Blade root limit load control method and system based on blade root resultant bending moment

Abstract

The invention discloses a blade root limit load control method and system based on a blade root resultant bending moment, and the method comprises the steps: calculating the blade root resultant bending moment of each blade based on the measured blade root in-plane load and out-of-plane load, taking the maximum value of the blade root resultant bending moment in all blades, and enveloping the maximum value, and multiplying the difference value of the envelope value and a set load threshold value by a set proportionality coefficient to obtain a pitch angle superposition amount, so that the wind generating set executes a pitch change instruction when the blade root resultant bending moment rises to exceed the set load threshold value, and the purpose of load reduction is achieved. The problem that the combined bending moment of the blade root of the large-impeller wind generating set is large can be solved, and then the blade root load meets the design requirement.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power generation, and in particular to a blade root limit load control method, system, storage medium and computing device based on blade root combined bending moment. Background Art

[0002] The main sources of loads on wind turbines are gravity loads, inertia loads and starting loads. Loads are the main factors affecting the operating status of wind turbines and the basis for wind turbine operation control. The size of the load is closely related to the safety of the unit and will directly affect the life of the components.

[0003] With the rapid development of the wind power industry, in order to improve the power generation efficiency of wind turbines in medium and low wind speed areas, wind turbines are gradually innovating in technology and optimizing costs in the direction of larger impellers and longer blades. As the impeller becomes larger, the axial thrust on the impeller swept plane also increases significantly, which will cause the operating load of the wind turbine, especially the blade root, to suffer greater load impact, such as the blade root combined bending moment M. xy Therefore, how to effectively reduce the load level of the blades and thus reduce the cost of the blades is a very important part of the cost reduction and optimization of the wind turbine generator set.

[0004] In response to the above problems, the methods currently used at home and abroad are mainly based on the measured power of wind turbines to indirectly reflect the change trend of thrust, and then formulate corresponding variable pitch strategies according to the change trend of thrust to reduce thrust in order to achieve the purpose of reducing blade root load. However, the output power of wind turbines does not have a strong correlation with the axial thrust of the impeller swept plane. Therefore, in actual control, in order to achieve a better load reduction effect, the pitch angle range of the variable pitch is often set very large, which will lead to large power fluctuations and power generation losses; at the same time, the thrust reduction strategy is mainly only for working conditions near and below the rated wind speed, and cannot reduce the load for working conditions above the rated wind speed. In summary, this method has limitations. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for controlling the blade root limit load based on the blade root resultant bending moment. When the blade root resultant bending moment rises and exceeds a set load threshold, the pitch angle is superimposed to change the pitch, thereby reducing the blade root resultant bending moment, thereby reducing the blade design cost of the wind turbine, solving the problem of large blade root resultant bending moment of large-impeller wind turbines, and thereby ensuring that the blade root load meets the design requirements.

[0006] A second object of the present invention is to provide a blade root limit load control system based on the blade root combined bending moment.

[0007] A third object of the present invention is to provide a storage medium.

[0008] A fourth object of the present invention is to provide a computing device.

[0009] The first purpose of the present invention is achieved through the following technical scheme: a blade root limit load control method based on blade root combined bending moment, the method calculates the blade root combined bending moment of each blade based on the measured blade root in-plane load and out-of-plane load, takes the maximum value of the blade root combined bending moment among all blades, and takes the envelope of the maximum value, multiplies the difference between the envelope value and the set load threshold by the set proportional coefficient to obtain the pitch angle superposition amount, so that the wind turbine executes a pitch change command when the blade root combined bending moment rises above the set load threshold, thereby achieving the purpose of load reduction.

[0010] Furthermore, the blade root limit load control method based on the blade root combined bending moment comprises the following steps:

[0011] In-plane load on blade root M x and the out-of-plane load M y High-pass filtering is performed, and then based on the filtered blade root in-plane load M x and the out-of-plane load M y Calculate the root bending moment M of each blade xy And filter, take the root bending moment M after filtering of all blades xy The maximum value of

[0012] If the maximum root bending moment of all blades at the current moment is M xy The filtered value and the maximum root bending moment M of all blades at the previous moment xy The difference of the filtered values ​​multiplied by the maximum root bending moment M of all blades at the previous moment xy The filtered value and the maximum root bending moment M of all blades at the previous moment xy The difference of the filtered values ​​is less than zero and the maximum root bending moment M of all blades at the current moment xy The filtered value and the maximum root bending moment M of all blades at the previous moment xy The difference of the filtered values ​​is also less than zero, so the maximum root bending moment of all blades at the current moment is M xy The filtered value is the envelope value, otherwise the maximum root bending moment M of all blades at the previous moment is used. xy The filtered value is used as the envelope value;

[0013] The load threshold is set in principle so that it cannot affect the steady-state wind, that is, the set load threshold should be greater than the maximum blade root bending moment M of the steady-state wind. xy The specific method is as follows: first simulate three steady-state wind conditions below the rated wind speed, rated wind speed and above the rated wind speed, and calculate the maximum blade root bending moment M under the three steady wind conditions xy The load threshold should be set to be greater than the maximum blade root bending moment M under the three steady-state wind conditions.xy The maximum value in the envelope value of ;

[0014] The blade root bending moment M xy The difference between the envelope value and the set load threshold is multiplied by the set proportional coefficient to obtain the pitch angle superposition, and then the unit executes the corresponding pitch change instruction based on this pitch angle superposition.

[0015] Furthermore, stress sensors are installed at the root positions of all blades of the wind turbine generator set to measure the root in-plane load M of each corresponding blade. x and the out-of-plane load M y The stress sensor converts the deformation of the strain gauge into a resistance or voltage output with a linear or arbitrary function relationship. Assuming that the unit has N blades, the distance between the blade root predetermined position P1 of blade 1 and the blade root position is X1, the distance between the blade root predetermined position P2 of blade 2 and the blade root position is X2, and the distance between the blade root predetermined position P N The distance from the blade root is X N , blade root predetermined position P1, P2, ..., P N is the actual stress sensor installation position, distance X1, X2, ..., X N is the distance between the sensor position and the blade root, X1, X2, ..., X N Calibration needs to be carried out according to actual site conditions.

[0016] Furthermore, the measured blade root in-plane load M x and the out-of-plane load M y After high-pass filtering, the blade root bending moment M is obtained by calculation. xy , the calculation formula is as follows:

[0017]

[0018] Furthermore, the calculated root bending moment M of each blade is xy Filter and then take the root bending moment M of all blades xy The maximum value after filtering is further used to obtain the envelope value based on the maximum value. The specific method is as follows: Assuming that the current time is T i , the corresponding maximum root bending moment of all blades is M xy The filter value is L i ; The last moment is T i-1 , the corresponding maximum root bending moment of all blades is M xy The filter value is L i-1 ; The last time is T i-2 , the corresponding maximum root bending moment of all blades is M xy The filter value is L i-2 ; Ti Moment and T i-1 The difference in time is (L i -L i-1 ), T i-1 Moment and T i-2 The difference in time is (L i-1 -L i-2 ), if (L i -L i-1 )×(L i-1 -L i-2 ) is less than zero and (L i -L i-1 ) is also less than zero, then the maximum root bending moment of all blades at the current moment is M xy Filter value L i is the envelope value, otherwise the maximum root bending moment M of all blades at the previous moment is used. xy Filter value L i-1 as the envelope value.

[0019] Furthermore, the specific method of setting the load threshold is as follows: take three wind speeds W1, W2 and W3, which represent the wind speed below the rated value, the rated wind speed and the wind speed above the rated value, respectively, perform simulations at the above three wind speeds, and calculate the blade root bending moment M xy The envelope values ​​of the load are counted, and the maximum envelope values ​​under the three wind speeds are L1, L2 and L3 respectively. The load threshold should be set greater than the maximum value among L1, L2 and L3.

[0020] The second object of the present invention is achieved by the following technical solution: a blade root limit load control system based on blade root combined bending moment, used to implement the above-mentioned blade root limit load control method based on blade root combined bending moment, comprising:

[0021] The blade root bending moment calculation module calculates the blade root bending moment of each blade based on the measured in-plane load and out-of-plane load of the blade root;

[0022] An envelope value acquisition module is used to obtain the maximum value of the blade root combined bending moment of all blades after filtering, and then further obtain an envelope value based on the maximum value;

[0023] The load threshold setting module is used to set the load threshold. The principle is that the steady-state wind should not be affected, that is, the set load threshold should be greater than the envelope value of the maximum blade root bending moment of the steady-state wind;

[0024] The pitch angle superposition calculation module is used to calculate the pitch angle superposition by multiplying the difference between the envelope value of the blade root combined bending moment and the set load threshold by the set proportional coefficient, and then the unit executes the corresponding pitch change instruction based on this pitch angle superposition.

[0025] The third objective of the present invention is achieved through the following technical solution: a storage medium stores a program, and when the program is executed by a processor, the above-mentioned blade root limit load control method based on blade root combined bending moment is implemented.

[0026] The fourth objective of the present invention is achieved through the following technical solution: a computing device, comprising a processor and a memory for storing a program executable by the processor, wherein when the processor executes the program stored in the memory, the above-mentioned blade root limit load control method based on blade root combined bending moment is implemented.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] 1. The present invention is based on the blade root in-plane load M measured by the wind turbine generator set. x and the out-of-plane load M y Calculate the blade root bending moment M xy , and then based on the blade root bending moment M xy To output the pitch angle superposition to reduce the load, and the blade root bending moment M xy The actual output moment M of the blade xy The basic overlap makes load reduction more reasonable and efficient.

[0029] 2. The present invention only has a blade root bending moment M xy When the set load threshold is exceeded, the pitch angle is superimposed and the variable pitch angle range is relatively smaller, so the power fluctuation is smaller and the power generation loss is also less.

[0030] 3. The logic of the present invention is that as long as the blade root bending moment M xy When the set load threshold is exceeded, the pitch angle can be superimposed to reduce the load. This is not limited to wind speeds near or below the rated value, and the applicable wind speed range is wider. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The control principle diagram of the method of the present invention.

[0032] Figure 2 Schematic diagram of the leaf root coordinate system.

[0033] Figure 3 Schematic diagram of the system of the present invention. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0035] Example 1

[0036] This embodiment discloses a blade root limit load control method based on blade root combined bending moment. The method calculates the blade root combined bending moment of each blade based on the measured blade root in-plane load and out-of-plane load, and takes the blade root combined bending moment M of all blades as xy The maximum value is obtained, and the envelope of the maximum value is taken. The difference between the envelope value and the set load threshold is multiplied by the set proportional coefficient to obtain the pitch angle superposition, so that the wind turbine generator set executes the pitch change command when the blade root combined bending moment rises above the set load threshold, thereby achieving the purpose of load reduction. Figure 1 As shown, the details of this method are as follows:

[0037] Stress sensors are installed at the root positions of all blades of the wind turbine to measure the root in-plane load M of each corresponding blade. x and the out-of-plane load M y The stress sensor converts the deformation of the strain gauge into a resistance or voltage output with a linear or arbitrary function relationship. Assuming that the unit has N blades, the distance between the blade root predetermined position P1 of blade 1 and the blade root position is X1, the distance between the blade root predetermined position P2 of blade 2 and the blade root position is X2, and the distance between the blade root predetermined position P N The distance from the blade root is X N , blade root predetermined position P1, P2, ..., P N is the actual stress sensor installation position, distance X1, X2, ..., X N is the distance between the sensor position and the blade root, X1, X2, ..., X N Calibration needs to be carried out according to the actual on-site conditions.

[0038] The measured blade root in-plane load M x and the out-of-plane load M y After high-pass filtering, the blade root bending moment M is obtained by calculation. xy , the calculation formula is as follows:

[0039]

[0040] like Figure 2 As shown, taking a three-blade unit as an example, the blade root coordinate system is within the range that can be understood by ordinary technicians in this field. x is the thrust in the direction of the incoming wind speed, F y is the thrust perpendicular to the transmission chain direction, F z is the force perpendicular to the XY plane, M x 、M y 、M z The bending moment is caused by the forces in three directions.

[0041] The calculated root bending moment M of each bladexy Filter and then take the root bending moment M of all blades xy The maximum value after filtering is further used to obtain the envelope value based on the maximum value. The purpose of taking the envelope value is to make the load fluctuation used to calculate the pitch angle superposition smaller, so that the pitch angle superposition is relatively more stable and lasts longer, so the load reduction effect is better. The specific method is: Assuming that the current time is T i , the corresponding maximum root bending moment of all blades is M xy The filter value is L i ; The last moment is T i-1 , the corresponding maximum root bending moment of all blades is M xy The filter value is L i-1 ; The last time is T i-2 , the corresponding maximum root bending moment of all blades is M xy The filter value is L i-2 ; T i Moment and T i-1 The difference in time is (L i -L i-1 ), T i-1 Moment and T i-2 The difference in time is (L i-1 -L i-2 ), if (L i -L i-1 )×(L i-1 -L i-2 ) is less than zero and (L i -L i-1 ) is also less than zero, then the maximum root bending moment of all blades at the current moment is M xy Filter value L i is the envelope value, otherwise the maximum root bending moment M of all blades at the previous moment is used. xy Filter value L i-1 as the envelope value.

[0042] The load threshold is set in principle so that it cannot affect the steady-state wind, that is, the set load threshold should be greater than the maximum blade root bending moment M of the steady-state wind. xy The specific method is as follows: take three wind speeds W1, W2 and W3, which represent the wind speed below the rated value, the rated wind speed and the wind speed above the rated value, respectively, and perform simulations at the above three wind speeds, and calculate the blade root bending moment M xy The envelope values ​​of the load are counted, and the maximum envelope values ​​under the three wind speeds are L1, L2 and L3 respectively. The load threshold should be set greater than the maximum value among L1, L2 and L3.

[0043] The blade root bending moment M xyThe difference between the envelope value and the set load threshold is multiplied by the set proportional coefficient to obtain the pitch angle superposition, and then the unit executes the corresponding pitch change command based on the pitch angle superposition to achieve the purpose of load reduction; the proportional coefficient is adjusted according to the actual load reduction demand and load reduction effect.

[0044] Example 2

[0045] This embodiment discloses a blade root limit load control system based on blade root combined bending moment, which is used to implement the blade root limit load control method based on blade root combined bending moment described in Example 1. Figure 3 As shown, including:

[0046] The blade root bending moment calculation module calculates the blade root bending moment of each blade based on the measured in-plane load and out-of-plane load of the blade root;

[0047] An envelope value acquisition module is used to obtain the maximum value of the blade root combined bending moment of all blades after filtering, and then further obtain an envelope value based on the maximum value;

[0048] The load threshold setting module is used to set the load threshold. The principle is that the steady-state wind should not be affected, that is, the set load threshold should be greater than the envelope value of the maximum blade root bending moment of the steady-state wind;

[0049] The pitch angle superposition calculation module is used to calculate the pitch angle superposition by multiplying the difference between the envelope value of the blade root combined bending moment and the set load threshold by the set proportional coefficient, and then the unit executes the corresponding pitch change instruction based on this pitch angle superposition.

[0050] Example 3

[0051] This embodiment discloses a storage medium storing a program. When the program is executed by a processor, the blade root limit load control method based on the blade root combined bending moment described in Embodiment 1 is implemented.

[0052] The storage medium in this embodiment can 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.

[0053] Example 4

[0054] 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 blade root limit load control method based on the blade root combined bending moment described in Example 1 is implemented.

[0055] 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.

[0056] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. Blade root limit load control method based on blade root combined bending moment, It is characterized in that The method calculates the root resultant bending moment of each blade based on the measured in-plane load and out-of-plane load of the blade root, takes the maximum value of the root resultant bending moment of all blades, and takes the envelope of the maximum value. The difference between the envelope value and the set load threshold is multiplied by the set proportional coefficient to obtain the pitch angle superposition amount, so that the wind turbine executes the pitch change command when the root resultant bending moment rises above the set load threshold, thereby achieving the purpose of load reduction.

2. The blade root limit load control method based on blade root combined bending moment according to claim 1, It is characterized in that The following steps are involved: In-plane load on blade root M x and the out-of-plane load M y High-pass filtering is performed, and then based on the filtered blade root in-plane load M x and the out-of-plane load M y Calculate the root bending moment M of each blade xy And filter, take the root bending moment M after filtering of all blades xy The maximum value of If the maximum root bending moment of all blades at the current moment is M xy The filtered value and the maximum root bending moment M of all blades at the previous moment xy The difference of the filtered values ​​multiplied by the maximum root bending moment M of all blades at the previous moment xy The filtered value and the maximum root bending moment M of all blades at the previous moment xy The difference of the filtered values ​​is less than zero and the maximum root bending moment M of all blades at the current moment xy The filtered value and the maximum root bending moment M of all blades at the previous moment xy The difference of the filtered values ​​is also less than zero, so the maximum root bending moment of all blades at the current moment is M xy The filtered value is the envelope value, otherwise the maximum root bending moment M of all blades at the previous moment is used. xy The filtered value is used as the envelope value; The load threshold is set in principle so that it cannot affect the steady-state wind, that is, the set load threshold should be greater than the maximum blade root bending moment M of the steady-state wind. xy The specific method is as follows: first simulate three steady-state wind conditions below the rated wind speed, rated wind speed and above the rated wind speed, and calculate the maximum blade root bending moment M under the three steady wind conditions xy The load threshold should be set to be greater than the maximum blade root bending moment M under the three steady-state wind conditions. xy The maximum value in the envelope value of ; The blade root bending moment M xy The difference between the envelope value and the set load threshold is multiplied by the set proportional coefficient to obtain the pitch angle superposition, and then the unit executes the corresponding pitch change instruction based on this pitch angle superposition.

3. The blade root limit load control method based on blade root combined bending moment according to claim 2, It is characterized in that Stress sensors are installed at the root positions of all blades of the wind turbine to measure the root in-plane load M of each corresponding blade. x and the out-of-plane load M y The stress sensor converts the deformation of the strain gauge into a resistance or voltage output with a linear or arbitrary function relationship. Assuming that the unit has N blades, the root of blade 1 is at a predetermined position P 1 The distance from the blade root is X 1 , the blade root predetermined position P of blade 2 2 The distance from the blade root is X 2 , the blade root predetermined position P of blade N N The distance from the blade root is X N , blade root predetermined position P 1 ,P 2 ,...,P N is the actual stress sensor installation position, distance X 1 ,X 2 ,...,X N is the distance from the sensor position to the blade root, X 1 ,X 2 ,...,X N Calibration needs to be carried out according to actual site conditions.

4. The blade root limit load control method based on blade root combined bending moment according to claim 2, It is characterized in that The measured blade root in-plane load M x and the out-of-plane load M y After high-pass filtering, the blade root bending moment M is obtained by calculation. xy , the calculation formula is as follows:

5. The blade root limit load control method based on blade root combined bending moment according to claim 2, It is characterized in that The calculated root bending moment M of each blade xy Filter and then take the root bending moment M of all blades xy The maximum value after filtering is further used to obtain the envelope value based on the maximum value. The specific method is as follows: Assuming that the current time is T i , the corresponding maximum root bending moment of all blades is M xy The filter value is L i ; The last moment is T i-1 , the corresponding maximum root bending moment of all blades is M xy The filter value is L i-1 ; The last time is T i-2 , the corresponding maximum root bending moment of all blades is M xy The filter value is L i-2 ; T i Moment and T i-1 The difference in time is (L i -L i-1 ), T i-1 Moment and T i-2 The difference in time is (L i-1 -L i-2 ), if (L i -L i-1 )×(L i-1 -L i-2 ) is less than zero and (L i -L i-1 ) is also less than zero, then the maximum root bending moment of all blades at the current moment is M xy Filter value L i is the envelope value, otherwise the maximum root bending moment M of all blades at the previous moment is used. xy Filter value L i-1 as the envelope value.

6. The blade root limit load control method based on blade root combined bending moment according to claim 2, It is characterized in that The specific method of setting the load threshold is: take 3 wind speeds W 1 , W 2 and W 3 , respectively represent wind speeds below rated, rated and above rated. Simulations are performed at the above three wind speeds, and the blade root bending moment M xy The envelope values ​​of the three wind speeds are statistically analyzed. The maximum envelope values ​​under the three wind speeds are L 1 , L 2 and L 3 , the load threshold should be set greater than L 1 , L 2 and L 3 The maximum value in .

7. Blade root limit load control system based on blade root combined bending moment, It is characterized in that A blade root limit load control method based on blade root combined bending moment for realizing any one of claims 1 to 6, comprising: The blade root bending moment calculation module calculates the blade root bending moment of each blade based on the measured in-plane load and out-of-plane load of the blade root; An envelope value acquisition module is used to obtain the maximum value of the blade root combined bending moment of all blades after filtering, and then further obtain an envelope value based on the maximum value; The load threshold setting module is used to set the load threshold. The principle is that the steady-state wind should not be affected, that is, the set load threshold should be greater than the envelope value of the maximum blade root bending moment of the steady-state wind; The pitch angle superposition calculation module is used to calculate the pitch angle superposition by multiplying the difference between the envelope value of the blade root combined bending moment and the set load threshold by the set proportional coefficient, and then the unit executes the corresponding pitch change instruction based on this pitch angle superposition.

8. A storage medium storing a program, It is characterized in that When the program is executed by a processor, the blade root limit load control method based on the blade root combined bending moment according to any one of claims 1 to 6 is implemented.

9. A computing device comprising a processor and a memory for storing a program executable by the processor, It is characterized in that When the processor executes the program stored in the memory, the blade root limit load control method based on the blade root combined bending moment according to any one of claims 1 to 6 is implemented.

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