming from the trailing edge to the leading edge; the positive direction of the blade root oscillation moment is defined as the trailing edge being stretched while the leading edge is compressed. The blade root out-of-plane bending moment refers to the blade root bending moment generated by the bending deformation of the blade relative to the wind turbine plane in the direction perpendicular to the wind turbine plane; the positive direction of the blade root out-of-plane bending moment is defined as the direction of the blade bending perpendicular to the wind turbine plane and along the tail of the nacelle; since the wind turbine continuously adjusts the pitch during operation, it is necessary to perform a rotational transformation on the blade root flapping moment and the blade root oscillation moment in order to obtain the blade root out-of-plane bending moment. The formula for calculating the out-of-plane bending moment at the leaf root is as follows: ； In the above formula, This indicates the external load on the root surface of the first blade; This indicates the external load on the root surface of the second blade; This indicates the external load on the root surface of the third blade; This represents the flapping moment at the root of the first blade measured by the sensor. This indicates the flapping moment at the root of the second blade, as measured by the sensor. This represents the flapping moment at the root of the third blade, as measured by the sensor. This indicates the root oscillation bending moment of the first blade measured by the sensor; This indicates the bending moment at the root of the second blade, measured by the sensor. This represents the bending moment at the root of the third blade, measured by the sensor. Indicates the average pitch angle after filtering; The formula for calculating the average pitch angle after filtering is as follows: ； In the above formula, Indicates the average pitch angle after filtering; This refers to a pitch angle filter, which includes a low-pass filter and a band-stop filter. This indicates the pitch angle of the first blade measured by the sensor. This indicates the pitch angle of the second blade measured by the sensor. This indicates the pitch angle of the third blade measured by the sensor.

3. The method for identifying and reducing load on wind turbine generators according to claim 2, characterized in that, The current blade azimuth angle is obtained by the azimuth angle sensor. The wind turbine pitch moment reflects the unbalanced force on the wind turbine plane in the vertical direction. Due to the existence of vertical wind shear, the wind speed on the upper half of the wind turbine plane is higher than that on the lower half of the wind turbine plane, resulting in a large thrust on the upper half of the wind turbine plane and a small thrust on the lower half of the wind turbine plane, thus generating the wind turbine pitch moment. The reference coordinate system for the wind turbine pitch moment is a fixed coordinate system, which is fixed at the center of the hub, stationary relative to the nacelle, and does not rotate with the wind turbine; the reference coordinate system for the blade root out-of-plane bending moment is a rotating coordinate system, which is fixed on the wind turbine and rotates with the wind turbine; in order to obtain the wind turbine pitch moment, it is necessary to transform the blade root out-of-plane bending moment in the rotating coordinate system to the fixed coordinate system. The formula for calculating the pitch moment of the wind turbine is as follows: ； In the above formula, Indicates the pitch moment of the wind turbine; This indicates the external load on the root surface of the first blade; This indicates the external load on the root surface of the second blade; This indicates the external load on the root surface of the third blade; This indicates the azimuth angle measured for the first blade.

4. An extreme vertical wind shear identification and load reduction control system for wind turbine generators, characterized in that, The method for identifying and reducing load on wind turbine units according to any one of claims 1 to 3 includes: The blade root out-of-plane bending moment acquisition module is used to acquire the blade root bending moment in two directions, namely the blade root flapping bending moment and the blade root oscillation bending moment. Based on the current measured pitch angle, the blade root out-of-plane bending moment is obtained through rotation transformation. The wind turbine pitch moment calculation module is used to obtain the current blade azimuth angle, perform coordinate transformation on the out-of-plane bending moment at the blade root, and calculate the wind turbine pitch moment. The extreme vertical wind shear identification module calculates the vertical wind shear coefficient based on the wind turbine pitch moment and the current average wind speed. When the vertical wind shear coefficient exceeds a preset threshold, the current wind condition is identified as extreme vertical wind shear. The extreme vertical wind shear control module is used to calculate and output additional independent pitch commands when the current wind condition is identified as extreme vertical wind shear. These commands are superimposed on the pitch commands output by the pitch controller, and the additional bending moment generated on the wind turbine is reduced by the pitch moment of the wind turbine.

5. A storage medium storing a program, characterized in that, When the program is executed by the processor, it implements the extreme vertical wind shear identification and load reduction control method for wind turbine units as described in any one of claims 1 to 3.

6. A computing device, comprising a processor and a memory for storing a processor-executable program, characterized in that, When the processor executes the program stored in the memory, it implements the extreme vertical wind shear identification and load reduction control method for wind turbine units as described in any one of claims 1 to 3.

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