Dynamic Reliability Evaluation And Life Prediction Of Wind Turbine Drive System Under Multiple Performance Degradation

Wind power energy is an important green energy source.Wind power generators(referred to as wind turbines)are the key equipment in the process of wind power energy production.Its transmission system is composed of multiple parts,of which the more representative ones include transmission shafts,gear boxes,etc.The failure rate of wind turbines is relatively high in wind turbines.The reasons for this situation include:blades,high-speed shafts and other components are subjected to aerodynamic loads for a long time,and their own inertial loads cause fatigue,fracture,and wear.The construction site of wind farms is usually more remote,and the installation location of rotating machinery is higher,the overall volume is larger,and it is more difficult to lift and post-maintain the unit.If it fails,it must be repaired to a higher cost.With the improvement in the performance requirements of various mechanical products,the evaluation method of this stage is difficult to meet the objective requirements of the project in some occasions,and the traditional reliability theory and methods are difficult to deal with the reliability analysis and evaluation of the wind turbine drive system.Key issues such as the time-varying load,the dynamics of the service environment,and the correlation of the failure of various components.In view of this,this topic will take the wind turbine drive system as the research object,consider the relationship between strength degradation and failure phase correlation,develop the system's dynamic reliability analysis and evaluation method,and predict the life of each component.First,the quantitative indicators of reliability,simple reliability system models and failure modes of wind turbine transmission systems are introduced.The model and distribution parameters of the contact stresses of gears,bearings and shafts of the transmission system are explored,and the coefficient of variation in the coefficients is determined.Next,the dynamic reliability of the wind turbine drive system was studied,and the traditional stress-strength model was revised.Based on the revised stress-strength interference model and considering the strength degradation,the dynamic reliability model of the planetary gear transmission system in the wind turbine transmission system is established.Using the improved Monte Carlo method based on BP(Back Propagation)neural network,on the basis of known correlation coefficients,the timevariation fitting curve of each gear component of the transmission system and the overall system reliability index is obtained.The reliability modeling method when subjected to shock load and random load degradation is studied,and the system reliability model of the correlation between sudden failure and degraded failure process is established.The system degradation process of different initial impacts values and failure degradation rate changes is analyzed.Finally,the rain flow counting method is used to count and analyze the stress time history of the wind turbine drive system components.The nominal stress method is used to predict the fatigue life of the transmission system according to Miner linear fatigue cumulative damage theory and Corten-Dolan nonlinear cumulative damage theory.