A wind turbine extreme gust identification method and overspeed suppression method

Abstract

The application provides a wind turbine extreme gust identification method and overspeed inhibition method, so that the wind turbine can be quickly identified when encountering gust, and the overspeed inhibition method is started to prevent the generator from stopping due to overspeed and increase the hub and yaw imbalance limit load. By statistically analyzing the speed characteristic quantity of the normal power generation condition, a speed characteristic threshold curve is obtained by using a multiple interpolation method, the threshold curve envelopes all speed characteristic quantities under the normal power generation condition, and ensures that the overspeed inhibition method will not be triggered under the normal power generation condition. Meanwhile, the threshold curve can effectively distinguish the normal power generation condition and the gust condition, and can identify the gust as early as possible. In addition, in combination with the gust identification method, the overspeed inhibition method fully considers the limit performance of the wind turbine, and an additional pitch angle and generator torque are superimposed on the basis of the original pitch PI and torque PI, so as to achieve fast pitch and increase torque, and inhibit the overspeed of the generator.

Description

Technical Field

[0001] This invention relates to the field of wind power generation technology, specifically to a method for identifying extreme gusts in wind turbine generators and a method for suppressing overspeed. Background Technology

[0002] Wind power generation is the process by which wind turbine blades convert wind energy into mechanical energy, thereby driving a generator to produce electricity. There are many types of wind in nature, with gusts being a common occurrence. During gusts, wind speed and direction increase rapidly in a short period. Relying solely on pitch control (PI) can easily lead to overspeed shutdown. Furthermore, due to the significant yaw error angle in this condition, open-loop shutdown may result in extreme loads on the hub and yaw imbalance. To address the generator overspeed shutdown problem under gust conditions, a common method is to dynamically adjust the pitch PI gain in addition to conventional PI control. Specifically, under gust conditions, increasing the pitch PI gain accelerates blade pitch, reduces blade absorption of wind energy, and suppresses generator overspeed.

[0003] However, enabling dynamic pitch PI gain adjustment requires that the wind turbine accurately identify gust conditions. Otherwise, it will lead to frequent or even divergent blade pitch changes, increasing fatigue and load on various components of the wind turbine and reducing its service life. If the wind turbine is slow to identify gusts, the generator will have already overspeeded and shut down before the dynamic pitch PI gain adjustment is activated. Furthermore, dynamic pitch PI gain adjustment only regulates the pitch actuator and does not regulate the generator torque. If encountering gusts with large amplitude fluctuations, it can still cause the generator to overspeed and shut down.

[0004] Therefore, in order to solve the above-mentioned technical problems, it is urgent to propose a method for rapid identification of gusts and a gust control strategy. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the present invention provides a method for identifying extreme gusts and suppressing overspeed in wind turbines, so as to at least solve the technical problem that existing wind turbines cannot quickly identify gust conditions.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] A first aspect of the present invention provides a method for identifying extreme gusts in wind turbine generators, comprising the following steps:

[0008] The generator speed GenSpeed ​​and generator speed acceleration GenAcc at each pitch angle are obtained by simulation calculation, and the speed characteristic quantity GSAPC_Sign corresponding to each pitch angle is calculated based on the obtained generator speed GenSpeed ​​and generator speed acceleration GenAcc.

[0009] Based on the speed characteristic GSAPC_Sign corresponding to each pitch angle, the speed characteristic boundary line GSAPC_SignBound is calculated, and the speed characteristic threshold line GSAPC_SignLimit is calculated based on the speed characteristic boundary line GSAPC_SignBound.

[0010] Compare the rotational speed characteristic GSAPC_Sign with the rotational speed characteristic threshold GSAPC_SignLimit, and make the following determination:

[0011] If GSAPC_Sign < GSAPC_SignLimit, then it is determined that this is a normal power generation condition.

[0012] If GSAPC_Sign≥GSAPC_SignLimit, then this is determined to be an extreme gust wind condition.

[0013] Optionally, the step of calculating the speed characteristic GSAPC_Sign based on the obtained generator speed GenSpeed ​​and generator speed acceleration GenAcc includes the following steps:

[0014] The generator speed GenSpeed ​​and generator speed acceleration GenAcc are filtered respectively to obtain the generator filtered speed GenSpeed_Filter and generator filtered speed acceleration GenAcc_Filter at each pitch angle;

[0015] Based on the generator filter speed GenSpeed_Filter and the generator filter speed acceleration GenAcc_Filter, the speed characteristic GSAPC_Sign is calculated according to the following formula:

[0016] GSAPC_Sign=(GenSpeed_Filter-N12)*GenAcc_Filter*Timestep

[0017] In the formula, N12 is the reference speed when the wind turbine control area switches from Zone I to Zone II, and Timestep is the controller calculation cycle.

[0018] Optionally, the step of calculating the speed characteristic boundary line GSAPC_SignBound based on the speed characteristic GSAPC_Sign corresponding to each pitch angle, and calculating the speed characteristic threshold line GSAPC_SignLimit based on the speed characteristic boundary line GSAPC_SignBound, includes the following steps:

[0019] The pitch angle range is divided into multiple angle intervals I. The maximum value of the rotational speed feature in each angle interval I is extracted, and the maximum values ​​of the rotational speed feature are collected to obtain the GSAPC_Sign_Max vector.

[0020] Extract the peak value GSAPC_Sign_Peak from the GSAPC_Sign_Max vector;

[0021] Amplifying GSAPC_Sign_Peak yields the amplified value of the rotational speed characteristic, GSAPC_Sign_Zoom, which satisfies the following formula:

[0022] GSAPC_Sign_Zoom=GSAPC_Sign_Peak*Gain

[0023] In the formula, Gain is the amplification factor;

[0024] Interpolating the amplified value of the rotational speed characteristic GSAPC_Sign_Zoom yields the boundary line of the rotational speed characteristic GSAPC_SignBound, which satisfies the following formula:

[0025]

[0026] In the formula, GSAPC_Sign_Zoom(i) is the amplified value of the rotational speed characteristic of the i-th angle interval I, GSAPC_Sign_Zoom(i+1) is the amplified value of the rotational speed characteristic of the (i+1)-th angle interval I, PitchAngle_Sign(i) is the pitch angle value corresponding to GSAPC_Sign_Zoom(i), PitchAngle_Sign(i+1) is the pitch angle value corresponding to GSAPC_Sign_Zoom(i+1), and i = 1, 2, 3, ...;

[0027] Divide the pitch angle range into multiple angle intervals II, and each angle interval II contains at least two angle intervals I. Extract the speed characteristic boundary line GSAPC_SignBound corresponding to each angle interval II, and select the maximum peak value within the extracted speed characteristic boundary line GSAPC_SignBound as the speed characteristic threshold point GSAPC_SignBound_Org of that angle interval II.

[0028] Interpolating the speed characteristic threshold point GSAPC_SignBound_Org yields the speed characteristic threshold line GSAPC_SignLimit, which satisfies the following formula:

[0029]

[0030] In the formula, GSAPC_SignBound_Org(j) is the speed characteristic threshold point of the j-th interval, GSAPC_SignBound_Org(j+1) is the speed characteristic threshold point of the (j+1)-th interval, PitchAngle_Bound(j) is the pitch angle value corresponding to GSAPC_SignBound_Org(j), PitchAngle_Bound(j+1) is the pitch angle value corresponding to GSAPC_SignBound_Org(j+1), and j = 1, 2, 3, ...

[0031] A second aspect of the present invention provides a method for suppressing overspeed in extreme gusts of wind turbine generators, comprising the following steps:

[0032] Based on any of the above-described methods for identifying extreme gusts in wind turbines, the current operating condition of the wind turbine is determined:

[0033] When the condition is determined to be normal power generation, the basic PI control strategy is executed.

[0034] When the condition is determined to be an extreme gust of wind, an overspeed suppression method is implemented, including the following steps:

[0035] The torque superposition amount is calculated and superimposed on the torque value under the PI control strategy to obtain the superimposed generator torque;

[0036] Compare the superimposed generator torque with the upper limit of the generator torque, and make the following judgment:

[0037] If the superimposed generator torque is less than the upper limit of the generator torque, the generator will operate under the superimposed generator torque for a first preset time.

[0038] If the superimposed generator torque is greater than the upper limit of the generator torque, then the generator will operate at the upper limit of the generator torque for a first preset time.

[0039] Calculate the pitch angle superposition amount and superimpose it onto the pitch value under the PI control strategy to obtain the superimposed pitch angle.

[0040] Compare the superimposed pitch angle with the maximum pitch angle under the pitch rate limit, and make the following judgment:

[0041] If the superimposed pitch angle is less than the maximum pitch angle under the pitch rate limit, the generator is made to operate at the superimposed pitch angle for a second preset duration, wherein the second preset duration is longer than the first preset duration.

[0042] If the superimposed pitch angle is greater than the maximum pitch angle under the pitch rate limit, then the generator will operate at the maximum pitch angle under the pitch rate limit for a second preset duration.

[0043] Optionally, the calculation of the torque superposition includes:

[0044] The formula for calculating the torque superposition is as follows:

[0045] Torque_Add=(GenAcc_Filter / Nr)*Torque_Rated*Torque_Add_Gain

[0046] In the formula, GenAcc_Filter is the generator filter speed acceleration, Nr is the generator rated speed, Torque_Rated is the generator rated torque, and Torque_Add_Gain is the torque superposition amplification factor.

[0047] Optionally, the upper limit of the generator torque is calculated according to the following formula:

[0048] Forque_Dem_Limit=Power_Gain*Power_Rated / GenSpeed_Filter

[0049] In the formula, Power_Gain is the power amplification factor of the power generation system's ultimate performance, Power_Rated is the rated power of the generator, and GenSpeed_Filter is the filtered speed of the generator.

[0050] Optionally, the calculation of the pitch angle superposition includes:

[0051] Within the first second of implementing the overspeed suppression method, the pitch angle superposition is:

[0052] Pitch_Add_I=Pitch_Add_Max*Timestep

[0053] In the formula, Pitch_Add_Max is the maximum value of the pitch angle superposition, and Timestep is the controller calculation cycle;

[0054] After the first second of implementing the overspeed suppression method, the pitch angle superposition is:

[0055] Pitch_Add=[(Pitch_Add_Y1-Pitch_Add_Y2) / (Pitch_Add_X1-Pitch_Add_X2)*(GenAcc_Filter-Pitch_Add_X1)+Pitch_Add_Y1]*Timestep

[0056] In the formula, Pitch_Add_Y1 is the lower limit of the pitch superposition, Pitch_Add_Y2 is the upper limit of the pitch superposition, Pitch_Add_X1 is the lower limit of the rotational speed acceleration corresponding to Pitch_Add_Y1, and Pitch_Add_X2 is the upper limit of the rotational speed acceleration corresponding to Pitch_Add_Y2.

[0057] Optionally, the maximum value of the pitch angle is calculated using the following formula:

[0058] Pitch_Dem_Limit=Pitch_Dem_Old+PitchRate_Max*Timestep

[0059] In the formula, Pitch_Dem_Add_Old is the pitch angle setpoint at the previous moment, PitchRate_Max is the maximum pitch rate of the pitch actuator, and Timestep is the controller calculation cycle.

[0060] Optionally, the method for suppressing overspeed in extreme gusts of wind turbines further includes:

[0061] After implementing the overspeed suppression method, the generator speed software monitoring was upgraded from N4 to N4_Limit, the speed hardware monitoring was upgraded from NA to NA_Limit, the generator power software monitoring was upgraded from PA to PA_Limit, and the power hardware monitoring was upgraded from PT to PT_Limit.

[0062] As can be seen from the above technical solution, the beneficial effects of the present invention are as follows:

[0063] This invention proposes a method for identifying extreme gusts in wind turbines and a method for suppressing overspeed. This allows for rapid identification of gusts and the activation of the overspeed suppression method to prevent generator overspeed shutdown and increased hub and yaw imbalance loads. By statistically analyzing the speed characteristics under normal power generation conditions, a speed characteristic threshold curve is obtained using multiple interpolation. This threshold curve encompasses all speed characteristics under normal power generation conditions, ensuring that the overspeed suppression method is not triggered under normal conditions. Furthermore, this threshold curve effectively distinguishes between normal power generation and gust conditions and allows for early identification when gusts occur. In addition, considering the extreme performance of wind turbines and combining the gust identification method with the overspeed suppression method, an additional pitch angle and generator torque are superimposed on the original pitch PI and torque PI to achieve rapid pitch adjustment and increased torque, thereby suppressing generator overspeed. Attached Figure Description

[0064] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0065] Figure 1 A flowchart of a method for identifying extreme gusts in wind turbines;

[0066] Figure 2 This is a schematic diagram of the control area division for a power speed controller used in a conventional PI control strategy. Detailed Implementation

[0067] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0068] To address generator overspeed shutdown under gust conditions, a common approach is to dynamically adjust the pitch PI gain on top of conventional PI control. This involves increasing the pitch PI gain under gust conditions to accelerate blade pitch, reduce wind energy absorption, and suppress generator overspeed. However, dynamically adjusting the pitch PI gain only affects the pitch actuator and not the generator torque. If gusts with large amplitude fluctuations occur, generator overspeed can still occur. Furthermore, if gust conditions are misidentified, the PI gain can lead to frequent or even divergent pitch adjustments, significantly increasing the unit load and reducing its lifespan. The overspeed suppression method employed in this invention does not change the pitch PI and torque PI. Instead, it adds an extra pitch angle and generator torque based on the wind turbine's ultimate performance limits, achieving rapid pitch adjustment and increased torque to suppress generator overspeed. The specific solution is as follows.

[0069] This invention provides a method for identifying extreme gusts in wind turbines, comprising the following steps:

[0070] S1. By inputting the external conditions of the wind turbine, perform simulation calculations under normal power generation conditions to obtain the generator speed GenSpeed ​​and generator speed acceleration GenAcc at each pitch angle, and calculate the speed characteristic quantity GSAPC_Sign corresponding to each pitch angle based on the obtained generator speed GenSpeed ​​and generator speed acceleration GenAcc.

[0071] S2. Calculate the speed characteristic boundary line GSAPC_SignBound based on the speed characteristic GSAPC_Sign corresponding to each pitch angle, and calculate the speed characteristic threshold line GSAPC_SignLimit based on the speed characteristic boundary line GSAPC_SignBound.

[0072] S3. Compare the rotational speed characteristic quantity GSAPC_Sign with the rotational speed characteristic quantity threshold GSAPC_SignLimit, and make the following determination:

[0073] If GSAPC_Sign < GSAPC_SignLimit, then it is determined that this is a normal power generation condition.

[0074] If GSAPC_Sign≥GSAPC_SignLimit, then this is determined to be an extreme gust wind condition.

[0075] In step S1, the speed characteristic quantity GSAPC_Sign corresponding to each pitch angle is calculated based on the obtained generator speed GenSpeed ​​and generator speed acceleration GenAcc, specifically including the following steps:

[0076] The generator speed GenSpeed ​​and generator speed acceleration GenAcc are filtered respectively to obtain the generator filtered speed GenSpeed_Filter and generator filtered speed acceleration GenAcc_Filter at each pitch angle;

[0077] Based on the generator filter speed GenSpeed_Filter and the generator filter speed acceleration GenAcc_Filter, the speed characteristic GSAPC_Sign is calculated according to the following formula:

[0078] GSAPC_Sign=(GenSpeed_Filter-N12)*GenAcc_Filter*Timestep

[0079] In the formula, N12 is the reference speed when the wind turbine control area switches from Zone I to Zone II, and Timestep is the controller calculation cycle.

[0080] To illustrate the technical solution of this embodiment, a brief description of the basic PI control strategy is provided. The power-speed controller control area division used in the conventional PI control strategy is as follows: Figure 2 As shown, the specific control method is as follows:

[0081] The power speed controller operates in three control zones determined by the generator speed, namely control zones I, II, and III, such as... Figure 2As shown. Control zones I and II are activated at low power, while control zone III is activated when rated power is reached. In control zones I and II, the pitch controller maintains the pitch angle at the minimum pitch angle. In control zone III, the pitch controller and torque controller control the rotor / generator speed, keeping it within a certain range of rated speed. The generator speed difference is used as the input to the pitch and torque controllers. Due to the nonlinear effects of pitch angle and output power variations at different wind speeds, a nonlinear pitch gain factor is required in the pitch controller.

[0082] Pitch Controller Description:

[0083] The pitch controller employs PI regulation. The regulator input x is the difference between the generator speed and the reference speed, and the regulator output y is the change (increment) of the pitch angle relative to the time step. The PI regulator equation is as follows:

[0084]

[0085] x = GenSpeed ​​- GenSpeed_Ref

[0086] Pitch_PI = Pitch_PI old +y

[0087] In the formula, kp-pitch is the proportional gain of the pitch controller, ki-pitch is the integral gain of the pitch controller, G(φ) is the nonlinear pitch gain factor, GenSpeed_Ref is the generator reference speed, Pitch_PI is the pitch angle setpoint, and the value with the subscript old indicates the value of the previous time step.

[0088] Torque controller description:

[0089] The torque controller employs PI regulation. The regulator input (x) is the difference between the generator speed and the reference speed, and the regulator output (y) is the change (increment) of torque relative to the time step. The PI regulator equation is as follows:

[0090]

[0091] x = GenSpeed ​​- GenSpeed_Ref

[0092] Torque_PI = Torque_PI old +y

[0093] In the formula, kp-torque is the proportional gain of the pitch controller, ki-torque is the proportional gain of the pitch controller, Timestep is the controller calculation cycle, Torque_PI is the torque setpoint, and the value with the subscript old indicates the value of the previous time step.

[0094] In step S2, the speed characteristic quantity boundary line GSAPC_SignBound is calculated based on the speed characteristic quantity GSAPC_Sign corresponding to each pitch angle, and the speed characteristic quantity threshold line GSAPC_SignLimit is calculated based on the speed characteristic quantity boundary line GSAPC_SignBound. The simulation software uses a bladed filter, and the filtering method for generator speed and speed acceleration is an arithmetic mean filter with a resolution of 0.5s. The specific steps include the following:

[0095] S21. Starting from 0°, take 0.1° pitch angle as angle interval I, extract the maximum value of the rotational speed feature within each angle interval I, and collect the maximum values ​​of the rotational speed feature to obtain the GSAPC_Sign_Max vector.

[0096] S22. Extract the peak value GSAPC_Sign_Peak of the GSAPC_Sign_Max vector, that is, a certain element is greater than the value of the two adjacent elements.

[0097] S23. Amplify GSAPC_Sign_Peak to obtain the amplified value of the rotational speed characteristic GSAPC_Sign_Zoom, which satisfies the following formula:

[0098] GSAPC_Sign_Zoom=GSAPC_Sign_Peak*Gain

[0099] In the formula, Gain is the amplification factor;

[0100] S24. Interpolate the amplified value of the rotational speed characteristic GSAPC_Sign_Zoom to obtain the boundary line of the rotational speed characteristic GSAPC_SignBound. The interpolation formula is as follows:

[0101]

[0102] Note: If the pitch angle is outside the interpolation range, the maximum value of the speed characteristic value at both ends of the range is used, and no further extrapolation is performed.

[0103] In the formula, GSAPC_Sign_Zoom(i) is the amplified value of the rotational speed characteristic of the i-th angle interval I, GSAPC_Sign_Zoom(i+1) is the amplified value of the rotational speed characteristic of the (i+1)-th angle interval I, PitchAngle_Sign(i) is the pitch angle value corresponding to GSAPC_Sign_Zoom(i), PitchAngle_Sign(i+1) is the pitch angle value corresponding to GSAPC_Sign_Zoom(i+1), and i = 1, 2, 3, ...;

[0104] S25. Starting from 0°, take 1° pitch angle as angle interval II, extract the speed characteristic boundary line GSAPC_SignBound corresponding to each angle interval II, and select the maximum peak value within the extracted speed characteristic boundary line GSAPC_SignBound as the speed characteristic threshold point GSAPC_SignBound_Org of that angle interval II.

[0105] S26. Interpolate the speed characteristic threshold point GSAPC_SignBound_Org to obtain the speed characteristic threshold line GSAPC_SignLimit, which satisfies the following formula:

[0106]

[0107] Note: If the pitch angle is outside the interpolation range, the maximum value of the speed characteristic value at both ends of the range is used, and no further extrapolation is performed.

[0108] In the formula, GSAPC_SignBound_Org(j) is the speed characteristic threshold point of the j-th interval, GSAPC_SignBound_Org(j+1) is the speed characteristic threshold point of the (j+1)-th interval, PitchAngle_Bound(j) is the pitch angle value corresponding to GSAPC_SignBound_Org(j), PitchAngle_Bound(j+1) is the pitch angle value corresponding to GSAPC_SignBound_Org(j+1), and j = 1, 2, 3, ...

[0109] In step S3, GSAPC_Sign and GSAPC_SignLimit are compared in real time, and the following determination is made:

[0110] If GSAPC_Sign < GSAPC_SignLimit, then it is determined that this is a normal power generation condition, that is, the basic PI control strategy is executed.

[0111] If GSAPC_Sign≥GSAPC_SignLimit, then this is determined to be an extreme gust of wind condition, that is, the overspeed suppression method is executed to prevent the generator from overspeeding and stopping, which would increase the ultimate load of the hub and yaw imbalance.

[0112] Therefore, the present invention further discloses a method for suppressing overspeed in extreme gusts of wind turbines, comprising the following steps:

[0113] S100. Calculate the torque superposition amount and superimpose it onto the torque value under the PI control strategy to obtain the superimposed generator torque;

[0114] S200. Compare the superimposed generator torque with the upper limit of the generator torque, and make the following judgment:

[0115] If the superimposed generator torque is less than the upper limit of the generator torque, the generator will operate under the superimposed generator torque for a first preset time.

[0116] If the superimposed generator torque is greater than the upper limit of the generator torque, then the generator will operate at the upper limit of the generator torque for a first preset time.

[0117] S300. Calculate the pitch angle superposition amount and superimpose it onto the pitch value under the PI control strategy to obtain the superimposed pitch angle.

[0118] Compare the superimposed pitch angle with the maximum pitch angle under the pitch rate limit, and make the following judgment:

[0119] If the superimposed pitch angle is less than the maximum pitch angle under the pitch rate limit, the generator is made to operate at the superimposed pitch angle for a second preset duration, wherein the second preset duration is longer than the first preset duration.

[0120] If the superimposed pitch angle is greater than the maximum pitch angle under the pitch rate limit, then the generator will operate at the maximum pitch angle under the pitch rate limit for a second preset duration.

[0121] Specifically, in step S200, the formula for calculating the torque superposition is as follows:

[0122] Torque_Add=(GenAcc_Filter / Nr)*Torque_Rated*Torque_add_Gain

[0123] In the formula, GenAcc_Filter is the generator filter speed acceleration, Nr is the generator rated speed, Torque_Rated is the generator rated torque, and Torque_Add_Gain is the torque superposition amplification factor.

[0124] The superimposed generator torque is:

[0125] Torque_Dem_Add=Torque_Add+Torque_PI

[0126] In the formula, Torque_PI is the torque calculated by the basic PI controller.

[0127] To prevent the superimposed generator torque from exceeding the generator's limiting performance, the upper limit of the superimposed generator torque is calculated as follows:

[0128] Torque_Dem_Limit=Power_Gain*Power_Rated / GenSpeed_Filter

[0129] In the formula, Power_Gain is the power amplification factor of the power generation system's ultimate performance, Power_Rated is the rated power of the generator, and GenSpeed_Filter is the filtered speed of the generator.

[0130] The torque value that triggers the overspeed suppression method is:

[0131] Torque_Dem=min(Torque_Dem_Add,Torque_Dem_Limit)

[0132] To prevent damage to the hardware caused by the generator operating at its maximum performance level for extended periods, the maximum duration of torque superposition needs to be set based on the specific generator performance. In this example, the maximum duration of torque superposition is 4 seconds.

[0133] In step S300, regarding the pitch angle superposition, within the first second of executing the overspeed suppression method, the pitch angle superposition is:

[0134] Pitch_Add_I=Pitch_Add_Max*Timestep

[0135] In the formula, Pitch_Add_Max is the maximum value of the pitch angle superposition, and Timestep is the controller calculation cycle;

[0136] After the first second of implementing the overspeed suppression method, the pitch angle superposition is:

[0137] Pitch_Add=[(Pitch_Add_Y1-Pitch_Add_Y2) / (Pitch_Add_X1-Pitch_Add_X2)*(GenAcc_Filter-Pitch_Add_X1)+Pitch_Add_Y1]*Timestep

[0138] In the formula, Pitch_Add_Y1 is the lower limit value of pitch overlay, Pitch_Add_Y2 is the upper limit value of pitch overlay, Pitch_Add_X1 is the lower limit value of rotational acceleration corresponding to Pitch_Add_Y1, and Pitch_Add_X2 is the upper limit value of rotational acceleration corresponding to Pitch_Add_Y2. If the rotational acceleration is outside the interpolation range, the pitch overlay values ​​at both ends of the range are used, and no further extrapolation is performed.

[0139] The superimposed pitch angle setpoint is then:

[0140] Pitch_Dem_Add=Pitch_Add+Pitch_PI

[0141] In the formula, Pitch_PI is the pitch angle calculated by the basic PI controller.

[0142] To ensure that the pitch rate after the pitch angles are superimposed does not exceed the hardware design requirements of the pitch actuator, the maximum value of the pitch angle is limited to:

[0143] PitchDem_Limit=Pitch_Dem_Old+PitchRate_Max*Timestep

[0144] In the formula, Pitch_Dem_Add_Old is the pitch angle setpoint of the previous moment, PitchRate_Max is the maximum pitch rate of the pitch actuator, and Timestep is the controller calculation cycle.

[0145] The pitch angle setpoint for the overspeed suppression method is:

[0146] Pitch_Dem=min(Pitch_Dem_Add, Pitch_Dem_Limit)

[0147] It should be noted that, in order to ensure the smooth implementation of the overspeed suppression method, after executing the overspeed suppression method, the generator speed software monitoring is upgraded from N4 to N4_Limit, the speed hardware monitoring is upgraded from NA to NA_Limit, the generator power software monitoring is upgraded from PA to PA_Limit, and the power hardware monitoring is upgraded from PT to PT_Limit; to ensure that the overspeed suppression method achieves the desired effect after execution, the execution duration of the overspeed suppression method is not less than 8 seconds.

[0148] This invention proposes a method for identifying extreme gusts in wind turbines and a method for suppressing overspeed. This allows for rapid identification of gusts and the activation of the overspeed suppression method to prevent generator overspeed shutdown and increased hub and yaw imbalance loads. By statistically analyzing the speed characteristics under normal power generation conditions, a speed characteristic threshold curve is obtained using multiple interpolation. This threshold curve encompasses all speed characteristics under normal power generation conditions, ensuring that the overspeed suppression method is not triggered under normal conditions. Furthermore, this threshold curve effectively distinguishes between normal power generation and gust conditions and allows for early identification when gusts occur. In addition, considering the extreme performance of wind turbines and combining the gust identification method with the overspeed suppression method, an additional pitch angle and generator torque are superimposed on the original pitch PI and torque PI to achieve rapid pitch adjustment and increased torque, thereby suppressing generator overspeed.

[0149] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A method of identifying extreme gusts for a wind turbine, characterized in that, The method comprises the following steps: The simulation calculation obtains the generator speed GenSpeed and the generator speed acceleration GenAcc under each pitch angle, and the speed characteristic quantity GSAPC_Sign corresponding to each pitch angle is calculated based on the obtained generator speed GenSpeed and the generator speed acceleration GenAcc, comprising the following steps: The generator speed GenSpeed and the generator speed acceleration GenAcc are respectively filtered to obtain the generator filtered speed GenSpeed_Filter and the generator filtered speed acceleration GenAcc_Filter under each pitch angle; The speed characteristic quantity GSAPC_Sign is calculated based on the generator filtered speed GenSpeed_Filter and the generator filtered speed acceleration GenAcc_Filter according to the following formula: GSAPC_Sign=(GenSpeed_Filter-N12)*GenAcc_Filter*Timestep In the formula, N12 is the reference speed at which the control area of the wind turbine is switched from region I to region II, and Timestep is the calculation period of the controller; The speed characteristic quantity boundary line GSAPC_SignBound is calculated based on the speed characteristic quantity GSAPC_Sign corresponding to each pitch angle, and the speed characteristic quantity threshold line GSAPC_SignLimit is calculated based on the speed characteristic quantity boundary line GSAPC_SignBound; The speed characteristic quantity GSAPC_Sign and the speed characteristic quantity threshold GSAPC_SignLimit are compared, and the following determination is made: If GSAPC_Sign<GSAPC_SignLimit, it is determined that the current working condition is a normal power generation condition; If GSAPC_Sign≥GSAPC_SignLimit, it is determined that the current working condition is an extreme gust condition.

2. A method of extreme gust identification for a wind turbine according to claim 1, characterized in that, The speed characteristic quantity boundary line GSAPC_SignBound is calculated based on the speed characteristic quantity GSAPC_Sign corresponding to each pitch angle, and the speed characteristic quantity threshold line GSAPC_SignLimit is calculated based on the speed characteristic quantity boundary line GSAPC_SignBound, comprising the following steps: Divide the pitch angle range into a plurality of angle intervals I, extract the maximum value of the speed characteristic quantity in each angle interval I, and collect the maximum values of the speed characteristic quantities to obtain a GSAPC_Sign_Max vector; Extract the peak value GSAPC_Sign_Peak of the GSAPC_Sign_Max vector; The GSAPC_Sign_Peak is amplified to obtain a speed characteristic quantity zoom value GSAPC_Sign_Zoom, satisfying the following formula: GSAPC_Sign_Zoom=GSAPC_Sign_Peak*Gain In the formula, Gain is an amplification coefficient; Interpolation is performed on the rotation speed characteristic quantity zoom value GSAPC_Sign_Zoom to obtain a rotation speed characteristic quantity boundary line GSAPC_SignBound, which satisfies the following formula: In the formula, GSAPC_Sign_Zoom(i) is a rotation speed characteristic quantity zoom value of the i-th angle interval I, GSAPC_Sign_Zoom(i+1) is a rotation speed characteristic quantity zoom value of the i+1-th angle interval I, PitchAngle_Sign(i) is a pitch angle value corresponding to GSAPC_Sign_Zoom(i), PitchAngle_Sign(i+1) is a pitch angle value corresponding to GSAPC_Sign_Zoom(i+1), and i = 1, 2, 3, …; The pitch angle range is evenly divided into a plurality of angle intervals II, and each angle interval II contains at least two angle intervals I. The rotation speed characteristic quantity boundary line GSAPC_SignBound corresponding to each angle interval II is intercepted, and the maximum peak value in the intercepted rotation speed characteristic quantity boundary line GSAPC_SignBound is selected as a rotation speed characteristic quantity threshold point GSAPC_SignBound_Org of the angle interval II; Interpolation is performed on the rotation speed characteristic quantity threshold point GSAPC_SignBound_Org to obtain a rotation speed characteristic quantity threshold line GSAPC_SignLimit, which satisfies the following formula: In the formula, GSAPC_SignBound_Org(j) is a rotation speed characteristic quantity threshold point of the j-th interval, GSAPC_SignBound_Org(j+1) is a rotation speed characteristic quantity threshold point of the j+1-th interval, PitchAngle_Bound(j) is a pitch angle value corresponding to GSAPC_SignBound_Org(j), PitchAngle_Bound(j+1) is a pitch angle value corresponding to GSAPC_SignBound_Org(j+1), and j = 1, 2, 3, ….

3. A method of extreme gust overspeed inhibition for a wind turbine, the method comprising: The method comprises the following steps: Based on the extreme gust identification method of the wind turbine according to claim 1 or 2, the current working condition of the wind turbine is determined: When it is determined that the working condition is normal power generation, a basic PI control strategy is executed; When it is determined that the working condition is an extreme gust, an overspeed suppression method is executed, which comprises the following steps: A torque superposition amount is calculated and superimposed on the torque value under the PI control strategy to obtain a superimposed generator torque; The superimposed generator torque and the upper limit value of the generator torque are compared, and the following determination is made: If the superimposed generator torque is less than the upper limit value of the generator torque, the generator operates at the superimposed generator torque for a first preset time length; If the superimposed generator torque is greater than the upper limit value of the generator torque, the generator operates at the upper limit value of the generator torque for a first preset time length; A pitch angle superposition amount is calculated and superimposed on the pitch value under the PI control strategy to obtain a superimposed pitch angle; The superimposed pitch angle and the maximum pitch angle under the pitch rate limit are compared, and the following determination is made: If the superimposed pitch angle is less than the maximum pitch angle under the pitch rate limit, the generator is operated at the superimposed pitch angle for a second preset time period, wherein the second preset time period is greater than the first preset time period; If the superimposed pitch angle is greater than the maximum pitch angle under the pitch rate limit, the generator is operated at the maximum pitch angle under the pitch rate limit for a second preset time period.

4. A method of inhibiting overspeed of a wind turbine due to an extreme gust according to claim 3, wherein, The torque superimposition amount is calculated, comprising: The formula for solving the torque superimposition amount is as follows: Torque_Add=(GenAcc_Filter / Nr)*Torque_Rated*Torque_Add_Gain In the formula, GenAcc_Filter is the generator filter speed acceleration, Nr is the generator rated speed, Torque_Rated is the generator rated torque, and Torque_Add_Gain is the torque superimposition amplification coefficient.

5. A method of inhibiting overspeed of a wind turbine due to an extreme gust of wind according to claim 4, characterized in that, The upper limit value of the generator torque is calculated according to the following formula: Torque_Dem_Limit=Power_Gain*Power_Rated / GenSpeed_Filter In the formula, Power_Gain is the power system limit performance power amplification coefficient, Power_Rated is the generator rated power, and GenSpeed_Filter is the generator filter speed.

6. A method of inhibiting overspeed of a wind turbine due to an extreme gust according to claim 3, wherein, The pitch angle superimposition amount is calculated, comprising: In the first second of executing the overspeed inhibition method, the pitch angle superimposition amount is: Pitch_Add_I-Pitch_Add_Max*Timestep In the formula, Pitch_Add_Max is the maximum value of the pitch angle superimposition amount, and Timestep is the controller calculation period. After the first second of executing the overspeed inhibition method, the pitch angle superimposition amount is: Pitch_Add=[(Pitch_Add_Y1-Pitch_Add_Y2) / (Pitch_Add_X1-Pitch_Add_X2)*(GenAcc_Filter-Pitch_Add_X1)+Pitch_Add_Y1]*Timestep In the formula, Pitch_Add_Y1 is the lower limit value of the pitch superimposition, Pitch_Add_Y2 is the upper limit value of the pitch superimposition, Pitch_Add_X1 is the lower limit value of the speed acceleration corresponding to Pitch_Add_Y1, and Pitch_Add_X2 is the upper limit value of the speed acceleration corresponding to Pitch_Add_Y2.

7. A method of inhibiting overspeed of a wind turbine due to an extreme gust according to claim 6, wherein, The maximum value of the pitch angle is calculated according to the following formula: Pitch_Dem_Limit=Pitch_Dem_Old+PitchRate_Max*Timestep In the formula, Pitch_Dem_Add_Old is the pitch angle given value at the previous time, PitchRate_Max is the maximum pitch rate of the pitch actuator, and Timestep is the controller calculation period.

8. A method of extreme gust overspeed inhibition for a wind turbine according to any of claims 3-7, characterized in that, Comprising: After the overspeed suppression method is executed, the speed software monitoring of the generator is raised from N4 to N4_Limit, the speed hardware monitoring is raised from NA to NA_Limit, the power software monitoring of the generator is raised from PA to PA_Limit, and the power hardware monitoring is raised from PT to PT_Limit.

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