Method for constructing three-dimensional wake flow model of wind turbine generator in complex terrain

Abstract

The invention discloses a method for constructing a three-dimensional wake flow model of a wind turbine generator in a complex terrain. The wake flow velocity loss is preset to present a Gaussian distribution characteristic, and a 3DJG-U wake flow model under the flat terrain is obtained based on an anisotropic wake flow linear expansion hypothesis and a mass conservation law; carrying out numerical simulation on the complex terrain based on a computational fluid mechanics method, determining local wind speeds at all positions in the complex terrain wind power plant, taking the local wind speeds as wake flow model inflow items, and taking a streamline from the center of a hub of a wind turbine generator as a wake flow center line of the wind turbine generator; and based on the 3DJG-U wake flow model, the local wind speed at each position in the complex terrain wind power plant and the wake flow center line of the wind turbine generator, deducing to obtain a three-dimensional wake flow model of the wind turbine generator under the complex terrain. The invention belongs to the field of wind turbine generators. According to the method, the speed loss caused by the wake effect between the wind turbine generators in the wind power plant in the complex terrain can be evaluated more accurately, and the economic benefit and the operation safety of the wind power plant are improved.

Description

Technical Field

[0001] The invention relates to the field of wind turbines, and in particular to a method for constructing a three-dimensional wake model of a wind turbine under complex terrain. Background Art

[0002] After the rapid increase in the installed capacity of wind turbines around the world, most flat terrain areas with good wind resources have been developed and utilized. As the demand for wind energy development further increases, some complex terrain areas with rich wind resources will be gradually developed.

[0003] The undulation of terrain has a significant impact on the development of wake, causing changes in flow shear, pressure gradient, and inducing local flow characteristics. By comparing the wind tunnel measurement results with the numerical simulation results, it can be found that due to the influence of secondary flow around the three-dimensional hills, the wind acceleration effect and wake expansion are significantly reduced. The intricate wake characteristics cause the downstream wind turbines to bear unstable aerodynamic loads, increasing the operation and maintenance costs of the wind turbines. Therefore, how to accurately evaluate the wake effect between wind farms is crucial to the economic benefits and safe operation of wind farms in complex terrain.

[0004] Current research on the wake model of wind farms in complex terrain ignores the non-uniformity of wind speed distribution in the background flow field at different downstream distances caused by terrain effects (the background flow field is defined as the flow field on complex terrain without any disturbance caused by wind turbines). The difference in local wind speed distribution is underestimated, which will directly affect the wake velocity profile and wake loss characteristics at different downstream distances. Secondly, the wake in wind farms in complex terrain will meander and deflect due to terrain effects. Current research assumes that the centerline of the wake starts from the center of the hub and develops along the contour line at the hub height above the terrain horizontal line. Obviously, the linear relationship between the centerline of the wake and the terrain fluctuation is inconsistent with physical reality, and the influence of terrain anisotropy on the deflection of the centerline of the wake is not fully considered. Summary of the invention

[0005] The embodiment of the present invention solves the technical problem that the prior art cannot accurately evaluate the wake effect between wind farms in complex terrain wind farms by providing a method for constructing a three-dimensional wake model of a wind turbine in complex terrain, and achieves the technical effect of being able to accurately evaluate the wake effect between wind farms in complex terrain wind farms.

[0006] In a first aspect, the present invention provides a method for constructing a three-dimensional wake model of a wind turbine under complex terrain, the method comprising:

[0007] The wake velocity loss is assumed to present Gaussian distribution characteristics. Based on the assumption of anisotropic wake linear expansion and the law of mass conservation, the 3DJG-U wake model under flat terrain is obtained.

[0008] Based on the computational fluid dynamics method, numerical simulation of complex terrain is carried out to obtain the background flow field of the wind farm in complex terrain, determine the local wind speed at each location in the wind farm in complex terrain, use the local wind speed as the inflow item of the wake model, and use the streamline originating from the center of the wind turbine hub as the centerline of the wind turbine wake;

[0009] Based on the 3DJG-U wake model, the local wind speed at each location in the complex terrain wind farm and the wake centerline of the wind turbine, a three-dimensional wake model of the wind turbine under complex terrain is derived.

[0010] Furthermore, the assumption about the anisotropic wake linear expansion includes:

[0011]

[0012] Among them, r y is the wake radius in the y direction, r z is the wake radius in the z direction, k y is the wake expansion coefficient in the y direction, k z is the wake expansion coefficient in the z direction, r i is the initial wake radius, σ y is the standard deviation of the Gaussian distribution in the y direction, σ z is the standard deviation of the Gaussian distribution in the z direction.

[0013] Furthermore, the preset wake velocity loss presents a Gaussian distribution characteristic, and when the wake of the wind turbine expands to the wake boundary, the wake velocity is equal to the incoming wind speed, including:

[0014]

[0015] Among them, U 0 is the incoming wind speed, u 0 (x,z) is the fully developed wake wind profile, A Inflow , B are variables in the Gaussian shape function.

[0016] Furthermore, the 3DJG-U wake model and the Jensen model have the same mass flux in the wake region, and the mass conservation law is applied, including:

[0017]

[0018] Among them, u * is the velocity in the wake area predicted based on the Jensen model;

[0019] The u * include:

[0020]

[0021] Where a is the axial induction factor of the wind turbine rotor, C t is the wind turbine rotor thrust coefficient, k Jensen is the wake expansion coefficient with a value of 0.075, r d is the radius of the wind turbine rotor, U hub is the hub wind speed at hub height.

[0022] Furthermore, regarding the 3DJG-U wake model under flat terrain, it includes:

[0023]

[0024] Here, e is the base of natural logarithms.

[0025] Furthermore, the nonlinear deflection and winding of the wake centerline due to terrain effects are considered, and the streamline originating from the center of the wind turbine hub is used as the wake centerline of the wind turbine, including:

[0026]

[0027] Among them, u 0CT (x,z) is the wake velocity distribution of the wind farm under complex terrain, ΔS z is the deflection of the wake center relative to the hub center at the downstream position x in the z direction.

[0028] Furthermore, considering the local wind speed at the location of the wind turbine and at different locations downstream of the wind turbine, a three-dimensional wake model of the wind turbine under complex terrain is obtained, including:

[0029]

[0030] Among them, u CT (x, y, z) is the three-dimensional wake model of the wind turbine under complex terrain, U local (x, y, z) is the local wind speed determined based on CFD simulation of the background flow field of the wind farm in complex terrain, ΔS y is the deflection of the wake center at the downstream position x relative to the hub center in the y direction.

[0031] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0032] The present invention provides a method for constructing a three-dimensional wake model of a wind turbine under complex terrain, including: based on the 3DJG-U wake model, the present invention proposes a new three-dimensional Jensen-Gaussian wake model (3DJG-CT) for complex terrain. The model is based on two improved assumptions and combined with CFD simulation to carry out CFD simulation of the background flow field of a wind farm under complex terrain. The centerline of the wake is determined by the velocity component extracted from the simulation result of the background flow field. The simulation result also provides the local wind speed to replace the inflow wind shear model in the traditional model. The present invention reveals the influence of topological anisotropy on the three-dimensional wake characteristics, and can more accurately evaluate the influence of the wake effect between wind farms on wind farms under complex terrain, thereby improving the economic benefits and operational safety of wind farms. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 A schematic diagram of the structure of a method for constructing a three-dimensional wake model of a wind turbine under complex terrain provided by the present invention;

[0035] Figure 2 A schematic diagram of a flow field of a wind turbine provided by the present invention;

[0036] Figure 3 A schematic diagram of a flow tube model of a wind turbine provided by the present invention. DETAILED DESCRIPTION

[0037] The embodiment of the present invention solves the technical problem in the prior art that the wake effect between wind farms in complex terrain cannot be accurately evaluated by providing a method for constructing a three-dimensional wake model of a wind turbine in complex terrain.

[0038] The technical solution of the embodiment of the present invention is to solve the above technical problems, and the overall idea is as follows:

[0039] A method for constructing a three-dimensional wake model of a wind turbine under complex terrain, the method comprising: presetting the wake velocity loss to present a Gaussian distribution characteristic, and obtaining a 3DJG-U wake model under flat terrain based on the assumption of anisotropic wake linear expansion and the law of conservation of mass; conducting numerical simulation of complex terrain based on computational fluid dynamics methods, determining the local wind speed at various locations in a wind farm with complex terrain, using the local wind speed as the inflow item of the wake model, and using the streamline originating from the center of the wind turbine hub as the centerline of the wind turbine wake; deriving a three-dimensional wake model of the wind turbine under complex terrain based on the 3DJG-U wake model, the local wind speed at various locations in a wind farm with complex terrain, and the centerline of the wind turbine wake. In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the drawings in the specification and specific implementation methods.

[0040] First of all, the term "and / or" in this article is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0041] It should be noted that CFD in the present invention refers to the method of computational fluid dynamics.

[0042] The present invention provides Figure 1 A method for constructing a three-dimensional wake model of a wind turbine under complex terrain is shown, comprising steps S11-S13:

[0043] Regarding step S11, it is preset that the wake velocity loss presents Gaussian distribution characteristics, and based on the anisotropic wake linear expansion assumption and the law of conservation of mass, a 3DJG-U wake model under flat terrain is obtained.

[0044] Regarding the assumption of anisotropic wake linear expansion: The wake radius of the wind turbine increases linearly with the downstream distance. Based on theoretical analysis and field experimental data, it is proved that when the wake radius is approximately 2.58σ z The model has higher accuracy, including:

[0045]

[0046] Among them, r y is the wake radius in the y direction, r z is the wake radius in the z direction, k y is the wake expansion coefficient in the y direction, k z is the wake expansion coefficient in the z direction, r i is the initial wake radius, σ y is the standard deviation of the Gaussian distribution in the y direction, σz is the standard deviation of the Gaussian distribution in the z direction.

[0047] The preset wake velocity loss shows Gaussian distribution characteristics, and when the wake of the wind turbine expands to the wake boundary, the wake velocity is equal to the incoming wind speed, and the fully developed wake wind profile shows a Gaussian shape, specifically including:

[0048]

[0049] Among them, U 0 is the incoming wind speed, u 0 (x,z) is the fully developed wake wind profile, A Inflow , B are variables in the Gaussian shape function.

[0050] Regarding the law of conservation of mass: The 3DJG-U wake model and the Jensen model have the same mass flux in the wake region, and the law of conservation of mass is applied, including:

[0051]

[0052] Among them, u * is the velocity in the wake area predicted based on the Jensen model;

[0053] u * include:

[0054]

[0055] Where a is the axial induction factor of the wind turbine rotor, V t is the wind turbine rotor thrust coefficient, k Jensen is the wake expansion coefficient with a value of 0.075, r d is the radius of the wind turbine rotor, U hub is the hub wind speed at hub height.

[0056] By combining the above formulas, the variable A in the Gaussian shape function can be determined Inflow , B.

[0057] Furthermore, the 3DJG-U wake model under flat terrain can be expressed as:

[0058]

[0059] Here, e is the base of natural logarithms.

[0060] Regarding step S12, numerical simulation of complex terrain is carried out based on computational fluid dynamics methods to obtain the background flow field of the complex terrain wind farm, determine the local wind speed at each location in the complex terrain wind farm, use the local wind speed as the inflow item of the wake model, and use the streamline originating from the center of the wind turbine hub as the wake centerline of the wind turbine.

[0061] In the above formula, the anisotropy of terrain topology and the horizontal wind speed fluctuations are ignored, and the two-dimensional mountain inflow engineering model and the wind shear model with exponential or logarithmic law cannot accurately describe the wind speed distribution of the background flow field. Therefore, the present invention proposes to carry out numerical simulation of complex terrain based on computational fluid dynamics methods, determine the local wind speed at each location in the complex terrain wind farm, use the local wind speed as the inflow term of the wake model, and carry out numerical simulation of complex terrain based on computational fluid dynamics methods, using the streamline originating from the center of the wind turbine hub as the centerline of the wind turbine wake, so as to meet the influence of terrain on the flow field (background flow field and wake field).

[0062] Regarding the numerical simulation of complex terrain based on computational fluid dynamics methods, the local wind speed at each location in the wind farm with complex terrain is determined, and the local wind speed is used as the inflow item of the wake model: the wake centerline of the wind turbine in the complex terrain is similar to or identical to the streamline at the hub height of the location of the wind turbine in the background flow field of the complex terrain.

[0063] The centerline of the wind turbine wake in complex terrain can be approximated by the streamlines of the background flow field originating from the center of the wind turbine hub. The streamlines of the background flow field can be extracted from the CFD simulation results of the background flow field, including the extraction of wind speed components (u x ,u y ,u z , where u x is the wind speed in the x direction, u y is the wind speed in the y direction, u z is the wind speed in the z direction, and the center of the coordinate system constructed by the present invention is the center of the hub of the wind turbine set, including three directions: x, y, and z. x, y, and z are perpendicular to each other, z is the vertical direction, and z is the horizontal direction).

[0064] u x and u y Parallel to the contour lines and perpendicular to each other. z It is the normal velocity component perpendicular to the surface on the contour line. Under the influence of the horizontal velocity component and the normal velocity component, as the wake develops, the centerline of the wake will meander and deflect in the horizontal and vertical directions, as shown in the following figure. Figure 2 As shown, where N is the centerline of the wake. Figure 2 The characters in all correspond one-to-one with the characters in the embodiments of the present invention.

[0065] Regarding the numerical simulation of complex terrain based on computational fluid dynamics methods, the streamline originating from the center of the wind turbine hub is used as the centerline of the wind turbine wake: when the fluid flows in complex terrain, the local wind speed distribution on the complex terrain is uneven.

[0066] Completely different from wind farms on flat terrain, the flow on complex terrain is affected by terrain effects (acceleration effect and hillside blocking effect). The local wind speed U local (x, y, z) can be defined as the vertical wind speed distribution at a certain coordinate position (x, y) in the background flow field.

[0067] For different slopes on the same hillside, a higher slope will significantly increase the wind speed at the top of the mountain. In addition, on steeper slopes, the mountain blocking effect is more obvious, resulting in a more obvious mountain wake area.

[0068] In order to reflect the influence of terrain effect on wake development, the incoming wind speed U in the wake model can be 0 Corrected to the local wind speed U determined by CFD simulation of the background flow field of the wind farm in complex terrain local (x,y,z).

[0069] Description of the background flow field of wind farms in complex terrain:

[0070] Flow over complex terrain has significant three-dimensional characteristics, in which the local wind speed distribution on complex terrain changes with the change of coordinate position (x, y), and the linear relationship between the wake centerline and terrain fluctuations is inconsistent with physical reality.

[0071] In order to capture the three-dimensional characteristics of the flow while reducing the computational cost, the local wind speed U determined by CFD simulation of the background flow field of a wind farm with complex terrain can be used. local (x, y, z) replaces the incoming wind speed U in the wake model 0 The background flow field can be defined as the flow field over complex terrain without any wind turbine disturbance.

[0072] The terrain topology is modeled by elevation points, which are extracted at 3m intervals in a Geographic Information System (GIS).

[0073] In the present invention, the finite element method is used to discretize the calculation domain of the wind farm in complex terrain, and the development process of the incompressible fluid is solved based on the Coupled algorithm.

[0074] Specifically, the velocity component (u) of a target position (x, y) is extracted from the simulation results of the background flow field. x ,u y ,u z ) and local wind speed U local (x,y,z).

[0075] Based on the influence of wind direction, during model verification, the terrain model in the calculation domain is rotated by a certain angle according to the real-time wind direction on site; when selecting the site for the wind farm layout, the power output and wake loss evaluation under multiple wind direction conditions can be achieved by changing the inflow wind direction of the calculation domain. Therefore, the three-dimensional characteristics of the terrain effect can be fully considered based on CFD simulation.

[0076] In the process of calculating the background flow field of wind farms in complex terrain, the Reynolds time-averaged method can be used to solve the Navier-Stokes equations. The standard k-ε turbulence model can be used to describe the turbulent motion, and the three-dimensional control equation can be expressed as:

[0077]

[0078] Among them, the turbulent kinetic energy generation term G k for:

[0079]

[0080] Turbulent viscosity μ t for

[0081]

[0082] In the above formula, k e is the turbulent kinetic energy, ε is the corresponding turbulent dissipation rate, S k With S ε is the source term, σ ε , σ k , C μ , C ε1 , C ε2 are turbulence model constants.

[0083] The standard wall equation can be used to simulate the near-wall flow, where the roughness height Ks is calculated by the following formula:

[0084]

[0085] Among them, E is the empirical parameter, C s is the roughness constant, z 0 is the roughness length and can be determined based on terrain classification.

[0086] Regarding step S13, based on the 3DJG-U wake model, the local wind speed at each location in the complex terrain wind farm and the wake centerline of the wind turbine, a three-dimensional wake model of the wind turbine under complex terrain is derived.

[0087] Based on the computational fluid dynamics method, numerical simulation of complex terrain is carried out to determine the local wind speed at each location in the complex terrain wind farm. The local wind speed is used as the inflow item of the wake model, and the streamline originating from the center of the wind turbine hub is used as the wake centerline of the wind turbine. The three-dimensional wake model is derived, including:

[0088] The CFD simulation of the background flow field takes into account the momentum mixing of the fluid and the interaction between the fluid and the terrain. local (x,y,z) to reflect.

[0089] In the derivation process, the wake development process can be regarded as the process of air particles flowing downstream, and there is no interaction between independent particles in the wake region.

[0090] Considering the nonlinear deflection and winding of the wake centerline due to terrain effects, the streamline originating from the hub center of the wind turbine is taken as the wake centerline of the wind turbine. As the wake develops, the deflection of the wake center at the downstream position x relative to the hub center in the Z direction is ΔS z , without considering the uneven inflow wind speed distribution, the wake velocity distribution of the wind farm in complex terrain (or the local wind speed at the location of the wind turbine and at different locations downstream of the wind turbine) is:

[0091]

[0092] Among them, u 0CT (x,z) is the wake velocity distribution of the wind farm under complex terrain, ΔS z is the deflection of the wake center relative to the hub center at the downstream position x in the z direction.

[0093] Since the terrain effect has a weak influence on the development of wake in flat terrain, the inflow wind and background flow field at different downstream locations in a flat terrain wind farm can be roughly considered equal.

[0094] In contrast to uniform inflow or wind shear inflow, the flow field in complex terrain background exhibits anisotropic distribution characteristics in both vertical and horizontal directions.

[0095] like Figure 2 As shown, the red line in front of the wind turbine represents the local wind profile, while the inflow velocity profile U at the hub hub With inflow velocity u 0 The uniform inflow profile is represented by the purple line.

[0096] Due to the anisotropy of terrain topology, the local wind speed distribution changes with the coordinate position (x, y) in the wind farm. hub and local wind speed U localThe wind speed difference between is represented by Δu(x, y, z), that is:

[0097] Δu(x,y,z)=U local (x,y,z)-U hub

[0098] According to the flow tube model of the one-dimensional momentum theory of the wind turbine, it can be assumed that the wind turbine rotor is an ideal brake disc. According to the principle of conservation of momentum, the inflow velocity V ∞ and wake velocity V 1 The relationships between

[0099] V 1 =(1-2a)V ∞

[0100] Among them, V 1 is the wake velocity, V ∞ is the speed at infinity.

[0101] like Figure 3 As shown by the line segment J in the figure, the wind speed difference Δu in front of the wind turbine will produce an additional mass loss Δm in the wake area, resulting in an asymmetric wake velocity profile. Combined with the flow tube model of the one-dimensional momentum theory of the wind turbine, the wake velocity distribution can be corrected in the vertical direction. The additional mass loss Δm in the wake area can be expressed as:

[0102]

[0103] Where Δm is the additional mass loss in the wake region and Δu is the wind speed difference in front of the wind turbine.

[0104] Based on the terrain effect in wind farms with complex terrain, it can be assumed that the wake velocity distribution in the vertical direction is u CT (x,z), based on the law of conservation of mass, we can The formula converts to:

[0105]

[0106] Among them, u CT (x,z) is the wake velocity distribution in the vertical direction.

[0107] Combining the above formulas to solve, we can get:

[0108]

[0109] Assuming that the three-dimensional velocity distribution in the wake area is also Gaussian, the local wind speed at the location of the wind turbine and at different locations downstream of the wind turbine is considered. In addition, the deflection of the wake center at the downstream position x relative to the hub center in the horizontal direction is considered. y, the three-dimensional wake model of wind turbines under complex terrain can be expressed as:

[0110]

[0111] Among them, u CT (x, y, z) is the three-dimensional wake model of the wind turbine under complex terrain, U local (x, y, z) is the local wind speed determined based on CFD simulation of the background flow field of the wind farm in complex terrain, ΔS y is the deflection of the wake center at the downstream position x relative to the hub center in the y direction.

[0112] In addition, k z With k y It can be determined based on the following formula.

[0113]

[0114] It represents the wake velocity distribution on the vertical plane, so when y = 0, we can and Solve the following formula:

[0115]

[0116] Where C is the variable in the Gaussian shape function.

[0117] In summary, the present invention provides a method for constructing a three-dimensional wake model of a wind turbine under complex terrain, including: presetting the wake velocity loss to present a Gaussian distribution characteristic, and obtaining a 3DJG-U wake model under flat terrain based on the assumption of anisotropic wake linear expansion and the law of conservation of mass; performing numerical simulation on complex terrain based on a computational fluid dynamics method, determining the local wind speed at each location in a wind farm with complex terrain, using the local wind speed as the inflow item of the wake model, and using the streamline originating from the center of the wind turbine hub as the wake centerline of the wind turbine; and deriving a three-dimensional wake model of the wind turbine under complex terrain based on the 3DJG-U wake model, the local wind speed at each location in the wind farm with complex terrain, and the wake centerline of the wind turbine.

[0118] Based on the 3DJG-U wake model, the present invention proposes a new three-dimensional JensenGaussian wake model for complex terrain (3DJG CT). The model is based on two improved assumptions and combined with CFD simulation to carry out CFD simulation of the background flow field of wind farms in complex terrain. The centerline of the wake is determined by the velocity component extracted from the background flow field simulation results. The simulation results also provide local wind speed to replace the inflow wind shear model in the traditional model. The present invention reveals the influence of topological anisotropy on the three-dimensional wake characteristics, and can more accurately evaluate the influence of the wake effect between wind farms on wind farms in complex terrain, thereby improving the economic benefits and operational safety of wind farms.

[0119] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0120] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for constructing a three-dimensional wake model of a wind turbine under complex terrain, characterized in that: The method comprises: The wake velocity loss is assumed to present Gaussian distribution characteristics. Based on the assumption of anisotropic wake linear expansion and the law of mass conservation, the 3DJG-U wake model under flat terrain is obtained. Based on the computational fluid dynamics method, numerical simulation of complex terrain is carried out to obtain the background flow field of the wind farm in complex terrain, determine the local wind speed at each location in the wind farm in complex terrain, use the local wind speed as the inflow item of the wake model, and use the streamline originating from the center of the wind turbine hub as the centerline of the wind turbine wake; Based on the 3DJG-U wake model, the local wind speed at each location in the complex terrain wind farm and the wake centerline of the wind turbine, a three-dimensional wake model of the wind turbine under complex terrain is derived.

2. The method for constructing a three-dimensional wake model of a wind turbine under complex terrain according to claim 1, characterized in that: The assumption of linear expansion of the anisotropic wake includes: Among them, r y is the wake radius in the y direction, r z is the wake radius in the z direction, k y is the wake expansion coefficient in the y direction, k z is the wake expansion coefficient in the z direction, r i is the initial wake radius, σ y is the standard deviation of the Gaussian distribution in the y direction, σ z is the standard deviation of the Gaussian distribution in the z direction.

3. The method for constructing a three-dimensional wake model of a wind turbine under complex terrain according to claim 2, characterized in that: The assumption that the wake velocity loss presents a Gaussian distribution characteristic and that when the wake of the wind turbine expands to the wake boundary, the wake velocity is equal to the incoming wind speed includes: Among them, U0 is the incoming wind speed, u0(x,z) is the fully developed wake wind profile, and A Inflow , B are variables in the Gaussian shape function.

4. A method for constructing a three-dimensional wake model of a wind turbine under complex terrain as claimed in claim 3, characterized in that: The 3DJG-U wake model and the Jensen model have the same mass flux in the wake region and apply the mass conservation law, including: Among them, u * is the velocity in the wake area predicted based on the Jensen model; The u * include: Where a is the axial induction factor of the wind turbine rotor, C t is the wind turbine rotor thrust coefficient, k Jensen is the wake expansion coefficient with a value of 0.075, r d is the radius of the wind turbine rotor, U hub is the hub wind speed at hub height.

5. The method for constructing a three-dimensional wake model of a wind turbine under complex terrain according to claim 4, characterized in that: About the 3DJG-U wake model under flat terrain, including: Here, e is the base of natural logarithms.

6. A method for constructing a three-dimensional wake model of a wind turbine under complex terrain as claimed in claim 5, characterized in that: Considering the nonlinear deflection and winding of the wake centerline due to terrain effects, the streamline originating from the center of the wind turbine hub is used as the wake centerline of the wind turbine, including: Among them, u 0CT (x,z) is the wake velocity distribution of the wind farm under complex terrain, ΔS z is the deflection of the wake center relative to the hub center at the downstream position x in the z direction.

7. A method for constructing a three-dimensional wake model of a wind turbine under complex terrain as claimed in claim 6, characterized in that: Considering the local wind speed at the location of the wind turbine and at different locations downstream of the wind turbine, a three-dimensional wake model of the wind turbine under complex terrain is obtained, including: Among them, u CT (x, y, z) is the three-dimensional wake model of the wind turbine under complex terrain, U local (x, y, z) is the local wind speed determined based on CFD simulation of the background flow field of the wind farm in complex terrain, ΔS y is the deflection of the wake center at the downstream position x relative to the hub center in the y direction.

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