Research On Prognosis Method Of Remaining Lifetime Of Wind Turbine Unit Shafting

Wind energy is one of the most promising energy sources among new energy sources.With the large-scale utilization of wind energy by human beings,the scale of installed wind power in my country has also been expanding,and the research on wind turbines has also been intensified.The wind turbine converts wind energy into rotating mechanical energy through the impeller,and then transmits the mechanical energy to the generator through the transmission system,converts it into electrical energy,and transmits it to the large power grid.In the wind turbine drive system,the unit shafting system composed of the main shaft(low-speed shaft),high-speed shaft and bearings is the most critical component.However,in the operation of wind turbines,the rapid change of wind speed will cause the mechanical torque acting on the impeller to change sharply,and the electromagnetic torque acting on the generator depends on the parameters of the power grid.The stability of the power grid makes the change of electromagnetic torque relatively smooth,which causes the torque imbalance at both ends of the unit shafting.Long-term torque imbalance will increase the failure rate of the wind turbine shaft system.In addition,it is difficult to maintain the transmission system,resulting in higher maintenance costs.The accurate estimation of the remaining life of the wind turbine unit shafting is conducive to the optimization of the maintenance plan,thereby effectively reducing the operating cost.In response to these problems,this paper firstly models the unit shafting degradation process,analyzes the unit shafting crack growth process,and concludes that the degradation process is affected by stress.However,the wind turbine is a dynamic rotating machine,and its motion behavior will cause changes in the stress response,so it is necessary to consider the influence of the rotation of the wind turbine unit shafting on the degradation.Then,according to the main composition and rotation mode of the wind turbine,the three-mass rotation model of the wind turbine unit shafting is established,and the influence of wind speed on the rotation of the unit shafting is explored at the same time.The slow degradation process of the wind turbine unit shafting and the fast rotation process influence each other.The speed of rotation affects the imbalance of the shafting torque,thereby affecting the speed of degradation;conversely,the speed of degradation affects the structural coefficient of the unit shafting,thus affect the rotation process.Therefore,finally,the two models are combined to form a wind turbine unit shafting degradation-torsional vibration coupling model.Through multiple Monte Carlo simulations,fourth-order Runge-Kutta algorithm and rainflow method,the curve of degradation over time can be solved,and the expected expectation and variance of the remaining service life at the current moment can be solved through the curve.At the end of this paper,by adjusting the probability distribution of wind speed,the degradation curve of the unit shafting of wind turbines is obtained,and the influence of the size and distribution of wind speed on the degradation process of the unit shafting is explored.By setting the limit value of the wind speed,the estimated interval of shafting degradation and the estimated interval of remaining life are obtained,which provides theoretical guidance for the formulation of future wind turbine maintenance plans,thereby reducing the operating cost of wind turbines and improving economic benefits.