The Impact Analysis On Non-stationary Extreme Wind Speed Evolution To Wind Turbine

Traditionally,the wind turbines and other infrastructures are designed with a premise of fix climate regime.Therefore,extreme wind of 50-year recurrence interval could be calculated with historical observed metorological data,and thereafter,utilized for planning and design of wind farms.Generally speaking,life cycle of a wind turbine is about 25 years.Once the wind extreme changes during its life cycle for climate change,it could either positively or negatively impact safety of the wind turbines.Therefore,it is highly preferred to evaluate the risk arising from climate change induced variarion in wind extremes.In order to analyze the regional evolution of wind extremes of multi-year recurrence interval,wind data from 1973 to 2012 years in Hailisu,Guaizihu,Hengshan,Huangshan,and Chengshantou are investigated in this thesis.In order to find out the influence of non-stationary trend of wind extreme on the evolution of wind extremes of multi-year recurrence interval over long time scale,Generalized Pareto distribution and non-stationary Generalized Extreme Value distribution are used to calculate the extreme wind of recurrence interval.When the non-stationary wind speed of the extreme wind speed is not considered,in order to analyze the trend of wind extremes,the wind extremes of five stations are divided into 1973-1992 and 1993-2012.Thereafter,residual life function and fit goodness test method are utilized to determine the thresholds in either former or latter 20-year time spans.The method of Independent Storm is used to singled out the maximum extremes from continuous wind extremes to obtain a set of independent threshold samples.The Generalized Pareto distribution model and the tail estimation formula are used to calculate the recurrence interval and the likelihood of wind extremes over designed wind speed to evaluate the regional evolution of extreme wind speed over long time scale.It iss uncovered that Hailisu,Guaizihu and Chengshantou of 50 year recurrence interval and 1 year recurrence level and the likelihood of wind extremes over designed wind extremes declined in the long time scale.The changes of wind extremes have a positive impact on the safety of wind turbines.Hengshan and Huangshan of 50-year recurrence interval and 1-year recurrence interval and likelihood of wind extremes over designed wind extremes increased.Variation of wind extreme could negatively impact safety of wind turbines.It is highly preferred to evaluate evolution of wind extremes over long time-scale with nonstationarity extreme distribution model.The annual extreme value methods,which single out the maximum wind of each year as sample data,are utilized.Thereafter,the annual wind extremes are test for nonstationarity.Finally,the maximum possible wind extreme is calculated with generalized extreme value distribution model to evaluate the influence of nonstationarity of wind extreme on safety of wind turbines.It is uncovered that the wind extreme in Hailisu,Guaizihu and Chengshantou are non-stationary.However,there is no maximum possible wind extreme and it is a positive impact on the safety of wind turbines.The wind extreme of Hengshan is stationary.The wind extremes of Huangshan is non-stationary and the maximum possible wind extreme over there is 41.416 m/s,which is notable larger than the design wind speed of 37.5m/s of wind turbines.It is of negative impact on the safety of wind turbines.