STUDY ON SEVERE SEA STATE DESIGN CONDITIONS OF OFFSHORE WIND TURBINES DURING POWER GENERATING

Abstract

 Evaluation of Severe Sea State conditions (SSS) of offshore wind turbines during power generating in the Hibiki-Nada sea-area was investigated in order to set reasonable design of the support structure. First, wind-wave condition was simulated for the past 30 high wave events in order to obtain simultaneous distribution of wind speed and wave heights. Next, using the Inverse First-Order Reliability method (IFORM), the environmental contour defining 50-year return period combinations of mean wind speed and significant wave height was evaluated. The results show that the estimated SSS wave height at the rated wind speed is lower than the 50-year wave height. Furthermore, it was found that more rational and economical design can be realized through further reduction of the design wave height, considering that power generation is not resumed immediately if the wind speed exceeds the cut-out value.