A new wake calculation model method for yaw wind turbines

Abstract

This invention provides a novel wake calculation model for a yawed wind turbine, relating to the technical field of wind turbine velocity field calculation. It utilizes a CFD method based on actuating line theory to simulate and calculate the near-wake flow field of the wind turbine. The wake center is then determined using a zero-search method. An improved Jensen model is then used to simulate and calculate the far-wake flow field. In the coupling region, an exponential factor is used to neutralize the CFD and Jensen methods for smoothing calculations. Compared to medium-precision wake models, this coupling method offers higher computational accuracy and lower computational cost than high-precision models, making it more suitable for preliminary estimation calculations in engineering applications.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbine velocity field calculation, and in particular to a novel wake calculation model method for a yawed wind turbine. Background Art

[0002] With the continuous advancement of wind power generation technology, the scale of wind farms is becoming increasingly large, the mutual influence between wind turbines is becoming increasingly complex, and the mutual influence between wind farms is also becoming increasingly greater. In pursuit of higher energy conversion efficiency, modern wind power facilities are developing towards a trend of gigantic and dense layout. This is not only reflected in the expansion of the scale of individual wind turbines, but also in the compact planning of the entire wind farm, striving to deploy more equipment within a limited geographical area. The resulting problem is the impact of the wake effect on the overall performance of the wind farm. Accurately describing the winding of the yaw wind turbine wake is crucial. In previous studies, most yaw analysis models used superposition models to consider the interaction of wind turbine wakes, which would introduce certain errors. This invention proposes a new yaw wind turbine wake calculation model method based on the CFD actuating line model and an improved Jensen wake model for analyzing the yaw of series wind turbines. When a wind turbine yaws or moves, its wake center will inevitably shift. As the wake develops, it will cause large-scale expansion and winding of the wake, which will greatly complicate the prediction of the wake. Accurate tracking of the wake center is crucial. To address the challenges of existing wake center tracking methods when applied to wake models, this paper proposes a zero-point search method. This method overcomes these challenges and makes it applicable to mixed wake models. This method not only achieves wake center tracking but also ensures velocity continuity across mixed models. The goal is to accurately calculate the impact of wind turbine wakes on wind farms, taking into account yaw angles. Summary of the Invention

[0003] The purpose of the present invention is to provide a new yaw wind turbine wake calculation model method, introduce a search zero point method, and solve the problem of insufficient accuracy and applicability of existing wake models in tracking the wake center. In addition, the present invention also uses a tracer particle method to calculate the meandering of the yaw wake, which effectively solves the problem of wind turbine wake prediction considering the yaw factor. The specific implementation method is as follows: a CFD method based on the actuating line theory is used to simulate and calculate the near-wake flow field of the wind turbine, and then the search zero point method is used to determine the wake center, and then the improved Jensen model is used to simulate and calculate the far-wake flow field of the wind turbine, and the coupling area uses an exponential factor to neutralize CFD and Jensen for smoothing calculations. Compared with the medium-precision wake model, the coupling method has higher calculation accuracy; compared with the high-precision model, the coupling method has lower calculation cost and is suitable for preliminary estimated calculations in engineering.

[0004] To achieve the above objectives, the present invention provides a novel yaw wind turbine wake calculation model method comprising the following steps:

[0005] S1. When performing numerical simulation of the wind turbine wake effect, the calculation domain is divided into three regions, including the wind turbine near wake region C1, the coupling region C2, and the wind turbine far wake region C3. The time step is set to T, and the initial conditions are set to the velocity fields of the three regions: V C1 、V C2 and V C3 , the velocity vector is initialized to (V wind ,0,0), where V wind represents the wind speed of the initial uniform wind field;

[0006] S2. In the process of numerical simulation of the wind turbine near wake area C1, the actuating line model of the wind turbine is established based on the actuating line theory. Based on the Reynolds averaged NS equation, the source term is introduced to replace the actual wind turbine blades to obtain the velocity field V in the wind turbine near wake area. C11 ;

[0007] S3. When the wind turbine yaws or moves, it affects the wake. The zero-point search method is used to determine the wake center.

[0008] S4. Calculation of yaw wake meandering using the tracer particle method;

[0009] S5. In the numerical simulation of the wind turbine coupling region C2, an exponential relaxation factor was added to the velocity field V. C11 and V C3 Perform coupling calculation to obtain the velocity field V in the coupling zone C2m , m=1,2,3,....;

[0010] S6. In the process of numerical simulation of the wind turbine wake area C3, based on the existing improved Jensen model, the velocity field V calculated in step S5 is converted to C2m Combined with the wake center P obtained in S4 n As the entry of the improved Jensen model, the boundary conditions are obtained, and then the wind turbine far wake velocity field V is calculated by the improved Jensen model. C3m ;

[0011] S7, use the new V C31 Repeat step S5 to output the new coupling zone velocity field V C2(m+1) ;

[0012] S8, repeat S6 and S7 until the final required velocity field V in the far wake area of ​​the wind turbine is calculated. C3(m+1) .

[0013] Preferably, in step S2, the velocity field V of the wind turbine near the wake is calculated. C11 The process is as follows:

[0014] Set the computational domain length of the wind turbine wake region C1 to x C1 , divide the computational domain of the wind turbine wake area C1 into grids, and calculate the initial wind turbine wake area velocity field V C1 The Reynolds-averaged NS equation is used to solve the problem. The fan actuation line model is used to add a source term to the Reynolds-averaged NS equation to replace the real fan blades. The formula is as follows:

[0015]

[0016]

[0017] Where u is the velocity vector of the near wake calculation grid, u j is the velocity component in the j direction, x j is the axial coordinate axis component of the wind field, ρ is the fluid density, u i is the velocity component in the i direction, t is the wind field calculation time, p is the pressure, τ ij and are the viscous and turbulent stresses, g i is the acceleration due to gravity, f σi is the surface tension, f UALM is the source term for modeling the blade effect on the fluid, i.e., the vector sum of lift and drag, i = 1, 2, 3 represent the directions of the x, y, and z axes in the Cartesian coordinate system, and j = 1, 2, 3 represent the directions of the x, y, and z axes in the Cartesian coordinate system, respectively;

[0018] In the near-wake flow field of a wind turbine, the wind turbine actuation line model is used to discretize each blade of the wind turbine into a series of spanwise sections with fixed profiles, chord lengths, and angles of attack. Each spanwise section is replaced by an actuation point that generates a body force. The body forces on these actuation points are represented by f k The aerodynamic force generated by each blade segment at (x, y, z, t) is expressed as follows:

[0019]

[0020] In the above formula, F(x,y,z,t) is the vector sum of lift and drag of each aerodynamic point, x, y, z, t are the three-dimensional coordinates of the point and the current wind field calculation time, n is the actuation point index, N is the total number of actuation point segments, d n is the distance between (x, y, z) and the position of the nth actuator point, and ε is a constant that determines the width of the projected area;

[0021] The formula for the velocity field near the wind turbine wake is as follows:

[0022] V C11 =(v1, v2, v3);

[0023] When the time step When , the calculation of the near-wake flow field is completed, and v1, v2, and v3 represent the velocities in the x, y, and z coordinate axes in the Cartesian coordinate system, respectively.

[0024] Preferably, in step S3, the wake center is determined using a zero-point search method, specifically as follows:

[0025] S31. Using CFD method to obtain t=x C1 / V wind The wake center P0 at

[0026] S32, at t>x C1 / V wind When P0 is used as the geometric center, the zero point of the wake tangential velocity is found in a square area with a length and width of 0.3R. The zero point of Vz determines the Y-axis coordinate of the wake center, and the zero point of Vy determines the Z-axis coordinate of the wake center, and the new wake center P1 is obtained.

[0027] S33, in the next time step, use P1 as the new wake center, repeat step S32, and obtain the next new wake center P2;

[0028] S34, by iteratively repeating steps S31 to S33, tracking the tangential velocity zero point in the wake at each time step, thereby obtaining P n , then P n The wake center is regarded as the Jensen inlet boundary condition; the wake center cylindrical coordinates (x g ,y g ,z g ).

[0029] Preferably, in step S4, calculating the yaw wake meandering specifically includes:

[0030] A quasi-Lagrangian method is designed to describe the large eddy turbulence mechanism, where the simulated eddy is larger than two rotor diameters. v and w are set as the lateral and vertical velocities, respectively, and the characteristic velocity is defined as follows:

[0031]

[0032] Among them, (x b ,y b ,z b ) is the inertial coordinate system, A f is the wake cross-sectional area, where the center coordinate of the wake cross-sectional area is (y b ,z b ), vc is the lateral characteristic velocity, w c is the vertical characteristic velocity;

[0033] The lateral and vertical wake displacements are described as:

[0034]

[0035] Among them, y g is the lateral wake displacement, U is the incoming wind speed, z g is the vertical wake displacement, according to the quasi-Lagrangian method T m =L / U,T m is the time interval, L is the length of the wake under consideration, t i is the time of wake release, and the time of wake release t is given in addition. i The initial conditions are as follows:

[0036]

[0037] Preferably, in step S4, based on the theory of the quasi-Lagrangian method, the wake meandering process is specifically solved as follows:

[0038] Time t q =t0+qΔt;q=0,1,2,3,…,R;where t0 is the initial time, Δt is the time step, and the solution process for each time step is as follows:

[0039] Determine initial conditions, determine lateral and vertical wake displacements, and determine the wake center Repeat the determination of the lateral and vertical wake displacements and the wake center until k + 1 = R, where the wake center is:

[0040]

[0041] Preferably, in step S5, the coupling region velocity field V is calculated C2m The calculation process is as follows:

[0042] The velocity of each point in the coupling region is calculated using two velocity fields V C2 and V C3 Perform coupling calculation to smooth the velocity distribution in the coupling zone. The calculation formula is as follows:

[0043] V C2m =V C11 ω+V C3 (1-ω);

[0044] Where ω is the weight factor:

[0045]

[0046] Where, δ is the dimensionless length or relative length of the coupling region C2, and the formula is as follows:

[0047]

[0048] In the above formula, H is the length of the calculation domain from the start to the end of the tail flow at the current time, x C1 is the computational domain length of the wake region C1, x C2 is the calculation domain length of the coupling region C2.

[0049] Preferably, in step S6, the velocity V in the far wake region is calculated C3m , where V C3m =Ar 2 +Br+C, A, B, and C are constants and meet the following conditions:

[0050] When the radial radius expands from r to r x When the wake velocity returns to the natural wind speed, the highest wake velocity and the lowest wake velocity are:

[0051]

[0052] Where r x is the cross-sectional radius of the far wake region, β is the wind shear coefficient, V0 is the velocity of the wake center at the entrance of the far wake region, and h is the height of the wake center at the entrance of the far wake region;

[0053] The improved Jensen wake model and the Jensen wake model have the same wake radius and the same mass flux, so:

[0054]

[0055] Where, u is the wake velocity of the original Jensen model;

[0056] Preferably, the velocity solution in the far wake region is performed in two steps:

[0057] The original Jensen model calculates the prediction step:

[0058] k=0.5 / ln(h / z0)

[0059]

[0060] u=u0[1-2a / (1+kx c3 / r0) 2 ];

[0061] Where k represents the wake expansion coefficient, z0 represents the ground roughness, and C Trepresents the thrust coefficient, a represents the axial induction factor, x C3 represents the length of the calculation domain of the far wake area, u0 represents the incoming wind speed, and r0 represents the initial wake radius;

[0062] Correction step:

[0063]

[0064] Therefore, the present invention adopts the above-mentioned novel yaw wind turbine wake calculation model method, and the technical effects are as follows:

[0065] (1) In this paper, a zero-point search method is proposed to address the low accuracy and inapplicability of existing hybrid wake center tracking methods. The zero-point search method ensures velocity continuity between the two wake models and successfully simulates the wake deflection of a yawed wind turbine.

[0066] (2) In the present invention, the winding of the yaw wake is taken into consideration. Based on the dynamic wake winding model, the wake winding is simulated and calculated using the tracer particle method, which solves the problem that the existing wake model does not take the yaw wake winding into consideration.

[0067] (3) In the present invention, the numerical relaxation method is used to avoid the problem of velocity backflow even if a smaller computational domain is used in CFD, thereby ensuring the stability of the velocity-pressure coupling calculation within the computational domain. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 The present invention provides a flow chart of a novel yaw wind turbine wake calculation model method. DETAILED DESCRIPTION

[0069] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0070] Unless otherwise defined, technical or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0071] Example 1

[0072] A novel yaw wind turbine wake calculation model method includes the following steps:

[0073] S1. When performing numerical simulation of the wind turbine wake effect, the calculation domain is divided into three regions, including the wind turbine near wake region C1, the coupling region C2, and the wind turbine far wake region C3. The time step is set to T, and the initial conditions are set to the velocity fields of the three regions: V C1 、V C2 and V C3 , the velocity vector is initialized to (V wind ,0,0), where Vwind represents the wind speed of the initial uniform wind field;

[0074] S2. In the process of numerical simulation of the wind turbine near wake area C1, the actuating line model of the wind turbine is established based on the actuating line theory. Based on the Reynolds averaged NS equation, the source term is introduced to replace the actual wind turbine blades to obtain the velocity field V in the wind turbine near wake area. C11 ;

[0075] Set the computational domain length of the wind turbine wake region C1 to x C1 , divide the computational domain of the wind turbine wake area C1 into grids, and calculate the initial wind turbine wake area velocity field V C1 The Reynolds-averaged NS equation is used to solve the problem. The fan actuation line model is used to add a source term to the Reynolds-averaged NS equation to replace the real fan blades. The formula is as follows:

[0076]

[0077] Where u is the velocity vector of the near wake calculation grid, u j is the velocity component in the j direction, x j is the axial coordinate axis component of the wind field, ρ is the fluid density, u i is the velocity component in the i direction, t is the wind field calculation time, p is the pressure, τ ij and are the viscous and turbulent stresses, g i is the acceleration due to gravity, f σi is the surface tension, f UALM is the source term for modeling the blade effect on the fluid, i.e., the vector sum of lift and drag, i = 1, 2, 3 represent the directions of the x, y, and z axes in the Cartesian coordinate system, and j = 1, 2, 3 represent the directions of the x, y, and z axes in the Cartesian coordinate system, respectively;

[0078] In the near-wake flow field of a wind turbine, the wind turbine actuation line model is used to discretize each blade of the wind turbine into a series of spanwise sections with fixed profiles, chord lengths, and angles of attack. Each spanwise section is replaced by an actuation point that generates a body force. The body forces on these actuation points are represented by f k The aerodynamic force generated by each blade segment at (x, y, z, t) is expressed as follows:

[0079]

[0080] In the above formula, F(x,y,z,t) is the vector sum of lift and drag of each aerodynamic point, x, y, z, t are the three-dimensional coordinates of the point and the current wind field calculation time, n is the actuation point index, N is the total number of actuation point segments, d nis the distance between (x, y, z) and the position of the nth actuator point, and ε is a constant that determines the width of the projected area;

[0081] The formula for the velocity field near the wind turbine wake is as follows:

[0082] V C11 =(v1, v2, v3);

[0083] When the time step When , the calculation of the near-wake flow field is completed, and v1, v2, and v3 represent the velocities in the x, y, and z coordinate axes in the Cartesian coordinate system, respectively.

[0084] S3. When the wind turbine yaws or moves, the wake center is determined using the zero search method, as follows:

[0085] S31. Using CFD method to obtain t=x C1 / V wind The wake center P0 at

[0086] S32, at t>x C1 / V wind When P0 is used as the geometric center, the zero point of the wake tangential velocity is found in a square area with a length and width of 0.3R. The zero point of Vz determines the Y-axis coordinate of the wake center, and the zero point of Vy determines the Z-axis coordinate of the wake center, and the new wake center P1 is obtained.

[0087] S33, in the next time step, use P1 as the new wake center, repeat step S32, and obtain the next new wake center P2;

[0088] S34, by iteratively repeating steps S31 to S33, tracking the tangential velocity zero point in the wake at each time step, thereby obtaining P n , then P n The wake center is regarded as the Jensen inlet boundary condition; the wake center cylindrical coordinates (x g ,y g ,z g ).

[0089] S4. Calculate the yaw wake meander using the tracer particle method, specifically including:

[0090] A quasi-Lagrangian method is designed to describe the large eddy turbulence mechanism, where the simulated eddy is larger than two rotor diameters. v and w are set as the lateral and vertical velocities, respectively, and the characteristic velocity is defined as follows:

[0091]

[0092] Among them, (x b ,y b,z b ) is the inertial coordinate system, A f is the wake cross-sectional area, where the origin is (y b ,z b ) has a diameter D w , v c is the lateral characteristic velocity, w c is the vertical characteristic velocity;

[0093] The lateral and vertical wake displacements are described as:

[0094]

[0095] Among them, y g is the lateral wake displacement, U is the incoming wind speed, z g is the vertical wake displacement, according to the quasi-Lagrangian method T m =L / U,T m is the time interval, L is the length of the wake under consideration, t i is the time of wake release, and the time of wake release t is given in addition. i The initial conditions are as follows:

[0096]

[0097]

[0098] Based on the theory of quasi-Lagrangian method, the specific solution of the wake meandering process is as follows:

[0099] The velocity field at the Jensen inlet boundary is expressed in cylindrical coordinates as V C =(V x ,V y ,V z );

[0100] Time t q =t0+qΔt;q=0,1,2,3,…,R;where t0 is the initial time, Δt is the time step, and the solution process for each time step is as follows:

[0101] Determine initial conditions, determine lateral and vertical wake displacements, and determine the wake center Repeat the determination of the lateral and vertical wake displacements and the wake center until k + 1 = R, where the wake center is:

[0102]

[0103] S5. In the numerical simulation of the wind turbine coupling region C2, an exponential relaxation factor was added to the velocity field V. C11 and V C3Perform coupling calculation to obtain the velocity field V in the coupling zone C2m , m=1,2,3,....;

[0104] The velocity of each point in the coupling region is calculated using two velocity fields V C2 and V C3 Perform coupling calculation to smooth the velocity distribution in the coupling zone. The calculation formula is as follows:

[0105] V C2m =V C11 ω+V C3 (1-ω);

[0106] Where ω is the weight factor:

[0107]

[0108] Where, δ is the dimensionless length or relative length of the coupling region C2, and the formula is as follows:

[0109]

[0110] In the above formula, H is the length of the calculation domain from the start point to the end point of the tail flow at the current time, x C1 is the computational domain length of the wake region C1, x C2 is the calculation domain length of the coupling region C2.

[0111] S6. In the process of numerical simulation of the wind turbine wake area C3, based on the existing improved Jensen model, the velocity field V calculated in step S5 is converted to C2m Combined with the wake center P obtained in S4 n As the entry of the improved Jensen model, the boundary conditions are obtained, and then the wind turbine far wake velocity field V is calculated by the improved Jensen model. C3m ;

[0112] Calculate the velocity V in the far wake region C3m , where V C3m =Ar 2 +Br+C, A, B, and C are constants and meet the following conditions:

[0113] (1) When the radial radius expands from r to r x When the wake velocity returns to the natural wind speed, the highest wake velocity and the lowest wake velocity are:

[0114]

[0115] Where r xis the cross-sectional radius of the far wake region, β is the wind shear coefficient, V0 is the velocity of the wake center at the entrance of the far wake region, and h is the height of the wake center at the entrance of the far wake region;

[0116] (2) The wake radius of the improved Jensen wake model and the Jensen wake model are the same, and the mass flux is equal, then:

[0117]

[0118] Where, u is the wake velocity of the original Jensen model;

[0119] The velocity solution in the far wake region is carried out in two steps:

[0120] (1) The original Jensen model calculates the prediction step:

[0121] k=0.5 / ln(h / z0)

[0122]

[0123] Where k represents the wake expansion coefficient, z0 represents the ground roughness, and C T represents the thrust coefficient, a represents the axial induction factor, x C3 represents the length of the calculation domain of the far wake area, u0 represents the incoming wind speed, and r0 represents the initial wake radius;

[0124] (2) Correction step:

[0125]

[0126] S7, use the new V C31 Repeat step S5 to output the new coupling zone velocity field V C2(m+1) ;

[0127] S8, repeat S6 and S7 until the final required velocity field V in the far wake area of ​​the wind turbine is calculated. C3(m+1) .

[0128] Therefore, the present invention adopts the above-mentioned new yaw wind turbine wake calculation model method, aiming to improve the accuracy and efficiency of the calculation. By combining the CFD actuating line model and the improved Jensen wake model, and introducing a search zero point method, the existing wake model's insufficient accuracy and applicability in wake center tracking are solved. In addition, the present invention also adopts the tracer particle method to calculate the meandering of the yaw wake, effectively solving the problem of wind turbine wake prediction considering the yaw factor. The present invention uses a CFD method based on the actuating line theory to simulate and calculate the near-wake flow field of the wind turbine, and then uses the search zero point method to determine the wake center, and then uses the improved Jensen model to simulate and calculate the far-wake flow field of the wind turbine. The coupling area uses an exponential factor to neutralize CFD and Jensen for smoothing calculations. Compared with the medium-precision wake model, the coupling method has higher calculation accuracy; compared with the high-precision model, the coupling method has lower calculation cost.

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A novel yaw wind turbine wake calculation model method, characterized in that: The following steps are involved: S1. When performing numerical simulation of wind turbine wake effect, the calculation domain is divided into three areas, including the wind turbine near wake area C 1. Coupling area C 2. Wind turbine far wake area C 3. The time step is set to T , set the initial conditions for the velocity fields in the three regions: 、 and , the velocity vector is initialized to ,in represents the wind speed of the initial uniform wind field; S2. In the wake area near the wind turbine C 1 During the numerical simulation, the actuating line model of the wind turbine is established based on the actuating line theory. Based on the Reynolds-averaged NS equation, the source term is introduced to replace the actual wind turbine blades to obtain the velocity field in the near-wake area of ​​the wind turbine. ; S3. When the wind turbine yaws or moves, it affects the wake. The zero-point search method is used to determine the wake center. S4. Calculation of yaw wake meandering using the tracer particle method; S5. In the wind turbine coupling area C 2 During the numerical simulation, an exponential relaxation factor was added to the velocity field. and Perform coupling calculation to obtain the velocity field in the coupling area , m=1,2,3,....; S6. In the wake area near the wind turbine C 3 During the numerical simulation, based on the existing improved Jensen model, the velocity field calculated in step S5 is Combined with the wake center obtained in S4 As the entry of the improved Jensen model, the boundary conditions are obtained, and then the wind turbine far wake velocity field is calculated by the improved Jensen model. ; Calculate the speed in the far wake region in, , A 、 B 、 C are constants and satisfy the following conditions: When the radial radius is extended by Expand to When the wake velocity returns to the natural wind speed, the highest wake velocity and the lowest wake velocity are: ； Where, is the cross-sectional radius of the far wake region, is the wind shear coefficient, is the velocity of the wake center at the far wake region entrance, is the height of the wake center at the entrance of the far wake region; The improved Jensen wake model and the Jensen wake model have the same wake radius and the same mass flux, so: ； Where, is the wake velocity of the original Jensen model; The velocity solution in the far wake region is carried out in two steps: The original Jensen model calculates the prediction step: ； Where, represents the wake expansion coefficient, Indicates the surface roughness. represents the thrust coefficient, represents the axial induction factor, represents the length of the computational domain in the far wake region, Indicates the incoming wind speed, represents the initial wake radius; Correction step: ； S7, use the new Repeat step S5 to output the new coupling zone velocity field ; S8, repeat S6 and S7 until the final required velocity field of the wind turbine far wake area is calculated .

2. A novel yaw wind turbine wake calculation model method according to claim 1, characterized in that: In step S2, the velocity field of the wind turbine near the wake is calculated The process is as follows: Place the fan close to the wake area C The computational domain length of 1 is set to , put the fan near the tail area C The computational domain of 1 is divided into grids, and the velocity field of the initial wind turbine near the wake area is calculated. The Reynolds-averaged NS equation is used to solve the problem. The fan actuation line model is used to add a source term to the Reynolds-averaged NS equation to replace the real fan blades. The formula is as follows: ； ； Where, is the velocity vector of the near-wake calculation grid, is the velocity component in the j direction, is the axial coordinate axis component of the wind field, is the fluid density, is the velocity component in the i direction, Calculate time for the wind farm, It's pressure. and are the viscous and turbulent stresses, is the acceleration due to gravity, is the surface tension, is the source term that models the blade effect on the fluid, i.e. the vector sum of lift and drag, Represents the Cartesian coordinate system 、 、 Three coordinate axis directions, 3 represent the Cartesian coordinate system 、 、 Three coordinate axis directions; In the near-wake flow field of a wind turbine, the wind turbine actuation line model is used to discretize each blade of the wind turbine into a series of spanwise sections with fixed profiles, chord lengths, and angles of attack. Each spanwise section is replaced by an actuation point that generates a body force. The body forces on these actuation points are given by Indicates that each leaf segment The aerodynamic force generated at is as follows: ； In the above formula, is the vector sum of lift and drag at each aerodynamic point, 、 、 、 They are the three-dimensional coordinate point and the current wind field calculation time, is the actuation point index, is the total number of actuation point segments, yes( , , ) and The distance between the actuator point positions, is a constant that determines the width of the projection area; The formula for the velocity field near the wind turbine wake is as follows: ； When the time step When , the calculation of the near wake flow field is completed, 、 、 Represents the Cartesian coordinate system Speed ​​in the coordinate axis direction.

3. A novel yaw wind turbine wake calculation model method according to claim 1, characterized in that: In step S3, the wake center is determined using the zero-point search method, as follows: S31, using CFD method to obtain Wake center ; S32, in When using As the geometric center, find the zero point of the wake tangential velocity in a square area with a length and width of 0.3R. The zero point of Vz determines the Y-axis coordinate of the wake center, and the zero point of Vy determines the Z-axis coordinate of the wake center to obtain the new wake center. ; S33. In the next time step, use As the new wake center, repeat step S32 to obtain the next new wake center. ; S34, by iteratively repeating steps S31 to S33, tracking the tangential velocity zero point in the wake at each time step, thereby obtaining , then The wake center is considered as the Jensen inlet boundary condition; Get the wake center cylindrical coordinates .

4. A novel yaw wind turbine wake calculation model method according to claim 1, characterized in that: In step S4, the yaw wake meandering is calculated, which specifically includes: A quasi-Lagrangian method is designed to describe the large eddy turbulence mechanism, where the simulated eddy is larger than two rotor diameters and the and are the lateral and vertical velocities respectively, and the characteristic velocity is defined as follows: ； in, is the inertial coordinate system, is the wake cross-sectional area, where the center coordinate of the wake cross-sectional area is ( ), is the transverse characteristic velocity, is the vertical characteristic velocity; The lateral and vertical wake displacements are described as: ； ； in, is the lateral wake displacement, is the incoming wind speed, is the vertical wake displacement, according to the quasi-Lagrangian method , is the time interval, is the wake length considered, is the time of wake release, and the time of wake release is given in addition. The initial conditions are as follows: ； 。 5. A novel yaw wind turbine wake calculation model method according to claim 4, characterized in that: In step S4, based on the theory of the quasi-Lagrangian method, the wake meandering process is specifically solved as follows: time , is the initial time, is the time step, and the solution process for each time step is as follows: Determine initial conditions, determine lateral and vertical wake displacements, and determine the wake center Repeat the determination of the lateral and vertical wake displacements and the wake center until , where the wake center is: 。 6. A novel yaw wind turbine wake calculation model method according to claim 1, characterized in that: In step S5, the velocity field in the coupling region is calculated The calculation process is as follows: The velocity of each point in the coupling region is calculated using two velocity fields: and Perform coupling calculation to smooth the velocity distribution in the coupling zone. The calculation formula is as follows: ； Where, is the weight factor: ； Where, , The coupling region C The dimensionless length or relative length of 2 is as follows: ； In the above formula, is the length of the calculation domain from the start to the end of the tail flow at the current time, Near-wake area C The computational domain length of 1, Coupling zone C The computational domain length is 2.

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