Empirical Correction Ratio and Scale Factor to Project the Extreme Wind Speed Profile for Offshore Wind Energy Exploitation

Abstract

The typhoon-resistant design should be given priority when constructing offshore wind farms in China coastal waters, where typhoons pose serious threats on the safety of offshore structures. A classical power-law model with the specific exponent of ${\text{0.11}}$ has been recommended by the code (IEC 61400-3 2009) to estimate the profile of extreme wind speed versus ${\text{50}}$ years return period. Its use in the typhoon-resistant design of offshore wind turbines in China coastal waters has, however, not been validated. In the present study, a series of full-set three-dimensional meteorology simulations are conducted to provide the artificial typhoon wind fields for the evaluation of code recommendations. The simulations reveal that the classical power-law with the exponent of ${\text{0.11}}$ is inadequate to estimate the extreme wind speed profile over China coastal waters. Based on the simulated typhoon wind fields, an empirical correction ratio and a scale factor are developed to adjust the classical power-law model to estimate the vertical variation of extreme wind speeds with any desired return periods over China coastal waters. More specifically, the correct ratio revises the power-law model to provide more accurate estimates of 50 years return period extreme wind speed profiles while the scale factor projects extreme wind speeds with other desired return periods.