Ultimate loads and response analysis of a monopile supported offshore wind turbine using fully coupled simulation

TLDR: In this paper, a subset of ultimate limit state load cases proposed by the IEC 61400-3 standard is systematically analyzed, and the relative severity among the load cases to identify the most critical among them.

About: This article is published in Renewable Energy.The article was published on 2017-02-01 and is currently open access. It has received 45 citations till now. The article focuses on the topics: Ultimate load & Design load.

Figures

Figure 19 - Time-series of a random seed for 12m/s of DLC 1.6a.

Figure 18 – Maximum values of the overturning, flapwise, edgewise moment and rotor thrust for each wind speed bin with 0° yaw misalignment for DLC 1.6a

Figure 20 - Time-series for different variables of DLC 1.6a with a Vref=12m/s for seed 5

Figure 11 - Comparison of reaction of Mx and My at seabed due to ECD+r

Figure 10 - Reaction of the overturning moment due to ECD±r

Figure 9 - Highest wind conditions for Flapwise and Edgewise moment as a function of the yaw angle (0±8°) and the initial azimuth angle of blade 1 (0, 30, 60 and 90°). Top row ECD-r+2 (left) and ECD+r+2 (right), lower row ECD-r (left) and ECD-r+2 (right).

Frequently asked questions

Q1. What contributions have the authors mentioned in the paper "Ultimate loads and response analysis of a monopile supported offshore wind turbine using fully coupled simulation" ?

2 The current design of offshore wind turbines follows mainly the IEC 61400-3 standard. The aim of this paper is to 5 systematically analyse a subset of ultimate limit state load cases proposed by the IEC 61400-3, 6 and understand the relative severity among the load cases to identify the most critical among 7 them. For this study, attention is focused on power production and parked load cases. 

Q2. What has led to the rapid development of renewable energy sources?

Depleting fossil fuel reserves and ever-increasing demand for energy have resulted in rapid 21 development of renewable energy sources. 

Q3. What are the main factors that make the design of offshore wind turbines a challenging exercise?

The combination of the hydrodynamic loading from waves and current, the 23 aerodynamic effects of wind, structural dynamics of the support structure, and the nonlinear 24 effects of the controller together make the design of Offshore Wind turbines a very challenging 25 exercise. 

Q4. What is the effect of the axisymmetry of the 419 structure on the wind-wave?

Note that since the foundation structure is a monopile, the axisymmetry of the 419 structure restricts the wind-wave misalignment combinations. 

Q5. What is the significant wave height for a 1-hour simulation period?

The significant wave 369 height for a 1-hour simulation period may be obtained from the value corresponding to a 3-hour 370 reference period [1] using a conversion factor of 1.09. 

Q6. how much resistance does the rotation towards 0° of the blade create?

This rotation towards 0° of the blade pitch angle creates a significant resistance 255 to the wind force and hence a peak in the overturning moment, the closer to 0° the trough gets, 256 the higher the overturning moment becomes. 

Q7. How many simulations of 40mins can be considered sufficient for studying the chosen responses?

50 Cheng [11] performed a thorough analysis on the effect of the number of wind and wave seeds 51 and simulation length on the maximum response distribution and concluded that 50 52 simulations of 40mins can be considered sufficient for studying the chosen responses. 

Q8. What is the pattern of the three yaw angles for each wind/wave?

The pattern of the three yaw angles is repeated for each wind/wave 428 misalignment, the negative yaw angle leads to higher loads in the three wind/wave conditions 429 followed by the +8° yaw angle. 

Q9. What is the effect of the yaw angle on the flapwise moment?

The initial azimuth angle of blade 1 does not influence the flapwise 310 moment magnitude, although the yaw angle does have an effect, especially in cases where the 311 wind speed is 2m/s above rated.