Extreme horizontal wind shear identification and load reduction control method and system for wind turbines

Abstract

The present invention discloses a method and system for identifying and controlling extreme horizontal wind shear for a wind turbine, including: obtaining blade root bending moments in two directions of the blade root, namely, the blade root flapping bending moment and the blade root shimmy bending moment; obtaining the blade root out-of-plane bending moment through rotational transformation based on the current measured pitch angle; obtaining the current blade azimuth angle, performing coordinate transformation on the blade root out-of-plane bending moment, and calculating the rotor shimmy bending moment; calculating the horizontal wind shear coefficient based on the rotor shimmy bending moment and the current average wind speed; identifying the current wind condition as extreme horizontal wind shear when the horizontal wind shear coefficient exceeds a preset threshold; and when the current wind condition is identified as extreme horizontal wind shear, calculating and outputting an additional independent pitch control command, which is superimposed on the pitch control command output by the pitch controller, so that the additional bending moment generated on the rotor counteracts the rotor shimmy bending moment. The present invention identifies whether the current condition is extreme horizontal wind shear based on the measured blade root load and reduces the load by providing the additional independent pitch control command.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbine control, and in particular to a method, system, storage medium and computing device for identifying and controlling extreme horizontal wind shear of a wind turbine. Background Art

[0002] Wind turbines will inevitably encounter various extreme wind conditions throughout their life cycle. Among them, the operation of wind turbines under extreme wind shear conditions is an extreme operating condition that the IEC design specifications require to be considered. Extreme wind shear is divided into two categories: extreme horizontal wind shear and extreme vertical wind shear. Extreme horizontal wind shear refers to the average wind speed on the rotor plane, which produces a velocity gradient change in the horizontal direction within a short period of time; extreme vertical wind shear refers to the average wind speed on the rotor plane, which produces a velocity gradient change in the vertical direction within a short period of time. Extreme wind shear conditions can cause large unbalanced loads on the rotor plane, and components such as the blade root, hub, and yaw bearing will generate extreme loads. For large wind turbines, due to the use of larger rotor diameters, the impact of extreme wind shear on the extreme loads of components is more significant. Currently, existing control strategies cannot identify extreme horizontal wind shear conditions and therefore cannot effectively reduce loads for extreme horizontal wind shear. Summary of the Invention

[0003] The first purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and provide a method for identifying and controlling extreme horizontal wind shear of a wind turbine. Based on the measured blade root load, it identifies whether the current situation is extreme horizontal wind shear and reduces the load by adding independent pitch control instructions.

[0004] A second object of the present invention is to provide an extreme horizontal wind shear identification and load reduction control system for a wind turbine.

[0005] A third object of the present invention is to provide a storage medium.

[0006] A fourth object of the present invention is to provide a computing device.

[0007] The first object of the present invention is achieved by the following technical solution: A method for identifying and controlling extreme horizontal wind shear of a wind turbine generator system, comprising the following steps:

[0008] Obtain the blade root bending moments in two directions, namely the blade root flapping bending moment and the blade root shimmy bending moment. According to the current measured pitch angle, the blade root out-of-plane bending moment is obtained through rotation transformation.

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

[0010] The horizontal wind shear coefficient is calculated based on the rotor oscillation bending moment and the current average wind speed. When the horizontal wind shear coefficient exceeds the preset threshold, the current wind condition is identified as extreme horizontal wind shear.

[0011] When the current wind condition is identified as extreme horizontal 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 rotor is offset by the wind rotor swing bending moment.

[0012] Furthermore, a load sensor, called a blade root load sensor, needs to be installed at the root of each blade. The blade root load sensor can measure the bending moments in two directions of the blade root in real time, namely the blade root flapping moment and the blade root shimmy moment. The blade root flapping moment refers to the load generated by the bending deformation of the blade from the pressure side to the suction side, and the positive direction of the blade root flapping moment is defined as the pressure side being stretched while the suction side is compressed. The blade root shimmy moment refers to the load generated by the bending deformation of the blade from the trailing edge to the leading edge, and the positive direction of the blade root shimmy 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 caused by the bending deformation of the blade relative to the rotor plane in a direction perpendicular to the rotor plane; the positive direction of the blade root out-of-plane bending moment is defined as the direction in which the blade is perpendicular to the rotor plane and bends along the tail of the nacelle; since the wind turbine continuously changes the pitch during operation, in order to obtain the blade root out-of-plane bending moment, it is necessary to perform a rotational transformation on the blade root flapping bending moment and the blade root shimmy bending moment;

[0014] The calculation formula of the blade root out-of-plane bending moment is as follows:

[0015]

[0016] In the above formula, M out1 represents the out-of-plane load on the root of the first blade; M out2 represents the out-of-plane load on the root of the second blade; M out3 represents the out-of-plane load on the root of the third blade; M flap1 represents the flapping bending moment of the first blade root measured by the sensor; M flap2 represents the flapping bending moment of the second blade root measured by the sensor; M flap3 represents the flapping bending moment of the third blade root measured by the sensor; M edge1 Indicates the root swing bending moment of the first blade measured by the sensor; M edge2 represents the root swing bending moment of the second blade measured by the sensor; M edge3 represents the root swing bending moment of the third blade measured by the sensor; represents the filtered average pitch angle;

[0017] The calculation formula of the filtered average pitch angle is as follows:

[0018]

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

[0020] Furthermore, the current blade azimuth angle is acquired by an azimuth sensor; the rotor shimmy bending moment reflects the unbalanced force on the rotor plane in the horizontal direction. Due to the existence of horizontal wind shear, the wind speed on the left half plane of the rotor is not equal to the wind speed on the right half plane, resulting in an unbalanced thrust on the left half plane and the right half plane of the rotor, thus generating the rotor shimmy bending moment;

[0021] The reference coordinate system for the rotor shimmy bending moment is a fixed coordinate system, which is fixed to the center of the hub, stationary relative to the nacelle, and does not rotate with the rotor. The reference coordinate system for the blade root out-of-plane bending moment is a rotating coordinate system, which is fixed to the rotor and rotates with the rotor. To obtain the rotor shimmy bending moment, it is necessary to transform the blade root out-of-plane bending moment in the rotating coordinate system into the fixed coordinate system.

[0022] The calculation formula of the wind rotor shimmying bending moment is as follows:

[0023]

[0024] In the above formula, M Q Indicates the rotor oscillation bending moment; M out1 represents the out-of-plane load on the root of the first blade; M out2 represents the out-of-plane load on the root of the second blade; M out3 represents the out-of-plane load on the root of the third blade; Indicates the azimuth angle measured by the first blade.

[0025] Furthermore, when a wind turbine encounters extreme horizontal wind shear, the wind speed in the left and right half planes of the rotor are not equal, resulting in an imbalance in the thrust in the left and right half planes of the rotor, thus generating a large rotor swing bending moment on the rotor. There is a clear linear relationship between the rotor swing bending moment and the horizontal wind shear coefficient, so the horizontal wind shear coefficient can be derived using the rotor swing bending moment.

[0026] Considering the existence of yaw error to wind, part of the rotor shimmy bending moment is caused by yaw error. Therefore, in the calculation process of horizontal wind shear coefficient, the influence of yaw error needs to be deducted. The calculation formula of the horizontal wind shear coefficient is as follows:

[0027]

[0028] In the above formula, represents the horizontal wind shear coefficient; Represents the average wind speed, which is obtained by performing a sliding average filter on the measured wind speed; The proportional factor of the rotor oscillation bending moment to the horizontal wind shear coefficient is expressed by the average wind speed Obtained by looking up the table; The offset factor of the rotor oscillation bending moment to the horizontal wind shear coefficient is expressed by the average wind speed Obtained by table lookup; Φ yaw represents the average yaw error angle; Indicates the influence factor of yaw error to horizontal wind shear, through the average wind speed Obtained by looking up the table;

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

[0030]

[0031] In the above formula, Indicates the extreme horizontal wind shear status flag; Indicates the horizontal wind shear coefficient; H max Indicates the extreme horizontal wind shear threshold; if indicates conditional judgment, or indicates the logical operation "or", and other indicates other conditions.

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

[0033] The calculation formula of the additional independent pitch command is as follows:

[0034]

[0035] In the above formula, Indicates the additional independent pitch command for the first blade; Indicates the additional independent pitch command for the second blade; Indicates the additional independent pitch command of the third blade; A H,shear Indicates the additional pitch command amplitude gain; represents the vertical wind shear coefficient; Indicates the azimuth angle measured by the first blade; ω r Indicates the measured speed of the wind rotor; τ indicates the time delay of the pitch system;

[0036] The pitch control output of the pitch controller is superimposed on the additional independent pitch control to obtain the final pitch control. The final pitch control command is transmitted to the pitch actuator, and the blade executes the pitch control with the final pitch control command as the target. The final pitch control command is defined as follows:

[0037]

[0038] In the above formula, Indicates the final pitch command of the first blade; Indicates the final pitch command for the second blade; Indicates the final pitch command for the third blade; Indicates the pitch command of the first blade output by the pitch controller; Indicates the pitch command of the second blade output by the pitch controller; Indicates the pitch command of the third blade output by the pitch controller; Indicates the additional independent pitch command for the first blade; Indicates the additional independent pitch command for the second blade; Indicates an additional independent pitch command for the third blade; Indicates the extreme horizontal wind shear status flag; if indicates conditional judgment, and other indicates other situations.

[0039] The second object of the present invention is achieved by the following technical solution: a wind turbine generator system for identifying and reducing loads, which is used to implement the above-mentioned wind turbine generator system for identifying and reducing loads, and comprises:

[0040] The blade root out-of-plane bending moment acquisition module is used to obtain the blade root bending moments in two directions of the blade root, namely the blade root flapping bending moment and the blade root shimmy bending moment. According to the current measured pitch angle, the blade root out-of-plane bending moment is obtained through rotation transformation;

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

[0042] The extreme horizontal wind shear identification module calculates the horizontal wind shear coefficient based on the rotor oscillation bending moment and the current average wind speed. When the horizontal wind shear coefficient exceeds a preset threshold, the current wind condition is identified as extreme horizontal wind shear;

[0043] The extreme horizontal wind shear control module is used to calculate and output additional independent pitch control instructions when the current wind condition is identified as extreme horizontal wind shear. The instructions are superimposed on the pitch control instructions output by the pitch controller, and the additional bending moment generated on the wind rotor is reduced by the wind rotor swing bending moment.

[0044] The third object of the present invention is achieved through the following technical solution: a storage medium stores a program, and when the program is executed by a processor, the extreme horizontal wind shear identification and load reduction control method of the wind turbine is implemented.

[0045] The fourth purpose of the present invention is achieved through the following technical solution: a computing device, comprising a processor and a memory for storing a program executable by the processor, wherein when the processor executes the program stored in the memory, the above-mentioned extreme horizontal wind shear identification and load reduction control method of the wind turbine is implemented.

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

[0047] 1. In view of the characteristics of horizontal wind shear, the present invention utilizes the linear relationship between the rotor oscillation bending moment and horizontal wind shear to construct a horizontal wind shear coefficient, thereby providing a method for identifying extreme horizontal wind shear.

[0048] 2. The present invention reduces the influence of yaw error on horizontal wind shear identification and can effectively and accurately identify extreme horizontal wind shear.

[0049] 3. The present invention superimposes an additional independent pitch command on the pitch command to generate an additional bending moment on the impeller plane, which is opposite to the rotor swing bending moment generated by horizontal wind shear, and can significantly reduce the limit load of extreme horizontal wind shear conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is an architecture diagram of the system of the present invention. DETAILED DESCRIPTION

[0051] The present invention will be described in further detail below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0052] Example 1

[0053] This embodiment discloses a method for identifying extreme horizontal wind shear and controlling load reduction of a wind turbine generator set, which specifically performs the following operations:

[0054] 1) Obtain the blade root bending moments in two directions, namely the blade root flapping bending moment and the blade root shimmy bending moment. According to the current measured pitch angle, the blade root out-of-plane bending moment is obtained through rotation transformation.

[0055] A load sensor, called a root load sensor, is installed at the root of each blade. The root load sensor can measure in real time the bending moments in two directions of the blade root, namely the root flapping moment and the root shimmy moment. The root flapping moment refers to the load generated by the blade bending from the pressure side to the suction side, with the positive direction of the root flapping moment defined as tension on the pressure side and compression on the suction side. The root shimmy moment refers to the load generated by the blade bending from the trailing edge to the leading edge, with tension on the trailing edge and compression on the leading edge defined as the positive direction of the root shimmy moment.

[0056] The blade root out-of-plane bending moment refers to the blade root bending moment caused by the bending deformation of the blade relative to the rotor plane in a direction perpendicular to the rotor plane; the positive direction of the blade root out-of-plane bending moment is defined as the direction in which the blade is perpendicular to the rotor plane and bends along the tail of the nacelle; since the wind turbine continuously changes the pitch during operation, in order to obtain the blade root out-of-plane bending moment, it is necessary to perform a rotational transformation on the blade root flapping bending moment and the blade root shimmy bending moment;

[0057] The calculation formula of the blade root out-of-plane bending moment is as follows:

[0058]

[0059] In the above formula, M out1 represents the out-of-plane load on the root of the first blade; M out2 represents the out-of-plane load on the root of the second blade; M out3 represents the out-of-plane load on the root of the third blade; M flap1 represents the flapping bending moment of the first blade root measured by the sensor; M flap2 represents the flapping bending moment of the second blade root measured by the sensor; M flap3 represents the flapping bending moment of the third blade root measured by the sensor; M edge1 Indicates the root swing bending moment of the first blade measured by the sensor; M edge2 represents the root swing bending moment of the second blade measured by the sensor; M edge3 represents the root swing bending moment of the third blade measured by the sensor; represents the filtered average pitch angle;

[0060] The calculation formula of the filtered average pitch angle is as follows:

[0061]

[0062] In the above formula, F β(s) represents the pitch angle filter, which includes a low-pass filter and a band-stop filter; Indicates the pitch angle of the first blade measured by the sensor; Indicates the pitch angle of the second blade measured by the sensor; Indicates the pitch angle of the third blade measured by the sensor.

[0063] 2) The current blade azimuth angle is obtained through the azimuth angle sensor, the out-of-plane bending moment of the blade root is transformed, and the wind rotor swing bending moment is calculated.

[0064] The rotor shimmying bending moment reflects the unbalanced force on the rotor plane in the horizontal direction. Due to the existence of horizontal wind shear, the wind speed on the left half plane of the rotor is not equal to the wind speed on the right half plane, resulting in an unbalanced thrust on the left half plane and the right half plane of the rotor, thus generating the rotor shimmying bending moment.

[0065] The reference coordinate system for the rotor shimmy bending moment is a fixed coordinate system, which is fixed to the center of the hub, stationary relative to the nacelle, and does not rotate with the rotor. The reference coordinate system for the blade root out-of-plane bending moment is a rotating coordinate system, which is fixed to the rotor and rotates with the rotor. To obtain the rotor shimmy bending moment, it is necessary to transform the blade root out-of-plane bending moment in the rotating coordinate system into the fixed coordinate system.

[0066] The calculation formula of the wind rotor shimmying bending moment is as follows:

[0067]

[0068] In the above formula, M Q Indicates the rotor oscillation bending moment; M out1 represents the out-of-plane load on the root of the first blade; M out2 represents the out-of-plane load on the root of the second blade; M out3 represents the out-of-plane load on the root of the third blade; Indicates the azimuth angle measured by the first blade.

[0069] 3) Based on the rotor oscillation bending moment and the current average wind speed, the horizontal wind shear coefficient is calculated. When the horizontal wind shear coefficient exceeds a preset threshold, the current wind condition is identified as extreme horizontal wind shear.

[0070] When a wind turbine encounters extreme horizontal wind shear, the wind speed in the left and right half planes of the rotor are not equal, resulting in an imbalance in the thrust in the left and right half planes of the rotor. This generates a large rotor swing bending moment on the rotor. There is a clear linear relationship between the rotor swing bending moment and the horizontal wind shear coefficient. Therefore, the horizontal wind shear coefficient can be derived by using the rotor swing bending moment.

[0071] Considering the existence of yaw error to wind, part of the rotor shimmy bending moment is caused by yaw error. Therefore, in the calculation process of horizontal wind shear coefficient, the influence of yaw error needs to be deducted. The calculation formula of the horizontal wind shear coefficient is as follows:

[0072]

[0073] In the above formula, represents the horizontal wind shear coefficient; Represents the average wind speed, which is obtained by performing a sliding average filter on the measured wind speed; The proportional factor of the rotor oscillation bending moment to the horizontal wind shear coefficient is expressed by the average wind speed Obtained by looking up the table; The offset factor of the rotor oscillation bending moment to the horizontal wind shear coefficient is expressed by the average wind speed Obtained by table lookup; Φ yaw represents the average yaw error angle; Indicates the influence factor of yaw error to horizontal wind shear, through the average wind speed Obtained by looking up the table;

[0074] If the horizontal wind shear coefficient exceeds the normal wind shear coefficient and reaches a specific value, the current wind condition should be identified as extreme horizontal wind shear. Therefore, an extreme horizontal wind shear threshold is set. When the horizontal wind shear coefficient is detected to exceed the extreme horizontal wind shear threshold, the extreme horizontal wind shear status flag is set to true, otherwise it is set to false. The extreme horizontal wind shear status flag is defined as follows:

[0075]

[0076] In the above formula, Indicates the extreme horizontal wind shear status flag; Indicates the horizontal wind shear coefficient; H max Indicates the extreme horizontal wind shear threshold; if indicates conditional judgment, or indicates the logical operation "or", and other indicates other conditions.

[0077] 4) When the current wind condition is identified as extreme horizontal 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 rotor is offset by the wind rotor swing bending moment.

[0078] If the extreme horizontal wind shear status flag is true, it indicates that the current wind condition is extreme horizontal wind shear. At this time, the blades, hub, yaw bearing and tower top of the wind turbine will be subject to large loads. By superimposing additional independent pitch commands on the pitch angle of the wind turbine, additional bending moments can be generated on the wind rotor. When the additional bending moments are opposite to the wind rotor shimmy bending moments caused by extreme horizontal wind shear, they can offset the bending moment loads caused by extreme horizontal wind shear.

[0079] The calculation formula of the additional independent pitch command is as follows:

[0080]

[0081] In the above formula, Indicates the additional independent pitch command for the first blade; Indicates the additional independent pitch command for the second blade; Indicates the additional independent pitch command of the third blade; A H,shear Indicates the additional pitch command amplitude gain; represents the vertical wind shear coefficient; Indicates the azimuth angle measured by the first blade; ω r Indicates the measured speed of the wind rotor; τ indicates the time delay of the pitch system;

[0082] The pitch control output of the pitch controller is superimposed on the additional independent pitch control to obtain the final pitch control. The final pitch control command is transmitted to the pitch actuator, and the blade executes the pitch control with the final pitch control command as the target. The final pitch control command is defined as follows:

[0083]

[0084] In the above formula, Indicates the final pitch command of the first blade; Indicates the final pitch command for the second blade; Indicates the final pitch command for the third blade; Indicates the pitch command of the first blade output by the pitch controller; Indicates the pitch command of the second blade output by the pitch controller; Indicates the pitch command of the third blade output by the pitch controller; Indicates the additional independent pitch command for the first blade; Indicates the additional independent pitch command for the second blade; Indicates an additional independent pitch command for the third blade; Indicates the extreme horizontal wind shear status flag; if indicates conditional judgment, and other indicates other situations.

[0085] Example 2

[0086] This embodiment discloses an extreme horizontal wind shear identification and load reduction control system for a wind turbine, which is used to implement the extreme horizontal wind shear identification and load reduction control method for a wind turbine described in Example 1. Figure 1 As shown, the system includes the following functional modules:

[0087] The blade root out-of-plane bending moment acquisition module is used to obtain the blade root bending moments in two directions of the blade root, namely the blade root flapping bending moment and the blade root shimmy bending moment. According to the current measured pitch angle, the blade root out-of-plane bending moment is obtained through rotation transformation;

[0088] The wind rotor shimmy bending moment calculation module is used to obtain the current blade azimuth angle, perform coordinate transformation on the blade root out-of-plane bending moment, and calculate the wind rotor shimmy bending moment;

[0089] The extreme horizontal wind shear identification module calculates the horizontal wind shear coefficient based on the rotor oscillation bending moment and the current average wind speed. When the horizontal wind shear coefficient exceeds a preset threshold, the current wind condition is identified as extreme horizontal wind shear;

[0090] The extreme horizontal wind shear control module is used to calculate and output additional independent pitch control instructions when the current wind condition is identified as extreme horizontal wind shear. The instructions are superimposed on the pitch control instructions output by the pitch controller, and the additional bending moment generated on the wind rotor is reduced by the wind rotor swing bending moment.

[0091] Example 3

[0092] This embodiment discloses a storage medium storing a program. When the program is executed by a processor, the method for identifying and controlling extreme horizontal wind shear and load reduction of a wind turbine generator set described in Example 1 is implemented.

[0093] The storage medium in this embodiment can be a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), a USB flash drive, a mobile hard disk, or the like.

[0094] Example 4

[0095] This embodiment discloses a computing device, including a processor and a memory for storing a program executable by the processor. When the processor executes the program stored in the memory, the extreme horizontal wind shear identification and load reduction control method of the wind turbine described in Example 1 is implemented.

[0096] The computing device described in this embodiment may be a desktop computer, a laptop computer, a smart phone, a PDA handheld terminal, a tablet computer, a programmable logic controller (PLC), or other terminal devices with a processor function.

[0097] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for identifying and controlling extreme horizontal wind shear in a wind turbine generator system, characterized in that: Do the following: Obtain the blade root bending moments in two directions, namely the blade root flapping bending moment and the blade root shimmy bending moment. According to the current measured pitch angle, the blade root out-of-plane bending moment is obtained through rotation transformation. Obtain the current blade azimuth angle, perform coordinate transformation on the blade root out-of-plane bending moment, and calculate the rotor shimmy bending moment; The horizontal wind shear coefficient is calculated based on the rotor oscillation bending moment and the current average wind speed. When the horizontal wind shear coefficient exceeds the preset threshold, the current wind condition is identified as extreme horizontal wind shear. When the current wind condition is identified as extreme horizontal 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 rotor is reduced by the wind rotor shimmying bending moment. A load sensor needs to be installed at the root of each blade, which is called a blade root load sensor; The blade root load sensor can measure the bending moments in two directions of the blade root in real time, namely the blade root flapping moment and the blade root shimmy bending moment. The blade root flapping moment refers to the load generated by the bending deformation of the blade from the pressure side to the suction side, and the positive direction of the blade root flapping moment is defined as the pressure side being stretched while the suction side is compressed. The blade root shimmy bending moment refers to the load generated by the bending deformation of the blade from the trailing edge to the leading edge, and the positive direction of the blade root shimmy bending 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 caused by the bending deformation of the blade relative to the rotor plane in a direction perpendicular to the rotor plane; the positive direction of the blade root out-of-plane bending moment is defined as the direction in which the blade is perpendicular to the rotor plane and bends along the tail of the nacelle; since the wind turbine continuously changes the pitch during operation, in order to obtain the blade root out-of-plane bending moment, it is necessary to perform a rotational transformation on the blade root flapping bending moment and the blade root shimmy bending moment; The calculation formula of the blade root out-of-plane bending moment is as follows: In the above formula, M out1 represents the out-of-plane load on the root of the first blade; M out2 represents the out-of-plane load on the root of the second blade; M out3 represents the out-of-plane load on the root of the third blade; M flap1 represents the flapping bending moment of the first blade root measured by the sensor; M flap2 represents the flapping bending moment of the second blade root measured by the sensor; M flap3 represents the flapping bending moment of the third blade root measured by the sensor; M edge1 Indicates the root swing bending moment of the first blade measured by the sensor; M edge2 represents the root swing bending moment of the second blade measured by the sensor; M edge3 represents the root swing bending moment of the third blade measured by the sensor; represents the filtered average pitch angle; The calculation formula of the filtered average pitch angle is as follows: In the above formula, F β (s) represents the pitch angle filter, which includes a low-pass filter and a band-stop filter; Indicates the pitch angle of the first blade measured by the sensor; Indicates the pitch angle of the second blade measured by the sensor; Indicates the pitch angle of the third blade measured by the sensor; The current blade azimuth angle is acquired by the azimuth sensor; the rotor shimmy bending moment reflects the unbalanced force on the rotor plane in the horizontal direction. Due to the existence of horizontal wind shear, the wind speed on the left half plane of the rotor is not equal to the wind speed on the right half plane, resulting in an unbalanced thrust on the left half plane and the right half plane of the rotor, thus generating the rotor shimmy bending moment; The reference coordinate system for the rotor shimmy bending moment is a fixed coordinate system, which is fixed to the center of the hub, stationary relative to the nacelle, and does not rotate with the rotor. The reference coordinate system for the blade root out-of-plane bending moment is a rotating coordinate system, which is fixed to the rotor and rotates with the rotor. To obtain the rotor shimmy bending moment, it is necessary to transform the blade root out-of-plane bending moment in the rotating coordinate system into the fixed coordinate system. The calculation formula of the wind rotor shimmying bending moment is as follows: In the above formula, M Q Indicates the rotor oscillation bending moment; M out1 represents the out-of-plane load on the root of the first blade; M out2 represents the out-of-plane load on the root of the second blade; M out3 represents the out-of-plane load on the root of the third blade; Indicates the azimuth angle measured by the first blade; When a wind turbine encounters extreme horizontal wind shear, the wind speed in the left and right half planes of the rotor are not equal, resulting in an imbalance in the thrust in the left and right half planes of the rotor. This generates a large rotor swing bending moment on the rotor. There is a clear linear relationship between the rotor swing bending moment and the horizontal wind shear coefficient. Therefore, the horizontal wind shear coefficient can be derived by using the rotor swing bending moment. Considering the existence of yaw error to wind, part of the rotor shimmy bending moment is caused by yaw error. Therefore, in the calculation process of horizontal wind shear coefficient, the influence of yaw error needs to be deducted. The calculation formula of the horizontal wind shear coefficient is as follows: In the above formula, represents the horizontal wind shear coefficient; Represents the average wind speed, which is obtained by performing a sliding average filter on the measured wind speed; The proportional factor of the rotor oscillation bending moment to the horizontal wind shear coefficient is expressed by the average wind speed Obtained by looking up the table; The offset factor of the rotor oscillation bending moment to the horizontal wind shear coefficient is expressed by the average wind speed Obtained by table lookup; Φ yaw represents the average yaw error angle; Indicates the influence factor of yaw error to horizontal wind shear, through the average wind speed Obtained by looking up the table; If the horizontal wind shear coefficient exceeds the normal wind shear coefficient and reaches a specific value, the current wind condition should be identified as extreme horizontal wind shear. Therefore, an extreme horizontal wind shear threshold is set. When the horizontal wind shear coefficient is detected to exceed the extreme horizontal wind shear threshold, the extreme horizontal wind shear status flag is set to true, otherwise it is set to false. The extreme horizontal wind shear status flag is defined as follows: In the above formula, Indicates the extreme horizontal wind shear status flag; Indicates the horizontal wind shear coefficient; H max Indicates the extreme horizontal wind shear threshold; if indicates conditional judgment, or indicates the logical operation "or", and other indicates other conditions.

2. The method for identifying and controlling extreme horizontal wind shear of a wind turbine according to claim 1, wherein: If the extreme horizontal wind shear status flag is true, it indicates that the current wind condition is extreme horizontal wind shear. At this time, the blades, hub, yaw bearing and tower top of the wind turbine will be subject to large loads. By superimposing additional independent pitch commands on the pitch angle of the wind turbine, additional bending moments can be generated on the wind rotor. When the additional bending moments are opposite to the wind rotor shimmy bending moments caused by extreme horizontal wind shear, they can offset the bending moment loads caused by extreme horizontal wind shear. The calculation formula of the additional independent pitch command is as follows: In the above formula, Indicates the additional independent pitch command for the first blade; Indicates the additional independent pitch command for the second blade; Indicates the additional independent pitch command of the third blade; A H,shear Indicates the additional pitch command amplitude gain; Indicates the azimuth angle measured by the first blade; ω r Indicates the measured speed of the wind rotor; τ indicates the time delay of the pitch system; The pitch control output of the pitch controller is superimposed on the additional independent pitch control to obtain the final pitch control. The final pitch control command is transmitted to the pitch actuator, and the blade executes the pitch control with the final pitch control command as the target. The final pitch control command is defined as follows: In the above formula, Indicates the final pitch command of the first blade; Indicates the final pitch command for the second blade; Indicates the final pitch change command of the third blade; Indicates the pitch command of the first blade output by the pitch controller; Indicates the pitch command of the second blade output by the pitch controller; Indicates the pitch command of the third blade output by the pitch controller; Indicates the additional independent pitch command for the first blade; Indicates the additional independent pitch command for the second blade; Indicates an additional independent pitch command for the third blade; Indicates the extreme horizontal wind shear status flag; if indicates conditional judgment, and other indicates other situations.

3. Extreme horizontal wind shear identification and load reduction control system for wind turbines, characterized by: A method for realizing extreme horizontal wind shear identification and load reduction control of a wind turbine generator system according to claim 1 or 2, comprising: The blade root out-of-plane bending moment acquisition module is used to obtain the blade root bending moments in two directions of the blade root, namely the blade root flapping bending moment and the blade root shimmy bending moment. According to the current measured pitch angle, the blade root out-of-plane bending moment is obtained through rotation transformation; The wind rotor shimmy bending moment calculation module is used to obtain the current blade azimuth angle, perform coordinate transformation on the blade root out-of-plane bending moment, and calculate the wind rotor shimmy bending moment; The extreme horizontal wind shear identification module calculates the horizontal wind shear coefficient based on the rotor oscillation bending moment and the current average wind speed. When the horizontal wind shear coefficient exceeds a preset threshold, the current wind condition is identified as extreme horizontal wind shear; The extreme horizontal wind shear control module is used to calculate and output additional independent pitch control instructions when the current wind condition is identified as extreme horizontal wind shear. The instructions are superimposed on the pitch control instructions output by the pitch controller, and the additional bending moment generated on the wind rotor is reduced by the wind rotor swing bending moment.

4. A storage medium storing a program, characterized in that: When the program is executed by a processor, the extreme horizontal wind shear identification and load reduction control method of the wind turbine set according to claim 1 or 2 is implemented.

5. A computing device comprising a processor and a memory for storing a program executable by the processor, characterized in that When the processor executes the program stored in the memory, the extreme horizontal wind shear identification and load reduction control method of the wind turbine set according to claim 1 or 2 is implemented.

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