An aerodynamic design method and system for constant speed and constant pitch wind turbines

Abstract

This invention discloses an aerodynamic design method and system for a constant-speed, constant-pitch wind turbine. Based on design requirements and battery characteristics, the rated wind speed, rated power, and transmission efficiency are determined; the initial value of the rotor diameter is estimated; the initial value of the rotor's rated rotational speed and the initial value of the design wind speed are predicted; a design section is selected based on the initial value of the rotor diameter; aerodynamic design is performed on each design section at the initial value of the design wind speed; based on the designed blade parameters, aerodynamic calculations are performed on the designed blades to obtain the electrical power at rated wind speed *a*, wind speed *a-1*, and wind speed *a+1*; based on the error between the power at rated wind speed *a* and the rated power obtained from the initial module, the rotor diameter is automatically corrected; and based on the power variation trend near rated wind speed *a*, the initial value of the design wind speed is corrected. This invention is simple and reliable, keeping the error between the power at rated wind speed and the expected rated power within the error range, requiring no manual operation, and greatly reducing labor costs.

Description

Technical Field

[0001] This invention belongs to the field of wind power generation technology, specifically relating to an aerodynamic design method and system for a constant speed and constant pitch wind turbine. Background Technology

[0002] Small off-grid wind turbines typically have a power output of less than 10kW and operate independently of the power grid. Their electrical energy is primarily stored in batteries, and they can be widely applied in remote areas for residential power supply, electric vehicle battery charging, electric vehicle charging, rural public lighting, highway signaling and lighting, border outposts, and island power supply. Their cost is significantly lower than long-distance, low-load power supply from the grid. Therefore, small off-grid wind turbines have excellent development prospects. Aerodynamic design is one of the key factors influencing the design and reliable operation of small off-grid wind turbines.

[0003] The main task of wind turbine aerodynamic design is to determine the optimal blade geometry based on the primary requirements of the application scenario, including the design of airfoil, chord length, and twist angle parameters. For existing mainstream large wind turbines, the main goal of aerodynamic design is to improve rotor conversion efficiency. Above rated wind speed, pitch control technology is often used to limit the maximum power output of the rotor to prevent excessive power from causing excessive load and generator damage. However, for small off-grid wind turbines, the blade size is smaller, and the pitch mechanism occupies relatively large space and is relatively expensive, making pitch control unsuitable for widespread application. Therefore, small off-grid wind turbines can be designed as stall-type turbines, ensuring they enter a stall state at the rated wind speed, utilizing their stall characteristics to limit the maximum captured power of the rotor. However, existing stall-type aerodynamic design methods often cannot ensure that the stall state is entered at the designated rated wind speed. If the stall state is entered too early, energy loss will occur, and the generator will not be able to operate at the rated operating point for a long time. If the stall state is entered too late, the power captured by the wind turbine may exceed the allowable load of the generator or battery, causing overspeed, overcurrent and other faults.

[0004] Therefore, developing an aerodynamic design method for constant-speed, constant-pitch wind turbines that can prepare for stall at a specified rated wind speed is of great significance for ensuring the safety and reliability of small off-grid wind turbines and promoting their application. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an aerodynamic design method and system for constant speed and constant pitch wind turbines, which addresses the shortcomings of the prior art and improves the stall characteristics of stall-type wind turbines and enhances the stability of small wind turbines at high wind speeds, thereby solving the technical problem of overload of small wind turbines at high wind speeds.

[0006] The present invention adopts the following technical solution:

[0007] This invention discloses an aerodynamic design method for a constant-speed, constant-pitch wind turbine, comprising the following steps:

[0008] S1. Determine the rated wind speed point a, rated power b, and transmission efficiency c based on design requirements and battery characteristics.

[0009] S2. Estimate the initial value of the wind turbine diameter e0 based on the rated wind speed point a, rated power b, and transmission efficiency c obtained in step S1.

[0010] S3. Based on the rated wind speed point a obtained in step S1 and the initial value of the wind turbine diameter e0 obtained in step S2, estimate the initial value of the rated wind turbine rotation speed g0.

[0011] S4. Based on the initial value of the wind turbine diameter e0 obtained in step S2 and the initial value of the wind turbine rated speed g0 obtained in step S3, estimate the initial value of the design wind speed h0.

[0012] S5. Select the design section based on the initial value e0 of the wind turbine diameter obtained in step S2;

[0013] S6. At the initial design wind speed h0 obtained in step S4, perform aerodynamic design on each design section selected in step S5 to determine the blade parameters.

[0014] S7. Based on the blade parameters designed in step S6, perform aerodynamic calculations on the designed blades to obtain the electrical power t1, t2, t3 at rated wind speed a, wind speed a-1, and wind speed a+1.

[0015] S8. Based on the error between the power t1 obtained in step S7 and the rated power b obtained in step S1, and using the initial value of the wind turbine diameter e0 obtained in step S2 as the initial value of the iteration, the wind turbine diameter e is automatically iterated and corrected, and the process returns to step S5; S9. Based on the power values ​​t1, t2, and t3 obtained in step S7, and using the initial value of the design wind speed h0 obtained in step S4 as the initial value of the iteration, the design wind speed h is automatically iterated and corrected, and the process returns to step S6.

[0016] S10. Repeat steps S7 to S9. When the wind turbine stalls at a specified wind speed and the stall power is the rated power, determine the blade parameters and complete the aerodynamic design of the constant speed and constant pitch wind turbine.

[0017] Specifically, in step S2, the initial value of the wind turbine diameter e0 is as follows:

[0018]

[0019] Where g is the inflow density and d0 is the wind energy utilization coefficient at the stall point of the rated wind speed.

[0020] Specifically, in step S3, the initial value of the rated speed g0 of the wind turbine is:

[0021]

[0022] Where f is the tip speed ratio at the rated wind speed point where the blade stalls.

[0023] Specifically, in step S4, the wind speed estimate h0 is:

[0024]

[0025] Where i is the angle of attack at which the airfoil has the highest lift-to-drag ratio.

[0026] Specifically, in step S5, the condition for selecting the design section is: the section density at the blade tip is greater than the section density at other locations.

[0027] Specifically, step S6 is as follows:

[0028] S601. Based on the Wilson design method, considering the optimization objective of maximizing the wind energy utilization coefficient at the initial design wind speed h0 and the energy constraint condition based on potential flow theory, solve for the axial induction factor m and the tangential induction factor n.

[0029] S602. Based on the axial induction factor m and tangential induction factor n obtained in step S601, calculate the inflow angle o, twist angle p and chord length q of each section of the blade.

[0030] Furthermore, the inflow angle θ, twist angle p, and chord length q of each section are as follows:

[0031] The inflow angle θ at each cross-section is:

[0032]

[0033] The torsion angle p of each section is:

[0034] p = oi

[0035] The chord length q of each section is:

[0036]

[0037] Where r is the airfoil lift coefficient at the maximum lift-to-drag ratio angle of attack, s is the airfoil drag coefficient at the maximum lift-to-drag ratio angle of attack, k is the distance from the blade root at each section, and L(m,n) is the tip loss factor at each section.

[0038] Specifically, in step S8, the automatic correction of the wind turbine diameter e is as follows:

[0039] If the error |b-t1|>u, according to e=e+k e(b-t1) Correct the rotor diameter and feed it back to step S5; if the error |b-t1|≤u, then do not correct the rotor diameter, where u is a positive constant; k e It is a positive number.

[0040] Specifically, in step S9, the initial value of the design wind speed is corrected as follows:

[0041] If t1>t2 and t1≥t3, the stall point is near the rated wind speed point a. No correction is made. Output the chord length and twist angle values ​​of the current iteration step and end the blade aerodynamic design process.

[0042] If t3≥t1>t2, the stall point is to the right of the rated wind speed point a. Correct the initial design wind speed value: h=h-0.1, and feed it back to step S6;

[0043] Otherwise, if the stall point is to the left of the rated wind speed point a, the initial design wind speed value is corrected: h = h + 0.1, and fed back to step S6.

[0044] Secondly, embodiments of the present invention provide an aerodynamic design system for a constant-speed, constant-pitch wind turbine, comprising:

[0045] The initial module determines the rated wind speed point a, rated power b, and transmission efficiency c based on design requirements and battery characteristics, and estimates the initial value of the wind turbine diameter e0.

[0046] The estimation module estimates the initial value of the rated wind speed g0 of the wind turbine based on the rated wind speed point a and the initial value of the wind turbine diameter e0 obtained from the initial module, and estimates the initial value of the design wind speed h0 based on the initial value of the wind turbine diameter e0 and the initial value of the wind turbine rated speed g0.

[0047] Select the module and choose the design section based on the initial value e0 of the wind turbine diameter obtained from the estimation module;

[0048] The calculation module performs aerodynamic design on each design section selected by the selection module at the initial design wind speed h0 obtained by the estimation module to determine the blade parameters. Based on the blade parameters, it performs aerodynamic calculation on the designed blade to obtain the electric power t1, t2, t3 at rated wind speed a, wind speed a-1, and wind speed a+1.

[0049] The design module, based on the error between the power t1 at the rated wind speed a obtained by the calculation module and the rated power b obtained by the initial module, uses the initial value e0 of the rotor diameter obtained by the initial module as the initial value for iteration, automatically iterates and corrects the rotor diameter e, and returns to the selection module. Based on the power values ​​t1, t2, t3 obtained by the calculation module, and using the initial value h0 of the design wind speed obtained by the estimation module as the initial value for iteration, it automatically iterates and corrects the design wind speed h, and returns to the calculation module. When stalling at a specified wind speed point and the stall power is the rated power, the final blade parameters are determined, and the aerodynamic design of the constant speed and constant pitch wind turbine is completed.

[0050] Compared with the prior art, the present invention has at least the following beneficial effects:

[0051] This invention discloses an aerodynamic design method for constant-speed, constant-pitch wind turbines, targeting small wind turbines. It specifies the rated wind speed and rated power, requiring the turbine to stall at the rated wind speed while still achieving the rated power demand. The method estimates the initial values ​​of the rotor diameter, rated rotational speed, and design wind speed, reducing the number of iterations. A wind speed lower than the rated wind speed is selected, and the model is designed to maximize energy at the initial design wind speed. The design process is based on the Wilson method, considering tip loss correction, thus improving the design accuracy at the blade tip. After obtaining the blade aerodynamic design parameters, the aerodynamic design level can be verified by performing aerodynamic performance calculations. The power results calculated from aerodynamic performance are fed back to the aerodynamic design stage to correct the rotor diameter and design wind speed, ultimately ensuring that the wind turbine stalls at the specified rated wind speed point and reaches the rated power requirement. The correction method of this invention is simple and reliable. It uses the power change trend to evaluate the stall point location, ensuring that the error between the stall point and the rated wind speed point is within a certain range. It uses the error between the power t1 at the rated wind speed a and the expected rated power b specified in step S1 to ensure that the error between the power at the rated wind speed and the expected rated power is kept within a certain error range. The correction method does not require manual operation but is automatically iterated, which can greatly reduce labor costs.

[0052] Furthermore, by using data on rated wind speed, rated power, and transmission efficiency to estimate the initial value of the wind turbine diameter, we can reduce the number of iterative corrections to the wind turbine diameter and avoid problems such as non-convergence in aerodynamic design and calculation processes caused by an unreasonable selection of the initial value of the wind turbine diameter.

[0053] Furthermore, by estimating the initial value of the wind turbine's rated speed g0 based on the approximate value of the tip speed ratio at stall, the probability of the wind turbine stalling at the rated wind speed point can be increased, the number of iterative corrections for the design wind speed can be reduced, and the problem of non-convergence in the aerodynamic design and aerodynamic calculation process caused by an unreasonable selection of the initial value of the wind turbine's rated speed can be prevented.

[0054] Furthermore, the initial design wind speed is estimated based on the optimal angle of attack with the largest lift ratio. On the one hand, the largest lift ratio can ensure the optimal power output characteristics of the wind turbine, so that the wind turbine utilization efficiency at the design wind speed point is maximized. On the other hand, it can reduce the number of iterative corrections to the design wind speed.

[0055] Furthermore, when selecting the blade design section, since the tip loss and the work contribution of the blade near the tip are greater, the gradient of the aerodynamic load with respect to the blade span is larger. It is beneficial to make the section closer to the tip denser to improve the design accuracy, and to make the section in other positions relatively sparse to improve the design and calculation efficiency.

[0056] Furthermore, the aerodynamic design process takes into account the tip loss factor, which improves the accuracy of aerodynamic design.

[0057] Furthermore, by correcting the rotor diameter e based on the difference between the power calculated at the rated wind speed and the specified rated power, the error between the power at the rated wind speed and the expected rated power can be kept within a certain error range. This correction method is simple, reliable, and requires no manual operation; instead, it is automatically iterated, which can greatly reduce labor costs.

[0058] Furthermore, the design wind speed point h is corrected based on the power variation trend near the rated wind speed in step S7. The stall operating point location is evaluated using the power variation trend, which can ensure that the error between the stall point and the rated wind speed point is within a certain range. This correction method is simple, reliable, and requires no manual operation; instead, it is automatically iterated, which can greatly reduce labor costs.

[0059] It is understood that the beneficial effects of the second and third aspects mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here.

[0060] In summary, this invention ensures the design accuracy of the cross-section near the blade tip, and the correction method is simple, reliable, and requires no manual operation.

[0061] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0062] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0063] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0064] In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0065] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0066] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this document generally indicates that the preceding and following objects have an "or" relationship.

[0067] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0068] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0069] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0070] This invention provides an aerodynamic design method for a constant-speed, constant-pitch wind turbine. Based on design requirements and battery characteristics, the rated wind speed point *a*, rated power *b*, and transmission efficiency *c* are determined, and the initial value of the rotor diameter *e0* is estimated. Based on the rated wind speed point *a* and the initial value of the rotor diameter *e0*, the initial value of the rotor's rated rotational speed *g0* is estimated. Based on the initial value of the rotor diameter *e0* and the initial value of the rotor's rated rotational speed *g0*, the initial value of the design wind speed *h0* is estimated. A design section is selected based on the initial value of the rotor diameter *e0*. Aerodynamic design is performed on each design section selected by the selection module at the initial value of the design wind speed *h0*, based on the designed blade parameters. Aerodynamic calculations are performed on the designed blades to obtain the electrical power t1, t2, and t3 at rated wind speeds a, a-1, and a+1. Based on the error between the power t1 at rated wind speed a and the rated power b obtained from the initial module, the rotor diameter e is automatically corrected. The design section is then reselected, and the initial value h of the design wind speed is corrected based on the power variation trend near the rated wind speed a. The aerodynamic design of each design section is then completed again. When the turbine stalls at a specified wind speed point and the stall power is the rated power, the blade parameters are determined, and the aerodynamic design of the constant speed and constant pitch wind turbine is completed.

[0071] Please see Figure 1 The present invention discloses an aerodynamic design method for a constant-speed, constant-pitch wind turbine, comprising the following steps:

[0072] S1. Determine the rated wind speed point a, rated power b, and transmission efficiency c based on design requirements and battery characteristics.

[0073] Rated wind speed point a is usually determined by the aerodynamic load that the wind turbine can withstand and the rated power value. Rated power b is usually determined by parameters such as the capacity and allowable current of the battery. Transmission efficiency c is jointly determined by the transmission chain and the energy storage and conversion efficiency of the battery.

[0074] It should be noted that the above determination method is for reference only, and the specific determination method should be flexibly handled according to actual needs.

[0075] S2. Based on the rated power b, rated wind speed a and transmission efficiency c obtained in step S1, estimate the initial value of the wind turbine diameter e0.

[0076] First, roughly estimate the wind energy utilization coefficient d0 at the stall point of the rated wind speed. Based on the experience of wind turbine aerodynamic stall, d0 can be taken as 0.1 to 0.2. Then, based on the relationship between the rated power b, the rated wind speed point a, and the transmission efficiency c and the rotor diameter obtained in step S1, estimate the initial value e0 of the rotor diameter as follows:

[0077]

[0078] Where g is the inflow density.

[0079] S3. Based on the rated wind speed point a obtained in step S1 and the initial value of the wind turbine diameter e0 obtained in step S2, estimate the initial value of the rated wind turbine rotation speed g0.

[0080] The tip speed ratio at the rated wind speed point where stall is f. Based on the experience of aerodynamic stall of wind turbines, f = 3. Then the estimated initial value of the rated speed of the wind turbine, g0, is:

[0081]

[0082] By estimating initial values ​​in steps S2 and S3 instead of assigning them arbitrarily, the number of iterations can be reduced.

[0083] S4. Based on the initial value of the wind turbine diameter e0 obtained in step S2 and the initial value of the wind turbine rated speed g0 obtained in step S3, estimate the initial value of the design wind speed h0.

[0084] At the initial design wind speed, the angle of attack is i, which is the angle of attack with the highest lift-to-drag ratio of the airfoil. The maximum lift-to-drag ratio can ensure the best power output characteristics of the wind turbine, so that the wind turbine utilization efficiency at the design point is maximized.

[0085] The estimated wind speed h0 is:

[0086]

[0087] Step S4: At the initial design wind speed, the angle of attack is i, which is the angle of attack with the largest lift-to-drag ratio of the airfoil. The maximum lift-to-drag ratio can ensure the best power output characteristics of the wind turbine, so that the wind turbine utilization efficiency at the design point is maximized.

[0088] S5. Select the design section based on the initial value e0 of the wind turbine diameter obtained in step S2;

[0089] Considering tip losses, the aerodynamic characteristics change significantly near the tip, so the cross-section should be denser, while the cross-section at other locations should be relatively sparser.

[0090] In step S5, on the one hand, there is tip loss, and on the other hand, the work done on the blade near the tip is relatively large, and the gradient of the load change with respect to the blade span is also relatively large. Making the cross section near the tip denser is beneficial to improving design accuracy; making other cross sections relatively sparse is beneficial to improving design and calculation speed.

[0091] S6. Perform aerodynamic design on each design section defined in step S5 at the initial design wind speed value h0 obtained in step S4.

[0092] S601. Based on the Wilson design method, considering the optimization objective of maximizing the wind energy utilization coefficient at the initial design wind speed h0 and the energy constraint condition based on potential flow theory, solve for the axial induction factor m and the tangential induction factor n.

[0093] The aerodynamic design objective function for the section at a distance k from the blade root is:

[0094] n(mL(m,n)-1)L(m,n)

[0095] Leaf tip loss factor is:

[0096]

[0097] The energy constraints based on potential flow theory constitute the constraints for this optimization problem:

[0098]

[0099] The extrema of the above-mentioned nonlinear multivariate function with constraints are solved by using functions such as fmincon. When the extrema are obtained, the corresponding independent variables are the axial induction factor m and the tangential induction factor n, respectively.

[0100] S602. Based on the axial induction factor m and tangential induction factor n obtained in step S601, calculate the inflow angle o, twist angle p and chord length q of each section of the blade.

[0101] The blade length and the chord length and twist angle of each section are the results of the blade aerodynamic design, representing the characteristics of the blade's geometric shape.

[0102] The inflow angle θ at each cross-section is:

[0103]

[0104] The formula for calculating the torsion angle ρ of each section is:

[0105] p = oi

[0106] The formula for calculating the chord length q of each section is:

[0107]

[0108] Where r is the airfoil lift coefficient at the maximum lift-to-drag ratio angle of attack, and s is the airfoil drag coefficient at the maximum lift-to-drag ratio angle of attack.

[0109] S7. Based on the blade parameters designed in step S6, perform aerodynamic calculations on the designed blades to obtain the electrical power t1, t2, t3 at rated wind speed a, wind speed a-1, and wind speed a+1.

[0110] Aerodynamic calculations are based on blade element-momentum theory. Taking wind speed a as an example, tip loss correction is incorporated into the calculation process. First, the induction factors m and n are calculated, and the calculation steps are as follows:

[0111] (1) Initialize factors m and n, setting m = n = 0;

[0112] (2) Calculate the inflow angle θ;

[0113] (3) Calculate the tip loss factor L;

[0114] (3) Calculate the angle of attack α;

[0115] (4) Obtain the lift coefficient C from the table. L (α) and drag coefficient C D (α);

[0116] (5) Calculate the normal and tangential force coefficients C N (α),C T (α);

[0117] (6) Calculate m and n;

[0118] (7) If the changes in m and n in consecutive iterations are greater than the allowable deviation (take 0.001), return to the second step; otherwise, complete the calculation and output the induction factors m, n and the leaf tip loss factor F.

[0119] At the rated wind speed a, after iterative calculations are performed on each section, the torque provided by each section of the blade is calculated based on the induction factors m and n and the tip loss factor F of each section. The aerodynamic torque of a single blade is obtained by integrating along the blade length direction. The aerodynamic torque of the wind turbine is obtained by multiplying it by the number of blades. The aerodynamic torque of the wind turbine is obtained by multiplying it by the rotational speed. The aerodynamic power of the wind turbine is obtained by multiplying it by the transmission efficiency c. The electrical power t1 is obtained by multiplying the aerodynamic torque of the wind turbine by the rotational speed.

[0120] Similarly, the electrical power t2 and t3 at wind speeds a-1 and a+1 can be obtained.

[0121] After the blade aerodynamic design is completed, aerodynamic performance calculations can be performed to verify the level of aerodynamic design. At the same time, the results of the aerodynamic performance calculations can serve as feedback, providing a basis for correcting the blade design.

[0122] Aerodynamic calculations are based on the blade element momentum theory, and the aerodynamic calculation process is a mature theory, which will not be elaborated here.

[0123] S8. Based on the error between the power t1 at the rated wind speed a obtained in step S7 and the rated power b obtained in step S1, the rotor diameter e is automatically corrected.

[0124] If the error |b-t1|>u, then the correction formula for the wind turbine diameter is: e=e+k e (b-t1), and feed it back to step S3;

[0125] If the error |b-t1|≤u, then the wind turbine diameter will not be corrected for the time being.

[0126] Where u is a positive constant; ke It is a positive number.

[0127] The correction method in step S8 is simple and reliable. By utilizing the error between the power t1 at the rated wind speed a and the expected rated power b specified in step S1, the rotor diameter can be adjusted over a wide range to ensure that the error between the power at the rated wind speed a and the expected rated power is kept within a certain error range. This correction does not require manual operation but is automatically iterated, which can greatly reduce labor costs.

[0128] S9. Based on the power variation trend near the rated wind speed in step S7, the initial value of the design wind speed h is corrected.

[0129] Shifting the initial design wind speed left or right allows for adjustment of the stall point location. The power variation trend near the rated wind speed is used to estimate whether the stall point is before or after the rated wind speed point 'a', and then the initial design wind speed value is corrected.

[0130] ① If t1>t2 and t1≥t3, then the stall point is considered to be near the rated wind speed point a, no correction is made, and the blade aerodynamic design process ends.

[0131] ②If t3≥t1>t2, then the stall point is considered to be to the right of the rated wind speed point a. The initial design wind speed is corrected: h=h-0.1, and fed back to step S4.

[0132] ③ Otherwise, it is assumed that the stall point is to the left of the rated wind speed point a, the initial design wind speed value is corrected: h = h + 0.1, and the feedback is sent to step S4;

[0133] Step S9 uses the power change trend to evaluate the stall operating point location, ensuring that the error between the stall point and the rated wind speed point is within a certain range. This correction does not require manual operation but is automatically iterated, which can greatly reduce labor costs.

[0134] In another embodiment of the present invention, an aerodynamic design system for a constant speed and constant pitch wind turbine is provided. This system can be used to implement the above-mentioned aerodynamic design method for a constant speed and constant pitch wind turbine. Specifically, the aerodynamic design system for a constant speed and constant pitch wind turbine includes an initial module, a prediction module, a selection module, a calculation module, and a design module.

[0135] The initial module determines the rated wind speed point a, rated power b, and transmission efficiency c based on design requirements and battery characteristics, and estimates the initial value of the wind turbine diameter e0.

[0136] The estimation module estimates the initial value of the rated wind speed g0 of the wind turbine based on the rated wind speed point a and the initial value of the wind turbine diameter e0 obtained from the initial module, and estimates the initial value of the design wind speed h0 based on the initial value of the wind turbine diameter e0 and the initial value of the wind turbine rated speed g0.

[0137] Select the module and choose the design section based on the initial value e0 of the wind turbine diameter obtained from the estimation module;

[0138] The calculation module performs aerodynamic design on each design section selected by the selection module at the initial design wind speed h0 obtained by the estimation module to determine the blade parameters. Based on the blade parameters, it performs aerodynamic calculation on the designed blade to obtain the electric power t1, t2, t3 at rated wind speed a, wind speed a-1, and wind speed a+1.

[0139] The design module, based on the error between the power t1 at the rated wind speed a obtained by the calculation module and the rated power b obtained by the initial module, uses the initial value e0 of the rotor diameter obtained by the initial module as the initial value for iteration, automatically iterates and corrects the rotor diameter e, and returns to the selection module. Based on the power values ​​t1, t2, t3 obtained by the calculation module, and using the initial value h0 of the design wind speed obtained by the estimation module as the initial value for iteration, it automatically iterates and corrects the design wind speed h, and returns to the calculation module. When stalling at a specified wind speed point and the stall power is the rated power, the final blade parameters are determined, and the aerodynamic design of the constant speed and constant pitch wind turbine is completed.

[0140] In summary, the present invention provides an aerodynamic design method and system for a constant-speed, constant-pitch wind turbine. First, it estimates the initial values ​​of the rotor diameter, rotor speed, and design wind speed, reducing the number of corrections required for the rotor diameter and design wind speed. Then, it performs blade aerodynamic design considering the tip loss factor, ensuring the design accuracy of the section near the blade tip. After obtaining the blade aerodynamic design parameters, it feeds the power results calculated from the aerodynamic performance back to the aerodynamic design stage, iteratively correcting the rotor diameter and design wind speed. Ultimately, it ensures that the wind turbine stalls at the specified rated wind speed and meets the rated power requirement. The correction method is simple, reliable, and requires no manual operation.

[0141] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0142] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0143] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0144] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0145] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method of aerodynamic design of a fixed speed, fixed pitch wind turbine, characterized in that, The method comprises the following steps: S1, determining a rated wind speed point a, a rated power b and a transmission efficiency c according to design requirements and battery characteristics; S2, estimating an initial value e0 of a wind wheel diameter according to the rated wind speed point a, the rated power b and the transmission efficiency c obtained in step S1; S3, estimating an initial value g0 of a rated rotating speed of the wind wheel according to the rated wind speed point a obtained in step S1 and the initial value e0 of the wind wheel diameter obtained in step S2; S4, estimating an initial value h0 of a design wind speed according to the initial value e0 of the wind wheel diameter obtained in step S2 and the initial value g0 of the rated rotating speed of the wind wheel obtained in step S3; S5, selecting a design section according to the initial value e0 of the wind wheel diameter obtained in step S2; S6, performing aerodynamic design on each design section selected in step S5 at the initial value h0 of the design wind speed obtained in step S4 to determine blade parameters, specifically: S601, solving an axial induction factor m and a tangential induction factor n based on a Wilson design method, considering that maximum wind energy utilization coefficient at the initial value h0 of the design wind speed is an optimization target and an energy constraint condition based on a potential flow theory; S602, calculating an inflow angle o, a twist angle p and a chord length q of each section of the blade according to the axial induction factor m and the tangential induction factor n obtained in step S601, specifically: The inflow angle o of each section is: The twist angle p of each section is: The chord length q of each section is: wherein r is the airfoil lift coefficient at the maximum lift-drag ratio angle of attack, i is the angle of attack at which the airfoil has the maximum lift-drag ratio, s is the airfoil drag coefficient at the maximum lift-drag ratio angle of attack, is the distance of each section from the blade root, is the tip loss factor for each section; S7, performing aerodynamic calculation on the designed blade based on the blade parameters designed in step S6 to obtain electric powers t1, t2 and t3 under the rated wind speed a, a wind speed a-1 and a wind speed a+1; S8, performing automatic iterative correction on the wind wheel diameter e with the initial value e0 of the wind wheel diameter obtained in step S2 as an iterative initial value according to an error between the power t1 obtained in step S7 and the rated power b obtained in step S1, and returning to step S5; S9, performing automatic iterative correction on the design wind speed h with the initial value h0 of the design wind speed obtained in step S4 as an iterative initial value according to the power values t1, t2 and t3 obtained in step S7, and returning to step S6; S10, repeating steps S7-S9, and determining final blade parameters when the blade parameters stall at a specified wind speed point and the stalling power is the rated power, thereby completing aerodynamic design of the constant-speed constant-pitch wind turbine generator set.

2. The aerodynamic design method of a fixed speed, fixed pitch wind turbine according to claim 1, characterized in that, In step S2, the initial value e0 of the wind wheel diameter is specifically: Wherein, g is an inflow density, and d0 is a wind energy utilization coefficient when the rated wind speed point stalls.

3. The aerodynamic design method of a fixed speed, fixed pitch wind turbine according to claim 1, characterized in that, In step S3, the initial value g0 of the rated rotating speed of the wind wheel is: Wherein, f is a tip speed ratio when the rated wind speed point stalls.

4. The aerodynamic design method of a fixed speed, fixed pitch wind turbine of claim 1, wherein, In step S4, the wind speed estimation value h0 is: Wherein, i is an attack angle at which the airfoil lift-drag ratio is maximum.

5. The aerodynamic design method of a fixed speed, fixed pitch wind turbine according to claim 1, characterized in that, In step S5, the condition for selecting the design section is that the sectional density at the tip is greater than the sectional density at other positions.

6. The aerodynamic design method of a fixed speed, fixed pitch wind turbine of claim 1, wherein, In step S8, the automatic correction on the wind wheel diameter e is specifically: if the error , according to corrects the wind wheel diameter and feeds back to step S5; if the error , the wind wheel diameter is not corrected, is a normal number; is a normal number.

7. The aerodynamic design method of a fixed speed, fixed pitch wind turbine of claim 1, wherein, In step S9, the correction on the initial value of the design wind speed is specifically: If and , the stall point is near the rated wind speed point a, no correction is made, and the chord length and twist angle values of the current iteration step are output, and the blade aerodynamic design process is ended. If , the stall point is on the right side of the rated wind speed point a, the initial value of the design wind speed is corrected: h = h - 0.1, and fed back to step S6; Otherwise, the stalling point is on the left side of the rated wind speed point a, the initial value of the design wind speed is corrected as h=h+0.1, and is fed back to step S6.

8. A fixed speed, fixed pitch wind turbine aerodynamic design system, characterized by, The method comprises the following steps: The initial module determines the rated wind speed point a, the rated power b and the transmission efficiency c according to the design requirement and the battery characteristics, and estimates the initial value e0 of the wind wheel diameter; The estimation module estimates the initial value g0 of the rated rotating speed of the wind wheel according to the rated wind speed point a and the initial value e0 of the wind wheel diameter obtained by the initial module, and estimates the initial value h0 of the design wind speed according to the initial value e0 of the wind wheel diameter and the initial value g0 of the rated rotating speed of the wind wheel; The selection module selects the design section according to the initial value e0 of the wind wheel diameter obtained by the estimation module; The calculation module performs aerodynamic design on each design section selected by the selection module at the initial value h0 of the design wind speed obtained by the estimation module to determine the blade parameters, specifically: Based on the Wilson design method, the maximum wind energy utilization coefficient at the initial value h0 of the design wind speed is taken as the optimization objective and the energy constraint condition based on the potential flow theory is considered, the axial induction factor m and the tangential induction factor n are solved; according to the obtained axial induction factor m and tangential induction factor n, the inflow angle o, the twist angle p and the chord length q of each section of the blade are calculated, specifically: The inflow angle o of each section is: The twist angle p of each section is: The chord length q of each section is: Wherein, r is the airfoil lift coefficient at the maximum lift-drag ratio attack angle, i is the airfoil lift-drag ratio maximum attack angle, s is the airfoil drag coefficient at the maximum lift-drag ratio attack angle, is the distance of each section from the blade root, is the tip loss factor of each section, based on the blade parameters, the designed blade is aerodynamically calculated to obtain the electric power t1, t2, t3 under the rated wind speed a, wind speed a-1, wind speed a+1; The design module performs automatic iterative correction on the wind wheel diameter e with the initial value e0 of the wind wheel diameter obtained by the initial module as the initial value of iteration and returns to the selection module according to the error between the power t1 at the rated wind speed a obtained by the calculation module and the rated power b obtained by the initial module, performs automatic iterative correction on the design wind speed h with the initial value h0 of the design wind speed obtained by the estimation module as the initial value of iteration according to the power values t1, t2 and t3 obtained by the calculation module, and returns to the calculation module, when the blade parameters stall at the specified wind speed point and the stall power is the rated power, the final blade parameters are determined, and the aerodynamic design of the constant-speed constant-pitch wind turbine generator set is completed.

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