Load algorithm for ultra-long blade of wind turbine generator under wave flow coupling condition

Abstract

The invention discloses a load algorithm of an ultra-long blade of a wind turbine generator under a wave flow coupling condition, and belongs to the technical field of wind power, and the method comprises the following steps: step 1, calculating a load value of the ultra-long blade of the wind turbine generator under the wave flow coupling condition by using a BEM algorithm; 2, a CFD algorithm is used for calculating the load value of the super-long blade of the wind turbine generator set under the wave flow coupling condition; step 3, comparing the load value in the step 1 with the load value in the step 2; 4, selecting a corresponding correction model according to a comparison result, and correcting the BEM algorithm by using the correction model to obtain a new algorithm model; and 5, calculating the load of the ultra-long blade of the wind turbine generator under the wave flow coupling condition by using the new algorithm model. By correcting the BEM algorithm, the blade load calculation accuracy is improved, the calculation efficiency is also improved, and the problems of low load calculation accuracy and long calculation time in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power, and in particular to a load algorithm for super-long blades of a wind turbine generator set under wave-current coupling conditions. Background Art

[0002] The ultra-long flexible blades of horizontal-axis wind turbines often have characteristics such as high aspect ratio, high linear velocity at the blade tip, large deformation and large displacement. The traditional finite volume method based on body-fitted meshes is difficult to meet the requirements of fast and robust generation of high-quality meshes, unified processing of high and low-speed flow fields, development of fluid-solid coupling calculation methods for large deformation and large displacement, and accurate transmission of flow field information at the dynamic and static interfaces.

[0003] The load calculation algorithm for ultra-long flexible blades in horizontal-axis wind turbines currently typically uses the momentum blade element method (BEM) for load calculation. However, the calculation results of the momentum blade element method (BEM) are inconsistent with the actual values, and it is found that it underestimates the actual unsteady aerodynamic forces. At the same time, the average torque calculated by BEM is large, so the momentum blade element method (BEM) needs to be corrected to improve the calculation accuracy.

[0004] Load calculations for the ultra-long, flexible blades of horizontal-axis wind turbines typically employ CFD algorithms, which offer high accuracy. CFD (Computational Fluid Dynamics) is an interdisciplinary field that uses numerical methods to simulate fluid flow, heat transfer, and related physical processes. Its core approach is to solve the governing equations of fluid dynamics (such as the Navier-Stokes equations), discretizing complex flow problems into numerical solutions at grid nodes to enable "virtual experiments." However, CFD algorithms require high resolution and are computationally inefficient. High-precision transient simulations (such as wind turbine wake analysis) require extremely large grids and long iteration times. Even with GPU acceleration, these simulations can take weeks, making them difficult to meet the demands of rapid engineering iteration. Summary of the Invention

[0005] The purpose of the present invention is to provide a load algorithm for ultra-long blades of a wind turbine under wave-flow coupling conditions, which not only greatly improves the accuracy of calculating the load of ultra-long flexible blades of a horizontal axis wind turbine, but also improves the calculation efficiency.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: A load algorithm for ultra-long blades of a wind turbine under wave-flow coupling conditions includes the following steps: Step 1. Use the BEM algorithm to calculate the load value of the wind turbine's super-long blades under wave-flow coupling conditions; Step 2. Use CFD algorithm to calculate the load value of the wind turbine's super-long blades under wave-flow coupling conditions; Step 3. Compare the load value of step 1 with the load value of step 2; Step 4. Select the corresponding correction model based on the comparison results, and use the correction model to correct the BEM algorithm to obtain a new algorithm model; Step 5. Use the new algorithm model to calculate the load of the wind turbine's ultra-long blades under wave-flow coupling conditions.

[0007] Furthermore, in step 4, the selected correction model is the Prandtl correction model.

[0008] Furthermore, the specific formula of the Prandtl correction model is as follows: The loss correction factor Ft of the wind turbine blade tip with extra-long blades is defined as ; ; The loss correction factor Fr of the blade root of the wind turbine with extra-long blades is defined as: ; , where rn is the hub radius, r n is the hub radius, N b is the turbulence intensity, r is the radial distance from the blade root detection point section to the hub center, R is the radial distance from the blade tip detection point section to the hub center, is the inflow angle; The total aerodynamic loss correction factor of the wind turbine rotor is: .

[0009] Furthermore, in step 4, the new algorithm model is as follows: ; When using the momentum blade method to iteratively solve a and b, we have ; , where dT is the blade pulsation amplitude, dM is the blade torque, unit: Nm; ρ is the air density, unit: kg / m 3 V1 is the incoming wind speed, in m / s; a is the axial induction factor, which indicates the degree of deceleration of the incoming flow velocity at the rotor plane; b is the tangential induction factor, which indicates the tangential velocity increment of the airflow due to blade rotation; F is the total aerodynamic loss correction factor of the wind turbine rotor; is the local solidity of the leaf; C n , C t is the aerodynamic coefficient; Ω is the angular velocity of the wind wheel, unit: rad / s; dr is the number of blades.

[0010] Beneficial effects By modifying the BEM algorithm, this application not only greatly improves the accuracy of calculating the load of ultra-long flexible blades of horizontal-axis wind turbines, but also improves the calculation efficiency, solving the problems of low load calculation accuracy and long calculation time in the existing technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The present invention is further described with reference to the accompanying drawings. However, the embodiments in the accompanying drawings do not limit the present invention in any way. A person skilled in the art can derive other drawings based on the following drawings without inventive effort. Figure 1 is a process flow chart of the present invention; Figure 2 Comparison chart of unsteady torque results obtained by CFD and BEM calculations; Figure 3 This is a comparison chart of the torque results calculated by the BEM, new algorithm model, and CFD of the present invention. DETAILED DESCRIPTION

[0012] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features therein can be combined with each other unless there is a conflict.

[0013] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper surface", "lower surface", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "forward", "reverse", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0014] like Figure 1 As shown, A load algorithm for ultra-long blades of a wind turbine under wave-flow coupling conditions includes the following steps: Step 1. Use the BEM algorithm to calculate the load value of the wind turbine's super-long blades under wave-flow coupling conditions.

[0015] Step 2. Use the CFD algorithm to calculate the load value of the wind turbine's super-long blades under wave-flow coupling conditions.

[0016] Step 3. Compare the load value of step 1 with the load value of step 2.

[0017] Figure 2 shows the unsteady torque results obtained using CFD and BEM calculations. The horizontal axis represents time, and the vertical axis represents unsteady torque. The two lines represent the unsteady torque results obtained using CFD and BEM, respectively. It can be seen that the period calculated using BEM is essentially consistent with the CFD result, but the pulsation amplitude is smaller than the CFD result, indicating that BEM underestimates the unsteady aerodynamic forces. Furthermore, the mean torque obtained using BEM is larger.

[0018] Step 4. Select the corresponding correction model based on the comparison results, and use the correction model to correct the BEM algorithm to obtain a new algorithm model; Step 5. Use the new algorithm model to calculate the load of the wind turbine's ultra-long blades under wave-flow coupling conditions.

[0019] Furthermore, in step 4, the selected correction model is the Prandtl correction model: Define the loss correction factor F for the tip of the wind turbine's extra-long blades t for ; ; Define the loss correction factor F for the root of extra-long blades of wind turbines r for: ; , where r n is the hub radius, N b is the turbulence intensity, r is the radial distance from the blade root detection point section to the hub center, R is the radial distance from the blade tip detection point section to the hub center, is the inflow angle.

[0020] The total aerodynamic loss correction factor of the wind turbine rotor is: .

[0021] Furthermore, in step 4, the new algorithm model is as follows: ; When using the momentum blade method to iteratively solve a and b, we have ; , where dT is the blade pulsation amplitude, dM is the blade torque, unit: Nm; ρ is the air density, unit: kg / m 3 V1 is the incoming wind speed, in m / s; a is the axial induction factor, which indicates the degree of deceleration of the incoming flow velocity at the rotor plane; b is the tangential induction factor, which indicates the tangential velocity increment of the airflow due to blade rotation; F is the total aerodynamic loss correction factor of the wind turbine rotor; is the local solidity of the leaf; C n , Ct is the aerodynamic coefficient; Ω is the angular velocity of the wind wheel, unit: rad / s; dr is the number of blades.

[0022] The unsteady torque results obtained by BEM, new algorithm model and CFD calculations are as follows: Figure 3 As shown in the figure, the horizontal axis is time, the vertical axis is unsteady torque, and the three lines represent BEM, the new algorithm model, and CFD, respectively. It can be seen that the differences between the pulsation amplitude and torque mean calculated by the new algorithm model and the CFD results are further reduced, indicating that the new algorithm model has greatly improved the load accuracy of the ultra-long flexible blades of the horizontal axis wind turbine. Furthermore, the calculation time required using the new algorithm model does not exceed 1 minute, greatly improving computational efficiency.

[0023] In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are mutually inconsistent. Although the embodiments of the present invention have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art may make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A load algorithm for super-long blades of wind turbines under wave-flow coupling conditions, characterized in that: The following steps are involved: Step 1. Use the BEM algorithm to calculate the load value of the wind turbine's super-long blades under wave-flow coupling conditions; Step 2. Use CFD algorithm to calculate the load value of the wind turbine's super-long blades under wave-flow coupling conditions; Step 3. Compare the load value of step 1 with the load value of step 2; Step 4. Select the corresponding correction model based on the comparison results, and use the correction model to correct the BEM algorithm to obtain a new algorithm model; Step 5. Use the new algorithm model to calculate the load of the wind turbine's ultra-long blades under wave-flow coupling conditions.

2. The load algorithm for super-long blades of a wind turbine under wave-flow coupling conditions according to claim 1 is characterized in that: In step 4, the selected correction model is the Prandtl correction model.

3. The load algorithm for super-long blades of wind turbines under wave-flow coupling conditions according to claim 2 is characterized in that: The specific formula of the Prandtl correction model is as follows, which defines the loss correction factor Ft of the wind turbine's extra-long blade tip as: ； ； The loss correction factor Fr of the blade root of the wind turbine with extra-long blades is defined as: ; , where rn is the hub radius, r n is the hub radius, N b is the turbulence intensity, r is the radial distance from the blade root detection point section to the hub center, R is the radial distance from the blade tip detection point section to the hub center, is the inflow angle; The total aerodynamic loss correction factor of the wind turbine rotor is .

4. The load algorithm for super-long blades of a wind turbine under wave-flow coupling conditions according to claim 3 is characterized by: In step 4, the new algorithm model is as follows: ； When using the momentum blade method to iteratively solve a and b, we have ; , where dT is the blade pulsation amplitude, dM is the blade torque, unit: Nm; ρ is the air density, unit: kg / m 3 V1 is the incoming wind speed, in m / s; a is the axial induction factor, which indicates the degree of deceleration of the incoming flow velocity at the rotor plane; b is the tangential induction factor, which indicates the tangential velocity increment of the airflow due to blade rotation; F is the total aerodynamic loss correction factor of the wind turbine rotor; is the local solidity of the leaf; C n , C t is the aerodynamic coefficient; Ω is the angular velocity of the wind wheel, unit: rad / s; dr is the number of blades.

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