计及风电机组齿轮箱疲劳的风电场可靠性评估

RELIABILITY ASSESSMENT OF WIND FARM CONSIDERING FATIGUE OF WIND TURBINE GEARBOX

风电机组的齿轮箱是其机械部分失效造成停机时间最长的零部件,而疲劳是齿轮箱最主要的失效形式。传统风电可靠性模型未考虑齿轮箱疲劳对机组停运的影响,该文提出一种计及齿轮箱疲劳的风电场可靠性评估方法,可直观反映各齿轮箱疲劳损伤程度不同造成的失效率差异,且适用于其他以疲劳为主要失效形式的元件可靠性建模。基于风电机组齿轮箱疲劳分析建立齿轮箱疲劳失效率模型,将疲劳失效状态通过失效率嵌入到常规风电机组Markov模型中,并应用于含有风电场可靠性评估,进而提高评估准确性。研究结果表明风电场投运6 a,疲劳最严重的齿轮箱的疲劳失效率是其理论值3倍以上,导致风电场出力期望评估值高于实际,对于风电渗透率接近30%的系统,电力不足期望值(expected demand not supplied,EDNS)评估误差达到5%以上;另外,对于算例中渗透率仅5.21%的系统,在机组设计年限内随着疲劳损伤累积,EDNS评估误差逐渐达到2.32%。

Fault time of wind turbine caused by gearbox failure is the longest of its mechanical part,where the main failure form of gearbox is fatigue failure.However,in the traditional reliability assessment of wind farm,the failure rate of gearbox is tackled without giving consideration to its fatigue.Therefore,a reliability assessment method of wind farm considering the fatigue of wind turbine gearbox is proposed in this paper,which can reflect the difference of failure rate corresponding to fatigue damage of each gearbox directly and be generally suitable for reliability modeling of other components with fatigue as the main failure form.Based on fatigue analysis of gearbox,the fatigue failure rate model of gearbox is established and inserted into a basic wind turbine Markov model for reliability assessment of wind power system to improve the accuracy of assessment.Results of case studies show that,for a 6 year wind farm,failure rate of the gearbox with the severest fatigue is more than 3 times as high as the theoretical value,resulting in the expected wind farm output higher than the actual value.If the wind power penetration is close to 30%,the evaluation error of EDNS is more than 5%;in addition,for the system in the cases with only 5.21%penetration,the error of EDNS gradually reached 2.32%with fatigue damage accumulation in the designed life of wind turbines.