A wind turbine wind shear condition identification method and system

Abstract

The application discloses a wind shear working condition recognition method and system for a wind generating set, the method is that the test data of the wind generating set is obtained through the independent variable pitch equipment of the wind generating set, the bending moment of the wind generating set in the static load coordinate system is calculated, the change rate time sequence is calculated according to the bending moment, the direction and the duration of the change rate in the change rate time sequence are compared with the preset threshold condition, if the direction and the duration of the change rate in the change rate time sequence meet the threshold condition, the wind generating set is recognized to be in the wind shear working condition; the test data can be obtained based on the independent variable pitch equipment, the difference between the wind shear working condition and the normal power generation working condition can be recognized, the load optimization and the clearance optimization of the wind shear working condition can be realized, the power generation capacity of the normal power generation working condition is not affected, and the loss of the power generation capacity of the wind generating set is prevented.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wind shear working condition recognition of wind turbine generator system, and in particular to a wind shear working condition recognition method and system of wind turbine generator system. BACKGROUND

[0002] Wind shear is an atmospheric phenomenon in which the wind speed and direction change suddenly in the horizontal or vertical direction. Domestic onshore wind farms are mostly erected in mountainous and hilly environments, and offshore wind farms mostly have "sea-land wind". The wind shear of the wind farm has the characteristics of short duration, small scale and high intensity, which can cause great interference to the operation of the wind turbine generator. Therefore, the "wind shear working condition" of the large wind turbine generator has gradually become a key working condition restricting the load and clearance of the wind turbine.

[0003] In the prior art, laser radar is often used for wind shear detection, but its cost is high and its application range is narrow; or as disclosed in Chinese patent application CN202110725377.3, the wind speed and direction of the environment where the wind turbine generator is located are determined based on wind speed and wind direction sampling data, and the wind turbine generator is determined to be in a wind shear working condition according to the similarity greater than a preset threshold, but it cannot simply and effectively distinguish the normal power generation working condition of the wind turbine generator from the wind shear working condition. SUMMARY

[0004] The present application aims to overcome the shortcomings of the prior art and provides a wind shear working condition recognition method and system of wind turbine generator, which converts the test data of the independent variable pitch device through the stationary hub coordinate system, obtains the bending moment of the stationary hub coordinate system, and then recognizes the wind shear working condition through the bending moment change rate and effectively distinguishes it from the normal power generation working condition.

[0005] The purpose of the present application is achieved by the following technical scheme: a wind shear working condition recognition method of wind turbine generator, which obtains test data of the wind turbine generator through an independent variable pitch device of the wind turbine generator, calculates the bending moment of the wind turbine generator in the stationary load coordinate system, compares the direction and duration of the change rate in the change rate time sequence with the preset threshold condition, and if the direction and duration of the change rate in the change rate time sequence meet the threshold condition, the wind turbine generator is recognized to be in a wind shear working condition.

[0006] Further, the method comprises the following steps:

[0007] S1, obtaining test data of the wind turbine generator through an independent variable pitch device of the wind turbine generator;

[0008] S2, calculating the stationary load coordinate system bending moment SH_My and SH_Mz of the wind turbine generator according to the test data;

[0009] S3, obtaining normal power generation condition load, wind shear condition load, SH_My change rate time sequence and SH_Mz change rate time sequence, and then setting the threshold condition for judging the wind shear condition as SH_My change rate being negative and the duration being at least 0.8 seconds, and SH_Mz change rate being negative and the duration being at least 0.8 seconds;

[0010] S4, comparing the direction and duration of the change rates of the bending moments SH_My and SH_Mz with the threshold condition described in step S3, if the direction and duration of the time sequence change rate do not meet the threshold condition, it is considered that the wind turbine generator set is not in the wind shear condition, if the direction and duration of the time sequence change rate meet the threshold condition, it is considered that the wind turbine generator set is in the wind shear condition.

[0011] Further, the step S1 comprises:

[0012] The test data includes first blade root bending moment BR_My1, second blade root bending moment BR_My2, third blade root bending moment BR_My3, wind wheel azimuth angle β, blade theoretical installation cone angle α, and theoretical static bending moments My0 and Mz0 of the static hub coordinate system under the condition of only gravity.

[0013] Further, the step S2 comprises:

[0014] 1) If the wind turbine generator set impeller rotates counterclockwise, that is, the rotation order of the blades is first blade, third blade, second blade, the formula for calculating the static load coordinate system bending moments SH_My and SH_Mz of the wind turbine generator set is as follows:

[0015] SH_My = BR_My1*cosβ + BR_My3*cos(β-120) + BR_My2*cos(β-240) + My0;

[0016] SH_Mz = (BR_My1*sinβ + BR_My3*sin(β-120) + BR_My2*sin(β-240))*cos(α);

[0017] 2) If the wind turbine generator set impeller rotates clockwise, that is, the rotation order of the blades is first blade, second blade, third blade, the formula for calculating the static load coordinate system bending moments SH_My and SH_Mz of the wind turbine generator set is as follows:

[0018] SH_My = BR_My1*cosβ + BR_My2*cos(β-120) + BR_My3*cos(β-240) + My0;

[0019] SH_Mz = (BR_My1 * sin β + BR_My2 * sin (β - 120) + BR_My3 * sin (β - 240)) * cos (α);

[0020] wherein BR_My1 is the first blade root bending moment, BR_My2 is the second blade root bending moment, BR_My3 is the third blade root bending moment, β is the wind direction angle, α is the theoretical installation cone angle of the blade, My0 and Mz0 are the theoretical static bending moments of the static hub coordinate system under the action of gravity only.

[0021] Further, the step S3 comprises:

[0022] S3.1, obtaining the blade root load of the wind turbine under normal power generation conditions and wind shear conditions, calculating the blade root load under the two conditions, and obtaining SH_My and SH_Mz time series under the static load coordinate system of the two conditions, wherein the SH_My time series of the wind shear condition is within the maximum and minimum value range of the SH_My time series of the normal power generation condition, and the SH_Mz time series of the wind shear condition is within the maximum and minimum value range of the SH_Mz time series of the normal power generation condition, then it is judged that the wind shear condition cannot be identified only according to the blade root load;

[0023] S3.2, according to the SH_My and SH_Mz time series of the wind turbine under normal power generation conditions and wind shear conditions, respectively, the time is derived, and the SH_My and SH_Mz time series change rate under normal power generation conditions and wind shear conditions is obtained, wherein the SH_My time series change rate of the wind shear condition is within the maximum and minimum value range of the SH_My time series change rate of the normal power generation condition, and the SH_Mz time series change rate of the wind shear condition is within the maximum and minimum value range of the SH_Mz time series change rate of the normal power generation condition, then it is judged that the wind shear condition cannot be identified only according to the SH_My and SH_Mz time series change rate;

[0024] S3.3, when the SH_My and SH_Mz time series change rate under normal power generation conditions and wind shear conditions is negative and the duration of the negative change rate is not less than 0.8s, the SH_My time series change rate of the wind shear condition is not covered by the maximum and minimum value of the SH_My time series change rate of the normal power generation condition, and the SH_Mz time series change rate of the wind shear condition is not covered by the maximum and minimum value of the SH_Mz time series change rate of the normal power generation condition, then the threshold condition is set as the SH_My and SH_Mz time series change rate is negative and the duration is not less than 0.8s.

[0025] A wind turbine wind shear condition identification system for implementing the above-mentioned wind turbine wind shear condition identification method, comprising:

[0026] An independent variable pitch device is used for testing a wind turbine generator system;

[0027] A test data acquisition module acquires test data of the wind turbine generator system through testing of the independent variable pitch device of the wind turbine generator system;

[0028] A static load coordinate system bending moment calculation module calculates static load coordinate system bending moments SH_My and SH_Mz of the wind turbine generator system according to the test data;

[0029] A threshold condition setting module acquires normal power generation working condition load, wind shear working condition load, SH_My change rate time sequence and SH_Mz change rate time sequence, and further sets threshold conditions for judging the wind shear working condition;

[0030] A wind shear working condition identification module compares the direction and duration of the change rate of the bending moments SH_My and SH_Mz with the threshold conditions of the threshold condition setting module, if the direction and duration of the time sequence change rate do not meet the threshold conditions, it is considered that the wind turbine generator system is not in the wind shear working condition, if the direction and duration of the time sequence change rate meet the threshold conditions, it is considered that the wind turbine generator system is in the wind shear working condition.

[0031] Further, the test data includes first blade root bending moment BR_My1, second blade root bending moment BR_My2, third blade root bending moment BR_My3, wind wheel azimuth angle β, blade theoretical installation cone angle α, and theoretical static bending moments My0 and Mz0 of the static hub coordinate system under the condition of only gravity.

[0032] Further, the static load coordinate system bending moment calculation module includes:

[0033] 1) If the wind turbine generator impeller rotates counterclockwise, that is, the rotation sequence of the blades is first blade, third blade, second blade in turn, the formula for calculating the static load coordinate system bending moments SH_My and SH_Mz of the wind turbine generator is as follows:

[0034] SH_My = BR_My1*cosβ + BR_My3*cos(β-120) + BR_My2*cos(β-240) + My0;

[0035] SH_Mz = (BR_My1*sinβ + BR_My3*sin(β-120) + BR_My2*sin(β-240))*cos(α);

[0036] 2) If the wind turbine generator impeller rotates clockwise, that is, the rotation sequence of the blades is first blade, second blade, third blade in turn, the formula for calculating the static load coordinate system bending moments SH_My and SH_Mz of the wind turbine generator is as follows:

[0037] SH_My = BR_My1*cosβ + BR_My2*cos(β-120) + BR_My3*cos(β-240) + My0;

[0038] SH_Mz = (BR_My1*sinβ + BR_My2*sin(β-120) + BR_My3*sin(β-240))*cos(α);

[0039] wherein BR_My1 is a first blade root bending moment, BR_My2 is a second blade root bending moment, BR_My3 is a third blade root bending moment, β is a wind wheel azimuth angle, α is a blade theoretical installation cone angle, My0 and Mz0 are theoretical static bending moments of a static hub coordinate system under the action of gravity only.

[0040] Further, the threshold condition setting module comprises:

[0041] obtaining blade root loads of the wind turbine under normal power generation conditions and wind shear conditions, calculating the blade root loads under the two conditions, and obtaining SH_My and SH_Mz time series under a static load coordinate system of the two conditions, wherein the SH_My time series of the wind shear condition is within the maximum and minimum value range of the SH_My time series of the normal power generation condition, and the SH_Mz time series of the wind shear condition is within the maximum and minimum value range of the SH_Mz time series of the normal power generation condition, and it is judged that the wind shear condition cannot be identified only according to the blade root load;

[0042] According to the SH_My and SH_Mz time series of the wind turbine under normal power generation conditions and wind shear conditions, the time is differentiated respectively, and the SH_My and SH_Mz time series change rates under the normal power generation conditions and the wind shear conditions are obtained, wherein the SH_My time series change rate of the wind shear condition is within the maximum and minimum value range of the SH_My time series change rate of the normal power generation condition, and the SH_Mz time series change rate of the wind shear condition is within the maximum and minimum value range of the SH_Mz time series change rate of the normal power generation condition, and it is judged that the wind shear condition cannot be identified only according to the SH_My and SH_Mz time series change rates;

[0043] When the SH_My and SH_Mz time series change rates under the normal power generation conditions and the wind shear conditions are negative values and the duration of the negative change rates is not less than 0.8s, the SH_My time series change rate of the wind shear condition is not covered by the maximum and minimum values of the SH_My time series change rate of the normal power generation condition, and the SH_Mz time series change rate of the wind shear condition is not covered by the maximum and minimum values of the SH_Mz time series change rate of the normal power generation condition, it is judged that the threshold condition is set as the SH_My and SH_Mz time series change rates being negative values and the duration being not less than 0.8s.

[0044] Further, the wind shear working condition recognition module comprises:

[0045] The direction and duration of the change rate of the bending moment SH_My and SH_Mz are compared with the threshold condition of the threshold condition setting module, if the direction and duration of the time sequence change rate do not meet the condition that the time sequence change rate is negative and the duration is not less than 0.8s, it is considered that the wind turbine is not in the wind shear working condition, if the direction and duration of the time sequence change rate meet the condition that the time sequence change rate is negative and the duration is not less than 0.8s, it is considered that the wind turbine is in the wind shear working condition.

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

[0047] (1) The present application can obtain test data based on independent variable pitch equipment, identify the difference between wind shear working condition and normal power generation working condition, realize load optimization and clearance optimization of wind shear working condition, and will not affect the power generation of normal power generation working condition, preventing the loss of power generation of wind turbine.

[0048] (2) The present application can realize the detection of wind shear working condition with the test data of existing independent variable pitch equipment, which is low in cost and wide in applicability. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 It is a schematic view of the stationary hub coordinate system of the wind turbine.

[0050] Figure 2 It is a time sequence diagram of the bending moment SH_My of the stationary hub coordinate system.

[0051] Figure 3 It is a time sequence diagram of the change rate of the bending moment SH_My of the stationary hub coordinate system.

[0052] Figure 4 It is a schematic view of selecting and recognizing wind shear working condition based on threshold condition in Figure 3 DETAILED DESCRIPTION

[0053] The present application will be further described below in combination with specific embodiments.

[0054] Embodiment 1

[0055] The wind shear working condition recognition method of the wind turbine provided in the embodiment is obtained by the independent variable pitch equipment of the wind turbine, the test data of the wind turbine is obtained, the bending moment of the wind turbine in the stationary load coordinate system is calculated, the direction and duration of the change rate in the change rate time sequence are compared with the preset threshold condition, if the direction and duration of the change rate in the change rate time sequence meet the threshold condition, it is considered that the wind turbine is in the wind shear working condition, comprising the following steps:​

[0056] S1, obtaining test data of the wind turbine generator set by the blade root load independent variable pitch device of the wind turbine generator set; the test data includes a first blade root bending moment BR_My1, a second blade root bending moment BR_My2, a third blade root bending moment BR_My3, a wind wheel azimuth angle β, a blade theoretical installation cone angle α, and a theoretical static bending moment My0 and Mz0 of a static hub coordinate system under the action of gravity only.

[0057] S2, referring to Figure 1 the figure, it is wind turbine generator set static hub coordinate system schematic diagram, wherein: XN is the axis along the rotor axis direction, ZN is the axis perpendicular to XN direction, YN is the horizontal axis and forms right hand coordinate system with XN axis and ZN axis, F XN , F YN , F ZN Along XN, YN and ZN axis tension respectively, M XN , M YN And M ZN It is the bending moment around the positive direction of XN, YN and ZN axis, and the positive direction around XN, YN and ZN axis is clockwise.

[0058] According to the test data, the YN axis and ZN axis bending moment SH_My (M YN ) and SH_Mz (M ZN ) of the wind turbine generator set in the static load coordinate system are calculated.

[0059] 1) if the wind turbine impeller rotates counterclockwise, that is, the rotation sequence of the blade is first blade, third blade, second blade, then the formula for calculating the static load coordinate system bending moment SH_My and SH_Mz of the wind turbine generator set is as follows:

[0060] SH_My=BR_My1*cosβ+BR_My3*cos(β-120)+BR_My2*cos(β-240)+My0;

[0061] SH_Mz=(BR_My1*sinβ+BR_My3*sin(β-120)+BR_My2*sin(β-240))*cos(α);

[0062] 2) if the wind turbine impeller rotates clockwise, that is, the rotation sequence of the blade is first blade, second blade, third blade, then the formula for calculating the static load coordinate system bending moment SH_My and SH_Mz of the wind turbine generator set is as follows:

[0063]

[0064] S3, obtain normal power generation condition load, wind shear condition load, SH_My change rate time sequence, and then set the threshold condition for judging the wind shear condition as SH_My change rate being negative and the duration being at least 0.8 seconds, including:

[0065] S3.1, obtain the blade root load of the wind turbine generator set under normal power generation condition and wind shear condition, calculate the blade root load under the two conditions, obtain the SH_My time sequence under the two conditions in the static load coordinate system, see Figure 2 , wherein the SH_My time sequence of the wind shear condition is within the maximum and minimum value range of the SH_My time sequence of the normal power generation condition, it is judged that the wind shear condition cannot be identified according to the blade root load alone;

[0066] S3.2, according to SH_My of the wind turbine generator set under normal power generation condition and wind shear condition, respectively, the derivative of time is obtained, the SH_My time sequence change rate under normal power generation condition and wind shear condition is obtained, see Figure 3 , wherein the SH_My time sequence change rate of the wind shear condition is within the maximum and minimum value range of the SH_My time sequence change rate of the normal power generation condition, it is judged that the wind shear condition cannot be identified according to the SH_My time sequence change rate alone;

[0067] S3.3, in order to make the SH_My time sequence change rate of the wind shear condition not be covered by the maximum and minimum value of the SH_My time sequence change rate of the normal power generation condition, it is necessary to superimpose the direction and time threshold of the time sequence change rate two conditions, because of the closed loop control of the wind turbine generator set control logic, that is, receiving signal, logical judgment and then delivering control instruction needs about 120ms, the judgment threshold condition is set as SH_My time sequence change rate being negative and the duration being not less than 0.8s; see Figure 4 , the SH_My time sequence change rate at A in the figure is negative and the duration is 5s, which meets the threshold condition, can make the SH_My time sequence change rate of the wind shear condition not be covered by the maximum and minimum value of the SH_My time sequence change rate of the normal power generation condition, and can be used to identify the wind shear condition.

[0068] In the static hub coordinate system, SH_Mz load and SH_My load belong to the axisymmetric bending moment of X axis, so the related strategy of identifying wind shear condition through SH_Mz load is consistent with SH_My mode.

[0069] S4, compare the direction and duration of the change rate of the bending moment SH_My and SH_Mz with the threshold condition described in step S3, if the direction and duration of the time sequence change rate do not meet the threshold condition, it is considered that the wind turbine generator set is not in the wind shear condition, if the direction and duration of the time sequence change rate meet the threshold condition, it is considered that the wind turbine generator set is in the wind shear condition.

[0070] Embodiment 2

[0071] The embodiment discloses a wind shear working condition recognition system of a wind generating set, which is used for implementing the wind shear working condition recognition method of the wind generating set in Embodiment 1, and comprises:

[0072] An independent variable pitch device is used for testing the wind generating set.

[0073] A test data acquisition module acquires test data of the wind generating set through testing of the independent variable pitch device of the wind generating set, wherein the test data comprises a first blade root bending moment BR_My1, a second blade root bending moment BR_My2, a third blade root bending moment BR_My3, a wind wheel azimuth angle β, a blade theoretical installation cone angle α, and a theoretical static bending moment My0 and Mz0 of a static hub coordinate system in a gravity-only state.

[0074] A static load coordinate system bending moment calculation module calculates static load coordinate system bending moments SH_My and SH_Mz of the wind generating set according to the test data, and the calculation module comprises:

[0075] 1) If the impeller of the wind generating set rotates counterclockwise, that is, the rotation sequence of the blades is the first blade, the third blade, and the second blade in turn, the formula for calculating the static load coordinate system bending moments SH_My and SH_Mz of the wind generating set is as follows:

[0076] SH_My = BR_My1*cosβ + BR_My3*cos(β-120) + BR_My2*cos(β-240) + My0;

[0077] SH_Mz = (BR_My1*sinβ + BR_My3*sin(β-120) + BR_My2*sin(β-240))*cos(α);

[0078] 2) If the impeller of the wind generating set rotates clockwise, that is, the rotation sequence of the blades is the first blade, the second blade, and the third blade in turn, the formula for calculating the static load coordinate system bending moments SH_My and SH_Mz of the wind generating set is as follows:

[0079]

[0080] A threshold condition setting module acquires normal power generation working condition loads, wind shear working condition loads, SH_My change rate time sequences, and SH_Mz change rate time sequences, and then sets threshold conditions for judging the wind shear working condition, and the threshold condition setting module comprises:

[0081] Obtaining the blade root load of the wind turbine under normal power generation conditions and wind shear conditions, calculating the blade root load under the two conditions, and obtaining SH_My and SH_Mz time series under the static load coordinate system of the two conditions, wherein the SH_My time series of the wind shear condition is within the maximum and minimum value range of the SH_My time series of the normal power generation condition, and the SH_Mz time series of the wind shear condition is within the maximum and minimum value range of the SH_Mz time series of the normal power generation condition, then it is judged that the wind shear condition cannot be identified only according to the blade root load.

[0082] According to the SH_My and SH_Mz time series of the wind turbine under normal power generation conditions and wind shear conditions, the time is differentiated respectively to obtain the SH_My and SH_Mz time series change rate under normal power generation conditions and wind shear conditions, wherein the SH_My time series change rate of the wind shear condition is within the maximum and minimum value range of the SH_My time series change rate of the normal power generation condition, and the SH_Mz time series change rate of the wind shear condition is within the maximum and minimum value range of the SH_Mz time series change rate of the normal power generation condition, then it is judged that the wind shear condition cannot be identified only according to the SH_My and SH_Mz time series change rate.

[0083] When the SH_My and SH_Mz time series change rates under normal power generation conditions and wind shear conditions are negative values and the duration of the negative change rate is not less than 0.8s, the SH_My time series change rate of the wind shear condition is not covered by the maximum and minimum value of the SH_My time series change rate of the normal power generation condition, and the SH_Mz time series change rate of the wind shear condition is not covered by the maximum and minimum value of the SH_Mz time series change rate of the normal power generation condition, then the threshold condition is set as the SH_My and SH_Mz time series change rate being negative and the duration being not less than 0.8s.

[0084] The wind shear condition identification module compares the direction and duration of the change rate of the bending moment SH_My and SH_Mz with the threshold condition of the threshold condition setting module. If the direction and duration of the time series change rate do not meet the condition that the time series change rate is negative and the duration is not less than 0.8s, it is considered that the wind turbine is not in the wind shear condition. If the direction and duration of the time series change rate meet the condition that the time series change rate is negative and the duration is not less than 0.8s, it is considered that the wind turbine is in the wind shear condition.

[0085] Embodiment 3

[0086] The embodiment discloses a non-transitory computer readable medium storing instructions which, when executed by a processor, perform the steps of the wind turbine wind shear condition identification method according to embodiment 1.

[0087] The non-transitory computer readable medium in the embodiment can be a disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), a U disk, a mobile hard disk, and the like.

[0088] Embodiment 4

[0089] The embodiment discloses a computing device, comprising a processor and a memory for storing a processor-executable program, and the processor implements the wind shear working condition identification method of the wind turbine generator set according to the program stored in the memory.

[0090] The computing device in the embodiment can be a desktop computer, a notebook computer, a smart phone, a PDA handheld terminal, a tablet computer, a programmable logic controller (PLC), or other terminal devices with a processor function.

[0091] The above-mentioned embodiments are only the preferred embodiments of the present application, and are not intended to limit the scope of the present application. Any changes made according to the shape and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A method for identifying wind shear conditions of a wind turbine generator set, characterized by: The method is to obtain test data of the wind turbine generator set through an independent pitch control device of the wind turbine generator set, calculate the bending moment of the wind turbine generator set in a static load coordinate system, calculate its change rate time series based on the bending moment, compare the direction and duration of the change rate in the change rate time series with a preset threshold condition, and identify the wind turbine generator set as being in a wind shear working condition if the direction and duration of the change rate in the change rate time series meet the threshold condition; The method comprises the following steps: S1. Obtain test data of the wind turbine generator set through the independent pitch control device of the wind turbine generator set; S2. Calculate the static load coordinate system bending moments SH_My and SH_Mz of the wind turbine generator set based on the test data, including: 1) If the impeller of the wind turbine generator set rotates counterclockwise, that is, the rotation order of the blades is the first blade, the third blade, and the second blade, the formula for calculating the static load coordinate system bending moments SH_My and SH_Mz of the wind turbine generator set is as follows: SH_My= BR_My1*cosβ+ BR_My3*cos(β-120)+ BR_My2* cos(β-240)+ My0; SH_Mz=( BR_My1*sinβ+ BR_My3*sin(β-120)+ BR_My2* sin(β-240))*cos(α); 2) If the impeller of the wind turbine generator set rotates clockwise, that is, the rotation order of the blades is the first blade, the second blade, and the third blade, the formula for calculating the static load coordinate system bending moments SH_My and SH_Mz of the wind turbine generator set is as follows: SH_My= BR_My1*cosβ+ BR_My2*cos(β-120)+ BR_My3* cos(β-240)+ My0; SH_Mz=( BR_My1*sinβ+ BR_My2*sin(β-120)+ BR_My3* sin(β-240))*cos(α); Wherein, BR_My1 is the first blade root bending moment, BR_My2 is the second blade root bending moment, BR_My3 is the third blade root bending moment, β is the rotor azimuth angle, α is the theoretical blade installation cone angle, and My0 is the theoretical static bending moment of the stationary hub coordinate system under gravity only. S3. Obtain the normal power generation load, the wind shear load, the SH_My change rate time series, and the SH_Mz change rate time series, and then set the threshold conditions for judging the wind shear condition as the SH_My change rate is negative and lasts for at least 0.8 seconds, and the SH_Mz change rate is negative and lasts for at least 0.8 seconds, including: S3.

1. Obtain the blade root loads of the wind turbine generator set under normal power generation conditions and wind shear conditions, calculate the blade root loads for the two conditions, and obtain the SH_My and SH_Mz time series for the two conditions in the static load coordinate system. If the SH_My time series for the wind shear condition is within the maximum and minimum range of the SH_My time series for the normal power generation condition, and the SH_Mz time series for the wind shear condition is within the maximum and minimum range of the SH_Mz time series for the normal power generation condition, then determine that the wind shear condition cannot be identified based solely on the blade root loads; S3.

2. Based on the SH_My and SH_Mz time series of the wind turbine generator set under normal power generation conditions and wind shear conditions, respectively, take the time derivative to obtain the time series change rates of SH_My and SH_Mz under normal power generation conditions and wind shear conditions. If the time series change rate of SH_My under the wind shear condition is within the maximum and minimum value range of the time series change rate of SH_My under the normal power generation condition, and the time series change rate of SH_Mz under the wind shear condition is within the maximum and minimum value range of the time series change rate of SH_Mz under the normal power generation condition, then it is determined that the wind shear condition cannot be identified based solely on the time series change rates of SH_My and SH_Mz. S3.

3. When the time-series change rates of SH_My and SH_Mz under normal power generation conditions and wind shear conditions are negative, and the duration of the negative change rates of both is not less than 0.8s, the time-series change rate of SH_My under wind shear conditions is not covered by the maximum and minimum values ​​of the time-series change rate of SH_My under normal power generation conditions, and the time-series change rate of SH_Mz under wind shear conditions is not covered by the maximum and minimum values ​​of the time-series change rate of SH_Mz under normal power generation conditions, then the judgment threshold condition is set to that the time-series change rates of SH_My and SH_Mz are negative and the duration is not less than 0.8s; S4. Compare the direction and duration of the rate of change of the bending moments SH_My and SH_Mz with the threshold conditions described in step S3. If the direction and duration of the time series change rate do not meet the threshold conditions, it is considered that the wind turbine generator set is not in a wind shear condition. If the direction and duration of the time series change rate meet the threshold conditions, it is considered that the wind turbine generator set is in a wind shear condition.

2. A method for identifying wind shear conditions of a wind turbine generator set according to claim 1, characterized in that: The step S1 comprises: The test data include the first blade root bending moment BR_My1, the second blade root bending moment BR_My2, the third blade root bending moment BR_My3, the wind wheel azimuth angle β, the blade theoretical installation cone angle α and the theoretical static bending moment My0 of the stationary hub coordinate system under only gravity.

3. A wind turbine generator set wind shear condition identification system, characterized in that: A method for identifying wind shear conditions of a wind turbine generator set according to any one of claims 1 to 2, comprising: Independent pitch control equipment for testing wind turbines; A test data acquisition module, which acquires test data of the wind turbine generator set by testing the independent pitch control device of the wind turbine generator set; The static load coordinate system bending moment calculation module calculates the static load coordinate system bending moments SH_My and SH_Mz of the wind turbine generator set based on the test data; The threshold condition setting module obtains the normal power generation load, wind shear load, SH_My change rate time series and SH_Mz change rate time series, and then sets the threshold conditions for judging the wind shear condition; The wind shear condition identification module compares the direction and duration of the change rate of the bending moments SH_My and SH_Mz with the threshold conditions of the threshold condition setting module. If the direction and duration of the temporal change rate do not meet the threshold conditions, it is considered that the wind turbine is not in a wind shear condition. If the direction and duration of the temporal change rate meet the threshold conditions, it is considered that the wind turbine is in a wind shear condition.

4. A wind turbine generator set wind shear condition identification system according to claim 3, characterized in that: The test data include the first blade root bending moment BR_My1, the second blade root bending moment BR_My2, the third blade root bending moment BR_My3, the wind wheel azimuth angle β, the blade theoretical installation cone angle α and the theoretical static bending moment My0 of the stationary hub coordinate system under only gravity.

5. The wind turbine generator set wind shear condition identification system according to claim 3, characterized in that: The static load coordinate system bending moment calculation module includes: 1) If the impeller of the wind turbine generator set rotates counterclockwise, that is, the rotation order of the blades is the first blade, the third blade, and the second blade, the formula for calculating the static load coordinate system bending moments SH_My and SH_Mz of the wind turbine generator set is as follows: SH_My= BR_My1*cosβ+ BR_My3*cos(β-120)+ BR_My2* cos(β-240)+ My0; SH_Mz=( BR_My1*sinβ+ BR_My3*sin(β-120)+ BR_My2* sin(β-240))*cos(α); 2) If the impeller of the wind turbine generator set rotates clockwise, that is, the rotation order of the blades is the first blade, the second blade, and the third blade, the formula for calculating the static load coordinate system bending moments SH_My and SH_Mz of the wind turbine generator set is as follows: SH_My= BR_My1*cosβ+ BR_My2*cos(β-120)+ BR_My3* cos(β-240)+ My0; SH_Mz=( BR_My1*sinβ+ BR_My2*sin(β-120)+ BR_My3* sin(β-240))*cos(α); Among them, BR_My1 is the first blade root bending moment, BR_My2 is the second blade root bending moment, BR_My3 is the third blade root bending moment, β is the wind rotor azimuth angle, α is the theoretical installation cone angle of the blade, and My0 is the theoretical static bending moment of the stationary hub coordinate system under the gravity only state.

6. A wind turbine generator set wind shear condition identification system according to claim 3, characterized in that: The threshold condition setting module includes: Obtain the blade root loads of the wind turbine generator set under normal power generation conditions and wind shear conditions, calculate the blade root loads of the two conditions, and obtain the SH_My and SH_Mz time series of the two conditions in the static load coordinate system. If the SH_My time series of the wind shear condition is within the maximum and minimum value range of the SH_My time series of the normal power generation condition, and the SH_Mz time series of the wind shear condition is within the maximum and minimum value range of the SH_Mz time series of the normal power generation condition, then it is determined that the wind shear condition cannot be identified based on the blade root load alone; According to the SH_My and SH_Mz time series of the wind turbine generator set under normal power generation conditions and wind shear conditions, the time derivative is respectively taken to obtain the time series change rates of SH_My and SH_Mz under normal power generation conditions and wind shear conditions. Among them, the SH_My time series change rate under the wind shear condition is within the maximum and minimum value range of the SH_My time series change rate under the normal power generation condition, and the SH_Mz time series change rate under the wind shear condition is within the maximum and minimum value range of the SH_Mz time series change rate under the normal power generation condition. It is judged that the wind shear condition cannot be identified based on the SH_My and SH_Mz time series change rates alone; When the timing change rates of SH_My and SH_Mz under normal power generation conditions and wind shear conditions are negative and the duration of the negative change rates of both is not less than 0.8s, the timing change rate of SH_My under wind shear conditions is not covered by the maximum and minimum values ​​of the timing change rate of SH_My under normal power generation conditions, and the timing change rate of SH_Mz under wind shear conditions is not covered by the maximum and minimum values ​​of the timing change rate of SH_Mz under normal power generation conditions, then the judgment threshold condition is set to that the timing change rates of SH_My and SH_Mz are negative and the duration is not less than 0.8s.

7. A wind turbine generator set wind shear condition identification system according to claim 3, characterized in that: The wind shear condition identification module includes: The direction and duration of the change rate of the bending moments SH_My and SH_Mz are compared with the threshold conditions of the threshold condition setting module. If the direction and duration of the time series change rate do not meet the requirements that the time series change rate is a negative value and the duration is not less than 0.8s, the wind turbine is considered not to be in a wind shear condition. If the direction and duration of the time series change rate meet the requirements that the time series change rate is a negative value and the duration is not less than 0.8s, the wind turbine is considered to be in a wind shear condition.

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