Offshore wind farm maximum wind speed analysis method

Abstract

This invention provides a method for analyzing the maximum wind speed of offshore wind farms, comprising the following steps: S1. Determining the study area; S2. Statistically analyzing historical typhoons within the study area and converting all 2-minute wind speeds to 10-minute wind speeds; S3. Calculating the maximum wind speed for each time period using typhoon wind field models; S4. Setting a gale threshold and selecting the maximum wind speed for each time period belonging to the same tropical cyclone to form a maximum wind speed sequence; S5. Using the chi-square and Kolmogorov methods to perform goodness-of-fit tests on the frequency and probability distribution of tropical cyclones in S4. If the test fails, return to step S4 and reset the gale threshold; S6. Using the Poisson-Gumbel method, calculating the maximum wind speed at the first altitude once every N years based on the maximum wind speed sequence; S7. Calculating the representative value of the maximum wind speed at the first altitude once every N years; S8. Using wind shear to estimate the maximum wind speed at the hub height, solving the technical problem of poor representativeness of reference meteorological stations in existing technologies.

Description

Technical Field

[0001] This invention relates to the field of marine engineering technology, and in particular to a method for analyzing the maximum wind speed of offshore wind farms. Background Technology

[0002] In recent years, my country's offshore wind power development has been rapid. The wind resistance ratings of wind turbines vary across coastal provinces, necessitating site-specific assessments to ensure the turbines meet local environmental requirements. A crucial reference indicator for wind turbine wind resistance rating assessment is the 50-year return period maximum wind speed, which refers to the maximum value of the 10-minute average wind speed within a 50-year return period. As offshore wind power projects expand into deeper waters, the representativeness of onshore meteorological stations for these projects is poor, making it difficult to assess the 50-year return period maximum wind speed at different return periods using methods related to strong wind processes at these stations. Therefore, it is necessary to propose a method applicable to different sea areas for assessing the 50-year return period maximum wind speed at the hub height of deep-sea wind farms. Summary of the Invention

[0003] The purpose of this invention is to provide a method for analyzing the maximum wind speed of offshore wind farms, in order to solve the technical problem of poor representativeness of reference meteorological stations in the prior art.

[0004] This invention provides a method for analyzing the maximum wind speed of offshore wind farms, comprising the following steps: S1. Determining the influence range of different sea areas as the study area; S2. Statistically analyzing historical typhoons within the study area, and converting the time interval to obtain the 2-minute wind speed V for all time periods. 2min，i Convert to 10-minute wind speed V 10min，i S3. Calculate the wind speed V at different times in the study area using the typhoon wind field model. 10min，i The maximum value V′ 10min，i S4. Set the strong wind threshold V 阈值 Filter out the wind speeds V at different times belonging to the same tropical cyclone. 10min，i The maximum value V″ 10min，i , so that V″ 10min，i =V′ 10min，i ≥V threshold, constitute the maximum wind speed sequence V″ 10min-max，i V 阈值 S5. Set a full wind threshold for the experience; Use the chi-square and Kolmogorov methods to test the goodness of fit of the tropical cyclone frequency and wind speed probability distributions in S4. If the test fails, return to step S4 and reset the wind threshold V. 阈值 S6. Using the Poisson-Gumbel method, based on the maximum wind speed sequence V″ 10min-max，iCalculate the maximum wind speed at the first altitude once every N years; S7. Calculate the representative value of the maximum wind speed at the first altitude once every N years; S7. Use strong wind shear to estimate the maximum wind speed at the wheel hub height.

[0005] Furthermore, the first height is 10m, and N years is 50 years.

[0006] Furthermore, in S7, the estimated value V of the maximum wind speed occurring once every 50 years at the hub height is calculated. 50，HH The formula for calculating (m / s) is:

[0007]

[0008] Where α is the empirical wind shear index, HH is the wheel hub height, and V is the tidal shear index. 50，10m This represents the maximum wind speed at a height of 10m that occurs once every 50 years.

[0009] Furthermore, the time-distance conversion formula in S2 is as follows: Among them, G 2min / 10min This is the time-moment conversion factor.

[0010] Furthermore, the typhoon wind field models in S3 include the Batts model and the Holland model.

[0011] In the Batts wind field model, the maximum wind speed V′ 10min，i The formula is:

[0012]

[0013] In the formula, f is the Coriolis force parameter, Δp is the central pressure difference, K is an empirical constant with a value of 6.7, and R... max The radius of maximum wind speed is determined using actual recorded values. If no records are available, the Fujita formula is used for estimation.

[0014]

[0015] In the formula, p c The measured air pressure at the simulated point is given by r, the distance between the typhoon center and the simulated point is given by Δp, and p is the air pressure difference at the typhoon center. ∞ The external air pressure,

[0016] In the Holland wind field model, the maximum wind speed V′ 10min，i The formula is:

[0017]

[0018] In the formula, ρ A Where is the air density; B is a shape parameter defined by Holland, used to match pressure curves for different types of cyclones. The recommended value range is 1 < B < 2.5. B can be estimated using the following formula:

[0019]

[0020] This invention provides a method for analyzing the maximum wind speed of offshore wind farms. Different influence ranges are set as study areas in different sea areas. Historical typhoons that actually occurred in the study area are statistically analyzed. The wind speed of each typhoon at each time point of the study point is simulated by combining wind field models. The maximum wind speed at the study point once every 50 years is calculated by the Possion-Gumbel extreme value distribution algorithm. The maximum wind speed at the hub height of the representative point is estimated based on the wind shear index. This solves the technical problem of poor representativeness of the reference meteorological stations in the existing technology. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This embodiment provides a flowchart of a method for analyzing the maximum wind speed in an offshore wind farm.

[0023] Figure 2 This is a schematic diagram of the research area provided in this embodiment;

[0024] Figure 3 This is a schematic diagram of historical typhoon paths for all the areas studied in this embodiment. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] This embodiment provides a method for analyzing the maximum wind speed of an offshore wind farm. Taking the assessment of the maximum wind speed during a 50-year return period at an offshore wind farm in Hainan as an example, the implementation steps of the maximum wind speed analysis method include:

[0027] S1. Determine the impact range of different sea areas as the study area. Taking the center point of a certain offshore wind power project in Hainan as the study point, a radius of R = 300km is set as the study area.

[0028] S2. The wind speed of all historical tropical cyclones passing through the study area was calculated from the 2-minute wind speed V. 2min，iConverted to 10-minute wind speed V 10min，i The conversion formula is as follows: Among them, G 2min / 10min This is the time-moment conversion factor.

[0029] S3. Based on the Batts and Holland models, the historical maximum wind speeds of tropical cyclones at a height of 10m at the study area were calculated, resulting in the following sequence:

[0030]

[0031]

[0032]

[0033] S4. Set the strong wind threshold V 阈值 =20m / s, filter out the historical maximum wind speed sequences of tropical cyclones that are greater than the gale threshold. The filtering criteria include the estimated wind speed V″ of each time period belonging to the same tropical cyclone. 10min，i The maximum value constitutes the historical maximum wind speed sequence of tropical cyclones, V″. 10min-max，i (m / s).

[0034] S5. The chi-square and Kolmogorov methods were used to test the goodness of fit of the tropical cyclone frequency and wind speed probability distributions in the historical tropical cyclone maximum wind speed sequence in S4. Both passed the significance test at a 5% confidence level. The tropical cyclone frequency conforms to the Poisson distribution and the wind speed probability conforms to the Gumbel distribution.

[0035] S6. Using the Poisson-Gumbel joint probability distribution, calculate the 50-year return period maximum wind speed at a height of 10m from the historical tropical cyclone maximum wind speed sequences obtained from the Batts and Holland models, respectively. The results are as follows:

[0036] V 50，10m，Batts =38.0m / s, V 50，10m，Holland = 38.7 m / s.

[0037] S7. Calculate the representative value of the maximum wind speed occurring once every 50 years at a height of 10m:

[0038] V 50，10m =max(V 50，10m，Batts V 50，10m，Holland ) = 38.7 m / s

[0039] S8. Based on the empirical wind shear index α = 0.11 recommended by IEC standards, the representative value of the maximum wind speed at a height of 10m in a 50-year return period, V, is... 50，10m By extrapolating to a wheel hub height of 130.5m, the estimated maximum wind speed at that height, which occurs once every 50 years, is obtained.

[0040] Verification of the effectiveness of the method in this embodiment: Referring to the situation of other projects around this project and the conclusion of the special report on maximum wind speed completed by the National Climate Center for this project area, the estimated maximum wind speed at a height of 130m near this wind farm area is 51.7m / s in 50 years, which is close to the result calculated by the correlation method of the strong wind process according to this embodiment.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; 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; and these 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 analyzing the maximum wind speed in an offshore wind farm, characterized in that, Includes the following steps: S1. Determine the study area; S2. Statistically study historical typhoons within the region, and convert the time interval to obtain the 2-minute wind speed for all times. Convert to 10-minute wind speed ; S3. Calculate the wind speed at different times in the study area using typhoon wind field models. maximum value ; S4. Set the high wind threshold Filter out the wind speeds at different times belonging to the same tropical cyclone. maximum value , making This constitutes the maximum wind speed sequence. ,in Set a maximum wind threshold based on experience; S5. Use the chi-square and Kolmogorov methods to test the goodness of fit of the tropical cyclone frequency and wind speed probability distributions in S4. If the significance test is not passed, return to step S4 and reset the strong wind threshold. ; S6. Using the Poisson-Gumbel method, based on the maximum wind speed sequence Calculate the maximum wind speed at the first altitude, which occurs once every N years. S7. Calculate the representative value of the maximum wind speed that occurs once every N years at the first altitude; S8. Calculate the maximum wind speed at the hub height using strong wind shear; The typhoon wind field models in S3 include the Batts model and the Holland model. In Batts wind field mode, the maximum wind speed The formula is: In the formula, For Coriolis force parameters, For the central pressure difference, This is an empirical constant with a value of 6.

7. The radius of maximum wind speed is determined using actual recorded values. If no records are available, the Fujita formula is used for estimation. In the formula, For the simulated point measured air pressure, The distance between the typhoon center and the simulated point. The pressure difference at the center of the typhoon. The external air pressure, In Holland wind field mode, the maximum wind speed The formula is: In the formula, air density; The shape parameter defined for Holland is used to match pressure profiles for different types of cyclones; a recommended value range is 1 < <2.5, The following formula can be used for estimation: 。 2. The method for analyzing the maximum wind speed of an offshore wind farm according to claim 1, characterized in that, The first height is 10m, and N years is 50 years.

3. The method for analyzing the maximum wind speed of an offshore wind farm according to claim 2, characterized in that, The S8 calculation calculates the estimated maximum wind speed at the hub height that occurs once every 50 years. The formula for calculating (m / s) is: in, This is the empirical wind shear index. For wheel hub height, This represents the maximum wind speed at a height of 10m that occurs once every 50 years.

4. The method for analyzing the maximum wind speed of an offshore wind farm according to claim 1, characterized in that, The time-distance conversion formula in S2 is: ,in, This is the time-moment conversion factor.

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