A control method and system for suppressing excessive load when wind turbine blades are stuck

Abstract

The present invention discloses a control method and system for suppressing excessive load when blades of a wind turbine are stuck. First, it is determined whether the wind turbine is shut down due to blade sticking. If not, a shutdown action is performed according to a conventional control strategy. If yes, a blade is stuck and no longer moves. At this time, a fixed value needs to be superimposed on the current pitch angle of the remaining blades, and then the pitch angle given value of the remaining blades is set according to the generator speed to avoid the large deviation of the pitch angle between the blades and the high speed of the generator from occurring at the same time, and to avoid large vibration of the wind turbine after a fault occurs. When the generator speed is reduced to the set value, the remaining blades are adjusted to 90° according to the set pitch rate, thereby achieving the purpose of suppressing excessive load when blades of the wind turbine are stuck. The present invention is also applicable to all working conditions with excessive load caused by aerodynamic imbalance and unit vibration, and has a very broad application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power generation, and in particular to a control method and system for suppressing excessive load when blades of a wind turbine are stuck. Background Art

[0002] According to the IEC-3 standard, considering the failure of the variable pitch system, it is necessary to simulate and calculate the operation of the unit under the condition of a single blade stuck, and evaluate whether the strength of the components meets its limit load. With the development of large capacity and long blades in wind power generation technology, it is found through simulation calculation that a large proportion of the maximum limit of the hub bending moment and tower bending moment occurs in the DLC2.2dd working condition with a single blade stuck.

[0003] DLC2.2dd working condition: wind speed is cut-out wind speed Vout, wind model is normal turbulent wind model, fault is blade 1 suddenly stuck and no longer moves when the unit is running normally for 10s, blades 2 and 3 can still receive the main control command to change the pitch. Conventional logic, when the pitch angle deviation between blade 1 and blades 2 and 3 is greater than the maximum setting value of blade following error, the main control algorithm triggers the pitch following fault and the unit shuts down.

[0004] 1) Near the cut-out wind speed Vout, the blade pitch angle fluctuates around 18°, and once blade 1 is stuck and cannot move, the unit will definitely trigger a variable pitch following fault. According to the conventional control strategy, after the unit triggers a variable pitch following fault, blade 1 will be stuck and no longer move, and its pitch angle will remain at the pitch angle value at the time of the stuck fault, that is, about 18°. Blades 2 and 3 receive the feathering command to feather, so the pitch angle values ​​of blades 2 and 3 are getting larger and larger, which directly leads to an increasing error between blade 1 and blades 2 and 3. At this time, the aerodynamic imbalance of the unit is getting more and more serious, which will inevitably lead to a greater limit load of the unit;

[0005] 2) The unit operates at the cut-out wind speed Vout. At this time, the unit is in full power state, and the impeller speed fluctuates around the rated speed, and the speed is high.

[0006] Combining 1) and 2), it can be seen that aerodynamic imbalance and high speed operation of the unit are two important factors that cause the unit load to be too large. In order to reduce the ultimate load, reduce the cost per kilowatt-hour, and improve product competitiveness, the ultimate maximum value of this operating condition must be reduced.

[0007] The methods used in the past, such as adjusting the pitch rate according to the pitch angle or simply reducing the pitch rate, can no longer fundamentally solve the problem of excessive load under this fault condition. Summary of the invention

[0008] The first purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a control method for suppressing the excessive load when the blades of a wind turbine are stuck. The pitch angle of the blades is adjusted based on the real-time speed of the generator, which can effectively reduce the problem of excessive load when a single blade is stuck caused by aerodynamic imbalance and unit vibration.

[0009] A second object of the present invention is to provide a control system that suppresses excessive load when a wind turbine blade is stuck.

[0010] The first purpose of the present invention is achieved through the following technical scheme: a control method for suppressing excessive load when the blades of a wind turbine are stuck. First, it is determined whether the wind turbine is shut down due to the stuck blades. If not, the shutdown action is performed according to the conventional control strategy. If so, a certain blade is stuck and no longer moves, and the remaining blades can still receive the main control command to perform pitch change action. At this time, it is necessary to superimpose a fixed value on the current pitch angle of the remaining blades, and then set the pitch angle of the remaining blades according to the generator speed to avoid the large deviation of the pitch angle between the blades and the high speed of the generator from occurring at the same time, and to avoid large vibration of the wind turbine after a fault occurs. When the generator speed is reduced to the set value, the remaining blades are pitched to 90° at the set pitch change rate, thereby achieving the purpose of suppressing excessive load when the blades of the wind turbine are stuck.

[0011] Furthermore, the control method for suppressing excessive load when the wind turbine blades are stuck comprises the following steps:

[0012] 1) Data measurement

[0013] Measure the pitch angle of each blade and the generator speed. Suppose the measured blade pitch angle is θ(k) and the generator speed is ω Gen , and filtering is performed, and the generator speed after filtering by the transfer function F(s) is ω Genf ,Right now:

[0014] ω Genf =ω Gen *F(s)

[0015]

[0016] Where F(s) is the transfer function, including a second-order low-pass filter and a notch filter, s is the Laplace operator, ξ, ξ1, ξ2 are damping coefficients, ω, ω1, ω2 are frequencies;

[0017] 2) Determine whether a single blade is stuck

[0018] When the wind turbine triggers a blade following fault, if the deviation between the current pitch angle value of a blade and the pitch angle value of the blade at the next moment is less than the set value θ, it is determined that the blade is stuck, and step 3) is executed; otherwise, it is considered that there is no blade stuck, and the shutdown action is performed according to the conventional control strategy;

[0019] 3) Calculate the superposition value of the pitch angle of the remaining blades

[0020] When the generator speed ω Genf When it falls in the wind speed range (A1, A4), the linear interpolation method is used to calculate the size of the pitch angle superposition value Δθ; when the generator speed ω Genf When the speed is less than or equal to A1, the superposition value of the pitch angle of the remaining blades Δθ is B1; when the generator speed ω Genf When it is greater than or equal to A4, the pitch angle superposition value Δθ of the remaining blades is taken as B4, that is, when ω Genf ≤A1, Δθ=B1, ω Genf ≥A4, Δθ=B4;

[0021] 4) Calculate the pitch angle given value of the remaining blades

[0022] Once it is determined that a blade is stuck, the pitch angle given value θ(k+1) of the remaining blades at the next moment is a fixed value superimposed on the pitch angle θ(k) at the current moment, that is, the pitch angle superposition value Δθ calculated in step 3) is added to reduce the generator speed, that is:

[0023] θ(k+1)=θ(k)+Δθ

[0024] If the generator speed decreases, the pitch angle set values ​​of the remaining blades need to be further increased; if the generator speed increases, the pitch angle set values ​​of the remaining blades need to be reduced;

[0025] 5) Adjust the blade pitch angle

[0026] When the generator speed ω Genf When it decreases to a certain set value, the value is 0.5 times the rated speed of the generator n r , the remaining blades are pitched to 90° at the set pitch rate, i.e. when ω Genf ≤0.5*n r When , the pitch angle setting value of the remaining blades at the next moment becomes:

[0027] θ(k+1)=θ(k)+pitchrate*T

[0028] Where, pitchrate is the set pitch rate, T is the Controller Cycle Time control algorithm cycle time constant;

[0029] Finally, the wind turbine blade actuator adjusts the blade pitch angle according to the determined pitch angle given value, that is, the final pitch command, so as to achieve optimized control to suppress excessive load when the wind turbine blade is stuck.

[0030] The second purpose of the present invention is achieved through the following technical scheme: a control system for suppressing excessive load when the blades of a wind turbine are stuck. The system must first determine whether the wind turbine is shut down due to blade jamming. If not, the system will perform a shutdown action according to a conventional control strategy. If so, a blade is stuck and no longer moves, and the remaining blades can still receive the main control command to perform pitch change actions. At this time, a fixed value needs to be superimposed on the current pitch angle of the remaining blades, and then the pitch angle of the remaining blades is set according to the generator speed to avoid the simultaneous occurrence of large deviations in the pitch angle between the blades and high generator speed, as well as to avoid large vibrations of the wind turbine after a fault occurs. When the generator speed is reduced to the set value, the remaining blades are pitched to 90° at the set pitch change rate, thereby achieving the purpose of suppressing excessive load when the blades of the wind turbine are stuck.

[0031] Furthermore, the control system for suppressing excessive load when the wind turbine blades are stuck comprises:

[0032] A measurement module, used to measure the pitch angle of each blade and the generator speed;

[0033] A discrimination module, used to discriminate whether a single blade is stuck;

[0034] A pitch angle superposition value calculation module is used to calculate the pitch angle superposition values ​​of the remaining blades except the stuck blade;

[0035] A pitch angle given value calculation module, used to calculate the pitch angle given values ​​of the remaining blades except the stuck blade;

[0036] The feathering control module is used to control the remaining blades except the stuck blade to feather to 90° according to the set pitch rate.

[0037] Furthermore, the measurement module specifically performs the following operations:

[0038] Assume the measured blade pitch angle is θ(k) and the generator speed is ω Gen , and filtering is performed, and the generator speed after filtering by the transfer function F(s) is ω Genf ,Right now:

[0039] ω Genf =ω Gen *F(s)

[0040]

[0041] Where F(s) is the transfer function, including a second-order low-pass filter and a notch filter, s is the Laplace operator, ξ, ξ1, ξ2 are damping coefficients, and ω, ω1, ω2 are frequencies.

[0042] Furthermore, the identification module specifically performs the following operations:

[0043] When the wind turbine triggers a blade following fault, if the deviation between the current pitch angle value of a blade and the pitch angle value of the blade at the next moment is less than the set value θ, it is determined that the blade is stuck and the pitch angle superposition value calculation module is executed. Otherwise, it is considered that there is no blade stuck and the shutdown action is performed according to the conventional control strategy.

[0044] Further, the pitch angle superposition value calculation module specifically performs the following operations:

[0045] When the generator speed ω Genf When it falls in the wind speed range (A1, A4), the linear interpolation method is used to calculate the size of the pitch angle superposition value Δθ; when the generator speed ω Genf When the speed is less than or equal to A1, the superposition value of the pitch angle of the remaining blades Δθ is B1; when the generator speed ω Genf When it is greater than or equal to A4, the pitch angle superposition value Δθ of the remaining blades is taken as B4, that is, when ω Genf ≤A1, Δθ=B1, ω Genf When ≥A4, Δθ=B4.

[0046] Further, the pitch angle given value calculation module specifically performs the following operations:

[0047] Once it is determined that a blade is stuck, the pitch angle given value θ(k+1) of the remaining blades at the next moment is a fixed value superimposed on the pitch angle θ(k) at the current moment, that is, the pitch angle superposition value Δθ calculated by the pitch angle superposition value calculation module is added to reduce the generator speed, that is:

[0048] θ(k+1)=θ(k)+Δθ

[0049] If the generator speed decreases, the pitch angle set values ​​of the remaining blades need to be further increased. If the generator speed increases, the pitch angle set values ​​of the remaining blades need to be reduced.

[0050] Further, the feathering control module specifically performs the following operations:

[0051] When the generator speed ω Genf When it decreases to a certain set value, the value is 0.5 times the rated speed of the generator n r , the remaining blades are pitched to 90° at the set pitch rate, i.e. when ω Genf ≤0.5*nr When , the pitch angle setting value of the remaining blades at the next moment becomes:

[0052] θ(k+1)=θ(k)+pitchrate*T

[0053] Wherein, θ(k+1) is the given value of the blade pitch angle at the next moment, θ(k) is the blade pitch angle at the current moment, pitchrate is the set pitch rate, and T is the Controller Cycle Time control algorithm cycle time constant;

[0054] Finally, the wind turbine blade actuator adjusts the blade pitch angle according to the determined pitch angle given value, that is, the final pitch command, so as to achieve optimized control to suppress excessive load when the wind turbine blade is stuck.

[0055] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0056] 1. The present invention adopts a method of adjusting the blade pitch angle based on the real-time speed of the generator. By avoiding the simultaneous occurrence of large deviations in the pitch angle between the blades and high speed of the generator, the large-scale vibration of the unit after a fault occurs is reduced. When the generator speed drops to the set value, the blades that are not stuck are adjusted to 90° at the set pitch rate. Compared with the existing control method, it can effectively reduce the problem of excessive load when a single blade is stuck due to aerodynamic imbalance and unit vibration.

[0057] 2. The present invention does not require additional unit equipment, but only requires adding corresponding functional modules to the control algorithm to reduce aerodynamic imbalance and unit vibration, reduce unit load, thereby saving costs and improving unit competitiveness.

[0058] 3. The present invention has a strong theoretical basis and is easily accepted by relevant technical personnel, laying the foundation for subsequent control optimization and improvement and equipment maintenance.

[0059] 4. The present invention is also applicable to all working conditions where the load is too large due to aerodynamic imbalance and unit vibration, has a very broad application prospect, and is worthy of promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 It is a flowchart of the method of the present invention.

[0061] Figure 2 Schematic diagram of the system of the present invention. DETAILED DESCRIPTION

[0062] The present invention will be further described below in conjunction with specific embodiments.

[0063] Example 1

[0064] For the DLC2.2dd working condition, this embodiment provides a control method for suppressing excessive load when the wind turbine blades are stuck. First, it is determined whether the wind turbine is shut down due to blade jamming. If not, the shutdown action is performed according to the conventional control strategy. If so, it is assumed that blade 1 is stuck (of course, if other blades 2 or blade 3 are stuck, the processing method is the same). Blades 2 and blades 3 can still accept the main control command to perform pitch change action. At this time, it is necessary to superimpose a fixed value on the current pitch angle of blades 2 and blades 3, and then set the pitch angle given value of blades 2 and blades 3 according to the generator speed to avoid the large deviation of the pitch angle between the blades and the high speed of the generator at the same time, and to avoid large vibration of the wind turbine after a fault occurs. When the generator speed is reduced to the set value, blades 2 and blades 3 are aligned to 90° at the set pitch change rate, thereby achieving the purpose of suppressing excessive load when the wind turbine blades are stuck.

[0065] like Figure 1 As shown, the control method for suppressing excessive load when the wind turbine blades are stuck in the present embodiment includes the following steps:

[0066] 1) Data measurement

[0067] Measure the pitch angle of each blade and the generator speed. Suppose the measured pitch angle of blade 1 is θ1(k), the pitch angle of blade 2 is θ2(k), the pitch angle of blade 3 is θ3(k), and the generator speed is ω Gen , and filtering is performed, and the generator speed after filtering by the transfer function F(s) is ω Genf ,Right now:

[0068] ω Genf =ω Gen *F(s)

[0069]

[0070] Wherein, F(s) is the transfer function, including a second-order low-pass filter and a notch filter, s is the Laplace operator, ξ, ξ1, ξ2 are damping coefficients, ω, ω1, ω2 are frequencies. Generally, ω1=ω2, and its size is the frequency of one rotation of the impeller.

[0071] 2) Determine whether a single blade is stuck

[0072] When the wind turbine triggers a blade following fault, if the deviation between the current pitch angle value of a blade and the pitch angle value of the blade at the next moment is less than a set value θ, where θ is generally 0.1°, it is determined that the blade is stuck and step 3) is executed; otherwise, it is considered that there is no blade stuck and the shutdown action is performed according to the conventional control strategy;

[0073] 3) Calculate the superposition value of the pitch angle of the remaining blades

[0074] At this time, it is assumed that blade 1 is stuck. Genf When the wind speed falls within the range (A1, A4) of Table 1 below, the linear interpolation method is used to calculate the size of the pitch angle superposition value Δθ; when the generator speed ω Genf When the speed of the generator is less than or equal to A1 in Table 1 below, the pitch angle superposition value Δθ of the remaining blades is taken as B1; when the speed of the generator is ω Gen When f is greater than or equal to A4 in Table 1 below, the pitch angle superposition value Δθ of the remaining blades is taken as B4, that is, when ω Genf ≤A1, Δθ=B1, ω Genf When ≥A4, Δθ=B4, the number of columns in this table can be increased or decreased.

[0075] Table 1 Correspondence between generator speed and superposition value of blade 2 and 3 pitch angle

[0076]

[0077] 4) Calculate the pitch angle given value of the remaining blades

[0078] Once it is determined that blade 1 is stuck, the pitch angle given value of blades 2 and 3 at the next moment is a fixed value superimposed on the pitch angle at the current moment, that is, the pitch angle superposition value Δθ calculated in step 3) is added to reduce the generator speed, that is:

[0079] θ2(k+1)=θ2(k)+Δθ

[0080] θ3(k+1)=θ3(k)+Δθ

[0081] If the generator speed decreases, the pitch angle set values ​​of the remaining blades need to be further increased. If the generator speed increases, the pitch angle set values ​​of the remaining blades need to be reduced.

[0082] 5) Adjust the blade pitch angle

[0083] When the generator speed ω Genf When it is reduced to a certain set value, the value is generally 0.5 times the rated speed of the generator n r , blades 2 and 3 are pitched to 90° at the set pitch rate, i.e. when ω Genf ≤0.5*n r When , the pitch angle given values ​​of blades 2 and 3 at the next moment become:

[0084] θ2(k+1)=θ2(k)+pitchrate*T

[0085] θ3(k+1)=θ3(k)+pitchrate*T

[0086] Wherein, θ2(k) is the pitch angle of blade 2 at the current moment, θ2(k+1) is the given value of the pitch angle of blade 2 at the next moment, θ3(k) is the pitch angle of blade 3 at the current moment, θ3(k+1) is the given value of the pitch angle of blade 3 at the next moment, pitchrate is the set pitch rate, and T is the cycle time constant of the Controller Cycle Time control algorithm;

[0087] Finally, the wind turbine blade actuator adjusts the blade pitch angle according to the determined pitch angle given value, that is, the final pitch command, so as to achieve optimized control to suppress excessive load when the wind turbine blade is stuck.

[0088] Example 2

[0089] The present embodiment provides a control system for suppressing excessive load when the wind turbine blades are stuck. The system first determines whether the wind turbine is shut down due to blade sticking. If not, the system performs a shutdown action according to a conventional control strategy. If so, a certain blade is stuck and no longer moves, and the remaining blades can still receive the main control command to perform pitch change action. At this time, a fixed value needs to be superimposed on the current pitch angle of the remaining blades, and then the pitch angle of the remaining blades is set according to the generator speed to avoid the large deviation of the pitch angle between the blades and the high speed of the generator from occurring at the same time, and to avoid large vibration of the wind turbine after a fault occurs. When the generator speed drops to the set value, the remaining blades are pitched to 90° at the set pitch change rate, thereby achieving the purpose of suppressing excessive load when the wind turbine blades are stuck.

[0090] like Figure 2 As shown, the control system for suppressing excessive load when the wind turbine blades are stuck in this embodiment includes the following functional modules:

[0091] A measurement module, used to measure the pitch angle of each blade and the generator speed;

[0092] A discrimination module, used to discriminate whether a single blade is stuck;

[0093] A pitch angle superposition value calculation module is used to calculate the pitch angle superposition values ​​of the remaining blades except the stuck blade;

[0094] A pitch angle given value calculation module, used to calculate the pitch angle given values ​​of the remaining blades except the stuck blade;

[0095] The feathering control module is used to control the remaining blades except the stuck blade to feather to 90° according to the set pitch rate.

[0096] The measurement module specifically performs the following operations:

[0097] Assume the measured blade pitch angle is θ(k) and the generator speed is ω Gen , and filtering is performed, and the generator speed after filtering by the transfer function F(s) is ω Genf ,Right now:

[0098] ω Genf =ω Gen *F(s)

[0099]

[0100] Wherein, F(s) is the transfer function, including a second-order low-pass filter and a notch filter, s is the Laplace operator, ξ, ξ1, ξ2 are damping coefficients, ω, ω1, ω2 are frequencies. Generally, ω1=ω2, and its magnitude is the frequency of one rotation of the impeller.

[0101] The identification module specifically performs the following operations:

[0102] When the wind turbine triggers a blade following fault, if the deviation between the current pitch angle value of a blade and the pitch angle value of the blade at the next moment is less than the set value θ, it is determined that the blade is stuck and the pitch angle superposition value calculation module is executed. Otherwise, it is considered that there is no blade stuck and the shutdown action is performed according to the conventional control strategy.

[0103] The pitch angle superposition value calculation module specifically performs the following operations:

[0104] When the generator speed ω Genf When it falls in the wind speed range (A1, A4), the linear interpolation method is used to calculate the size of the pitch angle superposition value Δθ; when the generator speed ω Genf When the speed is less than or equal to A1, the superposition value of the pitch angle of the remaining blades Δθ is B1; when the generator speed ω Genf When it is greater than or equal to A4, the pitch angle superposition value Δθ of the remaining blades is taken as B4, that is, when ω Genf ≤A1, Δθ=B1, ω Genf When ≥A4, Δθ=B4.

[0105] The pitch angle given value calculation module specifically performs the following operations:

[0106] Once it is determined that a blade is stuck, the pitch angle given value θ(k+1) of the remaining blades at the next moment is a fixed value superimposed on the pitch angle θ(k) at the current moment, that is, the pitch angle superposition value Δθ calculated by the pitch angle superposition value calculation module is added to reduce the generator speed, that is:

[0107] θ(k+1)=θ(k)+Δθ

[0108] If the generator speed decreases, the pitch angle set values ​​of the remaining blades need to be further increased. If the generator speed increases, the pitch angle set values ​​of the remaining blades need to be reduced.

[0109] The feathering control module specifically performs the following operations:

[0110] When the generator speed ω Genf When it decreases to a certain set value, the value is 0.5 times the rated speed of the generator n r , the remaining blades are pitched to 90° at the set pitch rate, i.e. when ω Genf ≤0.5*n r When , the pitch angle setting value of the remaining blades at the next moment becomes:

[0111] θ(k+1)=θ(k)+pitchrate*T

[0112] Wherein, θ(k+1) is the given value of the blade pitch angle at the next moment, θ(k) is the blade pitch angle at the current moment, pitchrate is the set pitch rate, and T is the Controller Cycle Time control algorithm cycle time constant;

[0113] Finally, the wind turbine blade actuator adjusts the blade pitch angle according to the determined pitch angle given value, that is, the final pitch command, so as to achieve optimized control to suppress excessive load when the wind turbine blade is stuck.

[0114] The above-described embodiments 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 control method for suppressing excessive load when wind turbine blades are stuck. It is characterized in that First, determine whether the wind turbine is shut down due to blade jamming. If not, shut down according to the conventional control strategy. If yes, a blade is jammed and no longer moves, and the remaining blades can still receive the main control command to change the pitch. At this time, a fixed value needs to be superimposed on the current pitch angle of the remaining blades, and then the pitch angle of the remaining blades is set according to the generator speed to avoid the large deviation of the pitch angle between the blades and the high speed of the generator. The two conditions can be avoided at the same time, and the wind turbine can be prevented from vibrating sharply after the fault occurs. When the generator speed drops to the set value, the remaining blades are pitched to 90° according to the set pitch rate, so as to achieve the purpose of suppressing the excessive load when the wind turbine blades are jammed. The following steps are involved: 1) Data measurement Measure the pitch angle of each blade and the generator speed. Suppose the measured blade pitch angle is , the generator speed is , and filter processing, and after the transfer function The generator speed after filtering is ,Right now: ； ； In the formula, is the transfer function, including a second-order low-pass filter and a notch filter. is the Laplace operator, , , is the damping coefficient, , , is the frequency; 2) Determine whether a single blade is stuck When the wind turbine triggers a blade following fault, if the deviation between the current pitch angle value of a blade and the pitch angle value of the blade at the next moment is less than the set value , it is determined that there is a blade stuck situation, and step 3) is executed. Otherwise, it is considered that there is no blade stuck situation, and the shutdown action is performed according to the conventional control strategy; 3) Calculate the superposition value of the pitch angle of the remaining blades When the generator speed When the wind speed falls within the range (A1, A4), the linear interpolation method is used to calculate the superposition value of the pitch angle. The size of the generator speed When it is less than or equal to A1, the pitch angle superposition value of the remaining blades Take B1; when the generator speed When A4 is greater than or equal to, the pitch angle superposition value of the remaining blades Take B4, that is, when hour, , hour, ; 4) Calculate the pitch angle given value of the remaining blades Once a blade is determined to be stuck, the pitch angle of the remaining blades at the next moment is set to is the pitch angle at the current moment A fixed value is superimposed on the basis, that is, the pitch angle superimposed value calculated in step 3) is added , to reduce the generator speed, that is: ； If the generator speed decreases, the pitch angle set values ​​of the remaining blades need to be further increased; if the generator speed increases, the pitch angle set values ​​of the remaining blades need to be reduced; 5) Adjust the blade pitch angle When the generator speed When it drops to a certain set value, the value is 0.5 times the rated speed of the generator. , the remaining blades are pitched to 90° at the set pitch rate, i.e. When , the pitch angle setting value of the remaining blades at the next moment becomes: ； In the formula, is the set pitch rate, Controller Cycle Time is the control algorithm cycle time constant; Finally, the wind turbine blade actuator adjusts the blade pitch angle according to the determined pitch angle given value, that is, the final pitch command, so as to achieve optimized control to suppress excessive load when the wind turbine blade is stuck.

2. A control system to suppress excessive load when wind turbine blades are stuck. Features: The system must first determine whether the wind turbine is shut down due to blade jamming. If not, it will shut down according to the conventional control strategy. If so, a blade is jammed and no longer moves, and the remaining blades can still receive the main control command to change the pitch. At this time, it is necessary to superimpose a fixed value on the current pitch angle of the remaining blades, and then set the pitch angle of the remaining blades according to the generator speed to avoid the large deviation of the pitch angle between the blades and the high speed of the generator. The two conditions occur at the same time, and the wind turbine vibrates sharply after the fault occurs. When the generator speed drops to the set value, the remaining blades are pitched to 90° at the set pitch rate, thereby achieving the purpose of suppressing the excessive load when the wind turbine blades are jammed; including: A measurement module, used to measure the pitch angle of each blade and the generator speed; A discrimination module, used to discriminate whether a single blade is stuck; A pitch angle superposition value calculation module is used to calculate the pitch angle superposition values ​​of the remaining blades except the stuck blade; A pitch angle given value calculation module, used to calculate the pitch angle given values ​​of the remaining blades except the stuck blade; A feathering control module is used to control the remaining blades except the stuck blade to feather to 90° according to the set pitch rate; The measurement module specifically performs the following operations: Assume the measured blade pitch angle is , the generator speed is , and filter processing, and after the transfer function The generator speed after filtering is ,Right now: ； ； In the formula, is the transfer function, including a second-order low-pass filter and a notch filter. is the Laplace operator, , , is the damping coefficient, , , is the frequency; The identification module specifically performs the following operations: When the wind turbine triggers a blade following fault, if the deviation between the current pitch angle value of a blade and the pitch angle value of the blade at the next moment is less than the set value , it is determined that there is a blade stuck situation, and the process jumps to the pitch angle superposition value calculation module for execution; otherwise, it is considered that there is no blade stuck situation, and the shutdown action is performed according to the conventional control strategy; The pitch angle superposition value calculation module specifically performs the following operations: When the generator speed When the wind speed falls within the range (A1, A4), the linear interpolation method is used to calculate the superposition value of the pitch angle. The size of the generator speed When it is less than or equal to A1, the pitch angle superposition value of the remaining blades Take B1; when the generator speed When A4 is greater than or equal to, the pitch angle superposition value of the remaining blades Take B4, that is, when hour, , hour, ; The pitch angle given value calculation module specifically performs the following operations: Once a blade is determined to be stuck, the pitch angle of the remaining blades at the next moment is set to is the pitch angle at the current moment A fixed value is superimposed on the basis, that is, the pitch angle superposition value calculated by the pitch angle superposition value calculation module is added , to reduce the generator speed, that is: ； If the generator speed decreases, the pitch angle set values ​​of the remaining blades need to be further increased; if the generator speed increases, the pitch angle set values ​​of the remaining blades need to be reduced; The feathering control module specifically performs the following operations: When the generator speed When it drops to a certain set value, the value is 0.5 times the rated speed of the generator. , the remaining blades are pitched to 90° at the set pitch rate, i.e. When , the pitch angle setting value of the remaining blades at the next moment becomes: ； In the formula, is the given value of the blade pitch angle at the next moment, is the pitch angle of the blade at the current moment, is the set pitch rate, Controller Cycle Time is the control algorithm cycle time constant; Finally, the wind turbine blade actuator adjusts the blade pitch angle according to the determined pitch angle given value, that is, the final pitch command, so as to achieve optimized control to suppress excessive load when the wind turbine blade is stuck.

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