Reliability Design Of 2.5MW Wind Power Gear Transmission System

With the development of society,the demand for energy has been increasing,but the non-renewable energy such as traditional coal and oil have been exhausted,and the environmental problems are becoming more and more serious.As wind energy is a renewable and clean energy,the wind power industry has enjoyed rapid growth both at home and abroad.With the progress of wind power technology,the power of a single wind turbine is getting larger and larger.At the same time,due to the complex and fluctuating wind load,the operating environment of a wind turbine is harsh,and the maintenance is inconvenient,the reliability and life expectancy of the wind turbine are getting higher and higher.Wind power gear transmission system is a key component of wind turbines,it is used to convert the high torque and low speed of the blade into the low torque and high speed required by the generator.According to statistics,it is one of the components with higher failure rate and longer maintenance time.Therefore,how to design the reliability of a megawatt wind turbine gearbox to ensure that it meets the design life requirements of 20 years while minimizing its size and weight.These have important practical significance and engineering application value.In this paper,2.5MW wind gear transmission system is used as the object,determine its transmission structure,study its reliability calculation method and reliability distribution methodAccording to the measured load spectrum.And establish its reliability design model,optimize the key parameters of the gear.The main research contents are as follows:First of all,the research background and significance of the paper and the status quo of wind power development at home and abroad are briefly described.The research status of reliability design and optimization design of gear transmission system are summarized.Based on this,the main research contents of the dissertation are proposed.Secondly,the main structure of wind power gear transmission system at home and abroad is analyzed.The structure of 2.5MW wind power gear transmission system is determined.The gear ratio calculation and gear torque analysis were carried out.According to the total transmission ratio and the bending strength of the two ring gears,the preallocation of the transmission ratio at all levels is carried out.This laid the foundation for the gear ratio constraints in subsequent reliability optimization design.Thirdly,the failure analysis of wind power gear transmission system is carried out,and themain failure modes and weak links of 2.5MW wind power gear transmission system are determined.Considering the correlation between the eight first-order fixed-shaft gears and the four second-order planetary gears respectively,based on the Copula function,a reliability calculation model of the gear transmission system is established.Using the stress-strength interference theory,based on the load spectrum,the Monte Carlo simulation method is used to establish the reliability calculation model for the contact and bending fatigue strength of variable load gear.These provide the foundation for the reliability optimization design.Fourthly,with the application of analytic hierarchy process(AHP),the reliability allocation of the gears at all levels in the wind power gear transmission system is carried out with the criteria of importance,technical level,maintenance and cost.For the eight first-order fixed-axis gears and the four second-order planetary gears,the reliability of single first-order fixed-shaft gear and single second-order planetary gear is allocated using the Gumbel Copula function under consideration of multiple same gears correlation.Thus,the reliability constraints in reliability optimization design are established.Fifthly,under the constraint of gear reliability,the reliability optimization design model of wind power gear transmission system reliability is established based on the minimum volume of each gear transmission system.The matlab optimization toolbox was used to solve the nonlinear optimization problem.On this basis,considering the impact of operation time on the model parameters,the optimal design was made under the same reliability conditions of wind gear transmission system in different operation phases.This provides an idea for the reliability optimization design of wind gear transmission system when considering performance degradation.Finally,the paper summarizes the research work,and put forward the direction that can be further studied.