Wind turbine generator emergency shutdown working condition load optimization method and system

Abstract

The invention discloses a load optimization method and system for an emergency shutdown condition of a wind turbine generator, and the method comprises the steps: analyzing the relation between a sectional type propeller return rate and a wind energy utilization rate under the emergency shutdown condition of the wind turbine generator, and defining a novel sectional type propeller return curve based on the wind energy utilization rate Cp; the HubMyz loads or the TowerTopMxy loads of the multiple sectional type paddle return curves are simulated and evaluated, the sectional type paddle return curve corresponding to the minimum load is selected as the optimal sectional type paddle return curve, and then the optimal sectional type paddle return curve is applied to a wind turbine generator to achieve load optimization under the emergency shutdown working condition; according to the method, the ultimate bending moment loads of the wind wheel, the transmission chain, the yaw system and the tower top can be greatly reduced, meanwhile, load reduction and cost reduction of large components of the wind turbine generator are achieved based on variable pitch logic, no new hardware needs to be additionally arranged, the application range is wide, and economical efficiency is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbine load optimization, and in particular to a method and system for optimizing the load of a wind turbine under emergency shutdown conditions. Background Art

[0002] Wind turbines are power machines that convert wind energy into electrical energy. They capture wind energy through the rotation of the wind rotor and connect to the generator through a mechanical transmission device to achieve the function of converting kinetic energy into electrical energy. In recent years, with the rapid development of the wind power industry, the unit capacity and wind rotor diameter of wind turbines have gradually increased, the component loads of wind turbines have increased year by year, and the weight of wind turbine components has gradually increased. Therefore, if efficient load optimization is achieved, it is a key factor to ensure the structural safety and cost reduction of wind turbines.

[0003] With the development of wind turbines towards larger and lighter sizes, the ultimate load of wind turbines is gradually increasing. Based on the IEC61400-1 standard, the design phase of wind turbines needs to evaluate: normal power generation conditions, fault conditions, normal shutdown conditions, emergency shutdown conditions, startup conditions, idling conditions, etc. Among them, fault conditions and emergency shutdown conditions are two key conditions that affect the ultimate load of wind turbines, and the severe sub-conditions all involve "the action of retracting the blades during emergency shutdown". Therefore, how to optimize the "action of retracting the blades during emergency shutdown" has become an important way to optimize the ultimate loads of the two types of conditions.

[0004] In order to optimize the "Emergency Stop Paddle Retraction Action", it is necessary to analyze the relationship between the "segmented paddle retraction rate" and the "wind energy utilization rate" (Cp). If the "segmented paddle retraction rate" causes a sudden change in the "wind energy utilization rate", such as the "peak" and "trough" types, it is easy to cause the "aerodynamic load" of the wind rotor to fluctuate, and eventually cause the ultimate bending moment of the wind rotor to increase. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and propose a method and system for optimizing the load under emergency shutdown conditions of a wind turbine. A new segmented propeller retraction curve is defined based on the wind energy utilization rate Cp to achieve a smooth decrease in wind energy capture of the wind turbine under emergency shutdown conditions, thereby achieving a significant decrease in the ultimate bending moment of the wind rotor.

[0006] The purpose of the present invention is achieved through the following technical solution: A method for optimizing the load of a wind turbine in an emergency shutdown condition, comprising the following steps:

[0007] S1. According to the single-stage propeller retraction rate of the wind turbine, simulate the rotating hub coordinate system Hub_Myz load or the tower coordinate system top TowerTop_Mxy load of the wind turbine at the corresponding single-stage propeller retraction rate, and select the single-stage propeller retraction rate corresponding to the minimum load as the reference propeller retraction rate;

[0008] S2. Simulate and obtain the three-dimensional matrix table of wind energy utilization factor Cp, pitch angle PitchAngle and blade tip speed ratio λ of the wind turbine, check the wind speed and wind rotor speed at the maximum value of Hub_Myz load or TowerTop_Mxy load, and calculate the reference blade tip speed ratio λ 0 ; According to the reference tip speed ratio λ 0 , and obtain the wind energy utilization rate-pitch angle Cp-PitchAngle curve in the three-dimensional matrix table;

[0009] S3. Based on the Cp-PitchAngle curve, derive the Cp-PitchAngle derivative curve;

[0010] S4. According to the pitch angle PitchAngle at the maximum position of the Hub_Myz load or the TowerTop_Mxy load, select the area of ​​±25 degrees of the pitch angle as the key propeller return area, and the rest of the area as the non-key propeller return area;

[0011] S5. Calculate a reference propeller return rate curve based on the reference propeller return rate and the Cp-PitchAngle derivative curve, select the number of data points for the reference propeller return rate curve according to the key propeller return area and the non-key propeller return area, and obtain a reference segmented propeller return curve;

[0012] S6. According to the reference segmented propeller return curve, a preset step size and range are set by using the DOE method, and a plurality of segmented propeller return curves are calculated;

[0013] S7. Simulate and evaluate the Hub_Myz load or TowerTop_Mxy load of multiple segmented propeller return curves, select the segmented propeller return curve corresponding to the minimum load as the optimal segmented propeller return curve, and then apply it to the wind turbine to achieve load optimization under emergency shutdown conditions.

[0014] Further, the step S1 comprises:

[0015] According to the single-stage propeller retraction rate of the wind turbine, software is used to simulate the rotating hub coordinate system Hub_Myz load or the tower coordinate system top TowerTop_Mxy load of the wind turbine under the corresponding single-stage propeller retraction rate. The maximum load of Hub_Myz or the maximum load of TowerTop_Mxy of the wind turbine under emergency shutdown conditions is simulated and evaluated. At the same time, according to the preset load optimization requirements, the single-stage propeller retraction rate corresponding to the minimum load is selected as the benchmark propeller retraction rate.

[0016] Further, the step S2 comprises:

[0017] Simulate and obtain the three-dimensional matrix table of wind energy utilization factor Cp, pitch angle PitchAngle and blade tip speed ratio λ of the wind turbine. In the three-dimensional matrix table, check the wind speed and rotor speed at the maximum value of Hub_Myz load or TowerTop_Mxy load and obtain the rotor circumference, and calculate the reference blade tip speed ratio λ 0 , as shown in the following formula:

[0018] λ 0 = wind rotor speed × wind rotor circumference / wind speed;

[0019] According to the reference tip speed ratio λ 0 , the corresponding wind energy utilization rate-pitch angle Cp-PitchAngle curve is obtained in the three-dimensional matrix table.

[0020] Further, the step S3 comprises:

[0021] Based on the Cp-PitchAngle curve, a Cp-PitchAngle derivative curve is obtained by derivation, and the absolute value of the ordinate of the Cp-PitchAngle derivative curve is taken.

[0022] Further, the step S5 comprises:

[0023] S5.1. Use the reference propeller return rate as the mean value of the reference segmented propeller return rate;

[0024] S5.2. Calculate the reciprocal of the Cp-PitchAngle derivative curve after taking the absolute value of the ordinate to obtain a 1 / Cp-PitchAngle curve;

[0025] S5.3. Divide the 1 / Cp-PitchAngle curve by the mean value of the 1 / Cp-PitchAngle curve to calculate the coefficient of the reference segmented propeller retraction rate;

[0026] S5.4. Multiply the mean value of the reference segmented propeller return rate by the coefficient of the reference segmented propeller return rate to obtain a reference propeller return rate curve;

[0027] S5.5. Select the number of data points for the benchmark propeller return rate curve according to the key propeller return area and the non-key propeller return area, so that the key propeller return area contains 4-6 data points, and simplify the number of data points in the non-key propeller return area to obtain the benchmark segmented propeller return curve.

[0028] A wind turbine generator set emergency shutdown condition load optimization system, used to implement the wind turbine generator set emergency shutdown condition load optimization method, comprising:

[0029] The reference propeller retraction rate acquisition module simulates the rotating hub coordinate system Hub_Myz load or the tower coordinate system top TowerTop_Mxy load of the wind turbine at the corresponding single-stage propeller retraction rate according to the single-stage propeller retraction rate of the wind turbine, and selects the single-stage propeller retraction rate corresponding to the minimum load as the reference propeller retraction rate;

[0030] The reference tip speed ratio calculation module simulates and obtains the three-dimensional matrix table of wind energy utilization factor Cp, pitch angle PitchAngle and tip speed ratio λ of the wind turbine, checks the wind speed and rotor speed at the maximum value of Hub_Myz load or TowerTop_Mxy load, and calculates the reference tip speed ratio λ 0 ;

[0031] Cp-PitchAngle curve acquisition module, based on the reference tip speed ratio λ 0 , and obtain the wind energy utilization rate-pitch angle Cp-PitchAngle curve in the three-dimensional matrix table;

[0032] Cp-PitchAngle derivative curve calculation module, based on the Cp-PitchAngle curve, obtains the Cp-PitchAngle derivative curve by derivative;

[0033] The critical propeller return area calculation module selects the area within ±25 degrees of the pitch angle as the critical propeller return area according to the pitch angle PitchAngle at the maximum position of the Hub_Myz load or TowerTop_Mxy load, and the remaining areas as non-critical propeller return areas;

[0034] The reference segmented propeller return curve calculation module calculates the reference propeller return rate curve based on the reference propeller return rate and the Cp-PitchAngle derivative curve, selects the number of data points for the reference propeller return rate curve according to the key propeller return area and the non-key propeller return area, and obtains the reference segmented propeller return curve;

[0035] The optimal segmented propeller return curve acquisition module uses the DOE method to set the preset step size and range according to the benchmark segmented propeller return curve, and calculates multiple segmented propeller return curves; simulates and evaluates the Hub_Myz load or TowerTop_Mxy load of multiple segmented propeller return curves, and selects the segmented propeller return curve corresponding to the minimum load as the optimal segmented propeller return curve.

[0036] Further, the reference propeller retraction rate acquisition module includes:

[0037] According to the single-stage propeller retraction rate of the wind turbine, the rotating hub coordinate system Hub_Myz load or the tower coordinate system top TowerTop_Mxy load of the wind turbine under the corresponding single-stage propeller retraction rate is simulated to evaluate the maximum load of Hub_Myz or the maximum load of TowerTop_Mxy of the wind turbine under emergency shutdown conditions. At the same time, according to the preset load optimization requirements, the single-stage propeller retraction rate corresponding to the minimum load is selected as the benchmark propeller retraction rate.

[0038] Further, the reference tip speed ratio calculation module includes:

[0039] Simulate and obtain the three-dimensional matrix table of wind energy utilization factor Cp, pitch angle PitchAngle and blade tip speed ratio λ of the wind turbine. In the three-dimensional matrix table, check the wind speed and rotor speed at the maximum value of Hub_Myz load or TowerTop_Mxy load and obtain the rotor circumference, and calculate the reference blade tip speed ratio λ 0 , as shown in the following formula:

[0040] λ 0 =Wind rotor speed × wind rotor circumference / wind speed.

[0041] Further, the Cp-PitchAngle derivative curve calculation module includes:

[0042] Based on the Cp-PitchAngle curve, a Cp-PitchAngle derivative curve is obtained by derivation, and the absolute value of the ordinate of the Cp-PitchAngle derivative curve is taken.

[0043] Furthermore, the reference segmented propeller retraction curve calculation module includes:

[0044] 1) The reference propeller return rate is used as the mean value of the reference segmented propeller return rate;

[0045] 2) Calculate the inverse of the Cp-PitchAngle derivative curve after taking the absolute value of the ordinate to obtain the 1 / Cp-PitchAngle curve;

[0046] 3) Divide the 1 / Cp-PitchAngle curve by the mean of the 1 / Cp-PitchAngle curve to calculate the coefficient of the reference segmented propeller retraction rate;

[0047] 4) Multiplying the mean of the reference segmented propeller return rate by the coefficient of the reference segmented propeller return rate to obtain a reference propeller return rate curve;

[0048] 5) According to the key propeller return area and the non-key propeller return area, the number of data points of the benchmark propeller return rate curve is selected so that the key propeller return area contains 4-6 data points, and the number of data points in the non-key propeller return area is simplified to obtain the benchmark segmented propeller return curve.

[0049] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0050] 1. The present invention is a method for optimizing the limit load based on the change curve of the wind energy utilization rate Cp of the wind turbine generator set and defining a segmented propeller retraction curve, which can significantly reduce the limit bending moment load of the wind rotor, transmission chain, yaw system and tower top;

[0051] 2. The present invention realizes load reduction and cost reduction of large components of wind turbines based on pitch control logic, without adding any new hardware, and is low-cost and economical.

[0052] 3. The present invention is applicable to variable pitch wind turbines, has a wide application range, and has great promotion significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 This is a schematic diagram of a wind turbine in the rotating hub coordinate system.

[0054] Figure 2 This is a schematic diagram of a wind turbine in the tower coordinate system.

[0055] Figure 3 Schematic diagram of the Cp-PitchAngle derivative curve.

[0056] Figure 4 Schematic diagram of the Cp-PitchAngle derivative curve after taking the absolute value of the ordinate.

[0057] Figure 5 Schematic diagram of the benchmark segmented propeller return curve. DETAILED DESCRIPTION

[0058] The present invention will be further described below in conjunction with specific embodiments.

[0059] Example 1

[0060] The wind turbine generator set emergency shutdown load optimization method provided in this embodiment includes the following steps:

[0061] S1. See Figure 1 to Figure 2As shown, according to the single-stage propeller retraction rate of the wind turbine, the FAST software is used to simulate the rotating hub coordinate system Hub_Myz load or the tower coordinate system top TowerTop_Mxy load of the wind turbine at the corresponding single-stage propeller retraction rate, and the single-stage propeller retraction rate mode is used to set the single-stage propeller retraction rate range to 0.5deg / s~9deg / s. The maximum load of Hub_Myz or the maximum load of TowerTop_Mxy of the wind turbine under the emergency shutdown condition is simulated and evaluated, and a reference propeller retraction rate screening table is obtained, as shown in Table 1 below; at the same time, according to the preset load optimization requirements, the single-stage propeller retraction rate of 1.5deg / s corresponding to the minimum load is selected as the reference propeller retraction rate;

[0062] Serial number Single-stage propeller retraction rate (deg / s) Hub_Myz(kNm) TowerTop_Mxy(kNm) Minimum load 1 0.5 35383 27865 no 2 1 33275 26384 no 3 1.5 31052 24897 yes 4 2 32987 25896 no 5 2.5 36783 28741 no 6 3 38974 30876 no 7 3.5 40762 32785 no 8 4 41824 34286 no 9 4.5 43891 36831 no 10 5 46914 38402 no 11 5.5 49120 40219 no 12 6 51247 43818 no 13 6.5 53439 46813 no 14 7 56895 49214 no 15 7.5 58129 52121 no 16 8 63012 55310 no 17 8.5 67126 58914 no 18 9 71025 64128 no

[0063] Table 1 Benchmark propeller retraction rate screening table

[0064] S2. Use FAST software to simulate and obtain the three-dimensional matrix table of wind energy utilization factor Cp, pitch angle PitchAngle and blade tip speed ratio λ of the wind turbine, check the wind speed and wind rotor speed at the maximum value position of Hub_Myz load or TowerTop_Mxy load, and calculate the reference blade tip speed ratio λ 0 , as shown in the following formula:

[0065] λ 0 = wind rotor speed × wind rotor circumference / wind speed;

[0066] According to the reference tip speed ratio λ 0 , and obtain the wind energy utilization rate-pitch angle Cp-PitchAngle curve in the three-dimensional matrix table;

[0067] S3, see Figure 3 As shown, based on the Cp-PitchAngle curve, the Cp-PitchAngle derivative curve is obtained by derivation; see Figure 4 As shown, in order to facilitate the statistics of the segmented pitch return rate, the absolute value of the ordinate of the Cp-PitchAngle derivative curve is taken;

[0068] S4. According to the pitch angle PitchAngle at the maximum position of the Hub_Myz load or the TowerTop_Mxy load, select the area of ​​±25 degrees of the pitch angle, that is, 10 degrees to 60 degrees is used as the key propeller return area, and the rest of the area is used as the non-key propeller return area;

[0069] S5. Calculate a reference propeller return rate curve based on the reference propeller return rate and the Cp-PitchAngle derivative curve, select the number of data points for the reference propeller return rate curve according to the key propeller return area and the non-key propeller return area, and obtain a reference segmented propeller return curve, including:

[0070] S5.1. Use the reference propeller return rate of 1.5 deg / s as the average value of the reference segmented propeller return rate;

[0071] S5.2. Calculate the reciprocal of the Cp-PitchAngle derivative curve after taking the absolute value of the ordinate to obtain a 1 / Cp-PitchAngle curve;

[0072] S5.3. Divide the 1 / Cp-PitchAngle curve by the mean value of the 1 / Cp-PitchAngle curve to calculate the coefficient of the reference segmented propeller retraction rate;

[0073] S5.4. Multiply the mean value of the reference segmented propeller return rate by the coefficient of the reference segmented propeller return rate to obtain a reference propeller return rate curve;

[0074] S5.5. Since the reference segmented propeller return rate contains 6-10 data points, the number of data points of the reference propeller return rate curve needs to be selected according to the key propeller return area and the non-key propeller return area, so that the key propeller return area contains 4-6 data points, and the number of data points of the non-key propeller return area is simplified, and each non-key propeller return area only needs to contain 1-2 data points, so as to obtain the reference segmented propeller return curve, see Figure 5 As shown;

[0075] S6. According to the benchmark segmented propeller return curve, the DOE method is used to set the range to 0.7-1.3 and the step size to 0.05, and 13 segmented propeller return curves are calculated;

[0076] S7. Simulate and evaluate the Hub_Myz load or TowerTop_Mxy load of 13 segmented propeller return curves, select the segmented propeller return curve corresponding to the minimum load as the optimal segmented propeller return curve, and then apply it to the wind turbine to achieve load optimization under emergency shutdown conditions.

[0077] Example 2

[0078] This embodiment discloses a wind turbine generator set emergency shutdown condition load optimization system, which is used to implement the wind turbine generator set emergency shutdown condition load optimization method described in Embodiment 1, including:

[0079] The reference propeller retraction rate acquisition module simulates the rotating hub coordinate system Hub_Myz load or the tower coordinate system top TowerTop_Mxy load of the wind turbine at the corresponding single-stage propeller retraction rate according to the single-stage propeller retraction rate of the wind turbine, and selects the single-stage propeller retraction rate corresponding to the minimum load as the reference propeller retraction rate;

[0080] The reference tip speed ratio calculation module simulates and obtains the three-dimensional matrix table of wind energy utilization factor Cp, pitch angle PitchAngle and tip speed ratio λ of the wind turbine, checks the wind speed and rotor speed at the maximum value of Hub_Myz load or TowerTop_Mxy load, and calculates the reference tip speed ratio λ 0 ;

[0081] Cp-PitchAngle curve acquisition module, based on the reference tip speed ratio λ 0 , and obtain the wind energy utilization rate-pitch angle Cp-PitchAngle curve in the three-dimensional matrix table;

[0082] Cp-PitchAngle derivative curve calculation module, based on the Cp-PitchAngle curve, obtains the Cp-PitchAngle derivative curve by derivative;

[0083] The critical propeller return area calculation module selects the area within ±25 degrees of the pitch angle as the critical propeller return area according to the pitch angle PitchAngle at the maximum position of the Hub_Myz load or TowerTop_Mxy load, and the remaining areas as non-critical propeller return areas;

[0084] The reference segmented propeller return curve calculation module calculates the reference propeller return rate curve based on the reference propeller return rate and the Cp-PitchAngle derivative curve, selects the number of data points for the reference propeller return rate curve according to the key propeller return area and the non-key propeller return area, and obtains the reference segmented propeller return curve;

[0085] The optimal segmented propeller return curve acquisition module uses the DOE method to set the preset step size and range according to the benchmark segmented propeller return curve, and calculates multiple segmented propeller return curves; simulates and evaluates the Hub_Myz load or TowerTop_Mxy load of multiple segmented propeller return curves, and selects the segmented propeller return curve corresponding to the minimum load as the optimal segmented propeller return curve.

[0086] Example 3

[0087] This embodiment discloses a non-transitory computer-readable medium storing instructions. When the instructions are executed by a processor, the steps of the wind turbine emergency shutdown condition load optimization method according to Embodiment 1 are executed.

[0088] The non-temporary computer-readable medium in this embodiment may be a 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 other media.

[0089] Example 4

[0090] 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 wind turbine emergency shutdown condition load optimization method described in Example 1 is implemented.

[0091] 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.

[0092] The embodiments described above are only preferred embodiments of the present invention and are not intended to limit the scope of implementation of the present invention. Therefore, all changes made according to the shape and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for optimizing loads under emergency shutdown conditions of a wind turbine generator set, characterized in that: The following steps are involved: S1. According to the single-stage propeller retraction rate of the wind turbine, simulate the rotating hub coordinate system Hub_Myz load or the tower coordinate system top TowerTop_Mxy load of the wind turbine at the corresponding single-stage propeller retraction rate, and select the single-stage propeller retraction rate corresponding to the minimum load as the reference propeller retraction rate; S2. Simulate and obtain the three-dimensional matrix table of wind energy utilization rate Cp, pitch angle PitchAngle and blade tip speed ratio λ of the wind turbine, check the wind speed and wind rotor speed at the maximum value position of Hub_Myz load or TowerTop_Mxy load, and calculate the reference blade tip speed ratio λ0; according to the reference blade tip speed ratio λ0, obtain the corresponding wind energy utilization rate-pitch angle Cp-PitchAngle curve in the three-dimensional matrix table; S3. Based on the Cp-PitchAngle curve, derive the Cp-PitchAngle derivative curve; S4. According to the pitch angle PitchAngle at the maximum position of the Hub_Myz load or the TowerTop_Mxy load, select the area of ​​±25 degrees of the pitch angle as the key propeller return area, and the rest of the area as the non-key propeller return area; S5. Calculate a reference propeller return rate curve based on the reference propeller return rate and the Cp-PitchAngle derivative curve, select the number of data points for the reference propeller return rate curve according to the key propeller return area and the non-key propeller return area, and obtain a reference segmented propeller return curve; S6. According to the reference segmented propeller return curve, a preset step size and range are set by using the DOE method, and a plurality of segmented propeller return curves are calculated; S7. Simulate and evaluate the Hub_Myz load or TowerTop_Mxy load of multiple segmented propeller return curves, select the segmented propeller return curve corresponding to the minimum load as the optimal segmented propeller return curve, and then apply it to the wind turbine to achieve load optimization under emergency shutdown conditions.

2. A method for optimizing load of emergency shutdown condition of wind turbine generator set according to claim 1, characterized in that: The step S1 comprises: According to the single-stage propeller retraction rate of the wind turbine, software is used to simulate the rotating hub coordinate system Hub_Myz load or the tower coordinate system top TowerTop_Mxy load of the wind turbine under the corresponding single-stage propeller retraction rate. The maximum load of Hub_Myz or the maximum load of TowerTop_Mxy of the wind turbine under emergency shutdown conditions is simulated and evaluated. At the same time, according to the preset load optimization requirements, the single-stage propeller retraction rate corresponding to the minimum load is selected as the benchmark propeller retraction rate.

3. A method for optimizing load of emergency shutdown condition of wind turbine according to claim 1, characterized in that: The step S2 comprises: Use software simulation to obtain the three-dimensional matrix table of wind energy utilization factor Cp, pitch angle PitchAngle and blade tip speed ratio λ of the wind turbine. In the three-dimensional matrix table, check the wind speed and rotor speed at the maximum value of Hub_Myz load or TowerTop_Mxy load and obtain the rotor circumference, and calculate the reference blade tip speed ratio λ0, as shown in the following formula: λ0 = wind rotor speed × wind rotor circumference / wind speed; According to the reference tip speed ratio λ0, a corresponding wind energy utilization rate-pitch angle Cp-PitchAngle curve is obtained in the three-dimensional matrix table.

4. A method for optimizing load of emergency shutdown condition of wind turbine according to claim 1, characterized in that: The step S3 comprises: Based on the Cp-PitchAngle curve, a Cp-PitchAngle derivative curve is obtained by derivation, and the absolute value of the ordinate of the Cp-PitchAngle derivative curve is taken.

5. A method for optimizing load of emergency shutdown condition of wind turbine generator set according to claim 1, characterized in that: The step S5 comprises: S5.

1. Use the reference propeller return rate as the mean value of the reference segmented propeller return rate; S5.

2. Calculate the reciprocal of the Cp-PitchAngle derivative curve after taking the absolute value of the ordinate to obtain a 1 / Cp-PitchAngle curve; S5.

3. Divide the 1 / Cp-PitchAngle curve by the mean value of the 1 / Cp-PitchAngle curve to calculate the coefficient of the reference segmented propeller retraction rate; S5.

4. Multiply the mean value of the reference segmented propeller return rate by the coefficient of the reference segmented propeller return rate to obtain a reference propeller return rate curve; S5.

5. Select the number of data points for the benchmark propeller return rate curve according to the key propeller return area and the non-key propeller return area, so that the key propeller return area contains 4-6 data points, and simplify the number of data points in the non-key propeller return area to obtain the benchmark segmented propeller return curve.

6. A wind turbine emergency shutdown load optimization system, characterized in that: A method for optimizing loads under emergency shutdown conditions of a wind turbine generator set according to any one of claims 1 to 5, comprising: The reference propeller retraction rate acquisition module simulates the rotating hub coordinate system Hub_Myz load or the tower coordinate system top TowerTop_Mxy load of the wind turbine at the corresponding single-stage propeller retraction rate according to the single-stage propeller retraction rate of the wind turbine, and selects the single-stage propeller retraction rate corresponding to the minimum load as the reference propeller retraction rate; The reference tip speed ratio calculation module simulates and obtains the three-dimensional matrix table of wind energy utilization factor Cp, pitch angle PitchAngle and tip speed ratio λ of the wind turbine, checks the wind speed and wind rotor speed at the maximum value position of Hub_Myz load or TowerTop_Mxy load, and calculates the reference tip speed ratio λ0; A Cp-PitchAngle curve acquisition module, which acquires the wind energy utilization rate-pitch angle Cp-PitchAngle curve in a three-dimensional matrix table according to the reference blade tip speed ratio λ0; Cp-PitchAngle derivative curve calculation module, based on the Cp-PitchAngle curve, obtains the Cp-PitchAngle derivative curve by derivative; The critical propeller return area calculation module selects the area within ±25 degrees of the pitch angle as the critical propeller return area according to the pitch angle PitchAngle at the maximum position of the Hub_Myz load or TowerTop_Mxy load, and the remaining areas as non-critical propeller return areas; The reference segmented propeller return curve calculation module calculates the reference propeller return rate curve based on the reference propeller return rate and the Cp-PitchAngle derivative curve, selects the number of data points for the reference propeller return rate curve according to the key propeller return area and the non-key propeller return area, and obtains the reference segmented propeller return curve; The optimal segmented propeller return curve acquisition module uses the DOE method to set the preset step size and range according to the benchmark segmented propeller return curve, and calculates multiple segmented propeller return curves; simulates and evaluates the Hub_Myz load or TowerTop_Mxy load of multiple segmented propeller return curves, and selects the segmented propeller return curve corresponding to the minimum load as the optimal segmented propeller return curve.

7. A wind turbine emergency shutdown load optimization system according to claim 6, characterized in that: The reference propeller return rate acquisition module includes: According to the single-stage propeller retraction rate of the wind turbine, the rotating hub coordinate system Hub_Myz load or the tower coordinate system top TowerTop_Mxy load of the wind turbine under the corresponding single-stage propeller retraction rate is simulated to evaluate the maximum load of Hub_Myz or the maximum load of TowerTop_Mxy of the wind turbine under emergency shutdown conditions. At the same time, according to the preset load optimization requirements, the single-stage propeller retraction rate corresponding to the minimum load is selected as the benchmark propeller retraction rate.

8. A wind turbine emergency shutdown load optimization system according to claim 6, characterized in that: The reference tip speed ratio calculation module comprises: Simulate and obtain the three-dimensional matrix table of wind energy utilization factor Cp, pitch angle PitchAngle and blade tip speed ratio λ of the wind turbine. In the three-dimensional matrix table, check the wind speed and rotor speed at the maximum value of Hub_Myz load or TowerTop_Mxy load and obtain the rotor circumference, and calculate the reference blade tip speed ratio λ0, as shown in the following formula: λ0 = wind rotor speed × wind rotor circumference / wind speed.

9. A wind turbine emergency shutdown load optimization system according to claim 6, characterized in that: The Cp-PitchAngle derivative curve calculation module includes: Based on the Cp-PitchAngle curve, a Cp-PitchAngle derivative curve is obtained by derivation, and the absolute value of the ordinate of the Cp-PitchAngle derivative curve is taken.

10. A wind turbine emergency shutdown load optimization system according to claim 6, characterized in that: The reference segmented propeller retraction curve calculation module includes: 1) The reference propeller return rate is used as the mean value of the reference segmented propeller return rate; 2) Calculate the inverse of the Cp-PitchAngle derivative curve after taking the absolute value of the ordinate to obtain the 1 / Cp-PitchAngle curve; 3) Divide the 1 / Cp-PitchAngle curve by the mean of the 1 / Cp-PitchAngle curve to calculate the coefficient of the reference segmented propeller retraction rate; 4) Multiplying the mean of the reference segmented propeller return rate by the coefficient of the reference segmented propeller return rate to obtain a reference propeller return rate curve; 5) According to the key propeller return area and the non-key propeller return area, the number of data points of the benchmark propeller return rate curve is selected so that the key propeller return area contains 4-6 data points, and the number of data points in the non-key propeller return area is simplified to obtain the benchmark segmented propeller return curve.

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