Research On Fatigue Life Calculation Of Wind Turbine Gearbox Based On Dynamic Model

At present,the total installed capacity of China wind power has ranked the first around the world.Improving the operation and maintenance quality of wind turbines in service units can further reduce the cost of wind power and improve the efficiency of power plants.As an important transmission part of the wind turbine,the gearbox is easily damaged by the long-term random alternating load.In order to assess the fatigue damage of gears,the calculation method of short-term fatigue,the long-term fatigue damage and the additional fatigue damage under extreme wind conditions of gears are discussed in this paper based on the method of dynamic modeling.The main research work includes:firstly,establishing the torsional dynamics model of gearbox,calculating the dynamic response of gearbox model with the Newmark-? method,the bending stress of gears are calculated based on GB/T3480-1997.The stress spectrum with zero mean is obtained by the rain flow counting method and Goodman correction,the calculation method of gear fatigue damage is proposed in this paper based on the linear Miner and nonlinear Corten-Dolan theory.According to the simplified power model of wind turbine,1 Omin's short-term bending fatigue damage is evaluated under different short-term wind conditions,which are simulated by the improved Von Karman wind model.Secondly,the variation tendencies of linear and nonlinear bending cumulative fatigue damage are given based on the statistical characteristics of SCADA data.A gear fatigue design life assessment method based on wind speed and turbulence intensity Weibull distribution is proposed.Finally,the dynamic responses of wind turbines under extreme wind conditions are simulated based on GH Bladed software.Combined with the gearbox dynamics model,the additional damage of gears under extreme wind conditions are evaluated and some references for the stop of wind turbine are provided.According to the calculation method of gear fatigue life based on the dynamic model of wind turbine gearbox,the influences of different wind conditions on the bending fatigue damage of gears are studied.The common wind turbine gear fatigue life calculation method is expanded by the introduction of the nonlinear Corten-Dolan's rule.Considering the historical characteristics of wind speed,a gear fatigue design life calculation method based on the Weibull probability distribution of wind speed and turbulence intensity is proposed to improve the theoretical accuracy of gear fatigue life evaluation.According to the transient response of gears with extreme wind condition under the controlled state of wind turbine,the gear fatigue damage under the continuous impact of extreme gust are evaluated for providing more comprehensive references of wind turbine gearbox's design and maintenance.