Effect of wind speed distribution and site assessment on pitch bearing loads and life

Abstract

In this paper, the wind speed distribution at thirteen onshore and offshore wind sites has been studied. Different probability distributions are used to estimate the wind speed distribution. Several goodness-of-fit indicators were used to assess the suitability of the fitting. The highest results were achieved by Kernel distribution in both onshore and offshore wind sites. Onshore wind sites did not fit well compared to offshore wind sites. Rayleigh distribution results at onshore wind sites were worse than at offshore wind sites. Onshore and offshore wind distributions result in various load duration distributions in pitch bearing. The concept of life ratio was introduced to compare the long-term fatigue life of the pitch bearing in different wind speed conditions. It is observed that the fatigue life of the pitch bearings in some wind sites is less than that of related IEC classes, and the risk of failure of the pitch bearing before the end of its expected designed fatigue life exists.