Method for calculating input wind speed of unit in offshore wind farm considering sea wave influence
By calculating the wind turbine shading coefficient and wave impact in offshore wind farms, and combining it with the AV wake model, the problem of inaccurate input wind speed calculation in offshore wind farms is solved, enabling accurate wind speed prediction under severe weather conditions and supporting wind farm power prediction.
Patent Information
- Application Number
- CN202610656074.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-05-13
- Publication Date
- 2026-07-14
AI Technical Summary
Existing AV wake models do not take into account the complexity of sea and wind conditions in offshore wind farms, resulting in inaccurate calculations of input wind speeds.
By reading the location coordinates and wind direction of the wind turbines in the wind farm, the shading coefficient between the turbines is calculated. Combined with the AV wake model, the influence of ocean waves is considered, the surface roughness and friction speed are calculated, the wind speed is calculated in different areas, and finally the input speed of each turbine is calculated.
Under severe weather conditions, it can accurately calculate the input wind speed of the turbines in the wind farm, providing strong support for wind farm power prediction.
Smart Images
Figure CN122389723A_ABST
Abstract
Description
Technical Field
[0001] This invention discloses a method for calculating the input wind speed of turbines in offshore wind farms that takes into account the influence of ocean waves, belonging to the field of wind speed calculation technology. Background Technology
[0002] For offshore wind farms, wind turbines are constantly in a complex environment of wind and wave interaction. Offshore wind farms consist of a large number of dispersed wind turbines. When airflow passes through the rotating rotor, the turbine extracts energy from the airflow, creating a region of reduced wind speed downstream of the turbine. This results in a decrease in the axial wake velocity behind the turbine, and the rotating rotor also disturbs the surrounding airflow, creating mechanical turbulence. This region is called the wake region. If a wind turbine is located within the wake region, the input wind speed of the downstream turbine will be lower than that of the upstream turbine. As the distance downstream of the rotor increases from the rotor plane, the velocity and mechanical turbulence in the wake region gradually decrease. After a certain distance, the wind speed gradually recovers under the influence of the surrounding airflow (background turbulence). The closer the wind turbines are, the greater their influence. This is the wake effect. Waves affect the atmospheric boundary layer near the sea surface, further influencing the airflow around the wind turbine, i.e., the background turbulence affecting the wake effect between offshore wind turbines. Therefore, it is necessary to consider the impact of ocean waves when establishing a wake model for offshore wind farms, with the input wind speed for the computer group.
[0003] Currently, wind farm wake models are established using analytical and numerical simulation methods. When determining the input wind speed to the turbines within a wind farm, analytical wake models primarily focus on the changes in wind speed and turbulence intensity in the wake region, offering high computational efficiency and being commonly used tools. Existing analytical wake models include the inviscid near-field wake model, the simplified wake model Jensen wake model, the Gauss wake model, and the AV wake model (a full-field wake model based on Abramovich jet theory). The first four wake models have poor applicability for calculating wind turbine wakes. The AV wake model, based on jet theory, considers the momentum exchange between the wake region generated by the rotating rotor and the surrounding stationary medium, ensuring a continuous influx of fluid into the wake mixing zone. It considers both the mechanical turbulence caused by the rotating rotor and the restoring effect of the surrounding airflow (background turbulence) on wind speed. However, current applications of the AV wake model do not consider the complexity of sea and wind conditions, and it has not been applied to the establishment of wake models for offshore wind farms or the calculation of turbine input wind speeds. Summary of the Invention
[0004] The purpose of this invention is to provide a method for calculating the input wind speed of turbines in offshore wind farms that takes into account the influence of ocean waves, in order to solve the problem that the AV wake model of the existing method for calculating the input wind speed of turbines in offshore wind farms does not take into account the complexity of sea and wind conditions, resulting in inaccurate calculation results.
[0005] Methods for calculating the input wind speed of turbines in offshore wind farms, taking into account the effects of ocean waves, include: S1. Read the position coordinate parameters of the wind turbines in the wind farm, read the input wind speed and wind direction of the wind farm, perform coordinate transformation on the wind farm according to the wind direction, and calculate the shading coefficient between the wind turbines. S2. Calculate the sea surface roughness and friction speed; S3. Calculate the wind speed in each region using the AV wake model; S4. Calculate the input speed of each wind turbine and determine whether the wind parameter sequence has ended. If it has, end the process; otherwise, return to read the input wind speed and direction of the wind farm.
[0006] Calculate the shading coefficient between wind turbines include: ; In the formula, It is in the Typhoon power unit The projected area of the wind turbine rotor. No. The area of the wind turbine rotor.
[0007] According to the Calculation of the radius of the wind turbine rotor ; The calculation is divided into three cases: If the rotor of an upstream wind turbine does not project onto the downstream wind turbine, it is considered unobstructed. ; The rotor of the upstream wind turbine projects a shadow that completely covers the downstream wind turbine. If it is completely blocked, it is considered as a complete blockage. ; The projection of the upstream wind turbine's rotor onto the downstream wind turbine does not fully cover the downstream wind turbine. If so, it is considered partial occlusion; Partial shading is divided into two cases. When equation (1) is satisfied, the projected area of the wind turbine rotor of the upstream wind turbine at the downstream wind turbine is calculated according to equation (2). (1); (2); In the formula, It is the rotor radius of the downstream wind turbine. It is the radius of the wind turbine rotor upstream. It is the distance between the center of the complete projection of the rotor of the upstream wind turbine and the center of the rotor of the downstream wind turbine. It is the distance from the center of the downstream wind turbine's rotor to the upper intersection point of the complete projection of the upstream wind turbine's rotor and the downstream wind turbine's rotor. When equation (3) is satisfied, the projected area of the wind turbine rotor of the upstream wind turbine at the downstream wind turbine is calculated according to equation (4); (3); (4).
[0008] Determining the sea surface roughness and friction speed includes taking the wheel hub height as an example. Wind speed at wheel hub height Substitution (5): (5); In the formula, It is the friction speed. It refers to sea surface roughness; Seek and , Relationship; Effective height of sea waves Substitution (6): (6); In the formula, It is gravitational acceleration; get and , Relationship; Solving the above two equations together, we get... and Below and .
[0009] The joint solution includes assuming an initial... , will the initial , and Substitution (5), reverse deduction of new Perform iterative convergence until the latest convergence is achieved. Compared to the last time Less than the threshold, at this time the result is and This is a simultaneous solution.
[0010] The calculation of wind speed in each region includes the wind speed model for region one as follows: ; ; ; ; ; ; ; ; ; ; ; ; In the formula, That's the wind speed in Zone 1. It is a parameter to determine. It is the initial velocity ratio. It is an axial inducing factor. This is the axial thrust coefficient of the wind turbine. Let be the distance from a point on the transverse cross-section of the wake to the wake's axis of rotation. Let be the dimensionless initial wake radius. Let the dimensionless wake radius be the radius of region one. Let the dimensionless wake radius be the radius of region two. , It is a parameter that can be calculated. The dimensionless wake length associated with mechanical turbulence. It is the dynamic wake diffusion coefficient. This represents the axial distance from a point downstream of the wind turbine to the wind turbine plane.
[0011] The wind speed model for Region 2 is as follows: ; ; ; ; It is a parameter that can be calculated. The width of region one, Let be the sum of the widths of region 1 and region 2.
[0012] The wind speed model for Region 3 is as follows: ; ; ; ; In the formula, Let be the dimensionless wake radius of region 3. It is a parameter that can be calculated.
[0013] The calculation of the input speed of each fan includes: ; In the formula, yes Time of the first Input speed at the typhoon turbine It did not take into account the effect of wind turbine overlap. Time of the first Input wind speed at the typhoon turbine This is the total number of wind turbines. It takes into account the wake effect between wind turbine units. Time of the first The first in the wake region of the typhoon turbine Wind speed at the typhoon turbine.
[0014] calculate , At that time, the calculation process for wind speed in each region is used to solve the problem, taking into account the specific location.
[0015] Compared with the prior art, the present invention has the following beneficial effects: Under severe weather conditions, the wind farm wake model established by the present invention, which considers the influence of sea surface roughness caused by large and giant waves, can accurately calculate the input wind speed of the units in the wind farm, proving that the present invention has strong rationality and providing strong support for subsequent wind farm power prediction. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of an AV wake model; Figure 2 A flowchart for calculating sea surface roughness considering the effects of ocean waves and friction speed; Figure 3 A schematic diagram illustrating the wake effects between wind turbine units; Figure 4 First schematic diagram showing partial shielding of the wind turbine; Figure 5 Second schematic diagram showing partial shielding of the wind turbine; Figure 6 This is a flowchart of the technology of the present invention; Figure 7 This is a layout diagram of wind farm turbine units; Figure 8 A wind rose diagram; Figure 9 This is a comparison chart of wind speeds. Detailed Implementation
[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention are described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.
[0018] Methods for calculating the input wind speed of turbines in offshore wind farms, taking into account the effects of ocean waves, include: S1. Read the position coordinate parameters of the wind turbines in the wind farm, read the input wind speed and wind direction of the wind farm, perform coordinate transformation on the wind farm according to the wind direction, and calculate the shading coefficient between the wind turbines. S2. Calculate the sea surface roughness and friction speed; S3. Calculate the wind speed in each region using the AV wake model; S4. Calculate the input speed of each wind turbine and determine whether the wind parameter sequence has ended. If it has, end the process; otherwise, return to read the input wind speed and direction of the wind farm.
[0019] Calculate the shading coefficient between wind turbines include: ; In the formula, It is in the Typhoon power unit The projected area of the wind turbine rotor. No. The area of the wind turbine rotor.
[0020] According to the Calculation of the radius of the wind turbine rotor ; The calculation is divided into three cases: If the rotor of an upstream wind turbine does not project onto the downstream wind turbine, it is considered unobstructed. ; The rotor of the upstream wind turbine projects a shadow that completely covers the downstream wind turbine. If it is completely blocked, it is considered as a complete blockage. ; The projection of the upstream wind turbine's rotor onto the downstream wind turbine does not fully cover the downstream wind turbine. If so, it is considered partial occlusion; Partial shading is divided into two cases. When equation (1) is satisfied, the projected area of the wind turbine rotor of the upstream wind turbine at the downstream wind turbine is calculated according to equation (2). (1); (2); In the formula, It is the rotor radius of the downstream wind turbine. It is the radius of the wind turbine rotor upstream. It is the distance between the center of the complete projection of the rotor of the upstream wind turbine and the center of the rotor of the downstream wind turbine. It is the distance from the center of the downstream wind turbine's rotor to the upper intersection point of the complete projection of the upstream wind turbine's rotor and the downstream wind turbine's rotor. When equation (3) is satisfied, the projected area of the wind turbine rotor of the upstream wind turbine at the downstream wind turbine is calculated according to equation (4); (3); (4).
[0021] Determining the sea surface roughness and friction speed includes taking the wheel hub height as an example. Wind speed at wheel hub height Substitution (5): (5); In the formula, It is the friction speed. It refers to sea surface roughness; Seek and , Relationship; Effective height of sea waves Substitution (6): (6); In the formula, It is gravitational acceleration; get and , Relationship; Solving the above two equations together, we get... and Below and .
[0022] The joint solution includes assuming an initial... , will the initial , and Substitution (5), reverse deduction of new Perform iterative convergence until the latest convergence is achieved. Compared to the last time Less than the threshold, at this time the result is and This is a simultaneous solution.
[0023] The calculation of wind speed in each region includes the wind speed model for region one as follows: ; ; ; ; ; ; ; ; ; ; ; ; In the formula, That's the wind speed in Zone 1. It is a parameter to determine. It is the initial velocity ratio. It is an axial inducing factor. This is the axial thrust coefficient of the wind turbine. Let be the distance from a point on the transverse cross-section of the wake to the wake's axis of rotation. Let be the dimensionless initial wake radius. Let the dimensionless wake radius be the radius of region one. Let the dimensionless wake radius be the radius of region two. , It is a parameter that can be calculated. The dimensionless wake length associated with mechanical turbulence. It is the dynamic wake diffusion coefficient. This represents the axial distance from a point downstream of the wind turbine to the wind turbine plane.
[0024] The wind speed model for Region 2 is as follows: ; ; ; ; It is a parameter that can be calculated. The width of region one, Let be the sum of the widths of region 1 and region 2.
[0025] The wind speed model for Region 3 is as follows: ; ; ; ; In the formula, Let be the dimensionless wake radius of region 3. It is a parameter that can be calculated.
[0026] The calculation of the input speed of each fan includes: ; In the formula, yes Time of the first Input speed at the typhoon turbine It did not take into account the effect of wind turbine overlap. Time of the first Input wind speed at the typhoon turbine This is the total number of wind turbines. It takes into account the wake effect between wind turbine units. Time of the first The first in the wake region of the typhoon turbine Wind speed at the typhoon turbine.
[0027] calculate , At that time, the calculation process for wind speed in each region is used to solve the problem, taking into account the specific location.
[0028] AV wake model schematic diagram as follows Figure 1 As shown, the AV wake model divides the wind turbine wake into three regions: the initial wake region (Region I), the transition region (Region II), and the far-field wake region (Region III). It is the radius of the wind turbine rotor upstream. It is the rotor radius of the downstream wind turbine. It is the initial wake radius. This refers to the radius of the uniform conical flow behind the wind turbine. It is the wake radius of region II. It is the wake radius at the end of region I. It is the wake radius at the end of region II. The width of region one, Let be the sum of the widths of regions one and two. In regions I, II, and III of the above AV wake model, the wake boundary layer growth rate represents the increase in the radius of the wind turbine's projected surface for every 1 meter of wind propagation downwards along the wind turbine axis after passing through it.
[0029] The flowchart for calculating sea surface roughness considering the effects of waves and friction speed is as follows: Figure 2 As shown, the wheel hub height Wind speed at wheel hub height Substituting into the logarithmic wind profile, as shown in equation (5): (5); In the formula, It is the friction speed. It refers to sea surface roughness; Seek and , Relationship; Effective height of sea waves Substituting this into the relationship between sea surface roughness and wind waves, as shown in equation (6): (6); In the formula, It is gravitational acceleration; get and , Relationship; Solving the above two equations together, we get... and Below and .
[0030] A schematic diagram of the wake effect between wind turbine units is shown below. Figure 3 As shown, the wind turbine is installed place, It is the axial distance from a point downstream of the wind turbine to the plane of the wind turbine. It is the radius of the upstream wind turbine rotor, and the area swept by the rotor is... .lie in wind turbine rotor surface The projection surface of the upstream wind turbine at this location The degree of occlusion can be categorized as follows: complete occlusion, partial occlusion, and no occlusion. If... Completely located If the wind turbine is completely blocked, it is considered completely blocked; otherwise, it is considered partially blocked or unblocked. The overlap area of the wind turbines during complete blocking is... Equal to the rotor area of the wind turbine downstream of point X . It did not take into account the effect of wind turbine overlap. Time of the first Input wind speed at the typhoon turbine It takes into account the wake effect between wind turbine units. Time of the first The first in the wake region of the typhoon turbine Wind speed at the typhoon turbine.
[0031] For partial occlusion, it can be divided into different types based on the overlapping area. Figure 4 , Figure 5 The two cases shown. Figure 4 yes In the situation shown in the diagram, yes The part that is covered on top yes The part that is covered on top yes The center of the circle, yes The center of the circle, yes and The upper intersection point, yes to lateral distance, yes and The distance between the centers of the circles. Figure 5 yes The situation.
[0032] The technical process of this invention is as follows: Figure 6 As shown, first refer to Figure 2 The process of obtaining Then, the system reads the position coordinate parameters of the wind turbines in the wind farm, reads the input wind speed and direction of the wind farm, performs coordinate transformation on the wind farm according to the wind direction, calculates the shading coefficient between the wind turbines in combination with the dynamic wake diffusion coefficient, calculates the input speed of each wind turbine, and determines whether the wind parameter sequence has ended. If it has, the system ends; otherwise, it returns to read the input wind speed and direction of the wind farm.
[0033] The following analysis uses a coastal offshore wind farm as an example. The wind farm consists of 60 turbines with a capacity of 8.35MW each, arranged as follows: Figure 7 As shown. The data includes wind speed, wind direction, power, and meteorological information for two years, from January 10, 2023 to August 10, 2025, with a time resolution of 15 minutes. The wind rose diagram for the wind farm area is obtained based on historical data, as shown below. Figure 8 As shown, Figure 8 The wind rose diagram at a height of 10 meters uses 16 azimuth frequencies, with intervals of 0-22.5°, 22.5°-45°, and so on.
[0034] Under normal weather conditions, the sea surface is calm with small waves, having minimal impact on the wind speed of the turbine. However, during extreme weather events, the waves are large and the sea surface roughness is high. Therefore, the following simulation was conducted on a severe extratropical storm surge that occurred in the sea area from April 3rd to 4th, 2023, accompanied by large to giant waves of 3-4.5 meters, to verify the rationality of the wind farm wake model considering the influence of sea waves proposed in this invention.
[0035] During the simulation, the wind speeds of the turbines in the wind farm were calculated for both cases where the sea surface roughness was not considered and cases where it was considered. These calculations were then compared with the measured wind speeds of wind farms on April 3rd and 4th, 2023. The mean absolute error (MAE), root mean square error (RMSE), and coefficient of determination (R²) of the input wind speeds for the 60 turbines are shown in Table 1. The wind speeds of turbine #20 in the wind farm, both cases where sea surface roughness was not considered and cases where it was considered, are compared with the measured wind speeds. Figure 9 As shown.
[0036] Table 1 Three evaluation indicators .
[0037] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for calculating the input wind speed of turbines in offshore wind farms considering the influence of ocean waves, characterized in that, include: S1. Read the position coordinate parameters of the wind turbines in the wind farm, read the input wind speed and wind direction of the wind farm, perform coordinate transformation on the wind farm according to the wind direction, and calculate the shading coefficient between the wind turbines. S2. Calculate the sea surface roughness and friction speed; S3. Calculate the wind speed in each region using the AV wake model; S4. Calculate the input speed of each wind turbine and determine whether the wind parameter sequence has ended. If it has, end the process; otherwise, return to read the input wind speed and direction of the wind farm.
2. The method for calculating the input wind speed of turbines in an offshore wind farm considering the influence of ocean waves, as described in claim 1, is characterized in that... Calculate the shading coefficient between wind turbines include: ； In the formula, It is in the Typhoon power unit The projected area of the wind turbine rotor. No. The area of the wind turbine rotor.
3. The method for calculating the input wind speed of turbines in an offshore wind farm considering the influence of ocean waves, as described in claim 2, is characterized in that... According to the Calculation of the radius of the wind turbine rotor ; The calculation is divided into three cases: If the rotor of an upstream wind turbine does not project onto the downstream wind turbine, it is considered unobstructed. ; The rotor of the upstream wind turbine projects a shadow that completely covers the downstream wind turbine. If it is completely blocked, it is considered as a complete blockage. ; The projection of the upstream wind turbine's rotor onto the downstream wind turbine does not fully cover the downstream wind turbine. If so, it is considered partial occlusion; Partial shading is divided into two cases. When equation (1) is satisfied, the projected area of the wind turbine rotor of the upstream wind turbine at the downstream wind turbine is calculated according to equation (2). （1）； （2）； In the formula, It is the rotor radius of the downstream wind turbine. It is the radius of the wind turbine rotor upstream. It is the distance between the center of the complete projection of the rotor of the upstream wind turbine and the center of the rotor of the downstream wind turbine. It is the distance from the center of the downstream wind turbine's rotor to the upper intersection point of the complete projection of the upstream wind turbine's rotor and the downstream wind turbine's rotor. When equation (3) is satisfied, the projected area of the wind turbine rotor of the upstream wind turbine at the downstream wind turbine is calculated according to equation (4); （3）； （4）。 4. The method for calculating the input wind speed of turbines in an offshore wind farm considering the influence of ocean waves, as described in claim 3, is characterized in that... Determining the sea surface roughness and friction speed includes taking the wheel hub height as an example. Wind speed at wheel hub height Substitution (5): （5）； In the formula, It is the friction speed. It refers to sea surface roughness; Seek and , Relationship; Effective height of sea waves Substitution (6): （6）； In the formula, It is gravitational acceleration; get and , Relationship; Solving the above two equations together, we get... and Below and .
5. The method for calculating the input wind speed of turbines in an offshore wind farm considering the influence of ocean waves, as described in claim 4, is characterized in that... The joint solution includes assuming an initial... , will the initial , and Substitution (5), reverse deduction of new Perform iterative convergence until the latest convergence is achieved. Compared to the last time Less than the threshold, at this time the result is and This is a simultaneous solution.
6. The method for calculating the input wind speed of turbines in an offshore wind farm considering the influence of ocean waves, as described in claim 5, is characterized in that... The calculation of wind speed in each region includes the wind speed model for region one as follows: ； ； ； ； ； ； ； ； ； ； ； ； In the formula, That's the wind speed in Zone 1. It is a parameter to determine. It is the initial velocity ratio. It is an axial inducing factor. This is the axial thrust coefficient of the wind turbine. Let be the distance from a point on the transverse cross-section of the wake to the wake's axis of rotation. Let be the dimensionless initial wake radius. Let the dimensionless wake radius be the radius of region one. Let the dimensionless wake radius be the radius of region two. , It is a parameter that can be calculated. The dimensionless wake length associated with mechanical turbulence. It is the dynamic wake diffusion coefficient. This represents the axial distance from a point downstream of the wind turbine to the wind turbine plane.
7. The method for calculating the input wind speed of turbines in an offshore wind farm considering the influence of ocean waves, as described in claim 6, is characterized in that... The wind speed model for Region 2 is as follows: ； ； ； ； It is a parameter that can be calculated. The width of region one, Let be the sum of the widths of region 1 and region 2.
8. The method for calculating the input wind speed of turbines in an offshore wind farm considering the influence of ocean waves, as described in claim 7, is characterized in that... The wind speed model for Region 3 is as follows: ； ； ； ； In the formula, Let be the dimensionless wake radius of region 3. It is a parameter that can be calculated.
9. The method for calculating the input wind speed of turbines in an offshore wind farm considering the influence of ocean waves, as described in claim 8, is characterized in that... The calculation of the input speed of each fan includes: ； In the formula, yes Time of the first Input speed at the typhoon turbine It did not take into account the effect of wind turbine overlap. Time of the first Input wind speed at the typhoon turbine This is the total number of wind turbines. It takes into account the wake effect between wind turbine units. Time of the first The first in the wake region of the typhoon turbine Wind speed at the typhoon turbine.
10. The method for calculating the input wind speed of turbines in an offshore wind farm considering the influence of ocean waves, as described in claim 9, is characterized in that... calculate , At that time, the calculation process for wind speed in each region is used to solve the problem, taking into account the specific location.