Evaluation method for stability of semi-submersible floating fan in construction stage

Abstract

The invention discloses a semi-submersible floating fan construction stage stability evaluation method, which comprises the following steps: S1, determining an environmental condition for stability evaluation in a floating fan construction stage according to the duration of the floating fan construction stage; s2, collecting historical environment data of a floating fan construction sea area; s3, the maximum inclination angle of the floating type draught fan is calculated; s4, calculating the wind speed of the construction sea area under the exceeding probability of the corresponding wind recurrence period; and S5, checking the stability of the floating fan in the construction stage according to the obtained maximum inclination angle of the floating fan and the wind speed under the exceeding probability of the wind return period corresponding to the construction sea area. According to the method, the stability of the floating fan in the construction stage is evaluated, and excessive conservative design is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of floating wind power, and in particular to a method for evaluating the stability of a semi-submersible floating wind turbine during the construction phase. Background Art

[0002] With the development of offshore wind power, the wind energy resources in offshore waters have been gradually developed, and offshore wind power needs to be developed in deep-water areas with richer wind energy resources. However, with the increase of water depth, the cost of offshore wind power with fixed foundations increases sharply, and the use of floating foundations is a feasible solution. At present, semi-submersible floating wind turbines are widely used, but their construction is a major difficulty.

[0003] Therefore, a stability evaluation method for semi-submersible floating wind turbines during the construction phase is proposed. Summary of the invention

[0004] The purpose of the present invention is to overcome the existing defects and provide a method for evaluating the stability of a semi-submersible floating wind turbine during the construction phase, thereby achieving the evaluation of the stability of the floating wind turbine during the construction phase and avoiding excessive conservatism in design.

[0005] The technical solution to achieve the above purpose is:

[0006] A method for evaluating the stability of a semi-submersible floating wind turbine during construction, comprising:

[0007] Step S1, determining environmental conditions for stability assessment during the construction phase of the floating wind turbine according to the duration of the construction phase of the floating wind turbine;

[0008] Step S2, collecting historical environmental data of the floating wind turbine construction area;

[0009] Step S3, calculating the maximum tilt angle of the floating wind turbine;

[0010] Step S4, calculating the wind speed under the exceedance probability of the corresponding wind return period in the construction sea area;

[0011] Step S5, checking the stability of the floating wind turbine during the construction phase according to the obtained maximum tilt angle of the floating wind turbine and the wind speed under the exceedance probability of the corresponding wind return period in the construction sea area.

[0012] Preferably, in step S1, different environmental conditions are selected for offshore construction of different durations.

[0013] Preferably, in step S2, the historical environmental data includes wind and waves, wherein the waves have a stability of 3 hours, and the collected historical environmental data are given as 3-hour wind and wave data.

[0014] Preferably, step S3 comprises:

[0015] Step S31, using the Geometry module of ANSYS-Workbench (a comprehensive simulation platform mainly used for engineering design and analysis) to establish a model of the floating wind turbine, and using the ANSYS-AQWA hydrodynamic analysis module to calculate the motion amplitude response operator of the floating wind turbine model under the installation condition;

[0016] Step S32, input the collected 3-hour wave environment conditions of the construction sea area in the past year into the ANSYS-AQWA hydrodynamic analysis module, use the PM spectrum for simulation, and combine the calculated motion response amplitude operator of the floating wind turbine model under the installation condition to calculate the maximum tilt angle of the floating wind turbine under the historical 3-hour wave environment conditions;

[0017] Step S33, performing extreme value statistics on the maximum tilt angles under all three-hour wave conditions, arranging them from small to large to form a histogram, and accumulating them to form a distribution function;

[0018] Step S34, using the Weibull function to fit the distribution function of the maximum tilt angle, and obtaining the values ​​of the α and ρ coefficients in the Weibull function;

[0019] Step S35, according to the wave return period determined in step S1, the corresponding exceedance probability is obtained, and the exceedance probability is brought into the distribution function of the Weibull model to obtain the maximum tilt angle under the exceedance probability corresponding to the return period.

[0020] Preferably, in step S32, the PM spectrum expression is:

[0021]

[0022]

[0023] Where exp is the natural logarithm, which is approximately 2.71828; H s is the wave height, T P is the spectrum peak period, and ω is the wave frequency.

[0024] Preferably, in step S34, the distribution function of the Weibull model is:

[0025]

[0026] Where e is the natural logarithm, which is approximately 2.71828; θ is the maximum tilt angle, and α and ρ are coefficients, which are solved by fitting the probability distribution.

[0027] Preferably, in step S35, the exceedance probability calculation formula is:

[0028]

[0029] Where n is the return period in years.

[0030] Preferably, in step S4, the collected 3-hour wind conditions are arranged from small to large to form a histogram, accumulated to form a distribution function, and a distribution model is established using Weibull to obtain the wind speed under the exceedance probability corresponding to the return period; wherein, the distribution function of the wind speed under the exceedance probability corresponding to the wind return period in the construction sea area is fitted using the Weibull function, and the corresponding distribution function of the Weibull model is:

[0031]

[0032] Where, e is the natural logarithm, which is approximately 2.71828; v is the wind speed, and the γ and λ coefficients are solved by fitting the probability distribution of wind speed, and then the maximum wind speed under the exceedance probability corresponding to the return period is obtained.

[0033] Preferably, in step S5, the stability of the floating wind turbine during installation is checked using GHS software, which specifically includes:

[0034] Step S51, importing the floating wind turbine model established in ANSYS-Workbench into the GHS software, inputting the maximum wind speed under the exceedance probability corresponding to the wind return period, and calculating the restoring moment and wind tilting moment of the floating wind turbine at different inclination angles;

[0035] Step S52, when the area A enclosed by the restoring arm corresponding to the maximum tilt angle and the x-axis is greater than 1.3 times the area B enclosed by the wind heel moment and the x-axis, the stability requirement of the floating wind turbine during the installation stage is met; otherwise, the stability requirement is not met.

[0036] The beneficial effects of the present invention are as follows: the present invention determines the environmental conditions for stability assessment during the construction phase of the floating wind turbine according to the duration of the construction phase of the floating wind turbine; collects historical environmental data of the floating wind turbine construction sea area; calculates the maximum inclination angle of the floating wind turbine; calculates the wind speed under the exceedance probability of the wind return period corresponding to the construction sea area; verifies the stability of the floating wind turbine during the construction phase according to the obtained maximum inclination angle of the floating wind turbine and the wind speed under the exceedance probability of the wind return period corresponding to the construction sea area; and then evaluates the stability of the floating wind turbine during the construction phase, thereby avoiding excessive conservatism in the design of the floating wind turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a flow chart of a method for evaluating the stability of a semi-submersible floating wind turbine during the construction phase of the present invention;

[0038] Figure 2is a specific flow chart for calculating the maximum tilt angle of a floating wind turbine in the present invention;

[0039] Figure 3 It is a specific flow chart for checking the stability of the floating wind turbine during the construction phase in the present invention;

[0040] Figure 4 is a schematic diagram of the structure of a floating wind turbine in an embodiment of the present invention;

[0041] Figure 5 is a probability histogram of the maximum tilt angle in the embodiment of the present invention;

[0042] Figure 6 is a distribution function curve diagram of the maximum tilt angle in an embodiment of the present invention;

[0043] Figure 7 is a frequency histogram of the maximum wind speed in an embodiment of the present invention;

[0044] Figure 8 is a frequency distribution function curve diagram of the maximum wind speed in an embodiment of the present invention;

[0045] Fig. 9 Schematic diagram of wind heel moment and restoring moment corresponding to different tilt angles at a wind direction angle of 0° in an embodiment of the present invention;

[0046] Fig.10 Schematic diagram of area A enclosed by the restoring moment at a wind direction angle of 90° in an embodiment of the present invention;

[0047] Fig.11 Schematic diagram of area B enclosed by the wind tilt moment at a wind direction angle of 90° in an embodiment of the present invention;

[0048] Fig.12 Schematic diagram of different wind and wave incident angles in an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0050] The present invention will be further described below in conjunction with the accompanying drawings.

[0051] like Figure 1 As shown, a method for evaluating the stability of a semi-submersible floating wind turbine during the construction phase includes:

[0052] Step S1, determining environmental conditions for stability assessment during the construction phase of the floating wind turbine according to the duration of the construction phase of the floating wind turbine.

[0053] In the embodiment, different environmental conditions are selected for offshore construction of different durations, as shown in Table 1.

[0054] Construction reference time Wind return period Wave return period Within 3 days 5 years March 3-7 days 10 years 1 year 7-30 days 25 years 10 years 1 month - 1 year 75 years 50 years More than one year 100 years 100 years

[0055] Table 1

[0056] Step S2, collecting historical environmental data of the floating wind turbine construction area.

[0057] In an embodiment, the historical environmental data includes wind and waves, wherein the waves have a stability of 3 hours, and the collected historical environmental data are given as 3-hour wind and wave data.

[0058] Step S3, calculating the maximum tilt angle of the floating wind turbine.

[0059] like Figure 2 As shown, step S3 includes:

[0060] Step S31, using the Geometry module of ANSYS-Workbench to establish a model of the floating wind turbine, and using the ANSYS-AQWA hydrodynamic analysis module to calculate the motion amplitude response operator of the floating wind turbine model under the installation condition.

[0061] Step S32, input the collected 3-hour wave environment conditions of the construction sea area in the past year into the ANSYS-AQWA hydrodynamic analysis module, use the PM spectrum for simulation, and combine the calculated motion response amplitude operator of the floating wind turbine model under the installation condition to calculate the maximum tilt angle of the floating wind turbine under the historical 3-hour wave environment conditions.

[0062] In the embodiment, the PM spectrum expression is:

[0063]

[0064]

[0065] Where exp is the natural logarithm, which is approximately 2.71828; H s is the wave height, T P is the spectrum peak period, and ω is the wave frequency.

[0066] Step S33, performing extreme value statistics on all maximum tilt angles under the three-hour wave conditions, arranging them from small to large to form a histogram, and accumulating them to form a distribution function.

[0067] Step S34, using the Weibull function to fit the distribution function of the maximum tilt angle, to obtain the values ​​of the α and ρ coefficients in the Weibull function.

[0068] In the embodiment, the distribution function of the Weibull model is:

[0069]

[0070] Where e is the natural logarithm, which is approximately 2.71828; θ is the maximum tilt angle, and α and ρ are coefficients, which are solved by fitting the probability distribution.

[0071] Step S35, according to the wave return period determined in step S1, the corresponding exceedance probability is obtained, and the exceedance probability is brought into the distribution function of the Weibull model to obtain the maximum tilt angle under the exceedance probability corresponding to the return period.

[0072] In the embodiment, the exceedance probability calculation formula is:

[0073]

[0074] Where n is the return period in years.

[0075] Step S4, calculating the wind speed under the exceedance probability of the corresponding wind return period in the construction sea area.

[0076] In the embodiment, the collected 3-hour wind conditions are arranged from small to large to form a histogram, accumulated to form a distribution function, and a distribution model is established using Weibull to obtain the wind speed under the exceedance probability corresponding to the return period; wherein, the distribution function of the wind speed under the exceedance probability corresponding to the wind return period in the construction sea area is fitted using the Weibull function, and the corresponding distribution function of the Weibull model is:

[0077]

[0078] Where, e is the natural logarithm, which is approximately 2.71828; v is the wind speed, and the γ and λ coefficients are solved by fitting the probability distribution of wind speed, and then the maximum wind speed under the exceedance probability corresponding to the return period is obtained.

[0079] Step S5, checking the stability of the floating wind turbine during the construction phase according to the obtained maximum tilt angle of the floating wind turbine and the wind speed under the exceedance probability of the corresponding wind return period in the construction sea area.

[0080] In the embodiment, the GHS software is used to check the stability of the floating wind turbine during the installation phase, such as Figure 3 As shown, specifically including:

[0081] Step S51, importing the floating wind turbine model established in ANSYS-Workbench into the GHS software, inputting the maximum wind speed under the exceedance probability corresponding to the wind return period, and calculating the restoring moment and wind tilting moment of the floating wind turbine at different inclination angles.

[0082] Step S52, when the area A enclosed by the restoring arm corresponding to the maximum tilt angle and the x-axis is greater than 1.3 times the area B enclosed by the wind heel moment and the x-axis, the stability requirement of the floating wind turbine during the installation stage is met; otherwise, the stability requirement is not met.

[0083] The following will take the installation of a floating wind turbine in a certain sea area as an example to specifically illustrate the specific implementation steps of the present invention.

[0084] In this example, the floating wind turbine impeller diameter is 167m, the blade length is 81.4m, the hub height is 116m, and the tower length is 98m. The main parameters of the floating foundation are as follows: the distance between the column centroids is 175.4m, the side length of the column is 15m, the foundation depth is 30m, and the center of gravity height is 30m. The floating wind turbine model is as follows Figure 4 As shown, it includes: a hub center 1, a tower 2, a column 3 and an impeller 4.

[0085] Step 1: Determine the installation time of the floating wind turbine.

[0086] According to the installation experience of floating wind turbines, the installation and construction time of floating wind turbines is generally 3-7 days. As shown in Table 1, the environmental conditions corresponding to the installation and construction of floating wind turbines are selected as follows: the wind recurrence period is once in 10 years, and the wave recurrence period is once in 1 year.

[0087] Step 2: Collect the wind and wave conditions in the sea area where the floating wind turbines are installed.

[0088] Since the sea waves have a 3-hour stability, the collected historical environmental data are given as 3-hourly wind and wave data.

[0089] Step 3: Calculate the maximum tilt angle during the installation of the floating wind turbine.

[0090] The Geometry module of ANSYS-Workbench is used to build the model of the floating wind turbine, and the ANSYS-AQWA hydrodynamic analysis module is used to calculate the motion amplitude response operator of the floating wind turbine model under installation conditions.

[0091] The collected 3-hour wave environment conditions of the construction sea area in the past year (a total of 2920 groups) were input into the ANSYS-AQWA hydrodynamic analysis module, and the maximum tilt angle of the floating wind turbine under the 3-hour wave environment conditions in the past year was calculated by combining the calculated motion response amplitude operator of the floating wind turbine model under the installation condition. The calculation results are shown in Table 2.

[0092]

[0093] Table 2

[0094] The maximum tilt angle extreme values ​​of all 3-hour wave conditions are counted and arranged from small to large to form a histogram, and the cumulative distribution function is formed, as shown in Table 3 and Figure 5 , 6 shown.

[0095]

[0096]

[0097] Table 3

[0098] The distribution function P(θ) is fitted using Weibull distribution, and the values ​​of coefficients α and ρ are 2.36 respectively.

[0099] and 148.41, that is, the Weibull distribution of the maximum tilt angle of the floating wind turbine during the construction stage is:

[0100]

[0101] The wave return period determined in step 1 is once a year, and the corresponding exceedance probability is:

[0102]

[0103] The corresponding maximum tilt angle under the one-year wave condition is 20.00°.

[0104] Step 4: collect the 3-hour wind data collected in the past year and arrange them into a histogram in ascending order. Use Weibull to establish an extreme value distribution model to obtain the wind speed under the exceedance probability corresponding to the wind return period (10 years), as follows: Figure 7 , 8 shown.

[0105]

[0106] The fitting results show that γ is equal to 2.42 and λ is equal to 244.69, corresponding to the distribution probability of a 10-year return period. The calculated wind speed corresponding to a return period of 10 years is 25.37 m / s.

[0107] Step 5: Check the stability of the floating wind turbine.

[0108] GHS (General HydroStatics) software is used to check the stability of floating wind turbines during the installation phase.

[0109] The floating wind turbine model established in ANSYS-Workbench was imported into the GHS software, and the wind speed corresponding to the exceedance probability of a return period of ten years was input, that is, the wind speed was 25.27m / s, and the stability of the floating wind turbine under different wind directions was verified using the GHS software. The results are shown in Table 4.

[0110]

[0111] Table 4

[0112] The area A enclosed by the restoring arm corresponding to the maximum tilt angle and the x-axis is greater than 1.3 times the area B enclosed by the wind heel moment and the x-axis. The stability of the floating wind turbine during the installation stage meets the requirements. Figure 9-11 are the wind heeling moment and restoring moment corresponding to a wind direction angle of 90°; Fig.12 Schematic diagram of different wind directions and incident angles.

[0113] 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 above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for evaluating the stability of a semi-submersible floating wind turbine during construction, characterized in that: include: Step S1, determining environmental conditions for stability assessment during the construction phase of the floating wind turbine according to the duration of the construction phase of the floating wind turbine; Step S2, collecting historical environmental data of the floating wind turbine construction area; Step S3, calculating the maximum tilt angle of the floating wind turbine; Step S4, calculating the wind speed under the exceedance probability of the corresponding wind return period in the construction sea area; Step S5, checking the stability of the floating wind turbine during the construction phase according to the obtained maximum tilt angle of the floating wind turbine and the wind speed under the exceedance probability of the corresponding wind return period in the construction sea area.

2. The method for evaluating the stability of a semi-submersible floating wind turbine during construction according to claim 1, characterized in that: In step S1, different environmental conditions are selected for offshore construction of different durations.

3. The method for evaluating the stability of a semi-submersible floating wind turbine during construction according to claim 1, characterized in that: In step S2, the historical environmental data includes wind and waves, wherein the waves have a stability of 3 hours, and the collected historical environmental data are given as 3-hour wind and wave data.

4. The method for evaluating the stability of a semi-submersible floating wind turbine during construction according to claim 1, characterized in that: The step S3 comprises: Step S31, using the Geometry module of ANSYS-Workbench to establish a model of the floating wind turbine, and using the ANSYS-AQWA hydrodynamic analysis module to calculate the motion amplitude response operator of the floating wind turbine model under the installation condition; Step S32, input the collected 3-hour wave environment conditions of the construction sea area in the past year into the ANSYS-AQWA hydrodynamic analysis module, use the PM spectrum for simulation, and combine the calculated motion response amplitude operator of the floating wind turbine model under the installation condition to calculate the maximum tilt angle of the floating wind turbine under the historical 3-hour wave environment conditions; Step S33, performing extreme value statistics on the maximum tilt angles under all three-hour wave conditions, arranging them from small to large to form a histogram, and accumulating them to form a distribution function; Step S34, fitting the distribution function of the maximum tilt angle using the Weibull function to obtain the values ​​of the α and ρ coefficients in the Weibull function; Step S35, according to the wave return period determined in step S1, the corresponding exceedance probability is obtained, and the exceedance probability is brought into the distribution function of the Weibull model to obtain the maximum tilt angle under the exceedance probability corresponding to the return period.

5. The method for evaluating the stability of a semi-submersible floating wind turbine during construction according to claim 4, characterized in that: In step S32, the PM spectrum expression is: Where exp is the natural logarithm, which is approximately 2.71828; H s is the significant wave height, T P is the spectrum peak period, and ω is the wave frequency.

6. A method for evaluating the stability of a semi-submersible floating wind turbine during construction according to claim 4, characterized in that: In step S34, the distribution function of the Weibull model is: Where e is the natural logarithm, which takes a value of approximately 2.71828; θ is the maximum tilt angle, and α and ρ are coefficients, which are solved by fitting the probability distribution.

7. A method for evaluating the stability of a semi-submersible floating wind turbine during construction according to claim 6, characterized in that: In step S35, the exceedance probability calculation formula is: Where n is the return period in years.

8. The method for evaluating the stability of a semi-submersible floating wind turbine during construction according to claim 7, characterized in that: In step S4, the collected 3-hour wind conditions are arranged from small to large to form a histogram, accumulated to form a distribution function, and a distribution model is established using Weibull to obtain the wind speed under the exceedance probability corresponding to the return period; wherein, the distribution function of the wind speed under the exceedance probability corresponding to the wind return period in the construction sea area is fitted using the Weibull function, and the corresponding distribution function of the Weibull model is: Where, e is the natural logarithm, which is approximately 2.71828; v is the wind speed, and the γ and λ coefficients are solved by fitting the probability distribution of wind speed, and then the maximum wind speed under the exceedance probability corresponding to the return period is obtained.

9. A method for evaluating the stability of a semi-submersible floating wind turbine during construction according to claim 8, characterized in that: In step S5, the stability of the floating wind turbine during installation is checked using the GHS software, which specifically includes: Step S51, importing the floating wind turbine model established in ANSYS-Workbench into the GHS software, inputting the maximum wind speed under the exceedance probability corresponding to the wind return period, and calculating the restoring moment and wind tilting moment of the floating wind turbine at different inclination angles; Step S52, when the area A enclosed by the restoring arm corresponding to the maximum tilt angle and the x-axis is greater than 1.3 times the area B enclosed by the wind heel moment and the x-axis, the stability requirement of the floating wind turbine during the installation stage is met; otherwise, the stability requirement is not met.

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