Three-dimensional wind fields of tropical cyclones for wind turbine structures

An efficient unsteady turbulent wind model is developed to simulate the wind field of tropical cyclones for wind turbines. The method first establishes frequency-domain wind fields, which are then changed to time-domain wind fields using the inverse Fast Fourier Transfer. Finally, interpolation is used to determine the full field unsteady turbulent wind speed. The OpenMP scheme for parallel computing and the skyline method for efficient matrix decomposition sped up 34 times faster than that without these schemes using an eight-core computer. Then, offshore wind turbine (OWT) support structure analyses and designs under International Electrotechnical Commission (IEC) 61400-3 and realistic tropical cyclone loads were performed for three cases. The results indicate that IEC 61400-3 Design Load Cases (DLCs) 2.2, 6.1, and 7.1 control the steel design for the case without tropical cyclone loads, but with such loads, IEC 61400-3 DLC I.2 dominates almost all the steel designs, which was attributed to yaw misalignment. However, actual tropical cyclones may cause worse conditions, especially for the yaw always on the X axis. Nevertheless, this actual tropical cyclone condition does not excessively increase the weight of the steel design, so IEC 61400-3 DLCs I.1 and I.2 are sufficient to ensure the safety of the OWT steel design.